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  • Articles  (2,222)
  • American Institute of Physics (AIP)  (2,222)
  • American Chemical Society
  • Nature Publishing Group
  • 1995-1999  (2,222)
  • 1975-1979
  • Mathematics  (2,222)
  • 1
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    College Park, Md. : American Institute of Physics (AIP)
    Journal of Mathematical Physics 40 (1999), S. 4227-4239 
    ISSN: 1089-7658
    Source: AIP Digital Archive
    Topics: Mathematics , Physics
    Notes: We introduce a class of quantum pure state models called the coherent models. A coherent model is an even-dimensional manifold of pure states whose tangent space is characterized by a symplectic structure. In a rigorous framework of noncommutative statistics, it is shown that a coherent model inherits and expands the original spirit of the minimum uncertainty property of coherent states. © 1999 American Institute of Physics.
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  • 2
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    Journal of Mathematical Physics 40 (1999), S. 4208-4226 
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    Topics: Mathematics , Physics
    Notes: A simple technique employed almost three decades ago to manufacture partially solvable quantum many-body problems is revisited. [A quantum problem is "partially solvable" if (only) some of its eigenvalues and eigenfunctions can be exhibited]. The models thereby generated are characterized by Hamiltonians of normal form, i.e., standard kinetic plus momentum-independent potential energy; in most cases the latter features three-body, in addition to two-body and one-body, interactions. The setting refers to D-dimensional space; the examples focus on D=1, D=2, and D≥2, and include generalizations of, and additional results on, cases recently discussed in the literature, as well as new models. © 1999 American Institute of Physics.
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  • 3
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    Journal of Mathematical Physics 40 (1999), S. 4185-4207 
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    Topics: Mathematics , Physics
    Notes: A simple image-charge construction enables one to insert point or line boundaries (or planar or hyperplanar boundaries when sufficiently many spatial dimensions are available) at or into the central point, line, plane etc., of a great range of spatial backgrounds in quantum field theory which have appropriate symmetry. This nontrivial construction (which provides among other things the exact vacuum stress tensor Tμν of the quantum field if Tμν can be computed for the original background prior to point, line,..., insertion) works if all directions xi perpendicular to the inserted object are symmetric under xi→−xi. In other respects the symmetric spatial background can be quite arbitrary. While the inserted object experiences (by symmetry) no net Casimir force from the background, it does exert Casimir forces throughout this background which were originally not present. In addition to general theory, detailed examples are given (which include exact field Tμν's and exact Casimir force densities) for arbitrary spatial dimension. First: point and line boundaries in otherwise empty space; then a planar boundary with a semi-infinite line extending from one side; finally, parallel planar boundaries with a point boundary halfway between them. Only scalar quantum fields are analyzed here; however the extension to the electromagnetic Casimir effect is discussed qualitatively. © 1999 American Institute of Physics.
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  • 4
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    Journal of Mathematical Physics 40 (1999), S. 4240-4254 
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    Topics: Mathematics , Physics
    Notes: Exact solutions of the Dirac equation in a chiral representation for neutrinos in the presence of external stresses are investigated in terms of special functions, using the algebraic method of the separation of variables in Cartesian, cylindrical, and spherical coordinates. © 1999 American Institute of Physics.
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  • 5
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    Journal of Mathematical Physics 40 (1999), S. 4255-4273 
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    Topics: Mathematics , Physics
    Notes: We introduce and perform a systematic study of a new exactly solvable model of sphere interactions in quantum mechanics : the δ′ interaction, formally given by −Δ+αδ′(|x|−R), x∈R3, R〉0, α∈R. We also consider the cases of a δ′ plus a Coulomb interaction and finitely many δ′-sphere interactions with support on concentric spheres. For all these models, we provide basic properties and discuss the stationary scattering theory. We also briefly discuss the δ′-sphere interaction of the second type. © 1999 American Institute of Physics.
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  • 6
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    Journal of Mathematical Physics 40 (1999), S. 4290-4295 
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    Topics: Mathematics , Physics
    Notes: It is widely believed that Bell has proved there can be no consistent local extension of the quantum formalism. Against this, Angelidis has presented a hidden variable theory which, he claims, makes precisely the same predictions as the quantum formalism and which also satisfies locality. In this note, we argue that Angelidis' theory does not live up to its inventor's claims. © 1999 American Institute of Physics.
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  • 7
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    Journal of Mathematical Physics 40 (1999), S. 4274-4289 
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    Topics: Mathematics , Physics
    Notes: The quantum mechanics of a spin 〈fraction SHAPE="CASE"〉12 particle on a locally spatial constant curvature part of a (2+1)-space–time in the presence of a constant magnetic field of a magnetic monopole has been investigated. It has been shown that these two-dimensional Hamiltonians have the degeneracy group of SL(2,c), and para-supersymmetry of arbitrary order or shape invariance. Using this symmetry we have obtained its spectrum algebraically. The Dirac's quantization condition has been obtained from the representation theory. Also, it is shown that the presence of angular deficit suppresses both the degeneracy and shape invariance. © 1999 American Institute of Physics.
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  • 8
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    Journal of Mathematical Physics 40 (1999), S. 4296-4302 
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    Topics: Mathematics , Physics
    Notes: A boundary value problem for a 2×2 S-matrix is solved by the method of projection matrices. The S-matrix is assumed to be diagnoalized by orthogonal matrix U(k2)=Ω(k2)/det Ω(k2), where matrix elements of Ω(k2) are polynomials. The equation det Ω(k2)=0 has roots of any order. The example is considered for the roots with order 2. © 1999 American Institute of Physics.
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  • 9
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    Journal of Mathematical Physics 40 (1999), S. 4303-4324 
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    Notes: We discuss the classical mechanics on the Grassmannian and the disc modeled on the ideal L(2,∞). We apply methods of geometric quantization to these systems. Their relation to a flat symplectic space is also discussed. © 1999 American Institute of Physics.
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  • 10
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    Journal of Mathematical Physics 40 (1999), S. 4325-4330 
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    Notes: The w∞ algebra is a higher-spin extension of the Virasoro algebra. In this paper, we construct the gauge theory of w symmetry in terms of its representations. © 1999 American Institute of Physics.
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  • 11
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    Journal of Mathematical Physics 40 (1999), S. 4331-4336 
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    Notes: The nonintegrable singularities that arise when the retarded potentials associated with supersonically or superluminally moving sources are differentiated are closely related to those encountered in the context of the Cauchy problem for hyperbolic equations over odd-dimensional space-times. The purpose of this paper is to point out that the field components are given in these cases by Hadamard's finite parts of the resulting divergent integrals, as in the case of the Cauchy problem, and to show that the procedure familiar from the subluminal regime—which is used by Hannay—is not applicable when there are source elements that approach the observer with the wave speed and zero acceleration at the retarded time. © 1999 American Institute of Physics.
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  • 12
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    Journal of Mathematical Physics 40 (1999), S. 4337-4358 
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    Topics: Mathematics , Physics
    Notes: We discuss the existence and uniqueness of nonequilibrium dynamics of infinitely many particles interacting via superstable pair interactions in one and two dimensions. The interaction is allowed to be of infinite range and singular at the origin. Under suitable regularity conditions on the interaction potential, we show that if the potential decreases polynomially as the distance between interacting two particles increases, then the tempered solution to the system of Hamiltonian equations exists. Moreover, if the potential satisfies further that either it has a subexponential decreasing rate or it is everywhere two-times continuously differentiable, then we show that the tempered solution is unique. The results extend those of Dobrushin and Fritz obtained for finite range interactions. © 1999 American Institute of Physics.
