Regular collision of dilatonic inflating branes

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