Measurements of the W production cross sections in association with jets with the ATLAS detector

This note presents the production cross section of the W boson in association with jets, measured in proton--proton collisions at $\sqrt{s}=7 TeV$ with the ATLAS experiment at the Large Hadron Collider. This measurement uses a data set corresponding to an integrated luminosity of $4.6\, fb^{-1}$ recorded during 2011. Cross sections are shown as a function of the jet multiplicity up to seven jets for electron and muon decay modes of the W boson. Differential cross sections are measured with respect to the transverse momenta and rapidity of jets for events with multiplicities up to five jets. The differential cross sections as a function of the sum of the transverse momenta of the jets, lepton and neutrino, of the sum of the transverse momentum of the jets, and of the angular separation and invariant mass of the two jets with the highest transverse momenta are also measured. The results have been corrected for detector effects and are quoted in well-defined ranges of jet and lepton kinematics corresponding to the detector acceptance. The measurements are compared to next-to-leading-order perturbative QCD calculations, resummation calculations and to predictions from different Monte Carlo generators implementing next-to-leading-order and leading-order matrix elements supplemented by parton showers.