K+-nucleus scattering and the nucleon in the nuclear medium

The ${\mathit{K}}^{+}$-nucleus interaction is investigated in the context of a covariant, momentum-space optical potential that incorporates covariant kinematics, relativistic normalizations, and phase-space factors, a covariant treatment of the recoil of the target nucleus, utilizes invariant amplitudes which are free of kinematic singularities, and allows an exact performance of the Fermi integration over the momentum of the struck nucleon. Elastic differential cross sections for ${\mathit{K}}^{+}$ scattering from ${}_{}{}^{12}{}_{}{}^{}\mathrm{C}$ and ${}_{}{}^{40}{}_{}{}^{}\mathrm{Ca}$ and total cross sections for ${\mathit{K}}^{+}$ scattering from ${}_{}{}^{12}{}_{}{}^{}\mathrm{C}$ are calculated. An enhanced, in-medium, two-body interaction is indicated as the data is consistent with an approximate 30% enhancement of the theoretical calculations.