Energy Conditions in a Generalized Second-Order Scalar-Tensor Gravity

Sharif, M.; Waheed, Saira

doi:10.1155/2013/253985

Cited by 21 publications

(18 citation statements)

References 59 publications

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“…Some other well-known examples include Brans-Dicke gravity, generalized scalar-tensor theory, f (τ ) gravity, where τ is a torsion, Gauss-Bonnet gravity and its generalized forms like f (G) gravity, f (R, G) gravity, and f (τ, τ G ) theory, etc. [17][18][19][20][21][22][23][24][25][26].…”

Section: Introductionmentioning

confidence: 99%

Existence of stable wormholes on a non-commutative-geometric background in modified gravity

et al. 2017

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In this paper, we discuss spherically symmetric wormhole solutions in f (R, T ) modified theory of gravity by introducing well-known non-commutative geometry in terms of Gaussian and Lorentzian distributions of string theory. For analytic discussion, we consider an interesting model of f (R, T ) gravity defined by f (R, T ) = f 1 (R) + λT . By taking two different choices for the function f 1 (R), that is, f 1 (R) = R and f 1 (R) = R + α R 2 + γ R n , we discuss the possible existence of wormhole solutions. In the presence of non-commutative Gaussian and Lorentzian distributions, we get exact and numerical solutions for both these models. By taking appropriate values of the free parameters, we discuss different properties of these wormhole models analytically and graphically. Further, using an equilibrium condition, it is found that these solutions are stable. Also, we discuss the phenomenon of gravitational lensing for the exact wormhole model and it is found that the deflection angle diverges at the wormhole throat.

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Section: Introductionmentioning

confidence: 99%

Existence of stable wormholes on a non-commutative-geometric background in modified gravity

et al. 2017

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“…Banijamali et al [26] investigated the energy conditions for non-minimally coupling f (G) theory with L m and found that the WEC is satisfied for specific viable f (G) models. Sharif and Waheed [27] explored the energy bounds in the context of generalized second order scalartensor gravity with the help of a power-law ansatz for the scalar field. Sharif and Zubair [28] derived these conditions in f (R, T, R αβ T αβ ) theory of gravity for two specific models and also examined the Dolgov-Kowasaki instability for particular models of f (R, T ) gravity.…”

Section: Introductionmentioning

confidence: 99%

Energy conditions in $$f(\mathcal {G},T)$$ f ( G , T ) gravity

2016

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The aim of this paper is to introduce a new modified gravity theory named f (G, T ) gravity (G and T are the Gauss-Bonnet invariant and trace of the energy-momentum tensor, respectively) and investigate energy conditions for two reconstructed models in the context of FRW universe. We formulate general field equations, divergence of energymomentum tensor, equation of motion for test particles as well as corresponding energy conditions. The massive test particles follow non-geodesic lines of geometry due to the presence of an extra force. We express the energy conditions in terms of cosmological parameters like the deceleration, jerk, and snap parameters. The reconstruction technique is applied to this theory using de Sitter and power-law cosmological solutions. We analyze the energy bounds and obtain feasible constraints on the free parameters.

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“…Further the energy conditions of a very generalized second-order scalar-tensor gravity have been discussed by Sharif and Saira [37]. Sharif and Zubair have examined these conditions for f (R, T ) gravity [25] and for f (R, T, R μν T μν ) gravity [38], which involves the nonminimal coupling between the Ricci tensor and the energy-momentum tensor.…”

Section: Introductionmentioning

confidence: 99%

Cosmological reconstruction and energy bounds in $$f(R,R_{\alpha \beta }R^{\alpha \beta },\phi )$$ f ( R , R α β R α β , ϕ ) gravity

Zubair¹,

Kousar²

2016

Eur. Phys. J. C

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We discuss the cosmological reconstruction of f (R, R αβ R αβ , φ) (where R, R αβ R αβ , and φ represent the Ricci scalar, the Ricci invariant, and the scalar field) corresponding to a power law and de Sitter evolution in the framework of the FRW universe model. We derive the energy conditions for this modified theory which seem to be more general and can be reduced to some well-known forms of these conditions in general relativity, f (R) and f (R, φ) theories. We have presented the general constraints in terms of recent values of the snap, jerk, deceleration, and Hubble parameters. The energy bounds are analyzed for reconstructed as well as known models in this theory. Finally, the free parameters are analyzed comprehensively.

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Energy Conditions in a Generalized Second-Order Scalar-Tensor Gravity

Cited by 21 publications

References 59 publications

Existence of stable wormholes on a non-commutative-geometric background in modified gravity

Existence of stable wormholes on a non-commutative-geometric background in modified gravity

Energy conditions in $$f(\mathcal {G},T)$$ f ( G , T ) gravity

Cosmological reconstruction and energy bounds in $$f(R,R_{\alpha \beta }R^{\alpha \beta },\phi )$$ f ( R , R α β R α β , ϕ ) gravity

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