Semesterübersicht – letztes Semester

Semesterübersicht Sommersemester 2023

Sommersemester 2023 - Wintersemester 2023/2024 - Sommersemester 2024

17 Apr 2023

Seminar about Experimental Particle and Astroparticle Physics (ETAP)

Institut für Physik

12:30 Uhr s.t., Staudingerweg 7, Minkowskiraum

Dennis Layh, Institut für Physik
MEDUSA and CALONet High-Speed Data Transmission and a Deep Learning-based Algorithm for an Upgrade of the ATLAS Trigger
at Zoom

18 Apr 2023

Physikalisches Kolloquium

Institut für Kernphysik

16:15 Uhr s.t., HS KPH

Dr. Masaki Hori, JGU Institute for Physics
Metastable antiprotonic helium is an exotic atom composed of a helium nucleus, electron, and an antiproton. It is among the hadron-antihadron systems with the longest known lifetimes. Laser light can be used to excite atomic transitions involving the antiproton orbital. By utilizing sub-Doppler two-photon laser spectroscopy and buffer gas cooling, its atomic transition frequencies were measured to ppb-scale precision. Comparisons with the results of QED calculations allowed the antiproton-to-electron mass ratio to be determined as 1836.1526734(15). The results were used to set upper limits on fifth forces between antiprotons and nucleons at atomic length scales, and on forces that may arise between an electron and antiproton mediated by hypothetical bosons. Efforts are currently underway to improve the experimental precision using CERN’s ELENA facility. We also observed narrow spectral lines of these atoms formed in superfluid helium with a surprisingly high spectral resolution of 2 parts per million. This revealed the hyperfine structure arising from the spin interaction between the antiproton and electron, despite the atom being surrounded by a dense matrix of normal atoms. Metastable pionic helium (πHe+) contains a negative pion occupying a state of n≈l-1≈17, and retains a 7 ns average lifetime. We recently used the 590 MeV ring cyclotron facility of Paul Scherrer Institute to synthesize the atoms, and irradiated them with infrared laser pulses. This induced a pionic transition within the atom and the π- being absorbed into the helium nucleus. This constitutes the first laser excitation and spectroscopy of an atom containing a meson. By improving the experimental precision, the pion mass may be determined to a high precision as in the antiproton case.

Theorie-Palaver

Institut für Physik

14:00 Uhr s.t., Lorentz room (Staudingerweg 7, 5th floor)

Anna Socha, Warsaw U.
According to the standard model of cosmology, the Universe at its very beginning underwent a phase of rapid expansion, followed by a reheating period. During this epoch, the energy density, initially accumulated in the coherent oscillations of the inflaton field, was injected into the visible sector, eventually setting the initial conditions for the hot Big Bang. In this talk, I will discuss perturbative production of the Standard Model (SM) particles adopting a non-standard post-inflationary scenario with a generic equation-of-state parameter \(\bar{w}\). To specify the inflaton dynamics, I will employ the \(\alpha\)-attractor T-model of inflation, such that \(\phi\) has a monomial potential \(V(\phi) \propto \phi^{2n}\) about the minimum. Moreover, I will explore the Higgs boson-induced reheating, assuming that it is achieved through a cubic inflaton-Higgs coupling \(\phi |\mathcal{H}|^2\). In the presence of such interaction, the Higgs field acquires a \(\phi\)-dependent mass which generates a vacuum expectation value that oscillates in time and breaks the electroweak gauge symmetry. Interestingly, the non-zero Higgs mass leads to a time-dependent inflaton decay rate and generates a phase-space suppression of the reheating efficiency. This, in turn, has non-trivial consequences for the reheating dynamics, modifying the evolution of the SM radiation energy density or the duration of the reheating phase. Furthermore, the implications of the non-standard reheating for the dark sector will be discussed, exemplified by the UV freeze-in dark matter model.

19 Apr 2023

PRISMA+ Colloquium

Institut für Physik

13:00 Uhr s.t., Lorentz-Raum, 05-127, Staudingerweg 7

Dr. Sebastian Ellis, Geneva University, Switzerland
Current and future Gravitational Wave (GW) observatories target the nHz to kHz frequency range. However, phenomena both within and beyond the Standard Model can give rise to GW signals above kHz. We will briefly discuss what these signals could be, before focusing on promising techniques to search for high-frequency GWs using resonant electromagnetic cavities. The technologies that have been developed to search for axion dark matter are directly transferrable to a search for GWs. Concurrent GW/axion searches are an exciting possibility.
Slides here...

20 Apr 2023

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

Institut für Physik

14 Uhr c.t., IPH Lorentzraum 05-127

Dr. Fernando Lemini, ICTP (Intl. Center for Theoretical Physics), Trieste, Italy
I discuss the concept of boundary time crystals, where the continuous time-translation symmetry breaking occurs only in a macroscopic fraction of a many-body quantum system. After introducing its definition and properties, we discuss in detail a solvable model where an accurate scaling analysis can be performed. The existence of the boundary time crystals is intimately connected to the emergence of a time-periodic steady state in the thermodynamic limit of a many-body open quantum system. I will also discuss the spreading of genuine multipartite correlations (GMC's) on such phases, showing results both for the (i) the structure (orders) of GMC's among its subsystem constituents, as well as (ii) their build-up dynamics for an initially uncorrelated state.

GRK 2516 Soft Matter Seminar

Uni Mainz

14:30 Uhr s.t., Minkowski Room, 05-119, Staudingerweg 7

Yuqing Wang, JGU, Chemistry
Printing of biologically functional constructs is significant for applications in tissue engineering and regenerative medicine. However, the development of bio-ink, a printable cell-laden material, remains a major challenge due to its multifaceted demands. While printability is highly dependent on the physical properties of the material, the formation of functional tissues requires interactions between the cells and the extracellular matrix. In this work, a balance between the physical processability and cytocompatibility is achieved by using a supramolecular approach. Therefore, one supramolecular network which shows fast stress relaxation and supports cell proliferation is mixed with a second physical network that can be transformed into a chemical network by applying an external photo trigger. The interpenetrating networks obtained have improved shape fidelity while the cytocompatibility is maintained.
at Zoom

24 Apr 2023

Seminar about Experimental Particle and Astroparticle Physics (ETAP)

Institut für Physik

12:30 Uhr s.t., Staudingerweg 7, Minkowskiraum

Savitri Gallego, Institut für Physik
From short baseline reactor neutrino experiment to gamma-ray astrophysics
at Zoom

RIND seminar on Mathematical Physics and String Theory

U. Mainz, LMU Munich, U. Heidelberg, U. Vienna

16 Uhr c.t.

Ed Segal, University College London
Given a Hamiltonian torus action on a symplectic manifold, Fukaya and Teleman tell us that we can relate the equivariant Fukaya category to the Fukaya category of a symplectic reduction. Yanki Lekili and I have some conjectures that extend this story - in certain special examples - to singular values of the moment map. I'll also explain the mirror symmetry picture that we use to support our conjectures, and how we interpret our claims in Teleman's framework of `topological group actions' on categories.
at Zoom

25 Apr 2023

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

Physikalisches Kolloquium

Institut für Kernphysik

16:15 Uhr s.t., HS KPH

Dr. Gaute Hagen, Oak Ridge National Lab. Knoxville - USA
High performance computing, many-body methods with polynomial scaling, and ideas from effective-field-theory is pushing the frontier of ab-initio computations of nuclei. Here I report on advances in coupled-cluster computations of nuclei starting from chiral Hamiltonians with two- and three-nucleon forces. The ab-initio approach can now be used to address fundamental questions related to the nature of the neutrino by accurate computations of neutrino-less double beta decay and making first steps towards neutrino-nucleus scattering on relevant nuclei. Global surveys of bulk properties of medium-mass and neutron- rich nuclei from ab-initio approaches are now possible by using reference states that break rotational symmetry. These calculations have revealed systematic trends of charge radii in various isotopic chains, questioned the existence of certain magic shell closures in neutron-rich nuclei, and confrontation with data have exposed challenges for ab- initio theory. By restoring rotational symmetry, we have made predictions for the rotational structure of neutron-rich neon isotopes including 32,34Ne. In addition to entire regions of the nuclear chart now being targeted by ab-initio computations, entirely new ways to make quantified predictions are becoming possible by the development of accurate emulators of ab-initio calculations. These emulators reduce the computational cost by many orders of magnitude allowing for billions of simulations of nuclei using modest computing resources. This allows us to perform global sensitivity analysis, quantify uncertainties, and use novel statistical tools in predicting properties of nuclei. Recently we used these tools to make a quantified prediction of the neutron skin in 208Pb, and found that the neutron-skin is smaller and more precise than a recent extraction from parity-violating electron scattering but in agreement with other experimental probes. We have also used these tools to address the questions of what drives deformation in atomic nuclei and whether 28O is a bound nucleus. These developments demonstrate how realistic two- and three-nucleon forces act in atomic nuclei and allow us to make quantitative predictions across the nuclear landscape.
Slides here...

Theorie-Palaver

Institut für Physik

14:00 Uhr s.t., Lorentz room (Staudingerweg 7, 5th floor)

Fabrizio Rompineve, CERN
A population of relativistic QCD axions can be produced in the early Universe, via scatterings with Standard Model particles. This can be searched for in cosmological datasets, which therefore provide the opportunity to discover/constrain the QCD axion, independently of astrophysical and/or laboratory probes. In this talk, after reviewing the subject, I present an improved calculation of the relic abundance of such “hot” axions from scatterings with pions below the QCD crossover, as well as the resulting upper bound on the QCD axion mass. I then discuss the exciting outlook of upcoming cosmological surveys, which may probe otherwise unexplored regions of the QCD axion parameter space. I highlight the need of a non-perturbative calculation of axion production rates throughout the QCD crossover, to fully exploit the reach of such datasets.

