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Observational Constraints and Cosmographic Analysis of f(T,T_G) Gravity and Cosmology

by Harshna Balhara, Jainendra Kumar Singh, Shaily and Emmanuel N. Saridakis

Symmetry 2024, 16(10), 1299; https://doi.org/10.3390/sym16101299 - 2 Oct 2024

Cited by 12 | Viewed by 2783

We perform observational confrontation and cosmographic analysis of

f (T, T_{G})

We perform observational confrontation and cosmographic analysis of

f (T, T_{G})

gravity and cosmology. This higher-order torsional gravity is based on both the torsion scalar, as well as on the teleparallel equivalent of the Gauss–Bonnet combination, and gives rise to an effective dark-energy sector which depends on the extra torsion contributions. We employ observational data from the Hubble function and supernova Type Ia Pantheon datasets, applying a Markov chain Monte Carlo sampling technique, and we provide the iso-likelihood contours, as well as the best-fit values for the parameters of the power-law model, an ansatz which is expected to be a good approximation of most realistic deviations from general relativity. Additionally, we reconstruct the effective dark-energy equation-of-state parameter, which exhibits a quintessence-like behavior, while in the future the Universe enters into the phantom regime, before it tends asymptotically to the cosmological constant value. Furthermore, we perform a detailed cosmographic analysis, examining the deceleration, jerk, snap, and lerk parameters, showing that the transition to acceleration occurs in the redshift range

0.52 \leq z_{t r} \leq 0.89

, as well as the preference of the scenario for quintessence-like behavior. Finally, we apply the Om diagnostic analysis to cross-verify the behavior of the obtained model. Full article

(This article belongs to the Special Issue Symmetry in Cosmological Theories and Observations)

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13 pages, 405 KB

Open AccessArticle

Big Bang Nucleosynthesis Constraints on f (T, T_G) Gravity

by Petros Asimakis, Emmanuel N. Saridakis, Spyros Basilakos and Kuralay Yesmakhanova

Universe 2022, 8(9), 486; https://doi.org/10.3390/universe8090486 - 14 Sep 2022

Cited by 12 | Viewed by 1981

Abstract

We confront

f (T, T_{G})

We confront

f (T, T_{G})

gravity, with big bang nucleosynthesis (BBN) requirements. The former is obtained using both the torsion scalar, as well as the teleparallel equivalent of the Gauss–Bonnet term, in the Lagrangian, resulting to modified Friedmann equations in which the extra torsional terms constitute an effective dark energy sector. We calculate the deviations of the freeze-out temperature

T_{f}

, caused by the extra torsion terms in comparison to

Λ

CDM paradigm. Then, we impose five specific

f (T, T_{G})

models and extract the constraints on the model parameters in order for the ratio

| Δ T_{f} / T_{f} |

to satisfy the observational BBN bound. As we find, in most of the models the involved parameters are bounded in a narrow window around their general relativity values as expected, asin the power-law model, where the exponent n needs to be

n ≲ 0.5

. Nevertheless, the logarithmic model can easily satisfy the BBN constraints for large regions of the model parameters. This feature should be taken into account in future model building. Full article

(This article belongs to the Special Issue Torsion-Gravity and Spinors in Fundamental Theoretical Physics)

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