ar X iv : 1 71 0 . 08 03 6 v 1 [ nu cl - t h ] 2 2 O ct 2 01 7 Binding , bonding and charge symmetry breaking in Λ - hypernuclei

Recent experiments have presented more accurate data on the ΛΛ-binding energies of a few ΛΛhypernuclei. This is important as the ΛΛbond energies (∆BΛΛ) of double-Λ hypernuclei provide a measure of the in-medium strength of the ΛΛ interaction. A mass formula, optimized with the newly available ΛΛ binding energy data, is used to estimate the binding energy and bond energy over a wide range of hypernuclei. The ∆BΛΛ values calculated with this mass formula are in good agreement with the experimental data, predictions of the quark mean-field (QMF) model and the relativistic mean-field (RMF) model as well. The ΛΛ-bond energy is found to diminish with neutron numbers, approaching zero near the neutron-drip line. In this formalism, the calculated binding energy difference in mirror nuclei arises from the Coulomb contributions and can be utilized to extract the Coulomb-corrected charge symmetry breaking effect.