Observation of a K̄ NN bound state in the He 3 (K-, Λp)n reaction OBSERVATION of A K̄ NN BOUND STATE ... T. YAMAGA et al.
We have performed an exclusive measurement of the K-+He3→Λpn reaction at an incident kaon momentum of 1GeV/c. In the Λp invariant mass spectrum, a clear peak was observed below the mass threshold of K̄+N+N, as a signal of the kaonic nuclear bound state, K̄NN. The binding energy, decay width, and S-wave Gaussian reaction form factor of this state were observed to be BK=42±3(stat.)-4+3(syst.)MeV, ΓK