First measurements of the W -> lv and Z/gamma* -> ll (l = e; mu) production cross sections in proton-proton collisions at root s = 7 TeV are presented using data recorded by the ATLAS experiment at the LHC. The results are based on 2250 W -> lv 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 sigma(tot)(W) center dot BR(W -> lv) = 9.96 +/- 0.23(stat) +/- 0.50(syst) +/- 1.10(lumi) nb and sigma(tot)(Z) center dot BR(Z/gamma* -> ll) = 0.82 +/- 0.06 (stat) +/- 0.05 (syst) +/- 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 +/- 0.9(stat) +/- 0.4(syst). In addition, measurements of the W+ 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. RI O'Shea, Val/G-1279-2010; Nemecek, Stanislav/C-3487-2012; valente, paolo/A-6640-2010; Takai, Helio/C-3301-2012; Jones, Roger/H-5578-2011; Britton, David/F-2602-2010; Li, Xuefei/C-3861-2012; Doyle, Anthony/C-5889-2009; Pina, Joao /C-4391-2012; Smirnova, Lidia/D-8089-2012; Smirnov, Sergei/F-1014-2011; Gladilin, Leonid/B-5226-2011; Kramarenko, Victor/E-1781-2012; Prokoshin, Fedor/E-2795-2012; Fazio, Salvatore /G-5156-2010; Alexa, Calin/F-6345-2010; Moorhead, Gareth/B-6634-2009; Livan, Michele/D-7531-2012; Petrucci, Fabrizio/G-8348-2012; Wemans, Andre/A-6738-2012; Fabbri, Laura/H-3442-2012; Kurashige, Hisaya/H-4916-2012; Villa, Mauro/C-9883-2009; Kuzhir, Polina/H-8653-2012; Andreazza, Attilio/E-5642-2011; Delmastro, Marco/I-5599-2012

Measurement of the W -> lv and Z/gamma* -> ll production cross sections in proton-proton collisions at root s=7 TeV with the ATLAS detector

CAPUA, Marcella;Crosetti G.;Fazio S.;