Λ, Σ, and Ξ hyperons in neutron matter

Hyperon single-particle potentials are calculated in pure neutron matter in the framework of the lowest-order Brueckner theory, using two recent baryon–baryon interactions, the SU6 quark-model potential and the potential derived from the chiral effective field theory. These properties are important for understanding neutron star matter on the basis of underlying baryon–baryon interactions. Because the calculated potential of image is strongly repulsive and that of image is also repulsive, these hyperons are unlikely to appear in neutron star matter. The Λ potential is attractive enough to appear in high neutron matter as has been commonly expected in microscopic calculations. After showing important contributions of three-nucleon forces in neutron matter, analogous repulsive contributions to the Λ potential from the image excitation are estimated by evaluating second-order diagrams.