Measuring triboson final states at the Large Hadron Collider provides a test of the non-Abelian structure of the Standard Model of particle physics. This structure gives rise to self-interactions of the electroweak gauge bosons and the Standard Model predicts the exact strength of these couplings. Any observed deviation from these expectations would imply the existence of new physical phenomena.

These proceedings present a study of triboson production using WWγ and WZγ events produced in proton–proton collisions corresponding to an integrated luminosity of 20.2 fb⁻¹ at a centre-of-mass energy of √s = 8 TeV and recorded with the ATLAS detector. The WWγ production cross-section is measured using the fully-leptonic final state containing an electron, a muon and a photon. Furthermore, upper limits on the production cross-section of the fully-leptonic final state and semi-leptonic final states containing an electron or a muon, two jets and a photon are derived. In addition, upper limits on the production cross-section are derived in a phase space optimised for the search of physics beyond the Standard Model. The limits are computed for all final states individually and for the combination of the electron and muon channel of the semi-leptonic final states. The results obtained in this phase space are combined and interpreted as confidence intervals on anomalous quartic gauge couplings using an effective field theory.