The dynamics of scalar-tensor cosmology from RS two-brane model

TL;DR

This paper analyzes the scalar-tensor cosmology derived from the Randall-Sundrum two-brane model, focusing on the radion field dynamics, stability conditions, and constraints on dark radiation within a low-energy approximation.

Contribution

It provides a first integral for the brane metric equations and explores radion stabilization and dark radiation constraints using phase space analysis.

Findings

Radion can be stabilized at finite values with negative matter densities.

Constraints on dark radiation are estimated within the model.

Phase space analysis reveals convergence towards general relativity.

Abstract

We consider Randall-Sundrum two-brane cosmological model in the low energy gradient expansion approximation by Kanno and Soda. It is a scalar-tensor theory with a specific coupling function. We find a first integral of equations for the A-brane metric and estimate constraints for the dark radiation term. We perform a complementary analysis of the dynamics of the scalar field (radion) using phase space methods and examine convergence towards the limit of general relativity. We find that it is possible to stabilize the radion at a finite value with suitable negative matter densities on the B-brane.