# Tag Info

I think you left out some bits and pieces here and there. Applying the Slavnov identity (which, I assume, also goes for the bare propagator $D^{(0)}$), one can cancel the left-hand side with the first term of the right-hand side (both being $-ia\delta_{ab}\frac1{k^2}k^\nu$). Then you bring some factors to the front to find that your third (indented) ...