Rolling tachyons for separated brane-antibrane systems

TL;DR

This paper analyzes tachyon condensation between separated brane-antibrane pairs in superstring theory, demonstrating conformal solutions for certain rolling tachyon configurations and constraining effective actions.

Contribution

It provides an exact conformal boundary conformal field theory solution for separated brane-antibrane systems and explores conditions for conformality in rolling tachyon scenarios.

Findings

The simple rolling tachyon solution is conformal and exact.

Time-reversal-symmetric solutions are not conformal.

Results constrain space-time effective actions for brane-antibrane systems.

Abstract

We consider tachyon condensation between a D-brane and an anti-D-brane in superstring theory, when they are separated in their common transverse directions. A simple rolling tachyon solution, that describes the time evolution of the process, is studied from the point of view of boundary conformal field theory. By computing the boundary beta-functions of the system, one finds that this theory is conformal, hence corresponds to an exact solution of the string theory equations of motion. By contrast, the time-reversal-symmetric rolling tachyon is not conformal. These results put constraints on the space-time effective actions for the system.