The Equation of State and Quark Number Susceptibility in Hard-Dense-Loop Approximation

TL;DR

This paper calculates the QCD equation of state and quark number susceptibility at finite density and temperature using HDL/HTL approximations, comparing results with perturbative and previous studies to understand dense quark matter properties.

Contribution

It introduces a calculation of the QCD EOS and QNS using HDL/HTL approximations, providing new insights into dense quark matter at zero temperature and finite chemical potential.

Findings

Pressure under HDL is smaller than perturbative results.

QNS results are consistent with previous literature.

Comparison highlights differences between HDL and perturbative approaches.

Abstract

Based on the method proposed in [ H. S. Zong, W. M. Sun, Phys. Rev. \textbf{D 78}, 054001 (2008)], we calculate the equation of state (EOS) of QCD at zero temperature and finite quark chemical potential under the hard-dense-loop (HDL) approximation. A comparison between the EOS under HDL approximation and the cold, perturbative EOS of QCD proposed by Fraga, Pisarski and Schaffner-Bielich is made. It is found that the pressure under HDL approximation is generally smaller than the perturbative result. In addition, we also calculate the quark number susceptibility (QNS) at finite temperature and finite chemical potential under hard-thermal/dense-loop (HTL/HDL) approximation and compare our results with the corresponding ones in the previous literature.