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Symmetry
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Symmetry and Problems in Modern Cosmology
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Symmetry and Problems in Modern Cosmology

A special issue of Symmetry (ISSN 2073-8994). This special issue belongs to the section "Physics".

Deadline for manuscript submissions: closed (30 April 2021) | Viewed by 9115

Special Issue Editor

Prof. Dr. Alexander Shalyt-Margolin

E-Mail Website
Guest Editor
Institute for Nuclear Problems, Belarusian State University, 220030 Minsk, Belarus
Interests: quantum theory; gravity, cosmology; dark energy problem; black holes physics (quantum aspects)
Special Issues, Collections and Topics in MDPI journals

Special Issue Information

Dear Colleague,

The notion of '''symmetry'' is fundamental for the whole theoretical physics. Modern cosmology, which is based on gravity, quantum theory, thermodynamics, and statistical mechanics, is no exception. In the recent decades, cosmology has stopped being a pure theoretical science, acquiring the experimental status as a result of the data obtained by means of WMAP, Hubble Space Telescope, Planck Space Observatory, and so on. Besides, considering that the potentialities for energy increase of modern and future colliders are rather limited, experimental studies for a high-energy physics are becoming increasingly prominent in cosmology in an effort to establish the «new physics», beyond the Standard Model.

Taking this into account, in experimental cosmology, a model of Lambda-Cold Dark Matter naturally becomes a problem of top priority, especially in regard to the selection of the adequate inflation scenario and to solutions of the Dark-Energy and Dark-Matter problems. It is hard to overestimate the role of symmetry as an instrument for studies in this context, on the one hand, because symmetry is an important component of the corresponding mathematical apparatus and, on the other hand, because, on the basis of theoretical calculations and experimental data, it logically limits the choice of solutions in cases when such a choice is too large.

Prof. Dr. Alexander Shalyt-Margolin
Guest Editor

Manuscript Submission Information

Manuscripts should be submitted online at www.mdpi.com by registering and logging in to this website. Once you are registered, click here to go to the submission form. Manuscripts can be submitted until the deadline. All submissions that pass pre-check are peer-reviewed. Accepted papers will be published continuously in the journal (as soon as accepted) and will be listed together on the special issue website. Research articles, review articles as well as short communications are invited. For planned papers, a title and short abstract (about 100 words) can be sent to the Editorial Office for announcement on this website.

Submitted manuscripts should not have been published previously, nor be under consideration for publication elsewhere (except conference proceedings papers). All manuscripts are thoroughly refereed through a single-blind peer-review process. A guide for authors and other relevant information for submission of manuscripts is available on the Instructions for Authors page. Symmetry is an international peer-reviewed open access monthly journal published by MDPI.

Please visit the Instructions for Authors page before submitting a manuscript. The Article Processing Charge (APC) for publication in this open access journal is 2400 CHF (Swiss Francs). Submitted papers should be well formatted and use good English. Authors may use MDPI's English editing service prior to publication or during author revisions.

Keywords

  • Lambda-CDM model
  • quantum cosmology
  • loop quantum cosmology
  • inflation models
  • cyclic models
  • dark-energy problem
  • dark-matter problem
  • large-scale structure of the universe
  • experimental measurements of cosmological parameters

Published Papers (5 papers)

