The electroweak production of Z(νν¯)γ 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(νν¯)γjj cross section for electroweak production is measured to be 0.77+0.34 −0.30 fb and is consistent with the Standard Model prediction. Evidence of electroweak Z(νν¯)γjj production is found with an observed significance of 3.2σ for the background-only hypothesis, compared with an expected significance of 3.7σ. The combination of this result with the previously published ATLAS observation of electroweak Z(νν¯)γjj production yields an observed (expected) signal significance of 6.3σ (6.6σ). Limits on anomalous quartic gauge boson couplings are obtained in the framework of effective field theory with dimension-8 operators.

G. Aad, B. Abbott, D. C. Abbott, K. Abeling, S. H. Abidi, A. Aboulhorma, et al. (2023). Measurement of electroweak Z(νν¯)γjj production and limits on anomalous quartic gauge couplings in pp collisions at √s = 13 TeV with the ATLAS detector. JOURNAL OF HIGH ENERGY PHYSICS, 2023(6), 0-47 [10.1007/jhep06(2023)082].

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

G. L. Alberghi;F. Alfonsi;M. Bindi;D. Boscherini;G. Cabras;G. Carratta;N. Cavalli;L. Clissa;S. De Castro;F. Fabbri;L. Fabbri;M. Franchini;A. Gabrielli;F. Lasagni Manghi;L. Massa;