SUSY implications from WIMP annihilation into scalars at the Galactic Center

An excess in γ rays emanating from the Galactic Center has recently been observed in the Fermi-LAT data. This signal can be interpreted as resulting from weakly interacting massive particle annihilation, with the spectrum well fit by dark matter annihilating dominantly into either bottom-quark or Higgs pairs. Supersymmetric models provide a well-motivated framework to study the implications of this signal in these channels. With a neutralino dark matter candidate, the γ-ray excess cannot be easily accommodated in the minimal supersymmetric model, which in any case requires tuning below the percent level to explain the observed Higgs mass. Instead we are naturally led to consider the next-to-minimal model with a singlet superfield. This not only allows for the annihilation channel into bottom-quark pairs to be implemented but also provides new possibilities for annihilation into Higgs-pseudoscalar pairs. We show that the fit to the γ-ray excess for the Higgs-pseudoscalar channel can be just as good as for annihilation into bottom-quark pairs. Moreover, in the parameter range of interest, the next-to-minimal supersymmetric model solves the μ problem and can explain the 125 GeV Higgs mass with improved naturalness. We also consider an extension by adding a right-handed neutrino superfield with the right-handed sneutrino acting as a dark matter candidate. Interestingly, this allows for the annihilation into pseudoscalar pairs which also provide a good fit to the γ-ray excess. Furthermore, in the case of a neutralino lightest supersymmetric particle, the late decay of a sneutrino next-to-lightest supersymmetric particle can nonthermally produce the observed relic abundance. Finally, the weakly interacting massive particle annihilation into scalar pairs allows for the possibility of detecting the Higgs or pseudoscalar decay into two photons, providing a smoking-gun signal of the model.