S= -2 Hypernuclear Structure

Abstract

The structure of light hypernuclei with strangeness S = −2 is investigated with the three-, four-, and five-body cluster model and the Gaussian Expansion method (GEM). Energy levels of the double-Λ hypernuclei ΛΛΛ7He, ΛΛΛ7Li, ΛΛΛ8Li, ΛΛΛ9Li, ΛΛΛ9Be, and ΛΛΛ10Be are predicted with the framework of αxΛΛ four-body model, where x = n, p, d, t, 3He, and α, respectively. Also, energy levels of the double Λ hypernucleus, ΛΛΛ11Be are calculated within the framework of a ααnΛΛ five-body model. The Demachi-Yanagi event, identified as ΛΛΛ10Be, is interpreted as an observation of its 2+ state excited state. The Hida event, recently observed at KEK-E373 experiment, is interpreted as an observation of the ground state of the ΛΛΛ11Be. Detailed structure calculations in Ξ12_Be, Ξ5_H, Ξ9_Li, Ξ7_H and Ξ10_Li are performed within the framework of the microscopic two-, three- and four-body cluster models. Ξ7_H and Ξ10_Li are predicted to have bound states.