Cycling in the Throat

Abstract

We analyse the dynamics of a probe D3-(anti-)brane propagating in a warped string compactification, making use of the Dirac-Born-Infeld action approximation. We also examine the time dependent expansion of such moving branes from the ``mirage cosmology'' perspective, where cosmology is induced by the brane motion in the background spacetime. A range of physically interesting backgrounds are considered: AdS5, Klebanov-Tseytlin and Klebanov-Strassler. Our focus is on exploring what new phenomenology is obtained from giving the brane angular momentum in the extra dimensions. We find that in general, angular momentum creates a centrifugal barrier, causing bouncing cosmologies. More unexpected, and more interesting, is the existence of bound orbits, corresponding to cyclic universes.