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  • Gravity with Higher Derivatives in D-Dimensions
    Universe (IF 1.752) Pub Date : 2020-10-20
    Sergey G. Rubin; Arkadiy Popov; Polina M. Petriakova

    The aim of this review is to discuss the ways to obtain results based on gravity with higher derivatives in D-dimensional world. We considered the following ways: (1) reduction to scalar tensor gravity, (2) direct solution of the equations of motion, (3) derivation of approximate equations in the presence of a small parameter in the system, and (4) the method of test functions. Some applications are

  • Gravitational Radiation as the Bremsstrahlung of Superheavy Particles in the Early Universe
    Universe (IF 1.752) Pub Date : 2020-10-20
    Andrey A. Grib; Yuri V. Pavlov

    The number of superheavy particles with the mass of the Grand Unification scale with trans-Planckian energy created at the epoch of superheavy particle creation from the vacuum by the gravitation of the expanding Universe is calculated. In later collisions of these particles, gravitational radiation is radiated playing the role of bremsstrahlung for gravity. The effective background radiation of the

  • Collapsing Wormholes Sustained by Dustlike Matter
    Universe (IF 1.752) Pub Date : 2020-10-18
    Pavel E. Kashargin; Sergey V. Sushkov

    It is well known that static wormhole configurations in general relativity (GR) are possible only if matter threading the wormhole throat is “exotic”—i.e., violates a number of energy conditions. For this reason, it is impossible to construct static wormholes supported only by dust-like matter which satisfies all usual energy conditions. However, this is not the case for non-static configurations.

  • Search for Double Beta Decay of 106Cd with an Enriched 106CdWO4 Crystal Scintillator in Coincidence with CdWO4 Scintillation Counters
    Universe (IF 1.752) Pub Date : 2020-10-16
    Pierluigi Belli; R. Bernabei; V.B. Brudanin; F. Cappella; V. Caracciolo; R. Cerulli; F. A. Danevich; Antonella Incicchitti; D.V. Kasperovych; V.R. Klavdiienko; V.V. Kobychev; Vittorio Merlo; O.G. Polischuk; V.I. Tretyak; M.M. Zarytskyy

    Studies on double beta decay processes in 106Cd were performed by using a cadmium tungstate scintillator enriched in 106Cd at 66% (106CdWO4) with two CdWO4 scintillation counters (with natural Cd composition). No effect was observed in the data that accumulated over 26,033 h. New improved half-life limits were set on the different channels and modes of the 106Cd double beta decay at level of limT1/2∼1020−1022

  • Null and Timelike Geodesics near the Throats of Phantom Scalar Field Wormholes
    Universe (IF 1.752) Pub Date : 2020-10-16
    Ivan Potashov; Julia Tchemarina; Alexander Tsirulev

    We study geodesic motion near the throats of asymptotically flat, static, spherically symmetric traversable wormholes supported by a self-gravitating minimally coupled phantom scalar field with an arbitrary self-interaction potential. We assume that any such wormhole possesses the reflection symmetry with respect to the throat, and consider only its observable “right half”. It turns out that the main

  • Gravitational Interaction of Cosmic String with Spinless Particle
    Universe (IF 1.752) Pub Date : 2020-10-16
    Pavel Spirin

    We consider the gravitational interaction of spinless relativistic particle and infinitely thin cosmic string within the classical linearized-theory framework. We compute the particle’s motion in the transverse (to the unperturbed string) plane. The reciprocal action of the particle on the cosmic string is also investigated. We derive the retarded solution which includes the longitudinal (with respect

  • On the Discrete Version of the Schwarzschild Problem
    Universe (IF 1.752) Pub Date : 2020-10-17
    Vladimir Khatsymovsky

    We consider a Schwarzschild type solution in the discrete Regge calculus formulation of general relativity quantized within the path integral approach. Earlier, we found a mechanism of a loose fixation of the background scale of Regge lengths. This elementary length scale is defined by the Planck scale and some free parameter of such a quantum extension of the theory. Besides, Regge action was reduced

  • The Higgs Mechanism and Spacetime Symmetry
    Universe (IF 1.752) Pub Date : 2020-10-15
    Irina Dymnikova

