bluuebunny/crossref_metadata_2025 huggingface dataset:
PARALLELISM ON THE INTEL 860 HYPERCUBE: ISING MAGNETS, HYDRODYNAMICAL CELLULAR AUTOMATA AND NEURAL NETWORKS
Authors: KOHRING G.A. , STAUFFER D.
Published: November 2004

Geometric parallelization was tested on the Intel Hypercube with 32 MIMD processors of 1860 type, each with 16 Mbytes of distributed memory. We applied it to Ising models in two and three dimensions as well as to neural networks and two-dimensional hydrodynamic cellular automata. For system sizes suited to this machine, up to 60960*60960 and 1410*1410*1408 Ising spins, we found nearly hundred percent parallel efficiency in spite of the needed inter-processor communications. For small systems, the observed deviations from full efficiency were compared with the scaling concepts of Heermann and Burkitt and of Jakobs and Gerling. For Ising models, we determined the Glauber kinetic exponent z≃2.18 in two dimensions and confirmed the stretched exponential relaxation of the magnetization towards the spontaneous magnetization below Tc. For three dimensions we found z≃2.09 and simple exponential relaxation.
THREE-DIMENSIONAL VISUALIZATION OF MOLECULAR ORGANIZATION AND PHASE TRANSITIONS IN LIQUID CRYSTAL LATTICE MODELS
Authors: CHICCOLI CESARE , PASINI PAOLO , SEMERIA FRANCO , ZANNONI CLAUDIO
Published: November 2004

An example of three-dimensional animation of Monte Carlo simulation results of liquid crystal lattice models is presented. Molecular configurations are obtained from Monte Carlo simulations on a VAX cluster and downloaded to a 486 personal computer. Visualization of molecular organizations and of their change at a phase transition is obtained by suitable colour coding of orientations and of other relevant physical information on the personal computer, and recorded on a VHS system using a genlock card. The animation sequences generated have a twofold interest: they are useful for educational purposes and, from a scientific point of view, they provide a tool for exploring a large amount of data and investigating the phenomena under study in a non-numerical way.
A PARALLEL CLUSTER LABELING METHOD FOR MONTE CARLO DYNAMICS
Authors: FLANIGAN MIKE , TAMAYO PABLO
Published: November 2004

We present an algorithm for cluster dynamics to efficiently simulate large systems on MIMD parallel computers with large numbers of processing nodes. The method divides physical space into rectangular cells which are assigned to processing nodes and combines a serial procedure, by which clusters are labeled locally inside each cell, with a nearest neighbor relaxation process in which processing nodes exchange labels until a fixed point is reached. By controlling overhead and reducing inter-processor communication this method attains good performance and speed-up. The complexity and scaling properties of the algorithm are analyzed. The algorithm has been used to simulate large two-dimensional Ising systems (up to 27808×27808 sites) with Swendsen-Wang dynamics. Typical updating times on the order of 82 nanosecs/site and efficiencies larger than 90% have been obtained using 256 processing nodes on the CM-5 supercomputer.
MULTICANONICAL SPIN GLASS SIMULATIONS
Authors: BERG BERND A. , CELIK TARIK
Published: November 2004

We report a Monte Carlo simulation of the 2D Edwards-Anderson spin glass model within the recently introduced multicanonical ensemble. Replica on lattices of size L2 up to L=48 are investigated. Once a true groundstate is found, we are able to give a lower bound on the number of statistically independent groundstates sampled. Temperature dependence of the energy, entropy and other quantities of interest are easily calculable. In particular we report the groundstate results. Our data indicate that the large L increase of the ergodicity time is reduced to an approximately V3 power law. Altogether the results suggest that the multicanonical ensemble improves the situation of simulations for spin glasses and other systems which have to cope with similar problems of conflicting constraints.
SUPERSYMMETRIC CONTRIBUTIONS TO THE CP ASYMMETRY OF THE B→ϕKS AND B→η'KS
Authors: KHALIL SHAABAN
Published: November 2004

We analyse the CP asymmetry of the B→ϕKS and B→η'KS processes in general supersymmetric models. We consider both gluino and chargino exchanges in a model-independent way by using the mass insertion approximation method. We adopt the QCD factorization method for evaluating the corresponding hadronic matrix elements. We show that chromomagnetic type of operator may play an important role in accounting for the deviation of the mixing CP asymmetry between B→ϕKS and B→J/ψKS processes observed by Belle and BaBar experiments. We also show that due to the different parity in the final states of these processes, their supersymmetric contributions from the R-sector have an opposite sign, which naturally explain the large deviation between their asymmetries.
THE B-MESON DECAY CONSTANT ON THE LATTICE WITH THE STATIC APPROXIMATION
Authors: HASHIMOTO SHOJI , SAEKI YUJI
Published: November 2004

The B-meson decay constant f B is calculated using the static approximation on the lattice. Our result for f B shows a large dependence on the size of smearing of operators used to create the B-meson. This result implies that one cannot extract the reliable physical value of f B from the lattice simulation with the static approximation.
MASSLESS SCALAR CASIMIR EFFECT IN A CLASS OF HYPERBOLIC KALUZA-KLEIN SPACE-TIMES
Authors: BYTSENKO ANDREI A. , VANZO LUCIANO , ZERBINI SERGIO
Published: November 2004

In the framework of heat-kernel approach to zeta-function regularization we calculate the one-loop effective potential (Casimir effect) massless scalar field on Kaluza-Klein space-time of the form RD−n×Hn/Γ(2≤n<D). In addition the Selberg trace formula associated with discrete torsion-free group Γ of the n-dimensional Lobachevsky space Hn is used. A negative Casimir effect related to trivial line bundle with character χ=1 is found. A comparison of the results obtained and Casimir effect for massless field on torus backgrounds is also presented.
CLASSICAL DIFFEOMORPHISM INVARIANT THEORIES AND LINKING NUMBERS
Authors: LEAL LORENZO
Published: November 2004

