# Aktuelle Veranstaltungen

## Kolloquium

Thema:

### Massen für Elementarteilchen und offene Fragen der Teilchenphysik - 10 Jahre Higgs-Entdeckung

Datum:

04.07.22

Uhrzeit:

16:15

Ort:

X-E0-001

Vortragender:

Dr. Bastian Brandt

Universität Bielefeld

Inhalt:

In diesem öffentlichen Vortrag werden anlässlich des 10-jährigen Jubiläums der experimentellen Entdeckung des Higgs-Teilchens die Grundzüge des Standardmodells der Teilchenphysik verständlich dargestellt. Im Anschluss werden offene Fragen der Teilchenphysik rund um den dritten Lauf des Large Hadron Colliders (LHC) am Europäischen Kernforschungszentrum CERN erläutert. Der Vortrag bildet gleichzeitig den Auftakt zu den Feierlichkeiten zum 50-jährigen Bestehen der Fakultät für Physik an der Universität Bielefeld vom 4. bis 9. Juli 2022.

Ansprechpartner:

D. Schwarz

## Kolloquium Mathematische Physik

Thema:

### Vertex Algebras for 2- and 4-Dimensional Conformal Field Theories

Datum:

01.07.22

Uhrzeit:

16:15

Ort:

D5-153

Vortragender:

Sven Möller

Universität Hamburg

Inhalt:

Vertex (operator) algebras axiomatise 2-dimensional conformal field theories in physics. They were introduced in the 1980s to explain mysterious connections between number and representation theory (monstrous moonshine). Not long ago, they were also shown to capture certain aspects of 4-dimensional superconformal field theories. In this talk I will describe recent classification results for holomorphic vertex algebras of central charge 24 by means of certain modular forms (vector-valued Eisenstein series). Moreover, I will sketch classification problems arising in the context of 4-dimensional field theories.

Ansprechpartner:

G. Akemann

## Seminar Hochenergiephysik

Thema:

### Medium-enhanced Production of C-cbar Pairs in Jets

Datum:

05.07.22

Uhrzeit:

14:15

Ort:

D6-135

Vortragender:

Jasmine Brewer

CERN

Inhalt:

The degrees of freedom of the high temperature phase of QCD matter produced in heavy-ion collisions can be studied through its interactions with high-energy partons that are also produced in these collisions. The medium broadens the momentum and degrades the energy of these partons, which is observed as a suppression of the yield of high-energy jets and hadrons in heavy-ion collisions compared to a proton-proton baseline. These interactions can be characterized by medium-modification of the QCD splitting functions. We study the modification of the g->c-cbar splitting function in the kinematic range accessible at the LHC. In addition to characterizing the momentum broadening of the c-cbar pair, we find that interactions with the medium also enhance the rate of c-cbar production. We also propose an experimental signature of this enhancement through the rate of jets containing two D0 mesons in heavy-ion collisions.

Ansprechpartner:

S. Schlichting

## Seminar Kondensierte Materie

Thema:

### Carbon materials and their theoretical modelling

Datum:

14.07.22

Uhrzeit:

14:15

Ort:

D5-153

Vortragender:

Nigel Marks

Curtin University, Perth

Inhalt:

Ansprechpartner:

Jürgen Schnack

## Seminar Mathematische Physik

Thema:

### Many-particles diffusing with resetting: study of the large-deviation properties of the flux distribution

Datum:

05.05.22

Uhrzeit:

16:00

Ort:

D5-153

Vortragender:

Costantino Di Bello

Inhalt:

In this paper we studied a model of noninteracting particles moving on a line following a common dynamics. In particular we considered either a diffusive motion with Poissonian resetting, and a run-and-tumble motion with Poissonian resetting. We were interested in studying the distribution of the random variable $Q_t$ defined as the flux of particles through origin up to time $t$. We used the notation $P(Q,t)$ to identify the probability $\mathbb{P}\{Q_t=Q\}$. We considered particles initially located on the negative half line with a fixed density $\rho$. In fully analogy with disordered systems, we studied both the annealed and the quenched case for initial conditions. In the former case we found that, independently from the specific dynamics, $P_\mathrm{an}(Q,t)$ has a Poissonian shape; while in the latter case, for what concerns the diffusive dynamics with resetting, the large deviation form of the quenched distribution reads $P_\mathrm{qu}(Q,t)\sim \exp\left[-r^2t^2 \Psi_\mathrm{diff}\left(\dfrac{Q}{\rho t}\right)\right]$ with the large deviation function $\Psi_\mathrm{diff}(x)$ exhibiting a discontinuity in the third derivative, hence aiming, despite the simplicity of the model, at the exhistence of a dynamical phase transition. The quenched distribution for the run-and-tumble dynamics, instead, does not exhibit any kind of phase transition. Importance sampling Monte Carlo simulations were performed to prove the analytical results. References: Current fluctuations in noninteracting run-and-tumble particles in one dimension Tirthankar Banerjee, Satya N. Majumdar, Alberto Rosso, and Grégory Schehr, Phys. Rev. E 101, 052101 https://doi.org/10.1103/PhysRevE.101.052101 Current Fluctuations in One Dimensional Diffusive Systems with a Step Initial Density Profile B. Derrida and A. Gerschenfeld, J. Stat. Phys. 137, 978 (2009) https://doi.org/10.1007/s10955-009-9830-1

Ansprechpartner:

Gernot Akemann

## Seminar AG Zufallsmatrizen

Thema:

### Determinants with Circular Root- and Jump-type Singularities

Datum:

06.07.22

Uhrzeit:

09:00

Ort:

ZOOM / Konferenzschaltung

Vortragender:

Christophe Charlier

Lund University

Inhalt:

Determinants with circular root- and jump-type singularities are of interest in the study of the eigenvalue moduli of random normal matrices. So far determinants with circular root-type singularities have been unexplored. In the first part of this talk, I will show that such singular determinants have a novel type of asymptotic behavior described in terms of the so-called associated Hermite polynomials. In the second part, I will focus on determinants with pure jump-type singularities, in the regime where they approach a hard edge. Such determinants give information about the disk counting statistics of coulomb gases near a hard edge and have been unexplored up to now. I will show that the counting statistics in the hard edge regime is considerably wilder than in all previously studied regimes. The first part of the talk is joint work with S.-S. Byun, and the second part is work in progress with Y. Ameur, J. Cronvall and J. Lenells.

Ansprechpartner:

Gernot Akemann

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