Theory Group Seminar, 10 October 2017

Matt Baumgart, Arizona State University

Resummed Photon Spectra for WIMP Annihilation

abstract

The indirect detection of photons that result from the annihilation of weakly interacting massive particles (WIMP) is one of the canonical discovery channels for these dark matter candidates.  This holds true for the example of $$SU(2)$$ triplet fermion dark matter -- the pure wino. A thermal wino would have mass of $$\sim 3 \textrm{ TeV}$$, and the strongest constraints come from a search for a photon line from the Galactic center, motivating a careful study of the relevant predictions. A large separation between the hard annihilation scale and the weak scale leads to a breakdown of perturbation theory from both the Sommerfeld enhancement and Sudakov double logarithms. The finite energy resolution inherent to the relevant experiments implies that contributions from the photon spectra away from the endpoint should be included, and will in fact yield an $$\mathcal{O}(1)$$ change in the prediction. This complicates the calculation since the inclusion of a finite bin size presents an additional scale(s), which appear as the argument of new Sudakov double logs. We construct a universal description in terms of an effective field theory (EFT) for heavy WIMP annihilation that can be used to separate all relevant scales.