    In this review, we summarize the results of the analysis of the inherent relation between the Higgs mechanism and spacetime symmetry provided by generic incorporation of the de Sitter vacuum as a false vacuum with the equation of state p=−ρ. This relation has been verified by the application for the interpretation of the experimental results on the negative mass squares for neutrinos, and of the appearance

  • An Alternative to Dark Matter and Dark Energy: Scale-Dependent Gravity in Superfluid Vacuum Theory
    Universe (IF 1.752) Pub Date : 2020-10-15
    Konstantin G. Zloshchastiev

    We derive an effective gravitational potential, induced by the quantum wavefunction of a physical vacuum of a self-gravitating configuration, while the vacuum itself is viewed as the superfluid described by the logarithmic quantum wave equation. We determine that gravity has a multiple-scale pattern, to such an extent that one can distinguish sub-Newtonian, Newtonian, galactic, extragalactic and cosmological

  • Quantum Vacuum Effects in Braneworlds on AdS Bulk
    Universe (IF 1.752) Pub Date : 2020-10-15
    Aram A. Saharian

    We review the results of investigations for brane-induced effects on the local properties of quantum vacuum in background of AdS spacetime. Two geometries are considered: a brane parallel to the AdS boundary and a brane intersecting the AdS boundary. For both cases, the contribution in the vacuum expectation value (VEV) of the energy–momentum tensor is separated explicitly and its behavior in various

  • Relativistic Effects in Orbital Motion of the S-Stars at the Galactic Center
    Universe (IF 1.752) Pub Date : 2020-10-14
    Rustam Gainutdinov; Yurij Baryshev

    The Galactic Center star cluster, known as S-stars, is a perfect source of relativistic phenomena observations. The stars are located in the strong field of relativistic compact object Sgr A* and are moving with very high velocities at pericenters of their orbits. In this work we consider motion of several S-stars by using the Parameterized Post-Newtonian (PPN) formalism of General Relativity (GR)

  • Matter Accretion Versus Semiclassical Bounce in Schwarzschild Interior
    Universe (IF 1.752) Pub Date : 2020-10-14
    Kirill Bronnikov; Sergey Bolokhov; Milena Skvortsova

    We discuss the properties of the previously constructed model of a Schwarzschild black hole interior where the singularity is replaced by a regular bounce, ultimately leading to a white hole. We assume that the black hole is young enough so that the Hawking radiation may be neglected. The model is semiclassical in nature and uses as a source of gravity the effective stress-energy tensor (SET) corresponding

  • The Functional Schrödinger Equation in the Semiclassical Limit of Quantum Gravity with a Gaussian Clock Field
    Universe (IF 1.752) Pub Date : 2020-10-13
    Marcello Rotondo

    We derive the functional Schrödinger equation for quantum fields in curved spacetime in the semiclassical limit of quantum geometrodynamics with a Gaussian incoherent dust acting as a clock field. We perform the semiclassical limit using a WKB-type expansion of the wave functional in powers of the squared Planck mass. The functional Schrödinger equation that we obtain exhibits a functional time derivative

  • Energy Conservation Law in the Closed Universe and a Concept of the Proper Time
    Universe (IF 1.752) Pub Date : 2020-10-12
    Natalia Gorobey; Alexander Lukyanenko; Pavel Drozdov

    To define time in the homogeneous anisotropic Bianchi-IX model of the universe, we propose a classical equation of motion of the proper time of the universe as an additional gauge condition. This equation is the law of conservation of energy. As a result, a new parameter, called a “mass” of the universe, appears. This parameter is added to the anisotropy energy and regarded as an observed quantity

  • A Test of Gravitational Theories Including Torsion with the BepiColombo Radio Science Experiment
    Universe (IF 1.752) Pub Date : 2020-10-12
    Giulia Schettino; Daniele Serra; Giacomo Tommei; Vincenzo Di Pierri

    Within the framework of the relativity experiment of the ESA/JAXA BepiColombo mission to Mercury, which was launched at the end of 2018, we describe how a test of alternative theories of gravity, including torsion can be set up. Following March et al. (2011), the effects of a non-vanishing spacetime torsion have been parameterized by three torsion parameters, t1, t2, and t3. These parameters can be

