Study of Light Λ- and ΛΛ-Hypernuclei with the Stochastic Variational Method and Effective ΛN Potentials

ΛΛHe are calculated to be strongly overbound compared to experiment. In relation to this well-known anomaly, we examine the effect of the quark substructure of N and Λ on their binding energies. The effect is negligible if the baryon size in which the three quarks are confined is smaller than 0.6 fm, but it becomes appreciable, particularly in 6 ΛΛHe, if the size is taken to be as large as 0.7 fm. We discuss the extent to which the nucleon subsystem in the hypernuclei changes by the addition of Λ particles. The charge symmetry breaking of the ΛN potential is phenomenologically determined and concluded to be weakly spin dependent.