Scalar fluctuations in dilatonic brane-worlds

TL;DR

This paper analyzes scalar fluctuations in dilatonic brane-world models, deriving the full perturbation spectrum, revealing a localized massless mode and massive modes that modify gravity at short distances.

Contribution

It provides a comprehensive derivation of scalar perturbations in dilatonic brane-worlds, including the spectrum and implications for gravity and scalar interactions.

Findings

Presence of a localized massless scalar mode acting as an effective dilaton

Massive scalar modes cause deviations from Newton's law at short distances

Corrections persist even when the dilaton coupling vanishes, as in Randall--Sundrum models

Abstract

We derive and solve the full set of scalar perturbation equations for a class of five-dimensional brane--world solutions, with a dilaton scalar field coupled to the bulk cosmological constant and to a 3-brane. The spectrum contains one localized massless scalar mode, to be interpreted as an effective dilaton on the brane, inducing long--range scalar interactions. Two massive scalar modes yield corrections to Newton's law at short distances, which persist even in the limit of vanishing dilaton (namely, in the standard Randall--Sundrum configuration).