Hubble induced mass after inflation in spectator field models

TL;DR

This paper examines how Hubble induced masses affect spectator field models like the curvaton and modulated reheating, revealing relaxed constraints and new predictions for non-gaussianity.

Contribution

It highlights the often overlooked impact of Hubble induced masses from inflaton kinetic energy on spectator field dynamics and model predictions.

Findings

Hubble induced mass relaxes constraints on inflation and reheating parameters.

It significantly alters non-gaussianity predictions in modulated reheating.

Proposes a new model with wide range of local non-gaussianity.

Abstract

Spectator field models such as the curvaton scenario and the modulated reheating are attractive scenarios for the generation of the cosmic curvature perturbation, as the constraints on inflation models are relaxed. In this paper, we discuss the effect of Hubble induced masses on the dynamics of spectator fields after inflation. We pay particular attention to the Hubble induced mass by the kinetic energy of an oscillating inflaton, which is generically unsuppressed but often overlooked. In the curvaton scenario, the Hubble induced mass relaxes the constraint on the property of the inflaton and the curvaton, such as the reheating temperature and the inflation scale. We comment on the implication of our discussion for baryogenesis in the curvaton scenario. In the modulated reheating, the predictions of models e.g. the non-gaussianity can be considerably altered. Furthermore, we propose a new model of the modulated reheating utilizing the Hubble induced mass which realizes a wide range of the local non-gaussianity parameter.