The effective action associated to a class of Abelian topological field theories with static sources is shown to give the linking number of the sources.
QUARK-ANTIQUARK CONDENSATES IN STRONG MAGNETIC FIELDS
Authors: SCHRAMM STEFAN , MÜLLER BERNDT , SCHRAMM ALEC J.
Published: November 2004

We discuss the effect of large external magnetic fields on the QCD vacuum structure. We show that the deformed vacuum leads to substantial changes in the hadronic spectrum.
ON THE INTERPOLATING SOLUTIONS OF STRING IN DIFFERENT BACKGROUNDS
Authors: MUKHERJI SUDIPTA
Published: November 2004

We analyze the β-function equations for string theory in the case when the target space has one space-like (or time-like) direction and the rest is some conformal field theory (CFT) with appropriate central charge and has one nearly marginal operator. We show there always exists a space-(time) dependent solution which interpolates between the original background and the background where CFT is replaced by a new conformal field theory, obtained by perturbing CPT by the nearly marginal operator.
THE “MYSTERY” OF σ(700)-MESON EXCHANGE IN γγ→ππ PROCESSES
Authors: IVANOV A.N. , NAGY M. , TROITSKAYA N.I.
Published: November 2004

The problem of the “mystery” of the σ(700)-meson contribution to the γγ→ππ and [Formula: see text] scattering amplitudes at low energies is studied at the quark level within a soft-pion-constituent-quark diagram technique. The Terent’ev low-energy theorem is derived at the quark level.
ANALYTIC FINAL STATE CORRECTIONS WITH CUT FOR e+e−→MASSIVE FERMIONS
Authors: ARBUZOV A.B. , BARDIN D. YU. , LEIKE A.
Published: November 2004

Analytic results for final state corrections to the differential and total cross-section for e+e−→massive fermions are presented. In the phase space integration a cut 011 the photon energy was included. The numerical importance of the obtained results is shown for QED and QCD corrections to r, b and t-quark production. Final state corrections are changed considerably by applying a cut on the photon energy. All results are immediately applicable to theories with several neutral gauge bosons.
SYNCYCLONS OR SOLITONIC SIGNALS FROM EXTRA DIMENSIONS
Authors: AULAKH C. S.
Published: November 2004

In theories where space-time is a direct product of Minkowski space (M4) and a d-dimensional compact space (Kd), there can exist topological solitons that simultaneously wind around ℝ3 (or ℝ2 or ℝ1) in M4 and the compact dimensions. A paradigmatic non-gravitational example of such "co-winding" solitons is furnished by Yang-Mills theory defined on M4 × S1. Point-like, string-like and sheet-like solitons can be identified by transcribing and generalizing the procedure used to construct the periodic instanton (caloron) solutions. Asymptotically the classical point-like objects have non-Abelian magnetic dipole fields together with a non-Abelian scalar potential while the "color" electric charge is zero. However quantization of collective coordinates associated with zero modes and coupling to fermions can radically change these quantum numbers due to fermion number fractionalization and its non-Abelian generalization. Interpreting the YM group as color (or the electroweak SU(2) group) and assuming that an extra circular dimension exists thus implies the existence of topologically stable solitonic objects which carry baryon(lepton) number and a mass O(1/g2R), where R is the radius of the compact dimension.
CIRCUMSTANCES OF FERMION FRACTIONIZATION IN HIGH DENSITY FERMI GAS
Authors: KHVIENGIA Z. , TOKAREV V. F.
Published: November 2004

We consider a (3 + 1)-dimensional SU(2)-gauge theory which is known to possess the fractional fermions. These are the monopoles.

We compute the fermion number of a monopole in the dense Fermi gas and find the conditions under which fermions decay into the monopoles.
CAN POLARIZED DRELL-YAN SHED MORE LIGHT ON THE PROTON SPIN?
Authors: MATHEWS PRAKASH , RAVINDRAN V.
Published: November 2004

We analyze polarized Drell-Yan process using the factorization method and derive operator definitions for polarized parton distribution functions. We demonstrate that a factorization analogous to that in the unpolarized Drell-Yan case holds in this process. We study the leading order gluonic contribution to the first moment of polarized Drell-Yan function and show that it is consistent with the results obtained from polarized deep inelastic scattering.
CHARGED CIRCULAR TEST-STRING IN EXTERNAL MAGNETIC FIELDS
Authors: LARSEN A. L.
Published: November 2004

We consider a charged (and superconducting) circular Nambu-Goto string in external magnetic fields. Exploiting the cylindrical symmetry of the problem we arrive at an effective potential for the string radius which completely determines the dynamics of the string. One of the most important tasks for this effective potential, which is a functional of the almost arbitrary external fields, is to decide whether non-collapsing configurations exist. A few examples are considered in detail.
MATTER FIELD KÄHLER POTENTIALS FOR Z3 × Z3 AND Z3 ORBIFOLD THEORIES
Authors: BAILIN DAVID , LOVE ALEX
Published: November 2004

The matter field Kähler potential to quadratic order in the moduli is derived, by direct calculation of string amplitudes, for Z3 × Z3 orbifold models with arbitrary Wilson lines and arbitrary embeddings of the point group in the gauge group. The Z3 orbifold is also discussed.
RIGHT-HANDED COUPLINGS AND CP VIOLATION IN W BOSON DECAY
Authors: TANAKA MINORU
Published: November 2004

