Radion dynamics in the Multibrane Randall-Sundrum Model

TL;DR

This paper investigates the behavior of the radion field in an extended Randall-Sundrum model with an intermediate brane, analyzing linearized Einstein equations and the implications for cosmological expansion.

Contribution

It extends the RS model by including an intermediate brane and analyzes the radion dynamics using the Goldberger-Wise mechanism, providing new insights into radion stability.

Findings

A unique radion field is identified in the extended setup.

The analysis confirms radion stability under the extended configuration.

Brief discussion on the impact on cosmological expansion.

Abstract

The radion equilibrium in the Randall-Sundrum (RS) model is guaranteed by the back-reaction of a bulk scalar field. In this paper we study an extended scenario, where an intermediate brane exists in addition to the two branes at the fixed points, due to the discontinuity of bulk cosmology constants in two spatial regions. We conducted a complete analysis of the linearized Einstein's equations after applying the Goldberger-Wise mechanism. Our result elucidates that in the presence of nonfixed point branes under the rigid assumption, a unique radion field is conjectured as legitimate in the RS metric perturbation. The cosmological expansion in this setup is briefly discussed.