Indirect detection imprint of a CP violating dark sector
We introduce a simple scenario involving fermionic dark matter (χ) and singlet scalar mediators that may account for the Galactic center GeV γ-ray excess while satisfying present direct detection constraints. CP violation in the scalar potential leads to a mixing between the Standard Model Higgs boson and the scalar singlet, resulting in three scalars, h_(1,2,3), of indefinite CP-transformation properties. This mixing enables s-wave χχ¯ annihilation into discalar states, followed by decays into four-fermion final states. The observed γ-ray spectrum can be fitted while respecting present direct detection bounds and Higgs boson properties for m_χ=60∼80 GeV, and m_(h_3)) ∼ m_χ. Searches for the Higgs exotic decay channel h_1 → h_3h_3 at the 14 TeV LHC should be able to further probe the parameter region favored by the γ-ray excess.
Additional Information© 2016 American Physical Society. (Received 1 March 2016; published 31 May 2016) We thank Kevork Abazajian, Grigory Ovanesyan, and Peter Winslow for the helpful discussions. J. H. Y. also thanks Wei Xue and Asher Berlin for the useful conversation during CETUP in South Dakota. This work was supported by U.S. Department of Energy Contract No. DE-SC0011095.
Published - PhysRevD.93.095025.pdf