Thermal Properties of Asymmetric Nuclear Matter

The thermal properties of asymmetric nuclear matter are investigated in a relativistic mean- field approach. We start from free space NN-interactions and derive in-medium self-energies by Dirac-Brueckner theory. By the DDRH procedure we derive in a self-consistent approach density- dependent meson-baryon vertices. At the mean-field level, we include isoscalar and isovector scalar and vector interactions. The nuclear equation of state is investigated for a large range of total baryon densities up to the neutron star regime, the full range of asymmetries from symmetric nuclear matter to pure neutron matter, and temperatures up to T~100 MeV. The isovector-scalar self-energies are found to modify strongly the thermal properties of asymmetric nuclear matter. A striking result is the change of phase transitions when isovector-scalar self-energies are included.