Viable super inflation scenario from F(T) modified teleparallel gravity

Keskin, A. I.

doi:10.1140/epjc/s10052-018-6199-9

Cited by 17 publications

(4 citation statements)

References 58 publications

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“…Of course inflation is known to start quite earlier than the horizon crossing time instance, but we choose t i to be the horizon crossing time instance, because the condition k = aH is vital for the calculation of the power spectrum, both scalar and tensor. Also we need to note that the initial condition of the constant-roll k-inflation theory may be a Bunch-Davies vacuum state [82] or a quasi-de Sitter like expansion which leads to a Bunch-Davies vacuum state [83]. Expressed in terms of the scalar field, the e-foldings number is equal to,…”

Section: Constant-roll K-inflation Gravity: Equations Of Motion and I...mentioning

confidence: 99%

Constant-roll k-inflation dynamics

Odintsov

Oikonomou

2019

Class. Quantum Grav.

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In this work we shall investigate the phenomenological implications of the constant-roll condition on a k-Inflation theory of gravity. The latter theories are particularly promising, since these remained robust to the results of GW170817, since these have a gravitational wave speed cT = 1 in natural units. We shall mainly focus on the phenomenology of the k-Inflation models, with the only assumption being the slow-roll condition imposed on the first and fourth slow-roll parameters, and the constant-roll condition for the evolution of the scalar field. We present in detail the final form of the gravitational equations of motion that control the dynamics of the cosmological system, with the constant-roll condition imposed, and by using a conveniently, from the perspective of analytical manipulations, chosen potential, we express the slow-roll indices and the resulting observational indices of the theory as functions of the e-foldings number. The results of our analysis indicate that the constant-roll k-Inflation theory can be compatible with the Planck 2018 data, for a wide range of the free parameters. Also we examine in a quantitative way the effects of the constantroll condition on the parameter f equil NL on which the bispectrum is proportional, in the equilateral momentum approximation, and we demonstrate that the effect of the constant-roll condition is nontrivial. In effect, non-Gaussianities in the theory may be enhanced, a phenomenon which is known to be produced by constant-roll scalar theories of gravity in general.PACS numbers: 04.50. Kd, 95.36.+x, 98.80.Cq,

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Section: Constant-roll K-inflation Gravity: Equations Of Motion and I...mentioning

confidence: 99%

Constant-roll k-inflation dynamics

Odintsov

Oikonomou

2019

Class. Quantum Grav.

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“…From a thermodynamics perspective, it was obtained the Friedmann equations in the studies [7,63]. In the background of the line element which describes a homogeneous and isotropic spacetime geometry, i.e., Friedmann-Robertson-Walker metric,…”

Section: Modified Friedmann Equationsmentioning

confidence: 99%

“…It is worth emphasizing that the slow-roll indices, and consequently, the inflation parameters (7) should be calculated at the horizon crossing point(k = a H) as the fluctuations in the inflation field [71,72] (scalar field φ) become crucial at this point. Here, k shows the comoving wave vectors [63,73]. We assume that the inflation begins where the fluctuations of the field occur during the horizon crossing.…”

Section: Modified Friedmann Equationsmentioning

confidence: 99%

Constant-roll inflation field with Tsallis entopic proposal

Keskin

Kurt

2023

Eur. Phys. J. C

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In this work, we investigate the high-energy era of the universe from the constant-roll condition perspective by taking the Friedmann equation, which is modified by a non-additive Tsallis entropic proposal. In the framework of the observational data, we determine the constant-roll parameter. Under the fixed field condition of the constant-roll parameter, for the wide range of the power-term of the chaotic potentials, $$\sim \phi ^{n}$$ ∼ ϕ n , which involves some string-chaotic potential models, $$n=\frac{2}{3}$$ n = 2 3 , $$n=\frac{4}{5}$$ n = 4 5 , the non-additive (nonextensive) Tsallis parameter is analyzed graphically. The resulting analysis shows that, in addition to a quasi-de Sitter phase, any value of the range $$0.5<n<1.2$$ 0.5 < n < 1.2 points to a dynamical form of the dark energy (quintessence) in the early universe. It implies that n values in the range may be included in string-chaotic potential models. The non-additive Tsallis parameter provides this with the help of its negative values in the constant-roll field.

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“…The nature of the inflaton field motivated the elaboration of a plethora of competing cosmological models [10][11][12][13][14][15][16][17][18][19] due to the fact that the form of the inflation field is not determined and the standard phenomenological model Λ cold dark matter (ΛCDM) with the fluid parameter w = −1 rapidly decays at the end of the inflationary period [20]. Thus, the inflaton field cannot be directly regarded as a cosmological constant Λ for the late acceleration of the universe.…”

Section: Introductionmentioning

confidence: 99%

Effective Potential for Quintessential Inflation Driven by Extrinsic Gravity

Capistrano,

Cabral

2023

Universe

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We numerically study the evolution of the extrinsic energy density in the context of an inflationary regime at the background level in a five-dimensional model using a Bayesian analysis from a dynamic nested sampler (DYNESTY) code. By means of the Nash–Greene embedding theorem, we show that the corresponding model provides an effective potential driven by the influence of extrinsic geometry. We obtain a quintessential inflation that defines a model with a potential V(ϕ)=e−α1ϕ(1−α2ϕ2), where α1 and α2 are dimensionless parameters. Using some known phenomenological parameterizations, such as Chevallier–Polarski–Linder (CPL) and Barboza–Alcaniz (BA) parameterizations, we show that the model reflects a slow-varying inflation preferring a thawing behavior, suggesting an optimistic scenario for further research on the unification of inflation with late cosmic acceleration.

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Viable super inflation scenario from F(T) modified teleparallel gravity

Cited by 17 publications

References 58 publications

Constant-roll k-inflation dynamics

Constant-roll k-inflation dynamics

Constant-roll inflation field with Tsallis entopic proposal

Effective Potential for Quintessential Inflation Driven by Extrinsic Gravity

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