Low-energy excitations and occupation probabilities

Abstract

The self-energy of nucleons in finite nuclei is evaluated including 2-particle-1-hole and 2-hole-1-particle terms, with and without taking into account the residual interaction between these configurations. The single-particle Green function is determined by solving the Dyson equation for this self-energy. This yields a fragmentation of the single-particle strength and a broad energy distribution for the spectral function of deep-lying hole states. A method is presented, which describes this spreading accurately in terms of a few discrete states. The relation between the Green function approach and the shell-model is discussed. The scheme is applied to the case of the nucleus 16O, using a realistic nucleon-nucleon interaction. The effects of the correlations on the occupation probabilities and the binding energy is evaluated.