Cascading Gravity and the Accelerated Expansion of the Universe

by Oriol Pujolas Boix

Friday 29 May 2009, 11:30 → 12:30 Europe/Zurich

Geneva University, Auditoire 234, 24 E. Ansermet

Higher dimensional models with brane-localized kinetic terms, like DGP and the Cascading Gravity model, realize consistent modifications of gravity. These models give rise to Self-Accelerated branches where the acceleration is supported by the brane kinetic terms. However, these branches have ghosts and so are irrelevant for phenomenological purposes. I will introduce a new type of `self-accelerated' solutions present in models with 6 or more dimensions. The Cascading Gravity model supports solutions of this kind and one can explicitly see that there are no ghost excitations around them. This provides the first example of consistent Lorentz-invariant modification of gravity with a healthy self-accelerated phase. We comment on the phenomenological signatures of this type of acceleration.