The (1+1) Dimensional Dirac Equation With Pseudoscalar Potentials: Path Integral Treatment

The supersymetric path integrals in solving the problem of relativistic spinning particle interacting with pseudoscalar potentials is examined. The relative propagator is presented by means of path integral, where the spin degrees of freedom are described by odd Grassmannian variables and the gauge invariant part of the effective action has a form similar to the standard pseudoclassical action given by Berezin and Marinov. After integrating over fermionic variables (Grassmannian variables), the problem is reduced to a nonrelativistic one with an effective supersymetric potential. Some explicit examples are considered, where we have extracted the energy spectrum of the electron and the wave functions. PACS numbers: 03.65. Ca-Formalism, 03.65. Db-Functional analytical methods, 03.65. Pm-Relativistic wave equations.     

浅水体系中的多孤立波

形式分离变量法被推广应用于寻求不可积模型的多孤立波解.特别地,应用形式分离变量法于三个描述浅水体系的非线性方程:推广WhithamBroerKaup(WBK)方程、2+1维耦合KortewegdeVries(KdV)方程和1+1维耦合KdV方程,给出了这些体系的明显的解析的多孤立波解 关键词： 浅水体系 多孤立波 形式分离变量法 不可积模型     

Pair creation in Feshbach-Villars formalism with two components

We have studied the behavior of the Feshbach-Villars equation (FV₀) in comparison with the Klein-Gordon one (KG) in the problem of particle pair creation from the vacuum in an external electromagnetic field, considering two approaches: the Schwinger effective action method and the Bogoliubov transformation technique. In the first approach the vacuum to vacuum transition amplitude is calculated treating the FV₀ field like a bosonic field. For the second approach, that uses canonical quantization, it is shown that the relative fields and their conjugate moments obey a commutation relation and not anticommutation one. The pair creation probability and the probability that the vacuum remains a vacuum calculated from the FV₀ equation are, consequently, the same as those obtained from the KG one.Received: 12 January 2005, Revised: 24 March 2005, Published online: 4 May 2005PACS: 03.65.Ca, 03.65.Db, 03.65.Pm, 23.20.Ra     

Path integral for one-dimensional Dirac oscillator

In this paper we derive the propagator for the one-dimensional Dirac oscillator using the supersymmetric path integral formalism. The spin calculations are carried out with the help of the technique of Grassmann functional integration. The Green function is exactly evaluated. The Polyakov spin factor is explicitly derived and the energy spectrum and the corresponding wave functions are deduced. PACS 03.65.Ca; 03.65.Db; 03.65.Ge; 03.65.Pm     

Nonlocality and entanglement in a strange system

We show that the relation between nonlocality and entanglement is subtler than one naively expects. In order to do this we consider the neutral kaon system – which is oscillating in time (particle–anti-particle mixing) and decaying – and describe it as an open quantum system. We consider a Bell–CHSH inequality and show a novel violation for non-maximally entangled states. Considering the change of purity and entanglement in time we find that, despite the fact that only two degrees of freedom at a certain time can be measured, the neutral kaon system does not behave like a bipartite qubit system. PACS 03.65.Ud; 03.65.Yz     

Construction of New Variable Separation Excitations via Extended Projective Ricatti Equation Expansion Method in (2+ 1)- Dimensional Dispersive Long Wave Systems

Utilizing the extended projective Ricatti equation expansion method, abundant variable separation solutions of the (2+1)-dimensional dispersive long wave systems are obtained. From the special variable separation solution (38) and by selecting appropriate functions, new types of interaction between the multi-valued and the single-valued solitons, such as semi-foldon and dromion, semi-foldon and peakon, semi-foldon and compacton are found. Meanwhile, we conclude that the solution v is essentially equivalent to the ’universal” formula (1). PACS numbers 05.45.Yv, 02.30.Jr, 03.65.Ge     

Quantization for brachistochrone problem

The brachistochrone curve corresponds to the minimization of the time functional. In this paper we discuss the dynamics of a massive particle, which moves classically on the brachistochrone curve under the potential V=-mgy. We derive the Lagrangian and the Hamiltonian of the particle and show that this problem corresponds to the particle in an infinite wall with a harmonic oscillator potential and the solutions of Schrödingers equation are confluent hypergeometric functions. We also discuss the periodic potential problem for the brachistochrones and obtain the band structure of Kronig-Penney model for the particle with positive energy in a certain limit.Received: 29 January 2003, Published online: 30 July 2003PACS: 03.65.-w Quantum mechanics - 03.65.Ge Solutions of wave equations: bound states - 71.15.Ap Basis sets (LCAO, plane-wave, APW, etc.) and related methodology (scattering methods, ASA, linearized methods, etc.)     

