Energetic γ-rays from TeV scale dark matter annihilation resummed

The annihilation cross section of TeV scale dark matter particles χ0 with electroweak charges into photons is affected by large quantum corrections due to Sudakov logarithms and the Sommerfeld effect. We calculate the semi-inclusive photon energy spectrum in χ0χ0→γ+X in the vicinity of the maximal photon energy Eγ=mχ with NLL' accuracy in an all-order summation of the electroweak perturbative expansion adopting the pure wino model. This results in the most precise theoretical prediction of the annihilation rate for γ-ray telescopes with photon energy resolution of parametric order mW2/mχ for photons with TeV energies.