  • How Extra Symmetries Affect Solutions in General Relativity
    Universe (IF 1.752) Pub Date : 2020-10-09
    Aroonkumar Beesham; Fisokuhle Makhanya

    To get exact solutions to Einstein’s field equations in general relativity, one has to impose some symmetry requirements. Otherwise, the equations are too difficult to solve. However, sometimes, the imposition of too much extra symmetry can cause the problem to become somewhat trivial. As a typical example to illustrate this, the effects of conharmonic flatness are studied and applied to Friedmann

  • Singularity Theorems in the Effective Field Theory for Quantum Gravity at Second Order in Curvature
    Universe (IF 1.752) Pub Date : 2020-10-10
    Folkert Kuipers; Xavier Calmet

    In this paper, we discuss singularity theorems in quantum gravity using effective field theory methods. To second order in curvature, the effective field theory contains two new degrees of freedom which have important implications for the derivation of these theorems: a massive spin-2 field and a massive spin-0 field. Using an explicit mapping of this theory from the Jordan frame to the Einstein frame

  • Hybrid Metric-Palatini Gravity: Regular Stringlike Configurations
    Universe (IF 1.752) Pub Date : 2020-10-11
    Kirill Bronnikov; Sergey Bolokhov; Milena Skvortsova

    We discuss static, cylindrically symmetric vacuum solutions of hybrid metric-Palatini gravity (HMPG), a recently proposed theory that has been shown to successfully pass the local observational tests and produce a certain progress in cosmology. We use HMPG in its well-known scalar-tensor representation. The latter coincides with general relativity containing, as a source of gravity, a conformally coupled

  • Energy–Momentum Pseudotensor and Superpotential for Generally Covariant Theories of Gravity of General Form
    Universe (IF 1.752) Pub Date : 2020-10-11
    Roman Ilin; Sergey Paston

    The current paper is devoted to the investigation of the general form of the energy–momentum pseudotensor (pEMT) and the corresponding superpotential for the wide class of theories. The only requirement for such a theory is the general covariance of the action without any restrictions on the order of derivatives of the independent variables in it or their transformation laws. As a result of the generalized

  • On the Energy of a Non-Singular Black Hole Solution Satisfying the Weak Energy Condition
    Universe (IF 1.752) Pub Date : 2020-10-07
    Irina Radinschi; Theophanes Grammenos; Farook Rahaman; Marius-Mihai Cazacu; Andromahi Spanou; Joydeep Chakraborty

    The energy-momentum localization for a new four-dimensional and spherically symmetric, charged black hole solution that through a coupling of general relativity with non-linear electrodynamics is everywhere non-singular while it satisfies the weak energy condition, is investigated. The Einstein and Møller energy-momentum complexes have been employed in order to calculate the energy distribution and

  • Using Unreal Engine to Visualize a Cosmological Volume
    Universe (IF 1.752) Pub Date : 2020-10-06
    Christopher Marsden; Francesco Shankar

    In this work we present “Astera’’, a cosmological visualization tool that renders a mock universe in real time using Unreal Engine 4. The large scale structure of the cosmic web is hard to visualize in two dimensions, and a 3D real time projection of this distribution allows for an unprecedented view of the large scale universe, with visually accurate galaxies placed in a dynamic 3D world. The underlying

  • Study on Anisotropic Strange Stars in f(T,T) Gravity
    Universe (IF 1.752) Pub Date : 2020-10-03
    Ines G. Salako; M. Khlopov; Saibal Ray; M.Z. Arouko; Pameli Saha; Ujjal Debnath

    In this work, we study the existence of strange stars in the background of f(T,T) gravity in the Einstein spacetime geometry, where T is the torsion tensor and T is the trace of the energy-momentum tensor. The equations of motion are derived for anisotropic pressure within the spherically symmetric strange star. We explore the physical features like energy conditions, mass-radius relations, modified

  • Resonant Production of an Ultrarelativistic Electron–Positron Pair at the Gamma Quantum Scattering by a Field of the X-ray Pulsar
    Universe (IF 1.752) Pub Date : 2020-10-01
    Vadim A. Yelatontsev; Sergei P. Roshchupkin; Viktor V. Dubov