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  • 13
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    Journal of Mathematical Physics 40 (1999), S. 4359-4373 
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    Topics: Mathematics , Physics
    Notes: With use of the invariant imbedding method and Markov process approximation, the statistical characteristics of the backscattering field from the impulse point source in a nonstationary multidimensional random medium are considered. The equations for the characteristic function and the density of the probability in the functional space of the backscattering are obtained. The equations for the statistical moments of the field are yielded and then solutions are presented in the matrix form. The additional averaging of the fast field variations is used for the simplification of the statistical equations. The procedures for the investigation of the direct and inverse statistical problem are proposed. The role of the phenomenological transfer theory is discussed from the statistical point of view. © 1999 American Institute of Physics.
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  • 14
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    Journal of Mathematical Physics 40 (1999), S. 4374-4392 
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    Topics: Mathematics , Physics
    Notes: The Cauchy problem of a class of nonlinear evolution equations is solved by finding explicit solutions of a discrete inverse scattering problem that are not restricted to the pure soliton case and implementing appropriate time evolution of the scattering data. This yields operator-valued functions, which are shown to solve a hierarchy of operator evolution equations by applying methods similar to those in Marchenko's work. In addition the relation to canonical Lax constructions is investigated. Using methods introduced by Aden and Carl and Schiebold, one obtains scalar solutions to corresponding scalar equations, sometimes representable by determinants on operator ideals. © 1999 American Institute of Physics.
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  • 15
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    Journal of Mathematical Physics 40 (1999), S. 4393-4399 
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    Topics: Mathematics , Physics
    Notes: We derive a generalized Gel'fand–Levitan integral equation for two block Ablowitz–Kaup–Newell–Segur systems. This is possible if we suppose that the matrix coupling coefficients are invertible and come from simple zeroes of the determinant of the diagonal blocks of the scattering matrix. © 1999 American Institute of Physics.
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  • 16
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    Journal of Mathematical Physics 40 (1999), S. 4400-4418 
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    Topics: Mathematics , Physics
    Notes: A general discussion is given of weak limits of classical dynamical systems depending on a parameter. The resulting maps are shown to be invertible if and only if they define a group of measure preserving point transformations. The irreversible case automatically leads to positive bistochastic maps and is characterized in terms of convergence properties of the corresponding automorphisms of the observable algebra. Necessary and sufficient conditions are given for the limit to define a time-independent Markov process. Two models are discussed, for a particle in a periodic potential, and for a particle interacting with fixed configurations of external obstacles. © 1999 American Institute of Physics.
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  • 17
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    Journal of Mathematical Physics 40 (1999), S. 4429-4443 
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    Notes: Spatially homogeneous field theories are studied in the framework of dynamical system theory. In particular, we consider a model of inflationary cosmology and a Yang–Mills–Higgs system. We discuss also the role of quantum chaos and its application to field theories. © 1999 American Institute of Physics.
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  • 18
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    Journal of Mathematical Physics 40 (1999), S. 4419-4428 
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    Notes: A coupled AKNS–Kaup–Newell hierarchy of systems of soliton equations is proposed in terms of hereditary symmetry operators resulted from Hamiltonian pairs. Zero curvature representations and tri-Hamiltonian structures are established for all coupled AKNS–Kaup–Newell systems in the hierarchy. Therefore all systems have infinitely many commuting symmetries and conservation laws. Two reductions of the systems lead to the AKNS hierarchy and the Kaup–Newell hierarchy, and thus those two soliton hierarchies also possess tri-Hamiltonian structures. © 1999 American Institute of Physics.
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  • 19
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    Journal of Mathematical Physics 40 (1999), S. 4444-4451 
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    Notes: We obtain an estimate of the upper bound of the Hausdorff dimension of the global attractor for damped semilinear wave equations with a critical exponent. The obtained Hausdorff dimension decreases as the damping grows for large damping. © 1999 American Institute of Physics.
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  • 20
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    Journal of Mathematical Physics 40 (1999), S. 4452-4473 
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    Notes: It is shown how to construct an infinite number of families of quasi-bi-Hamiltonian (QBH) systems by means of the constrained flows of soliton equations. Three explicit QBH structures are presented for the first three families of the constrained flows. The Nijenhuis coordinates defined by the Nijenhuis tensor for the corresponding families of QBH systems are proved to be exactly the same as the separated variables introduced by mean of the Lax matrices for the constrained flows. © 1999 American Institute of Physics.
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  • 21
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    Journal of Mathematical Physics 40 (1999), S. 4474-4494 
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    Notes: We show that the resonant interaction of sound waves is a source of gravitational waves in general relativity. We derive an asymptotic equation that describes this process, and compute the interaction coefficient for the quadratically nonlinear coupling between sound waves and gravitational waves. © 1999 American Institute of Physics.
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  • 22
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    Journal of Mathematical Physics 40 (1999), S. 4495-4505 
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    Notes: All nontwisting Petrov-type N solutions of vacuum Einstein field equations with cosmological constant Λ are summarized. They are shown to belong either to the nonexpanding Kundt class or to the expanding Robinson–Trautman class. Invariant subclasses of each class are defined and the corresponding metrics are given explicitly in suitable canonical coordinates. Relations between the subclasses and their geometrical properties are analyzed. In the subsequent paper these solutions are interpreted as exact gravitational waves propagating in de Sitter or anti-de Sitter spacetimes. © 1999 American Institute of Physics.
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  • 23
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    Journal of Mathematical Physics 40 (1999), S. 4518-4526 
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    Notes: We derive simple general expressions for the explicit Killing spinors on the n-sphere, for arbitrary n. Using these results we also construct the Killing spinors on various AdS×Sphere supergravity backgrounds, including AdS5×S5, AdS4×S7, and AdS7×S4. In addition, we extend previous results to obtain the Killing spinors on the hyperbolic spaces Hn. © 1999 American Institute of Physics.
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  • 24
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    Journal of Mathematical Physics 40 (1999), S. 4527-4537 
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    Notes: Homogeneous and isotropic cosmological models whose Hamilton–Jacobi equation is separable are deparametrized by turning their action functional into that of an ordinary gauge system. Canonical gauge conditions imposed on the gauge system are used to define a global phase time in terms of the canonical coordinates and momenta of the minisuperspaces. The procedure clearly shows how the geometry of the constraint surface restricts the choice of time; the consequences that this has on the path integral quantization are discussed. © 1999 American Institute of Physics.
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  • 25
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    Journal of Mathematical Physics 40 (1999), S. 4506-4517 
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    Notes: In a suitably chosen essentially unique frame tied to a given observer in a general spacetime, the equation of geodesic deviation can be decomposed into a sum of terms describing specific effects: isotropic (background) motions associated with the cosmological constant, transverse motions corresponding to the effects of gravitational waves, longitudinal motions and Coulomb-type effects. Conditions under which the frame is parallelly transported along a geodesic are discussed. Suitable coordinates are introduced and an explicit coordinate form of the frame is determined for spacetimes admitting a nontwisting null congruence. Specific properties of all nontwisting type N vacuum solutions with cosmological constant Λ (nonexpanding Kundt class and expanding Robinson–Trautman class) are then analyzed. It is demonstrated that these spacetimes can be understood as exact transverse gravitational waves of two polarization modes "+" and "×," shifted by π/4, which propagate "on" Minkowski, de Sitter or anti-de Sitter backgrounds. It is also shown that the solutions with Λ〉0 may serve as exact demonstrations of the cosmic "no-hair" conjecture in radiative spacetimes with no symmetry. © 1999 American Institute of Physics.
