This preview has intentionally blurred sections. Sign up to view the full version.
View Full Document
Unformatted text preview: arXiv:hepth/0404011v1 2 Apr 2004 Brane World Cosmology Philippe Brax â€ , Carsten van de Bruck â€¡ and Anneâ€“Christine Davis âˆ— â€ Service de Physique ThÂ´ eorique, CEASaclay F91191, Gif/Yvette cedex, France â€¡ Department of Applied Mathematics, Astroâ€“Particle and Cosmology Group University of Sheffield, Hounsfield Road, Hicks Building Sheffield S3 7RH, United Kingdom * Department of Applied Mathematics and Theoretical Physics, Center for Mathematical Sciences, University of Cambridge, Wilberforce Road, Cambridge CB3 0WA, U.K. Email: [email protected], [email protected], [email protected] Abstract. Recent developments in the physics of extra dimensions have opened up new avenues to test such theories. We review cosmological aspects of brane world scenarios such as the Randallâ€“Sundrum brane model and twoâ€“brane systems with a bulk scalar field. We start with the simplest brane world scenario leading to a consistent cosmology: a brane embedded in an Antiâ€“de Sitter spaceâ€“time. We generalise this setting to the case with a bulk scalar field and then to twoâ€“brane systems. We discuss different ways of obtaining a lowâ€“energy effective theory for twoâ€“brane systems, such as the moduli space approximation and the lowâ€“energy expansion. A comparison between the different methods is given. Cosmological perturbations are briefly discussed as well as early universe scenarios such as the cyclic model and the bornâ€“again brane world model. Finally we also present some physical consequences of brane world scenarios on the cosmic microwave background and the variation of constants. Brane World Cosmology 2 1. Introduction Whilst theories formulated in extra dimensions have been around since the early twentieth century, recent developments have opened up new avenues which have enabled the cosmological consequences of such theories to be extracted. This, together with advances in high precision cosmological data, opens up the exciting possibility of testing and constraining extraâ€“dimensional theories for the first time. In this review we explore these developments. In the early twentieth century Kaluza and Klein [1], following Nordstrom, attempted to unify electromagnetism and gravity by proposing a theory in five spaceâ€“time dimensions, with the extra spatial dimension compactified on a circle. More recently, attempts to construct a consistent theory incorporating both quantum mechanics and gravity have been constructed in more than four dimensions, with the extra, spatial dimensions compactified. In particular superstring theories, which include both quantum theory and gravity, are only consistent in ten dimensions [2], with the extra dimensions being spatial. The usual four dimensional physics is retrieved by compactifying on a compact manifold with dimensions typically of the order of the Planck scale. This is essentially a generalisation of Kaluzaâ€“Klein theory....
View
Full Document
 Spring '08
 BALLZ
 General Relativity, The Land, Brane World Cosmology, brane world

Click to edit the document details