26 Apr 2023

PRISMA+ Colloquium

Institut für Physik

13:00 Uhr s.t., Lorentz-Raum, 05-127, Staudingerweg 7

Prof. Dr. Ryan Mitchell, Indiana University, USA
Using the idea of a field guide as a template, the referent will briefly review the rapidly expanding catalog of known mesons, which are strongly interacting subatomic particles made from equal numbers of quarks and antiquarks. While most mesons can be successfully described as one quark bound to one antiquark, recent discoveries point towards the existence of new meson families. These discoveries, made at experiments such as the BESIII e+e- experiment in Beijing and the LHCb pp experiment at the LHC, offer new contexts in which to study the strong force of particle physics.
Slides here...

27 Apr 2023

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

Institut für Physik

14 Uhr c.t., IPH Lorentzraum 05-127

Dr. Jack A. Devlin, Imperial College, London, UK
The toolkit of quantum technologies developed in atomic, molecular and optical physics are ideally suited to enhance the search for dark matter axions with masses above ~40 µeV. I will present an overview of a new experimental effort under construction at Imperial College, developing technologies to detect DFSZ axions with masses 120-250 µeV. We plan to use a large mode area Fabry-Perot cavity to efficiently convert axions into microwave photons. Compared to other geometries, the Fabry-Perot cavity can present a large mode volume and high Q, and can be easily tuned. To detect the microwaves, we will use an electron in a Penning trap as a single photon counter. Individual microwave absorption events will change the cyclotron state of the electron, causing measurable shifts in the trapped particle’s oscillation frequencies. This versatile device will also open other possible detection routes for alternative dark matter candidates and cosmological phenomena.

02 May 2023

Physikalisches Kolloquium

Institut für Kernphysik

16:15 Uhr s.t., HS KPH

Prof. Peter Zoller, University of Innsbruck and IQOQI - Austria
The development of atomic quantum simulation platforms has led to the creation of a new generation of programmable quantum simulators that can be scaled to large particle numbers while maintaining a certain degree of programmability. This talk reports on theory-experiment collaborative work using trapped ion platforms with up to fifty-one qubits/spins, where we develop and demonstrate quantum protocols that can address questions ranging from fundamental to practical. Examples include first observation of area law vs. volume law entanglement in ground and excited states of many-body systems, and quantum simulators acting as programable quantum sensors implementing near “optimal” entanglement-enhanced quantum metrology.

Theorie-Palaver

Institut für Physik

14:00 Uhr s.t., Lorentz room (Staudingerweg 7, 5th floor)

Jose Zurita, IFIC Valencia
In the last years there has been a renewed interest in the particle physics theoretical and experimental communities on the study of exotic (non-standard) signatures at colliders, including Long-Lived Particles (LLPs). In this talk I will first give a brief overview of the theoretical motivations for long-lived particles. Later I will illustrate the impact of LLPs in the current LHC physics programme, including new LHC detectors specifically hunting for LLPs (MoEDAL, FASER, SND@LHC), detector proposals under consideration (MATHUSLA, ANUBIS, FPF) and relevant upgrades to the ATLAS, CMS and LHCb experiments. Finally, I will present snapshots of novel signatures and the implications of LLP searches in the context of neutrino, axion, dark matter and Higgs physics.

Seminar Festkörper- und Grenzflächenphysik KOMET - experimentell

Institut für Physik

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

TBA, TBA
TBA

03 May 2023

PRISMA+ Colloquium

Institut für Physik

13:00 Uhr s.t., Lorentz-Raum, 05-127, Staudingerweg 7

Dr. Ida Zadeh, JGU Mainz
A conformal field theory is a physical theory which is invariant under changes in its length or energy scale. It describes the physics of boiling of water. In this talk, the referent will present how conformal field theory is used as a powerful tool to study quantum gravity. She will discuss how conformal field theories describe quantum properties of a family of black holes, just as quantum mechanics describes the Hydrogen atom.
Slides here...

04 May 2023

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

Institut für Physik

14 Uhr c.t., IPH Lorentzraum 05-127

Prof. Dr. Artur Widera, TU Kaiserslautern
Excellent experimental control over quantum systems is increasingly bringing applications in quan-tum technologies within reach. In my talk, I will present our work on quantum technology applica-tions in various physical systems. Ultracold atoms have proven to be excellent platforms for studying quantum effects. In recent years, we have succeeded in introducing single Cs atoms as controlled impurities in an ultracold gas of Rb atoms. Spin-exchange collisions allow a very controlled transfer of energy quanta, and we use this transfer to operate the single atom as a machine in a magnetic field gradient. In another exper-imental setup, we address whether the significant energy differences resulting from the Pauli prin-ciple between ensembles of different fermionic and bosonic quantum statistics can be used as a novel form of energy to drive a quantum machine. Finally, I will present two new projects in the field of quantum technology. First, we are studying nanocrystals of diamond with a large number of NV centers in terms of collective effects and track-ing how the typical signatures in fluorescence lifetime and photon statistics change when larger agglomerates of nanocrystals show the transition to a bulk-like material. Second, I report on a new BMBF collaborative project, the quantum computing demonstrator pro-ject Rymax, which will simulate optimization problems from logistics and industry expressed as gra-phene problems on an array of single Yb atoms with Rydberg excitations.

GRK 2516 Soft Matter Seminar

Uni Mainz

14:30 Uhr s.t., Minkowski Room, 05-119, Staudingerweg 7

Franziska Lissel, Leibniz Institute of Polymer Research, Dresden
Triblock Copolymers – Using Nanophase Separation to Achieve Low Modulus, Elastic Deformation and Good Mobility in Polymer Semiconductors
at Zoom

08 May 2023

Seminar about Experimental Particle and Astroparticle Physics (ETAP)

Institut für Physik

12:30 Uhr s.t., Staudingerweg 7, Minkowskiraum

Annika Hollnagel, Institut für Physik
Search for Hidden Particles: SHiP @ECN3
at Zoom

RIND seminar on Mathematical Physics and String Theory

U. Mainz, LMU Munich, U. Heidelberg, U. Vienna

16 Uhr c.t.

Pyry Kuusela, JGU Mainz
Supersymmetic flux vacua in Calabi-Yau compactifications are closely related to intricate number theoretic properties of the compactification manifolds. Such relations are of interest to physicists and number theorists alike: On one hand these can be used to find new, interesting flux vacuum solutions and relate physical quantities to well-studied number theoretic functions. On the other hand, physical intuition allows one to give examples of interesting number theoretic relations and obtain evidence for various conjectures. To study these relations, we present a novel method, based on symmetries of the compactification manifold, for constructing many large families of number theoretically interesting supersymmetric flux vacua. We show that the zeta functions of the compactification manifolds factorise, as expected by the celebrated modularity conjectures. The coefficients appearing in these factorisations can be associated to elliptic curves which appear in various contexts: For instance, we argue that the value of the axiodilaton field associated to the flux vacua can be identified with the modulus of these elliptic curves. We also obtain extensive evidence for the flux vacuum modularity conjecture proposed recently by Kachru, Nally, and Yang. This talk is based on arXiv:2302.03047 with Candelas, de la Ossa, and McGovern.
at Zoom

09 May 2023

Physikalisches Kolloquium

Institut für Kernphysik

16:15 Uhr s.t., HS KPH

Dr. Szymon Pustelny, University of Krakau
Thanks to its strong immunity to environmental perturbations, for many decades, molecular nuclear systems have found extensive applications in science, technology, and medicine. One of the techniques exploring these nuclear-spin systems is the technique of nuclear magnetic resonance (NMR). While typically performed under very strong magnetic fields (>1 T), recent advances in hyperpolarization methods and magnetometric techniques have led to the emergence of a technique of zero- and ultralow-field (ZULF) NMR. Operation under such unique conditions, with simple, small, and cost-efficient experimental systems, has opened up new avenues for ultraprecise spectroscopy and relaxometry, allowing for interesting applications in chemistry and biology. In physics, ZULF NMR was used for the engineering of long-lived (tens of seconds) nuclear states and the searches for physics beyond the Standard Model. Despite these applications, however, the technique is still at its early stage and many applications will be developed in future. During the colloquium, the fundamentals and distinctive features of ZULF NMR will be presented and some of its applications will be highlighted.

Seminar Festkörper- und Grenzflächenphysik KOMET - experimentell

Institut für Physik

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

TBA, TBA
TBA

10 May 2023

PRISMA+ Colloquium

Institut für Physik

13:00 Uhr s.t., Lorentz-Raum, 05-127, Staudingerweg 7

Prof. Dr. Giovanni de Lellis, Naples University, Italy
SND@LHC is a compact and stand-alone experiment to perform measurements with neutrinos produced at the LHC in a hitherto unexplored pseudo-rapidity region of 7.2 < 𝜂 < 8.4, complementary to all the other experiments at the LHC. The experiment is located 480 m downstream of IP1 in the unused TI18 tunnel. The detector is composed of a hybrid system based on an 800 kg target mass of tungsten plates, interleaved with emulsion and electronic trackers, followed downstream by a calorimeter and a muon system. The configuration allows efficiently distinguishing between all three neutrino flavours, opening a unique opportunity to probe physics of heavy flavour production at the LHC in the region that is not accessible to ATLAS, CMS and LHCb. This region is of particular interest also for future circular colliders and for predictions of very high-energy atmospheric neutrinos. The detector concept is also well suited to searching for Feebly Interacting Particles via signatures of scattering in the detector target. The first phase aims at operating the detector throughout LHC Run 3 to collect a total of 250 fb−1. The experiment has been taking data successfully during the proton physics run of 2022. We show the detector concept, design and performance as well as the first physics results.
Slides here...

