Tensor correlation in 4He with the tensor-optimized shell model

We study the characteristics of the tensor correlation in He-4 using a shell model type method. We treat the tensor force explicitly by performing a configuration-mixing calculation in the 2p2h basis and include single-particle states up to intermediately high angular momenta. We adopt the Gaussian expansion method for the quantitative description of the spatial shrinkage of the single-particle states to optimize the tensor correlation. We are able to describe the full strength of the tenser correlation for He-4 in the shell model type method by realizing convergence. We call this model the tensor-optimized shell model. It is found that in He-4, three specific 2p2h configurations are strongly coupled with the (08)4 configuration due to the characteristic features of the tenser operator.