Latest in gr-qc

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An overview of the gravitational spin Hall effectApr 22 2019In General Relativity, the propagation of electromagnetic waves is usually described by the vacuum Maxwell's equations on a fixed curved background. In the limit of infinitely high frequencies, electromagnetic waves can be localized as point particles, ... More
Nonsingular bounce cosmology from general relativityApr 22 2019We investigate a particular classical nonsingular bounce cosmology, which results from general relativity if we allow for degenerate metrics. The simplest model has a constant equation of state and we calculate the modified Hubble diagram for both the ... More
Cosmological Solutions in Multiscalar Field TheoryApr 22 2019We consider a cosmological model with two scalar fields minimally coupled to gravity which have a mixed kinetic term. Hence, Chiral cosmology is included in our analysis. The coupling function and the potential function, which depend on one of the fields, ... More
A Multipolar Effective One Body Model for Non-Spinning Black Hole BinariesApr 21 2019We introduce \TEOBiResumSM{}, a nonspinning inspiral-merger-ringdown waveform model built within the effective one body (EOB) framework that includes gravitational waveform modes beyond the dominant quadrupole $(\ell,|m|) = (2,2)$. The model incorporates: ... More
Astro2020 Science White Paper: Using X-Ray Polarimetry to Probe the Physics of Black Holes and Neutron StarsApr 19 2019This white paper highlights compact object and fundamental physics science opportunities afforded by high-throughput broadband (0.1-60 keV) X-ray polarization observations. X-ray polarimetry gives new observables with geometric information about stellar ... More
Characterization of numerical relativity waveforms of eccentric binary black hole mergersApr 19 2019We introduce a method to quantify the initial eccentricity, gravitational wave frequency, and mean anomaly of numerical relativity simulations that describe non-spinning black holes on moderately eccentric orbits. We demonstrate that this method provides ... More
Secondary CMB temperature anisotropies from magnetic reheatingApr 19 2019Spatially fluctuating primordial magnetic fields~(PMFs) inhomogeneously reheat the Universe when they dissipate deep inside the horizon before recombination. Such an entropy production turns into the additional photon temperature perturbations, in particular, ... More
Gravitational probes of ultra-light axionsApr 18 2019The axion is a hypothetical, well-motivated dark-matter particle whose existence would explain the lack of charge-parity violation in the strong interaction. In addition to this original motivation, an `axiverse' of ultra-light axions (ULAs) with masses ... More
A phase transition creates the geometry of the continuum from discrete spaceApr 18 2019Models of discrete space and space-time that exhibit continuum-like behavior at large lengths could have profound implications for physics. They may tame the infinities that arise from quantizing gravity, and dispense with the machinery of the real numbers, ... More
Axion-Dilaton Destabilization and the Hubble TensionApr 18 2019The discrepancy in measurements of the Hubble constant indicates new physics in dark energy, dark matter, or both. Drawing inspiration from string theory, where axions interact with the other moduli fields, including the dilaton, here we demonstrate that ... More
Constraining the equation of state of high-density cold matter using nuclear and astronomical measurementsApr 18 2019The increasing richness of data related to cold dense matter, from laboratory experiments to neutron star observations, requires a framework for constraining the properties of such matter that makes use of all relevant information. Here we present a rigorous ... More
A transient phase in cosmological evolution : A multi-fluid approximation for a quasi-thermodynamics equilibriumApr 18 2019In this article, we examine the dynamics of a multi-fluid system in which (i) different fluids interact, and (ii) there exists a limit in which the multiple fluids evolve into a mixture that satisfies single-fluid approximation. We consider the potential ... More
Magnonic Analogue Black/White Hole Horizon in Superfluid $^3$He-B: experimentApr 18 2019We provide experimental details of the first experiment made in zero temperature limit ($\sim$ 600\,$\mu$K) studying the magnonic black/white hole horizon analogue using absolutely pure physical system based on the spin superfluidity in superfluid $^3$He-B. ... More
Axially-Symmetric Exact Solutions for Majorana Fermions with GravityApr 18 2019In this paper, we consider Majorana spinor fields in interaction with their own gravitational field: for this case we present axially-symmetry exact solutions. Final comments are given.
