Gravitational Perturbations of a Six Dimensional Self-Tuning Model

TL;DR

This paper analyzes gravitational perturbations in a six-dimensional self-tuning brane model, finding that all problematic light scalar modes are eliminated by boundary conditions, suggesting the model may not self-tune.

Contribution

It provides an analytic solution for gravitational perturbations in a 6D self-tuning model and shows that no light scalar modes remain at linear order.

Findings

All potential light scalar modes are eliminated by boundary conditions.

The model does not contain light scalars at linear order.

Implication that the model may not self-tune.

Abstract

We investigate gravitational perturbations in a compact six-dimensional self-tuning brane model. We specifically look for analytic solutions to the perturbed Einstein equations that correspond in four-dimensions to massless or approximately massless scalars coupled to matter on the brane. The presence of such modes with gravitational couplings would be phenomenologically unacceptable. The most general solution for all such modes is obtained, but it is found that they are all eliminated by the boundary conditions. Our main result is that to linear order in perturbation theory this model does not contain any light scalars. We speculate that this model does not self-tune.