Nonequilibrium Renormalization Theory I

TL;DR

This paper addresses divergences in nonequilibrium diagram techniques within the Keldysh formalism, proposing a renormalization scheme and illustrating its implications for understanding thermalization in nonequilibrium systems.

Contribution

It introduces a renormalization scheme for divergences in nonequilibrium diagrams, linking divergence treatment to system thermalization behavior.

Findings

Divergences in nonequilibrium diagrams can be renormalized.

Renormalization affects the understanding of thermalization.

Boundary conditions influence system approach to equilibrium.

Abstract

In the present article we consider some general class of divergent diagrams in Keldysh diagram technique. These divergences arise for nonequilibrium matter and closely related to the divergences in the kinetic theory of gases. We suggest a scheme of renormalization of such divergences and illustrate it on some examples. In the other papers of these series we develop the general theory of renormalization of nonequilibrium diagram technique. The fact that thermal divergences in non-equilibrium diagram technique can be renormalized leads to the following consequence: to prove that the system tends to the thermal equilibrium one should to take into account the behaviour of the system on its boundary. In this paper we illustrate this fact on Bogoliubov derivation of kinetic equations.