Recent developments in antikaon–nucleon dynamics

Abstract

Stimulated by various experimental achievements, the study ofKN dynamics now enters a new phase. The two-bodyKN interaction is largely constrained by recent experimental data, and the nature of the Λ(1405) resonance is being unveiled by several theoretical analyses. These findings provide a basic tool for applications toK-nuclear systems. We summarize the current status of theKN phenomenology and outline the future direction in this field.

Observation of the "K- pp"-like structure in the d( +, K+) reaction at 1.69 GeV/c

“…The information on the KN interaction has been obtained by analyzing low-energy KN scattering data and kaonic-atom X-ray data [1]. The recent measurement of the energy shift and width on kaonic-hydrogen X-ray in high precision by the SIDDHARTA group [2] has contributed a lot [3]. From the theoretical analyses by using these results, it is well known that the KN interaction has a strong attraction in isospin 0 channel, which suggests possible existence of kaonic bound state formations [4].…”

MESON2016 – Concluding Remarks

“…A recent LQCD calculation confirms its KN hadronic structure [2] as opposed to a tightly bound genuine pentaquark. Indeed, the Λ(1405) emerges naturally below the K − p threshold in chiral EFT hadronic approaches [3], although as shown in Cieplý's talk [4] the subthreshold KN scattering amplitudes exhibit appreciable model dependence, with consequences for K − pp quasibound-state searches.…”

K−ppsearch experiments at J-PARC

“…While our understandings on theKN interaction near the binding threshold have been in progress [1] together with the nature of Λ(1405) resonance, we still have some theoretical ambiguities whether the real part of theK-nucleus potential is deeply attractive (−(150-200) MeV) or shallow (−(40-60) MeV) [2].…”