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Light on Dark Worlds—A Themed Issue in Honor of Professor Maxim Yu. Khlopov on the Occasion of His 70th Birthday

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A special issue of Physics (ISSN 2624-8174). This special issue belongs to the section "High Energy Physics".

Deadline for manuscript submissions: closed (30 April 2022) | Viewed by 12807

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Special Issue Editors

Prof. Dr. Alexander S. Sakharov

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Guest Editor

1. Experimental Physics Department, CERN, 1211 Geneva 23, Switzerland
2. Department of Physics, Manhattan College, Riverdale, NY 10471, USA
Interests: astroparticle physics; cosmology; particle physics; advance statistics in data analysis
Special Issues, Collections and Topics in MDPI journals

Prof. Dr. Konstantin Belotsky

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Guest Editor

1. Moscow Engineering Physics Institute (MEPHI), National Research Nuclear University (NRNU), Kashirskoe shosse 31, 115409 Moscow, Russia
2. Virtual Institute of Astroparticle Physics, University of Paris, CNRS, Astroparticle and Cosmology, F-75013 Paris, France
Interests: cosmoparticle physics; dark matter; cosmic rays; primordial black holes; particle physics
Special Issues, Collections and Topics in MDPI journals

Prof. Dr. Sergey G. Rubin

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Guest Editor

1. Moscow Engineering Physics Institute (MEPHI), National Research Nuclear University (NRNU), Kashirskoe shosse 31, 115409 Moscow, Russia
2. N.I. Lobachevsky Institute of Mathematics and Mechanics, Kazan Federal University, Kremlevskaya Street 18, 420008 Kazan, Russia
Interests: cosmology; multidimensional gravity; primordial black holes

Special Issue Information

Dear Colleagues,

This Special Issue of Physics is dedicated to Professor Dr. Maxim Yu. Khlopov in honor of his 70th birthday. Professor Khlopov is a pioneer in cosmological probes of new physics and the development of cosmoparticle physics, studying the fundamental relationship between cosmology and particle physics in the cross-disciplinary links with its physical, cosmological, and astrophysical signatures. M. Yu. Khlopov’s interest in physics has been in studying the physical basis of modern cosmology and revealing nontrivial features of phenomena, going beyond the standard models of cosmology and particle physics. We open this Special Issue to all areas of physics, shedding light on such phenomena.

We congratulate M. Yu. Khlopov on his birthday and wish him many happy, fruitful years ahead, new fundamental discoveries, and talented disciples. We believe that this Special Issue constitutes a timely celebration of this respected scholar, researcher, and friend. Furthermore, we hope that this Special Issue will inspire scholars, especially junior researchers, to continue the advancement of physics.

Prof. Dr. Alexander S. Sakharov
Prof. Dr. Konstantin Belotsky
Prof. Dr. Sergey G. Rubin
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. Physics is an international peer-reviewed open access quarterly 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 1400 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

Cosmoparticle physics
Astroparticle physics
Particle physics
Dark matter
Primordial black holes
Inflation
Baryosynthesis
Dark matter
Beyond Standard Model physics
Antimatter
Mirror world

Published Papers (6 papers)

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Research

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12 pages, 353 KiB

Open AccessArticle

The Birth of the Universe as a Result of the Change of the Metric Signature

by Tatyana P. Shestakova

Physics 2022, 4(1), 160-171; https://0-doi-org.brum.beds.ac.uk/10.3390/physics4010012 - 07 Feb 2022

Cited by 2 | Viewed by 2184

Abstract

In this paper, I discuss the idea that the birth of our Universe may be a result of a quantum transition from a physical continuum with the Euclidean signature to a Lorentzian spacetime. A similar idea was expressed by Andrei D. Sakharov At the classical level, the idea was studied by George F. R. Ellis and his collaborators, who explored if solutions to the classical Einstein equation exist which admit a change of metric signature. The present paper aims at examining possible realizations of this idea at the level of quantum gravity, in the framework of the Wheeler–DeWitt theory and in the extended phase space approach to quantization of gravity. I intend to answer the questions: to answer the questions: Does the Hartle–Hawking wave function imply such a realization? How can this idea be realized in the extended phase space approach to quantum gravity, where the change of signature is described by imposing special conditions on

g_{00}

-component of the metric in different regions of the physical continuum? The conclusion is that the idea can be realized from a formal mathematical point of view, but it can hardly help in understanding how spacetime structure and time itself appeared from a timeless continuum. Full article

(This article belongs to the Special Issue Light on Dark Worlds—A Themed Issue in Honor of Professor Maxim Yu. Khlopov on the Occasion of His 70th Birthday)

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8 pages, 364 KiB

Open AccessArticle

Some Features of the Direct and Inverse Double-Compton Effect as Applied to Astrophysics

by Viktor Dubrovich and Timur Zalialiutdinov

Physics 2021, 3(4), 1167-1174; https://0-doi-org.brum.beds.ac.uk/10.3390/physics3040074 - 29 Nov 2021

Cited by 1 | Viewed by 1992

Abstract

In the present paper, the process of inverse double-Compton (IDC) scattering is considered in the context of astrophysical applications. It is assumed that the two hard X-ray photons emitted from an astrophysical source are scattered on a free electron and converted into a single soft photon of optical range. Using the QED S-matrix formalism for the derivation of a cross-section of direct double-Compton (DDC) scattering and assuming detailed balance conditions, an analytical expression for the cross-section of the IDC process is presented. It is shown that at fixed energies of incident photons, the inverse cross-section has no infrared divergences, and its behavior is completely defined by the spectral characteristics of the photon source itself, in particular by the finite interaction time of radiation with an electron. Thus, even for the direct process, the problem of resolving infrared divergence actually refers to a real physical source of radiation in which photons are never actually plane waves. As a result, the physical frequency profile of the scattered radiation for DDC as well as for IDC processes is a function of both the intensity and line shape of the incident photon field. Full article

