Indirect Detection Imprint of a CP Violating Dark Sector

Understand

We introduce a simple scenario involving fermionic dark matter ($\chi$) and singlet scalar mediators that may account for the Galactic Center GeV $\gamma$-ray excess while satisfying present direct detection constraints.

• CP-violation in the scalar potential leads to 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 $\chi{\bar\chi}$ annihilation into di-scalar states, followed by decays into four fermion final states.
• The observed $\gamma$-ray spectrum can be fitted while respecting present direct detection bounds and Higgs boson properties for $m_{\chi} = 60 \sim 80 $ GeV, and $m_{h_3} \sim m_{\chi}$.