Sterile neutrino dark matter production in presence of non-standard neutrino self-interactions: an EFT approach

TL;DR

This paper explores how effective self-interactions among active neutrinos influence the production, parameter space, and observational signatures of keV-scale sterile neutrino dark matter, with implications for upcoming experiments and structure formation.

Contribution

It introduces an EFT framework to study active neutrino self-interactions and their impact on sterile neutrino dark matter production and detectability, extending previous models.

Findings

Self-interactions shift the sterile neutrino parameter space relevant for experiments.

Phase 3 of HUNTER can probe larger regions of parameter space with self-interactions.

Self-interactions affect the free-streaming length, influencing structure formation constraints.

Abstract

Sterile neutrinos with keV-scale masses are popular candidates for warm dark matter. In the most straightforward case they are produced via oscillations with active neutrinos. We introduce effective self-interactions of active neutrinos and investigate the effect on the parameter space of sterile neutrino mass and mixing. Our focus is on mixing with electron neutrinos, which is subject to constraints from several upcoming or running experiments like TRISTAN, ECHo, BeEST and HUNTER. Depending on the size of the self-interaction, the parameter space moves closer to, or further away from, the one testable by those future experiments. In particular, we show that phase 3 of the HUNTER experiment would test a larger amount of parameter space in the presence of self-interactions than without them. We also investigate the effect of the self-interactions on the free-streaming length of the sterile neutrino dark matter, which is important for structure formation observables.