Chern-Simons Terms on Noncommutative Branes

TL;DR

This paper extends the Chern-Simons couplings to noncommutative D-branes, demonstrating their relation to Myers terms and proposing couplings for unstable branes, with implications for tachyon condensation.

Contribution

It provides a background-independent formulation of noncommutative Chern-Simons terms and connects them to Myers effects and tachyon condensation on unstable branes.

Findings

Noncommutative Chern-Simons terms map to Myers terms.

Proposed couplings for unstable non-BPS branes.

Tachyon condensation reproduces expected Myers terms.

Abstract

We write down couplings of the fields on a single BPS Dp-brane with noncommutative world-volume coordinates to the RR-forms in type II theories, in a manifestly background independent way. This generalises the usual Chern-Simons action for a commutative Dp-brane. We show that the noncommutative Chern-Simons terms can be mapped to Myers terms on a collection of infinitely many D-instantons. We also propose Chern-Simons couplings for unstable non-BPS branes, and show that condensation of noncommutative tachyons on these branes leads to the correct Myers terms on the decay products.