ATLAS collaboration (3024 authors)Aguilar-Saavedra, Juan AntonioAmaral, PedroAnjos, NunoCarvalho, JoaoCastro, Nuno FilipeConde Muino, PatriciaDo Valle Wemans, AndreFiolhais, MiguelGomes, AgostinhoGoncalo, RicardoJorge, PedroLopes, LourencoMachado Miguens, JoanaMaio, AmeliaManeira, JoseOliveira, Miguel AlfonsoOnofre, AntonioPalma, AlbertoPina, Joao AntonioPinto, BelmiroSantos, HelenaSaraiva, JoaoSilva, JoseSoares, MaraVeloso, FilipeWolters, Helmut2019-02-032019-02-032013-07-16http://dx.doi.org/10.1016/j.physletb.2012.01.042http://hdl.handle.net/10400.26/26030The ratio of production cross sections of the W and Z bosons with exactly one associated jet is presented as a function of jet transverse momentum threshold. The measurement has been designed to maximise cancellation of experimental and theoretical uncertainties, and is reported both within a particle-level kinematic range corresponding to the detector acceptance and as a total cross-section ratio. Results are obtained with the ATLAS detector at the LHC in pp collisions at a centre-of-mass energy of 7 TeV using an integrated luminosity of 33 pb^-1. The results are compared with perturbative leading-order, leading-log, and next-to-leading-order QCD predictions, and are found to agree within experimental and theoretical uncertainties. The ratio is measured for events with a single jet with p_T > 30 GeV to be 8.73 +/- 0.30 (stat) +/- 0.40 (syst) in the electron channel, and $ 8.49 +/- 0.23 (stat) +/- 0.33 (syst) in the muon channel.engjournal article2019-02-03