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Despite many nice properties and numerous achievements, general relativity is not a complete theory. One of actual approaches towards more complete theory of gravity is its nonlocal modification. We present here a brief review of nonlocal…

General Relativity and Quantum Cosmology · Physics 2017-01-04 Branko Dragovich

We consider nonlocal modification of the Einstein theory of gravity in framework of the pseudo-Riemannian geometry. The nonlocal term has the form $\mathcal{H}(R) \mathcal{F}(\Box)\mathcal {G}(R)$, where $\mathcal{H}$ and $\mathcal{G}$ are…

High Energy Physics - Theory · Physics 2015-08-25 Ivan Dimitrijevic , Branko Dragovich , Jelena Grujic , Zoran Rakic

In this paper, we investigate a nonlocal modification of general relativity (GR) with action $S = \frac{1}{16\pi G} \int [ R- 2\Lambda + (R-4\Lambda) \, \mathcal{F}(\Box) \, (R-4\Lambda) ] \, \sqrt{-g}\; d^4x ,$ where $\mathcal{F} (\Box) =…

General Relativity and Quantum Cosmology · Physics 2020-06-30 I. Dimitrijevic , B. Dragovich , A. S. Koshelev , Z. Rakic , J. Stankovic

We consider some cosmological aspects of nonlocal modified gravity with $\Lambda$ term, where nonlocality is of the type $R \mathcal{F}(\Box) R$. Using ansatz of the form $\Box R = r R +s,$ we find a few a(t) nonsingular bounce cosmological…

General Relativity and Quantum Cosmology · Physics 2015-08-20 I. Dimitrijevic , B. Dragovich , J. Grujic , Z. Rakic

A non-local modified gravity model with an analytic function of the d'Alembert operator is considered. This model has been recently proposed as a possible way of resolving the singularities problem in cosmology. We present an exact bouncing…

High Energy Physics - Theory · Physics 2012-09-18 Alexey S. Koshelev , Sergey Yu. Vernov

We discuss some main aspects of theories of gravity containing non-local terms in view of cosmological applications. In particular, we consider various extensions of General Relativity based on geometrical invariants as $f(R, \Box^{-1} R)$,…

General Relativity and Quantum Cosmology · Physics 2022-01-13 Salvatore Capozziello , Francesco Bajardi

We consider a new modified gravity model with nonlocal term of the form $R^{-1} \mathcal{F}(\Box) R. $ This kind of nonlocality is motivated by investigation of applicability of a few unusual ans\"atze to obtain some exact cosmological…

High Energy Physics - Theory · Physics 2014-11-20 Ivan Dimitrijevic , Branko Dragovich , Jelena Grujic , Zoran Rakic

A non-local modified gravity model with an analytic function of the d'Alembert operator that has been proposed as a possible way of resolving the singularities problems in cosmology is considered. We show that the anzats that is usually…

General Relativity and Quantum Cosmology · Physics 2015-01-09 Alexey S. Koshelev , Sergey Yu. Vernov

The Newtonian regime of a recent nonlocal extension of general relativity (GR) is investigated. Nonlocality is introduced via a scalar "constitutive" kernel in a special case of the translational gauge theory of gravitation, namely, the…

General Relativity and Quantum Cosmology · Physics 2010-04-29 Hans-Joachim Blome , Carmen Chicone , Friedrich W. Hehl , Bahram Mashhoon

The observed acceleration of the Universe can be explained by modifying general relativity. One such attempt is the nonlocal model of Deser and Woodard. Here we fix the background cosmology using results from the Planck satellite and…

Cosmology and Nongalactic Astrophysics · Physics 2014-09-05 Scott Dodelson , Sohyun Park

We review recent progress in the construction of modified gravity models as alternatives to dark energy as well as the development of cosmological tests of gravity. Einstein's theory of General Relativity (GR) has been tested accurately…

Cosmology and Nongalactic Astrophysics · Physics 2016-03-24 Kazuya Koyama

In this paper we consider modification of general relativity extending $R - 2 \Lambda$ by nonlocal term of the form $\sqrt{R-2\Lambda}\, \mathcal{F}(\Box)\, \sqrt{R-2\Lambda} ,$ where $\mathcal{F}(\Box)$ is an analytic function of the…

General Relativity and Quantum Cosmology · Physics 2019-09-04 I. Dimitrijevic , B. Dragovich , A. S. Koshelev , Z. Rakic , J. Stankovic

Nonlocal gravity (NLG) is a classical nonlocal generalization of Einstein's theory of gravitation developed in close analogy with the nonlocal electrodynamics of media. It appears that the nonlocal aspect of the universal gravitational…

General Relativity and Quantum Cosmology · Physics 2022-09-12 Mahmood Roshan , Bahram Mashhoon

A nonlocal gravity model with a function $f(\Box^{-1} R)$, where $\Box$ is the d'Alembert operator, is considered. The algorithm, allowing to reconstruct $f(\Box^{-1} R)$, corresponding to the given Hubble parameter and the state parameter…

Cosmology and Nongalactic Astrophysics · Physics 2012-09-18 Sergey Yu. Vernov

Nonlocal quantum corrections to gravity have been recently proposed as a possible solution to the cosmological fine tuning problems. We study the dynamics of a class of nonlocal actions defined by a function of the inverse d'Alembertian of…

General Relativity and Quantum Cosmology · Physics 2008-11-26 Tomi Koivisto

We consider some aspects of nonlocal modified gravity, where nonlocality is of the type $R \mathcal{F}(\Box) R$. In particular, using ansatz of the form $\Box R = c R^\gamma,$ we find a few $R(t)$ solutions for the spatially flat FLRW…

High Energy Physics - Theory · Physics 2017-01-10 Ivan Dimitrijevic , Branko Dragovich , Jelena Grujic , Zoran Rakic

This thesis is devoted to the study of gravitational theories which can be seen as modifications or generalisations of General Relativity. The motivation for considering such theories, stemming from Cosmology, High Energy Physics and…

General Relativity and Quantum Cosmology · Physics 2011-11-10 Thomas P. Sotiriou

The analysis of measurements of accelerated observers in Minkowski spacetime has led to the development of nonlocal special relativity theory. Inertia and gravitation are intimately connected in accordance with the principle of equivalence.…

General Relativity and Quantum Cosmology · Physics 2012-10-11 Bahram Mashhoon

The recent classical nonlocal generalization of Einstein's theory of gravitation is presented within the framework of general relativity via the introduction of a preferred frame field. The nonlocal generalization of Einstein's field…

General Relativity and Quantum Cosmology · Physics 2015-06-22 B. Mashhoon

A nonlocal generalization of Einstein's theory of gravitation is constructed within the framework of the translational gauge theory of gravity. In the linear approximation, the nonlocal theory can be interpreted as linearized general…

General Relativity and Quantum Cosmology · Physics 2009-03-24 Friedrich W. Hehl , Bahram Mashhoon
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