Two-meson exchange hyperonic three-body forces and consequences for neutron stars

We construct two-meson exchange three-baryon potentials between two nucleons and one hyperon (NNY) consistent with the two body nucleon-hyperon (NY) J04 potential of the Jülich group. In particular, we focus on the NNΛ and NNΣ− forces since Λ and Σ− are the first hyperons expected to appear in microscopic calculations of neutron star matter. Brueckner-Hartree-Fock calculations of the hyperonic matter are then performed including the effect of these three-body forces. Our results show that at high densities the total contribution of the NNY force is repulsive making the resulting equation of state stiffer, as required from neutron star mass observations.