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  • Dark Side of Weyl Gravity
    Universe (IF 1.752) Pub Date : 2020-08-12
    Petr Jizba; Lesław Rachwał; Stefano G. Giaccari; Jaroslav Kňap

    We address the issue of a dynamical breakdown of scale invariance in quantum Weyl gravity together with related cosmological implications. In the first part, we build on our previous work [Phys. Rev. D2020, 101, 044050], where we found a non-trivial renormalization group fixed point in the infrared sector of quantum Weyl gravity. Here, we prove that the ensuing non-Gaussian IR fixed point is renormalization

  • Possible Wormhole Candidates in Active Galactic Nuclei
    Universe (IF 1.752) Pub Date : 2020-08-11
    Mikhail Piotrovich; Serguei Krasnikov; Stanislava Buliga; Tinatin Natsvlishvili

    The hypothesis is considered that the active galactic nuclei (AGNs) are wormhole (WH) mouths rather than supermassive black holes (SMBHs). We study the difference in the physical properties of such objects from those of AGNs with SMBH, as well as the the corresponding difference in observational data. Firstly, the radiative efficiency for some types of WHs (both static and rotating) can be significantly

  • CPTM Discrete Symmetry, Quantum Wormholes and Cosmological Constant Problem
    Universe (IF 1.752) Pub Date : 2020-08-11
    Sergey Bondarenko

    We discuss the consequences of the charge, parity, time, and mass (CPTM) extended reversal symmetry for the problems of the vacuum energy density and value of the cosmological constant. The results obtained are based on the framework with the separation of extended space-time of the interest on the different regions connected by this symmetry with the action of the theory valid for the full space-time

  • Ionospheric Behavior of foF2 over Chinese EIA Region and Its Comparison with IRI-2016
    Universe (IF 1.752) Pub Date : 2020-08-11
    Peng Zhu; Cong Xie; Chunhua Jiang; Guobin Yang; Jing Liu; Zhengqiang Li; Zhengyu Zhao

    The ionograms, which were recorded by the ionosonde located at Pu’er station (PUR, 22.7°N, 101.05°E, Dip Latitude 12.9°N) in the Southwest of China in the year of 2016, were used to study the ionospheric behavior of the ordinary critical frequency of the F2 layer (foF2) in the region of the northern equatorial ionization anomaly. To verify the performance of the International Reference Ionosphere (IRI)

  • Statistical Analysis of Field-Aligned Alfvénic Turbulence and Intermittency in Fast Solar Wind
    Universe (IF 1.752) Pub Date : 2020-08-09
    Francesco Carbone; Daniele Telloni; Luca Sorriso-Valvo; Gary Zank; Lingling Zhao; Laxman Adhikari; Roberto Bruno

    The statistical properties of fast Alfvénic solar wind turbulence have been analyzed by means of empirical mode decomposition and the associated Hilbert spectral analysis. The stringent criteria employed for the data selection in the Wind spacecraft database, has made possible to sample multiple k‖ field-aligned intervals of the three magnetic field components. The results suggest that the spectral

  • Intensity and Polarization of Radiation Emerging from Rotating Accretion Disc with Increasing Height
    Universe (IF 1.752) Pub Date : 2020-08-10
    Nikolai Silant’ev; Galina Alekseeva; Yulia Ananjevskaja; Viktor Novikov

    We consider the radiation emission in continuum and spectral lines from rotating accretion disc with the progressive increasing height. It is known that for the plane accretion disc with homogeneous atmosphere the wave electric field E is perpendicular to the plane between line of sight n and the normal to the disc N. For the expanding accretion disc the wave electric field from every inclined cone-like

  • Paradigms and Scenarios for the Dark Matter Phenomenon
    Universe (IF 1.752) Pub Date : 2020-08-10
    Paolo Salucci; Nicola Turini; Chiara di Paolo

    Well known scaling laws among the structural properties of the dark and the luminous matter in disc systems are too complex to be arisen by two inert components that just share the same gravitational field. This brings us to critically focus on the 30-year-old paradigm, that, resting on a priori knowledge of the nature of Dark Matter (DM), has led us to a restricted number of scenarios, especially