    The process of a resonant production of an ultrarelativistic electron–positron pair in the process of gamma-quantum scattering in the X-ray field of a pulsar is theoretically studied. This process has two reaction channels. Under resonant conditions, an intermediate electron (for a channel A) or a positron (for a channel B) enters the mass shell. As a result, the initial second-order process of the

  • Soft Anomalous Dimensions and Resummation in QCD
    Universe (IF 1.752) Pub Date : 2020-10-01
    Nikolaos Kidonakis

    I discuss and review soft anomalous dimensions in QCD that describe soft-gluon threshold resummation for a wide range of hard-scattering processes. The factorization properties of the cross section in moment space and renormalization-group evolution are implemented to derive a general form for differential resummed cross sections. Detailed expressions are given for the soft anomalous dimensions at

  • Universal Constants and Natural Systems of Units in a Spacetime of Arbitrary Dimension
    Universe (IF 1.752) Pub Date : 2020-10-01
    Anton Sheykin; Sergey Manida

    We study the properties of fundamental physical constants using the threefold classification of dimensional constants proposed by J.-M. Lévy-Leblond: constants of objects (masses, etc.), constants of phenomena (coupling constants), and “universal constants” (such as c and ℏ). We show that all of the known “natural” systems of units contain at least one non-universal constant. We discuss the possible

  • Non-Relativistic Limit of Embedding Gravity as General Relativity with Dark Matter
    Universe (IF 1.752) Pub Date : 2020-09-29
    Sergey Paston

    Regge-Teitelboim embedding gravity is the modified gravity based on a simple string-inspired geometrical principle – our spacetime is considered here as a 4-dimensional surface in a flat bulk. This theory is similar to the recently popular theory of mimetic gravity – the modification of gravity appears in both theories as a result of the change of variables in the action of General Relativity. Embedding

  • Cosmogenic Activation in Double Beta Decay Experiments
    Universe (IF 1.752) Pub Date : 2020-09-29
    Susana Cebrián

    Double beta decay is a very rare nuclear process and, therefore, experiments intended to detect it must be operated deep underground and in ultra-low background conditions. Long-lived radioisotopes produced by the previous exposure of materials to cosmic rays on the Earth’s surface or even underground can become problematic for the required sensitivity. Here, the studies developed to quantify and reduce

  • Predicting >10 MeV SEP Events from Solar Flare and Radio Burst Data
    Universe (IF 1.752) Pub Date : 2020-09-28
    Marlon Núñez; Daniel Paul-Pena

    The prediction of solar energetic particle (SEP) events or solar radiation storms is one of the most important problems in the space weather field. These events may have adverse effects on technology infrastructures and humans in space; they may also irradiate passengers and flight crews in commercial aircraft flying at polar latitudes. This paper explores the use of ≥ M2 solar flares and radio burst

  • Precise Half-Life Values for Two-Neutrino Double-β Decay: 2020 Review
    Universe (IF 1.752) Pub Date : 2020-09-27
    Alexander Barabash

    All existing positive results on two-neutrino double beta decay and two-neutrino double electron capture in different nuclei have been analyzed. Weighted average and recommended half-life values for 48Ca, 76Ge, 82Se, 96Zr, 100Mo, 100Mo - 100Ru (01+), 116Cd, 128Te, 130Te, 136Xe, 150Nd, 150Nd - 150Sm (01+), 238U, 78Kr, 124Xe and 130Ba have been obtained. Given the measured half-life values, effective

  • Gravity-Induced Geometric Phases and Entanglement in Spinors and Neutrinos: Gravitational Zeeman Effect
    Universe (IF 1.752) Pub Date : 2020-09-27
    Banibrata Mukhopadhyay; Soumya Kanti Ganguly

    We show Zeeman-like splitting in the energy of spinors propagating in a background gravitational field, analogous to the spinors in an electromagnetic field, otherwise termed the Gravitational Zeeman Effect. These spinors are also found to acquire a geometric phase, in a similar way as they do in the presence of magnetic fields. However, in a gravitational background, the Aharonov-Bohm type effect

  • Spectra of a Rydberg Atom in Crossed Electric and Magnetic Fields
    Universe (IF 1.752) Pub Date : 2020-09-24
    Andrei Letunov; Valery Lisitsa

