A new three-baryon-force in ΛΛ hypernuclei

We describe a few‐body calculation of ΛΛ5H as well as ΛΛ4H and ΛΛ6He taking account fully coupled‐channel two‐baryon potentials acting among the octet of baryons. The wave function includes not only pnnΛΛ and ppnnΞ− components but also pnnΛΣ0, ppnΛΣ−, pnnΣ0Σ0 and ppnΣ0Σ−. An effective YY potential based on Nijmegen model D is used. We find that the pnnλΣ0 and ppnΛΣ− components play an important role in producing the ΛΛ5H bound state. The present result requires the introduction of a new coupled‐channel three‐body‐force, NΛΛ—NNΞ, if the intermediate pnnλσ0 and ppnΛΣ− states are eliminated from the model space.