Microscopic analysis of two-body correlations in light nuclei

Abstract

Within a nonperturbative dynamical two-body approach — based on coupled equations of motion for the one-body density matrix and the two-body correlation function — we study the distribution of occupation numbers in a correlated system close to the groundstate, the relaxation of singleparticle excitations and the damping of collective modes. For this purpose the nonlinear equations of motion are solved numerically within a finite oscillator basis for the first time adopting shortrange repulsive and long-range attractive two-body forces. We find in all cases that the formation of long- and short-range correlations and their mixing is related to the long- and short-range part of the nucleon-nucleon interaction which dominate the resummation of loop or ladder diagrams, respectively. However, the proper description of relaxation or damping phenomena is found to require both types of diagrams as well as the mixed terms simultaneously.