MESON EXCHANGE CURRENT CONTRIBUTION TO K+-NUCLEUS SCATTERING

We investigate the meson exchange current (MEC) contribution to K+-nucleus elastic scattering. Starting with a model of the off-shell Kpi scattering amplitude and a calculation of the excess pion distribution in finite nuclei, we proceed to derive both real and imaginary forward scattering amplitudes for the MEC contribution. The resulting amplitudes interfere constructively with the optical model amplitudes, and, therefore, lead to an increase in both calculated total and differential cross sections. This increase brings about a better agreement with the data, in particular with regard to the energy dependence of the total cross section. This last feature follows from the fact that the calculated imaginary MEC amplitude has a threshold at incident momentum p approximately 400 MeV/c, which distinguishes our MEC model from recently proposed nucleon ''swelling'' models. We also examine the sources of uncertainties for our results.