114 research outputs found
On gauge invariant regularization of fermion currents
We compare Schwinger and complex powers methods to construct regularized
fermion currents. We show that although both of them are gauge invariant they
not always yield the same result.Comment: 10 pages, 1 figur
A calculation with a bi-orthogonal wavelet transformation
We explore the use of bi-orthogonal basis for continuous wavelet
transformations, thus relaxing the so-called admissibility condition on the
analyzing wavelet. As an application, we determine the eigenvalues and
corresponding radial eigenfunctions of the Hamiltonian of relativistic
Hydrogen-like atoms.Comment: 18 pages, see instead physics/970300
Width-amplitude relation of Bernstein-Greene-Kruskal solitary waves
Inequality width-amplitude relations for three-dimensional
Bernstein-Greene-Kruskal solitary waves are derived for magnetized plasmas.
Criteria for neglecting effects of nonzero cyclotron radius are obtained. We
emphasize that the form of the solitary potential is not tightly constrained,
and the amplitude and widths of the potential are constrained by inequalities.
The existence of a continuous range of allowed sizes and shapes for these waves
makes them easily accessible. We propose that these solitary waves can be
spontaneously generated in turbulence or thermal fluctuations. We expect that
the high excitation probability of these waves should alter the bulk properties
of the plasma medium such as electrical resistivity and thermal conductivity.Comment: 5 pages, 2 figure
Determinants of Dirac operators with local boundary conditions
We study functional determinants for Dirac operators on manifolds with
boundary. We give, for local boundary conditions, an explicit formula relating
these determinants to the corresponding Green functions. We finally apply this
result to the case of a bidimensional disk under bag-like conditions.Comment: standard LaTeX, 24 pages. To appear in Jour. Math. Phy
Approximate Analytic Solution for the Spatiotemporal Evolution of Wave Packets undergoing Arbitrary Dispersion
We apply expansion methods to obtain an approximate expression in terms of
elementary functions for the space and time dependence of wave packets in a
dispersive medium. The specific application to pulses in a cold plasma is
considered in detail, and the explicit analytic formula that results is
provided. When certain general initial conditions are satisfied, these
expressions describe the packet evolution quite well. We conclude by employing
the method to exhibit aspects of dispersive pulse propagation in a cold plasma,
and suggest how predicted and experimental effects may be compared to improve
the theoretical description of a medium's dispersive properties.Comment: 17 pages, 4 figures, RevTe
On deformation of electron holes in phase space
This Letter shows that for particularly shaped background particle
distributions momentum exchange between phase space holes and the distribution
causes acceleration of the holes along the magnetic field. In the particular
case of a non-symmetric ring distribution (ring with loss cone) this
acceleration is nonuniform in phase space being weaker at larger perpendicular
velocities thus causing deformation of the hole in phase space.Comment: Original MS in EPL style, 1 Figur
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