Onset of hyperon formation in neutron star matter from Brueckner theory

We determine fully self-consistent single-particle potentials and chemical potentials of nucleons and hyperons in asymmetric nuclear matter, using an extended Brueckner-Hartree-Fock formalism. We carefully analyze the onset of ${\Sigma }^{-}$ and $\Lambda$ formation in $\beta$ stable and charge neutral matter. The role played by the three-body nucleon interaction is widely discussed. The results indicate that formation of hyperons sets in at about (2–3) times normal nuclear matter density, for all the different nucleonic equations of state that are considered.