ASYMMETRIC NUCLEAR-MATTER IN THE RELATIVISTIC BRUECKNER-HARTREE-FOCK APPROACH

We present a calculation of asymmetric nuclear matter properties at ze ro temperature in a relativistic Brueckner-Hartree-Fock framework. Fol lowing other calculations the components of the self-energies are extr acted by projecting on Lorentz-invariant amplitudes. It is shown that for asymmetric nuclear matter one needs a sixth invariant. We present a set of invariants which in the limit of symmetric nuclear matter red uces to the conventional set. We argue that the existence of such a pr operly behaving set is also crucial for the application of the project ion method in symmetric nuclear matter. Results for the equation of st ate and other observables are presented. Special attention is paid to an analysis in terms of mean-field effective coupling constants. Apart from the usual ones we also find significant strength in the isovecto r scalar channel, which can be interpreted as an effective delta meson .