The problem of hyperon-nucleon interaction is a key problem in the physics of hypernuclei. An extremely scarce experimental database of direct hyperon-nucleon interaction stimulates interest in studying bound hyperon-nucleon systems. From the point of view of studying spin-spin and spin- orbit components of N interaction and charge symmetry in hypernuclei the 7He and 9Be nuclei are of particular interest as examples of the p-shell nuclei. On the other hand these hyperon-nucleon systems may exhibit new properties in relation to nucleon-nucleus systems due to exclusion of the Pauli between hyperon and nucleons.
The 7He hypernucleus was considered within the 5He +n+n cluster model (Fig. 1).
Fig. 1 Cluster model 5He+n+n for 7He hypernucleus. Spin projection of particles are shown by arrows.
The hyperon-nucleon interaction is described by a one-boson-exchange potential that is constructed on the basis of the NSC97f model. Phenomenological potentials are used to describe the α and αN interactions. For the 5He interaction, used is a folding-model potential.
Our findings are:
Fig. 2 Low-lying levels of 7He hypernucleus. For comparison the spectrum of 6He is depicted. Total orbital momentum of each level is shown.
An α-cluster model is applied to study low-lying spectrum of the 9Be hypernucleus. The spin-orbit α interaction is given by modified Scheerbaum potential.
For 9 Be nucleus findings are:
Fig. 4 Low-lying levels of 9Be and 9Be spectrum.
Fig. 5 Low-lying levels of 9Be hypernucleus. Results of our calculation are noted by Cal.1. Calculations by T. Yamada, K. Ikeda, T. Motoba, H. Bando (PRC 38, 854 (1988)) are Cal. 2. Orbital momentum of each level is shown.