471 research outputs found
The comparative analysis of master’s degree curriculums in the majorof “Electronics and nanoelectronics” in TPU (Russia) and “Solid state systems” in Czech Technical University (Prague)
Semiclassical approach to the nonlocal nonlinear Schr\"{o}dinger equation with a non-Hermitian term
The nonlinear Sch\"{o}dinger equation (NLSE) with a non-Hermitian term is the
model for various phenomena in nonlinear open quantum systems. We deal with the
Cauchy problem for the nonlocal generalization of multidimensional NLSE with a
non-Hermitian term. Using the ideas of the Maslov method, we propose the method
of constructing asymptotic solutions to this equation within the framework of
semiclassically concentrated states. The semiclassical nonlinear evolution
operator and symmetry operators for the leading term of asymptotics are
derived. Our approach is based on the solutions of the auxiliary dynamical
system that effectively linearize the problem under certain algebraic
conditions. The formalism proposed is illustrated with the specific example of
the NLSE with a non-Hermitian term that is the model of an atom laser. The
analytical asymptotic solution to the Cauchy problem is obtained explicitly for
this example.Comment: 29 pages, 1 figur
Quasiparticles for the one-dimensional nonlocal Fisher-Kolmogorov-Petrovskii-Piskunov equation
We construct quasiparticles-like solutions to the one-dimensional
Fisher-Kolmogorov-Petrovskii-Piskunov (FKPP) with a nonlocal nonlinearity using
the method of semiclassically concentrated states in the weak diffusion
approximation. Such solutions are of use for predicting the dynamics of
population patterns. The interaction of quasiparticles stems from nonlocal
competitive losses in the FKPP model. We developed the formalism of our
approach relying on ideas of the Maslov method. The construction of the
asymptotic expansion of a solution to the original nonlinear evolution equation
is based on solutions to an auxiliary dynamical system of ODEs. The asymptotic
solutions for various specific cases corresponding to various spatial profiles
of the reproduction rate and nonlocal competitive losses are studied within the
framework of the approach proposed.Comment: 27 pages, 2 figure
Semiclassical approach to the nonlocal kinetic model of metal vapor active media
A semiclassical approach based on the WKB–Maslov method is developed for the kinetic ionization equation in dense plasma with approximations characteristic of metal vapor active media excited by a contracted discharge. We develop the technique for constructing the leading term of the semiclassical asymptotics of the Cauchy problem solution for the kinetic equation under the supposition of weak diffusion. In terms of the approach developed, the local cubic nonlinear term in the original kinetic equation is considered in a nonlocal form. This allows one to transform the nonlinear nonlocal kinetic equation to an associated linear partial differential equation with a given accuracy of the asymptotic parameter using the dynamical system of moments of the desired solution of the equation. The Cauchy problem solution for the nonlinear nonlocal kinetic equation can be obtained from the solution of the associated linear partial differential equation and some algebraic equations for the coefficients of the linear equation. Within the developed approach, the plasma relaxation in metal vapor active media is studied with asymptotic solutions expressed in terms of higher transcendental functions. The qualitative analysis of such the solutions is given
Family of asymptotic solutions to the two-dimensional kinetic equation with a nonlocal cubic nonlinearity
We apply the original semiclassical approach to the kinetic ionization
equation with the nonlocal cubic nonlinearity in order to construct the family
of its asymptotic solutions. The approach proposed relies on an auxiliary
dynamical system of moments of the desired solution to the kinetic equation and
the associated linear partial differential equation. The family of asymptotic
solutions to the kinetic equation is constructed using the symmetry operators
acting on functions concentrated in a neighborhood of a point determined by the
dynamical system. Based on these solutions, we introduce the nonlinear
superposition principle for the nonlinear kinetic equation. Our formalism based
on the Maslov germ method is applied to the Cauchy problem for the specific
two-dimensional kinetic equation. The evolution of the ion distribution in the
kinetically enhanced metal vapor active medium is obtained as the nonlinear
superposition using the numerical-analytical calculations.Comment: 29 pages, 3 figures, 1 table, minor improvements, the article is
published in Symmetr
Study of amplifying characteristics of copper bromide active media operating at the increased superradiance pulse duration mode
Amplifying characteristics of the copper bromide vapor active media with the increased inversion duration are studied using the detailed kinetic modeling. The analysis of the gain radial profile and its time evolution at various points of the GDT profile is presented. The results show the possibility of application such active media to the tasks of the remote object visualization
Next-to-Leading Order perturbative QCD corrections to baryon correlators in matter
We compute the next-to-leading order perturbative QCD corrections to the
correlators of nucleon interpolating currents in relativistic nuclear matter.
The main new result is the calculation of the O(alpha_s) perturbative
corrections to the coefficient functions of the vector quark condensate in
matter. This condensate appears in matter due to the violation of Lorentz
invariance. The NLO perturbative QCD corrections turn out to be large which
implies that the NLO corrections must be included in a sum rule analysis of the
properties of both bound nucleons and relativistic nuclear matter.Comment: 19 pages in LaTeX, including 5 Postscript figure
Study of high-frequency brightness amplifiers radial profile
The paper presents experimental results on obtaining high pulse repetition frequencies of radiation/gain in copper bromide vapor active media. Also the results of experimental and theoretical studies of radial profiles of radiation and amplification of such media at raised pump pulse frequencies are give
Charge Symmetry Violation Corrections to Determination of the Weinberg Angle in Neutrino Reactions
We show that the correction to the Paschos-Wolfenstein relation associated
with charge symmetry violation in the valence quark distributions is
essentially model independent. It is proportional to a ratio of quark momenta
that is independent of Q^2. This result provides a natural explanation of the
surprisingly good agreement found between our earlier estimates within several
different models. When applied to the recent NuTeV measurement, this effect
significantly reduces the discrepancy with other determinations of the Weinberg
angle.Comment: 7 pages, no figures; expanded discussion of N.ne.Z correction
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