Parity and CP violation in W boson decay are discussed. It is shown that CP test is possible by measuring the angular distribution in a W boson non-suppressed two-body decay mode without the polarization measurement of the final state fermions. We found that LEP200 and next linear collider (NLC) have non-trivial sensitivity on the right-handed coupling and CP violation. LEP200 will slightly improve the present limit on the right-handed coupling in the [Formula: see text] coupling, and have sensitivity on the relative magnitude of the CP violation to the P violation up to 8×10−2. NLC will improve the former by some factor or even an order of magnitude, and have sensitivity on the latter up to 10−3–10−2.
e+e− MODES AND U(1) SPONTANEOUS CHIRAL SYMMETRY BREAKING: A CASE STUDY
Authors: STEININGER KLAUS
Published: November 2004

Motivated by evidence for a chiral phase transition in strong coupling lattice QED we calculate the two-particle spectrum of the broken QED phase. This is done in the framework of a Nambu and Jona-Lasinio model with U(1) symmetry including chiral symmetry and symmetry breaking properties of QED. The second order chiral phase transition behavior in our model and in lattice QED are in excellent agreement. We then present a detailed analysis of the spectra of the e+e− modes in the broken phase. We examine whether these modes have any possible relationship to the narrow e+e− resonances found in soft heavy ion collisions at GSL. Our answer is negative.
$\widehat{{\rm su}}\left( 3 \right)_k $ FUSION COEFFICIENTS
Authors: BÉGIN L. , MATHIEU P. , WALTON M.A.
Published: November 2004

A closed and explicit formula for all [Formula: see text] fusion coefficients is presented which, in the limit k→∞, turns into a simple and compact expression for the su(3) tensor product coefficients. The derivation is based on a new diagrammatic method which gives directly both tensor product and fusion coefficients.
COLLECTIVE-FIELD APPROACH TO ANYONIC SYSTEMS
Authors: ANDRIĆ I. , BARDEK V.
Published: November 2004

We consider a large-N anyonic system in the Hamiltonian, collective-field approach. We derive a collective-field representation of the Hamiltonian. In some interesting cases we determine the ground-state energy and the corresponding anyon collective motions.
ON REPRESENTATION OF QUANTUM ACTION FUNCTIONAL
Authors: GOLFAND YU. A.
Published: November 2004

A representation for QA functional is constructed. The representation can be formulated in terms of compact (one-particle—irreducible) Feynman diagrams with special correspondence rules. The main properties are: (1) the representation of the exact vertex requires only a finite number of diagrams, (2) manifest symmetry with respect to permutations of particles. That enables one to develop consistent calculational methods. The resulting set of equations for the exact Green functions and vertices can open a way to approximate nonperturbative solutions.
CHIRAL SYMMETRY AND OPERATOR MIXING IN LATTICE SU(N) THIRRING MODEL WITH SHIFT SYMMETRY
Authors: KIKUKAWA YOSHIO
Published: November 2004

We formulate lattice SU (N) Thirring model in which two Wilson fermions describe the respective left- and right-handed components of the Dirac fermion in the continuum model. Only chirally projected half components of the Wilson fermions have four-fermion interaction. As to their non-interacting components, there exist shift symmetries discussed by Golterman and Petcher. Axial U (1) Ward-Takahashi identity is examined by weak coupling expansion. It is shown in all orders of the weak coupling expansion that the chiral limit is achieved by simply setting fermion bare mass equal to zero, and that a lattice operator has no mixing due to the Wilson masses with the operators of wrong chiral representation and of lower dimensionality.
CLASSICAL AND QUANTUM MECHANICS OF A SPINNING PARTICLE INTERACTING WITH ANTI-SYMMETRIC NON-ABELIAN TENSOR FIELDS
Authors: RIETDIJK R. H.
Published: November 2004

We study the spinning particle interacting in a supersymmetric and gauge invariant way with anti-symmetric non-Abelian tensor fields. A quantum theory is presented. We calculate the Witten index for the corresponding Dirac operator and conclude that the anti-symmetric non-Abelian tensor fields do not give any contribution to it.
CHIRAL SOLITONS VERSUS SOFT PION THEOREMS IN LARGE Nc QCD
Authors: YAMAGISHI HIDENAGA , ZAHED ISMAIL
Published: November 2004

It is shown that large-N c (number of colors) QCD does not obey conventional soft pion theorems, if the nucleon is a soliton.
RACE DECAYS AND HEAVY NEUTRINO MIXING
Authors: ACKER ANDY , PAKVASA SANDIP
Published: November 2004

From the experimental upper bound on the decay μ→eγ the mixing of a heavy neutral lepton (m>45 GeV ) with νe and νμ can be constrained to be [Formula: see text]. In turn this implies a contribution to KL→μe of no more than 2×10-15 in the branching ratio.
DOES THE EXISTENCE OF ANTIPARTICLES FORBID VIOLATIONS OF STATISTICS?
Authors: GOVORKOV A. B.
Published: November 2004

We consider a field theory based on the bilinear q-mutator relations and continuously transforming into the usual theory. For the free fields we show that the violations of usual (Fermi- or Bose-) statistics even within this "slightly" nonlocal theory are incompatible with the existence of antiparticles and the positive definiteness of norms of the state vectors in the Fock representation.
NEW UNDERSTANDING OF THE DIFFRACTIVE SCATTERING OF HADRONS AT HIGH ENERGIES: THE BLACKENING AND INCREASING EFFECTIVE INTERACTION AREA OF THE PROTON
Authors: BARSHAY SAUL , HEILIGER PATRICK , REIN DIETER
Published: November 2004

A new structure for the high-energy diffractive scattering amplitude is derived in two complementary ways (one of them recently revealed as due to Richard Feynman). Total cross-sections increase, due to a blackening of the interaction and also due to an effect which leads to an increase in the effective interaction area at fixed opacity. These features are dynamically related to the dominant high-energy process of multiparticle production.
PROJECTORS, MATRIX MODELS AND NONCOMMUTATIVE INSTANTONS
Authors: VALTANCOLI P.
Published: November 2004

