**
Jahresübersicht für das Jahr 2018**

### PRISMA Colloquium

Institut für Physik 13:00 Uhr s.t., Lorentz-Raum 05-127, Staudingerweg 7 |

Kristina Giesel, University Erlangen/Nrnberg | |

## Dy |

### PRISMA Colloquium

Institut für Physik 13:00 Uhr s.t., Lorentz-Raum 05-127, Staudingerweg 7 |

David Marsch, Gttingen | |

## Numerical |

### Seminar about Experimental Particle and Astroparticle Physics (ETAP)

Institut für Physik 12:30 Uhr s.t., Staudingerweg 7, Minkowskiraum |

Anne Schlürscheid, Marco Silvestri, ETAP | |

## Mars-Mission auf dem Prüfstand |

### Seminar Festkörper- und Grenzflächenphysik KOMET - experimentell

Institut für Physik 12:15 Uhr s.t., Newton-Raum, Staudingerweg 9, 1. Stock, Raum 122 (Nebengebäude) |

Joel Cramer, Institut fuer Physik | |

In recent years, the investigation of pure spin currents mediated by magnons (spin waves) has gained increased interest within the spintronics community due to potential advantages over charge-based spin transport [1]. Magnons do not include charge motion and therefore Joule heating, which poses one of the major loss channels in charge-driven devices, is omitted. On that account, magnetic insulators experienced re-gained interest, as within these materials the damping of spin waves is usually low.
In this seminar talk, results with respect to the generation and detection of magnon spin currents within magnetic oxides obtained over the last years will be presented. We shortly introduce different generation schemes of magnon spin currents and discuss the observed temperature and interface dependences [2]. Furthermore, we demonstrate potential applications of magnon spin currents as, for instance, the qualitative determination of materials spin Hall angles [3] or the implementation of a spin valve-like effect [4].
[1] Chumak et al., Nat. Phys. 11, 453 (2015)
[2] Guo et al., Phys. Rev. X 3, 031012 (2016)
[3] Cramer et al., arXiv:1709:01890 (2017)
[4] Cramer et al., arXiv:1707.01082 (2017) |

### Theory of Condensed Matter: Hard Condensed Matter

Institut für Physik, SPICE 14:00 Uhr s.t., Galilei room, 01-128 (Staudinger Weg 9) |

Wojciech Morawiec, Johannes Gutenberg-Universität | |

## Master thesis talk: Specialization seminar |

### Theorie-Palaver

Institut für Physik 14:30 Uhr s.t., MITP seminar room |

Mark Goodsell, LPTHE, Paris | |

In theories defined by high-energy boundary conditions (such as supersymmetry), the Higgs mass is a prediction. On the other hand, in the Standard Model, it is an input, that we need to use to calculate the Higgs quartic coupling, to predict the cubic coupling and also to test for vacuum stability. However, since the Higgs is a scalar, its mass is very sensitive to those of other particles such as the top quark -- or any new physics (hence we have a hierarchy problem) but this also means that we need to calculate as many loop corrections as we can in order to obtain accurate results. Once we reach two loops, however, we find a technical "Catastrophe" associated with the would-be Goldstone Bosons of the W and Z bosons: in Landau gauge their masses vanish, and this leads to infra-red divergences in the amplitudes. I will show how this problem can be avoided for general renormalisable field theories, with applications in the Standard Model and several popular extensions (such as the NMSSM), and describe how the results have been implemented in the public code SARAH.
On the other hand, when we consider that the scale of new physics might be high, we need a method of making predictions for the Higgs mass
(or predictions for the properties of the high-energy theory`s stability)
using the Standard Model as an effective field theory.
These calculations are beset by a similar but worse infra-red problem, in that the infra-red divergences appear already at one-loop order. I will briefly describe some work in progress to show the relation between the two problems and how to solve the latter, so far at one-loop order. |

### Physikalisches Kolloquium

Institut für Kernphysik, Johann Joachim Becher Weg 45 16 Uhr c.t., HS KPH |

Prof. Dr. Ute Ebert, Centrum Wiskunde & Informatica, Amsterdam | |

## Thunderstorms as particle accelerators |

### Quantum Sonderseminar

Institut für Physik 11 Uhr c.t., Medienraum (03-431) des Instituts für Physik, Staudingerweg 7 |

Max Werner (M. Sc.), Institut für Angewandte Physik der TU Darmstadt | |

Different transition scheme of the two photon process of cold rubidium atoms where investigated using a phase-stabilized laser system at 780 nm, which is based on a digital feedback control. Therefor the atoms at the QUIPS experiment (Quantum Information Processing System) where trapped in a optical dipole trap. Additionally a second system at 795 nm was built with revised optical setup and electronic processing. |

### PRISMA Colloquium

Institut für Physik 13:00 Uhr s.t., Lorentz-Raum 05-127, Staudingerweg 7 |

Dr. Miha Mihovilovic, Kernphysik Mainz | |

The discrepancy between the proton charge radius determined by Lamb shift measurements in muonic hydrogen and the radius obtained from elastic scat-tering submits all existing data to scrutiny and questions our understanding of QED. To provide new insight into the problem, several new experiments are underway. They are complemented by extensive theoretical eﬀorts fo-cused on processes inﬂuencing the Lamb shift extractions as well as ways to interpret the form-factor measurements. Features and challenges of these new experiments will be discussed, together with the results of the most recent measurements and prospects for future studies. |

### Seminar about Experimental Particle and Astroparticle Physics (ETAP)

Institut für Physik 12:30 Uhr s.t., Staudingerweg 7, Minkowskiraum |

Friedemann Neuhaus, ETAP | |

## Einfluss der Größe der Verstärkungsregion auf die Verstärkung in Micromegas-Detektoren | |

Master Colloquium |

### Institutsseminar Kern- und Hadronenphysik

Institut für Kernphysik 14 Uhr c.t., HS Kernphysik, Becherweg 45 |

Vahe Sokhoyan, Mainz | |

## Proton radius measurement in the A2 hall |

### Seminar Festkörper- und Grenzflächenphysik KOMET - experimentell

Institut für Physik 12:15 Uhr s.t., Newton-Raum, Staudingerweg 9, 1. Stock, Raum 122 (Nebengebäude) |

Ramon Weber, Institut fuer Physik | |

t b a |

### Theorie-Palaver

Institut für Physik 14:30 Uhr s.t., MITP seminar room |

Kfir Blum, Weizmann Institute, Israel | |

Over the last decade space-borne experiments have delivered new measurements of cosmic-ray (CR) antiprotons and positrons. Where does this antimatter come from? Does it contain evidence for new physics, or exotic astrophysical phenomena? What does it teach us about high-energy processes in the Galaxy? I will describe an attempt to understand cosmic-ray antimatter from first-principles, derive key lessons for astrophysics, and highlight open questions. To conclude I will show how analyses of cosmic-ray composite antinuclei anti-helium and anti-deuterium connect to very recent progress at the LHC and to basic questions of coalescence and flow in high multiplicity hadronic collisions. |

### Physikalisches Kolloquium

Institut für Kernphysik, Johann Joachim Becher Weg 45 16 Uhr c.t., HS KPH |

Prof. Dr. Christophe Salomon, Laboratoire Kastler Brossel, ENS Paris | |

## Atomic clocks |

### PRISMA Colloquium

Institut für Physik 13:00 Uhr s.t., Lorentz-Raum 05-127, Staudingerweg 7 |

Dr. Angela Papa, PSI Villigen, Schweiz | |

Lepton flavor violation (LFV) research is currently one of the most exciting branches of particle physics due to its high sensitivity
to new physics. The observation of neutrino oscillations has clearly demonstrated that neutral lepton flavor is not conserved. This
implies that charged LFV (cLFV) processes, such as the µ+ → e+ ϒ
decay, can also occur in simple extended Standard Model (SM)
versions (i.e. including Dirac neutrinos) which takes into account for neutrino oscillations, although strongly suppressed. On the
other hand, Beyond SM (BSM) extensions strongly enhance the predictions for cLFV branching ratios. Therefore such decays are
ideal probes for new physics.
The MEG experiment at the Paul Scherrer Institut searches for the µ+ → e+ ϒ decay and has completed the data collection at
the end of the 2013. The analysis of the full data set acquired in the period 2009-2013 for a total amount of 7.5 10E14 stopped
muons on the target has been recently completed and it will be presented. Using the full data sample we set a new upper limit on
the branching ratio of this decay of 4.2 10E-13 (90% confidence level): It is a factor 30 improvement over the previous limit set by
the MEGA experiment and also the strongest bound on any forbidden particle decay.
The strong scientific motivation to search for the µ+ → e+ ϒ
decay pushes the collaboration for an upgrade of the MEG experiment:
MEGII. The MEGII experiment is a pre-engineering phase: The status of the MEGII experiment will be given in detail. |

### Seminar über Quanten-, Atom- und Neutronenphysik (QUANTUM)

Institut für Physik 14 Uhr c.t., Lorentz-Raum (05-127), Staudingerweg 7 |

Prof. Dr. Christoph E. Düllmann, Institut für Kernchemie, Universität Mainz, HIM Mainz und GSI/Darmstadt | |

Long-lived transuranium isotopes are central in the study of a variety of hot physics topics. The institute of nuclear chemistry has decade-long expertise and suitable infrastructure for handling these exotic substances, which are often available only in very limited amounts.
In my seminar, I will first discuss current research on thorium-229, in which a long-lived metastable nuclear state at the unusually low excitation energy of around 10 eV exists that is thought to provide a basis for the development of an ultra-precise nuclear clock. This provides the only known example of an atomic nucleus that is accessible using laser-based techniques and is also in the focus of a new joint project among QUANTUM, the Institute of Nuclear Chemistry, and HIM.
I will then briefly describe synthesis and study of nuclear, atomic and chemical properties of elements beyond the actinides, which can be produced at accelerator facilities like GSI Darmstadt at the single-atom-level.
Finally, I will introduce the ECHo-project aiming at the determination of the electron neutrino mass via high-precision calorimetric measurements of the electron capture-spectrum of the artificial radioisotope holmium-163, which is produced and separated in a joint effort between the Institute of Nuclear Chemistry and QUANTUM. |

### THEP Internal Seminar / Exp. Theory Crosstalk

Institut für Physik 12:30 Uhr s.t., THEP Social Room |

Kristiane Novotny, JGU Mainz | |

## Testing the validity of the Randall-Sundrum model with Flavor physics and a Higgs decay |

### Seminar about Experimental Particle and Astroparticle Physics (ETAP)

Institut für Physik 12:30 Uhr s.t., Staudingerweg 7, Minkowskiraum |

Thomas Ehrhardt, ETAP | |

## Non-Standard Interactions in IceCube |

### Theory of Condensed Matter: Hard Condensed Matter

Institut für Physik, SPICE 13:00 Uhr s.t., Media Raum, 03-431 (Staudinger Weg 7) |

André Thiaville, Université Paris-Sud | |

Magnetic skyrmions in ultrathin films require a strong chiral interaction. It is usually provided by the Dzyaloshinskii-Moriya interaction, of the interfacial type for ultrathin films. For single films, in an asymmetrical architecture, it has been shown that the skyrmion size and stability depend extremely sensitively on all sample parameters. Multilayers with typically 10 repetitions of an asymmetrical structure have also being studied, showing robust skyrmions but, as realized recently, a degraded chirality of the domain wall due to magnetostatic effects.
In order to retain, by construction, the benefits of both the magnetostatic interaction and the Dzyaloshinskii-Moriya interaction, we have studied symmetric bilayers of ultrathin films, each in an asymmetric structure. In such a system, we obtain robust skyrmions with a typical 100 nm diameter, show that they can be nucleated by localized current injection using sharp electrodes, measure their current-induced propagation with up to 60 m/s longitudinal velocity, and observe their transverse deflection according to the gyrovector sign. These experiments were performed inside a magnetic force microscope. In addition, high-resolution skyrmion shapes have been systematically mapped using the NV-center magnetic microscope and the measured distributions have been compared to micromagnetic simulations, using a physical description of magnetic disorder based on magnetic layer thickness fluctuations.
[1] Current-induced skyrmion generation and dynamics in symmetric bilayers, A. Hrabec, J. Sampaio, M. Belmeguenai, I. Gross, R. Weil, S.M. Cherif, A. Stashkevich, V. Jacques, A. Thiaville, and S. Rohart, Nat. Commun. 8, 15765 (2017). [2] Skyrmion morphology in ultrathin magnetic films, I. Gross, W. Akhtar, A. Hrabec, J. Sampaio, L. J. Martinez, S. Chouaieb, B. J. Shields, P. Maletinsky, A. Thiaville, S. Rohart, and V. Jacques, arXiv:1709.06027 (2017). |

### Institutsseminar Kern- und Hadronenphysik

Institut für Kernphysik 14 Uhr c.t., HS Kernphysik, Becherweg 45 |

Peter Weidenkaff, Mainz | |

## Analysis of the decay D0 -> Ks K+ K- |

### Physikalisches Kolloquium

Institut für Kernphysik, Johann Joachim Becher Weg 45 Sonderseminar: 16 Uhr c.t., Hörsaal IMB, Ackermannweg 4 |

Prof. Dr. Wolfgang Ketterle, Direktor des Center of Ultracold Atoms (CUA), Massachusetts Institute of Technology (MIT), USA | |

Why do physicists freeze matter to extremely low temperatures? Why is it worthwhile to cool to temperatures which are a billion times lower than that of interstellar space? In this talk, I will discuss new forms of matter, which only exist at extremely low temperatures. With the help of laser beams, gases of ultracold atoms can be transformed into crystals and insulators, and recently into a supersolid which is gaseous, liquid and solid at the same time | |

Sonderseminar |

### Theory of Condensed Matter: Hard Condensed Matter

Institut für Physik, SPICE 14:00 Uhr s.t., Galilei Raum, 01-128 (Staudinger Weg 9) |

Igor Lukyanchuk, Laboratory of Condensed Matter Physics, University of Picardie, France | |

Formation of unusual textures of polarization is imminent for nano-scale ferroelectric samples, films, rods, and granules, where the depolarization surface effects play the crucial role. The topologically protected stability of such textures is coming from polarization vorticity, provided by condition of absence of the energetically-unfavorable depolarization charge. Polarization domains that alternate the surface charge distribution, first proposed by Landau and Kittel in contents of ferromagnetism can be formed in ferroelectric thin films as an effective mechanism to confine the depolarization field to the near-surface layer and diminish the depolarization energy. However, their existence have long been considered as barely possible until the direct theoretical predictions and experimental evidences thin oxide-based superlattices. Very recently we have demonstrated that the effective capacitance of ferroelectric layers with domains is negative. This effect is explained by the opposite orientation of the depolarizing field with respect to the field-induced averaged polarization. This phenomenon is currently considered as the platform for realization of the dissipationfree high performance nano-circuits. Moreover, in sub-THz region the resonance plasmonic effect can be induced by oscillating domain walls and can be suitable for design of the ultrasmall low-energy THz chips. Multi-vortex and skyrmion states can be formed inside ferroelectric cylindrical nano-dots and nanorods to reduce the depolarization energy. We study the stability of such states and demonstrate that the topological class of the most stable topological excitations can be driven by the geometrical and electrical parameters of the system, external field and temperature. We target the multi-domain and topological excitations in FE nanodots as a platform for multivalued logic units, breaking ground for neuromorphic computing.
All interested are cordially welcome! |

### Theorie-Palaver

Institut für Physik 14:30 Uhr s.t., MITP seminar room |

Fabian Ruehle, Oxford University | |

We will start with a pedagogical introduction to machine learning with particular emphasis on the subfield of reinforcement learning. Subsequently, we discuss how
to apply reinforcement learning to the study of a particular class of string theory solutions, so-called Type II intersecting brane worlds. We explain the physical consistency conditions that arise in these constructions, without assuming any prior string theory knowledge. We end by mapping this set of string theory consistency constraints onto an environment that can be analyzed with reinforcement learning and present some preliminary results of the AI exploration of this corner of the string theory landscape. |

### Physikalisches Kolloquium

Institut für Kernphysik, Johann Joachim Becher Weg 45 16 Uhr c.t., HS KPH |

Prof. Dr. Thomas Lippert, Jülich Supercomputing Centre & Universität Wuppertal | |

## Quantum Computing |

### PRISMA Colloquium

Institut für Physik 13:00 Uhr s.t., Lorentz-Raum 05-127, Staudingerweg 7 |

Professor Mark Pearce, KTH Royal Institute of Technology, Stockholm | |

Polarimetry has long been a routine method to probe sources within radio, optical and infra-red astronomy. The application to the X-ray regime has not evolved as rapidly and advances in the field are instead driven by spectroscopy, imaging and timing studies. Many astrophysical X-ray sources are dominated by non-thermal emission with radiation transferred in highly asymmetric systems. A measurement of the linear polarisation of the emitted radiation therefore constitutes a key observable and diagnostic for sources which cannot be spatially resolved. PoGO+ is a balloon-borne hard X-ray polarimeter operating in the 20 - ~200 keV energy band. A one-week long flight was conducted during the Summer of 2016, launching from the Esrange Space Center, Sweden, and landing on Victoria Island, Canada. The design and polarimetric calibration of the PoGO+ instrument will be described and observational results on two bright X-ray sources, the Crab and Cygnus X-1, discussed. |

### Seminar über Quanten-, Atom- und Neutronenphysik (QUANTUM)

Institut für Physik 14 Uhr c.t., Lorentz-Raum (05-127), Staudingerweg 7 |

Dr. Igor Ivanov, CFTP, Instituto Superior Tecnico, Universidade de Lisboa, Portugal | |

I will give an introduction to the topic of vortex electron beams, which emerged a few years ago and has already found applications.
Vortex electron beams are freely propagating electrons with helical wave-fronts and carry intrinsic orbital angular momentum.
These features modify the electron behavior in external fields, as well as radiation and scattering processes, offering new insights into electromagnetic interactions. |

### SFB/TR49/SFB TRR 173 Spin+X-Kolloquium - Seminar experimentelle Physik der kondensierten Materie

SFB/TR49 - Prof. Dr. Elmers 14:00 Uhr s.t., MINKOWSKI-Room, Staudinger Weg 7, 05-119 |

Prof. Dr. Heiko Wende, Universität Duisburg-Essen, Fakultät für Physik | |

In two examples it will be demonstrated how microscopic, element-specific investigations help to advance the fundamental understanding of 1) magnetic molecular hybrid systems and 2) magnetocaloric systems for solid state refrigeration. The former hybrid systems are developed with the vision to promote the on-going process of electronic device miniaturization. For this purpose the tailoring of the magnetic properties in these nanoscale systems is essential. We make use of hybrid systems that consist of a combination of magnetic molecules, graphene and thin films. By means of X-ray absorption spectroscopy and especially XMCD studies the magnetic coupling of paramagnetic molecules or single molecular magnets to ferromagnetic surfaces is analyzed (Fig. 1) [1-4]. These magnetic properties can be tailored by the help of an intermediate layer of atomic oxygen or graphene [5-7]. The fundamental understanding of the relevant interactions in these molecular hybrid systems is possible by combination of experimental and theoretical results utilizing ab initio calculations.
Concerning the magnetocaloric systems 2) it is crucial that ferroic materials allow for a significant adiabatic temperature change induced by realistic electrical and magnetic fields, under pressure and external stress. This approves their use in solid state refrigeration concepts, which offer an energy efficient alternative to the classical gas-compressor scheme [8]. By combination of two independent approaches, nuclear resonant inelastic X-ray scattering (NRIXS) and first-principles calculations in the framework of density functional theory, we demonstrate significant changes in the element-resolved vibrational density of states across the first-order transition from the ferromagnetic low temperature to the paramagnetic high temperature phase of LaFe13−xSix [9,10]. These changes originate from the itinerant electron metamagnetism associated with Fe and lead to a pronounced magnetoelastic softening despite the large volume decrease at the transition. The increase in lattice entropy associated with the Fe subsystem is significant and contributes cooperatively with the magnetic and electronic entropy changes to the excellent magneto- and barocaloric properties.
[1] S. Bhandary et al., Manipulation of spin state of iron porphyrin by chemisorption on magnetic substrates,
Phys. Rev. B 88, 024401 (2013).
[2] H. Wende et al., Substrate-induced magnetic ordering and switching of iron porphyrin molecules,
Nature Materials 6, 516 (2007).
[3] H. Wende, Molecular magnets: How a nightmare turns into a vision, Nature Materials 8, 165 (2009).
[4] A. Candini et al., Spin-communication channels between Ln(III) bis-phthalocyanines molecular nanomagnets and a magnetic substrate, Sci. Rep. 6, 21740 (2016).
[5] M. Bernien et al., Tailoring the Nature of Magnetic Coupling of Fe-Porphyrin Molecules to Ferromagnetic Substrates, Phys. Rev. Lett. 102, 047202 (2009).
[6] S. Bhandary et al., Graphene as a Reversible Spin Manipulator of Molecular Magnets,
Phys. Rev. Lett. 107, 257202 (2011).
[7] S. Marocchi et al., Relay-Like Exchange Mechanism through a Spin Radical between TbPc2 Molecules and Graphene/Ni(111) Substrates, ACS Nano 10, 9353-9360 (2016).
[8] O. Gutfleisch et al., Mastering hysteresis in magnetocaloric materials, Phil. Trans. R. Soc. A 347, 20150308 (2016).
[9] M. Gruner et al., Element-resolved thermodynamics of magnetocaloric LaFe13−xSix,
Phys. Rev. Lett., 114, 057202 (2015).
[10] M. Gruner et al., Moment-Volume Coupling in La(Fe1−xSix)13, Phys. Status Solidi B, 1700465. doi:10.1002/pssb.201700465 (2017). | |

ATTENTION - ROOM CHANGE !!!! |

### THEP Internal Seminar / Exp. Theory Crosstalk

Institut für Physik 12:30 Uhr s.t., Minkowski Raum, Staudinger Weg 7, 05-119 |

Martin Bauer, Matthias Schott, U. Heidelberg, JGU Mainz | |

Bauer, Neubert, Thamm [1704.08207, 1708.00443] |

### Seminar about Experimental Particle and Astroparticle Physics (ETAP)

Institut für Physik 12:30 Uhr s.t., Staudingerweg 7, Minkowskiraum |

Anton Wolf, ETAP | |

## Suche nach Leptoquarks bei ATLAS |

### Institutsseminar Kern- und Hadronenphysik

Institut für Kernphysik 14 Uhr c.t., HS Kernphysik, Becherweg 45 |

Gilberto Colangelo, Bern | |

The decay $eta to 3 pi$ would not happen if isospin were an exact symmetry. Moreover the contribution from the electromagnetic interaction is suppressed, which makes it a unique source of phenomenological information on the quark mass difference $m_u-m_d$.
In this talk I will start with general introduction on the problem of the determination of the light quark masses. I will then present a recent dispersive analysis of this decay which is shown to accurately describe the measured Dalitz plot, both of the charged as well as of the neutral channel of this decay.To understand the relation between the two decay channels at the current level of experimental accuracy it is necessary to take into account also electromagnetic corrections, which has also been done. Finally, we rely on chiral perturbation theory to predict the overall normalization of the amplitude and extract from the
measurement of the rate the value of the QCD contribution to the kaon mass difference, which is proportional to $m_u-m_d$. |

### Seminar Festkörper- und Grenzflächenphysik KOMET - experimentell

Institut für Physik 12:15 Uhr s.t., Newton-Raum, Staudingerweg 9, 1. Stock, Raum 122 (Nebengebäude) |

Marie-Luise Braatz, Insitut fuer Physik | |

Graphene is a remarkable material with numerous extraordinary prop-
erties, among them a high charge carrier mobility. However, it does not
have a band gap, which is necessary for many applications. To modify
graphene in this respect we employ chemical doping which has been
shown to have an effect on the electronic structure [1]. Hence, we use
heteroatom-doping, in particular nitrogen, to modify the structure as
well as the electronic and magnetotransport properties. The amount of
dopants is systematically varied so different dopant concentrations can
be compared. The samples are then analyzed by Raman and electron
microscopy to elucidate the changes in structure. Measuring the mag-
netoresistance at various temperatures and fields allows us to correlate
the structure to the charge transport properties [2].
[1] H. Wang et al., ACS Catal. 2, 781 (2012)
[2] M. Rein et al., ACS Nano 9, 1360 (2015) |

