On K−-nuclear Interaction, K−-nuclear Quasibound States and K− Atoms

The K−N potentials derived from SU(3) chiral coupled-channel meson-baryon interaction models fail to describe kaonic atom data. It was shown that K− single-nucleon potentials have to be supplemented by a phenomenological K− multi-nucleon optical potential in order to achieve good description of the data. Moreover, only the Prague, Kyoto-Munich and Barcelona models are able to account for the experimental data on K− atoms and K− singlenucleon absorption ratios from bubble chamber experiments. A considerable imaginary part coming from the multi-nucleon absorption ruled out existence of narrow K−-nuclear quasibound states in nuclei with A ≥ 6. We have developed a microscopic model for the K−NN absorption in nuclear matter. The absorption was described as a meson-exchange process and the primary K−N interaction strength was derived from the state-of-the-art chiral models. The medium modifications of the K−N scattering amplitudes due to the Pauli exclusion principle were taken into account. The model was applied in calculations of kaonic atoms for the first time. The description of the data improved significantly when the two nucleon absorption was considered.