We deconstruct the finite projective modules for the fuzzy four-sphere, described in a previous paper, and correlate them with the matrix model approach, making manifest the physical implications of noncommutative topology. We briefly discuss also the U (2) case, being a smooth deformation of the celebrated BPST SU (2) classical instantons on a sphere.
INTEGRABILITY IN QCD AND BEYOND
Authors: BELITSKY A. V. , BRAUN V. M. , GORSKY A. S. , KORCHEMSKY G. P.
Published: November 2004

Yang–Mills theories in four space–time dimensions possess a hidden symmetry which does not exhibit itself as a symmetry of classical Lagrangians but is only revealed on the quantum level. It turns out that the effective Yang–Mills dynamics in several important limits is described by completely integrable systems that prove to be related to the celebrated Heisenberg spin chain and its generalizations. In this review we explain the general phenomenon of complete integrability and its realization in several different situations. As a prime example, we consider in some detail the scale dependence of composite (Wilson) operators in QCD and super-Yang–Mills (SYM) theories. High-energy (Regge) behavior of scattering amplitudes in QCD is also discussed and provides one with another realization of the same phenomenon that differs, however, from the first example in essential details. As the third example, we address the low-energy effective action in a [Formula: see text] SYM theory which, contrary to the previous two cases, corresponds to a classical integrable model. Finally, we include a short overview of recent attempts to use gauge/string duality in order to relate integrability of Yang–Mills dynamics with the hidden symmetry of a string theory on a curved background.
HADRON PRODUCTION IN THE RESTRICTED RAPIDITY INTERVALS IN PROTON-NUCLEUS INTERACTIONS AT HIGH ENERGIES
Authors: AGGARWAL MADAN M.
Published: November 2004

Data on 200 and 400 GeV proton interactions with nuclear emulsion have been analyzed. It is found that the multiplicity distributions of the shower particles in the restricted rapidity intervals are well described by the negative binomial distribution (NBD). The dependences of the NBD parameters on rapidity interval, energy and target size have been studied. The results have also been discussed in terms of Giovannini and Van Hove’s clan model of multiparticle production.
MONTE CARLO SIMULATIONS ON AND OF TWO-DIMENSIONAL DYNAMICAL LATTICES: A THEORETICAL OVERVIEW
Authors: ALBERTY J.M.
Published: November 2004

A short review is presented of different projects for regularization of two-dimensional surfaces with lattices. The problems with the emergence of acceptable continuum limits are briefly referred to; the emphasis is on the attempts to saturate the functional measure in the integral over the intrinsic metrics.
POSSIBLE IMPLICATIONS OF INTEGRABLE SYSTEMS FOR STRING THEORY
Authors: GERASIMOV A. , LEBEDEV D. , MOROZOV A.
Published: November 2004

A kind of program for the unification of conformal and two-dimensional integrable models is described. Integrable systems, defined by the condition of vanishing curvature (Lax representation), can be derived from universal generalizations of Wess-Zumino-Witten action, including one more integration (over spectral parameter λ). Such actions, in their turn, should be derivable from some membrane-like action, related to the Kirillov-Kostant form for some quantum two-loop Lie algebras (like complexification of Fairlie’s deformed algebra of two-dimensional area-preserving reparametrizations).
SL(2)k WZNW MODELS, PERTURBATIONS AND INTEGRABLE MODELS
Authors: BONORA L. , ZHANG Y.-Z. , MARTELLINI M.
Published: November 2004

Perturbations of the SL(2)kC WZNW model by relevant operators are studied. Nontrivial off-critical conservation laws in these perturbed systems are constructed. For the rational level k, one of the perturbations is shown to be an analogue of the (1, 2j+1) operator in the WZNW model. Linear systems (Lax pairs) are defined whose zero curvature conditions give rise to the classical versions of the perturbed equations of motion. The classical r-matrix for these linear systems is found.
EXTENDED INFLATION— A QUANTUM-COSMOLOGICAL SURVEY
Authors: SANYAL ABHIK KUMAR , MODAK BIJAN
Published: November 2004

This paper considers the Einstein-Brans-Dicke action coupled with a Higgs sector. It is shown that a graceful exit from inflation is not possible, rejecting the claim of La and Steinhardt. Further, wormhole solutions with and without conserved charges are explored. Finally, the wave function of the universe in this model is constructed with the boundary condition, as proposed by Vilenkin. The interesting feature of the wave function is that it has been constructed for an arbitrary factor-ordering index.
BOSONIZED OPERATOR FORMALISM FOR FERMIONS WITH ODD SPIN STRUCTURES AND ANOMALY CALCULATION
Authors: KONNO HITOSHI
Published: November 2004

Bosonization of fermions with odd spin structures on an arbitrary genus Riemann surface is investigated by means of a covariant operator formalism based on the sewing techniques. A corollary of the Fay’s addition theorem is used to show the consistency of the formalism. The application to the hexagon gauge anomaly calculation in superstring theory is demonstrated. The surface term ambiguity associated with the insertion of picture-changing operator is analyzed in the operator formalism. The insertion point, which implies anomaly freedom, is identified as a repulsive fixed point in the Schottky parametrization.
ON THE MEAN FIELD ANSATZ IN ANYON THEORIES
Authors: BOYANOVSKY DANIEL
Published: November 2004

We study the physics of the mean field ansatz in a simplified anyon model. The model is solved exactly in a finite geometry with particular attention to boundary conditions compatible with a mean statistical magnetic field. The spectrum consists of bosonic plasma-like density fluctuations with a gap. We find that the repulsive Coulomb interactions introduced by the fluctuations around the mean field force the statistical charge and magnetic field to become localized near the boundaries. Translational invariance, broken by the mean field, is restored in the infinite volume limit as the statistical charge and magnetic field escape to infinity. The polarization effects of an external magnetic field and the role of “large” gauge transformations are also studied.
STATISTICS ON NETWORKS
Authors: BALACHANDRAN A.P. , ERCOLESSI E.
Published: November 2004

