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We consider modified theories of gravity with a direct coupling between matter and geometry, denoted by an arbitrary function in terms of the Ricci scalar. Due to such a coupling, the matter stress tensor is no longer conserved and there is…

General Relativity and Quantum Cosmology · Physics 2015-06-05 Yousef Bisabr

The $f(R,T)$ gravity is an extended theory of gravity in which the gravitational action contains general terms of both the Ricci scalar $R$ and trace of the energy-momentum tensor $T$. In this way, $f(R,T)$ models are capable of describing…

General Relativity and Quantum Cosmology · Physics 2017-07-20 P. H. R. S. Moraes , P. K. Sahoo

A modified f(G) gravity model with coupling between matter and geometry is proposed, which is described by the product of the Lagrange density of the matter and an arbitrary function of the Gauss-Bonnet term. The field equations and the…

Cosmology and Nongalactic Astrophysics · Physics 2015-06-04 Yue-Yue Zhao , Ya-Bo Wu , Jianbo Lu , Zhuo Zhang , Wei-Li Han , Liang-Liang Ling

In this contribution one examines the generalization of the $f(R)$ theories of gravity where one introduces a non-minimal coupling between curvature and matter. This model has new and interesting features. %, specially concerning the energy…

General Relativity and Quantum Cosmology · Physics 2014-11-20 Orfeu Bertolami , Miguel Carvalho Sequeira

In this work, we review a plethora of modified theories of gravity with generalized curvature-matter couplings. The explicit nonminimal couplings, for instance, between an arbitrary function of the scalar curvature $R$ and the Lagrangian…

General Relativity and Quantum Cosmology · Physics 2014-07-29 Tiberiu Harko , Francisco S. N. Lobo

In this paper we study a model of modified gravity with non-minimal coupling between a general function of the Gauss-Bonnet invariant, $f(G)$, and matter Lagrangian from the point of view of the energy conditions. Such model has been…

General Physics · Physics 2015-06-03 A. Banijamali , B. Fazlpour , M. R. Setare

In this study, we first establish that gravity models incorporating matter-related terms, such as $f(\mathcal{L}_{\rm m})$, $f(g_{\mu\nu} T^{\mu\nu})$, and $f(T_{\mu\nu} T^{\mu\nu})$, into the usual matter Lagrangian density…

General Relativity and Quantum Cosmology · Physics 2024-04-12 Özgür Akarsu , Mariam Bouhmadi-López , Nihan Katırcı , Elham Nazari , Mahmood Roshan , N. Merve Uzun

We construct new classes of modified theories in which the matter sector couples with the Einstein tensor, namely we consider direct couplings of the latter to the energy-momentum tensor, and to the derivatives of its trace. We extract the…

General Relativity and Quantum Cosmology · Physics 2023-05-17 Petros Asimakis , Spyros Basilakos , Andreas Lymperis , Maria Petronikolou , Emmanuel N. Saridakis

We show that in modified $f(R)$ type gravity models with non-minimal coupling between matter and geometry, both the matter Lagrangian, and the energy-momentum tensor, are completely and uniquely determined by the form of the coupling. This…

General Relativity and Quantum Cosmology · Physics 2010-05-27 T. Harko

We consider an extension of standard General Relativity in which the Hilbert-Einstein action is replaced by an arbitrary function of the Ricci scalar, nonmetricity, torsion, and the trace of the matter energy-momentum tensor. By…

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

The paper extends basic Einstein--Hilbert action by adding a newly proposed invariant constructed from a specific contraction between the Einstein tensor and the energy momentum tensor, encoding a non--minimal coupling between the…

General Relativity and Quantum Cosmology · Physics 2023-02-09 Mihai Marciu , Dana Maria Ioan

General Relativity (GR) exists in different formulations. They are equivalent in pure gravity but generically lead to distinct predictions once matter is included. After a brief overview of various versions of GR, we focus on metric-affine…

High Energy Physics - Theory · Physics 2023-11-09 Claire Rigouzzo , Sebastian Zell

In certain modified theories of gravity, non-minimal couplings between matter and geometry lead to the nonconservation of the energy-momentum tensor. By interpreting this as an effective dissipative process, we formulate a general class of…

General Relativity and Quantum Cosmology · Physics 2026-04-27 Szőllősi Tamás-Géza

In this proceeding, we review modified theories of gravity with a curvature-matter coupling between an arbitrary function of the scalar curvature and the Lagrangian density of matter. This explicit nonminimal coupling induces a…

General Relativity and Quantum Cosmology · Physics 2022-09-20 Francisco S. N. Lobo , Tiberiu Harko

The field equations of a generalized $f(R)$ type gravity model, in which there is an arbitrary coupling between matter and geometry, are obtained. The equations of motion for test particles are derived from a variational principle in the…

General Relativity and Quantum Cosmology · Physics 2009-05-26 T. Harko

In this paper, we investigate the modified Geodesic Deviation Equation (GDE) in the framework of $f(R,T)$ theory of gravity where $R$ and $T$ are the curvature scalar and the trace of the energy-momentum tensor, respectively, using the FLRW…

General Relativity and Quantum Cosmology · Physics 2017-05-04 E. H. Baffou , M. J. S. Houndjo , M. E. Rodrigues , A. V. Kpadonou , J. Tossa

The connection between $f(R)$ theories of gravity and scalar-tensor models with a "physical" metric coupled to the scalar field is well known. In this work, we pursue the equivalence between a suitable scalar theory and a model that…

General Relativity and Quantum Cosmology · Physics 2009-01-01 O. Bertolami , J. Páramos

We consider f(R,T) modified theory of gravity in which, in general, the gravitational Lagrangian is given by an arbitrary function of the Ricci scalar and the trace of the energy-momentum tensor. We indicate that in this type of the theory,…

General Relativity and Quantum Cosmology · Physics 2016-10-05 Raziyeh Zaregonbadi , Mehrdad Farhoudi

We consider a gravitational model in which matter is non-minimally coupled to geometry, with the effective Lagrangian of the gravitational field being given by an arbitrary function of the Ricci scalar, the trace of the matter…

General Relativity and Quantum Cosmology · Physics 2024-11-18 Zahra Haghani , Tiberiu Harko , Francisco S. N. Lobo , Hamid Reza Sepangi , Shahab Shahidi

Over the past century, General Relativity (GR) has been a cornerstone of gravitational theory. However, recent cosmological observations, such as the accelerated expansion of the Universe, challenge its completeness and the standard…

General Relativity and Quantum Cosmology · Physics 2025-06-02 Lakhan V. Jaybhaye
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