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Résumé |
I will present a brane-world framework, based on the gauge/gravity duality, in which the four-dimensional
cosmological constant is neutralized by a dynamical self-adjustment mechanism. The model consists in a
five-dimensional Einstein-Dilaton gravity coupled to a four-dimensional brane on which ordinary
matter and gauge fields are localized. The brane position in the bulk is determined dynamically by the
junction conditions, and flat-brane solutions exist for generic values of the brane vacuum energy. A regime
with emergent 4-dimensional gravity is possible, due to the presence of an induced gravity term on
the brane. The emergent 4d graviton acquires an effective mass, and a five-dimensional regime may exist at
large and/or small scales. Analysis of scalar fluctuations allows to formulate conditions for perturbative
stability of the flat solutions, which can be met in a broad range of the model parameters. |
