Constraints on Tsallis Cosmology from Big Bang Nucleosynthesis and Dark Matter Freeze-out

TL;DR

This paper constrains the Tsallis parameter in Tsallis cosmology using Big Bang Nucleosynthesis data and dark matter relic abundance, finding tight bounds that limit deviations from General Relativity.

Contribution

It derives new bounds on the Tsallis parameter from primordial element formation and dark matter freeze-out, linking thermodynamic gravity to observational cosmology.

Findings

Tsallis parameter must be less than 2 from BBN constraints

Dark matter relic abundance bounds imply 1 - β < 10^{-5}

Deviations from General Relativity are tightly constrained

Abstract

We consider Tsallis cosmology as an approach to thermodynamic gravity and derive the bound on the Tsallis parameter to be $\beta<2$ by using the constraints derived from the formation of the primordial light elements, Helium, Deuterium and Litium, from the observational data from Big Bang Nucleosynthesis (BBN) which allows only a very tiny deviation from General Relativity (GR). Next we consider thermal dark matter (DM) freeze-out mechanism in Tsallis cosmological era and derive bounds on the Tsallis parameter from the observed DM relic abundance to be $1-\beta < 10^{-5}$.