Screening bulk curvature in the presence of large brane tension

TL;DR

This paper investigates a mechanism to screen extrinsic curvature in a 5D cascading gravity model with large brane tension, simplifying higher-dimensional dark energy models, but encounters ghost instabilities depending on tension sign.

Contribution

It introduces a screening mechanism that keeps the bulk Riemann-flat in the presence of large brane tension, facilitating generalization of dark energy models to higher codimensions.

Findings

Screening mechanism effectively neutralizes extrinsic curvature.

Ghost instabilities arise for positive tension.

Ghost-free conditions are achievable with sufficiently small negative tension.

Abstract

We study a flat brane solution in an effective 5D action for cascading gravity and propose a mechanism to screen extrinsic curvature in the presence of a large tension on the brane. The screening mechanism leaves the bulk Riemann-flat, thus making it simpler to generalize large extra dimension dark energy models to higher codimensions. By studying an action with cubic interactions for the brane-bending scalar mode, we find that the perturbed action suffers from ghostlike instabilities for positive tension, whereas it can be made ghost-free for sufficiently small negative tension.