Role of the tensor exchange potential in nucleon-nucleus scattering

Abstract

We give a microscopic derivation of the spin-spin components of the optical potential for elastic scattering of a nucleon from a target with nonzero spin. A realistic nucleon-nucleon interaction containing direct and exchange terms is used to generate a folded nucleon-nucleus potential whose spin-spin components are treated in distorted-wave Born approximation. We show how folding leads to spin-spin tensor interactions with higher order couplings in the projectile and target spin that have not been explicitly considered before. We place particular emphasis on the polarization transfer coefficient DNN for 200-MeV protons elastically scattered from 10B, which is rigorously unity in the absence of any spin-spin interactions and for which experimental data exist. We find that deviations of DNN from unity are particularly sensitive to spin-spin exchange terms arising from the nucleon-nucleon tensor interaction and the nuclear wave functions describing the target one-body density matrix. Unpolarized differential cross sections and vector analyzing powers are found to be very insensitive to these terms. © 2011 American Physical Society.