D-brane dynamics

TL;DR

This paper analyzes D-brane scattering, revealing that their moduli space remains flat at low velocities in toroidal compactifications and relates K3 compactifications to gauge theory, with high-velocity behavior resembling black disk absorption.

Contribution

It provides a detailed semiclassical calculation of D-brane phase shifts and explores their implications for moduli space geometry and dual gauge theories, including novel insights into ultrarelativistic regimes.

Findings

Moduli space remains flat for toroidal compactifications.

D-brane phase shift behavior resembles black disk absorption at high velocities.

The D-brane scattering features are qualitatively similar to large fundamental string scattering.

Abstract

I calculate the semiclassical phase shift ($\delta$), as function of impact parameter ($b$) and velocity ($v$), when one D-brane moves past another. From its low-velocity expansion I show that, for torroidal compactifications, the moduli space of two identical D-branes stays flat to all orders in $\alpha^\prime$. For K3 compactifications, the calculation of the D-brane moduli-space metric can be mapped to a dual gauge-coupling renormalization problem. In the ultrarelativistic regime, the absorptive part of the phase shift grows as if the D-branes were black disks of area $\sim \alpha^\prime ln{1\over 1-v^2}$. The scattering of large fundamental strings shares all the above qualitative features. A side remark concerns the intriguing duality between limiting electric fields and the speed of light.