Precise predictions for W+4-jet production at the large hadron collider.

We present the next-to-leading order (NLO) QCD results for W+4-jet production at hadron colliders. This is the first hadron-collider process with five final-state objects to be computed at NLO. It represents an important background to many searches for new physics at the energy frontier. Total cross sections, as well as distributions in the jet transverse momenta, are provided for the initial LHC energy of √s = 7 TeV. We use a leading-color approximation, known to be accurate to 3% for W production with fewer jets. The calculation uses the BLACKHAT library along with the SHERPA package.

Precise predictions for w+3 jet production at hadron colliders.

We report on the first next-to-leading order QCD computation of W+3-jet production in hadronic collisions including all partonic subprocesses. We compare the results with data from the Tevatron and find excellent agreement. The required one-loop matrix elements are computed using on-shell methods, implemented in a numerical program, BlackHat. We use the SHERPA package to generate the real-emission contributions and to integrate the various contributions over phase space. We use a leading-color (large-N_{c}) approximation for the virtual part, which we confirm in W+1, 2-jet production to be valid to within three percent.