Symmetries of massless Dirac equations and supersymmetric quantum mechanics

It is shown how symmetries of Dirac equations can be used to obtain constants of motion for nonrelativistic supersymmetric quantum Hamiltonians. In particular, conserved supercharges are found for a spin-1/2 particle in the field of a dyon which yield under anticommutation the generalized Runge-Lenz symmetry of the system.This work is supported in part through funds provided by the Natural Sciences and Engineering Research Council (NSERC) of Canada and the Fonds FCAR of the Quebec Ministry of Education.     

A relationship between the Dirac and Maxwell equations

It is shown that an analogue of Dirac's equation may be constructed from Milner's extension of Maxwell's equations and a comparison of the algebraic and physical features of the equations made.     

Dirac and Maxwell equations in the Clifford and spin-Clifford bundles

We show how to write the Dirac and the generalized Maxwell equations (including monopoles) in the Clifford and spin-Clifford bundles (of differential forms) over space-time (either of signaturep=1,q=3 orp=3,q=1). In our approach Dirac and Maxwell fields are represented by objects of the same mathematical nature and the Dirac and Maxwell equations can then be directly compared. We show also that all presentations of the Maxwell equations in (matrix) Dirac-like spinor form appearing in the literature can be obtained by choosing particular global idempotents in the bundles referred to above. We investigate also the transformation laws under the action of the Lorentz group of Dirac and Maxwell fields (defined as algebraic spinor sections of the Clifford or spin-Clifford bundles), clearing up several misunderstandings and misconceptions found in the literature. Among the many new results, we exhibit a factorization of the Maxwell field into two-component spinor fields (Weyl spinors), which is important.     

Higher dimensional supersymmetric quantum mechanics and Dirac equation

We exhibit the supersymmetric quantum mechanical structure of the full 3+1 dimensional Dirac equation considering ‘mass’ as a function of coordinates. Its usefulness in solving potential problems is discussed with specific examples. We also discuss the ‘physical’ significance of the supersymmetric states in this formalism.     

Generalized maxwell equations and quantum mechanics. I. Dirac equation for the free electron

Some preliminary results presented in two previous papers are expanded upon. In the first it was shown that the Maxwell equations are equivalent to a nonlinear Dirac-like spinor equation. In the present paper it is shown that, in that formalism, the Dirac equation for the free electron is susceptible to a puzzling reinterpretation. In fact, it is shown that the Dirac equation is equivalent to the Maxwell equations for an electromagnetic field generated by two currents: one electric in nature and one, magnetic-monopolar. The elaboration of this result brings a nonlinear generalization of Maxwell's equations, as well as a nonlinear Dirac-like equation fully equivalent to them, from which both the electron mass as well as the magnetic monopole mass appear to be fully electromagnetic in nature, and the magnetic monopole to be tachyonic. The corresponding nonlinear Dirac equation reduces, under suitable approximations, to the ordinary Dirac equation for the free electron.     

Derivation of quantum Maxwell equations from relativistic particle Hamiltonian

Given the Hamiltonian forN relativistic particles with charges and intrinsic magnetic moments interacting via pair potentials and self-interactions, we derive not only the particle equations, but also the full set of Maxwell's equations, thereby testing the consistency of particle equations, currents, and field equations in the Heisenberg picture.     

Entropy,information and Maxwell’s demon after quantum mechanics

The problem of the subjective nature of entropy and its relation to information and irreversibility is examined in the light of the quantum measurement problem. The main thesis of the paper is that state collapse during a measurement and hence entropy increase in the observed universe is seen by observers who are only able to observe a restricted manifold of states determined by their concepts, language, etc., in short by their level of perception. The thesis leads to the assertion that any universe with a structure must evolve.     

用光晶格模拟狄拉克、外尔和麦克斯韦方程

相对论性量子力学波动方程,如狄拉克、外尔和麦克斯韦方程,是描述微观粒子运动的基石.最近的实验和理论研究表明,冷原子系统中几乎所有参数都可精确调控,因此冷原子系统被认为是实现量子模拟的理想平台,可以用来研究高能和凝聚态物理中的一些基本问题.本文介绍了设计原子光晶格哈密顿量的思路和方法,主要涉及激光辅助跳跃的理论.基于这些方法,物理学界提出了利用光晶格体系模拟相对论性量子力学波动方程,包括狄拉克、外尔和麦克斯韦方程等,并且预言了一些在基本粒子物理中很难观察到,但在冷原子体系可能观察到的物理现象.本文综述了国际上此领域的研究进展.     