### Theory of Condensed Matter: Hard Condensed Matter

Institut für Physik, SPICE 14:00 Uhr s.t., Galilei room 01-128 (Staudinger Weg 9) |

Babak Seradjeh, Indiana University | |

## Universal fluctuations of Floquet topological invariants at low frequencies |

### Theorie-Palaver

Institut für Physik 14:30 Uhr s.t., MITP seminar room |

Harald Ita, Freiburg University | |

A recent calculation of the planar two-loop five-gluon amplitudes will be discussed.
The amplitudes are obtained in a variant of the generalized unitarity approach suitable for numerical computations. Given the available master integrals arbitrary-precision benchmark values for the amplitudes have been given.
Some of the technical aspects of the approach are addressed in more detail including e.g.
the construction of unitarity-compatible integration-by-parts identities. |

### Physikalisches Kolloquium

Institut für Kernphysik, Johann Joachim Becher Weg 45 16 Uhr c.t., HS KPH |

Prof. Dr. Susanne Mertens, TU München | |

## Probing neutrino mass and searching for sterile neutrinos with KATRIN |

### PRISMA Colloquium

Institut für Physik 13:00 Uhr s.t., Lorentz-Raum 05-127, Staudingerweg 7 |

Prof. M. Aspelmeyer, University of Vienna | |

The quantum optical control of solid-state mechanical devices, quantum optomechanics, has emerged as a new frontier of light-matter interactions. Devices currently under investigation cover a mass range of more than 17 orders of magnitude - from nanomechanical waveguides of some picograms to macroscopic, kilogram-weight mirrors of gravitational wave detectors. This development has been enabled by the insight that quantum optics provides a powerful toolbox to generate, manipulate and detect quantum states of mechanical motion, in particular by coupling the mechanics to an optical or microwave cavity field. Today, 10 years after the first demonstrations of laser cooling of micromechanical resonators, the quantum regime of nano- and micromechanical motion is firmly established.
This opens fascinating perspectives both for applications and for unique tests of the foundations of quantum physics. For example, the availability of quantum superposition states involving massive solid-state objects could enable a completely new class of experiments, in which the source mass character of the quantum system starts to play a role. This addresses directly one of the outstanding questions at the interface between quantum physics and gravity, namely how does a quantum system gravitate?. |

### Seminar über Quanten-, Atom- und Neutronenphysik (QUANTUM)

Institut für Physik 14 Uhr c.t., Lorentz-Raum (05-127), Staudingerweg 7 |

Prof. Dr. Jacob Friis Sherson, Department of Physics and Astronomy, Aarhus University, Denmark | |

Spurred on by rapidly progressing scientific advances and massive investments, quantum technology is finally approaching the time to step out of university labs and into the corporate world. Real-world applications can be realized in two ways: a) by miniaturizing and mass producing quantum technology hardware or b) by creating centralized facilities on which it can be conducted assisted by a globally assessable interface. One example of the latter approach is the IBM quantum experience, which gives access to their quantum computing chip and has ushered in a time when theoreticians can experimentally test and develop their error correction models directly. An open question for the future of research is how to design interfaces that allow for an optimal interaction between human intuition, complex machinery, and the increasingly powerful machine learning algorithms.
In the www.scienceathome.org project, we have recently developed a gamified version of quantum optimization that has so far allowed 250,000 players from around the world to contribute to the research by providing insightful seeds for state-of-the-art optimization algorithms [1]. In recent work [2], we have launched our new open-access quantum research lab: an easily accessible remote interface for our ultra-cold atoms experiment allowing amateur scientists, students, and research institutions world-wide to perform state-of-the-art quantum experimentation. In the first test, a team of theoretical optimal control researchers employ a Remote version of their dCRAB optimization algorithm (RedCRAB), and secondly a gamified democratic-lab interface allowed 600 citizen scientists from around the world to participate in the optimization. In both cases solutions improving previous best performance were found. Within the new www.quatomic.org project, we are attempting to create visual software tools to enable intuition-based theoretical quantum research as well as a non-formalistic but powerful introduction to university level quantum education.
Finally, with a palette of additional games within cognitive science, behavioral economics, and corporate innovation we investigate the general features of individual and collaborative problem solving to shed additional light on the process of human intuition and innovation and potentially develop novel models of artificial intelligence.
[1] JJ Sørensen et al, Nature, 532, 210 (2016) [2] R. Heck et al, arXiv:1709.02230 |

### Seminar about Experimental Particle and Astroparticle Physics (ETAP)

Institut für Physik 12:30 Uhr s.t., Staudingerweg 7, Minkowskiraum |

Alexandra Schulte, ETAP | |

## Measurement of the ttZ Coupling |

### Institutsseminar Kern- und Hadronenphysik

Institut für Kernphysik 14 Uhr c.t., HS Kernphysik, Becherweg 45 |

Johannes Simonis, Mainz | |

The calculation of nuclei as strongly correlated many-body systems based on nucleonic degrees of freedom is an intriguing challenge of nuclear structure theory. Recent developments in the derivation of nuclear forces within chiral effective field theory (EFT), rooted in the symmetries of quantum chromodynamics, and the emergence of systematically improvable many-body methods allow the calculation of light to medium-mass nuclei from chiral two- and three-nucleon forces. Using the in-medium similarity renormalization group (IM-SRG), I will study ground-state energies and charge radii of closed-shell nuclei from He-4 to Ni-78. Extending the calculations to open-shell nuclei in the sd and pf shells with the valence-space IM-SRG allows to study the formation of shell structure, the spectroscopy of exotic nuclei, and the location of the neutron drip line, enabling the comparison to experimental results obtained at rare isotope beam facilities. Moreover, I will present first calculations using the next-generation chiral EFT interactions. |

### Seminar Festkörper- und Grenzflächenphysik KOMET - experimentell

Institut für Physik 12:15 Uhr s.t., Newton-Raum, Staudingerweg 9, 1. Stock, Raum 122 (Nebengebäude) |

Alexander Pfeiffer, Institut fuer Physik | |

The spin Hall effect, observed in non-magnetic heavy metals with large spin orbit coupling such as Platinum
and Tungsten, has received remarkable recent interest as an attractive alternative to electrical spin injection
for the generation of spin currents. To understand the mechanisms behind the spin Hall effect and the
inverse spin Hall effect better, we study multi terminal Pt-Py-Cu lateral spin valves. We generate pure spin
currents into the copper both via the spin Hall effect and electric spin injection from Permalloy and compare
both non-local signals and those generated via the inverse spin Hall effect in one single device. While we
determine the equal temperature dependence for the signals generated by the spin Hall and the inverse spin
Hall effect, changes in the electric spin signal occurs which we explain by different spin injection and absorption
mechanisms. Furthermore, we determine a different interface behaviour, highlighting the importance of the
exact current path for the spin Hall effect. |

### Theorie-Palaver

Institut für Physik 14:30 Uhr s.t., MITP seminar room |

Kasper Larsen, University of Southampton | |

A powerful approach to compute multi-loop Feynman integrals
is to reduce the integrals to a basis of integrals and set up
a first-order linear system of partial differential equations
for the basis integrals. In this talk I will discuss the differential
equations that arise when the loop integrals are parametrized
in Baikov representation. In particular, I give a proof
that dimension shifts (which are undesirable) can always be avoided.
I will moreover show that in a large class of two- and three-loop diagrams
it is possible to avoid integrals with squared propagators in the
intermediate stages of setting up the differential equations. This
is interesting because it implies that the differential equations
can be set up using a smaller set of reductions. |

### Physikalisches Kolloquium

Institut für Kernphysik, Johann Joachim Becher Weg 45 16 Uhr c.t., HS KPH |

Prof. Dr. Katja Matthes, GEOMAR, Kiel | |

## Decadal Climate Variability: the Role of the Stratosphere and the Ocean |

### PRISMA Colloquium

Institut für Physik 13:00 Uhr s.t., Lorentz-Raum 05-127, Staudingerweg 7 |

Dr. Peter G. Thirolf, LMU Garching | |

Todays most precise time and frequency measurements are performed with optical atomic clocks. However, it has been proposed that they could potentially be outperformed by a nuclear clock, which employs a nuclear transition instead of an atomic shell transition. There is only one known nuclear state that could serve as a nuclear clock using currently available technology, namely, the isomeric first excited state of 229Th. Since 40 years nuclear physicists have targeted the identification and characterization of the elusive isomeric ground state transition of 229mTh. Evidence for its existence until recently could only be inferred from indirect measurements, suggesting an excitation energy of 7.8(5) eV. |

### Seminar über Theorie der kondensierten Materie / TRR146 Seminar

K. Binder/ S. Jabbari / A. Nikoubashman / F. Schmid / G. Settanni / T. Speck / M. Sulpizi / P. Virnau 10:30 Uhr s.t., Newtonraum, 01-122, Staudingerweg 9 |

Mihir Khadilkar, Institut für Physik | |

## Self-assembly of mixtures of hard polyhedra: colloids as 'Lego' blocks |

### SFB/TR49/SFB TRR 173 Spin+X-Kolloquium - Seminar experimentelle Physik der kondensierten Materie

SFB/TR49 - Prof. Dr. Elmers Sonderseminar: 11:00 Uhr s.t., MEDIEN-Room, Staudinger Weg 7, 03-431 |

Bernd Beschoten, RWTH Aachen | |

Graphene research has prospered impressively in the past years, and promising applications such as high frequency transistors, THz detectors, magnetic field sensors, flexible optoelectronics, and spintronics applications are waiting for a scalable and cost efficient fabrication technology to produce high-quality, i.e. high-mobility graphene. Although significant progress has been made in chemical vapor deposition (CVD) of "synthetic" graphene on copper foils, typical charge carrier mobilities are significantly lower than what is achieved using exfoliated "natural" graphene. We show that the quality of CVD-grown graphene depends critically on the used transfer process, where the true membrane property of graphene - placing this material right at the crossover from "soft" to "hard" matter - plays a crucial role. We report on an advanced transfer technique that allows making devices with carrier mobilities up to three million cm2/(Vs) thus rivaling exfoliated "natural" graphene. This brings novel electron-optic devices into reach. Furthermore, we demonstrate that dry transfer techniques are also the key to push the spin transport properties of graphene beyond the 10 ns benchmark of the spin lifetime at room temperature. This is of high technological interest as it marks the threshold at which manipulation of spins with electrical high frequency technology becomes feasible. | |

Sonderseminar |

### THEP Internal Seminar / Exp. Theory Crosstalk

Institut für Physik 12:30 Uhr s.t., Minkowski Raum, Staudinger Weg 7, 05-119 |

Mario Reig, IFIC, Valencia | |

Motivated by the idea of Comprehensive Unification, we propose a minimal bottom-up theory with an SO(3) flavor symmetry assembling the three families of matter. This symmetry leads to a golden formula relating charged lepton and down-type quark masses, accounting for the observed hierarchies, and providing a dynamical understanding of the CKM matrix elements. In this framework, the understanding of flavor and the strong CP problem could be closely related. The theory provides an adequate implementation of an anomalous Peccei-Quinn symmetry broken at the family symmetry breaking scale. If the latter is also chosen to coincide with the neutrino seesaw scale we relate four of the major open challenges in particle physics.
arXiv reference:
Reig, Valle, Vaquera-Araujo, Wilczek
https://arxiv.org/pdf/1706.03116.pdf |

### Seminar Festkörper- und Grenzflächenphysik KOMET - experimentell

Institut für Physik 12:15 Uhr s.t., Newton-Raum, Staudingerweg 9, 1. Stock, Raum 122 (Nebengebäude) |

Olena Fedchenko, Institut fuer Physik | |

## Cold Electron Source using a Magneto-Optical Trap |

### Theorie-Palaver

Institut für Physik 14:30 Uhr s.t., MITP seminar room |

Zahra Khajeh Tabrizi, Universidade de Sao Paulo, Brazil | |

The DUNE near detector would offer not only the requisite systematic precision for oscillation studies, but also a generational advance in the precision measurements and unique searches that a neutrino beam can provide. We use neutrino trident events as a way to probe new physics at DUNE. We also use elastic neutrino scattering on electrons as a way to extract the uncertainty of the weak mixing angle. Moreover, we use the trident production, elastic neutrino scattering on electrons and neutrino scattering on nuclei as a way to constrain the operators in the Standard Model Effective Field Theory (SMEFT). | |

Special Seminar! |

### Seminar über Theorie der kondensierten Materie / TRR146 Seminar

K. Binder/ S. Jabbari / A. Nikoubashman / F. Schmid / G. Settanni / T. Speck / M. Sulpizi / P. Virnau 10:30 Uhr s.t., Newtonraum, 01-122, Staudingerweg 9 |

Matteo Campo, Institut für Physik | |

## Collective behaviour of simple models of cells |

### THEP Internal Seminar / Exp. Theory Crosstalk

Institut für Physik 12:30 Uhr s.t., Minkowski Raum, Staudinger Weg 7, 05-119 |

Julien Laux, JGU Mainz | |

Spontaneous symmetry breakings in the early universe can produce gravitational waves in a measurable range, if there is a first order phase transition. These gravitational waves can be detected for example with Pulsar Timing Arrays (PTAs). With the Signal-to-Noise Ratio (SNR) one finds constraints for the detectable range of these arrays. As result one finds, that PTAs are useful for detecting gravitational waves produced by the chiral symmetry breaking at a temperature of 0.1 GeV. Additionally one can use the chi squared in order to distinguish between a signal and a power law background of gravitational waves. | |

Masters Colloquium, THEP Social Room |

### Seminar Festkörper- und Grenzflächenphysik KOMET - experimentell

Institut für Physik Sonderseminar: 10:00 Uhr s.t., MEDIEN-Raum, Staudinger Weg 7, 3. Etage, Raum 03-431 |

Dr. Andrea Vaccaro, LS Instruments AG, Fribourg, Switzerland | |

Light scattering, in its static or dynamic realization, since quite a long time represents the technique of choice for the characterization of diluted colloids. Historically, by the end of the 80s several commercial light scattering instruments were already present on the market, thus fostering a widespread adoption of light scattering techniques in industry and academia. Around the 90s mounting interest in soft matter system generated revived scientific attention to the light scattering technology, specifically around the multiple scattering limitation typically encountered in soft matter system. To this time date two major advancements that took two diametrically opposed directions: suppressing multiple scattering in a traditional light scattering setting and taking a radically new approach by leveraging on multiple scattering itself. This resulted in the development of the multiple scattering suppression by cross-correlation and the Diffusing Wave Spectroscopy (DWS) technologies, respectively. Both these techniques have allowed scientists to study soft matter systems. Yet, due to their added complexity, their implementation has taken time to appear in commercial instruments. In this talk I will review the modulated 3D cross-correlation and the DWS technologies, I will illustrate the main challenges encountered in their implementation in commercial instruments, and, in closing, I will present some typical results of their application to soft matter systems. | |

Sonderseminar |

### Theory of Condensed Matter: Hard Condensed Matter

Institut für Physik, SPICE 14:00 Uhr s.t., Galilei Raum, 01-128 (Staudinger Weg 9) |

Rafael Gonzalez-Hernandez, Universidad del Norte, Barranquilla, Colombia | |

The last decade has seen nearly exponential growth in the science and technology of two-dimensional (2D) materials. Beyond graphene, there is a great variety of new monolayer materials, which can adjust their properties from insulators to superconductors. On the other hand, the stacking of different materials also allows an additional "dimensionality" in the design of new semiconductor and superconductor heterostructures. In this talk, I will discuss recent breakthroughs in the theoretical characterization of two-dimensional materials, including the new 2D nitrides. In particular, starting from the wurtzite phase of gallium nitride (GaN); mechanical, electronic and optical properties of a novel 2D phase (type of graphene, known as g-GaN) is debated. The structural and vibrational stability of g-GaN is presented within the density functional theory (DFT) framework [1]. It is also shown a comparative study to reveal how their physical properties are modified by the dimensionality and doping [2].
[1] P. Giannozzi, et al, J. Phys.: Condens. Matter, (2009), 21, 395502
[2] R. González, W. López-Pérez, Á. González-García, M. Moreno-Armenta, R. González-Hernández, Applied Surface Science, (2018) 433, 1049
All interested are cordially welcome! |

### Seminar über Theorie der kondensierten Materie / TRR146 Seminar

K. Binder/ S. Jabbari / A. Nikoubashman / F. Schmid / G. Settanni / T. Speck / M. Sulpizi / P. Virnau 10:30 Uhr s.t., Newtonraum, 01-122, Staudingerweg 9 |

Dr. Alexandre dos Santos, Physics Department, UFRGS, Porto Alegre, Brazil | |

## Simulation of charged polarizable surfaces |

### Theory of Condensed Matter: Hard Condensed Matter

Institut für Physik, SPICE 14:00 Uhr s.t., Galilei Raum, 01-128 (Staudinger Weg 9) |

Kyoung-Whan Kim, JGU | |

Chiral magnets are ferromagnetic systems that prefer a particular chirality due to the presence of spin-orbit coupling and broken inversion symmetry. They have received considerable attention due to their remarkable properties including spin-orbit torque, the Dzyaloshinskii-Moriya interaction, the existence of magnetic skyrmions, and anisotropic magnetoresistance. Analysis of chiral magnets mostly starts from the Landau- Lifshitz-Gilbert equation with additional terms corresponding to the Dzyaloshinskii-Moriya interaction and the spin-orbit torque. In this formalism, the chirality of equilibrium magnetic properties and that of non- equilibrium electron properties are only taken into account, while that of non-equilibrium magnetic properties are not taken into account.
In this talk, I would like to present the effects of chirality on the excitation and relaxation of magnetization. We examine self-feedback of chiral magnetization dynamics to demonstrate that the gyromagnetic ratio and the Gilbert damping effectively felt by the magnetic moments depend on the chirality of magnetic textures. We illustrate that the chiral renormalization of these parameters is non-negligible for systems with large spin-orbit torque. We also present how one can experimentally measure the chirality renormalized parameters by the domain wall motion in the flow and creep regimes. The qualitative changes from the chiral renormalization indicate that describing the dynamics of the magnetization in chiral magnets requires the chirality of these parameters to be taken into account. |

### Seminar Festkörper- und Grenzflächenphysik KOMET - experimentell

Institut für Physik Sonderseminar: 10:00 Uhr s.t., MEDIEN-Raum, Staudingerweg 7, 3. Stock, Raum 03-431 |

Olga Lozhkina, Department of Physics, Saint Petersburg State University, Russia | |

Quantum dot excitons can serve for quantum logical operations with all-optical control, but obtaining a uniform array of quantum dots is a technical challenge.
Quantum well nanofragmentation leads to the formation of the ordered array of quantum dots. Nanosphere lithography proposes a cheap and scalable way of formation of a close-packed array of pillars on sample surface. This report will present a method of nanosphere lithography as an alternative to electron beam lithography. | |

Sonderseminar |

### Seminar über Theorie der kondensierten Materie / TRR146 Seminar

10:30 Uhr s.t., Newtonraum, 01-122, Staudingerweg 9 |

Prof. Dr. Vladimir Lobaskin, University College Dublin, Ireland | |

## Bionano interactions - key to understanding toxicity and function of nanomaterials |

### THEP Internal Seminar / Exp. Theory Crosstalk

Institut für Physik 12:30 Uhr s.t., Minkowski Raum, Staudinger Weg 7, 05-119 |

Mathias Heiles, JGU Mainz | |

Beside the origin of the axion from the solution for the strong CP problem proposed by Peccin and Quinn, an axion-like particle (ALP) arises from various theories beyond the Standard Model (SM). The interaction of the pseudoscalar, which is a gauge singlet under the SM gauge group, with the SM particles will be described by means of an effective Field Theory (EFT). After a short introduction, the decay of ALPs into SM particles is considered. Following that, three production processes of an ALP together with a Higgs boson, a photon and a Z boson at an e+e- collider will be discussed. These processes probe the parameter space of the ALP couplings to SM fi elds. In addition, the two future colliders FCC-ee and ILC will be compared regarding their investigatable region in the parameter space of the ALP. Furthermore, the production process of an ALP together with a pair of muons is discussed, which gives constraints on the ALP parameter space by means of a search of BaBar for dark Z-bosons. | |

Bachelor's colloquium, THEP Social Room |

### Seminar über Theorie der kondensierten Materie / TRR146 Seminar

10:30 Uhr s.t., Medienraum, 3rd floor, Staudingerweg 7 |

Yoav G. Pollack, Weizmann Institute of Science, Rehovot, Israel | |

## The Static Glass Lengthscale at Low T |

### Seminar zur Vielteilchentheorie

Institut für Physik Sonderseminar: 10:30 Uhr s.t., Seminarraum K (Bau 2/413, 01-525) |

Dr. Giacomo Marmorini, Yukawa Institute for Theoretical Physics, Kyoto | |

Frustrated antiferromagnets are a very rich class of physical systems, in which various new phases of matter are expected to be realized. From a theoretical point of view, however, they present challenging difficulties and typically defy a full quantum treatment, except for specific regions of the parameter space or in one dimension. Employing a combination of analytic and numerical techniques, we determine the ground-state phase diagram of the prototypical spin-1/2 XXZ model on the triangular lattice in a magnetic field and explain the magnetization process of Ba3CoSb2O9. Stimulated by recent evidence of long-range antiferromagnetic order in cold-atom experiments, we explore the thermal phase diagram of the model in the easy-axis region and with transverse field. Away from the highly quantum regime, thermal fluctuations give rise to a nontrivial two-step phase transition through an intermediate phase in which the broken symmetry at zero temperature is partially restored. We discuss how the two transition lines can connect to one of the two BerezinskiiKosterlitzThouless points at zero field. | |

Sonderseminar |

### Seminar zur Vielteilchentheorie

Institut für Physik Sonderseminar: 10:30 Uhr s.t., Seminarraum K (Bau 2/413, 01-525) |

Dr. Tobias Gulden, Technion, Haifa/Israel | |

A key challenge in the search for new non-equilibrium phases of matter is the tendency of closed many-body systems to indefinitely absorb energy from a driving field. Generically this leads to an infinite temperature state where any interesting quantum, and in particular topological, effects are washed out. Here we show that in fact heating can be used as a resource for establishing universal prethermal behavior which exhibits topological phenomena. The prethermalization regime which we consider occurs for low driving frequencies, and persists throughout a long time window. Recently such prethermal states were found in one dimensional topological pumps [Lindner, Berg, Rudner, PRX 2017]. We provide bounds on the lifetimes of states, study different manifestations of universal prethermal behavior in a variety of systems, and discuss probes for observing topological properties. | |

Sonderseminar |

### SFB/TR49/SFB TRR 173 Spin+X-Kolloquium - Seminar experimentelle Physik der kondensierten Materie

SFB/TR49 - Prof. Dr. Elmers Sonderseminar: 14:30 Uhr s.t., MEDIEN-Raum, Staudinger Weg 7, 3. Etage, Raum 03-431 |

Jun-young Kim, Department of Physics, University of York, UK | |

In this talk, I will present recent results on developments of optically-gated Fe/n-GaAs spin injection devices, NiFe/Cu lateral spin valves and antiferromagnetic Heusler alloys including Mn3Ga and Fe2.5VAl. These researches are parts of University of Yorks investigation into new classes of spintronic devices and antiferromagnetic materials.
Firstly, Fe/n-GaAs lateral spin valves were fabricated to probe an optical gating technique of electrically-injected spins in GaAs. More specifically, a circularly-polarised light was used to photoexcite spin-polarised electrons in n-GaAs channel, where the optically- and electrically-injected spins would interact and modulate resultant non-local signals. Preliminary results on these devices will be discussed.
Secondly, all-metallic nano-spin motor devices were investigated, where a lateral spin transfer torque was utilised to manipulate magnetisation direction of a ferromagnetic island. The device consisted of a nanometric NiFe island with two horse-shoe injector contacts for applying spin transfer torque in opposite directions. Visualisation of the island magnetisation by using diamagnetic biogenic guanine crystals obtained from fish scales [1] was also explored.
Lastly, growth and characterisation of antiferromagnetic Heusler alloy compounds, namely Mn3Ga and Fe2.5VAl, will be presented. Atomic compositions and structural properties of the Heusler alloy films, sputter-deposited with a different number of dopant pegs, were studied. The optimised antiferromagnetic Heusler alloy films were characterised as ferromagnet/Heusler alloy bilayer structures, where exchange-bias fields between 15 Oe and 400 Oe were observed at 100 K [2, 3].
This work has been partially supported by UK-EPSRC (EP/M02458X/1) and EU-FP7 HARFIR (NMP3-SL-2013-604398). | |

