Threshold resummed and approximate next-to-next-to-leading order results forWþW pair production at the LHC

The next-to-leading order (NLO) QCD radiative corrections to WþW production at hadron colliders are well understood. We combine NLO perturbative QCD calculations with soft-gluon resummation of threshold logarithms to find a next-to-next-to-leading logarithmic (NNLL) prediction for the total cross section and the invariant mass distribution at the LHC. We also obtain approximate next-to-next-toleading order (NNLO) results for the total WþW cross section at the LHC which includes all contributions from the scale dependent leading singular terms. Our result for the approximate NNLO total cross section is the most precise theoretical prediction available. Uncertainties due to scale variation are shown to be small when the threshold logarithms are included. NNLL threshold resummation increases the WþW invariant mass distribution by 3%–4% in the peak region for both ffiffiffi S p 1⁄4 8 and 14 TeV. The NNLL threshold resummed and approximate NNLO cross sections increase the NLO cross section by 0.5%–3% for ffiffiffi S p 1⁄4 7, 8, 13, and 14 TeV.