Relation between many-body and single-particle aspects in nuclei

Abstract

The process by which certain types of collective excitations in nuclei are built up from single-particle excitations through the nucleon-nucleon interaction is described. Analogies in the methods used to those employed in describing other Fermi systems are shown. Among the types of collective excitations are the dipole state and vibrational motion. A schematic model formulated in the language of the many-body theory and designed to handle the main qualitative features of a finite system is described. It was found that taking ground-state correlations meant doubling the order of the matrix in shell- model calculations. The ground-state correlations enhanced the transition probability for vibrational states where E << epsilon and cut it dow. for plasma oscillations. (M.C.G.)