Recent results on K− absorption at rest by few nucleons and the bound kaonic nuclear state puzzle

Data from the absorption reaction in light nuclei (6,7Li, 9Be, 13C and 16O) have recently been collected by FINUDA at DAΦNE, INFN Laboratori Nazionali di Frascati (LNF), Italy. The studies of kaon absorption on multibaryonic systems have been carried out by examining Λp(d,t) correlations. The observation of a nearly constant rate of Λp(d,t) pairs emitted in opposite direction for the targets examined suggests that the absorption of K− at rest in nuclei proceeds through the formation of an intermediate nuclear state, often named Bound Kaonic Nuclear (BKN) state. The experimental study of such states is based on the behavior of the Λp(d,t) invariant masses, which allow the structure of bound [K−NN(NNN, NNNN)] systems in nuclei to be examined. Missing mass distributions supply complementary information on the dynamics of the K− absorption.