15 May 2023

Seminar about Experimental Particle and Astroparticle Physics (ETAP)

Institut für Physik

12:30 Uhr s.t., Staudingerweg 7, Minkowskiraum

Patrick Deucher, Institut Für Physik
Plastic Scintillator Development in Mainz
at Zoom

RIND seminar on Mathematical Physics and String Theory

U. Mainz, LMU Munich, U. Heidelberg, U. Vienna

16 Uhr c.t.

Clay Córdova, University of Chicago
We elucidate the fate of classical symmetries which suffer from abelian Adler-Bell-Jackiw anomalies. Instead of being completely destroyed, these symmetries survive as non-invertible topological global symmetry defects with worldvolume anyon degrees of freedom that couple to the bulk through a magnetic one-form global symmetry as in the fractional hall effect. These non-invertible chiral symmetries imply selection rules on correlation functions and arise in familiar models of massless quantum electrodynamics and models of axions (as well as their non- abelian generalizations)
at Zoom

16 May 2023

Physikalisches Kolloquium

Institut für Kernphysik

16:15 Uhr s.t., HS KPH

Prof. Rebecca Surman, University of Notre Dame, Indiana USA
The groundbreaking discovery of the neutron star merger event GW170817 ushered in a new era of multimessenger astrophysics. One key observation was the optical signal that accompanied GW170817, which provided the first firm proof that neutron star mergers produce heavy elements. Still, it is not known exactly which elements are produced by mergers and in what proportions. Are neutron star mergers the sole astrophysical source of the heaviest elements or do other extreme events contribute? A full understanding of neutron star mergers and their role in galactic chemical evolution requires progress in a number of areas including nuclear physics. Thousands of exotic nuclear species participate in neutron star merger nucleosynthesis, and their properties shape abundance patterns and kilonova signals. Here we discuss how nuclear physics uncertainties influence predictions of nucleosynthesis observables. We then explore the promise of experimental campaigns at rare isotope beam facilities to both reduce these uncertainties and provide insight into astrophysical environments of heavy element production.

Theorie-Palaver

Institut für Physik

14:00 Uhr s.t., Lorentz room (Staudingerweg 7, 5th floor)

Anne Spiering, Bohr Inst
The direct integration of Feynman integrals can be a daunting task, in particular for increasing numbers of loops and external particles. The “symbol bootstrap” has proven to be a powerful tool in the calculation of certain polylogarithmic Feynman integrals and scattering amplitudes that bypasses this direct integration. In this approach one first writes an ansatz for the symbol of the integral and then fixes its degrees of freedom by imposing known mathematical and physical properties of the final result. In this talk I will discuss a generalisation of this approach to an elliptic case: the 12-point two-loop double-box integral. The bootstrapping ansatz is obtained from an elliptic generalisation of the so-called Schubert problem, and after imposing a sufficient number of constraints on this ansatz, we obtain a compact one-line formula for the (2,2)-coproduct of the double-box integral.

Seminar Festkörper- und Grenzflächenphysik KOMET - experimentell

Institut für Physik

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

TBA, TBA
TBA

17 May 2023

PRISMA+ Colloquium

Institut für Physik

13:00 Uhr s.t., Lorentz-Raum, 05-127, Staudingerweg 7

Dr. Vera Gülpers, University of Edinburgh
Indirect high-precision searches for possible deviations from Standard Model predictions at low energies are an important tool for finding signatures of new physics. Ab-initio theoretical predictions involving the strong nuclear force at small energies are only possible using Monte Carlo methods in a numerical approach known as Lattice QCD. In recent years lattice calculations of several quantities, such as the pion decay constant, have reached a precision of O(1%), where electromagnetic effects can no longer be neglected. In this talk Vera Gülpers will discuss how electromagnetic effects can be included in lattice calculations and present results of our recent calculation of electromagnetic corrections to leptonic pion and kaon decays.
Slides here...

Seminar über Theorie der kondensierten Materie / TRR146 Seminar

F. Schmid / G. Settanni / P. Virnau / L. Stelzl

18:00 Uhr s.t., Minkowski Room, 05-119, Staudingerweg 7,

Bernhard von Vacano, BASF
PW 059721

https://trr146.uni-mainz.de/activities/

22 May 2023

Seminar about Experimental Particle and Astroparticle Physics (ETAP)

Institut für Physik

12:30 Uhr s.t., Staudingerweg 7, Minkowskiraum

Mathias Schott, Institut für Physik
High Precision Measurement of the Strong Coupling Constant
at Zoom

RIND seminar on Mathematical Physics and String Theory

U. Mainz, LMU Munich, U. Heidelberg, U. Vienna

11:00 Uhr s.t.

Kantaro Ohmori, Tokyo
The common statement that any consistent quantum gravity theory contains dynamical objects with all possible charges suggests that there are still a number of hitherto-unidentified branes in string theory. Such charges are classified by the bordism classes in the working EFT. In this talk I will describe some of those charges and then discuss plausible worldsheet descriptions of strings near the corresponding branes.
at Zoom

23 May 2023

Physikalisches Kolloquium

Institut für Kernphysik

16:15 Uhr s.t., HS KPH

Prof. Frank Cichos, University of Leipzig
Plasmonics is commonly used to confine electromagnetic waves into subwavelength noble metal structures for photonic applications. As an unwanted side effect, heat is generated locally, which is the foundation of thermoplasmonics. Besides numerous very interdisciplinary applications, such local heat generation provides unique dynamic control over microscopic objects in liquids with non-equilibrium physics. I will give two examples. First, I discuss experiments on active colloidal particles that are self-propelled by thermoplasmonic effects. Such active particles mimic the motility of living species like bacteria but lack the feedback loops that control their behavior. The optical control of plasmonic heating allows us to implement feedback loops, behavior and even learning for active particles. Using this technique, we can show that perception-reaction delays as omnipresent in living systems can be the origin of a variety of dynamical collective states that even display signatures of criticality. In a second example, I will briefly report on experiments using plasmonic heat generation to enable the control of liquids and macromolecules. Dynamic temperature fields thereby help us to study elementary processes of peptide aggregation as relevant for neurodegenerative diseases over extremely long periods of time.

Theorie-Palaver

Institut für Physik

14:00 Uhr s.t., Lorentz room (Staudingerweg 7, 5th floor)

Felipe Llanes Estrada, Madrid U.
The Electroweak Symmetry Breaking Sector of the Standard Model is an active field where new physics is sought. In the absence of new higher-energy particles at colliders, Effective Field Theories in terms of the Standard Model particles (longitudinal gauge and Higgs bosons) seem a natural tool. New physics could then manifest itself as new forces modifying the couplings of those particles. Should such new forces be found, they could be used to confront (falsify?) the popular SMEFT: as it is not the most general possible EFT, we have managed to produce correlations among the parameters of the embedding HEFT that can be tested if that new physics is describable by SMEFT. We have also extended HEFT via the Inverse Amplitude Method to be able to address resonances in the electroweak sector directly from the low-energy particles and eventual BSM couplings, thus maintaining agnosticism about the nature of the eventual new physics, and I will discuss the systematic uncertainties of the unitarization procedure. Based on various works, e.g. https://inspirehep.net/literature/2120028 https://inspirehep.net/literature/2154526 https://inspirehep.net/literature/1826204 https://inspirehep.net/literature/1345172 https://inspirehep.net/literature/1310013

Seminar Festkörper- und Grenzflächenphysik KOMET - experimentell

Institut für Physik

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

Anna Liedtke, Institute of Physics
Spin-Orbit Torques in the van-der Waals materials Fe3GeTe2 and Fe3-xCoxGeTe2

24 May 2023

PRISMA+ Colloquium

Institut für Physik

13:00 Uhr s.t., Lorentz-Raum, 05-127, Staudingerweg 7

Prof. Dr. Mikhail Shaposhnikov, EPF Lausanne, Switzerland
The referent will overview the problem of baryon asymmetry of the Universe and the theoretical framework within which the baryogenesis, i.e. the dynamical generation of a matter–antimatter asymmetry, can occur. He will discuss different mechanisms for baryogenesis with special emphasis to those of them that can be experimentally tested.
Slides here...

25 May 2023

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

Institut für Physik

14 Uhr c.t., IPH Lorentzraum 05-127

Prof. Dr. Enno Giese, TU Darmstadt
Light pulses are an excellent tool to manipulate atoms, so that they move in superposition of different trajectories through space and time. In analogy to the concept of an optical interferometer, these branches can be brought to interference and used as sensors for gravity and other inertial forces. As such, atom interferometry has become a versatile tool technique high-precision quantum metrology, which ranges from gyroscopes to gravitational wave detection, as well as a testbed for the interface of relativity and quantum mechanics. At the same time, atoms not only possess a center-of-mass motion, but also internal degrees of freedom that are the very basis for atomic clocks. Making use of this additional property, one can in principle generate atomic clocks that move in superposition of different branches, interfere with each other, and therefore constitute a different probe of relativistic effects linked to time. This colloquium gives an introduction into the main concepts of atom interferometry and the toolbox necessary to manipulate atoms. While we explain basic examples of atom interferometers and state-of-the-art experiments, we also discuss current and ambitious proposals for high-precision tests of fundamental physics.

30 May 2023

Physikalisches Kolloquium

Institut für Kernphysik

16:15 Uhr s.t., HS KPH

Prof. Angela Wittmann, JGU Institute for Physics
Controlled manipulation of a system allows for systematic investigation of the underlying interactions and phenomena. Simultaneously, tunability also enables the development of novel materials systems and devices customized for specific applications. Here, we will focus on materials systems that conventionally have not been used as active components in spintronic devices. We will explore the impact of strain on the antiferromagnetic domain structure via magneto-elastic coupling1. Furthermore, we will delve into hybrid molecule-magnetic interfaces. Molecules offer a unique way of controlling and varying the structure at the interface making it possible to precisely tune the spin injection and diffusion by molecular design2. In particular, chirality has gained recent interest in the context of the chiral-induced spin selectivity effect3. Here, we will explore signatures of spin filtering at a non-magnetic chiral molecule-metal interface paving the path toward novel hybrid spintronics.