Spherical dust collapse in bimetric relativity: Bimetric polytropesApr 18 2019We present a method for solving the constraint equations in the Hassan-Rosen bimetric theory to determine the initial data for the gravitational collapse of spherically symmetric dust. The setup leads to equations similar to those for a polytropic fluid ... More
Vacuum fluctuation, micro-cyclic "universes" and the cosmological constant problemApr 18 2019We show that the usual formulation of the cosmological constant problem breaks down when the effect of the huge fluctuations in quantum vacuum stress-energy tensor is considered. Even if one has successfully fine-tuned the bare cosmological constant in ... More
Gravitino condensate in $N=1$ supergravity coupled to the $N=1$ supersymmetric Born-Infeld theoryApr 18 2019The $N=1$ supersymmetric Born-Infeld theory coupled to $N=1$ supergravity in four spacetime dimensions is studied in the presence of a cosmological term with spontaneous supersymmetry breaking. The consistency is achieved by compensating a negative contribution ... More
Vacuum Decay in Real Time and Imaginary Time FormalismsApr 18 2019We analyze vacuum tunneling in quantum field theory in a general formalism by using the Wigner representation. In the standard instanton formalism, one usually approximates the initial false vacuum state by an eigenstate of the field operator, imposes ... More
Redshift in Finsler spacetimesApr 17 2019We derive and discuss a general redshift formula in Finsler spacetimes. The condition for the existence of a redshift potential is worked out. The results are illustrated with two examples, one refering to a spherically symmetric and static Finsler spacetime ... More
The holographic dual of Rényi relative entropyApr 17 2019The relative entropy is a measure of the distinguishability of two quantum states. A great deal of progress has been made in the study of the relative entropy between an excited state and the vacuum state of a conformal field theory (CFT) reduced to a ... More
Jet-cocoon outflows from neutron star mergers: structure, light curves, and fundamental physicsApr 17 2019The discovery of GW170817, the merger of a binary neutron star (NS) triggered by a gravitational wave detection by LIGO and Virgo, has opened a new window of exploration in the physics of NSs and their cosmological role. Among the important quantities ... More
Surface Theory: the Classical, the Quantum, and the HolographicApr 17 2019Motivated by the power of subregion/subregion duality for constraining the bulk geometry in gauge/gravity duality, we pursue a comprehensive and systematic approach to the behavior of extremal surfaces under perturbations. Specifically, we consider modifications ... More
Typical entropy of a subsystem: Page curve and its varianceApr 17 2019When an isolated quantum system is in a random pure state, the average entropy of a subsystem is close to maximal. The exact formula for the average $\langle{S_{A}}\rangle$ was conjectured by Page in 1995 and later proved. Here we compute the exact formula ... More
Axion superradiance in rotating neutron starsApr 17 2019It is a well-known fact that compact gravitating objects admit bound state configurations for massive bosonic fields. In this work we describe a new class of superradiant instabilities of axion bound states in neutron star magnetospheres. The instability ... More
Black hole shadow in a general rotating spacetime obtained through Newman-Janis algorithmApr 17 2019The Newman-Janis (NJ) algorithm has been extensively used in the literature to generate rotating black hole solutions from nonrotating seed spacetimes. In this work, we show, using various constants of motion, that the null geodesic equations in an arbitrary ... More
The large $D$ membrane paradigm for general four-derivative theory of gravity with a cosmological constantApr 17 2019We find the membrane equations which describe the leading order in $1/D$ dynamics of black holes in the $D\rightarrow\infty$ limit for the most general four-derivative theory of gravity in the presence of a cosmological constant. We work up to linear ... More
Vacuum polarization in high-dimensional AdS spacetime in the presence of a cosmic string and compactified extra dimensionApr 17 2019In this paper, we analyze the vacuum expectation values (VEVs) of the field squared and the energy-momentum tensor associated with a charged and massive scalar quantum field in a generalized $(D+1)$-dimensional anti-de Sitter space in the presence of ... More
A new perspective on galactic dynamicsApr 17 2019We derive the radial acceleration of stars in galaxies by using basic features of thermodynamics, statistical mechanics and general relativity. We assume that the "dark" component of the radial acceleration is originated from the reaction of dark energy ... More
