# Fibre Inflation and Reheating

## TL;DR

This paper constrains the reheating phase in Fibre Inflation models using Planck data, analyzing how reheating parameters depend on the scalar spectral index and comparing results with $eta$-attractor models.

## Contribution

It provides a model-independent analysis of reheating constraints in Fibre Inflation, relating reheating parameters to observable spectral index and comparing with $eta$-attractor models.

## Key findings

- Large $w_{reh}>1/3$ are favored for $n_s o 0.9680$
- Reheating curves in Fibre Inflation resemble those in $eta$-attractor models
- Reheating temperature and e-foldings depend on spectral index within observational bounds.

## Abstract

We present constraints on the reheating era within the string Fibre Inflation scenario, in terms of the effective equation-of-state parameter of the reheating fluid, $w_{reh}$. The results of the analysis, completely independent on the details of the inflaton physics around the vacuum, illustrate the behavior of the number of $e$-foldings during the reheating stage, $N_{reh}$, and of the final reheating temperature, $T_{reh}$, as functions of the scalar spectral index, $n_s$. We analyze our results with respect to the current bounds given by the PLANCK mission data and to upcoming cosmological experiments. We find that large values of the equation-of-state parameter ($w_{reh}>1/3$) are particularly favored as the scalar spectral index is of the order of $n_s\sim 0.9680$, with a $\sigma_{n_s}\sim 0.002$ error. Moreover, we compare the behavior of the general reheating functions $N_{reh}$ and $T_{reh}$ in the Fibre Inflation scenario with that extracted by the class of the $\alpha$-attractor models with $\alpha=2$. We find that the corresponding reheating curves are very similar in the two cases.