  Measurements are presented of W gamma gamma and Z gamma gamma production in
proton-proton collisions. Fiducial cross sections are reported based on a data
sample corresponding to an integrated luminosity of 19.4 inverse femtobarns
collected with the CMS detector at a center-of-mass energy of 8 TeV. Signal is
identified through the W to l nu and Z to ll decay modes, where l is a muon or
an electron. The production of W gamma gamma and Z gamma gamma, measured with
significances of 2.6 and 5.9 standard deviations, respectively, is consistent
with standard model predictions. In addition, limits on anomalous quartic gauge
couplings in W gamma gamma production are determined in the context of a
dimension-8 effective field theory.