    Contemporary spectroscopic studies of astrophysical and laboratory plasmas frequently deal with extremely large values of principle quantum numbers of atomic systems. These atomic states are very sensitive to electric and magnetic fields of the surrounding medium. While interpreting the spectra of such excited atomic systems, one faces the problem of a huge array of radiative transitions between highly

  • Formation and Clustering of Primordial Black Holes in Brans-Dicke Theory
    Universe (IF 1.752) Pub Date : 2020-09-24
    Victor Berezin; Vyacheslav Dokuchaev; Yury Eroshenko; Alexey Smirnov

    The formation of primordial black holes in the early universe in the Brans-Dicke scalar-tensor theory of gravity is investigated. Corrections to the threshold value of density perturbations are found. Above the threshold, the gravitational collapse occurs after the cosmological horizon crossing. The corrections depend in a certain way on the evolving scalar field. They affect the probability of primordial

  • The Negative Energy in Generalized Vaidya Spacetime
    Universe (IF 1.752) Pub Date : 2020-09-22
    Vitalii Vertogradov

    In this paper we consider the negative energy problem in generalized Vaidya spacetime. We consider several models where we have the naked singularity as a result of the gravitational collapse. In these models we investigate the geodesics for particles with negative energy when the II type of the matter field satisfies the equation of the state P=αρ (α∈[0,1]).

  • Gravity Tests with Radio Pulsars
    Universe (IF 1.752) Pub Date : 2020-09-22
    Norbert Wex; Michael Kramer

    The discovery of the first binary pulsar in 1974 has opened up a completely new field of experimental gravity. In numerous important ways, pulsars have taken precision gravity tests quantitatively and qualitatively beyond the weak-field slow-motion regime of the Solar System. Apart from the first verification of the existence of gravitational waves, binary pulsars for the first time gave us the possibility

  • Visible Shapes of Black Holes M87* and SgrA*
    Universe (IF 1.752) Pub Date : 2020-09-21
    Vyacheslav I. Dokuchaev; Natalia O. Nazarova

    We review the physical origins for possible visible images of the supermassive black hole M87* in the galaxy M87 and SgrA* in the Milky Way Galaxy. The classical dark black hole shadow of the maximal size is visible in the case of luminous background behind the black hole at the distance exceeding the so-called photon spheres. The notably smaller dark shadow (dark silhouette) of the black hole event

  • Evidence for Solar Modulation on the Millennial-Scale Climate Change of Earth
    Universe (IF 1.752) Pub Date : 2020-09-18
    Xinhua Zhao; Willie Soon; Victor M. Velasco Herrera

    In this study, we use available reconstructed data to investigate periodicities of solar activity (i.e., sunspot number) and the Earth’s climate change (temperatures of Lake Qinghai in China and Vostok in Antarctica, the GISP δ18O climate record of Greenland, and the stalagmite δ18O monsoon records of Dongge Cave in China) as well as their cross-wavelet coherences on millennial scale. We find that

  • Spinors in Cylindrically Symmetric Space–Time
    Universe (IF 1.752) Pub Date : 2020-09-15
    Bijan Saha

    We studied the behavior of nonlinear spinor field within the scope of a static cylindrically symmetric space–time. It is found that the energy-momentum tensor (EMT) of the spinor field in this case possesses nontrivial non-diagonal components. The presence of non-diagonal components of the EMT imposes three-way restrictions either on the space–time geometry or on the components of the spinor field

  • Ricci Linear Weyl/Maxwell Mutual Sourcing
    Universe (IF 1.752) Pub Date : 2020-09-14
    Aharon Davidson; Tomer Ygael

    We elevate the field theoretical similarities between Maxwell and Weyl vector fields into a full local scale/gauge invariant Weyl/Maxwell mutual sourcing theory. In its preliminary form, and exclusively in four dimensions, the associated Lagrangian is dynamical scalar field free, hosts no fermion matter fields, and Holdom kinetic mixing is switched off. The mutual sourcing term is then necessarily

  • Constructing Higher-Dimensional Exact Black Holes in Einstein-Maxwell-Scalar Theory
    Universe (IF 1.752) Pub Date : 2020-09-09
    Jianhui Qiu; Changjun Gao

    We construct higher-dimensional and exact black holes in Einstein-Maxwell-scalar theory. The strategy we adopted is to extend the known, static and spherically symmetric black holes in the Einstein-Maxwell dilaton gravity and Einstein-Maxwell-scalar theory. Then we investigate the black hole thermodynamics. Concretely, the generalized Smarr formula and the first law of thermodynamics are derived.

