Abstract
We report a study of final states containing a W boson and hadronic jets, produced in proton-proton collisions at a center-of-mass energy of 7 TeV. The data were collected with the ATLAS detector at the CERN LHC and comprise the full 2010 data sample of 36 pb^-1. Cross sections are determined using both the electron and muon decay modes of the W boson and are presented as a function of inclusive jet multiplicity, N_jet, for up to five jets. At each multiplicity, cross sections are presented as a function of jet transverse momentum, the scalar sum of the transverse momenta of the charged lepton, missing transverse momentum, and all jets, the invariant mass spectra of jets, and the rapidity distributions of various combinations of leptons and final-state jets. The results, corrected for all detector effects and for all backgrounds such as diboson and top quark pair production, are compared with particle-level predictions from perturbative QCD. Leading-order multiparton event generators, normalized to the NNLO total cross section for inclusive W-boson production, describe the data reasonably well for all measured inclusive jet multiplicities. Next-to-leading-order calculations from MCFM, studied here for N_jet >= 2, and BlackHat-Sherpa, studied here for N_jet >= 4, are found to be mostly in good agreement with the data.
Highlights
The study of massive vector boson production in association with one or more jets is an important test of quantum chromodynamics (QCD)
This paper reports a measurement at the CERN Large Hadron Collider (LHC) of the W þ jets cross section for pproffiffiton-proton collisions at a center-of-mass energy ( s) of 7 TeV, using the ATLAS detector
The transverse energy within a cone of radius R 1⁄4 0:2 around the electron, corrected for contributions from the electron, was required to be less than 4 GeV. This isolation requirement is more than 96% efficient over all jet multiplicities for prompt electrons originating from decays of W bosons and reduces the nonisolated electron background by a factor of 2
Summary
The study of massive vector boson production in association with one or more jets is an important test of quantum chromodynamics (QCD). It is an extension of an earlier ATLAS measurement of both the electron and muon decay modes of the W boson based on 1:3 pbÀ1 [9]. The results have been corrected for all known detector effects and are quoted in a specific range of jet and lepton kinematics, fully covered by the detector acceptance. This avoids model-dependent extrapolations and facilitates comparisons with theoretical predictions. Theoretical calculations at next-to-leading order (NLO) in perturbative QCD (pQCD) have been computed inclusively for up to four jets [10,11] and are compared with the data
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