Dark energy cosmologies with an equation of state parameter w less than −1 are often found to violate the null energy condition and show unstable behaviour. A solution to this problem may require the existence of a consistent effective theory that violates the null energy condition only momentarily and does not develop any instabilities or other pathological features for a late time cosmology. ...

Although the Gauss-Bonnet term is a topological invariant for general relativity, it couples naturally to a quintessence scalar field, modifying gravity at solar system scales. We determine the solar system constraints due to this term by evaluating the post-Newtonian metric for a distributional source. We find a mass dependent, 1/r correction to the Newtonian potential, and also deviations fro...

An iterative construction of higher order Einstein tensors for a maximally GaussBonnet extended gravitational Lagrangian was introduced in a previous paper. Here the formalism is extended to non-factorisable metrics in arbitrary (d + 1) dimensions in the presence of superposed Gauss-Bonnet terms. Such a generalisation turns out to be remarkably convenient and elegant. Having thus obtained the v...

The (n+1)-dimensional Einstein-Gauss-Bonnet (EGB) model is considered. For diagonal cosmological metrics the equations of motion are written as a set of Lagrange equations with the Lagrangian containing two “minisuperspace” metrics on R : a 2-metric of pseudo-Euclidean signature and a Finslerian 4-metric that is proportional to n-dimensional Berwald-Moor 4-metric. When a synchronous time variab...

In the Randall-Sundrum (RS) brane-world model a singular delta-function source is matched by the second derivative of the warp factor. So one should take possible curvature corrections in the effective action of the RS models in a Gauss-Bonnet (GB) form. We present a linearized treatment of gravity in the RS brane-world with the Gauss-Bonnet modification to Einstein gravity. We give explicit ex...

The d-dimensional string generated gravity models lead to Einstein-Maxwell equations with quadratic order correction term called the Gauss-Bonnet term. We calculate the quasinormal modes for the d-dimensional charged black hole in the framework of this model. The quasinormal spectrum essentially depends upon the Gauss-Bonnet coupling parameter α which is related to the string scale, and is tota...

In this paper, we prove the following two results: First, we study a class of conformally invariant operators P and their related conformally invariant curvatures Q on even-dimensional Riemannian manifolds. When the manifold is locally conformally flat(LCF) and compact without boundary, Q-curvature is naturally related to the integrand in the classical Gauss-Bonnet-Chern formula, i.e., the Pfaf...