Search for $WW \gamma$ and $WZ \gamma$ production and constraints on anomalous quartic gauge couplings in $pp$ collisions at $\sqrt s =$ 8 TeV

A search for WV gamma 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 inverse femtobarns collected in 2012 with the CMS detector at the LHC in pp collisions at sqrt(s) = 8 TeV. An upper limit of 311 fb on the fiducial cross section for the WV gamma 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 WW gamma gamma or WWZ gamma quartic gauge boson couplings is found, this paper presents the first experimental limits on the dimension-8 parameter f[T,0] and the CP-conserving WWZ gamma parameters kappa[0,W] and kappa[C,W]. Limits are also obtained for the WW gamma gamma parameters a[0,W] and a[C,W].