Sonderseminar |

### Seminar über Theorie der kondensierten Materie / TRR146 Seminar

10:30 Uhr s.t., Newtonraum, 01-122, Staudingerweg 9 |

Jonathan Siebert, Institut für Physik | |

## Critical Behavior of Active Brownian Particles |

### Theory of Condensed Matter: Hard Condensed Matter

Institut für Physik, SPICE 14:00 Uhr s.t., Lorentz-Raum (Staudinger Weg 7, 05-127) |

Alexander Mook, Martin-Luther-Universität Halle-Wittenberg | |

The Topology has conquered the field of condensed matter physics with the discovery of the quantum Hall effect. Since then the zoo of topological materials is steadily increasing. In this talk, I demonstrate how to realize different topological phases with magnons: the magnon pendants to topological insulators as well as Weyl and nodal-line semimetals are presented.
Magnon bulk spectra are characterized by topological invariants, dictating special surface properties. For instance, the bulk bands of topological magnon insulators (TMIs) carry nonzero Chern numbers, causing topological magnon edge states that revolve unidirectionally the sample. Magnon Weyl semimetals possess zero-dimensional band degeneracies acting as source and sink of Berry curvature; at their surface they feature "magnon arcs" connecting the surface projections of Weyl points. Magnon nodal-line semimetals exhibit one-dimensional band degeneracies, i. e., closed loops in reciprocal space. Surface projections of these nodal lines host "drumhead" surface states whose details depend strongly on the surface termination.
Similar to the electronic case, nonzero Berry curvature causes transverse transport, that is, magnon Hall effects. I show how these effects can be quantified by classical spin dynamics simulations of the TMI Cu(1,3-benzenedicarboxylate) and a skyrmionic TMI.
All interested are cordially welcome! |

### SFB/TR49/SFB TRR 173 Spin+X-Kolloquium - Seminar experimentelle Physik der kondensierten Materie

SFB/TR49 - Prof. Dr. Elmers Sonderseminar: 14:15 Uhr s.t., Lorentz-Room, Staudinger Weg 7, 05-127 |

Dr. Alexander Mook, Martin Luther University Halle-Wittenberg, Germany | |

Topology has conquered the field of condensed matter physics with the discovery of the quantum Hall effect. Since then the zoo of topological materials is steadily increasing. In this talk, I demonstrate how to realize different topological phases with magnons: the magnon pendants to topological insulators [1] as well as Weyl [2] and nodal-line semimetals are presented [3].
Magnon bulk spectra are characterized by topological invariants, dictating special surface properties. For instance, the bulk bands of topological magnon insulators (TMIs) carry nonzero Chern numbers, causing topological magnon edge states that revolve unidirectionally the sample [1]. Magnon Weyl semimetals possess zero-dimensional band degeneracies acting as source and sink of Berry curvature; at their surface they feature "magnon arcs" connecting the surface projections of Weyl points [2]. Magnon nodal-line semimetals exhibit one-dimensional band degeneracies, i. e., closed loops in reciprocal space. Surface projections of these nodal lines host "drumhead" surface states whose details depend strongly on the surface termination [3].
Similar to the electronic case, nonzero Berry curvature causes transverse transport, that is, magnon Hall effects [1]. I show how these effects can be quantified by classical spin dynamics simulations of the TMI Cu(1,3-benzenedicarboxylate) [4] and a skyrmionic TMI [5].
[1] H. Katsura et al., Phys. Rev. Lett. 104, 066403 (2010); Y. Onose et al., Science 329, 297 (2010); R. Matsumoto et al., Phys. Rev. Lett. 106, 197202 (2011); L. Zhang et al., Phys. Rev. B 87, 144101 (2013); A. Mook et al., Phys. Rev. B 89, 134409 (2014); A. Mook et al., Phys. Rev. B 90, 024412 (2014)
[2] F.-Y. Li et al., Nature Commun. 7, 12691 (2016); A. Mook et al., Phys. Rev. Lett. 177, 157204 (2016)
[3] A. Mook et al., Phys. Rev. B 95, 014418 (2017)
[4] Chisnell et al., Phys. Rev. Lett. 115, 147201 (2015); Hirschberger et al., Phys. Rev. Lett. 115, 106603 (2015); A. Mook et al., Phys. Rev. B 94, 174444 (2016)
[5] A. Mook et al., Phys. Rev. B 95, 020401(R) (2017) | |

Sonderseminar |

### SFB/TR49/SFB TRR 173 Spin+X-Kolloquium - Seminar experimentelle Physik der kondensierten Materie

SFB/TR49 - Prof. Dr. Elmers Sonderseminar: 14:00 Uhr s.t., MEDIEN-Raum, Staudinger Weg 7, 03-431 |

Prof. Udo Schwingenschloegl, Institut für Physik/Universität Augsburg and King Abdullah University of Science and Technology, Saudi Arabia | |

The presentation will address recent developments related to elemental 2D materials beyond graphene, with a focus on silicene, germanene, and arsenene. Several examples will be discussed in order to illustrate how computational theory based on first-principles calculations can contribute to understanding basic physical and chemical phenomena in 2D condensed matter. Silicene is of particular interest due to its compatibility with established Si technology. Regrettably, strong interaction with common substrates eliminates the Dirac states. Alternative substrates will be analyzed and the effects on silicene evaluated with respect to technological requirements. Germanene attracts more and more attention, because effects of spin-orbit coupling are accessible in contrast to lighter 2D materials. While the same is true for arsenene, the material's strongly buckled structure is not compatible with Dirac physics. Recovering the sp2 bonding, on the other hand, makes it possible to realize unusual properties. | |

Sonderseminar |

### Seminar about Experimental Particle and Astroparticle Physics (ETAP)

Institut für Physik 12:30 Uhr s.t., Staudingerweg 7, Minkowskiraum |

Jan Schäffer, ETAP | |

## Search for supersymmetry with charm jets at ATLAS |

### Seminar Festkörper- und Grenzflächenphysik KOMET - experimentell

Institut für Physik 12:00 Uhr s.t., Newton-Raum, Staudingerweg 9, 1. Stock, Raum 122 (Nebengebäude) |

Prof Elmers, Insitut für Physik | |

## VORBESPRECHUNG / PRELIMINARY DISCUSSION |

### Theory of Condensed Matter: Hard Condensed Matter

Institut für Physik, SPICE 14:00 Uhr s.t., Galilei Raum, 01-128 (Staudinger Weg 9) |

Wojciech Morawiec, Johannes Gutenberg Universität | |

Wojciech Morawiec will give the second talk of his Master thesis. The talk will be about the methodology that he will use during the research phase of his master. |

### Physikalisches Kolloquium

Institut für Kernphysik, Johann Joachim Becher Weg 45 16 Uhr c.t., HS KPH |

Marco Cirelli, LPTHE Jussieu CNRS & Sorbonne Université | |

Dark Matter constitutes more than 80% of the total amount of matter in the Universe: we know it exists, we can guess some of its properties, but we have no idea of what it actually is. This is humbling and it constitutes one of the most pressing issues in cosmology and particle physics today. And indeed the search is not easy: from building ultra-clean experiments within some of the deepest mines on Earth, to installing giant detectors on board the International Space Station, to scrutinizing the products of the most energetic particle collider ever built (the Large Hadron Collider of CERN, near Geneva), many subdisciplines are employed to the purpose. At the same time, theorists are working frantically to build a coherent theory capable of explaining all the observed properties.
The talk will review the basic knowledge available on Dark Matter today and then explore the recent phenomenological and theoretical directions. |

### PRISMA Colloquium

Institut für Physik 13:00 Uhr s.t., Lorentz-Raum 05-127, Staudingerweg 7 |

Andreas Ekström, Chalmers University of Technology, Schweden | |

A precise and accurate theoretical model of the strong interactions between protons and neutrons would provide a key to new knowledge across 20 orders of magnitude; from neutrinos to neutron stars. Despite a century of the finest efforts, a systematic and quantitative description of strongly interacting matter at low energies is still lacking. In this seminar I will present some of the recent developments and future perspectives towards a predictive theory for atomic nuclei. |

### Seminar über Theorie der kondensierten Materie / TRR146 Seminar

Sonderseminar: 10:30 Uhr s.t., Medienraum, 3rd floor, Staudingerweg 7 |

Dr. Peter van Oostrum, University of Natural Resources and Life Science, Vienna | |

Many bacteria interact with surfaces via long (µm) and thin (nm) tethers called fimbriae or pili. These are implicated in pathogenic biofilm formation via both specific and nonspecific bonds. We investigated the interaction of bacteria under shear with surfaces displaying different densities of mannose or hydrophobic domains of similar size as the fimbriae tip. The fimbriae tips form specific bonds with mannose, while only non-specific bonds can form to hydrophobic patches. Digital holographic phase contrast microscopy was implemented to map 3D bacterium trajectories with ~50 nm precision and millisecond time resolution. Simultaneously, shear forces on the bacteria were measured by resolving the laminar flow profile. Our results show transient bonds that are formed and, irrespective of binding specificity, a rolling motion regulated by the binding valency; the higher the number of bound fimbriae, the slower the movement. Upon increased flow, the bacteria slowed down and eventually stopped. This behaviour correlates with a force-induced displacement towards the interface, affording shorter fimbria to also bind to surface domains, thereby increasing the binding valency. Our data suggests that fimbriae allow bacteria to explore different surface niches, responding both to the affinity and number of available contact points, as well as to flow. In contrast to other force-controlled binding mechanisms, e.g. catch-bonds, force actuation of the binding valency is generic; it is not limited to a specific interaction, but merely dependent on general properties such as the number, length distribution and mechanical properties of the tethers. We argue that this effect may be ubiquitous in biology and play an important, but overlooked, role in cellular interactions under physiological conditions. | |

Sonderseminar |

### Seminar über Theorie der kondensierten Materie / TRR146 Seminar

10:30 Uhr s.t., Newtonraum, 01-122, Staudingerweg 9 |

Marcello Guzman, Institut für Physik | |

## Non-ideal rheology and spatial structures of bacterial suspensions in the semidilute regime |

### Seminar about Experimental Particle and Astroparticle Physics (ETAP)

Institut für Physik 12:30 Uhr s.t., Staudingerweg 7, Minkowskiraum |

Jan Weldert, ETAP | |

## Combined Neutrino Mass Hierarchy Analysis from JUNO and PINGU |

### Institutsseminar Kern- und Hadronenphysik

Institut für Kernphysik 14 Uhr c.t., HS Kernphysik, Becherweg 45 |

Torben Ferber, Desy | |

There is overwhelming evidence that we do not understand our Universe. It points to the existence of Dark Matter that makes up a quarter of the Universe. Direct detection experiments and searches at the LHC have focussed on rather heavy Dark Matter particles. A plausible explanation why these experiments have been unsuccessful so far is that Dark Matter particles are actually lighter than the GeV scale and have extremely weak couplings to our Standard Model particles. I will report on searches for light Dark Matter and Axion-Like Particles at Belle II. These particles can be mediators of a new Dark Force or they can be Dark Matter candidates themselves. Belle II in Japan is a flagship experiment at the intensity frontier that will start data taking this year. These searches will profit both from the very large dataset that will be acquired by the Belle II experiment, and from specifically designed triggers for the early running of Belle II. In this talk I will focus on the discovery potential with the first data, and the complementarity with other experiments. |

### Theorie-Palaver

Institut für Physik 14:30 Uhr s.t., MITP seminar room |

Jakub Scholtz, IPPP Durham | |

We revisit constraints on dark matter that is charged under a U(1) gauge group in the dark sector, decoupled from Standard Model forces. We find that the strongest constraints in the literature are subject to a number of mitigating factors. For instance, the naive dark matter thermalization timescale in halos is corrected by saturation effects that slow down isotropization for modest ellipticities. The weakened bounds uncover interesting parameter space, making models with weak-scale charged dark matter viable, even with electromagnetic strength interaction. This also leads to the intriguing possibility that dark matter self-interactions within small dwarf galaxies are extremely large, a relatively unexplored regime in current simulations. Such strong interactions suppress heat transfer over scales larger than the dark matter mean free path, inducing a dynamical cutoff length scale above which the system appears to have only feeble interactions. These effects must be taken into account to assess the viability of darkly-charged dark matter. Future analyses and measurements should probe a promising region of parameter space for this model. |

### PRISMA Colloquium

Institut für Physik 13:00 Uhr s.t., Lorentz-Raum 05-127, Staudingerweg 7 |

David Armstrong, College of William & Mary, USA | |

The QWeak collaboration has used parity-violating elastic electron-proton scattering at very low momentum transfer to precisely measure the Proton´s weak charge. The weak charge is cleanly predicted within the Standard Model, with minimal theoretical uncertainty, however it has never before been measured. Thus, this measurement provides the opportunity for a sensitive search for beyond-the-Standard Model (BSM) physics. The final results for the weak charge will be presented, as well as the extracted values of the vector weak couplings of the up and down quarks, and the weak mixing angle. We will also discuss implications for BSM physics at the multi-TeV energy scale, and the plans for an even more precise measurement at the MESA accelerator. |

### Seminar über Theorie der kondensierten Materie / TRR146 Seminar

10:30 Uhr s.t., Newtonraum, 01-122, Staudingerweg 9 |

Prof. Dr. Michele Cascella, Chemistry Department, University of Oslo | |

I will present a new model of peptide chains based on the hybrid particle field approach [1]. The
intramolecular potential is built on a two-bead coarse grain mapping for each amino acid. A
combined potential for the bending and the torsional degrees of freedom ensures the stabilisation
of secondary structure elements in the conformational space of the polypeptide. The electrostatic
dipoles associated with the peptide bonds of the main chain are reconstructed by a topological
procedure following previous works [2-3] The intermolecular interactions comprising both the
solute and the explicit solvent are treated by a density functional-based mean-field potential.
Molecular dynamics simulations on a series of test systems show how the model is able to
capture all the main features of polypeptides. In particular, homopolymers of different lengths
yield a complex folding phase diagram, covering from the collapsed to swollen state. Moreover,
simulations on models of a four-helix bundle and of an alpha+beta peptide evidence how the
collapse of the hydrophobic core drives the appearance of both folded motifs and the stabilization
of tertiary or quaternary assemblies. Finally, the polypeptide model is able to structurally
respond to the environmental changes caused by the presence of a lipid bilayer. References [1] S. L. Bore, G. Milano, and M. Cascella J. Chem. Theory Comput 2018, 14, 11201130. [2] M. Cascella et al. J. Chem. Theory Comput. 2008, 4, 13781385. [3]D. Alemani et al. J. Chem. Theory Comput. 2010, 6, 315324. |

### THEP Internal Seminar / Exp. Theory Crosstalk

Institut für Physik 13:00 Uhr s.t., Minkowski Raum, Staudinger Weg 7, 05-119 |

Moritz Breitbach, JGU Mainz | |

In 2015, gravitational waves originating from a binary black hole merger were directly detected by the LIGO observatory, a revolutionary discovery which was awarded the 2017 Nobel Prize of Physics. The detection capabilities of planned pulsar timing arrays and space-based observatories herald a new era of astronomical and cosmological research, complementary to current and future collider experiments. Cosmological phenomena such as cosmic strings, the inflation and phase transitions are believed to generate a stochastic gravitational wave background.
We focus on cosmological phase transitions driven by the temperature dependence of the thermodynamical free energy density in the expanding and cooling universe. If such a transition occurs abruptly, i.e. if it is first-order, bubbles of the new phase nucleate, expand and finally collide. These collisions cause anisotropies acting as sources for gravitational radiation. After their production, the gravitational waves propagate through space undisturbed until they might be detected in the form of a redshifted stochastic background today. We present different models that feature dark matter candidates together with first-order phase transitions. | |

Masters defense, Medienraum, 03-431 |

### Seminar über Quanten-, Atom- und Neutronenphysik (QUANTUM)

Institut für Physik 14 Uhr c.t., Lorentz-Raum (05-127), Staudingerweg 7 |

Dr. Tom Wirtz, Luxembourg Institute of Science and Technology (LIST), Belvaux, Luxembourg | |

While Secondary Ion Mass Spectrometry (SIMS) was originally mainly used for depth profiling, the applications gradually shifted towards 2D and 3D imaging as a result of the dramatically improved spatial resolution resulting from the progress made on the instrumental side. As a consequence, new fields of application for SIMS, e.g. in life sciences and nanotechnologies, are emerging.
SIMS can also play a major role when it is used in conjunction with other high-resolution imaging techniques. Due to the ever increasing complexity of devices and the continuously shrinking geometries in materials research, analytical tools allowing a mapping of samples with both excellent resolution and high-sensitivity chemical information are strongly needed [1]. In this context, we developed integrated instruments combining SIMS with Transmission Electron Microscopy [2], Scanning Probe Microscopy [3] and Helium Ion Microscopy [4-6]. The main advantage of this in-situ correlative approach is its capability to analyse the same area of interest of any sample without need of transferring the sample from one instrument to another one, which would result in a number of artefacts ranging from surface contamination to issues with localizing exactly the same ROIs. Moreover, the integrated approach allows fast and multiple interlacing between the different imaging and analysis modes.
In this talk, I will first introduce some basics and challenges of SIMS, and then present the TEM-SIMS, HIM-SIMS and SPM-SIMS concepts and instruments and discuss their performance characteristics. I will then present a number of examples taken from various fields of materials science and life science to show the powerful correlative microscopy possibilities enabled by these new in-situ methods.
References
[1] T. Wirtz, P. Philipp, J.-N. Audinot, D. Dowsett, S. Eswara, Nanotechnology 26 (2015) 434001
[2] L. Yedra, S. Eswara, D. Dowsett, T. Wirtz, Sci. Rep. 6, 28705, 2016
[3] Y. Fleming, T. Wirtz, Beilstein J. Nanotechnol. 6 (2015) 1091-1099
[4] T. Wirtz, D. Dowsett, P. Philipp, Helium Ion Microscopy, ed. G. Hlawacek, A. Gölzhäuser, Springer, 2017
[5] D. Dowsett, T. Wirtz, Anal. Chem. 89 (2017) 8957-8965
[6] P. Gratia et al, J. Am. Chem. Soc. 138 (49) 1582115824, 2016 | |

Vortrag im Rahmen des SFB/TR 49-Kolloquiums |

### THEP Internal Seminar / Exp. Theory Crosstalk

Institut für Physik 14:00 Uhr s.t., Minkowski Raum, Staudinger Weg 7, 05-119 |

Sven Baumholzer, JGU Mainz | |

The standard model of particle physics (SM) fails to explain several phenomena
occurring in high energy physics and cosmology which we want to address in this thesis.
We do so by studying the so called scotogenic model, where we add an second
Higgs doublet and three gauge-singlet neutrinos to the existing SM particle
content. Furthermore, all new particles are supposed to be charged under a new parity
symmetry. Due to this symmetry, SM neutrino masses are generated at one-loop level.
By considering particle masses below the TeV-scale such that the new scalars are
heavier than the singlet neutrinos, will qualify the lightest particle for a viable dark
matter candidate. The baryon asymmetry is generated via a dynamical production
of asymmetries in the lepton sector through a mechanism called leptogenesis.
We study the production of dark matter via two different mechanisms and find
that the correct relic density can be obtained for a wide range of parameters. In
addition, we show that there is a region in the parameter space which leads to
a sizable generation of baryon asymmetries. Finally, we discuss the viability of
simultaneous explanation of both dark matter and baryon asymmetry.
All our findings are critically compared to the constraints coming primarily from
measurements of the primordial abundances of light nuclei, stability of the Higgs
potential and lepton flavor violation processes. | |

Masters defense, Medienraum, 03-431 |

### Seminar about Experimental Particle and Astroparticle Physics (ETAP)

Institut für Physik 12:30 Uhr s.t., Staudingerweg 7, Minkowskiraum |

Daniel Marco Schmitt, ETAP | |

## Electron and Tau Neutrino Identification in IceCube and Gen-2 | |

Bachelor Colloquium |

### Physikalisches Kolloquium

Institut für Kernphysik, Johann Joachim Becher Weg 45 16 Uhr c.t., HS KPH |

1st of May (holiday), --- | |

## --- |

### PRISMA Colloquium

Institut für Physik 13:00 Uhr s.t., Lorentz-Raum 05-127, Staudingerweg 7 |

Kyle Wendt, Lawrence Livermore National Laboratory, US | |

Title:
The quenching puzzle of $beta$-decay
$beta$-decay, where a neutron turns into a proton (or vice versa), is the dominant decay mode of atomic nuclei. This decay process offers a unique window to study the fundamental laws of the universe, to probe the origin and synthesis of the elements of matter, and to understand the evolution of stars.
For more the 4 decades, $beta$-decay has presented a challenging puzzle for theoretical nuclear physics. Theoretical predictions of $beta$-decay rates
of for all but the lightest nuclei are systematically larger than observed rates. This is often attributed to an apparent quenching of the axial-vector coupling constant, $g_a$, in the nuclear medium compared to the decay of the free neutron. The mechanism behind this quenching is a source of controversy and contention, and has thus far eluded first-principles calculation. I will present recent efforts to address this controversy and provide a pathway to solve this decades old puzzle. | |

Talk had to be canceled due to illness! |

### Seminar über Quanten-, Atom- und Neutronenphysik (QUANTUM)

Institut für Physik 14 Uhr c.t., Lorentz-Raum (05-127), Staudingerweg 7 |

Prof. Dr. Mauro Paternostro, School of Mathematics and Physics, Queens University Belfast, Northern Ireland/UK | |

Thermodynamics is an inherently macroscopic theory that describes energy-exchange processes between a system and its environment, and the extraction of work from a driven system. Its traditional formulation requires processes that are quasi-static: at every instant of time, the system should be close to its thermodynamic equilibrium, so that macroscopic thermodynamic quantities (such as pressure, volume, and temperature) could be meaningfully defined.
Yet, the current management of microscopic systems evolving according to the theory of quantum mechanics extends up to the viability of observations of individual trajectories. This opens up the possibility to study non-equilibrium processes that are strongly affected by non-classical (i.e. non-thermal) fluctuations. Which are the implications for thermodynamics? Is it still possible to define and study thermodynamic quantities when we address non-equilibrium processes at the quantum level?
In this talk I will introduce the field of stochastic thermodynamics of quantum processes, illustrating recent theoretical developments, inspired by an information-theoretic approach, and the experimental progresses that have resulted from them. I will address both theoretical proposals (aimed, for instance, at sharpening the fundamental Landauer principle), and experimental endeavours in NMR, optomechanics, and intra-cavity ultra-cold atoms. |

### SFB/TR49/SFB TRR 173 Spin+X-Kolloquium - Seminar experimentelle Physik der kondensierten Materie

SFB/TR49 - Prof. Dr. Elmers 14:15 Uhr s.t., MAINZ-Seminarroom, Staudinger Weg 9, 03-122 |

Dr. Simone Finizio, Paul Scherrer Institut, Villingen, Switzerland | |

Scanning transmission x-ray microscopy (STXM) is a synchrotron-based non-invasive x-ray microscopy technique that can be employed for the investigation of micro- and nanostructured materials. This technique combines a high spatial resolution (for soft x-rays on the order of 10-15 nm) with a high temporal resolution (depending on the filling pattern of the synchrotron light source, either on the order of 10 or 100 ps). Furthermore, thanks to the use of monochromatic x-rays as probing mechanism, element-sensitive imaging can be carried out with STXM. The typical soft x-ray photon energies available (between ca. 100 eV and 2000 eV) allow the investigation of both carbon-based systems (e.g. polymers) and metallic systems (e.g. based on 3d transition metals). Furthermore, the elemental sensitivity of this technique, combined with the x-ray magnetic circular dichroism (XMCD) effect, allows for the investigation of the local magnetic configuration of magnetic materials and multilayers with sub-μm spatial and sub-ns temporal resolution.
In this presentation, an overview of the PolLux STXM endstation of the Swiss Light Source will be given. In particular, the FPGA-based time-resolved acquisition system installed at the PolLux endstation, which allows for the acquisition of time-resolved images with sub-ns temporal resolution, will be presented in detail.
Finally, several examples of projects that employed the instrumentation available at the PolLux endstation, both for Polymer science and for nanomagnetism will be presented. In particular, the time-resolved imaging of vortex and Skyrmion dynamics, and the imaging of magnetic Skyrmions combined with in-situ electrical transport measurements will be presented in detail. |