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    Journal of Mathematical Physics 40 (1999), S. 4538-4548 
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    Notes: The covariant Klein–Gordon equation in the Kerr–Newman black hole geometry is separated into a radial part and an angular part. It is discovered that in the nonextreme case, these two equations belong to a generalized spin-weighted spheroidal wave equation. Then general exact solutions in integral forms and several special solutions with physical interest are given. While in the extreme case, the radial equation can be transformed into a generalized Whittaker–Hill equation. In both cases, five-term recurrence relations between coefficients in power series expansion of general solutions are presented. Finally, the connection between the radial equations in both cases is discussed. © 1999 American Institute of Physics.
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    Journal of Mathematical Physics 40 (1999), S. 4549-4568 
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    Notes: We study a pair of commuting difference operators arising from the elliptic C2(1)-face model. The operators, whose coefficients are expressed in terms of the Jacobi's elliptic theta function, act on the space of meromorphic functions on the weight space of the C2-type simple Lie algebra. We show that the space of functions spanned by the level one characters of the affine Lie algebra sp&dbgcaret;(4,C) is invariant under the action of the difference operators. © 1999 American Institute of Physics.
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    Journal of Mathematical Physics 40 (1999), S. 1420-1431 
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    Notes: A general symmetry of the bilinear BKP hierarchy is studied in terms of tau functions. We use this symmetry to define reductions of the BKP hierarchy, among which new integrable systems can be found. The reductions are connected to constraints on the Lax operator as well as on the bilinear formulation. A class of solutions for the reduced equations is derived. © 1999 American Institute of Physics.
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    Journal of Mathematical Physics 40 (1999), S. 1439-1465 
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    Notes: The fractionally charged solitons in a trimerized electron–phonon system are studied by both analytical and numerical methods. To make those methods possible, an effective Lagrangian is derived by diagrammatic calculations. It is found that this Lagrangian is similar to that derived by the so-called derivative expansion. Both the phase and amplitude parts of the complex order parameter are included in the Lagrangian, and here we particularly focus on the nonlinear coupling between them. When the electron–phonon coupling is very weak, the aforementioned coupling is also weak, and so the soliton is almost considered to be a pure phase soliton with a constant amplitude. While, in the intermediate electron–phonon coupling case, the two parts of the order parameter are nonlinearly coupled. As a result, the soliton changes its pattern from that of a phase soliton to a strongly amplitude-deformed one. Our both methods, i.e., the analytical and numerical ones, succeed in giving such changes as gradual ones. Moreover, the coincidence of the two results is also good at a quantitative level. © 1999 American Institute of Physics.
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    Journal of Mathematical Physics 40 (1999), S. 1504-1517 
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    Notes: A scalar field nonminimally coupled to gravity is studied in the canonical framework, using self-dual variables. The corresponding constraints are first class and polynomial. To identify the real sector of the theory, reality conditions are implemented as second class constraints, leading to three real configurational degrees of freedom per space point. Nevertheless, this realization makes nonpolynomial some of the constraints. The original complex symplectic structure reduces to the expected real one, by using the appropriate Dirac brackets. For the sake of preserving the simplicity of the constraints, an alternative method preventing the use of Dirac brackets, is discussed. It consists of converting all second class constraints into first class by adding extra variables. This strategy is implemented for the pure gravity case. © 1999 American Institute of Physics.
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    Journal of Mathematical Physics 40 (1999), S. 708-725 
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    Notes: Potentials for which the corresponding Schrödinger equation is maximally superintegrable in three-dimensional Euclidean space are studied. The quadratic algebra which is associated with each of these potentials is constructed and the bound state wave functions are computed in the separable coordinates. © 1999 American Institute of Physics.
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    Journal of Mathematical Physics 40 (1999), S. 787-794 
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    Notes: We present a mathematical framework of gauge theories that is based upon a skew-adjoint Lie algebra and a generalized Dirac operator, both acting on a Hilbert space. © 1999 American Institute of Physics.
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    Journal of Mathematical Physics 40 (1999), S. 795-820 
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    Notes: A general model is proposed for constrained dynamical systems on a symplectic manifold which covers, among others, the description of Lagrangian and Hamiltonian systems with nonholonomic constraints and the canonical description of mechanical systems with a singular Lagrangian. The reduction properties of these systems in the presence of symmetry are investigated within this general framework. © 1999 American Institute of Physics.
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    Journal of Mathematical Physics 40 (1999), S. 838-856 
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    Notes: The one-variable Fokker–Planck equation is studied in its general form by means of an algebraic method. An expression of the Green's function is derived as an expansion in powers of the square root of frequency. The expansion coefficient of arbitrary order is expressed as a functional of the potential in terms of integrals. © 1999 American Institute of Physics.
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    Journal of Mathematical Physics 40 (1999), S. 869-883 
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    Notes: In this paper we study an incompressible inviscid fluid when the initial vorticity is sharply concentrated in N disjoint regions. This problem has been well studied when a planar symmetry is present, i.e., the fluid moves in R2. In this case we know that, when the diameter σ of each region supporting the vorticity is very small, the time evolution of the fluid is quite well described by a dynamical system with finite degrees of freedom called the "point vortex model." In particular the connection between this model and the Euler equation has been proved rigorously as σ→0. In the present paper we discuss the "stability" of the point vortex model with respect to a particular small perturbation of the planar symmetry. More precisely we consider a fluid moving in R3 with a cylindrical symmetry without swirl in which each vortex is no longer a straight tube, but a vorticity ring. We prove that large annuli of radii r(approximate)σ−β for any β〉0 remain "localized" and hence we obtain the point vortex model as σ→0. © 1999 American Institute of Physics.
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    Journal of Mathematical Physics 40 (1999), S. 924-938 
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    Notes: Multidimensional gravity interacting with intersecting electric and magnetic p-branes is considered for fields depending on a single variable. Some general features of the system behavior are revealed without solving the field equations. Thus, essential asymptotic properties of isotropic cosmologies are indicated for different signs of spatial curvature; a no-hair-type theorem and a single-time theorem for black holes are proved (the latter makes sense in models with multiple time coordinates). The validity of the general observations is verified for a class of exact solutions known for the cases when certain vectors, built from the input parameters of the model, are either orthogonal in minisuperspace, or form mutually orthogonal subsystems. From the nonexistence of Lorentzian wormholes, a universal restriction is obtained, applicable to orthogonal or block-orthogonal subsystems of any p-brane system. © 1999 American Institute of Physics.
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    Journal of Mathematical Physics 40 (1999), S. 980-1010 
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    Notes: Computations of the strong field generation of gravitational waves by black hole processes produces waveforms that are dominated by quasinormal (QN) ringing, a damped oscillation characteristic of the black hole. We describe here the mathematical problem of quantifying the QN content of the waveforms generated. This is done in several steps: (i) We develop the mathematics of QN systems that are complete (in a sense to be defined) and show that there is a quantity, the "excitation coefficient," that appears to have the properties needed to quantify QN content. (ii) We show that incomplete systems can (at least sometimes) be converted to physically equivalent complete systems. Most notably, we give a rigorous proof of completeness for a specific modified model problem. (iii) We evaluate the excitation coefficient for the model problem, and demonstrate that the excitation coefficient is of limited utility. We finish by discussing the general question of quantification of QN excitations, and offer a few speculations about unavoidable differences between normal mode and QNM systems. © 1999 American Institute of Physics.
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    Journal of Mathematical Physics 40 (1999), S. 6167-6177 
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    Notes: Phase-integral formulas for the Coulomb wave functions FL(η,ρ) and GL(η,ρ) and certain linear combinations of these functions, with complex values of the variable ρ and the parameters L and η, are obtained explicitly up to the fifth order of the phase-integral approximation for two different choices of the base function. © 1999 American Institute of Physics.
