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 the FERMI observation of $\sim$GeV scale $γ$-ray excess from the galactic center (GC), we investigate a scenario that a pair of dark matter $X$ annihilates into a pair of dark Higgs $H_2$, which subsequently decays into standard model particles through its mixing with SM Higgs boson. Besides the two-body decay of $H_2$, we also include multibody decay channels of the dark Higgs. We find that the best-fit point is around $M_X\simeq 95.0$GeV, $M_{H_2}\simeq 86.7$GeV, $\langle σv\rangle\simeq 4.0\times 10^{-26}\textrm{cm}^3\textrm{/s}$ and gives a p-value $\simeq 0.40$. 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.