Seminar Festkörper- und Grenzflächenphysik KOMET - experimentell

Institut für Physik

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

TBA, TBA
TBA

Theorie-Palaver

Institut für Physik

14:00 Uhr s.t., Lorentz room (Staudingerweg 7, 5th floor)

Christian Ecker, Frankfurt U.
According to the inflationary theory of cosmology, most elementary particles in the current universe were created during a period of reheating after inflation. In this talk I will show how to self-consistently couple the Einstein-inflaton equations to a strongly coupled quantum field theory (QFT) that is described by holography. I will then use a specific example to demonstrate that this setup leads to an inflating universe, a reheating phase and finally a universe dominated by the QFT in thermal equilibrium. This talk is based on arXiv:2302.06618.

31 May 2023

PRISMA+ Colloquium

Institut für Physik

13:00 Uhr s.t., Lorentz-Raum, 05-127, Staudingerweg 7

Prof. Robert Wilson, Colorado State University, USA
Forty years ago as an undergraduate contemplating graduate school in high energy physics, the referent declined a research assistantship to work on a neutrino experiment because neutrinos weren’t interesting … they were massless and weakly interacting so produced frustratingly few events to analyze even in massive detectors. How things have changed! The more we learn, the more we realize the importance of the most abundant known matter particle in the universe. In the decades since my naïve snubbing of this intriguing particle we have developed a well-established three-flavor paradigm that may help explain the matter-antimatter asymmetry of the universe. Yet beyond that, a few intriguing measurement “anomalies” hint at the existence of something stranger still, a neutrino that does not interact via any known forces except gravity, a sterile neutrino. Robert Wilson will give a brief overview of the results that motivated a definitive search for sterile neutrinos with a mass in the 1 eV/c2 range – the Short-Baseline Neutrino program at Fermi National Accelerator Laboratory. He will describe the physics sensitivity and the detectors that will measure the appearance of electron-type neutrinos in a muon-type neutrino beam using massive liquid argon time-projection chambers with an emphasis on the 760-ton far detector developed by the ICARUS collaboration. Operating both in Italy’s Gran Sasso underground laboratory and now at Fermilab, this detector demonstrated the viability of the technology for large-scale experiments such as the international Deep Underground Neutrino Experiment (DUNE).

Seminar über Theorie der kondensierten Materie / TRR146 Seminar

F. Schmid / G. Settanni / P. Virnau / L. Stelzl

16:00 Uhr s.t., KpH lecture room, 00-200, Johann-Joachim-Becher-Weg 45

Nico Bischoff, R+V
Hybrid event; PW: 359038

PW: 359038

01 Jun 2023

GRK 2516 Soft Matter Seminar

Uni Mainz

14:30 Uhr s.t., Minkowski Room, 05-119, Staudingerweg 7

Matthew Baker, Maastricht University
TBA
at Zoom

06 Jun 2023

Physikalisches Kolloquium

Institut für Kernphysik

16:15 Uhr s.t., HS KPH

Prof. Susan Gardner, University of Kentucky - USA
Questions that drive searches for physics beyond the Standard Model include the physical origin of the cosmic baryon asymmetry and of dark matter. Quark dynamics, as realized through the theory of quantum chromodynamics (QCD), can appear in these studies in very different ways. In this talk, I develop these possibilities explicitly, first describing the role of QCD in ultra-sensitive searches for new physics, particularly at low energies, and then turning to how its features could be exploited in describing the undiscovered universe, along with the essential observational and experimental tests that could confirm them.

Theorie-Palaver

Institut für Physik

14:00 Uhr s.t., Lorentz room (Staudingerweg 7, 5th floor)

Bibhushan Shakya, DESY
The Standard Model Higgs becomes tachyonic at high energy scales according to current measurements. This unstable regime of the Higgs potential can be realized in the early Universe during high scale inflation, potentially with catastrophic consequences. In this talk, we will discuss a crucial inherent feature of such configurations that has so far remained ignored: Higgs particle production out of vacuum induced by the rapidly evolving Higgs field, which gets exponentially enhanced due to the tachyonic instability. We will discuss various theoretical and observational implications of this effect.

Seminar Festkörper- und Grenzflächenphysik KOMET - experimentell

Institut für Physik

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

Dr. Olena Fedchenko, Institut für Physik / KOMET 5
Investigation of phase-transition in Mo1-x Wx Te2 using ToF-MY

07 Jun 2023

PRISMA+ Colloquium

Institut für Physik

13:00 Uhr s.t., Lorentz-Raum, 05-127, Staudingerweg 7

Dr. Alexander Gerbershagen, University of Groningen, Netherlands
The presentation covers the aspects of the use the accelerators for the hadron therapy. It includes the summary of the advantages of hadron use for radiation treatment of cancer, the technological solutions used for the beam acceleration, dose delivery and application, and an overview over the types of commercially available systems. Following that, the presentation concludes by describing the newly established the PARticle Therapy REsearch Center (PARTREC) in Groningen. Using the superconducting cyclotron AGOR and being embedded within the University Medical Center Groningen, providing proton beams of up to 190 MeV and ion beams (up to Pb) with energies up to 90 MeV/nucleon for pre-clinical research in medical physics and radiobiology.
Slides here...

12 Jun 2023

Seminar about Experimental Particle and Astroparticle Physics (ETAP)

Institut für Physik

12:30 Uhr s.t., Staudingerweg 7, Minkowskiraum

Tim Schneemann, Institut für Physik
SUPAX - A Superconducting Axion Search Experiment
at Zoom

Seminar über Theorie der kondensierten Materie / TRR146 Seminar

F. Schmid / G. Settanni / P. Virnau / L. Stelzl

14:30 Uhr s.t., Medienraum (IPH, 03-431)

Apratim Chatterji, IISER-Pune, Pune
I shall present our recent results where we modify internal-topology of ring polymers (bead-spring model) to obtain localization of polymer segments within cylindrical confinement. We tried out a variety of topologies to establish the entropic principles which lead to localization of polymer segments. Two polymers in a mixed state under cylindrical confinement undergo segregation, and again topology plays an important part in determining the forces which lead to segregation and subsequent localization. We have used this understanding to predict the localization of loci (polymer segments) of bacterial DNA polymers, as the chromosome is replicating and segregating. It is known that some simple bacterial cells do not have the required machinery to separate their chromosomes within the cell. We have matched out model simulations results for two different bacterial chromosomes, moreover, our model simulation match data from two different experimental techniques ( HiC and FISH) which are complementary in spirit. I am extending our topology driven organization understanding in a variety of scenarios, some of which will be useful to understand more complex organization of chromosomes within more complex cells as well in more complex scenarios of multifork replication within the bacterial cell.

13 Jun 2023

Physikalisches Kolloquium

Institut für Kernphysik

16:15 Uhr s.t., HS KPH

Dr. Frank Stefani, Helmholz-Zentrum Dresden-Rossendorf
Magnetic fields of planets, stars and galaxies are generated by the homogeneous dynamo effect, or self-excitation, in moving electrically conducting fluids, such as liquid metals or plasmas. Once generated, magnetic fields can promote cosmic structure formation by destabilizing, via the magnetorotational instability (MRI), rotational flows that would be otherwise hydrodynamically stable. Closely related instabilities, such as the current-driven Tayler instability might be at work in the solar tachocline. For a long time, these topics had been the subject of purely theoretical and numerical research. This situation changed in 1999 when the threshold of magnetic-field self-excitation was exceeded in the two liquid sodium experiments in Riga and Karlsruhe. Since 2006, the VKS dynamo experiment in Cadarache has successfully reproduced many features of geophysical interest such as reversals and excursions. MRI related experiments were partly successful with the observation of the helical MRI and the azimuthal MRI at Helmholtz-Zentrum Dresden-Rossendorf (HZDR), where first evidence of the current-driven Tayler instability in a liquid metal was obtained, too. In another liquid metal experiment at the Dresden High Magnetic Field laboratory (HLD) the “magic point” of coinciding Alfvén and sound speeds was reached, which is thought to play a key role for the heating of the solar corona. The lecture gives an overview about previous and future liquid metal experiments on dynamo action and magnetically triggered flow instabilities, with special focus on the precession driven liquid sodium experiment and the large-scale MRI experiment that are under construction in the framework of the DRESDYN project at HZDR. Particular emphasis is placed on generic questions such as the reversal mechanism of the geodynamo and the possibility of a planetary synchronization of the solar dynamo, on which those experiments might shed some fresh light.

Theorie-Palaver

Institut für Physik

14:00 Uhr s.t., Lorentz room (Staudingerweg 7, 5th floor)

Thomas Thiemann, Erlangen Nürnberg
The Hamiltonian approach to quantum gravity initiated by Bergman, Dirac, DeWitt, Komar, Wheeler et al has a long tradition and many quantum gravity programmes rest on it. While there has been progress in the past, the current theory is still not predictive because the Einstein-Hilbert Lagrangian is not even polynomial in the metric field which triggers many quantisation ambiguities. To eliminate those, renormalisation methods suggest themselves, preferrably directly in the Hamiltonian rather than the path integral language. After an introduction to those concepts, in this talk we present such a Hamiltonian renormalisation scheme which is derived from Wilson's notion of non-perturbative renormalisation of path integrals together with methods from constructive QFT. As a test we study Hamiltonian renomalisation of parametrised field theory in 2D which is a toy model for 4D quantum gravity in the sense that both theories are subject to the hypersurface deformation algebroid shared by all generally covariant field theories.