  • Entangling Superconducting Qubits through an Analogue Wormhole
    Universe (IF 1.752) Pub Date : 2020-09-09
    Carlos Sabín

    We propose an experimental setup to test the effect of curved spacetime upon the extraction of entanglement from the quantum field vacuum to a pair of two-level systems. We consider two superconducting qubits coupled to a dc-SQUID array embedded into an open microwave transmission line, where an external bias can emulate a spacetime containing a traversable wormhole. We find that the amount of vacuum

  • Casimir and Casimir-Polder Forces in Graphene Systems: Quantum Field Theoretical Description and Thermodynamics
    Universe (IF 1.752) Pub Date : 2020-09-09
    Galina L. Klimchitskaya; Vladimir M. Mostepanenko

    We review recent results on the low-temperature behaviors of the Casimir-Polder and Casimir free energy an entropy for a polarizable atom interacting with a graphene sheet and for two graphene sheets, respectively. These results are discussed in the wide context of problems arising in the Lifshitz theory of van der Waals and Casimir forces when it is applied to metallic and dielectric bodies. After

  • The State of the Art in Constraining Axion-to-Nucleon Coupling and Non-Newtonian Gravity from Laboratory Experiments
    Universe (IF 1.752) Pub Date : 2020-09-08
    Vladimir M. Mostepanenko; Galina L. Klimchitskaya

    Constraints on the Yukawa-type corrections to Newton’s gravitational law and on the coupling constant of axionlike particles to nucleons obtained from different laboratory experiments are reviewed and compared. The constraints on non-Newtonian gravity under discussion cover the wide interaction range from nanometers to millimeters and follow from the experiments on neutron scattering, measuring the

  • Investigation of the Elliptic Flow Fluctuations of the Identified Particles Using the a Multi-Phase Transport Model
    Universe (IF 1.752) Pub Date : 2020-09-06
    Niseem Magdy; Xu Sun; Zhenyu Ye; Olga Evdokimov; Roy Lacey

    A Multi-Phase Transport (AMPT) model is used to study the elliptic flow fluctuations of identified particles using participant and spectator event planes. The elliptic flow measured using the first order spectator event plane is expected to give the elliptic flow relative to the true reaction plane which suppresses the flow fluctuations. However, the elliptic flow measured using the second-order participant

  • Effects of Turbulent Environment on Self-Organized Critical Behavior: Isotropy vs. Anisotropy
    Universe (IF 1.752) Pub Date : 2020-09-06
    Nikolay V. Antonov; Nikolay M. Gulitskiy; Polina I. Kakin; German E. Kochnev

    We study a self-organized critical system under the influence of turbulent motion of the environment. The system is described by the anisotropic continuous stochastic equation proposed by Hwa and Kardar [Phys. Rev. Lett.62: 1813 (1989)]. The motion of the environment is modelled by the isotropic Kazantsev–Kraichnan “rapid-change” ensemble for an incompressible fluid: it is Gaussian with vanishing correlation

  • Conformal Symmetry and Supersymmetry in Rindler Space
    Universe (IF 1.752) Pub Date : 2020-09-04
    J. W. van Holten

    This paper addresses the fate of extended space-time symmetries, in particular conformal symmetry and supersymmetry, in two-dimensional Rindler space-time appropriate to a uniformly accelerated non-inertial frame in flat 1+1-dimensional space-time. Generically, in addition to a conformal co-ordinate transformation, the transformation of fields from Minkowski to Rindler space is accompanied by local

  • The Resonant Bremsstrahlung of Ultrarelativistic Electrons on a Nucleus with Radiation of Hard Gamma-Quanta in the Presence of a Pulsed Field of the X-ray Pulsar
    Universe (IF 1.752) Pub Date : 2020-09-03
    Alexander Dubov; Victor V. Dubov; Sergei P. Roshchupkin

