Kaon-nucleon dynamics and role of chiral symmetry

The K¯ is a flavor partner of the π meson which contains the strange quark. Because of the Λ(1405) quasi-bound state which lies below the K¯N threshold, the interaction of the K¯ and the nucleon is considered to be strongly attractive, leading to the possibility of the bound K¯ nuclei. On the other hand, the K¯ is the Nambu-Goldstone boson of spontaneous breaking of chiral SU(3)×SU(3) symmetry in QCD. We discuss the dynamics of the K¯N interaction and the K¯-nuclear systems from the viewpoint of chiral symmetry.