Ξ^- t quasibound state instead of ΛΛnn bound state

The coupled Λ Λ nn-Ξ^- pnn system was studied to investigate whether the inclusion of channel coupling is able to bind the Λ Λ nn-Ξ^- system. We use a separable potential three-body model of the coupled Λ Λ nn-Ξ^- pnn system and a variational four-body calculation with realistic interactions. Our results exclude the possibility of a Λ Λ nn bound state by a large margin. Instead, we found a Ξ^- t quasibound state above the Λ Λ nn threshold.