Second Order Perturbations During Inflation Beyond Slow-roll

TL;DR

This paper numerically studies second order cosmological perturbations during inflation without slow-roll assumptions, analyzing the impact of potential features and providing an open-source computational tool.

Contribution

It introduces a numerical method for second order perturbations during inflation beyond slow-roll, including localized potential features, and releases an open-source solver.

Findings

Results align with slow-roll approximations where applicable

Localized potential features can break slow-roll conditions

Open-source code facilitates further research in inflationary perturbations

Abstract

We numerically calculate the evolution of second order cosmological perturbations for an inflationary scalar field without resorting to the slow-roll approximation or assuming large scales. In contrast to previous approaches we therefore use the full non-slow-roll source term for the second order Klein-Gordon equation which is valid on all scales. The numerical results are consistent with the ones obtained previously where slow-roll is a good approximation. We investigate the effect of localised features in the scalar field potential which break slow-roll for some portion of the evolution. The numerical package solving the second order Klein-Gordon equation has been released under an open source license and is available for download.