The double-Λ hypernucleus ΛΛ11Be

The ground-state energy of the double-Λ hypernucleus ΛΛ 11 Be is calculated within the frame-work of the five-body model ααn ΛΛ. The five-body nucleus is described using the Faddeev formalism for the unequal mass clusters involved and the potential harmonics expansion of the corresponding amplitudes. The resulting coupled differential equations depend only on the inter-cluster interactions, ΛΛ, Λ n , Λ α , nα , and αα , which are fairly well known from previous investigations of hypernuclei. The results obtained are in excellent agreement with the recent KEK-E373 experiment as well as with the theoretical results obtained within the Gaussian expansionmethod by Hiyama et al. The ΛΛ nn double hypernucleus is also discussed.