The Galactic center excess is explained in the framework of the Next-to-Minimal Supersymmetric Standard Model with a $Z_3$ discrete symmetry. We show that a resonant $CP$-odd Higgs boson with mass twice that of the Dark Matter (DM) candidate is favored. Meanwhile, the DM candidate is required to have relatively large coupling with the $Z$ boson through its Higgsino component in order to obtain correct DM relic density. Its LHC discovery potential via four signatures is discussed in detail. We find that the most sensitive signals are provided by the Higgsino-like chargino and neutralino pair production with their subsequent decays into $W$ bosons, $Z$ bosons, and DM. The majority of the relevant parameter space can be probed at the Large Hadron Collider with a center-of-mass energy of 14 TeV and an integrated luminosity $1000{\mathrm{fb}}^{-1}$.

• Received 31 December 2014

DOI:https://doi.org/10.1103/PhysRevD.91.095003