Galactic Center gamma-ray excess from two-Higgs-doublet-portal dark matter

TL;DR

This paper proposes a two-Higgs-doublet model with a scalar dark matter candidate that explains the gamma-ray excess from the Galactic Center through dark matter annihilation into b-quarks, consistent with current constraints.

Contribution

It introduces a minimal extension of the type-II two-Higgs-doublet model with a scalar dark matter particle that accounts for the gamma-ray excess and satisfies phenomenological constraints.

Findings

Identifies parameter space fitting gamma-ray excess

Predicts most of the parameter space is testable by future experiments

Demonstrates compatibility with relic density and null direct detection results

Abstract

We consider a simple extension of the type-II two-Higgs-doublet model by introducing a real scalar as a candidate for dark matter in the present Universe. The main annihilation mode of the dark matter particle with a mass of around $31-40$ GeV is into a $b\bar{b}$ pair, and this annihilation mode suitably explains the observed excess of the gamma-ray flux from the Galactic Center. We identify the parameter region of the model that can fit the gamma-ray excess and satisfy phenomenological constraints, such as the observed dark matter relic density and the null results of direct dark matter search experiments. Most of the parameter region is found to be within the search reach of future direct dark matter detection experiments.