Variational approximation for two-time correlation functions in $\Phi^4$ theory : optimization of the dynamics

TL;DR

This paper develops a variational approach to approximate two-time correlation functions in $\

Contribution

It introduces a novel parametrization within the variational framework to derive dynamical equations for correlation functions in $\

Findings

Derived coupled dynamical equations for correlation functions

Provided approximations for two, three, and four field operator correlations

Applied the method to $\

Abstract

We apply the time-dependent variational principle of Balian and V\'en\'eroni to the $ \Phi^4$ theory. An appropriate parametrization for the variational objects allows us to write coupled dynamical equations from which we derive approximations for the two-time correlation functions involving two, three or four field operators.