bluuebunny/crossref_metadata_2025 huggingface dataset:
RECURSION RELATIONS IN SEMIRIGID TOPOLOGICAL GRAVITY
Authors: WONG EUGENE
Published: November 2004

A field theoretical realization of topological gravity is discussed in the semirigid geometry context. In particular, its topological nature is given by the relation between de Rham cohomology on the moduli space and equivariant BRST cohomology on the Hilbert space and the fact that all but one of the physical operators are BRST exact. The puncture equation and the dilaton equation of pure topological gravity are reproduced, following Ref. 1.
PATH INTEGRALS AND PERTURBATIVE EXPANSIONS FOR NONCOMPACT SYMMETRIC SPACES
Authors: LINDEN NOAH , PEFIRY MALCOLM J.
Published: November 2004

We show how to construct path integrals for quantum-mechanical systems where the space of configurations is a general noncompact symmetric space. Associated with this path integral is a perturbation theory which respects the global structure of the system. This perturbation expansion is evaluated for a simple example and leads to a new exactly soluble model. This work is a step towards the construction of a strong coupling perturbation theory for quantum gravity.
BRST FIELD THEORY OF RELATIVISTIC PARTICLES
Authors: HOLTEN J.W. VAN
Published: November 2004

A generalization of BRST field theory is presented, based on wave operators for the fields constructed out of, but different from the BRST operator. We discuss their quantization, gauge fixing and the derivation of propagators. We show, that the generalized theories are relevant to relativistic particle theories in the Brink-Di Vecchia-Howe-Polyakov (BDHP) formulation, and argue that the same phenomenon holds in string theories. In particular it is shown, that the naive BRST formulation of the BDHP theory leads to trivial quantum field theories with vanishing correlation functions.
GENERALIZED LAGRANGIAN DYNAMICS AND NOETHERIAN SYMMETRIES
Authors: GRIGORE D.R.
Published: November 2004

We propose a generalization of the usual Lagrangian formulation of dynamics, suggested by the Souriau approach to analytical mechanics. It is a global formulation in which the Lagrangian is defined, in general, only locally. Some examples are given of generalized dynamics in this sense. We analyze in detail the Galilean invariant N-particle system and we also study the case of identical particles.
NONLINEAR SCHRÖDINGER EQUATIONS ON SUPER SYMMETRIC SPACES RELATED TO ORTHOGONAL-SYMPLECTIC LIE SUPERALGEBRAS
Authors: CANOGLU AHMET , GÜLDOGAN BAHRI , SALIHOGLU SELÂMI
Published: November 2004

We obtain new integrable coupled nonlinear partial differential equations by assuming the soliton connection having values in orthogonal-symplectic Lie superalgebras [B(m, n), C(n), D(m, n)]. These equations are coupled Nonlinear Schrödinger equations on various super symmetric spaces.
ALL EXACTLY SOLVABLE U(1)-INVARIANT QUANTUM SPIN 1 CHAINS FROM HECKE ALGEBRA
Authors: ALCARAZ FRANCISCO C. , KÖBERLE ROLAND , LIMA-SANTOS A.
Published: November 2004

We obtain all exactly integrable spin 1 quantum chains, which are U(1) invariant and satisfy the Hecke algebra. We present various generalizations for arbitrary spin S and discuss their solution via Bethe ansatz methods.
GENERALIZATION OF MANTON’S CONSTRUCTION OF THE WEINBERG-SALAM MODEL WITH A GAUSS-BONNET TERM
Authors: BERTRAND CHRISTINE , KERNER RICHARD , MIGNEMI SALVATORE
Published: November 2004

In a paper1 published in 1979 Manton has derived the bosonic sector of the Weinberg-Salam electroweak model by considering the Yang-Mills Lagrangian on a six-dimensional space M4×S2. The model turned out to be very rigid and identified the Weinberg angle with the angle between two neighbor roots in the Cartan diagram of the gauge group. leading to θW=60° for SU(3), θW=45° for O(5) and θW=30° for G2 and to the equality of the masses of the Z particle and of the Higgs boson.

We generalize this model by identifying the Yang-Mills Lagrangian with a part of the Einstein-Hilbert Lagrangian on the fibre bundle P(M4×S2), and by adding to it a Gauss-Bonnet invariant. which produces new terms, quartic and cubic in Fμν. This in turn modifies the definition of the Weinberg angle and the Higgs mass. The new free parameter is the dimensional factor in front of the Gauss-Bonnet term.

We discuss the values of MW, MZ and MH in function of this parameter and the radii of the internal space S2 of the gauge group G. Realistic values can be obtained if the Gauss-Bonnet term contributes to the Lagrangian with a negative sign.
EXACT SOLUTIONS OF A MANY-ANYON PROBLEM
Authors: MASHKEVICH STEFAN V.
Published: November 2004

A scheme for obtaining exact analytic solutions of the problem of an arbitrary number of anyons in a harmonic well is developed. Its essence consists in establishing a set of wave functions with the demanded interchange properties followed by finding stationary state functions within this set by the method of successive approximations. The energy of the corresponding states depends linearly on the statistical parameter. The discussion of the obtained states is carried out.
J/ψ-PRODUCTION MECHANISMS AND DETERMINATION OF THE GLUON DENSITY AT HERA
Authors: JUNG H. , SCHULER G.A. , TERRON J.
Published: November 2004

We discuss photo- and leptoproduction of J/ψ mesons at energies ranging from those of fixed-target experiments up to those of HERA. Elastic and diffractive production as well as various inelastic processes are studied. We investigate the range in which J/ψ production is described by photon-gluon fusion in the color-singlet model. We show how inelastic J/ψ production at HERA can be used to extract the gluon density. We estimate an accessible range of 3×10−4<x<0.1 and discuss sources of errors in the reconstruction of the gluon density at HERA.
PSEUDOSCALAR QUARK STATES MIXING AND AXIAL WARD IDENTITIES
Authors: NEKRASOV M.L.
Published: November 2004

