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- 117

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When looking at the renormalization conditions for QED (see page 332, equation 10.40 from Peskin), there is a condition that requires the photon propagator at ##q^2 = 0## to evaluate to 0. But looking at the expression for the photon propagator counterterm: ##-i(g^{\mu\nu}q^2 - q^{\mu}q^{\nu})\delta_{3}##, can I not rewrite ##q^{\mu}q^{\nu} = g^{\mu\nu}q_{\nu}q^{\nu} = g^{\mu\nu}q^{2}## and then the entire counterterm just disappears?