Measurement of electroweak Z(??¯) ?jj production and limits on anomalous quartic gauge couplings in pp collisions at ?s = 13 TeV with the ATLAS detector

Abstract

The electroweak production of Z(??¯) ? in association with two jets is studied in a regime with a photon of high transverse momentum above 150 GeV using proton–proton collisions at a centre-of-mass energy of 13 TeV at the Large Hadron Collider. The analysis uses a data sample with an integrated luminosity of 139 fb?1 collected by the ATLAS detector during the 2015–2018 LHC data-taking period. This process is an important probe of the electroweak symmetry breaking mechanism in the Standard Model and is sensitive to quartic gauge boson couplings via vector-boson scattering. The fiducial Z(??¯) ?jj cross section for electroweak production is measured to be 0.77?0.30+0.34 fb and is consistent with the Standard Model prediction. Evidence of electroweak Z(??¯) ?jj production is found with an observed significance of 3.2? for the background-only hypothesis, compared with an expected significance of 3.7?. The combination of this result with the previously published ATLAS observation of electroweak Z(??¯) ?jj production yields an observed (expected) signal significance of 6.3? (6.6?). Limits on anomalous quartic gauge boson couplings are obtained in the framework of effective field theory with dimension-8 operators. [Figure not available: see fulltext.]. © 2023, The Author(s).