Hiroharu Bandō

EFFECTIVE HAMILTONIAN AND ENERGY GAP IN FINITE NUCLEI

An effective hamiltonian is derived for finite nuclei from the original one that contains a hard-core interaction. The former has a screened hard-core interaction and is used to treat the phenomena near the ground state of the nuclei. Thus it gives a base for the calculation in the shell model. As an example, the energy gap is calculated for Ni/sup 60/ by applying Bogoliubovs method to the effective hamiltonian. (auth)

pi-Mesonic decay of hypernuclei and pion wavefunction

The pi-mesonic decay of hypernuclei is studied by using the pion distorted waves which are the solutions of the Klein-Gordon equation with the optical potential. The distortions of the pion waves give rise to significant enhancement of theπ-decay rate compared with the pion free-wave case. Theπ-decay rates are very sensitive to the behavior of the pion wave deep inside the nucleus and therefore to the chosen pion optical potentials. There is a tendency that the enhancement is larger for theπ−-decay than for theπ0-decay due to the combined effects of the Coulomb and optical potentials.

REACTION MATRIX THEORY FOR CLUSTER STATES IN LIGHT NUCLEI. II. CLUSTERING DEPENDENCE OF THE EFFECTIVE INTERACTION.

The states with triangular and linear chain configurations of three a-clusters in C12 are treated by the reaction matrix theory on the basis of a realistic nuclear force. Clustering dependence of G-matrix is found to be essential for clusterization. It also ·brings on a change of effective interaction between the two configurations, which has a role in reducing the excitation energy of the linear chain state. Its origin is mainly in the triplet even-state tensor force.

Cluster model study of lightp-shell Λ-hypernuclei with OBE-based effective ΛN interaction

AbstractThe structures of the lightp-shell hypernuclei

Extended Folding Potential Model for Λ-Deuteron System with Hard Core Potential

{}_\Lambda ^6 He,{}_\Lambda ^7 Li,{}_\Lambda ^9 Liand{}_\Lambda ^9 Be

Light p-Shell Λ-Hypernuclei by the Microscopic Three-Cluster Model

are studied by using a realistic effectiveΛN interaction (YNG), and compared to those with the use of the simple one-range Gaussian (ORG) interaction. The YNG interaction, which simulates theΛNG-matrix for the Nijmegen OBE modelD, is characterized by the inner repulsive core and the density-dependence along with the space-exchange and spin-spin components. The framework we adopt is the microscopic α +x + Λ (x=n, d, t or α) three-cluster model, where nucleon antisymmetrization is exactly treated. The characteristic behaviors ofΛ−x andΛ−(αx) interactions derived from the YNG are displayed and discussed. In spite of the remarkable characteristic of YNG, the calculated energy levels of the four hypernuclei are very similar to those previous obtained by using the simple ORG interaction. The stabilization and contraction of the hypernuclear system due to the glue-like role ofΛ-particle persists in the present calculation, though the repulsive core of theΛN interaction tends to prevent from too much contraction.

On the Λ-Hypernuclear Single Particle Energies

The effect of the pion wave distortion on the pi-mesonic weak decay ofΛ-hyperon in hypernuclei is studied by using two different pion optical potentials, one by Gmitro, Kamalov and Mach, which is given in momentum space, and the other by MSU group, which is in the standard Kisslinger form. The two potentials lead to a striking difference in the pi-mesonic decay, reflecting different behaviors of the pion wavefunctions deep inside the nucleus.

Chapter II. Baryon-Baryon Interactions and Single-Particle Aspects of Hypernuclei

An extended folding potential model for the J1·d system is proposed to treat both the bound state and scatterings within the same framework by using hard core potentials. This model is derived by a variational method to take into account interparticle correlations. The J1-d scattering length and the binding energy of ~H are calculated with the effective central potential proposed by Dalitz, et al. The present model is proved advantageous not only in handling hard core potentials but also in visualizing the physical structure of the J1·d system.