bluuebunny/crossref_metadata_2025_split huggingface dataset:
IR Spectroscopic Study of the Mixed Crystal System (LixAg1‐x)NO3
Authors: El‐Kabbany F. , Taha S. , Tosson M. 
Published: May 2007

AbstractA spectroscopic analysis of the various IR internal modes for the mixed crystal system of lithium nitrate and silver nitrate were carried out. The study aims mainly to find out the effect of partial replacement of Ag+ ion by Li+ ion on the internal fundamental modes of vibrations of the NO3− group in both of the ordering and disordering states of these two metallic nitrate compounds.The characteristic variations observed are attributed to differences in polarizability from cationic sphere around the nitrate group. An interesting increase of the maximum frequency observed on passing from pure components to mixtures is attributed to a change in force constant.
On the Epistemological Status of Cosmology Anthropic Principle, Cosmological Numbers, and the Subject of Cosmology
Authors: Wahsner Renate 
Published: May 2007

AbstractIt is shown that cosmology destroys the fundamental on which it lies as a natural‐scientific discipline if it introduces subjectivistic principles as one of them is the so‐called Anthropic Principle that superseds the Copernican turn of sciences. Likewise conceptions are proved as conceptions that contradict the physical cosmology which conceive that the “World harmony” or the physical‐uniform grasping of the world can be derived from numbers or relations of numbers. This is due to the fact that these conceptions liquadate the advantage of physics to get via measurements statements about reality.
Erzwingt die Quantenmechanik eine drastische Änderung unseres Weltbilds? Gedanken und Experimente nach Einstein, Podolsky und Rosen
Authors: Frodl Peter 
Published: May 2007

AbstractVon den Anfängen der Quantenmechanik bis heute gibt es Versuche, sie als statistische Theorie über Ensembles individueller ‚klassischer’︁ Systeme zu interpretieren. Die Bedingungen, unter denen Theorien verborgener Parameter zu deterministischen Beschreibungen dieser individuellen Systeme als ‚klassisch’︁ angesehen werden können, wurden von Einstein, Podolsky und Rosen 1935 formuliert: 1. Physikalische Systeme sind im Prinzip separierbar. 2. Zu jeder physikalischen Größe, deren Wert man ohne Störung des betrachteten Systems mit Sicherheit voraussagen kann, existiert ein ihr entsprechendes Element der physikalischen Realität.Zusammen sind sie, wie Bell 1964 gezeigt hat, prinzipiell unverträglich mit der Quantenmechanik und unhaltbar angesichts neuerer Experimente. Diese erweisen einmal mehr die Quantenmechanik als richtige Theorie. Um ihre Ergebnisse zu verstehen, müssen wir entweder die in der klassischen Physik als selbstverständlich angesehene Annahme der Separierbarkeit physikalischer Systeme aufgeben oder unseren Begriff der physikalischen Realität revidieren. Eine Untersuchung des Begriffs der Separabilität und einige Überlegungen zum Problem der Messung von Observablen zeigen, daß eine Änderung des Begriffs der physikalischen Realität unumgänglich ist. Der revidierte Realitätsbegriff sollte mit klassischer Physik und Quantenmechanik verträglich sein, um ein einheitliches Weltbild zu ermöglichen.
On Causal Disjointness Relations and Causal Nets of Algebras on the Lattice ℤn+1
Authors: Baumgaertel H. 
Published: May 2007

AbstractThis mathematical paper reviews basic facts on nets of algebras on lattices. Causal disjointness relations on the lattice ℤn+1 are represented. The relation is cleared between causal disjointness and orthogonality. A CAR‐algebra is represented.
Rational Conformal Field Theories and Zamolodchikov‐Fateev Parafermions
Authors: Paunov Roman , Todorov Ivan 
Published: May 2007

AbstractThe charged fields in a local chiral algebra with a (single) U(1)‐current appear, in general, as tensor products of a U(1)‐vertex operator and a (generalized) parafermionic current of the type introduced by Zamolodchikov and Fateev in 1985. Inequalities among parafermionic conformal weights Δv are established without any assumption about Hilbert space positivity. In a theory with a unique zero energy (vacuum) state and a non‐degenerate inner product we deduce the non‐negativity of Δv. It is shown that if the reduced theories coincide with the standard Zx parafermions
equation image
the local extensions of the U(1)‐conformal current algebra are given by the coset space construction SU(2)x X U(1)/U(1) with appropriate levels of the U(1) algebras.
Die Elementarkonstanten und die Mathematik
Authors: Rompe Robert , Treder Hans‐Jürgen 
Published: May 2007

