Nucleon-nucleon scattering with isobar degrees of freedom.

Abstract

A nonrelativistic nucleon-nucleon interaction potential model containing explicit coupling to N\ensuremath{\Delta}(1232 MeV) and /or ${\mathrm{NN}}^{\mathrm{*}}$(1440 MeV) channels is developed and used to describe empirical elastic scattering phase shifts from 0--1000 MeV. The theoretical Feshbach-Lomon meson exchange potential provides the starting point for describing the interaction between the two nucleons. NN\ensuremath{\pi} and NNNN\ifmmode\bar\else\textasciimacron\fi{} intermediate states are implicitly included through the two-pion exchange portion of the Feshbach-Lomon interaction. Short range phenomenological NN-NN potentials are used along with empirical short range and one pion exchange coupling potentials between the nucleon-nucleon and nucleon-isobar channels. Quantitative fits to the Arndt phase shifts and inelasticity parameters from 0--1000 MeV for J\ensuremath{\le}6 are obtained. The resulting potentials are obtained in a local, coordinate space representation, convenient for use in many-body calculations at intermediate energies.