Spin-flavor oscillations of Dirac neutrinos described by relativistic quantum mechanics

Spin-flavor oscillations of Dirac neutrinos in matter and a magnetic field are studied using the method of relativistic quantum mechanics. Using the exact solution of the wave equation for a massive neutrino, taking into account external fields, the effective Hamiltonian governing neutrino spin-flavor oscillations is derived. Then the The consistency of our approach with the commonly used quantum mechanical method is demonstrated. The obtained correction to the usual effective Hamiltonian results in the appearance of the new resonance in neutrino oscillations. Applications to spin-flavor neutrino oscillations in an expanding envelope of a supernova are discussed. In particular, transitions between right-polarized electron neutrinos and additional sterile neutrinos are studied for realistic background matter and magnetic field distributions. The influence of other factors such as the longitudinal magnetic field, the matter polarization, and the non-standard contributions to the neutrino effective potential, is also analyzed.     

Solutions of Klein-Gordon and Dirac equations on quantum Minkowski spaces

Covariant differential calculi and exterior algebras on quantum homogeneous spaces endowed with the action of inhomogeneous quantum groups are classified. In the case of quantum Minkowski spaces they have the same dimensions as in the classical case. Formal solutions of the corresponding Klein-Gordon and Dirac equations are found. The Fock space construction is sketched.This research was supported in part by NSF grant DMS-9508597 and in part by Polish KBN grant No. 2 P301 02007.     

Extension of PT-symmetric quantum mechanics to the Dirac theory with position-dependent mass

We present a new method to construct the exactly solvable PT-symmetric potentials within the framework of the position-dependent effective mass Dirac equation with the vector potential coupling scheme in 1 + 1 dimensions. In order to illustrate the procedure, we produce three PT-symmetric potentials as examples, which are PT-symmetric harmonic oscillator-like potential, PT-symmetric potential with the form of a linear potential plus an inversely linear potential, and PT-symmetric kink-like potential, respectively. The real relativistic energy levels and corresponding spinor components for the bound states are obtained by using the basic concepts of the supersymmetric quantum mechanics formalism and function analysis method.     

A simple efficient methodology for Dirac equation in minimal length quantum mechanics

We solve the modified Dirac equation by adding a harmonic oscillator potential and implementing the Nikiforov–Uvarov technique. The closed forms of solutions are reported in a quite simple and systematic manner.     

On the equations of state in quantum statistical mechanics

By extending methods previously used to study the equations of state at low temperature, it is shown that the entropy density and the statistical average of a conserved, non-spontaneously violated, charge density can be expanded in terms of integrals over products of many body n-point amplitudes defined for real, continuous frequencies. The general structure of the expansions is described, and it is demonstrated that essentially the same spectral function determines the entropy density and the average charge densities. Certain classes of terms are worked out in detail, and the formal sum of one such class is shown to provide the contributions to the equations of state arising from composite quasiparticles associated with the poles of the n-point amplitudes. [Another term, discussed in many previous works, involves the logarithms of the elementary propagators and yields the contributions to the equations of state coming from elementary quasiparticles.]The Appendices include an extensive study of the analytic properties of many body amplitudes in the frequencies of the external and internal lines. Specialized to zero temperature, these considerations apply to the Feynman diagrams for elementary particle amplitudes.     

On a relation between Maxwell and Dirac theories

It is shown that the Dirac equation can be written in a form similar to Maxwell equations, where the Maxwell tensor is written as a bilinear expression of the Dirac field and the current is a simple function of the external potential and the Dirac field. Similarly, the Maxwell equations can be written as a self-coupled Dirac equation where the potential is a simple function of the Dirac field itself. It is illustrated by examples how the new formalism helps to find solutions of the coupled field equations.