Year: 2010
Type: conference-paper
Abstract: This is a brief review of applications of extended gravity theories to cosmology, in particular to the dark energy problem. Generically extensions of gravity action involve higher derivative terms, which can result in ghosts and instabilities. We consider three ways to circumvent this: Chern‐Simons terms, first order variational principle and nonlocality. We consider some recent cosmological applications within these three classes of modified gravity models avoiding introduction of extra degrees of freedom. The viable parameter space can be very efficiently bounded by taking into account cosmological constraints from all epochs in addition to bounds from Solar system tests and stability considerations. We make some new remarks concerning so called algebraic scalar‐tensor theories, biscalar reformulation of nonlocal actions involving the inverse d’Alembertian, and a possible covariant formulation holographic cosmology with nonperturbative gravity.
Source: AIP conference proceedings
DOI: 10.1063/1.3292516
Author: Tomi S. Koivisto
Institutions: Utrecht University, Heidelberg University
Language: English
Subfield: Astronomy and Astrophysics
Field: Physics and Astronomy
Domain: Physical Sciences
Open Access status: green
OpenAlex ID: W1983733249