Self interacting Sterile Neutrino Dark Matter

Abstract

Its inability to explain the experimentally observed neutrino masses and the identity of dark matter (DM) are among the most widely accepted flaws of the current formulation of the Standard Model (SM). It has been established that the addition of right-handed (sterile) neutrinos to the SM field content might resolve both issues separately. For example, self-interacting right-handed neutrinos pose a viable and consistent DM candidate. Also, through the type-I seesaw mechanism right-handed neutrinos can explain the tiny neutrino masses. However, the scenario in which both issues are resolved simultaneously by adding a single sterile neutrino is excluded due to the different sterile masses needed to solve the separate problems. That being said, we are not restricted to adding only one sterile neutrino.

In this work, it is examined whether a setup with multiple self-interacting sterile neutrinos can be realized, in which, consistently with all available constraining data, both the neutrino masses can be explained and the correct DM abundance can be produced. For a setup including three sterile neutrinos on top of the three active ones, in which DM is produced through a minimal self-interacting sterile neutrino DM mechanism, it is shown using the Casas-Ibarra parametrization that such a consistent region of parameter space is indeed available. On the other hand, for a more involved self-interacting sterile neutrino DM mechanism based on a population transfer in the dark sector, it is established that no such consistent parameter space is at hand when adding up to three sterile neutrinos.