Centre d'études et d'expertise sur les risques, l'environnement, la mobilité et l'aménagement

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We present the complete calculation of W-boson production in association with a jet in hadronic collisions through next-to-next-to-leading order (NNLO) in perturbative QCD. To cancel infrared divergences, we discuss a new subtraction method that exploits the fact that the N-jettiness event-shape variable fully captures the singularity structure of QCD amplitudes with final-state partons. This method holds for processes with an arbitrary number of jets and is easily implemented into existing frameworks for higher-order calculations. We present initial phenomenological results for W+jet production at the LHC. The NNLO corrections are small and lead to a significantly reduced theoretical error, opening the door to precision measurements in the W+jet channel at the LHC.

We compute the 3-loop O(αα s ) correction to the Higgs boson production cross section arising from light quarks using an effective theory approach. Our calculation probes the factorization of QCD and electroweak perturbative corrections to this process. We combine our results with the best current estimates for contributions from top and bottom quarks to derive an updated theoretical prediction for the Higgs boson production cross section in gluon fusion. With the use of the MSTW 2008 parton distribution functions that include the newest experimental data, our study results in cross sections approximately 4 − 6% lower for intermediate Higgs boson masses than those used in recent Tevatron analyses that imposed a 95% confidence level exclusion limit of a Standard Model Higgs boson with M H = 170 GeV.