bluuebunny/crossref_metadata_2025 huggingface dataset:
HETEROPOLYMER FOLDING ON A APE-100 SUPERCOMPUTER
Authors: IORI GIULIA , MARINARI ENZO , PARISI GIORGIO
Published: November 2004

We discuss a model of protein folding, the IMP model of a random heteropolymer. We discuss the thermodynamic behavior of a linear heteropolymer in which the interaction between different monomers contains a quenched random component. We show the existence, along with the usual coil and globule phases, of a new folded phase, characterized by long relaxation times and by the existence of few stable states. We discuss further relevant features of the model. We describe massively parallel simulations of this model on the APE-100 supercomputer.
LARGE SORTING AND ROUTING PROBLEMS ON THE HYPERCUBE AND RELATED NETWORKS
Authors: MANZINI GIOVANNI
Published: November 2004

In this paper we present upper and lower bounds for the problems of sorting and routing n items using p processors on the hypercube, the shuffle, the butterfly and the Cube-Connected-Cycles. We consider problems where n is large; more precisely we assume that n = Ω (p2). The main results of this paper are an algorithm for routing n packets in O((n/p) log p) time, and an algorithm for sorting n integers in the range 0, 1, …, R – 1 in [Formula: see text] time.
MAINTAINING DIGITAL CLOCKS IN STEP
Authors: ARORA ANISH , DOLEV SHLOMI , GOUDA MOHAMED
Published: November 2004

A system of simultaneously triggered clocks is designed to be stabilizing: if the clock values ever differ, the system is guaranteed to converge to a state where all clock values are identical, and are subsequently maintained to be identical. For an N-clock system, the design uses N registers of 2 log N bits each and guarantees convergence to identical values within N2 "triggers".
OPTIMAL TREE RANKING IS IN $\mathcal{NC}$
Authors: DE LA TORRE PILAR , GREENLAW RAYMOND , PRZYTYCKA TERESA M.
Published: November 2004

This paper places the optimal tree ranking problem in [Formula: see text]. A ranking is a labeling of the nodes with natural numbers such that if nodes u and v have the same label then there exists another node with a greater label on the path between them. An optimal ranking is a ranking in which the largest label assigned to any node is as small as possible among all rankings. An O(n) sequential algorithm is known. Researchers have speculated that this problem is P-complete. We show that for an n-node tree, one can compute an optimal ranking in O( log n) time using n2/ log n CREW PRAM processors. In fact, our ranking is super critical in that the label assigned to each node is absolutely as small as possible. We achieve these results by showing that a more general problem, which we call the super critical numbering problem, is in [Formula: see text]. No [Formula: see text] algorithm for the super critical tree ranking problem, approximate or otherwise, was previously known; the only known [Formula: see text] algorithm for optimal tree ranking was an approximate one.
RECONFIGURABLE PARALLEL COMPUTER ARCHITECTURE BASED ON WAVELENGTH-DIVISION MULTIPLEXED OPTICAL INTERCONNECTION NETWORK
Authors: ALY KHALED A. , DOWD PATRICK W.
Published: November 2004

Reconfigurability is a desirable characteristic in parallel computer architecture that supports the structural parallelism inherent to multiple parallel algorithms. This paper presents a novel approach to achieve reconfigurability via a multiple-domain wavelength-division multiplexed optical interconnection network. A network structure is defined to host a set of point-to-point guest interconnection topologies. Fast complete reconfiguration takes place by re-labeling node identifiers and re-tuning receiver filters according to a local table at each node. For a network of size N, the connecting fiber complexity is O(N), the same order of the link complexities of the individual topologies. The proposed network avoids the possible edge dilation, congestion, and cumulative switching latencies associated with previously proposed approaches.
DATA PARALLEL COMPUTATION OF EUCLIDEAN DISTANCE TRANSFORMS
Authors: BOSSOMAIER TERRY , ISIDORO NATALINA , LOEFF ADRIAN
Published: November 2004