  • The Equation of State of Nuclear Matter: From Finite Nuclei to Neutron Stars
    Universe (IF 1.752) Pub Date : 2020-08-10
    G. Fiorella Burgio; Isaac Vidaña

    Background. We investigate possible correlations between neutron star observables and properties of atomic nuclei. In particular, we explore how the tidal deformability of a 1.4 solar mass neutron star, M1.4, and the neutron-skin thickness of 48Ca and 208Pb are related to the stellar radius and the stiffness of the symmetry energy. Methods. We examine a large set of nuclear equations of state based

  • Riddle of a Black Hole: Guessing the Riddle of a Black Hole
    Universe (IF 1.752) Pub Date : 2020-08-07
    Boris E. Meierovich

    A static structure of matter, extremely compressed to the state of a Bose–Einstein condensate by its own gravitational field, is considered. Instead of the widely spread restriction detgik<0, I used a weaker condition of regularity: all invariants of gik are finite. This makes it possible to find regular static solutions to Einstein equations for a spherically symmetric distribution of matter with

  • A Chi-Squared Analysis of the Measurements of Two Cosmological Parameters over Time
    Universe (IF 1.752) Pub Date : 2020-08-07
    Timothy Faerber; Martín López-Corredoira

    The aim of this analysis was to determine whether or not the given error bars truly represented the dispersion of values in a historical compilation of two cosmological parameters: the amplitude of mass fluctuations (σ8) and Hubble’s constant (H0) parameters in the standard cosmological model. For this analysis, a chi-squared test was executed on a compiled list of past measurements. It was found through

  • Nuclear Pairing Gaps and Neutron Star Cooling
    Universe (IF 1.752) Pub Date : 2020-08-08
    Jin-Biao Wei; Fiorella Burgio; Hans-Josef Schulze

    We study the cooling of isolated neutron stars with particular regard to the importance of nuclear pairing gaps. A microscopic nuclear equation of state derived in the Brueckner-Hartree-Fock approach is used together with compatible neutron and proton pairing gaps. We then study the effect of modifying the gaps on the final deduced neutron star mass distributions. We find that a consistent description

  • On the Role of Einstein–Cartan Gravity in Fundamental Particle Physics
    Universe (IF 1.752) Pub Date : 2020-08-05
    Carl F. Diether III; Joy Christian

    Two of the major open questions in particle physics are: (1) Why do the elementary fermionic particles that are so far observed have such low mass-energy compared to the Planck energy scale? (2) What mechanical energy may be counterbalancing the divergent electrostatic and strong force energies of point-like charged fermions in the vicinity of the Planck scale? In this paper, using a hitherto unrecognised

  • Approximate Analytical Periodic Solutions to the Restricted Three-Body Problem with Perturbation, Oblateness, Radiation and Varying Mass
    Universe (IF 1.752) Pub Date : 2020-08-04
    Fabao Gao; Yongqing Wang

    Against the background of a restricted three-body problem consisting of a supergiant eclipsing binary system, the two primaries are composed of a pair of bright oblate stars whose mass changes with time. The zero-velocity surface and curve of the problem are numerically studied to describe the third body’s motion area, and the corresponding five libration points are obtained. Moreover, the effect of

  • Dirac, Majorana, Weyl in 4D
    Universe (IF 1.752) Pub Date : 2020-08-04
    Loriano Bonora; Roberto Soldati; Stav Zalel

    This is a review of some elementary properties of Dirac, Weyl and Majorana spinors in 4D. We focus in particular on the differences between massless Dirac and Majorana fermions, on one side, and Weyl fermions, on the other. We review in detail the definition of their effective actions, when coupled to (vector and axial) gauge fields, and revisit the corresponding anomalies using the Feynman diagram

  • A Bayesian Approach to the Simulation Argument
    Universe (IF 1.752) Pub Date : 2020-08-03
    David Kipping

