Effective field theory approach to Bose--Einstein condensation

TL;DR

This paper develops a general effective field theory framework to analyze low-energy excitations in Bose--Einstein condensates at finite temperature, providing a model-independent approach to predict excitation damping.

Contribution

It introduces a universal effective Lagrangian based on symmetry breaking to describe collective excitations in Bose--Einstein condensates at finite temperature.

Findings

Derived momentum and temperature dependence of excitation damping

Provided a model-independent theoretical framework

Demonstrated the use of power counting in predictions

Abstract

We consider the low-energy collective excitations at finite temperature of Bose--Einstein condensed gases (and liquids as well). A most general model-independent effective Lagrangian is written down according to a prescription obtained from the breakdown of the global symmetry U(1). To show how the theory predicts easily, we derive the momentum and temperature dependence of the damping of excitations by means of power counting as an example.