MODIFIED GRAVITY · Modifying gravity with large or infinite extra dimensions: understanding foundations and phenomenology

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Project objective

This project is devoted to understanding gravitational physics, and is motivated by both theory and experiment. From experiment, we have supernova data that suggests we should modify gravity in the infra-red. This is difficult to do without introducing problems such as ghosts, vDVZ discontinuities and strong coupling. We intend to develop models and check their consistency. Specifically, we propose to develop the phenomenology of the asymmetric brane model, extending previous results to include non-trivial Gauss-Bonnet coupling in the extra dimension. We also intend to examine the impact of asymmetry on the strong coupling problem in DGP gravity, as well as the issue of instabilities on self accelerating branes. An asymmetric generalisation of the GRS model will also be studied. From theory, we have strings. These represent our best candidate for a quantum theory of gravity. Since strings live in 10 dimensions, it is vital we understand gravity in more than 4 dimensions. To this end, we will study branes of higher co-dimension. We will identify key patterns in the structure of junction conditions, and hope to find non-trivial solutions, in particular cosmological ones that could model our universe. We will also study higher dimensional black holes . Black holes gravitate so strongly they lie at the interface of classical and quantum" gravity. We will investigate the stability of the black ring in five dimensional General Relativity. We will also attempt to find any non-trivial extensions to Lovelock gravities, aswell as an exact black string solution in Gauss-Bonnet gravity. The area formula for the entropy of black holes suggests that gravity is "holographic" in nature. We will investigate this from a braneworld perspective. We will study braneworld holography in a black ring background. We will also derive the Hubble entropy bound on a brane, with a view to understanding the behaviour of the CFT on a brane in a black hole bulk."

Original text from CORDIS.

Participants

• LABORATOIRE DE PHYSIQUE THEORIQUE, UNIVERSITE PARIS-SUDCoordinatorCity levelFrance

Links

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