Dark energy from logarithmically modified gravity and deformed Coleman-Weinberg potential

Abstract

Recent astrophysical measurements strongly suggest the existence of a missing energy component dubbed dark energy that is responsible for the current accelerated expansion of the universe. A new class of modified gravity theory is introduced which yields a universe accelerating in time and dominated by dark energy. The new modified gravity model constructed here concurrently includes a Gauss-Bonnet invariant term, barotropic fluid with a time-dependent equation of state parameter, a Coleman-Weinberg (CW) potential-like expression V(φ) = ξφm ln φn and a new Einstein-Hilbert term f(R, φ) = E(φ)R which depends on both the scalar curvature and the scalar field φ through a generic logarithmic function E(φ) = ln φ. Here m and n take different values from the standard CW potential and ξ is a real parameter. It was shown that the presence of these terms provides many useful features which are discussed in some detail.