Tensor Correlation in 4He and Its Effect on the Doublet Splitting in 5He

We investigate the role of tensor correlation on the structures of\nuc{4}{He} and its effect on the doublet splitting in \nuc{5}{He}. We performa configuration mixing calculation in the shell model type bases to representthe tensor correlation for $^4$He. It is found that our model describes thecharacteristics of the tensor correlation, which is represented by an admixtureof the $0s_{1/2}$ configuration with a spatially modified $0p_{1/2}$ orbit. For$^5$He, we solve a coupled OCM equation for an extended $^4$He+$n$ model, whiletaking into account the tensor correlation in the $^4$He cluster. It is shownthat 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 doubletsplitting in $^5$He. This indicates that the strength of the effectivespin-orbit interaction should be reduced by about half from the conventionalone. We obtain a reliable $^4$He-$n$ interaction, including the tensorcorrelation, which further improves the behavior of the $d$- and $f$-wave phaseshifts in the $^4$He+$n$ system.Comment: 21 pages, 9 figures, To be published in Progress of Theoretical Physic