Study of WWγ and W Zγ production in pp collisions at √s = 8 TeV and search for anomalous quartic gauge couplings with the ATLAS experiment

This paper presents a study of WWγWWγ and WZγWZγ triboson production using events from proton–proton collisions at a centre-of-mass energy of s√=8TeVs=8TeV recorded with the ATLAS detector at the LHC and corresponding to an integrated luminosity of 20.2 fb −1−1 . The WWγWWγ production cross-section is determined using a final state containing an electron, a muon, a photon, and neutrinos ( eνμνγeνμνγ ). Upper limits on the production cross-section of the eνμνγeνμνγ final state and the WWγWWγ and WZγWZγ final states containing an electron or a muon, two jets, a photon, and a neutrino ( eνjjγeνjjγ or μνjjγμνjjγ ) are also derived. The results are compared to the cross-sections predicted by the Standard Model at next-to-leading order in the strong-coupling constant. In addition, upper limits on the production cross-sections are derived in a fiducial region optimised for a search for new physics beyond the Standard Model. The results are interpreted in the context of anomalous quartic gauge couplings using an effective field theory. Confidence intervals at 95% confidence level are derived for the 14 coupling coefficients to which WWγWWγ and WZγWZγ production are sensitive.