The interaction of K mesons with nuclei

The experimental data for K⁻ capture by nuclei is interpreted in terms of K⁻ nucleon scattering amplitudes in a region of negative relative kinetic energy. It is shown that constant scattering length solutions which represent the data in the region of positive relative kinetic energy up to 100 MeV do not satisfactorily describe the interaction with bound nucleons and a modified scattering length solution is proposed. Measured values of the widths of K-mesic X-ray lines which require a strongly attractive K⁻ nucleons optical potential are successfully interpreted in terms of K⁻N scattering lengths appropriate for bound nucleons. The information obtainable about relative neutron and proton density distributions in the nuclear periphery from studies of this kind is discussed. The need for more data on interaction of K⁻ in hydrogen at low kinetic energies and at rest and in other elements at rest is emphasised.