    The investigation scrutinizes the circulation of the large-scaled fluxes of ultrarelativistic electrons near the neutron stars. This work focuses on the effects that occur during the adjustment of the strong electromagnetic field near the X-ray pulsars. Particularly, this study analyzes the resonant high-energy spontaneous bremsstrahlung of ultrarelativistic electrons in the pulsed fields of a nucleus

  • GW Interferometer Euro-Asian Network: Detection Characteristics for Signals of Known Shape
    Universe (IF 1.752) Pub Date : 2020-09-02
    Valentin Rudenko; Svetlana Andrusenko; Daniil Krichevskiy; Gevorg Manucharyan

    In this paper, we estimate efficiency of a conceivable Euro-Asian network of gravitational wave (GW) interferometers that might be realized having in mind a plan of construction of third generation interferometer in Novosibirsk region. Subsequently, some network would be composed, including four GW detectors. Among them there are the already active interferometers VIRGO (Italy) and KAGRA (Japan), Indian

  • Resonant Effects in a Photoproduction of Ultrarelativistic Electron-Positron Pairs on a Nucleus in the Field of the X-ray Pulsar
    Universe (IF 1.752) Pub Date : 2020-09-02
    Nikita R. Larin; Sergei P. Roshchupkin; Victor V. Dubov

    The resonant photoproduction of the electron-positron pairs on a nucleus near a surface of the X-ray pulsar was studied theoretically. The main feature of the processes, which are responsible for the formation of the electron-positron fluxes, is a capability to occur in a resonant way in the electromagnetic field of the X-ray pulsar. One of the properties of the resonant case is that the initial process

  • Gravitational Interaction in a Null String Gas and Its Possible Consequences
    Universe (IF 1.752) Pub Date : 2020-09-02
    Alexander Lelyakov

    In this paper, we investigated the possible consequences of gravitational interaction in a gas of null strings. The structural elements of this gas are closed null strings in the form of a circle (thin closed tubes of massless scalar field). A possibility to qualitatively take into account the mutual influence on motion for gravitationally interacting null strings is proposed. It is shown that the

  • A 1% Measurement of the Gravitomagnetic Field of the Earth with Laser-Tracked Satellites
    Universe (IF 1.752) Pub Date : 2020-08-31
    David Lucchesi; Massimo Visco; Roberto Peron; Massimo Bassan; Giuseppe Pucacco; Carmen Pardini; Luciano Anselmo; Carmelo Magnafico

    A new measurement of the gravitomagnetic field of the Earth is presented. The measurement has been obtained through the careful evaluation of the Lense-Thirring (LT) precession on the combined orbits of three passive geodetic satellites, LAGEOS, LAGEOS II, and LARES, tracked by the Satellite Laser Ranging (SLR) technique. This general relativity precession, also known as frame-dragging, is a manifestation

  • The Resonant Effect of an Annihilation Channel in the Interaction of the Ultrarelativistic Electron and Positron in the Field of an X-ray Pulsar
    Universe (IF 1.752) Pub Date : 2020-08-28
    Dmitriy V. Doroshenko; Sergei P. Roshchupkin; Victor V. Dubov

    We investigated the effects that occur during the circulation of ultrarelativistic electrons and positrons in the field of an X-ray pulsar. A resonant process in annihilation and the subsequent production of the electron–positron pairs were studied theoretically. Under the resonance, the second-order process in an original fine-structure constant process effectively decays to two first order processes

  • Dark Gravitational Field on Riemannian and Sasaki Spacetime
    Universe (IF 1.752) Pub Date : 2020-08-28
    Panayiotis Stavrinos; Christos Savvopoulos

    The aim of this paper is to provide the geometrical structure of a gravitational field that includes the addition of dark matter in the framework of a Riemannian and a Riemann–Sasaki spacetime. By means of the classical Riemannian geometric methods we arrive at modified geodesic equations, tidal forces, and Einstein and Raychaudhuri equations to account for extra dark gravity. We further examine an

  • Jetted Narrow-Line Seyfert 1 Galaxies & Co.: Where Do We Stand?
    Universe (IF 1.752) Pub Date : 2020-08-26
    Luigi Foschini

