Stability of multibrane models

TL;DR

This paper analyzes the stability of multibrane models with warped extra dimensions, deriving conditions for stability based on the radion spectrum, extending previous 2-brane analyses to models with multiple branes.

Contribution

It provides the first comprehensive stability criteria for multibrane models by analyzing the radion spectrum and its relation to brane configurations.

Findings

Derived necessary and sufficient conditions for stability of multibrane models.

Established the link between radion mass spectrum and model stability.

Discussed properties of radions and their relation to brane distances.

Abstract

Multibrane 5-dimensional models with a warped extra spatial dimension compactified on an $S^1/\mathbb{Z}_2$ orbifold are investigated. The Goldberger-Wise field, with appropriate bulk and brane potentials, is utilized to fix the brane positions. However, not all configurations with fixed brane positions are stable. Stability against small scalar perturbations of the metric and the Goldberger-Wise field was so far analyzed only for 2-brane models. Generalization of such analysis for multibrane models is the main subject of the present work. Stability of brane configurations is closely related to the spectrum of radions: namely, the existence of any tachyonic radion indicates instability, while models with positive squared masses for all radions are stable. The necessary and sufficient conditions for each of these possibilities are derived for multibrane models and constitute the main result of this paper. Additionally, some properties of radions, particularly their relation to distances between and along branes, are discussed.