One-dimensional networks are excellent examples of topological spaces which are not manifolds and which admit interesting quantum physics. They are of importance in the free electron model for molecules and crystals. They also occur as fabricated mesoscopic networks. We review single-particle quantum physics on networks from topological and operator theoretic points of view and then initiate study of identical particles on networks. It is established that the available statistics on networks in its range and complexity rival the richness of statistical options in two dimensions. We treat two-particle statistics on simple networks with detail, taking care to cover operator theoretic issues pertaining to multiple connectivity and also those due to basic topological differences between a generic network and a manifold.
POSSIBLE EFFECTS OF ADDITIONAL VECTOR BOSONS IN $e^+ e^- \to f\bar{f}$ AT THE TRISTAN ENERGIES
Authors: LIKHODED A.A. , PANKOV A.A. , YUSHCHENKO O.P.
Published: November 2004

The phenomenological manifestation of the additional Y(YL) boson arising in models with the composite structure of electroweak interactions is studied for the process [Formula: see text] at the TRISTAN energies [Formula: see text]. It is shown that the experimentally observed deviation of Rμ from the Standard Model predictions can be explained by the presence of the additional isoscalar Y boson in the region of a small mixing paramenter. The increase of statistics for the above processes at TRISTAN will permit one to set an additional limit on the model parameters.
CONSTRAINTS ON THE MAJORON DECAY MODES OF A 17 keVντ AND ITS IMPLICATIONS
Authors: MOHAPATRA R.N. , NUSSINOV S.
Published: November 2004

Supernova 1987A constraints on the decay mode [Formula: see text] (χ ≡ Majoron) is discussed for the case where the ντ mass is assumed to be 17 keV. Its implications for theoretical models of a 17 keV ντ are considered.
INTRODUCTION TO QUANTIZED LIE GROUPS AND ALGEBRAS
Authors: TJIN T.
Published: November 2004

We give a self-contained introduction to the theory of quantum groups according to Drinfeld, highlighting the formal aspects as well as the applications to the Yang-Baxter equation and representation theory. Introductions to Hopf algebras, Poisson structures and deformation quantization are also provided. After defining Poisson Lie groups we study their relation to Lie bialgebras and the classical Yang-Baxter equation. Then we explain in detail the concept of quantization for them. As an example the quantization of sl2 is explicitly carried out. Next we show how quantum groups are related to the Yang-Baxter equation and how they can be used to solve it. Using the quantum double construction we explicitly construct the universal R matrix for the quantum sl2 algebra. In the last section we deduce all finite-dimensional irreducible representations for q a root of unity. We also give their tensor product decomposition (fusion rules), which is relevant to conformal field theory.
A REVIEW OF THE EXPERIMENTAL TESTS OF QUANTUM MECHANICS
Authors: LAMOREAUX STEVE K.
Published: November 2004

A review of the experimental tests of quantum mechanics is presented. Tests of the wave-particle duality of matter for atoms, electrons, and neutrons are discussed. Also covered are applications of neutron interferometry to a variety of quantum mechanics tests. Tests of the topological nature of quantum mechanics (Aharonov-Bohm effect, Aharonov-Casher effect, Berry’s phase, Aharonov-Anandan phase) are reviewed. Other topics reviewed include the experimental tests of the Bell inequality, nonlinear additions to the Schrödinger equation, the Pauli exclusion principle, the Zeno effect, and the uniqueness of ħ.
THE SPIN-STATISTICS CONNECTION FROM HOMOLOGY GROUPS OF CONFIGURATION SPACE AND AN ANYON WESS-ZUMINO TERM
Authors: BALACHANDRAN A.P. , SORKIN R.D. , MCGLINN W.D. , O’RAIFEARTAIGH L. , SEN S.
Published: November 2004

The first and second homology groups Hi for configuration spaces of framed two-dimensional particles and antiparticles, with annihilation included, are computed when up to two particles and an antiparticle are present. The set of “frames” considered are S2, SO(2) and SO(3). It is found that the H1 groups are those of the “frames” and are generated by a cycle corresponding to a 2π frame rotation. This same cycle is homologous to the exchange path—the spin-statistics theorem. Furthermore for the frame space SO(2), H2 contains a Z subgroup which implies the existence of a nontrivial Wess-Zumino term. A rotationally and translationally invariant, topologically nontrivial Wess-Zumino term for a pair of anyons and an antianyon is exhibited for this case.
ON THE SYMPLECTIC STRUCTURE OF HARMONIC SUPERSPACE
Authors: KACHKACHI M. , SAIDI E.H.
Published: November 2004

The symplectic properties of harmonic superspace are studied. It is shown that Diff (S2) is isomorphic to Diff 0(S3)/ Ab(Diff 0(S3)), where Diff 0(S3) is the group of the diffeomorphisms of S3 preserving the Cartan charge operator D0 and Ab (Diff0(S3)) is its Abelian subgroup generated by the Cartan vectors L0=w0D0. We show also that the eigenvalue equation D0λ(z)=0 defines a symplectic structure in harmonic superspace, and we calculate the corresponding algebra. The general symplectic invariant coupling of the Maxwell prepotential is constructed in both flat and curved harmonic superspace. Other features are discussed.
UNSTABLE VORTICES IN THE 2D WZNW MODEL
Authors: YUNG A.V.
Published: November 2004

Unstable-vortex solutions to equations of motion are studied in the WZNW model. The valley method is used to integrate over negative modes of the vortex. The result is that vortices produce the Kosterlitz-Thouless phase transition. At large values of the level k the theory is conformal, whereas at small k it is driven away from criticality. The corresponding effective Lagrangian is obtained.
TOPOLOGICAL INTERPRETATION OF ELECTRIC CHARGE, DUALITY AND CONFINEMENT IN 2+1 DIMENSIONS
Authors: KOVNER A. , ROSENSTEIN B.
Published: November 2004

Electric charge in QED is topological in the sense that the electric current is a curl of a local gauge-invariant field — the dual electromagnetic field strength. In 2+1 dimensions it can be explicitly represented as the winding number in terms of a local field V describing the Nielsen-Olesen magnetic vortices: [Formula: see text]. Electrically charged particles are then visualized as topological solitons of V corresponding to elements of the homotopy group π1(S1)=Z. The quantization of electric charge and the universality of the electromagnetic coupling are thus given a topological interpretation.

