Measurement of the W -_s13gt_s19 lnu and Z/gamma* -_s13gt_s19 ll production cross sections in proton-proton collisions at sqrt(s) = 7 TeV with the ATLAS detector

Abstract

First measurements of the W -> lnu and Z/gamma* -> ll (l = e, mu) production cross sections in proton-proton collisions at sqrt(s) = 7 TeV are presented using data recorded by the ATLAS experiment at the LHC. The results are based on 2250 W -> lnu and 179 Z/gamma* -> ll candidate events selected from a data set corresponding to an integrated luminosity of approximately 320 nb-1. The measured total W and Z/gamma*-boson production cross sections times the respective leptonic branching ratios for the combined electron and muon channels are $stotW$ * BR(W -> lnu) = 9.96 _s16- 0.23(stat) _s16- 0.50(syst) _s16- 1.10(lumi) nb and $stotZg$ * BR(Z/gamma* -> ll) = 0.82 _s16- 0.06(stat) _s16- 0.05(syst) _s16- 0.09(lumi) nb (within the invariant mass window 66 < m_ll < 116 GeV). The W/Z cross-section ratio is measured to be 11.7 _s16- 0.9(stat) _s16- 0.4(syst). In addition, measurements of the W_s16 and W- production cross sections and of the lepton charge asymmetry are reported. Theoretical predictions based on NNLO QCD calculations are found to agree with the measurements.