Search for WWγ and WZγ production and constraints on anomalous quartic gauge couplings in pp collisions at √s = 8 TeV

A search for WVγ triple vector boson production is presented based on events containing a W boson decaying to a muon or an electron and a neutrino, a second V (W or Z) boson, and a photon. The data correspond to an integrated luminosity of 19.3 fb⁻¹ collected in 2012 with the CMS detector at the LHC in pp collisions at √s = 8 TeV. An upper limit of 311 fb on the cross section for the WVγ production process is obtained at 95% confidence level for photons with a transverse energy above 30 GeV and with an absolute value of pseudorapidity of less than 1.44. This limit is approximately a factor of 3.4 larger than the standard model predictions that are based on next-to-leading order QCD calculations. Since no evidence of anomalous WWγγ or WWZγ quartic gauge boson couplings is found, this paper presents the first experimental limits on the dimension-eight parameter f_T;0 and the CP-conserving WWZγ parameters κ^W₀ and κ^W_C. Limits are also obtained for the WWγγ parameters a^W₀ and a^W_C.