Abstract:
A measurement of the 𝑊𝑍𝛾
triboson production cross section is presented. The analysis is based on a data sample of proton-proton collisions at a center-of-mass energy of √𝑠 =13 TeV
recorded with the CMS detector at the LHC, corresponding to an integrated luminosity of 138 fb−1
. The analysis focuses on the final state with three charged leptons, ℓ±𝜈ℓ+ℓ−
, where ℓ =𝑒
or 𝜇
, accompanied by an additional photon. The observed (expected) significance of the 𝑊𝑍𝛾
signal is 5.4 (3.8) standard deviations. The cross section is measured in a fiducial region, where events with an ℓ originating from a tau lepton decay are excluded, to be 5.48 ±1.11 fb
, which is compatible with the prediction of 3.69 ±0.24 fb
at next-to-leading order in quantum chromodynamics. Exclusion limits are set on anomalous quartic gauge couplings and on the production cross sections of massive axionlike particles.