Dark energy from “extended modified gravity” and Gauss–Bonnet invariant term

Abstract

There exists strong observational evidence for dark energy. The work done in this letter is just a new kind of extended modified gravity theory to yield a universe accelerating in time and dominated by dark energy. The extended modified gravity constructed here includes simultaneously a Gauss–Bonnet invariant term and a new Einstein–Hilbert term f(R,φ)=E(φ)R−μ R −1 which depends on both the scalar curvature and on the scalar field φ through a generic function E(φ). It is shown that the presence of both terms provides remarkably many interesting features, which are discussed in some detail.