The η-, η′-meson system is investigated in a relativistic invariant approach of composite operators under assumptions of completeness and quark nature of mesons. New advanced solutions of axial Ward identities have been obtained. The connection of the decays constants and other parameters of the η-, η′-meson system with the mixing angle and the pion and kaon constants has been established. In the approach under consideration the improved PCAC formulas for the decays η→γγ, η′→γγ have been determined and the basic parameter values of the η-, η′-meson system have been evaluated. The effect of the nonet symmetry breaking obtained in this system exceeds the usually expected value and is estimated as ≃50%. The value of the pseudoscalar mixing angle is estimated as θp=−14.5°±1.0°.
BEYOND THE LARGE N LIMIT: NON-LINEAR W∞ AS SYMMETRY OF THE SL(2,R)/U(1) COSET MODEL
Authors: BAKAS IOANNIS , KIRITSIS ELIAS
Published: November 2004

We show that the symmetry algebra of the SL(2,R)k/ U(1) coset model is a non-linear deformation of W∞, characterized by k. This is a universal W-algebra which linearizes in the large k limit and truncates to WN for K=-N. Using the theory of non-compact parafermions we construct a free field realization of the non-linear W∞ in terms of two bosons with background charge. The W-characters of all unitary SL(2,R)/ U(1) representations are computed. Applications to the physics of 2-d black hole backgrounds are also discussed and connections with the KP approach to c=1 string theory are outlined.
ASYMPTOTICS OF A TAU-FUNCTION AND TOEPLITZ DETERMINANTS WITH SINGULAR GENERATING FUNCTIONS
Authors: BASOR ESTELLE L. , TRACY CRAIG A.
Published: November 2004

We compute the short distance asymptotics of a tau-fucntion appearing in the work of Sato, Miwa, and Jimbo on holonomic quantum fields, We show that these asymptotics are determined by the Widom operator. This same operator is fundamental in the asymptotics of Toeplitz determinants with singular generating fucntions.
AN ALGEBRAIC APPROACH TO VERTEX MODELS AND TRANSFER MATRIX SPECTRA
Authors: DEGUCHI T. , MARTIN P. P.
Published: November 2004

We analyse the transfer matrix spectra of vertex models associated with the Lie superalgebras gl(P|M) and sl(P|M) using the representation theory of the Hecke algebra Hn(q). We develop a terminology for discussing the Bethe ansatz computation of the spectrum from this perspective. Using representations coming from these vertex models we develop some new methods for dealing with the analysis of Hecke algebras in any specialisation, including roots of unity. We also discuss the construction and spectrum of fusion models from the viewpoint of representation theory, begining a classification of the spectrum and identifying some sectors with trivial spectrum. In particular we show that the spectrum of the sl(P|M) λ-fusion model is trivial if λP+1>M.
CORNER TRANSFER MATRICES AND QUANTUM AFFINE ALGEBRAS
Authors: FODA OMAR , MIWA TETSUJI
Published: November 2004

Let ℋ be the corner-transfer-matrix Hamiltonian for the six-vertex model in the anti-ferroelectric regime. It acts on the infinite tensor product W=V⊗V⊗V⊗⋯, where V is the 2-dimensional irreducible representation of the quantum affine Lie algebra [Formula: see text]. We observe that ℋ is the derivation of [Formula: see text], and conjecture that the eigenvectors of ℋ form the level-1 vacuum representation of [Formula: see text]. We report on checks in support of our conjecture.
SOLVABLE MODEL OF THE PAIRING TRANSITION IN A TWO-DIMENSIONAL ONE-COMPONENT PLASMA/METAL INTERFACE MODEL
Authors: FORRESTER P. J.
Published: November 2004

An exactly solvable model of the pairing transition from a conductive to an insulator phase in a two-dimensional, log-potential Coulomb system is given. The system considered is the one-component plasma of positive particles without a neutralizing background near a metal interface, which is coupled to an external (non-Coulombic) potential. A complete analytic description of the equilibrium properties of the two phases and the transition is provided, and this is compared with the expected analytic properties of the two-component log-potential Coulomb gas in one and two-dimensions.
N3-STATE R-MATRIX RELATED WITH Uq(sl(3)) ALGEBRA AT q2N=1
Authors: KASHAEV R. M. , MANGAZEEV V. V. , STROGANOV YU. G.
Published: November 2004

We present N3-state R-matrix related with Uq(sl(3)) algebra at q2N=1. Its matrix elements are interpreted as Boltzmann weights of an elementary box of some 2d lattice statistical model and given in terms of [Formula: see text] weights of the "minimal" sl(3) chiral Potts model.
SOLUTIONS OF THE STAR-TRIANGLE EQUATIONS IN (Nα,Nβ) POTTS MODELS
Authors: AU-YANG HELEN , PERK JACQUES H. H.
Published: November 2004

In this paper we present the solutions of the star-triangle equation for Boltzmann weights of the (Nα,Nβ) model. This model consists of two scalar Potts models (of Nα and Nβ states, respectively) coupled together by four-spin interaction terms and was introduced by Domany and Riedel to study the phase transitions in adsorbed thin films. If Nα,Nβ≠2, the star-triangle equations have nontrivial self-dual and non-self-dual solutions only for Nα=Nβ; whereas if Nα≠Nβ=2, we have other self-dual and non-self-dual solutions. After applying partial duality transformations several of our solutions can be identified with known solutions for Interaction-Round-a-Face (IRF) models. Our results also mean that our high-genus solutions found earlier are not the only solutions to the star-triangle equations in chiral Potts models with six or more states per site.
THE CHERN–SIMONS–LANDAU–GINZBURG THEORY OF THE FRACTIONAL QUANTUM HALL EFFECT
Authors: ZHANG SHOU CHENG
Published: November 2004

