130 GeV gamma-ray line and enhancement of $h\to\gamma\gamma$ in the Higgs triplet model plus a scalar dark matter

TL;DR

This paper proposes a Higgs triplet model with a scalar dark matter candidate that explains the 130 GeV gamma-ray line, predicts an additional 114 GeV photon peak, and enhances the Higgs to diphoton decay rate, aligning with experimental data.

Contribution

The model introduces a real singlet scalar with a $Z_2$ symmetry into the Higgs triplet framework, explaining the gamma-ray line and Higgs decay enhancements simultaneously.

Findings

The model achieves a gamma-ray line cross section of about 10^{-27} cm^3/s.

Predicts a second photon peak at 114 GeV from $SS\to\gamma Z$.

Light charged scalars enhance LHC Higgs diphoton rate, consistent with ATLAS and CMS.

Abstract

With a discrete $Z_2$ symmetry being imposed, we introduce a real singlet scalar $S$ to the Higgs triplet model with the motivation of explaining the tentative evidence for a spectral feature at $E_\gamma$ = 130 GeV in the Fermi LAT data. The model can naturally satisfy the experimental constraints of the dark matter relic density and direct detection data from Xenon100. The doubly charged and one charged scalars can enhance the annihilation cross section of $SS\to\gamma\gamma$ via the one-loop contributions, and give the negligible contributions to the relic density. $<\sigmav>_{SS\to\gamma\gamma}$ for $m_{S}=130$ GeV can reach $\ord(1)\times10^{-27} cm^3 s^{-1}$ for the small charged scalar masses and the coupling constant of larger than 1. Besides, this model also predict a second photon peak at 114 GeV from the annihilation $SS\to\gamma Z$, and the cross section is approximately 0.76 times that of $SS\to\gamma \gamma$, which is below the upper limit reported by Fermi LAT. Finally, the light charged scalars can enhance LHC diphoton Higgs rate, and make it to be consistent with the experimental data reported by ATLAS and CMS.