791 research outputs found
Electrically neutral Dirac particles in the presence of external fields: exact solutions
In the present article we present exact solutions of the Dirac equation for
electric neutral particles with anomalous electric and magnetic moments. Using
the algebraic method of separation of variables, the Dirac equation is
separated in cartesian, cylindrical and spherical coordinates, and exact
solutions are obtained in terms of special functions.Comment: 20pp, IVIC-CFLE-93/02 (this is a version without Tex problems, the
first version was corrupted
A technique to prove parameter-uniform convergence for a singularly perturbed convection–diffusion equation
AbstractA priori parameter explicit bounds on the solution of singularly perturbed elliptic problems of convection–diffusion type are established. Regular exponential boundary layers can appear in the solution. These bounds on the solutions and its derivatives are obtained using a suitable decomposition of the solution into regular and layer components. By introducing extensions of the coefficients to a larger domain, artificial compatibility conditions are not imposed in the derivation of these decompositions
Vacuum effects in an asymptotically uniformly accelerated frame with a constant magnetic field
In the present article we solve the Dirac-Pauli and Klein Gordon equations in
an asymptotically uniformly accelerated frame when a constant magnetic field is
present. We compute, via the Bogoliubov coefficients, the density of scalar and
spin 1/2 particles created. We discuss the role played by the magnetic field
and the thermal character of the spectrum.Comment: 17 pages. RevTe
Investigations of Properties of Powdered Ferromagnetic Sorbents
The paper examines possible application of certain disperse materials based on iron powders as ferromagnetic sorbents for collecting the oil products spilled on the water surface. Sorption ability is defined for the investigated ferromagnetic sorbents
Field induced evolution of regular and random 2D domain structures and shape of isolated domains in LiNbO<sub>3</sub> and LiTaO<sub>3</sub>
The shapes of isolated domains produced by application of the uniform external electric field in different experimental conditions were investigated experimentally in single crystalline lithium niobate LiNbO3 and lithium tantalate LiTaO3. The study of the domain kinetics by computer simulation and experimentally by polarization reversal of the model structure using two-dimensional regular electrode pattern confirms applicability of the kinetic approach to explanation of the experimentally observed evolution of the domain shape and geometry of the domain structure. It has been shown that the fast domain walls strictly oriented along X directions appear after domain merging
Equivalence of the Path Integral for Fermions in Cartesian and Spherical Coordinates
The path-integral calculation for the free energy of a spin-1/2 Dirac-fermion
gas is performed in spherical polar coordinates for a flat spacetime geometry.
Its equivalence with the Cartesian-coordinate representation is explicitly
established. This evaluation involves a relevant limiting case of the fermionic
path integral in a Schwarzschild background, whose near-horizon limit has been
shown to be related to black hole thermodynamics.Comment: 16 page
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