Speaker: Thomas Buervenich (T-16, LANL)

Relativistic point-coupling models for the nuclear ground state: Status and Perspectives

Our ability to understand the structure of the nuclear ground state is strongly connected to formulating nuclear models that deliver a quantitative description of all measured ground-state observables. Then, present (and future) experimental data on nuclear ground states can be given a more solid physical interpretation. Observables related to the mass, densities and geometries of the nucleus as well as specific nuclear level data can be calculated with microscopic mean-field models. Selfconsistent mean-field models do this also, but are designed to allow a description of medium-light (A>16), medium and heavy nuclei with effective interactions that are adjusted to observables of spherical nuclei across that range. They can be used to extrapolate to the borders of the periodic system. We present recent results for the calculation of nuclear ground-state properties using relativistic mean-field theory with contact interactions (point couplings). We discuss strengths and short-comings of this approach as well as other unresolved issues. We test extensions to our most successful Lagrangian presently consisting of 4-, 6- and 8-fermion terms together with derivative terms. Mixed terms (with and without isovector dependence) have been considered. Because the measured ground-state observables appear to determine well only a few coupling constants, we must ask how well the new coupling constants have been determined. Then, the new models and sets of coupling constants are tested with respect to predictive power. Furthermore, we investigate the linkage of relativistic mean-field models and low-momentum QCD with the help of naive dimensional analysis (QCD scaling and chiral symmetry).