Relativistic Mean Field Models and Nucleon-Nucleon Interactions

We investigate the connection between relativistic mean field models and the barenucleon-nucleon interaction by using a realistic interaction in the nuclear medium. Start-ing from a nonrelativistic bare potential and by employing a G-matrix formalism we derivean effective interaction in the nuclear medium that depends on its density. We show thatits medium- and long-range components canbe described to a good extent by an effectivedensity-dependent one-boson-exchange (OBE) potential. For a good fit of the OBE to theG-matrix potential the following degrees of freedom have been found to be necessary: anisoscalar scalarS(σ-meson), an isoscalar vectorV(ω-meson), an isovector scalarTS(δ-meson), an isovector vectorTV(ρ-meson), and an isovector pseudoscalarPS(π-meson)Yukawa field. This allows us to extract the mass and the coupling strength of the variousmesons at different densities of nuclear matter. In such a way, we investigate the density-dependence of these parameters and the influence of many-body and multi-scattering effects.We find that with increasing density of the nuclear mediummσis constant to a good ap-proximation,mδdecreases quite strongly, whilemωandmρdecrease rather weakly. Thecoupling strengths of the fields also show a rather weak decreasing tendency. Furthermoreit turns out that the extracted values of the meson fields masses and couplings are ratherconsistent with the parameters of effective mesons of recent RMF phenomenologies. Finally,we find that the tensor force of the bare nucleon-nucleon interaction is essential to explainthe dominance of theσ-fistatus: publishe