Brueckner—Hartree—Fock Methods for Nuclear Matter and Finite Nuclei

Abstract

In the present chapter we consider some methods developed during recent years for considering correlations in the relativistic description of the properties of nuclear matter and finite nuclei. First of all, we define more precisely what is meant by correlations. At the present stage, a detailed investigation has been carried out of interactions of free nucleons, both in the case of nucleon-nucleon scattering and in the case of the description of the properties of the deutron in the relativistic framework on the basis of meson exchange. Quite reasonable agreement with experiment has been obtained [34, 40, 50, 78, 275] in such a framework. The main product of this investigation is the one-boson exchange potentials, embodied in a specific meson exchange model. The next natural step is to describe, on the same footing, complicated systems containing more than two nucleons. The simplest tool to handle the problem in this case is the concept of the mean field generated by the nucleon-nucleon potential. Such a philosophy is a copy of the Hartree and Hartree -Fock methods successfully applied to problems related to the electronic shells in atoms. Although, as was shown in the previous chapters, a quantitative description of nuclear bulk properties has been achieved in the framework of the mean-field approximation, in general this method cannot he considered as a final stage of the investigation of nuclear systems. The commonly accepted reason for the deficiencies of this method is the important modification of the nucleon -nucleon interaction in the nuclear medium in comparison with the interaction of free nucleons. It is conventional to treat the effects generating these modifications as correlations [30, 385].