Full NLO corrections to 3-jet production and R32 at the LHC

We present the evaluation of the complete set of NLO corrections to three-jet production at the LHC. To this end we consider all contributions of $\mathcal{{O}}(\alpha _s^n\alpha ^m)$ with $n+m=3$ and $n+m=4$ . This includes in particular also subleading Born contributions of electroweak origin, as well as electroweak virtual and QED real-radiative corrections. As an application we present results for the three- over two-jet ratio $R_{32}$ . While the impact of non-QCD corrections on the total cross section is rather small, they can exceed $-10\%$ for high jet transverse momenta. The $R_{32}$ observable turns out to be very stable against electroweak corrections, receiving absolute corrections below $5\%$ even in the high- $p_T$ region.