    The Simulation Argument posed by Bostrom suggests that we may be living inside a sophisticated computer simulation. If posthuman civilizations eventually have both the capability and desire to generate such Bostrom-like simulations, then the number of simulated realities would greatly exceed the one base reality, ostensibly indicating a high probability that we do not live in said base reality. In

  • Revisiting the Cosmological Constant Problem within Quantum Cosmology
    Universe (IF 1.752) Pub Date : 2020-08-02
    Vesselin G. Gueorguiev; Andre Maeder

    A new perspective on the Cosmological Constant Problem (CCP) is proposed and discussed within the multiverse approach of Quantum Cosmology. It is assumed that each member of the ensemble of universes has a characteristic scale a that can be used as integration variable in the partition function. An averaged characteristic scale of the ensemble is estimated by using only members that satisfy the Einstein

  • Dark Matters on the Scale of Galaxies
    Universe (IF 1.752) Pub Date : 2020-08-01
    Ivan de Martino; Sankha S. Chakrabarty; Valentina Cesare; Arianna Gallo; Luisa Ostorero; Antonaldo Diaferio

    The cold dark-matter model successfully explains both the emergence and evolution of cosmic structures on large scales and, when we include a cosmological constant, the properties of the homogeneous and isotropic Universe. However, the cold dark-matter model faces persistent challenges on the scales of galaxies. Indeed, N-body simulations predict some galaxy properties that are at odds with the observations

  • Formation Dynamics of Black- and White-Hole Horizons in an Analogue Gravity Model
    Universe (IF 1.752) Pub Date : 2020-07-31
    Manuele Tettamanti; Alberto Parola

    We investigate the formation dynamics of sonic horizons in a Bose gas confined in a (quasi) one-dimensional trap. This system is one of the most promising realizations of the analogue gravity paradigm and has already been successfully studied experimentally. Taking advantage of the exact solution of the one-dimensional, hard-core, Bose model (Tonks–Girardeau gas), we show that by switching on a step

  • Caustics in Gravitational Lensing by Mixed Binary Systems
    Universe (IF 1.752) Pub Date : 2020-07-31
    Valerio Bozza; Silvia Pietroni; Chiara Melchiorre

    We investigated binary lenses with 1/rn potentials in the asymmetric case with two lenses with different indexes n and m. These kinds of potentials have been widely used in several contexts, ranging from galaxies with halos described by different power laws to lensing by wormholes or exotic matter. In this paper, we present a complete atlas of critical curves and caustics for mixed binaries, starting

  • Critical Tidal Currents in General Relativity
    Universe (IF 1.752) Pub Date : 2020-07-30
    Bahram Mashhoon

    Relativistic tidal equations are formulated with respect to the rest frame of a central gravitational source and their solutions are studied. The existence of certain relativistic critical tidal currents are thereby elucidated. Specifically, observers that are spatially at rest in the exterior Kerr spacetime are considered in detail; in effect, these fiducial observers define the rest frame of the

  • Spinning Test Particle in Four-Dimensional Einstein–Gauss–Bonnet Black Holes
    Universe (IF 1.752) Pub Date : 2020-07-28
    Yu-Peng Zhang; Shao-Wen Wei; Yu-Xiao Liu

    In this paper, we investigate the motion of a classical spinning test particle in a background of a spherically symmetric black hole based on the novel four-dimensional Einstein–Gauss–Bonnet gravity [D. Glavan and C. Lin, Phys. Rev. Lett. 124, 081301 (2020)]. We find that the effective potential of a spinning test particle in this background could have two minima when the Gauss–Bonnet coupling parameter

  • The Fundamental Roles of the de Sitter Vacuum
    Universe (IF 1.752) Pub Date : 2020-07-24
    Irina Dymnikova

    We overview the fundamental roles of the de Sitter vacuum in cosmology where it is responsible for powering the early inflationary stage(s) and the present accelerated expansion, in black hole physics where it provides the existence of a wide class of regular black holes and self-gravitating solitons replacing naked singularities, and in particle physics where it ensures the intrinsic relation of the