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    Journal of Mathematical Physics 40 (1999), S. 6178-6188 
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    Notes: The collective dynamics of solitons with a coset space G/H as moduli space is studied. It is shown that the collective band for a vibrational state is given by the inequivalent coset space quantization corresponding to the representation of H carried by the vibration. To leading order the collective dynamics is free motion in G/H coupled to background gauge fields determined by the vibrational state. © 1999 American Institute of Physics.
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    Journal of Mathematical Physics 40 (1999), S. 6234-6244 
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    Notes: We establish the Schlieder and the Borchers property for thermal field theories. In addition, we provide some information on the commutation and localization properties of projection operators. © 1999 American Institute of Physics.
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    Journal of Mathematical Physics 40 (1999), S. 6223-6233 
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    Notes: Recently we have presented an ansatz which allows us to construct skyrmion fields from the harmonic maps of S2 to CPN−1. In this paper we examine this construction in detail and use it to construct, in an explicit form, new static spherically symmetric solutions of the SU(N) Skyrme models. We also discuss some properties of these solutions. © 1999 American Institute of Physics.
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    Journal of Mathematical Physics 40 (1999), S. 6266-6291 
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    Notes: The proof of the convergence of the quasilinearization method of Bellman and Kalaba, whose origin lies in the theory of linear programming, is extended to large and infinite domains and to singular functionals in order to enable the application of the method to physical problems. This powerful method approximates solution of nonlinear differential equations by treating the nonlinear terms as a perturbation about the linear ones, and is not based, unlike perturbation theories, on existence of some kind of small parameter. The general properties of the method, particularly its uniform and quadratic convergence, which often also is monotonic, are analyzed and verified on exactly solvable models in quantum mechanics. Namely, application of the method to scattering length calculations in the variable phase method shows that each approximation of the method sums many orders of the perturbation theory and that the method reproduces properly the singular structure of the exact solutions. The method provides final and reasonable answers for infinite values of the coupling constant and is able to handle even super singular potentials for which each term of the perturbation theory is infinite and the perturbation expansion does not exist. © 1999 American Institute of Physics.
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    Journal of Mathematical Physics 40 (1999), S. 6292-6301 
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    Notes: In general, Whitham dynamics involves infinitely many parameters called Whitham times, but in the context of N=2 supersymmetric Yang–Mills theory it can be regarded as a finite system by restricting the number of Whitham times appropriately. For example, in the case of SU(r+1) gauge theory without hypermultiplets, there are r Whitham times and they play an essential role in the theory. In this situation, the generating meromorphic one-form of the Whitham hierarchy on the Seiberg–Witten curve is represented by a finite linear combination of meromorphic one-forms associated with these Whitham times, but it turns out that there are various differential relations among these differentials. Since these relations can be written only in terms of the Seiberg–Witten one-form, their consistency conditions are found to give the Picard–Fuchs equations for the Seiberg–Witten periods. © 1999 American Institute of Physics.
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    Journal of Mathematical Physics 40 (1999), S. 6366-6398 
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    Notes: Systems of Newton equations of the form q¨=−〈fraction SHAPE="CASE"〉12A−1(q)∇k with an integral of motion quadratic in velocities are studied. These equations generalize the potential case (when A=I, the identity matrix) and they admit a curious quasi-Lagrangian formulation which differs from the standard Lagrange equations by the plus sign between terms. A theory of such quasi-Lagrangian Newton (qLN) systems having two functionally independent integrals of motion is developed with focus on two-dimensional systems. Such systems admit a bi-Hamiltonian formulation and are proved to be completely integrable by embedding into five-dimensional integrable systems. They are characterized by a linear, second-order partial differential equation PDE which we call the fundamental equation. Fundamental equations are classified through linear pencils of matrices associated with qLN systems. The theory is illustrated by two classes of systems: separable potential systems and driven systems. New separation variables for driven systems are found. These variables are based on sets of nonconfocal conics. An effective criterion for existence of a qLN formulation of a given system is formulated and applied to dynamical systems of the Hénon–Heiles type. © 1999 American Institute of Physics.
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    Journal of Mathematical Physics 40 (1999), S. 625-634 
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    Notes: The Schrödinger equation in higher dimensions is considered. It consists of the kinetic energy part given by the corresponding Laplace operator, and a term describing the interaction with the electrostatic field of a point charge. From Rutherford-type scattering experiments one can conclude that the potential of a point charge is ∼1/r irrespective of the dimension of the space where the experiment is carried through. Also the structure of the kinetic energy is unchanged in higher dimensions so that one is lead to the result that there exist stable atoms in higher spatial dimensions d≥4. The solutions and energy eigenvalues to this Schrödinger equation in higher dimensions are presented. As a consequence, the dimensionality of space can be read off from the spectral scheme of atoms: The three-dimensionality of space is a consequence of the existence of the Lyman series. Another consequence is that the Maxwell equations in higher dimensions must be modified in order to have the 1/r-potential as solution for a point charge. © 1999 American Institute of Physics.
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    Journal of Mathematical Physics 40 (1999), S. 4064-4071 
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    Notes: It is shown that the Levi-Civita metric can be obtained from a family of the Weyl metric, the γ metric, by taking the limit when the length of its Newtonian image source tends to infinity. In this process a relationship appears between two fundamental parameters of both metrics. © 1999 American Institute of Physics.
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    Journal of Mathematical Physics 40 (1999), S. 4011-4027 
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    Notes: Five-dimensional (5D) generalized Gödel-type manifolds are examined in the light of the equivalence problem techniques, as formulated by Cartan. The necessary and sufficient conditions for local homogeneity of these 5D manifolds are derived. The local equivalence of these homogeneous Riemannian manifolds is studied. It is found that they are characterized by three essential parameters k, m2, and ω: identical triads (k,m2,ω) correspond to locally equivalent 5D manifolds. An irreducible set of isometrically nonequivalent 5D locally homogeneous Riemannian generalized Gödel-type metrics are exhibited. A classification of these manifolds based on the essential parameters is presented, and the Killing vector fields as well as the corresponding Lie algebra of each class are determined. It is shown that the generalized Gödel-type 5D manifolds admit maximal group of isometry Gr with r=7, r=9, or r=15 depending on the essential parameters k, m2, and ω. The breakdown of causality in all these classes of homogeneous Gödel-type manifolds are also examined. It is found that in three out of the six irreducible classes the causality can be violated. The unique generalized Gödel-type solution of the induced matter (IM) field equations is found. The question as to whether the induced matter version of general relativity is an effective therapy for these types of causal anomalies of general relativity is also discussed in connection with a recent work by Romero, Tavakol, and Zalaletdinov. © 1999 American Institute of Physics.
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    Journal of Mathematical Physics 40 (1999), S. 4035-4055 
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    Notes: We introduce the canonical supermomentum tensors mSikl(P;vt) and gSikl(P;vt) for matter and gravitation, respectively. These tensors give kinds of the quasilocal quantities which have recently been considered in the framework of general relativity though usually constructed in some special cases and for the mass only. Our method to construct the quasilocal quantities (i.e., superenergy and supermomentum tensors) is very general and does not require introducing any supplementary elements into general relativity. It merely extracts covariant data from the suitable canonical objects which exist in the framework of the standard general relativity. Having given a constructive definition of the canonical supermomentum tensors for gravitation and matter, we apply the canonical gravitational supermomentum tensor gSikl(P;vt) for the local analysis of the plane and plane-fronted gravitational waves. Next, we apply the canonical supermomentum tensors gSikl(P;vt) and mSikl(P;vt), gravitation and matter, to local and global analysis of the Friedman, Schwarzschild, and Kerr space–times. We show that the canonical angular supermomentum tensors and integral angular supermomenta have better geometric and physical properties than the canonical objects which describe densities of the angular momenta and integral quantities determined by these densities. © 1999 American Institute of Physics.