AbstractDie Elementarkonstanten im Sinne von Max Planck sind von ähnlicher Bedeutung wie die reinen Zahlen der Mathematik. Die Newtonschen Prinzipien und die Elementarkonstanten zusammen sind der Grundbau der physikalischen Theoriebildung.
The Functional Integral on the Lattice Gauge Orbit Space
Authors: Rudolph Gerd 
Published: May 2007

AbstractWe construct a complete set of lattice invariants for the bosonic sector of the Georgi‐Glashow model and propose a lattice approximation of the physical action in terms of these invariants. In particular, we describe topologically non‐trivial configurations on the lattice level. Finally, we give a lattice approximation of the functional integral measure in terms of invariants, which enables us to formulate the functional integral on the lattice gauge orbit space.
Construction of Local and Non‐Local Conservation Laws for Non‐Linear Field Equations
Authors: Vladimirov V. S. , Volovich I. V. 
Published: May 2007

AbstractA method of constructing conserved currents for non‐linear field equations is presented. More explicitly, for non‐linear equations, which can be derived from compatibility conditions of some linear system with a parameter, a procedure of obtaining explicit expressions for local and non‐local currents is developed. Some examples including the supersymmetric Yang‐Mills theory are considered.
Symplectic Formalism for the Thermodynamics of Irreversible Processes
Authors: Vojta G. 
Published: May 2007

AbstractThe fundamentals of a Lagrangian and Hamiltonian formalism for the thermodynamics of irreversible processes are developed. An abstract frame for linear and nonlinear processes is formulated in the Onsager scheme for discontinuous systems. It is always possible to construct a locally defined nondegenerate symplectic structure which is characterized by the entropy production. As an example, thermodynamic systems with kinetic energy possessing evolution equations with time derivatives of second order are treated in the Onsager‐Machlup formulation. Modifications of the formalism by complexification of the thermodynamic phase space and introduction of a Kähler manifold are discussed.
A Riemann‐Hilbert Approach to the Inverse Problem for Three Dimensional Heisenberg Spin‐Chain
Authors: Chowdhury A. Roy , Mitra Pritha 
Published: May 2007

AbstractThree dimensional Heisenberg Spin Chain along with the Tjon‐Wright ansatz admit a Lax pair with pole in the eigenvalue plane. We have developed the corresponding inverse problem through the technique of Riemann‐Hilbert approach. The analytic structure is determined through the reduction technique, associated with the Lax pair.
First Order Approximation of the 5‐dimensional Projective Unified Field Theory
Authors: Schmutzer E. , Kroll P. 
Published: May 2007

AbstractThe new version of a 5‐dimensional Projective Unified Field Theory is presented up to the first order approximation with respect to the gravitational constant and referring to nonrelativistic velocities. Since exact solutions of this theory can only be found for exceptional cases, this approximation procedure provides a practicable approach to physical applications of the theory.
Elementary Constants of Nature
Authors: Hantzsche E. 
Published: May 2007

AbstractElementary constants of nature play a decisive role in physics, though they are not taken notice in most physical investigations, compared with the much more interesting variables: They are normally regarded as a kind of self‐evident ingredients or accessories of physical laws. However, from a more general point of view such a neglect is not justified. In this commenting paper several aspects of the occurrence, the meaning and measurement, of the origin, the character and the properties of elementary constants are discussed, as well as the use of such constants to define “natural” unit systems. The question of variability is mentioned, and finally the deep roots of fundamental constants in nature are emphasized.
Lifetime‐Measurements of Selectively Excited Molecular Levels
Authors: Bieniak B. , Hinske H. P. , Paulus H. , Zevgolis D. , Demtröder W. 
Published: May 2007

AbstractA synchroneously pumped mode‐locked cavity‐dumped dye laser, which delivers nearly Fourier‐limited output pulses with 20 W peak power, 500 ps pulsewidth and 1.5 GHz spectral bandwidth is used to populate selected rovibronic levels in excited electronic states of alkali molecules. The laser induced fluorescence is filtered through a monochromator and the lifetimes of individual rovibronic levels are determined with the single photon delayed coincidence technique. The influence of different perturbations on the lifetimes is investigated and discussed.
A 12‐GHz Standard Clock on Trapped Ytterbium Ions
Authors: Casdorff R. , Enders V. , Blatt R. , Neuhauser W. , Toschek P. E. 
Published: May 2007

