Dark Higgs channel for Fermi GeV γ-ray excess

Abstract

Dark Higgs is very generic in dark matter models where DM is stabilized by some spontaneously broken dark gauge symmetries. Motivated by tentative GeV scale γ-ray excess from the galactic center (GC), we investigate a scenario where a pair of dark matter X annihilates into a pair of dark Higgs H2, which subsequently decays into standard model particles through its mixing with SM Higgs boson. Besides the two-body decay of H2, we also include multibody decay channels of the dark Higgs. We find that the best-fit point is around MX 95.0 GeV, MH2 86.7 GeV, 〈συ 〉 4.0 × 10-26cm3/s and gives a p-value 0.40. Implication of this result is described in the context of dark matter models with dark gauge symmetries. Since such a dark Higgs boson is very difficult to produce at colliders, indirect DM detections of cosmic γ-rays could be an important probe of dark sectors, complementary to collider searches.