Tabletop potentials for inflation from f(R) gravity

Abstract We show that a large class of modified gravity theories (MOG) with the Jordan-frame Lagrangian f ( R ) translate into scalar-field (scalaron) models hilltop potentials in Einstein frame. (A rare exception to this rule is provided by Starobinsky model for which corresponding scalaron potential plateau-like ϕ > 0.) find MOG featuring two distinct mass scales lead have flattened hilltop, or tabletop . Inflationary evolution agrees very well CMB observations. Tabletop therefore provide new and compelling MOG-based inflationary models. By contrast, single scale generally correspond steep fail reproduce power spectrum. hilltop/tabletop can proceed alternative directions: towards stable point at small describing observable universe, asymptotic region The we examine several properties including fact become asymptotically vanishing, G eff → 0, infinite finite values scalar curvature A universe evolving vanishing will either run 'Big-Rip' singularity, inflate eternally.