Brightening the (130 GeV) Gamma-Ray Line

TL;DR

This paper develops an effective theory to explain the 130 GeV gamma-ray line from dark matter annihilation, linking it to potential signals at the LHC and constraints from existing experiments.

Contribution

It introduces a minimal EFT framework that accounts for the gamma-ray line, explores resonance effects, and connects dark matter properties with collider signals and relic density.

Findings

Resonance or strong coupling enhances the annihilation rate.

Dirac DM or colored charged particles are constrained by XENON100 and WMAP.

The framework can explain the Higgs di-photon excess and interpret the gamma-ray line in NMSSM.

Abstract

The gamma-ray line from dark matter (DM) annihilation is too weak to observe, but its observation will uncover much information, e.g., the DM mass and an nomalously large annihilation rate $\sim0.1$ pb into di-photon. In this work, we construct a minimal effective theory (EFT) incorporating DM and heavier charged particles. A large annihilation rate is obtained from operator coefficients with resonance or strong coupling enhancement. The EFT is stringently constrained by the XENON100 and WMAP data. Without resonance, Dirac DM or colored charged particles are ruled out. It is pointed out that the di-gluon mode may correctly determine the DM relic density. Interestingly, this framework also provides an origin for the Higgs di-photon excess at the LHC\@. We apply the general analysis to the NMSSM, which can elegantly interpret the tentative 130 GeV gamma-ray line. A top-window model is also proposed to explain the gamma-ray line.