This paper gives a systematic review of a field theoretical approach to the fractional quantum Hall effect (FQHE) that has been developed in the past few years. We first illustrate some simple physical ideas to motivate such an approach and then present a systematic derivation of the Chern–Simons–Landau–Ginzburg (CSLG) action for the FQHE, starting from the microscopic Hamiltonian. It is demonstrated that all the phenomenological aspects of the FQHE can be derived from the mean field solution and the small fluctuations of the CSLG action. Although this formalism is logically independent of Laughlin's wave function approach, their physical consequences are equivalent. The CSLG theory demonstrates a deep connection between the phenomena of superfluidity and the FQHE, and can provide a simple and direct formalism to address many new macroscopic phenomena of the FQHE.
He DIFFRACTION FROM Ag(110) SURFACE
Authors: ARTUNÇ M. , CEYLAN M. , KOLSUZ N.
Published: November 2004

Using the exact close-coupling method we have investigated the diffraction intensities of He atoms from a Ag(110) surface. He-Ag(110) interaction is represented by a corrugated Mie potential. In our calculations we have used three different well depths D. Diffraction intensities were calculated for x = <001> direction. The softness parameter β is optimized for a given incident energy Ei and incident angle θi so as to reproduce the experimental results. Using well depth D and van der Waals constant C3 for six He-metal (Al, Ni, Cu, Ag, Pt, Au) systems we have obtained a relation, D = 0.070C3 − 9.006, between parameters D and C3.

Our results are in good agreement with experimental observations.
THE MICROSCOPIC THEORY OF THE SURFACE PROPERTIES OF ANHARMONIC CRYSTALS I: General Method and (001) Surface of BCC Crystal
Authors: ZUBOV V. I. , MAMONTOV I. V. , TRETYAKOV N. P.
Published: November 2004

The self-consistent theory of the structural, dynamical, and thermodynamic surface properties of anharmonic crystals previously given for one- and two-dimensional models is extended to the surfaces of three-dimensional crystals which take into account the surface anisotropy. After considering the reference system, in the general case, the equations for the properties of the interface cyrstal-vapour to the second order in the temperature are derived. The (001) face of the BCC crystal is investigated. The lattice relaxation and dynamics are calculated. The surface Helmholtz free energy and other thermodynamic properties are obtained. At high temperatures, the surface specific heat increases linearly with temperature due to the anharmonicity.
INFLUENCE OF THE FLOW ON THE ORIENTATION INDUCED BY A SOLID SUBSTRATE ON A NEMATIC LIQUID CRYSTAL
Authors: BARBERO G. , CHUVYROV A. N. , KREKHOV A. P.
Published: November 2004

The influence of the flow on the orientation induced by a solid substrate on a nematic liquid crystal is experimentally and theoretically analyzed. Our experimental data show that a nematic cell filled by capillarity presents a birefringence dependent on the sample thickness. This fact suggests that the symmetry of the problem is broken by the filling process. A simple model is presented in order to explain the experimental observations. According to this model, a surface anchoring contribution to the total surface energy, of the same order of the usual one appearing in the Rapini-Papoular expression, is connected to the flow. The agreement between the experimental data and the theoretical results is fairly good.
A Theory of the Normal and Superconducting States of Doped Solid C60
Authors: Baskaran G.
Published: November 2004

We identify the ‘Stability of Molecular Singlets'(SMS) as an important feature of MxC60, and argue that it arises from the intramolecular carbon pπ-electron correlations and the consequent RVB character of the ‘two dimensional’pπ-electron system of the C60molecule. Alternatively SMS is shown to arise from the exchange of virtual triplet intra-molecular excitons. SMS is modelled as an effective intra-molecular pairing resulting in a narrow band model with an effective negative Hubbard U, which explains the observed superconductivity as well as predicts anomalous boson metal like normal state properties. Disorder plays an important role and restricts superconductivity to a narrow range of x around 3. The narrowness of the conduction band puts limitations on the maximum attainable Tc.
SINGLE PARTICLE AND OPTICAL GAPS IN CHARGE-TRANSFER INSULATORS
Authors: Bang Y. , Castellani C. , Grilli M. , Kotliar G. , Raimondi R. , Wang Z.
Published: November 2004

We analyze the collective excitations near a Mott-Hubbard and a metal charge transfer insulator transition, using the slave boson technique. We show that the Mott transition can be viewed as an excitonic softening, which takes place when the bound state between the lower and upper Hubbard bands reaches zero energy. The exciton energy is related to the jump of the chemical potential at zero doping. In a charge transfer insulator this mode describes a p-d charge fluctuation, i.e. it is a charge transfer exciton. In the single band Hubbard model the excitonic resonance describes virtual transitions between the lower and the upper Hubbard band.

