Self-interacting sterile neutrino dark matter: The heavy-mediator case

Abstract

For active-sterile mixing to be responsible for the full relic abundance of dark matter additional new physics is needed beyond the keV-scale sterile neutrino itself. The extra ingredient we consider here is the presence of self-interactions among the sterile neutrinos. We examine whether active-tosterile conversion is amplified enough in this scenario that the observed abundance of dark matter can be obtained with a subconstraint mixing angle. This turns out never to be the case in the region we explore: either self-interactions have too small an impact and cannot escape bounds on the mass and mixing angle, or they have too great an impact and cause dark matter to be overproduced. The sharp transition from marginal to excessive effectiveness occurs because a resonance criterion is met in the effective in-medium mixing angle. Once the system goes resonant the game is as good as over, as nonlinearity in the Boltzmann equation leads to runaway production of sterile neutrinos, beginning at a plasma temperature of a few hundred MeV and typically ending at a few tens of MeV. The scenario is therefore ruled out largely by its own dynamics. In this study we focus exclusively on mediators heavier than ∼ 1 GeV; future work will extend the analysis to lighter mediators, allowing for contact to be made with the kinds of scenarios motivated by issues of small-scale structure.

Dodelson-Widrow Mechanism in the Presence of Self-Interacting Neutrinos

“…These are associated to slightly different phenomenological and model-building challenges. We also note that the impact of new interactions involving the sterile neutrino to the dynamics of these light fermions in the early universe -different from what we are discussing here -have been explored in [23,[31][32][33][34][35].…”

Neutrino Flavor Conversions in High-Density Astrophysical and Cosmological Environments

“…Anyway, also this scenario is strongly constrained [78,[91][92][93][94] and the 7 keV sterile neutrino interpretation of the observed 3.5 keV line is not favoured [95,96]. As recently speculated by different groups, the allowed mass and mixing parameter space could be extended in presence of new interactions among only active neutrinos [97,98] or among only sterile species [99] which imply extra terms in the interaction rate Γ (eq. ( 9)).…”

New Physics Searches at Kaon and Hyperon Factories

“…8 Similar interactions/models have been used to explain the XENON1T electron excess [226]. 8 The goal of the MiniBooNE experiment was to address the 3.3σ LSND anomaly in electron-like events seen in the νe The light mediator would also induce neutrino self-interactions that can potentially explain the Hubble tension [227][228][229] or allow for sterile neutrino dark matter [230,231]. The mediator that is light enough would be produced in rare kaon decays, K + → µ + νX, via bremsstrahlung of X off the final state neutrino, so that rare kaon decays offer a unique opportunity to test for such neutrino interactions (similar signatures where X is radiated off the charged lepton are discussed in Section 2.5).…”