| Abstract: |
We construct an effective field theory (EFT) description of the hard photon spectrum for heavy WIMP annihilation. This facilitates precision predictions relevant for line searches, and allows the incorporation of non-trivial energy resolution effects. Our framework combines techniques from non-relativistic EFTs and soft-collinear effective theory (SCET), as well as its multi-scale extensions that have been recently introduced for studying jet substructure. We derive a factorization formula that enables both the resummation of all large Sudakov double logarithms that appear in the perturbative spectrum, and the inclusion of the Sommerfeld enhancement. Our final result reproduces both the exclusive and the inclusive limits, thereby providing a unifying description of these two previously considered approximations. We estimate the impact on experimental sensitivity, focusing for concreteness on an SU(2) triplet fermion dark matter -- the pure wino -- where the strongest constraints are due to a search for lines from the Galactic center. We find significant corrections to the analysis based on the resummed exclusive calculation, thereby highlighting the importance of including spectral photons when interpreting data from future indirect detection experiments. |
