On Higher Derivative Terms in Tachyon Effective Actions

TL;DR

This paper reconstructs the tachyon effective action for unstable D-branes in superstring theory, demonstrating its agreement with boundary string field theory and accurately reproducing brane tensions and dynamics.

Contribution

It provides a new reconstruction of the tachyon effective action near marginal deformations, clarifying higher derivative ambiguities and matching known results from boundary string field theory.

Findings

Reconstructed tachyon effective action matches boundary string field theory results.

Exact reproduction of brane tensions and BI-action for center of mass motion.

Comments on tachyon actions in D-brane/anti-D-brane systems and bosonic string theory.

Abstract

We reconstruct the tachyon effective action for unstable D-branes in superstring theory by examining its behaviour near exactly marginal deformations, where the ambigous higher derivative terms can be eliminated. We then compare this action with that obtained in boundary string field theory and find remarkable agreement. In particular, the tension for lower dimensional branes and the BI-action for the centre of mass motion are reprodued exactly. We also comment on the action for tachyons on the kink in a D-brane/anti-D-brane system and on bosonic string theory.