Nuclear symmetry energy in the presence of hyperons in the non-relativistic Thomas-Fermi approximation

We generalize the finite-range momentum- and density-dependent Seyler-Blanc hard nucleon-nucleon effective interaction to the case of interaction betwe en two baryons. This effective interaction is then used to describe dense h adronic matter relevant to neutron stars in the nonrelativistic Thomas-Ferm i approach. We investigate the behaviour of nuclear symmetry energy in dens e nuclear and hyperon matter relevant to neutron stars. It is found that th e nuclear symmetry energy always increases with density in hyperon matter u nlike the situation in nuclear matter This rising characteristic of the sym metry energy in the presence of hyperons may have significant implications on the mass-radius relationship and the cooling properties of neutron stars . We have also noted that with the appearance of hyperons, the equation of state calculated in this model remains causal at high density.