Observable Signatures of Inflaton Decays

TL;DR

This paper numerically investigates how inflaton field decays during inflation create observable features in the power spectrum, confirming analytic predictions and extending to complex multi-field scenarios.

Contribution

It introduces a numerical framework that models inflaton decay effects on the power spectrum across many fields, bridging analytic and complex multi-field inflation models.

Findings

Discrete steps in power spectrum for few fields

Features become smeared with many decaying fields

Analytic approach validated in multi-field regime

Abstract

We numerically compute features in the power-spectrum that originate from the decay of fields during inflation. Using a simple, phenomenological, multi-field setup, we increase the number of fields from a few to thousands. Whenever a field decays, its associated potential energy is transferred into radiation, causing a jump in the equation of state parameter and mode mixing at the perturbed level. We observe discrete steps in the power-spectrum if the number of fields is low, in agreement with analytic arguments in the literature. These features become increasingly smeared out once many fields decay within a given Hubble time. In this regime we confirm the validity of the analytic approach to staggered inflation, which is based on a coarse-graining procedure. Our numerical approach bridges the aforementioned analytic treatments, and can be used in more complicated scenarios.