13 research outputs found
Aharonov-Bohm scattering of charged particles and neutral atoms: the role of absorption
The Aharonov-Bohm scattering of charged particles by the magnetic field of an
infinitely long and infinitely thin solenoid (magnetic string) in an absorbing
medium is studied. We discuss the partial-wave approach to this problem and
show that standard partial-wave method can be adjusted to this case. The effect
of absorption leads to oscillations of the AB cross section.
Based on this we investigate the scattering of neutral atoms with induced
electric dipole moments by a charge wire of finite radius which is placed in an
uniform magnetic field. The physical realistic and practically important case
that all atoms which collide with the wire are totally absorbed at its surface,
is studied in detail. The dominating terms of the scattering amplitude are
evaluated analytically for different physical constellations. The rest terms
are written in a form suitable for a numerical computation. We show that if the
magnetic field is absent, the absorbing charged wire causes oscillations of the
cross section. In the presence of the magnetic field the cross section
increases and the dominating Aharonov--Bohm peak appears in the forward
direction, suppressing the oscillations.Comment: 15 pages, LaTeXfile, 2 figure
Electron-positron pair production in the Aharonov-Bohm potential
In the framework of QED we evaluate the cross section for electron-positron
pair production by a single photon in the presence of the external
Aharonov-Bohm potential in first order of perturbation theory. We analyse
energy, angular and polarization distributions at different energy regimes:
near the threshold and at high photon energies.Comment: LaTeX file, 13 page
Perturbative Study of Bremsstrahlung and Pair-Production by Spin-1/2 Particles in the Aharonov-Bohm Potential
In the presence of an external Aharonov-Bohm potential, we investigate the
two QED processes of the emission of a bremsstrahlung photon by an electron,
and the production of an electron-positron pair by a single photon.
Calculations are carried out using the Born approximation within the framework
of covariant perturbation theory to lowest non-vanishing order in \alpha. The
matrix element for each process is derived, and the corresponding differential
cross-section is calculated. In the non-relativistic limit, the resulting
angular and spectral distributions and some polarization properties are
considered, and compared to results of previous works.Comment: 15 pages, RevTex 4, 2 figures, submitted for publicatio
A pragmatic approach to the problem of the self-adjoint extension of Hamilton operators with the Aharonov-Bohm potential
We consider the problem of self-adjoint extension of Hamilton operators for
charged quantum particles in the pure Aharonov-Bohm potential (infinitely thin
solenoid). We present a pragmatic approach to the problem based on the
orthogonalization of the radial solutions for different quantum numbers. Then
we discuss a model of a scalar particle with a magnetic moment which allows to
explain why the self-adjoint extension contains arbitrary parameters and give a
physical interpretation.Comment: 8 pages, LaTeX, to appear in J. Phys.
Scattering of scalar and Dirac particles by a magnetic tube of finite radius
We consider the Dirac equation in cylindrically symmetric magnetic fields and
find its normal modes as eigenfunctions of a complete set of commuting
operators. This set consists of the Dirac operator itself, the -components
of the linear and the total angular momenta, and of one of the possible spin
polarization operators. The spin structure of the solution is completely fixed
independently of the radial distribution of the magnetic field which influences
only the radial modes. We solve explicitly the radial equations for the uniform
magnetic field inside a solenoid of a finite radius and consider in detail the
scattering of scalar and Dirac particles in this field. For particles with low
energy the scattering cross section coincides with the Aharonov-Bohm scattering
cross section. We work out the first order corrections to this result caused by
the fact that the solenoid radius is finite. At high energies we obtain the
classical result for the scattering cross section.Comment: LaTeX file, 17 page
Scalar Pair Production in the Aharonov-Bohm Potential
In the framework of QED, scalar pair production by a single linearly
polarized high-energy photon in the presence of an external Aharonov-Bohm
potential is investigated. The exact scattering solutions of the Klein-Gordon
equation in cylindrically symmetric field are constructed and used to write the
first order transition amplitude. The matrix elements and the corresponding
differential scattering cross-section are calculated. The pair production at
both the nonrelativistic and the ultrarelativistic limits is discussed.Comment: 13 pages, 1 figur
Bremsstrahlung in the gravitational field of a cosmic string
In the framework of QED we investigate the bremsstrahlung process for an
electron passing by a straight static cosmic string. This process is precluded
in empty Minkowski space-time by energy and momentum conservation laws. It
happens in the presence of the cosmic string as a consequence of the conical
structure of space, in spite of the flatness of the metric. The cross section
and emitted electromagnetic energy are computed and analytic expressions are
found for different energies of the incoming electron. The energy interval is
divided in three parts depending on whether the energy is just above electron
rest mass , much larger than , or exceeds , with the
string mass per unit length in Planck units. We compare our results with those
of scalar QED and classical electrodynamics and also with conic pair production
process computed earlier.Comment: 21 pages, to appear in Phys. Rev. D., KONS-RGKU-94-0