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Covariant Galileon
Abstract We consider the recently introduced “galileon” field in a dynamical spacetime. When the galileon is assumed to be minimally coupled to the metric, we underline that both field equations ofExpand
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From k-essence to generalised Galileons
We determine the most general scalar field theories which have an action that depends on derivatives of order two or less, and have equations of motion that stay second order and lower on flatExpand
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Imperfect Dark Energy from Kinetic Gravity Braiding
We introduce a large class of scalar-tensor models with interactions containing the second derivatives of the scalar field but not leading to additional degrees of freedom. These models exhibitExpand
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Brane cosmological evolution in a bulk with cosmological constant
Abstract We consider the cosmology of a “3-brane universe” in a five dimensional (bulk) space-time with a cosmological constant. We show that Einstein's equations admit a first integral, analogous toExpand
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Non-conventional cosmology from a brane-universe
Abstract We consider “brane universes”, where energy density is confined to four-dimensional hypersurfaces (three-branes) whereas one extra compact dimension is felt by gravity only. We show that theExpand
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Cosmology on a Brane in Minkowski Bulk
Abstract We discuss the cosmology of a 3-brane embedded in a 5D bulk space–time with a cosmological constant when an intrinsic curvature Ricci scalar is included in the brane action. After derivingExpand
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Accelerated universe from gravity leaking to extra dimensions
We discuss the idea that the accelerated universe could be the result of gravitational leakage into extra dimensions over Hubble distances rather than the consequence of a nonzero cosmologicalExpand
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Generalized Galileons: All scalar models whose curved background extensions maintain second-order field equations and stress tensors
We extend to curved backgrounds all flat-space scalar field models that obey purely second-order equations, while maintaining their second-order dependence on both field and metric. This extensionExpand
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Ghosts, strong coupling and accidental symmetries in massive gravity
We show that the strong self-interaction of the scalar polarization of a massive graviton can be understood in terms of the propagation of an extra ghostlike degree of freedom, thus relating strongExpand
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Nonperturbative Continuity in Graviton Mass versus Perturbative Discontinuity
We address the question whether a graviton could have a small nonzero mass. The issue is subtle for two reasons: there is a discontinuity in the mass in the lowest tree-level approximation, and,Expand
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