  • Cosmic-Ray Database Update: Ultra-High Energy, Ultra-Heavy, and Antinuclei Cosmic-Ray Data (CRDB v4.0)
    Universe (IF 1.752) Pub Date : 2020-07-24
    David Maurin; Hans Peter Dembinski; Javier Gonzalez; Ioana Codrina Mariş; Frédéric Melot

    We present an update on CRDB, the cosmic-ray database for charged species. CRDB is based on MySQL, queried and sorted by jquery and table-sorter libraries, and displayed via PHP web pages through the AJAX protocol. We review the modifications made on the structure and outputs of the database since the first release (Maurin et al., 2014). For this update, the most important feature is the inclusion

  • Holographic Interpretation of Relative State Complexity
    Universe (IF 1.752) Pub Date : 2020-07-22
    Alexander Yosifov; Aditya Iyer; Lachezar Filipov

    We investigate a large-N conformal field theory (CFT) in a high-energy pure state coupled to a small auxiliary system of M weakly-interacting degrees of freedom, and argue the relative state complexity of the auxiliary system is holographically dual to an effective low-energy notion of computational cost in the bulk, i.e., to the minimal depth of the quantum circuit required to decode its gravitational

  • The Origin of Matter at the Base of Relativistic Jets in Active Galactic Nuclei
    Universe (IF 1.752) Pub Date : 2020-07-18
    Gustavo E. Romero; Eduardo Gutiérrez

    The generation of relativistic jets in active sources such as blazars is a complex problem with many aspects, most of them still not fully understood. Relativistic jets are likely produced by the accretion of matter and magnetic fields onto spinning black holes. Ergospheric dragging effects launch a Poynting-dominated outflow in the polar directions of these systems. Observations with very high resolution

  • A Plausible Model of Inflation Driven by Strong Gravitational Wave Turbulence
    Universe (IF 1.752) Pub Date : 2020-07-16
    Sébastien Galtier; Jason Laurie; Sergey V. Nazarenko

    It is widely accepted that the primordial universe experienced a brief period of accelerated expansion called inflation. This scenario provides a plausible solution to the horizon and flatness problems. However, the particle physics mechanism responsible for inflation remains speculative with, in particular, the assumption of a scalar field called inflaton. Furthermore, the comparison with the most

  • Tensor Network Renormalization with Fusion Charges—Applications to 3D Lattice Gauge Theory
    Universe (IF 1.752) Pub Date : 2020-07-12
    William J. Cunningham; Bianca Dittrich; Sebastian Steinhaus

    Tensor network methods are powerful and efficient tools for studying the properties and dynamics of statistical and quantum systems, in particular in one and two dimensions. In recent years, these methods have been applied to lattice gauge theories, yet these theories remain a challenge in ( 2 + 1 ) dimensions. In this article, we present a new (decorated) tensor network algorithm, in which the tensors

  • Excess of Soft Dielectrons and Photons
    Universe (IF 1.752) Pub Date : 2020-07-10
    I. M. Dremin

    Spectra of unbound electron–positron pairs (dielectrons, in brief) and photons from decays of parapositronia produced in ultraperipheral collisions of electrically charged objects are calculated. Their shapes at energies of the NICA collider are demonstrated. Soft dielectrons and photons are abundantly produced. The relevance of these processes to the astrophysical problem of cooling electron–positron

  • Spontaneous Color Polarization as A Modus Originis of the Dynamic Aether
    Universe (IF 1.752) Pub Date : 2020-07-10
    Alexander Balakin; Gleb Kiselev

    We suggest the phenomenological model of emergence of the dynamic aether as a result of decay of the SU(N) symmetric field configuration containing the multiplet of vector fields. The scenario of the transition to the dynamic aether, which is characterized by one unit timelike vector field that is associated with the aether velocity, is based on the idea of spontaneous color polarization analogous

  • Genuine Dilatons in Gauge Theories
    Universe (IF 1.752) Pub Date : 2020-07-10
    R. J. Crewther

    A genuine dilaton σ allows scales to exist even in the limit of exact conformal invariance. In gauge theories, these may occur at an infrared fixed point (IRFP) α IR through dimensional transmutation. These large scales at α IR can be separated from small scales produced by θ μ μ , the trace of the energy-momentum tensor. For quantum chromodynamics (QCD), the conformal limit can be combined with chiral

