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We provide a detailed analysis of Friedmann-Robertson-Walker universes in a wide range of scalar-tensor theories of gravity. We apply solution-generating methods to three parametrised classes of scalar-tensor theory which lead naturally to…

General Relativity and Quantum Cosmology · Physics 2009-10-28 John D. Barrow , Paul Parsons

In present paper, we search the existence of dark energy scalar field models within in $f(R, T)$ gravity theory established by Harko et al. (Phys. Rev. D 84, 024020, 2011) in a flat FRW universe. The correspondence between scalar field…

General Relativity and Quantum Cosmology · Physics 2021-09-08 Vinod Kumar Bhardwaj , Anirudh Pradhan

The main purpose of this paper is to investigate the exact solutions of cylindrically symmetric spacetime in the context of $f(R,T)$ gravity [1], where $f(R,T)$ is an arbitrary function of Ricci scalar $R$ and trace of the energy momentum…

General Relativity and Quantum Cosmology · Physics 2015-07-01 M. Farasat Shamir , Zahid Raza

We investigate exact and analytic solutions in $f\left( T\right) $ gravity within the context of a Friedmann--Lema\^{\i}tre--Robertson--Walker background space with nonzero spatial curvature. For the power law theory $f\left( T\right)…

General Relativity and Quantum Cosmology · Physics 2022-01-05 Andronikos Paliathanasis

In this work we investigate the structure of neutron stars in modified f(T) gravity models. We find that, unlike the f(R) models, the equations of motion put a rather strict constraint on the possible f(T) functions. Specifically, after…

General Relativity and Quantum Cosmology · Physics 2015-09-11 Cemsinan Deliduman , Baris Yapiskan

In this work, we study a model of holographic dark energy using FLRW cosmology in the context of modified gravity. An extension of the symmetric teleparallel gravity is obtained by considering the gravitational action L is given by an…

General Relativity and Quantum Cosmology · Physics 2025-08-06 Houda Filali , Mouhsine Koussou , Mohamed Bennai , Rachid Ahl Laamara

In this work the exact Friedmann-Robertson-Walker equations for an Elko spinor field coupled to gravity in an Einstein-Cartan framework are presented. The torsion functions coupling the Elko field spin-connection to gravity can be exactly…

General Relativity and Quantum Cosmology · Physics 2017-09-13 S. H. Pereira , S. S. A. Pinho , J. M. Hoff da Silva , J. F. Jesus

In the semi-classical regime, quantum fluctuations embedded in a Riemannian spacetime can be effectively recast as classical back reactions and manifest themselves in the form of non-minimal couplings between matter and curvature. In this…

General Relativity and Quantum Cosmology · Physics 2022-02-07 Che-Yu Chen , Yu-Hsien Kung

We propose an extension of the symmetric teleparallel gravity, in which the gravitational action $L$ is given by an arbitrary function $f$ of the nonmetricity $Q$ and of the trace of the matter energy-momentum tensor $T$, so that…

General Relativity and Quantum Cosmology · Physics 2020-05-19 Yixin Xu , Guangjie Li , Tiberiu Harko , Shi-Dong Liang

We discuss conformal issues of pure and extended teleparallel gravity. In particular, we present formulations of conformal transformation in teleparallel gravity. Furthermore, we propose conformal scalar and gauge field theories in…

General Relativity and Quantum Cosmology · Physics 2013-11-19 Kazuharu Bamba , Sergei D. Odintsov , Diego Sáez-Gómez

The presence of spinor fields is considered in the framework of some extensions of teleparallel gravity, where the Weitzenb\"ock connection is assumed. Some well known models as the Chaplygin gas and its generalizations are reconstructed in…

General Relativity and Quantum Cosmology · Physics 2013-11-22 Ratbay Myrzakulov , Diego Saez-Gomez , Petr Tsyba

Being based on the only assumption that the universe is homogenous and isotropic on large scales, cosmography is an ideal tool to investigate the cosmic expansion history in a almost model-independent way. Fitting the data on the luminosity…

Cosmology and Nongalactic Astrophysics · Physics 2011-11-10 S. Capozziello , V. F. Cardone , H. Farajollahi , A. Ravanpak

We study a Friedmann-Lema\^{\i}tre-Robertson-Walker (FLRW) space-time in the theory of $f(Q)$-gravity, where $Q$ denotes the non-metricity scalar. It has been previously shown in the literature, that there exist four distinct families of…

General Relativity and Quantum Cosmology · Physics 2022-08-17 N. Dimakis , A. Paliathanasis , M. Roumeliotis , T. Christodoulakis

Modern cosmological theory is based on the Friedmann--Robertson--Walker (FRW) metric. Often written in terms of co-moving coordinates, this well-known solution to Einstein's equations owes its elegant and highly practical formulation to the…

General Physics · Physics 2018-09-14 Fulvio Melia

We study teleparallel gravity in five-dimensional spacetime with particular discussions on Kaluza-Klein (KK) and braneworld theories. We directly perform the dimensional reduction by differential forms. In the braneworld theory, the…

High Energy Physics - Theory · Physics 2014-08-29 Chao-Qiang Geng , Ling-Wei Luo , Huan-Hsin Tseng

We construct a theory in which the gravitational interaction is described only by torsion, but that generalizes the Teleparallel Theory still keeping the invariance of local Lorentz transformations in one particular case. We show that our…

General Relativity and Quantum Cosmology · Physics 2016-07-07 Ednaldo L. B. Junior , Manuel E. Rodrigues

In this work a tetrad theory of gravity, invariant under conformal transformations, is investigated. The action of the theory is similar to the action of Maxwell's electromagnetism. The role of the electromagnetic gauge potential is played…

General Relativity and Quantum Cosmology · Physics 2012-06-28 J. W. Maluf , F. F. Faria

An exact charged axially symmetric solution of the coupled gravitational and electromagnetic fields in the teleparallel equivalent of Einstein theory is derived. It is characterized by three parameters ``$ $the gravitational mass $M$, the…

General Relativity and Quantum Cosmology · Physics 2010-10-27 Gamal G. L. Nashed

The field equations of a special class of teleparallel theory of gravitation and electromagnetic fields have been applied to tetrad space having cylindrical symmetry with four unknown functions of radial coordinate $r$ and azimuth angle…

General Relativity and Quantum Cosmology · Physics 2007-05-23 Gamal G. L. Nashed

We present a method to calculate the gravitational energy when asymptotic boundary conditions for the space-time are not given. This is the situation for most of the cosmological models. The expression for the gravitational energy is…

General Relativity and Quantum Cosmology · Physics 2010-10-18 S. C. Ulhoa , J. F. da Rocha Neto , J. W. Maluf