Possible Lightest Ξ Hypernucleus with Modern ΞN Interactions

Experimental evidence exists that the Xi-nucleus interaction is attractive. We search for NN Xi and NNN Xi bound systems on the basis of the AV8 NN potential combined with either a phenomenological Nijmegen Xi N potential or a first principles HAL QCD Xi N potential. The binding energies of the three-body and four-body systems (below the d + Xi and H-3/He-3 + Xi thresholds, respectively) are calculated by a high precision variational approach, the Gaussian expansion method. Although the two Xi N potentials have significantly different isospin (T) and spin (S) dependence, the NNN Xi system with quantum numbers (T = 0, J(pi) = 1(+)) appears to be bound (one deep for Nijmegen and one shallow for HAL QCD) below the H-3/He-3 + Xi threshold. Experimental implications for such a state are discussed.