Influence of core excitations on the deuteron stripping reaction with the method of many-body green functions

Abstract

Within the scope of many-body Green functions we derive a formally exact expression for the ( d,p)-stripping amplitude, which resembles the DWBA for this reaction. However, the distorted wavefunctions in the entrance and exit channel are defined with respect to the most general expressions for the optical potentials, as they are given by the mass operators of corresponding Dyson equations for correlation functions. In the same way the transition operator is a complicated many-body quantity which explicitly depends on the deuteron energy and contains for example contributions coming from the core excitations of the target nucleus. In this paper we are mainly interested in the latter effect and a numerical estimation of a crude model for the many-body effects of the transition operator reveals no pronounced (sharply resonant) energy dependence. The essential difference of our paper to other publications on the same subject is that we are dealing with the “Dyson equation” approach developed recently for higher Green functions.