Nuclear medium effects on K and (K)over-bar interactions

Medium effects on the interaction of Ii and Ii mesons with nucleons are reviewed. Recent K+ nuclear data confirm that conventional multiple scattering models fail to describe the interaction of K mesons for incoming momenta p(L) = 400-800 MeV/c, suggesting a particular form of density dependence for the K nuclear optical potential. K- atom strong-interaction data, fitted using a density dependent nuclear optical potential which respects the low-density theorem, require an appreciably stronger attraction than that obtained using a V-opt = t rho form, of order 180 +/- 20 MeV at nuclear-matter density. The relationship of this result to the physics of the Lambda(1405) (K) over bar N unstable bound state is clarified, and the prospects of meeting the conditions for K- condensation in high-density matter are discussed.