Seminar Festkörper- und Grenzflächenphysik KOMET - experimentell

Institut für Physik

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

Giovanni Masciocchi, Institute of Physics
Strain control of magnetization: an opportunity for innovative magnetic sensors

14 Jun 2023

PRISMA+ Colloquium

Institut für Physik

13:00 Uhr s.t., Lorentz-Raum, 05-127, Staudingerweg 7

Prof. Dr. Seyda Ipek, Carleton University, USA
Everything around us, cookies, rocks, stars, galaxies... is made up of “matter” and not “antimatter”. We know that if antimatter comes close to matter, they annihilate each other leaving only energy behind. That we are here means there is no antimatter to annihilate with us! But what happened to the antimatter in the Universe? Where did it go? How did it disappear? Why/how did matter stay behind? The referent will talk about this mystery and possible ways around it, which requires new physics beyond the Standard Model of particle physics.
Slides here...

15 Jun 2023

GRK 2516 Soft Matter Seminar

Uni Mainz

15:00 Uhr s.t., Minkowski Room, 05-119, Staudingerweg 7

Atieh Razavi, TU Darmstadt, Physics
TBA
at Zoom

20 Jun 2023

Physikalisches Kolloquium

Institut für Kernphysik

16:15 Uhr s.t., HS KPH

Dr. Simone Pirrotta, Italian Space Agency (ASI) Rome - Italy
Small satellites are nowadays extremely powerful, flexible and sustainable platforms that can be used to complement the missions usually assigned to larger spacecrafts. Modularity, standardization, intensive use of state-of-the art COTS technologies consent to prepare cheaper missions in shorter timeframes, thus allowing a more frequent access to space environment, including Cislunar and Interplanetary. The Italian Space Agency – ASI promotes, funds and coordinates the national initiatives also in this promising sector, both for national missions and within international cooperation. The first products of this effort are ArgoMoon and LICIACube, both 6U cubesats which operated during 2022 as first Italian spacecrafts beyond the Low Earth Orbit. The Light Italian Cubesat for Imaging of Asteroids - LICIACube participated in the NASA Double Asteroid Redirection Test - DART mission, the first active Planetary Defense mission; on September 26th 2022, few minutes after DART’s impact on asteroid Dimorphos, LICIACube captured unique images of the impact effects, primarily the plume of ejecta, and the not visible side of the secondary asteroid. The operations have been conducted by a national team coordinated by ASI. The design, manufacturing, testing and operations of the space and ground segment elements have been performed by the Italian firm Argotec under ASI management, while a wide scientific team supported the investigation preparation with impact modelling simulation and data analysis and interpretation, under the coordination of the National Institute of Astrophysics INAF. The engineering teams of Polytechnic of Milan and University of Bologna were in charge of trajectory design and optimization and the orbit determination and navigation, respectively. Captured images during the challenging fly-by confirmed the DART success as Planetary Defense initiative and provided scientists with highly valuable data, that allowed a first set of results to be confirmed and are currently under further analysis for scientific investigations. In fact, on October 11th 2022, NASA announced the complete success of the DART mission, confirming that the spacecraft’s impact altered Dimorphos’ orbit around Didymos by 32 minutes. Moreover, The LICIACube images show that the DART impact on Dimorphos generated a cone of ejected surface material with a large aperture angle. This plume has a complex and inhomogeneous structure, characterized by non-radial filaments, dust grains, and single and clustered boulders that allows us to deeply investigate the nature of the ejecta and the structure of Dimorphos.

Theorie-Palaver

Institut für Physik

14:00 Uhr s.t., Lorentz room (Staudingerweg 7, 5th floor)

Thomas Becher, Bern
In cross sections involving angular cuts, intricate patterns of enhanced higher-order corrections known as non-global logarithms arise. These corrections do not exponentiate and to resum them to all orders one has to resort to numerical techniques. The resummation of the leading non-global logarithms was achieved twenty years ago, but higher-logarithmic resummations remained elusive. In my talk, I will show how such resummation can be performed using renormalization group methods in effective field theory. I will demonstrate how the associated evolution equations can be implemented into a Monte-Carlo framework and will present first numerical results for higher-logarithmic resummations at both lepton and hadron colliders.

Seminar Festkörper- und Grenzflächenphysik KOMET - experimentell

Institut für Physik

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

Kilian Leutner, Institute of Physics
Simulation and detection of topological spin structures

21 Jun 2023

PRISMA+ Colloquium

Institut für Physik

13:00 Uhr s.t., Lorentz-Raum, 05-127, Staudingerweg 7

Prof. Dr. Marcos Marino, Geneva University, Switzerland
Perturbation theory remains one of the main tools in physics, in particular in quantum theories. However, most perturbative series diverge factorially, and it is not obvious how to extract information from them. Their divergence also suggests that, in order to obtain accurate results, one might need additional non-perturbative information. The theory of resurgence has been proposed as a general framework to address these issues. In this talk the referent will give an introduction to this theory and will illustrate it with applications -old and new - in quantum mechanics and in quantum field theory.
Slides here...

Seminar über Theorie der kondensierten Materie / TRR146 Seminar

F. Schmid / G. Settanni / P. Virnau / L. Stelzl

14:30 Uhr s.t., Minkowski Room, 05-119, Staudingerweg 7

Abhishek Singharoy, Arizona State University
Molecular modeling of biomolecular assemblies exemplifies a disruptive area holding both promises and contentions. We will start with a brief story of simulating the first ever cell organelle in molecular details to find how nature has chosen survival fitness over efficiency of energy transfer as an evolutionary design (Cell, 2020). Despite such advances in exascale computing, biophysical simulation continues to grapple with handling molecular diversity. So, we will employ deep learning approaches often used in Google searches, called the inception network, to marry interaction signatures from Alphafold models and proteomics analysis with predictable patient outcomes (Cell Sys, 2022). An application will highlight how molecular modeling is used at an industrial scale to de-risk vector-based vaccines for distribution across 194 countries (Sci Adv 2021). We will conclude by seeing how transient interactions are difficult to predict, and path integrals with reinforcement learning offer a possible way to track diversity of dynamics (NeurIPS, 2022).

22 Jun 2023

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

Institut für Physik

14 Uhr c.t., IPH Lorentzraum 05-127

Prof. Dr. Sven Höfling, Technische Physik, Universität Würzburg
We will summarize recent progress made within our group on self-assembled quantum dot device development for quantum repeater and quantum computer applications. A particular emphasis will be on semiconductor quantum dots embedded in circular Bragg grating cavities. For scalability, spatially deterministic placement of quantum dots in bullseye cavities is pursued and tuning by electric and strain fields are implemented. To apply electric fields, a new device design for electrically contactable circular Bragg grating cavities in labyrinth geometry is employed. In(Ga)As/GaAs quantum dots (QDs) are very attractive candidates to confine single excitons and single spins serving as solid state qubits in a mature semiconductor platform. While these qubits can be directly manipulated by optical means, both optical and electrical excitation of the QDs can be implemented to efficiently generate single photons or entangled photon pairs on demand. Light-matter interaction in coupled quantum dot-cavity systems can be widely controlled by embedding the QDs into microcavities. In this presentation, we will summarize recent progress made within our group and plans on device development with self-assembled quantum dots intended for quantum repeater and quantum computer applications [1]. A particular emphasis will be on semiconductor quantum dots embedded in circular Bragg grating cavities [2,3]. For scalability, spatially deterministic placement of quantum dots in bullseye cavities is pursued and techniques for tuning by electric and strain fields are implemented. To apply electric fields, a new device design for electrically contactable circular Bragg grating cavities in labyrinth geometry is employed [4]. We report on the challenges experienced in obtaining high performance devices based on circular Bragg grating cavities and figures of merits achieved, outlining the prospects for these devices in quantum technology applications. We are grateful for financial support of this work by the German Federal Ministry of Education and Research (BMBF) within the projects Q.Link.X, QR.X, MHLASQU, PhotonQ and QD-E-QKD. Expert technical assistance by Silke Kuhn, Adriana Wolf and Margit Wagenbrenner is gratefully acknowledged. 1. C.-Y. Lu and J.-W. Pan, Nature Nanotechnology 16, 1294-1296 (2021) 2. J. Scheuer and A. Yariv, IEEE J. Quantum Electron. 39, 1555-1562 (2003) 3. M. Davanco, M. T. Rakher, D. Schuh, A. Badolato, and K. Srinivasan, Appl. Phys. Lett. 99, 041102 (2011) 4. Q. Buchinger, S. Betzold, S. Höfling and T. Huber-Loyola, Appl. Phys. Lett. 122, 111110 (2023)

Seminar über Theorie der kondensierten Materie / TRR146 Seminar

F. Schmid / G. Settanni / P. Virnau / L. Stelzl

14:30 Uhr s.t., Minkowski Room, 05-119, Staudingerweg 7,

Bettina Keller, Freie Universität Berlin
Rare-event simulations with Girsanov reweighting

26 Jun 2023

Seminar about Experimental Particle and Astroparticle Physics (ETAP)

Institut für Physik

12:30 Uhr s.t., Staudingerweg 7, Minkowskiraum

Jack MacDonald, Institut für Physik
First physics results from the FASER experiment
at Zoom

RIND seminar on Mathematical Physics and String Theory

U. Mainz, LMU Munich, U. Heidelberg, U. Vienna

16 Uhr c.t.

Kai Cieliebak, Augsburg
Algebraic structures arising in string topology and Rabinowitz Floer homology
at Zoom

27 Jun 2023

Physikalisches Kolloquium

Institut für Kernphysik

16:15 Uhr s.t., HS KPH

Prof. Kate Scholberg, Duke University - USA
Coherent elastic neutrino-nucleus scattering (CEvNS) is a process in which a neutrino scatters off an entire nucleus. It is tremendously challenging to detect, due to the tiny nuclear recoil. CEvNS was measured for the first time by the COHERENT collaboration using the unique source of neutrinos at the Oak Ridge National Laboratory Spallation Neutron Source. This talk will describe the physics reach of CEvNS, as well as COHERENT's measurements, status and future plans.

