Weakly interacting Bose gases below the critical temperature

TL;DR

This paper develops a finite temperature field theory approach to analyze homogeneous non-ideal Bose gases below the critical temperature, introducing an algorithm that simplifies diagram calculations while ensuring physically consistent results.

Contribution

It presents a novel algorithm for simplifying diagram calculations in finite temperature field theory for Bose gases, coupled with a self-consistent condition for free energy minimization.

Findings

Provides a manageable diagram subset for calculations

Ensures physically reasonable results through self-consistency

Applicable to non-ideal Bose gases below T_C

Abstract

We consider a homogeneous non-ideal Bose gas at nonzero temperature in equilibrium below the critical temperature $T_C$ in the framework of finite temperature field theory. An algorithm is described in which a manageable subset of diagrams can be considered which, coupled with a self--consistent condition related to the minimization of the free energy, can be used to obtain physically reasonable results.