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A new solution with constant torsion is derived using the field equations of f(T). Asymptotic forms of energy density, radial and transversal pressures are shown to meet the standard energy conditions, i.e., weak and null energy conditions…

General Physics · Physics 2016-10-24 Gamal G. L. Nashed

We investigate the field equations of the conformally invariant models of gravity with curvature-matter coupling, constructed in Weyl geometry, by using the Palatini formalism. We consider the case in which the Lagrangian is given by the…

General Relativity and Quantum Cosmology · Physics 2024-11-18 Tiberiu Harko , Shahab Shahidi

We explore an extension of the symmetric teleparallel gravity denoted the $f(Q)$ theory, by considering a function of the nonmetricity invariant $Q$ as the gravitational Lagrangian. Some interesting properties could be found in the $f(Q)$…

General Relativity and Quantum Cosmology · Physics 2019-06-24 Jianbo Lu , Xin Zhao , Guoying Chee

In this paper, we will consider a subclass of models of Horndeski theories of gravity and we will check for several Static Spherically Symmetric solutions. We will find a model which admits an exact black hole solution and we will study its…

General Relativity and Quantum Cosmology · Physics 2018-07-31 Lorenzo Sebastiani

Teleparallel Gravity offers the possibility of reformulating gravity in terms of torsion by exchanging the Levi-Civita connection with the Weitzenb\"ock connection which describes torsion rather than curvature. Surprisingly, Teleparallel…

General Relativity and Quantum Cosmology · Physics 2020-07-23 Maria Caruana , Gabriel Farrugia , Jackson Levi Said

We study static, spherically symmetric neutron stars in a class of scalar-tensor theories with non-canonical kinetic terms (K-essence) obeying all causality and hyperbolicity conditions. These models have non-trivial dynamics that lead to a…

General Relativity and Quantum Cosmology · Physics 2025-09-12 Mark P. Hertzberg , Oleksandr S. Stashko

We study teleparallel gravitational theories with are invariant under the conformal transformations. Wide family of the gravitational Lagrangians that are invariant under conformal transformations have investigated. Cosmological solutions…

General Relativity and Quantum Cosmology · Physics 2014-06-24 Davood Momeni , Ratbay Myrzakulov

We show that extended theories of gravity with Lagrangian f(R,R_{\mu\nu}R^{\mu\nu}) in the Palatini formulation possess a phenomenology much richer than the simpler f(R) or f(R_{\mu\nu}R^{\mu\nu}) theories. In fact, we find that the scalars…

General Relativity and Quantum Cosmology · Physics 2010-02-23 Gonzalo J. Olmo , Helios Sanchis-Alepuz , Swapnil Tripathi

In recent years, a number of alternative theories of gravity have been proposed as possible resolutions of certain cosmological problems or as toy models for possible but heretofore unobserved effects. However, the implications of such…

General Relativity and Quantum Cosmology · Physics 2008-11-26 Michael D. Seifert

In the Palatini action of general relativity the connection and the metric are treated as independent dynamical variables. Instead of assuming a relation between these quantities, the desired relation between them is derived through the…

General Relativity and Quantum Cosmology · Physics 2009-11-05 Eran Rosenthal

In this work, we investigate the construction of spherically symmetric solutions within the framework of modified teleparallel gravity, focusing in particular on $f({\cal T})$ theory, where ${\cal T}$ represents the torsion scalar.…

General Relativity and Quantum Cosmology · Physics 2025-08-08 G. G. L. Nashed , A. Eid

Our manuscript aims to analysis the viability and stability of anisotropic stellar objects in the modified symmetric teleparallel gravity. A particular model of this extended theory is considered to formulate explicit field equations which…

General Relativity and Quantum Cosmology · Physics 2024-08-29 M. Zeeshan Gul , M. Sharif , Adeeba Arooj

We study series of the stationary solutions with asymptotic flatness properties in the Einstein-Maxwell-free scalar system because they are locally equivalent with the exterior solutions in some class of the scalar-tensor theories of…

General Relativity and Quantum Cosmology · Physics 2010-11-19 Tooru Tsuchida , Kazuya Watanabe

Extending the Proca Lagrangian of a massive complex-valued vector field by self-interaction potential, we construct a large class of spherically symmetric solutions in flat Minkowski background as well as in the self-gravitating case. Our…

General Relativity and Quantum Cosmology · Physics 2017-08-09 Y. Brihaye , Th. Delplace , Y. Verbin

The modified theories of gravity, especially the $f(R)$ gravity, have attracted much attention in the last decade. This paper is devoted to exploring plane symmetric solutions in the context of metric $f(R)$ gravity. We extend the work on…

General Relativity and Quantum Cosmology · Physics 2017-06-15 M. Farasat Shamir

We analyze a class of topological static spherically symmetric vacuum solutions in $f(Q)$-gravity. We considered an Ansatz ensuring that those solutions trivially satisfy the field equations of the theory when the non-metricity scalar is…

General Relativity and Quantum Cosmology · Physics 2023-09-14 Marco Calzá , Lorenzo Sebastiani

We investigate some exact static cylindrically symmetric solutions for a perfect fluid in the metric $f(R)$ theory of gravity. For this purpose, three different families of solutions are explored. We evaluate energy density, pressure, Ricci…

General Relativity and Quantum Cosmology · Physics 2015-06-12 M. Sharif , Sadia Arif

We analyse the vacuum static spherically symmetric space-time for a specific class of non-conservative theories of gravity based on the Rastall's theory. We obtain a new vacuum solution which has the same structure as the Schwarzschild-de…

General Relativity and Quantum Cosmology · Physics 2016-06-15 A. M. Oliveira , H. E. S. Velten , J. C. Fabris

We investigate static cylindrically symmetric vacuum solutions in Weyl coordinates in the framework of f(T) theories of gravity, where T is the torsion scalar. The set of modified Einstein equations is presented and the fourth coming…

General Physics · Physics 2013-01-15 M. J. S. Houndjo , D. Momeni , R. Myrzakulov

We study Palatini f(R) cosmology using Noether symmetry approach for the matter dominated universe. In order to construct a point-like Lagrangian in the flat FRW space time, we use the dynamical equivalence between f(R) gravity and…

General Relativity and Quantum Cosmology · Physics 2011-05-19 Mahmood Roshan , Fatimah Shojai