Hydrodynamics at large baryon densities: Understanding proton vs. anti-proton v_2 and other puzzles

Abstract

We study the importance of the initial state, baryon stopping and baryon number transport for the dynamical evolution of a strongly interacting system produced in heavy ion collisions. We employ a hybrid model, which combines the fluid dynamical evolution of the fireball with a transport treatment for the initial state and the final hadronic phase. We present results for collisions at beam energies from sqrt{s_{NN}}=7.7 to 200 GeV. We study various observables such as the centrality dependent freeze out parameters, the non-monotonic behavior of effective slope parameter parameter with particle mass as well as the apparent difference in particle and anti-particle elliptic flow. Our results are in reasonable agreement with the available data. We find that the propagation of the baryon-number current in the hydrodynamic evolution as well as the transport treatment of the hadronic phase are essential for reproducing the experimental data.