Early and late time cosmology: the f(R) gravity perspective

Bajardi, F; D’Agostino, Rocco; Benetti, Micol; Falco, Vittorio De; Capozziello, Salvatore

doi:10.1140/epjp/s13360-022-03418-8

Cited by 22 publications

(6 citation statements)

References 114 publications

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“…To address these issues, different approaches have been considered like extensions of General Relativity (GR), on which the ΛCDM model is based. For instance, a particular extension, known as f (R) gravity [27][28][29][30][31][32]), has been considered in cosmological applications [33][34][35][36][37] to address different issues related to the ΛCDM model, like the late-time dark energy [14,27], and the early inflationary behavior [4]. The philosophy of these approaches is that, instead of searching for new exotic ingredients, the gravitational sector should be improved according to the scales.…”

Section: Introductionmentioning

confidence: 99%

A Critical Discussion on the H0 Tension

Capozziello,

Sarracino,

De Somma

2024

Universe

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A critical discussion on the H0 Hubble constant tension is presented by considering both early and late-type observations. From recent precise measurements, discrepancies emerge when comparing results for some cosmological quantities obtained at different redshifts. We highlight the most relevant measurements of H0 and propose potential ideas to solve its tension. These solutions concern the exploration of new physics beyond the ΛCDM model or the evaluation of H0 by other methods. In particular, we focus on the role of the look-back time.

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Section: Introductionmentioning

confidence: 99%

A Critical Discussion on the H0 Tension

Capozziello,

Sarracino,

De Somma

2024

Universe

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“…The simplest and the most popular extension to the General relativity (GR) is the F(R) gravity [1][2][3][4][5] with a nonlinear function F(R) in the action. In the context of F(R) gravity, inflationary scenarios are being actively studied .…”

Section: Introductionmentioning

confidence: 99%

“…where γ is not integer, are actively investigated [5,16,17,30,[46][47][48][49][50][51][52][53][54]. Models with the R 3/2 term have been investigated in context of integrability and symmetries [46,48,50,52], in particular, it has been shown in [46,48,50] that the R 3/2 term appears naturally from the Noether symmetry analysis.…”

Section: Introductionmentioning

confidence: 99%

New one-parametric extension of the Starobinsky inflationary model

Pozdeeva¹,

Vernov²

2023

Phys. Scr.

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We propose a one-parametric extension of the Starobinsky $R+R^2$ model by adding the $\left(R+m^2\beta^2\right)^{3/2}$ term. The parameter $m$ is the inflaton mass, which is determined in the same way as in the Starobinsky model, and $\beta$ is a dimensionless constant. Using the Einstein frame and the scalar field potential, we get the inflationary parameters of the model proposed. The value of the tensor-to-scalar ratio $r$ can be significantly larger than in the Starobinsky model. The considered inflationary model is in a good agreement with the current observational data. The corresponding scalar field potential is a polynomial of the exponential function.

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“…Discrepancies between early and late Universe are studied in [18] adopting Noether symmetries to select viable models. In this perspective, f (R) gravity can have an important role to solve cosmic tensions.…”

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confidence: 99%

Focus point on tensions in cosmology from early to late universe: the value of the Hubble constant and the question of dark energy

Capozziello

Gurzadyan

2023

Eur. Phys. J. Plus

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Papers included in this Focus Point collection are devoted to one of the hot topics of modern cosmology: the Hubble constant tension. It emerged from observations revealing, with a high degree of confidence, a discrepancy between the value of the Hubble constant, as measured by galaxy distance surveys and standard candles, and the value derived from the Cosmic Microwave Background data. Tension emerges assuming the standard ΛCDM cosmological model [1][2][3]. This discrepancy is attracting numerous research groups, and it is resulting in hundreds of publications aimed to fix it. From a general point of view, this discrepancy and other ones seem to point out a tension between the current picture of late and early Universe.A broad range of topics can be considered in searching for a solution of this puzzle. A bunch of them has been considered in this Focus Point. They range from the detailed methods of observational data analysis, up to dark matter and dark energy models dealing with modifications of ΛCDM, general relativity, basic physical principles, or variation of physical constants, including of the gravitational constant (see [4] for a recent review).The puzzle is, essentially, twofold: from one side, the tension could be addressed by improving measurements and datasets like Cepheids, type Ia supernovae (SNeIa), galaxy sky surveys, gravitational lensing, baryon acoustic oscillations, Big Bang nucleosynthesis, etc. From the other side, the effort is to search for new physics, including possible modifications of general relativity.Let us illustrate the diversity of the approaches considered in this Focus Point.There are studies on the very nature of the main observational parameter, the redshift. In the framework of nonlinearelectromagnetism involving the Lorentz-Poincaré symmetry violation, the possibility of additional cosmological expansionindependent frequency shift has been discussed in [5,6]. The results are compared with observational Pantheon data of SNeIa. Such results allow to conclude that the frequency shift can support an alternative to accelerated expansion accommodating the SNeIa data. Importantly, laboratory tests to investigate additional shifts from extended Electromagnetism can be taken into account. In another study, systematic errors in the cosmological redshift for SNeIa measurements have been studied [7]. As shown, the reduction of the Hubble constant local value is possible up to 5%.The observational constraints for inflationary models derived from f (R) gravity, including the Starobinski and higher-order Lagrangians, have been derived using Planck satellite and Keck datasets [8]. Remarkably, it appears that although f (R) constant-roll models adopt observationally acceptable values of the parameter r, they do not predict favorable values of the spectral index. In another paper [9], f (R) gravity in Palatini approach is studied as an inverse problem: specifically, models are reconstructed starting from an effective equation of state to be constrained by data. In particular, the Starobinsk...

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Early and late time cosmology: the f(R) gravity perspective

Cited by 22 publications

References 114 publications

A Critical Discussion on the H0 Tension

A Critical Discussion on the H0 Tension

New one-parametric extension of the Starobinsky inflationary model

Focus point on tensions in cosmology from early to late universe: the value of the Hubble constant and the question of dark energy

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