Effects of Tensor Interactions in Nuclei

It is well known that the strong tensor interaction is caused by pion exchange between nucleons due to the pseudo-scalar nature of the pion. However, in most of the successful nuclear models, mean field models as examples do not include the tensor interactions explicitly. Many evidences are known that the tensor interactions play important role in nuclear structure. Recently, the expansion of studies of nuclei far from the stability line presents important cases since the ratio of proton and neutron numbers changes in large. In this chapter, experimental evidences in ground states of nuclei that require the tensor interactions are presented. A focus is set on the contribution of tensor interactions through the high-momentum components of nucleon, which is difficult to be handled in mean field models of nuclei.