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Braneworld dynamics in Einstein-Gauss-Bonnet gravity

We discuss the cosmological evolution of a braneworld in five dimensional Gauss-Bonnet gravity. Our discussion allows the fifth (bulk) dimension to be space-like as well as time-like. The resulting equations of motion have the form of a cubic equation in the (H^2,(ρ+σ)^2) plane, where σis the brane tension and ρis the matter density. This allows us to conduct a comprehensive pictorial analysis of cosmological evolution for the Gauss-Bonnet brane. The many interesting properties of this braneworld include the possibility of accelerated expansion at late times. For a finite region in parameter space the accelerated expansion can be phantom-like so that w < -1. At late times, this branch approaches de Sitter space (w = -1) and avoids the big-rip singularities usually present in phantom models. For a time-like extra dimension the Gauss-Bonnet brane can bounce and avoid the initial singularity.