Braneworld Isotropization and Magnetic Fields

TL;DR

This paper investigates how anisotropic magnetic brane universes rapidly become isotropic through energy dissipation into the bulk, providing insights into braneworld dynamics and potential observational signatures.

Contribution

It demonstrates the process of braneworld isotropization in magnetic Bianchi I models and links bulk energy flow to dual CFT particle production, enhancing understanding of anisotropic brane behavior.

Findings

Efficient dissipation of anisotropy on the brane.

Anisotropic energy carried into the bulk by gravitons.

Evidence of over-produced particles potentially observable.

Abstract

We consider a magnetic Bianchi I braneworld, embedded in between two Schwarzschild-AdS spacetimes, boosted equal amounts in opposite directions and compare them to the analagous solution in four-dimensional General Relativity. The efficient dissipation of anisotropy on the brane is explicitly demonstrated, a process we dub braneworld isotropization. From the bulk point of view, we attribute this to anisotropic energy being carried into the bulk by hot gravitons leaving the brane. From the brane point of view this can be interpreted in terms of the production of particles in the dual CFT. We explain how this result enables us to gain a better understanding of the behaviour of anisotropic branes already studied in the literature. We also show how there is evidence of particles being over-produced, and comment on how this may ultimately provide a possible observational signature of braneworlds.