Perturbative Analysis of Generalized Einstein Theories

Fabris, J. C.; Kerner, Richard; Tossa, J.

doi:10.1142/s0218271800000116

Cited by 29 publications

(26 citation statements)

References 25 publications

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“…Another estimation can be obtained by using structure formation. Following [25], we see that the modification of the equation of state induced by Rastall's theory at the background level, from the point of view of the general relativity framework, i.e. p m = ω e ρ m , is maintained for linear perturbations, i.e.…”

Section: The Modelmentioning

confidence: 91%

“…p m = ω e ρ m , is maintained for linear perturbations, i.e. δp m ≈ ω e δρ m (we use the approximate sign since in [25] the model considered is a single-fluid one). The cold dark matter scenario implies ω e = 0, while the warm dark matter scenario could lead to ω e ∼ 0 (we admit that the hot dark matter scenario is excluded by observation).…”

Section: The Modelmentioning

confidence: 99%

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Rastall cosmology and theΛCDMmodel

et al. 2012

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Section: The Modelmentioning

confidence: 91%

Section: The Modelmentioning

confidence: 99%

Rastall cosmology and theΛCDMmodel

et al. 2012

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“…The approaches to this problem available in the literature [38]- [40] [ 27,6,7,41,28] are limited to special cases of generalized gravity theories and, usually, to homogeneous perturbations. The consideration of more general inhomogeneous perturbations is complicated by the gauge-dependence of this kind of cosmological perturbations.…”

Section: Perturbationsmentioning

confidence: 99%

de Sitter attractors in generalized gravity

Faraoni

2004

Phys. Rev. D

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We obtain conditions for the existence and stability of de Sitter attractors in the phase space of homogeneous and isotropic cosmology in generalized theories of gravity (including non-linear and scalar-tensor theories). These conditions are valid for any form of the coupling functions of the theory. Stability with respect to inhomogeneous perturbations is analyzed using a covariant and gauge-invariant formalism. The relevance for inflationary scenarios of the early universe and for quintessence models of the present era is discussed.

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“…Based on these observational evidences, there have been some recently studies of the various cosmic eras in the framework of Rastall gravity [18][19][20][21][22]. Other interesting a e-mail: cordac.galilei@gmail.com issues are that Rastall gravity seems to do not suffer from the entropy and age problems of standard cosmology [23] and is consistent with the gravitational lensing phenomena [24,25]. Further interesting works on Rastall gravity are given by [26][27][28][29][30] and references within.…”

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confidence: 99%

Einstein and Rastall theories of gravitation in comparison

Darabi

Moradpour

Licata³

et al. 2018

Eur. Phys. J. C

178

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We profit by a recent paper of Visser claiming that Rastall gravity is equivalent to Einstein gravity to compare the two gravitational theories in a general way. Our conclusions are different from Visser's ones. We indeed argue that these two theories are not equivalent. In fact, Rastall theory of gravity is an "open" theory when compared to Einstein general theory of relativity. Thus, it is ready to accept the challenges of observational cosmology and quantum gravity.The framework of extended theories of gravity [1][2][3][4][5] is today considered an useful and popular approach to attempt to solve the important problems of the standard model of cosmology like Dark Energy [6,7] and Dark Matter [8,9]. A key point is that all of the potential alternatives to Einstein's general theory of relativity (GTR) must be viable. This implies that alternative theories must be in agreement with the Einstein's equivalence principle, which has today a strong, unchallengeable empirical evidence [2]. The fundamental consequence is that the alternatives to Einstein gravity must be metric theories [2]. Another important point is that such alternatives must pass the solar system tests. Hence, deviations from the standard GTR must be weak [1,2].Within the framework of extended gravity, one finds the theory proposed by Rastall in 1972 [10], which recently obtained a renewed interest in the literature [11][12][13][14]. This interest is due to some good behavior of the Rastall theory. In fact, on one hand it seems in good agreement with observational data on the Universe age and on the Hubble parameter [15]. On the other hand it may, in principle, provide an alternative description for the matter dominated era with respect to the GTR [16]. Observational data from the helium nucleosynthesis seem also in agreement with Rastall gravity [17]. Based on these observational evidences, there have been some recently studies of the various cosmic eras in the framework of Rastall gravity [18][19][20][21][22]. Other interesting a e-mail: cordac.galilei@gmail.com issues are that Rastall gravity seems to do not suffer from the entropy and age problems of standard cosmology [23] and is consistent with the gravitational lensing phenomena [24,25]. Further interesting works on Rastall gravity are given by [26][27][28][29][30] and references within.Differently from Einstein gravity, Rastall gravity considers a non-divergence-free energy-momentum . A different, but similar theory is the so called Curvature-matter theory of gravity [31][32][33][34][35]. In this theory the matter and geometry are coupled to each other in a non-minimal way [31][32][33][34][35]. Then, the standard energy-momentum conservation law does not work in this case too [31][32][33][34][35].In a recent paper [36], Visser claimed that Rastall gravity is equivalent to Einstein gravity. In this letter, we argue that these two theories are not equivalent instead. Let us see the key points of our interpretation.Rastall did not define a new energy-momentum tensor (EMT) in his origina...

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Perturbative Analysis of Generalized Einstein Theories

Cited by 29 publications

References 25 publications

Rastall cosmology and theΛCDMmodel

Rastall cosmology and theΛCDMmodel

de Sitter attractors in generalized gravity

Einstein and Rastall theories of gravitation in comparison

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