bluuebunny/crossref_metadata_2025 huggingface dataset:
Cats exhibit the Franssen Effect illusion
Authors: Dent Micheal L. , Tollin Daniel J. , Yin Tom C. T.
Published: November 2004

The Franssen Effect (FE) is a striking auditory illusion previously demonstrated only in humans. To elicit the FE, subjects are presented with two spatially-separated sounds; one a transient tone with an abrupt onset and immediate ramped offset and the other a sustained tone of the same frequency with a ramped onset which remains on for several hundred ms. The FE illusion occurs when listeners localize the tones at the location of the transient signal, even though that sound has ended and the sustained one is still present. The FE illusion occurs most readily in reverberant environments and with pure tones of ∼1–2.5 kHz in humans, conditions where sound localization is difficult in humans. Here, we demonstrate this illusion in domestic cats using, for the first time, localization procedures. Previous studies in humans employed discrimination procedures, making it difficult to link the FE to sound localization mechanisms. The frequencies for eliciting the FE in cats were higher than in humans, corresponding to frequencies where cats have difficulty localizing pure tones. These findings strengthen the hypothesis that difficulty in accurately localizing sounds is the basis for the FE.
Diffuse fields in open systems and the emergence of the Green’s function (L)
Authors: Weaver Richard L. , Lobkis Oleg I.
Published: November 2004

A definition of a diffuse field applicable to open heterogeneous systems is proposed. The identity between the Green’s function of the structure and the diffuse field’s correlations is proved. The Green’s function that emerges from the correlation is found to be the full Green’s function of the medium, symmetrized in time, with all reflections and scatterings and propagation modes. This is in contrast to suggestions that the correlation is the ballistic Green’s function only, or the Green’s function of a homogeneous effective medium.
PARALLEL WOLFF CLUSTER ALGORITHMS
Authors: BAE S. , KO S.H. , CODDINGTON P.D.
Published: November 2004

The Wolff single-cluster algorithm is the most efficient method known for Monte Carlo simulation of many spin models. Due to the irregular size, shape and position of the Wolff clusters, this method does not easily lend itself to efficient parallel implementation, so that simulations using this method have thus far been confined to workstations and vector machines. Here we present two parallel implementations of this algorithm, and show that one gives fairly good performance on a MIMD parallel computer.
MONTE CARLO SIMULATION OF THE DC SIZE EFFECT IN THIN FILMS
Authors: BOUGHTON R.I. , FENG ZHIPING
Published: November 2004

The Monte Carlo method is used to study the effect of boundary scattering on the temperature dependent part of the resistivity of thin metal films. A computational scheme is used that realistically simulates electron scattering mechanisms in the semi-classical context. As a test of the accuracy of the method, comparison is made between the present method at absolute zero (impurity and boundary scattering only) and the analytical results of Fuchs, which rely on the relaxation time approximation (RTA). The inclusion of phonon scattering provides a measure of the size induced deviations from Matthiessen’s Rule (SIDMR). At low temperatures phonon scattering cannot be adequately described using the RTA and the numerical technique presented shows good promise of overcoming this problem. Calculated SIDMR results are compared with some recent data on Al and Ga films.
A SEMI-LINEAR ELLIPTIC PDE MODEL FOR THE STATIC SOLUTION OF JOSEPHSON JUNCTIONS
Authors: CAPUTO JEAN-GUY , FLYTZANIS NIKOS , VAVALIS EMMANUEL
Published: November 2004

In this study we derive a semi-linear Elliptic Partial Differential Equation (PDE) problem that models the static (zero voltage) behavior of a Josephson window junction. Iterative methods for solving this problem are proposed and their computer implementation is discussed. The preliminary computational results that are given, show the modeling power of our approach and exhibit its computational efficiency.
SUPERLINEAR SPEEDUP FOR PARALLEL IMPLEMENTATION OF BIOLOGICALLY MOTIVATED SPIN GLASS OPTIMIZATION ALGORITHM
Authors: GROPENGIESSER UWE
Published: November 2004

Using a simple master-slave parallelization scheme given by A. Berengoltz and J. Adler, we observe superlinear speedups during the search algorithm for the ground state energy of the ±J spin glass via biologically motivated methods. With this parallel implementation we are able to improve earlier sequentially-calculated estimates for the infinite lattice ground state energy of the square and simple cubic lattice to −1.401±0.001 and −1.787±0.003, respectively.
A TWO-DIMENSIONAL DYNAMIC SIMULATION OF SOLID FRACTURE PART II: EXAMPLES
Authors: POTAPOV ALEXANDER V. , CAMPBELL CHARLES S. , HOPKINS MARK A.
Published: November 2004

This paper uses the model described in Ref. 1 to simulate fracture in many simple systems with the goal of evaluating the advantages and deficiencies of the model. The examples include compressive failure of a rectangular sample, four-point shear failure of a beam and the impact of particles with a plate and binary impacts of particles. Where possible, the simulated results seem to be in good agreement with typical experimental results. Finally, a simulation of ball-milling, which involves the flow and fracture of many particles is shown to demonstrate the overall utility of the model.
EXPERIENCE USING FORMAL METHODS IN HIGH ENERGY PHYSICS
Authors: BALKE A.C. , CARTER J. , HAVEMAN J.
Published: November 2004

