Kinetic axion dark matter in string corrected f (R) gravity

Under the main assumption that the axion scalar field mainly composes the dark matter in the Uni-verse, in this paper we shall extend the formalism of kinetic axion R2 gravity to include Gauss-Bonnet terms non-minimally coupled to the axion field. As we demonstrate, this non-trivial Gauss-Bonnet term has dramatic effects on the inflationary phenomenology and on the kinetic axion scenario. Specifically, in the context of our formalism, the kinetic axion ceases to be kinetically dominated at the end of the inflationary era, since the condition phi similar or equal to 0 naturally emerges in the theory. Thus, unlike the case of kinetic axion R2 gravity, the Gauss-Bonnet corrected kinetic axion R2 gravity leads to an inflationary era which is not further extended and the reheating era commences right after the inflationary era, driven by the R2 fluctuations.(c) 2023 Elsevier B.V. All rights reserved.