The low energy physics is described by a “dual” Lagrangian written in terms of the field V only. This dual Lagrangian furnishes the Landau-Ginzburg description of the Coulomb-Higgs phase transition with V as a pertinent local order parameter. The symmetry which is associated with the phase transition is the magnetic flux symmetry. The nonzero VEV of V in the Coulomb phase breaks the magnetic flux spontaneously, leading to the appearance of a massless Goldstone boson—the photon.

The vortex field V is also constructed in non-Abelian gauge theories. Here the solitons of V are identified with the “constituent” quarks. The dual Lagrangian contains explicit flux-symmetry-breaking terms. As a result the topological solitons (quarks) are linearly confined. We describe in detail the derivation of the dual Lagrangian and the topological mechanism of confinement in non-Abelian theories with adjoint and fundamental matter.

The extension of the above description to the (3+1)-dimensional gauge theories is briefly discussed. Several notions are easily generalizable but the picture is far from being complete.
PHENOMENOLOGICAL DISCUSSION OF THE THREE-GENERATION GEPNER MODEL
Authors: SCHEICH CHRISTOPH M.A. , SCHMIDT MICHAEL G.
Published: November 2004

We discuss in detail if the three-generation Gepner model in string theory and some variants can lead to a low energy theory with phenomenological attractive features. Starting from an SU(3)3 gauge theory obtained at the compactification scale by Wilson line breaking from the E6, extensive use of (numerical) renormalization group methods allows for a detailed search for further symmetry breakings and the final low energy massless particle content. In most cases the 273 Yukawa couplings are kept as from the Gepner construction, but we allow for a variation of the other couplings related to radial variations of the corresponding Calabi-Yau manifold of Schimmrigk. The parametrization of soft supersymmetry breaking also induces some freedom. Nevertheless we have not found a parametrization of one of the model variants which simultaneously evades proton decay, has only the standard spectrum of light particles, a reasonable Weinberg angle and a heavy top.
HAMILTONIAN REDUCTION OF SUPER OSP(1,2) AND SL(2,1) KAC-MOODY ALGEBRAS
Authors: KIMURA KAZUHIRO
Published: November 2004

We present the Wakimoto construction of the super OSP(1,2) and SL(2,1) Kac-Moody algebras and the free field representation of the corresponding WZW models. After imposing suitable constraints, we can lead the Feigin-Fuchs representation of Virasoro algebras and coadjoint actions of the N=1 and N=2 conformal symmetries. This formulation corresponds to a supercovariant extension of the Drinfeld and Sokolov Hamiltonian reduction.
4-D SELF-DUAL INSTANTONS FROM 2-D SIGMA MODEL
Authors: PARK Q-HAN
Published: November 2004

4-d self-dual gravity and Yang-Mills theories are identified with 2-d sigma models taking values in infinite dimensional groups. This allows us to view 4-d self-dual theories as "large N limits" of 2-d conformal field theories. We also find a possible "integrable deformation" of 4-d self-dual gravity leading to the Einstein-Maxwell system and discuss its implication in the context of higher dimensional integrability.
THE SPIN-BOSON MODEL AS A PROBLEM OF NONLINEAR STOCHASTIC PHYSICS
Authors: GRIGOLINI PAOLO
Published: November 2004

The semiclassical approximation to the spin-boson model leads to interesting nonlinear effects, triggered by the important action of the reaction field, namely the influence that the boson "bath" exerts on the spin system. This paper illustrates the quantum mechanical mamifestations of the semiclassical nonlinearity in a variety of conditions.
ELECTRON SPECTROSCOPY OF STRONGLY CORRELATED ELECTRON MATERIALS—RECENT ISSUES AND RESULTS
Authors: ALLEN J.W. , LIU L.-Z. , CLAESSEN R. , ANDERSON R.O. , PARK J.-H. , KANG J.-S. , SEAMAN C.L. , MAPLE M.B. , DALICHAOUCH Y. , de la TORRE M.L. , OLSON C.G. , ELLIS W.P. , TORIKACHVILI M.S.
Published: November 2004

An overview is given of some recent issues and results concerning the single-particle electronic structure of strongly correlated electron systems. Specific topics include (i) the α−γ transition in cerium metal, (ii) the Kondo resonance in Y 1−x U x Pd 3 and (iii) the insulator-to-metal transition in superconducting cuprates.
SINGLE-PARTICLE AND OPTICAL EXCITATIONS IN DOPED MOTT- HUBBARD INSULATORS
Authors: STEPHAN WALTER , HORSCH PETER
Published: November 2004

Recent numerical results for the single-particle spectral function and optical conductivity of the two-dimensional Hubbard and t−J models are reviewed. Already for two holes in systems of sixteen to twenty sites (≥ 10% doping) a large electronic Fermi surface, compatible with Luttinger’s theorem, is observed. The full single-particle Green’s function is examined, and is shown to exhibit quasiparticle-like behavior, with dispersion consistent with the band structure of the non-interacting limit, and band width scaling approximately as J for J smaller than t. The optical conductivity of the Hubbard and t−J models is shown to have many features in common with recent experiments on copper oxide superconductors. The importance of the often neglected 3-site terms which arise in the derivation of the t−J model from the Hubbard model for optical properties is discussed.
EFFECT OF NONEQUILIBRIUM PHONONS ON THE ELECTRON RELAXATION AND TRANSPORT
Authors: Lax M. , Cai W.
Published: November 2004

