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We extend Padmanabhan's entropy functional formalism to show that, in addition to the Gauss-Bonnet or the entire series of Lanczos-Lovelock Lagrangians already obtained, more general higher-order corrections to General Relativity, i.e., the…

General Relativity and Quantum Cosmology · Physics 2015-08-17 Fayçal Hammad

Motivated by a special consideration in quantum measurement, we present a new improved energy-momentum tensor. The new tensor differs from the traditional canonical and symmetric ones, and can be derived as Nother current from a Lagrangian…

General Relativity and Quantum Cosmology · Physics 2019-03-06 Tao Lei , Zi-Wei Chen , Zhen-Lai Wang , Xiang-Song Chen*

The properties of metric perturbations are determined in the context of an expanding Universe governed by a modified theory of gravity with a non-minimal coupling between curvature and matter. We analyse the dynamics of the 6 components of…

General Relativity and Quantum Cosmology · Physics 2025-01-07 Miguel Barroso Varela , Orfeu Bertolami

Scalar-tensor-vector gravity, also known as modified gravity (MOG), has emerged as an alternative to General Relativity (GR). It aims to explain astrophysical phenomena without invoking dark matter. The S-stars orbiting the supermassive…

General Relativity and Quantum Cosmology · Physics 2026-05-21 Ioannis Liodis , Gernot Heissel , Rita Mastroioanni , Jai Grover , Dario Izzo

We propose a covariant formulation of refracted gravity (RG), a classical theory of gravity based on the introduction of gravitational permittivity (GP), a monotonic function of the local mass density, in the standard Poisson equation. GP…

Cosmology and Nongalactic Astrophysics · Physics 2023-06-30 Andrea Pierfrancesco Sanna , Titos Matsakos , Antonaldo Diaferio

We compute the parametrized post-Newtonian parameter $\gamma$ in the case of a static point source for multiscalar-tensor gravity with completely general nonderivative couplings and potential in the Jordan frame. Similarly to the single…

General Relativity and Quantum Cosmology · Physics 2017-01-12 Manuel Hohmann , Laur Jarv , Piret Kuusk , Erik Randla , Ott Vilson

We analyse the implications of the presence of spatial curvature in modified gravity models. As it is well known, the current standard cosmological model, the $\Lambda$CDM, is assumed to be spatially flat based on the results of many…

General Relativity and Quantum Cosmology · Physics 2024-12-03 Serena Gambino , Francesco Pace

Modified Newtonian Dynamics is an empirical modification to Poisson's equation which has had success in accounting for the `gravitational field' $\Phi$ in a variety of astrophysical systems. The field $\Phi$ may be interpreted in terms of…

General Relativity and Quantum Cosmology · Physics 2013-05-30 C. Skordis , T. G. Zlosnik

We consider the possibility of energy being exchanged between the scalar and matter fields in scalar-tensor theories of gravity. Such an exchange provides a new mechanism which can drive variations in the gravitational 'constant' G. We find…

General Relativity and Quantum Cosmology · Physics 2009-01-14 T. Clifton , John D. Barrow

Recently, a gauge theory of unified gravity [Rep. Prog. Phys. 88, 057802 (2025)] has been developed to extend the Standard Model to include gravity. Here we present unified gravity using the ordinary four-vector and tensor field notation of…

General Relativity and Quantum Cosmology · Physics 2025-08-12 Mikko Partanen , Jukka Tulkki

Inspired by Verlinde's idea, some modified versions of entropic gravity have appeared in the literature. Extending them in a unified formalism, we derive the generalized gravitational equations accordingly. From gravitational equations, the…

High Energy Physics - Theory · Physics 2012-11-27 Tower Wang

We derive the equations of motion of an electrically neutral test particle for modified gravity theories in which the covariant divergence of the ordinary matter energy-momentum tensor dose not vanish (i.e. $\nabla_{\mu}T^{\mu\nu}\neq0$).…

General Relativity and Quantum Cosmology · Physics 2013-02-06 Mahmood Roshan

Eddington-inspired Born-Infeld gravity is an important modification of Einstein's general relativity, which can give rise to non-singular cosmologies at the classical level, and avoid the end-stage singularity in a gravitational collapse…

General Relativity and Quantum Cosmology · Physics 2022-01-12 Pritam Banerjee , Debojyoti Garain , Suvankar Paul , Rajibul Shaikh , Tapobrata Sarkar

In the new framework of gravitational quantum field theory (GQFT) with spin and scaling gauge invariance developed in Phys. Rev. D\textbf{93} (2016) 024012-1~\cite{Wu:2015wwa}, we make a perturbative expansion for the full action in a…

General Physics · Physics 2018-09-11 Yue-Liang Wu , Rui Zhang

Modified Newtonian Dynamics (MOND) provides a successful description of stellar and galactic dynamics on almost all astronomical scales. A key feature of MOND is the transition function from Newtonian to modified dynamics which corresponds…

General Physics · Physics 2015-06-19 Sascha Trippe

Using the latest most accurate values of post-Newtonian parameters $\gamma$ and $\beta$ obtained by MESSENGER we impose restrictions on the recently proposed hybrid f(R)-gravity model in its scalar-tensor representation. We show that the…

General Relativity and Quantum Cosmology · Physics 2019-10-08 P. I. Dyadina , S. P. Labazova , S. O. Alexeyev

In this letter, we consider the theory of $F(R)$ gravity with the lagrangian density $ \pounds = R+\alpha R^2 + \beta R^2 \ln \beta R $. We obtain the constant curvature solutions and find the scalar potential of the gravitational field. We…

General Relativity and Quantum Cosmology · Physics 2016-06-09 J. Sadeghi , H. Farahani

We investigate the relationship between a one-parameter family of (anti-)de Sitter Yang-Mills models and a model of Einstein-Palatini gravity with matter, realized through In\"o\"nu-Wigner contraction of the (A)dS algebra. By setting the…

General Relativity and Quantum Cosmology · Physics 2025-12-24 Goffredo Chirco , Alfonso Lamberti , Lucio Vacchiano , Patrizia Vitale

We report an updated constraint on the Solar System quadrupole parameter $Q_2$, which encodes the external field effect predicted by modified gravity versions of the MOND paradigm. Using the dataset employed to compute the DE440 planetary…

General Relativity and Quantum Cosmology · Physics 2026-02-24 R. S. Park , A. Hees , B. Famaey , H. Desmond , A. Durakovic

Starting with an entropy that includes volumetric, area and length terms as well as logarithmic contributions, we derive the corresponding modified Newtonian gravity and derive the expression for planetary orbits. We calculate the shift of…

General Relativity and Quantum Cosmology · Physics 2021-06-18 G. Pérez-Cuéllar , M. Sabido
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