### Seminar über Theorie der kondensierten Materie / TRR146 Seminar

Sonderseminar: 11:00 Uhr s.t., Newtonraum, 01-122, Staudingerweg 9 |

Markus Bachmayr, University of Bonn | |

## Reduced basis methods, low-rank approximations, and uncertainty quantification | |

Sonderseminar |

### Seminar about Experimental Particle and Astroparticle Physics (ETAP)

Institut für Physik 12:30 Uhr s.t., Staudingerweg 7, Minkowskiraum |

Alfons Weber, Oxford/CERN | |

## Neutrino Oscillations Present and Future |

### Institutsseminar Kern- und Hadronenphysik

Institut für Kernphysik 14 Uhr c.t., HS Kernphysik, Becherweg 45 |

Jannes Nys, Ghent | |

## ￼￼￼Analyticity constraints for hadron spectroscopy |

### Excellence@WORK

MAINZ 12:15 Uhr s.t., MAINZ Seminarraum (Staudingerweg 9, 03.122) |

Dr. Julia Rolnik, Bundeskriminialamt, Biologin | |

## Als Biologin zum BKA - zwischen CSI und Stromberg |

### Theorie-Palaver

Institut für Physik 14:30 Uhr s.t., THEP social room |

Yunfeng Jiang, ETH Zurich | |

In this talk, I will discuss how to apply methods of modern computational algebraic geometry to Bethe ansatz. I will show that algebraic geometry provides natural mathematical languages and powerful tools to understand the structure of solutions of Bethe ansatz equations (BAE). In particular, I will present new methods to count the number of physical solutions with fixed quantum numbers based on Gröbner basis and quotient ring. This method can be applied to study the completeness of Bethe ansatz. I will also discuss an analytical method to compute the sum of on-shell physical quantities over all physical solutions without explicitly solving BAE. This method has important applications in calculating the sum rules of OPE coefficients in N=4 super-Yang-Mills theory. |

### PRISMA Colloquium

Institut für Physik 13:00 Uhr s.t., Lorentz-Raum 05-127, Staudingerweg 7 |

Carlo Rizzo, LNCMI, CNRS, Toulouse, France | |

I will first give the description of a quantum vacuum in the framework of non linear electrodynamics. I will further discuss the phenomena that are predicted because of the fact that non linear electrodynamics allows the photon-photon scattering. Some of these phenomena can be tested by astrophysical observations and/or by laboratory experiments. I will finally conclude giving the state of the art of the Toulouse BMV (Birefringence Magnétique du Vide) experiment whose goal is to observe for the first time vacuum magnetic birefringence. |

### Seminar about Experimental Particle and Astroparticle Physics (ETAP)

Institut für Physik 12:30 Uhr s.t., Staudingerweg 7, Minkowskiraum |

Alexander Basan, ETAP | |

## Energy Asymmetry in Top-Antitop-Jet Events at ATLAS | |

Master Colloquium |

### Institutsseminar Kern- und Hadronenphysik

Institut für Kernphysik 14 Uhr c.t., HS Kernphysik, Becherweg 45 |

Kirill Nikonov, Mainz | |

## Analysis of eta photoproduction with MAID and dispersion relations |

### Seminar Festkörper- und Grenzflächenphysik KOMET - experimentell

Institut für Physik 12:15 Uhr s.t., Newton-Raum, Staudingerweg 9, 1. Stock, Raum 122 (Nebengebäude) |

Steinn Y. Agustsson, Institut für Physik | |

## CANCELLED |

### Theory of Condensed Matter: Hard Condensed Matter

Institut für Physik, SPICE 14:00 Uhr s.t., Galileo room, 01-128 (Staudinger Weg 9) |

Lykourgos Bougas, Helmholtz-Institute, Johannes Gutenberg University, Mainz | |

Chirality is a fundamental property of life, making chiral sensing and analysis crucial to numerous scientific and technological fields, ranging from fundamental physics to drug development and food monitoring. The measurement of chiral optical rotation and circular dichroism is the most widely used method for chirality sensing, but chiral signals are typically very weak and their measurement is limited by larger time-dependent backgrounds and by imperfect and slow subtraction procedures. Well present a novel cavity-enhanced polarimetric scheme that allows for: (a) the enhancement of the chiral signal by the number of the cavity passes (typically »1000); (b) the suppression of birefringent backgrounds; and (c) the ability to reverse the sign of the chiral signal rapidly, allowing for the isolation of the chiral signal from backgrounds and, therefore, its absolute measurement. Well present measurements of optical rotation for chiral molecules within achiral, open-air, environments, and for chiral liquids in the evanescent wave produced by total internal reflection at a prism surface. Well finally discuss different applications of our technique with larger focus on atmospheric studies, particularly the real-time monitoring of chiral volatile organic compounds in forests, and biomolecular dynamics.
All interested are cordially welcome! |

### Theorie-Palaver

Institut für Physik 14:30 Uhr s.t., THEP social room |

Christoph Englert, Glasgow University | |

While the Higgs and top quark phenomenology programmes are well underway, direct signs for new physics beyond the Standard Model remain elusive. In this talk, I will discuss the implications of recent LHC Higgs measurements and how differential distributions will improve the sensitivity to new interactions beyond the Standard Model in the light of expected uncertainties. Special attention will be devoted to the particular case of multi-Higgs production as a direct probe of the Higgs bosons self-interactions. While the expected sensitivity to this parameter is expected to be low at the LHC, it provides a key motivation for a potential future 100 TeV collider. |

### Physikalisches Kolloquium

Institut für Kernphysik, Johann Joachim Becher Weg 45 16 Uhr c.t., HS KPH |

Can-Ming Hu, University of Manitoba, Canada | |

This talk aims to provide an introduction to this new frontier of condensed matter physics to researchers working in magnetism, spintronics, quantum information, and microwave technologies. The talk starts with a historical review, tracing this new field back to some of the most courageous work in the history of magnetism, spintronics, cavity quantum electrodynamics, and polaritons. Recent experiments focusing on the development of new cavity-mediated techniques, such as coupling of magnetic moments, distant manipulation of spin current, qubit-magnon coupling, and conversion between optical and microwave photons, will be highlighted. |

### PRISMA Colloquium

Institut für Physik 13:00 Uhr s.t., Lorentz-Raum 05-127, Staudingerweg 7 |

Andreas Crivellin, PSI Villigen | |

In this talk I discuss the recent experimental hints for Lepton Flavour Universality Violation and their implications for New Physics models. While in the Standard Model (SM) of particle physics all charged leptons (electrons, muons and taus) interact in the same way (i.e. Lepton Flavour Universality is satisfied), experimental hints for Lepton Flavour universality Violation accumulated within recent years. These hints therefore suggest the existence of New Physics with a radically new behaviour compared to the SM. After reviewing the experimental situation, I discuss the implications for theoretical models of physics beyond the SM. As it turns out, leptoquarks (new hypothetical particles which couple to leptons and quarks simultaneously) can explain all the anomalies and I highlight the prospects of finding these particles in direct and indirect searches. |

### Seminar über Theorie der kondensierten Materie / TRR146 Seminar

10:30 Uhr s.t., Newtonraum, 01-122, Staudingerweg 9 |

Saikat Chakraborty, Institut für Physik | |

## Ferromagnetic Ordering in 3D Ising Model at Zero Temperature: Surprises in structure, growth and relaxation |

### Seminar über Quanten-, Atom- und Neutronenphysik (QUANTUM)

Institut für Physik 14 Uhr c.t., Lorentz-Raum (05-127), Staudingerweg 7 |

Prof. Dr. Markus Müller, Department of Physics, Swansea University, Swansea, Wales/UK | |

Quantum computers hold the promise to allow one to solve important problems that cannot be efficiently treated on classical computers. To date, the construction of a fault-tolerant quantum computer remains a fundamental scientific and technological challenge, due the influence of unavoidable noise which affects the fragile quantum states. In our talk, we first introduce basic concepts of topological quantum error-correcting codes, which allow one to protect quantum information during storage and processing by distributing logical quantum information over quantum many-body spin systems. We then discuss progress on experimental quantum error correction, in particular the realisation of a minimal topological color code with trapped ions, which for the first time demonstrated basic quantum computations on an encoded qubit. In the second part, I will focus on fault-tolerant quantum computing in trapped-ion quantum processors, in which scalability is achieved by shuttling ions between various trapping regions and by a rich toolbox of ion-crystal reconfiguration techniques. Here, I will present recent theory work of our group on resource-efficient and fault-tolerant protocols to control single and coupled logical qubits of increasing size and robustness. |

### Seminar Festkörper- und Grenzflächenphysik KOMET - experimentell

Institut für Physik 09 Uhr c.t., Medien Raum, Staudingerweg 7, 3. Stock, Raum 03-431 |

Daniel Waas, IFW Dresden | |

This presentation deals with the investigation of organic interfaces by means of photoelectron spectroscopy in the valence band as well as in the core level region. Charge transfer across the interfaces and changes in the electronic properties were investigated. The systems consisting of MnPc and F6TCNNQ show a very strong charge transfer. The oxidation of the Mn in the MnPc, the reduction of the F6TCNNQ as well as the occupation of the F6TCNNQ-LUMO-structure and the depopulation of the MnPc-HOMO-structure are evidence for this conclusion. At the interfaces of F16CoPc and pentacene a weak charge transfer was measured. A reduction of the central Co atom was observed as well as a low occupation of the F16CoPc-LUMO. Interfaces consisting of F6TCNNQ and pentacene form a partial charge transfer complexl. The first monolayer of each material at the interface reveals different behavior in the core level as well as in the valence band compared to the other layers. An occupation of the F6TCNNQ-LUMO could not be observed. These observations could be explained by a partial charge transfer connected with a charge transfer complex and creation of supramolecular hybrid orbitals. |

### Seminar zur Vielteilchentheorie

Institut für Physik 10:15 Uhr s.t., Seminarraum K (Bau 2/413, 01-525) |

Dr. Julian Großmann, Technische Universitt Hamburg | |

Sturm-Liouville oscillation theory is around 200 years old and goes back to Charles-Franois Sturm and Joseph Liouville. They considered eigenvalue problems of some particular continuous differential equations. In this talk, this oscillation theory is studied for a discrete analogous case, so-called Jacobi operators or Jacobi matrices. The entries of this matrix can even given by elements of a unital C*-algebra, for example linear operators on a Hilbert space. New results in this general framework are developed and eventually applied to certain high-dimensional random Schrdinger operators. A typical physical example is the d-dimensional Anderson model. It is shown that the integrated density of states of the Jacobi operator is approximated by a certain generalised winding number. These results are based on arXiv:1706.07498. |

### Excellence@WORK

MAINZ 12:15 Uhr s.t., MAINZ Seminarraum (Staudingerweg 9, 03.122) |

Dr. Niklas Loges, BASF SE, Chemiker | |

## Vom Chemiker zum Manager |

### Physikalisches Kolloquium

Institut für Kernphysik, Johann Joachim Becher Weg 45 16 Uhr c.t., HS KPH |

Francesca Ferlaino, Institut für Experimentalphysik, Universität Innsbruck und IQOQI, Innsbruck (Austria) | |

With the tremendous advances in cooling and manipulation techniques, ultracold atomic gases have consolidated themselves as an ideal system to address fundamental questions in quantum few- and many-body physics. Recently, we have reached Bose-Einstein condensation and Fermi degeneracy with ultracold Erbium atoms. This exotic atomic species combines unusually rich atomic spectra and a large magnetic moment.
In the quantum regime, bosonic Er atoms feature interactions of genuinely different nature. The more ordinary and magnetically-tunable contact interaction combines with the long-range and anisotropic magnetic dipolar interaction. The mere existence and competition between these two sources of interactions dictate the physics at play, disclosing a variety of intriguing phenomena in close connection to superfluid He.
This talk will provide an overview of some fascinating dipolar phenomena from the Innsbruck prospective, including the first observation of roton in the gas and quasi-self-bound quantum droplets. |

### PRISMA Colloquium

Institut für Physik 13:00 Uhr s.t., Lorentz-Raum 05-127, Staudingerweg 7 |

Gia Khoriauli, Universität Mainz | |

"The NA62 is a fixed target experiment at CERN operating with 400 GeV/c proton beam supplied by the CERN SPS accelerator facility. A secondary beam of positively charged Kaons with the 75 GeV/c momentum is selected after the target. The NA62 aims to collect 10^{13} charged Kaon decays to be able to measure the branching ratio of a very rare FCNC decay K^{+} -> pi^{+} nu anti-nu with better than 10% precision. The branching ratio is precisely known in the Standard Model. The most recent theoretical calculation provides about 10% accuracy. Therefore, this decay is very sensitive to possible new physics phenomena, which can alter its branching ratio. The NA62 was able to reach the Standard Model sensitivity region for the interesting decay by analyzing data collected in 2016. This preliminary result is presented in the current work. The theory framework and the NA62 detector are also reviewed." |

### Seminar über Quanten-, Atom- und Neutronenphysik (QUANTUM)

Institut für Physik 14 Uhr c.t., Lorentz-Raum (05-127), Staudingerweg 7 |

Dr. Michele Campisi, Department of Physics and Astronomy, University of Florence, Italy | |

I will begin showing that heat engines and refrigerators can be understood as a driven
bipartite quantum system. I will then illustrate that a fluctuation theorem (the so called heat
engine fluctuation relation or HEFR) holds for such system [1]. Fluctuation theorems are exact
relations in non-equilibrium thermodynamics that are obeyed by the statistics of work and heat
(which are indeed stochastic variables) [2]. The second law of thermodynamics in both Carnot and
Kelvin formulation can be quickly derived from the HEFR, and as well in the formulation according
to which heat spontaneously flows from hot to cold. I will then illustrate a possible experimental realisation
of quantum heat engine/refrigerator with superconducting qubits, and illustrate its functioning [3].
If time will allow I will discuss how quantum measurements and feedback control may break the HEFR and
illustrate the possible implementation a Maxwell Demon that can steer energy from cold reservoir to a
hot one by observing the state of a central qubit playing the role of trapdoor and using the acquired
information [4].
[1] M. Campisi Fluctuation relation for quantum heat engines and refrigerators, J. Phys A: Math Theor 47, 245001 (2014)
[2] M. Campisi, P. Hänggi, and P. Talkner, Colloquium. Quantum Fluctuation Relations: Foundations and Applications, Rev. Mod. Phys. 83 , 771 (2011)
[3] M. Campisi, J. Pekola, R. Fazio, Nonequilibrium fluctuations in quantum heat engines: Theory, example, and possible solid state experiments, New J. Phys.17 0350 (2015)
[4] M. Campisi, J. Pekola and R. Fazio, Feedback controlled heat transport in quantum devices: Theory and solid state experimental proposal, New J. Phys. 19 05302 (2017) | |

Vortrag im Rahmen des SFB/TR 49-Kolloquiums |

### SFB/TR49/SFB TRR 173 Spin+X-Kolloquium - Seminar experimentelle Physik der kondensierten Materie

SFB/TR49 - Prof. Dr. Elmers 14:15 Uhr s.t., MAINZ-Seminarroom, Staudinger Weg 9, 03-122 |

Prof. Dr. Pietro Gambardella, Department of Materials, ETH Zürich, Switzerland | |

The coupling of spin and orbital angular momenta underlies the magnetoelectric properties of matter. Although small, the spin-orbit interaction determines the equilibrium properties of magnets as well as the possibility to excite the magnetization out of equilibrium while ensuring the conservation of angular momentum. In this talk, I will review prominent mechanisms due to spin-orbit coupling that give rise to spin currents in ferromagnetic and antiferromagnetic heterostructures, showing how unusual magnetoresistance [1] and spin torque [2-4] phenomena emerge from charge-spin conversion in these materials. Finally, I will present recent results based on pump-probe magneto-optic experiments that allow us to measure the spin Hall effect in nonmagnetic conductors [5] and image current-induced magnetization switching of ferromagnetic dots on a timescale of 100 ps [6]. |

### Seminar about Experimental Particle and Astroparticle Physics (ETAP)

Institut für Physik 12:30 Uhr s.t., Staudingerweg 7, Minkowskiraum |

Alec Lindman, ETAP | |

## First Results from an Atomic Tritium Test Stand |

### Institutsseminar Kern- und Hadronenphysik

Institut für Kernphysik 14 Uhr c.t., HS Kernphysik, Becherweg 45 |

J. Diefenbach, Mainz | |

## Strahlenschutzunterweisung |

### SFB/TR49/SFB TRR 173 Spin+X-Kolloquium - Seminar experimentelle Physik der kondensierten Materie

SFB/TR49 - Prof. Dr. Elmers Sonderseminar: 14:00 Uhr s.t., MEDIEN-Raum, Staudinger Weg 79, 03-431 |

Atsufumi Hirohata, Department of Electronic Engineering, University of York | |

Spintronics is one of the emerging research fields in nanoelectronics, of which future progress depends on the development of new materials. One of such materials is a half-metallic ferromagnet with 100% spin polarisation at the Fermi level. Here, Heusler alloys have the greatest potential due to their controllable intrinsic magnetisation, high Curie temperature and good lattice matching with common substrates. We have been growing such alloys in their epitaxial and polycrystalline film forms to demonstrate larger activation volume and to achieve over 50% reduction in crystallisation energy by aligning the crystalline plane to be (110). These films have been confirmed to have a bandgap at the Fermi level by infra-red circularly polarised photoexcitation.
These ternary Heusler alloys have a cubic structure, leading to in-plane magnetic anisotropy. However, the in-plane magnetisation is known to be inferior to the perpendicular anisotropy due to their recording/storage density for applications. For further miniaturisation of the spintronic devices, perpendicular anisotropy is therefore necessary, which can be induced by tetragonal distortion by growing the Huesler alloy film on a bcc seed layer with the (110) surface plane [7]. Zero-moment Heusler alloys, such as antiferromagnets [8], have also been developed for the GMR and/or TMR device implementation. Such fast development is unique to the research field of spintronics.
This work has been partially supported by EPSRC (EP/H026126/1, EP/K03278X/1, EP/M02458X/1), Royal Society Industry Fellowship, EU-FP7 HARFIR (NMP3-SL-2013-604398) and JST PRESTO and CREST. | |

Sonderseminar |

### Theorie-Palaver

Institut für Physik 14:30 Uhr s.t., THEP social room |

Michael Schmidt, Sydney University | |

Particle dark matter is the simplest explanation for the missing mass in our Universe. I will focus on weakly interacting massive particles (WIMPs) which are theoretically well motivated. Despite tremendous experimental effort, so far there is no solid evidence in (in)direct detection experiments or at the LHC. This indicates that the scattering cross section of dark matter with Standard Model particles may be smaller than naively assumed. I will discuss two aspects related to this: (i) the possibility that dark matter does not directly couple to quarks and consequently direct detection only occurs at loop level; (ii) regions of parameter space, which are naively ruled out, because dark matter is overabundant, may be allowed if there is a phase in the early Universe during which dark matter is unstable. |

### Physikalisches Kolloquium

Institut für Kernphysik, Johann Joachim Becher Weg 45 16 Uhr c.t., HS KPH |

Owe Philipsen, ITP, Goethe-Universität, Frankfurt/Main | |

Despite the long history of experimental nuclear physics and a plethora of data, we are still lacking a theoretical description in terms of the fundamental theory of the strong interactions, Quantum Chromodynamics (QCD).
This issue has become pressing with the discovery of very massive neutron stars, whose core density is believed to exceed nuclear density by far, and hence warrants a theoretical description of bulk nuclear matter rooted in QCD.
Unfortunately, QCD at finite matter density is not tractable by lattice Monte Carlo methods, which have proven so successful in the theoretical description of the hadron spectrum. After a brief introduction to lattice QCD, I will explain why it does not work at finite density and summarize what we know about the QCD phase diagram. I will then present a solution to the problem based on analytic expansions, which are so far only valid for very heavy quarks. For this case, an equation of state for bulk nuclear matter can be successfully calculated. |

### PRISMA Colloquium

Institut für Physik 13:00 Uhr s.t., Lorentz-Raum 05-127, Staudingerweg 7 |

Tina Pollmann, TUM- Garching | |

DEAP-3600 is a single-phase liquid-argon Dark Matter direct detection experiment located 2 km underground at SNOLAB, in Sudbury, Canada. With a 1 tonne fiducial mass, the target sensitivity to spin-independent scattering of 100 GeV weakly interacting massive particles (WIMPs) is 10^-46 cm^2. The detector was designed and built to reach a background level of less than 0.6 events in 3 tonne-years exposure. This included designing all parts of the detector to prevent or veto backgrounds, radio-purity screening for all detector materials, working with suppliers to source radio-pure materials, and using construction techniques that limit contaminations with radio-isotopes. The largest remaining background - beta decays from Ar-39 - is mitigated offline through pulse shape analysis. DEAP-3600 has been taking physics data since late 2016. This talk presents first results and the status of the experiment. |

### Seminar about Experimental Particle and Astroparticle Physics (ETAP)

Institut für Physik 12:30 Uhr s.t., Staudingerweg 7, Minkowskiraum |

Marc Geisen, ETAP | |

## Higgs Cross Section in Vector Boson Fusion with H->WW |

### Institutsseminar Kern- und Hadronenphysik

Institut für Kernphysik 14 Uhr c.t., HS Kernphysik, Becherweg 45 |

Tom Jude, Bonn | |

## Strangeness photoproduction with the BGO-OD experiment at ELSA |

### Excellence@WORK

MAINZ 12:15 Uhr s.t., MAINZ Seminarraum (Staudingerweg 9, 03.122) |

Dr. Benjamin Trefz, Senacor Technologies AG, Physiker | |

## Ven der Naturwissenschaft zur Softwarearchitektur - digitale Zukunft transformieren |

### Seminar Festkörper- und Grenzflächenphysik KOMET - experimentell

Institut für Physik 12:15 Uhr s.t., Newton-Raum, Staudingerweg 9, 1. Stock, Raum 122 (Nebengebäude) |

Christian Lidig, Institut für Physik | |

## Stability of a highly spin polarized surface resonance of Co2MnSi at spin-valve interfaces |

### Theory of Condensed Matter: Hard Condensed Matter

Institut für Physik, SPICE 14:00 Uhr s.t., Galileo room, 01-128 (Staudinger Weg 9) |

Paschalis Gkoupidenis, Max Planck Institute for Polymer Research, Mainz, Germany | |

Hardware-based implementation of neuromorphic architectures offers efficient ways of data manipulation
and processing, especially in data intensive applications such as big data analysis and real time
processing. In contrast to traditional von Neumann architectures, neuro-inspired devices may offer
promising solutions in interacting with human sensory data and process information in real time.
Therefore such kind of devices may offer in the future novel ways of data manipulation in bioelectronics.
Over the past years, organic materials and devices have attracted lots of attention in bioelectronics due to
their attractive characteristics for bioelectronics applications such as biocompatibility, the ability to
operate in liquid electrolytes, tunability via chemical synthesis and low cost fabrication processes.
Here, various concepts of organic neuromorphic devices will be presented based on organic
electrochemical transistors (OECTs), devices that are traditionally used in bioelectronics. Regarding the
implementation of neuromorphic devices, the key properties of the OECT that resemble the neural
environment will be presented here. These include the operation in liquid electrolyte environment, low
power consumption and the ability of formation of massive interconnections through the electrolyte
continuum. Showcase examples of neuromorphic functions with OECTs will also be presented, including
short-, long-term plasticity and spatiotemporal or distributed information processing. |

### Theorie-Palaver

Institut für Physik 14:30 Uhr s.t., THEP social room |

Nayara Fonseca, DESY Hamburg | |

The relaxion models propose a new idea to explain the smallness of the Higgs mass. They rely on the scanning of the Higgs mass parameter by a new field, the relaxion, and a back-reaction mechanism that is triggered when the Higgs vacuum expectation value has reached the size of the electroweak scale, making the relaxion evolution cease. In the usual relaxion model the scanning happens during an inflationary period. Here we explore the cosmological consequences if the relaxation happens independently of inflation. In this scenario, the stopping mechanism is provided by particle production. The stopping barriers of the periodic potential are large and Higgs-independent, which facilitates the model-building and can make the relaxion heavier than in the usual case. |

