Wochenübersicht für die Woche vom

27 Nov 2023 bis 03 Dec 2023 (KW 48)

KW47 - KW48 - KW49 - KW50

28 Nov 2023

Physikalisches Kolloquium

Institut für Kernphysik

16 Uhr c.t., HS KPH

Prof. Eberhard Bodenschatz, MPI for Dynamics and Self-Organization, Göttingen
82 years ago, the mathematician Andrei Nikolayevich Kolmogorov postulated that a turbulent flow should have universal statistical self-similar properties. Independently, the flow researcher Ludwig Prandtl concluded similar results 4 years later. Nobel laureates Werner von Heisenberg and Carl-Friedrich von Weizsäcker and Lars Onsager each came to the same conclusion shortly thereafter. Over the years, the expected power laws have been refined, but it has not been possible to measure them at very high turbulence level necessary. Simulations of driven turbulence on the world's largest computers provide evidence of this statistical universality. These simulations are highly idealized, they live in a periodic box, and the energy is introduced globally on large scales. Experimentally, this kind of turbulent flow is not feasible. So the question is: what do experiments show? For more than 100 years, the wind tunnel has been the canonical flow regime for turbulence research. When a fluid flows through a grid at high velocity, vortices form and decay after a short time; the flow then exhibits the universal statistical properties of turbulence. Today, electronics are highly optimized and there are the smallest hotwires made with advanced nanotechnology. This also makes it possible to measure velocities on the smallest length scales. However, very high turbulence intensity is required to measure universal static properties. In the past, experiments were mainly performed with air (hence the name wind tunnel). When using air at atmospheric pressure, the wind tunnel would have to be huge in diameter to achieve extremely high turbulence intensity to test Kolmogorov like theories. This is where the Variable Density Turbulence Tunnel (VDTT) at the Max Planck Institute for Dynamics and Self-Organization comes in. Among others, I will present recent results showing that universality is found, albeit with spatially dependent logarithmic dependence of the power-law exponents.
Slides here...


Institut für Physik

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

Stefano De Angelis, IPhT, Saclay
In the first part of the seminar, I will review some recent progress made using modern on-shell techniques to understand (relativistic) EFTs and uncover hidden structures, with a particular focus on the SMEFT (from a purely on-shell construction of EFTs to selection rules in cross-section and RG equations). Motivated by this recent progress, in the second part, I will present a new on-shell formula for the matching of ultraviolet models featuring massive states onto their massless effective field theory. This formula is based on a dispersion relation in the space of complex momentum dilations to capture, in a single variable, the relevant analytic structure of scattering amplitudes at any multiplicity.

Seminar Festkörper- und Grenzflächenphysik KOMET - experimentell

Institut für Physik

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

Tobias Sparmann, JGU


29 Nov 2023

PRISMA+ Colloquium

Institut für Physik

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

Prof. Dr. Laura Lopez Honorez, Univ. Brussels, Belgium
Compelling data from Cosmology tell us that more than 80% of the matter content of the universe is made of Dark Matter (DM). Yet the fundamental properties of DM is still unknown. In my talk, I will assume that DM is a particle beyond the Standard Model of Particle physics. You usually hear that DM should be cold and not hot. Yet it can be warm. The referent will discuss under which condition "non-cold" dark matter can be a good candidate to account for all the DM. In this framework, she will briefly present different mechanisms for dark matter production. She will also show that, even when dark matter interacts very feebly with visible matter, the interplay between particle physics and cosmology experiments is a key in probing the dark matter nature.

zukünftige Termine
30 Nov 2023

GRK 2516 Soft Matter Seminar

Uni Mainz

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

Dijkstra, Marjolein, Computational Condensed Matter, Utrecht University
Predicting the emergent properties of a material from a microscopic description is a scientific challenge. Machine learning and reverse-engineering have opened new paradigms in the understanding and design of materials. However, this approach for the design of soft materials is highly non-trivial. The main difficulty stems from the importance of entropy, the ubiquity of multi-scale and many-body interactions, and the prevalence of non-equilibrium and active matter systems. The abundance of exotic soft-matter phases with (partial) orientation and positional order like liquid crystals, quasicrystals, plastic crystals, along with the omnipresent thermal noise, makes the classification of these states of matter using ML tools highly non-trivial. In this talk, I will address questions like: Can we use machine learning to autonomously identify local structures [1,2], detect phase transitions [1], classify phases and find the corresponding order parameters [2], can we identify the kinetic pathways for phase transformations [1], and can we use machine learning to coarse-grain our models [3,4,5]? Finally, I will show in this lecture how one can use machine learning to reverse-engineer the particle interactions to stabilize nature’s impossible phase of matter, namely quasicrystals [6]? [1] An artificial neural network reveals the nucleation mechanism of a binary colloidal AB13 crystal G.M. Coli and M. Dijkstra, ASC Nano 15, 4335-4346 (2021). [2] Classifying crystals of rounded tetrahedra and determining their order parameters using dimensionality reduction R. van Damme, G.M. Coli, R. van Roij, and M. Dijkstra, ACS Nano 14, 15144-15153 (2020). [3] Machine learning many-body potentials for colloidal systems G. Campos-Villalobos, E. Boattini, L. Filion and M. Dijkstra, The Journal of Chemical Physics 155 (17), 174902 (2021). [4] Machine-learning effective many-body potentials for anisotropic particles using orientation-dependent symmetry functions G. Campos-Villalobos, G. Giunta, S. Marín-Aguilar and M. Dijkstra, The Journal of Chemical Physics 157 (2), 024902 (2022). [5] Coarse-Grained Many-Body Potentials of Ligand-Stabilized Nanoparticles from Machine-Learned Mean Forces G. Giunta, G. Campos-Villalobos, and M. Dijkstra, ACS Nano (2023). [6] Inverse design of soft materials via a deep learning–based evolutionary strategy G.M. Coli, E. Boattini, L. Filion, and M. Dijkstra, Science Advances 8 (3), eabj6731 (2022).
at Zoom

Seminar über Theorie der kondensierten Materie / TRR146 Seminar

K. Binder/ A. Nikoubashman / F. Schmid / G. Settanni / T. Speck / M. Sulpizi / P. Virnau

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

Marjolein Dijkstra, Computational Condensed Matter, Utrecht University
GRK 2516 Soft Matter Seminar

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

Institut für Physik

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

Prof. Dr. Catalina Curceanu, INFN, Rom/Italy
We are experimentally investigating possible departures from the standard quantum mechanics’ predictions at the Gran Sasso underground laboratory in Italy. In particular, with refined radiation detectors, we are searching signals predicted by the dynamical collapse models (spontaneous emission of radiation) which were proposed to solve the “measurement problem” in quantum physics, and signals indicating a possible violation of the Pauli Exclusion Principle. I shall discuss our recent results which ruled out the natural parameter-free version of the gravity-related collapse model. I shall then present more generic results on testing CSL (Continuous Spontaneous Localization) collapse models and discuss future perspectives. Finally, I shall present the VIP experiment, with which we search for possible violations of the Pauli Exclusion Principle manifested as “impossible” atomic transitions, and muse about the impact of this research in relation to Quantum Gravity models.

01 Dec 2023

THEP Journal Club

Institut für Physik

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

Anke Biekötter, JGU Mainz
SMEFT Analyses for New Physics (TBA)