Basic K nuclear cluster, K-pp, and its enhanced formation in the p+p→K++X reaction

We have studied the structure of K-pp nuclear cluster comprehensively by solving this three-body system exactly in a variational method starting from the Ansatz that the Λ(1405) resonance (≡Λ*) is a K-p bound state. We have found that our original prediction for the presence of K-pp as a compact bound system with M=2322 MeV/c2,BK=48 MeV, and Γ=60 MeV remains unchanged by varying the KN and NN interactions widely as far as they reproduce Λ(1405). The structure of K-pp reveals a molecular feature, namely the K- in Λ* as an ''atomic center'' plays a key role in producing strong covalent bonding with the other proton. We have shown that the elementary process, p+p→K++Λ*+p, which occurs in a short impact parameter and with a large momentum transfer (Q∼1.6 GeV/c), leads to unusually large self-trapping of Λ* by the participating proton, because the Λ*-p system exists as a compact doorway state propagating to K-pp (RΛ*p∼1.67 fm)