D-brane anomaly inflow revisited

TL;DR

The paper addresses how axial and gravitational anomalies on brane world-volumes are canceled by inflow from RR topological couplings, emphasizing the regularity of Bianchi identities and smeared magnetic sources. By combining FHMM-style regularization with a unified treatment of Chern-Simons couplings, it shows inflow for all D-branes (including self-dual D3) and I-brane setups, and extends the analysis to orientifold planes with a universal, type-independent inflow that matches closed-string one-loop results. The key contributions include (i) resolving the D3 inflow puzzle, (ii) demonstrating that inflow is largely independent of the particular CS form up to local counterterms, and (iii) deriving consistent orientifold CS couplings and a Green-Schwarz tadpole framework that ensure complete anomaly cancellation. These results provide a robust, broadly applicable framework for anomaly cancellation in string-theoretic brane configurations, with potential implications for model-building and dualities.

Abstract

Axial and gravitational anomaly of field theories, when embedded in string theory, must be accompanied by canceling inflow. We give a self-contained overview for various world-volume theories, and clarify the role of smeared magnetic sources in I-brane/D-brane cases. The proper anomaly descent of the source, as demanded by regularity of RR field strengths H's, turns out to be an essential ingredient. We show how this allows correct inflow to be generated for all such theories, including self-dual cases, and also that the mechanism is now insensitive to the choice between the two related but inequivalent forms of D-brane Chern-Simons couplings. In particular, SO(6)_R axial anomaly of d=4 maximal SYM is canceled by the inflow onto D3-branes via the standard minimal coupling to C_4. We also propose how, for the anomaly cancelation, the four types of Orientifold planes should be coupled to the spacetime curvatures, of which conflicting claims existed previously.