Sterile Neutrino Shape-shifting Caused by Dark Matter

Understand

Light sterile neutrinos with a mass of $\sim 1$ eV continue to be interesting due to multiple hints from terrestrial experiments.

• This simple hypothesis suffers from strong astrophysical constraints, in particular from the early universe as well as solar neutrinos.
• We develop a cosmologically viable proposal consistent with the terrestrial hints, as well as solar constraints, by sourcing the sterile neutrino's mass from ordinary matter via an ultralight scalar $\phi$ which can also be the dark matter.
• In this scenario, the experimentally implied $\sim 1$ eV sterile neutrino mass is a local value and changes throughout spacetime.