### Physikalisches Kolloquium

Institut für Kernphysik, Johann Joachim Becher Weg 45 16 Uhr c.t., HS KPH |

Yannick Dumeige, Laboratoire FOTON, Université de Rennes | |

High quality-factor optical micro-resonators with long photon lifetimes are of great interest in contemporary photonics. In the linear regime, they can be used as optical memories, delay lines, highly selective filters with applications in biological or chemical sensing and in optical signal processing. In this talk we will show that by introducing optical gain within microcavities their dispersive and filtering properties can be enhanced and controlled. We will also show that slowing down the light propagation can increase by several order of magnitude, up to few milliseconds, the photon lifetime of whispering gallery mode micro-resonators operating in the near infrared. |

### PRISMA Colloquium

Institut für Physik 13:00 Uhr s.t., Lorentz-Raum 05-127, Staudingerweg 7 |

Alfonsi Matteo, Universität Mainz | |

The XENON1T detector, located at the Laboratori Nazionali del Gran Sasso in central Italy, is the largest and most sensitive dual phase xenon Time Projection Chamber searching for Dark Matter (DM). New results on the direct detection of Weakly Interactive Massive Particles (WIMPs), a well-motivated particle DM candidate, have been recently published, based on an exposure of 1.0 tonne x year (fiducial mass of 1.3 tonne, 278.8 days data taking). In this talk I discuss the experimental apparatus, the ultra-low background conditions achieved, and the recent results, which set the most stringent limit on the WIMP-nucleon spin-independent elastic scattering cross-section for WIMP masses above 6 GeV/c². |

### Seminar zur Vielteilchentheorie

Institut für Physik Sonderseminar: 15:00 Uhr s.t., Lorentzraum (05-127) |

Dr. Shi-Ju Ran, ICFO The Institute of Photonic Sciences, Barcelona | |

Due to the presence of strong correlations, theoretical or experimental investigations of quantum many-body systems belong to the most challenging tasks in modern physics. Stimulated by tensor networks, we propose a scheme of constructing the few-body models that can be easily accessed by theoretical or experimental means, to accurately capture the ground-state properties of infinite many-body systems in higher dimensions. The general idea is to embed a small bulk of the infinite model in an ``entanglement bath'' so that the many-body effects can be faithfully mimicked. The approach we propose is efficient, simple, flexible, sign-problem-free, and it directly accesses the thermodynamic limit. The numerical results of the spin models on honeycomb and simple cubic lattices show that the ground-state properties including quantum phase transitions and the critical behaviors are accurately captured by only O(10) physical and bath sites. | |

Sonderseminar |

### Seminar über Quanten-, Atom- und Neutronenphysik (QUANTUM)

Institut für Physik 14 Uhr c.t., Lorentz-Raum (05-127), Staudingerweg 7 |

Prof. Dr. Jean-Michel Raimond, Sorbonne Université, Laboratoire Kastler Brossel, Collège de France, Paris | |

Rydberg atoms, excited states with a high principal quantum number are very sensitive to external fields. Their rich level structure allows one to engineer non-classical states, which can be used for the realization of quantum-enabled sensors. We realized an electrometer based on Schrödinger cats, superpositions of states with very different electric dipoles. It measures the electric field and its time correlation function with a 5 MHz bandwidth. Its exquisite sensitivity leads to interesting perspectives for single-charge detection in mesoscopic physics. We also develop a quantum-enabled magnetometer based on a superposition of circular Rydberg states with opposite magnetic moments.
The strong dipole-dipole interactions between giant Rydberg atoms can be used to realize quantum simulations of many-body problems. We propose a quantum simulator, based on laser-trapped circular Rydberg atoms, protected from spontaneous emission, with lifetimes in the minute range. The dipole-dipole interaction implements a XXZ nearest-neighbor spin-1/2 Hamiltonian. All its parameters are under control. This flexible simulator of spin ensembles is able to follow their evolution over extremely long times. I will report on progress towards its realization. |

### Seminar about Experimental Particle and Astroparticle Physics (ETAP)

Institut für Physik 12:30 Uhr s.t., Staudingerweg 7, Minkowskiraum |

Letizia Peruzzo, ETAP | |

## Search for pi0 -> invisible Decays |

### Institutsseminar Kern- und Hadronenphysik

Institut für Kernphysik 14 Uhr c.t., HS Kernphysik, Becherweg 45 |

Victor Bechthold, Mainz | |

## Potassium Cesium Antimonide - a photocathode for high average currents at MESA ? |

### Seminar zur Vielteilchentheorie

Institut für Physik 10:15 Uhr s.t., Seminarraum K (Bau 2/413, 01-525) |

Dr. Lorenzo Cardarelli, ITP Universitt Hannover | |

We show that whereas spin-1/2 one-dimensional U(1) quantum-link models (QLMs) are topologically trivial, when implemented in ladder-like lattices these models may present an intriguing ground-state phase diagram, which includes a symmetry protected topological (SPT) phase that may be readily revealed by analyzing long-range string spin correlations along the ladder legs. We propose a simple scheme for the realization of spin-1/2 U(1) QLMs based on single-component fermions loaded in an optical lattice with s- and p-bands, showing that the SPT phase may be experimentally realized by adiabatic preparation. |

### Seminar Festkörper- und Grenzflächenphysik KOMET - experimentell

Institut für Physik 12:15 Uhr s.t., Newton-Raum, Staudingerweg 9, 1. Stock, Raum 122 (Nebengebäude) |

Daniel Schönke, Institut für Physik | |

## Magnetic imaging using SEMPA with ns time resolution and phase-sensitive detection | |

ENTFÄLLT -- CANCELLED |

### Theorie-Palaver

Institut für Physik 14:30 Uhr s.t., THEP social room |

Dhritiman Nandan, University of Edinburgh | |

In this talk I will discuss recent developments in the study of scattering amplitudes in Einstein-Yang-Mills Theory. I will present novel relations between tree-level amplitudes in this theory and YM theory. Finally, I will discuss unitarity based observations regarding rational one-loop amplitudes involving gluons and gravitons. |

### Physikalisches Kolloquium

Institut für Kernphysik, Johann Joachim Becher Weg 45 16 Uhr c.t., HS KPH |

Tanja Schilling, Albert-Ludwigs-Universität Freiburg | |

In several branches of physical chemistry, biophysics and statistical physics it is common
to use transition state theory to estimate rates of processes. Transition state theory and
related approaches (such as Kramer's theory) are in essence quasi-equilibrium theories.
Computer simulation in soft matter and biophysics also often employs quasi-equilibrium
concepts to model out-of-equilibrium processes.
In the colloquium, we give an overview over these concepts. Then we present a recent
piece of work, in which we used time-dependent projection operator formalism to obtain
coarse-grained dynamics out of equilibrium. Finally, as an illustration of a non-equilibrium
path sampling method, we discuss the dynamics of the game of chess. |

### PRISMA Colloquium

Institut für Physik 13:00 Uhr s.t., Lorentz-Raum 05-127, Staudingerweg 7 |

Heather Russel, McGill University | |

Despite the best efforts of many people, physics beyond the standard model has yet to be discovered. A variety of exotic signatures that would hide from traditional searches have been postulated in an attempt to explain where such new physics could be hiding.
This seminar will provide an overview of some of the
stranger, more exotic models that are searched for at LHC experiments, with an emphasis on long-lived, neutral particles. |

### Seminar über Quanten-, Atom- und Neutronenphysik (QUANTUM)

Institut für Physik 14 Uhr c.t., Lorentz-Raum (05-127), Staudingerweg 7 |

Prof. Dr. Dan Stamper-Kurn, Department of Physics, University of California, Berkeley, USA | |

An assortment of quantum technologies are being developed, for purposes such as precise sensing, quantum information processing, and quantum simulation of complex systems, in which light is used to cause quantum objects to interact and to allow their properties to be measured. By combining techniques of ultracold atomic physics and quantum optics, we have developed a system in which both mechanical oscillators and also spin oscillators, both comprised of small batches of atoms trapped in vacuum, interact with the electromagnetic modes of a high-finesse optical cavity. I will describe the use of this system for realizing quantum-limited force detection, for cavity "cooling" of spin ensembles, and for exploring light-induced coupling between mechanical and spin oscillators. |

### SFB/TR49/SFB TRR 173 Spin+X-Kolloquium - Seminar experimentelle Physik der kondensierten Materie

SFB/TR49 - Prof. Dr. Elmers Sonderseminar: 14:15 Uhr s.t., MEDIEN-Raum, Staudinger Weg 7, Raum 03-431 |

Prof. Felix Casanova, Ikerbasque, San Sebastian, Spain | |

The discovery of new phenomena leading to spin-to-charge current conversion (spin Hall effect (SHE) in heavy metals, Edelstein effect in Rashba interfaces, spin-momentum locking in topological insulators) is expanding the potential of applications such as the magnetization switching of ferromagnetic elements for memories [1] or the recent proposal of a spin-orbit logic [2] which can have a strong technological impact. Finding routes to maximize the SHE is not possible as long as it remains unclear which is the dominant mechanism in a material. I will present a systematic study in Pt, the prototypical SHE material, using the spin absorption method in lateral spin valve devices. We find a single intrinsic spin Hall conductivity in a wide range of resistivities, in good agreement with theory. By tuning the resistivity, we observe for the first time the crossover between the moderately dirty (where the intrinsic mechanism dominates) and the superclean (where the extrinsic mechanism governs) scaling regimes of the SHE, equivalent to that obtained for the anomalous Hall effect. Our results explain the dispersion of values in the literature and find a route to maximize this important effect [3]. We also studied highly-resistive Ta, a material with a claimed giant SHE. In this case, the intrinsic mechanism in Ta dominates the SHE and allows us to linearly enhance the spin Hall angle by further increasing the resistivity of Ta, reaching up to -35±3 %, the largest value reported for a pure metal [4]. Finally, I will show how to optimize the spin-to-charge current conversion at room temperature by combining Pt with a graphene channel [5], opening up exciting opportunities towards the implementation of spin-orbit-based logic circuits. | |

Sonderseminar |

### Seminar zur Vielteilchentheorie

Institut für Physik Sonderseminar: 16 Uhr c.t., Lorentzraum (05-127) |

Dr. Mykhailo Rakov, Universitt Kiew | |

Continuous symmetries (U(1) and SU(2)) are incorporated into matrix product states (MPS) for periodic boundary conditions (PBC). Appropriate mathematical formalism is tedious but efficient with sparse tensor techniques. The possibility of ab initio construction of U(1) and SU(2) symmetric MPS is touched upon. The advantage of circular update manner is utilized for U(1) symmetric case.
A variety of numerically demanding properties of 1D spin systems is addressed. Firstly, complicated entanglement structure of the excited states is uncovered in the ferromagnetic phase of U(1) symmetric spin-1/2 XXZ model. In particular, three-tangle has significant weight close to and inside this phase. Secondly, the boundaries of the dimerized phase in the SU(2)-symmetric biquadratic spin-1 Heisenberg model with single-ion anisotropy are determined. The results suggest that gapless dimerized area can exist in a 1D system, thus explaining big discrepancy in the results of other groups. An attempt to clarify the behavior of the bilinear-biquadratic Heisenberg model close to SU(3) symmetric point is also made. | |

Sonderseminar |

### Seminar about Experimental Particle and Astroparticle Physics (ETAP)

Institut für Physik 12:30 Uhr s.t., Staudingerweg 7, Minkowskiraum |

Daniel Wenz, ETAP | |

## Calibration of the MainzTPC with Ar-37 | |

Master Colloquium |

### Institutsseminar Kern- und Hadronenphysik

Institut für Kernphysik 14 Uhr c.t., HS Kernphysik, Becherweg 45 |

Nicolas Pierre, Mainz/Saclay | |

## Monte Carlo event generation with radiative QED Processes in Deep-Inelastic Scattering |

### Excellence@WORK

MAINZ 12:15 Uhr s.t., MAINZ Seminarraum (Staudingerweg 9, 03.122) |

Dr. Alexandra Christ, Umweltministerium Rheinland-Pfalz, Geologin | |

## Ministerialrätin - Als Naturwissenschaftlerin im behördlichen Umweltschutz |

### Seminar Festkörper- und Grenzflächenphysik KOMET - experimentell

Institut für Physik 12:15 Uhr s.t., Newton-Raum, Staudingerweg 9, 1. Stock, Raum 122 (Nebengebäude) |

Vladimir Grigorev, Institut für Physik | |

## Ultrafast dynamics in spin-liquid candidate RuCl3 |

### Theory of Condensed Matter: Hard Condensed Matter

Institut für Physik, SPICE 14:00 Uhr s.t., Galilei room, 01-128 (Staudinger Weg 9) |

Ilja Müller, JGU | |

## Master thesis talk: Method seminar "Theoretical Approach of Electron Transport in Organic Semiconductors by the example of Organic Molecule PSSS" |

### Physikalisches Kolloquium

Institut für Kernphysik, Johann Joachim Becher Weg 45 16 Uhr c.t., HS KPH |

Michael Farle, Universität Duisburg-Essen | |

Lets dream of materials that convert energy reversibly by temperature changes between day and night or provide a non-invasive treatment of cancer. These visions may be realized by using magnetic nanoparticles that are functionalized to be biocompatible or environmentally stable and recyclable, which are low-cost and allow the design of self-healing materials.
Starting with a discussion of basic concepts of magnetic properties with a focus on how to tune parameters in a nanomagnet, I will highlight selected state-of-the-art experimental approaches [1,2] that allow us to experimentally analyze multifunctional particles with single particle or even atomic precision. The apparently complex behavior of hybrid metal/metal, metal/oxide, or oxide/oxide interface materials core-shell materials - can be understood from the three fundamental interactions in magnetism: magnetic exchange due to orbital overlap, spin-orbit interaction due to inner- and intra-atomic relativistic effects (e.g., crystal field effects) and the long-range magnetic dipolar interaction. Several examples will be presented, including the formation of above-room-temperature ferromagnetic interface layers between core/shell antiferromagnetic shells, the design of a macroscopic magnet with a monopole-like magnetic response [3] and the first magnonic dispersion measured in single magnetotactic bacteria.
Work supported by European Union and Deutsche Forschungsgemeinschaft. The fruitful collaboration with many colleagues and students is thankfully acknowledged.
[1] M. Farle Imaging techniques: Nanoparticles atoms pinpointed NATURE (News and Views) 542 (2017) 35
[2] Zi-An Li, et al. Magnetic Skyrmion Formation at Lattice Defects and Grain Boundaries Studied by Quantitative Off-Axis Electron Holography, Nano Lett. 17 (2017) 13951401, and Nat. Comm. 8 (2017) 15569
[3] Franziska Scheibel, Detlef Spoddig, Ralf Meckenstock, Aslı Çakır, Michael Farle, and Mehmet Acet
Shell-ferromagnetism in a Ni-Mn-In off-stoichiometric Heusler studied by ferromagnetic resonance
AIP Advances 7 (2016) 056425 |

### MAINZ lecture series

MAINZ 09 Uhr c.t., Staudingerweg 9, 03-122 |

Siegfried Waldvogel, Organic Chemistry, JGU | |

## Electrifying Organic Synthesis | |

introduced by Maximilian Selt |

### PRISMA Colloquium

Institut für Physik 13:00 Uhr s.t., Lorentz-Raum 05-127, Staudingerweg 7 |

Markus Oberthaler, KIP Universität Heidelberg | |

The fundamental research of controlled quantum systems has become mature and applications especially in the realm of sensing have been developed. In this colloquium I will discuss the basic tools and techniques in the field of quantum atom optics which allow for the detection of single atoms one by one. These capabilities allow the implementation of trace analysis at the ultimate quantum level, namely on the single atom level. More specifically I will present our latest results on detecting the rare isotope 39Ar which is a perfect age tracer for oceanography and ground water. With the new capabilities less than 10 liters of water are necessary to give a good estimate for the apparent age of the water sample. As first application we analyzed ocean depth profiles close to Cape Verde and can give new constraints to the transit time distribution by combining the results with other tracer results. This gives a new route to characterizing the ventilation of the ocean. Since the amount of water has become very small, sample taking gets into the regime of being parasitic or better symbiotic to standard sampling campaigns. |

### Seminar über Theorie der kondensierten Materie / TRR146 Seminar

10:30 Uhr s.t., Newtonraum, 01-122, Staudingerweg 9 |

Dominika Lesnicki, Institut für Physik | |

## Increased acid dissociation at the Quartz/Water interface |

### Seminar über Quanten-, Atom- und Neutronenphysik (QUANTUM)

Institut für Physik 14 Uhr c.t., Lorentz-Raum (05-127), Staudingerweg 7 |

Prof. Dr. Fred Jendrzejewski, Kirchhoff-Institut für Physik, Universität Heidelberg | |

Mixtures of ultracold atomic gases are an extremely versatile platform for the investigation of a wide variety of fundamental questions in physics. In this talk, we will first discuss their realization as done in our lab [1]. We will then present their possible application to two rather distinct problems, the quantum simulation of dynamical gauge fields [2] and the implementation of quantum heat engines.
REFERENCES
[1] T. Rentrop, A. Trautmann, F. A. Olivares, F. Jendrzejewski, A. Komnik, and M.
K. Oberthaler, Observation of the phononic Lamb shift with a synthetic vacuum, Phys. Rev. X 6, 41041 (2016).
[2] V. Kasper, F. Hebenstreit, F. Jendrzejewski, M. K. Oberthaler, and J. Berges, Implementing quantum electrodynamics with ultracold atomic systems New J. Phys. 19, 23030 (2016). | |

Vortrag im Rahmen des SFB/TR 49-Kolloquiums |

### Seminar über Theorie der kondensierten Materie / TRR146 Seminar

10:15 Uhr s.t., Newtonraum, 01-122, Staudingerweg 9 |

Prof. Hendrik Heinz, Department of Chemical and Biological Engineering, University of Colorado-Boulder | |

## Understanding Multiphase Materials Interactions from Molecules to Microstructures |

### MAINZ lecture series

MAINZ Sonderseminar: 09 Uhr c.t., Staudingerweg 9, 03-122 |

Clemens Barth, Institut de Physique, CINaM - Centre Interdisciplinaire de Nanoscience de Marseille | |

## Kelvin Probe Force Microscopy in Surface Science and Catalysis | |

Sonderseminar |

### Seminar about Experimental Particle and Astroparticle Physics (ETAP)

Institut für Physik 12:30 Uhr s.t., Staudingerweg 7, Minkowskiraum |

Bernard Brickwedde, ETAP | |

## Transverse Momentum of the Z Boson in ATLAS |

### Institutsseminar Kern- und Hadronenphysik

Institut für Kernphysik 14 Uhr c.t., HS Kernphysik, Becherweg 45 |

Nike Heinß, IMM Mainz | |

## The effect of deformability on particle velocity in laminar flows |

### Seminar Festkörper- und Grenzflächenphysik KOMET - experimentell

Institut für Physik 12:15 Uhr s.t., Newton-Raum, Staudingerweg 9, 1. Stock, Raum 122 (Nebengebäude) |

Mariia Filianina, Institut für Physik | |

## Electric field control of magnetism in thin films |

### Theory of Condensed Matter: Hard Condensed Matter

Institut für Physik, SPICE 14:00 Uhr s.t., Galilei room 01-128 (Staudinger Weg 9) |

Mikhail Titov, Radboud University, Nijmegen | |

We derive general finite temperature expressions for Dzyaloshinskii-Moriya
interaction (DMI) and symmetric exchange in a 2D s-d ferromagnet model with
momentum-dependent spin-orbit coupling (SOC) of Rashba type and arbitrary
(generally non-parabolic) kinetic energy of itinerant electrons. We show that a
commonly used parabolic model with Rashba SOC gives rise to vanishing of
both DMI and exchange stiffness in the metal regime, i.e. for both spin-split subbands
occupied. Both quantities are, however, finite if non-parabolic corrections
to kinetic energy or non-linear corrections to SOC are taken into account. We
further demonstrate that the commonly assumed form of the DMI in terms of
Lifshitz invariants breaks down if SOC energy exceeds the s-d exchange energy. In
this situation, the DMI vector becomes strongly anisotropic. It also acquires an
additional essential dependence on the perpendicular-to-the-plane component of
the magnetization. We discuss the relevance of our results for the formation of
chiral magnetic textures in 2D systems with strong Rashba SOC. |

### Theorie-Palaver

Institut für Physik 14:30 Uhr s.t., THEP social room |

Jonathan Gaunt, CERN | |

We rely heavily on factorisation formulae to make useful predictions at colliders such as the LHC. But when do such formulae work, and why? When do they not work? I will discuss this issue in the context of the production of a colour singlet V at hadronic colliders. Observables discussed include the total cross section for the production of V, p_T of V (including spin-dependent observables), and hadronic transverse energy E_T accompanying V. Based on arXiv:1405.2080 and arXiv:1709.04935. |

### Physikalisches Kolloquium

Institut für Kernphysik, Johann Joachim Becher Weg 45 16 Uhr c.t., HS KPH |

Andreas Petzold, Forschungszentrum Jülich | |

The European Research Infrastructure IAGOS (In-service Aircraft for a Global Observing System;
www.iagos.org) and its predecessor programme MOZAIC perform long-term routine in-situ
observations of atmospheric chemical composition, water vapour, aerosols, clouds and
temperature on a global scale by operating compact instruments on board of passenger aircraft,
starting in 1994. The unique character of the IAGOS data set originates from the global-scale
sampling with similar instrumentation such that the observations are truly comparable and well
suited for atmospheric research on a statistical basis. Emerging data records cover more than 20
years for ozone and water vapour, whereas ice cloud particle data are available since 2011. The
talk will focus on the new findings on ozone, water vapour and cirrus clouds. |

### Excellence@WORK

MAINZ Sonderseminar: 17:15 Uhr s.t., Helmholtz-Institut Mainz, Raum 00-135 |

Dr. Holger Bengs, BCNP Consultants GmbH | |

## Chemiker, Consultant, Unternehmer: Der Weg vom Periodensystem zum Netzwerker | |

Sonderseminar |

### PRISMA Colloquium

Institut für Physik 13:00 Uhr s.t., Lorentz-Raum 05-127, Staudingerweg 7 |

Jan Plefka, Humboldt-Universität, Berlin | |

We review our recent work on the efficient construction of tree and one-loop scattering amplitudes involving
gravitons. The general complexity of perturbative gravity will be discussed and recent insights on
rewriting gravitational scattering amplitudes as a double copy of Yang-Mills theories reviewed.
Then our results on expanding amplitudes involving gravitons into a basis of only gluon (or more general
gluon-matter) amplitudes will be reviewed. Finally, the construction of all rational Einstein-Yang-Mills
amplitudes at one-loop order shall be exposed. |

### Seminar about Experimental Particle and Astroparticle Physics (ETAP)

Institut für Physik 12:30 Uhr s.t., Staudingerweg 7, Minkowskiraum |

Johann Martyn, ETAP | |

## Directional Reconstruction of Neutrino Events in Borexino |

### Institutsseminar Kern- und Hadronenphysik

Institut für Kernphysik 14 Uhr c.t., HS Kernphysik, Becherweg 45 |

Mirco Christmann, Mainz | |

## Instrumentation and optimization studies for a Beam Dump Experiment at MESA |

### Quantum Sonderseminar

Institut für Physik 14 Uhr c.t., Medienraum (03-431) des Instituts für Physik |

Dr. Norbert M. Linke, Joint Quantum Institute, University of Maryland, College Park, MD 20742, USA | |

Trapped ions are a promising candidate system to realize a scalable quantum computer. We present a modular quantum computing architecture comprised of a chain of 171Yb+ ions with individual Raman beam addressing and individual readout [1]. We use the transverse modes of motion in the chain to produce entangling gates between any qubit pair. This creates a fully connected system which can be configured to run any sequence of single- and two-qubit gates, making it in effect an arbitrarily programmable quantum computer that does not suffer any swap-gate overhead [2].
Recent results from different quantum algorithms on five and seven ions will be presented [3], including current work in quantum machine learning. I will also discuss schemes to scale up this architecture, as well as other ideas for the future [4].
[1] S. Debnath et al., Nature 563:63 (2016)
[2] NML et al., PNAS 114 13:3305 (2017)
[3] NML et al., arXiv:1712.08581 (2017)
[4] S. Debnath et al., PRL, 073001 (2018) |