Seminar Festkörper- und Grenzflächenphysik KOMET - experimentell

Institut für Physik

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

Hendrik Meer, Institute of Physics
Control and manipulation of antiferromagnetic domains in insulating transition metal oxides

Theorie-Palaver

Institut für Physik

14:00 Uhr s.t., Lorentz room (Staudingerweg 7, 5th floor)

Maria Anayeli Ramirez Ortiz, Milano Bicocca
The AdS3/CFT2 correspondence provides the best arena to test the holographic duality. This is because there is a better understanding of how to quantise strings on AdS3, compared with the higher dimensional cases, and the relative tractability of two-dimensional CFTs. In spite of this, little effort has been made to construct and classify supersymmetric AdS3 solutions. With a focus in their CFT interpretation, in this talk I will show you new AdS3 solutions in massive type IIA supergravity preserving small N=(4,0) supersymmetry. From the geometry, we engineer the dual CFT with well-known tools and propose a duality with a precise family of quivers. Additionally, we compute field theory and holographic central charges showing a clean matching in both descriptions.

28 Jun 2023

PRISMA+ Colloquium

Institut für Physik

13:00 Uhr s.t., Lorentz-Raum, 05-127, Staudingerweg 7

Daniel Wenz, JGU Mainz
A rich number of astrophysical and cosmological observations indicate the existence of a massive, non-luminous and non-baryonic matter component which is commonly referred to as dark matter (DM). One well motivated class of DM are weakly interacting massive particles (WIMPs) which arise naturally from several beyond-Standard-model theories. The XENON dark matter project aims for the direct detection of WIMPs utilizing the concept of a dual-phase time projection chamber (TPC), currently operating the 4th generation of XENON experiment, XENONnT, at the INFN Laboratori Nazionali del Gran Sasso underground laboratory. XENONnT was designed as a fast upgrade of its predecessor XENON1T, augmented by many new subsystems -- among them the world's first water Cherenkov neutron veto. The XENONnT TPC features a sensitive liquid xenon mass of 5.9 t and an unprecedented low background of intrinsic 85Kr and 222Rn, leading to an electronic recoil background rate of (15.8 +/- 1.3) events / t year keV in the region of interest. In this seminar we will report on the first WIMP search results with the XENONnT experiment, conducted in a blind analysis in an energy range between 3.1 keV and 60.0 keV, and an exposure of approximately 1.1 tonne-year.
Slides here...

29 Jun 2023

GRK 2516 Soft Matter Seminar

Uni Mainz

14:30 Uhr s.t., Minkowski Room, 05-119, Staudingerweg 7

Benno Liebchen, TU Darmstadt, Physics
TBA
at Zoom

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

Institut für Physik

14:00 Uhr s.t., IPH Lorentzraum 05-127

Dr. Leif Schröder, Helmholtz Imaging + DKFZ Heidelberg
Chemical exchange processes play an important role for various soluble molecular systems with cavities. Hyperpolarized 129Xe gives insights into the underlying kinetics and structure parameters by providing a spin system that comes with several NMR spectroscopic advantages. It contributes to the understanding of synthetic molecules for binding greenhouse gases or characterizes hydrophobic pockets in naturally occurring proteins. This talk gives an overview how 129Xe is a powerful probe to explore such cavities. The nuclear spin of an inert gas is a useful “spy” that reveals, e.g., hidden states of different molecular symmetry. It also enables “spin counting” to quantify the attoliter volume in hollow protein structures. Such structures, normally used by bacteria to adjust their buoyancy in water, may one day also improve medical magnetic resonance imaging. Bacterial gas vesicles fill up with the harmless noble gas xenon according to the ideal gas law and have the potential to serve as powerful MRI contrast agents.

Seminar über die Physik der kondensierten Materie (SFB/TRR173 Spin+X und SFB/TR288 Kolloquium, TopDyn-Seminar)

JGU

14:00 Uhr s.t., 01-122 Newton Raum

Oleksandr V. Pylypovskyi, Helmholtz-Zentrum Dresden-Rossendorf e.V.
The geometry of magnetic objects at the nanoscale plays a crucial role in their properties. Conventionally, the respective phenomena were considered for a long time as a result of sample boundaries leading, e.g., to the formation of closed-flux magnetization distributions and the interaction of magnetic solitons with notches in racetracks. However, such a simplified picture omits the topological properties and symmetries of the sample. A quantitative approach to predict magnetic responses based on the geometry of magnetic nanoarchitectures is provided by the theory of curvilinear magnetism. In this talk, we will discuss analytical approaches and some experimental validations of theoretical predictions for curvilinear nanomagnets. The local bends and twists of low-dimensional ferromagnets enable chiral and anisotropic responses stemming from the exchange interaction. For the particular sample scale, these responses are complemented by the magnetostatics-induced symmetry breaks and the respective formation of multiple magnetochiral characteristics of the magnetic textures. Antiferromagnetic nanoobjects inherit particular properties of curvilinear ferromagnets and complement them with more complex properties of the Neel order parameter and field-induced spin-reorientation transitions.

03 Jul 2023

Seminar about Experimental Particle and Astroparticle Physics (ETAP)

Institut für Physik

12:30 Uhr s.t., Staudingerweg 7, Minkowskiraum

Emanuel Meuser, Institut für Physik
Phase-2 Upgrades for the ATLAS hardware trigger system and MZ firmware development for L0Global
at Zoom

RIND seminar on Mathematical Physics and String Theory

U. Mainz, LMU Munich, U. Heidelberg, U. Vienna

16 Uhr c.t.

Tony Pantev, U. Penn
Wild character varieties parametrize monodromy representations of flat meromorphic connections on compact Riemann surfaces. They are classical objects with remarkable geometric and topological properties. In the past twenty years new insights from algebraic geometry lead to precise conjectures on the topological structure and complexity of character varieties. I will recall some of these conjectures and will sketch a strategy for approaching them. In particular I will describe recent joint works with Chuang, Diaconescu, Donagi, and Nawata in which we use dualities in geometry and physics to extract cohomological invariants of wild character varieties from enumerative Calabi-Yau geometry and refined Chern-Simons invariants of torus knots.
at Zoom

04 Jul 2023

Physikalisches Kolloquium

Institut für Kernphysik

16:15 Uhr s.t., HS KPH

Prof. Paul Indelicato, University of Sarbonne - France
Quantum electrodynamics (QED) is part of the standard model and the best understood quantum field theory. Many tests exist, from free particles (electron and muon anomalous magnetic moment) to bound states. From the historical measurement of the Lamb-shift which lead to the advent of QED and field theories, many systems have been studied and compared to the most advanced calculations. One can cite hydrogen, positronium, muonium, highly charged, few electron ions[1] and exotic atoms (atoms in which the electron is replaced by a heavier particle like a muon, a pion or an antiproton). In this talk I will present a few cases of highly charged ions high-precision results (few ppm accuracy) obtained with our Double Crystal Spectrometer in Paris[2-4] for medium-Z elements, and preliminary results obtained at GSI on few-electron uranium. I will then present new ideas [5] and first demonstration results on QED tests using muonic atoms and transition-edge sensor micro-calorimeter at JPARC [6, 7], and their extension to antiprotonic atoms at ELENA in the future. Detailed comparison with QED and relativistic many-body calculations when relevant will be made. [1]Topical Review: QED tests with highly-charged ions, P. Indelicato. J. Phys. B 52, 232001 (2019). [2]High-precision measurements of n=2->n=1 transition energies and level widths in He- and Be-like Argon Ions, J. Machado, C.I. Szabo, J.P. Santos et al. Phys. Rev. A 97, 032517 (2018). [3]Reference-free measurements of the 1s 2s 2p 2P1/2,3/2 → 1s2 2s 2S1/2 and 1s 2s 2p 4P5/2 → 1s2 2s 2S1/2 transition energies and widths in lithiumlike sulfur and argon ions, J. Machado, G. Bian, N. Paul et al. Phys. Rev. A 101, 062505 (2020). [4]Absolute measurement of the relativistic magnetic dipole transition in He-like sulfur, J. Machado, N. Paul, G. Soum-Sidikov et al. Phys. Rev. A in press, (2023). [5]Testing Quantum Electrodynamics with Exotic Atoms, N. Paul, G. Bian, T. Azuma et al. Phys. Rev. Lett. 126, 173001 (2021). [6]Deexcitation Dynamics of Muonic Atoms Revealed by High-Precision Spectroscopy of Electronic K X Rays, T. Okumura, T. Azuma, D.A. Bennett et al. Phys. Rev. Lett. 127, 053001 (2021). [7]Proof-of-Principle Experiment for Testing Strong-Field Quantum Electrodynamics with Exotic Atoms: High Precision X-ray Spectroscopy of Muonic Neon, T. Okumura, T. Azuma, D.A. Bennett et al. Phys. Rev. Lett. in press, (2023).

Theorie-Palaver

Institut für Physik

14:00 Uhr s.t., Lorentz room (Staudingerweg 7, 5th floor)

Pouria Mazloumi, MPP Munich
In this talk, I will discuss different types of integrals over moduli space of punctured Riemann surfaces. First, I start with string scattering amplitudes and progress to the intersection number of twisted forms over the Riemann surface. I will discuss the equivalency between the two integrals and how this relation can be used to produce QFT (tree-level) amplitudes. In particular, I explore the double copy construction in amplitudes, which states that gravitational amplitudes can be expressed in terms of two sets of Yang-Mills amplitudes i.e.gravity=(gauge X gauge). I will motivate a formal construction of double copy in terms of the twisted cohomology and explain its relation to other forms of the double copy such as BCJ double copy and color kinematic duality. I will finish by discussing the possibility of extending this formalism into the loop level in both string and QFT amplitudes.

