Ultra-hot quantum field theories

Research project P 14632 Ultra-hot quantum field theories Anton REBHAN 09.10.2000 Quantum field theories at ultrarelativistic temperatures and densities provide the theoretical framework for describing the physics of matter under extreme conditions as they have existed in the very early universe, still exist in extreme astrophysical situations such as the interior of neutron stars, and are being produced in ultrarelativistic heavy ion collisions. The latter are presently at the verge of demonstrating compellingly the existence of a new phase of hadronic matter, the so-called quark-gluon plasma. Conventional resummation techniques of thermal perturbation theory, which constitute the most important tool for analytical investigations, have been found to have unexpectedly bad convergence properties. More complete resummation techniques which rely on a complete treatment of quasiparticle properties have recently been shown to be able to improve this situation greatly. The aim of this project is a) to develop these new techniques further; b) to use them for a quantitative determination of the thermodynamic potential of ultrahot and dense gauge theories in general and of the quark-gluon plasma in particular; and c) to extend these techniques to also cover dynamical quantities such as transport coefficients and production rates.

Quantum field theories at ultrarelativistic temperatures and densities provide the theoretical framework for describing the physics of matter under extreme conditions as they have existed in the very early universe, still exist in extreme astrophysical situations such as the interior of neutron stars, and are being produced in ultrarelativistic heavy ion collisions. The latter are presently at the verge of demonstrating compellingly the existence of a new phase of hadronic matter, the so-called quark-gluon plasma. Conventional resummation techniques of thermal perturbation theory, which constitute the most important tool for analytical investigations, have been found to have unexpectedly bad convergence properties. More complete resummation techniques which rely on a complete treatment of quasiparticle properties have recently been shown to be able to improve this situation greatly. The aim of this project is a) to develop these new techniques further; b) to use them for a quantitative determination of the thermodynamic potential of ultrahot and dense gauge theories in general and of the quark-gluon plasma in particular; and c) to extend these techniques to also cover dynamical quantities such as transport coefficients and production rates.