Constraints on generating the primordial curvature perturbation and non-Gaussianity from instant preheating

TL;DR

This paper investigates how isocurvature perturbations during inflation can be converted into primordial curvature perturbations via instant preheating, highlighting the tight constraints and potential for large negative non-Gaussianity.

Contribution

It provides a comprehensive analysis of constraints on inflation models involving instant preheating and isocurvature perturbations, emphasizing the conditions for their viability and observational signatures.

Findings

Constraints are very tight for proposed models.

Special initial conditions are required for model viability.

Large negative non-Gaussianity (f_NL) can occur with strong symmetry breaking.

Abstract

We analyse models of inflation in which isocurvature perturbations present during inflation are converted into the primordial curvature perturbation during instant preheating. This can be due to an asymmetry between the fields present either during inflation or during preheating. We consider all the constraints that the model must satisfy in order to be theoretically valid and to satisfy observations. We show that the constraints are very tight in all of the models proposed and special initial conditions are required for the models to work. In the case where the symmetry is strongly broken during inflation the non-Gaussianity parameter f_NL is generally large and negative.