Anomalies on orbifolds

We review the form of the chiral anomaly on an S-1 /Z(2) orbifold with chiral boundary conditions. The 4-divergence of the higher-dimensional current evaluated at a given point in the extra dimension is proportional to the probability of finding the chiral zero mode there. Nevertheless the anomaly, appropriately defined as the five-dimensional divergence of the current, lives entirely on the orbifold fixed planes and is independent of the shape of the zero mode. We show how to obtain these results in a simple way in terms of the properties of the Kaluza-Klein modes of the orbifold. (C) 2001 Elsevier Science B.V. All rights reserved.