NLO QCD corrections to WW+jet production including leptonic W decays at hadron colliders

We report on the calculation of the next-to-leading order QCD corrections to the production of W-boson pairs in association with a hard jet at the Tevatron and the LHC, which is an important source of background for Higgs and new-physics searches. Leptonic decays of the W bosons are included by applying an improved version of the narrow-width approximation that treats the W bosons as on-shell particles, but keeps the information on the W spin. A selection of differential NLO QCD cross sections is provided both for the LHC and the Tevatron. The QCD corrections stabilize the LO prediction for the cross section with respect to scale variations. The differential LO cross sections are generally not simply rescaled by the corrections. Their shapes are particularly distorted if an additional energy scale is involved.