We review the recent theoretical study of the effect of nonequilibrium phonons on hot-carrier relaxation and transport. In a quantum well, the proper treatment of the electron-phonon coupling between electrons confined to two dimensions (2-D) by phonons traveling freely in three dimensions (3D) requires special care because phonon heating produces a bottleneck in the rate of transfer of energy from the carriers to the phonons. Because the carriers interact with phonons primarily when the latter are close to the quantum well, the latter should be described, not by plane waves, but by packets adapted to the shape of the carrier confinement. A quasi-equilibrium technique that retains off-diagonal elements in the phonon wave-vector permits an unrestricted treatment of the density operator equation. That in turn leads to a choice of wave packet that comes from solving the integrodifferential equations rather than by imposition. Moreover, if the carrier distribution is assumed in quasi-equilibrium with a given drift and temperature, the coupled partial differential equations are reduced to coupled ordinary differential equations that can be solved with modest computer power. Comparison with experimental results for steady flow of energy from carriers to phonons, and for time-dependent relaxation yields quantitative agreement.
QUANTUM TUNNELING OF MAGNETIZATION IN SOLIDS
Authors: STAMP P.C.E. , CHUDNOVSKY E.M. , BARBARA B.
Published: November 2004

Magnetic solids should, under certain circumstances, show macroscopic quantum behavior, in which coherence exists between completely distinct magnetization states, each involving a very large number of spins (~1012 spins). This article reviews the recent work in this field, concentrating particularly on macroscopic quantum tunneling (MQT) of magnetization.

The two main phenomena discussed are (a) the tunneling of magnetization in singledomain particles or grains (in which some 103−104 spins rotate together through an energy barrier), and (b) the tunneling of domain walls in films or in bulk magnets; where walls containing ~ 1010 spins may tunnel off a pinning potential, or from one pinning centre to another. Some attention is also given to the quantum nucleation of magnetization reversal in a bulk magnet, and to the quantum motion of other magnetic solitons (such as vortices).

After a thorough analysis of the basic grain and wall tunneling phenomena, we continue on to a discussion of the various dissipative or “decoherence” mechanisms, which destroy the phase correlations involved in tunneling. The coupling of grain magnetization to phonons, photons, and electrons is shown to have little consequence for weaklyconducting or insulating grains. Domain walls couple to these and also to magnons and impurities or defects; the 3rd order coupling to magnons can have serious effects, but if one uses pure insulators at low temperatures, these can also be ignored.

As a result, theory indicates that MQT should be visible in both grains and bulk magnets at low temperatures (at least below ~1 K). The present experimental evidence for such behavior is inconclusive, partly because few experiments have been done. We discuss these experiments, and make some suggestions for future work. It is hoped this review will stimulate such work, not only because of the fundamental interest in macroscopic quantum phenomena, but also because of the considerable scope for technological innovation.
GEOMETRIC APPROACH TO SUPERSYMMETRY
Authors: MOROZOV A. YU. , NIEMI ANTTI J. , PALO K.
Published: November 2004

We argue that a generic supersymmetric theory can be characterized entirely in terms of loop space symplectic geometry, either in a loop space parametrized by the bosonic variables or in a superloop space parametrized by half of the bosonic and fermionic variables. A Poincare supersymmetric theory is a realization of our construction in terms of space-time variables that admit a natural Lorentz-invariant interpretation. Our approach opens a new, geometric point of view to a large number of problems, including the mechanism of supersymmetry breaking and the structure of topological quantum field theories.
SINGLE-ELECTRON TUNNELING IN DOUBLE-BARRIER NANOSTRUCTURES
Authors: GOLDMAN V.J. , SU BO , CUNNINGHAM J.E.
Published: November 2004

We review experimental study of charge transport in nanometer double-barrier resonant tunneling devices. Heterostructure material is asymmetric: one barrier is substantially less transparent than the other. Resonant tunneling through size-quantized well states and single-electron charging of the well are thus largely separated in the two bias polarities. When the emitter barrier is more transparent than the collector barrier, electrons accumulate in the well; incremental electron occupation of the well is accompanied by Coulomb blockade leading to sharp steps of the tunneling current. When the emitter barrier is less transparent, the current reflects resonant tunneling of just one electron at a time through size-quantized well states; the current peaks and/or steps (depending on experimental parameters) appear in current-voltage characteristics. Magnetic field and temperature effects are also reviewed. Good agreement is achieved in comparison of many features of experimental data with simple theoretical models.
Quantum size effect in sodium: NMR and ESR in small Na particles in zeolite y
Authors: Trescos E. , Rachdi F. , de Ménorval L.C. , Fajula F.
Published: November 2004

The Na exchanged zeolite Y has been reacted with sodium or cesium metal vapor. For low concentration of the metal vapor, hyperfine ESR signal was observed, characteristic of ionic cluster species Na 43+ in the sodalite cages of the zeolite. Exposure to higher concentration leads to a single ESR narrow line which is attributed to Na small metallic particles inside the zeolite cavities. The metallic signal linewidth shows no temperature dependence in the range 4 to 300 K, which indicates a quenching of the bulk metal relaxation mechanisms. The signal intensity obeys Curie law in the same temperature range, in agreement with theoretical models for small metal particles.