### Seminar Festkörper- und Grenzflächenphysik KOMET - experimentell

Institut für Physik 12:15 Uhr s.t., Newton-Raum, Staudingerweg 9, 1. Stock, Raum 122 (Nebengebäude) |

Stanislav Bodnar, Institut für Physik | |

## Manipulation of Néel vector in antiferromagnets |

### Theory of Condensed Matter: Hard Condensed Matter

Institut für Physik, SPICE 14:00 Uhr s.t., Galilei Raum, 01-128 (Staudinger Weg 9) |

Laura Köhler, Institute of Theoretical Physics, TU Dresden | |

The Dzyaloshinskii-Moriya interaction in chiral magnets stabilizes a magnetic helix with a wavelength set
by the spin-orbit coupling. We study domain walls of helimagnetic order both theoretically and
experimentally using micromagnetic simulations and magnetic force microscopy studies on surfaces of
FeGe. We find that such domain walls are distinctly different from those in ferromagnets and rather
similar to grain boundaries of liquid crystals. Three types of domain walls are realized depending on the
relative domain orientation: a curvature wall, a zig-zag disclination wall and a dislocation wall.
Disclinations are vortex defects in the helix axis orientation, and they can be combined to form
dislocations. We discuss the topological skyrmion charge associated with these dislocations which can be
finite. This leads to an emergent electrodynamics and thus a coupling to spin currents as well as to a
contribution to the topological Hall effect. We discuss the dislocation profile using both micromagnetic
simulations and an effective elasticity theory known from liquid crystals [2]. A single dislocation causes
long-range distortions of the perfect helix. As a consequence, impurities that pin the Goldstone mode
have a strong impact on the dislocation motion.
References
[1] Schnherr et al. Topological domain walls in helimagnets. Nat. Phys. 14, 465 (2018)
[2] Smalyukh, I. I., Lavrentovich, O. D. Physical Review E 66, 0511703 (2002) |

### Theorie-Palaver

Institut für Physik 14:30 Uhr s.t., THEP social room |

Matthias Neubert, JGU Mainz | |

When a new heavy particle is discovered at the LHC, it will be interesting to study its decays into Standard Model particles using an effective field-theory framework. We point out that the proper effective theory can not be constructed as an expansion in local, higher-dimensional operators; rather, it must be based on non-local operators defined in soft-collinear effective theory (SCET). For the interesting case where the new resonance is a gauge-singlet spin-0 boson, which is the first member of a new sector governed by a mass scale M, we show how a consistent scale separation between M and the electroweak scale v is achieved up to next-to-next-to-leading order in the expansion parameter λ∼v/M. The Wilson coefficients in the effective Lagrangian depend in a non-trivial way on the mass of the new resonance and the masses of yet undiscovered heavy particles. Large logarithms of the ratio M/v can be systematically resummed using the renormalization group. We develop a SCET toolbox, with which it is straightforward to construct the relevant effective Lagrangians for new heavy particles with other charges and spin. |

### Physikalisches Kolloquium

Institut für Kernphysik, Johann Joachim Becher Weg 45 16 Uhr c.t., HS KPH |

Michelangelo Mangano, CERN TH Division | |

The LHC results have redefined the boundary conditions for the discussion of future HEP facilities. On one side, the discovery of the Higgs and the knowledge of its mass clearly define the needs, the challenges and the prospects of future precise measurements of its properties. On the other, the lack on new physics signals stimulates reconsideration of theoretical scenarios, and opens a broad discussion of the best ways to move forward. I will informally review these issues, summarize the most recent initiatives, and provide some personal perspective. |

### Institutsseminar Kern- und Hadronenphysik

Institut für Kernphysik Sonderseminar: 14 Uhr c.t., A2 Meetingroom, Ersatzneubau, Kernphysik |

Calvin R. Howell, Duke University | |

## The low-energy QCD program at HIGS | |

Sonderseminar |

### PRISMA Colloquium

Institut für Physik 13:00 Uhr s.t., Lorentz-Raum 05-127, Staudingerweg 7 |

Kristina Giesel, University Erlangen/Nrnberg | |

Loop quantum gravity is a candidate for a theory of quantum gravity which takes general relativity as its classical starting point. The quantum theory is obtained by applying canonical quantization to general relativity. For this purpose, the techniques known from quantum field theory need to be generalized. As a consequence, loop quantum gravity is based on a quantum field theory, which is in many aspects different from the quantum field theory, that is used to formulate the Standard Model of particle physics. The dynamics of the quantum theory is described by the so called quantum Einstein equations, the quantum analog of Einstein's equations.
After a brief introduction to the ideas and concepts of loop quantum gravity, we will discuss the current status of the dynamics, particularly the role of gauge invariance in this context and also present further research directions currently addressed in loop quantum gravity. |

### Seminar über Theorie der kondensierten Materie / TRR146 Seminar

10:30 Uhr s.t., Newtonraum, 01-122, Staudingerweg 9 |

Andreas Fischer, Institut fr Physik | |

## Self-Organization of Active Particles by Quorum Sensing |

### Seminar über Quanten-, Atom- und Neutronenphysik (QUANTUM)

Institut für Physik 14 Uhr c.t., Lorentz-Raum (05-127), Staudingerweg 7 |

Dr. Arne Wickenbrock, Helmholtz-Institut Mainz und Institut für Physik, Universität Mainz | |

18 month have passed since we moved into the freshly opened Helmholtz Institute Mainz. 18 month of scientific activity, that are starting to bear fruits.
I will try to give an overview of the experiments that have been set up in the eight laboratories of the Matter-Anti-Matter section and will focus on the most recent highlights including our efforts to detect dark matter with atomic systems, recent results on the study of fundamental symmetries and the constructive role that atomic magnetometry is playing for a variety of applications. |

### Institutsseminar Kern- und Hadronenphysik

Institut für Kernphysik 14 Uhr c.t., HS Kernphysik, Becherweg 45 |

Markus Ball, Bonn | |

## The ALICE TPC upgrade from R&D to Installation |

### Theory of Condensed Matter: Hard Condensed Matter

Institut für Physik, SPICE 11:00 Uhr s.t., Galilei room 01-128 (Staudinger Weg 9) |

Jonas Nothhelfer, JGU | |

Quantum Computation received great interest in the last years. There two level systems, in which the
energy levels can be described as effective spin up or spin down, are used. The special feature here is, that
the state of this two-level system is not forced to be either of the two spin directions, but also every
superposition in between which is then also known as a Qubit. Such Qubits form the basis of quantum
information theory, a fully new paradigm of computation with still undisclosed potential. In Spintronics
systems topological protected spin-structures can be stabilized through the Dzyaloshinski-Moriya
interaction. These objects are called magnetic skyrmions, which have many interesting properties and are
promising candidates for new applications. In my first Master talk, I will introduce two ideas how
magnetic skyrmion materials could potentially be used as a platform for quantum computation connecting
these two fields. The first idea is to exploit the excitation modes of skyrmions to define a qubit analogous
to the ones in Ion Trap quantum computers. The second idea is to use the topological properties of
skyrmions for topological quantum computation. |

### Institutsseminar Kern- und Hadronenphysik

Institut für Kernphysik Sonderseminar: 14:00 Uhr s.t., Roter Salon, Ersatzneubau, ground floor |

Garth Huber, University of Regina | |

Deep Exclusive Meson Production (DEMP) reactions are an important tool in our quest to better understand the non-perturbative structure of hadrons. They provide one of the clearest pictures of the inner workings of QCD, but the studies are difficult experimentally because of the small reaction cross sections and clean multi-particle coincidence requirements. In particular, DEMP reactions allow experimental access to the spacelike pion elastic form factor and the transition between perturbative and non-perturbative QCD. Similar techniques may allow access to the spacelike kaon form factor for the first time. Furthermore, if the hard-soft factorization regime is reached, DEMP reactions allow unique Generalized Parton Distribution data to be acquired. I will summarize the present experimental situation and provide an overview of what might be obtained during the first decade of 12 GeV Jefferson Lab Hall C operations. | |

Sonderseminar |

### Seminar über Theorie der kondensierten Materie / TRR146 Seminar

10:30 Uhr s.t., Newtonraum, 01-122, Staudingerweg 9 |

Samuel Ntim, Institut fr Physik | |

## Structure of room-temperature ionic liquids at metallic interfaces. |

### Theory of Condensed Matter: Hard Condensed Matter

Institut für Physik, SPICE 14:00 Uhr s.t., Galilei room, 01-128 (Staudinger Weg 9) |

Vincent Baltz, Inac, Institute for Nanoscience and Cryogenics | |

## Probing antiferromagnets with currents |

### Seminar zur Vielteilchentheorie

Institut für Physik 10:15 Uhr s.t., Seminarraum K (Bau 2/413, 01-525) |

Alvaro Diaz-Fernandez, Universidad Complutense, Madrid | |

Topological materials support topologically robust edge states in two dimensions and surface states in three dimensions [1], that are key to the envisaged technological devices related to these materials due to their remarkable properties in quantum transport measurements. To this respect, the Fermi velocity plays a crucial role. Early proposals have achieved the goal of modifying the Fermi velocity, but the experimental setups are rather cumbersome [2,3]. It would then be desirable to be capable of fine-tuning this parameter in a way that is experimentally simpler.
In this seminar, I will start with a brief overview of topological insulators, followed by a discussion of different alternatives to modify the Fermi velocity of topological crystalline insulators and three- dimensional topological insulators. I will show that electric and magnetic fields can be judiciously placed in order to achieve the goal of tailoring the Fermi velocity, even in an anisotropic way [4, 5, 6]. Interestingly enough, the hybridization of these states when two surfaces are sufficiently close forming a quantum well leads to an energy gap. The control of the Fermi velocity in the isolated surface translates into a control of the size of the energy gap [7]. Finally, I will consider the effects of strong disorder on these states, placing a δ-layer of donor atoms right at the surface. As I will show, surface states remain robust to such a large perturbation and their presence can be detected from their optical response as measured by the oscillator strength [8].
References
[1] M. Z. Hasan and C. L. Kane, Rev. Mod. Phys. 82, 3045 (2010).
[2] G. Li et al., Nat. Phys. 6, 109 (2010).
[3] D. C. Elias et al., Nat. Phys. 7, 701 (2011).
[4] A. Diaz-Fernandez et al., Sci. Rep. 7, 8058 (2017).
[5] A. Diaz-Fernandez et al., Physica E 93, 230 (2017).
[6] A. Diaz-Fernandez et al., Beilstein J. Nanotechnol. 9, 1405 (2018).
[7] A. Diaz-Fernandez et al., J. Phys.: Condens. Matter 29, 475301 (2017).
[8] A. Diaz-Fernandez et al., arXiv:1805.09879 [cond-mat.mes-hall]. |

### Quantum Sonderseminar

Institut für Physik 14 Uhr c.t., Medienraum (03-431) des Instituts für Physik |

Prof. Dr. Nikolay V. Vitanov, Faculty of Physics, Sofia University, Bulgaria | |

The technique of composite pulses replaces the single pulse used traditionally for driving a two-state quantum transition by a sequence of pulses with suitably chosen phases. These phases are used as control parameters for shaping the excitation profile in a desired manner.
Composite pulses produce unitary operations, which combine very high fidelity with robustness to parameter variations. We have developed a pool of composite pulses by using a novel SU(2) approach to design recipes for construction of single-qubit operations, including broadband, narrowband and passband pulses, universal composite pulses, composite adiabatic passage and composite STIRAP, some of which have already been demonstrated in experiments with doped solids and trapped ions. We have also designed efficient and robust composite techniques for construction of highly entangled states, e.g. Dicke and NOON states, and single-qubit and multi-qubit gates, e.g. C-phase, Toffoli, and generally CN-phase gates. Similar ideas have been used in the implementation of a new protocol for robust dynamical decoupling.
We have also applied the idea of composite sequences beyond quantum physics, e.g. in polarization optics and nonlinear frequency conversion, with recent experimental demonstrations. |

### Quantum Sonderseminar

Institut für Physik 11 Uhr c.t., Medienraum (03-431), Institut für Physik, Staudingerweg 7 |

Prof. Dr. Andrei Afanasev, Department of Physics, The George Washington University, Washington, DC, USA | |

Quantized optical vortices, or the twisted photons, may carry pre-set amounts of angular momentum along their direction of propagation, thus allowing for quantum transitions otherwise forbidden for conventional plane-wave light. In this talk I will address the question of the angular momentum transfer to internal degrees of freedom of quantum systems excited by the twisted photons, and discuss appropriate polarization observables. We will show that interactions of such beams generate parity-conserving single-spin asymmetries due to presence of an orbital angular momentum, showing in circular dichroism even in the isotropic atomic matter. We extend our theory approach to the case of semi-conductor quantum dots and demonstrate associated spin-orbit effects for spin injection of photoelectrons in bulk GaAs. I will also present new theoretical results for spin-orbit effects in scattering of low-energy twisted electrons and twisted neutrons off Coulomb field. The developed formalism was confirmed experimentally for twisted-photoexcitation of cold trapped 40Ca+ ions [A. Afanasev et al., New J. Phys. 20, 023032 (2018)]. |

### Quantum Sonderseminar

Institut für Physik 11 Uhr c.t., Medienraum (03-431), Staudingerweg 7 |

Prof. Dr. Hans A. Schuessler, Texas A&M University, College Station, TX, USA | |

High resolution spectroscopy in the infrared has been employed for monitoring atmospheric pollution with a variety of techniques. Here we report on recent advances using broadband infrared frequency combs in dual comb (1) and Vernier spectro-scopies (2), and narrow band diode lasers in cavity ring-down and wavelength modulation spectroscopies for the detection of methane in ambient air both in our laboratory, and over km path lengths in the atmosphere.
1. F. Zhu, J. Xia, A. Bicer, J. Bounds, A. A. Kolomenskii, J. Strohaber, L. Johnson, M. Amani, and H. A. Schuessler
Probing methane in air with a midinfrared frequency comb source
Applied Optics 56, 6311-6316 (2017) DOI: 10.1364/AO.56.006311.
2 .A. Bicer, J. Bounds, F. Zhu, A. A. Kolomenski, N. Kaya, E. Aluauee, M. Amani,
H. A. Schuessler
Sensitive Spectroscopic Analysis of Biomarkers in Exhaled Breath
International Journal of Thermophys 39-69 (2018) DOI:10.1007/s10765-018-2389-9. |

### Quantum Sonderseminar

Institut für Physik 14 Uhr c.t., Medienraum (03-431), Staudingerweg 7 |

Dr. Alexander M. Jakob, School of Physics, The University of Melbourne, Victoria, Australia | |

The remarkable success in addressing and manipulating single P-donor spins (qubits) in 28-Si represents a milestone for the realisation of quantum-computing and information transport applications. Inspired by these results, innovative quantum architectures such as the highly scalable flip-flop qubit configuration were recently proposed. A robust qubit entanglement over long distances up to several hundreds of nanometres loosens the generally tight constraints on the donor-qubit placement precision. This in turn makes ion implantation the semiconductor industrys standard doping tool very promising for scalable silicon quantum device fabrication. In order to allow a fully deterministic implantation of donor qubits into pre-defined quantum architecture sites, we employ the Ion Beam Induced Charge (IBIC) technique, which detects a single ion via free e-h-pairs induced upon the ion stopping in Silicon. A PIN diode architecture is therefore integrated into the silicon substrate to separate the induced free charge carriers and probe corresponding transients with surface electrodes.
However, the reliable detection of small charge signals generated by low-energetic ions raises tremendous demands on the single ion detectors noise performance.
In this study, we seek to further develop our single ion detector fabrication procedure. Prototype devices are electrically characterised using I-V analysis and admittance spectroscopy and are furthermore subjected to IBIC tests using sub-15 keV P-ions.
The detectors are evaluated in terms of low-noise performance at room temperature an essential pre-requisite for a scalable top-down fabrication of donor-qubits with highest fidelity and placement precision. |

### Quantum Sonderseminar

Institut für Physik 14 Uhr c.t., THEP-Sozialraum (05-427), Staudingerweg 7 |

Dr. Philip Light, IPAS, School of Physical Sciences, University of Adelaide, Adelaide, Australia | |

I will discuss our work on understanding and optimising the loading of laser cooled rubidium into hollow-core optical fibres to deliver a powerful technology for atom-optics and quantum information processing. I will also give an overview of other optical precision measurements in the Precision Measurement Group at the University of Adelaide, including Doppler-broadened primary thermometry, vapour-cell magnetometry and noble-gas radio-isotope ratiometry. |

### MAINZ lecture series

MAINZ Sonderseminar: 09 Uhr c.t., Staudingerweg 9, 03-122 |

Pulickel Ajayan, Materials Science and Engineering, Rice University, USA | |

## Materials Science with Atomically Thin Layers | |

Sonderseminar |

### Seminar über Theorie der kondensierten Materie / TRR146 Seminar

10:30 Uhr s.t., Newtonraum, 01-122, Staudingerweg 9 |

Johannes Nuebler, MIT | |

## Polymer Models for Chromatin Organization |

### MAINZ lecture series

MAINZ 09 Uhr c.t., Staudingerweg 9, 03-122 |

David Landau, Center for Simulational Physics, University of Georgia, USA | |

## Designing better lattice proteins and enzymes with modern Monte Carlo methods | |

introduced by Uday Chopra |

### SFB/TR49/SFB TRR 173 Spin+X-Kolloquium - Seminar experimentelle Physik der kondensierten Materie

SFB/TR49 - Prof. Dr. Elmers 14:00 Uhr s.t., der Raum wird separat angekndigt |

Sug-Bong Choe, 1Center for Subwavelength Optics and Department of Physics, Seoul National University, Seoul 151-742, Republic of Korea | |

In the last decade, there have been remarkable advances in the study of current-induced domain wall (DW) motion as the key operation principle of emerging memory and logic devices. As the major driving mechanism of the DW motion, spin-orbit torque (SOT) with chiral DWs draws great attention nowadays, which explains the direction of DW motions in heavy metal/transition metal/oxide films. However, here we demonstrate that the spin-transfer torque (STT) is significantly enhanced in ultra-thin Co films sandwiched by Pt layers and consequently, plays a major role in determining the direction of DW motions. Such significant enhancement is attributed to the ultra-narrow DW width down to about 1 nm, which considerably boosts up the nonadiabaticity of the conduction electrons. Moreover, the sign of the enhanced STT is found to be negative, possibly caused by either a negative nonadiabaticity or a negative spin polarization, which results in the DW motion along the current direction. The detailed experimental procedures and results will be discussed. |

### THEP Internal Seminar / Exp. Theory Crosstalk

Institut für Physik 13:30 Uhr s.t., THEP Social Room |

Arvind Rajaraman, UC Irvine | |

I will present two studies of flavor physics that can be done at colliders. Firstly, recent anomalies in the decay of B-mesons can be explained by leptoquarks. We argue that models of composite leptoquarks are better motivated, and can produce unique signals at colliders. Secondly, we show that measurements of lepton magnetic moments can be improved by measurements of a rare higgs decay. | |

Sonderzeit und sonderraum: 13.30 at THEP Social Room |

### Theorie-Palaver

Institut für Physik 14:30 Uhr s.t., THEP social room |

Anirban Karan, HBNI, Taramani, India | |

CPT invariance is believed to be a sacred symmetry of nature as well
as quantum field theory (QFT). Therefore, it is very important to test the
validity of this assumption experimentally. Though all the experimental
data is consistent with CPT conservation, improvement in statistics is
expected in LHCb and Belle II. But LHCb cannot use the usual method
of measuring CPT violation through entangled B 0 − B̄ 0 states and a
new technique is required. We found that the time-dependent, indirect
CP asymmetry (A fCP/CP T ) involving B decays to CP eigenstate contains
enough information to measure T and CPT violation in B 0 − B̄ 0 mixing,
in addition to the standard CP-violating weak phases. The advantages of
this method are following:
1. Entangled B 0 − B̄ 0 states are not required (so that this analysis
can be carried out at LHCb, as well as at the B factories),
2. Penguin pollution need not be neglected.
3. This approach can be used in both B d 0 and B s 0 systems.
4. A similar approach can be used for B decaying to two vectors too. |

### Theory of Condensed Matter: Hard Condensed Matter

Institut für Physik, SPICE 14:00 Uhr s.t., Galilei Raum, 01-128 (Staudinger Weg 9) |

George Bourianoff, tba | |

## tba |

### Seminar über Theorie der kondensierten Materie / TRR146 Seminar

10:30 Uhr s.t., Newtonraum, 01-122, Staudingerweg 9 |

Prof. Subir Das, Theoretical Sciences Unit, Jawaharlal Nehru Centre for Advanced Scientific Research, Bangalore | |

## Tug of War between Coarsening and Critical Phenomena: How does an ordering system forget its point of origin? |

### Seminar about Experimental Particle and Astroparticle Physics (ETAP)

Institut für Physik 12:30 Uhr s.t., Staudingerweg 7, Minkowskiraum |

Natalie Wieseotte, ETAP | |

## Higgs Cross Section in VH with H->WW |

### Seminar Festkörper- und Grenzflächenphysik KOMET - experimentell

Institut für Physik 12:15 Uhr s.t., Newton-Raum, Staudingerweg 9, 1. Stock, Raum 122 (Nebengebäude) |

PRELIMINARY DISCUSSION, Institut fuer Physik | |

## VORBESPRECHUNG |

### Theory of Condensed Matter: Hard Condensed Matter

Institut für Physik, SPICE 14:00 Uhr s.t., galilei Raum, 01-128 (Staudinger Weg 9) |

Warlley Campos, JGU | |

## Semi-Transparent Particles in Optical Tweezers: Topological Insulators, Semiconductors and Generalization of the Ashkins Mode |

### Theorie-Palaver

Institut für Physik 14:30 Uhr s.t., MITP room |

Florian Goertz, Max-Planck-Institut für Kernphysik, Heidelberg, Germany | |

I discuss a unified model of scalar particles that addresses the flavour hierarchies, solves the strong CP problem, delivers a dark matter candidate, and provides the trigger for electroweak symmetry breaking. Besides furnishing a unification of the recently proposed axiflavon with a Goldstone-Higgs sector, the scenario can also be seen as adding a model of flavour to elementary Goldstone-Higgs setups.
Including constraints from flavour physics, we find that the model is very predictive, restricting the axion decay constant to a thin stripe of f_a ~ (10^11−10^12) GeV in the minimal implementation. |

### Physikalisches Kolloquium

Institut für Kernphysik, Johann Joachim Becher Weg 45 16 Uhr c.t., HS KPH |

Prof. Dr. Tanja Weil, Max-Planck-Institute for Polymer Research, Mainz | |

Fluorescent nanodiamonds (FNDs) are emerging as promising quantum materials for bio-medical applications and precision sensing due to their unique optical and magnetic proper-ties.[1] They are obtained by implementing elemental defects into the carbon lattice, such as the nitrogen vacancy (N-V), giving unconditionally stable fluorescence without bleaching or blinking even after several months of continuous excitation. The emission wavelength of FNDs is not size-dependent and is tuneable from the visible to the near infrared region according to the elemental defects. In addition, the N-V center in FNDs serves as single-spin sensor[2] that locally detects various physical properties offering great potential for atomic resolution imaging under physiological conditions. The advent of diamond quantum sensing promises solving the longstanding goal of single molecule detection with atomic resolution under ambient condi-tions[1] There is currently no other nanomaterial that would offer such features.
There is an urgent need to prepare high quality N-V diamonds nanodiamonds in a controlled fashion to customize diamond sizes and lattice defects. We present the synthesis of nanodia-monds that paves the way to tailored quantum materials with precisely defined and positioned lattice defects. In addition, functionalization of nanodiamonds is crucial for various applications in biology and medicine. Nanodiamond surface coatings based on biopolymers[3-4] and pro-teins[2,5] will be discussed that provide the basis for quantum sensing and drug delivery in living biological environments. In addition, functionalization of N-V diamonds with proteins or DNA provides access to precisely assembled diamonds on DNA origami to access sophisti-cated quantum devices. |

