Rolling in the Modulated Reheating Scenario

TL;DR

This paper investigates how the dynamics of the modulus field in the modulated reheating scenario affect the amplitude and non-Gaussianity of density perturbations, highlighting the importance of including these effects for accurate predictions.

Contribution

It introduces a detailed analysis of the modulus field dynamics in modulated reheating, showing their significant impact on perturbation statistics and non-Gaussianity levels.

Findings

Modulus dynamics can significantly alter the power spectrum amplitude.

The evolution of the modulus can amplify non-Gaussianity.

Some scenarios produce non-Gaussianity levels excluded by CMB observations.

Abstract

In the modulated reheating scenario, the field that drives inflation has a spatially varying decay rate, and the resulting inhomogeneous reheating process generates adiabatic perturbations. We examine the statistical properties of the density perturbations generated in this scenario. Unlike earlier analyses, we include the dynamics of the field that determines the inflaton decay rate. We show that the dynamics of this modulus field can significantly alter the amplitude of the power spectrum and the bispectrum, even if the modulus field has a simple potential and its effective mass is smaller than the Hubble rate. In some cases, the evolution of the modulus amplifies the non-Gaussianity of the perturbations to levels that are excluded by recent observations of the cosmic microwave background. Therefore, a proper treatment of the modulus dynamics is required to accurately calculate the statistical properties of the perturbations generated by modulated reheating.