Relativistic Klein-Gordon Equation Research Articles

Exact phonon quasibound states around an optical black hole

In this work, we present an exact solution of phonon quasibound states in a vortex photon flow that creates an analogous black hole background. We worked out and successfully solve the governing differential equation of the systen that is similar with the relativistic Klein–Gordon equation. The exact radial solutions are discovered in terms of the confluent Heun functions that behaves as ingoing waves near the black hole’s horizon and decaying far away from the black hole’s horizon. The polynomial condition of the confluent Heun function leads to the discovery of the the complex valued quantized energy levels expression of the quasibound state of which depends on the phonon mass Ω0\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$\\Omega _0$$\\end{document}, the photon vortex horizon’s spin ΩH\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$\\Omega _H$$\\end{document} and the azimuthal and the main quantum number (m, n). In the last section, by using the Damour–Ruffini method, the Hawking radiation of the analog black hole’s horizon is investigated to derive the phononic radiation distribution function from where, the Hawking temberature is obtained.

Behavior of spin-0 scalar particles in Eddington-inspired Born–Infeld gravity global monopole with harmonic oscillator potential

In this paper, we investigate the behavior of a scalar bosonic field within the backdrop of Eddington-inspired Born–Infeld gravity with a global monopole configuration. Additionally, we consider the presence of both scalar and vector potentials. To introduce the scalar potential, we perform a transformation on the mass term, replacing [Formula: see text] with [Formula: see text]. For the vector potential, we apply a minimal coupling scheme, transforming [Formula: see text] within the relativistic Klein–Gordon equation. We opt for a harmonic oscillator scenario where the scalar and vector potentials are equal, i.e. [Formula: see text]. Through this setup, we analytically solve the wave equation using the confluent Heun equation form. Subsequently, we delve into the quantum system in the absence of any potential, determining the permissible values for bound-state relativistic energy levels and the scalar field’s wave function. Our analysis reveals that the energy levels and wave function are influenced by various parameters present in the eigenvalue expression.

Inertio-gravity Poincaré waves and the quantum relativistic Klein–Gordon equation, near-inertial waves and the non-relativistic Schrödinger equation

Shallow water inertio-gravity Poincaré waves in a rotating frame satisfy the Klein–Gordon equation, originally derived for relativistic, spinless quantum particles. Here, we compare these two superficially unrelated phenomena, suggesting a reason for them sharing the same equation. We discuss their energy conservation laws and the equivalency between the non-relativistic limit of the Klein–Gordon equation, yielding the Schrödinger equation, and the near-inertial wave limit in the shallow water system.

Fresh look at the effects of gravitational tidal forces on a freely-falling quantum particle

In this paper, we take a closer and new look at the effects of tidal forces on the free fall of a quantum particle inside a spherically symmetric gravitational field. We derive the corresponding Schrödinger equation for the particle by starting from the fully relativistic Klein–Gordon equation in order (i) to briefly discuss the issue of the equivalence principle and (ii) to be able to compare the relativistic terms in the equation to the tidal-force terms. To the second order of the nonrelativistic approximation, the resulting Schrödinger equation is that of a simple harmonic oscillator in the horizontal direction and that of an inverted harmonic oscillator in the vertical direction. Two methods are used for solving the equation in the vertical direction. The first method is based on a fixed boundary condition, and yields a discrete-energy spectrum with a wavefunction that is asymptotic to that of a particle in a linear gravitational field. The second method is based on time-varying boundary conditions and yields a quantized-energy spectrum that is decaying in time. Moving on to a freely-falling reference frame, we derive the corresponding time-dependent energy spectrum. The effects of tidal forces yield an expectation value for the Hamiltonian and a relative change in time of a wavepacket’s width that are mass-independent. The equivalence principle, which we understand here as the empirical equivalence between gravitation and inertia, is discussed based on these various results. For completeness, we briefly discuss the consequences expected to be obtained for a Bose–Einstein condensate or a superfluid in free fall using the nonlinear Gross–Pitaevskii equation.