### PRISMA Colloquium

Institut für Physik 13:00 Uhr s.t., Lorentz-Raum 05-127, Staudingerweg 7 |

Bradley Kavanagh, GRAPPA, University of Amsterdam | |

Searches for particle Dark Matter (DM) in the Solar neighbourhood are rapidly gaining in sensitivity. With underground "direct" detectors, we can search for the nuclear scattering of the fastest DM particles in the Milky Way halo. Instead, using neutrino telescopes, we can probe the Solar capture and subsequent annihilation of the slowest DM particles. Unfortunately, calculating signals and constraints from such experiments depends on the uncertain distribution of DM near the Sun and Earth. Can we robustly account for these uncertainties in experimental analyses? I will present a number of approaches to solving this problem. Even better, I will also show that with a future discovery it should be possible to measure the local velocity distribution of DM and so learn something about the Milky Way and its formation history. I will also discuss ongoing work to show that in certain regions of the DM parameter space, it may be possible to directly measure the local DM density using direct detection alone. This will not only allow us to probe the DM distribution in our local neighbourhood but would also allow us to completely disentangle the astrophysical and particle physics properties of the elusive Dark Matter particle. |

### Seminar über Theorie der kondensierten Materie / TRR146 Seminar

10:30 Uhr s.t., Newtonraum, 01-122, Staudingerweg 9 |

Fabian Berressem, Institut für Physik | |

## Static and Dynamic Properties of Diblock and Multiblock Copolymers | |

Master Kolloquium |

### Institutsseminar Kern- und Hadronenphysik

Institut für Kernphysik 14 Uhr c.t., HS Kernphysik, Becherweg 45 |

Pierre Capel, Mainz | |

￼￼Halo nuclei are among the most exotic quantum structures [1]. Unlike stable nuclei, which are tightly bound compact objects, halo nuclei exhibit an uncommonly large matter radius. This results from their unusual cluster structure. They can be seen as a core, which has all the features of a usual nucleusviz. strongly bound and compactto which one or two neutrons are loosely bound. Thanks to the quantum tunnel effect, the loose binding of these valence nucleons enables them to exhibit a high probability of presence at a large distance from the other nucleons. They thus form like a diffuse halo around a dense core [2].
Halo nuclei are among the most exotic quantal structures [1]. Unlike stable nuclei, which are tightly bound compact objects, halo nuclei exhibit an uncommonly large matter radius. This results from their unusual cluster structure. They can be seen as a core, which has all the features of a usual nucleusviz. strongly bound and compactto which one or two neutrons are loosely bound. Thanks to the quantum tunnel effect, the loose binding of these valence nucleons enables them to exhibit a high probability of presence at a large distance from the other nucleons. They thus form like a diffuse halo around a dense core [2].
Halo nuclei are mostly found close to or even at the neutron dripline, where additional neutrons can no longer be added to an isotopic line. Archetypical examples are 11Be or 15C, which exhibit a one-neutron halo, and 6He or 11Li, which have two neutrons in their halo [1]. Being located so far from stability, halo nuclei exhibit very short half lives and hence cannot be studied with usual spectroscopic techniques, like electron scattering. Their structure must be investigated through indirect techniques. In breakup reactions, the halo nucleus once produced is directly sent on a target. The different interactions its core and its halo neutrons experience with the target will lead to the dissociation of this fragile structure, hence revealing its internal structure.
To extract valuable information from experimental data, an accurate reaction model coupled to a realistic description of the projectile is needed [3]. In this seminar, after a summary on these exotic halo nuclei, I will explain how breakup reactions are modelled and how we can, thanks to Effective Field Theory, relate the most accurate ab initio calculations of halo nuclei to breakup cross sections and as such explore the structure of nuclei far from stability.
[1] I. Tanihata, J. Phys. G, 22, 157 (1996)
[2] P.G. Hansen and B. Jonson, Europhys. Lett. 4, 409 (1987)
[3] D. Baye and P. Capel, Lecture Notes in Physics 848, 121 (2012) |

### Seminar über Theorie der kondensierten Materie / TRR146 Seminar

14:00 Uhr s.t., Newtonraum, 01-122, Staudingerweg 9 |

Prof. Dr. Yacov Kantor, Tel Aviv University | |

## Energy vs. Entropy: Polymers near Repulsive and Attractive Wedges |

### Theorie-Palaver

Institut für Physik 14:30 Uhr s.t., THEP social room |

Mikhail Gorshteyn, Institut fr Kernphysik, JGU, Mainz, Germany | |

Radiative corrections to neutron beta-decay have been fundamental for establishing the
electroweak model. Universality of the weak interaction and conservation of vector current lead to the
requirement of unitarity of the CKM mixing matrix. Unitarity in the first row, |V_{ud}|^2+|V_{us}|^2+|V_{ub}|^2=1
belongs to the most stringent tests of the Standard Model and beyond. Current PDG value is in good
agreement with unitarity, |V_{ud}|^2+|V_{us}|^2+|V_{ub}|^2=0.9994 +- 0.0005, and the central value
and the uncertainty are dominated by those due to the upper-left corner element |V_{ud}|=0.97420(10)_{exp}(18)_{th},
which is obtained from analysis of superallowed nuclear decays. The uncertainty of V_{ud} is dominated
by the theoretical uncertainty related to the gamma-W-box diagram which depends on hadronic and
nuclear structure. The hadronic part has been addressed by Marciano and Sirlin, while the nuclear part
by Towner and Hardy. To test previous analyses, we applied dispersion relations to the calculation of the
gamma-W-box correction, and used data on neutrino and antineutrino scattering to better constrain
the input in the dispersion integral. We were able to reduce the hadronic uncertainty by almost a factor 2,
|V_{ud}|=0.97366(10)_{exp}(11)_{th}. However, the central value shifted considerably, raising tension
with unitarity, |V_{ud}|^2+|V_{us}|^2+|V_{ub}|^2=0.9984 +- 0.0004. Ongoing work is concentrated on
proposing new measurements with polarized electrons and neutrinos to test our new analysis in a more
direct and model-independent way, and on reevaluating the nuclear structure corrections within the
dispersive framework. |

### PRISMA Colloquium

Institut für Physik 13:00 Uhr s.t., Lorentz-Raum 05-127, Staudingerweg 7 |

Kathrin Valerius, KIT, Karlsruhe | |

The mass scale of neutrinos remains one of the fundamental open questions in modern physics, with far-reaching implications from particle physics to cosmology.
Precision measurements of the kinematics of weak interactions, in particular tritium beta decay and electron capture in 163Ho, offer the only model-independent (direct) approach to access the neutrino mass scale in a laboratory experiment.
The currently most mature technique relies on the spectroscopy of tritium beta decay near its kinematic endpoint at 18.6 keV. The KArlsruhe TRItium Neutrino experiment (KATRIN) is targeted at improving the sensitivity of this method by an order of magnitude to 200 meV (90% C.L.). To this end, KATRIN utilises an ultra-luminous windowless gaseous tritium source and a high-resolution electrostatic spectrometer.
In this talk I will present results of the First Tritium campaign in which the full 70-m long beam line of KATRIN was successfully inaugurated in summer 2018, demonstrating the precision spectroscopy performance and stability of the overall system. I will furthermore report on the current final steps of preparing the KATRIN apparatus and the analysis chain for first neutrino-mass measurements starting next spring. |

### Seminar über Quanten-, Atom- und Neutronenphysik (QUANTUM)

Institut für Physik 14 Uhr c.t., Lorentz-Raum (05-127), Staudingerweg 7 |

Prof. Dr. Hartmut Häffner, University of California, Berkeley, USA | |

Many important chemical and biochemical processes in the condensed phase are notoriously difficult to simulate numerically. Often, this difficulty arises from the complexity of simulating dynamics resulting from coupling to structured, mesoscopic baths, for which no separation of time scales exists and statistical treatments fail. A prime example of such a process is vibrationally assisted charge or energy transfer. A quantum simulator, capable of implementing a realistic model of the system of interest, could provide insight into these processes in regimes where numerical treatments fail. We take a first step towards modeling such transfer processes using an ion-trap quantum simulator. By implementing a minimal model, we observe vibrationally assisted energy transport between the electronic states of a donor and an acceptor ion augmented by coupling the donor ion to its vibration. We tune our simulator into several parameter regimes and, in particular, investigate the transfer dynamics in the nonperturbative regime often found in biochemical situations. |

### Seminar über Quanten-, Atom- und Neutronenphysik (QUANTUM)

Institut für Physik Sonderseminar: 09 Uhr c.t., Medienraum (03-431) Staudingerweg 7 |

Dr. Jiehang Zhang, Joint Quantum Institute, University of Maryland, College Park, USA | |

Trapped ions are ideal candidates for engineering quantum systems with individual resolution. Qubits are encoded with the internal levels of the ions, and controlled with laser-driven interactions. Such a system present an excellent coherence time and can find wide applications in quantum simulations and quantum computing. I will present recent experiments using these systems to study non-equilibrium matter, including discrete time-crystals [1], as well as dynamical phases [2]. A spin chain with individual resolution for more than 50 qubits enables many applications such as quantum sampling and optimization.
[1] J. Zhang, et al., Nature 543, 217220 (2017).
[2] J. Zhang, et al., Nature 551, 601604 (2017). | |

Sonderseminar |

### Theory of Condensed Matter: Hard Condensed Matter

Institut für Physik, SPICE 10:00 Uhr s.t., Galileo Room, 01-128 |

Imke Schneider, Technical University Kaiserslautern | |

The effects of impurities in quasi one-dimensional quantum systems are recently experiencing a renewed interest due to experimental realizations in solid state systems and ultra-cold gases. Due to spatial confinement impurities have strong impact on the magnetic excitation spectrum and transport properties in one dimension. Already the smallest generic scatterer can block the electric or magnetic conductance which leads to effectively isolated finite chain segments with discrete energies and characteristic boundary correlations. Surprisingly, relatively little is known about impurity effects on the momentum- and frequency resolved dynamical response functions as for example the dynamical structure factor in spin-1/2 Heisenberg chains. Using bosonization and the numerical Density Matrix Renormalization Group we provide detailed quantitative predictions for the momentum and energy resolved structure factor in doped spin chains. Due to the impurities, spectral weight is shifted away from the antiferromagnetic wave-vector k = π into regions which normally have no spectral weight in the thermodynamic limit. As another example of impurity physics in one dimension we consider simple intersections between one-dimensional quantum wires. These can act as coherent beam splitters for non-interacting electrons. Here we examine how coherent splitting at such quantum wire crossings is affected by inter-particle interactions. |

### Theorie-Palaver

Institut für Physik 14:30 Uhr s.t., MITP seminar room |

Da Huang, University of Warsaw | |

We connect the electroweak (EW) baryogenesis and the dark matter
physics in a complex singlet scalar S extension of the Standard Model.
We impose the additional CP and Z_2 symmetries on the scalar
potential. With the complex vacuum expectation value of S at the
temperature higher than the EW phase transition, the CP symmetry is
spontaneously broken and a strong first-order EW phase transition is
easily realized. Together with a dimension-6 effective operator that
gives new complex contributions to the top quark mass, we show that it
is easy to yield the observed baryon asymmetry in our Universe. On the
other hand, the CP and Z_2 symmetries are recovered after the EW phase
transition. The lighter real state in S can be the dark matter
candidate, and the strong constraints of CP violations can be avoided.
With the scan of parameter space, we can find models which can explain
the dark matter relic abundance and the baryon asymmetry
simultaneously while satisfying all constraints. |

### Physikalisches Kolloquium

Institut für Kernphysik, Johann Joachim Becher Weg 45 16 Uhr c.t., HS KPH |

Prof. Dr. Jan-Michael Rost, Max-Planck-Institut für Physik komplexer Systeme, Dresden | |

Highly excited "Rydberg" systems play an important role for progress in theory, experiment, and more recently for potential applications in quantum computing.
Rydberg systems connect ultracold physics, condensed and atomic/molecular physics and also non-linear (semi-)classical dynamics on the theoretical side.
In the talk I will illustrate this progress with exotic Rydberg systems from antiprotonic helium to ultralong-range Rydberg molecules with several thousand atomic units bond length. Immersed in their natural environment of an ultracold gas those molecules thrive through the presence of many randomly located gas atoms - a surprising and counterintuitive result. It is rooted in a novel scarring phenomenon of excited quantum wave functions and the fact that a random gas contains clusters of atoms, a phenomenon more broadly known as "birthday paradoxon". |

### Seminar about Experimental Particle and Astroparticle Physics (ETAP)

Institut für Physik 12:30 Uhr s.t., Staudingerweg 7, Minkowskiraum |

Matthias Schott, ETAP | |

## Axion Searches |

### Theory of Condensed Matter: Hard Condensed Matter

Institut für Physik, SPICE 14:00 Uhr s.t., Galilei Room, 01-128 (Staudinger Weg 9) |

Markus Drescher, Universitt Hamburg | |

Tunnelling spectroscopy has been proven to be a powerful means to determine fundamental properties of superconductors such as the density of states, with scanning tunnelling microscopy (STM) allowing for a high spatial resolution. However, data from STM experiments can in general only be understood comprehensively by taking into account both elastic and inelastic tunnelling processes. In inelastic tunnelling events, the tunnelling of the electron leads additionally to the excitation or annihilation of collective bosonic modes such as phonons in the sample.
We extend the theory of STM spectroscopy in superconductors by assuming that both the sample and the tip are in the superconducting regime and explore the characteristics of the system if inelastic tunnelling is taken into account. Besides applying a constant voltage between sample and tip, we also consider an alternating sinusoidal voltage, leading to Shapiro-like effects.
All interested are cordially welcome! |

### Theorie-Palaver

Institut für Physik 14:30 Uhr s.t., MITP seminar room |

Gabor Somogyi, University of Debrecen | |

The excellent performance of the LHC experiments and the wealth of precise
data they deliver requires that the challenge of high precision also be addressed
in the theory calculations used to describe the measurements. One aspect of
theoretical precision is related to the computation of exact higher order corrections
to physical observables in QCD perturbation theory. As the mass production of
two-loop amplitudes is becoming a reality, frameworks and tools to organize
computations at next-to-next-to-leading order (NNLO) accuracy must also be
developed. In the talk I will present the CoLoRFulNNLO method for calculating
fully differential predictions at NNLO in QCD. After addressing the key conceptual
issues which arise in the construction of the method, I will discuss the status of
extending the scheme to deal with initial state radiation, pointing out some technical
issues specific to this approach which must be addressed. I will also show some
applications of the CoLoRFulNNLO framework, in particular, I will discuss a new
measurement of the strong coupling from measurements of energy-energy correlation
in electron-positron collisions, as well as a full NNLO computation of the associated
production of a Higgs boson decaying into bottom quarks at the LHC. |

### Physikalisches Kolloquium

Institut für Kernphysik, Johann Joachim Becher Weg 45 16 Uhr c.t., HS KPH |

Prof. Dr. Naohito Saito, Japan Proton Accelerator Research Complex (J-PARC), Japan | |

A precision measurement of muon dipole moments have been playing important role to test the standard model of particle physics in the past and to shape the new physics in recent years. We plan to launch an experiment to perform precision measurements of the muon anomalous magnetic moment (aka "g-2") and electric dipole moment with a novel technique at Japan Proton Accelerator Research Complex, J-PARC. This experiment requires a muon source with very small emittance, muon acceleration, spiral injection of the muon beam into super-precision magnetic field with 66-cm diameter and high-rate tracking system. The current status and prospect of the experiment will be described in this seminar. |

### PRISMA Colloquium

Institut für Physik 13:00 Uhr s.t., Lorentz-Raum 05-127, Staudingerweg 7 |

Gudrun Hiller, TU Dortmund | |

implications of the exciting hints for lepton-nonuniversality seen in ratios of rare B decays into muons and electrons at LHCb are discussed.
Iff indeed true and confirmed with more data in the future at the LHC and Belle II, this would constitute a spectacular breakdown of the standard model.
Leptoquarks provide natural explanations of the anomalies as they carry lepton and quark flavor charges and thus generically can induce
nonuniversality, and lepton flavor violation. B-physics data point to masses from just around the corner, at the present search limits, to the few multi-TeV range,
while viable flavor models suggest few TeV. Collider signatures are discussed. In the second part of the talk we discuss possibilities to test LNU and look for New Physics
more generally with rare charm decays. While dominated by hadronic resonances we point out opportunities with Null tests to learn about flavor in the up-decotr, complementing
ongoing programs with kaons and B-decays. |

### Seminar über Quanten-, Atom- und Neutronenphysik (QUANTUM)

Institut für Physik 14 Uhr c.t., Lorentz-Raum (05-127), Staudingerweg 7 |

Prof. Dr. Andrey Surzhykov, Fundamentale Physik der Metrologie, PTB Braunschweig | |

During the recent years light beams with a helical phase front, that also carry orbital angular momentum (OAM) have been in the focus of experimental and theoretical studies. Today, such twisted beams are routinely produced across the electromagnetic spectrum, with photon energies ranging from meV to hundreds of eV. Twisted light is used for multiplexing in optical communications, for manipulating microparticles, and for studying the angular momentum transfer to atoms, molecules or even BEC's. In my talk, I will review recent theoretical advances in studying fundamental light-matter interaction processes such as the photon absorption and atomic photoeffect. We will discuss, in particular, how the OAM of twisted photons can affect the selection rules of bound-state radiative transitions as well as the angular distribution of emitted photoelectrons. | |

Vortrag im Rahmen des SFB/TR 49-Kolloquiums |

### Theorie-Palaver

Institut für Physik Sonderseminar: 13:30 Uhr s.t., THEP social room |

Tilman Plehn, Heidelberg University | |

Machine Learning techniques have been used at the LHC for a long time. Jet
sub-structure has become an especially active field to test new ideas in this
direction. I will discuss how jet sub-stucture has become an established concept
in the last decade and in which sense machine learning is the next logical step
in this field. Specifially, top tagging has many applications in searches for
physics beyond the Standard Model. It allows us to to test different approaches,
benchmark new architectures and tools, understand how deep learning tools actually
work, and illustrate the conceptual progress we can expect in jet analyses in the
coming years. | |

Sonderseminar |

### Seminar about Experimental Particle and Astroparticle Physics (ETAP)

Institut für Physik 12:30 Uhr s.t., Staudingerweg 7, Minkowskiraum |

Uwe Oberlack, ETAP | |

## Direct Dark Matter Searches |

### Theory of Condensed Matter: Hard Condensed Matter

Institut für Physik, SPICE 14:00 Uhr s.t., Galilei Room, 01-128 (Staudinger Weg 9) |

Inti Sodemann, Max-Planck-Institut fr Physik komplexer Systeme Dresden | |

The Hall effect is often thought to be a hallmark of broken time reversal invariance. I will describe how a Hall-like effect can appear beyond linear response theory in time reversal symmetric metals. These metals can have a non-linear Hall effect that is controlled by the "Berry curvature dipole": an average of the gradient of the Berry curvature over the occupied states. I will describe recent experimental observation of this effect in 2D materials and our predictions for the effect in 3D materials, including Weyl semimetals. I will also comment on the role of other extrinsic mechanisms and on an ongoing effort to try to understand the Berry dipole as a kind non-linear version of the Drude weight. If time permits, I will also describe our recent predictions of a novel shear collective mode in strongly interacting metals. |

### Theorie-Palaver

Institut für Physik 14:30 Uhr s.t., MITP seminar room |

Pablo Quilez, IFT-UAM/CSIC, Universidad Autonoma de Madrid | |

I will review recent attempts to build heavy axion models which solve the strong CP problem while enlarging the parameter space well beyond that of invisible axion models. I will also discuss new theoretical and phenomenological results on the axion and ALP parameter space axion couplings to photons, Z and W bosons. Next, I will present a recent model of heavy axions: the first axion model solving the strong CP problem with colour unification and massless fermions. The axion scale may be not far from the TeV region which translates to observable signals at colliders. |

### PRISMA Colloquium

Institut für Physik 13:00 Uhr s.t., Lorentz-Raum 05-127, Staudingerweg 7 |

David Marsh, Universität Göttingen | |

Axions are a hypothetical class of particle which may constitute all, or a part of, the dark matter in the Universe. Due to their unique symmetry properties, they are the lightest viable dark matter candidate, with the mass possibly being as low as 1e-22 eV. I will discuss how this lower limit is derived from observations of the cosmic microwave background anisotropies, and the abundance of galaxies at high redshift, and the observed spin distribution of supermassive black holes. At the lower mass limit, axions manifest novel wavelike behaviour in the inner regions of galaxies that can be used to search for evidence of them in stellar motions. Direct detection of such ultralight axions is extremely challenging, and I will discuss some ideas. |

### Seminar about Experimental Particle and Astroparticle Physics (ETAP)

Institut für Physik 12:30 Uhr s.t., Staudingerweg 7, Minkowskiraum |

Anna Rosmanitz, ETAP | |

## Data Analysis of the CALICE Prototype |

### Theory of Condensed Matter: Hard Condensed Matter

Institut für Physik, SPICE 14:00 Uhr s.t., Galilei Room, 01-128 (Staudinger Weg 9) |

Tobias Meng, Technische Universitt Dresden | |

Weyl semimetals are defined by the presence of isolated points in the Brillouin zone at which a conduction and a valence band touch. The so-called Nielsen-Ninomiya theorem requires these points (the Weyl nodes) to appear in pairs. This theorem, however, is only valid for interactions of sufficiently short range. In this talk, I will discuss that long-range interactions can break the Nielsen-Ninomiya-theorem, and provide an explicit construction for an interacting tight-binding model that contains only a single Weyl node. I will then analyze the fate of the chiral anomaly in such single Weyl node semimetals, and demonstrate that the chiral magnetic effect remains intact for arbitrarily strong interactions in such a single node Weyl semimetal, while it is at most robust up to a critical interaction strength if the interaction gaps all Weyl nodes. |

### Theorie-Palaver

Institut für Physik 14:30 Uhr s.t., MITP seminar room |

Jiayin Gu, JGU Mainz | |

We study the reach on the Higgs coupling constraints at future lepton colliders in a global effective-field-theory framework. The impact and complementarity of different measurements, at different center-of-mass energies and for several beam polarization configurations, are discussed in detail. We also study the sensitivities to the Higgs self-coupling at future lepton colliders under this framework. |

### PRISMA Colloquium

Institut für Physik 13:00 Uhr s.t., Lorentz-Raum 05-127, Staudingerweg 7 |

Sebastian Kempf, KIP Heidelberg | |

Neutrinos, and in particular their tiny but non-vanishing masses, are presently considered to be a very promising experimental playground to study physics beyond the Standard Model. Precision studies of the kinematics of weak interactions such as the 3H β-decay and the 163Ho electron capture (EC) represent the only model independent approach to determine the absolute scale of neutrino masses. The electron capture in 163Ho experiment, ECHo, aims to investigate the electron neutrino mass with sub-eV/c2 sensitivity by performing a calorimetric measurement of the electron capture spectrum of the nuclide 163Ho. The maximum energy available for this decay is about 2.8 keV and constrains the type of detectors that can be used. It strongly suggests to employ metallic magnetic calorimeters (MMCs) since they provide an excellent energy resolution, a very fast signal rise time, an almost ideal linear detector response as well as a quantum efficiency close to 100%. A metallic magnetic calorimeter consists of an absorber for the particles to be detected that is in tight thermal contact with a paramagnetic temperature sensor situated in a weak magnetic field to create a temperature dependent sensor magnetization. The temperature change upon the absorption of an energetic particle, e.g. an electron created within an EC event of 163Ho, results in a change of sensor magnetization which can be precisely measured using a superconducting quantum interference device (SQUIDs). To achieve the target sensitivity on the electron neutrino mass, ECHo will operate large MMC arrays with more than 104 detectors. However, this large number of detectors sets constraints on the SQUID readout technique to be employed. In particular, it prohibits the use of single-channel readout schemes due to limitations on available cooling power, system complexity and costs. Therefore, sophisticated microwave SQUID based multiplexing techniques for the readout of MMCs are presently developed.
Within this talk, we will give a short introduction into the ECHo experiment as well as the fundamentals of metallic magnetic calorimeters. We then extensively discuss the basics and realization of SQUID based readout techniques presently used in the ECHo experiment as well as recent developments paving the way for performing a 163Ho based experiment with sub-eV/c2 sensitivity. |

