Measurement of W± and Z-boson production cross sections in pp collisions at 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 √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 σ tot W + =11.83±0.02(stat)±0.32(sys)±0.25(lumi) nb and σ tot 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 66stat)±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 σ fid W + /σ fid W − =1.295±0.003(stat)±0.010(sys) and σ fid W ± /σ fid 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.