Open Access Open Access  Restricted Access Access granted  Restricted Access Subscription Access

Vol 201, No 1 (2019)

Article

Description of Solutions with the Uniton Number 3 in the Case of One Eigenvalue: Counterexample to the Dimension Conjecture

Domrina A.V.

Abstract

We explicitly describe solutions of the noncommutative unitary U (1) sigma model that represent finitedimensional perturbations of the identity operator and have only one eigenvalue and the minimum uniton number 3. We also show that the solution set M(e, r, u) of energy e and canonical rank r with the minimum uniton number u = 3 has a complex dimension greater than r for e = 4 n - 1 and r = n+1, where n ≥ 3. This disproves the dimension conjecture that holds in the case u ∈ {1, 2}.

Theoretical and Mathematical Physics. 2019;201(1):1413-1425
pages 1413-1425 views

Solution Space Monodromy of a Special Double Confluent Heun Equation and Its Applications

Tertychniy S.I.

Abstract

We consider three linear operators determining automorphisms of the solution space of a special double confluent Heun equation of positive integer order (L-operators). We propose a new method for describing properties of the solution space of this equation based on using eigenfunctions of one of the L-operators, called the universal L-operator. We construct composition laws for L-operators and establish their relation to the monodromy transformation of the solution space of the special double confluent Heun equation. We find four functionals quadratic in eigenfunctions of the universal automorphism; they have a property with respect to the considered equation analogous to the property of the first integral. Based on them, we construct matrix representations of the L-operators and also the monodromy operator. We give a method for extending solutions of the special double confluent Heun equation from the subset Re z > 0 of a complex plane to a maximum domain on which the solution exists. As an example of its application to the RSJ model theory of overdamped Josephson junctions, we give the explicit form of the transformation of the phase difference function induced by the monodromy of the solution space of the special double confluent Heun equation and propose a way to continue this function from a half-period interval to any given interval in the domain of the function using only algebraic transformations.

Theoretical and Mathematical Physics. 2019;201(1):1426-1441
pages 1426-1441 views

Some Exact Solutions of the Volterra Lattice

Adler V.E., Shabat A.B.

Abstract

We study solutions of the Volterra lattice satisfying the stationary equation for its nonautonomous symmetry. We show that the dynamics in t and n are governed by the respective continuous and discrete Painlevé equations and describe the class of initial data leading to regular solutions. For the lattice on the half-axis, we express these solutions in terms of the confluent hypergeometric function. We compute the Hankel transform of the coefficients of the corresponding Taylor series based on the Wronskian representation of the solution.

Theoretical and Mathematical Physics. 2019;201(1):1442-1456
pages 1442-1456 views

Blowup Solutions of the Nonlinear Thomas Equation

Korpusov M.O.

Abstract

We study boundary value problems on an interval and on the half-line for the well-known Thomas equation uxt + αux + βut + uxut = 0, which is a model equation describing processes in chemical kinetics with ion exchange during sorption in a reagent stream. For this equation, we obtain sufficient conditions for its solution blowup in a finite time.

Theoretical and Mathematical Physics. 2019;201(1):1457-1467
pages 1457-1467 views

Description of Stable Chemical Elements by an aF Diagram and Mean Square Fluctuations

Maslov V.P.

Abstract

We study the process of a nucleon separating from an atomic nucleus from the mathematical standpoint using experimental values of the binding energy for the nucleus of the given substance. A nucleon becomes a boson at the instant of separating from a fermionic nucleus. We study the further transformations of boson and fermion states of separation in a small neighborhood of zero pressure and obtain new important parastatistical relations between the temperature and the chemical potential when a nucleon separates from an atomic nucleus. The obtained relations allow constructing a new diagram (an aF diagram) or isotherms of very high temperatures corresponding to nuclear matter. We mathematically prove that the transition of particles from the domain governed by Fermi-Dirac statistics to the domain governed by Bose-Einstein statistics near the zero pressure P occurs in the neutron uncertainty domain or halo domain. We obtain equations for the chemical potential that allow determining the width of the uncertainty domain. Based on the calculated values of the minimum intensivity for Bose particles, the chemical potential, the compressibility factor, and the minimum mean square fluctuation of the chemical potential, we construct a table of stable nuclei of chemical elements, demonstrating a monotonic relation between the nucleus mass number and the other parameters.

Theoretical and Mathematical Physics. 2019;201(1):1468-1483
pages 1468-1483 views

Approximate Formula for the Total Cross Section for a Moderately Small Eikonal Function

Kisselev A.V.

