373 research outputs found
Bound states of scalar particles in the presence of a short range potential
We analyze the behavior of the energy spectrum of the Klein-Gordon equation
in the presence of a truncated hyperbolic tangent potential. From our analysis
we obtain that, for some values of the potential there is embedding of the
bound states into the negative energy continuum, showing that, in opposition to
the general belief, relativistic scalar particles in one-dimensional short
range potentials can exhibit resonant behavior and not only the Schiff-Snyder
effect.Comment: To appear in Modern Physics Letters
English → Russian MT evaluation campaign
This paper presents the settings and the result of the ROMIP 2013 MT shared task for the English→Russian language direction. The quality of generated translations was assessed using automatic metrics and human evaluation. We also discuss ways to reduce human evaluation efforts using pairwise sentence comparisons by human judges to simulate sort operations
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
Planar Dirac Electron in Coulomb and Magnetic Fields
The Dirac equation for an electron in two spatial dimensions in the Coulomb
and homogeneous magnetic fields is discussed. For weak magnetic fields, the
approximate energy values are obtained by semiclassical method. In the case
with strong magnetic fields, we present the exact recursion relations that
determine the coefficients of the series expansion of wave functions, the
possible energies and the magnetic fields. It is found that analytic solutions
are possible for a denumerably infinite set of magnetic field strengths. This
system thus furnishes an example of the so-called quasi-exactly solvable
models. A distinctive feature in the Dirac case is that, depending on the
strength of the Coulomb field, not all total angular momentum quantum number
allow exact solutions with wavefunctions in reasonable polynomial forms.
Solutions in the nonrelativistic limit with both attractive and repulsive
Coulomb fields are briefly discussed by means of the method of factorization.Comment: 18 pages, RevTex, no figure
Spectrum of the Relativistic Particles in Various Potentials
We extend the notion of Dirac oscillator in two dimensions, to construct a
set of potentials. These potentials becomes exactly and quasi-exactly solvable
potentials of non-relativistic quantum mechanics when they are transformed into
a Schr\"{o}dinger-like equation. For the exactly solvable potentials,
eigenvalues are calculated and eigenfunctions are given by confluent
hypergeometric functions. It is shown that, our formulation also leads to the
study of those potentials in the framework of the supersymmetric quantum
mechanics
ROMIP MT Evaluatio n Track 2013: Organizer s’ Report
The paper presents the settings and the results of the ROMIP 2013 machine translation evaluation campaign for the English-to-Russian language pair. The quality of generated translations was assessed using automatic metrics and human evaluation. We also demonstrate the usefulness of a dynamic mechanism for human evaluation based on pairwise segment comparison
1-Methylamino-3-(2,4,6-trimethylphenyl)propan-2-ol
The methylaminopropyl chain in the title compound, C13H21NO, adopts an extended zigzag conformation and the N atom shows a trigonal coordination. The N atom acts as hydrogen-bond acceptor to the hydroxy group of an adjacent molecule, generating a helical chain running along the b axis. The amino H atom is not involved in hydrogen bonding
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