Some Scenarios of Cosmological Revolution in Polynomial - Exponential f(R) Modified Theory of Gravity

In this paper, we study the evolution of the universe in a modified theory of gravity considering a Lagrangian density f(R) which is a polynomial - exponential function of the scalar curvature R in the Einstein - Hilbert action in vacuum. The field equation obtained from the modified action corresponding to a Friedman-Robertson-Walker metric is highly non-linear and not simple enough to obtain an analytic solution. Therefore we use a numerical technique to study the evolution of the FRW universe. A number of evolutionary phases of the universe including the present accelerating phase are found to exist in this model of gravity. The cosmological solutions obtained here are new and interesting. The physical importance of the coupling parameters considered in the action are also discussed.