Cosmic-Ray Positrons Limit Dark Matter Models

Astrophysicists are still trying to make sense out of an excess of positrons recently revealed in cosmic-ray data. One possible explanation is that these antielectrons result from dark matter decays or annihilations. A new analysis shows that certain dark matter models are constrained by the smoothness of the positron energy spectrum. In Physical Review Letters, the authors place the strictest limits yet on potential annihilation scenarios for dark matter particles.