Structure of the A=3 Σ-hypernuclei

The structure of A=3 Σ-hypernuclei is investigated on the basis of a central two-body ΣN interaction. We perform a three-body coupled-channel calculation by using the coupled-rearrangement-channel variational method. The results suggest that there exist unstable bound states of S=1/2, i.e. 3ΣH, 3ΣHe and 3Σn, due to the channel coupling through the ΣN potential which strongly admixes 3S1, TNN=0 and 1S0, TNN=1 states in the NN pair. The total isospin T=1 is approximately a very good quantum number (>or∼96%). In 3ΣHe and 3Σn, energies are largely affected by the Coulomb potential and dependent on the model of the ΣN potential. The characteristic features of the nucleus-Σ potential are also discussed. (orig.)