S = -1 hypernuclear structure

The structure of light hypernuclei with strangeness S = -1 is investigated with the three- and four-body cluster model and the Gaussian Expansion method (GEM). Interesting phenomena such as shrinkage effect of the core nucleus and the halo and skin structure due to the glue-like role of A particle are demonstrated from the study of structure of _Λ⁶He, _Λ⁷Li and _Λ¹³C. Precise three- and four-body cluster calculation of _Λ⁷He, _Λ⁷Li, _Λ⁷Be, _Λ⁹Be and _Λ¹³C provide us with information about ΛN interaction such as spin-spin, spin-orbit, charge symmetry breaking term, etc., by comparing with the recent experimental data. Precise four-body calculation taking NNNΛ and NNNΣ for _Λ⁴H and _Λ⁴He are performed and the role of Λ-Σ conversion and the size of the virtual Σ component in _Λ⁴H and _Λ⁴He are discussed.