06 Jul 2023

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

Institut für Physik

14:00 Uhr s.t., IPH Lorentzraum 05-127

Prof. Dr. Daniel Rodriguez, Universidad de Granada
Penning traps are used to perform motional-frequency measurements to deliver the most precise and accurate cyclotron-frequency values of many atomic/molecular ions and charged (anti)particles. By applying laser cooling, it is possible to better control those effects arising from deviations of the Penning trap from the ideal configuration. Since laser cooling can be only performed on a few ion species, a single laser-cooled (auxiliary) ion can be used to cool the target ion, forming an ordered structure along the magnetic-field axis of the Penning trap. At the University of Granada, we have built a 7-T Penning-trap platform and generated the (unbalanced) Coulomb crystals 42Ca+-40Ca+, 232Th+ -40Ca+ and 232ThO+-40Ca+, establishing the basis to perform quantum Penning-trap mass spectrometry and with prospects to explore laser-spectroscopy. In this talk, I will present the first Penning-trap eigenfrequency measurements using two-ion Coulomb crystals, from the detection of fluorescence photons, and will show the work carried out towards the final goal in our lab, including the recent upgrade of the laboratory after the installation of a new cryogen-free magnet.

07 Jul 2023

Seminar über Theorie der kondensierten Materie / TRR146 Seminar

F. Schmid / G. Settanni / P. Virnau / L. Stelzl

14:30 Uhr s.t., Minkowski Room, 05-119, Staudingerweg 9

Erik Kalz and Abhinav Sharma, Leibniz-Institut für Polymerforschung Dresden & TU Dresden
The Physics of Odd Systems

10 Jul 2023

Seminar about Experimental Particle and Astroparticle Physics (ETAP)

Institut für Physik

12:30 Uhr s.t., Staudingerweg 7, Minkowskiraum

Florian Thomas, Institut für Physik
Neutrino Mass Sensitivity of Project 8
at Zoom

11 Jul 2023

Physikalisches Kolloquium

Institut für Kernphysik

16:15 Uhr s.t., HS KPH

Prof. Susana Cardoso de Freitas, INESC MN University of Lisboa - Portugal
Magnetic field sensors have a mature and transversal level of implementation in the market, from automotive to biomedical domains. The impressive technological progress in thin film preparation and characterization, combined with nano-microfabrication tools offer presently large spectra for device design. The materials discussed include several varieties of thin film materials combined onto multilayer stacks. In addition, the noise mechanisms (the “killing factor” that limits the MR sensor performance) will be discussed, and I will show successful strategies for improving the signal-to-noise ratio, improving the ultimate field detectable by an MR sensor. Examples where spintronic sensors are useful tools for precision sensing will be provided, including integration with microfluidics, optical and MEMS micromachined actuators. During my talk, I will show how challenging applications have identified creative solutions, requiring joint skills in transversal areas as physics, materials, electronics and mechanical engineering.

Seminar Festkörper- und Grenzflächenphysik KOMET - experimentell

Institut für Physik

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

Olga Lozhkina, Institute of Physics
Domain wall propagation in soft magnetic wires with periodical width modulation

Theorie-Palaver

Institut für Physik

14:00 Uhr s.t., Lorentz room (Staudingerweg 7, 5th floor)

Cristina Benso, MPIK Heidelberg
In our current understanding of the universe, the fundamental nature of one of its most abundant constituents, the dark matter (DM), is still a mystery. Among the many theorized candidates to play the role of DM, in this talk I will focus on sterile neutrinos with mass of O(keV) and in particular on their production in the early universe and phenomenology in terrestrial experiments today. The simplest mechanism able to produce sterile neutrino DM in the early universe is named Dodelson-Widrow mechanism after its inventors. Although very fascinating due to its extreme simplicity, if we assume that sterile neutrinos constitute the entire abundance of DM today this vanilla solution is, on the one hand, far from the region of the parameter space in which near future experiments will be sensitive to such particles and, on the other hand, mostly excluded by X-ray observations. After introducing the standard/vanilla scenario, I will discuss three minimal modifications to the standard scenario that change drastically the perspectives of detection of this DM candidate in the near future. They have to do with the following questions. What if before Big Bang Nucleosynthesis the universe evolved differently with respect to what is usually assumed? Should we consider the X-ray bound to be absolute or model dependent? What if active neutrinos interact among each other also with non-standard interactions?

12 Jul 2023

PRISMA+ Colloquium

Institut für Physik

13:00 Uhr s.t., Lorentz-Raum, 05-127, Staudingerweg 7

Prof. Dr. Thomas Schwetz, KIT Karlsruhe
In this talk the referent reviews the recent status of the hypothesis of sterile neutrinos with masses in the eV range, motivated by oscillation searches at short baselines. Indications for muon to electron neutrino transitions from the LSND and MiniBooNE experiments are in severe tension with constraints from disappearance experiments. Previous hints for electron neutrino disappearance at short-baseline reactor experiments are neither confirmed by recent data (among others from the STEREO experiment) nor supported by updated reactor flux determinations. However, previous indications from radio-active source experiments in gallium detectors have been recently confirmed by the BEST collaboration, which observes a neutrino-induced count rate about 20% lower than expected at about 5 sigma significance. However, an explanation in terms of sterile neutrinos is in strong tension with other constraints. If any of these anomalies is due to new physics, most likely more ingredients than sterile neutrino oscillations are required. The referent will comment on possible explanations of the gallium anomaly in terms of quantum decoherence.

13 Jul 2023

Seminar über Theorie der kondensierten Materie / TRR146 Seminar

F. Schmid / G. Settanni / P. Virnau / L. Stelzl

18:00 Uhr s.t., hybrid meeting, Minkowski Room, 05-119, Staudingerweg 7

Martin Vögele, Schrödinger
Hybrid meeting; ID: 814 7712 9515, Passcode: 008795

Time to be determined.

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

Institut für Physik

14:00 Uhr s.t., IPH Lorentzraum 05-127

Asst. Prof. Tracy Northup, Universität Innsbruck
Entanglement-based quantum networks hold out the promise of new capabilities for secure communication, distributed quantum computing, and interconnected quantum sensors. However, only a handful of elementary quantum networks have been realized to date. I will present results from our prototype network, in which two calcium ions are entangled with one another over a distance of 230 m, via a 520 m optical fiber channel linking two buildings. The ion-ion entanglement is based on ion-photon entanglement mediated by coherent Raman processes in optical cavities. I will discuss the advantages of trapped ions for quantum networks and the role that cavities can play as quantum interfaces between light and matter at network nodes. After examining the key metrics for remote entanglement, we will consider the necessary steps to extend this work to long-distance networks of entangled quantum processors.

17 Jul 2023

Seminar about Experimental Particle and Astroparticle Physics (ETAP)

Institut für Physik

12:30 Uhr s.t., Staudingerweg 7, Minkowskiraum

Moritz Hesping, Institut für Physik
Differential Measurement of Higgs Boson Associated Production with H-to-WW Decay at ATLAS
at Zoom

RIND seminar on Mathematical Physics and String Theory

U. Mainz, LMU Munich, U. Heidelberg, U. Vienna

16 Uhr c.t.

Lorenz Schlechter, Utrecht U.
TBA
at Zoom

18 Jul 2023

Seminar Festkörper- und Grenzflächenphysik KOMET - experimentell

Institut für Physik

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

Olena Tkach, Institute of Physics
Recent developments in ToF momentum microscopy

Physikalisches Kolloquium

Institut für Kernphysik

16 Uhr c.t., HS KPH

Prof. Dr. Winfried Barth, GSI Helmholtzzentrum für Schwerionenforschung GmbH
Research on and with ions has been the subject of current scientific activities for some time. In particular, heavy ions with very different particle energies are of increasing interest. The provision of electrically charged "heavy" particle fluxes of high density and the acceleration of these particle beams is therefore of particular importance and has grown into an almost independent focus of research and development. In the talk, a brief outline of the past development of key technologies for accelerating heavy ions, especially in linear accelerators, will be given. The heavy ion linear accelerator at GSI in Darmstadt has to be upgraded for the future as a synchrotron-injector for highest intensities. In addition, the HElmholtz LInear ACcelerator HELIAC, a superconducting accelerator with the highest continuous wave intensities for heavy ion beams in the medium energy segment, is currently being designed and construction has already begun. These brand-new developments will also be presented. Die Forschung an und mit Ionen ist seit längere Zeit Gegenstand aktueller wissenschaftlicher Aktivitäten. Insbesondere schwere Ionen mit sehr unterschiedlicher Teilchenenergie sind dabei von zunehmendem Interesse. Die Bereitstellung elektrisch geladener "schwerer" Teilchenflüsse hoher Dichte und der Beschleunigung dieser Teilchenstrahlen kommt daher besondere Bedeutung zu und ist zu einem fast eigenständigen Schwerpunkt der Forschung und Entwicklung gewachsen. Im Vortrag soll ein kurzer Abriss der vergangenen Entwicklung der Schlüsseltechnologien zur Beschleunigung schwere Ionen insbesondere in Linear-beschleunigern gegeben werden. Der Schwerionenlinearbeschleuniger der GSI in Darmstadt muss für die Zukunft als Synchrotron-Injektor für höchste Intensitäten aufgerüstet werden. Darüber hinaus wird zurzeit mit dem HElmholtz LInear ACcelerator HELIAC ein supraleitender Beschleuniger mit höchstem Dauerstrichintensitäten für Schwerionenstrahlen im mittleren Energiesegment konzipiert und auch bereits begonnen zu bauen. Diese brandaktuellen Neuentwicklungen sollen ebenfalls dargestellt werden.

