144 research outputs found
Induced quantum numbers of a magnetic monopole at finite temperature
A Dirac electron field is quantized in the background of a Dirac magnetic
monopole, and the phenomenon of induced quantum numbers in this system is
analyzed. We show that, in addition to electric charge, also squares of orbital
angular momentum, spin, and total angular momentum are induced. The functional
dependence of these quantities on the temperature and the CP-violating vacuum
angle is determined. Thermal quadratic fluctuations of charge and squared total
angular momentum, as well as the correlation between them and their
correlations with squared orbital angular momentum and squared spin, are
examined. We find the conditions when charge and squared total angular momentum
at zero temperature are sharp quantum observables rather than mere quantum
averages.Comment: 24 pages, minor grammatical changes, journal versio
Influence of quantized massive matter fields on the Casimir effect
Charged massive matter fields of spin 0 and 1/2 are quantized in the presence
of an external uniform magnetic field in a spatial region bounded by two
parallel plates. The most general set of boundary conditions at the plates,
that is required by mathematical consistency and the self-adjointness of the
Hamiltonian operator, is employed. The vacuum fluctuations of the matter field
in the case of the magnetic field orthogonal to the plates are analyzed, and it
is shown that the pressure from the vacuum onto the plates is positive and
independent of the boundary condition, as well as of the distance between the
plates. Possibilities of the detection of this new-type Casimir effect are
discussed.Comment: 14 pages, constants and are recovered in formula (40).
arXiv admin note: text overlap with arXiv:1411.246
Diffraction and quasiclassical limit of the Aharonov--Bohm effect
Since the Aharonov-Bohm effect is the purely quantum effect that has no
analogues in classical physics, its persistence in the quasiclassical limit
seems to be hardly possible. Nevertheless, we show that the scattering
Aharonov-Bohm effect does persist in the quasiclassical limit owing to the
diffraction, i.e. the Fraunhofer diffraction in the case when space outside the
enclosed magnetic flux is Euclidean, and the Fresnel diffraction in the case
when the outer space is conical. Hence, the enclosed magnetic flux can serve as
a gate for the propagation of short-wavelength, almost classical, particles. In
the case of conical space, this quasiclassical effect which is in principle
detectable depends on the particle spin.Comment: 12 pages, minor changes, references update
Vacuum energy induced by an impenetrable flux tube of finite radius
We consider the effect of the magnetic field background in the form of a tube
of the finite transverse size on the vacuum of the quantized charged massive
scalar field which is subject to the Dirichlet boundary condition at the edge
of the tube. The vacuum energy is induced, being periodic in the value of the
magnetic flux enclosed in the tube. Our previous study in J. Phys. A: Vol.43,
175401 (2010) is extended to the case of smaller radius of the tube and larger
distances from it. The dependence of the vacuum energy density on the distance
from the tube and on the coupling to the space-time curvature scalar is
comprehensively analyzed.Comment: 11 pages, 8 figures, journal version, abstract extended. arXiv admin
note: substantial text overlap with arXiv:0911.287
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