paper

On the number of -folds in the Jordan and Einstein frames

arXiv:2111.09677 · doi:10.1140/epjp/s13360-022-02853-x

Abstract

We investigate how inflationary predictions are affected by the difference in the number of -folds between the Jordan and Einstein frames. We study several test models in relation to a Jordan frame defined by the common Higgs-inflation-like non-minimal coupling to gravity and consider two different formulations of gravity: metric and Palatini. We find that the difference is quite contained in case of a metric Jordan frame while can be quite remarkable in case of a Palatini Jordan frame. We also discuss a way to overcome the discrepancy by introducing a frame invariant physical distance and a consequently frame invariant number of -folds.

21 pages, 4 figures, matches the published version

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