Galactic Centre GeV Photons from Dark Technicolor

TL;DR

This paper proposes a classically scale-invariant dark sector model with a confining gauge group, explaining the galactic centre gamma ray excess via dark matter decays, and explores relic density mechanisms including freeze-in.

Contribution

It introduces a novel scale-invariant dark sector model coupled through the Higgs portal, analyzing its ability to explain gamma ray excess and relic density.

Findings

The model can account for the gamma ray excess through dark matter decays to b-quarks.

Relic density can be achieved via freeze-in without fine-tuning.

A wide parameter space satisfies both relic density and gamma ray observations.

Abstract

We present a classically scale-invariant model with a confining dark sector, which is coupled to the Standard Model through the Higgs portal. The galactic centre gamma ray excess can be explained in this model by collision-induced dark matter decays to b-quarks. We discuss the possibility to obtain the dark matter relic density through thermal freeze-out, which however requires excessive fine-tuning. We then instead focus on a freeze-in scenario and perform detailed calculations and a parameter scan. We find that the observed relic density and the gamma ray excess can be explained by a wide range of parameters in this model.