Hydrodynamics at large baryon densities: Understanding proton vs.   anti-proton v_2 and other puzzles
  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. 
J. Steinheimer, V. Koch and M. Bleicher
nucl-th hep-ph