Reheating constraints on Tachyon Inflation

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 $r$.