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    Journal of Mathematical Physics 40 (1999), S. 4084-4088 
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    Notes: A natural three-dimensional covariant derivative with torsion emerges from the Ashtekar–Barbero connection in the canonical approach to general relativity. The torsion is related to the extrinsic curvature when the Barbero–Immirzi parameter β does not vanish. Alternatively, torsion can be avoided, but at the price of a nonvanishing covariant derivative of the triad field. The properties of both cases are discussed. © 1999 American Institute of Physics.
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    Journal of Mathematical Physics 40 (1999), S. 4072-4083 
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    Notes: A subclass of a recently discovered class of solutions in multidimensional gravity with intersecting p-branes related to Lie algebras and governed by a set of harmonic functions is considered. This subclass in case of three Euclidean p-branes (one electric and two magnetic) contains a cosmological solution to D=11 supergravity related to hyperbolic Kac–Moody algebra F3 (of rank 3). This solution describes the non-Kasner power-law inflation. © 1999 American Institute of Physics.
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    Journal of Mathematical Physics 40 (1999), S. 4099-4105 
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    Notes: It is shown that there exists a one-to-one correspondence between the real solutions of the Einstein vacuum field equations linearized about the Minkowski metric and the (complex) metric perturbations whose curvature to first order in the metric perturbation is self-dual. It is also shown that the self-duality condition of the curvature to first order in the metric perturbation is equivalent to a set of first-order equations for the metric perturbation whose solution is given by a scalar potential that obeys the wave equation. © 1999 American Institute of Physics.
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    Journal of Mathematical Physics 40 (1999), S. 4089-4098 
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    Notes: Prepotentials in N=2 supersymmetric Yang–Mills theories are known to obey nonlinear partial differential equations called Witten–Dijkgraaf–Verlinde–Verlinde (WDVV) equations. In this paper, the prepotentials at the one-instanton level in N=2 supersymmetric SU(4) Yang–Mills theory are studied from the standpoint of WDVV equations. Especially, it is shown that the one-instanton prepotentials are obtained from WDVV equations by assuming the perturbative prepotential and by using the scaling relation as a subsidiary condition but are determined without introducing the Seiberg–Witten curve. In this way, various one-instanton prepotentials which satisfy both WDVV equations and the scaling relation can be derived, but it turns out that among them there exist one-instanton prepotentials which coincide with the instanton calculus. © 1999 American Institute of Physics.
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    Journal of Mathematical Physics 40 (1999), S. 4106-4118 
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    Notes: The singular continuous spectrum of the Liouville operator of quantum statistical physics is, in general, properly included in the difference of the spectral values of the singular continuous spectrum of the associated Hamiltonian. The absolutely continuous spectrum of the Liouvillian may arise from a purely singular continuous Hamiltonian. We provide the correct formulas for the spectrum of the Liouville operator and show that the decaying states of the singular continuous subspace of the Hamiltonian do not necessarily contribute to the absolutely continuous subspace of the Liouvillian. © 1999 American Institute of Physics.
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    Journal of Mathematical Physics 40 (1999), S. 5440-5455 
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    Notes: Recently Jarvis has proved a correspondence between SU(N) monopoles and rational maps of the Riemann sphere into flag manifolds. Furthermore, he has outlined a construction to obtain the monopole fields from the rational map. In this paper we examine this construction in some detail and provide explicit examples for spherically symmetric SU(N) monopoles with various symmetry breakings. In particular we show how to obtain these monopoles from harmonic maps into complex projective spaces. The approach extends in a natural way to monopoles in hyperbolic space and we use it to construct new spherically symmetric SU(N) hyperbolic monopoles. © 1999 American Institute of Physics.
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    Journal of Mathematical Physics 40 (1999), S. 4151-4156 
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    Notes: By Kirillov's theorem, every non-Abelian nilpotent Lie algebra contains the three-dimensional Heisenberg algebra H(3) as a subalgebra. [R. Schimming, Arch. Math. 24, 65–74 (1988)]. Here we are interested in a sufficient condition for a non-nilpotent Lie algebra to contain a subalgebra isomorphic to H(3). Explicitly, we show: Every indecomposable non-nilpotent Lie algebra L of dimension dim L≥3 with a nonvanishing center Z(L)≠{0} contains a non-Abelian nilpotent subalgebra and hence a copy of H(3). © 1999 American Institute of Physics.
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    Journal of Mathematical Physics 40 (1999), S. 4134-4150 
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    Notes: We define a special matrix multiplication among a special subset of 2N×2N matrices, and study the resulting (nonassociative) algebras and their subalgebras. We derive the conditions under which these algebras become alternative nonassociative, and when they become associative. In particular, these algebras yield special matrix representations of octonions and complex numbers; they naturally lead to the Cayley–Dickson doubling process. Our matrix representation of octonions also yields elegant insights into Dirac's equation for a free particle. A few other results and remarks arise as byproducts. © 1999 American Institute of Physics.
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    Journal of Mathematical Physics 40 (1999), S. 4165-4176 
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    Notes: The properties of linear equations on braided linear spaces are investigated and conservation laws for them are derived. The conserved currents are given in the explicit form. The procedure is then applied to scalar wave equations on a quantum plane and on q-Minkowski space. © 1999 American Institute of Physics.
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    Journal of Mathematical Physics 40 (1999), S. 6319-6338 
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    Notes: We classify (1+3)-dimensional Schrödinger equations for a particle interacting with the electromagnetic field that are solvable by the method of separation of variables. As a result, we get 11 classes of the vector potentials of the electromagnetic field A(t,x(vector))=(A0(t,x(vector)),A(vector)(t,x(vector))) providing separability of the corresponding Schrödinger equations. It is established, in particular, that the necessary condition for the Schrödinger equation to be separable is that the magnetic field must be independent of the spatial variables. Next, we prove that any Schrödinger equation admitting variable separation into second-order ordinary differential equations can be reduced to one of the 11 separable Schrödinger equations mentioned above and carry out variable separation in the latter. Furthermore, we apply the results obtained for separating variables in the Hamilton–Jacobi equation. © 1999 American Institute of Physics.
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    Journal of Mathematical Physics 40 (1999), S. 5787-5821 
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    Notes: We show that various models of the elliptic Calogero–Moser systems are accompanied with an isomonodromic system on a torus. The isomonodromic partner is a nonautonomous Hamiltonian system defined by the same Hamiltonian. The role of the time variable is played by the modulus of the base torus. A suitably chosen Lax pair (with an elliptic spectral parameter) of the elliptic Calogero–Moser system turns out to give a Lax representation of the nonautonomous system as well. This Lax representation ensures that the nonautonomous system describes isomonodromic deformations of a linear ordinary differential equation on the torus on which the spectral parameter of the Lax pair is defined. A particularly interesting example is the "extended twisted BCl model" recently introduced along with some other models by Bordner and Sasaki, who remarked that this system is equivalent to Inozemtsev's generalized elliptic Calogero–Moser system. We use the "root-type" Lax pair developed by Bordner et al. to formulate the associated isomonodromic system on the torus. © 1999 American Institute of Physics.
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    Journal of Mathematical Physics 40 (1999), S. 5883-5889 
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    Notes: A K slicing of the Reissner–Nordstrom (RN) spacetime is shown to provide a complete foliation of the region up to the inner horizon, and the horizon to correspond to the limit as K→±∞. The implications of this foliation in the context of York time are discussed. © 1999 American Institute of Physics.
