Measurement of the $W^{\pm }Z$ boson pair-production cross section in $pp$ collisions at $\sqrt{s}=13$ TeV with the ATLAS Detector

Abstract

The production of $W^{\pm }Z$ 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 $W^{\pm }Z$ 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 ${\sigma }_{W^{\pm }Z\to {\ell }^{{}^{\prime }}\nu \ell \ell }^{\text{fid.}}=63.2\pm 3.2$ (stat.) $\pm 2.6$ (sys.) $\pm 1.5$ (lumi.) fb. In comparison, the next-to-leading-order Standard Model prediction is $53.4_{-2.8}^{+3.6}$ fb. The extrapolation of the measurement from the fiducial to the total phase space yields ${\sigma }_{W^{\pm }Z}^{\text{tot.}}=50.6\pm 2.6$ (stat.) $\pm 2.0$ (sys.) $\pm 0.9$ (th.) $\pm 1.2$ (lumi.) pb, in agreement with a recent next-to-next-to-leading-order calculation of $48.2_{-1.0}^{+1.1}$ pb. 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.

21 pages plus author list + cover pages (39 pages total), 4 figures, 4 tables, published in Phys. Lett. B. All figures including auxiliary figures are available at http://atlas.web.cern.ch/Atlas/GROUPS/PHYSICS/PAPERS/STDM-2015-19