Tachyon Mimetic Inflation as an Instabilities-Free Model

TL;DR

This paper investigates a mimetic tachyon inflation model, analyzing its perturbations and stability, and finds parameter ranges where it is free of instabilities and consistent with observational data.

Contribution

It introduces a mimetic tachyon inflation model analyzed for stability and observational viability, identifying specific parameter ranges that are free of instabilities.

Findings

Model is free of ghost and gradient instabilities within certain parameter ranges.

Power-law model with 26.3<n<33.0 is observationally viable.

Intermediate model with 0.116<β<0.130 fits observational data.

Abstract

We consider the mimetic tachyon model in the Lagrange multiplier approach. We study both the linear and non-linear perturbations and find the perturbation and non-gaussianity parameters in this setup. By adopting two types of the scale factor as the power-law ($a=a_{0}\,t^{n}$) and intermediate ($a=a_{0}\exp(bt^{\beta})$) scale factors, we perform a numerical analysis on the model which is based on Planck2018 TT, TE, EE+lowE+lensing +BAO +BK14 and Planck2018 TTT, EEE, TTE and EET data sets. We show that the mimetic tachyon model with both the power-law and intermediate scale factors, in some ranges of its parameter space is instabilities-free and observationally viable. The power-law mimetic tachyon model with $26.3<n<33.0$ and the intermediate mimetic tachyon model with $0.116<\beta<0.130$ are consistent with observational data and free of the ghost and gradient instabilities.