369 research outputs found
New quantum-mechanical phenomenon in a model of electron-electron interaction in graphene
A quantum mechanical model of two interacting electrons in graphene is
considered. We concentrate on the case of zero total momentum of the pair. We
show that the dynamics of the system is very unusual. Both stationary and
time-dependent problems are considered. It is shown that the complete set of
the wave functions with definite energy includes the new functions, previously
overlooked. The time evolution of the wave packet, corresponding to the
scattering problem setup, leads to the appearance of the localized state at
large time. The asymptotics of this state is found analytically. We obtain the
lower bound of the life time of this state, which is connected with the
breakdown of the continuous model on the lattice scale. The estimate of this
bound gives one a hope to observe the localized states in the experiment.Comment: 10 pages, 2 figure
Social technology management in the service of the state to fight corruption and incompetence of civil servants
В данном докладе рассмотрены проблемы коррупции, взяточничества, казнокрадства, некомпетентности госслужащих, и предложено решение данной проблемы, основанное на применении социальных технологий преобразования и развития общественных систем.This report describes the problems of corruption, bribery, embezzlement, incompetence, civil servants, and proposed a solution to this problem, based on the use of social technologies of transformation and development of social systems
Coulomb corrections to the Delbrueck scattering amplitude at low energies
In this article, we study the Coulomb corrections to the Delbrueck scattering
amplitude. We consider the limit when the energy of the photon is much less
than the electron mass. The calculations are carried out in the coordinate
representation using the exact relativistic Green function of an electron in a
Coulomb field. The resulting relative corrections are of the order of a few
percent for scattering on for a large charge of the nucleus. We compare the
corrections with the corresponding ones calculated through the dispersion
integral of the pair production cross section and also with the magnetic loop
contribution to the g-factor of a bound electron. The last one is in a good
agreement with our results but the corrections calculated through the
dispersion relation are not.Comment: 8 pages, 6 figure
Induced current in the presence of magnetic flux tube of small radius
The induced current density, corresponding to the massless Dirac equation in
(2+1) dimensions in a magnetic flux tube of small radius is considered. This
problem is important for graphene. In the case, when an electron can not
penetrate the region of nonzero magnetic field, this current is the odd
periodical function of the magnetic flux. If the region inside the magnetic
tube is not forbidden for penetration of electron, the induced current is not a
periodical function of the magnetic flux. However in the limit , where
is the radius of magnetic flux tube, this function has the universal form
which is independent of the magnetic field distribution inside the magnetic
tube at fixed value of the magnetic flux.Comment: 5 pages, 1 figur
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