Based on the method proposed by Zong et al.,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 when μ is less than 4.7 GeV,the pressure density calculated using HDL approximation is much larger than that calculated using pertur-bation theory.This enhancement of the obtained pressure density with respect to that of perturbation theory can be regarded as a possible explanation for the strong coupled QGP.It is also expected that the obtained EOS can be applied in the study of neutron stars.
In this paper we calculate the equation of state （EOS） of QCD at zero temperature and finite chemical potential by using several models of quark propagators including the Dyson-Schwinger equations （DSEs） model,the hard-dense-loop （HDL） approximation and the quasi-particle model.The results are analyzed and compared with the known results in the literature.
