In-medium K - And η-meson interactions and bound states

The role played by subthreshold meson-baryon dynamics is demonstrated in K-atom, ηK -nuclear and η-nuclear bound-state calculations within in-medium models of K N and ηN interactions. New analyses of kaonic atom data reveal appreciable multi-nucleon contributions. Calculations of η-nuclear bound states show, in particular, that the ηN scattering length is not a useful indicator of whether or not η mesons bind in nuclei nor of the widths anticipated for such states.