Sterile neutrinos with pseudoscalar self-interactions and cosmology

Sterile neutrinos in the electronvolt mass range are hinted at by a number of terrestrial neutrino experiments. However, such neutrinos are highly incompatible with data from the cosmic microwave background and large scale structure. This paper discusses how charging sterile neutrinos under a new pseudoscalar interaction can reconcile eV sterile neutrinos with cosmological data. We show that this model provides a fit to all available data which is way better than the standard Λ cold dark matter model with one additional fully thermalized sterile neutrino. In particular it also prefers a value of the Hubble parameter much closer to the locally measured value.