Fermi Gamma Ray Line at 130 GeV from Axion-Mediated Dark Matter

TL;DR

This paper proposes a dark matter model with axion mediation that explains the 130 GeV gamma-ray line observed by Fermi LAT, highlighting a resonant annihilation process and exploring detection prospects.

Contribution

It introduces a novel axion-mediated dark matter model with PQ symmetry that accounts for the gamma-ray line and connects to collider and direct detection experiments.

Findings

Resonant dark matter annihilation explains the 130 GeV gamma-ray line.

Axion mediation leads to a p-wave suppressed Higgs portal annihilation.

Model is embedded into the NMSSM with PQ symmetry.

Abstract

We consider a singlet Dirac fermion with Peccei-Quinn(PQ) symmetry as dark matter. A singlet complex scalar is introduced to mediate between dark matter and the SM through Higgs portal interaction and electroweak PQ anomalies. We show that a resonant annihilation of dark matter with axion mediation can explain the monochromatic photon line of the Fermi LAT data at 130 GeV by anomaly interactions while the annihilation cross section with Higgs portal interaction is p-wave suppressed. We discuss the interplay between the direct detection of the fermion dark matter and the collider search of Higgs-like scalars. We also present a ultra-violet completion of the dark matter model into the NMSSM with PQ symmetry.