Pseudoscalar Goldstone bosons in the color-flavor locked phase at moderate densities

TL;DR

This paper investigates the properties of pseudoscalar Goldstone bosons in the color-flavor locked phase at moderate densities using a Nambu--Jona-Lasinio model, focusing on decay constants, masses, and kaon condensation.

Contribution

It explicitly constructs Goldstone bosons by solving the Bethe-Salpeter equation and compares results with low-energy effective field theory predictions at moderate densities.

Findings

Calculated decay constants in the chiral limit.

Determined masses of flavored Goldstone bosons with non-zero quark masses.

Analyzed conditions for kaon condensation.

Abstract

The properties of the pseudoscalar Goldstone bosons in the color-flavor locked phase at moderate densities are studied within a model of the Nambu--Jona-Lasinio type. The Goldstone bosons are constructed explicitly by solving the Bethe-Salpeter equation for quark-quark scattering in random phase approximation. Main focus of our investigations are (i) the weak decay constant in the chiral limit, (ii) the masses of the flavored (pseudo-) Goldstone bosons for non-zero but equal quark masses, (iii) their masses and effective chemical potentials for non-equal quark masses, and (iv) the onset of kaon condensation. We compare our results with the predictions of the low-energy effective field theory. The deviations from results obtained in the weak-coupling limit are discussed in detail.