A. Zee, Quantum Field Theory in a Nutshell · Problem V.7.13
Field Theory Redux
Physics — QFT
Problem
Prove that higher order corrections do not change the chiral anomaly ∂μJ5μ=[1/(4π)2]ϵμνλσtrFμνFλσ (I have rescaled A→(1/g)A). [Hint: Integrate over spacetime and show that the left hand side is given by the number of right-handed fermion quanta minus the number of left-handed fermion quanta, so that both sides are given by integers.]