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.2011.12.046http://hdl.handle.net/10400.26/26039A measurement is presented of the cross section for the production of a W boson with one or two jets, of which at least one must be a b-jet, in pp collisions at sqrt(s)=7 TeV. Production via top decay is not included in the signal definition. The measurement is based on 35 pb^-1 of data collected with the ATLAS detector at the LHC. The W+b-jet cross section is defined for jets reconstructed with the anti-kt clustering algorithm with transverse momentum above 25 GeV and rapidity within +/-2.1. The b-jets are identified by reconstructing secondary vertices. The fiducial cross section is measured both for the electron and muon decay channel of the W boson and is found to be 10.2 +/- 1.9 (stat) +/- 2.6 (syst) pb for one lepton flavour. The results are compared with next-to-leading order QCD calculations, which predict a cross section smaller than, though consistent with, the measured value.engjournal article2019-02-03