Measurement of the electroweak production of Z gamma and two jets in proton-proton collisions at √ s=13 TeV and constraints on anomalous quartic gauge couplings

Abstract

The first observation of the electroweak (EW) production of a Z boson, a photon, and two forward jets (Zγjj) in proton-proton collisions at a center-of-mass energy of 13 TeV is presented. A data set corresponding to an integrated luminosity of 137 fb−¹, collected by the CMS experiment at the LHC in 2016–2018 is used. The measured fiducial cross section for EW Zγjj is σEW ¼ 5.21 ± 0.52(stat)± 0.56(syst) fb = 5.21 ± 0.76 fb. Single-differential cross sections in photon, leading lepton, and leading jet transverse momenta, and double-differential cross sections in mjj and |Δηjj|are also measured. Exclusion limits on anomalous quartic gauge couplings are derived at 95% confidence level in terms of the effective field theory operators M₀ to M₅, M₇, T₀ to T₂, and T₅ to T₉.