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arXiv · 1810.05536

Inflation with $R^2$ term in the Palatini formalism

Vera-Maria Enckell·Kari Enqvist·Syksy Rasanen·Lumi-Pyry Wahlman
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Abstract

We study scalar field inflation in $F(R)$ gravity in the Palatini formulation of general relativity. Unlike in the metric formulation, in the Palatini formulation $F(R)$ gravity does not introduce new degrees of freedom. However, it changes the relations between existing degrees of freedom, including the inflaton and spacetime curvature. Considering the case $F(R)=R+\alpha R^2$, we find that the $R^2$ term decreases the height of the effective inflaton potential. By adjusting the value of $\alpha$, this mechanism can be used to suppress the tensor-to-scalar ratio $r$ without limit in any scalar field model of inflation without affecting the spectrum of scalar perturbations.

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Vera-Maria Enckell, Kari Enqvist, Syksy Rasanen, Lumi-Pyry Wahlman. 2018-10-11. Inflation with $R^2$ term in the Palatini formalism. https://doi.org/10.1088/1475-7516%2F2019%2F02%2F022

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