Strangeness production in neutron stars

Abstract

Production of strange quarks in neutron stars is investigated in this work. Three cases, one in which the energy and neutrinos produced in the strangeness production reactions are retained in the reaction region, second in which the neutrinos are allowed to escape the reaction region but the energy is retained and the third in which both the energy and neutrinos escape the reaction region are considered. It is shown that the nonleptonic weak process dominates strange quark production while semileptonic weak processes, which produce neutrinos, lead to the cooling if the neutrinos escape the reaction region. It is found that the time required for the saturation of the strangeness fraction is between $10^{-7}$ and $10^{-5}$ sec, with the shorter time corresponding to the first two cases. About 0.2 neutrinos/baryon are emitted during the process in the first two cases where as the neutrino emission is somewhat suppressed in the last case. The average energy of the neutrinos produced in all the three cases is found to be several hundred $MeV$. We also find that a large amount of energy is released during the strangeness production in the first two cases and this leads to the heating of the reaction region. Implications of the neutrino production are investigated.