The Euclidean Distance Transform is an important, but computationally expensive, technique of computational geometry, with applications in many areas including image processing, graphics and pattern recognition. Since the data sets used are typically large, one might hope that parallel computers would be suitable for its determination. We show that existing parallel algorithms perform poorly on certain data sets and introduce new strategies. These achieve high speed on diverse data sets, but fail occasionally in pathological cases. We determine the maximum error in such cases and demonstrate that it is satisfactorily low. Although adequate efficiency is achievable on SIMD machines, we demonstrate that problems of this kind are data parallel yet best suited to MIMD architectures.
TWO SELECTION ALGORITHMS ON A MESH-CONNECTED COMPUTER
Authors: CHLEBUS BOGDAN S.
Published: November 2004

Two deterministic selection algorithms on an n × n mesh-connected processor array are developed. The model of computation is restricted in the following sense: at every step each processor buffers exactly one of the original keys, and every one of the original keys is buffered by a processor. The first algorithm operates in time 2.5n + o(n). It is a general selection algorithm, that is, its complexity bound does not depend on the rank of the element searched for. The second algorithm has its time bound depending on the rank of the item sought. This bound is [Formula: see text], where the rank is x2n2. This algorithm is superior to the previous one for approximately 10% of the smallest and 10% of the largest keys.
SIMULATION OF GENETIC ALGORITHMS ON MIMD MULTICOMPUTERS
Authors: DE FALCO I. , DEL BALIO R. , TARANTINO E. , VACCARO R.
Published: November 2004

In this paper, a Parallel Genetic Algorithm has been developed and mapped onto a coarse grain MIMD multicomputer whose processors have been configured in a fully connected chordal ring topology. In this way, parallel diffusion processes of good local information among processors have been carried out. The Parallel Genetic Algorithm has been applied, specifically, to the Travelling Salesman Problem. Many experiments have been performed with different combinations of genetic operators; the test results suggest that PMX crossover can be avoided by using only the inversion genetic operator and that a diffusion process leads to improved search in Parallel Genetic Algorithms.
NC-ALGORITHMS FOR OPERATIONS ON BINARY DECISION DIAGRAMS
Authors: SIELING DETLEF , WEGENER INGO
Published: November 2004

(Ordered) binary decision diagrams are a powerful representation for Boolean functions and are widely used in logical synthesis, verification, test pattern generation or as part of CAD tools. NC-algorithms are presented for the most important operations on this representation, e.g. evaluation for a given input, minimization, satisfiability, redundancy test, replacement of variables by constants or functions, equivalence test and synthesis. The algorithms have logarithmic run time on CRCW COMMON PRAMs with a polynomial number of processors.
AN OPTIMAL ALGORITHM FOR COMPUTING CENSUS FUNCTIONS IN MESSAGE-PASSING SYSTEMS
Authors: BAR-NOY AMOTZ , KIPNIS SHLOMO , SCHIEBER BARUCH
Published: November 2004

We consider a message-passing system of n processors, each of which initially holds one piece of data. The goal is to compute an associative and commutative census function f on the n distributed pieces of data and to make the result known to all processors. To perform the computation, processors communicate with each other by sending and receiving messages in specified communication rounds. We describe an optimal algorithm for this problem that requires the least number of communication rounds and that minimizes the time spent by any processor in sending and receiving messages.
SCHEDULING A SCATTERING-GATHERING SEQUENCE ON HYPERCUBES
Authors: HENRI-PIERRE CHARLES , PIERRE FRAIGNIAUD
Published: November 2004

The scattering problem refers to the gossiping and the broadcasting problems [1, 2]. It consists in distributing a set of data from a single source such that each component is sent to a distinct address. The gathering operation is the reverse of the scattering operation. This paper studies the problem of pipelining a scattering-gathering sequence in order to overlap these operations. We first give a general solution for distributed memory parallel computers, and next we particularly study this problem on hypercubes.
A COMPARISON OF MESHES WITH STATIC BUSES AND HALF-DUPLEX WRAP-AROUNDS
Authors: KRIZANC DANNY , RAJASEKARAN SANGUTHEVAR , SHENDE SUNIL M.
Published: November 2004

