Topic: 
Statistical Mechanical Perspectives on Cosmological Puzzles 
Date: 
19.04.21 
Time: 
16:15 
Place: 
cyberspace 
Guest: 

KU Leuven 

Abstract: 
We review some wellknown paradoxes in cosmology and give a statistical mechanics reading. Puzzles to be touched include the horizon and the flatness problem, the information paradox, the dark energy problem and the origin of the so called space roar. Each time, we emphasize the role of statistical arguments to complement the dynamical understanding. In the end, we argue, statistical mechanics clarifies important aspects of the problems and has a great future in contributing to the understanding of newly observed "fluctuation" features of our cosmos. 
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Topic: 
Integrability and Universality in nonlinear waves 
Date: 
05.02.21 
Time: 
16:15 
Place: 
ZOOM/Konferenzschaltung 
Guest: 

University of Bristol 

Abstract: 
What is an integrable system? Intuitively, an integrable system is a dynamical system that can be integrated directly. While in principle integrable systems should be very rare, it happens that in nature, a lot of fundamental systems are integrable such as many models of nonlinear waves, models in statistical mechanics and in theory of random matrices. The study of nonlinear waves has led to many remarkable discoveries, one of them being 'solitons', found some 50 years ago. Solitons motivated the development of the Inverse Scattering Transform (IST). History and some examples will be discussed. Finally I will present some universality results about small dispersion limits and semiclassical limits of nonlinear dispersive waves. 
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Topic: 
Is Our Universe the Remnant of Chiral Anomaly in Inflation? 
Date: 
27.04.21 
Time: 
14:15 
Place: 
Online, via ZOOM 
Guest: 

CERN, Geneva 

Abstract: 
Modern cosmology has been remarkably successful in describing the Universe from a second after the Big Bang until today. However, its physics before that time is still much less certain. It profoundly involves particle theory beyond the Standard Model to explain longstanding puzzles: the origin of the observed matter asymmetry, nature of dark matter, massive neutrinos, and cosmic inflation. In this talk, I will explain that a new framework based on embedding axioninflation in leftright symmetric gauge extensions of the SM can possibly solve and relate these seemingly unrelated mysteries of modern cosmology. The baryon asymmetry and dark matter today are remnants of a pure quantum effect (chiral anomaly) in inflation which is the source of CP violation in inflation. As a smoking gun, this setup has robust observable signatures for the GW background to be probed by future CMB missions and laser interferometer detectors. 
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Topic: 
Verschoben: Enhanced Convergence of Quantum Typicality using a Randomized LowRank Approximation 
Date: 
15.04.21 
Time: 
14:39 
Place: 
ZOOM / Konferenzschaltung 
Guest: 
Phillip Weinberg 
Northeastern University Boston 

Abstract: 

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Topic: 
The Character Expansion in effective Theories for chiral Symmetry Breaking 
Date: 
03.12.20 
Time: 
16:30 
Place: 
ZOOM / Konferenzschaltung 
Guest: 

Universität Bielefeld 

Abstract: 

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Topic: 
Products of Random Matrices and their real Eigenvalues 
Date: 
14.04.21 
Time: 
09:00 
Place: 
ZOOM / Konferenzschaltung 
Guest: 

University of Bristol 

Abstract: 
Recently there has been a wave of research into products of real asymmetric random matrices. Because these random matrices are asymmetric, they have both real and complex eigenvalues, with the number of each being random. The real eigenvalues of an asymmetric random matrix interact in an interesting way with taking products, in particular, longer products tend to lead to more real eigenvalues. We look at a particular ensemble, products of socalled "truncated orthogonal" matrices and prove a conjecture about the number of real eigenvalues and their distribution along the real line. Proving this conjecture amounted to a problem in asymptotic analysis, and I will go over the key tricks we used to carry this out. This was joint work with Francesco Mezzadri (Bristol) and Nicholas Simm (Sussex). Our paper can be found here: https://arxiv.org/abs/2102.08842 
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