Constant-roll $f(R)$ inflation compared with Cosmic Microwave Background anisotropies and swampland criteria

Abstract

Inflationary models derived from $f(R)$ gravity, where the scalaron rolls down with a constant rate from the top to the minimum of the effective potential, are considered. Specifically, we take into account three $f(R)$ models \textit{i.e.}\,Starobinsky $R^2$, $R^{2p}$ and the logarithmic corrected models. We compare the inflationary parameters derived from the models with the observational data of CMB anisotropies \textit{i.e.} the Planck and Keck/array datasets in order to find observational constraints on the parameters space. We find that although our $f(R)$ constant-roll models for $\gamma =0$ show observationally acceptable values of $r$, they do not predict favoured values of the spectral index. In particular, we have $n_s>1$ for the Starobinsky $R^2$ and $R^{2p}$ models and $0.996<n_s<0.999$ for logarithmic model. Finally, we study the models from the point of view of Weak Gravity Conjecture adopting the swampland criteria.

16 pages, 5 figures

Cited by in corpus (1)

• Swampland conjectures in hybrid metric-Palatini gravity