170 research outputs found
Distributed Order Derivatives and Relaxation Patterns
We consider equations of the form , ,
where , is a distributed order derivative, that is the
Caputo-Dzhrbashyan fractional derivative of order , integrated in
with respect to a positive measure . Such equations are
used for modeling anomalous, non-exponential relaxation processes. In this work
we study asymptotic behavior of solutions of the above equation, depending on
properties of the measure
Levy stable distributions via associated integral transform
We present a method of generation of exact and explicit forms of one-sided,
heavy-tailed Levy stable probability distributions g_{\alpha}(x), 0 \leq x <
\infty, 0 < \alpha < 1. We demonstrate that the knowledge of one such a
distribution g_{\alpha}(x) suffices to obtain exactly g_{\alpha^{p}}(x), p=2,
3,... Similarly, from known g_{\alpha}(x) and g_{\beta}(x), 0 < \alpha, \beta <
1, we obtain g_{\alpha \beta}(x). The method is based on the construction of
the integral operator, called Levy transform, which implements the above
operations. For \alpha rational, \alpha = l/k with l < k, we reproduce in this
manner many of the recently obtained exact results for g_{l/k}(x). This
approach can be also recast as an application of the Efros theorem for
generalized Laplace convolutions. It relies solely on efficient definite
integration.Comment: 12 pages, typos removed, references adde
Self-adjoint extensions and spectral analysis in Calogero problem
In this paper, we present a mathematically rigorous quantum-mechanical
treatment of a one-dimensional motion of a particle in the Calogero potential
. Although the problem is quite old and well-studied, we believe
that our consideration, based on a uniform approach to constructing a correct
quantum-mechanical description for systems with singular potentials and/or
boundaries, proposed in our previous works, adds some new points to its
solution. To demonstrate that a consideration of the Calogero problem requires
mathematical accuracy, we discuss some "paradoxes" inherent in the "naive"
quantum-mechanical treatment. We study all possible self-adjoint operators
(self-adjoint Hamiltonians) associated with a formal differential expression
for the Calogero Hamiltonian. In addition, we discuss a spontaneous
scale-symmetry breaking associated with self-adjoint extensions. A complete
spectral analysis of all self-adjoint Hamiltonians is presented.Comment: 39 page
A Cauchy-type problem for the diffusion-wave equation with Riemann-Liouville partial derivative
Multi-dimensional trio coherent states
We introduce a novel class of higher-order, three-mode states called
K-dimensional trio coherent states. We study their mathematical properties and
prove that they form a complete set in a truncated Fock space. We also study
their physical content by explicitly showing that they exhibit nonclassical
features such as oscillatory number distribution, sub-poissonian statistics,
Cauchy-Schwarz inequality violation and phase-space quantum interferences.
Finally, we propose an experimental scheme to realize the state with K=2 in the
quantized vibronic motion of a trapped ion.Comment: 17 pages, 12 figures, accepted for publication in J. Phys. A: Math.
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Thermally stressed state of a semiinfinite plate caused by a heat source moving with variable velocity
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