# Acceleration in Friedmann cosmology with torsion

## TL;DR

This paper explores a Friedmann cosmological model within Einstein-Cartan theory incorporating torsion linked to matter spin, demonstrating compatibility with observations and explaining the universe's accelerated expansion.

## Contribution

It introduces a specific torsion function proportional to the Hubble parameter and matter density, fitting recent cosmological data and explaining acceleration.

## Key findings

- Model reproduces accelerated expansion with transition redshift ~0.65
- Torsion function form is compatible with observational data
- Deceleration parameter indicates a transition from deceleration to acceleration

## Abstract

A Friedmann like cosmological model in Einstein-Cartan framework is studied when the torsion function is assumed to be proportional to a single $\phi(t)$ function coming just from the spin vector contribution of ordinary matter. By analysing four different types of torsion function written in terms of one, two and three free parameters, we found that a model with $\phi(t)=- \alpha H(t) \big({\rho_{m}(t)}/{\rho_{0c}}\big)^n$ is totally compatible with recent cosmological data, where $\alpha$ and $n$ are free parameters to be constrained from observations, $\rho_m$ is the matter energy density and $\rho_{0c}$ the critical density. The recent accelerated phase of expansion of the universe is correctly reproduced by the contribution coming from torsion function, with a deceleration parameter indicating a transition redshift of about $0.65$.