Preheating after N-flation

TL;DR

This paper investigates preheating in N-flation models with a Marčenko-Pastur mass distribution, finding that parametric resonance is suppressed and perturbative preheating dominates, with implications for observable inflationary parameters.

Contribution

It provides a numerical analysis of preheating in N-flation with specific assumptions, showing suppression of parametric resonance and highlighting differences from single-field inflation.

Findings

Preheating via parametric resonance is suppressed in N-flation.

Perturbative preheating is the dominant mechanism.

Inflationary observables are similar to single-field inflation within certain parameters.

Abstract

We study preheating in N-flation, assuming the Mar\v{c}enko-Pastur mass distribution, equal energy initial conditions at the beginning of inflation and equal axion-matter couplings, where matter is taken to be a single, massless bosonic field. By numerical analysis we find that preheating via parametric resonance is suppressed, indicating that the old theory of perturbative preheating is applicable. While the tensor-to-scalar ratio, the non-Gaussianity parameters and the scalar spectral index computed for N-flation are similar to those in single field inflation (at least within an observationally viable parameter region), our results suggest that the physics of preheating can differ significantly from the single field case.