We report our experience using the formal method VDM++ in high energy physics real-time applications. VDM++ is an extension of the established formal method VDM to include object-oriented, concurrency and real-time features. VDM++ is supported by the VENUS tool-set, comprising an OMT graphical editor, VDM++ syntax and type checker, and a C++ code generator. Formal specification meta-languages allow formal data modeling, algorithm and system behavior specification at a highly abstract level. Once an abstract design has converged it is refined towards a particular implementation, with formal validation of each step if desired. We have applied VDM++ to the design of a fast track pattern recognition algorithm; the design of a global second- level trigger system for LHC experiments; the specification of simulated physics data; and the design of a data router hardware unit for a LHC second-level trigger. We are encouraged by the application of mathematics in an engineering discipline and conclude that formal methods have the potential to make a valuable contribution to the systems development process in high energy physics.
CALCULATION OF TWO-LOOP VERTEX FUNCTIONS FROM THEIR SMALL MOMENTUM EXPANSION
Authors: FLEISCHER J.
Published: November 2004

In a recent paper1 a new powerful method to calculate Feynman diagrams was proposed. It consists in setting up a Taylor series expansion in the external momenta squared, a certain conformal mapping and subsequent resummation by means of Padé approximants. I present numerical examples.
TOTEM: A HIGHLY PARALLEL CHIP FOR TRIGGERING APPLICATIONS WITH INDUCTIVE LEARNING BASED ON THE REACTIVE TABU SEARCH
Authors: ANZELLOTTI G. , BATTITI R. , LAZZIZZERA I. , SONCINI G. , ZORAT A. , SARTORI A. , TECCHIOLLI G. , LEE P.
Published: November 2004

The training of a Multi-Layer Perceptron (MLP) classifier is considered as a Combinatorial Optimization task and solved using the Reactive Tabu Search (RTS) method. RTS needs only forward passes (no derivatives) and does not require high precision network parameters. TOTEM, a special-purpose VLSI chip, was developed to take advantage of the limited memory and processing requirements of RTS: the final system effects a very close match between hardware and training algorithm. The RTS algorithm and the design of TOTEM are discussed, together with the operational characteristics of the VLSI chip and some preliminary training and generalization tests on triggering tasks.
EXPERIENCE WITH THE IBM ZISC036 NEURAL NETWORK CHIP
Authors: LINDSEY CLARK S. , LINDBLAD THOMAS , SEKHNIAIDZE GIVI , SZÉKELY G. , MINERSKJÖLD M.
Published: November 2004

The new IBM Zero Instruction Set Computer (ZISC) provides a radial basis function neural network. The first generation chip (ZISC036) allows for 64 8-bit inputs, 36 RBF neurons in the middle layer, and up to 16383 possible output categories. Forward processing takes 4μs with a 20MHz clock. Cascading multiple chips increases the number of available RBF’s with no increase in processing time. The chip also executes a learning algorithm. We report on tests of the ZISC with a high energy physics related task.
Application of a Neural Network and a Genetic Algorithm in the Analysis of Multi Particle Final States
Authors: Degener Thomas F. , Kunze Marcel
Published: November 2004

The analysis of a particle physics experiment requires the correct selection of the desired multiplicity of charged (pions or kaons) and neutral (photons) particles. Due to fluctuations in hadronic and electromagnetic showers often too many photons are reconstructed by the analysis software. The combination of a feed forward neural network and a genetic algorithm is used to separate photons and fluctuations.
MANY MASSES ON ONE STROKE: ECONOMIC COMPUTATION OF QUARK PROPAGATORS
Authors: FROMMER ANDREAS , NÖCKEL BERTOLD , GÜSKEN STEPHAN , LIPPERT THOMAS , SCHILLING KLAUS
Published: November 2004

The computational effort in the calculation of Wilson fermion quark propagators in Lattice Quantum Chromodynamics can be considerably reduced by exploiting the Wilson fermion matrix structure in inversion algorithms based on the non-symmetric Lanczos process. We consider two such methods: QMR (quasi minimal residual) and BCG (biconjugate gradients).

Based on the decomposition M/κ = 1/κ−D of the Wilson mass matrix, using QMR, one can carry out inversions on a whole trajectory of masses simultaneously, merely at the computational expense of a single propagator computation. In other words, one has to compute the propagator corresponding to the lightest mass only, while all the heavier masses are given for free, at the price of extra storage.

Moreover, the symmetry γ5M = M†γ5 can be used to cut the computational effort in QMR and BCG by a factor of two. We show that both methods then become — in the critical regime of small quark masses — competitive to BiCGStab and significantly better than the standard MR method, with optimal relaxation factor, and CG as applied to the normal equations.
NUMERICAL CALCULATIONS OF THE SMALL RELATIVISTIC CORRECTIONS OF QUANTUM HARMONIC OSCILLATOR ENERGY EIGENVALUES
Authors: ARDELEAN GHEORGHE
Published: November 2004

The relativistic correction of the energy eigenvalues of quantum harmonic oscillator (QHO) are calculated using [Formula: see text] as eigenstates, for different values of the relativistic parameter α ≡ ħω/m0c2.
ERRORS IN MONTE CARLO SIMULATIONS USING SHIFT REGISTER RANDOM NUMBER GENERATORS
Authors: SCHMID F. , WILDING N. B.
Published: November 2004

We report large systematic errors in Monte Carlo simulations of the tricritical Blume–Capel model using single spin Metropolis updating. The error, manifest as a 20% asymmetry in the magnetization distribution, is traced to the interplay between strong triplet correlations in the shift register random number generator and the large tricritical clusters. The effect of these correlations is visible only when the system volume is a multiple of the random number generator lag parameter. No such effects are observed in related models.
PRECISE DETERMINATION OF THE CONDUCTIVITY EXPONENT OF 3D PERCOLATION USING "PERCOLA"
Authors: NORMAND JEAN-MARIE , HERRMANN HANS J.
Published: November 2004

