Superstring Scattering from D-Branes

TL;DR

This paper derives covariant two-point scattering amplitudes for massless closed strings from D-branes, linking them to open string amplitudes, and confirms they match extremal p-brane solutions in supergravity.

Contribution

It provides a covariant formulation of D-brane scattering amplitudes and relates them to open string amplitudes, advancing understanding of D-brane interactions in superstring theory.

Findings

Derived covariant two-point amplitudes for massless closed strings from D-branes.

Connected D-brane amplitudes to four-point open string scattering amplitudes.

Confirmed the background fields match extremal p-brane solutions.

Abstract

We derive fully covariant expressions for all two-point scattering amplitudes of two massless closed strings from a Dirichlet $p$-brane. This construction relies on the observation that there is a simple relation between these D-brane amplitudes in type II superstring theory and four-point scattering amplitudes for type I open superstrings. From the two-point amplitudes, we derive the long range background fields for the D-branes, and verify that as expected they correspond to those of extremally charged $p$-brane solutions of the low energy effective action.