BCS-BEC crossover in dense relativistic matter: Collective excitations

TL;DR

This paper explores the transition between BCS and BEC superfluid phases in dense relativistic matter using NJL models, analyzing collective excitations and Goldstone bosons to understand superfluid properties.

Contribution

It provides a mean-field analysis of collective bosonic excitations in relativistic superfluids, including spectral properties and Goldstone modes, within a systematic framework.

Findings

Spectral properties of collective excitations analyzed

Goldstone bosons characterized in superfluid phase

Illustrated on two-flavor quark matter

Abstract

We study the relativistic BCS-BEC crossover within a class of Nambu-Jona-Lasinio type models, including arbitrary Lorentz-scalar pairing channels. Using the mean-field approximation we investigate spectral properties of the collective bosonic excitations in the superfluid phase, with particular attention to the Nambu--Goldstone bosons of the broken symmetry. This is a first step towards a systematic improvement of the mean-field approximation by including the fluctuation effects. The general results are illustrated on pairing in dense two-flavor quark matter - the two-flavor color superconductor.