Measurements of inclusive W and Z cross sections in pp collisions at √s= 7s TeV

Measurements of inclusive W and Z boson production cross sections in pp collisions at √s = 7 TeV are presented, based on 2.9 pb-1 of data recorded by the CMS detector at the LHC. The measurements, performed in the electron and muon decay channels, are combined to give σ( pp→ WX ) × B( W→ev) = 9.95± 0.07(stat. )± 0.28( syst. )± 1.09 (lumi.) nb and σ( pp → ZX ) × B( Z → l+ l-) = 0.931± 0.026( stat.)± 0.023( syst.)± 0.102 (lumi.) nb, where l stands for either e or μ. Theoretical predictions, calculated at the next-to-next-to-leading order in QCD using recent parton distribution functions, are in agreement with the measured cross sections. Ratios of cross sections, which incur an experimental systematic uncertainty of less than 4%, are also reported