Single electrons from heavy-flavor mesons in relativistic heavy-ion collisions
AbstractWe study the single electron spectra from D- and B-meson semileptonic decays in Au+Au collisions at sNN=200, 62.4, and 19.2 GeV by employing the parton-hadron-string dynamics (PHSD) transport approach that has been shown to reasonably describe the charm dynamics at Relativistic Heavy Ion Collider and Large Hadron Collider energies on a microscopic level. In this approach the initial charm and bottom quarks are produced by using the PYTHIA event generator which is tuned to reproduce the fixed-order next-to-leading logarithm calculations for charm and bottom production. The produced charm and bottom quarks interact with off-shell (massive) partons in the quark-gluon plasma with scattering cross sections which are calculated in the dynamical quasiparticle model that is matched to reproduce the equation of state of the partonic system above the deconfinement temperature Tc. At energy densities close to the critical energy density (≈0.5GeV/fm3) the charm and bottom quarks are hadronized into D and B mesons through either coalescence or fragmentation. After hadronization the D and B mesons interact with the light hadrons by employing the scattering cross sections from an effective Lagrangian. The final D and B mesons then produce single electrons through semileptonic decay. We find that the PHSD approach well describes the nuclear modification factor RAA and elliptic flow v2 of single electrons in d+Au and Au+Au collisions at sNN=200GeV and the elliptic flow in Au+Au reactions at sNN=62.4GeV from the PHENIX Collaboration, however, the large RAA at sNN=62.4GeV is not described at all. Furthermore, we make predictions for the RAA of D mesons and of single electrons at the lower energy of sNN=19.2GeV. Additionally, the medium modification of the azimuthal angle ϕ between a heavy quark and a heavy antiquark is studied. We find that the transverse flow enhances the azimuthal angular distributions close to ϕ=0 because the heavy flavors strongly interact with nuclear medium in relativistic heavy-ion collisions and almost flow with the bulk matter.