ΛΣ⁻ PAIRING IN “BUBBLE FERMI SHELL” SCHEME

In neutron star cores, superfluid state of hyperons such as lambda (Λ) and sigma-minus (Σ⁻) has been shown to realize by a realistic approach. This result importantly supports the idea of nonstandard fast “hyperon cooling” scenario to explain colder class neutron stars observed. However, a less attractive ΛΛ interaction suggested by a double Λ hypernucleus (; “NAGARA” event) leads to a disappearance of Λ superfluidity and thereby the breaking down of the scenario. In this connection, the revival of “Λ superfluidity” due to the ΛΣ⁻ pairing, instead of ΛΛ one, is discussed in a new scheme of “bubble Fermi shell” hypothesis where the matching of two different Fermi surfaces is forced.