Realtime dynamics of axion particle production due to spontaneous decay of coherent axion fieldApr 17 2019We show that the coherent axion field spontaneously decays by emitting axion particles via quantum tunneling if axion potential has more than one minimum. By employing the $\hbar$-expansion and mean field approximation, we develop a formalism to trace ... More
Quasi-normal modes in a symmetric triangular barrierApr 17 2019Quasi-normal modes (QNMs) of the massless scalar wave in $1+1$ dimensions are obtained for a symmetric, finite, triangular barrier potential. This problem is exactly solvable, with Airy functions involved in the solutions. Before we obtain the QNMs, we ... More
Weyl Covariant Theories of Gravity in Riemann-Cartan-Weyl Space-times I. Topologically Massive GravityApr 17 2019We discuss locally Weyl (scale) covariant generalisations of gravitational theories using Riemann-Cartan-Weyl space-times in arbitrary dimensions. We demonstrate the procedure of Weyl gauging on two examples in particular: General relativity, and topologically ... More
Conformal symmetries in generalised Vaidya spacetimesApr 17 2019In this paper we excavate, for the first time, the most general class of conformal Killing vectors, that lies in the two dimensional subspace described by the null and radial co-ordinates, that are admitted by the generalised Vaidya geometry. Subsequently ... More
Gravitational lensing around Kehagias-Sfetsos compact objects surrounded by plasmaApr 17 2019We study the optical properties of the Kehagias-Sfetsos (KS) compact objects, characterized by the "Ho\v{r}ava" parameter $\omega_{_{KS}}$, in the presence of plasma, considering its homogeneous or power-law density distribution. The strong effects of ... More
Slow-roll inflation in generalized scalar-torsion gravityApr 17 2019We study the dynamics of inflation in a generalized scalar-torsion gravity scenario by assuming a canonical scalar field non-minimally coupled to torsion with a Galileon-type self-interaction. After obtaining the field equations for a flat FRW background, ... More
Testing the Kerr hypothesis using X-ray reflection spectroscopy with NuSTAR data of Cygnus X-1 in the soft stateApr 17 2019We continue exploring the constraining capabilities of X-ray reflection spectroscopy to test the Kerr-nature of astrophysical black holes and we present the results of our analysis of two NuSTAR observations of Cygnus X-1 in the soft state. We find that ... More
A new kind of cyclic universeApr 16 2019Combining intervals of ekpyrotic (ultra-slow) contraction with a (non-singular) classical bounce naturally leads to a novel cyclic theory of the universe in which the Hubble parameter, energy density and temperature oscillate periodically, but the scale ... More
Geometrical tools for embedding fields, submanifolds, and foliationsApr 16 2019Embedding fields provide a way of coupling a background structure to a theory while preserving diffeomorphism-invariance. Examples of such background structures include embedded submanifolds such as branes; boundaries of local subregions, such as the ... More
A hierarchical test of general relativity with gravitational wavesApr 16 2019We propose a hierarchical approach to testing general relativity with multiple gravitational wave detections. Unlike existing strategies, our method does not assume that parameters quantifying deviations from general relativity are either common or completely ... More
On the existence of exotic matter in classical Newtonian mechanicsApr 16 2019According to Newton's law of gravitation the force between two particles depends upon their inertial, as well as their active and passive gravitational masses. For ordinary matter all three of these are equal and positive. We consider here the more general ... More
Measurement of the spin of the M87 black hole from its observed twisted lightApr 16 2019The warped spacetime around a black hole modifies the propagation of light and radio. A recent study predicted that light emitted from the immediate vicinity of a massive rotating black hole (BH) should be twisted, i.e. be imprinted with orbital angular ... More
On thermal field fluctuations in ghost-free theoriesApr 16 2019We study the response of a scalar thermal field to a $\delta$-probe in the context of non-local ghost-free theories. In these theories a non-local form factor is inserted into the kinetic part of the action which does not introduce new poles. For the ... More
Consistency of local and astrophysical tests of the stability of fundamental constantsApr 16 2019Tests of the stability of nature's fundamental constants are one of the cornerstones of the ongoing search for the new physics which is required to explain the recent acceleration of the universe. The two main settings for these tests are high-resolution ... More
