Perturbations in Regularized Lovelock Gravity

In this paper we study the perturbation theory of the recently proposed Regularized Lovelock Gravity (Glavan and Lin, 2020), on the curved Friedmann-Lemaitre-Robertson-Walker (FLRW) space-time. We provide the first order perturbation equations both in the scalar and tensor sector in the presence of an additional minimally coupled scalar field. A general expression for the velocity of gravitational waves at the generic order is inferred. Moreover, we apply the results on the study of slow-roll inflation on flat FLRW background, at second order in the Regularized Lovelock Gravity, i.e. in the presence of the Gauss-Bonnet correction only. We derive the power spectra of scalar and tensor perturbations, and provide the equations for the inflation observable quantities: the spectral indices and the tensor-to-scalar spectra ratio. (C) 2021 Elsevier B.V. All rights reserved.