Effective Λ−Λ interaction energy in HΛΛ6e

In this paper, the double-Λ hypernuclei, HΛΛ6e, HΛΛ5e and HΛΛ5e have been theoretically investigated to determine effective Λ-Λ interaction energies in double-Λ hypernuclei which is closely related to hyperon superfluidity in neutron stars. These double-Λ hypernuclei were considered as three-body cluster model; Λ-Λ-core nucleus. We constructed the free-space single-channel Λ-Λ interaction from Shinmura's multi-channel S=-2 potentials which are phase shift equivalent to Nijmegen soft core potentials. The interaction strength and range parameter are fitted with the most updated experimental data of Nagara event from E373 experiment. By using NSC97e potential, the effective Λ-Λ interaction energies are found to be 0.67 MeV, 0.88 MeV and 0.64 MeV for HΛΛ6e, HΛΛ5e and HΛΛ5e respectively. The medium effects are not negligible in these double-Λ hypernuclei.