Cosmological constant: relaxation vs multiverseApr 16 2019We consider a scalar field with a bottom-less potential, such as $g^3 \phi$, finding that cosmologies unavoidably end up with a crunch, late enough to be compatible with observations if $g \lesssim 1.2 H_0^{2/3} M_{\rm Pl}^{1/3}$. If rebounces avoid singularities, ... More
Nonlinear Dynamics of the Cold Atom Analog False VacuumApr 16 2019We investigate the nonlinear dynamics of cold atom systems that can in principle serve as quantum simulators of false vacuum decay. The analog false vacuum manifests as a metastable vacuum state for the relative phase in a two-species Bose-Einstein condensate ... More
Probing Boson Stars with Extreme Mass Ratio InspiralsApr 16 2019We propose to use gravitational waves from extreme mass ratio inspirals (EMRI), composed of a boson star and a supermassive black hole in the center of galaxies, as a new method to search for boson stars. Gravitational waves from EMRI have the advantage ... More
Imprint of a scalar era on the primordial spectrum of gravitational wavesApr 16 2019Upcoming searches for the stochastic background of inflationary gravitational waves (GWs) offer the exciting possibility to probe the evolution of our Universe prior to Big Bang nucleosynthesis. In this spirit, we explore the sensitivity of future GW ... More
Covariant BSSN formulation in bimetric relativityApr 16 2019Numerical integration of the field equations in bimetric relativity is necessary to obtain solutions describing realistic systems. Thus, it is crucial to recast the equations into a well-posed form. In general relativity, under certain assumptions, the ... More
General Relativistic Cosmological N-body Simulations I: time integrationApr 16 2019This is the first in a series of papers devoted to fully general-relativistic $N$-body simulations applied to late-time cosmology. The purpose of this paper is to present the combination of a numerical relativity scheme, discretization method and time-integration ... More
Curvature radius and Kerr black hole shadowApr 16 2019We consider applications of the curvature radius of a Kerr black hole shadow and propose three new approaches to simultaneously determine the black hole spin and inclination angle of the observer. The first one uses only two symmetric characteristic points, ... More
Rotating black hole shadow in asymptotically safe gravityApr 16 2019We investigate the rotating black hole shadow and its observables in asymptotically safe gravity (ASG). The shape and size of shadow depends on various parameters such as black hole mass $(M)$, spin parameter $(a)$ and ASG parameters $(\zeta)$ and $(\gamma)$. ... More
Kerr black holes with parity-odd scalar hairApr 16 2019We study Kerr black holes with synchronised non-trivial parity-odd massive scalar hair in four dimensional asymptotically flat space-time. These axially symmetric stationary spinning solutions of the minimally coupled Einstein-Klein-Gordon theory provide ... More
Low-energy modified gravity signatures on the large-scale structuresApr 16 2019A large number of dark energy and modified gravity models lead to the same expansion history of the Universe, hence, making it difficult to distinguish them from observations. To make the calculations transparent, we consider $f(R)$ gravity with a pressureless ... More
Constraining Chaplygin models using diffuse supernova neutrino backgroundApr 16 2019In this work, we examine the possibility of using the diffuse supernova neutrino background (DSNB) to test the Chaplygin gas (CG) models of the Universe. With a typical star formation rate $\psi(z)$, supernova rate $R_{\mathrm{SN}}(z)$ and single supernova ... More
Are primordial black holes produced by entropy perturbations in single field inflationary models?Apr 16 2019We show that in single field inflationary models the super-horizon evolution of curvature perturbations on comoving slices $\mathcal{R}$, which can cause the production of primordial black holes (PBH), is not due to entropy perturbations but to a fast ... More
Generalized Hawking-Page transitionsApr 16 2019We construct holographic backgrounds that are dual by the AdS/CFT correspondence to Euclidean conformal field theories on products of spheres $S^{d_1}\times S^{d_2}$, for conformal field theories whose dual may be approximated by classical Einstein gravity ... More
A local Lagrangian for MOND as modified inertiaApr 15 2019We propose a local Lagrangian for a point particle where its inertia part is modified in the regime of small accelerations and its potential energy is kept intact. This Lagrangian is such that for the standard gravitational central force it recovers the ... More
Observable Features of Tachyon-Dominated CosmologyApr 15 2019A Friedman-Robertson-Walker cosmological model dominated by tachyonic---faster-than-light---dark matter can exhibit features similar to those of a standard dark energy/dark matter or Lambda-CDM model. For example, it can undergo expansion which decelerates ... More
