Suppose the theory of left and right fermions, which interact with the abelian gauge field. Left and right sectors of the theory have the gauge anomaly: by defining the anomaly as the variation of the quantum effective action Γ[A], obtained by integrating out the heavy fermions (the so-called consistent anomaly), we have
∂μJμL/R=±148π2Fμν˜Fμν
I have met the statement that for the abelian case the above consistent anomaly is related to the so-called
covariant anomaly,
∂μJμL/R=±116π2Fμν˜Fμν,
by the factor one third. See, precisely, remark [29]
here. In one reference I've seen completely unclear manipulations with the Bardeen-Zumino polynomial, see section 2
here. What I don't understand is the formal difference between the covariant and consistent anomalies in the abelian case. In my opinion, for the abelian case the difference is absent, as I think, since the consistent anomaly in fact is the covariant one. So that I don't understand how to obtain the factor one third from formal thinking, and what in fact the covariant anomaly is in the abelian case. Could You explain, please?