Using 20 months of CPU time on our special purpose computer "Percola" we determined the exponent for the normal conductivity at the threshold of three-dimensional site and bond percolation. The extrapolation analysis taking into account the first correction to scaling gives a value of t/ν = 2.26±0.04 and a correction exponent ω around 1.4.
THE INFLUENCE OF INVESTOR NUMBER ON A MICROSCOPIC MARKET MODEL
Authors: HELLTHALER T.
Published: November 2004

The stock market model of Levy, Persky, Solomon is simulated for much larger numbers of investors. While small markets can lead to realistically looking prices, the resulting prices of large markets oscillate smoothly in a semi-regular fashion.
GRAVITOMAGNETIC MOMENTS AND DYNAMICS OF DIRAC (SPIN ½) FERMIONS IN FLAT SPACE–TIME MAXWELLIAN GRAVITY
Authors: BEHERA HARIHAR , NAIK P. C.
Published: November 2004

The gravitational effects in the relativistic quantum mechanics are investigated in a relativistically derived version of Heaviside's speculative gravity (in flat space–time) named here as "Maxwellian gravity." The standard Dirac's approach to the intrinsic spin in the fields of Maxwellian gravity yields the gravitomagnetic moment of a Dirac (spin ½) particle exactly equal to its intrinsic spin. Violation of the Equivalence Principle (both at classical and quantum-mechanical level) in the relativistic domain has also been reported in this work.
PROJECTORS, MATRIX MODELS AND NONCOMMUTATIVE MONOPOLES
Authors: VALTANCOLI P.
Published: November 2004

We study the interconnection between the finite projective modules for a fuzzy sphere, determined in a previous paper, and the matrix model approach, making clear the physical meaning of noncommutative topological configurations.
CASIMIR DENSITIES FOR TWO CONCENTRIC SPHERICAL SHELLS IN THE GLOBAL MONOPOLE SPACE–TIME
Authors: SAHARIAN A. A. , SETARE M. R.
Published: November 2004

The quantum vacuum effects are investigated for a massive scalar field with general curvature coupling and obeying the Robin boundary conditions given on two concentric spherical shells with radii a and b in the (D+1)-dimensional global monopole background. The expressions are derived for the Wightman function, the vacuum expectation values of the field square, the vacuum energy density, radial and azimuthal stress components in the region between the shells. A regularization procedure is carried out by making use of the generalized Abel–Plana formula for the series over zeros of combinations of the cylinder functions. This formula allows us to extract from the vacuum expectation values the parts due to a single sphere on background of the global monopole gravitational field, and to present the "interference" parts in terms of exponentially convergent integrals, useful, in particular, for numerical evaluations. The vacuum forces acting on the boundaries are presented as a sum of the self-action and interaction terms. The first one contains well-known surface divergences and needs a further regularization. The interaction forces between the spheres are finite for all values a<b and are attractive for a Dirichlet scalar. The asymptotic behavior of the vacuum densities is investigated (i) in the limits a→0 and b→∞, (ii) in the limit a, b→∞ for fixed value b-a, and (iii) for small values of the parameter associated with the solid angle deficit in global monopole geometry. We show that in the case (ii) the results for two parallel Robin plates on the Minkowski bulk are rederived to the leading order.
STRING THEORY AND THE FUZZY TORUS
Authors: BIGATTI DANIELA
Published: November 2004

We outline a brief description of noncommutative geometry and present some applications in string theory. We use the fuzzy torus as our guiding example.
HIGGS PARTICLES AT FUTURE HADRON AND ELECTRON-POSITRON COLLIDERS
Authors: DJOUADI A.
Published: November 2004

The prospects for discovering Higgs particles and studying their fundamental properties at future high-energy electron-positron and hadron colliders are reviewed. Both the Standard Model Higgs boson and the Higgs particles of its minimal supersymmetric extension are discussed. We update various results by taking into account the new value of the top-quark mass obtained by the CDF Collaboration, and by including radiative corrections, some of which have been calculated only recently.
QUANTUM GRAVITY AND MINIMUM LENGTH
Authors: GARAY LUIS J.
Published: November 2004

The existence of a fundamental scale, a lower bound to any output of a position measurement, seems to be a model-independent feature of quantum gravity. In fact, different approaches to this theory lead to this result. The key ingredients for the appearance of this minimum length are quantum mechanics, special relativity and general relativity. As a consequence, classical notions such as causality or distance between events cannot be expected to be applicable at this scale. They must be replaced by some other, yet unknown, structure.
MIRROR SYMMETRY OF THE K3 SURFACE
Authors: NAGURA MASARU , SUGIYAMA KATSUYUKI
Published: November 2004

We discuss the K3 surface and the complex torus from the viewpoint of “mirror symmetry.” We calculate the periods of some K3 surface and construct a mirror map for the two-point correlation function and the prepotential. We find that there are no instanton corrections of the Yukawa coupling for K3 (also torus), which is expected from the viewpoint of algebraic geometry.
REPRESENTATION TRANSFORMATION IN QUANTUM KANTOWSKI-SACHS UNIVERSE
Authors: HUANG CHAO-GUANG , YU (XIN YU) ALFRED
Published: November 2004

