The interpretation for Galactic Center Excess and Electroweak Phase Transition in the NMSSM

TL;DR

This paper explores how the NMSSM model can simultaneously explain the Galactic Center gamma-ray excess via dark matter annihilation and achieve a strongly first order electroweak phase transition relevant for baryogenesis, highlighting the role of light pseudoscalars and specific parameter choices.

Contribution

It demonstrates that the NMSSM can concurrently account for the gamma-ray excess and electroweak baryogenesis through specific parameter regions involving light pseudoscalars and singlino/Higgsino dark matter.

Findings

Dark matter annihilation near the light pseudoscalar resonance explains the gamma-ray excess.

Small ppa/lambda and negative A_k lead to a strong first order phase transition.

Parameter space with singlino/Higgsino DM is favored for both phenomena.

Abstract

The gamma-ray excess observed by the Fermi-LAT in the Galactic Center can be interpreted by the dark matter annihilation to $b\bar{b}$ via a light pseudoscalar in the NMSSM. It is interesting to note that the corresponding singlet scalar is useful to achieve a strongly first order phase transition required by the electroweak baryogenesis. In this paper, we investigate the possibility that the NMSSM model can simultaneously accommodate these two issues. The phase transition strength can be characterized by the vacua energy gap at zero temperature and be sufficiently enhanced by the tree-level effect in the NMSSM. We find that the annihilation of Singlino/Higgsino DM particles occurring close to the light pseudoscalar resonance is favored by the galactic center excess and the observed DM relic density, and a resulting small $\kappa/\lambda$ and a negative $A_\kappa$ can also lead to a successful strongly first order electroweak phase transition.