3-6 March 2020
Faculty of Science, University of Toyama
Asia/Tokyo timezone

MeV-scale reheating temperature and cosmological constraints on sterile neutrinos

5 Mar 2020, 14:20
A238 (Faculty of Science, University of Toyama)


Faculty of Science, University of Toyama

3190 Gofuku, Toyama 930-8555, Japan


Takuya Hasegawa (KEK)


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.

Primary author

Takuya Hasegawa (KEK)


Nagisa Hiroshima (RIKEN) Kazunori Kohri (KEK) Rasmus Sloth Hansen (Conseil Europeen Recherche Nucl. (CERN)) Thomas Tram Bulow (Institute of Physics and Astronomy-Aarhus University) Steen Hannestad (Aarhus University)

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