A pentaquark model of the negative parity Lambda(1405)

We test a pentaquark model of the negative parity hyperon Lambda(1405). We use the model where valence four quarks and one antiquark move in a potential relativisticaly and interact with themselves and each other through gluon and NG boson. We calculate mass shift of the system and find that there are two Lambda(1405) with almost degenerate mass: one flavor singlet and one flavor octet. We calclate also sigma-term and scalar form factor of the hyperon and show their usefulness to deduce the number of valence quark in the hypeon.Comment: 4 pages, 1 figure, to appear in the proceedings of the Yukawa International Seminar (YKIS) 2006, "New frontiers in QCD", Kyoto, Japa

Bound H-dibaryon in the Flavor SU(3) Limit from a Full QCD Simulation on the Lattice

Existence of the H-dibaryon in the flavor SU(3) symmetric limit is studied by full QCD simulations on the lattice, in the approach recently developed for the baryon-baryon (BB) interactions. Potential of the flavor-singlet BB channel is derived from the Nambu-Bethe-Salpeter wave function, and a bound H-dibaryon is discovered from it, with the binding energy of 20--50 MeV for the pseudo-scalar meson mass of 469--1171 MeV.Comment: 3 pages, 2 figures, talk presented at the 19th Particles & Nuclei International Conference (PANIC 2011), Massachusetts Institute of Technology, Cambridge, MA, USA, July 24-29, 201

Fully coupled-channel study of K−ppK^-pp resonance in a chiral SU(3)-based KˉN\bar{K}N potential

We have investigated the most essential kaonic nucleus "$K^-pp$" as a resonant state of the $\bar{K}NN$-$\pi\Sigma N$-$\pi\Lambda N$ coupled channel system using a chiral SU(3)-based $\bar{K}N$ potential. We treat the "$K^-pp$" resonance adequately with a fully coupled-channel complex scaling method (full ccCSM). Self-consistency needs to be considered for the energy dependence of the chiral SU(3)-based potential. In the present study, we propose a simple prescription for the treatment of self-consistency, considering the {\it averaged threshold} and {\it averaged binding energy of mesons}. With this prescription, we have successfully found the self-consistent solutions of the "$K^-pp$" three-body resonance. The results indicate that the "$K^-pp$" system is bound rather shallowly. In particular, when the potential parameters are constrained with the latest $\bar{K}N$ scattering length, the binding energy and half of the mesonic decay width are obtained as $14-50$ MeV and $8-19$ MeV, respectively.Comment: 7 pages, 2 figures, accepted by Phys. Lett.