AbstractThe ground‐state hyperfine transition ΔmF = 0 of trapped Yb+ ions has been measured as 12642812119.6 (0.4) Hz. The frequency instability of a microwave, controlled by this resonance, is characterised by the standard deviation 2·10−11· (τ/sec)−1/2, where τ is the time separation of probes. The performance of this frequency standard or “clock” exceeds the stability of commercial cesium clocks and still offers major potential for improvement.
Semiclassical Coupled Channels Theory
Authors: Grawert G. , Müller St. 
Published: May 2007

AbstractA semiclassical theory for heavy ion scattering in the Fresnel diffraction regime covering coupled elastic and inelastic channels is developed. The scattering is described as diffraction off the rainbow trajectory along which the development of the internal degrees of freedom is calculated. Simple formulae for the transition amplitudes are derived and interpreted in terms of matching conditions, time scales and potential strengths at closest approach. Polarization potentials comprising of real and absorptive terms and of tensors of various ranks are constructed. Analyzing power data for elastic and inelastic scattering of polarized 7Li on 120Sn are analyzed.
Theoretical Analysis of the Einstein Relation in n‐Channel Inversion Layers on A3IIB2V Semiconductors under Magnetic Quantization
Authors: Ghatak K. P. , Mitra B. , Mondal M. 
Published: May 2007

AbstractWe have investigated the Einstein relation in n‐channel inversion layers on A3IIB2V semiconductors at low temperatures on the basis of a newly derived dispersion relation of the carriers under arbitrary magnetic quantization for the general case which occurs from the consideration of the anisotropies of the band parameters within the frame work of k · p formalism. It is found by incorporating both the effects of electron spin and broadening of Landau levels, using n‐Cd3As2 as an example, that the theoretical formulation is in qualitative agreement with the suggested experimental method of determining the Einstein relation in degenerate semiconductors having arbitrary dispersion law. In addition, the corresponding well‐known results for bulk specimens of two band Kane model both in the presence and absence of magnetic quantization, are also obtained from the generalized expressions as special cases.
Relativistic Single Particle Kinetic Theory
Authors: Long David G. 
Published: May 2007

AbstractSingle particle kinetic theory is the study of the dynamics of a single particle moving through a medium. The only mechanism for change in this theory is through two‐body collisions between the single particle and the particles of the medium given by the collision term of Boltzmann's equation in kinetic theory. This article contains a summery of relativistic dynamics and a method of projecting the relativistic dynamical system into phase space. This enables us to express relativistic kinetic theory in terms of phase space variables and also to apply the techniques of approximation in the non‐relativistic theory to the relativistic domain.
Quasiclassical 1/N Energy‐Formulas for Relativistic Two‐Body Systems
Authors: Papp E. 
Published: May 2007

AbstractQuickly tractable energy‐formulas for relativistic two‐body systems are established to first 1/N‐order in terms of general classical Hamiltonians (m1 ≥ m2). Arbitrary spherically‐symmetrical vector and/or scalar potentials are assumed. Such Hamiltonians, which have to be converted into related non‐relativistic ones, play the role of a dominant zeroth‐order approximation (an exact description) in the case of two fermions (two bosons). Proofs have also been given that the 1/N‐method is quite suitable for the systematic description of order‐dependent contributions to the energy of Coulomb‐Bethe‐Salpeter systems, now to α6‐order.
Die quantenmechanische Interpretation der allgemeinkovarianten Dirac‐Gleichung und die 8‐parametrische Gruppe der Spinor‐Transformationen
Authors: Gorbatsievich A. K. 
Published: May 2007

AbstractEs wird die bezüglich der im allgemeinen nicht unimodularen Spinor‐Transformationen kovariante Dirac‐Gleichung untersucht. Es wird gezeigt, daß diese Gleichung selbst in kartesischen Koordinaten in der flachen Raum‐Zeit nur dann als eine Ortsdarstellung der quantenmechanischen Bewegungsgleichungen in einem abstrakten Hilbertraum interpretiert werden kann, wenn die diese Darstellung realisierenden Hilbertraum‐Basisvektoren nicht orthonormiert sind.
Self‐Consistent Calculations of Landau Levels for Symmetric p‐Type Inversion Layers
Authors: Latussek V. , Bangert E. , Landwehr G. 
Published: May 2007

