A 6-D Brane World Model

TL;DR

This paper develops a six-dimensional brane world model with periodic and compact extra dimensions, deriving static and non-static solutions, analyzing brane tensions, and studying the stability of the radion field in different spacetime geometries.

Contribution

It introduces a novel 6D brane world setup with exact solutions and stability analysis, extending previous 5D models to higher dimensions without requiring additional fine-tuning.

Findings

Static solutions require brane tension tuning similar to 5D models.

Non-static solutions can fix inter-brane distance and include various tension configurations.

De Sitter solutions are unstable; Anti de Sitter solutions are stable.

Abstract

We consider a 6D space-time which is periodic in one of the extra dimensions and compact in the other. The periodic direction is defined by two 4-brane boundaries. Both static and non-static exact solutions, in which the internal spacetime has constant radius of curvature, are derived. In the case of static solutions, the brane tensions must be tuned as in the 5D Randall-Sundrum model, however, no additional fine-tuning is necessary between the brane tensions and the bulk cosmological constant. By further relaxing the sole fine-tuning of the model, we derive non-static solutions, describing de Sitter or Anti de Sitter 4D spacetimes, that allow for the fixing of the inter-brane distance and the accommodation of pairs of positive-negative and positive-positive tension branes. Finally, we consider the stability of the radion field in these configurations by employing small, time-dependent perturbations around the background solutions. In analogy with results drawn in 5 dimensions, the solutions describing a de Sitter 4D spacetime turn out to be unstable while those describing an Anti de Sitter geometry are shown to be stable.