<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" altimg="si1.gif" overflow="scroll"><mml:mi>f</mml:mi><mml:mo stretchy="false">(</mml:mo><mml:mi>R</mml:mi><mml:mo stretchy="false">)</mml:mo></mml:math> Gravities à la Brans–Dicke

Rador, T.

doi:10.1016/j.physletb.2007.07.034

Cited by 25 publications

(5 citation statements)

References 28 publications

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“…We caution that this analysis does not cover the theory such as [500], because the quantity F depends on both ϕ and R (in other words, δF = F , ϕ δϕ + F , R δR ). In the following we write the curvature perturbations and as .…”

Section: Perturbations Generated During Inflationmentioning

confidence: 99%

f(R) Theories

Felice

Tsujikawa

2010

Living Rev. Relativ.

3,562

3,400

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Over the past decade, f(R) theories have been extensively studied as one of the simplest modifications to General Relativity. In this article we review various applications of f(R) theories to cosmology and gravity — such as inflation, dark energy, local gravity constraints, cosmological perturbations, and spherically symmetric solutions in weak and strong gravitational backgrounds. We present a number of ways to distinguish those theories from General Relativity observationally and experimentally. We also discuss the extension to other modified gravity theories such as Brans-Dicke theory and Gauss-Bonnet gravity, and address models that can satisfy both cosmological and local gravity constraints.

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Section: Perturbations Generated During Inflationmentioning

confidence: 99%

f(R) Theories

Felice

Tsujikawa

2010

Living Rev. Relativ.

3,562

3,400

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“…Our action is of the form similar to form obtained in [68]. But our approach here is to develop a model of inflation in palatini formalism.…”

Section: Jcap05(2021)019mentioning

confidence: 97%

“…In this work, we formulate a palatini inflation model in f (R, h) theory. In metric formalism inflation model in f (R, h) gravity has been considered earlier in literature [68][69][70].…”

Section: Introductionmentioning

confidence: 99%

Inflation and Reheating in f(R,h) theory formulated in the Palatini formalism

Das

Panda

2021

J. Cosmol. Astropart. Phys.

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A new model for inflation using modified gravity in the Palatini formalism is constructed. Here non-minimal coupling of scalar field h with the curvature R as a general function f (R, h) is considered. Explicit inflation models for some choices of f (R, h) are developed. By writing an equivalent scalar-tensor action for this model and going over to Einstein frame, slow roll parameters are constructed. There exists a large parameter space for different choices of f (R, h) and potentials which satisfy values of n s and limits on r compatible with Planck 2018 data. Further, we calculate reheating temperature and the number of e-folds at the end of reheating for different values of equation of state parameter for all the constructed models.

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“…As discussed in Ref. [24,33], this is a nontrivial task for modified theories of gravity. Then, we expand the action (5) to the second order in scalar and tensor perturbations and study their implications for the model.…”

Section: Linear Perturbationsmentioning

confidence: 97%

Alternative approach to the Starobinsky model for inflation scenarios

Chaichian¹,

Ghal'e²,

Oksanen³

2022

Preprint

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The R + R 2 model of gravity with the corresponding shallow potential in the Einstein frame is consistent with the observations. Recently, many effort have been made to generalize the R + R 2 (Starobinsky) model of inflation or use other shallow potentials to construct a model for the early Universe. We revise the question about the shallow potential. We propose a model in which the Starobinsky model can emerge through a dynamical mechanism. We show that the absence of ghost modes results to constraints on the parameters of the Starobinsky model. We obtain the scalar spectral index and the tensor-to-scalar ratio of the extended model and study the three-point correlation function of the curvature perturbation to estimate the primordial non-Gaussianities of the proposed model.

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f(R) Gravities à la Brans–Dicke

Cited by 25 publications

References 28 publications

f(R) Theories

f(R) Theories

Inflation and Reheating in f(R,h) theory formulated in the Palatini formalism

Alternative approach to the Starobinsky model for inflation scenarios

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