Gamma rays from Dark Matter Annihilation in Three-loop Radiative Neutrino Mass Generation Models

TL;DR

This paper investigates gamma ray signals from dark matter annihilation in three-loop radiative neutrino mass models with large electroweak multiplets, showing current and future telescopes can constrain or detect these models.

Contribution

It demonstrates the impact of electroweak multiplet size on dark matter annihilation signals and the potential of CTA to probe these models.

Findings

Larger electroweak multiplets enhance DM annihilation signals.

Current IACTs like H.E.S.S. can already constrain some models.

Future CTA observations will significantly improve sensitivity.

Abstract

We present the Sommerfeld enhanced Dark Matter (DM) annihilation into gamma ray for a class of three-loop radiative neutrino mass models with large electroweak multiplets where the DM mass is in O(TeV) range. We show that in this model, the DM annihilation rate becomes more prominent for larger multiplets and it is already within the reach of currently operating Imaging Atmospheric Cherenkov telescopes (IACTs), High Energy Stereoscopic System (H.E.S.S.). Furthermore, Cherenkov Telescope Array (CTA), which will begin operating in 2030, will improve this sensitivity by a factor of $\mathcal{O}{(10)}$ and may exclude a large portion of parameter space of this radiative neutrino mass model with larger electroweak multiplet. This implies that the only viable option is the model with lowest electroweak multiplets i.e. singlets of $SU(2)_{L}$ where the DM annihilation rate is not Sommerfeld enhanced and hence it is not yet constrained by the indirect detection limits from H.E.S.S. or future CTA.