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    Journal of Mathematical Physics 40 (1999), S. 5905-5920 
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    Notes: This paper extends the investigation of the invariants of the Riemann tensor to include the invariants that are of odd degree in the trace-free Ricci tensor. It is shown that these invariants can be expressed in terms of 15 such invariants that are irreducible. As a consequence, it is possible to write down a complete set of invariants of the Riemann tensor. Several syzygies for these invariants have been found and examples of these are given. These syzygies suggest there may be several new syzygies of invariants with even degree in the trace-free Ricci tensor. A large number of these have also been found and are discussed in the paper. © 1999 American Institute of Physics.
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    Journal of Mathematical Physics 40 (1999), S. 5939-5955 
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    Notes: The explicit denominator (normalization) function of the canonical tensor operators of the quantum algebra uq(3), corresponding to the maximal null space case is derived ab initio in terms of double basic hypergeometric series, which cannot be obtained as any q-extension of the SU(3) denominator polynomial Gb″1(Δ,x) in terms of multiple (double or triple) balanced hypergeometric series, introduced by Biedenharn, Louck, and their collaborators (although their q=1 versions are shown being equivalent). The corresponding orthonormal seed isoscalar factors of the coupling (Wigner–Clebsch–Gordan) coefficients of uq(3) and SU(3) with multiple irreducible representations are presented. Conjectured expression of the q-polynomials [which ratios appear in the uq(3) and (new) SU(3) denominator functions for an arbitrary value of the canonical multiplicity label t of the repeating irreducible representations] in terms of multiple partition dependent q-series (extension of the maximal and minimal null space versions) is presented and considered. © 1999 American Institute of Physics.
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    Journal of Mathematical Physics 40 (1999), S. 6689-6691 
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    Notes: We give a simple proof of the Ališauskas–Jucys triple sum formula for Wigner 9j-symbols. © 1999 American Institute of Physics.
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    Journal of Mathematical Physics 40 (1999), S. 6707-6707 
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    Notes: © 1999 American Institute of Physics.
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    Journal of Mathematical Physics 40 (1999), S. 6044-6051 
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    Notes: A general technique is developed for calculating functional determinants of second-order differential operators with Dirichlet, periodic, and antiperiodic boundary conditions, without the knowledge of spectral properties. As an example, we give explicit formulas for a harmonic oscillator with an arbitrary time-dependent frequency, where our result is a generalization of the Gel'fand–Yaglom famous formula for Dirichlet boundary conditions. Our technique is based on the Wronski's construction of Green functions, which does not require spectral knowledge. Our final formula expresses the ratios of functional determinants in terms of an ordinary 2×2 determinant of a constant matrix constructed from two linearly independent solutions of the homogeneous differential equations associated with second-order differential operators. For ratios of determinants encountered in semiclassical fluctuations around a classical solution, the result can further be expressed in terms of the classical solution. Special properties of operators with a zero mode are exhibited. © 1999 American Institute of Physics.
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    Journal of Mathematical Physics 40 (1999), S. 6033-6043 
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    Notes: We make use of the properties of product integrals to obtain a surface product integral representation for the Wilson loop operator. The result can be interpreted as the non-Abelian version of Stokes' theorem. © 1999 American Institute of Physics.
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    Journal of Mathematical Physics 40 (1999), S. 4616-4621 
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    Notes: A precise calculation of the ground-state energy of the complex PT-symmetric Hamiltonian H=p2+〈fraction SHAPE="CASE"〉14x2+iλx3, is performed using high-order Rayleigh–Schrödinger perturbation theory. The energy spectrum of this Hamiltonian has recently been shown to be real using numerical methods. Here we present convincing numerical evidence that the Rayleigh–Schrödinger perturbation series is Borel summable, and show that Padé summation provides excellent agreement with the real energy spectrum. Padé analysis provides strong numerical evidence that the once-subtracted ground-state energy considered as a function of λ2 is a Stieltjes function. The analyticity properties of this Stieltjes function lead to a dispersion relation that can be used to compute the imaginary part of the energy for the related real but unstable Hamiltonian H=p2+〈fraction SHAPE="CASE"〉14 x2−εx3. © 1999 American Institute of Physics.
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    Journal of Mathematical Physics 40 (1999), S. 4658-4663 
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    Notes: An explicit, order-by-order perturbative solution, valid over extended time scales, for the time dependence of operators of anharmonic oscillators, is developed within the framework of the method of normal forms. The freedom of choice of the zeroth-order term and, concurrently in the higher-order corrections, is exploited to develop a minimal normal form (MNF). The expansion for the eigenvalues of the perturbed Hamiltonian in a standard form is independent of the choice. However, the simple form obtained for the time dependence of the perturbative solution is more suitable than any other choice for application to high-lying excited states, as it offers a renormalized form for the propagator. © 1999 American Institute of Physics.
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    Journal of Mathematical Physics 40 (1999), S. 3341-3352 
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    Notes: In this article, Kirchhoff's elasticity theory of rods is revisited but from a viewpoint of Riemannian geometry. By means of the Cayley–Klein parameter, the theory under clamped-end conditions can be regarded as a geometry of paths on some geometrically distorted three-sphere produced by a constrained elastic energy functional. Using this geometric formulation, the uniqueness of elasticae with prescribed initial values of the strains can be easily shown. On the other hand, a family of elasticae with prescribed values of orthonormal frames at two endpoints is demonstrated to be parametrized by an open set in R3. In particular, a criterion of the nonuniqueness of elasticae satisfying clamped-end conditions is given in terms of a geometric concept—conjugate points. © 1999 American Institute of Physics.
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    Journal of Mathematical Physics 40 (1999), S. 3353-3371 
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    Notes: The purpose of this paper is to develop variational integrators for conservative mechanical systems that are symplectic and energy and momentum conserving. To do this, a space–time view of variational integrators is employed and time step adaptation is used to impose the constraint of conservation of energy. Criteria for the solvability of the time steps and some numerical examples are given. © 1999 American Institute of Physics.
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    Journal of Mathematical Physics 40 (1999), S. 4807-4812 
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    Notes: The Landau–Lifshitz equation is derived as a first-order iteration of the Lorentz–Dirac equation for the charged particle. In those cases with null electromagnetic field's gradient, the Landau-Lifshitz gives the so named Herrera equation. A general method for the solution of the latter equation is presented and applied to the motion of a particle in a uniform electromagnetic field. © 1999 American Institute of Physics.
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    Journal of Mathematical Physics 40 (1999), S. 4859-4887 
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    Notes: Let Ω⊂R3 be a bounded simply connected obstacle with boundary ∂Ω locally Lipschitz, we consider the scattering of a time harmonic electromagnetic wave that hits Ω when ∂Ω is assumed to be perfectly conducting. The scattered electromagnetic field is the solution of an exterior boundary value problem for the vector Helmholtz equation. Under suitable hypotheses we prove the existence and uniqueness of the solution of this boundary value problem and we give a new numerical method to compute this solution. The numerical method proposed is based on a perturbative series and is highly parallelizable. Some numerical results obtained with the numerical method proposed on test problems are presented and discussed from the numerical and the physical point of view. © 1999 American Institute of Physics.
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    Journal of Mathematical Physics 40 (1999), S. 4911-4943 
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    Notes: Euclidean and Minkowski four-space uniqueness theorems are derived which yield a new perspective of classical four-vector fields. The Euclidean four-space uniqueness theorem is based on a Euclidean four-vector identity which is analogous to an identity used in Helmholtz's theorem on the uniqueness of three-vector fields. A Minkowski space identity and uniqueness theorem can be formulated from first principles and the space components of this identity turn out to reduce to the three-vector Helmholtz's identity in a static Newtonian limit. A further result is a uniqueness theorem for scalar fields based on an identity which is proved to be a static Newtonian limit of the zeroth or scalar component of the Minkowski space extension of the Helmholtz identity. Last, the three-vector Helmholtz identity and uniqueness theorem and their four-space extensions to Minkowski space are generalized to mass damped fields. © 1999 American Institute of Physics.
