Measurement of W+W− production in association with one jet in proton--proton collisions at s√=8 TeV with the ATLAS detector

Abstract

The production of W boson pairs in association with one jet in pp collisions at s = 8 TeVis studied using data corresponding to an integrated luminosity of 20.3 fb −1 collected bythe ATLAS detector during 2012 at the CERN Large Hadron Collider. The cross section ismeasured in a fiducial phase-space region defined by the presence of exactly one electronand one muon, missing transverse momentum and exactly one jet with a transverse mo-mentum above 25 GeV and a pseudorapidity of |η| < 4.5. The leptons are required to haveopposite electric charge and to pass transverse momentum and pseudorapidity requirements.fid,1-jetThe fiducial cross section is found to be σ WW = 136 ± 6 (stat) ± 14 syst ± 3 (lumi) fb. Incombination with a previous measurement restricted to leptonic final states with no associ-ated jets, the fiducial cross section of WW production with zero or one jet is measured to befid,≤1-jetσ WW= 511 ± 9 (stat) ± 26 syst ± 10 (lumi) fb. The ratio of fiducial cross sections in finalstates with one and zero jets is determined to be 0.36 ± 0.05. Finally, a total cross sectionextrapolated from the fiducial measurement of WW production with zero or one associatedjet is reported.