scholarly journals Construction of the cosmological model with periodically distributed inhomogeneities with growing amplitude

2021 ◽  
Vol 81 (3) ◽  
Author(s):  
Szymon Sikora ◽  
Krzysztof Głód
Keyword(s):  
Hubble Constant ◽  
De Sitter ◽  
Einstein Tensor ◽  
Cosmological Perturbation ◽  
Cosmological Perturbation Theory ◽  
Local Measurements ◽  
Sitter Background ◽  
Local Observables ◽  
Homogeneous Background ◽  
Physical Quantities

AbstractWe construct an approximate solution to the cosmological perturbation theory around Einstein–de Sitter background up to the fourth-order perturbations. This could be done with the help of the specific symmetry condition imposed on the metric, from which follows that the model density forms an infinite, cubic lattice. To verify the convergence of the perturbative construction, we express the resulting metric as a polynomial in the perturbative parameter and calculate the exact Einstein tensor. In our model, it seems that physical quantities averaged over large scales overlap with the respective Einstein–de Sitter prediction, while local observables could differ significantly from their background counterparts. As an example, we analyze the behavior of the local measurements of the Hubble constant and compare them with the Hubble constant of the homogeneous background model. A difference between these quantities is important in the context of a current Hubble tension problem.

scholarly journals de Sitter spacetime with a Becchi–Rouet–Stora quartet

2017 ◽  
Vol 26 (11) ◽  
pp. 1750132 ◽  
Author(s):  
Rio Saitou ◽  
Yungui Gong
Keyword(s):  
Field Theory ◽  
Second Order ◽  
De Sitter Spacetime ◽  
De Sitter ◽  
Cosmological Perturbation ◽  
Curvature Perturbation ◽  
Cosmological Perturbation Theory ◽  
Sitter Spacetime ◽  
Sitter Background ◽  
Brs Symmetry

We generalize the topological model recently proposed and investigate the cosmological perturbations of the model. The model has an exact de Sitter background solution associated with the Becchi–Rouet–Stora (BRS) quartet terms which are regarded as the Lagrangian density of the topological field theory. The de Sitter solution can be selected without spontaneously breaking the BRS symmetry, and be interpreted as a gauge fixing of de Sitter spacetime. The BRS symmetry is preserved for the perturbations around the de Sitter background before we solve the constraints of general relativity. We derive action to the second-order of the perturbations and confirm that even after solving the constraints, we have the BRS symmetry at least for the second-order action. We construct the cosmological perturbation theory involving the BRS sector, and obtain the two-point correlation functions for the curvature perturbation and the isocurvature perturbations which compose the BRS sector. Our result gives a new description for de Sitter spacetime and the quantum field theory in de Sitter spacetime.

scholarly journals Hawking’s radiation in non-stationary rotating de Sitter background

2011 ◽  
Vol 333 (1) ◽  
pp. 175-185 ◽  
Author(s):  
N. Ibohal ◽  
T. Ibungochouba
Keyword(s):  
De Sitter ◽  
Sitter Background

Dirac particle in electric field with confining scalar potential on (anti)-de Sitter background

2018 ◽  
Vol 33 (34) ◽  
pp. 1850202 ◽  
Author(s):  
N. Messai ◽  
B. Hamil ◽  
A. Hafdallah
Keyword(s):  
Energy Spectrum ◽  
Dirac Equation ◽  
Electric Field ◽  
Scalar Potential ◽  
Dirac Particle ◽  
Wave Functions ◽  
De Sitter ◽  
Sitter Background ◽  
Position Representation

In this paper, we study the (1 + 1)-dimensional Dirac equation in the presence of electric field and scalar linear potentials on (anti)-de Sitter background. Using the position representation, the energy spectrum and the corresponding wave functions are exactly obtained.

scholarly journals Maximum turnaround radius in f(R) gravity

2019 ◽  
Vol 28 (03) ◽  
pp. 1950058 ◽  
Author(s):  
Salvatore Capozziello ◽  
Konstantinos F. Dialektopoulos ◽  
Orlando Luongo
Keyword(s):  
Large Scale ◽  
A Priori ◽  
Spherically Symmetric ◽  
Cosmological Perturbation ◽  
Suitable Alternative ◽  
Cosmological Perturbation Theory ◽  
Large Scale Structures ◽  
Scale Structures ◽  
Analytic Expression ◽  
Prescription Rules

The accelerating behavior of cosmic fluid opposes gravitational attraction at present epoch, whereas standard gravity is dominant at small scales. As a consequence, there exists a point where the effects are counterbalanced, dubbed turnaround radius, [Formula: see text]. By construction, it provides a bound on maximum structure sizes of the observed universe. Once an upper bound on [Formula: see text] is provided, i.e. [Formula: see text], one can check whether cosmological models guarantee structure formation. Here, we focus on [Formula: see text] gravity, without imposing a priori the form of [Formula: see text]. We thus provide an analytic expression for the turnaround radius in the framework of [Formula: see text] models. To figure this out, we compute the turnaround radius in two distinct cases: (1) under the hypothesis of static and spherically symmetric spacetime, and (2) by using the cosmological perturbation theory. We thus find a criterion to enable large scale structures to be stable in [Formula: see text] models, circumscribing the class of [Formula: see text] theories as suitable alternative to dark energy. In particular, we get that for constant curvature, the viability condition becomes [Formula: see text], with [Formula: see text] and [Formula: see text], respectively, the observed cosmological constant and the Ricci curvature. This prescription rules out models which do not pass the aforementioned [Formula: see text] limit.

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