First study of the radiation-amplitude zero in W gamma production and limits on anomalous WW gamma couplings at s**(1/2) = 1.96- TeV

We present results from a study of p-pbar -> W(gamma) + X events utilizing data corresponding to 0.7 fb^{-1} of integrated luminosity at sqrt(s) = 1.96 TeV collected by the D0 detector at the Fermilab Tevatron Collider. We set limits on anomalous WWgamma couplings at the 95% C.L. The one dimensional 95% C.L. limits are 0.49 < kappa_{gamma} < 1.51 and -0.12 < lambda_{gamma} < 0.13. We make the first study of the charge-signed rapidity difference between the lepton and the photon and find it to be indicative of the standard model radiation-amplitude zero in the Wgamma system