Dark Matter Self-Interactions and Light Force Carriers

TL;DR

This paper explores how light force carriers mediating dark matter interactions can explain cosmic ray signals and discusses the constraints on such models from astrophysical observations of dark matter self-scattering.

Contribution

It analyzes the implications of light mediators on dark matter self-interactions and derives observational constraints on their properties.

Findings

Light mediators can enhance dark matter annihilation cross sections.

Astrophysical bounds limit the mass and couplings of the light force carriers.

Self-interaction cross sections are constrained by observations of astrophysical systems.

Abstract

Recent observations from PAMELA, FERMI, and ATIC point to a new source of high energy cosmic rays. If these signals are due to annihilating dark matter, then the annihilation cross section in the present day must be substantially larger than that necessary for thermal freeze-out in the early universe. A new force, mediated by a particle of mass O(100 MeV), leading to a velocity dependent annihilation cross section - a `Sommerfeld enhancement' - has been proposed as a possible explanation. We point out that such models necessarily increase the dark matter (DM) self-scattering cross section, and use observational bounds on the amount of DM-DM scattering allowed in various astrophysical systems to place constraints on the mass and couplings of the light mediator.