Tensor correlation in 4He and its effect on the doublet splitting in 5He

We investigate the role of tensor correlation on the structures of He-4 and its effect on the doublet splitting in He-5. We perform a configuration mixing calculation in the shell model type bases to represent the tensor correlation for He-4. It is found that our model describes the characteristics of the tensor correlation, which is represented by an admixture of the 0s(1/2) configuration with a spatially modified 0p(1/2) orbit. For He-5, we solve a coupled OCM equation for an extended He-4+n model, while taking into account the tensor correlation in the He-4 cluster. It is shown that the tensor correlation produces the Pauli blocking, in particular, for the J(pi) = 1/2(-) state, and its effect causes about half of the p-wave doublet splitting in He-5. This indicates that the strength of the effective spin-orbit interaction should be reduced by about half from the conventional one. We obtain a reliable He-4-n interaction, including the tensor correlation, which further improves the behavior of the d- and f-wave phase shifts in the He-4+n system.