We have performed an exclusive measurement of the K− + 3He → Λpn reaction at an incident kaon momentum of 1 GeV/c. In the Λp invariant mass spectrum, a clear peak was observed below the mass threshold of K¯ +N +N, as a signal of the kaonic nuclear bound state, KNN. The binding energy, decay width, and S-wave Gaussian reaction form-factor of this state were observed to be BK = 42 ± 3(stat.)+3−4(syst.) MeV, ΓK = 100 ± 7(stat.)+19−9 (syst.) MeV, and QK = 383 ± 11(stat.)+4−1(syst.) MeV/c, respectively. The total production cross-section of KNN, determined by its Λp decay mode, was σKtot · BRΛp = 9.3 ± 0.8(stat.)+1.4−1.0(syst.) µb. We estimated the branching ratio of the KNN state to the Λp and Σ0p decay modes as BRΛp/BRΣ0p ∼ 1.7, by assuming that the physical processes leading to the ΣNN final states are analogous to those of Λpn.
|Publication status||Published - 2020 Jun 23|
ASJC Scopus subject areas