Intermediate and Power-Law Inflation in the Tachyon Model with Constant Sound Speed

TL;DR

This paper investigates tachyon inflation models with constant sound speed using intermediate and power-law scale factors, analyzing perturbations, non-gaussianity, and observational constraints from Planck2018 and other data sets.

Contribution

It provides a detailed numerical analysis of tachyon inflation with constant sound speed, constraining model parameters and non-gaussian features using recent observational data.

Findings

Viable parameter ranges at 68% and 95% CL for the model.

Sound speed constrained between 0.186 and 1 at 97% CL.

Non-gaussian features analyzed in equilateral and orthogonal configurations.

Abstract

By adopting the intermediate and power-law scale factors, we study the tachyon inflation with constant sound speed. We perform some numerical analysis on the perturbation and non-gaussianity parameters in this model and compare the results with observational data. By using the constraints on the scalar spectral index and tensor-to-scalar-ratio, obtained from Planck2018 TT, TE, EE+lowE+lensing+BAO+BK14 data, the constraint on the running of the scalar spectral index obtained from Planck2018 TT, TE, EE+lowEB+lensing data, and constraint on tensor spectral index obtained from Planck2018 TT, TE, EE +lowE+lensing+BK14+BAO+LIGO and Virgo2016 data, we find the observationally viable ranges of the model's parameters at both $68\%$ CL and $95\%$ CL. We also analyze the non-gaussian features of the model in the equilateral and orthogonal configurations. Based on Planck2018 TTT, EEE, TTE and EET data, we find the constraints on the sound speed as $0.276\leq c_{s}\leq 1$ at $68\%$ CL, $0.213\leq c_{s}\leq 1$ at $95\%$ CL, and $0.186\leq c_{s}\leq 1$ at $97\%$ CL.