1 Excerpt

- Published 2009

For the description of the Universe expansion, compatible with observational data, a model of Lovelock gravity with dilaton is investigated. D-dimensional space with 3and (D-4)-dimensional maximally symmetric subspaces is considered. Space without matter and space with perfect fluid are under test. In various forms of the theory (third order without dilaton and second order with dilaton and without it) there are obtained stationary, power-law, exponential and exponent-of-exponent form cosmological solutions. Last two forms include solutions which are clear to describe accelerating expansion of 3-dimensional subspace. Also there is a set of solutions describing cosmological expansion which does not tend to isotropization in the presence of matter. Keywoerds: Cosmology, Dilation, Lovelock gravity. INTRODUCTION At present time there are numerous observational data known to be incompatible with the Standard Cosmological Model. On the one hand, accelerating expansion observations from supernovae type Ia [1] and gravitational lensing [2] allow us to calculate metric tensor. On the other hand, evaluating the amount of visible matter, energymomentum tensor can be obtained. However, it is impossible to satisfy Einstein equations by plugging in these values. Then there are two possibilities: there is a great amount of invisible matter or Einstein equations are not true. These possibilities point out two approaches to the problem: to develop theories of dark matter and dark energy or to modify theory of gravity. In the present article we deal with the second approach. Modified gravity has its beginning in 1920-th. The most popular theories are Brans-Dicke theory [3, 4], Lovelock gravity [5] and f(R) -gravity (see, e. g. [6]). However, for a long time these theories were not useful for explanation of experimental data incompatible with general relativity. Here we will investigate a scalar-tensor extension of Lovelock gravity --Lovelock gravity with dilaton which might have its origin in low-energy limit of string theory. Lovelock gravity with dilaton contains scalar field (dilaton), metric tensor μ g , matter fields I and is described (in D -dimensional space-time) by Lagrangian *Address correspondence to this author at the Tomsk State University, 634050, Russia, Tomsk, Lenin prosp., 36, Tel: +7 915 2374648; Fax: +7 (3822) 52-17-93; E-mail: ikirnos@mail.ru where m = 1 2 D, if D is even, m = 1 2 (D 1), if D is odd, p ( ) , V ( ) are arbitrary functions of dilaton, k k μ μ L

@inproceedings{Kirnos2009AcceleratingCI,
title={Accelerating Cosmologies in Lovelock Gravity with Dilaton},
author={Ilya V. Kirnos and Andrey N. Makarenko},
year={2009}
}