48 research outputs found
Dirac-Kahler Theory and Massless Fields
Three massless limits of the Dirac-Kahler theory are considered.
It is shown that the Dirac-Kahler equation for massive particles can be
represented as a result of the gauge-invariant mixture (topological
interaction) of the above massless fields.Comment: 10 pages, to appear in Proceedings of International conference in
honor of Ya. B. Zeldovich 95th Anniversary, April 20-23, 2009, Minsk, Belaru
Electron-positron annihilation into Dirac magnetic monopole and antimonopole: the string ambiguity and the discrete symmetries
We address the problem of string arbitrariness in the quantum field theory of
Dirac magnetic monopoles. Different prescriptions are shown to yield different
physical results. The constraints due to the discrete symmetries (C and P) are
derived for the process of electron- positron annihilation into the
monopole-antimonopole pair. In the case of the annihilation through the
one-photon channel, the production of spin 0 monopoles is absolutely forbidden;
spin 1/2 monopole and antimonopole should have the same helicities (or,
equivalently, the monopole-antimonopole state should be p-wave ).Comment: 14 pages, revtex, 3 figure
Quantum state of a free spin-1/2 particle and the inextricable dependence of spin and momentum under Lorentz transformations
We revise the Dirac equation for a free particle and investigate Lorentz
transformations on spinors. We study how the spin quantization axis changes
under Lorentz transformations, and evince the interplay between spin and
momentum in this context.Comment: 14 pages, 3 figures, published as a Review in the IJQ
On non-Adiabatic Holonomoic Quantum Computer
Non-adiabatic non-Abelian geometric phase of spin-3/2 system in the rotating
magnetic field is considered. Explicit expression for the corresponding
effective non-Abelian gauge potential is obtained. This formula can be used for
construction of quantum gates in quantum computations.Comment: 6 page
Massive Electrodynamics and the Magnetic Monopoles
We investigate in detail the problem of constructing magnetic monopole
solutions within the finite-range electrodynamics (i.e., electrodynamics with
non-zero photon mass, which is the simplest extension of the standard theory;
it is fully compatible with the experiment). We first analyze the classical
electrodynamics with the additional terms describing the photon mass and the
magnetic charge; then we look for a solution analogous to the Dirac monopole
solution. Next, we plug the found solution into the Schr\"{o}dinger equation
describing the interaction between the the magnetic charge and the electron.
After that, we try to derive the Dirac quantization condition for our case.
Since gauge invariance is lost in massive electrodynamics, we use the method of
angular momentum algebra. Under rather general assumptions we prove the theorem
that the construction of such an algebra is not possible and therefore the
quantization condition cannot be derived. This points to the conclusion that
the Dirac monopole and the finite photon mass cannot coexist within one and the
same theory. Some physical consequences of this conclusion are considered. The
case of t'Hooft-Polyakov monopole is touched upon briefly.Comment: 24 pages, revtex, 1 figure appended as a PostScript fil