Adler-Bell-Jackiw anomaly, the Nieh-Yan form, and vacuum polarization - art. no. 045006

We show, from first principles, using explicitly invariant Pauli-Villars re gularization of chiral fermions, that the Nieh-Yan form does contribute to the Adler-Bell-Jackiw (ABJ) anomaly for spacetimes with generic torsion, an d comment on some of the implications. There are a number of interesting an d important differences with the usual ABJ contribution in the absence of t orsion. For dimensional reasons, the Nieh-Yan term is proportional to the s quare of the regulator mass. In spacetimes with flat vierbein but nontrivia l torsion, the associated diagrams are actually vacuum polarization rather than triangle diagrams and the Nieh-Yan contribution to the ABJ anomaly ari ses from the fact that the axial torsion ''photon'' is not transverse. [S05 56-2821(99)02402-9].