Role of tensor force in light nuclei with tensor-optimized shell model

We investigate the structures of light nuclei focusing on the role of the tensor force. We describe the tensor and short-range correlations with the tensor optimized shell model (TOSM) and the unitary correlation operator method (UCOM), respectively. In the TOSM, the 2p2h states are fully optimized to describe the large tensor contribution that brings high momentum components explicitly in the wave function. We use a bare nucleon-nucleon interaction AV8' and discuss the structures of the He and Li isotopes, such as the excitation energy spectra and the radii. We also investigate the structures of ⁸Be from the ground-band states to the highly excited states. These states of ⁸Be are indicated to have different structures of the 2α clustering states and the shell-model like states