Quantum Mutual Entropy for a Multilevel Atom Interacting with a Cavity Field

We derive an explicit formula for the quantum mutual entropy as a measure of the total correlations in a multi-level atom interacting with a cavity field. We describe its theoretical basis and discuss its practical relevance. The effect of the number of levels involved on the quantum mutual entropy is demonstrated via examples of three-, four- and five-level atom. Numerical calculations under current experimental conditions are performed and it is found that the number of levels present changes the general features of the correlations dramatically. PACS numbers: 32.80.−t, 42.50.Ct, 03.65.Ud, 03.65.Yz.     

Small corrections to the tunneling phase-time formulation

After reexamining the above-barrier diffusion problem where we notice that the wave packet collision implies the existence of multiple reflected and transmitted wave packets, we analyze the way of obtaining phase times for tunneling/reflecting particles in a particular colliding configuration where the idea of multiple peak decomposition is recovered. To partially overcome the analytical incongruities which frequently arise when the stationary phase method is adopted for computing the (tunneling) phase-time expressions, we present a theoretical exercise involving a symmetrical collision between two identical wave packets and a unidimensional squared potential barrier where the scattered wave packets can be recomposed by summing the amplitudes of simultaneously reflected and transmitted wave components so that the conditions for applying the stationary phase principle are totally recovered. Lessons concerning the use of the stationary phase method are drawn. PACS 02.30.Mv, 03.65.Xp     

Relativistic effects in bound two-particle systems

The predictions of relativistic Schrödinger theory (RST) for the relativistic effects in helium-like ions with high nuclear charge ( -80) are elaborated in the electrostatic approximation (i.e. neglection of the magnetic interactions). The corresponding RST results are found to meet with the experimental data and with the predictions of other theoretical approaches, provided an estimate of the (neglected) magnetic effects is taken into account. This suggests to carry through high-precision calculations (including the magnetic forces) in order to further test the physical significance of RST.Received: 28 August 2003, Published online: 20 April 2004PACS: 03.65.Pm Relativistic wave equations - 03.65.Ge Solutions of wave equations: bound states - 03.65.Ud Entanglement and quantum nonlocality (e.g. EPR paradox, Bells inequalities, GHZ states, etc.)     

Quantization and conformal properties of a generalized Calogero model

We analyze a generalization of the quantum Calogero model with the underlying conformal symmetry, paying special attention to the two-body model deformation. Owing to the underlying SU(1,1) symmetry, we find that the analytic solutions of this model can be described within the scope of the Bargmann representation analysis, and we investigate its dynamical structure by constructing the corresponding Fock space realization. The analysis from the standpoint of supersymmetric quantum mechanics (SUSYQM), when applied to this problem, reveals that the model is also shape invariant. For a certain range of the system parameters, the two-body generalization of the Calogero model is shown to admit a one-parameter family of self-adjoint extensions, leading to inequivalent quantizations of the system. PACS 02.30.Ik; 03.65.Fd; 03.65.-w     

A symmetry relating certain processes in 2-and 4-dimensional space-times and the value α0 = 1/4π of the bare fine structure constant

The symmetry manifests itself in exact relations between the Bogoliubov coefficients for processes induced by an accelerated point mirror in 1 + 1 dimensional space and the current (charge) densities for the processes caused by an accelerated point charge in 3 + 1 dimensional space. The spectra of pairs of Bose (Fermi) massless quanta emitted by the mirror coincide with the spectra of photons (scalar quanta) emitted by the electric (scalar) charge up to the factor e ²/ħc. The integral relation between the propagator of a pair of oppositely directed massless particles in 1 + 1 dimensional space and the propagator of a single particle in 3 + 1 dimensional space leads to the equality of the vacuum-vacuum amplitudes for the charge and the mirror if the mean number of created particles is small and the charge e = √ħc. Due to the symmetry, the mass shifts of electric and scalar charges (the sources of Bose fields with spin 1 and 0 in 3 + 1 dimensional space) for the trajectories with a subluminal relative velocity β₁₂ of the ends and the maximum proper acceleration w ₀ are expressed in terms of the heat capacity (or energy) spectral densities of Bose and Fermi gases of massless particles with the temperature w ₀/2π in 1 + 1 dimensional space. Thus, the acceleration excites 1-dimensional oscillation in the proper field of a charge, and the energy of oscillation is partly deexcited in the form of real quanta and partly remains in the field. As a result, the mass shift of an accelerated electric charge is nonzero and negative, while that of a scalar charge is zero. The symmetry is extended to the mirror and charge interactions with the fields carrying spacelike momenta and defining the Bogoliubov coefficients α^B,F. The traces trα^B,F, which describe the vector and scalar interactions of the accelerated mirror with a uniformly moving detector, were found in analytic form for two mirror trajectories with subluminal velocities of the ends. The symmetry predicts one and the same value e ₀ = √ħc for the electric and scalar charges in 3 + 1 dimensional space. Arguments are adduced in favor of the conclusion that this value and the corresponding value α₀ = 1/4π of the fine structure constant are the bare, nonrenormalized values. The text was submitted by the author in English.     