  • Two-Dimensional Correlation Function of Binary Black Hole Coalescences
    Universe (IF 1.752) Pub Date : 2020-07-07
    Marco Cavaglià; Ashini Modi

    We compute the two-dimensional correlation functions of the binary black hole coalescence detections in LIGO-Virgo’s first and second observation runs. The sky distribution of binary black hole coalescence events is tested for correlations at different angular scales by comparing the observed correlation function to two reference functions that are obtained from mock datasets of localization error

  • Gravitational Fluctuations as an Alternative to Inflation III. Numerical Results
    Universe (IF 1.752) Pub Date : 2020-07-04
    Herbert W. Hamber; Lu Heng Sunny Yu; Hasitha E. Pituwala Kankanamge

    Power spectra play an important role in the theory of inflation, and their ability to reproduce current observational data to high accuracy is often considered a triumph of inflation, largely because of a lack of credible alternatives. In previous work we introduced an alternative picture for the cosmological power spectra based on the nonperturbative features of the quantum version of Einstein’s gravity

  • Langer Modification, Quantization Condition and Barrier Penetration in Quantum Mechanics
    Universe (IF 1.752) Pub Date : 2020-06-30
    Bao-Fei Li; Tao Zhu; Anzhong Wang

    The WKB approximation plays an essential role in the development of quantum mechanics and various important results have been obtained from it. In this paper, we introduce another method, the so-called uniform asymptotic approximations, which is an analytical approximation method to calculate the wave functions of the Schrödinger-like equations, and it is applicable to various problems, including cases

  • Correlation Functions of Quantum Artin System
    Universe (IF 1.752) Pub Date : 2020-06-30
    Hrachya Babujian; Rubik Poghossian; George Savvidy

    It was conjectured by Maldacena, Shenker and Stanford that the classical chaos can be diagnosed in thermal quantum systems by using an out-of-time-order correlation function. The Artin dynamical system defined on the fundamental region of the modular group SL(2,Z) represents a well defined example of a highly chaotic dynamical system in its classical regime. We investigated the influence of the classical

  • Parton Distribution Functions and Tensorgluons
    Universe (IF 1.752) Pub Date : 2020-06-29
    Roland Kirschner; George Savvidy

    We derive the regularised evolution equations for the parton distribution functions that include tensorgluons.

  • Gravitational Waves in Axion Dark Matter
    Universe (IF 1.752) Pub Date : 2020-06-29
    Chong-Sun Chu; Jiro Soda; Daiske Yoshida

    Axion dark matter is interesting as it allows a natural coupling to the gravitational Chern–Simons term. In the presence of an axion background, the gravitational Chern–Simons term produces parity violating effects in the gravitational sector, in particular on the propagation of gravitational waves. Previously, it has been shown that the coherent oscillation of the axion field leads to a parametric

  • Identifying the Λb(6146)0 and Λb(6152)0 as D-Wave Bottom Baryons
    Universe (IF 1.752) Pub Date : 2020-06-23
    Qiang Mao; Hua-Xing Chen; Hui-Min Yang

    We study the Λ b ( 6146 ) 0 and Λ b ( 6152 ) 0 recently observed by LHCb using the method of Quantum Chromodynamics (QCD) sum rules within the framework of heavy quark effective theory. Our results suggest that they can be interpreted as D-wave bottom baryons of J P = 3 / 2 + and 5 / 2 + respectively, both of which contain two λ -mode excitations. We also investigate other possible assignments containing

  • The Spectrum of Gravitational Waves, Their Overproduction in Quintessential Inflation and Its Influence in the Reheating Temperature
    Universe (IF 1.752) Pub Date : 2020-06-23
    Jaume Haro Cases; Llibert Aresté Saló

    One of the most important issues in an inflationary theory as standard or quintessential inflation is the mechanism to reheat the universe after the end of the inflationary period in order to match with the Hot Big Bang universe. In quintessential inflation two mechanisms are frequently used, namely the reheating via gravitational particle production which is, as we will see, very efficient when the

