The equation of state and quark number susceptibility in the hard-dense-loop approximation

Abstract

Based on the method proposed by H S Zong and W M Sun (2008 Phys. Rev. D 78 054001), we calculate the equation of state (EOS) of quantum chromodynamics (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 the 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 the hard-thermal/dense-loop (HTL/HDL) approximation and compare our results with the corresponding ones in the previous literature.