Viable secret neutrino interactions with ultralight dark matter

摘要

Several anomalies in neutrino oscillation experiments point to the existence of a similar to 1 eV sterile neutrino vs mixing with I), at the level of U-e4 congruent to 0.1, but such a neutrino is strongly disfavored by constraints on additional light degrees of freedom (delta N-eff) and total neutrino mass (Sigma(nu), m(nu)) from cosmology. "Secret neutrino interactions" that have been invoked to suppress the cosmological production of nu s typically falter, but recently it was pointed out that nu s could get a large mass in the early universe by coupling to ultralight dark matter phi, which can robustly suppress its production. The model has essentially two free parameters: m(phi), and m(s,0), the mass of the sterile neutrino at early times, enhanced by its coupling to 0. I determine the parameter regions allowed by limits on delta N-eff and E mi, from the cosmic microwave background and big bang nucleosynthesis, using a simplified yet accurate treatment of neutrino oscillations in the early universe. This mechanism could have an important impact on laboratory experiments that suggest oscillations with sterile neutrinos. (C) 2020 The Author. Published by Elsevier B.V.