A viable logarithmic<i>f</i>(<i>R</i>) model for inflation

Amin, Mustafa A.; Khalil, S.; Salah, Moataz M.

doi:10.1088/1475-7516/2016/08/043

Cited by 16 publications

(14 citation statements)

References 65 publications

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“…We assume that the number of e-foldings required to solve the problems of the ΛCDM model are 50 < N < 60 [18,39]. Therefore,…”

Section: Inflationary Dynamics and Reheating Temperaturementioning

confidence: 99%

Constraining $f(R)$ model through spectral indices and reheating temperature

Sharma,

Verma

2020

Preprint

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We investigate a form of f (R) = R 1+δ /R δ c and study the viability of the model for inflation in the Jordan and the Einstein frames. This model is further analysed by using the power spectrum indices of the inflation and the reheating temperature. During the inflationary evolution, the model predicts a value of δ parameter very close to one (δ = 0.98), while the reheating temperature Tre ∼ 10 17 GeV at δ = 0.98 is consistent with the standard approach to inflation and observations. We calculate the slow roll parameters for the minimally coupled scalar field within the framework of our model. It is found that the values of the scalar spectral index and tensor-to-scalar ratio are very close to the recent observational data, including those released by Planck 2018. We also show that the Jordan and the Einstein frames are equivalent when δ ∼ 1 by using the scalar spectral index, tensor-to-scalar ratio and reheating temperature.

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“…We assume that the number of e-foldings required to solve the problems of the ΛCDM model are 50 < N < 60 [18,39]. Therefore,…”

Section: Inflationary Dynamics and Reheating Temperaturementioning

confidence: 99%

Constraining $f(R)$ model through spectral indices and reheating temperature

Sharma,

Verma

2020

Preprint

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“…This is checked by taking the time derivative of (93) δẆ e 2X δẊ and using Eqs. (22) and (86). Then,…”

Section: A Scalar Solutionsmentioning

confidence: 99%

Higher-order modified Starobinsky inflation

Cuzinatto

Medeiros

Pompeia

2019

J. Cosmol. Astropart. Phys.

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An extension of the Starobinsky model is proposed. Besides the usual Starobinsky Lagrangian, a term proportional to the derivative of the scalar curvature, ∇µR∇ µ R, is considered. The analyzis is done in the Einstein frame with the introduction of a scalar field and a vector field. We show that inflation is attainable in our model, allowing for a graceful exit. We also build the cosmological perturbations and obtain the leading-order curvature power spectrum, scalar and tensor tilts and tensor-to-scalar ratio. The tensor and curvature power spectrums are compared to the most recent observations from BICEP2/Keck collaboration. We verify that the scalar-to-tensor rate r can be expected to be up to three times the values predicted by Starobinsky model.Hence, the fluid represented by Eq. (9) has no contribution from viscous shear components, which are null here. Notice that the heat flux vector exists solely due to the higher order term -were it absent, the theory would be reduced to Starobinsky's model and, therefore, would be represented by a perfect fluid energy-momentum tensor. The above equations are specified in FLRW spacetime in the next section.

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“…However, as has been stressed in the literature, the graceful exit from inflation is not enough, since the temperature of the Universe has decreased significantly and in effect it must be somehow be increased by some internal mechanism in the post-inflationary era, so that cosmic evolution will continue as we know from the standard Big Bang model [53][54][55][56][57][58][59]. This problem is usually addressed by the very own structure of the inflationary potential, that is expected to reach either a minimum, or some times an inflection point, where the inflation-generating scalar field will also generate the reheating of the Universe [40,. Of course, this idea has not come without restraints, since classical scalar fields, like the Higgs, are proved to block or delay the reheating [80,81], with some references claiming that auxiliary scalar fields [82] or some non-minimal gravitational couplings [83] are essential to the reheating phase.…”

Section: The Reheating Eramentioning

confidence: 99%

Canonical scalar field inflation with a Woods–Saxon potential

Oikonomou

Chatzarakis

2019

Annals of Physics

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This paper focuses on the realization of an inflationary model from a canonical scalar field theory with a Woods-Saxon potential, in the slow-roll approximation. Our analysis indicates that the observable quantities derived theoretically from our model, namely the spectral index of the primordial scalar curvature perturbations and the tensor-to-scalar ratio, are compatible with the latest Planck collaboration data. We also discuss the qualitative features of the potential, and we show that the value of the scalar field for which the graceful exit occurs, coincides with the inflection point of the scalar potential. We also attempt to study the post-inflation reheating phase of the model, in order to further examine the viability of the Woods-Saxon scalar field model, and as we demonstrate the results indicate viability of the model for this era too, however the instantaneous reheating is not allowed for the model at hand. PACS numbers: 04.50. Kd, 95.36.+x, 98.80.Cq,

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A viable logarithmicf(R) model for inflation

Cited by 16 publications

References 65 publications

Constraining $f(R)$ model through spectral indices and reheating temperature

Constraining $f(R)$ model through spectral indices and reheating temperature

Higher-order modified Starobinsky inflation

Canonical scalar field inflation with a Woods–Saxon potential

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