Measurement of the WWγ coupling in the process eγ→νqq̄ off the W-boson resonance

We study the WWγ gauge boson coupling in the process eγ→νqq̄ off the W-boson resonance by evaluating the helicity amplitudes of all contributing Feynman diagrams. We examine this process for 500 GeV and 1 TeV e⁺e^- colliders including the photon spectra obtained from both a backscattered laser and from beamstrahlung radiation. The couplings could best be measured using the backscattered laser photons with |δκ_γ| ≤=0.08 and -0.07<λ<0.10 at a 500 GeV collider and |λ_γ|≤0.03 at a 1 TeV collider, all at 95% C.L. Except for the relatively weak limits on δκ at √s = 1 TeV, these sensitivities are the same order of magnitude as can be obtained from real single W-production demonstrating that additional information can be obtained from non-resonant final states.