Few-body systems with S = - 1 and -2

The structure of the T = 1 iso-triplet hypernuclei, _Λ⁷He, _Λ⁷Li and _Λ⁷Be within the framework of an α + Λ + N + N four-body cluster model is studied. A phenomenological ΛN charge symmetry breaking (CSB) interaction is introduced. The Λ binding energy of the ground state in _Λ⁷He is predicted to be 5.16 (5.36) MeV with(without) the CSB interaction. The five-body cluster model calculation of α α n Λ Λ for _{Λ Λ}¹¹Be, which has been observed as Hida event, is performed. The calculated B_{Λ Λ} is 18.23 MeV, which is less bound by about 2 MeV than the experimental data. The structure calculation in _Ξ-⁷Li and _Ξ-¹⁰Li are performed within the framework of α Ξ^- n n and α α Ξ^- n four-body model. _Ξ-⁷Li and _Ξ-¹⁰Li are predicted to have bound states. We propose to observe the bound states in future (K^-, K⁺) experiments using ⁷Li and ¹⁰B targets in addition to the standard ¹²C target.