Reheating and Entropy Perturbations in Fibre Inflation

TL;DR

This paper investigates the reheating process in Fibre Inflation models, highlighting the dynamics of preheating and entropy perturbations, and demonstrating the stability of curvature fluctuations due to the large mass of entropy modes.

Contribution

It provides a detailed analysis of reheating in Fibre Inflation, showing that entropy modes do not destabilize curvature fluctuations thanks to their large mass.

Findings

Reheating begins with a phase of preheating involving long wavelength modes.

In two-field models, entropy modes are stabilized by their large mass.

Models are well-behaved during reheating without curvature fluctuation instability.

Abstract

We study reheating in some one and two field realizations of {\it Fibre Inflation}. We find that reheating begins with a phase of preheating in which long wavelength fluctuation modes are excited. In two field models there is a danger that the parametric amplification of infrared fluctuations in the second scalar field - associated with an entropy mode - might induce an instability of the curvature fluctuations. We show that, at least in the models we consider, the entropy mode has a sufficiently large mass to prevent this instability. Hence, from the point of view of reheating the models we consider are well-behaved.