Opening up New Parameter Space for Sterile Neutrino Dark Matter

TL;DR

This paper introduces a new mechanism for sterile neutrino dark matter production via scalar-mediated interactions, expanding viable parameter space and enabling detection through future X-ray and gamma-ray observations.

Contribution

It proposes a novel scalar-mediated interaction channel for sterile neutrino production, independent of mixing angles, addressing previous astrophysical constraints.

Findings

New production channels enable sterile neutrino DM at small mixing angles.

Expands parameter space for sterile neutrino viability.

Potential for future detection via X-ray and gamma-ray observations.

Abstract

Sterile neutrinos are compelling dark matter (DM) candidates, yet the minimal production mechanism solely based on active ($\nu_a$)-sterile ($\nu_s$) oscillations is excluded by astrophysical observations. Non-standard self-interactions in either active ($\nu_a-\nu_a$) or sterile ($\nu_s-\nu_s$) sector are known to alter the sterile neutrino DM production in the early Universe, which could alleviate the tension with astrophysical constraints to some extent. Here we propose a novel solution where scalar-mediated non-standard interactions between active and sterile neutrinos ($\nu_a-\nu_s$) generate new production channels for $\nu_s$, independent of the active-sterile mixing and without the need for any fine-tuned resonance or primordial lepton asymmetry. This framework enables efficient sterile neutrino DM production even at vanishingly small mixing angles and opens up new viable regions of parameter space that can be tested with future $X$-ray and gamma-ray observations.