Super strong nuclear force caused by migrating K̄ mesons - Revival of the Heitler-London-Heisenberg scheme in kaonic nuclear clusters

Strong binding and shrinkage of single and double (K) nuclear systems (K(-)pp, K(-)ppn, K(-)K(-)p and K(-)K(-)pp) predicted by Faddeev-Yakubovsky calculations

Non-relativistic Faddeev and Faddeev-Yakubovsky calculations were made for K(-)pp, K(-)ppn, K(-)K(-)p and K(-)K(-)pp kaonic nuclear clusters, where the quasi bound states were treated as bound states by employing real separable potential models for the K(-)-K(-) and the K(-)-nucleon interactions as well as for the nucleon-nucleon interaction. The binding energies and spatial shrinkages of these states, obtained for various values of the K interaction, were found to increase rapidly with the K interaction strength. Their behaviors are shown in a reference diagram, where possible changes by varying the K interaction in the dense nuclear medium are given. Using the Λ(1405) ansatz with a PDG mass of 1405 MeV/c(2) for K(-)p, the following ground-state binding energies together with the wave functions were obtained: 51.5 MeV (K(-)pp), 69 MeV (K(-)ppn), 30.4 MeV (K(-)K(-)p) and 93 MeV (K(-)K(-)pp), which are in good agreement with previous results of variational calculation based on the Akaishi-Yamazaki coupled-channel potential. The K(-)K(-)pp state has a significantly increased density where the two nucleons are located very close to each other, in spite of the inner NN repulsion. Relativistic corrections on the calculated non-relativistic results indicate substantial lowering of the bound-state masses, especially of K(-)K(-)pp, toward the kaon condensation regime. The fact that the recently observed binding energy of K(-)pp is much larger (by a factor of 2) than the originally predicted one may infer an enhancement of the K interaction in dense nuclei by about 25% possibly due to chiral symmetry restoration. In this respect some qualitative accounts are given based on "clearing QCD vacuum" model of Brown, Kubodera and Rho.

New way to produce dense double-antikaonic dibaryon system, KKNN, through Λ(1405)-doorway sticking in p+p collisions

A recent successful observation of a dense and deeply bound K nuclear system, K-pp, in the p+p→K++K-pp reaction in a DISTO experiment indicates that the double-K dibaryon, K-K-pp, which was predicted to be a dense nuclear system, can also be formed in p+p collisions. We find theoretically that the K--K- repulsion plays no significant role in reducing the density and binding energy of K-K-pp and that, when two Λ(1405) resonances are produced simultaneously in a short-range p+p collision, they act as doorways to copious formation of K-K-pp, if and only if K-K-pp is a dense object, as predicted.

Indication of a deeply bound and compact K- pp state formed in the pp- -> pLambdaK+ reaction at 2.85 GeV

We have analyzed data of the DISTO experiment on the exclusive pp --> pLambdaK+ reaction at 2.85 GeV to search for a strongly bound compact K- pp(approximately = X) state to be formed in the pp --> K+ + X reaction. The observed spectra of the K+ missing mass and the pLambda invariant-mass with high transverse momenta of p and K+ revealed a broad distinct peak of 26-sigma confidence with a mass M(X)=2267+/-3(stat)+/-5(syst) MeV/c2 and a width Gamma(X)=118+/-8(stat)+/-10(syst) MeV. The enormously large cross section indicates formation of a compact K- pp with a large binding energy of B(K)=103 MeV, which can be a possible gateway toward cold and dense kaonic nuclear matter.

Kaonic nuclear systems KN and KNN as decaying states

The formation spectra of model KN and KNN systems formed by (K(-),n) reactions are investigated in order to obtain a theoretical basis for a proper interpretation of experimental data concerning kaonic nuclear quasi-bound states. It has been clarified that the experimentally observable kaonic nuclear state K(-)pp should be regarded as the decaying state introduced by Kapur-Peierls, which is different from the pole state solution of the Faddeev equation.

Kaonic nuclear systems KN and KNN as decaying states

The formation spectra of model KN and KNN systems formed by (K(-),n) reactions are investigated in order to obtain a theoretical basis for a proper interpretation of experimental data concerning kaonic nuclear quasi-bound states. It has been clarified that the experimentally observable kaonic nuclear state K(-)pp should be regarded as the decaying state introduced by Kapur-Peierls, which is different from the pole state solution of the Faddeev equation.