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Research

14 pages, 491 KiB  
Article
AdS Black Holes in the Framework of Nonlinear Electrodynamics, Thermodynamics, and Joule–Thomson Expansion
by Sergey Il’ich Kruglov
Symmetry 2022, 14(8), 1597; https://doi.org/10.3390/sym14081597 - 03 Aug 2022
Cited by 5 | Viewed by 1059
Abstract
The thermodynamics and phase transitions of magnetic Anti-de Sitter black holes were studied. We considered extended-phase-space thermodynamics, with the cosmological constant being a thermodynamic pressure and the black hole mass being treated as a chemical enthalpy. The extended-phase-space thermodynamics of black holes mimic [...] Read more.
The thermodynamics and phase transitions of magnetic Anti-de Sitter black holes were studied. We considered extended-phase-space thermodynamics, with the cosmological constant being a thermodynamic pressure and the black hole mass being treated as a chemical enthalpy. The extended-phase-space thermodynamics of black holes mimic the behavior of a Van der Waals liquid. Quantities conjugated to the coupling of nonlinear electrodynamics (NED) and a magnetic charge are obtained. Thermodynamic critical points of phase transitions are investigated. It was demonstrated that the first law of black hole thermodynamics and the generalized Smarr relation hold. The Joule–Thomson adiabatic expansion of NED-AdS black holes is studied. The dependence of inversion temperature on pressure and the minimum of the inversion temperature are found. Full article
(This article belongs to the Special Issue Symmetry and Problems in Modern Cosmology)
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11 pages, 287 KiB  
Article
Einstein–Gauss–Bonnet Gravity with Nonlinear Electrodynamics: Entropy, Energy Emission, Quasinormal Modes and Deflection Angle
by Sergey Il’ich Kruglov
Symmetry 2021, 13(6), 944; https://doi.org/10.3390/sym13060944 - 26 May 2021
Cited by 13 | Viewed by 1499
Abstract
The logarithmic correction to Bekenshtein–Hawking entropy in the framework of 4D Einstein–Gauss–Bonnet gravity coupled with nonlinear electrodynamics is obtained. We explore the black hole solution with the spherically symmetric metric. The logarithmic term in the entropy has a structure similar to the entropy [...] Read more.
The logarithmic correction to Bekenshtein–Hawking entropy in the framework of 4D Einstein–Gauss–Bonnet gravity coupled with nonlinear electrodynamics is obtained. We explore the black hole solution with the spherically symmetric metric. The logarithmic term in the entropy has a structure similar to the entropy correction in the semi-classical Einstein equations. The energy emission rate of black holes and energy conditions are studied. The quasinormal modes of a test scalar field are investigated. The gravitational lensing of light around BHs was studied. We calculated the deflection angle for some model parameters. Full article
(This article belongs to the Special Issue Symmetry and Problems in Modern Cosmology)
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13 pages, 342 KiB  
Article
CPT Symmetry in Two-Fold de Sitter Universe
by Davide Fiscaletti, Ignazio Licata and Fabrizio Tamburini
Symmetry 2021, 13(3), 375; https://doi.org/10.3390/sym13030375 - 25 Feb 2021
Cited by 1 | Viewed by 1738
Abstract
The problem of baryon asymmetry unifies cosmology and particle physics at the hearth of theoretical physics. In this work, we consider the point of view of archaic cosmology based on the de Sitter hypersphere as topology of quantum vacuum. We show CPT symmetry [...] Read more.
The problem of baryon asymmetry unifies cosmology and particle physics at the hearth of theoretical physics. In this work, we consider the point of view of archaic cosmology based on the de Sitter hypersphere as topology of quantum vacuum. We show CPT symmetry derives from the nucleation of particles that divides the hypersphere in two mirror universes and defines big bang as a bifurcation point, as the creation of a de Sitter universe or a pair of entangled universes from “nothing”. Then, we direct our attention to the behavior of neutrinos in a CPT universe and discuss the differences between Majorana and Dirac neutrinos in the observational imprints of the entangled universes. Full article
(This article belongs to the Special Issue Symmetry and Problems in Modern Cosmology)
10 pages, 412 KiB  
Article
4D Einstein–Gauss–Bonnet Gravity Coupled with Nonlinear Electrodynamics
by Sergey Il’ich Kruglov
Symmetry 2021, 13(2), 204; https://doi.org/10.3390/sym13020204 - 27 Jan 2021
Cited by 8 | Viewed by 1546
Abstract
A new exact spherically symmetric and magnetically charged black hole solution in regularization scheme of Glavan and Lin is obtained. The nonlinear electrodynamics Lagrangian is given by LNED=−F/(1+2βF4) [...] Read more.
A new exact spherically symmetric and magnetically charged black hole solution in regularization scheme of Glavan and Lin is obtained. The nonlinear electrodynamics Lagrangian is given by LNED=−F/(1+2βF4), where F is the field invariant. We study the thermodynamics calculating the Hawking temperature and the heat capacity of the black hole. The phase transitions take place when the Hawking temperature has an extremum and the heat capacity is singular. We demonstrate that black holes are thermodynamically stable in some range of event horizon radii where the heat capacity is positive. The BH shadow radius is calculated and we study its dependance on model parameters. Full article
(This article belongs to the Special Issue Symmetry and Problems in Modern Cosmology)
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50 pages, 2319 KiB  
Article
Dyson’s Equations for Quantum Gravity in the Hartree–Fock Approximation
by Herbert W. Hamber and Lu Heng Sunny Yu
Symmetry 2021, 13(1), 120; https://doi.org/10.3390/sym13010120 - 12 Jan 2021
Cited by 1 | Viewed by 2551
Abstract
Unlike scalar and gauge field theories in four dimensions, gravity is not perturbatively renormalizable and as a result perturbation theory is badly divergent. Often the method of choice for investigating nonperturbative effects has been the lattice formulation, and in the case of gravity [...] Read more.
Unlike scalar and gauge field theories in four dimensions, gravity is not perturbatively renormalizable and as a result perturbation theory is badly divergent. Often the method of choice for investigating nonperturbative effects has been the lattice formulation, and in the case of gravity the Regge–Wheeler lattice path integral lends itself well for that purpose. Nevertheless, lattice methods ultimately rely on extensive numerical calculations, leaving a desire for alternate methods that can be pursued analytically. In this work, we outline the Hartree–Fock approximation to quantum gravity, along lines which are analogous to what is done for scalar fields and gauge theories. The starting point is Dyson’s equations, a closed set of integral equations which relate various physical amplitudes involving graviton propagators, vertex functions, and proper self-energies. Such equations are in general difficult to solve, and as a result they are not very useful in practice, but nevertheless provide a basis for subsequent approximations. This is where the Hartree–Fock approximation comes in, whereby lowest order diagrams get partially dressed by the use of fully interacting Green’s function and self-energies, which then lead to a set of self-consistent integral equations. The resulting nonlinear equations for the graviton self-energy show some remarkable features that clearly distinguish it from the scalar and gauge theory cases. Specifically, for quantum gravity one finds a nontrivial ultraviolet fixed point in Newton’s constant G for spacetime dimensions greater than two, and nontrivial scaling dimensions between d=2 and d=4, above which one obtains Gaussian exponents. In addition, the Hartree–Fock approximation gives an explicit analytic expression for the renormalization group running of Newton’s constant, suggesting gravitational antiscreening with Newton’s constant slowly increasing on cosmological scales. Full article
(This article belongs to the Special Issue Symmetry and Problems in Modern Cosmology)
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