Sterile neutrinos with pseudoscalar self-interactions and cosmology

TL;DR

This paper proposes a pseudoscalar self-interaction model for sterile neutrinos that resolves conflicts between terrestrial experiments and cosmological observations, improving data fit and aligning Hubble parameter estimates.

Contribution

It introduces a new pseudoscalar interaction framework that allows eV-scale sterile neutrinos to be compatible with cosmological data, outperforming standard models.

Findings

Model fits all available data better than ΛCDM with a fully thermalized sterile neutrino.

The model prefers a Hubble parameter value closer to local measurements.

Reconciles terrestrial neutrino hints with cosmological constraints.

Abstract

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 terrestrial neutrino data. We show that this model can reconcile eV sterile neutrinos in cosmology, providing a fit to all available data which is way better than the standard $\Lambda$CDM 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.