Structure of the sigma meson and the softening

We study the structure of the sigma meson, the lowest-lying resonance of the pi pi scattering in the scalar-isoscalar channel, through the softening phenomena associated with the partial restoration of chiral symmetry. We build dynamical chiral models to describe the pi pi scattering amplitude, in which the sigma meson is described either as the chiral partner of the pion or as the dynamically generated resonance through the pi pi attraction. It is shown that the internal structure is reflected in the softening phenomena; the softening pattern of the dynamically generated sigma meson is qualitatively different from the behavior of the chiral partner of the pion. On the other hand, in the symmetry restoration limit, the dynamically generated sigma meson behaves similarly to the chiral partner.Comment: 10 pages, 2 figures, 1 table, talk give at HNP09, November 16-19, 2009, RCNP, Osaka Universit

Electric Mean Squared Radii of Lambda(1405) in Chiral Dynamics

The electric mean squared radii _E of Lambda(1405) are calculated in the chiral unitary model. We describe the Lambda(1405) as a dynamically generated resonance fully in the octet meson and octet baryon scattering. We also consider ``Lambda(1405)'' as a bound state of KbarN. For the later ``Lambda(1405),'' we obtain negative and larger absolute value of electric mean squared radius than that of ordinary baryons, which implies that Lambda(1405) have structure of widely spread K^- around p.Comment: 4 pages, 1 figure, use ws-mpla.cls. Talk given at Workshop on Chiral Symmetry in Hadron and Nuclear Physics: Chiral07, Osaka, Japan, 13-16 Nov 200

Electromagnetic mean squared radii of Lambda(1405) in chiral dynamics

The electromagnetic mean squared radii, _E and _M, of Lambda(1405) are calculated in the chiral unitary model. We describe the excited baryons as dynamically generated resonances in the octet meson and octet baryon scattering. We evaluate values of _E and _M for the Lambda(1405) on the resonance pole and obtain their complex values. We also consider Lambda(1405) obtained by neglecting decay channels. For the latter case, we obtain negative and larger absolute electric mean squared radius than that of typical ground state baryons. This implies that Lambda(1405) has structure that K^- is widely spread around p.Comment: 7 pages, 4 figures, use elsart3p.cl

Determining the Θ+\Theta^+ quantum numbers through a Kaon induced reaction

We study the $K^+p\to \pi^+KN$ reaction with kinematical condition suited to the production of the $\Theta^+$ resonance. It is shown that in this reaction with the polarization experiment, a combined consideration of the strength at the peak and the angular dependence of cross section can help determine the $\Theta^+$ quantum numbers.Comment: 4 pages, 3 figures, Talk given at International Workshop PENTAQUARK04 at SPring-8, Japan, July 20-23, 200

A narrow DNNDNN quasi-bound state

The energies and widths of $DNN$ quasi-bound states with isospin I=1/2 are evaluated in two methods, the fixed center approximation to the Faddeev equation and the variational method approach to the effective one-channel Hamiltonian. The $DN$ interactions are constructed so that they dynamically generate the $\Lambda_c(2595)$ (I=0, $J^{\pi} =1/2^-$) resonance state. We find that the system is bound by about 250 MeV from the $DNN$ threshold, $\sqrt{s} \sim 3500$ MeV. Its width including both the mesonic decay and the $D$ absorption, is estimated to be about 20-40 MeV. The I=0 $DN$ pair in the $DNN$ system is found to form a cluster that is similar to the $\Lambda_c(2595)$.Comment: 17 pages, 18 figures, 3 table