Pomerons and BCFW recursion relations for strings on D-branes

TL;DR

This paper develops pomeron vertex operators for strings with D-branes, explores BCFW recursion relations in this context, and analyzes scattering amplitudes and Regge behavior involving D-branes, revealing novel features due to defects.

Contribution

It introduces pomeron vertices for strings on D-branes and extends BCFW recursion relations to defect settings, including single particle shifts and mixed open-closed string amplitudes.

Findings

Superstring amplitudes on D-branes obey BCFW recursion relations.

Novel BCFW shifts include single particle momentum shifts due to broken momentum conservation.

The eikonal Regge regime conjecture is examined in the presence of D-branes.

Abstract

We derive pomeron vertex operators for bosonic strings and superstrings in the presence of D-branes. We demonstrate how they can be used in order to compute the Regge behavior of string amplitudes on D-branes and the amplitude of ultrarelativistic D-brane scattering. After a lightning review of the BCFW method, we proceed in a classification of the various BCFW shifts possible in a field/string theory in the presence of defects/D-branes. The BCFW shifts present several novel features, such as the possibility of performing single particle momentum shifts, due to the breaking of momentum conservation in the directions normal to the defect. Using the pomeron vertices we show that superstring amplitudes on the disc involving both open and closed strings should obey BCFW recursion relations. As a particular example, we analyze explicitly the case of 1 -> 1 scattering of level one closed string states off a D-brane. Finally, we investigate whether the eikonal Regge regime conjecture holds in the presence of D-branes.