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Igor Loutsenko

Publications and source records attributed to Igor Loutsenko.

17 recordsLinked to original sources
arXiv2024

Equilibrium of Charges and Differential Equations Solved by Polynomials II

We continue study of equilibrium of two species of 2d coulomb charges (or point vortices in 2d ideal fluid) started in (Igor Loutsenko, J. Phys. A: Math. Gen. 37, 1309, 2004). Although for two species of vortices with circulation ratio -1 the relationship between the equilibria and the factorization/Darboux transformation of the Schrodinger operator was established a long ago, the question about similar relationship for the ratio -2 remained unanswered. Here we present the answer: One has to consider Darboux-type transformations of third order differential operators rather than second order Schrodinger operators. Furthermore, we show that such transformations can also generate equilibrium configurations where an additional charge of a third specie is present. Relationship with integrable hierarchies is briefly discussed.

math-ph↗
arXiv2024

Vortices and Factorization

We review applications of factorization methods to the problem of finding stationary point vortex patterns in two-dimensional fluid mechanics. Then we present a new class of patterns related to periodic analogs of Schrodinger operators from the ``even" bi-spectral family. We also show that patterns related to soliton solutions of the KdV hierarchy constitute complete solution of the problem for certain classes of vortex systems. Keywords: Point vortices in ideal fluid, Factorization of second- and third-order differential operators, KdV and Sawada-Kotera hierarchies, Bispectral problem, Locus configurations

math-ph↗
arXiv2020

Quasi Band-Limited Coronagraph for Extended Sources

We propose a class of graded coronagraphic "amplitude" image masks for a high throughput Lyot-type coronagraph that transmits light from an annular region around an extended source and suppresses light, with extremely high ratio, from elsewhere. The interior radius of the region is comparable with its exterior radius. The masks are designed using an idea inspired by approach due M.J. Kuchner and W.A. Traub ("band-limited" masks) and approach to optimal apodization by D.Slepian. One potential application of our masks is direct high-resolution imaging of exo-planets with the help of the Solar Gravitational Lens, where apparent radius of the "Einstein ring" image of a planet is of the order of an arc-second and is comparable with the apparent radius of the sun and solar corona. Keywords: Coronagraphy, Optimal Band-Limiting, Exo-Planets, Solar Gravitational Lens

astro-ph.IM↗
arXiv2019

Stochastic Loewner Evolutions, Fuchsian Systems and Orthogonal Polynomials

We find a wide class of Levy-Loewner evolutions for which the value of integral means beta-spectrum $\beta(q)$ at $q=2$ is the maximal real eigenvalue of a three-diagonal matrix. The second moments of derivatives of corresponding conformal mappings are expressed through solutions of matrix Fuchsian systems with three singular points.

math-ph↗
arXiv2019

On Integrability and Exact Solvability in Deterministic and Stochastic Laplacian Growth

We review applications of theory of classical and quantum integrable systems to the free-boundary problems of fluid mechanics as well as to corresponding problems of statistical mechanics. We also review important exact results obtained in the theory of multi-fractal spectra of the stochastic models related to the Laplacian growth: Schramm-Loewner and Levy-Loewner evolutions.

math-ph↗
arXiv2017

On the Role of Caustic in Solar Gravitational Lens Imaging

We consider scattering of electromagnetic waves from a distant point source by the gravitational field of the sun, taking the field oblateness due to the quadrupole moment of the sun into account. Effects of the field oblateness can play an important role in the high resolution solar gravitational lens imaging in the sub-micrometer wavelength range of the electromagnetic spectrum.

gr-qc↗
arXiv2013

On Harmonic Measure of the Whole Plane Levy-Loewner Evolution

Levy-Loewner evolution (LLE) is a generalization of the Schramm-Loewner evolution (SLE) where the branching is possible in a course of growth process. We consider a class of radial Levy-Loewner evolutions for which sets of points of the average means beta-spectrum can be found exactly. In this paper we show how to overcome difficulties arised in previous works on multi-fractal analysis of SLE/LLE.

math-ph↗
arXiv2012

New Applications of Quantum Algebraically Integrable Systems in Fluid Dynamics

The rational quantum algebraically integrable systems are non-trivial generalizations of Laplacian operators to the case of elliptic operators with variable coefficients. We study corresponding extensions of Laplacian growth connected with algebraically integrable systems, describing viscous free-boundary flows in non-homogenous media. We introduce a class of planar flows related with application of Adler-Moser polynomials and construct solutions for higher-dimensional cases, where the conformal mapping technique is unavailable.