In this paper we study the quantum Kantowski-Sachs universe. We use the requirement that physical states be independent of the choice between the representations of canonical coordinate and conjugate momentum to pick out unphysical states of the universe from the mathematically general solutions of quantum Hamiltonian constraint equations.
WEAK AXIAL PION-EXCHANGE CURRENTS IN THE PSEUDOSCALAR πNN COUPLING
Authors: TRUHLIK E. , KHANNA F. C.
Published: November 2004

The operator of the weak axial meson-exchange currents of the pion range is derived in the pseudoscalar πNN coupling. Leading relativistic corrections are obtained up to the order ~1/M2. The operator is constructed on the basis of a phenomenological locally chiral-invariant Lagrangian and contains all contributions from the A1- and π-pole mediated currents. The extracted nuclear exchange-current operator satisfies the nuclear continuity equation in the considered order in 1/M.
ON THE FORM OF LOCAL CONSERVATION LAWS FOR SOME RELATIVISTIC FIELD THEORIES IN 1 + 1 DIMENSIONS
Authors: HOHLER ERLING G.B. , OLAUSSEN KÅRE
Published: November 2004

We investigate the possible form of local translation-invariant conservation laws associated with the relativistic field equations [Formula: see text] for a multicomponent field ϕ. Under the assumptions that (i) the vi' s can be expressed as linear combinations of partial derivatives ∂wj / ∂ϕk of a set of functions wj (ϕ), (ii) the space of functions spanned by the wj' s is closed under partial derivations, and (iii) the fields ϕ take values in a simply connected space, the local conservation laws can be transformed either to the form [Formula: see text] (where [Formula: see text] and [Formula: see text] are homogeneous polynomials in the variables [Formula: see text]), or to the parity-transformed version of this expression, [Formula: see text].
COSMOLOGY CONFRONTS THE COSMIC MICROWAVE BACKGROUND
Authors: STEINHARDT PAUL J.
Published: November 2004

Observational tests during the next decade may determine if the evolution of the Universe can be understood from fundamental physical principles, or if special initial conditions, coincidences, and new, untestable physical laws must be invoked. The inflationary model of the Universe is an important example of a predictive cosmological theory based on physical principles. In this article, we discuss the distinctive fingerprint that inflation leaves on the cosmic microwave background anisotropy. We then suggest a series of five milestone experimental tests of the microwave background which could determine the validity of the inflationary hypothesis within the next decade.
MASS SCALE IN THE SINE–GORDON MODEL AND ITS REDUCTIONS
Authors: ZAMOLODCHIKOV AL. B.
Published: November 2004

Known Bethe ansatz results about the sine–Gordon factorized scattering are reinterpreted in terms of perturbed conformal field theory. We obtain an exact relation between the ultraviolet and asymptotic scales (i.e. between the dimensional coupling constant and the soliton mass) and an explicit expression for the vacuum energy. The reduction technique then permits one to relate exactly the coupling constants and the mass scales in the Φ13-perturbed minimal CFT models. The preasymptotically free situation at β2 near 8π is discussed on a preliminary footing.
IS SUPERSYMMETRY REALLY BROKEN?
Authors: WITTEN EDWARD
Published: November 2004

In 2 + 1 dimensions, in the presence of gravity, supersymmetry can ensure the vanishing of the cosmological constant without requiring the equality of Bose and Fermi masses.
MATRIX ELEMENT AND COMPLEX l PLANE EVALUATION OF TWO-LOOP VACUUM AMPLITUDES IN QED ON S4
Authors: HARRIS B.A. , JOSHI G.C.
Published: November 2004

In this paper we further develop our matrix element and complex angular momentum summation techniques, in order to calculate both the one-loop free field and two-loop interacting vacuum diagrams in field theory on a four-sphere. In the case of the free field diagrams, we show how the sums may be evaluated by integrating over an analytic function with both poles and branch cuts where the discontinuity across the cuts determines the result. We then extend the matrix element formalism to multiple angular momenta involving the addition of angular momenta and the associated Clebsch-Gordon type selection rules. This then allows us to evaluate the matrix elements of two-loop diagrams in spherical QED as a function of the three angular momenta in the diagram. The selection rules allow us to cast the triple angular momentum sum into a form which enables evaluation again by contour integration. The result is obtained in analytic form using dimensional regularization for the previously obtained spinor case, and also for scalar QED, which we believe is a new result. Finally, we discuss the applicability of this method for calculations in non-Abelian field theory which we believe cannot be performed using earlier methods.
THE SINE-GORDON MODEL AS $\mathcal{SO}(2n)_{1} \times \mathcal{SO}(2n)_{1} \over \mathcal{SO}(2n)_{2}$-PERTURBED COSET THEORY AND GENERALIZATIONS
Authors: TATEO R.
Published: November 2004

The ground state energies of the [Formula: see text] coset theories, perturbed by the [Formula: see text] operator, and those of the sine-Gordon theory, for special values of the coupling constant in the attracting regime, are the same. In the first part of this paper we extend these results to the [Formula: see text] cases. In the second part, we analyze the algebraic Bethe ansatz procedure for special points in the repulsive region. We find a one-to-one “duality” correspondence between these theories and those studied in the first part of the paper. We use the gluing procedure at the massive node proposed by Fendley and Intriligator in order to obtain the TBA systems for the generalized parafermionic supersymmetric sine-Gordon model. In the third part we propose the TBA equations for the whole class of perturbed coset models [Formula: see text] with the operator [Formula: see text] and G a nonsimplylaced group generated by one of the [Formula: see text], ℱ4, ℬn, [Formula: see text] algebras.
MINIMAL STRING UNIFICATION AND YUKAWA COUPLINGS IN ORBIFOLD MODELS
Authors: KOBAYASHI TATSUO
Published: November 2004

