Effect of reheating on predictions following multiple-field inflation

TL;DR

This paper investigates how the reheating phase after multi-field inflation influences cosmological observable predictions, using a semi-analytic approach to model the decay of scalar fields into radiation.

Contribution

It introduces a semi-analytic method to analyze the impact of perturbative reheating on cosmological perturbations in multi-field inflation models.

Findings

Reheating can significantly alter the scalar spectral index and tensor-to-scalar ratio.

Decay rates of scalar fields critically influence observable predictions.

The method applies to $ $-quadratic inflation models.

Abstract

We study the sensitivity of cosmological observables to the reheating phase following inflation driven by many scalar fields. We describe a method which allows semi-analytic treatment of the impact of perturbative reheating on cosmological perturbations using the sudden decay approximation. Focusing on $\mathcal{N}$-quadratic inflation, we show how the scalar spectral index and tensor-to-scalar ratio are affected by the rates at which the scalar fields decay into radiation. We find that for certain choices of decay rates, reheating following multiple-field inflation can have a significant impact on the prediction of cosmological observables.