nlin.SI↗
arXiv2012

SLE_k: correlation functions in the coefficient problem

We apply the method of correlation functions to the coefficient problem in stochastic geometry. In particular, we give a proof for some universal patterns conjectured by M. Zinsmeister for the second moments of the Taylor coefficients for special values of kappa in the whole-plane Schramm-Loewner evolution (SLE_kappa). We propose to use multi-point correlation functions for the study of higher moments in coefficient problem. Generalizations related to the Levy-type processes are also considered. The exact multifractal spectrum of considered version of the whole-plane SLE_kappa is discussed.

math-ph↗
arXiv2008

Discrete Laplacian Growth: Linear Stability vs Fractal Formation

We introduce stochastic Discrete Laplacian Growth and consider its deterministic continuous version. These are reminiscent respectively to well-known Diffusion Limited Aggregation and Hele-Shaw free boundary problem for the interface propagation. We study correlation between stability of deterministic free-boundary problem and macroscopic fractal growth in the corresponding discrete problem. It turns out that fractal growth in the discrete problem is not influenced by stability of its deterministic version. Using this fact one can easily provide a qualitative analytic description of the Discrete Laplacian Growth.

cond-mat.stat-mech↗
arXiv2006

Non-Laplacian growth, algebraic domains and finite reflection groups

Dynamics of planar domains with moving boundaries driven by the gradient of a scalar field that satisfies an elliptic PDE is studied. We consider the question: For which kind of PDEs the domains are algebraic, provided the field has singularities at a fixed point inside the domain? The construction reveals a direct connection with the theory of the Calogero-Moser systems related to finite reflection groups and their integrable deformations.

math-ph↗
arXiv2005

The Variable Coefficient Hele-Shaw Problem, Integrability and Quadrature Identities

The theory of quadrature domains for harmonic functions and the Hele-Shaw problem of the fluid dynamics are related subjects of the complex variables and mathematical physics. We present results generalizing the above subjects for elliptic PDEs with variable coefficients emerging in a class of the free-boundary problems for viscous flows in non-homogeneous media. Such flows posses an infinite number of conservation laws, whose special cases may be viewed as quadrature identities for solutions of variable-coefficient elliptic PDEs. If such PDEs are gauge equivalent to the Laplace equation (gauge-trivial case), a time-dependent conformal map technique, employed for description of the quadrature domains, leads to differential equations, known as "string" constraints in the theory of integrable systems. Although analogs of the string constraints have non-local forms for gauge-non-trivial equations, it is still possible to construct the quadrature domains explicitly, if the elliptic operator belongs to a class of the Calogero-Moser Hamiltonians.

math-ph↗
arXiv2004

Quantum Separation of Variables and Multi-component Dyson Brownian Motion

A new type of Coulomb gas is defined, consisting of arbitrary numbers of point charges of two species executing Brownian motions under the influence of their mutual electrostatic repulsion. Being a generalization of a model of identical particles introduced by Dyson as a dynamical system describing non-equilibrium state of various random matrix ensembles, our system gives an exact mathematical description of the Brownian motion of charges of magnitudes $ Q_1 $ and $ Q_2 $, such that $ \beta Q_1 Q_2 = 1 $ on the line or circle, where $\beta$ is an inverse temperature of the gas.

cond-mat.other↗
arXiv2002

Integrable Dynamics of Charges Related to Bilinear Hypergeometric Equation

A family of systems related to a linear and bilinear evolution of roots of polynomials in the complex plane is considered. Restricted to the line, the evolution induces dynamics of the Coulomb charges in external potentials, while its fixed points correspond to equilibria of charges (or point vortices in hydrodynamics) in the plane. The construction reveals a direct connection with the theories of the Calogero-Moser systems and Lie-algebraic differential operators. A study of the equilibrium configurations amounts in a construction (bilinear hypergeometric equation) for which the classical orthogonal and the Adler-Moser polynomials represent some particular cases

math-ph↗
arXiv1999

Soliton Solutions of Integrable Hierarchies and Coulomb Plasmas

Some direct relations between soliton solutions of integrable hierarchies and thermodynamical quantities of the Coulomb plasmas on the plane are revealed. We find that certain soliton solutions of the Kadomtsev-Petviashvili (KP) and B-type KP (BKP) hierarchies describe two-dimensional one or two component plasmas at special boundary conditions and fixed temperatures. It is shown that different reductions of integrable hierarchies describe one (two) component plasmas or dipole gases on one-dimensional submanifolds embedded in the two-dimensional space. We demonstrate application of the methods of soliton theory to statistical mechanics of such systems.

cond-mat.stat-mech↗