We study the minimal supersymmetric standard model derived from ZN×ZM orbifold models. Moduli-dependent threshold corrections of gauge couplings are investigated to explain the measured values of the coupling constants. We also study the Yukawa couplings of the models. We find that the Z2×Z2×Z6′, Z3×Z6 and Z6×Z6 orbifold models have the possibility of deriving Yukawa couplings for the second and third generations as well as the measured gauge coupling constants. Allowed models are shown explicitly by combinations of modular weights for the matter fields.
SPECTRUM OF THE TRANSFER MATRIX FOR THE Uq(Bn)-INVARIANT $A_{2n}^{(2)}$ OPEN SPIN CHAIN
Authors: ARTZ SIMONE , MEZINCESCU LUCA , NEPOMECHIE RAFAEL I.
Published: November 2004

We propose an expression for the eigenvalues of the transfer matrix for the Uq(Bn)-invariant open quantum spin chain associated with the fundamental representation of [Formula: see text] By assumption, the Bethe ansatz equations are “doubled” with respect to those of the corresponding closed chain with periodic boundary conditions. We verify that the transfer matrix eigenvalues have the correct analyticity properties and asymptotic behavior. We also briefly discuss the structure of the eigenstates of the transfer matrix.
EDGE STATES IN GAUGE THEORIES: THEORY, INTERPRETATIONS AND PREDICTIONS
Authors: BALACHANDRAN A.P. , CHANDAR L. , ERCOLESSI E.
Published: November 2004

Gauge theories on manifolds with spatial boundaries are studied. It is shown that observables localized at the boundaries (edge observables) can occur in such models irrespective of the dimensionality of space-time. The intimate connection of these observables to charge fractionation, vertex operators and topological field theories is described. The edge observables, however, may or may not exist as well-defined operators in a fully quantized theory depending on the boundary conditions imposed on the fields and their momenta. The latter are obtained by requiring the Hamiltonian of the theory to be self-adjoint and positive-definite. We show that these boundary conditions can also have nice physical interpretations in terms of certain experimental parameters, such as the penetration depth of the electromagnetic field in a surrounding superconducting medium. The dependence of the spectrum on one such parameter is explicitly exhibited for the Higgs model on a spatial disk in its London limit. It should be possible to test such dependences experimentally, the above Higgs model for example being a model for a superconductor. Boundary conditions for the (3+1)-dimensional BF system confined to a spatial ball are studied. Their physical meaning is clarified and their influence on the edge states of this system (known to exist under certain conditions) is discussed. It is pointed out that edge states occur for topological solitons of gauge theories such as the ’t Hooft-Polyakov monopoles.
GENERALIZED KAZAKOV-MIGDAL-KONTSEVICH MODEL: GROUP THEORY ASPECTS
Authors: KHARCHEV S. , MARSHAKOV A. , MIRONOV A. , MOROZOV A.
Published: November 2004

The Kazakov-Migdal model, if considered as a functional of external fields, can always be represented as an expansion over characters of the GL group. The integration over “matter fields” can be interpreted as going over the model (the space of all highest weight representations) of GL. In the case of compact unitary groups the integrals should be substituted by discrete sums over the weight lattice. The D=0 version of the model is the generalized Kontsevich integral, which in the above-mentioned unitary (discrete) situation coincides with the partition function of 2D Yang-Mills theory with the target space of genus g=0 and m=0, 1, 2 holes. This particular quantity is always a bilinear combination of characters and appears to be a Toda lattice τ function. (This is a generalization of the classical statement that individual GL characters are always singular KP τ functions.) The corresponding element of the universal Grassmannian is very simple and somewhat similar to the one arising in investigations of the c=1 string models. However, in certain circumstances the formal sum over representations should be evaluated by the steepest descent method, and this procedure leads to some more-complicated elements of the Grassmannian. This “Kontsevich phase,” as opposed to the simple “character phase,” deserves further investigation.
THE STRING CALCULATION OF WILSON LOOPS IN TWO-DIMENSIONAL YANG-MILLS THEORY
Authors: NACULICH STEPHEN G. , RIGGS HAROLD A. , SCHNITZER HOWARD J.
Published: November 2004

We demonstrate that the large N expansion of Wilson loop expectation values in SO (N) and Sp (N) Yang-Mills theory on orientable and nonorientable surfaces has a natural description as a weighted sum over covers of the given surface. The sum takes the form of the perturbative expansion of an open string theory. The derivation makes contact with the classification of branched covers by Gabai and Kazez. Comparison with the analogous results for the chiral sectors of QCD 2 is instructive for both cases.
QUANTIZING HIGHER-SPIN STRING THEORIES
Authors: LU H. , WANG X.J. , XU K.-W. , POPE C.N. , THIELEMANS K.
Published: November 2004