Abstract

We study the eikonal approximation of the total cross section for the scattering of two unpolarized particles and obtain an approximate formula in the case where the eikonal function χ(b) is moderately small, |χ(b)| ≲ 0.1. We show that the total cross section is given by a series of improper integrals of the Born amplitude AB. The advantage of this representation compared with standard eikonal formulas is that these integrals contain no rapidly oscillating Bessel functions. We prove two theorems that allow relating the large-b asymptotic behavior of χ(b) to analytic properties of the Born amplitude and give several examples of applying these theorems. To check the effectiveness of the main formula, we use it to calculate the total cross section numerically for a selection of specific expressions for AB, choosing only Born amplitudes that result in moderately small eikonal functions and lead to the correct asymptotic behavior of χ(b). The numerical calculations show that if only the first three nonzero terms in it are taken into account, this formula approximates the total cross section with a relative error of O(10−5).

Theoretical and Mathematical Physics. 2019;201(1):1484-1502
pages 1484-1502 views

Full Analytic Spectrum of Generalized Jaynes-Cummings Hamiltonians

Adanmitonde A.J., Avossevou G.Y.

Abstract

We develop an analytic formalism using basic quantum mechanics techniques to successfully solve the multiphoton Jaynes–Cummings and the generalized Dicke Hamiltonians. For this, we split the Hamiltonians of these models into two operators that have the properties of constants of motion for these systems. We then use some well-known operator properties to obtain complete analytic spectra for the considered models.

Theoretical and Mathematical Physics. 2019;201(1):1503-1513
pages 1503-1513 views

Nonlinear Evolutionary Schrödinger Equation in a Two-Dimensional Domain

Nasibov S.M.

Abstract

We consider a mixed problem for a nonlinear evolutionary Schrödinger equation in a two-dimensional domain and study the smoothness of solutions and their destruction.

Theoretical and Mathematical Physics. 2019;201(1):1514-1520
pages 1514-1520 views

A p-Adic Generalized Gibbs Measure for the Ising Model on a Cayley Tree

Rahmatullaev M.M., Khakimov O.N., Tukhtaboev A.M.

Abstract

We consider a p-adic Ising model on the Cayley tree of order k ≥ 2. We completely describe all p-adic-translation-invariant generalized Gibbs measures for k = 3. Moreover, we show the existence of a phase transition for the p-adic Ising model for any k ≥ 3 if p ≡ 1 (mod 4).

Theoretical and Mathematical Physics. 2019;201(1):1521-1530
pages 1521-1530 views

Effect of Phonons on the Magnetic Characteristics of Metals at Finite Temperatures

Melnikov N.B., Paradezhenko G.V., Reser B.I.

Abstract

We consider the electron-phonon interaction in the framework of dynamic spin-fluctuation theory and obtain an expression for the self-energy part that depends explicitly on the spin fluctuations and lattice vibrations. We illustrate the theoretical results with the example of iron. We show that the effect of phonons on temperature dependence of the magnetic characteristics of metals is appreciable but not as large as in the static single-site approximation of the spin-fluctuation theory and spin dynamics using classical Hamiltonians.

Theoretical and Mathematical Physics. 2019;201(1):1531-1540
pages 1531-1540 views

Erratum

Erratum to: Static Limit and Penrose Effect in Rotating Reference Frames

Grib A.A., Pavlov Y.V.

Abstract

Reference [3] on page 1125, 3. A. A. Grib and Yu. V. Pavlov, “Comparison of particle properties in Kerr metric and in rotating coordinates,” Gen. Rel. Grav., 49, 78 (2017); arXiv:1609.04202v2 [gr-qc] (2016).C. W. Misner, K. S. Thorne, and J. A. Wheeler, Gravitation, Freeman, San Francisco (1973).

should be split as

3. A. A. Grib and Yu. V. Pavlov, “Comparison of particle properties in Kerr metric and in rotating coordinates,” Gen. Rel. Grav., 49, 78 (2017); arXiv:1609.04202v2 [gr-qc] (2016).

4. C. W. Misner, K. S. Thorne, and J. A. Wheeler, Gravitation, Freeman, San Francisco (1973).

The subsequent reference numbers should incremented (old numbers 4–20 become 5–21). Then the citations in the text will correctly relate to the list of references.

The editorial staff apologizes to the authors.

Theoretical and Mathematical Physics. 2019;201(1):1541-1541
pages 1541-1541 views