From Kadanoff-Baym dynamics to off-shell parton transport

TL;DR

This paper reviews the derivation of off-shell quantum transport equations from quantum field theory, demonstrating their application to non-equilibrium systems like heavy-ion collisions and dilepton production.

Contribution

It presents a comprehensive derivation of off-shell transport theory from Kadanoff-Baym equations, including solution methods and practical applications in heavy-ion physics.

Findings

Transport equations can be solved using test-particle methods.

Application to dilepton production matches experimental data.

Addresses partonic to hadronic transition in heavy-ion collisions.

Abstract

This review provides a written version of the lectures presented at the Schladming Winter School 2008, Austria, on 'Nonequilibrium Aspects of Quantum Field Theory'. In particular, it shows the way from quantum-field theory - in two-particle irreducible approximation - to the Kadanoff-Baym (KB) equations and various approximations schemes of the KB equations in phase space. This ultimately leads to the formulation of an off-shell transport theory that well incorporates the underlying quantum physics. Remarkably, these transport equations may be solved within a testparticle representation that allows to study non-equilibrium quantum systems in the weak and strong coupling regime. Actual applications to dilepton production in heavy-ion reactions are presented in comparison with available data. The approach, furthermore, allows to address the hadronization process from partonic to hadronic degrees of freedom.