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    Journal of Mathematical Physics 40 (1999), S. 4956-4974 
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    Notes: Uniqueness of Gibbs states in the one-dimensional antiferromagnetic model with very long-range interaction is established. © 1999 American Institute of Physics.
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    Journal of Mathematical Physics 40 (1999), S. 5026-5057 
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    Notes: The existence of superintegrable systems with n=2 degrees of freedom possessing three independent globally defined constants of motion which are quadratic in the velocities is studied on the two-dimensional sphere S2 and on the hyperbolic plane H2. The approach used is based on enforcing the conditions for the existence of two independent integrals (further than the energy). This is done in a way which allows us to discuss at once the cases of the sphere S2 and the hyperbolical plane H2, by considering the curvature κ as a parameter. Different superintegrable potentials are obtained as the solutions of certain systems of two κ-dependent second order partial differential equations. The Euclidean results are directly recovered for κ=0, and the superintegrable potentials on either the standard unit sphere (radius R=1) or the unit Lobachewski plane ("radius" R=1) appear as the particular values of the κ-dependent superintegrable potentials for the values κ=1 and κ=−1. Some new superintegrable potentials are found, both on S2 and H2. The correspondence between superintegrable systems in spaces of zero and nonzero curvature is discussed. © 1999 American Institute of Physics.
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    Journal of Mathematical Physics 40 (1999), S. 5092-5105 
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    Notes: A qualitative analysis is presented for a class of homogeneous cosmologies derived from the string effective action when a cosmological constant is present in the matter sector of the theory. Such a term has significant effects on the qualitative dynamics. For example, models exist which undergo a series of oscillations between expanding and contracting phases due to the existence of a heteroclinic cycle in the phase space. Particular analytical solutions corresponding to the equilibrium points are also found. © 1999 American Institute of Physics.
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    Journal of Mathematical Physics 40 (1999), S. 5117-5130 
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    Notes: This is the first part of a series of two papers. In this article we study the linearization stability of the Einstein equation in the presence of matter. We have slightly changed the classic definition of this concept for the vacuum spacetime and a more general one adapted to our case is given. We consider a Robertson–Walker model (V,g,T) where V stands for the spacetime, g for a Robertson–Walker metric, and T for a stress-energy tensor of a perfect fluid. We write V=S×I where S is a spacelike hypersurface of V and I an R-interval. We show that in the case S has a constant curvature K equal to 0, the Einstein equation G(g)=χT is linearization stable at g. In a subsequent paper we shall prove that in the case K=1 the opposite occurs. The case K=−1 remains as an open question. © 1999 American Institute of Physics.
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    Journal of Mathematical Physics 40 (1999), S. 5157-5183 
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    Notes: The properties of the effective σ-model for D-dimensional Einstein gravity based on multidimensional geometries is analyzed. Besides pure geometry additional minimally coupled scalars and (p+2)-forms are considered which yield an extended target space after reduction to the effective D0-dimensional geometry. The target space is always a homogeneous space. Exact solutions exist provided an orthobrane condition is satisfied which geometrically makes the target space a locally symmetric one. New solutions with scalar fields are found which may inflate not only in time-like but in also in additional spatial directions of the effective geometry. Static spherically symmetric solutions with a particular configuration of intersecting electric and magnetic branes are investigated both, for the orthobrane case and for degenerated charges. In both cases TH depends critically on the intersection dimension of the branes. Finally, the role of the Einstein frame for 4-geometries is addressed, and the physical frame transformation for cosmological geometries is given. © 1999 American Institute of Physics.
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    Journal of Mathematical Physics 40 (1999), S. 5283-5283 
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    Notes: © 1999 American Institute of Physics.
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    Journal of Mathematical Physics 40 (1999), S. 12-18 
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    Notes: An exact stochastic model for the thermalization of quantum states is proposed. The model has various physically appealing properties. The dynamics are characterized by an underlying Schrödinger evolution, together with a nonlinear term driving the system toward an asymptotic equilibrium state and a stochastic term reflecting fluctuations. There are two free parameters, one of which can be identified with the heat bath temperature, while the other determines the characteristic time scale for thermalization. Exact expressions are derived for the evolutionary dynamics of the system energy, the system entropy, and the associated density operator. © 1999 American Institute of Physics.
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    Journal of Mathematical Physics 40 (1999), S. 101-122 
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    Notes: Square and circular infinite wells are among the simplest two-dimensional potentials which can completely solved in both classical and quantum mechanics. Using the methods of periodic orbit theory, we study several variants of these planar billiard systems which admit both singular isolated and continuous classes of nonisolated periodic orbits. (In this context, isolated orbits are defined as those which are not members of a continuous family of paths whose orbits are all of the same length.) Examples include (i) various "folded" versions of the standard infinite wells (i.e., potentials whose geometrical shapes or "footprints" can be obtained by repeated folding of the basic square and circular shapes) and (ii) a square well with an infinite-strength repulsive δ-function "core," which is a special case of a Sinai billiard. In each variant case considered, new isolated orbits are introduced and their connections to the changes in the quantum mechanical energy spectrum are explored. Finally, we also speculate about the connections between the periodic orbit structure of supersymmetric partner potentials, using the two-dimensional square well and it superpartner potential as a specific example. © 1999 American Institute of Physics.
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    Journal of Mathematical Physics 40 (1999), S. 169-187 
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    Notes: The language of differential forms and topological concepts are applied to study classical electromagnetic theory on a lattice. It is shown that differential forms and their discrete counterparts (cochains) provide a natural bridge between the continuum and the lattice versions of the theory, allowing for a natural factorization of the field equations into topological field equations (i.e., invariant under homeomorphisms) and metric field equations. The various potential sources of inconsistency in the discretization process are identified, distinguished, and discussed. A rationale for a consistent extension of the lattice theory to more general situations, such as to irregular lattices, is considered. © 1999 American Institute of Physics.
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    Journal of Mathematical Physics 40 (1999), S. 188-209 
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    Notes: Integrable systems in low dimensions, constructed through the symmetry reduction method, are studied using phase portrait and variable separation techniques. In particular, invariant quantities and explicit periodic solutions are determined. Widely applied models in Physics are shown to appear as particular cases of the method. © 1999 American Institute of Physics.
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    Journal of Mathematical Physics 40 (1999), S. 256-278 
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    Notes: An ideal fluid whose internal energy depends on density, density gradient, and entropy is considered. Dynamic equations are integrated, and a description in terms of hydrodynamic (Clebsch) potentials occurs. All essential information on the fluid flow (including initial and boundary conditions) appears to be carried by the dynamic equations for hydrodynamic potentials. Information on initial values of the fluid flow is carried by arbitrary integration functions. Initial and boundary conditions for potentials contain only nonessential information concerning the fluid particle labeling. It is shown that the description in terms of n-component complex wave function is a kind of such description in terms of hydrodynamic potentials. Spin determined by the irreducible number nm of the wave function components appears to be an attribute of the fluid flow. Classification of fluid flows by the spin appears to be connected with invariant subspaces of the relabeling group. © 1999 American Institute of Physics.
