http://arxiv.org/abs/2001.04946
We consider a Higgs portal (vector) dark matter (DM) model where the hidden scalar, nearly degenerate with DM in mass, mediates the interaction of the secluded DM with Standard Model (SM) due to its mixing with the SM Higgs. We find that the parameter region $m_X\in[60, 132] \text{GeV}$ can provide a good fit to the Fermi Galactic center gamma-ray excess spectrum, appearing a prominent gamma-ray line with the energy $\in [30, 66]$ GeV. The best fit gives $m_X\simeq m_S \simeq 86$ GeV with a $p$-value$\, =0.42$, so that the resultant gamma-ray line, arising from the decay of the scalar mediator into $\gamma\gamma$, peaks at 43 GeV. We derive constraints on the annihilation cross section from the Fermi-LAT gamma-ray line search, gamma-ray observations of the Fermi-LAT dwarf spheroidal galaxies, and Planck cosmic microwave background measurement. For the secluded vector DM model, the parameter space constrained by the current XENON1T and future LUX-ZEPLIN is shown. Finally, for the mixing angle between the Higgs sectors, we discuss its lower bound, which is required by the big bang nucleosynthesis constraint and relevant to the hidden sector decoupling temperature.
K. Yang
Wed, 15 Jan 20
53/66
Comments: 36, pages, 8 figures, 1 table