Fiducial and differential measurements of W^+W^- production in events with at least one hadronic jet are presented. These cross-section measurements are sensitive to the properties of electroweak-boson self-interactions and provide a test of perturbative quantum chromodynamics and the electroweak theory. The analysis is performed using proton-−proton collision data collected at \sqrt{s}=13 TeV with the ATLAS experiment, corresponding to an integrated luminosity of 139~ fb^{-1} . Events are selected with exactly one oppositely charged electron-−muon pair and at least one hadronic jet with a transverse momentum of p_T>30 GeV and a pseudorapidity of |\eta|<4.5∣η∣<4.5. After subtracting the background contributions and correcting for detector effects, the jet-inclusive W^+W^- \ge 1~W ≥1 jet fiducial cross-section and W^+W^-+W jets differential cross-sections with respect to several kinematic variables are measured, thus probing a previously unexplored event topology at the LHC. These measurements include leptonic quantities, such as the lepton transverse momenta and the transverse mass of the W^+W^- system, as well as jet-related observables such as the leading jet transverse momentum and the jet multiplicity. Limits on anomalous triple-gauge-boson couplings are obtained in a phase space where interference between the Standard Model amplitude and the anomalous amplitude is enhanced.

Measurements of W + W −+ ≥ 1 jet production cross-sections in pp collisions at √s = 13 TeV with the ATLAS detector

Farina E. M.;Introzzi G.;Livan M.;Negri A.;Pezzotti L.;Rebuzzi D. M.;Rimoldi A.;Rovelli G.;