Molecular energies of a modified and deformed exponential-type potential model

The solutions of a one-dimensional relativistic Klein-Gordon equation for a modified and deformed exponential-type potential are obtained using supersymmetric approach and parametric Nikiforov-Uvarov method respectively. The numerical values for lithium molecule were obtained using the energy equations from the two methods. The non-relativistic limit of the relativistic Klein-Gordn equation was obtained for each of the energy equation using a popular transformation invoked on the solution of the Klein-Gordon equation. Numerical values for lithium and sodium molecules were also generated based on the two methods. The generated values for both relativistic and non-relativistic were compared with the experimental values. These results agreed perfectly with the experimental values of the studied molecules.

Entropic system in the relativistic Klein-Gordon Particle

The solutions of Kratzer potential plus Hellmann potential was obtained under the Klein-Gordon equation via the parametric Nikiforov-Uvarov method. The relativistic energy and its corresponding normalized wave functions were fully calculated. The theoretic quantities in terms of the entropic system under the relativistic Klein-Gordon equation (a spinless particle) for a Kratzer-Hellmann’s potential model were studied. The effects of a and b respectively (the parameters in the potential that determine the strength of the potential) on each of the entropy were fully examined. The maximum point of stability of a system under the three entropies was determined at the point of intersection between two formulated expressions plotted against a as one of the parameters in the potential. Finally, the popular Shannon entropy uncertainty relation known as Bialynick-Birula, Mycielski inequality was deduced by generating numerical results.

Eigensolution techniques, expectation values and Fisher information of Wei potential function.

An approximate solution of the one-dimensional relativistic Klein-Gordon equation was obtained under the interaction of an improved expression for Wei potential energy function. The solution of the non-relativistic Schrödinger equation was obtained from the solution of the relativistic Klein-Gordon equation by certain mappings. We have calculated Fisher information for position space and momentum space via the computation of expectation values. The effects of some parameters of the Wei potential energy function on the Fisher information were fully examined graphically. We have also examined the effects of the quantum number n and the angular momentum quantum number ℓ on the expectation values and Fisher information respectively for some selected molecules. Our results revealed that the variation of most of the parameters of the Wei potential energy function against the Fisher information does not obey the Heisenberg uncertainty relation for Fisher information while that of the quantum number and angular momentum quantum number on Fisher information obeyed the relation.

Bound Electron Transitions under the Influence of Electromagnetic Wave in Constant Magnetic Field

Motion and radiative transitions of an electron in a magnetic field under the influence of an external electromagnetic wave are studied for various confining conditions in semiconductor, graphene, in quantum wells, and relativistic generalization in terms of the Klein–Gordon equation are considered. In particular, the following problems are discussed. The so-called cyclotron resonance, which may appear in graphene, is studied with indication for appearance of the so-called frequency-halving. The problem is solved for two-dimensional massless charged particle, whose gapless nature is protected by sublattice symmetry. The exact classical calculation of this effect is undertaken in the framework of a 2D classical equation for a zero-mass electron. We also find an exact solution of the Schrödinger equation for charge carriers in semiconductors under the influence of an external magnetic field and in the field of electromagnetic wave with an account for their radiative transitions. Solutions of the relativistic Klein–Gordon equation in this configuration of electromagnetic fields are found as a certain generalization of the results obtained for the non-relativistic case. These results may serve as a first step for further efforts to find exact solutions of wave equations for quasiparticles in solid state structures in external fields.

Bound State Solutions of Three-Dimensional Klein-Gordon Equation for Two Model Potentials by NU Method

In this study, we investigate the relativistic Klein-Gordon equation analytically for the Deng-Fan potential and Hulthen plus Eckart potential under the equal vector and scalar potential conditions. Accordingly, we obtain the energy eigenvalues of the molecular systems in different states as well as the normalized wave function in terms of the generalized Laguerre polynomials function through the NU method, which is an effective method for the exact solution of second-order linear differential equations.