Finally we contrast the behaviour of the collective modes near the Mott transition with and near the Charge Transfer Instability. In the former the exciton energy and the charge compressibility go to zero. In the latter the exciton energy remains finite and the charge susceptibility diverges, causing phase separation.
NONEQUILIBRIUM STATISTICAL OPERATOR IN HOT-ELECTRON TRANSPORT THEORY
Authors: Xing D.Y. , Liu M.
Published: November 2004

The Nonequilibrium Statistical Operator method developed by Zubarev is generalized and applied to the study of hot-electron transport in semiconductors. The steady-state balance equations for momentum and energy are derived to the lowest order in the electron-lattice coupling. We show that the derived balance equations are exactly the same as those obtained by Lei and Ting. This equivalence stems from the fact that to the linear order in the electron-lattice coupling, two statistical density matrices have identical effect when they are used to calculate the average value of a dynamical operator. The application to the steady-state and transient hot-electron transport in multivalley semiconductors is also discussed.
THE ELECTRICAL AND OPTICAL PROPERTIES OF V2O5-TeO2 GLASSES CONTAINING LEAD OXIDE
Authors: AL-SAIE AHMED M.
Published: November 2004

The electrical conductivity, density optical absorption and infrared transmission spectra of vanadium tellurite glasses are studied as a function of lead content. It is found that the activation energy of the conductivity increases with the increase of lead concentration. The optical observation is a function of glass composition and the optical absorption is due to indirect transition in K-space. The infrared transmission spectra of these glasses show that the addition of lead does not introduce any absorption band and the main transmission band in V2O5-TeO2-PbO glasses are related to those characteristics of the TeO 2 component.
THE EDWARDS MODEL: SOME NEW EXTENSIONS OF THE EDWARDS MODEL
Authors: EDWARDS S.F.
Published: November 2004

There are important problems which require the path which emerges physically not only to move but to lose or gain some part of its length. Two notable examples arise in oxbow lakes, and the deposition of feathery material. These problems are described and an outline offered for a solution.
DECAHEDRAL AND ICOSAHEDRAL SYMMETRIES: AN APERIODIC MULTIPLE TWINNING MODEL WITH LINEAR STRAINS AND DENSITY INHOMOGENEITY
Authors: CONTI LUIGI G.
Published: November 2004

The decahedral and icosahedral symmetries often observed in pure metals can be easily explained on the basis of an aperiodic multiple twinning model if defect concentration gradients are present. The different behavior of Au and Pt is discussed in detail in terms of defect formation volumes and migration thermodynamics.
TOPOLOGICAL QUANTUM FIELD THEORY AND INVARIANTS OF SPATIAL GRAPHS
Authors: MILLETT KENNETH C.
Published: November 2004

According to Sir Michael Atiyah [At], the study of topological quantum field theory is equivalent to the study of invariant quantities associated to three-dimensional manifolds. Although one has long considered the classical homology and cohomology structures and their extremely successful generalizations, the real subject of the Atiyah assertion is the new invariants proposed by Witten associated to the Jones polynomials of classical knots and links in the three-dimensional sphere. There have been many manifestations described by Reshetikhin & Turaev [Re1&2], Turaev & Viro [TV], Lickorish [Li 11– 15]. Kirby & Melvin [KM1&2], and Blanchet, Habegger, Mausbaum & Vogel [BHMV]. In these notes I describe some of the fundamental aspects of this theory, discuss the interest in these invariants and their extensions to the class of spatial graphs by Jonish & Millett [JonM], Kauffman & Vogel [KauV], Yamada [Ya2], Millett [Mi1&2], Kuperberg [Ku1&2], and Jaeger, Vertigan and Welsh [JaVW].
ON THE SYMMETRIES OF INTEGRABILITY
Authors: BELLON M. , MAILLARD J-M. , VIALLET C.
Published: November 2004

We show that the Yang-Baxter equations for two-dimensional models admit as a group of symmetry the infinite discrete group [Formula: see text]. The existence of this symmetry explains the presence of a spectral parameter in the solutions of the equations. We show that similarly, for three-dimensional vertex models and the associated tetrahedron equations, there also exists an infinite discrete group of symmetry. Although generalizing naturally the previous one, it is a much bigger hyperbolic Coxeter group. We indicate how this symmetry can help to resolve the Yang-Baxter equations and their higher-dimensional generalizations and initiate the study of three-dimensional vertex models. These symmetries are naturally represented as birational projective transformations. They may preserve non-trivial algebraic varieties, and lead to proper parametrizations of the models, be they integrable or not. We mention the relation existing between spin models and the Bose-Messner algebras of algebraic combinatorics. Our results also yield the generalization of the condition qn=1 so often mentioned in the theory of quantum groups, when no q parameter is available.
THE EFFECTS OF BOUNDARY CURVATURE ON HYDRODYNAMIC FLUID FLOW: CALCULATION OF SLIP LENGTHS
Authors: PANZER PETER , LIU MARIO , EINZEL DIETRICH
Published: November 2004

The slip description of fluid flow past solid boundaries is reconsidered. We find that the traditional picture of fluid slip as a mean free path correction to hydrodynamics has to be revised whenever the particle scattering becomes close to specular. Then the microscopic slip length may diverge and it is the boundary’s curvature which is decisive for the momentum transfer between fluid and wall. By explicitly considering surface roughness we can explain discrepancies between experimentally observed data and traditional slip theory.
RECURSION METHOD IN AUGMENTED SPACE
Authors: DATTA ABHIJIT , MOOKERJEE ABHIJIT
Published: November 2004

A new method for configuration averaging in random binary alloy problem is proposed which combines the augmented space method with Haydock’s recursion scheme. The basis members of the augmented space are represented by a series of binary words (the multi-spin coding technique). Haydock’s recursion scheme is employed to obtain the resolvent of the Hamiltonian in the augmented space formalism. The configuration averaged DOS is obtained from the resolvent. The procedure is illustrated by applying it to a simple s-state model of random binary alloy on a simple cubic structure. We have also applied the method to calculate the density of states for CuAg alloys using both the LCAO and TB-LMTO methods.
TRANSFORMATIONS, GENERATION AND MEASUREMENT OF PHOTONIC STATES THAT POSSESS A GAUSSIAN DENSITY MATRIX
Authors: TUCCI ROBERT R.
Published: November 2004