We investigate the relative computational powers of a mesh with static buses and a mesh with half-duplex wrap-arounds. The latter model is like a torus, except that any wrap-around link of the architecture can only transmit data in one of the two directions at any clock tick. We show that the permutation routing problem can be solved as efficiently on a linear array augmented with a half-duplex wrap-around link, as on a linear array with an augmented broadcast bus. We also present a routing algorithm for a two-dimensional (2D) mesh with half-duplex wrap-around links whose run time is close to that of the best known algorithm for routing on a 2D mesh with broadcast buses in each dimension. In addition, we show that on an n×n 2D mesh with broadcast buses, randomized sorting of n2 elements can be accomplished in time that is only o(n) more, with high probability, than the time needed for permutation routing.
A PARALLEL ALGORITHM TO GENERATE N-ARY REFLECTED GRAY CODES IN A LINEAR ARRAY WITH RECONFIGURABLE BUS SYSTEM
Authors: THANGAVEL P. , MUTHUSWAMY V.P.
Published: November 2004

A simple parallel algorithm for generating N-ary reflected Gray codes is presented. The algorithm is derived from the pattern of N-ary reflected Gray codes. The algorithm runs on a linear processor array with a reconfigurable bus system. A reconfigurable bus system is a bus system whose configuration can be dynamically changed. Recently processor arrays with reconfigurable bus systems were used to solve many problems in constant time. There already exists experimental reconfigurable chips.
ON THE DESIGN OF DEADLOCK-FREE ADAPTIVE MULTICAST ROUTING ALGORITHMS
Authors: DUATO JOSÉ
Published: November 2004

Multicast communication refers to the delivery of the same message from one source node to an arbitrary number of destination nodes. Two multicast wormhole routing methods have been presented in [13] for multicomputers with 2D-mesh and hypercube topologies. Also, a theory for the design of deadlock-free adaptive routing algorithms for wormhole networks has been proposed in [7, 8]. This theory supplies the sufficient conditions for an adaptive routing algorithm to be deadlock-free, even when there are cyclic dependencies between channels.

This paper analyses the additional channel dependencies produced by multicast routing algorithms on wormhole networks. Then, the theory proposed in [7, 8] is extended by considering them. As an example, the multicast routing algorithms presented in [13] are extended, taking advantage of the alternative paths offered by the network.
MASSLESS FERMIONS IN KALUZA-KLEIN MODELS: SU(N) GAUGE FIELDS, ZN SYMMETRY AND STABILITY OF THE METASTABLE VACUUM
Authors: BELYAEV V.M. , KOGAN IAN I.
Published: November 2004

Kaluza-Klein model on M4×S1 with SU (N) gauge fields and Nf fermions in fundamental representation is considered. It is noted that on one-loop level the lowest state of this theory corresponds to effective four-dimensional theory which has no massless fermions. This statement does not depend on fermion boundary conditions. The state with mass-less four-dimensional fermions is metastable. It is shown that this metastable states can be stabilized by effects of classical gravitation. The same problem of metastability of states with zero fermionic modes can appear in more realistic superstring compactification models and these effects of classical gravitation can resolve this problem of metastability.
SYMMETRIES IN THE FIRST-ORDER FORMULATION FOR STRINGS
Authors: AMORIM R. , BARCELOS-NETO J. , CHAGAS-FILHO W.F.
Published: November 2004

We study the symmetries, including the off-shell κ-symmetry, for strings in the first order formulation. We consider the cases with and without tension.
NUCLEOSYNTHESIS BOUNDS ON JORDAN-BRANS-DICKE THEORIES OF GRAVITY
Authors: CASAS J.A. , GARCÍA-BELLIDO J. , QUIRÓS M.
Published: November 2004

We reexamine the nucleosynthesis predictions for the simplest class of scalar-tensor theories of gravity, the Jordan-Brans-Dicke theory. Comparison with present observational data on light elements’ abundances provides bounds on the ω-parameter which are as strong as the post-Newtonian ones, or even stronger, depending on the value of Ωh2. Future improvements in the determination of the 4 He and D +3He abundances will increase this bound dramatically. We argue that a future (hypothetical) experimental deviation from general relativity prediction could be restored by a Jordan-Brans-Dicke theory.
INITIAL STATE SCATTERING AND pT SPECTRA OF MUON PAIRS IN HADRON-NUCLEUS AND NUCLEUS-NUCLEUS COLLISIONS AT HIGH ENERGIES
Authors: SALEEV V.A. , ZOTOV N.P.
Published: November 2004

