Measurement of W-+/- and Z-boson production cross sections in pp collisions at root s=13 TeV with the ATLAS detector

Measurements of the W± → ±ν and Z → +− production cross sections (where ± = e±, μ±) in proton–proton collisions at √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 σtot W+ = 11.83 ±0.02 (stat)±0.32 (sys)±0.25 (lumi) nb and σtot W− =8.79 ±0.02 (stat)±0.24 (sys)±0.18 (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 <116 GeV, is σtot Z =1.981 ±0.007 (stat)± 0.038 (sys) ± 0.042 (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 σfid W+/σfid W− = 1.295 ±0.003 (stat)±0.010 (sys) and σfid W±/σfid Z =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 to next-to-leading order for electroweak processes and which employ different parton distribution function sets, are compared to these measurements.