Experimental study of K̅NN and future experiments for kaonic nuclei

Abstract

Quasi-bound systems of antikaon and nucleus, K̅ -nuclei, have been considered as a natural extension of the interpretation that Λ(1405) is the K̅-N hadronic molecule. The lightest K̅-nucleus, K̅NN quasi-bound state, is particularly important to be investigated for confirmation of the existence of such an exotic nuclear state containing a meson. We conducted an experiment, JPARC E15, to search for K̅NN(Iz=+1/2) by the in-flight K− induced reaction on 3He, and finally observed a clear signal of K̅NN(Iz=+1/2) for the first time. To robustly confirm the existence of K̅-nuclei, we have planned systematic measurements for various K̅ -nuclei at J-PARC.