Parton–Hadron-String Dynamics at relativistic collider energies

The novel Parton–Hadron-String Dynamics (PHSD) transport approach is applied to nucleus–nucleus collisions at RHIC energies with respect to differential hadronic spectra in comparison to available data. The PHSD approach is based on a dynamical quasiparticle model for partons (DQPM) matched to reproduce recent lattice-QCD results from the Wuppertal–Budapest group in thermodynamic equilibrium. The transition from partonic to hadronic degrees of freedom is described by covariant transition rates for the fusion of quark–antiquark pairs or three quarks (antiquarks), respectively, obeying flavor current-conservation, color neutrality as well as energy–momentum conservation. Our dynamical studies for heavy-ion collisions at relativistic collider energies are compared to earlier results from the Hadron-String Dynamics (HSD) approach – incorporating no explicit dynamical partonic phase – as well as to experimental data from the STAR, PHENIX, BRAHMS and PHOBOS Collaborations for Au + Au collisions at the top RHIC energy of image. We find a reasonable reproduction of hadron rapidity distributions and transverse mass spectra and also a fair description of the elliptic flow of charged hadrons as a function of the centrality of the reaction and the transverse momentum image. Furthermore, an approximate quark-number scaling of the elliptic flow image of hadrons is observed in the PHSD results, too.