Two- and three-alpha systems with nonlocal potential

Two body data alone cannot determine the potential uniquely, one needs three-body data as well. A method is presented here which simultaneously fits local or nonlocal potentials to two-body and three-body observables. The interaction of composite particles, due to the Pauli effect and the indistinguishability of the constituent particles, is genuinely nonlocal. As an example, we use a Pauli-correct nonlocal fish-bone type optical model for the $\alpha-\alpha$ potential and derive the fitting parameters such that it reproduces the two-$\alpha$ and three-$\alpha$ experimental data.Comment: 16 pages, 5 figures, Inverse Scattering Conference, Aug 2007, Siofok, Hungary New reference adde

Cluster structures in Oxygen isotopes

Cluster structure of 16O,18O and 20O is investigated by the antisymmettrized molecular dynamics (AMD) plus generator coordinate method (GCM). We have found the K^{\pi}=0$_2^+$ and 0$_1^-$ rotational bands of 18O that have the prominent 14C+\alpha cluster structure. Clustering systematics becomes richer in 20O. We suggest the K^{\pi}=0$_2^+$ band that is the mixture of the 12C+\alpha+4n and 14C+6He cluster structures, and the K^{\pi}=0$_1^-$ band that has the 14C+6He cluster structure. The K^{\pi}=0$_3^+$ and 0$_2^-$ bands that have the prominent 16C+\alpha cluster structure are also found.Comment: 9pages, 9figure

Realistic ghost state: Pauli forbidden state from rigorous solution of the α particle

The antisymmetrization of the composite particles in cluster model calculations manifests itself in Pauli forbidden states (ghost states), if one restricts oneself to an undeformed cluster in the low-energy region. The resonating group method and the generating coordinate method rely on a property of the norm kernel, which introduces some of the ghost states. The norm kernel has been usually been calculated under the assumption that the inner wave functions have a simple Gaussian form. This is the first time that this assumption has been tested in a rigorous way. In the 4He+N system, we demonstrate a ghost state, which is calculated from a rigorous solution of Yakubovsky equations for the α particle. The ghost states calculated by rigorous and approximate methods turn out to have a very similar form. It is analytically proved that the trace of the norm kernel does not depend on the inner wave function we choose

Discrepancy in the cross section minimum of elastic nucleon-deuteron scattering

Δ-isobar excitation in the nuclear medium yields an effective three-nucleon force. A coupled-channel formulation of nucleon-deuteron scattering with Δ-isobar excitation developed previously is used. The three-particle scattering equations are solved by a separable expansion of the two-baryon transition matrix below the inelastic threshold of pion production. The effect of Δ-isobar excitation on the spin-averaged differential cross section is studied. The discrepancy between theory and experiment in the diffraction minimum is reduced

A new molecular dynamics calculation and its application to the spectra of light and strange baryons

A new approach based on antisymmetrized molecular dynamics is proposed to correctly take account of the many-body correlation. We applied it to the spectra of low-lying, light and strange baryons. The inclusion of the quark-quark correlation is vital to predict the precise spectra, and the semi-relativistic kinematics is also important to correct the level ordering. The baryon spectra calculated by the present method is as precise as the Faddeev calculation.Comment: 13 pages, 2 figure