Updated Collider and Direct Detection Constraints on Dark Matter Models for the Galactic Center Gamma-Ray Excess

TL;DR

This paper reevaluates dark matter models explaining the Galactic Center gamma-ray excess, updating constraints from direct detection experiments and colliders, and identifies viable pseudoscalar models while ruling out many others.

Contribution

It provides a comprehensive update on dark matter model constraints using simplified models, highlighting which scenarios remain viable after recent experimental data.

Findings

Pseudoscalar mediated models remain consistent with constraints.

Dark matter with spin-1 mediators are largely ruled out unless near resonance.

t-channel annihilation models are excluded by combined constraints.

Abstract

Utilizing an exhaustive set of simplified models, we revisit dark matter scenarios potentially capable of generating the observed Galactic Center gamma-ray excess, updating constraints from the LUX and PandaX-II experiments, as well as from the LHC and other colliders. We identify a variety of pseudoscalar mediated models that remain consistent with all constraints. In contrast, dark matter candidates which annihilate through a spin-1 mediator are ruled out by direct detection constraints unless the mass of the mediator is near an annihilation resonance, or the mediator has a purely vector coupling to the dark matter and a purely axial coupling to Standard Model fermions. All scenarios in which the dark matter annihilates through $t$-channel processes are now ruled out by a combination of the constraints from LUX/PandaX-II and the LHC.