Z' Mediated Dark Matter Models for the Galactic Center Gamma-Ray Excess

TL;DR

This paper explores Z'-mediated dark matter models to explain the Galactic Center gamma-ray excess, identifying scenarios consistent with current constraints and potentially detectable by upcoming experiments.

Contribution

It introduces new Z' mediated dark matter models that fit the gamma-ray excess while satisfying collider and detection constraints, including an anomaly-free axial leptophobic Z' example.

Findings

Several viable Z' models explain the gamma-ray excess.

Many models are testable by near-future direct detection experiments.

The models respect existing collider and detection constraints.

Abstract

With the goal of generating the Galactic Center gamma-ray excess, we revisit models in which the dark matter interacts with the Standard Model through the exchange of a new neutral gauge boson, Z'. We find several scenarios that can account for this signal, while respecting all existing constraints from colliders and direct detection experiments. In such models, the Z' either 1) couples axially to light quarks and is leptophobic, 2) couples dominantly to the third generation, or 3) is near resonance, m_Z' ~ 2 m_DM. We identify an example of an anomaly-free U(1)' that leads to an axial and leptophobic Z'. Many of the models presented here are within the reach of near future direct detection experiments, such as LUX and XENON1T.