983 research outputs found
Total-field absorbing boundary conditions for the time-domain electromagnetic field equations
Magnetic scattering of Dirac fermions in topological insulators and graphene
We study quantum transport and scattering of massless Dirac fermions by
spatially localized static magnetic fields. The employed model describes in a
unified manner the effects of orbital magnetic fields, Zeeman and exchange
fields in topological insulators, and the pseudo-magnetic fields caused by
strain or defects in monolayer graphene. The general scattering theory is
formulated, and for radially symmetric fields, the scattering amplitude and the
total and transport cross sections are expressed in terms of phase shifts. As
applications, we study ring-shaped magnetic fields (including the Aharanov-Bohm
geometry) and scattering by magnetic dipoles.Comment: 11 pages, 4 figure
Compatibility relations and the finite-element formulation of electromagnetic field problems
Three fully polarized fermions close to a p-wave Feshbach resonance
We study the three-body problem for three atomic fermions, in the same spin
state, experiencing a resonant interaction in the p-wave channel via a Feshbach
resonance represented by a two-channel model. The rate of inelastic processes
due to recombination to deeply bound dimers is then estimated from the
three-body solution using a simple prescription. We obtain numerical and
analytical predictions for most of the experimentally relevant quantities that
can be extracted from the three-body solution: the existence of weakly bound
trimers and their lifetime, the low-energy elastic and inelastic scattering
properties of an atom on a weakly bound dimer (including the atom-dimer
scattering length and scattering volume), and the recombination rates for three
colliding atoms towards weakly bound and deeply bound dimers. The effect of
"background" non-resonant interactions in the open channel of the two-channel
model is also calculated and allows to determine which three-body quantities
are `universal' and which on the contrary depend on the details of the model.Comment: 31 pages, 12 figure
The quasiclassical theory of the Dirac equation with a scalar-vector interaction and its applications in the theory of heavy-light mesons
We construct a relativistic potential quark model of , , , and
mesons in which the light quark motion is described by the Dirac equation
with a scalar-vector interaction and the heavy quark is considered a local
source of the gluon field. The effective interquark interaction is described by
a combination of the perturbative one-gluon exchange potential
and the long-range Lorentz-scalar and
Lorentz-vector linear potentials and , where
. Within the quasiclassical approximation, we obtain
simple asymptotic formulas for the energy and mass spectra and for the mean
radii of , , , and mesons, which ensure a high accuracy of
calculations even for states with the radial quantum number . We
show that the fine structure of P-wave states in heavy-light mesons is
primarily sensitive to the choice of two parameters: the strong-coupling
constant and the coefficient of mixing of the long-range
scalar and vector potentials and .
The quasiclassical formulas for asymptotic coefficients of wave function at
zero and infinity are obtained.Comment: 22 pages, 6 figure
Finite formulation and domain-integrated field relations in electromagnetics - a synthesis
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