Measurements of W+W- production cross-sections in pp collisions at SQUARE ROOTs = 13 TeV with the ATLAS detector

Abstract

Measurements of W+W- RIGHTWARDS ARROW e+-νμMINUS-OR-PLUS SIGNν production cross-sections are presented,providing a test of the predictions of perturbative quantum chromodynamics and theelectroweak theory. The measurements are based on data from pp collisions at SQUARE ROOTs = 13TeVrecorded by the ATLAS detector at the Large Hadron Collider in 2015-2018, corresponding toan integrated luminosity of 140 fb-1. The number of events due to top-quark pair production,the largest background, is reduced by rejecting events containing jets with b-hadron decays.An improved methodology for estimating the remaining top-quark background enables aprecise measurement of W+W- cross-sections with no additional requirements on jets. Thefiducial W+W- cross-section is determined in a maximum-likelihood fit with an uncertaintyof 3.1%. The measurement is extrapolated to the full phase space, resulting in a totalW+W- cross-section of 127 +- 4 pb. Differential cross-sections are measured as a functionof twelve observables that comprehensively describe the kinematics of W+W- events. Themeasurements are compared with state-of-the-art theory calculations and excellent agreementwith predictions is observed. A charge asymmetry in the lepton rapidity is observed as afunction of the dilepton invariant mass, in agreement with the Standard Model expectation.A CP-odd observable is measured to be consistent with no CP violation. Limits on StandardModel effective field theory Wilson coefficients in the Warsaw basis are obtained from thedifferential cross-sections.