Reheating constraints on Tachyon Inflation

TL;DR

This paper examines constraints on tachyon inflation models with specific potentials by analyzing reheating parameters and their compatibility with Planck observational data, ultimately disfavoring these models.

Contribution

It provides a detailed analysis of reheating constraints on tachyon inflation with inverse cosh and exponential potentials, linking reheating parameters to observational data.

Findings

Reheating temperature must be above electroweak scale.

Both potentials are disfavored by Planck data.

Reheating equation of state should be close to 1.

Abstract

Tachyon inflation is one of the most attractive models of noncannonical inflation motivated by string theory. In this work we revisit the constraints on tachyon inflation with inverse $\cosh$ potential and exponential potential considering reheating, Although the phase of reheating is not well understood, it can be parameterized in terms of reheating temperature $T_{re}$, number of e-folds during reheating $N_{re}$ and effective equation of state during reheating $w_{re}$, which can be related to the parameters of the tachyon potential, spectral index $n_s$ and tensor-to-scalar ratio $r$. For various reheating scenarios there is a finite range of $w_{re}$ and the reheating temperature should be above electroweak scale. By imposing these conditions, we find that both the inverse $\cosh$ potential and exponential potential are disfavored by Planck observations. We also find that $w_{re}$ for both these potentials should be close to $1$ to satisfy Planck-2015 joint constraints on $n_s$ and $r$.