Bouncing brane cosmologies from warped string compactifications

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Published 12 March 2003 Published under licence by IOP Publishing Ltd
, , Citation Shamit Kachru and Liam McAllister JHEP03(2003)018 DOI 10.1088/1126-6708/2003/03/018

1126-6708/2003/03/018

Abstract

We study the cosmology induced on a brane probing a warped throat region in a Calabi-Yau compactification of type-IIB string theory. For the case of a BPS D3-brane probing the Klebanov-Strassler warped deformed conifold, the cosmology described by a suitable brane observer is a bouncing, spatially flat Friedmann-Robertson-Walker universe with time-varying Newton's constant, which passes smoothly from a contracting to an expanding phase. In the Klebanov-Tseytlin approximation to the Klebanov-Strassler solution the cosmology would end with a big crunch singularity. In this sense, the warped deformed conifold provides a string theory resolution of a spacelike singularity in the brane cosmology. The four-dimensional effective action appropriate for a brane observer is a simple scalar-tensor theory of gravity. In this description of the physics, a bounce is possible because the relevant energy-momentum tensor can classically violate the null energy condition.

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10.1088/1126-6708/2003/03/018