AbstractA method for calculating the Landau levels of symmetric p‐type inversion layers is presented. Using the envelope function approach in the Hartree approximation the magnetic field is incorporated into the Hamiltonian. In order to characterize the energy levels and to obtain a detailed understanding of the unusual Landau scheme, an analysis of the wave functions is made. Special effects are discussed for the inversion layers adjacent to the grain boundary of a Ge‐bicrystal, with two occupied subbands. The simulation of Shubnikov‐de Haas data by a density of states analysis shows that the different oscillatory periods are not directly related to the subband occupations.
Resonances and Gamow States in Non‐Local Potentials
Authors: Mondragon A. , Hernandez E. , Arcos J. M. Velazquez 
Published: May 2007

AbstractFor a large class of non‐local, non separable potentials with non‐compact support, the solution of the radial integrodifferential equation may be reduced to the solution of a homogeneous linear integral equation of Fredholm type with a quadratically integrable kernel. In this way we derive expansions of the wave functions and the Green's function of the Schrödinger equation with a non‐local potential in terms of bound states, resonant states and a continuum of scattering functions with complex wave number. The rules of normalization, orthogonality and completeness satisfied by the eigenstates of the Schrödinger equation belonging to complex eigenvalues with Im En < 0, (Gamow or resonant states) are also derived. Finally, by means of a realistic example, it is shown how to use these expansions to exhibit the resonant behaviour of the differential cross section. Explicit expressions for the transition amplitudes and the partial widths in terms of expectation values of operators computed with Gamow functions are given.
Several large‐scale superperiodicities on highly oriented pyrolytic graphite observed by scanning tunneling microscopy
Authors: Yang X. , Bromm Ch. , Geyer U. , von Minnigerode G. 
Published: May 2007

AbstractOn freshly cleaved highly oriented pyrolytic graphite we observed large‐scale superperiodicities by a scanning tunneling microscope at room temperature in air. Several hexagonal superstructures with periods of 30 nm, 4.2 nm, 2.4 nm, and 2.0 nm, respectively, and a strip‐like superstructure with a period of 1 nm were obtained. With exception of the largest hexagonal superperiodicity (30 nm spacing), all other superstructures are superimposed on the atomic corrugation of graphite. The origin of these superstructures is not clear yet. We assume that they arise from crystal defects in graphite. The hexagonal superstructure may be caused by the Moiré effect due to the rotational misorientation of the two top layers or of two successive layers near the surface.
A variational treatment of the periodic Anderson model with antiferromagnetic order
Authors: Brenig W. , Müller‐Hartmann E. 
Published: May 2007

AbstractWe discuss a variational ground state wave function for the symmetric periodic Anderson model with commensurate spin density order. The energy of this ansatz is evaluated in closed form. Our approach generalizes a variational treatment proposed recently by Strack and Vollhardt and results in significantly lower energy. Contrary to the Gutzwiller ansatz the wave function recovers the Schrieffer‐Wolff limit for large Coulomb repulsion. We clarify the relation of our approach to unrestricted Hartree‐Fock and present a comparison with existing quantum Monte Carlo calculations for one dimension.
On a simple formula for the energy of the lowest octupole state
Authors: Zamfir N. V. , von Brentano P. , Casten R. F. 
Published: May 2007

AbstractA recently introduced way of parameterizing the energies of 3 states in many even‐even nuclei, based on the microscopic structure of the low‐energy octupole mode, is slightly modified so it now includes all (non‐doubly magic) nuclei with A ⩾ 30.
Generalized conformal invariance conditions on a sigma model of the open bosonic string including the first massive mode
Authors: Förste S. 
Published: May 2007

AbstractConformal invariance conditions on a sigma model of the open bosonic string including the tachyon, the abelian gauge field an the first excited massive mode are calculated up to order a′. Inner symmetries are used to compute conformal invariance conditions from renormalization group beta functions.
Corner transfer matrix study of an inhomogeneous Ising model
Authors: Peschel Ingo , Wunderling Roland 
Published: May 2007

AbstractWe consider a planar Ising model with an extended defect described by couplings of the form K(r) = K·(1 + A/r). We determine the spectrum of the corner transfer matrix numerically and analytically and use it to calculate the local magnetization at the defect and the corresponding, non‐universal critical exponent.
Migdal‐Kadanoff renormalization of a nonlinear supervector model with hyperbolic symmetry
Authors: Drunk W. , Fuchs D. , Zirnbauer M. R. 
Published: May 2007