Kerr-NUT-de Sitter as an Inhomogeneous Non-Singular Bouncing CosmologyApr 15 2019We present exact non-singular bounce solutions of general relativity in the presence of a positive cosmological constant and an electromagnetic field, without any exotic matter. The solutions are distinguished by being spatially inhomogeneous in one direction, ... More
Exploring the CMB Power Suppression in Canonical Inflation ModelsApr 15 2019There exists some evidence of a suppression in power in the CMB multipoles around $l \sim 20-30$. If taken seriously, this is in tension with the simplest inflationary models driven by a single scalar field with a standard type of slowly varying potential ... More
New Binary Black Hole Mergers in the Second Observing Run of Advanced LIGO and Advanced VirgoApr 15 2019We report the detection of new binary black hole merger events in the publicly available data from the second observing run of advanced LIGO and advanced Virgo (O2). The mergers were discovered using the new search pipeline described in Venumadhav et ... More
Acoustic modes of pulsating axion stars: Non-radial oscillationsApr 15 2019We compute the lowest frequency non-radial oscillation modes of dilute axion stars. The effective potential that enters into the Schr{\"o}dinger-like equation, several associated eigenfunctions, and the large as well as the small frequency separations ... More
Radial oscillations of boson stars made of ultralight repulsive dark matterApr 15 2019We compute the lowest frequency radial oscillation modes of boson stars. It is assumed that the object is made of pseudo-Goldstone bosons subjected to a scalar potential that leads to a repulsive self-interaction force, and which is characterized by two ... More
Radial oscillations of boson stars made of ultralight repulsive dark matterApr 15 2019Apr 22 2019We compute the lowest frequency radial oscillation modes of boson stars. It is assumed that the object is made of pseudo-Goldstone bosons subjected to a scalar potential that leads to a repulsive self-interaction force, and which is characterized by two ... More
Non-vanishing cosmological constant effect in super-Poincare-invariant UniverseApr 15 2019In \cite{AminMoc} we defined the Minkowski superspace $SM(4,4\vert \lambda, \mu)$ as the invariant of the Poincare supergroup of supertransformations, which is a solution of Killing superequations. In the present paper we use formulae of super-Riemannian ... More
Asymptotic safety casts its shadowApr 15 2019We set out to bridge the gap between regular black-hole spacetimes and observations of a black-hole shadow by the Event Horizon Telescope. We explore modifications of spinning and non-spinning black-hole spacetimes inspired by asymptotically safe quantum ... More
Roles of sterile neutrinos in particle physics and cosmologyApr 15 2019The impacts of the light sterile neutrino hypothesis in particle physics and cosmology are reviewed. The observed short baseline neutrino anomalies challenging the standard explanation of neutrino oscillations within the framework of three active neutrinos ... More
United test of the equivalence principle at $10^{-10}$ level using mass and internal energy specified atomsApr 15 2019We use both mass and internal energy specified rubidium atoms to jointly test the weak equivalence principle (WEP). We improve the four-wave double-diffraction Raman transition method (FWDR) we proposed before to select atoms with certain mass and angular ... More
Dark Energy, the Swampland and the Equivalence PrincipleApr 15 2019Apr 17 2019It has recently been argued that string theory does not admit de Sitter vacua. This would imply that the current accelerated expansion of the universe is not driven by a cosmological constant (or vacuum energy) but by other means such as a quintessential ... More
Dark Energy, the Swampland and the Equivalence PrincipleApr 15 2019It has recently been argued that string theory does not admit de Sitter vacua. This would imply that the current accelerated expansion of the universe is not driven by a cosmological constant (or vacuum energy) but by other means such as a quintessential ... More
Bouncing evolution in a model of loop quantum gravityApr 15 2019To understand the dynamics of loop quantum gravity, the deparametrized model of gravity coupled to a scalar field is studied in a simple case, where the graph underlying the spin network basis is one loop based at a single vertex. The Hamiltonian operator ... More
Quantum spacetime and the renormalization group: Progress and visionsApr 15 2019The quest for a consistent theory which describes the quantum microstructure of spacetime seems to require some departure from the paradigms that have been followed in the construction of quantum theories for the other fundamental interactions. In this ... More
