A Systematic Study of Hidden Sector Dark Matter: Application to the Gamma-Ray and Antiproton Excesses

TL;DR

This paper systematically explores hidden sector dark matter models, analyzing their annihilation properties, constraints, and potential to explain gamma-ray and antiproton excesses without conflicting with astrophysical observations.

Contribution

It provides a comprehensive classification of hidden sector dark matter models, their annihilation behaviors, and their compatibility with observed cosmic-ray excesses.

Findings

Hidden sector models can explain gamma-ray and antiproton excesses simultaneously.

Many models satisfy relic density and dwarf galaxy constraints.

Lower bounds on portal coupling and scattering cross sections are established.

Abstract

In hidden sector models, dark matter does not directly couple to the particle content of the Standard Model, strongly suppressing rates at direct detection experiments, while still allowing for large signals from annihilation. In this paper, we conduct an extensive study of hidden sector dark matter, covering a wide range of dark matter spins, mediator spins, interaction diagrams, and annihilation final states, in each case determining whether the annihilations are s-wave (thus enabling efficient annihilation in the universe today). We then go on to consider a variety of portal interactions that allow the hidden sector annihilation products to decay into the Standard Model. We broadly classify constraints from relic density requirements and dwarf spheroidal galaxy observations. In the scenario that the hidden sector was in equilibrium with the Standard Model in the early universe, we place a lower bound on the portal coupling, as well as on the dark matter's elastic scattering cross section with nuclei. We apply our hidden sector results to the observed Galactic Center gamma-ray excess and the cosmic-ray antiproton excess. We find that both of these excesses can be simultaneously explained by a variety of hidden sector models, without any tension with constraints from observations of dwarf spheroidal galaxies.