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Nonlocal gravity models are constructed to explain the current acceleration of the universe. These models are inspired by the infrared correction appearing in Einstein Hilbert action. Here we develop the Hamiltonian formalism of a nonlocal…

General Relativity and Quantum Cosmology · Physics 2021-12-28 Pawan Joshi , Utkarsh Kumar , Sukanta Panda

The cosmological reconstruction of modified $F(R)$ and $F(\mathcal{G})$ gravities with agegraphic dark energy (ADE) model in a spatially flat universe without matter field is investigated by using e-folding "$N$" as a forward way. After…

High Energy Physics - Theory · Physics 2011-01-13 A. Khodam-Mohammadi , P. majari , M. Malekjani

This study offers a comprehensive reconstruction of $f(T)$ gravity model with three distinct non-linear as well as novel forms employing a hybrid scale factor to depict the expansion history of the universe starting from early decelerated…

General Relativity and Quantum Cosmology · Physics 2026-02-17 Suraj Kumar Behera , Pratik P. Ray

Using the reconstruction technique with an auxiliary field, we investigate which $F(R)$ gravities can produce the matter bounce cosmological solutions. Owing to the specific functional form of the matter bounce Hubble parameter, the…

General Relativity and Quantum Cosmology · Physics 2015-11-04 V. K. Oikonomou

A nonlocal form of the effective gravitational action could cure the unboundedness of euclidean gravity with Einstein action. On sub-horizon length scales the modified gravitational field equations seem compatible with all present tests of…

General Relativity and Quantum Cosmology · Physics 2015-06-25 C. Wetterich

Models of gravity with variable G and Lambda have acquired greater relevance after the recent evidence in favour of the Einstein theory being non-perturbatively renormalizable in the Weinberg sense. The present paper builds a modified…

High Energy Physics - Theory · Physics 2009-11-11 Alfio Bonanno , Giampiero Esposito , Claudio Rubano

We consider cosmological properties of modified gravity with nonlocal term $ R^p\mathcal{F}(\Box)R^q$ in its Lagrangian. Equations of motion are presented. For the flat FLRW metric, and some particular values of natural numbers $p$ and $q$…

General Relativity and Quantum Cosmology · Physics 2016-04-26 Ivan Dimitrijevic

In the context of a Hubble tension problem that is growing in its statistical significance, we reconsider the effectiveness of non-parametric reconstruction techniques which are independent of prescriptive cosmological models. By taking…

Cosmology and Nongalactic Astrophysics · Physics 2021-10-11 Celia Escamilla-Rivera , Jackson Levi Said , Jurgen Mifsud

We present a reconstruction algorithm for cosmological models based on $f(\mathcal{Q})$ gravity. We specifically focus on obtaining exact Bianchi Type-I and Friedmann-Lema\^{\i}tre-Robertson-Walker solutions, finding solutions that might…

General Relativity and Quantum Cosmology · Physics 2022-05-12 Fabrizio Esposito , Sante Carloni , Roberto Cianci , Stefano Vignolo

Even if the fundamental action of gravity is local, the corresponding quantum effective action, that includes the effect of quantum fluctuations, is a nonlocal object. These nonlocalities are well understood in the ultraviolet regime but…

High Energy Physics - Theory · Physics 2018-03-21 Enis Belgacem , Yves Dirian , Stefano Foffa , Michele Maggiore

In this work, we use reconstruction methods to obtain cosmological solutions in the recently developed scalar-tensor representation of $f(R,T)$ gravity. Assuming that matter is described by an isotropic perfect fluid and the spacetime is…

General Relativity and Quantum Cosmology · Physics 2022-03-15 Tiago B. Gonçalves , João Luís Rosa , Francisco S. N. Lobo

We present a reconstruction method for flat Friedman-Robertson-Walker (FRW) spacetime in a subclass of Horndeski theory -- specifically shiftsymmetric, the kinetic gravity braiding (KGB) theory with a non-vanishing conserved current.…

General Relativity and Quantum Cosmology · Physics 2021-11-01 Ruslan K. Muharlyamov , Tatiana N. Pankratyeva

We present a class of modified-gravity theories which we call ultra-local models. We add a scalar field, with negligible kinetic terms, to the Einstein-Hilbert action. We also introduce a conformal coupling to matter. This gives rise to a…

Cosmology and Nongalactic Astrophysics · Physics 2016-08-17 Philippe Brax , Luca Alberto Rizzo , Patrick Valageas

This article deals with a cosmological scenario in $ f(R,T) $ gravity for a flat FLRW model of the universe. We consider the $ f(R,T) $ function as $ f(R)+f(T) $ which starts with a quadratic correction of the geometric term $ f(R) $ having…

General Relativity and Quantum Cosmology · Physics 2022-05-03 Ritika Nagpal , J. K. Singh , A. Beesham , Hamid Shabani

We present a systematic analysis of the dynamics of flat Friedmann-Lema\^{i}tre-Robertson-Walker cosmological models with radiation and dust matter in generalized teleparallel $f(T)$ gravity. We show that the cosmological dynamics of this…

General Relativity and Quantum Cosmology · Physics 2017-09-05 Manuel Hohmann , Laur Jarv , Ulbossyn Ualikhanova

In the previous article Eur. Phys. J. Plus 136, 590 (2021) (arXiv: 2110.15396) we have proposed a reconstruction method for the kinetic gravity braiding theory in the framework of the flat Friedman-Robertson-Walker spacetime. Here we…

General Relativity and Quantum Cosmology · Physics 2022-07-05 Ruslan K. Muharlyamov , Tatiana N. Pankratyeva

We show that the effective brane-world and the loop quantum cosmology background expansion histories can be reproduced from a modified gravity perspective in terms of an $f(R)$ gravity action plus a $g(R)$ term non-minimally coupled with…

High Energy Physics - Theory · Physics 2015-12-09 Gonzalo J. Olmo , D. Rubiera-Garcia

The present paper reports a study on the cosmological consequences arising from reconstructing $f(T)$ gravity through new holographic-polytropic dark energy. We assume two approaches, namely a particular form of Hubble parameter $H$ and a…

General Relativity and Quantum Cosmology · Physics 2016-11-01 Surajit Chattopadhyay , Abdul Jawad , Shamaila Rani

A new representation is found for the action of the recently suggested ghost-free nonlocal gravity models generating de Sitter or Anti-de Sitter background with an arbitrary value of the effective cosmological constant. This representation…

High Energy Physics - Theory · Physics 2015-06-11 A. O. Barvinsky , Yu. V. Gusev

We discuss the cosmological reconstruction of $f(R,R_{\alpha\beta}R^{\alpha\beta},\phi)$ (where $R$, $R_{\alpha\beta}R^{\alpha\beta}$ and $\phi$ represents the Ricci scalar, Ricci invariant and scalar field) corresponding to power law and…

General Relativity and Quantum Cosmology · Physics 2017-05-01 M. Zubair , Farzana Kousar