Observational Constraints on $f(T)$ gravity from varying fundamental constants

TL;DR

This study uses observational data on fundamental constants to constrain $f(T)$ gravity models, finding they are consistent with $ ext{Lambda}$CDM but allow small deviations, informing future model development.

Contribution

It provides observational constraints on $f(T)$ gravity models using variations in fundamental constants, a novel approach in testing these theories.

Findings

$f(T)$ models are consistent with current observations.

Deviations from $ ext{Lambda}$CDM are small but possible.

Constraints are derived from fine-structure constant and Hubble data.

Abstract

We use observations related to the variation of fundamental constants, in order to impose constraints on the viable and most used $f(T)$ gravity models. In particular, for the fine-structure constant we use direct measurements obtained by different spectrographic methods, while for the effective Newton's constant we use a model-dependent reconstruction, using direct observational Hubble parameter data, in order to investigate its temporal evolution. We consider two $f(T)$ models and we quantify their deviation from $\Lambda$CDM cosmology through a sole parameter. Our analysis reveals that this parameter can be slightly different from its $\Lambda$CDM value, however the best-fit value is very close to the $\Lambda$CDM one. Hence, $f(T)$ gravity is consistent with observations, nevertheless, as every modified gravity, it may exhibit only small deviations from $\Lambda$CDM cosmology, a feature that must be taken into account in any $f(T)$ model-building.