Theoretical evidence for di-molecular rotational behaviour in the hypernuclei ⁸ _∑ Li and ⁸ _∑ Be

Abstract

We have performed microscopic cluster studies of light∑-hypernuclei based on effective nucleon-nucleon and two different sigma-nucleon interactions. Our calculation confirms a bound 0⁺ state in ⁴ _∑ He and ⁴ _∑ H, but reveals no evidence for levels in other partial waves. We have investigated the ⁸ _∑ Li and ⁸ _∑ Be hypernuclei in a microscopic 3-cluster approach. For both hypernuclei, our calculation shows that the lowest levels in the partial wavesJ=0–4 are bound or quasibound states of collective nature and show a strong α ⁴ _∑ H and α + ⁴ _∑ He clustering. These levels form a sequence of states which can be well interpreted as arising from a rotatingα+ ⁴ _∑ H orα+ ⁴ _∑ He di-molecule. Our results are compared to those of similar studies for lightΛ-hypernuclei which do not show evidence for this kind of collective degrees of freedom.