Effect of the Mott-Schwinger Interaction on Neutron-Proton Scattering

The influence of the interaction between the magnetic moment of a neutron and the Coulomb field of a target proton is investigated. For this interaction, channel spin is not conserved. A formalism is developed which includes the resulting singlet-triplet mixing. The scattering amplitude, or $M$ matrix, is presented, and its elements are related to the coefficients of the most general form of the $M$ matrix. Expressions for the nine most common nucleon-nucleon-scattering observables are obtained, including the effects of the singlet-triplet mixing. Coupled radial wave equations are derived and solved to reveal the phase-shift modifications. Calculations are performed over an energy range from 25 to 210 MeV using nuclear phase shifts previously determined from best ${\chi }^2$ fits to the scattering data. Our calculations indicate that all nine of the scattering observables considered are significantly influenced by the Mott-Schwinger interaction, but only for very small (