Global view of QCD axion stars

Taking a comprehensive view, including a full range of boundary conditions, we reexamine QCD axion star solutions based on the relativistic Klein-Gordon equation (using the Ruffini-Bonazzola approach) and its non-relativistic limit, the Gross-Pitaevskii equation. A single free parameter, conveniently chosen as the central value of the wavefunction of the axion star, or alternatively the chemical potential with range $-m<\mu< 0$ (where $m$ is the axion mass), uniquely determines a spherically-symmetric ground state solution, the axion condensate. We clarify how the interplay of various terms of the Klein-Gordon equation determines the properties of solutions in three separate regions: the structurally stable (corresponding to a local energy minimum) dilute and dense regions, and the intermediate, structurally unstable transition region. From the Klein-Gordon equation, one can derive alternative equations of motion including the Gross-Pitaevskii and Sine-Gordon equations, which have been used previously to describe axion stars in the dense region. In this work, we clarify precisely how and why such methods break down as the binding energy increases, emphasizing the necessity of using the full relativistic Klein-Gordon approach. Finally, we point out that, even after including perturbative axion number violating corrections, solutions to the equations of motion, which assume approximate conservation of axion number, break down completely in the regime with strong binding energy, where the magnitude of the chemical potential approaches the axion mass.

Tunable Magnonic Thermal Hall Effect in Skyrmion Crystal Phases of Ferrimagnets.

We theoretically study the thermal Hall effect by magnons in skyrmion crystal phases of ferrimagnets in the vicinity of the angular momentum compensation point (CP). To this end, we start by deriving the equation of motion for magnons in the background of an arbitrary equilibrium spin texture, which gives rise to the fictitious electromagnetic field for magnons. As the net spin density varies, the resultant equation of motion interpolates between the relativistic Klein-Gordon equation at the CP and the nonrelativistic Schrödinger-like equation away from it. In skyrmion crystal phases, the right- and the left-circularly polarized magnons, with respect to the order parameter, are shown to form the Landau levels separately within the uniform skyrmion-density approximation. For an experimental proposal, we predict that the magnonic thermal Hall conductivity changes its sign when the ferrimagnet is tuned across the CP, providing a way to control heat flux in spin-caloritronic devices on the one hand and a feasible way to detect the CP of ferrimagnets on the other hand.

Klein–Gordon equation in curved space-time

We report the methods and results of a computational physics project on the solution of the relativistic Klein–Gordon equation for a light particle gravitationally bound to a heavy central mass. The gravitational interaction is prescribed by the metric of a spherically symmetric space-time. Metrics are considered for an impenetrable sphere, a soft sphere of uniform density, and a soft sphere with a linear transition from constant to zero density; in each case the radius of the central mass is chosen to be sufficient to avoid any event horizon. The solutions are obtained numerically and compared with nonrelativistic Coulomb-type solutions, both directly and in perturbation theory, to study the general-relativistic corrections to the quantum solutions for a 1/r potential. The density profile with a linear transition is chosen to avoid singularities in the wave equation that can be caused by a discontinuous derivative of the density. This project should be of interest to instructors and students of computational physics at the graduate and advanced undergraduate levels.

Perturbed Coulomb Potentials in the Klein–Gordon Equation: Quasi-Exact Solution

Using the Lie algebraic approach, we present the quasi-exact solutions of the relativistic Klein–Gordon equation for perturbed Coulomb potentials namely the Cornell potential, the Kratzer potential and the Killingbeck potential. We calculate the general exact expressions for the energies, corresponding wave functions and the allowed values of the parameters of the potential within the representation space of sl(2) Lie algebra. In addition, we show that the considered equations can be transformed into the Heun’s differential equations and then we reproduce the results using the associated special functions. Also, we study the special case of the Coulomb potential and show that in the non-relativistic limit, the solution of the Klein–Gordon equation converges to that of Schrodinger equation.

Approximate Analytical Solutions of the Effective Mass Klein-Gordon Equation for Two Interacting Potentials

In this study, the approximate analytical solutions of the relativistic Klein-Gordon equation in the spatial dimensions with unequal Coulomb-inverse Trigonometry scarf scalar and vector potentials for an effective mass function is investigated in the framework of supersymmetric and shape invariance method by employing a suitable approximation scheme to the centrifugal term. The energy equation for some special cases such as the Coulomb potential and inverse Trigonometry scarf potential are obtained. Using a certain transformation, the non-relativistic energy equation is obtained which is identical to the energy equation of the Hellmann potential.

