Three-, four- and five-body calculations of s-shell hypernuclei with realistic interactions

Abstract

We perform stochastic variational calculations for s-shell hypernuclear systems, Λ3H, Λ4H, Λ4H* and Λ5He with realistic NN and YN interactions including explicitly Σ degrees of freedom. The G3RS potential is used for the NN interaction. We test four sets of the YN interactions; D2, SC97e(S), SC97f(S) and SC89(S). The Λ-separation energies and the probabilities in Σ-channel are successfully calculated for all the s-shell hypernuclei. The bound state solution of Λ5He is the first result obtained by the five-body calculation with realistic interactions. The largest probability of Σ-component is found in the ground state of four-body system. With change of the YN interaction from D2 to SC97e(S), SC97f(S) and SC89(S), the Σ-probabilities increase except for the case of Λ4H using the D2. It is found that the BΛ(Λ3H) grows with increasing PΣ while BΛ(Λ4H*) and BΛ(Λ5He) decrease. The present result implies that the Λ−Σ coupling plays an important role in understanding the binding mechanism of s-shell hypernuclei. The results obtained by using the SC97e(S) are in relatively good agreement with experimental data. The most important contribution in the case of the SC97e(S) is the strong spin-triplet tensor Λ−Σ coupling. The D2 is also a reasonable phenomenological interaction which reproduces well the experimental binding energies.