Out of Equilibrium Quantum Field Theory --- Perturbation Theory and Generalized Boltzmann Equation

TL;DR

This paper develops a perturbative framework using the closed-time-path formalism to derive generalized Boltzmann equations for relativistic quantum field systems near equilibrium and in nonequilibrium quasistationary states.

Contribution

It introduces two equivalent calculational schemes based on different particle distribution functions, leading to a generalized kinetic equation for quantum field systems.

Findings

Derivation of a generalized Boltzmann equation from quantum field theory.

Two calculational schemes are shown to be equivalent.

Provides a concrete procedure for computing amplitudes in this framework.

Abstract

This paper describes perturbative framework, on the basis of the closed-time-path formalism, in terms of quasiparticle picture for studying quasiuniform relativistic quantum field systems near equilibrium and nonequilibrium quasistationary systems. Two calculational schemes are introduced, the one is formulated on the basis of the initial-particle distribution function and the one is formulated on the basis of the ``physical''-particle distribution function. It is shown that both schemes are equivalent and lead to a generalized kinetic or Boltzmann equation. Concrete procedure of computing a generic amplitude is presented.