The Λ-Sigma coupling effect in the neutron-rich Λ-hypernucleus _(Λ)¹⁰Li by microscopic shell model

We investigate the structure of the neutron-rich $\Lambda$-hypernucleus $_{\Lambda}^{10}$Li by using microscopic shell-model calculations considering a $\Lambda$-$\Sigma$ coupling effect. The calculated $\Sigma$-mixing probability in the $_{\Lambda}^{10}$Li ground state is found to be about 0.34 % which is coherently enhanced by the $\Lambda$-$\Sigma$ coupling configurations, leading to the energy shift 0.28 MeV which is about 3 times larger than that in $_{\Lambda}^{7}$Li. The importance of the $\Sigma$ configuration obtained by the $\Sigma N$ interaction and the potentiality of the neutron-rich environment are discussed.