Anomalous Current Due to Weyl Anomaly for Conformal Field TheoryApr 15 2019Recently it is found that Weyl anomaly leads to new anomalous currents in an external electromagnetic field in curved spacetime. For simplicity, the initial works focus on weak gravitational fields and the anomalous current is obtained for conformally ... More
Meissner like effect in holographic superconductors with back reactionApr 15 2019In this article we employ the matching method to analytically investigate the properties of holographic superconductors in the framework of Maxwell electrodynamics taking into account the effects of back reaction on spacetime. The relationship between ... More
Spontaneous symmetry breaking or non minimal coupling?Apr 15 2019We show that the combined minimal and non minimal interaction with the gravitational field may produce the generation of a cosmological constant without self-interaction of the scalar field. In the same vein we analyze the existence of states of a scalar ... More
Constraining the neutron star equation of state using Pulse Profile ModelingApr 15 2019One very promising technique for measuring the dense matter Equation of State exploits hotspots that form on the neutron star surface due to the pulsar mechanism, accretion streams, or during thermonuclear explosions in the neutron star ocean. This article ... More
Axion Structure Formation II: The Wrath of CollapseApr 15 2019The first paper in this series showed that QCD axion dark matter, as a highly-correlated Bose fluid, contains extra-classical physics on cosmological scales. The nature of the derived extra-classical physics is exchange-correlation interactions induced ... More
A generally covariant measurement scheme for quantum field theory in curved spacetimesApr 15 2019We propose and develop a measurement scheme for quantum field theory (QFT) in curved spacetimes, in which the QFT of interest, the "system", is dynamically coupled to another, the "probe", in a compact spacetime region. Measurements of observables in ... More
Regular Bardeen AdS Black Hole as a Heat EngineApr 15 2019We investigate the thermodynamic phase transitions and heat engine efficiency in regular Bardeen AdS black hole. Interpreting cosmological constant as thermodynamic pressure, we study the thermodynamics using T S and P v plots. Specific heat studies also ... More
Symmetry breaking and lattice kirigami: finite temperature effectsApr 15 2019Recent work has analysed how deformations due to the insertion of a defect in a flat hexagonal lattice affect the ground state structure of an interacting fermion field theory. Such modifications result in an increase of the order parameter in the vicinity ... More
Ultra-compact spherically symmetric dark matter charged star objectsApr 15 2019We study the properties of ultra-compact spherically symmetric dark matter sector star objects, being the solution of Einstein equations with two $U(1)$-gauge fields. One of them is the ordinary Maxwell field, while the auxiliary gauge field pertains ... More
Black hole solutions correspondence between conformal and massive theories of gravityApr 15 2019In this work, a correspondence between black hole solutions of conformal and massive theories of gravity is found. It is seen that this correspondence imposes some constraints on parameters of these theories. What's more, a relation between the mass of ... More
Bit threads and holographic entanglement of purificationApr 15 2019The entanglement of purification (EoP), which measures the classical correlations and entanglement of a given mixed states, has been conjectured to be dual to the area of the minimal cross section of the entanglement wedge in holography. Using the surface-state ... More
A bound on Planck-scale deformations of CPT from muon lifetimeApr 14 2019We show that deformed relativistic kinematics, expected to emerge in a flat-spacetime limit of quantum gravity, predicts different lifetimes for particles and their antiparticles. This phenomenon is a consequence of Planck-scale modifications of the action ... More
Bootstrapped Newtonian stars and black holesApr 14 2019We study equilibrium configurations of a homogenous ball of matter in a bootstrapped description of gravity which includes a gravitational self-interaction term beyond the Newtonian coupling. Both matter density and pressure are accounted for as sources ... More
Even parity potential for spacetimes with Gaussian matter source and its associated QNM spectraApr 14 2019We have obtained the general form of even mode potential function for the gravitational perturbation of a static spherically symmetric spacetime. Considering the minimal-spread Gaussian matter source, parameterized by a smearing length scale {\Theta}, ... More
Rotating cylinders with anisotropic fluids in general relativityApr 14 2019We consider anisotropic fluids with directional pressures $p_i = w_i \rho$ ($\rho$ is the density, $w_i = $const, $i = 1,2,3$) as sources of gravity in stationary cylindrically symmetric space-times. We describe a general way of obtaining exact solutions ... More
