Speaker
Description
In this study, we investigate a possible existence of sterile neutrinos with a various range of masses in terms of cosmology assuming an MeV-scale reheating temperature. By numerically calculating sterile neutrino production through flavor mixing, we find that the existence of light sterile neutrinos inferred from short-baseline neutrino oscillation experiments becomes consistent with observational results of big-bang nucleosynthesis (BBN) for the reheating temperature of O(1) MeV if the scalar particle responsible for the reheating fully decay into radiations. In contrast, if the scalar particle mainly decays into hadrons, the BBN bound becomes more stringent, and the allowed region for the light sterile neutrino is completely excluded, depending on the mass of the scalar particle and the hadronic branching ratio of the decay.
