2008/10/31 by Damien P. George, Mark Trodden, Raymond R. Volkas · 1 citation
Physics and Astronomy · #hep-ph #astro-ph #gr-qc #hep-th
paper · pdf · doi:10.1088/1126-6708/2009/02/035
published as JHEP 0902:035,2009 · 23 pages; v2 has additional references and reflects journal version
arxiv created 2009/02/13 · arxiv updated 2009/12/01
We show how to define a consistent braneworld cosmology in a model in which the brane is constructed as a field-theoretic domain wall of finite thickness. The Friedmann, Robertson-Walker metric is recovered in the region of the brane, but, remarkably, with scale factor that depends on particle energy and on particle species, constituting a breakdown of the weak equivalence principle on sufficiently small scales. This unusual effect comes from the extended nature of particles confined to a domain-wall brane, and the fact that they feel an "average" of the bulk spacetime. We demonstrate how to recover the standard results of brane cosmology in the infinitely-thin brane limit, and comment on how our results have the potential to place bounds on parameters such as the thickness of domain-wall braneworlds.