  We present the full one-loop SUSY-QCD corrections to stop-antistop
annihilation into gluons and light quarks within the Minimal Supersymmetric
Standard Model including Sommerfeld enhancement effects from the exchange of
multiple gluons between the incoming particles. These corrections are important
as stop (co)annihilation becomes the dominant contribution to the relic density
for scenarios with a small mass difference between the neutralino and the stop
which are less constrained by current LHC searches and consistent with the
observation of a 125 GeV SM-like Higgs boson. We discuss important technical
details of our one-loop, real emission, and resummation calculations where we
pay particular attention to the cancellation of infrared divergences and the
associated application of the dipole formalism for massive initial scalars. The
corrections have been implemented in the dark matter precision tool DM@NLO
which allows us to study numerically the impact of these corrections on the
annihilation cross section. We find that for the chosen reference scenario the
dominant correction comes from the Sommerfeld effect and that the pure NLO
correction is below 3%. The inclusion of these radiative corrections is still
large enough to decrease the relic density by more than 10% and shift the
cosmologically preferred parameter region by a few GeV relative to the standard
MicrOMEGAs result. Therefore, the inclusion of these corrections is mandatory
if the experimental errors are taken as upper and lower bounds of the theory
value.
