Beyond the Standard Model: Cosmology Explored with Higher Order Gravity

We present an extension of General Relativity by adding an infinite tower of higher order curvature invariants to the Einstein-Hilbert action. The presence of an inflationary epoch is a natural, almost unavoidable, consequence of this modification. No additional fields besides the metric are required. The period of exponential growth of the scale factor is gracefully connected with standard late-time ΛCDM cosmology. When we rewrite the theory in terms of two energy scales, it is possible to reproduce the late-time acceleration observed in the universe. The evolution is consistent with the acceleration provided by the cosmological constant at low redshift.