Exploring the partonic phase at finite chemical potential in and out-of equilibrium

Abstract

We study the influence of the baryon chemical potential μB on the properties of the Quark–Gluon–Plasma (QGP) in and out-of equilibrium. The description of the QGP in equilibrium is based on the effective propagators and couplings from the Dynamical QuasiParticle Model (DQPM) that is matched to reproduce the equation-of-state of the partonic system above the deconfinement temperature Tc from lattice Quantum Chromodynamics (QCD). We calculate the transport coefficients such as the ratio of shear viscosity ɳ and bulk viscosity ¶ over entropy density s, i.e., η/s and ¶/s in the (T, μB ) plane and compare to other model results available at μB = 0. The out-of equilibrium study of the QGP is performed within the Parton–Hadron–String Dynamics (PHSD) transport approach extended in the partonic sector by explicitly calculating the total and differential partonic scattering cross sections (based on the DQPM propagators and couplings) evaluated at the actual temperature T and baryon chemical potential μB in each individual space-time cell of the partonic scattering. The traces of their μB dependences are investigated in different observables for relativistic heavy-ion collisions with a focus on the directed and elliptic flow coefficients in the energy range 7.7 GeV ≤ .