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 E_γ=m_χ 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 m_W ²/m_χ for photons with TeV energies.