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Symmetry
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Symmetry with Gravity and Particle Theories
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Symmetry with Gravity and Particle Theories

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

Deadline for manuscript submissions: closed (30 November 2020) | Viewed by 12303

Special Issue Editors

Prof. Dr. Shin'ichi Nojiri

E-Mail Website
Guest Editor
Division of Particle and Astrophysical Science, Nagoya University, Nagoya, Aichi 466-8550, Japan
Interests: particle cosmology; quantum field theory; gravity
Prof. Dr. Taishi Katsuragawa

E-Mail Website
Guest Editor
CCNU (Hua-Zhong Normal U.)
Interests: gravitation and cosmology

Special Issue Information

Dear Colleagues,

Symmetry is the most important guiding principle for constructing realistic theories of gravity and particles. Gauge symmetries, that is, local symmetries, play the main role in obtaining consistent quantum theories for the models of particles with a spin of greater than or equal to one, such as with gauge particles and graviton. Furthermore, gauge symmetries strongly restrict the models. On the other hand, many global symmetries appear in low-energy effective theories, although there seems to be no exact global symmetry, which is broken either spontaneously or explicitly. Low energy symmetries may also appear emergently.

In our Special Issue on “Symmetry with Gravity and Particle Theories”, we review the role of symmetries in gravity and particle theories, origins of symmetries, mechanisms of breakdown, relations between the symmetries, and other related topics.

Prof. Dr. Shin'ichi Nojiri
Prof. Dr. Taishi Katsuragaw
Guest Editors

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

  • local symmetry
  • global symmetry
  • breakdown of symmetries
  • origin of symmetries
  • emergent symmetries

Published Papers (5 papers)

