On the quantum-field description of many-particle Bose systems with spontaneously broken symmetry

TL;DR

This paper develops a quantum-field theoretical framework for analyzing many-particle Bose systems at finite temperatures with spontaneously broken symmetry, introducing a self-consistent model, perturbation theory, and Green's function techniques.

Contribution

It presents a novel quantum-field approach with a generalized self-consistent model and diagrammatic perturbation theory for inhomogeneous Bose systems with broken symmetry.

Findings

Formulated Dyson's equations for eigenenergy and vertex functions.

Constructed a diagram technique for temperature Green's functions.

Developed a perturbation theory for Bose systems with broken symmetry.

Abstract

A quantum-field approach to studying the Bose systems at finite temperatures and in states with spontaneously broken symmetry, in particular in a superfluid state, is proposed. A generalized model of a self-consistent field (SCF) for spatially inhomogeneous many-particle Bose systems is used as the initial approximation. A perturbation theory has been developed, and a diagram technique for temperature Green's functions (GFs) has been constructed. The Dyson's equations joining the eigenenergy and vertex functions have been deduced.