Observation of Wγγ triboson production in proton-proton collisions at √s = 13 TeV with the ATLAS detector Aad, Georges Rodríguez Chala, Mikael Atlas Collaboration, / This letter reports the observation of W(lv)γγ production in proton-proton collisions. This measurement uses the full Run 2 sample of events recorded at a center-of-mass energy of √s = 13 TeV by the ATLAS detector at the LHC, corresponding to an integrated luminosity of 140 fb−1. Events with a leptonically-decaying W boson and at least two photons are considered. The background-only hypothesis is rejected with an observed and expected significance of 5.6 standard deviations. The inclusive fiducial production cross section of W(ev)γγ and W(µv)γγ events is measured to be σfid = 13.8 ± 1.1(stat)+2.1−2.0(syst) ± 0.1(lumi) fb, in agreement with the Standard Model prediction. 2024-06-12T10:40:41Z 2024-06-12T10:40:41Z 2023-12-14 journal article Aad, Georges, et al. Observation of Wγγ triboson production in proton-proton collisions at √s = 13 TeV with the ATLAS detector. Phys. Lett. B 848 (2024) 138400 [10.1016/j.physletb.2023.138400] https://hdl.handle.net/10481/92540 10.1016/j.physletb.2023.138400 eng http://creativecommons.org/licenses/by/4.0/ open access Atribución 4.0 Internacional Elsevier