Double-Strangeness Five-Body System

概要

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We perform theoretical analysis on the structure and decay of a double-strangeness five-body system which consists of ^<5>_<ΛΛ>H and ^<5>_<Ξ> states. In this S= -2 five-body system the thresholds of the tΛΛ channel and the αΞ^- channel come closer with only 8.51 MeV difference. We treat both bound and resonant states of the three-body channels tΛΛ and tpΞ^- by applying a complex rotation method. It is found that there is a bound ^<5>_<ΛΛ>H state with 6.3 MeV below the threshold of t+Λ+Λ. In the Ξ^- channel a resonant ^<5>_<Ξ> state appears at 1.7 MeV below the threshold of α+Ξ^-. Though the existence of this state is ensured by the Coulomb interaction, it is a `halo' nuclear state rather than an atomic state as judged from its size. The conversion width of this state is 0.2 MeV which is extremely narrow. It is also found that Ξ mixing into the ^<5>_<ΛΛ>H ground state is small with 1.0%. For the ^<5>_<ΛΛ>H state, the weak decay to the α+Σ^- final state produces a high mono-energetic Σ^- with branching ratio of 5.5%. Thus the Σ^- with discrete energy would become a clear signature of the forming of the ΛΛ hypernucleus.
理論物理学刊行会の論文
1995-03-31