19 Jul 2023

PRISMA+ Colloquium

Institut für Physik

13:00 Uhr s.t., Lorentz-Raum, 05-127, Staudingerweg 7

Dr. Rodolfo Ferro-Hernandez, JGU Mainz
The fine structure constant is a fundamental parameter in the Standard Model, playing a crucial role in computing a wide range of observables and consistency relations. While the current error on $\Delta\alpha(M_Z)$ is at the level of $\sim10^{-4}$, future requirements, such as those of the FCC-ee/ILC, demand a reduction. In this talk, the referent presents an updated calculation of the hadronic contribution to $\Delta\alpha(M_Z)$. He will review different computational methods, such as the explicit integration in the timelike , renormalization group equations (RGE), and the euclidean split technique. The results emphasize the importance of accurately accounting for the charm quark contributions.

20 Jul 2023

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

Institut für Physik

14:00 Uhr s.t., IPH Lorentzraum 05-127

Asst. Prof. Dylan Yost, Colorado State University
Because of atomic hydrogen’s simplicity, its energy levels can be precisely described by theory. This has made hydrogen an important atom in the development of quantum mechanics and quantum electrodynamics (QED). While one can use hydrogen spectroscopy to determine the Rydberg constant and the proton charge radius, a discrepancy of these constants determined through different transitions, or in different species, can indicate new physics. Such discrepancies currently persist between different measurements in hydrogen and muonic hydrogen. With this motivation in mind, I will discuss several precision spectroscopy measurements of hydrogen as Colorado State University including a relatively recent measurement of the hydrogen 2S-8D two-photon transition, a measurement of the hydrogen 2S hyperfine splitting, and our future plans to measure several relatively narrow 2S-nS transitions in hydrogen. If these latter measurements are successful, they could provide some of the most precise measurements of the Rydberg constant along with insight into the experimental discrepancies.

Seminar über Theorie der kondensierten Materie / TRR146 Seminar

F. Schmid / G. Settanni / P. Virnau / L. Stelzl

14:30 Uhr s.t., Online

Jerelle Joseph, Princeton University
Accurate models for interrogating and engineering biomolecular condensates

21 Jul 2023

Theorie-Palaver

Institut für Physik

14:00 Uhr s.t., Lorentz room (Staudingerweg 7, 5th floor)

Elias Bernreuther, Fermilab
Searches for long-lived particles (LLPs) are a rapidly expanding frontier at the LHC and other collider experiments. Still, many gaps remain in the current search program, in particular for LLPs with masses at the GeV or sub-GeV scale and with very large decay lengths. In this talk, I will illustrate two different approaches to filling this gap by discussing two models of light LLPs and their associated collider signals. First, I will show that the dominant decay mode of vectorlike leptons can be a very long-lived pseudoscalar and a tau lepton and argue that the muon chambers of CMS or ATLAS are ideal places to search for this final state. Second, I will illustrate the excellent sensitivity of Belle II to light LLPs with meter-scale decay lengths using the example of displaced vertex signals from strongly interacting dark sectors.

25 Jul 2023

Theorie-Palaver

Institut für Physik

14:00 Uhr s.t., Lorentz room (Staudingerweg 7, 5th floor)

Tin Sulejmanpasic, Durham U.
I will introduce a formalism for abelian lattice gauge theories called the Modified Villain Action formalism, which has been popular in recent years for constructing abelian gauge theories with correct symmetries and anomalies of their continuum counterparts. I will then show that this formalism can be used to write down a \(U(1)\) Chern-Simons theory on the lattice for even levels. The theory we construct suffers from the peculiar zero modes of the Gaussian differential operator which are infamous in the literature for plaguing the Chern-Simons theory with unphysical modes. I will show that such modes are related to a peculiar subsystem symmetry of a space-time lattice. This symmetry causes almost all Wilson loops to vanish. However Wilson loop-like operators with strip-like topology survive the pernicious symmetry and are topological, exactly like one expects in the continuum. Further the strip-like topology of the loops is a lattice realization of a well known phenomenon in continuum called the framing anomaly. I will further argue, time permitting, that the pernicious symmetry is really a form of gauge symmetry, projecting out certain states from the Hilbert space, and that it is not associated with any physical significance.

10 Aug 2023

Seminar über die Physik der kondensierten Materie (SFB/TRR173 Spin+X und SFB/TR288 Kolloquium, TopDyn-Seminar)

JGU

14:00 Uhr s.t., 01-122 Newton Raum

Dr. Naoto Yamashita, Department of I&E Visionaries Faculty of Information Science and Electrical Engineering Kyushu University
Spin Metal-Oxide-Semiconductor Field-Effect transistor (MOSFET) is a promising device [1] that utilizes the fundamental material in electronics: silicon (Si). In 2007, the electrical injection of spin current into Si was achieved, overcoming the challenge of "conductance mismatch" [2]. Over the past decade, extensive research has been devoted to studying the transport of spin current in Si, resulting in the realization of room temperature operation [3]. In our investigations to enhance the magnetoresistance ratio, we have focused on understanding the physics of the metal/Si interface and proposed three different approaches [4-6]. Firstly, we have made progress by improving the crystal alignment between the spin source material and the tunneling barrier through moderate-temperature thermal annealing [4]. Secondly, we have demonstrated the spin-dependent Seebeck effect, a novel spin caloritronic effect, for the first time using semiconducting materials [5]. Lastly, we have achieved a significant reduction in electrical resistance at the interface by implementing ohmic contact on non-degenerate n-type Si with ferrimagnetic material, resulting in a 100-fold improvement [6]. By leveraging these technologies, we anticipate a notable improvement in the magnetoresistance ratio, bringing us closer to practical device applications. Reference [1] S. Sugahara and M. Tanaka, Appl. Phys. Lett. 84, 2307 (2004). [2] I. Appelbaum, B. Huang, and D. J. Monsma, Nature 447, 295-298 (2007). [3] T. Tahara, Y. Ando, M. Shiraishi, et al., Appl. Phys. Express 8, 113004 (2015). [4] N. Yamashita, Y. Ando, M. Shiraishi, et al., AIP Advances 10, 095021 (2020). [5] N. Yamashita, Y. Ando, M. Shiraishi, et al., Phys. Rev. Applied 9, 054002 (2018). [6] N. Yamashita, M. Shiraishi, Y. Ando, et al., Phys. Rev. Materials 6, 104405 (2022).

07 Sep 2023

Seminar über Theorie der kondensierten Materie / TRR146 Seminar

F. Schmid / G. Settanni / P. Virnau / L. Stelzl

13:30 Uhr s.t., Online

Yuichi Masubuchi, Department of Materials Physics, Nagoya University, Japan
Effect of node functionality on the fracture of polymer networks

14 Sep 2023

GRK 2516 Soft Matter Seminar

Uni Mainz

14:30 Uhr s.t., Minkowski Room, 05-119, Staudingerweg 7

Mike Howard, Chemical Engineering, Auburn University, USA
Materials made from nanoparticles (NPs) have highly versatile applications, ranging from household products such as paint to functional materials used for catalysis and optoelectronics. The properties of such materials can be tailored through the chemistry of their NPs as well as the NP composition within the material. A common method to prepare such materials is to disperse the NPs in a solvent at a low volume fraction, then remove the solvent to assemble the NPs into a solid. For example, solvent drying from planar surfaces has been used to make abrasion- and bacteria-resistant NP coatings, while solvent drying from spherical droplets has been used to make porous supraparticles with significant internal void space that is promising for catalysis, photonics, and sorption. The mesoscopic structure of the NPs within these materials is known to depend on both properties of the NPs and the drying conditions; however, predicting it is challenging because the NP self-assembly involves confined molecular thermodynamics and nonequilibrium transport. In this seminar, I will discuss our efforts to use both particle-based simulations and continuum modeling (dynamic density functional theory) to model drying-induced assembly in colloidal suspensions. The two types of models shed different insights into the self-assembly process at different scales. Our principal finding is that solvent-mediated hydrodynamic interactions between NPs play a critical role in the drying process that must be captured to faithfully resolve the final structure in many cases. In future, we envision using these models to design NPs and drying processes to assemble them into materials with targeted compositions.
at Zoom

Seminar über Theorie der kondensierten Materie / TRR146 Seminar

F. Schmid / G. Settanni / P. Virnau / L. Stelzl

14:30 Uhr s.t., Minkowski Room, 05-119, Staudingerweg 7

Mike Howard, Chemical Engineering, Auburn University, USA
GRK 2516 Soft Matter Seminar

22 Sep 2023

Theorie-Palaver

Institut für Physik

Sonderseminar: 10 Uhr c.t., THEP seminar room (05-427)

Hidenori SONODA, Kobe University
I would like to explain how the construction of a Wilson action in the exact renormalization group (ERG) formalism is related to diffusion equations for the fields. By making the diffusion equations gauge covariant, we have managed to linearize the BRST invariance of U(1) gauge theories. But with YM theories, the BRST invariance remains non-linear, and we have not been able to solve the constraint. All this has been done in collaboration with Hiroshi Suzuki (Kyushu University).

Sonderseminar

25 Sep 2023

MMA 23 Conference (Sept 25th-28th)

Johannes Gutenberg-Universität Mainz, Institut für Physik

8:00 Uhr s.t., Alte Mensa, Johann-Joachim-Becher-Weg 3, 55128 Mainz

Dr. Martin Letz, SCHOTT AG
12th International Conference on Microwave Materials and their Applications (MMA23 from 25th to 29th September 2023)