In this paper, we examine the conditions under which a higher-spin string theory can be quantized. The quantizability is crucially dependent on the way in which the matter currents are realized at the classical level. In particular, we construct classical realizations for the W2,s algebra, which is generated by a primary spin-s current in addition to the energy-momentum tensor, and discuss the quantization for s≤8. From these examples we see that quantum BRST operators can exist even when there is no quantum generalization of the classical W2,s algebra. Moreover, we find that there can be several inequivalent ways of quantizing a given classical theory, leading to different BRST operators with inequivalent cohomologies. We discuss their relation to certain minimal models. We also consider the hierarchical embeddings of string theories proposed recently by Berkovits and Vafa, and show how the already known W strings provide examples of this phenomenon. Attempts to find higher-spin fermionic generalizations lead us to examine whether classical BRST operators for [Formula: see text](n odd) algebras can exist. We find that even though such fermionic algebras close up to null fields, one cannot build nilpotent BRST operators, at least of the standard form.
SINGULAR VECTORS OF THE N=2 SUPERCONFORMAL ALGEBRA
Authors: DÖRRZAPF MATTHIAS
Published: November 2004

We derive a set of recursion formulae to construct singular vectors for the N=2 (untwisted) algebra, by using the approach of Bauer, di Francesco, Itzykson and Zuber. Applying these formulae, we obtain explicit expressions for the charged singular vectors and for a class of uncharged singular vectors.
PHASE STRUCTURE OF FOUR-FERMION THEORIES AT FINITE TEMPERATURE AND CHEMICAL POTENTIAL IN ARBITRARY DIMENSIONS
Authors: INAGAKI T. , KOUNO T. , MUTA T.
Published: November 2004

The phase structure of four-fermion theories is thoroughly investigated with varying temperature and chemical potential for arbitrary space-time dimensions (2≤D<4) by using the 1/N expansion method. It is shown that the chiral symmetry is restored in the theory under consideration for sufficiently high temperature and/or chemical potential. The critical line dividing the symmetric and the broken phase is given explicitly. It is found that for space-time dimension 2≤D<3 both the first order and the second order phase transition occur depending on the value of the temperature and chemical potential while for 3≤D<4 only the second order phase transition exists.
THE FINITE VACUUM ENERGY FOR SPINOR, SCALAR AND VECTOR FIELDS
Authors: SHTYKOV N.N.
Published: November 2004

We compute the one-loop potential (the Casimir energy) for scalar fields with coupling ξR and massive spinor and vector fields on the spaces Rm+1×Y with Y=SN, CP2. We find that in most of the models a divergent part of the Casimir energy on even-dimensional spaces is canceled by means of the appropriate values of ξ, msp, mv. As a physical model we consider spinor electrodynamics on four-dimensional product manifolds and show that the Casimir energy is finite on R1×S3, R3×S1 and R2×S2 for msp=0, msp=0 and [Formula: see text] respectively.
COSET REALIZATION OF UNIFYING ${\mathcal W}$ ALGEBRAS
Authors: BLUMENHAGEN R. , EHOLZER W. , HONECKER A. , HÜBEL R. , HORNFECK K.
Published: November 2004

We construct several quantum coset [Formula: see text] algebras, e.g. [Formula: see text] and [Formula: see text] and argue that they are finitely nonfreely generated. Furthermore, we discuss in detail their role as unifying [Formula: see text] algebras of Casimir [Formula: see text] algebras. We show that it is possible to give coset realizations of various types of unifying [Formula: see text] algebras; for example, the diagonal cosets based on the symplectic Lie algebras sp (2n) realize the unifying [Formula: see text] algebras which have previously been introduced as [Formula: see text]. In addition, minimal models of [Formula: see text] are studied. The coset realizations provide a generalization of level-rank duality of dual coset pairs. As further examples of finitely nonfreely generated quantum [Formula: see text] algebras, we discuss orbifolding of [Formula: see text] algebras which on the quantum level has different properties than in the classical case. We demonstrate through some examples that the classical limit — according to Bowcock and Watts — of these finitely nonfreely generated quantum [Formula: see text] algebras probably yields infinitely nonfreely generated classical [Formula: see text] algebras.
SOME LOW ORDER TWO-STEP ALMOST P-STABLE METHODS WITH PHASE-LAG OF ORDER INFINITY FOR THE NUMERICAL INTEGRATION OF THE RADIAL SCHRÖDINGER EQUATION
Authors: SIMOS T.E.
Published: November 2004

Some two-step P-stable methods with phase-lag of order infinity are developed for the numerical integration of the radial Schrödinger equation. The methods are of O(h2) and O(h4) respectively. We produce, based on these methods and on a new local error estimate, a very simple variable step procedure. Extensive numerical testing indicates that these new methods are generally more accurate than other two-step methods with higher algebraic order.
POISSON ALGEBRA OF WILSON LOOPS IN FOUR-DIMENSIONAL YANG-MILLS THEORY
Authors: RAJEEV S.G. , TURGUT O.T.
Published: November 2004

We formulate the canonical structure of Yang-Mills theory in terms of Poisson brackets of gauge-invariant observables analogous to Wilson loops. This algebra is nontrivial and tractable in a light cone formulation. For U (N) gauge theories the result is a Lie algebra while for SU (N) gauge theories it is a quadratic algebra. We also study the identities satisfied by the gauge-invariant observables. We suggest that the phase space of a Yang-Mills theory is a coadjoint orbit of our Poisson algebra; some partial results in this direction are obtained.
GENERALIZED HIROTA EQUATIONS AND REPRESENTATION THEORY I: THE CASE OF SL(2) AND SLq(2)
Authors: GERASIMOV A. , KHOROSHKIN S. , LEBEDEV D. , MIRONOV A. , MOROZOV A.
Published: November 2004

