Surprising phenomena in a rich new class of inflationary models

TL;DR

This paper introduces a new class of fast-roll inflationary models exhibiting unusual perturbation phenomena, with some parameter ranges aligning with observations and unique behaviors like scalar reentry and duality to flat space quantum field theory.

Contribution

It presents a novel class of inflationary models with distinctive perturbation behaviors and identifies parameter regimes consistent with observational data.

Findings

Scalar and tensor modes freeze out at different times.

Scalar modes can reenter the horizon during inflation.

A specific parameter point shows absence of freeze-out and particle production.

Abstract

We report on a new class of fast-roll inflationary models. In a huge part of its parameter space, inflationary perturbations exhibit quite unusual phenomena such as scalar and tensor modes freezing out at widely different times, as well as scalar modes reentering the horizon during inflation. In another, narrower range of parameters, this class of models agrees with observations. One specific point in parameter space is characterized by extraordinary behavior of the scalar perturbations. Freeze-out of scalar perturbations as well as particle production at horizon crossing are absent. Also the behavior of the perturbations around this quasi-de Sitter background is dual to a quantum field theory in flat space-time. Finally, the form of the primordial power spectrum is determined by the interaction between different modes of scalar perturbations.