Singular inflation

Barrow, John D.; Graham, Alexander A. H.

doi:10.1103/physrevd.91.083513

Cited by 82 publications

(104 citation statements)

References 50 publications

(52 reference statements)

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“…Exact examples displaying a generalised sudden singularity of the type identified by Barrow and Graham [62] for inflationary scalar fields with fractional potentials were found here. Lastly, the ranges for the values of the free parameters of the models have been considered which permit the universe to escape from the inflationary phase.…”

Section: Discussionmentioning

confidence: 81%

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Reconstructions of the dark-energy equation of state and the inflationary potential

Barrow

Paliathanasis

2018

Gen Relativ Gravit

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We use a mathematical approach based on the constraints systems in order to reconstruct the equation of state and the inflationary potential for the inflaton field from the observed spectral indices for the density perturbations n s and the tensor to scalar ratio r . From the astronomical data, we can observe that the measured values of these two indices lie on a two-dimensional surface. We express these indices in terms of the Hubble slow-roll parameters and we assume that n s − 1 = h (r ). For the function h (r ), we consider three cases, where h (r ) is constant, linear and quadratic, respectively. From this, we derive second-order equations whose solutions provide us with the explicit forms for the expansion scale-factor, the scalar-field potential, and the effective equation of state for the scalar field. Finally, we show that for there exist mappings which transform one cosmological solution to another and allow new solutions to be generated from existing ones.

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Section: Discussionmentioning

confidence: 81%

“…For small values of |φ| ,the potential, (67) becomes the power-law potential V (φ) φ − 2 3 , which means that finite-time singularities of the 'generalized sudden' type can follow [62]. Moreover, for the EoS for the scalar field it follows that the effective equation of state is…”

Section: Parabolic: N S − 1 Rmentioning

confidence: 99%

Reconstructions of the dark-energy equation of state and the inflationary potential

Barrow

Paliathanasis

2018

Gen Relativ Gravit

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“…In principle, the complex F (R) gravity cosmology can develop quite intriguing features, with the most sound one being the inability to analytically continue the Lorentz signature metric to a metric with a Euclidean signature, in the Jordan frame. Also, as shown in [35][36][37][38], bouncing cosmologies in the Jordan frame are never generated by complex F (R) gravity and also bouncing cosmologies in the Einstein frame never lead to complex F (R) gravity in the Jordan frame. However, as we demonstrated in this section, within the mimetic F (R) framework, a complex F (R) gravity in the Jordan frame may realize the matter bounce scenario, for suitably chosen mimetic potential and Lagrange multiplier.…”

Section: Inverse Reconstruction Methods For the F (R) Gravitymentioning

confidence: 99%

Accelerating cosmologies and the phase structure ofF(R)gravity with Lagrange multiplier constraints: A mimetic approach

Odintsov

Oikonomou

2016

Phys. Rev. D

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We study mimetic F (R) gravity with potential and Lagrange multiplier constraint. In the context of these theories, we introduce a reconstruction technique which enables us to realize arbitrary cosmologies, given the Hubble rate and an arbitrarily chosen F (R) gravity. We exemplify our method by realizing cosmologies that are in concordance with current observations (Planck data) and also well known bouncing cosmologies. The attribute of our method is that the F (R) gravity can be arbitrarily chosen, so we can have the appealing features of the mimetic approach combined with the known features of some F (R) gravities, which unify early-time with late-time acceleration. Moreover, we study the existence and the stability of de Sitter points in the context of mimetic F (R) gravity. In the case of unstable de Sitter points, it is demonstrated that graceful exit from inflation occurs. We also study the Einstein frame counterpart theory of the Jordan frame mimetic F (R) gravity, we discuss the general properties of the theory and exemplify our analysis by studying a quite interesting from a phenomenological point of view, model with two scalar fields. We also calculate the observational indices of the two scalar field model, by using the two scalar field formalism. Furthermore, we extensively study the dynamical system that corresponds to the mimetic F (R) gravity, by finding the fixed points and studying their stability. Finally, we modify our reconstruction method to function in the inverse way and thus yielding which F (R) gravity can realize a specific cosmological evolution, given the mimetic potential and the Lagrange multiplier.PACS numbers: 95.35.+d, 98.80.Cq, 95.36.+x

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“…In classical general relativity (GR), all inflationary models struggle with the inevitable big bang singularity [4][5][6]. One way to address this issue is to work in loop quantum cosmology (LQC), in which the big bang singularity is replaced by a quantum bounce [7][8][9][10].…”

Section: Introductionmentioning

confidence: 99%

Preinflationary Dynamics of Power-Law Potential in Loop Quantum Cosmology †

Shahalam

2018

Universe

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Abstract:In this article, I mainly discuss the dynamics of the pre-inflationary Universe for the potential V(φ) ∝ φ n with n = 5/3 in the context of loop quantum cosmology, in which the big bang singularity is resolved by a non-singular quantum bounce. In the case of the kinetic energy-dominated initial conditions of the scalar field at the bounce, the numerical evolution of the Universe can be split up into three regimes: bouncing, transition, and slow-roll inflation. In the bouncing regime, the numerical evolution of the scale factor does not depend on a wide range of initial values, or on the inflationary potentials. I calculate the number of e-folds in the slow-roll regime, by which observationally identified initial conditions are obtained. Additionally, I display the phase portrait for the model under consideration.

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Singular inflation

Cited by 82 publications

References 50 publications

Reconstructions of the dark-energy equation of state and the inflationary potential

Reconstructions of the dark-energy equation of state and the inflationary potential

Accelerating cosmologies and the phase structure ofF(R)gravity with Lagrange multiplier constraints: A mimetic approach

Preinflationary Dynamics of Power-Law Potential in Loop Quantum Cosmology †

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