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Research

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7 pages, 269 KiB  
Article
Cartan F(R) Gravity and Equivalent Scalar–Tensor Theory
by Tomohiro Inagaki and Masahiko Taniguchi
Symmetry 2022, 14(9), 1830; https://doi.org/10.3390/sym14091830 - 3 Sep 2022
Cited by 6 | Viewed by 1017
Abstract
We investigate the Cartan formalism in F(R) gravity. F(R) gravity has been introduced as a theory to explain cosmologically accelerated expansions by replacing the Ricci scalar R in the Einstein–Hilbert action with a function of R. [...] Read more.
We investigate the Cartan formalism in F(R) gravity. F(R) gravity has been introduced as a theory to explain cosmologically accelerated expansions by replacing the Ricci scalar R in the Einstein–Hilbert action with a function of R. As is well-known, F(R) gravity is rewritten as a scalar–tensor theory by using the conformal transformation. Cartan F(R) gravity is described based on the Riemann–Cartan geometry formulated by the vierbein-associated local Lorenz symmetry. In the Cartan formalism, the Ricci scalar R is divided into two parts: one derived from the Levi–Civita connection and the other from the torsion. Assuming the spin connection-independent matter action, we have successfully rewritten the action of Cartan F(R) gravity into the Einstein–Hilbert action and a scalar field with canonical kinetic and potential terms without any conformal transformations. red Thus, symmetries in Cartan F(R) gravity are clearly conserved. The resulting scalar–tensor theory is useful in applications of the usual slow-roll scenario. As a simple case, we employ the Starobinsky model and evaluate fluctuations in cosmological microwave background radiation. Full article
(This article belongs to the Special Issue Symmetry with Gravity and Particle Theories)
8 pages, 269 KiB  
Article
Polarized Initial States of Primordial Gravitational Waves
by Sugumi Kanno and Jiro Soda
Symmetry 2020, 12(4), 672; https://doi.org/10.3390/sym12040672 - 23 Apr 2020
Cited by 4 | Viewed by 1896
Abstract
Polarizations of primordial gravitational waves can be relevant when considering an inflationary universe in modified gravity or when matter fields survive during inflation. Such polarizations have been discussed in the Bunch–Davies vacuum. Instead of taking into account the dynamical generation of polarizations of [...] Read more.
Polarizations of primordial gravitational waves can be relevant when considering an inflationary universe in modified gravity or when matter fields survive during inflation. Such polarizations have been discussed in the Bunch–Davies vacuum. Instead of taking into account the dynamical generation of polarizations of gravitational waves, in this paper, we consider polarized initial states constructed from S U ( 2 ) coherent states. We then evaluate the power spectrums of the primordial gravitational waves in the states. Full article
(This article belongs to the Special Issue Symmetry with Gravity and Particle Theories)
13 pages, 315 KiB  
Article
Mass, Spacetime Symmetry, de Sitter Vacuum, and the Higgs Mechanism
by Irina Dymnikova
Symmetry 2020, 12(4), 634; https://doi.org/10.3390/sym12040634 - 16 Apr 2020
Cited by 11 | Viewed by 2080
Abstract
We address the question of the intrinsic relation between mass, gravity, spacetime symmetry, and the Higgs mechanism implied by involvement of the de Sitter vacuum as its basic ingredient (a false vacuum). Incorporating the de Sitter vacuum, the Higgs mechanism implicitly incorporates the [...] Read more.
We address the question of the intrinsic relation between mass, gravity, spacetime symmetry, and the Higgs mechanism implied by involvement of the de Sitter vacuum as its basic ingredient (a false vacuum). Incorporating the de Sitter vacuum, the Higgs mechanism implicitly incorporates the generic relation between mass, gravity, and spacetime symmetry revealed in the frame of General Relativity for all objects involving the de Sitter vacuum. We overview two observational cases which display and verify this relation, the case known as “negative mass square problem” for neutrino, and appearance of a minimal length scale in e + e − annihilation. Full article
(This article belongs to the Special Issue Symmetry with Gravity and Particle Theories)
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6 pages, 215 KiB  
Article
A Symmetry of the Einstein–Friedmann Equations for Spatially Flat, Perfect Fluid, Universes
by Valerio Faraoni
Symmetry 2020, 12(1), 147; https://doi.org/10.3390/sym12010147 - 10 Jan 2020
Cited by 10 | Viewed by 2020
Abstract
We report a symmetry property of the Einstein–Friedmann equations for spatially flat Friedmann–Lemaître–Robertson–Walker universes filled with a perfect fluid with any constant equation of state. The symmetry transformations form a one-parameter Abelian group. Full article
(This article belongs to the Special Issue Symmetry with Gravity and Particle Theories)

Review

Jump to: Research

24 pages, 441 KiB  
Review
Symmetry Restoration and Breaking at Finite Temperature: An Introductory Review
by Eibun Senaha
Symmetry 2020, 12(5), 733; https://doi.org/10.3390/sym12050733 - 5 May 2020
Cited by 29 | Viewed by 4558
Abstract
Symmetries at finite temperature are of great importance to understand dynamics of spontaneous symmetry breaking phenomena, especially phase transitions in early Universe. Some symmetries such as the electroweak symmetry can be restored in hot environment. However, it is a nontrivial question that the [...] Read more.
Symmetries at finite temperature are of great importance to understand dynamics of spontaneous symmetry breaking phenomena, especially phase transitions in early Universe. Some symmetries such as the electroweak symmetry can be restored in hot environment. However, it is a nontrivial question that the phase transition occurs via first or second order, or even smooth crossover, which strongly depends on underlying physics. If it is first order, gravitational waves can be generated, providing a detectable signal of this epoch. Moreover, the baryon asymmetry of the Universe can also arise under some conditions. In this article, the electroweak phase transition is reviewed, focusing particularly on the case of the first-order phase transition. Much attention is paid to multi-step phase transitions in which additional symmetry breaking such as a spontaneous Z 2 breaking plays a pivotal role in broadening the possibility of the first-order electroweak phase transition. On the technical side, we review thermal resummation that mitigates a bad infrared behavior related to the symmetry restoration. In addition, gauge and scheme dependences of perturbative calculations are also briefly discussed. Full article
(This article belongs to the Special Issue Symmetry with Gravity and Particle Theories)
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