(This article belongs to the Special Issue Light on Dark Worlds—A Themed Issue in Honor of Professor Maxim Yu. Khlopov on the Occasion of His 70th Birthday)

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10 pages, 458 KiB

Open AccessArticle

Stellar Structure in a Newtonian Theory with Variable G

by Júlio C. Fabris, Túlio Ottoni, Júnior D. Toniato and Hermano Velten

Physics 2021, 3(4), 1123-1132; https://0-doi-org.brum.beds.ac.uk/10.3390/physics3040071 - 25 Nov 2021

Cited by 3 | Viewed by 1955

Abstract

A Newtonian-like theory inspired by the Brans–Dicke gravitational Lagrangian has been recently proposed by us. For static configurations, the gravitational coupling acquires an intrinsic spatial dependence within the matter distribution. Therefore, the interior of astrophysical configurations may provide a testable environment for this approach as long as no screening mechanism is evoked. In this work, we focus on the stellar hydrostatic equilibrium structure in such a varying Newtonian gravitational coupling G scenario. A modified Lane–Emden equation is presented and its solutions for various values of the polytropic index are discussed. The role played by the theory parameter

ω

, the analogue of the Brans–Dicke parameter, in the physical properties of stars is discussed. Full article

(This article belongs to the Special Issue Light on Dark Worlds—A Themed Issue in Honor of Professor Maxim Yu. Khlopov on the Occasion of His 70th Birthday)

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7 pages, 232 KiB

Open AccessArticle

Supervisor of the Universe

by Victor A. Berezin and Vyacheslav I. Dokuchaev

Physics 2021, 3(4), 814-820; https://0-doi-org.brum.beds.ac.uk/10.3390/physics3040051 - 23 Sep 2021

Cited by 4 | Viewed by 1844

Abstract

In this paper, conformal invariant gravitation, based on Weyl geometry, is considered. In addition to the gravitational and matter action integrals, the interaction between the Weyl vector (entered in Weyl geometry) and the vector, representing the world line of the independent observer, are introduced. It is shown that the very existence of such an interaction selects the exponentially growing scale factor solutions among the cosmological vacua. Full article

(This article belongs to the Special Issue Light on Dark Worlds—A Themed Issue in Honor of Professor Maxim Yu. Khlopov on the Occasion of His 70th Birthday)

9 pages, 306 KiB

Open AccessArticle

Local Regions with Expanding Extra Dimensions

by Kirill A. Bronnikov and Sergey G. Rubin

Physics 2021, 3(3), 781-789; https://0-doi-org.brum.beds.ac.uk/10.3390/physics3030048 - 13 Sep 2021

Cited by 2 | Viewed by 1568

Abstract

In this paper possible spatial domains, containing expanding extra dimensions, are studied. It is demonstrated that these domains are predicted in the framework of

f (R)

gravity (where R is the scalar curviture) and could appear due to quantum fluctuations during [...] Read more.

In this paper possible spatial domains, containing expanding extra dimensions, are studied. It is demonstrated that these domains are predicted in the framework of

f (R)

gravity (where R is the scalar curviture) and could appear due to quantum fluctuations during inflation. The interior of the domains is shown to be characterized by the multidimensional curvature ultimately tending to zero and a slowly growing size of the extra dimensions. Full article

(This article belongs to the Special Issue Light on Dark Worlds—A Themed Issue in Honor of Professor Maxim Yu. Khlopov on the Occasion of His 70th Birthday)

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8 pages, 599 KiB

Open AccessOpinion

Distinctive Features of Charge Exchange Involving the Second Flavor of Hydrogen Atoms—The Candidates for Dark Matter

by Eugene Oks

Physics 2022, 4(1), 286-293; https://0-doi-org.brum.beds.ac.uk/10.3390/physics4010019 - 23 Feb 2022

Viewed by 1708

Abstract

The second flavor of hydrogen atoms (SFHA) refers to the kind of hydrogen atoms that have only the states of the zero orbital angular momentum (the S-states), both in the discrete and continuous spectra. They were first discovered theoretically in one of my earlier papers, where a proof of their existence was also provided by analyzing atomic experiments concerning the high-energy tail of the linear momentum distribution in the ground state of hydrogen atoms. From a theoretical point of view, the discovery was based on the standard Dirac equation for hydrogen atoms without changing the existing physical laws. Recently, the existence of the SFHA was seemingly also confirmed by two types of astrophysical observations: the allowance for the SFHA explained the puzzling results concerning both the anomalous absorption of the redshifted 21 cm spectral line from the early Universe, and the observations by the Dark Energy Survey (DES) team where it was found that the distribution of dark matter in the Universe is noticeably smoother than predictions employing Einstein’s relativity. In the present review, we exhibit results from two recent papers where attention was brought to a visible difference in the cross-sections of the resonant charge exchange for collisions of the SFHA with incoming protons, compared to collisions of the usual hydrogen atoms with incoming protons. It was shown that, after taking into account the SFHA, there is a better agreement with the corresponding experimental cross-section. Coupled with the previous evidence of the existence of the SFHA, deduced from the analysis of the other kind of atomic experiments, and evidenced by two different kinds of astrophysical observations, this strengthens the standing of the SFHA as the most probable candidate for all or a part of dark matter. Full article

(This article belongs to the Special Issue Light on Dark Worlds—A Themed Issue in Honor of Professor Maxim Yu. Khlopov on the Occasion of His 70th Birthday)

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