In this paper, we consider issues of importance in dealing with 1-mode and 2-mode photonic states that possess a Gaussian density matrix. By a Gaussian density matrix or a Gaussian “rho”, we mean an exponential of a quadratic polynomial of the creation and annihilation operators of the modes. Gaussian-rho states, which include the socalled squeezed states of light, are uniquely specified by the covariance matrix of their modes (provided we assume zero mean fields). We discuss the set of all possible linear transformations of N modes into an equal number of modes. This set is shown to be a group that is isomorphic to one of the symplectic groups. We propose a device, which we call a covmuter, that can perform any linear transformation in this group. Given a fixed covariance matrix Vo of a Gaussian-rho state, we find all covariance matrices V for which there exists a multi-mode linear transformation that takes Vo to V. We study the conservation laws obeyed by such transformations. Finally, we show that a covmuter can be used both to generate and to measure 1-mode and 2-mode Gaussian-rho states.
A THEORY OF FERROMAGNETISM IN THE HUBBARD MODEL WITH INFINITE COULOMB INTERACTION
Authors: IZYUMOV YU. A. , LETFULOV B.M. , SHIPITSYN E.V. , CHAO K.A.
Published: November 2004

On the basis of a regular perturbation theory in the form of diagrammatic technique with X-operators, a ferromagnetic state in the Hubbard model with infinite on-site Coulomb interaction U is studied for a wide range of electron concentration n. Treating the kinetic energy of electrons as perturbation, we get the exact graphic representations for three Green’s functions [Formula: see text] and [Formula: see text] for electrons with spin ↑ and ↓ (spontaneous magnetic moment is in ↑ direction) and [Formula: see text] for spin waves. All of them are expressed through the unique system of four-point and three-point vertex parts for effective electron-magnon and electron-electron interactions. These vertex parts are calculated in two approximations: a low-density approximation for n≪1 or nh=1–n≫1, and the generalized random-phase approximation (GRPA), which was suggested earlier by us for the description of paramagnetic phase in this model.

An important result in both cases is the understanding of essential difference of electron states with spin ↑ and ↓. The state for ↑ has coherent character in all region of electron concentration (n>nc) where a ferromagnetic state exists, while the state for spin ↓ has mixed characters including both coherent and incoherent contribution. For the saturated ferromagnetism (n>ns) when nh≪1, [Formula: see text] is an entirely incoherent (nonquasiparticle) state. Appearance of incoherent state is probably a general property of strongly correlated systems distinguishing its behavior from the Fermi liquid. We show also that the Hubbard-I approximation has no region of applicability for the electron with spin ↓ in a ferromagnet and we found a new factor describing the correlation-narrowing of ↓ spin electron band.

Green’s function [Formula: see text] calculated in two different limits n≪1 and nh≪1, are jointed together to allow us to calculate ns which lies in the intermediate concentration regime. For simple cubic lattice we found ns=0.87. In the limit nh≪1 our results reduce to the earlier known ones, including Nagaoka’s result for the spin wave energy. We point out the way to construct a rigorous theory for ferromagnetic state in the intermediate range of electron concentration. In the conclusion several important problems are discussed in connection to the continuation of the present work.
MOLECULAR DYNAMICS STUDY OF CLUSTER GROWTH AND POLYMER DEGRADATION
Authors: Blaisten-Barojas Estela
Published: November 2004

This work is an overview on two molecular dynamics studies of processes at temperatures characteristic of a flame — growth of silicon clusters from binary cluster collisions and thermal degradation of polymers. In the first study, silicon clusters grow as a consequence of cluster-cluster collisions by forming transient agglomerates that coalesce in a few picoseconds. The collision energy accommodates within the cluster favoring the formation of globular larger clusters regardless of the collision energy and of the impact parameter. On the average the probability for the clusters to stick upon collision is almost 1, showing clearly that the process is irreversible. The second study concerns simple polymeric chains undergoing fragmentation when they burn. These fragments are products of thermal degradation. The consorted sequence of depolymerization reactions arises after fragmentation. As a result, a sample of degrading fragments is formed where the polymer chains have dramatically coiled. These fragments self trap themselves in coiled conformations due to the cooling effect produced by the depolymerization reaction.
ANALYTICAL THEORY FOR THE TEMPERATURE DEPENDENT ELECTRONIC SHELL STRUCTURE OF METALLIC CLUSTERS
Authors: Stampfli P. , Bennemann K.H.
Published: November 2004

We present a theory for the electronic shell structure of large metallic clusters. Analytical results are given for the dependence of the shell effect on the cluster size and temperature. In particular, we present results for the shell effect in the cohesive energy and ionization potential. A good quantitative agreement with previous numerical calculations and with experiments on Na clusters is obtained.
FULLERENES DOPED WITH METAL HALIDES
Authors: Martin T.P. , Heinebrodt M. , Näher U. , Göhlich H. , Lange T. , Schaber H.
Published: November 2004

The cage-like structure of fullerenes is a challenge to every experimentalist to put something inside—to dope the fullerenes. In fact, the research team that first identified C 60 as a football-like molecule quickly succeeded in trapping metal atoms inside and in shrinking the cage around this atom by photofragmentation. In this paper we report the results of “shrink-wrapping” the fullerenes around metal halide molecules. Of special interest is the critical size (the minimum number of carbon atoms) that can still enclose the dopant. A rough model for the space available inside a carbon cage gives good agreement with the measured shrinking limits.
CRITICAL STATE IN DENSE JOSEPHSON STRUCTURES
Authors: BRYKSIN V. V. , GOLTSEV A. V. , DOROGOVTSEV S. N. , SAMUKHIN A. N.
Published: November 2004

