Theory of Kaon-Nuclear Systems

The strong interaction between an antikaon and a nucleon is at the origin of various interesting phenomena in kaon-nuclear systems. In particular, the interaction in the isospin I = 0 channel is sufficiently attractive to generate a quasibound state, the Λ(1405) resonance, below the K¯N threshold. Based on this picture, it may be expected that the K¯N interaction also generates quasibound states in kaon-nuclear systems, sometimes called kaonic nuclei. At the same time, the K¯N quasibound picture of the Λ(1405) is also related to the discussion of hadronic molecules in hadron spectroscopy. Here an overview is presented on the theoretical studies developed for kaon-nucleon and kaon-nuclear systems. We start from the modern understanding of the Λ(1405) resonance. We then discuss the K¯N interaction and various aspects of few-body kaonic nuclei. Heavier kaon-nuclear systems are examined from the viewpoint of nuclear many-body physics, with focus on the properties of antikaons in nuclear matter. Related topics, such as the K⁻p momentum correlation functions in high-energy collisions and the studies of kaonic atoms, are also discussed.