RenormalizableWself-energy in the unitary gauge via the pinch technique

We use the S-matrix pinch technique to derive to one loop order an effective renormalizable self-energy for the W gauge boson, when the theory is quantized in the unitary gauge. We then show that this amplitude is identical to the ξ-independent W self-energy previously constructed by applying the pinch technique in the context of the renormalizable ${\mathit{R}}_{\xi }$ gauges.