High Energy Theory Seminar

Since late July, the cosmic ray community has scrambled to explain the positron/electron ratio spectrum from the PAMELA satellite at 1 < E < 50 GeV. Combining this with previous data on the electron cosmic ray spectrum, we now have evidence for a "bump" in the cosmic spectrum, half electrons and half positrons. I will explore the possibilities for making this with WIMP annihilation, and show that generic candidates from supersymmetry cannot make such a signal without violating other constraints on gamma-rays. I will then introduce a toy model (developed with Neal Weiner) involving a new light particle in the dark sector which couples strongly to the WIMP, but only very weakly to the standard model. In this scenario, the WIMP annihilates through this new particle, evading constraints on gammas and anti-protons. Such a model can have the correct mass, annihilation cross section, and scattering cross section to explain the PAMELA data and the WMAP haze excess, while naturally having the right thermal relic cross section. The model can also explain the INTEGRAL 511 keV line in the inner few degrees of the galaxy via inelastic scattering.