Prediction of exotic hyperon halos in neutron-rich Zr hypernuclei

We study the single- and double-Λ hypernuclei in Zr isotopes with the Hartree–Fock–Bogoliubov model and Skyrme-type nucleon–nucleon, Λ–nucleon, and Λ–Λ interactions. We found two peculiar features of the Λ hyperon halo phenomena that have never been found in nuclei without the strangeness degree of freedom. One is the d-wave halo, and the other is a bunch of three halo orbits just below the Λ hyperon threshold in $^{137}_\Lambda$Zr and also in $^{138}_{\Lambda \Lambda }$Zr. We name these exotic halo phenomena giant hyperon halos in hypernuclei whose core nucleus 136Zr was predicted to have a “giant neutron halo.” The interaction between Λ hyperons and the neutrons is responsible for inducing giant hyperon halo phenomena in the single- and double-Λ nuclei $^{137}_\Lambda$Zr and $^{138}_{\Lambda \Lambda }$Zr.