Transport properties and equation-of-state of hot and dense QGP matter near the critical end-point in the phenomenological dynamical quasi-particle model

Abstract

We extend the effective dynamical quasiparticle model (DQPM) - constructed for the description of non-perturbative QCD phenomena of the strongly interacting quark-gluon plasma (QGP) - to large baryon chemical potentials, $\mu_B$, including a critical end-point and a 1st order phase transition. The DQPM description of quarks and gluons is based on partonic propagators with complex selfenergies where the real part of the selfenergies is related to the quasiparticle mass and the imaginary part to a finite width of their spectral functions. In DQPM the determination of complex selfenergies for the partonic degrees of freedom at zero and finite $\mu_B$ has been performed by adjusting the entropy density to the lQCD data. The temperature-dependent effective coupling (squared) $g^2(T/T_c)$, as well as the parton effective masses and widths are based on this adjustment. The novel extended dynamical quasiparticle model, named "DQPM-CP", makes it possible to describe thermodynamical and transport properties of quarks and gluons in a wide range of $T$ and $\mu_B$, and reproduces the equation-of-state (EoS) of lQCD calculations in the crossover region of finite $T, \mu_B$. We apply a scaling ansatz for the strong coupling constant near the CEP, located at ($T^{CEP}$, $\mu^{CEP}_B) = (0.100, 0.960)$ GeV. We show the EoS as well as the speed of sound for $T>T_c$ and for a wide range of $\mu_B$, which can be of interest for hydrodynamical simulations. Furthermore, we consider two settings for the strange quark chemical potentials (I) $\mu_s=\mu_B/3$ and (II) $\mu_s=0$. The isentropic trajectories of the QGP matter are compared for these two cases. The phase diagram of DQPM-CP is close to PNJL calculations. The leading order pQCD transport coefficients of both approaches differ. This elucidates that the knowledge of the phase diagram alone is not sufficient to describe the dynamical evolution of QGP.