Speaker
Chun Shen
(The Ohio State University)
Description
Predictions and postdictions from viscous hydrodynamics for the transverse momentum spectra and differential elliptic flow for unidentified and identified charged hadrons from Pb+Pb collisions at LHC energies, including their centrality dependence, will be presented. These predictions are based on a global viscous hydrodynamic fit of soft hadron spectra and their anisotropies measured in Au+Au collisions at RHIC, using a state-of-the-art equation of state, which accurately reproduces the observed charged hadron, pion and proton spectra and their differential v_2(p_T) for all collision centralities in the range p_T<2 GeV. Assuming the same specific effective shear viscosity eta/s=0.20 for KLN initial conditions at RHIC and LHC, we obtain a good description of the soft charged hadron spectra in central Pb+Pb collisions at sqrt{s}=2.76 A TeV, but slightly overpredict the integrated charged hadron elliptic flow in measured by the ALICE Collaboration in non-central Pb+Pb collisions. We explore whether and how this can be remedied by allowing for a temperature dependent change of the specific shear viscosity eta/s of the quark-gluon plasma in the newly explored higher temperature region probed at the LHC. In doing so, we expose a need for a more quantitative understanding of the early pre-equilibrium stage. Future comparisons of spectra and elliptic flow for identified hadrons at both sqrt{s}=2.76 and 5.5 A TeV with predictions presented in this talk will allow to further test the validity of the viscous hydrodynamic model and will shed additional light on possible variations of the quark-gluon transport coefficients between RHIC and LHC energies.
Primary author
Chun Shen
(The Ohio State University)
Co-author
Prof.
Ulrich Heinz
(The Ohio State University)
