NMSSM Interpretation of the Galactic Center Excess

Abstract

We explore models for the GeV Galactic Center Excess (GCE) observed by the Fermi Telescope, focusing on χχ→ƒƒ(bar) annihilation processes in the Z3 NMSSM. We begin by examining the requirements for a simplified model (parametrized by the couplings and masses of dark matter (DM) and mediator particles) to reproduce the GCE via χχ→ƒƒ^bar, while simultaneously thermally producing the observed relic abundance. We apply the results of our simplified model to the Z_3 NMSSM for Singlino/Higgsino~(S/H) or Bino/Higgsino~(B/H) DM. In the case of S/H DM, we find that the DM must be be very close to a pseudoscalar resonance to be viable, and large tan β and positive values of μ are preferred for evading direct detection constraints while simultaneously obtaining the observed Higgs mass. In the case of B/H DM, by contrast, the situation is much less tuned: annihilation generally occurs off-resonance, and for large tan β direct detection constraints are easily satisfied by choosing μ sufficiently large and negative. The B/H model generally has a light, largely MSSM-like pseudoscalar with no accompanying charged Higgs, which could be searched for at the LHC.