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Aktuelle Veranstaltungen

 

Kolloquium

Thema:

tba

Datum:

01.02.21

Uhrzeit:

16:15

Ort:

cyberspace

Vortragender:

JProf. Francesca Cuteri

Goethe-Universität Frankfurt

Inhalt:

Ansprechpartner:

F. Karsch/TR211

Kolloquium Mathematische Physik

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

Seminar Hochenergiephysik

Thema:

The muon g-2

Datum:

20.10.20

Uhrzeit:

14:15

Ort:

cyberspace

Vortragender:

Christoph Lehner

Uni Regensburg

Inhalt:

There is a long-standing 3-4 sigma tension between the standard model calculation and the BNL experimental result for the anomalous magnetic moment, g-2, of the muon. The Fermilab E989 experiment will soon release an improved result and commensurate improvements are in progress for the theory calculation. I am going to discuss the current status of experiment and theory with focus on first-principles calculations of the important hadronic vacuum polarization and hadronic light-by-light contributions.

Ansprechpartner:

Ch. Schmidt

Seminar Kondensierte Materie

Thema:

Evaluation der Genauigkeit des Tschebyscheff-Algorithmus zur Bestimmung thermodynamischer Funktionen am Beispiel einer Heisenberg-Spin-Leiter

Datum:

11.09.20

Uhrzeit:

14:00

Ort:

ZOOM / Konferenzschaltung

Vortragender:

Henrik Schlüter

Universität Bielefeld

Inhalt:

Es wird eine Einführung in die numerische Berechnung thermodynamischer Funktionen mithilfe des Tschebyscheff-Algorithmus gegeben. Anschließend findet eine Bewertung der Ergebnisse am Beispiel einer Heisenberg-Spin-Leiter in Abhängigkeit der Tschebyscheff-Parameter statt.

Ansprechpartner:

Jürgen Schnack

Seminar Mathematische Physik

Thema:

Statistics of Extremes in Eigenvalue-counting Staircases

Datum:

04.06.20

Uhrzeit:

16:00

Ort:

ZOOM / Konferenzschaltung

Vortragender:

Yan Fyodorov

King's College London

Inhalt:

We consider the counting function (“spectral staircase”) for eigenvalues of a random unitary matrix, drawn from the corresponding beta-ensemble. Our goal is to characterize the statistics of maximum deviation of this staircase from its mean slope in a fixed interval, when size of the matrix N >>1. We will show that one-sided extremes can be addressed by exploiting a mapping onto the statistical mechanics of log-correlated random processes and using an extended Fisher-Hartwig conjecture. The resulting statistics exhibits combined features of counting statistics of Fermions with Sutherland-type interaction and extremal statistics of the fractional Brownian motion with Hurst index H = 0. Some of the features are expected to be universal. The talk is based on the paper Fyodorov-Le Doussal arXiv:2001.04135.

Ansprechpartner:

Gernot Akemann

Seminar Bielefeld-Melbourne Zufallsmatrizen

Thema:

On absolute continuity of limiting spectral distributions of random Toeplitz and Hankel matrices

Datum:

21.10.20

Uhrzeit:

09:00

Ort:

ZOOM / Konferenzschaltung

Vortragender:

Manjunath Krishnapur

Indian Institute of Science, Bangalore

Inhalt:

While the method of moments is an effective method of proving the existence of limiting spectral distributions for many models of random matrices, it does not reveal properties of the limiting distribution such as absolute continuity or unimodality. In this talk we work with random Toeplitz and Hankel matrices and show the absolute continuity of the corresponding limiting distributions. The existence of the limiting distribution was already shown by Hammond-Miller and Bryc-Dembo-Jiang (~2003) and the absolute continuity was settled for the Toeplitz case by Sen and Virag (2011). The result is new for the Hankel matrix. Our methods also work for Toeplitz and Hankel matrices defined by certain other groups such as Z^d. The key idea is to write the random matrix under consideration as a sum of two or more independent random circulant-like matrices. All this is joint work with Anish Mallick.

Ansprechpartner:

Anas Rahman



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  • | Letzte Änderung: 30.06.2020
  •  Olaf Kaczmarek
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