Shell-Model Calculations for_{\Lambda}^{16}O and_{\Lambda}^{17}O Using   Microscopic Effective Interactions with \Sigma Degrees of Freedom
  Shell-model calculations in a large model space are performed for _{\Lambda}^{16}O and_{\Lambda}^{17}O. Effective interactions with degrees of freedom of \Sigma in addition to \Lambda and nucleons are derived from hyperon-nucleon and nucleon-nucleon interactions within the framework of the unitary-model-operator approach. Effects of the \Sigma degrees of freedom and the parity-mixing intershell coupling on the \Lambda hypernuclear structure are investigated, employing the Nijmegen NSC97a-f and NSC89 hyperon-nucleon potentials. 
S. Fujii, R. Okamoto, K. Suzuki