Gravity in Enhanced Brane-World Models

Abstract: We generalize and extend results on the localization of gravity on Karch-Randall-Sundrum brane-worlds with positive, negative, or zero cosmological constant on the brane. We do so both from the study of bulk metric perturbations, and from their reinterpretation through brane-world holography: an induced higher-derivative theory of gravity coupled to a cut-off CFT on the brane. We then enhance these models by adding an explicit Einstein-Hilbert term on the brane action (i.e. a DGP term) and, through studying the brane position and the localization of gravity on the brane, we establish bounds for its coupling constant, beyond which the theory presents pathologies. We finally study the limit in which the brane reaches the boundary, and comment on adding further higher-derivative terms on the brane action.