Exact CTP Renormalization Group Equation for the Coarse Grained Effective Action

TL;DR

This paper derives an exact renormalization group equation for the coarse grained CTP effective action in scalar field theory, enabling analysis of non-equilibrium phase transitions.

Contribution

It introduces a novel exact CTP renormalization group equation and applies it to scalar field theory, advancing non-equilibrium quantum field analysis.

Findings

Derived an exact CTP RG equation for scalar fields

Applied the equation to λφ^4 theory

Discussed implications for non-equilibrium phase transitions

Abstract

We consider a scalar field theory in Minkowski spacetime and define a coarse grained Closed Time Path (CTP) effective action by integrating quantum fluctuations of wavelengths shorter than a critical value. We derive an exact CTP renormalization group equation and solve it using a derivative expansion approach. Explicit calculation is performed for the $\lambda \phi^4$ theory. We discuss the relevance of the CTP average action in the study of non-equilibrium aspects of phase transitions in quantum field theory.