AbstractThe Migdal‐Kadanoff approximation is applied to a nonlinear σ model with fields taking values in a perfectly graded noncompact superspace G/K of rank one. It is shown how to implement the spherical transform for this model space numerically in a controlled manner. The correlation length exponent ν, and the dimensions of a series of G‐invariant scaling operators at the fixed point, are computed for 2 < d ⩽ 3. No perturbative instability of the type found by Kravtsov et al. and Wegner is observed.
Hyperfine interactions of 111Cd in TiO2 (Rutile) studied by perturbed angular correlations
Authors: Wenzel Th. , Bartos A. , Lieb K. P. , Uhrmacher M. , Wiarda D. 
Published: May 2007

AbstractThe time‐differential perturbed angular correlation for 111Cd nuclei has been measured after 111In implantation into polycrystalline TiO2. The observed perturbation functions are characterized by a well‐defined electric field gradient with the quadrupole coupling constant νQ = 105(1) MHz and the asymmetry parameter η = 0.18(1). We attribute these hyperfine parameters to 111Cd on the (distorted) substitutional cation site in rutile. The PAC results are compared with those in SnO2 rutile as well as with X‐ray diffraction, RBS channeling experiments and point charge model calculations including relaxation of the probe atom surrounding.
A note on Δn ≠ 0 Stark transitions in hydrogenlike atoms
Authors: Kretzschmar Martin , Steinmetz Andreas 
Published: May 2007

AbstractIn a gaseous helium or hydrogen target slow muons or antiprotons are captured into orbits with a high principal quantum number (n = 15 to 50) to form (μ− α)+ ions, (pα)+ ions, or (pp) atoms respectively. In the subsequent deexcitation process Stark mixing of the intermediary states plays an important role. The successful Mainz Cascade Model assumed Δn = 0 for the Stark transitions, although formally no such selection rule exists. This note examines the reasons why Δn ≠ 0 Stark transitions play only a negligible role in the deexcitation cascade.
Spinfluctuations versus phonons: The case of Heavy‐Fermion superconductivity
Authors: Welslau B. , Grewe N. 
Published: May 2007

AbstractSuperconductivity of Heavy‐Fermions, with an emphasis on hexagonal UPt3, is investigated microscopically on the basis of the LNCA‐approximation for strongly correlated electrons in a Kondo lattice and of Eliashberg theory for anisotropic singlet and triplet superconducting order. The effective interaction kernel incorporates exchange of spin fluctuations carried by strongly renormalized particle‐hole excitations as well as exchange of phonons generated by the breathing mechanism. Particular care is taken to include realistic anisotropies in band structure and couplings and to expand interaction kernel and order parameter in appropriate Fermi surface harmonics. Separate interactions and corresponding gap equations are used for pseudo‐spin‐singlet and ‐triplet channel, with a restriction to the case of weak spin‐orbit coupling. Our main results include a detailed study of phonon‐ and spin‐fluctuation mechanisms as a possible source for superconductivity and, in combination, their mutual influence and competition. Furthermore, the questions regarding singlet or triplet order, conventional or unconventional symmetry, order parameter zeros and phase transitions between different superconducting states are addressed. We propose a possible scenario of Heavy‐Fermion superconductivity.
3D‐solitons in a strongly magnetized plasma: Transition from flat to spherical waves of the Zakharov‐Kuznetsov equation
Authors: Murawski K. 
Published: May 2007

AbstractThe Zakharov‐Kuznetsov equation has been used to describe ion‐acoustic wave propagation in a strong magnetic plasma. An initial‐value problem has been solved for this equation on the basis of a numerical method that uses the fast Fourier transform technique for calculating space derivatives and a fourth order Runge‐Kutta method for the time scheme. Numerical simulations have shown that the disturbed flat solitary waves can break up into spherical ones.
Magnetic‐field‐induced damage in a superconducting YBa2Cu3O7−x film
Authors: Brüll P. , Kirchgässner D. , Leiderer P. , Berberich P. , Kinder H. 
Published: May 2007

AbstractDuring investigations of the magnetic flux dynamics in thin superconducting YBa2Cu3O7−x films we have observed the spontaneous formation of a damage in the film, apparently induced by the applied magnetic field of 0.1 T. The damage developed within less than 40 ms (the time resolution of the experiment) and showed up in the magnetiooptically recorded image of the flux above the sample as a path for massive flux penetration. A subsequent analysis revealed a 1 μm wide gap in the YBa2Cu3O7−x film which had developed over a major portion of the 1 · 1 cm2 sample. It is suggested that the film locally melted as a result of an instability of the superconductor in the critical state.