# The phases of nuclear matter

## Dénes Sexty

The primary research area in my research group is the investigation of Quantum Field Theories, such as Quantum Chromodynamics, the theory of quarks and gluons. Although the theory is well defined, in certain circumstances it is very hard to calculate predicitions of the theory without makeing certain hard to control approximations. Such a circumstance is for exmaple the thermodynamics of QCD for non-zero baryon density which is needed to describe the core of neutron stars. The understanding of QCD matter in such state is needed to describe the structure neutron stars (for example through the mass-radius relation), and also to understand gravitational wave signals from collisions of neutron stars. A similar hard to access area is non-equilibrium Quantum-Field theory, which is needed to understand e.g. the time evolution in the first few fm/c of heavy-ion collisions, describing how the hot QCD matter equilibrates, tunneling events in the early universe seeding phase transitions, etc. In my research group we search for potential solutions to these hard problems (often through simplified models) with innovative solution methods such as the Complex Langevin method, as well as carry out various studies of QFTs though the use of lattice discretised versions of the theory in question, with the help of computers.

### Specific research topics

- lattice QCD thermodynamics
- QCD at nonzero chemical potential, phase diagram of QCD
- Sign problem, solution via Complex Langevin, complexified integration manifolds
- Real-time evolution in Quantum Field Theories
- using machine learning to optimize Complex Langevin eq.
- Monte Carlo simulations
- MC using Density of States, parallel tempering, etc.

If you are interested in bachelor, master or PhD theses, contact me via email or in my office in the Institute of Physics.

### Teaching

**Summer Term 2023**

Übungen zu Mathematische Metoden 2

**Winter Term 2022/23**

Numerical Methods in Linear Algebra

**Summer Term 2022**

Gewöhnliche und partielle Differentialgleichungen

Übungen zu Gewöhnliche und partielle Differentialgleichungen

Fortgeschrittene Programmierung in der Physik

**Winter Term 2021/22**

** **Monte Carlo Methods

Numerical Methods in Linear Algebra

**Lecture Notes**

### Publications

Have a look on the following research indexing sites, or on the Forschungsportal of Uni Graz:

### Talks

**Selected Talks from conferences, Workshops, Schools**

Talk at XQCD 2022, Trondheim, Norway

Lectures on "Nonzero density on the lattice" DK-PI Retreat of TU Wien, 2022 Graz

Talk on Topology and axions on ACHT2021

Talk on SIGN 2018, Bielefeld, Germany

Talk on Lattice 2014, New York, USA

Lectures on Non-equilibrium lattice field theory, Schladming 2013

Talk on Thermalization of Non-Abelian Plasmas, Heidelberg, Germany, 2011

## Team

### Dénes Sexty

Phone:+43 316 380 - 5236

Location:Institut für Physik, Universitätsplatz 5, 8010 Graz

1. Stock, Raum 0032