Anomalies and inflow on D-branes and O-planes

TL;DR

The paper derives the general anomaly structure for chiral spinors and self-dual tensors on D-brane/O-plane intersections and demonstrates that RR couplings generate inflow that exactly cancels these anomalies. By employing both Fujikawa path-integral methods and index/G-index theorems, it connects the anomaly polynomials to geometric characteristic classes and verifies the inflow cancellation in concrete Type IIB orientifold setups. It confirms that neutral sector anomalies align with self-dual tensor inflow and charged sector anomalies with chiral spinor inflow, fixing the coupling constants in key models such as Type I theory and K3 orientifolds. The results provide a robust, general framework for local anomaly cancellation in orientifolds, including considerations of twisted sectors and Calabi-Yau embeddings.

Abstract

We derive the general form of the anomaly for chiral spinors and self-dual antisymmetric tensors living on D-brane and O-plane interesections, using both path-integral and index theorem methods. We then show that the anomalous couplings to RR forms of D-branes and O-planes in a general background are precisely those required to cancel these anomalies through the inflow mechanism. This allows, for instance, for local anomaly cancellation in generic orientifold models, the relevant Green-Schwarz term being given by the sum of the anomalous couplings of all the D-branes and O-planes in the model.