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HK: Fachverband Hadronen und Kerne
HK 55: Heavy Ion Collisions and QCD phases
HK 55.7: Talk
Wednesday, March 18, 2009, 18:30–18:45, H-ZO 10
A transport calculation with an embedded (3+1)d hydrodynamic evolution: Elliptic flow results from Elab=2−160A GeV — •Hannah Petersen1,2, Jan Steinheimer2, Marlene Nahrgang2, Gerhard Burau2, and Marcus Bleicher2 — 1Frankfurt Institute for Advanced Studies, Frankfurt, Germany — 2Institut for Theoretical Physics, Frankfurt University, Frankfurt, Germany
The elliptic flow excitation function calculated in a full (3+1)d Boltzmann approach with an intermediate hydrodynamic stage for heavy ion reactions from GSI-SIS to the highest CERN-SPS energies is discussed in the context of the experimental data. Within this integrated dynamical approach different equations of state are explored without adjusting parameters. At higher SPS energies, where the pure transport calculation cannot account for the high elliptic flow values, the smaller mean free path in the hydrodynamic evolution leads to higher elliptic flow values. Event-by-event fluctuations are directly taken into account via event wise non-equilibrium initial conditions generated by the primary collisions and string fragmentations in the microscopic UrQMD model. Due to the more realistic initial conditions and the incorporated hadronic rescattering the results are in line with the experimental data almost over the whole energy range from Elab=2−160A GeV. This newly developed approach leads to a substantially different shape of the v2/є scaling curve as a function of (1/S dNch/dy) which is now in line with the experimental data compared to previous ideal hydrodynamic calculations. We also present predictions for the differential flow measurements in the RHIC low energy run.