Heavy Ion Collisions and the Density Dependence of the Local Mean Field

We study the effect of the density dependence of the scalar and the vector part of the nucleonic self-energy in Relativistic Quantum Molecular Dynamics (RQMD) on observables like the transversal flow and the rapidity distribution. The stability of nuclei in RQMD is greatly improved if the density dependence is included in the self-energies compared to a calculation assuming always saturation density of nuclear matter. Different approaches are studied: The main results are calculated with self-energies extracted from a Dirac-Br\"uckner-Hartree-Fock G-matrix of a one boson exchange model, i.e. the Bonn potential. These results are compared with those obtained by a generalization of static Skyrme force, with calculations in the simple linear Walecka model and results of the Br\"uckner-Hartree-Fock G-matrix of the Reid soft core potential. The transversal flow is very sensitive to these different approaches. A comparison with the data is given.