# 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:

### Axion warm inflation and reheating

Datum:

30.06.22

Uhrzeit:

14:15

Ort:

D6-135

Vortragender:

Simona Procacci

Universität Bern

Inhalt:

After introducing a simple homogeneous and isotropic inflationary model, we add interactions via an axion-like decay to Yang-Mills gauge bosons. As these rapidly thermalize, the friction felt by the inflaton field is increased by non-Abelian “strong sphalerons”. The resulting self-amplifying process can efficiently heat up the system. Such a reheating period may produce gravitational waves via hydrodynamic fluctuations and particle collisions.

Ansprechpartner:

D. Bödeker

## Seminar Kondensierte Materie

Thema:

### Das Perzeptron: Grundbaustein neuronaler Netze und kuenstlicher Intelligenz

Datum:

30.06.22

Uhrzeit:

14:15

Ort:

D5-153

Vortragender:

Paul Angelike

Universität Bielefeld

Inhalt:

Ansprechpartner:

Peter Reimann

## 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 Bielefeld-Melbourne Zufallsmatrizen

Thema:

### Operator Delocalization in Quantum Networks

Datum:

29.06.22

Uhrzeit:

09:00

Ort:

ZOOM / Konferenzschaltung

Vortragender:

Dario Rosa

Daejeon and Stony Brook

Inhalt:

I will introduce the notion of operator delocalization, to be contrasted with the more conventional notion of operator growth. I will show that even free quantum mechanical systems, once defined on sufficiently connected networks, can exhibit non-trivial delocalization properties. Some preliminary results, based on a current work in progress, on the connection between operator delocalization and quantum many-body chaos will be discussed.

Ansprechpartner:

Gernot Akemann

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