Edge magnetism of Heisenberg model on honeycomb lattice

Edge magnetism in graphene sparks intense theoretical and experimental interests. In the previous study, we demonstrated the existence of collective excitations at the zigzag edge of the honeycomb lattice with long-ranged Néel order. By employing the Schwinger-boson approach, we show that the edge magnons remain robust even when the long-ranged order is destroyed by spin fluctuations. Furthermore, in the effective field-theory limit, the dynamics of the edge magnon is captured by the one-dimensional relativistic Klein-Gordon equation. It is intriguing that the boundary field theory for the edge magnon is tied up with its bulk counterpart. By performing density-matrix renormalization group calculations, we show that the robustness may be attributed to the closeness between the ground state and the Néel state. The existence of edge magnon is not limited to the honeycomb structure, as demonstrated in the rotated-square lattice with zigzag edges as well. The universal behavior indicates that the edge magnons may attribute to the uncompensated edges and can be detected in many two-dimensional materials.

Theory of Stochastic Schrödinger Equation in Complex Vector Space

A generalized Schrodinger equation containing correction terms to classical kinetic energy, has been derived in the complex vector space by considering an extended particle structure in stochastic electrodynamics with spin. The correction terms are obtained by considering the internal complex structure of the particle which is a consequence of stochastic average of particle oscillations in the zeropoint field. Hence, the generalised Schrodinger equation may be called stochastic Schrodinger equation. It is found that the second order correction terms are similar to corresponding relativistic corrections. When higher order correction terms are neglected, the stochastic Schrodinger equation reduces to normal Schrodinger equation. It is found that the Schrodinger equation contains an internal structure in disguise and that can be revealed in the form of internal kinetic energy. The internal kinetic energy is found to be equal to the quantum potential obtained in the Madelung fluid theory or Bohm statistical theory. In the rest frame of the particle, the stochastic Schrodinger equation reduces to a Dirac type equation and its Lorentz boost gives the Dirac equation. Finally, the relativistic Klein–Gordon equation is derived by squaring the stochastic Schrodinger equation. The theory elucidates a logical understanding of classical approach to quantum mechanical foundations.

The Relativistic Quantum Hydrodynamic Representation of Klein-Gordon Equation

The quantum hydrodynamic-like equations for two real variables (i.e., the phase and the amplitude of the wave function) of the relativistic Klein-Gordon equation are derived in the present paper. The paper also shows that in classical limit the hydrodynamic Klein-Gordon equations lead to the Madelung pseudo-potential as well as to the quantum pseudo potential for a charged particle given by Janossy and by Bialynicki et al. The origin of the non-local interactions of quantum mechanics in the hydrodynamic model is discussed both for free and charged particles. The generalization to the stochastic case is preliminarily depicted.

Hydrodynamics of the physical vacuum: Dark matter is an illusion

The relativistic hydrodynamical equations are being examined with the aim of extracting the quantum-mechanical equations (the relativistic Klein–Gordon equation and the Schrödinger equation in the non-relativistic limit). In both cases we find the quantum potential, which follows from pressure gradients within a superfluid vacuum medium. This special fluid, endowed with viscosity allows to describe emergence of the flat orbital speeds of spiral galaxies. The viscosity averaged on time vanishes, but its variance is different from zero. It is a function fluctuating about zero. Therefore, the flattening is the result of the energy exchange of the torque with zero-point fluctuations of the physical vacuum on the ultra-low frequencies.

Relativistic Treatment of Spinless Particles Subject to Modified Scarf II Potential

We employ the parametric generalization of Nikiforov-Uvarov method to obtain the bound state solutions the relativistic Klein-Gordon equation under equal scalar and vector modified Scarf II potential. The energy eigenvalues and the corresponding wave functions expressed in term of Jacobi polynomial are equally obtained. Our results will have many applications in many branches of physics especially nuclear physics where it could be used in describing nuclei interactions .For further guide to interested readers, we have also provided numerical data which discuses the energy spectra.

A Travelling Wave Group III—Consistent with QED

The travelling wave group is a stable wave packet. Many surprising results are derived from it. The group is easily quantized for photons and applied, as a solution to the relativistic Klein-Gordon equation, to free particles. Further solutions to the resulting algebraic equation provide a stable wave function for free antiparticles. Consistency with the superstructure of quantum electrodynamics is obtained by an assignment to the electron antiparticle of negative mass and negative charge. Then in 5-dimensional space-time-mass, CPT invariance transforms to M’PT conservation in either charged or neutral particles, while many other consequences are also evident.