Measurement of the W±Z boson pair-production cross section in pp collisions at √s = 13 TeV with the ATLAS detector

The production of W±Z events in proton–proton collisions at a centre-of-mass energy of 13 TeV is measured with the ATLAS detector at the LHC. The collected data correspond to an integrated luminosity of 3.2 fb−1. The W±Z candidates are reconstructed using leptonic decays of the gauge bosons into electrons or muons. The measured inclusive cross section in the detector fiducial region for leptonic decay modes is σfid. W±Z→ℓʹ νℓℓ = 63.2±3.2(stat.)±2.6(sys.)±1.5 (lumi.) fb. In comparison, the next-to-leading-order Standard Model prediction is 53.4 +3.6 −2.8fb. The extrapolation of the measurement from the fiducial to the total phase space yields σtot. W±Z=50.6±2.6 (stat.)±2.0 (sys.)±0.9 (th.)±1.2 (lumi.) pb, in agreement with a recent next-to-next-to-leading-order calculation of 48.2 +1.1 −1.0pb. The cross section as a function of jet multiplicity is also measured, together with the charge-dependent W+Z and W−Z cross sections and their ratio.