The radion in brane cosmology

TL;DR

This paper investigates the dynamics of the radion, the interbrane distance, in brane cosmology, deriving its equations of motion and analyzing fluctuations in a symmetric two-brane setup.

Contribution

It derives the non-linear equations of motion for the radion in a symmetric two-brane model and analyzes its fluctuations, providing insights into brane cosmology dynamics.

Findings

Derived non-linear radion equations of motion.

Analyzed radion fluctuations in specific cases.

Provided solutions for radion dynamics.

Abstract

We consider the homogeneous cosmological radion, which we define as the interbrane distance in a two brane and $Z_2$ symmetrical configuration. In a coordinate system where one of the brane is at rest, the junction conditions for the second (moving) brane give directly the (non-linear) equations of motion for the radion. We analyse the radion fluctuations and solve the non-linear dynamics in some simple cases of interest.