Regular collision of dilatonic inflating branes

TL;DR

This paper investigates the instability in a two-brane system with a bulk scalar field causing power-law inflation, showing that the radion instability can lead to brane collision while maintaining regularity in brane quantities.

Contribution

It introduces an analysis of radion instability in inflating branes and provides both exact and low energy expansion solutions for the brane dynamics.

Findings

Radion instability can cause brane collision.

Brane quantities remain regular at collision.

Low energy expansion matches exact solutions and reveals alternative bulk metrics.

Abstract

We demonstrate that a two brane system with a bulk scalar field driving power-law inflation on the branes has an instability in the radion. We solve for the resulting trajectory of the brane, and find that the instability can lead to collision. Brane quantities such as the scale factor are shown to be regular at this collision. In addition we describe the system using a low energy expansion. The low energy expansion accurately reproduces the known exact solution, but also identifies an alternative solution for the bulk metric and brane trajectory.