The Sommerfeld Enhancement in the Scotogenic Model with Large Electroweak Scalar Multiplets

TL;DR

This paper studies how the Sommerfeld enhancement affects dark matter annihilation in a model with large electroweak multiplets, showing larger multiplets have significantly increased annihilation signals that could be constrained by gamma-ray observations.

Contribution

It extends the analysis of Sommerfeld enhancement to large electroweak multiplets in the scotogenic model, highlighting their increased annihilation cross sections and observational implications.

Findings

Larger multiplets exhibit sizable Sommerfeld enhancement.

Enhanced annihilation cross sections are more constrained by gamma-ray observations.

Potential for future detection with CTA.

Abstract

We investigate the Sommerfeld enhancement (SE) in the generalized scotogenic model with large electroweak multiplets. We focus on scalar dark matter (DM) candidate of the model and compare DM annihilation cross sections to $WW$, $ZZ$, $\gamma\gamma$ and $\gamma Z$ at present day in the galactic halo for scalar doublet and its immediate generalization, the quartet in their respective viable regions of parameter space. We find that larger multiplet has sizable Sommerfeld enhanced annihilation cross section compared to the doublet and because of that it is more likely to be constrained by the current H.E.S.S. results and future CTA sensitivity limits.