Factorization of soft and collinear divergences in non-equilibrium quantum field theory

Proof of factorization of soft and collinear divergences in non-equilibrium QCD may be necessary to study hadronic signatures of quark–gluon plasma at RHIC and LHC. In this paper we prove factorization of soft and collinear divergences in non-equilibrium QED by using Schwinger–Keldysh closed-time path integral formalism in the background field method in pure gauge.