The Fate of the Radion in Models with Metastable Graviton

TL;DR

This paper investigates models with localized gravity, emphasizing the crucial role of the radion mode, and explains how negative tension branes affect energy positivity and Einstein gravity recovery at intermediate scales.

Contribution

It introduces the radion mode into models with localized gravity and analyzes its impact on energy positivity and gravitational behavior.

Findings

Radion mode is essential in models with localized gravity.

Negative tension branes induce negative kinetic terms for the radion.

Recovery of Einstein gravity at intermediate distances is linked to radion effects.

Abstract

We clarify some general issues in models where gravity is localized at intermediate distances. We introduce the radion mode, which is usually neglected, and we point out that its role in the model is crucial. We show that the brane bending effects discussed in the literature can be obtained in a formalism where the physical origin is manifest. The model violates positivity of energy due to a negative tension brane, which induces a negative kinetic term for the radion. The very same effect that violates positivity is responsible for the recovery of conventional Einstein gravity at intermediate distances.