Measurement of W± and Z-boson production cross sections in pp collisions at sqrt(s) = 13 TeV with the ATLAS detector

Measurements of the W±→ℓ±ν and Z→ℓ+ℓ− production cross sections (where ℓ±=e±,μ±) in proton-proton collisions at sqrt(s)=13 TeV are presented using data recorded by the ATLAS experiment at the Large Hadron Collider, corresponding to a total integrated luminosity of 81 pb−1. The total inclusive W±-boson production cross sections times the single-lepton-flavour branching ratios are σtotW+=11.78±0.02(stat)±0.32(sys)±0.59(lumi) nb and σtotW−=8.75±0.02(stat)±0.24(sys)±0.44(lumi) nb for W+ and W−, respectively. The total inclusive Z-boson production cross section times leptonic branching ratio, within the invariant mass window 66<mℓℓ<116 GeV, is σtotZ=1.97±0.01(stat)±0.04(sys)±0.10(lumi) nb. The W+, W−, and Z-boson production cross sections and cross-section ratios within a fiducial region defined by the detector acceptance are also measured. The cross-section ratios benefit from significant cancellation of experimental uncertainties, resulting in σfidW+/σfidW−=1.295±0.003(stat)±0.010(sys) and σfidW±/σfidZ=10.31±0.04(stat)±0.20(sys). Theoretical predictions, based on calculations accurate to next-to-next-to-leading order for quantum chromodynamics and next-to-leading order for electroweak processes and which employ different parton distribution function sets, are compared to these measurements.