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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

By considering the realization of the emergent universe scenario in Eddington-inspired Born-Infeld (EiBI) theory, we study the stability of the Einstein static universe filled with perfect fluid in EiBI theory against both the homogeneous…

General Relativity and Quantum Cosmology · Physics 2017-08-02 Shou-Long Li , Hao Wei

We consider perturbations of closed Friedmann universes. Perturbation modes of two lowest wavenumbers ($L=0$ and $1$) are generally known to be fictitious, but here we show that both are physical. The issue is more subtle in Einstein static…

General Relativity and Quantum Cosmology · Physics 2020-07-07 Hyerim Noh , Jai-chan Hwang , John D. Barrow

We discuss a no-go theorem for the novel Ricci-inverse theory of modified gravity. By considering a static spherically symmetric matter distribution embedded within a de Sitter cosmology, we demonstrate that achieving a stable Sub-Horizon…

Cosmology and Nongalactic Astrophysics · Physics 2025-01-22 Mattia Scomparin

We reconcile seemingly conflicting statements in the literature about the behavior of cosmological solutions in modified theories of gravity where the Einstein-Hilbert Lagrangian for gravity is modified by the addition of a function of the…

Astrophysics · Physics 2008-11-26 Ignacy Sawicki , Wayne Hu

This paper aims to analyze the generalization of Lema\^{\i}tre-Tolman-Bondi (LTB) spacetime for dissipative dust under the influence of Palatini $f(R)$ gravity. We explore the modified field equations, kinematical variables, and mass…

General Relativity and Quantum Cosmology · Physics 2021-12-21 M. Z. Bhatti , Z. Yousaf , F. Hussain

We present a detailed investigation of the Rastall gravity extension of the standard $\Lambda$CDM model. We review the model for two simultaneous modifications of different nature in the Friedmann equation due to the Rastall gravity: the…

Cosmology and Nongalactic Astrophysics · Physics 2020-11-17 Ozgur Akarsu , Nihan Katirci , Suresh Kumar , Rafael C. Nunes , Burcu Ozturk , Shivani Sharma

We study the stability of the isotropic vacuum Friedmann universe in gravity theories with higher-order curvature terms of the form $(R_{ab}R^{ab})^{n}$ added to the Einstein-Hilbert Lagrangian of general relativity on approach to an…

General Relativity and Quantum Cosmology · Physics 2008-11-26 Jonathan Middleton , John D. Barrow

We work out the description of the gauge symmetry of unimodular gravity in the constrained Hamiltonian formalism. In particular, we demonstrate how the transversality conditions restricting the diffeomorphism parameters emerge from the…

High Energy Physics - Theory · Physics 2022-06-07 I. Yu. Karataeva , S. L. Lyakhovich

We derive a model of constrained topological gravity, a theory recently introduced by us through the twist of N=2 Liouville theory, starting from the general BRST algebra and imposing the moduli space constraint as a gauge fixing. To do…

High Energy Physics - Theory · Physics 2009-10-28 Damiano Anselmi , Pietro Fre' , Luciano Girardello , Paolo Soriani

We will investigate the influence of the inhomogeneity of the universe, especially that of the Lema{\^i}tre-Tolman-Bondi (LTB) model, on a gravitationally bound local system such as the solar system. We concentrate on the dynamical…

General Relativity and Quantum Cosmology · Physics 2015-06-04 Hideyoshi Arakida

We propose a topological model of induced gravity (pregeometry) where both Newton's coupling constant and the cosmological constant appear as integration constants in solving field equations. The matter sector of a scalar field is also…

General Relativity and Quantum Cosmology · Physics 2017-02-15 Ichiro Oda

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 this work we study some aspects of the Rastall gravity, being the thermodynamics consistency of the model the core of this paper, for this purpose we will consider the dynamical equations of Rastall model in a flat FLRW geometry. Under a…

General Relativity and Quantum Cosmology · Physics 2019-10-22 Miguel Cruz , Samuel Lepe , Gerardo Morales-Navarrete

At the present paper, it is studied cosmological solutions and its stability in the frame of F(R) Horava-Lifshitz gravity. The perturbations around general spatially flat FRW solutions are analyzed and it is showed that the stability of…

High Energy Physics - Theory · Physics 2011-05-10 Diego Sáez-Gómez

We study relativistic stars in the simplest model of the de Rham-Gabadadze-Tolley massive gravity which describes the massive graviton without ghost propagating mode. We consider the hydrostatic equilibrium, and obtain the modified…

General Relativity and Quantum Cosmology · Physics 2016-06-15 Taishi Katsuragawa , Shin'ichi Nojiri , Sergei D. Odintsov , Masashi Yamazaki

We generalise the Buchdahl-Bondi limit for the case of static, spherically symmetric, relativistic compact stars immersed in Schwarzschild vacuum in f(R)-theory of gravity, subject to very generic regularity, thermodynamic stability and…

General Relativity and Quantum Cosmology · Physics 2015-09-09 Rituparno Goswami , Sunil D. Maharaj , Anne Marie Nzioki

We investigate the modified $F(R)$ gravity theory with the function $F(R) = (1-\sqrt{1-2\lambda R-\sigma (\lambda R)^2})/\lambda$. The action is converted into Einstein$-$Hilbert action at small values of $\lambda$ and $\sigma$. The local…

General Relativity and Quantum Cosmology · Physics 2016-03-23 S. I. Kruglov

The spherically symmetric static solutions are searched for in some f(T) models of gravity theory with a Maxwell term. To do this, we demonstrate that reconstructing the Lagrangian of f(T) theories is sensitive to the choice of frame, and…

General Relativity and Quantum Cosmology · Physics 2011-08-11 Tower Wang

Rastall gravity is a modified gravity proposal that incorporates a non-conserved energy momentum tensor (EMT). We study the equivalence between Rastall gravity and general relativity, analyzing its consequences for an EMT of dark matter and…

General Relativity and Quantum Cosmology · Physics 2023-03-08 Javier Chagoya , López-Domínguez , C. Ortiz
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