Forty years of ΛΛ hypernuclei

Recent experiments on production of ΛΛ Hypernuclei have provoked renewed interest in extracting the ΛΛ interaction from the few events identified since the inception of this field forty years ago. Few-body calculations relating to this issue are reviewed, particularly with respect to the possibility that A = 4 marks the onset of ΛΛ binding to nuclei. The Nijmegen soft-core model potentials NSC97 qualitatively agree with the strength of the ΛΛ interaction deduced from the newly determined binding energy of _ΛΛ⁶He. Applying the extended NSC97 model to stranger nuclear systems suggests that A = 6 marks the onset of Ξ binding, with a particle stable _ΛΞ⁶He, and that strange hadronic matter is robustly bound.