Thema:

Shine a light! When matter shatters

Datum:

08.06.20

Uhrzeit:

16:15

Ort:

cyberspace

Vortragender:

Prof. Dr. Tetyana Galatyuk

TU Darmstadt

Inhalt:

The microscopic properties of strong-interaction matter under extreme conditions of temperature and density is a topic of great interest. Matter in equilibrium radiates photons with a thermal spectrum revealing its temperature in the slope of the energy distribution. This is generalized for virtual photons, which materialize after a short time by creation of a pair of charged leptons (dileptons), for which their invariant mass takes the role of the energy as observable. In contrast to the case of photons, their spectral distribution is not affected by a blue (or red) shift. Moreover, dileptons offer the unique opportunity also to directly monitor in-medium electromagnetic spectral functions. Hence, dilepton spectra from strong-interaction medium reflect not only its temperature but also are sensitive to possible effects of a restoration of the spontaneously broken chiral symmetry. This talk will discuss important experimental results obtained so far at various facilities and the latest theoretical developments on emissivity of matter.

Ansprechpartner:

F. Karsch/TR211

Thema:

The problem of latency in estimating the Covid-19 replication number

Datum:

08.05.20

Uhrzeit:

16:15

Ort:

ZOOM/Konferenzschaltung

Vortragender:

Lorenzo Sadun

University of Texas at Austin

Inhalt:

Figuring out how to restart the world's economy without a resurgence of disease depends on understanding how contagious Covid-19 really is. However, estimates of the basic replication number $R_0$ vary greatly, with well-respected groups publishing estimates whose 95% confidence intervals don't even overlap. In this talk I'll go over the basic SIR and SEIR models of disease spread and present several different ways to treat the latency period between being exposed and becoming infectious. Simple SEIR models are unstable; working with a fixed set of data, small changes to the model can result in large changes to the estimated value of $R_0$. More realistic models are more complicated and are even less stable. The upshot is that we know much less about $R_0$ than is generally believed, and the error bars on the high side are particularly large. Containing the outbreak for an extended period may be a lot harder than our leaders think.

Ansprechpartner:

Gähler, Dr. Franz

Thema:

Hydrodynamic attractors, initial state energy and particle production in relativistic nuclear collisions

Datum:

19.05.20

Uhrzeit:

14:15

Ort:

cyberspace

Vortragender:

Aleksas Mazeliauskas

CERN

Inhalt:

The loss of information in a thermalizing system manifests itself as production of entropy. In relativistic nuclear collisions the final state entropy is proportional to the number of produced particles and therefore the measured particle multiplicities probe the entropy produced during the non-equilibrium evolution of quark-gluon matter. Thanks to the recent understanding of off-equilibrium dynamics using the concept of hydrodynamic attractors, we were able to establish a general relation between the initial state energy and the produced particle multiplicities in high-energy nuclear collisions. References: https://doi.org/10.1103/PhysRevLett.123.262301 https://doi.org/10.1103/PhysRevC.100.064903

Ansprechpartner:

S. Schlichting

Thema:

22-05-2020-14.15 hrs - D5-153 - Construction of tight binding models from ab initio calculations using maximally localized Wannier functions

Datum:

22.05.20

Uhrzeit:

14:15

Ort:

D5-153

Vortragender:

Thomas Benkenstein

Universtität Bielefeld

Inhalt:

Ansprechpartner:

Thomas Dahm

Thema:

CLTs for biorthogonal ensembles: Beyond the Strong Szegö Limit Theorem

Datum:

14.05.20

Uhrzeit:

16:00

Ort:

ZOOM / Konferenzschaltung

Vortragender:

Maurice Duits

KTH Stockholm

Inhalt:

In random matrix theory, the Strong Szegö Limit Theorem for Toeplitz determinants is a Central Limit Theorem for linear statistics for eigenvalues of a CUE matrix. Although this connection does exploit the determinantal structure for the CUE eigenvalues, it does not use the correlation kernel in an explicit way. This talk will be around a generalization of the Strong Szegö Limit theorem that implies CLTs for the moments of the empirical measure for Multiple Orthogonal Polynomials Ensembles. Such models include Gaussian Unitary Ensembles with external source, complex Wishart matrices, two matrix models and certain specializations of the Schur process. The talk is based on joint works with Jonathan Breuer and a recent joint work with Benjamin Fahs and Rostyslav Kozhan.

Ansprechpartner:

Gernot Akemann

Thema:

>>> 0900 hrs <<< Approaching Products Involving Hermitian Matrices with Harmonic Analysis

Datum:

27.05.20

Uhrzeit:

09:00

Ort:

ZOOM / Konferenzschaltung

Vortragender:

Mario Kieburg

University of Melbourne

Inhalt:

Products of random matrices have been successfully analytically studied from the viewpoint of harmonic analysis for the past five years. The reason of its feasibility has been born out of the explicit knowledge of some group integrals of the form of the Harish-Chandra integral resulting in determinantal point processes. Originally those products involved complex matrices and positive definite Hermitian matrices. Extending those to products involving arbitrary Hermitian matrices opened new possibilities in creating new local as well as global spectral statistics, but they have exhibited also analytical obstacles as shown by Forrester, Ipsen and Liu in their work considering products of complex induced Ginibre matrices with Hermitian matrices. Those obstacles are related to non-compact group structures due to the fact of positive and negative eigenvalues. Harmonic analysis helps to overcome these problems so that one can extend the result to non-Gaussian random matrices. I will report on this approach and which consequences the results yield.

Ansprechpartner:

Gernot Akemann