    The discovery in 2008 of high-energy gamma-rays from Narrow-Line Seyfert 1 Galaxies (NLS1s) made it clear that there were active galactic nuclei (AGN) other than blazars and radio galaxies that can eject powerful relativistic jets. In addition to NLS1s, the great performance of the Fermi Large Area Telescope made it possible to discover MeV-GeV photons emitted from more classes of AGN, like Seyferts

  • Neutrinos: Majorana or Dirac?
    Universe (IF 1.752) Pub Date : 2020-08-24
    Samoil M. Bilenky

    Are neutrinos with definite masses Majorana or Dirac particles? This is one of the most fundamental problems of modern neutrino physics. The solution to this problem could be crucial for understanding the origin of small neutrino masses. We review here basic arguments in favor of the Majorana nature of massive neutrinos. The phenomenological theory of 0νββ-decay is briefly discussed and recent experimental

  • An SU(2) Gauge Principle for the Cosmic Microwave Background: Perspectives on the Dark Sector of the Cosmological Model
    Universe (IF 1.752) Pub Date : 2020-08-24
    Ralf Hofmann

    We review consequences for the radiation and dark sectors of the cosmological model arising from the postulate that the Cosmic Microwave Background (CMB) is governed by an SU(2) rather than a U(1) gauge principle. We also speculate on the possibility of actively assisted structure formation due to the de-percolation of lump-like configurations of condensed ultralight axions with a Peccei–Quinn scale

  • Varying Newton Constant and Black Hole to White Hole Quantum Tunneling
    Universe (IF 1.752) Pub Date : 2020-08-23
    Grigory Volovik

    The thermodynamics of black holes is discussed for the case, when the Newton constant G is not a constant, but it is the thermodynamic variable. This gives for the first law of the Schwarzschild black hole thermodynamics: dSBH=−AdK+dMTBH, where the gravitational coupling K=1/4G, M is the black hole mass, A is the area of horizon, and TBH is Hawking temperature. From this first law, it follows that

  • Resonant Ultrarelativistic Electron–Positron Pair Production by High-Energy Electrons in the Field of an X-ray Pulsar
    Universe (IF 1.752) Pub Date : 2020-08-22
    Georgii K. Sizykh; Sergei P. Roshchupkin; Victor V. Dubov

    The process of resonant high-energy electron–positron pair production by an ultrarelativistic electron colliding with the field of an X-ray pulsar is theoretically investigated. Resonant kinematics of the process is studied in detail. Under the resonance condition, the intermediate virtual photon in the X-ray pulsar field becomes a real particle. As a result, the initial process of the second order

  • The Astrobiology of Alien Worlds: Known and Unknown Forms of Life
    Universe (IF 1.752) Pub Date : 2020-08-20
    Louis N. Irwin; Dirk Schulze-Makuch

    Most definitions of life assume that, at a minimum, life is a physical form of matter distinct from its environment at a lower state of entropy than its surroundings, using energy from the environment for internal maintenance and activity, and capable of autonomous reproduction. These assumptions cover all of life as we know it, though more exotic entities can be envisioned, including organic forms

  • Radiation from an Inertial Mirror Horizon
    Universe (IF 1.752) Pub Date : 2020-08-20
    Michael Good; Ernazar Abdikamalov

    The purpose of this study is to investigate radiation from asymptotic zero acceleration motion where a horizon is formed and subsequently detected by an outside witness. A perfectly reflecting moving mirror is used to model such a system and compute the energy and spectrum. The trajectory is asymptotically inertial (zero proper acceleration)—ensuring negative energy flux (NEF), yet approaches light-speed

  • Is the Copenhagen Interpretation Inapplicable to Quantum Cosmology?
    Universe (IF 1.752) Pub Date : 2020-08-19
    Tatyana P. Shestakova

    It is generally accepted that the Copenhagen interpretation is inapplicable to quantum cosmology, by contrast with the many worlds interpretation. I shall demonstrate that the two basic principles of the Copenhagen interpretation, the principle of wholeness and the principle of complementarity, do make sense in quantum gravity, since we can judge about quantum gravitational processes in the very early

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