A Signature of Higher Dimensions at the Cosmic Singularity
Abstract
In this thesis we study the dynamics of higherdimensional gravity in a universe emerging from a brane collision. We develop a set of powerful analytic methods which, we believe, render braneworld cosmological perturbation theory solvable. Our particular concern is to determine the extent to which the fourdimensional effective theory accurately captures the higherdimensional dynamics about the cosmic singularity. We begin with an overview of the generation of primordial density perturbations, both in inflation and in the ekpyrotic mechanism, followed by an introduction to braneworld cosmology. A simple derivation of the lowenergy effective action for braneworlds is presented, highlighting the role of conformal invariance. We then solve for cosmological perturbations in a fivedimensional background consisting of two separating or colliding boundary branes, as an expansion in the collision rapidity. We show that the fourdimensional effective description fails at first nontrivial order in this expansion, and highlight the implications for cosmology. Finally, we extend our methods to find a colliding brane solution of heterotic Mtheory.
 Publication:

Ph.D. Thesis
 Pub Date:
 December 2006
 arXiv:
 arXiv:hepth/0612008
 Bibcode:
 2006PhDT.......286M
 Keywords:

 High Energy Physics  Theory;
 High Energy Physics  Theory
 EPrint:
 Author's PhD thesis