DKP Equation with Smooth Potential and Position-Dependent Mass

The Duffin-Kemmer-Petiau (DKP) equation for spin 0 and 1 with smooth potential and position dependent- mass is solved. The solution is given in terms of the Heun function. The step case for potential and mass are deduced as a limiting case. The boundary conditions are also discussed. PACS Numbers:03.30.+p, 03.65.Pm, 03.65.Ge, 03.65.Db     

A new ab initio method of calculating $\mathsf{Z_{eff}}$ and positron annihilation rates using coupled-channel T-matrix amplitudes

We present a new ab initio theoretical formulation to calculate and hence the positron annihilation rates directly from the onshell and offshell (half) scattering amplitudes. The method does not require any explicit use of the scattering wave function and is formally exact within the framework of the well established Lippmann-Schwinger equation. It could serve as an effective tool as all the T-, K-, and S-matrix formulations, yield directly the scattering amplitudes; not the wave function. Numerical test of the method is presented considering sample static calculations in positron-hydrogen and positron-helium systems.Received: 15 January 2004, Published online: 15 April 2004PACS: 03.65.Nk Scattering theory - 34.85. + x Positron scattering - 71.60. + z Positron states - 78.70.Bj Positron annihilation     

Bound-State Solutions of the Klein-Gordon Equation for the Generalized <Emphasis Type="Italic">PT</Emphasis>-Symmetric Hulthén Potential

The one-dimensional Klein-Gordon equation is solved for the PT-symmetric generalized Hulthén potential in the scalar coupling scheme. The relativistic bound-state energy spectrum and the corresponding wave functions are obtained by using the Nikiforov-Uvarov method which is based on solving the second-order linear differential equations by reduction to a generalized equation of hypergeometric type. PACS numbers: 03.65.Fd, 03.65.Ge     

Nonlinear Airy Light Bullets in a 3D Self‐Defocusing Medium

The (3+1)‐dimensional [(3+1)D] nonlinear Schrödinger (NLS) equation is investigated, describing the propagation of nonlinear spatiotemporal wave packets in a self‐defocusing medium, and a new type of Airy spatiotemporal solutions is presented. By using the reductive perturbation method, the (3+1)D NLS equation is reduced to the spherical Kortewegde Vries (SKdV) equation. Based on the Hirota's bilinear method, the bilinear form of the SKdV equation is constructed and Airy light bullet (LB) solutions of different orders are obtained, which depend on the sets of two free constants associated with the amplitude and initial phase. The results show that these Airy LBs can exist in the self‐defocusing medium and their intensities can be controlled by selecting the suitable free parameters along the propagation distance. As examples, three types of low‐order approximate LB solutions are presented and their intensity profiles numerically discussed. The obtained results are helpful in exploring nonlinear phenomena in a self‐defocusing medium and providing a new approach for possible experimental verification of LBs.     

Green’s function for spinless particle via Parisi-Wu stochastic quantization method

An exact and analytic Green function for a spinless particle in interaction with an electromagnetic plane wave field, expressed in the coordinate gauge is given by Parisi-Wu stochastic quantization method. We separate the classical calculations from those related to the quantum fluctuation term. We have used a perturbative treatment relying on phase and configuration spaces formulation.Received: 27 January 2005, Revised: 3 April 2005, Published online: 8 June 2005PACS: 03.65.Ca, 03.65.Pm, 05.10.Gg     

Bäcklund Transformations,Solitary Waves,Conoid Waves and Bessel Waves of the (2+1)-Dimensional Euler equation

Some simple special Bäcklund transformation theorems are proposed and utilized to obtain exact solutions for the (2+1)-dimensional Euler equation. It is found that the (2+1)-dimensional Euler equation possesses abundant soliton or solitary wave structures, conoid periodic wave structures and the quasi-periodic Bessel wave structures on account of the arbitrary functions in its solutions. Moreover, all solutions of the arbitrary two dimensional nonlinear Poisson equation can be used to construct exact solutions of the (2+1)-dimensional Euler equation.     

Hawking radiation from the with a global monopole via Schwarzschild black hole gravitational anomaly

This paper derives the Hawking flux from the Schwarzschild black hole with a global monopole by using Robinson and Wilczek＇s method. Adopting a dimensional reduction technique, it can describe the effective quantum field in the （3 ＋ 1）-dimensional global monopole background by an infinite collection of the （1 ＋ 1）-dimensional massless fields if neglecting the ingoing modes near the horizon, where the gravitational anomaly can be cancelled by the （1 ＋ 1）- dimensional black body radiation at the Hawking temperature.     

New Periodic Solution to Jacobi Elliptic Functions of a (2+1)-Dimensional BKP Equation and a Generalized Klein-Gordon Equation

With the help of the homogeneous balance method, the Jacobi elliptic expansion method and the auxiliary equation method, the first elliptic function equation is used to obtain the Jacobi doubly periodic wave solutions of the (2+1)-dimensional B-type Kadomtsev-Petviashvili (BKP) equation and the generalized Klein-Gordon equation. The method is also valid for other (1+1)-dimensional and higher dimensional systems.