On effective actions of non-BPS branes and their higher derivative corrections

TL;DR

This paper derives effective actions for non-BPS branes by analyzing string S-matrix elements, revealing higher derivative corrections and emphasizing the importance of internal CP factors for consistency between string theory and field theory.

Contribution

It provides the first detailed derivation of higher derivative corrections to tachyon DBI and Wess-Zumino actions for non-BPS branes, including the role of internal CP factors.

Findings

Exact match between string and field theory tachyon poles when CP factors are included.

Identification of specific higher derivative couplings in the effective action.

Clarification of the role of tachyon vertex operator pictures and internal CP matrices.

Abstract

By calculating various disk level S-matrix elements and studying in details their momentum expansions, we have extracted some of the couplings in tachyon DBI action and Wess-Zumino terms of the non-BPS branes, and their higher derivative corrections. In particular, we have found that there is exact consistency between field theory and string theory tachyon pole of S-matrix element of one RR and three tachyons provided that one takes into account the fact that the tachyon vertex operator in 0 picture to be along the Pauli matrix $\sigma_1$ whereas the tachyon in -1 picture to be along the $\sigma_2$ direction. This internal CP factors should be included in the tachyon DBI part of the effective action.