  • Is There Still Something Left That Gravity Probe B Can Measure?
    Universe (IF 1.752) Pub Date : 2020-06-20
    Lorenzo Iorio

    We perform a full analytical and numerical treatment, to the first post-Newtonian (1pN) order, of the general relativistic long-term spin precession of an orbiting gyroscope due to the mass quadrupole moment J 2 of its primary without any restriction on either the gyro’s orbital configuration and the orientation in space of the symmetry axis k ^ of the central body. We apply our results to the past

  • Hyperfine Splitting of Excited States of New Heavy Hadrons and Low-Energy Interaction of Hadronic Dark Matter with Photons, Nucleons, and Leptons
    Universe (IF 1.752) Pub Date : 2020-06-19
    Vladimir Kuksa; Vitaly Beylin

    We consider the structure of excited states and low-energy interaction of hadronic dark matter with photons, leptons, and nucleons. Description of the lowest excited levels is fulfilled in an analogy with the standard heavy-light mesons. Using the effective vertex of new heavy hadrons interaction with W-boson, we calculate cross-section of the lepton scattering on the dark matter particle. Analysis

  • Comments on P. Jordan’s Cosmological Model
    Universe (IF 1.752) Pub Date : 2020-06-17
    Eve-Aline Dubois; André Füzfa

    We analyse the original cosmology of P. Jordan through his 1939 key paper entitled “Bemerkungen zur Kosmologie" or “Comments on cosmology". In this almost forgotten work, the author introduced a model of dynamical cosmology with spontaneous creation of matter, based on the Large Numbers study, initiated by Eddington and further developed by Dirac. Jordan’s will to explore heuristically all possible

  • General Relativistic Mean-Field Dynamo Model for Proto-Neutron Stars
    Universe (IF 1.752) Pub Date : 2020-06-17
    Kevin Franceschetti; Luca Del Zanna

    Neutron stars, and magnetars in particular, are known to host the strongest magnetic fields in the Universe. The origin of these strong fields is a matter of controversy. In this preliminary work, via numerical simulations, we study, for the first time in non-ideal general relativistic magnetohydrodynamic (GRMHD) regime, the growth of the magnetic field due to the action of the mean-field dynamo due

  • Was GW170817 a Canonical Neutron Star Merger? Bayesian Analysis with a Third Family of Compact Stars
    Universe (IF 1.752) Pub Date : 2020-06-10
    David Blaschke; Alexander Ayriyan; David Edwin Alvarez-Castillo; Hovik Grigorian

    We investigate the possibility that GW170817 was not the merger of two conventional neutron stars (NS), but involved at least one if not two hybrid stars with a quark matter core that might even belong to a third family of compact stars. To this end, we develop a Bayesian analysis method for selecting the most probable equation of state (EoS) under a set of constraints from compact star physics, which

  • Unified Description of Dark Energy and Dark Matter within the Generalized Hybrid Metric-Palatini Theory of Gravity
    Universe (IF 1.752) Pub Date : 2020-06-05
    Paulo M. Sá

    The generalized hybrid metric-Palatini theory of gravity admits a scalar-tensor representation in terms of two interacting scalar fields. We show that, upon an appropriate choice of the interaction potential, one of the scalar fields behaves like dark energy, inducing a late-time accelerated expansion of the universe, while the other scalar field behaves like pressureless dark matter that, together

  • Cosmological Spectrum of Two-Point Correlation Function from Vacuum Fluctuation of Stringy Axion Field in De Sitter Space: A Study of the Role of Quantum Entanglement
    Universe (IF 1.752) Pub Date : 2020-06-05
    Sayantan Choudhury; Sudhakar Panda

    In this work, we study the impact of quantum entanglement on the two-point correlation function and the associated primordial power spectrum of mean square vacuum fluctuation in a bipartite quantum field theoretic system. The field theory that we consider is the effective theory of axion field arising from Type IIB string theory compacted to four dimensions. We compute the expression for the power