Aharonov-Bohm rings in de Sitter expanding universeApr 14 2019Apr 17 2019The $(1+3)$-dimensional Dirac equation of the fermions moving in ideal Aharonov-Bohm rings in the de Sitter expanding universe is used for deriving the exact expressions of the general relativistic partial currents and corresponding energies. In the de ... More
Aharonov-Bohm rings in de Sitter expanding universeApr 14 2019The $(1+3)$-dimensional Dirac equation of the fermions moving in ideal Aharonov-Bohm rings in the de Sitter expanding universe is used for deriving the exact expressions of the general relativistic partial currents and corresponding energies. In the de ... More
Stueckelberg breaking of Weyl conformal geometry and applications to gravityApr 13 2019Weyl conformal geometry may play a role in early cosmology where effective theory at short distances becomes conformal. Weyl conformal geometry also has a built-in geometric Stueckelberg mechanism: it is broken spontaneously to Riemannian geometry after ... More
Spontaneous scalarization of black holes in the Horndeski theoryApr 13 2019We investigate the possibility of spontaneous scalarization of static, spherically symmetric, and asymptotically flat black holes (BHs) in the Horndeski theory. Spontaneous scalarization of BHs is a phenomenon that the scalar field spontaneously obtains ... More
The gyroscopic frequency of metric $f(R)$ and generalised Brans-Dicke theories: constraints from Gravity Probe-BApr 13 2019We confront the predicted gyroscopic precession (in particular the geodetic precession) from metric $f(R)$ theory with the data provided by the mission, Gravity Probe-B. We find the constraint, $|a_2| < 1.33\times 10^{12} \mathrm{m}^2$, where $a_2$ is ... More
The gyroscopic frequency of metric $f(R)$ and generalised Brans-Dicke theories: constraints from Gravity Probe-BApr 13 2019Apr 17 2019We confront the predicted gyroscopic precession (in particular the geodetic precession) from metric $f(R)$ theory with the data provided by the mission, Gravity Probe-B. We find the constraint, $|a_2| < 1.33\times 10^{12} \mathrm{m}^2$, where $a_2$ is ... More
Semiclassical gravity effects near horizon formationApr 13 2019We study the magnitude of semiclassical gravity effects near the formation of a black-hole horizon in spherically-symmetric spacetimes. As a probe for these effects we use a quantised massless scalar field. Specifically, we calculate two quantities derived ... More
Electromagnetic self-force in the five dimensional Myers-Perry space timeApr 13 2019We calculate the effects of the electromagnetic self-force on a charged particle outside a five dimensional Myers-Perry space-time. Based on our earlier work [1], we obtain the self-force using quaternions in Janis-Newman and Giampieri algorithms. In ... More
Gravity and Nonlinear Symmetry RealisationApr 13 2019Application of nonlinear symmetry realisation technique to gravity is studied. We identify the simplest extensions of the Poincare group suitable for nonlinear realisation. Among them only one model is suitable for description of massless spin-2 states. ... More
Black hole evaporation in Lovelock gravity with diverse dimensionsApr 13 2019We investigate the black hole evaporation process in Lovelock gravity with diverse dimensions. By selecting the appropriate coefficients, the space-time solutions can possess a unique AdS vacuum with a fixed cosmological constant $\Lambda=-\frac{(d-1)(d-2)}{2\ell^{2}}$. ... More
Dual 2+1D Loop Quantum Gravity on the EdgeApr 12 2019In a recent paper, we introduced a new discretization scheme for gravity in 2+1 dimensions. Starting from the continuum theory, this new scheme allowed us to rigorously obtain the discrete phase space of loop gravity, coupled to particle-like "edge mode" ... More
Spontaneous scalarization in generalised scalar-tensor theoryApr 12 2019Spontaneous scalarization is a mechanism that endows relativistic stars and black holes with a nontrivial configuration only when their spacetime curvature exceeds some threshold. The standard way to trigger spontaneous scalarization is via a tachyonic ... More
Quantum Cosmology and the Generalized Uncertainty PrincipleApr 12 2019A Kantowski-Sachs model with a modified quantization prescription is considered. Such quantization rules, inspired by the so-called Generalized Uncertainty Principle (GUP), correspond to a modified commutation relation between minisuperspace variables ... More
Characterizing the sensitivity of isolated continuous gravitational wave searches to binary orbitsApr 12 2019Broadband all-sky searches for continuous gravitational waves (CW) from isolated neutron stars typically yield a number of significant candidates that are discarded through hierarchical semi-coherent and coherent follow-up searches. However, these searches ... More