BCS pairing in Fermi systems with several flavors

TL;DR

This paper explores the superfluid phase of a three-flavor fermionic system with attractive interactions, identifying multiple pairing modes and their signatures in the density response, relevant for cold atom experiments.

Contribution

It analyzes collective pairing modes and their damping in a three-flavor Fermi system, revealing robustness of these features against symmetry-breaking perturbations.

Findings

Multiple low-lying collective pairing modes identified

Signatures of gapless third flavor in density response

Robustness of pairing modes against SU(3) symmetry breaking

Abstract

Motivated by the prospect of Bardeen-Cooper-Schrieffer (BCS) pairing in cold fermionic gases we analyze the superfluid phase of 3 fermionic flavors in the attractive Hubbard model. We show that there are several low--lying collective pairing modes and investigate their damping due to the partially gapless nature of the single-particle spectrum. Furthermore we analyze how these modes show up in the density response of the system. Apart from the Anderson-Bogoliubov phase mode of the pairing between two flavors, the dynamical structure factor contains signatures of the gapless third flavor. This picture is found to be robust against perturbations that break the global SU(3)-symmetry of the Hamiltonian.