Mon Enfance en U. R. S. S.

Fay, Sidney B.; Pousino, O.

doi:10.2307/40082217

Cited by 12 publications

(13 citation statements)

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“…It turns then out that these models can generate a viable sequence 5 of radiation dominated, matter dominated and accelerating era matching with the constraints. This has been shown for various parameterizations of the function f (R), most often with some power-law forms (with one, two or three powers of R), but also with square-root, logarithmic and exponential forms for the curvature correction terms [53,50,54,55,56]. As an example we show, in the left panel of Fig.…”

Section: Palatini Models: Cosmologymentioning

confidence: 53%

Cosmology of Modified (but second order) Gravity

Koivisto

2010

AIP Conference Proceedings

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This is a brief review of applications of extended gravity theories to cosmology, in particular to the dark energy problem. Generically extensions of gravity action involve higher derivative terms, which can result in ghosts and instabilities. We consider three ways to circumvent this: Chern-Simons terms, first order variational principle and nonlocality. We consider some recent cosmological applications of these three classes of modified gravity models. The viable parameter spaces can be very efficiently bounded by taking into account cosmological constraints from all epochs in addition to bounds from Solar system tests and stability considerations. We make some new remarks concerning so called algebraic scalar-tensor theories, biscalar reformulation of nonlocal actions involving the inverse d'Alembertian, and a possible covariant formulation holographic cosmology with nonperturbative gravity.

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Section: Palatini Models: Cosmologymentioning

confidence: 53%

Cosmology of Modified (but second order) Gravity

Koivisto

2010

AIP Conference Proceedings

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“…Besides, the simplest cases of the kind f (R) = R − β/R n have shown difficulties with, weak field tests [18,19], gravitational instabilities [20] and do not present a matter dominated era previous to the acceleration era [21,22]. Alternatively, the Palatini variational approach for such f (R) theories leads to 2nd order field equations, and some authors have achieved to put observational constraints to these theories [23,24,25]. However in many cases the equations are still hard to work with, as evidenced by the functional form of the modified Friedmann equation for a generic f (R).…”

Section: Introductionmentioning

confidence: 99%

Dark torsion as the cosmic speed-up

2009

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It is shown that the recently detected acceleration of the universe can be understood by considering a modification of the teleparallel equivalent of General Relativity (TEGR), with no need of dark energy. The solution also exhibits phases dominated by matter and radiation as expected in the standard cosmological evolution. We perform a joint analysis with measurements of the most recent type Ia supernovae (SNe Ia), Baryon Acoustic Oscillation (BAO) peak and estimates of the CMB shift parameter data to constraint the only new parameter this theory has.Comment: 5 pages, 5 figures, replaced to match version to be published in Physical Review

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“…According to the fact of accelerated expansion of the universe, Buchdahl proposed the f (R) theory as a kind of modified gravity [1] and further the theory has been applied to explain the accelerated-inflation problem without dark matter or dark energy [2][3][4]. The f (R) gravity generalizes the general relativity and the generalization certainly arises in the description of the background around the gravitational sources.…”

Section: Introductionmentioning

confidence: 99%

The tunneling radiation of a black hole with a f(R) global monopole under generalized uncertainty principle

Chen

Cheng

2018

Gen Relativ Gravit

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We consider the evolution of black hole involving an f (R) global monopole based on the Extended Uncertainty Principle (EUP). The black hole evolutions refer to the instability due to the Parikh-Kraus-Wilczeck tunneling radiation or fragmentation. It is found that the EUP corrections make the entropy difference larger to encourage the black hole to radiate more greatly. We also show that the appearance of the EUP effects result in the black hole's division. The influence from global monopole and the revision of general relativity can also adjust the black hole evolution simultaneously, but can not change the final result that the black hole will not be stable because of the EUP's effects.

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Mon Enfance en U. R. S. S.

Cited by 12 publications

References 0 publications

Cosmology of Modified (but second order) Gravity

Cosmology of Modified (but second order) Gravity

Dark torsion as the cosmic speed-up

The tunneling radiation of a black hole with a f(R) global monopole under generalized uncertainty principle

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