Heavy ion collisions and non-equilibrium mean fields

Methods and difficulties of the determination of the equation-of-state of nuclear matter by means of relativistic heavy ion collisions are reviewed. The description of nuclear structure in the framework of a hadronic field theory is discussed and it is argued that the Dirac-Brueckner approach represents a framework that allows to unify the description of NN-scattering, nuclear matter and finite nuclei, and heavy ion reactions. In the latter case, however, non-equilibrium features of the phase space distribution have to be taken into account to reliably extract the equation-of-state. This is done here in a local phase space configuration approximation. An examplary application to flow observables in relativistic Aut-Au collisions is presented. It is seen that the microscopic Dirac Brueckner fields reproduce experimental data reasonably well if non-equlibrium effects are accounted for approximately.