  • Observation of Atmospheric Neutrinos
    Universe (IF 1.752) Pub Date : 2020-06-05
    Yusuke Koshio

    In 1998, the Super-Kamiokande discovered neutrino oscillation using atmospheric neutrino anomalies. It was the first direct evidence of neutrino mass and the first phenomenon to be discovered beyond the standard model of particle physics. Recently, more precise measurements of neutrino oscillation parameters using atmospheric neutrinos have been achieved by several detectors, such as Super-Kamiokande

  • Symmetries, a Systematic Construction of Invariant Fields and AdS Backgrounds
    Universe (IF 1.752) Pub Date : 2020-06-04
    George Papadopoulos

    We give a systematic local description of invariant metrics and other invariant fields on a spacetime under the action of a (non-abelian) group. This includes the invariant fields in a neighbourhood of a principal and a special orbit. The construction is illustrated with examples. We also apply the formalism to give the R-symmetry invariant metrics of some AdS backgrounds and comment on applications

  • Black Hole as a Quantum Field Configuration
    Universe (IF 1.752) Pub Date : 2020-06-04
    Hikaru Kawai; Yuki Yokokura

    We describe 4D evaporating black holes as quantum field configurations by solving the semi-classical Einstein equation G μ ν = 8 π G 〈 ψ | T μ ν | ψ 〉 and quantum matter fields in a self-consistent manner. As the matter fields, we consider N massless free scalar fields (N is large). We find a spherically symmetric self-consistent solution of the metric g μ ν and the state | ψ 〉 . Here, g μ ν is locally

  • Invisible QCD as Dark Energy
    Universe (IF 1.752) Pub Date : 2020-05-31
    Andrea Addazi; Stephon Alexander; Antonino Marcianò

    We account for the late time acceleration of the Universe by extending the Quantum Chromodynamics (QCD) color to a S U ( 3 ) invisible sector (IQCD). If the Invisible Chiral symmetry is broken in the early universe, a condensate of dark pions (dpions) and dark gluons (dgluons) forms. The condensate naturally forms due to strong dynamics similar to the Nambu–Jona-Lasinio mechanism. As the Universe evolves

  • Semi-Classical Einstein Equations: Descend to the Ground State
    Universe (IF 1.752) Pub Date : 2020-05-29
    Zbigniew Haba

    The time-dependent cosmological term arises from the energy-momentum tensor calculated in a state different from the ground state. We discuss the expectation value of the energy-momentum tensor on the right hand side of Einstein equations in various (approximate) quantum pure as well as mixed states. We apply the classical slow-roll field evolution as well as the Starobinsky and warm inflation stochastic

  • Numerical Investigation for Periodic Orbits in the Hill Three-Body Problem
    Universe (IF 1.752) Pub Date : 2020-05-28
    Vassilis S. Kalantonis

    The current work performs a numerical study on periodic motions of the Hill three-body problem. In particular, by computing the stability of its basic planar families we determine vertical self-resonant (VSR) periodic orbits at which families of three-dimensional periodic orbits bifurcate. It is found that each VSR orbit generates two such families where the multiplicity and symmetry of their member

  • Obscuration and Scattering in Narrow-Line Seyfert 1s
    Universe (IF 1.752) Pub Date : 2020-05-28
    Xiang Pan; Hongyan Zhou; Peng Jiang

    Narrow-line Seyfert 1s (NLS1s) observed at large inclinations from face-on are important for understanding this amazing AGN subclass. However, progress is slowly being made in the huntings and studies of highly obscured ( ≥ 1 ) NLS1s . Recently, we discovered that multi-wavelength photometric and polarimetric analysis can be of great help in identifying and studying highly obscured NLS1s. This paper

  • Cosmic Analogues of Classic Variational Problems
    Universe (IF 1.752) Pub Date : 2020-05-27
    Valerio Faraoni

    Several classic one-dimensional problems of variational calculus originating in non-relativistic particle mechanics have solutions that are analogues of spatially homogeneous and isotropic universes. They are ruled by an equation which is formally a Friedmann equation for a suitable cosmic fluid. These problems are revisited and their cosmic analogues are pointed out. Some correspond to the main solutions

