Gauge Invariant Three-Boson Vertices in the Standard Model and the Static Properties of the W

We use the S-matrix pinch technique to derive to one loop-order gauge independent $\gamma W^{+}{W}^{-}$ and Z $W^{+}{W}^{-}$ vertices in the context of the Standard Model,with all three incoming momenta off-shell. We show that the $\gamma W^{+}{W}^{-}$ vertex so constructed is related to the gauge-independent W self-energy,derived by Degrassi and Sirlin,by a very simple QED-like Ward identity.The same results are obtained by the pinch technique applied directly to the process $e^{+}{e}^{-}\to W^{+}{W}^{-}$. Explicit calculations give rise to expressions for the static properties of the W gauge bosons like magnetic dipole and electric quadruple moments which being gauge independent satisfy such crucial properties as infrared finiteness and perturbative unitarity.