Quark condensate and chiral symmetry restoration in neutron stars

TL;DR

This paper models the behavior of quark condensates in neutron stars using an equivparticle approach, revealing partial chiral symmetry restoration at high densities within astrophysical constraints.

Contribution

It introduces a novel application of an equivparticle model to study in-medium quark condensates and chiral symmetry restoration in neutron star matter.

Findings

Quark condensate decreases non-linearly with density.

Chiral symmetry is only partially restored in neutron stars.

Complete restoration may occur at densities beyond neutron star limits.

Abstract

Based on an equivparticle model, we investigate the in-medium quark condensate in neutron stars. Carrying out a Taylor expansion of the nuclear binding energy to the order of $\rho^3$, we obtain a series of EOSs for neutron star matter, which are confronted with the latest nuclear and astrophysical constraints. The in-medium quark condensate is then extracted from the constrained properties of neutron star matter, which decreases non-linearly with density. However, the chiral symmetry is only partially restored with non-vanishing quark condensates, which may vanish at a density that is out of reach for neutron stars.