Comparative Study of $f(T)$ Gravity Models with Observational Constraints from \textit{OHD} and \textit{Pantheon+ datasets}

TL;DR

This paper compares three $f(T)$ gravity models using observational data, analyzing their cosmological behavior, stability, and energy conditions, and finds all models approach $\\Lambda$CDM at late times.

Contribution

It provides a systematic comparison of three $f(T)$ models constrained by recent observational data, highlighting their similarities and differences in cosmological dynamics.

Findings

All models asymptotically approach $\\Lambda$CDM behavior.

Violation of the strong energy condition (SEC) is common across models.

Models differ in stability properties and energy condition behaviors.

Abstract

The late-time acceleration of the universe remains one of the most significant open problems in modern cosmology. Modified gravity frameworks such as $f(T)$ gravity provide a geometric alternative to dark energy by attributing cosmic acceleration to torsional effects. In this study, we present a comparative analysis of three different forms of $f(T)$ models: (i) a simple power-law form $f(T) = \eta (-T)^{n}$, (ii) the exponential form $f(T) = \beta T_{0}\left(1-e^{-p \sqrt{T/T_{0}}}\right)$ and (iii) a logarithmic form $f(T) = \gamma T \ln\!\left(\frac{T}{T_{0}}\right)$. Using parameterization of the deceleration parameter $q(z)$ and the corresponding $H(z)$ expression, we constrain the model parameters with the recent Hubble parameter and BAO data through a Markov Chain Monte Carlo (MCMC) approach. The physical behavior of the effective energy density, equation of state parameter, squared sound speed, cosmological $Om(z)$ diagnostics, and energy conditions (NEC, DEC, SEC) were investigated for all three models. Our comparative analysis shows that all models asymptotically approach the $\Lambda$CDM behavior at late times, while they differ in stability properties and energy condition behaviors. In particular, the violation of the strong energy condition (SEC) has emerged as a common feature consistent with current accelerated expansion. This study highlights how different $f(T)$ functional forms can yield distinct cosmological dynamics while maintaining consistency with observational data.