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    Journal of Mathematical Physics 40 (1999), S. 353-368 
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    Notes: The automorphism group and frame commutator relations in the orthonormal frame approach to Bianchi cosmology are used to construct an explicit coordinate representation of the orthonormal frame itself (and hence of the spacetime metric) which depends algebraically on the connection coefficients. This is not possible in general inhomogeneous models where differential equations must instead be solved. The shift vector field required for this procedure is intimately related to the true Smarr–York minimal strain and minimal distortion shifts. © 1999 American Institute of Physics.
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    Journal of Mathematical Physics 40 (1999), S. 408-426 
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    Notes: We show that a left-rigid monoidal C* category with irreducible monoidal unit is also a sovereign and spherical category. Defining a Frobenius–Schur-type indicator we obtain selection rules for the fusion coefficients of irreducible objects. As a main result we prove S4 invariance of 6j symbols in such a category. © 1999 American Institute of Physics.
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    Journal of Mathematical Physics 40 (1999), S. 454-479 
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    Notes: We give the definition of a line bundle over the Brownian bridge by using its section. This allows us to define a Hilbert space of sections of a line bundle over the Brownian bridge associated to the transgression of a representative of an element of H3(M;Z). We consider the case of a string structure over the Brownian bridge: this allows us to define a Hilbert space of spinor fields over the Brownian bridge, when the first Pontryaguin class of the spin bundle over the manifold is equal to 0. © 1999 American Institute of Physics.
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    Journal of Mathematical Physics 40 (1999), S. 5106-5116 
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    Notes: An Euclidean approach for investigating quantum aspects of a scalar field living on a class of D-dimensional static black hole space–times, including the extremal ones, is reviewed. The approach makes use of a near-horizon approximation of the metric and ζ-function formalism for evaluating the partition function and the expectation value of the field 〈φ2(x)〉. After a review of the nonextreme black hole case, the extreme one is considered in some detail. In this case, there is no conical singularity, but the finite imaginary time compactification introduces a cusp singularity. It is found that the ζ-function regularized partition function can be defined, and the vacuum expectation value of the field, is finite on the horizon, as soon as the cusp singularity is absent, namely, the manifold is smooth and the corresponding temperature is T=0. It is suggested that the requirement of having a smooth near-horizon geometry always selects the correct black hole equilibrium temperature. © 1999 American Institute of Physics.
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    Journal of Mathematical Physics 40 (1999), S. 5184-5202 
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    Notes: Let (P,V) be an irreducible imprimitivity system for a group H based on a dual group  of an Abelian group A and acting on a Hilbert space H. Given ψ∈H, we find necessary and sufficient conditions in order that the set of vectors {∫Â〈â,a〉Vh−1 dP(â)ψ : a∈A, h∈H} be a frame in H. Moreover, we apply these results to some examples that are considered in the literature in the context of square-integrability modulo a coset space. © 1999 American Institute of Physics.
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    Journal of Mathematical Physics 40 (1999), S. 5203-5223 
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    Notes: We present the general solution of the system of coupled nonlinear equations describing dynamics of D-dimensional bosonic string in the geometric (or embedding) approach. The solution is parametrized in terms of the left- and right-moving Lorentz harmonic variables providing a special coset space realization of the product of two (D−2)-dimensional spheres SD−2=[SO(1,D−1)/SO(1,1)×SO(D−2)(semidirect product)KD−2]. © 1999 American Institute of Physics.
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    Journal of Mathematical Physics 40 (1999), S. 71-92 
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    Notes: In relativistic Schrödinger theory the mixtures and pure states can be treated from a unified point of view such that a pure state merely emerges as a special case of a mixture. Here the concept of mixture is of purely local nature and therefore the mixture character (degree of order) can change over space and time. Although the general dynamics does not forbid the transitions from mixtures to pure states (and vice versa), the considered models do admit these transitions only in an asymptotic sense. The general concepts and results are demonstrated by considering the four-component Dirac theory for spinning matter over the Robertson–Walker universes. A detailed study is made for a specific subclass of second-order mixtures sharing many of their properties with the pure states (i.e., wave functions). © 1999 American Institute of Physics.
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    Journal of Mathematical Physics 40 (1999), S. 93-100 
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    Notes: The topologically nontrivial correspondence between the 5D SU(2)-Kepler problem and the 8D singular oscillator is considered. It is shown that both "isospinor" and "isovector" particles on the SU(2) instanton + 1/R background in 5D can be described in terms of an 8D singular oscillator. The energy spectrum is calculated for an arbitrary "isospin" case. © 1999 American Institute of Physics.
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    Journal of Mathematical Physics 40 (1999), S. 369-382 
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    Notes: We prove an extension of the result on the inverse Laplace transform. This extension will help toward making the applications of Borel techniques to perturbation theory in Quantum Field Theories be placed on a more rigorous foundation. © 1999 American Institute of Physics.
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    Journal of Mathematical Physics 40 (1999), S. 501-510 
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    Notes: The involutive automorphisms of hyperbolic Kac–Moody algebras are computed from Satake diagrams of these algebras which are then used to furnish a general procedure of their Iwasawa decomposition. In particular Â1(1) and Â2(1) are considered as representative examples to illustrate the efficacy of the underlying treatment. © 1999 American Institute of Physics.
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    Journal of Mathematical Physics 40 (1999), S. 64-70 
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    Notes: Using improper Riemann integrals, we will formulate a rigorous version of the real-time, time-sliced Feynman path integral for the L2 transition probability amplitude. We will do this for nonvector potential Hamiltonians with potential which has, at most, a finite number of discontinuities and singularities. We will also provide a Nonstandard Analysis version of our formulation. © 1999 American Institute of Physics.
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    Journal of Mathematical Physics 40 (1999), S. 2735-2756 
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    Notes: The supersymmetric descent equations in N=1 superspace are discussed by means of the introduction of two operators ζα,ζ¯α(overdot), which allow to decompose the supersymmetric covariant derivatives Dα,D¯α(overdot) as BRS commutators. © 1999 American Institute of Physics.
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    Journal of Mathematical Physics 40 (1999), S. 2757-2781 
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    Notes: We discuss Bloch and Wannier functions related to oscillator eigenfunctions. In particular, we construct complete sets of mutually orthogonal Bloch and Wannier functions. We show that they can be expressed in several ways in terms of theta functions and their derivatives. We also analyze their localization properties and discuss expectation values for specifically chosen Hamiltonians. © 1999 American Institute of Physics.
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    Journal of Mathematical Physics 40 (1999), S. 2782-2804 
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    Notes: The Lie point symmetries of a coupled system of two nonlinear differential-difference equations are investigated. It is shown that in special cases the symmetry group can be infinite dimensional, in other cases up to ten dimensional. The equations can describe the interaction of two long molecular chains, each involving one type of atoms. © 1999 American Institute of Physics.
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    Journal of Mathematical Physics 40 (1999), S. 2805-2815 
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    Notes: A theory of stochastic flows over the algebra of observables of a dynamical system is presented in which the main objective is to ensure that the overall canonical/symplectic structure on the algebra is preserved. We study both classical and quantum systems and the importance of physical interpretation in the Stratonovich interpretation is stressed. We find the natural formulation of quantum dissipative systems to be given in terms of quantum stochastic calculus. This treatment allows for a physically meaningful treatment of both constant and nonlinear dissipation. As an application, we quantize a mechanical system with the same nonlinear damping mechanism as the van der Pol oscillator. © 1999 American Institute of Physics.
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    Journal of Mathematical Physics 40 (1999), S. 3035-3052 
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    Notes: We derive an asymptotic solution of the Einstein field equations which describes the propagation of a thin, large amplitude gravitational wave into a curved space–time. The resulting equations have the same form as the colliding plane wave equations without one of the usual constraint equations. © 1999 American Institute of Physics.
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