Braneworlds with Curvature Corrections

By Eleftherios Papantonopoulos, National Technical University of Athens

We study the cosmology of the Randall-Sundrum brane-world where the Einstein-Hilbert action is modified by curvature correction terms: a four-dimensional scalar curvature from induced gravity on the brane, and a five-dimensional Gauss-Bonnet curvature term. The combined effect of these curvature corrections to the action removes the infinite-density big bang singularity, although the curvature can still diverge for some parameter values. A radiation brane undergoes accelerated expansion near the minimal scale factor, for a range of parameters. This acceleration is driven by the geometric effects, without an inflaton field or negative pressures. At late times, conventional cosmology is recovered. We also study the collapse of a homogeneous braneworld dust cloud in the context of the above curvature correction scenarios. In accordance to the Randall-Sundrum model, and contrary to the general relativity case, we show in all cases that the exterior spacetime on the brane is non-static.