### Seminar über Theorie der kondensierten Materie / TRR146 Seminar

10:30 Uhr s.t., Newtonraum, 01-122, Staudingerweg 9 |

Giang Thi Vu, Institut fr Physik | |

## Phase behavior of diblock copolymers in thin films and membranes |

### Seminar about Experimental Particle and Astroparticle Physics (ETAP)

Institut für Physik 12:30 Uhr s.t., Staudingerweg 7, Minkowskiraum |

Sophio Pataraia, ETAP | |

## Introduction to statistics and statistical tools & the HistFitter framework |

### Institutsseminar Kern- und Hadronenphysik

Institut für Kernphysik 14 Uhr c.t., HS Kernphysik, Becherweg 45 |

Laura Moschini, Bruxelles | |

Aside from being a one-neutron halo nucleus, 15C is an interesting
nuclear system because it is involved in reactions of relevance for
several nucleosynthesis scenarios such as inhomogeneous Big Bang models,
neutron induced CNO cycles, and neutrino driven wind models for the
r-process.
The aim of this work is to provide good predictions for various
reactions involving 15C, using a single structure model.
So, first we determine the 15C structure within an Halo-EFT description [1] reproducing both the one-neutron binding energy of 15C ground state and the asymptotic normalization coefficient (ANC), fixed through the analysis of the 14C(d,p)15C transfer reaction at 17.06 MeV [2]. Then, we study the 15C breakup at intermediate (68 MeV/nucleon) and high energy (605 MeV/nucleon) using an eikonal model with a consistent treatment of nuclear and Coulomb interactions at all orders, which takes into account proper relativistic corrections. The former was measured at RIKEN [3], while the latter was measured at GSI [4]. Finally, we study the 14C(n,γ)15C radiative capture comparing our results to direct measurements performed by Reifarth et al. [5]. We find that our theoretical predictions are in good agreement with the experimental data for each reaction, thus assessing the robustness of the structure model provided for this nucleus. We show the importance of the inclusion of relativistic corrections in the case of the breakup at high energy, and we confirm the small contribution of the 15C d wave in the continuum in the neutron capture cross section of 14C.
[1] H.-W. Hammer, C. Ji, and D. R. Phillips, J. Phys. G 44, 103002 (2017)
[2] A. M. Mukhamedzhanov et al., Phys. Rev. C 84, 024616 (2011)
[3] T. Nakamura et al., Phys. Rev. C 79, 035805 (2009)
[4] U. Datta Pramanik et al., Phys. Lett. B 551, 6370 (2003)
[5] Reifarth et al., Phys. Rev. C 77, 015804 (2008) |

### Theory of Condensed Matter: Hard Condensed Matter

Institut für Physik, SPICE 14:00 Uhr s.t., Lorentz Room 05-127 (Staudingerweg 7) |

Assa Auerbach, Department of Physics, Technion, Israel | |

In metals, transport coefficients involve non-adiabatic relaxational dynamics which are in general, much harder to compute than equilibrium susceptibilities.
In this talk I present three formulas derived from Kubo formula [1], for DC transport coefficients which can be expressed as sums of equilibrium susceptibilities: (1) The Hall coefficient, (2) A modified Nernst coefficient, and (3) The Thermal Hall coefficient. The formulas are valid for general Hamitlonians and can treat bad metals where Boltzmann theory ceases to be valid. I show new results for the Hall coefficients of the square lattice t-J model, and of lattice bosons near the Mott insulator phases.
1. Hall Number of Strongly Correlated Metals, A. Auerbach, Phys. Rev. Lett. 121, 066601 (2018) |

### Seminar über Theorie der kondensierten Materie / TRR146 Seminar

Sonderseminar: 14:15 Uhr s.t., Gernot Gräff Raum, 5th floor, Room 05-431, Staudingerweg 7 |

Dr. Benjamin Rotenberg, Laboratoire PHENIX, Sorbonne Université, Paris | |

Simulations of fluids, regardless of the level of description, usually use periodic boundary conditions. This introduces biases in the computation of physical properties. For example, the diffusion coefficient depends on the size of the simulation box. Yeh and Hummer demonstrated the hydrodynamic origin of this effect and obtained an analytical expression to correct for this bias in the case of cubic boxes [1]. In this talk, I will review the main results of this pioneering study as well as some consequences and extensions on which we have worked in the recent years. After analyzing this effect for various water models [2], we showed the influence of the box shape, in addition to its size [3] before turning to the case of confined fluids [4]. Finally, we analyzed finite size effects on the transient regime using Lattice Boltzmann simulations [5]. In all cases, the hydrodynamic origin allows us to evaluate the correction to be applied to simulations (molecular as well as mesoscopic). I will also mention recent work from other groups on membrane dynamics as well as rotational dynamics. [1] Yeh et Hummer, J. Phys. Chem. B 108 15873 (2004). [2] Tazi et al, J. Phys. Cond. Matt., 24, 284117 (2012). [3] Botan et al, Mol. Phys., 113, 2674 (2015). [4] Simonnin et al, J. Chem. Theory Comput., 13, 2881 (2017). [5] Asta et al, Phys. Rev. E, 95, 061301 (2017). | |

Sonderseminar |

### Theorie-Palaver

Institut für Physik 14:30 Uhr s.t., THEP social room |

Luc Darme, NCBJ Warsaw | |

Minimal self-consistent scenarios with light (sub-GeV) dark matter are usually accompanied by a correspondingly light "dark sector". The presence of the latter leads to bright detection prospects at fixed target experiments and colliders and potentially strong astrophysical bounds. We will illustrate this point by exploring explicitly a typical simple fermion dark matter setup, showing in particular that the presence of an often long-lived dark Higgs boson is a key element of the phenomenology. |

### Physikalisches Kolloquium

Institut für Kernphysik, Johann Joachim Becher Weg 45 16 Uhr c.t., HS KPH |

Prof. Dr. Regine von Klitzing, Technische Universität Darmstadt | |

The presentation addresses ordering phenomena of Silica suspensions under confinement in a Colloidal Probe AFM (CP-AFM). The wavelength λ scales with the particle number density as λ=ρ-1/3. An extrapolation towards high volume fractions shows that the ρ-1/3 scaling law for λ ends up into a cubic lattice found for one-component systems like organic solvents, where λ=d (d: diameter of molecules, particles etc.). A deviation from the exponentially decaying cosine function was found and can be described by an additional repulsion term [2,3] which will be discussed. Furthermore, it will be shown how oscillatory forces can be switched on and off by external stimuli [4].
Partially hydrophobized Silica particles order laterally at the interfaces of a free-standing film. They can form percolation networks which seem to stabilize foam films and even foams, i.e. so called Pickering foams |

### Seminar über Theorie der kondensierten Materie / TRR146 Seminar

10:30 Uhr s.t., Newtonraum, 01-122, Staudingerweg 9 |

Fabian Koessel, Institut fr Physik | |

## A kinetic theory of magnetic, active suspensions |

### Seminar über Quanten-, Atom- und Neutronenphysik (QUANTUM)

Institut für Physik 14 Uhr c.t., MITP-Seminarraum, 02-430, Staudingerweg 9 (Nachbargebäude) |

Dr. Hendrick L. Bethlem, Vrije Universiteit, Amsterdam, The Netherlands | |

We use electric fields to cool and manipulate polar molecules and use these cold molecules to perform precision tests of fundamental physics theories and collisions studies. I will present two experiments; in the first experiment we let beams of argon atoms collide with ammonia molecules that are stored in a synchrotron. Using a synchrotron has the advantage that the collision partners move in the same direction, resulting in a low collision energy. Furthermore, by storing molecules many roundtrips the sensitivity to collisions is greatly enhanced [1]. In the second experiment beams of ammonia molecules are decelerated, trapped, cooled and subsequently launched upwards with a velocity between 1.4 and 1.9 m/s. Molecules with this speed will fly up 60-180 mm before falling back under gravity. We have demonstrated field-free interaction times up to 266 millisecond, two orders of magnitude longer than has been achieved with molecular beams [2]. Finally, I will discuss a new project, conducted in collaboration with the University of Groningen, to cool barium-fluoride molecules and use these to search for the electric dipole moment of the electron which is a sensitive probe for physics beyond the standard model [3].
References
[1] Cold Collisions in a Molecular Synchrotron, A.P.P. van der Poel, P.C. Zieger, S.Y.T. van de Meerakker, J. Loreau, A. van der Avoird, and H.L. Bethlem, Phys. Rev. Lett. 120, 033402 (2018).
[2] Molecular Fountain, C. Cheng, A.P.P. van der Poel, P. Jansen, M. Quintero-Prez, T.E. Wall, W. Ubachs, and H.L. Bethlem, Phys. Rev. Lett. 117, 253201 (2016).
[3] Measuring the electric dipole moment of the electron in BaF, NL-eEDM collaboration,
Eur. Phys. J. D. 72, 197 (2018). | |

Achtung Raumänderung, da gemeinsames Kolloquium mit NPCCM Meeting |

### Seminar about Experimental Particle and Astroparticle Physics (ETAP)

Institut für Physik 12:30 Uhr s.t., Staudingerweg 7, Minkowskiraum |

Marisol Robles Manzano, ETAP | |

## Flexible PCB Design for a High-Granularity Timing Detector |

### Institutsseminar Kern- und Hadronenphysik

Institut für Kernphysik 14 Uhr c.t., HS Kernphysik, Becherweg 45 |

Luca Doria, Mainz | |

## Dark Matter searches at the intensity frontier |

### Theorie-Palaver

Institut für Physik 14:30 Uhr s.t., MITP seminar room |

Javi Serra, Technical University of Munich | |

The unitarity, analyticity and Poincare invariance of a microscopic theorys S-matrix leaves its imprints at low energies as constraints on the Wilson coefficients of the resulting effective field theory (EFT). In this talk I will discuss the implications of such bounds on various EFTs in particle physics and cosmology, including strongly coupled fermions and vectors, massive gravity, and higher-spin theories. |

### Physikalisches Kolloquium

Institut für Kernphysik, Johann Joachim Becher Weg 45 16 Uhr c.t., HS KPH |

Prof. Dr. Steven Johnson, ETH Zürich Institute for Quantum Electronics | |

The original experiments showing what is now called the Einstein-de Haas effect were a critical demonstration in early modern physics of the equivalence of angular momentum in electronic spins and mechanical angular momentum. Here I discuss a recent experiment where we investigate using femtosecond x-ray diffraction the dynamics of the Einstein-de Haas effect on picosecond time scales, along the way showing definitively that the long-studied but poorly understood phenomenon of ultrafast demagetisation in ferromagnetic iron involves a sub-picosecond time scale transfer of angular momentum from the spin system to the lattice. |

### PRISMA Colloquium

Institut für Physik 13:00 Uhr s.t., Lorentz-Raum 05-127, Staudingerweg 7 |

Anna Franckowiak, DESY | |

The recent discovery of high-energy astrophysical neutrinos has opened a new window to the Universe. Identifying the sources of those neutrinos is the most pressing question in the new field of neutrino astronomy. Combining neutrino data with electromagnetic measurements in a multi-messenger approach increases the sensitivity to identify the neutrino sources and helps to solve long-standing problems in astrophysics such as the origin of cosmic rays.
A first compelling candidate was identified on September 22, 2017, when the IceCube Neutrino Observatory observed an extremely high-energy neutrino, IceCube-170922, in spatial and temporal coincidence with a gamma-ray flaring blazar, TXS 0506+056, monitored by the Fermi Large Area Telescope. The coincidence triggered a large follow-up campaign in a broad wavelength band.
In this talk I will review the recent progress in multi-messenger astronomy using neutrino data with a focus on the candidate source, TXS 0506+056. |

### Seminar über Theorie der kondensierten Materie / TRR146 Seminar

10:30 Uhr s.t., Newtonraum, 01-122, Staudingerweg 9 |

Matthias Nebouy, MATEIS INSA Lyon | |

## Describing the structure of thermoplastic elastomers : A dual approach using experiments and molecular dynamics |

### SFB/TR49/SFB TRR 173 Spin+X-Kolloquium - Seminar experimentelle Physik der kondensierten Materie

SFB/TR49 - Prof. Dr. Elmers Sonderseminar: 14:15 Uhr s.t., Gernot-Graeff-Raum, Staudinger Weg 7, 05-431 |

Prof. Istvan Kezsmarki, Experimental Physics V, Center for Electronic Correlations and Magnetism, University of Augsburg | |

Multiferroics permit the magnetic control of the electric polarization and the electric control of the magnetization. These static magnetoelectric (ME) effects are of enormous interest: The ability to read and write a magnetic state current-free by an electric voltage would provide a huge technological advantage. Dynamic or optical ME effects are equally interesting, because they give rise to unidirectional light propagation as recently observed in several multiferroic compounds [1-5].
In conventional media the propagation of waveslight, magnons and phononsis reciprocal, that is counter-propagating waves experience the same material properties. However, reciprocity can be violated in multiferroic materials, where the velocity and the attenuation depend on the ±k direction of the wave propagation [1]. Such non-reciprocal propagation can be the consequence of e.g. the dynamic magnetoelectric effect emerging in materials with simultaneously broken time reversal and spatial inversion symmetries. Recently, the non-reciprocal wave propagation has also been observed in multi-antiferroics [6], i.e. in materials with coexisting purely antiferroelectric and antiferromagnetic orders. The symmetry-based guidance for the synthesis of multi-antiferroics and the connection to antiferromagnetic spintronics will also be discussed. | |

Sonderseminar |

### Seminar Festkörper- und Grenzflächenphysik KOMET - experimentell

Institut für Physik 12:00 Uhr s.t., Newton-Raum, Staudingerweg 9, 1. Stock, Raum 122 (Nebengebaeude) |

Thomas Winkler, Institut fuer Physik | |

Magnetic skyrmions are potential candidates for next generation storage or
computing devices and so a highly interesting field of research. Stable skyrmions
at room temperature are a requirement for customer devices, so the tempera-
ture dependency of skyrmion dynamics is important to understand. To simulate
magnetization dynamics fast and accurate at the same time, a multiscale ap-
proach of the software package micromagnum [1] was developed by Andrea de
Lucia [2], which allows to embed a Heisenberg model into an micromagentic
simulation in areas where such precision is needed. A GPU-based version is un-
der construction which allows to simulate large skyrmions with that multiscale
approach. Computational post-processing of measurement data is an impor-
tant field, which is worth to get optimized. An adoption of the U-Net [3], a
neural network for biomedical image segmentation, is presented. It hopefully
allows the detection and tracking of skyrmion movement from measurement
data faster and easier than with the existing methods in the group. |

### Theory of Condensed Matter: Hard Condensed Matter

Institut für Physik, SPICE 14:00 Uhr s.t., Galilei Room, 01-128 (Staudinger Weg 9) |

Maxime Garnier, Laboratoire de Physique des Solides, Universit Paris-Sud | |

Magnetic skyrmions are nanoscale particle-like spin configurations that are efficiently created and manipulated. They hold great promises for next-generation spintronics applications. In parallel to thesedevelopments, the interplay of magnetism, superconductivity and spin-orbit coupling has proved to be a versatile platform for engineering topological superconductivity predicted to host non-abelianexcitations, Majorana zero modes (MZMs).
In this talk, after an introduction to topological superconductivity and a quick survey of the experimental status of MZMs, I will focus on the theoretical analysis of magnetic skyrmions proximitized by conventional superconductors. We show that a topological superconducting phase can emerge in these systems and uncover a whole flat band of these modes on the edge of the magnetic texture, in contrast to a previously reported MZM in the core of the skyrmion [1]. I will discuss in details the origin of these MZMs based on a procedure introduced in [2] that relates our problem to the the extensively-studied Rashba nanowire model [3, 4]. We find that these modes are remarkably stable to electronic and geometric perturbations which we investigate by a combination of analytical arguments and numerical tight-binding calculations. Additionally, this analysis reveals that the number of MZMs on the edge scales linearly with its perimeter. I will then discuss possible experimental realizations and consequences of this phenomenon and argue that this system is suitable for the realization of the topological Kondo effect and of electron teleportation.
[1] G. Yang, P. Stano, J. Klinovaja & D. Loss, PRB 93, 224505 (2016). [2] F. Wu & I. MArtin, PRB 95, 224503 (2017).
[3] R. M. Lutchyn, Jay D. Sau & S. Das Sarma, PRL 105, 077001 (2010). [4] Y. Oreg, G. Refael & F. von Oppen, PRL 105, 177002 (2010) |

### Theorie-Palaver

Institut für Physik 14:30 Uhr s.t., MITP seminar room |

Wouter Waalewijn, University of Amsterdam | |

Electroweak corrections are important for BSM searches, as they can modify the tails of distributions. I will present a framework to resum electroweak logarithms in inclusive processes, that enables resummation beyond leading logarithmic accuracy. Interestingly, this is not simply achieved by the electroweak evolution of PDFs and fragmentation functions, but also involves soft functions. This introduces a dependence on angles and leads to mixing. I will also discuss a few extensions, including jets, and discuss the electroweak gauge boson PDFs. |

### Physikalisches Kolloquium

Institut für Kernphysik, Johann Joachim Becher Weg 45 16 Uhr c.t., HS KPH |

Prof. Lawrence Wald, Ph.D., Harvard Medical School & Massachusetts General Hospital | |

The textbook formulation of MRI is typically framed with uniform fields, well-controlled linear gradients and stationary objects. If violated, corrections are imposed to nudge the data back into the proper form. If instead we replace image reconstruction with a more general optimization-based strategy, the increased computational burden can buy us important benefits. We show the potential of moving in this direction in three experiments; a fast imaging method otherwise compromised by small gradient control errors, a reconstruction that jointly estimates both the image and patient motion, thus producing artifact-free images of moving patients, and a 120 kg but inhomogeneous brain MRI that forms images with no switching gradients (and is thus also silent). We also show the potential of the method to eliminate motion and gradient mis-calibration artifacts from MR images. Finally, Machine Learning approaches appear poised to either completely take over the model-based reconstruction, offering a very general form of model, or perhaps less scary, do some of the more difficult and computation-time consuming steps. |

### PRISMA Colloquium

Institut für Physik 13:00 Uhr s.t., Lorentz-Raum 05-127, Staudingerweg 7 |

Daniel Phillips, Ohio University / Darmstadt | |

For almost a century physicists have devoted intense attention to teasing out the nature of the nuclear force. But there remains much that we do not know about the way neutrons and protons interact, and the way that they come together to form nuclei. In this talk I will show how two toolseffective field theory and Bayesian probability theorycan provide quantitative assessments of the impact of the things that we dont know about nuclear physics on the observables that are measured in experiments. |

### SFB/TR49/SFB TRR 173 Spin+X-Kolloquium - Seminar experimentelle Physik der kondensierten Materie

SFB/TR49 - Prof. Dr. Elmers 14:00 Uhr s.t., MEDIEN-Raum, 03-431, Staudinger Weg 7 |

Scientific Colloquium, Klaeui-Lab | |

14:10 - 14:55 Andreas Stierle, DESY Hamburg
From the World of Dwarfs: a Nano Tale
14:55 - 15:40 Katharine Theis-Broehl, Hochschule Bremerhaven
Self-assembled layering of magnetic nanoparticles in a ferrofluid onto solid surfaces
15:40 - 16:00 Coffee Break
16:00 - 16:45 Bjoergvin Hjoervarsson, Uppsala University
Reflections on reflections
16:45 - 17:15 Hans Joachim Elmers, JGU
Anti-Ferromagnetism, the Antimatter in the Research Area of Magnetism |

### Seminar über Quanten-, Atom- und Neutronenphysik (QUANTUM)

Institut für Physik 14 Uhr c.t., Lorentz-Raum (05-127), Staudingerweg 7 |

Prof. Dr. Patrick Maletinsky, Department of Physics, University of Basel | |

Electronic spins yield excellent quantum sensors [1], offering quantitative sensing [2] and nanoscale imaging [3] down to the level of single spins [4]. Over the last years, the Basel Quantum Sensing Group has developed all-diamond scanning probes [5,6], hosting individual Nitrogen-Vacancy (NV) centre electronic spins as nanoscale magnetometers, to address open problems in condensed matter physics. I will describe our recent advances in applying this novel and unique quantum-sensing technology to study nano-magnetism in a variety of systems at room temperature and under cryogenic conditions [7].
Specifically, I will discuss applications of NV magnetometry in the emerging fields of antiferromagnetic spintronics [8] and magnetism in two-dimensional van der Waals materials [9]. In the former case, we demonstrated imaging of nanoscale antiferromagnetic domains in granular thin films of Cr2O3 [10] to explore the mechanism of domain formation and determine the strength of the inter-granular exchange coupling [10] - a key parameter for all technologically relevant thin films magnets. Atomic monolayers form an ultimate limit for such thin films and the recent discovery of magnetism in a range of van der Waals materials has therefore attracted significant interest. I will discuss how we shed new light on several key open aspects of the physics of these materials by employing quantitative NV magnetometry to study CrI3 magnetism down to the monolayer limit. Specifically, we provided the first direct determination of the saturation magnetisation in few layer CrI3 and elucidate the nature of the interlayer exchange coupling in this material. These results show the high potential for pushing further the frontiers of antiferromagnetic spintronics and two-dimensional magnetism by quantum sensing with NV centre spins.
[1] B. Chernobrod and G. Berman, J. of Appl. Phys. 97, 014903 (2004) [2] J. Taylor et al., Nature Physics 4, 810 (2008) [3] L. Rondin et al., Rep. Prog. Phys. 77 056503 (2014) [4] M. S. Grinolds et al., Nature Physics 9, 215 (2013) [5] P. Appel et al., Review of Scientific Instruments 87, 063703 (2016) [6] P. Maletinsky et al.,Nature Nanotechnology 7, 320 (2012) [7] L. Thiel et al., Nature Nanotechnology 11, 6776 (2016) [8] T. Jungwirth et al., Nature Nanotechnology 11, 231 (2016) [9] B. Huang, et al., Nature 546, 270 (2017) [10] T. Kosub et al., Nature Communications 8, 13985 (2017) [11] P. Appel et al., ArXiv:1806.02572 (2018) |

### Seminar about Experimental Particle and Astroparticle Physics (ETAP)

Institut für Physik 12:30 Uhr s.t., Staudingerweg 7, Minkowskiraum |

Robin Meyer, ETAP | |

## Development of new Scintillators based on Quantum Dots | |

Master Colloquium |

### Institutsseminar Kern- und Hadronenphysik

Institut für Kernphysik 14 Uhr c.t., HS Kernphysik, Becherweg 45 |

Marco Zimmermann, Mainz | |

## The Tracking Detector for the P2 Experiment |

### Theorie-Palaver

Institut für Physik 14:30 Uhr s.t., MITP seminar room |

Julian Munoz, Harvard University | |

The nature of the dark matter is still a mystery, although current and upcoming 21-cm measurements during the cosmic dawn can provide a new arena on the search for the cosmological dark matter. This era saw the formation of the first stars, which coupled the spin temperature of hydrogen to its kinetic temperature---producing 21-cm absorption in the CMB. The strength of this absorption acts as a thermostat, showing us if the baryons have been cooled down or heated up by different processes. I will show the discovery space for new dark-sector interactions, focusing on the case of "minicharged" dark-matter, which can explain the anomalous 21-cm depth observed by the EDGES collaboration. |

### Physikalisches Kolloquium

Institut für Kernphysik, Johann Joachim Becher Weg 45 16 Uhr c.t., HS KPH |

Prof. Dr. Ulrich Achatz, Goethe Universität Frankfurt/Institut für Atmosphäre u. Umwelt | |

Even with present and foreseeable computational capabilities, the spatial resolution of atmospheric weather-forecast and climate models is and will remain insufficient to capture many essential processes. Next to clouds and turbulence, subgrid-scale waves and their parameterization are one of the grand challenges of the field. Here, especially buoyancy-driven gravity waves are in the focus. The talk will give an overview of the fundamental properties and atmospheric impacts of these waves. It will describe the lead issues in their handling in models, and it will discuss recent developments towards their solution, ranging from laboratory experiments over theory to atmospheric modeling. |

### Theorie-Palaver

Institut für Physik Sonderseminar: 13:30 Uhr s.t., THEP social room |

Kim Berghaus, Johns Hopkins University | |

The 5.6 sigma high-energy neutrino excess at the IceCube detector could be an indicator of physics beyond the standard model. I will discuss the scenario of long-lived relics decays, with lifetimes shorter than the age of the universe, sourcing the neutrino excess . I will show the constraints on this possibility that arise from light element abundances, CMB anisotropies, and diffuse gamma-ray spectra. I will also discuss the importance of including electroweak corrections when exploring new physics far beyond the electroweak scale. | |

Sonderseminar |