Matthew Baumgart (Carnagie Mellon University)

On the Annihilation of WIMPs

If dark matter has a straightforward connection to known physics, the thermal-relic, weakly interacting massive particle (WIMP) is one of the most elegant candidates. The possibility of obtaining such a particle from SUSY continues to be a principle argument for that scenario. The case of pure-Wino dark matter is an especially simple possibility and is favored by "mini-split'' SUSY, which foregoes strict naturalness for simpler model-building. Furthermore, independently of supersymmetry, the addition of a stable SU(2) triplet represents a minimal Standard Model extension to provide dark matter. An accurate determination of wino annihilation rates relevant for constraints from indirect detection is therefore highly desired. The regime of wino masses favored by relic abundance determinations places Mwino ~ 3 TeV. This results in large Sudakov double logarithms that persist even in the total rate. By combining a nonrelativistic effective theory for the heavy dark matter with an electroweak SCET for the gauge boson final states, we can resum these effects. By combining Sommerfeld enhancement from the initial state, we determine the overall rate and constrain the wino parameter space. Despite the specific interest in winos, our methods are generic for any electroweak-coupled dark matter in the with mass TeV-scale or greater.