Generalizing the coupling between geometry and matter: $$f\left( R,L_m,T\right) $$ gravity

Haghani, Zahra; Harkó, Tiberiu

doi:10.1140/epjc/s10052-021-09359-3

Cited by 26 publications

(12 citation statements)

References 173 publications

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“…The theoretical models of Table III increase in complexity, with MGVIII involving all the three possible geometrical parameters, as well as one single matter parameter, the trace of the energy-momentum tensor. However, couplings generated by general matter terms involving the matter Lagrangian L m , are also possible, and a first step in this direction is represented by the f (R, T m , L m ) gravity theory [201], which introduces a new matter degree of freedom. Some of these models have been extensively investigated in the literature [202,203,206,207].…”

Section: Discussion and Final Remarksmentioning

confidence: 99%

Non-minimal geometry-matter couplings in Weyl-Cartan space-times: $f(R,T,Q,T_m)$ gravity

Harko,

Myrzakulov,

Myrzakulov

et al. 2021

Preprint

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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 construction, the action involves a non-minimal coupling between matter and geometry. The field equations of the model are obtained, and they lead to the nonconservation of the matter energy-momentum tensor. A thermodynamic interpretation of the nonconservation of the energy-momentum tensor is also developed in the framework of the thermodynamics of the irreversible processes in open systems. The Newtonian limit of the theory is considered, and the generalized Poisson equation is obtained in the low velocity and weak fields limits. The nonmetricity, the Weyl vector, and the matter couplings generate an effective gravitational coupling in the Poisson equation. We investigate the cosmological implications of the theory for two different choices of the gravitational action, corresponding to an additive and a multiplicative algebraic structure of the function f , respectively. We obtain the generalized Friedmann equations, and we compare the theoretical predictions with the observational data. We find that the models can give a good descriptions of the observations up to a redshift of z = 1.

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Section: Discussion and Final Remarksmentioning

confidence: 99%

Non-minimal geometry-matter couplings in Weyl-Cartan space-times: $f(R,T,Q,T_m)$ gravity

Harko,

Myrzakulov,

Myrzakulov

et al. 2021

Preprint

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“…We shall also provide some essential assumptions used for this work. The action of  (R, L m , T) gravity is given by [33]…”

Section: Preliminaries Of  (R L M T) Theory Of Gravitymentioning

confidence: 99%

“…Recently, Dolgov-Kawasaki instability is explored for this newly proposed  (R, T, L m ) theory. [33] It is argued that for  (R, T) and  (R, T, L m ) theories, this criteria remains the same as in  (R) gravity and is given by…”

Section: Some Newly Proposed Models Using Reconstruction Techniquementioning

confidence: 99%

Thermodynamics and Perturbative Analysis of Some Newly Developed F(R,Lm,T)$\mathcal {F}(R,L_m, T)$ Theories Under the Scenario of Conserved Energy‐momentum Tensor

Zubair

Waheed

Muneer

et al. 2023

Fortschritte der Physik

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The present work is devoted to explore some interesting cosmological features of a newly proposed theory of gravity namely theory, where R and T represent the Ricci scalar and trace of energy momentum‐tensor, respectively. First, a non‐equilibrium thermodynamical description is considered on the apparent horizon of the Friedmann's cosmos. The Friedmann equations are demonstrated to be equivalent to the first law of thermodynamics, i.e., , where refers to entropy production term. The constraint for validity of generalized second law of thermodynamics is also formulated and checked it for some simple well‐known forms of generic function . Next, the energy bounds for this framework and constraint the free variables by finding the validity regions for NEC and WEC are developed. Furthermore, some interesting cosmological solutions namely power law, ΛCDM, and de Sitter models in this theory are reconstructed. The reconstructed solutions are then examined by checking the validity of GSLT and energy bounds. Lastly, the stability of all reconstructed solutions by introducing suitable perturbations in the field equations is analyzed. It is concluded that obtained solutions are stable and cosmologically viable.

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“…The slow-roll approximation of cosmic inflation within the context of f (R, T ) gravity was studied in [21]. A gravitational model unifying both f (R, L m ) and f (R, T ) theories into the f (R, L m , T ) was developed in [22].…”

Section: Introductionmentioning

confidence: 99%

Self-similar cosmological solutions in f(R,T) gravity theory

Belinchón,

González,

Dib

2021

Preprint

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We study the f (R, T ) cosmological models under the self-similarity hypothesis. We determine the exact form that each physical and geometrical quantity may take in order that the Field Equations (FE) admit exact self-similar solutions through the matter collineation approach. We study two models: the case f (R,In each case, we state general theorems which determine completely the form of the unknown functions f i such that the field equations admit self-similar solutions. We also state some corollaries as limiting cases. These results are quite general and valid for any homogeneous self-similar metric. In this way, we are able to generate new cosmological scenarios. As examples, we study two cases by finding exact solutions to these particular models.

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Generalizing the coupling between geometry and matter: $$f\left( R,L_m,T\right) $$ gravity

Abstract: We generalize and unify the $$f\left( R,T\right) $$ f R , T and $$f\left( R,L_m\right) $$ f R , L m … Show more

Cited by 26 publications

References 173 publications

Non-minimal geometry-matter couplings in Weyl-Cartan space-times: $f(R,T,Q,T_m)$ gravity

Non-minimal geometry-matter couplings in Weyl-Cartan space-times: $f(R,T,Q,T_m)$ gravity

Thermodynamics and Perturbative Analysis of Some Newly Developed F(R,Lm,T)$\mathcal {F}(R,L_m, T)$ Theories Under the Scenario of Conserved Energy‐momentum Tensor

Self-similar cosmological solutions in f(R,T) gravity theory

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