Effect of momentum anisotropy on quark matter in the quark-meson model

TL;DR

This study explores how spheroidal momentum-space anisotropy influences the chiral phase structure, critical endpoint location, and thermodynamic properties of quark matter within the 2+1 flavor quark-meson model, revealing significant shifts and behaviors.

Contribution

It introduces the effect of spheroidal momentum anisotropy on the quark-meson model's phase diagram and thermodynamics, highlighting the sensitivity of the critical endpoint to anisotropy.

Findings

CEP shifts to lower temperatures with increasing anisotropy

Anisotropy hinders chiral symmetry restoration

Transport coefficients like shear viscosity decrease with anisotropy

Abstract

We investigate the chiral phase structure of quark matter with spheroidal momentum-space anisotropy specified by one anisotropy parameter $\xi$ in the 2+1 flavor quark-meson model. We find that the chiral phase diagram and the location of the critical endpoint (CEP) are affected significantly by the value of $\xi$. With the increase of $\xi$, the CEP is shifted to smaller temperatures and larger quark chemical potentials. And the temperature of the CEP is more sensitive to the anisotropy parameter than the corresponding quark chemical potential, which is opposite to the study for finite system volume effect. Furthermore, the effects of momentum anisotropy on the thermodynamic properties and scalar (pseudoscalar) meson masses are also studied at vanishing quark chemical potential. The numerical results show that an increase of $\xi$ can hinder the restoration of chiral symmetry. We also find that shear viscosity and electrical conductivity decrease as $\xi$ grows. However, bulk viscosity exhibits a significant non-trivial behavior with $\xi$ in the entire temperature domain of interest.