26 research outputs found
Massless fields over space-time and coherent states for the Lorentz group
The solutions of the arbitrary-spin massless wave equations over space are obtained using the generalized coherent states for the
Lorentz group. The use of these solutions for the construction of invariant
propagators of quantized massless fields with an arbitrary spin over the space is considered. The expression for the scalar propagator
is obtained in the explicit form.Comment: 6 pages, LATEX, no figures. To appear in Modern Phys. Lett.
The Newman-Janis Algorithm, Rotating Solutions and Einstein-Born-Infeld Black Holes
A new metric is obtained by applying a complex coordinate trans- formation to
the static metric of the self-gravitating Born-Infeld monopole. The behaviour
of the new metric is typical of a rotating charged source, but this source is
not a spherically symmetric Born-Infeld monopole with rotation. We show that
the structure of the energy-momentum tensor obtained with this new metric does
not correspond to the typical structure of the energy momentum tensor of
Einstein-Born-Infeld theory induced by a rotating spherically symmetric source.
This also show, that the complex coordinate transformations have the
interpretation given by Newman and Janis only in space-time solutions with
linear sources
On Tamm's problem in the Vavilov-Cherenkov radiation theory
We analyse the well-known Tamm problem treating the charge motion on a finite
space interval with the velocity exceeding light velocity in medium. By
comparing Tamm's formulae with the exact ones we prove that former do not
properly describe Cherenkov radiation terms. We also investigate Tamm's formula
cos(theta)=1/(beta n) defining the position of maximum of the field strengths
Fourier components for the infinite uniform motion of a charge. Numerical
analysis of the Fourier components of field strengths shows that they have a
pronounced maximum at cos(theta)=1/(beta n) only for the charge motion on the
infinitely small interval. As the latter grows, many maxima appear. For the
charge motion on an infinite interval there is infinite number of maxima of the
same amplitude. The quantum analysis of Tamm's formula leads to the same
results.Comment: 28 pages, 8 figures, to be published in J.Phys.D:Appl.Phy