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Aktuelle Veranstaltungen

 

Kolloquium

Thema:

Used Nuclear Fuel - Past, Present, and Future

Datum:

29.01.18

Uhrzeit:

16:15

Ort:

H6

Vortragender:

Dr. Maik Stuke

Gesellschaft für Anlagen- und Reaktorsicherheit (GRS) gGmbH

Inhalt:

After a short introduction and overview of the company GRS I will focus on the past, present, and future of nuclear fuel used in German nuclear reactors. A summary of the origin and composition of different types of used nuclear fuel will be followed by an overview of the current situation and future plans of storage. This includes an overview of the foreseen steps until a final repository. I summarize my talk by discussing some open scientific questions.

Ansprechpartner:

D. Schwarz

Kolloquium Mathematische Physik

Thema:

Mesoscopic eigenvalue correlations of random matrices

Datum:

01.12.17

Uhrzeit:

16:00

Ort:

V2-210/216

Vortragender:

Antti Knowles

University of Geneva

Inhalt:

Ever since the pioneering works of Wigner, Gaudin, Dyson, and Mehta, the correlations of eigenvalues of large random matrices on short scales have been a central topic in random matrix theory. On the microscopic spectral scale, comparable with the typical eigenvalue spacing, these correlations are now well understood for Wigner matrices thanks to the recent solution of the Wigner-Gaudin-Dyson-Mehta universality conjecture. In this talk I focus on eigenvalue density-density correlations between eigenvalues whose separation is much larger than the microscopic spectral scale; here the correlations are much weaker than on the microscopic scale. I discuss to what extent the Wigner-Gaudin-Dyson-Mehta universality remains valid on such larger scales, for Wigner matrices and random band matrices.

Ansprechpartner:

G. Akemann

Seminar Hochenergiephysik

Thema:

Patterns and partners for chiral and $U(1)_A$ restoration

Datum:

16.01.18

Uhrzeit:

14:15

Ort:

D6-135

Vortragender:

Angel Gomez Nicola

Madrid

Inhalt:

The nature of chiral symmetry restoration and the identification of its correct pattern in terms of $O(4)$ and $U(1)_A$ symmetries are central problems for our present understanding of the QCD phase diagram, currently explored in lattice simulations and heavy-ion collisions. We will present a theoretical analysis based on Ward Identities for the full scalar/pseudoscalar $U(3)$ meson nonets, which sheds light on these issues. Our results lead to interesting conclusions regarding the behaviour of chiral partners in the limit of exact restoration and provide useful relations for lattice analysis. In addition, partner degeneration is connected with physical interaction vertices and the temperature dependence of lattice screening masses is related to quark condensate combinations. We will also describe the realization of these ideas in meson theories. In particular, a $U(3)$ Chiral Perturbation Theory calculation supports the partner and pattern conclusions from WI. The role of the thermal $f_0(500)$ state, generated in unitarized pion scattering, to describe the scalar susceptibility will also be analyzed, as well as the information provided by the large number of Goldstone Bosons framework.

Ansprechpartner:

Ch. Schmidt

Seminar Kondensierte Materie

Thema:

Finite-temperature dynamics using matrix product states

Datum:

26.01.18

Uhrzeit:

14:15

Ort:

V2-205

Vortragender:

Salvatore Manmanna

Universität Göttingen

Inhalt:

Ansprechpartner:

Jürgen Schnack

Seminar Mathematische Physik

Thema:

Exploring the boundaries of universality for Gaussian perturbations of Hermitian matrices

Datum:

18.01.18

Uhrzeit:

16:00

Ort:

D5-153

Vortragender:

Thorsten Neuschel

University Catholique de Louvain

Inhalt:

We explore the boundaries of sine kernel universality for the eigen- values of Gaussian perturbations of large deterministic Hermitian ma- trices. Equivalently, we study for deterministic initial data the time after which Dyson's Brownian motion exhibits sine kernel correlations. We explicitly describe this time span in terms of the limiting density and rigidity of the initial points. This is joint work with Tom Claeys and Martin Venker.

Ansprechpartner:

Gernot Akemann

Seminar AG Zufallsmatrizen

Thema:

Local inhomogeneous circular law

Datum:

18.12.17

Uhrzeit:

14:15

Ort:

V3-201

Vortragender:

Johannes Alt

Institute of Science and Technology, Austria

Inhalt:

The density of eigenvalues of large random matrices typically converges to a deterministic limit as the dimension of the matrix tends to infinity. In the Hermitian case, the best known examples are the Wigner semicircle law for Wigner ensembles and the Marchenko-Pastur law for sample covariance matrices. In the non-Hermitian case, the most prominent result is Girko’s circular law: The eigenvalue distribution of a matrix X with centered, independent entries converges to a limiting density supported on a disk. Although inhomogeneous in general, the density is uniform for identical variances. In this special case, the local circular law by Bourgade et al. shows this convergence even locally on scales slightly above the typical eigenvalue spacing. In the general case, the density is obtained via solving a system of deterministic equations. In my talk, I explain how a detailed stability analysis of these equations yields the local inhomogeneous circular law in the bulk spectrum for a general variance profile of the entries of X. This result was obtained in joint work with László Erdos and Torben Krüger. 1

Ansprechpartner:

Friedrich Götze



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  • | Letzte Änderung: 23.11.2011
  •  Olaf Kaczmarek
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