Observational Constraints on Constant Roll Inflation

TL;DR

This paper explores constant-roll inflation models by analyzing their background and perturbation dynamics without slow-roll assumptions, using a new computational method to compare with CMB data and constrain model parameters.

Contribution

It introduces a novel efficient method for computing perturbation spectra in constant-roll inflation and provides observational constraints from Planck and BICEP2/Keck data.

Findings

Constraints on constant-roll parameters from CMB data

Validation of the new computational method

Insights into deviations from slow-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.