Vortices penetration into the periodically inhomogeneous Josephson junction is treated within the framework of the microscopic approach. The pinning centers are suggested to be situated closely enough to each other. It appears possible to obtain the exact magnetic flux profile and field dependence of the critical current in this case. Possible generalizations concerning higher-dimensional Josephson structures including the case of granular superconductors are discussed. The comparison with the dependencies used to describe experimental data is given.
CHERN-SIMONS GAUGE THEORY FOR DOUBLE-LAYER ELECTRON SYSTEM
Authors: EZAWA Z. F. , IWAZAKI A.
Published: November 2004

We present a microscopic theory of the fractional quantum Hall effect at the filling factor ν with even denominator, which is recently observed in a double-layer electron system. In our approach electrons belonging to different layers are interpreted as different types of anyons with appropriate statistics. The wavefunction of the Hall state is calculated, which is found to coincide with that of Halperin. We also analyze vortex (quasihole) excitations. It is shown that a single vortex carries electric charges on both of the layers; for instance, a vortex at ν=½ has the electric charge [Formula: see text] on one layer and -⅛e on the other layer. The ground state at the vicinity of ν=½ is given by a Wigner crystal made of these vortices.
GLOBAL AND GAUGE SYMMETRIES OF THE HUBBARD MODEL
Authors: ERCOLESSI E. , MORANDI G. , ORTOLANI F.
Published: November 2004

A remarkable global SO(4) symmetry of the Hubbard model, when there is on the average one electron per site (“weak” half-filling condition) has been recently uncovered by Yang and Zhang. We discuss here its relationship to the SU(2) gauge symmetry of the model that holds when there is exactly one electron per site (“strong” half-filling condition) as well as its possible generalizations to lattice structures more general than those considered by Yang and Zhang.
RESISTIVE CHARACTERISTICS OF YBa2Cu3Ox THIN FILMS UNDER DIFFUSION OF INDIUM ATOMS
Authors: MIKHEENKO P.N. , SOBOLEV V.L. , USOSKIN A.I.
Published: November 2004

A series of elementary dissipative formations in superconducting YBa 2 Cu 3 O x films under diffusion of In atoms in them is observed. It is shown that diffusion weakens intergranular bonds, but granules remain superconductive. Time dependence of main superconducting parameters is analyzed.
A HIERARCHICAL APPROACH TO THE EVEN-DENOMINATOR QUANTUM HALL STATES
Authors: YANG J. , SU W.P. , SU Z.B.
Published: November 2004

The standard hierarchy theory (SHT) of the fractional quantum Hall effect is generalized. We find that for each hierarchy state of the SHT, one can build two kinds of daughter states. The first one belongs to the next hierarchy class of the SHT, while the second one, which is stabilized by the condensation of paired quasiparticles (or quasiholes), can give rise to even-denominator states. The even-denominator states constructed in this way are incompressible but deformable, and thus able to explain the experimental results. Charges carried by excitations of this kind of states are unusual. Two new even-denominator states are predicted, which could be used to test the theory experimentally.
INCREMENTAL CHARGING OF A MOLECULE AT ROOM TEMPERATURE: DISTURBANCE OF MOLECULAR ELECTRONIC STATES DUE TO THE TUNNELING EVENT
Authors: NEJOH H. , AONO M.
Published: November 2004

The many-electron problem has been studied by many researchers, mainly theoretically. The reason why there have not been many experimental studies is that there have not been adequate tools to measure the total energy of a system. We have succeeded to measure the total energy difference between an ionized molecule and a neutral molecule. This answers the question of how much the correlation energy is. The measured total energy differences between the ionized state and the neutral state are far smaller than those which are calculated, even including the effect of the substrate on which the molecules are supported. This result provides a way of comparing theoretical and experimental values of the correlation energy.
MICROWAVE DETECTING PROPERTIES OF Tl-BASED HIGH Tc THIN FILM MICROBRIDGES
Authors: YAN S.L. , FENG H.H. , FANG L. , CAO H.L. , YANG X.M.
Published: November 2004

Microwave detecting properties of Tl -based high T c superconducting microbridges have been investigated at liquid nitrogen temperature. The microbridges with the area of about 4×4 μ m 2 were fabricated by photolithographing and chemical etching superconducting Tl 2 Ba 2 Ca 2 Cu 3 O x thin films. Zero resistance temperatures T c (R=0) of the thin films were over 110 K. Detecting sensitivity was influenced heavily by the dc bias current and was reasonably linear function of the incident microwave power at a constant bias current. The sensitivity of 5.5×104 V/W has been obtained at microwave frequency of 9.40 GHz.
MACROSCOPIC SQUEEZING FROM A REGULAR ARRAY OF THREE-LEVEL ATOMS
Authors: D’SOUZA RICHARD , JAYARAO ARUNDHATI S. , LAWANDE SURESH V.
Published: November 2004

It is shown that the resonance fluorescence from N regularly arrayed three-level atoms in V-configuration could be a source of macroscopic squeezing. The V-configuration exhibits squeezing in both the transitions, whereas the cascade and the Raman configurations shown squeezing only in the lower and Rayleigh transitions respectively.
GENERATION OF SQUEEZED EXCITONS IN SEMICONDUCTORS BY COHERENT LIGHT
Authors: NGUYEN BA AN , TRAN THAI HOA
Published: November 2004

In this letter, we show that semiconductor excitons generated by coherent light may become squeezed. This is due to their interactions both with the light and among themselves. Based on a polariton theory and using a secular approximation, analytical expressions for exciton quadrature variances have been derived, which enable us to study easily the dependence of exciton squeezing degree on the pumping light intensity, frequency detuning and strength of exciton-exciton, as well as exciton-photon, interactions.
TRANSPORT PROPERTIES AND SUPERCONDUCTIVITY IN PRESENCE OF BACKSCATTERING
Authors: CHEN HUA , MATTIS DANIEL , RUDIN SERGBY
Published: November 2004

