Towards a Supersymmetric Description of the Fermi Galactic Center Excess

TL;DR

This paper explores a supersymmetric model to explain the Fermi galactic gamma-ray excess, identifying a specific parameter space with a singlino dark matter candidate and a light CP-odd Higgs, and discusses the challenges in detecting such signals.

Contribution

It demonstrates that a supersymmetric explanation for the FGCE is feasible within the general NMSSM with specific parameters, highlighting the importance of a light CP-odd Higgs and singlino dark matter.

Findings

A particular NMSSM parameter space fits the FGCE data.

Detection of the light CP-odd Higgs at the LHC is challenging.

Indirect detection remains the most promising method for probing this scenario.

Abstract

We attempt to build a model that describes the {\it Fermi} galactic gamma-ray excess (FGCE) within a UV-complete Supersymmetric framework; we find this to be highly non-trivial. At the very least a successful Supersymmetric explanation must have several important ingredients in order to fit the data and satisfy other theoretical and experimental constraints. Under the assumption that a {\it single} annihilation mediator is responsible for both the observed relic density as well as the FGCE, we show that the requirements are not easily satisfied in many TeV-scale SUSY models, but can be met with some model building effort in the general NMSSM with $\sim 10$ parameters beyond the MSSM. We find that the data selects a particular region of the parameter space with a mostly singlino lightest Supersymmetric particle and a relatively light CP-odd Higgs boson that acts as the mediator for dark matter annihilation. We study the predictions for various observables within this parameter space, and find that searches for this light CP-odd state at the LHC, as well as searches for the direct detection of dark matter, are likely to be quite challenging. It is possible that a signature could be observed in the flavor sector; however, indirect detection remains the best probe of this scenario.