Di-neutrons in neutron matter within Brueckner-Hartree-Fock approach

We investigate the appearance of di-neutron bound states in pure neutron matter within the Brueckner-Hartree-Fock approach at zero temperature. We consider Argonne \(v_{18}\) and Paris bare interactions as well as chiral two- and three-nucleon forces. Self-consistent single-particle potentials are calculated controlling explicitly singularities in the \(g\) matrix associated with bound states. Di-neutrons are loosely bound, with binding energies below \(1\) MeV, but are unambiguously present for Fermi momenta below \(1\) fm\(^{-1}\) for all interactions. Within the same framework we are able to calculate and characterize di-neutron bound states, obtaining mean radii as high as \(\sim 110\) fm. The resulting equations of state and mass-radius relations for pure neutron stars are analyzed including di-neutron contributions.