  • Significance of Black Hole Visualization and Its Implication for Science Education Focusing on the Event Horizon Telescope Project
    Universe (IF 1.752) Pub Date : 2020-05-25
    Hye-Gyoung Yoon; Jeongwoo Park; Insun Lee

    In recent years, substantial progress has been made in black hole visualization. However, there is a lack of essential up-to-date information regarding black holes in current school curricula, in spite of students’ substantial interest in black holes. In this study, we examined the implications of the Event Horizon Telescope project, a recent achievement of the scientific community, for science education

  • Localization of Energy and Momentum in an Asymptotically Reissner-Nordström Non-Singular Black Hole Space-Time Geometry
    Universe (IF 1.752) Pub Date : 2020-05-23
    Irina Radinschi; Pradyumn Kumar Sahoo; Theophanes Grammenos; Surajit Chattopadhyay; Marius-Mihai Cazacu

    The space-time geometry exterior to a new four-dimensional, spherically symmetric and charged black hole solution that, through a coupling of general relativity with a non-linear electrodynamics, is non-singular everywhere, for small r it behaves as a de Sitter metric, and asymptotically it behaves as the Reissner-Nordström metric, is considered in order to study energy-momentum localization. For the

  • The Jet-Disk Coupling of Seyfert Galaxies from a Complete Hard X-ray Sample
    Universe (IF 1.752) Pub Date : 2020-05-10
    Xiang Liu; Ning Chang; Zhenhua Han; Xin Wang

    We analyze the jet-disk coupling for different subsamples from a complete hard X-ray Seyfert sample to study the coupling indices and their relation to accretion rate. The results are: (1) the power-law coupling index ranges from nearly unity (linear correlation) for radio loud Seyferts to significantly less than unity for radio quiet ones. This decline trend of coupling index also holds from larger

  • Evidence of Time Evolution in Quantum Gravity
    Universe (IF 1.752) Pub Date : 2020-05-08
    Sergey Cherkas and Vladimir Kalashnikov

    In this paper, we argue that the problem of time is not a crucial issue inherent in the quantum picture of the universe evolution. On the minisuperspace model example with the massless scalar field, we demonstrate four approaches to the description of quantum evolution, which give similar results explicitly. The relevance of these approaches to building a quantum theory of gravity is discussed.

  • Mass in de Sitter and Anti-de Sitter Universes with Regard to Dark Matter
    Universe (IF 1.752) Pub Date : 2020-05-05
    Jean-Pierre Gazeau

    An explanation of the origin of dark matter is suggested in this work. The argument is based on symmetry considerations about the concept of mass. In Wigner’s view, the rest mass and the spin of a free elementary particle in flat space-time are the two invariants that characterize the associated unitary irreducible representation of the Poincaré group. The Poincaré group has two and only two deformations

  • Cosmological Finsler Spacetimes
    Universe (IF 1.752) Pub Date : 2020-05-05
    Manuel Hohmann; Christian Pfeifer; Nicoleta Voicu

    Applying the cosmological principle to Finsler spacetimes, we identify the Lie Algebra of symmetry generators of spatially homogeneous and isotropic Finsler geometries, thus generalising Friedmann-Lemaître-Robertson-Walker geometry. In particular, we find the most general spatially homogeneous and isotropic Berwald spacetimes, which are Finsler spacetimes that can be regarded as closest to pseudo-Riemannian

  • On the Non Metrizability of Berwald Finsler Spacetimes
    Universe (IF 1.752) Pub Date : 2020-05-01
    Andrea Fuster; Sjors Heefer; Christian Pfeifer; Nicoleta Voicu

    We investigate whether Szabo’s metrizability theorem can be extended to Finsler spaces of indefinite signature. For smooth, positive definite Finsler metrics, this important theorem states that, if the metric is of Berwald type (i.e., its Chern–Rund connection defines an affine connection on the underlying manifold), then it is affinely equivalent to a Riemann space, meaning that its affine connection

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