Inflation Based on the Tsallis Entropy

TL;DR

This paper explores an inflationary cosmology model based on Tsallis entropy, deriving key inflationary parameters and testing its compatibility with Planck 2018 data, showing improved observational consistency over standard models.

Contribution

It introduces a novel inflationary framework using Tsallis entropy, reconstructs an equivalent $f(R)$ gravity model, and assesses its observational viability with current data.

Findings

Tsallis entropy-based inflation can better fit Planck 2018 data.

Quadratic and natural inflation potentials show improved consistency.

Constraints on inflationary parameters are derived from observational data.

Abstract

We study the inflationary scenario in the Tsallis entropy-based cosmology. The Friedmann equations in this setup can be derived by using the first law of thermodynamics. To derive the relations of the power spectra of the scalar and tensor perturbations in this setup, we reconstruct an $f(R)$ gravity model which is thermodynamically equivalent to our model in the slow-roll approximation. In this way, we find the inflationary observables, including the scalar spectral index and the tensor-to-scalar ratio in our scenario. Then, we investigate two different potentials in our scenario, including the quadratic potential and the potential associated with the natural inflation in which the inflaton is an axion or a pseudo-Nambu-Goldstone boson. We examine their observational viability in light of the Planck 2018 CMB data. We show that although the results of these potentials are in tension with the observations in the standard inflationary setting, their consistency with the observations can be significantly improved within the setup of the Tsallis entropy-based inflation. Moreover, we place constraints on the parameters of the considered inflationary models by using the current observational data.