D-brane anomaly inflow revisited

TL;DR

This paper revisits D-brane anomaly inflow, clarifying the role of magnetic sources and anomaly descent, ensuring correct inflow for various theories, including self-dual cases, and proposes how orientifold planes couple to spacetime curvatures.

Contribution

It provides a self-contained overview of D-brane anomaly inflow, emphasizing the importance of anomaly descent and source regularity, and clarifies coupling mechanisms for orientifold planes.

Findings

Proper anomaly descent is essential for correct inflow.

The mechanism is insensitive to different D-brane Chern-Simons couplings.

SO(6)_R axial anomaly in d=4 SYM is canceled via inflow onto D3-branes.

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.