Neutron stars with parametrized meson couplings

We investigate static properties of nuclear and neutron star matter by usin g a relativistic mean field theory with parametrized couplings. With a suit able choice of mathematical parameters, the couplings allow one to reproduc e results of current quantum hadrodynamics models. For other parametrizatio ns, a better description of bulk properties of nuclear matter is obtained. The formalism is extended to include hyperon and lepton degrees of freedom, and an analysis on the effects of the phenomenological couplings in the fe rmion populations and mass of neutron stars is performed. The results show a strong similarity between the predictions of ZM-like models and those wit h exponential couplings. We have observed in particular an extreme sensibil ity of the predictions of these theories on the specific choice of the valu es of the binding energy of nuclear matter and saturation density. Addition ally, the role of the very intense scalar meson mean field found in the int erior of neutron stars in the screening of the nucleon mass is discussed.