Observational Constraints on Constant Roll Inflation

Abstract

Constant-roll inflation was recently introduced by Motohashi, Starobinsky and Yokoyama as a phenomenological way to parametrize deviations from the slow-roll scenarios. In this paper, we investigate the dynamics of both the background and the perturbations in this model, without making any slow-roll assumptions. The perturbation spectra are computed with an efficient and accurate novel method that allowed us to quickly scan the parameter space of constant-roll inflation. We derive the constraints on the model parameters from the cosmic microwave background anisotropy measurements provided by the joint analysis of the Planck Collaboration and the BICEP2/Keck Array data.

Comments: REVTeX 4.1. 9 pages, 8 figures, Typos fixed, Improved definitions and discussion on parameter degeneracies in the slow-roll limit. Matches the version approved for publication in JCAP