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Quark mean-field model for single and double $Λ$ and $Ξ$ hypernuclei

The study of hypernuclei in the quark mean-field model are extended from single-$Λ$ hypernuclei to double-$Λ$ hypernuclei as well as $Ξ$ hypernuclei (double strangeness nuclei), with a broken SU(3) symmetry for the quark confinement potential. The strength of the potential for $u,d$ quarks is constrained by the properties of finite nuclei, while the one for $s$ quark is fixed by the single $Λ$-nucleus potential at the nuclear saturation density, which has a slightly different value. Compared to our previous work, we find that the introduction of such symmetry breaking improves efficiently the description of the single $Λ$ energies for a wide range of mass region, which demonstrates the importance of this effect on the hypernuclei study. Predictions for double-$Λ$ hypernuclei and $Ξ$ hypernuclei are then made, confronting with a few available experiential double-$Λ$ hypernuclei data and other model calculations. The consistency of our results with the available double-$Λ$ hypernucleus is found to be surprisingly good. Also, there is generally a bound state for $Ξ^0$ hypernuclei with both light and heavy core nuclei in our model.