23 Na NMR spectrum of (Na-Y) highly loaded with Na shows a very broad unshifted line with respect to sodium diamagnetic compound. This line is attributed to Na even metallic particles with a large size distribution. In the case of (Na-Y) highly loaded with Cs, the room temperature 23Na NMR spectrum shows two highly shifted narrow lines and a broad unshifted line. The latter should have the same origin as in the concentrated (Na-Y) with Na. The shifted lines are assigned to the Knight shifts in (Na/Cs) alloy particles which are formed by an exchange between the cesium and the Na cations of the zeolite framework. Such observation is being reported for the first time in the alkali-metals loaded zeolites.
UNIVERSAL PARAMETER TIGHT-BINDING MOLECULAR DYNAMICS FOR CLUSTERS AND MOLECULES
Authors: Menon Madhu , Subbaswamy K.R.
Published: November 2004

A non-orthogonal basis tight-binding molecular dynamics method, based on Harrison’s universal parameter scheme is described. The method can handle interactions between heteroatoms in a systematic way, and can treat interactions at arbitrary range. Results for small clusters and fullerenes are presented.
EVALUATION OF LINEAR AND NONLINEAR MICROSCOPIC POLARIZABILITIES OF C60
Authors: Westin Erik , Rosén Arne
Published: November 2004

The electronic structure of C 60 and some of its doped compounds have earlier been investigated at the level of the local density approximation, LDA, using a numerical LCAO approach. In this study, single particle wavefunctions determined from ground state LDA calculations are used for evaluation of dipole matrix elements which combined with a sum over state approach yield linear and nonlinear microscopic polarizabilities γ(1) and γ(3), respectively. Lorentz local field factors, as well as a simple RPA type correction are introduced to facilitate comparison with the dielectric function ε(ω) determined from films of C 60. γ(2) for a centrosymmetric molecule such as C 60 is zero and the lowest non-zero contribution to the polarizability is γ(3). Reasonable agreement is found with results from linear optical response experiments i.e. ellipsometric and EELS measurements on C 60 in solid or solution form. SHG, THG and DFWM experiments yield values close to the unscreened result, while invoking a RPA screening results in a non-resonant value about 2 orders of magnitude lower than most experiments.
FERROMAGNETIC TDAE-C60 VERSUS PARAMAGNETIC TDAE-C70: FARADEY BALANCE AND ESR STUDY
Authors: Tanaka Kazuyoshi , Zakhidov Anvar A. , Yoshizawa Kazunari , Okahara Kenji , Yamabe Tokio , Yakushi Kyuya , Kikuchi Koichi , Suzuki Shinzo , Ikemoto Isao , Achiba Yohji
Published: November 2004

Magnetic properties of C 60 and C 70 complexes with tetrakis(dimethylamino)ethylene (TDAE) have been studied based on the measurements of the Faraday-balance magnetization and the electron spin resonance (ESR). It has been found that both TDAE- C 60 and TDAE- C 70 possess about one radical spin per fullerene molecule. TDAE- C 60 has been confirmed to show ferromagnetic-type transition at Tc=16.7–17.5 K . Appearance of a new broad and intense ESR signal below Tc of TDAE- C 60 suggests that the radical spins in the magnetically ordered state rather localize on each C 60 molecule and are ferromagnetically correlated. On the other hand, TDAE- C 70 does not show ferromagnetism in all the temperature range down to 4.5K.
PERTURBATION THEORY FOR THE BLOCH ELECTRONS ON STRONGLY COUPLED CHAINS IN BOTH UNIFORM ELECTRIC AND MAGNETIC FIELDS
Authors: ZHAO XIAN-GENG , CHEN SHI-GANG
Published: November 2004

The energy spectrum and the wave functions for a tight-binding Bloch electron on coupled chains under the action of both uniform electric and magnetic fields are studied in detail. Exact results are obtained for the case when the coupling between chains is large by using the perturbation theory, from which it is found that the spectrum is that of two interspaced Stark ladders. The magnetic field dependence of the energy spectrum is also discussed.
THERMOELASTIC BEHAVIOUR OF FLUORITE SOLIDS USING THREE-BODY FORCE SHELL MODEL
Authors: BEDI S. S. , SINGH MAJOR , SINGH JASPAL
Published: November 2004

The expressions for the second and third order elastic constants of fluorite lattice are derived using Lundqvist three-body potential incorporating thermal phonon pressure and inter-sublattice displacement through the shell model. Theoretically calculated values of the third order elastic constants are compared with the theoretical results of other workers and experiments. First order pressure derivatives of the second order elastic constants calculated using Thurston and Brugger relations for Ca 1-x Sr x F 2 and Sr 1-x Ba x F 2 are found to be in agreement with the experiment.
MICROWAVE ABSORPTION STUDIES ON HIGH-Tc SUPERCONDUCTORS AND RELATED MATERIALS VI—NON-RESONANT MICROWAVE ABSORPTION IN ULTRA-THIN Bi-Sr-Ca-Cu-O FILMS—
Authors: SUGAWARA K. , SUGIMOTO T. , BAAR D.J. , SHIOHARA Y. , TANAKA S.
Published: November 2004

Non-resonant microwave absorption (NRMA) studies have been done for Bi-Sr-Ca-Cu-O (BSCCO) films with thicknesses of 30 Å and 15 Å fabricated on MgO substrate by MOCVD. For the latter two kinds of samples have been fabricated: BSCCO/MgO and BiOx/BSCCO/MgO . NRMA signals have been detected up to about 70–75 K for all the samples. The lower critical magnetic field H c1 * of the 30 Å film was severely increased by the application of a magnetic field of several kGauss, whereas it is almost unaffected in the case of 15 Å films. H c1 * increases but the signal intensity decreases with increasing temperature for all the 30 Å and 15 Å samples. The temperature dependence of the intensity is quite different from that of thicker films (100 Å and 350 Å), in which the intensity vs. temperature relation has a peak (or peaks) at particular temperature(s).