This paper begins investigation of the concept of a “generalized τ function,” defined as a generating function of all the matrix elements of a group element g∈G in a given highest weight representation of a universal enveloping algebra [Formula: see text]. In the generic situation, the time variables correspond to the elements of maximal nilpotent subalgebras rather than Cartanian elements. Moreover, in the case of quantum groups such τ “functions” are not c numbers but take their values in noncommutative algebras (of functions on the quantum group G). Despite all these differences from the particular case of conventional τ functions of integrable (KP and Toda lattice) hierarchies [which arise when G is a Kac-Moody (one-loop) algebra of level k=1], these generic τ functions also satisfy bilinear Hirota-like equations, which can be deduced from manipulations with intertwining operators. The most important applications of the formalism should be to k>1 Kac-Moody and multiloop algebras, but this paper contains only illustrative calculations for the simplest case of ordinary (zero-loop) algebra SL (2) and its quantum counterpart SL q(2), as well as for the system of fundamental representations of SL (n).
SECOND ORDER DERIVATIVE SUPERSYMMETRY, q DEFORMATIONS AND THE SCATTERING PROBLEM
Authors: ANDRIANOV A.A. , IOFFE M.V. , CANNATA F. , DEDONDER J.-P.
Published: November 2004

In a search for pairs of quantum systems linked by dynamical symmetries, we give a systematic analysis of novel extensions of standard one-dimensional supersymmetric quantum mechanics. The most general supercharges involving higher order derivatives are introduced, leading to an algebra which incorporates a higher order polynomial of the Hamiltonian. We investigate the condition for irreducibility of such a higher order generator to a product of standard first derivative Darboux transformations. As a new example of application of this approach we study the quantum-mechanical radial problem including the scattering amplitudes. We also investigate the links between this higher derivative SUSY and a q-deformed supersymmetric quantum mechanics and introduce the notion of self-similarity in momentum space. An explicit model for the scattering amplitude is constructed in terms of a hypergeometric function which corresponds to a reflectionless potential with infinitely many bound states.
SYMPLECTIC GEOMETRY AND HAMILTONIAN FLOW OF THE RENORMALIZATION GROUP EQUATION
Authors: DOLAN BRIAN P.
Published: November 2004

It is argued that renormalization group flow can be interpreted as a Hamiltonian vector flow on a phase space which consists of the couplings of the theory and their conjugate “momenta,” which are the vacuum expectation values of the corresponding composite operators. The Hamiltonian is linear in the conjugate variables and can be identified with the vacuum expectation value of the trace of the energy-momentum operator. For theories with massive couplings the identity operator plays a central role and its associated coupling gives rise to a potential in the flow equations. The evolution of any quantity, such as N-point Green functions, under renormalization group flow can be obtained from its Poisson bracket with the Hamiltonian. Ward identities can be represented as constants of the motion which act as symmetry generators on the phase space via the Poisson bracket structure.
PRECISION DETERMINATION OF αs AND mb FROM QCD SUM RULES FOR $b\bar b$
Authors: VOLOSHIN M.B.
Published: November 2004

The QCD sum rules for moments of the production cross section of [Formula: see text] states in e+ e− annihilation are extremely sensitive to the values of mb and αs for moments of large order n. This enables one to extract from the existing data on ϒ resonances the values of these parameters with a high precision by using a nonrelativistic expansion in 1/n. It is found that the sum rules fit the data with [Formula: see text] and mb=4827±7 MeV, where the estimate of the errors includes the theoretical uncertainty due to subleading-in-1/n terms and the experimental uncertainty of the e+ e− annihilation cross section above the [Formula: see text] threshold. The found value of αs, when evolved in two loops up to the Z mass, gives [Formula: see text]. The b quark mass mb corresponds to the “on-shell” value appropriate for one-loop perturbative calculations.
QUARKONIUM PRODUCTION IN HADRONIC COLLISIONS
Authors: GAVAI R. , KHARZEEV D. , SATZ H. , SCHULER G.A. , SRIDHAR K. , VOGT R.
Published: November 2004

We summarize the theoretical description of charmonium and bottonium production in hadronic collisions and compare it to the available data from hadron-nucleon interactions. With the parameters of the theory established by these data, we obtain predictions for quarkonium production at RHIC and LHC energies.
POSSIBLE EXISTENCE OF TOPPED HADRONS
Authors: ITO TOSHIAKI , SAWADA SHOJI
Published: November 2004

We study possibilities of formation of the topped hadrons, the [Formula: see text], [Formula: see text], tqq, ttq and ttt bound systems. We assume that the inverse of binding energy is the parameter of the formation time of the bound system and take the ratio Γtotal/EB as a criterion for the formation of these hadrons, where EB and Γtotal are a binding energy and a total decay width of a topped system respectively. We take into account the binding force caused by the Higgs scalar exchange as well as the one-gluon exchange. It is shown that there is no possibility of forming the single top quark hadrons before the top quark decay. In the standard model, where only one Higgs doublet contributes, among the topped hadrons only toponium [Formula: see text] and the three-top-quark baryon Ωttt with the top quark mass less than 140 GeV and 130 GeV have a possibility of forming the bound states before their decay. In the case of the two-Higgs-doublet model we show that there is a possibility of forming the topped hadrons, toponium, Ξtt and Ωttt for the larger top quark mass if the ratio of vacuum expectation values of two Higgs scalars is large near to the unitarity bound.
QUASI TWO-BODY DECAYS OF CHARM MESONS
Authors: TERASAKI K.
Published: November 2004

Quasi two-body decays of charm mesons are studied by using a hard-meson approximation in which the amplitude M is given by M≃METC+MS. The surface term MS is given by a sum of all possible pole amplitudes involving contributions of four-quark and hybrid mesons in addition to ground-state [Formula: see text] mesons. Contributions of multihadron intermediate states are taken in the form of METC. The spectator type of decays can have significant contributions of s-channel poles of four-quark mesons. In the annihilation type of decays, s-channel hybrid-meson poles can play an important role. The mixed type of decays can have all the pole contributions of the ground-state [Formula: see text], possible hybrid and four-quark mesons in the s-channel.

