Scattering higher spins off D-branes

TL;DR

This work investigates the scattering of massive higher-spin closed-string states, belonging to the leading Regge trajectory, off Dp-branes. By constructing BRST-invariant vertex operators in both bosonic and superstring theories and computing tree-level (disk) and one-loop (annulus) amplitudes, the authors reveal remarkable Regge-limit simplifications: the dominant high-energy behavior scales as $E^2$ at tree level and as $E^3$ at one loop, independent of the specific level on the leading trajectory. The results support an eikonal interpretation, showing that the one-loop amplitude factorizes as a convolution of disk amplitudes with a Reggeon vertex, consistent with unitarity restoration through Reggeized graviton exchanges. These findings bolster the all-orders Regge-eikonal picture for string-brane scattering and point to a tractable framework for exploring higher-order effects and subleading contributions for massive higher-spin states.

Abstract

We study scattering amplitudes of higher spin closed-string states off D-branes. For states in the `first Regge trajectory' we find remarkable simplifications both at tree level and at one loop. We discuss the high energy behavior in the Regge limit and comment on the validity of the eikonal approximation in this regime.