Cosmic inflation in some viable modified models of f(R) gravity of polynomial-exponential form

Abstract In this paper, we present the cosmic inflation scenario in some viable models of the f(R) modified gravity of polynomial-exponential form. Results show that the magnitude of the parameter β in these viable models is at the order of 5.67x10–76 and the time of inflation is at the order of 4.6 x 10–35 s.

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The Perturbation of Material Density in f(R) Modified Gravity of Polynormal Exponential Form

10.29007/xqpk ◽

2020 ◽

Author(s):

Van On Vo

Keyword(s):

Cosmological Model ◽

Modified Gravity ◽

Linear Perturbation ◽

Exponential Form ◽

Material Density ◽

Gravitational Model ◽

Standard Cosmological Model ◽

The Difference ◽

Evolutionary Aspects ◽

The Universe

In this paper, we investigate the linear perturbation of the material density of the universe in f(R) modified gravity of polynomial exponential form on the scale of distance below the cosmic horizon (sub-horizon). The results show that the model for the evolutionary aspects of the universe is slightly different from that in the standard cosmological model of ΛCDM. They can be used to show the difference between this modified gravitational model with the standard cosmological model of ΛCMD and other cosmological models. We also investigate the ration Ψ/ Φ and Geff / GN in the model and show that they are within allowable limits of experiments.

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1D Supergravity FLRW Model of Starobinsky

Universe ◽

10.3390/universe7110449 ◽

2021 ◽

Vol 7 (11) ◽

pp. 449

Author(s):

Nephtalí E. Martínez-Pérez ◽

Cupatitzio Ramírez-Romero ◽

Víctor M. Vázquez-Báez

Keyword(s):

Scalar Field ◽

Modified Gravity ◽

Energy State ◽

Hamiltonian Formulation ◽

Low Energy ◽

The Other ◽

Classical Dynamics ◽

Massive Scalar ◽

Massive Scalar Field ◽

Cosmic Inflation

We study two homogeneous supersymmetric extensions for the f(R) modified gravity model of Starobinsky with the FLRW metric. The actions are defined in terms of a superfield R that contains the FLRW scalar curvature. One model has N = 1 local supersymmetry, and its bosonic sector is the Starobinsky action; the other action has N = 2, its bosonic sector contains, in additional to Starobinsky, a massive scalar field without self-interaction. As expected, the bosonic sectors of these models are consistent with cosmic inflation, as we show by solving numerically the classical dynamics. Inflation is driven by the R2 term during the large curvature regime. In the N = 2 case, the additional scalar field remains in a low energy state during inflation. Further, by means of an additional superfield, we write equivalent tensor-scalar-like actions from which we can give the Hamiltonian formulation.

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Jointly modelling Cosmic Inflation and Dark Energy

Journal of Physics Conference Series ◽

10.1088/1742-6596/2105/1/012001 ◽

2021 ◽

Vol 2105 (1) ◽

pp. 012001

Author(s):

Konstantinos Dimopoulos

Keyword(s):

Dark Energy ◽

Scalar Field ◽

Modified Gravity ◽

Cosmic Inflation

Abstract Quintessential inflation utilises a single scalar field to account for the observations of both cosmic inflation and dark energy. The requirements for modelling quintessential inflation are described and two explicit successful models are presented in the context of α-attractors and Palatini modified gravity.

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The Perturbation of Material Density in F(R) Modified Gravity of Polynomial Exponential Form

10.7176/apta/78-05 ◽

2019 ◽

Keyword(s):

Modified Gravity ◽

Exponential Form ◽

Material Density

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On the expanding phase of a singular bounce and intermediate inflation: The modified gravity description

Modern Physics Letters A ◽

10.1142/s0217732317500675 ◽

2017 ◽

Vol 32 (10) ◽

pp. 1750067 ◽

Cited By ~ 7

Author(s):

V. K. Oikonomou

Keyword(s):

Energy Density ◽

Power Spectrum ◽

Observational Data ◽

Spectral Index ◽

Modified Gravity ◽

Bonnet Gravity ◽

Type Iii ◽

Density Singularity ◽

Inflation Scenario

We demonstrate that the intermediate inflation scenario is a singular inflation cosmology, with the singularity at the origin t = 0 being a pressure and energy density singularity and particularly a Type III singularity. Also, we show that the expanding phase of a singular bounce can be identical to the intermediate inflation scenario, if the singular bounce has a Type III singularity at the origin. For the intermediate inflation scenario we examine the cosmological implications on the power spectrum in the context of various forms of modified gravity. Particularly, we calculate the power spectrum in the context of F(R), F(G) Gauss–Bonnet gravity and also for F(T) gravity and we discuss the viability of each scenario by comparing the resulting spectral index with the latest observational data.

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