# On All-Order Higher-Point $\text{D}p$-$\overline{\text{D}p}$ Effective Actions

## TL;DR

This paper derives all-order corrections to the effective action of D-brane-anti D-brane systems in Type II string theory, revealing new couplings and a series representation applicable to complex six-point amplitudes.

## Contribution

It introduces a comprehensive all-order $ ext{α'}$ expansion for D-brane-anti D-brane effective actions, including new couplings and a series representation for six-point superstring amplitudes.

## Key findings

- Derived all-order $ ext{α'}$ corrections to D-brane-anti D-brane actions.
- Identified new effective couplings involving open and closed string states.
- Developed a series representation applicable to general six-point superstring amplitudes.

## Abstract

In this paper we derive a class of contributions to all orders in $\alpha'$ to the effective action of D-brane-anti D-brane systems in Type II String Theory, considering an amplitude involving a closed-string Ramond-Ramond state and four open-string states: two tachyons, a scalar and a gauge boson. This type of amplitude arises in both Type IIA and Type IIB strings, and reveals a number of new effective couplings. Furthermore, we derive a series representation for the result that goes beyond a factorized limit that was recently studied, and which is expected to apply to more general six-point amplitudes of superstrings, including external fermions.