Description of heavy ion collisions with medium dependent forces

One of the proclaimed goals of heavy ion collisions with 100 MeV up to 2000 MeV per nucleon is the determination of the equation of state of nuclear matter, needed to describe for example, neutron stars, supernova explosions and the early universe. But the situation in heavy ion collisions is quite different from thermal equilibrium with a spherical momentum distribution and a fixed temperature. The effective nucleon-nucleon interaction as determined for example, by the solution of the Bethe-Goldstone equation depends on the Pauli operator and the single particle energies in the surrounding nuclear matter. This dependence is especially pronounced since the nucleon-nucleon interaction is highly momentum dependent. It is attractive at small relative momenta and repulsive at higher values. Thus the effective nucleon-nucleon interaction in heavy ion collisions depends on the distribution of the surrounding nuclear matter in orbital and momentum space. Here results are presented using Quantum Molecular Dynamics (QMD) for the description of heavy ion reactions at intermediate energies in a non-relativistic and in a completely covariant (RQMD) form. We show that the production of gamma-rays, pions and the inclusive spectra of nucleons and light nuclei are not sensitive to the equation of states. (author)