264 research outputs found
Hamiltonian anomalies of bound states in QED
The Bound State in QED is described in systematic way by means of nonlocal
irreducible representations of the nonhomogeneous Poincare group and Dirac's
method of quantization. As an example of application of this method we
calculate triangle diagram . We show that
the Hamiltonian approach to Bound State in QED leads to anomaly-type
contribution to creation of pair of parapositronium by two photon.Comment: 12 pages, 2 figures. Proceedings of the conference "Symmetry Methods
in Physics XV", July 12-16, 2011, Dubna, Russi
Monopole Vacuum in Non-Abelian Theories
It is shown that, in the theory of interacting Yang -Mills fields and a Higgs
field, there is a topological degeneracy of Bogomol'nyi-Prasad-Sommerfield
(BPS) monopoles and that there arises, in this case, a chromoelectric monopole
characterized by a new topological variable that describes transitions between
topological states of the monopole in the Minkowski space (in just the same way
as an instanton describes such transitions in the Euclidean space). The limit
of an infinitely large mass of the Higgs field at a finite density of the BPS
monopole is considered as a model of the stable vacuum in the pure Yang-Mills
theory. It is shown that, in QCD, such a monopole vacuum may lead to a rising
potential, a topological confinement and an additional mass of the
meson. The relationship between the result obtained here for the generating
functional of perturbation theory and Faddeev-Popov integral is discussed
The kinetic description of vacuum particle creation in the oscillator representation
The oscillator representation is used for the non-perturbative description of
vacuum particle creation in a strong time-dependent electric field in the
framework of scalar QED. It is shown that the method can be more effective for
the derivation of the quantum kinetic equation (KE) in comparison with the
Bogoliubov method of time-dependent canonical transformations. This KE is used
for the investigation of vacuum creation in periodical linear and circular
polarized electric fields and also in the case of the presence of a constant
magnetic field, including the back reaction problem. In particular, these
examples are applied for a model illustration of some features of vacuum
creation of electron-positron plasma within the planned experiments on the
X-ray free electron lasers.Comment: 17 pages, 3 figures, v2: a reference added; some changes in tex
Schwinger Pair Production at Finite Temperature in Scalar QED
In scalar QED we study the Schwinger pair production from an initial ensemble
of charged bosons when an electric field is turned on for a finite period
together with or without a constant magnetic field. The scalar QED Hamiltonian
depends on time through the electric field, which causes the initial ensemble
of bosons to evolve out of equilibrium. Using the Liouville-von Neumann method
for the density operator and quantum states for each momentum mode, we
calculate the Schwinger pair-production rate at finite temperature, which is
the pair-production rate from the vacuum times a thermal factor of the
Bose-Einstein distribution.Comment: RevTex 10 pages, no figure; replaced by the version accepted in Phys.
Rev. D; references correcte
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