Quasi-particle model of QGP - a revisit

The quasi-particle model of quark gluon plasma (QGP) is revisited here with thermodynamically consistent formalism, different from earlier studies, without the need of temperature dependent bag constant as well as other effects such as confinement effects, effective degrees of freedom etc. Our model has only one system dependent parameter and surpraisingly good fit to lattice results for gluon plasma, 2-flavor and 3-flavor QGP are obtained. The basic idea is to evaluate energy density $\epsilon$ first from grand partition function of quasi-particle QGP and then derive all other thermodynamic functions from $\epsilon$. Quasi-particles are assumed to have temperature dependent mass equal to plasma frequency. Energy density, pressure and speed of sound are evaluated and compared with available lattice data. We further extend the model to finite chemical potential, without any new parameters, to obtain quark density, quark susceptibility etc. and fits very well with the lattice results on 2-flavor QGP.