We achieve an exact evaluation of the Kubo formula for electrical resistivity, within a model in which random impurity scattering is parametrized by random back-scattering matrix elements. If the alloy is a superconductor, our theory allows us to correlate T c with the normal-phase resistivity. The results are in nice agreement with experiment.
QUASI-ONE-DIMENSIONAL IMPURITY STATES IN Ga1−xAlxAs/GaAs HETEROSTRUCTURE
Authors: GHAZALI A. , DA CUNHA LIMA I. C.
Published: November 2004

The advances in submicron lithography on semiconductor devices allow to produce very narrow inversion channels in which the electron gas behaves as quasi-one-dimensional. The presence of shallow donor impurities introduces bound states for electrons which have their binding energies depending on the impurity location in the plane perpendicular to the channel. In this paper we calculate these binding energies and plot the iso-energy curves for the dilute regime, assuming a confinement potential separable into a square well (caused by the barriers at the interfaces creating the quantum well) and an electrically induced harmonic potential in a direction perpendicular to the growth axis.
ROLE OF ANODE LENGTH IN A MATHER-TYPE PLASMA FOCUS
Authors: BEG FARHAT N. , ZAKAULLAH M. , NISAR M. , MURTAZA G.
Published: November 2004

Neutron emission from a 3 KJ Mather-type plasma focus is studied. Specifically, the behavior of system with the change in anode length is investigated. Anode lengths of high and low fluence anisotropy as well as for high neutron yield are identified. Experiment also suggests the possibility of ion beam generation leading to neutron production via beam-plasma interaction.
STUDY OF ELECTRONIC STATES IN THE HYDROGEN-INDUCED STRUCTURAL PHASE TRANSITION FROM DIAMOND C(111)–(2*1) RECONSTRUCTION TO (1*1) STRUCTURE
Authors: PAN B. C. , XIA S. D.
Published: November 2004

The electronic structure in the structural phase transition of diamond C(111) surface from (2*1) reconstruction to (1*1) structure induced by adsorbed hydrogen has been studied by DV-X αab initio calculations. The role of the adsorbed hydrogen in the structural phase transition is also discussed.
DIFFUSING VOID MODEL FOR GRANULAR FLOW
Authors: CARAM H. S. , HONG D. C.
Published: November 2004

The gravitational flow pattern of granular media in a confined geometry is assumed to be caused by the upward motion of voids generated at the discharge orifices. The model describes some well known and unique features of granular flows such as the deformation of the free surface, the formation of dead zones, the flow around obstacles with its companion void regions and the formation of cascading zones. It also predicts an unexpected velocity profile in a flow expansion as well as the propagation of dilation waves whose scaling solutions are presented. These thin two-dimensional beds are also found to behave very differently from three-dimensional beds.
ORBITAL MAGNETISM OF MESOSCOPIC METALS: BEYOND THE PERTURBATION THEORY
Authors: SEROTA R.A.
Published: November 2004

We extend our investigation of orbital magnetic response of mesoscopic metallic systems to the limit of temperature and inelastic level broadening being comparable or less than the average interlevel spacing. We address the role of level repulsion and derive a level density correlation function which interpolates between the perturbation result and the Wigner-Dyson statistics. We plot out the magnetic field dependence of the sample magnetic moment for the entire range of experimentally relevant temperatures. We briefly discuss the relationship of our results to quantum chaos.
MONTE CARLO STUDIES OF A NEW MODEL DRIVEN DIFFUSIVE SYSTEM WITH REPULSIVE INTERACTIONS
Authors: MON K.K.
Published: November 2004

We propose a new class of driven lattice gas with repulsive nearest-neighbor interactions. Particles are allowed to jump to empty next-nearest-neighbor (nnn) sites in addition to the standard nearest-neighbor moves. In contrast to previous model with repulsive interactions, the external driving field (E) acts only along the nnn directions and does not destroy ground state sublattice ordering. Extensive Monte Carlo simulations in two dimensions for small E are consistent with a line of continuous transitions with Ising exponents. First-order transitions are also found for larger E.
TWO-DIMENSIONAL TWO LAYER ELECTRONS NEAR A HALF-FILLED LANDAU LEVEL
Authors: CHUI S.T.
Published: November 2004

We report finite cluster exact diagonalization studies under periodic boundary conditions of two layers of electrons in a strong magnetic field at a half-filled Landau level. For the system studied by Suen et al., the ground states have more than 97 per cent of its spectral weight in the symmetric single particle levels. The eigenfunctions and eigenvalues up to a constant factor for different aspect ratios are essentially the same as previous numerical results of a single layer of electrons of zero thickness at half-filling.
PREPARATION AND SUPERCONDUCTIVITY OF NEW 214-TYPE CUPRATES (La1.85−xCa0.15Ax)CuO4−y (A=Bi, Pb or Tl)
Authors: CHEN Z.Y. , SHENG Z.Z. , TANG Y.Q. , LI Y.F. , PEDERSON D.O.
Published: November 2004

Single-phase 214-type cuprates (La1.70Ca0.15Bi0.15)CuO4−y and (La1.70Ca0.15Pb0.15) CuO4−y have been successfully synthesized and identified by X-ray diffraction analyses. The former has a superconducting onset temperature of about 35 K which is higher than that of (La1.85Ca0.15)CuO4−y, whereas the latter does not show superconductivity down to 20 K. Further introduction of Tl into La-site in (La,Ca)2CuO4-type cuprates can reduce the formation temperature of this kind of compounds, but neither (La1.50Ca0.15Bi0.15Tl0.20)CuO4−y nor (La1.50Ca0.15Pb0.15Tl0.20)CuO4−y shows superconductivity.
PROPERTIES OF A LORENZ MODEL FOR CONVECTION IN A ROTATING FLUID LAYER
Authors: RAJESH GOVINDAN , DAS SUPREETI , BHATTACHARJEE JAYANTA K.
Published: November 2004

