Abstract
We show that the GeV scale γ-ray excess from the direction of the Galactic Center can be naturally explained by the pair annihilation of Abelian vector dark matter (VDM) into a pair of dark Higgs bosons (VV→ ϕ ϕ), followed by the subsequent decay of ϕ into bb̄ or τ τ̄ . All the processes are described by a renormalizable VDM model with the Higgs portal, which is naturally flavor-dependent. Some parameter space of this scenario can be tested at the near future direct dark matter search experiments such as LUX and XENON1T.
Highlights
Note that the structure of above scenarios can be realized when DM is charged under a dark gauge symmetry which is broken to, for example, a discrete Z2 or Z3 symmetry
We revisit Singlet vector dark matter (SVDM) scenario with Higgs portal in the context of the the γ-ray excess from the Galactic Center, and show that the SVDM model can naturally explain it, while satisfying all of known constraints coming from CMB, Fermi-LAT γ-ray search and LHC experiments
We show that the parameter space relevant for the γ-ray excess can be probed by the near future direct dark matter search experiment, for example LUX and XENON1T
Summary
Let us consider a Abelian vector boson dark matter 4, Xμ, which is assumed to be a gauge boson associated with Abelian dark gauge symmetry U (1)X. The simplest model will be defined with a complex scalar dark Higgs field Φ only, and no other extra fields. The VEV of Φ breaks U (1)X spontaneously and generate the mass for Xμ through the standard Higgs mechanism Assuming that the U (1)X -charged complex scalar Φ develops a nonzero VEV, vΦ, and breaks U (1)X spontaneously, we would have. The hidden sector Higgs field (or dark Higgs field) φ(x) will mix with the SM Higgs field h(x) through the Higgs portal λΦH term, resulting in two neutral Higgs-like scalar bosons. In the small mixing limit which is of our interest, the mass eigenstates are approximated to the interaction eigenstates as (H2, H1) ≈ (h, φ), and we use (h, φ) to represent quantities associated with (H2, H1) on
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