Mild Quasilocal Non-Gaussianity as a Signature of Modified Gravity During Inflation

Abstract

We show that modifications of Einstein gravity during inflation could leave potentially measurable imprints on cosmological observables in the form of non-Gaussian perturbations. This is due to the fact that these modifications appear in the form of an extra field that could have nontrivial interactions with the inflaton. We show it explicitly for the case R + α R 2 , where nearly scale-invariant non-Gaussianity at the level of f NL ≈ − ( 1 to 30 ) can be obtained, in a quasilocal configuration.