Modified gravity with negative and positive powers of the curvature: unification of the inflation and of the cosmic acceleration

Abstract

The modified gravity, which eliminates the need for dark energy and which seems to be stable, is considered. The terms with positive powers of the curvature support the inflationary epoch while the terms with negative powers of the curvature serve as effective dark energy, supporting current cosmic acceleration. The equivalent scalar-tensor gravity may be compatible with the simplest solar system experiments.

23 pages, 3 figures, discussion is extended, references added, version to appear in PRD