Cosmologies from nonlinear multidimensional gravity with acceleration and slowly varying G

Бронников, К. А.; Kononogov, S. A.; Melnikov, V. N.; Rubin, S. G.

doi:10.1134/s0202289308030043

Cited by 18 publications

(21 citation statements)

References 12 publications

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“…However, as stated in [53], the method used in refs. [49][50][51][52] would lead to ambiguous when a background scalar field is introduced.…”

Section: Introductionmentioning

confidence: 99%

“…However, in f (R) gravity things are more complex, since the dynamical equations are of fourth-order. Based on the fact that f (R) gravity is conformally equivalent to a second-order gravity theory [48], some thin braneworld models have been constructed in the lower order frame [49][50][51][52] by introducing a conformal transformation. We hope this method still valid for the discussions of thick branes.…”

Section: Introductionmentioning

confidence: 99%

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Tensor perturbations of f(R)-branes

2011

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We analyze the tensor perturbations of flat thick domain wall branes in f (R) gravity. Our results indicate that under the transverse and traceless gauge, the metric perturbations decouple from the perturbation of the scalar field. Besides, the perturbed equation reduces to the familiar Klein-Gordon equation for massless spin-2 particles only when the bulk curvature is a constant or when f (R) = R. As an application of our results, we consider the possibility of localizing gravity on some flat thick branes. The stability of these brane solutions is also shortly discussed.

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“…However, as stated in [53], the method used in refs. [49][50][51][52] would lead to ambiguous when a background scalar field is introduced.…”

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Tensor perturbations of f(R)-branes

2011

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“…(32) A final remark: Despite intriguingly similar, even the same, observable values, it is our conviction that the Ellis-Bronnikov wormhole for real values of γ would survive as a topological object of its own class, remaining fundamentally distinct from a Schwarzschild black hole. This would be expected because a real γ > 0 cannot jump to γ = −i, augering a spontaneous topology change against experience [4,36]. By an intuitive extension, it is tempting to elevate this conviction into a principle: Collapse of any object will lead to a final state definable only within the parameter range of the initial object and not to a state defined by parameters outside that range.…”

Section: Discussionmentioning

confidence: 99%

Ring-down gravitational waves and lensing observables: How far can a wormhole mimic those of a black hole?

Nandi¹,

Izmailov²,

Yanbekov³

et al. 2017

Phys. Rev. D

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It has been argued that the recently detected ring-down gravity waveforms could be indicative only of the presence of light rings in a horizonless object, such as a surgical Schwarzschild wormhole, with the frequencies differing drastically from those of the horizon quasinormal mode frequencies ω QNM at late times. While the possibility of such a horizonless alternative is novel by itself, we show by the example of Ellis-Bronnikov wormhole that the differences in ω QNM in the eikonal limit (large l) need not be drastic. This result will be reached by exploiting the connection between ω QNM and the Bozza strong field lensing parameters. We shall also show that the lensing observables of the EllisBronnikov wormhole can also be very close to those of a black hole (say, SgrA * hosted by our galaxy) of the same mass. This situation indicates that the ringdown frequencies and lensing observables of the Ellis-Bronnikov wormhole can remarkably mimic those of a black hole. The constraint on wormhole parameter γ imposed by experimental accuracy is briefly discussed. We also provide independent arguments supporting the stability of the Ellis-Bronnikov wormhole proven recently.---------------

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“…We also recently considered [66] the multidimensional gravity with a Lagrangian containing the Ricci tensor squared and the Kretschmann invariant. In a KaluzaKlein approach with a single compact extra space of arbitrary dimension, with the aid of a slow-change approximation (as compared with the Planck scale), we built a class of spatially flat cosmological models in which both the observed scale factor a(τ ) and the extra-dimensional one, b(τ ), grow exponentially at large times, but b(τ ) grows slowly enough to admit variations of the effective gravitational constant G within observational limits.…”

Section: óò ðù× óò×mentioning

confidence: 99%

Models of G time variations in diverse dimensions

Melnikov

2009

Front. Phys. China

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A review of different cosmological models in diverse dimensions leading to a relatively small time variation of the effective gravitational constant G is presented. Among them: 4-dimensional general scalar-tensor model, multidimensional vacuum model with two curved Einstein spaces, multidimensional model with multicomponent anisotropic "perfect fluid", S-brane model with scalar fields and two form field etc. It is shown that there exist different possible ways of explanation of relatively small time variation of the effective gravitational constant G compatible with present cosmological data (e.g. acceleration): 4-dimensional scalar-tensor theories or multidimensional cosmological models with different matter sources. The experimental bounds on G-dot may be satisfied ether in some restricted interval or for all allowed values of the synchronous time variable.Comment: 27 pages, Late

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Cosmologies from nonlinear multidimensional gravity with acceleration and slowly varying G

Cited by 18 publications

References 12 publications

Tensor perturbations of f(R)-branes

Tensor perturbations of f(R)-branes

Ring-down gravitational waves and lensing observables: How far can a wormhole mimic those of a black hole?

Models of G time variations in diverse dimensions

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