A Lorenz-like model due to Veronis for onset of convection in a rotating fluid layer is analysed for Rayleigh numbers higher than the point at which stationary convection occurs. The most outstanding feature is that for Taylor numbers above a critical value, the Hopf bifurcation does lead to a finite amplitude stable limit cycle via a hysteretic transition. This limit cycle undergoes a sequence of period doubling bifurcations to form a Feigenbaum attractor which then makes a transition to the Lorenz-like attractor.
CLUSTER EXPANSION AND PAIRING IN A TWO-BAND MODEL OF Cu OXIDES
Authors: TOMBOULIS E. T.
Published: November 2004

A two-band model for the high-T c Cu oxide superconductors involving Cu - O exchange and pair-hopping interactions is considered. A cluster expansion for treating fluctuations around a superconducting mean-field background is developed, and shown to converge at T=0 for small but non-zero doping concentration, and small "J/t" couplings.
AN OVERVIEW OF PARALLEL HARDWARE ARCHITECTURES FOR COMPUTER VISION
Authors: WECHSLER HARRY
Published: November 2004

The sheer complexity of the visual task and the need for robust behavior provide a unifying theme for computer vision — what can be accomplished is constrained by relatively limited computational resources, but the resulting performance must be robust. As a consequence parallel computation over space and time becomes essential for machine vision systems. Parallel computation is all encompassing and includes both image representations and processing. We give an overview in this paper of a taxonomy of parallel hardware architectures which includes pipelining, Single instruction multiple data (SIMD), multiple instruction multiple data (MIMD), data-flow, and neurocomputing. Specific applications and the relevance of parallel hardware architectures for computer vision tasks are discussed as well.
ON SHAPE RECOVERY FROM TWO SHADING PATTERNS
Authors: KOZERA RYSZARD
Published: November 2004

In this paper, we analyze the problem of recovering the shape of a smooth Lambertian surface from two images obtained by consecutive illumination of the surface by distant point light-sources from two different directions. We discuss the issues of existence and uniqueness of solutions to the corresponding system of two first-order non-linear partial differential equations. We show that generically this system has, up to a constant, a unique solution. We also examine exceptional cases for which there is no such uniqueness.
ROBUST MORPHOLOGICALLY CONTINUOUS FOURIER DESCRIPTORS II: CONTINUITY AND OCCLUSION ANALYSIS
Authors: DOUGHERTY EDWARD R. , LOCE ROBERT P.
Published: November 2004

Fourier descriptors based upon the waveform induced by a pattern's projection overcome a number of classic difficulties with Fourier-descriptor methodology. Not only are the descriptors invariant with respect to scale, translation, and rotation (as is usually the case), they are also continuous in the Hausdorff metric and robust with respect to both point noise and occlusion; insensitivity with respect to minimum occlusions is perhaps their most significant advantage. Continuity in the Hausdorff metric allows prediction of the effect on the descriptors when morphologically filtering a pattern. The effect of occlusion is also predictable.
PATTERN-BASED TACTICAL PLANNING
Authors: WALCZAK STEVEN
Published: November 2004

Our research demonstrates the utility of incorporating pattern recognition with machine learning in adversarial domains. We use induction to recognize cognitive behavioral patterns of an adversary and use those patterns for tactical planning in the adversarial domain. Results of our methodology for the application domain of chess are presented.
IMPROVED TECHNIQUES FOR WIRING AND STRETCHING LAYOUTS
Authors: TOLLIS IOANNIS G. , VAGUINE ANDRE V.
Published: November 2004

We present improved techniques for obtaining wirings of layouts in the square grid, where at most two wires pass through a point. Namely, we show that the number of layouts that require four layers using our heuristics is often less than half the number of layouts that require four layers without using the heuristics. We also show how to use our heuristics in order to obtain very efficient stretchings of layouts that can be wired using at most three layers.
THE IMPACT OF WIRE TOPOLOGY ON SINGLE ROW ROUTING
Authors: BLAIR JEAN R.S. , LLOYD ERROL L.
Published: November 2004

Since several aspects of the single row approach to local routing in automated PCB and VLSI chip design have been shown to be NP-complete, the research emphasis has been on placing various restrictions on the form of a solution. One widely used restriction involves the topological structure of the wires that interconnect common signal points. To date, four basic wire topologies have been considered. However, little is known about how these wire topologies compare in terms of the feasibility of routing instances and the size of optimal solutions. This paper defines five classes of routings and compares the feasibility and performance (the number of tracks necessary for a routing) of the various classes.
USING MOMENTS FOR 3-D MOTION PARAMETER ESTIMATION: A PURE ROTATION CASE
Authors: RAGUPATHI S. , KING R.A.
Published: November 2004

Moment Invariants (MIs) are widely used for object recognition. Most of the moment based object recognition work reported is for 2-Dimensional (2-D) objects only. There have been considerable attempts made in extending the 2-D MIs to 3-D space. However, using moments for 3-D motion parameter estimation is relatively neglected. In this paper we present two iterative schemes for motion estimation of planar objects using moments as features. One, using the Levinberg-Marquardt method, performs better compared with the other. Only the pure rotational case is considered. By using moments, the correspondence problem is completely eliminated. We show from simulation experiments that this method is a feasible one and the error performance is reasonable. As motion of a planar patch is considered, the algorithm estimates both the rotational parameters and the planar coefficients.