728 research outputs found
Stationary States in Bistable System Driven by L\'evy Noise
We study the properties of the probability density function (PDF) of a
bistable system driven by heavy tailed white symmetric L\'evy noise. The shape
of the stationary PDF is found analytically for the particular case of the
L\'evy index \alpha = 1 (Cauchy noise). For an arbitrary L\'evy index we employ
numerical methods based on the solution of the stochastic Langevin equation and
space fractional kinetic equation. In contrast with the bistable system driven
by Gaussian noise, in the L\'evy case the positions of maxima of the stationary
PDF do not coincide with the positions of minima of the bistable potential. We
provide a detailed study of the distance between the maxima and the minima as a
function of the potential's depth and L\'evy noise parameters.Comment: Accepted to EPJS
Vibronic interaction as main reason of magnetic ordering in insulating manganites R 1-x A x MnO 3
The model of orbitally dependent magnetic structure of charge ordered insulated manganites is proposed. The model is semi-phenomenological. It allows using a few parameters to describe possible magnetic structures of compounds. The experimental crystal structure of compounds also could be taken into account. The compounds LaMnO 3 , La 1/2 Ca 1/2 MnO 3 , La 1/3 Ca 2/3 MnO 3 , BiMnO 3 are considered. © 2018 The Authors, published by EDP Sciences
Overinterpolation
In this paper we study the consequences of overinterpolation, i.e., the
situation when a function can be interpolated by polynomial, or rational, or
algebraic functions in more points that normally expected. We show that in many
cases such a function has specific forms.Comment: 14 page
Crucial role of orbital structure in formation of frustrated magnetic structure in BiMnO3
The paper presents an investigation in the field of orbital physics of strongly correlated oxides. The theoretical study of vibronic mechanism of orbital and magnetic structures forming in BiMnO3 crystal is carried out. An effect of orbital structure upon superexchange interaction is described. Nonlinear and second-neighbor terms in vibronic interaction on manganese ions play an important role in magnetic ordering of frustrated BiMnO3. It is shown that the linear vibronic interaction is insufficient to describe the experimentally detected ferromagnetic structure of bismuth manganite. The new approach to orbital structure formation, presented in the paper, could be used not only in manganite physics but also in other Jahn-Teller compounds. © 2013 American Physical Society
Mixing of fermion fields of opposite parities and baryon resonances
We consider a loop mixing of two fermion fields of opposite parities whereas
the parity is conserved in a Lagrangian. Such kind of mixing is specific for
fermions and has no analogy in boson case. Possible applications of this effect
may be related with physics of baryon resonances. The obtained matrix
propagator defines a pair of unitary partial amplitudes which describe the
production of resonances of spin and different parity or
. The use of our amplitudes for joint description of
partial waves and shows that the discussed effect is clearly
seen in these partial waves as the specific form of interference between
resonance and background. Another interesting application of this effect may be
a pair of partial waves and where the picture is more
complicated due to presence of several resonance states.Comment: 22 pages, 6 figures, more detailed comparison with \pi N PW
Meromorphic Approximants to Complex Cauchy Transforms with Polar Singularities
We study AAK-type meromorphic approximants to functions , where is a
sum of a rational function and a Cauchy transform of a complex measure
with compact regular support included in , whose argument has
bounded variation on the support. The approximation is understood in -norm
of the unit circle, . We obtain that the counting measures of poles of
the approximants converge to the Green equilibrium distribution on the support
of relative to the unit disk, that the approximants themselves
converge in capacity to , and that the poles of attract at least as many
poles of the approximants as their multiplicity and not much more.Comment: 39 pages, 4 figure
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