D-brane scattering and annihilation

TL;DR

This paper investigates brane-brane and brane-antibrane collisions in string theory, showing that under certain conditions, they can pass through each other despite tachyonic instabilities, with implications for string cosmology.

Contribution

It provides a detailed analysis of brane collision dynamics at small impact parameters, incorporating tachyon effects and T-duality, and discusses implications for string-inspired inflation models.

Findings

Branes can pass through each other with low annihilation probability.

Tachyon presence does not necessarily lead to annihilation at small impact parameters.

Results are relevant for stringy inflation scenarios involving moving branes.

Abstract

We study the dynamics of parallel brane-brane and brane-antibrane scattering in string theory in flat spacetime, focusing on the pair production of open strings that stretch between the branes. We are particularly interested in the case of scattering at small impact parameter $b < l_s$, where there is a tachyon in the spectrum when a brane and an antibrane approach within a string length. Our conclusion is that despite the tachyon, branes and antibranes can pass through each other with only a very small probability of annihilating, so long as $g_s$ is small and the relative velocity $v$ is neither too small nor too close to 1. Our analysis is relevant also to the case of charged open string production in world-volume electric fields, and we make use of this T-dual scenario in our analysis. We briefly discuss the application of our results to a stringy model of inflation involving moving branes.