Inflationary Slow-Roll Parameters in the Jordan Frame for Cosmological F(R) Gravity Models
arXiv:2508.14250
Abstract
inflationary models are analyzed without the Weyl transformation to the Einstein frame. Sufficient conditions for existence of global inflationary attractors in models are provided. Following that, the procedure for calculating inflationary observables completely in the original, Jordan, frame is given. The described procedure is used to analyze a new inflationary model (a one-parameter deformation of the Starobinsky model), which is shown to provide predictions in good agreement with the recent ACT data.
11 pages, 3 figures, v2: correction of typos, additional references added, a new figure added