The estimated branching ratios, [Formula: see text] and [Formula: see text] are of ordinary size, in contrast with the factorization which predicts very large rates for these decays. The [Formula: see text] and [Formula: see text] decays can be suppressed in consistency with the other decays.
CORE DEFORMATIONS OF TOPOLOGICAL DEFECTS
Authors: BAIS F. ALEXANDER , JOHN PER
Published: November 2004

We consider phases of spontaneously broken gauge theories in which different types of topological excitations, like flux tubes, monopoles etc., coexist. We analyze the topological relations which exist between the charges, and give a description of the admissible core deformations in terms of certain cohomology groups that occur in obstruction theory. Simple examples are worked out in detail.
ON TYPE I QUANTUM AFFINE SUPERALGEBRAS
Authors: DELIUS GUSTAV W. , GOULD MARK D. , LINKS JON R. , ZHANG YAO-ZHONG
Published: November 2004

The type I simple Lie superalgebras are sl(m|n) and osp(2|2n). We study the quantum deformations of their untwisted affine extensions Uq[sl(m|n)(1)] and Uq[osp(2|2n)(1)]. We identify additional relations between the simple generators (“extra q Serre relations”) which need to be imposed in order to properly define Uq[sl(m|n)(1)] and Uq[osp(2|2n)(1)]. We present a general technique for deriving the spectral-parameter-dependent R matrices from quantum affine superalgebras. We determine the R matrices for the type I affine superalgebra Uq[sl(m|n)(1)] in various representations, thereby deriving new solutions of the spectral-parameter-dependent Yang-Baxter equation. In particular, because this algebra possesses one-parameter families of finite-dimensional irreps, we are able to construct R matrices depending on two additional spectral-parameter-like parameters, providing generalizations of the free fermion model.
CYCLIC PERMUTATIONS IN KAZAMA-SUZUKI STRING MODELS
Authors: ALDAZABAL G. , ALLEKOTTE I. , ANDRÉS E. , NÚÑEZ C.
Published: November 2004

Moddings by cyclic permutation symmetries are performed on four-dimensional strings, built from N=2 coset models of the type CPm=SU(m+1)/[SU(m)×U(1)]. For some illustrative cases, the massless chiral and antichiral states of E6 are computed. The extent of the equivalence between different conformal invariant theories which possess equal chiral rings is analyzed.
CRITICAL BEHAVIOR IN (2+1)-DIMENSIONAL QED WITH A FOUR-FERMION INTERACTION
Authors: KYE WON-HO , LEE JAE SIK , KIM JAE KWAN
Published: November 2004

We analyze QED3 with a scalar-scalar type four-fermion interaction in the framework of 1/N expansion. We have derived the Dyson-Schwinger gap equation up to the next-to-leading order and determined the dynamically generated fermion mass as a function of the number of fermion flavors N and a scaled coupling θ. We observe that the critical behaviors are separated by the point [Formula: see text] and, contrary to the leading behaviors, there are mass generations even when θ ≥ θc with the critical flavor Nc. The critical line on the Nc−θc plane is presented. We also discuss the vacuum stability of our model, and confirm that our nontrivial solutions are energetically preferred to the perturbative solution Σ(p)=0.
A q-DEFORMED VERSION OF THE HEAVENLY EQUATIONS
Authors: PLEBAŃSKI J.F. , GARCÍA-COMPEÁN H.
Published: November 2004

Using a q-deformed Moyal algebra associated with the group of area-preserving diffeomorphisms of the two-dimensional torus T2, sdiffq(T2), a q-deformed version of the heavenly equations is given. In addition, the two-dimensional chiral version of self-dual gravity in this q-deformed context is briefly discussed.
THE CALOGERO MODEL AND THE VIRASORO SYMMETRY
Authors: BERGSHOEFF E. , VASILIEV M.
Published: November 2004

We construct new realizations of the Virasoro algebra inspired by the Calogero model. The Virasoro algebra we find acts as a kind of spectrum-generating algebra of the Calogero model. Furthermore, we present the superextension of these results and introduce a class of higher spin extensions of the Virasoro algebra which are of the W∞ type.
METHODS OF CALCULATION OF HIGHER POWER CORRECTIONS IN QCD
Authors: GROZIN A.G.
Published: November 2004

Although the methods of calculation of power corrections in QCD sum rules are well known, algebraic complexity rapidly grows with the increase of vacuum condensates’ dimensions. Currently, state-of-the-art calculations include dimension 7 and 8 condensates. I summarize and extend algorithms of such calculations. First, I present all the formulae necessary for application of the systematic classification of bilinear quark condensates proposed earlier, and extend this method to the case of gluon condensates. Then I apply these systematic procedures to expansions of bilinear and noncollinear quark and gluon condensates in local ones, and of noncollinear condensates in bilocal ones. The formulae obtained can be used for calculation of correlators involving non-local condensates, and for inventing consistent ansätze for these condensates. Finally, I summarize the methods of calculation of heavy and light quark currents’ correlators. This paper aims both to present new results on gluon and nonlocal condensates and to be a self-contained handbook of formulae necessary for calculation of power corrections in QCD sum rules.