arXiv subjects
Publications and source records attributed to Wilhelm I. Fushchych.
Classes of the nonlinear Schrodinger-type equations compatible with the Galilei relativity principle are described. Solutions of these equations satisfy the continuity equation.
We construct nonlinear representations of the Poincare, Galilei, and conformal algebras on a set of the vector-functions $Ψ=(\vec E, \vec H)$. A nonlinear complex equation of Euler type for the electromagnetic field is proposed. The invariance algebra of this equation is found.
Ansatzes for the Navier-Stokes field are described. These ansatzes reduce the Navier-Stokes equations to system of differential equations in three, two, and one independent variables. The large sets of exact solutions of the Navier-Stokes equations are constructed.
In this note we show that there exists a new set of operators {Q} (this set is different from the operators which satisfy the Lie algebra of the Poincare group P(1,3) with respect to which the Dirac and Maxwell equations are invariant. We shall give the detailed proof of our assertions only for the Dirac equation, since for the Maxwell equations all the assertions are proved analogously.
The purpose of the present note is to propose, in the framework of relativistic quantum mechanics, a new Poincare-invariant equation for two particles with masses m_1, m_2 and spin s_1=s_2=1/2. It is a first-order linear differential equation for the eight-component wave function. With the help of this equation the description of the motion of two-particle systems is reduced to the description of one-particle systems in the (1+6)-dimensional Minkowski space which can be in two spin states (s=0 or s=1).
In this note we shall construct, in the framework of relativistic quantum mechanics, the Poincare-invariant motion equations with realistic mass spectra. These equations describe a system with mass spectra of the form $m^2=a^2+b^2 s(s+1)$, where a and b are arbitrary parameters. Such equations are obtained by a reduction of the motion equation for two particles to a one-particle equation which describes the particle in various mass and spin states. It we impose a certain condition on the wave function of the derived equation, such an equation describes the free motion of a fixed-mass particle with arbitrary (but fixed) spin s.
In previous papers quant-ph/0206077, quant-ph/0206078, quant-ph/0206079 we have shown that there exist three types of the relativistic equations for the massless particles. Here we show that for the free particles and antiparticles with the mass m>0 and the arbitrary spin $s \geq 1/2$ there also exist three types of nonequivalent equations.
We have shown quant-ph/0206104 (Lett. Nuovo Cimento, 1972, 4, 344) that for free particles and antiparticles with mass m>0 and arbitrary spin s>0, in the framework of the Poincare group P(1,3), there exist three types of nonequivalent equations. In the present paper we study the P, T, C properties of these equations.
There are a number of papers dedicated to the description of free particles and antiparticles with zero mass and spin 1/2. A great many equations with different C, P, T properties have been proposed and the impression could be formed that there are many nonequivalent theories for zero-mass particles. The purpose or this paper is to show that it is not the case and to describe all nonequivalent equations.
The relativistic two-component equation describing the free motion of particles with zero mass and spin 1/2, which is P- and T-non-invariant but C-invariant, is found. The representation of the Poincare group for zero mass and discrete spin is constructed. The position operator for such a particle is defined.
One of us quant-ph/0206077 (Nucl. Phys. B, 1970, 21, 321) has shown that for the particle with zero mass and spin s=1/2 there are three types of two-component equations (or one four-component equation with three different subsidiary conditions) which differ from one another by P, T and C properties. One of these equations is the two-component Weyl equation. In this note we give two other relativistic invariant equations.
The paper presents a detailed theoretical-group analysis of three types of two-component equations of motion which describe the particle with zero mass and spin 1/2. There are studied P-, T- and C-propertias of the equations obtained.
The properties of the equation of Dirac type in three-dimensional and five-dimensional Minkowski space-time with respect to time reflection (in sense of Pauli and Wigner) as well as to the operation of charge conjugation are investigated. P-, T-, C-invariance of Dirac equation for the cases of four components (in three-dimentional space) and eight components (in five-dimensional space) is established. Within the framework of the Poincare group a relativistic equation is suggested wich describes the movement of a particle with non-fixed (indefinite) mass in external electromagnetic field.
This paper is a continuation and elaboration of our work quant-ph/0206057 (Nucl. Phys. B, 1968, 7, 79) where some approach to the variable-mass problem were proposed. Here we have found a concret realization of irreducible representations of the inhomogeneous group P(1,n) - the group of translations and rotations in (1+n)-dimensional Minkowski space in two classes (when P_0^2-P_k^2>0 and P_0^2-P_k^2<0). All the P(1,n)-invariant equations of the Schrodinger-Foldy type are written down. Some questions of a physical interpretation of the quantum, mechanical scheme based on the inhomogeneous de Sitter group P(1,n) are discussed.
The mass operator M is introduced as an independent dynamical variable which is taken as the translation generator P_4 of the inhomogenous De Sitter group. The classification of representations of the algebra P(1,4) of this group is performed and the corresponding P(1,4) invariant equations for variable-mass particles are written out. In this way we have succeeded, in particular, in uniting the ``external'' and ``internal'' (SU_2) symmetries in a non-trivial fashion.
This paper is a continuation and elaboration of our brief notice quant-ph/0206057 (Nucl. Phys. B, 1968, 7, 79) where some approach to the variable-mass problem was proposed. Here we have found a definite realization of irreducible representations of the inhomogeneous group P(1,n), the group of translations and rotations in (1+n)-dimensional Minkowski space, in two classes (when P_0^2-P_k^2>0 and P_0^2-P_k^2<0). All P(1,n)-invariant equations of the Schrodinger-Foldy type are written down. Some equations of physical interpretation of the quantal scheme based on the inhomogeneous de Sitter group P(1,4) are discussed. The analysis of the Dirac and Kemmer-Duffin type equations in the P(1,4) scheme is carried out. A concrete realization of representations of the algebra P(1,4) connected with this equations, is obtained. The transformations of the Foldy-Wouthuysen type for this equations are found. It is shown that in the P(1,4) scheme of the Kemmer-Duffin type equation describes a fermion multiplet like the nucleon-antinucleon.
In Ukrain. J. Phys., 1967, V.12, N 5, p.741-746 it was shown how, for a given (discrete) mass spectrum of elementary or hypothetical particles, it was possible to construct a non-trivial algebra G containing a Poincare algebra P as a subalgebra so that the mass operator, defined throughout the space where one of the irreducible representations G is given, is self-conjugate and its spectrum coincides with the given mass spectrum. Such an algebra was constructed in explicit form for the nonrelativistic case, i.e., the generators were written for the algebra. However, the problem of how to assign the algebra G constructively and determine an explicit form of the mass operator in the relativistic case has remained unsolved. In the present work we present a solution of this problem, construct continuum analogs of the classical algebras U(N) and Sp(2N), and show that the problem of including the Poincare algebra can be formulated in the language of wave function equations.
We suggest an effective approach to separation of variables in the Schrödinger equation with two space variables. Using it we classify inequivalent potentials $V(x_1,x_2)$ such that the corresponding Schr\" odinger equations admit separation of variables. Besides that, we carry out separation of variables in the Schr\" odinger equation with the anisotropic harmonic oscillator potential $V=k_1x_1^2+k_2x_2^2$ and obtain a complete list of coordinate systems providing its separability. Most of these coordinate systems depend essentially on the form of the potential and do not provide separation of variables in the free Schr\" odinger equation ($V=0$).