Acceleration in Friedmann cosmology with torsion

Abstract

A Friedmann like cosmological model in Einstein-Cartan framework is studied when the torsion function is assumed to be proportional to a single φ(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 φ(t) = −αH(t) ρ m (t)/ρ 0c n is totally compatible with recent cosmological data, where α and n are free parameters to be constrained from observations, ρ m is the matter energy density and ρ 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.

Low-redshift constraints on homogeneous and isotropic universes with torsion

“…We start by considering models without a cosmological constant (where torsion would be expected to yield the current acceleration of the universe) finding that these are strongly disfavoured by the data. To the extent that a comparison is possible, our results here are in agreement with other recent work [10], which uses different assumptions and data (as we discuss below). We then treat these models under a more general assumption that they are one-parameter extensions of ΛCDM, constraining the relative contribution of torsion to the level of a few percent (in appropriate units, also defined below).…”

Non-zero torsion and late cosmology

“…On the other hand, in Ref. [53] an Ansatz for the torsion term is given as a function of the energy density as follows…”

“…Our aim in this work is to discuss some aspects of the cosmology that results from the torsional formalism when it is implemented for a Friedmann-Lemaitre-Robertson-Walker (FLRW) type spacetime, as in Refs. [52,53], and to study a possible relationship between torsion and dark energy.…”

β -decay properties of neutron-rich Ca, Ti, and Cr isotopes

“…These calculations are timely because the mass region addressed is at the borderline of present experimental capabilities for measuring half-lives and β-delayed neutrons. There is increasing experimental activity focused to extend our knowledge about the decay properties of neutron-rich nuclei in different mass regions [2,13,[41][42][43][44][45][46][47]. See also Ref.…”