The muon pair production processes in hadron-nucleus and nucleus-nucleus collisions at high energies are considered using the additive quark model and the perturbation QCD. The transverse momentum dependence of the muon pairs in hadron-nucleus collisions is described. The pT-dependence of the muon pair distributions and their ratio at different values of the total transverse energy ET in heavy nucleus collisions is predicted. A good description of the ET-dependence of [Formula: see text] is provided.
NUCLEON PROPERTIES IN CHIRAL COLOR DIELECTRIC MODEL
Authors: SAHU SARIRA , PHATAK S.C.
Published: November 2004

The chiral extension of color dielectric model has been used to study the static properties of nucleon. In this calculation we have treated the gluon and the pion fields perturbatively. It is found that the neutron charge rms radius and the pion-nucleon coupling constant are almost insensitive to the parameters used and are in excellent agreement with the experimental values. For better fitting the proton charge rms radius, nucleon magnetic moments and axial coupling constant prefer large quark masses (~100 MeV) and small glueball masses (<1100 MeV). The strong coupling constant is found to be very sensitive to the quark and glueball masses.
CRITICAL TEMPERATURES FOR SUPERCONDUCTING QUARK MATTER EXISTENCE IN DENSE STELLAR CORES
Authors: HORVATH J.E. , BENVENUTO O.G. , VUCETICH H.
Published: November 2004

If quark matter is actually a component of compact stars it can probably develope a superconducting phase as a result of QCD interactions. This effect may be harmless for (or dramatically affect) the properties of the star, depending on the actual value of the strong coupling constant α c . Explicit expressions for the critical temperature T c are derived by using some recent results on the long-range behavior of the gluon propagators. The consequences for the cooling histories of compact stars and possible trends are briefly discussed.
MASSIVE ORBIFOLDS
Authors: CECOTTI SERGIO , VAFA CUMRUN
Published: November 2004

We study some aspects of 2D supersymmetric sigma models on orbifolds. It turns out that independently of whether the 2D QFT is conformal the operator products of twist operators are non-singular, suggesting that massive (non-conformal) orbifolds also “resolve singularities” just as in the conformal case. Moreover we recover the OPE of twist operators for conformal theories by considering the uv limit of the massive orbifold correlation functions. Alternatively, we can use the OPE of twist fields at the conformal point to derive conditions for the existence of non-singular solutions to special nonlinear differential equations (such as Painleve III).
NEW REALIZATIONS OF W ALGEBRAS AND W STRINGS
Authors: LU H. , POPE C.N. , SCHRANS S. , WANG X.J.
Published: November 2004

We discuss new realizations of W algebras in which the currents are expressed in terms of two arbitrary commuting energy-momentum tensors together with a set of free scalar fields. This contrasts with the previously-known realizations, which involve only one energy-momentum tensor. Since realizations of nonlinear algebras are not easy to come by, the fact that this new class exists is of intrinsic interest. We use these new realizations to build the corresponding W-string theories and show that they are effectively described by two independent ordinary Virasoro-like strings.
CONSTRAINED FERMIONIC MODELS IN NON-TRIVIAL TOPOLOGICAL SECTORS
Authors: MORENO ENRIQUE F.
Published: November 2004

We study a constrained fermionic model involving non-trivial topological gauge configurations. After a path-integral treatment of the topologically trivial degrees of freedom we show that the resulting effective theory is equivalent to a Coulomb gas theory with a "background charge" at infinity plus a b, c ghost system. The Virasoro central charge of the theory is found to be independent of the topological sector.
SCALING PATTERN FOR PARTICLE PRODUCTION IN HEAVY-ION COLLISIONS AT SUB-THRESHOLD BEAM ENERGY
Authors: GHOSH B.
Published: November 2004

We examine the experimentally observed scaling patterns for particle production in nuclear collisions at sub-threshold energy regime in the framework of a cooperative model. Besides π+, K+, K− and [Formula: see text] we also include protons emitted at extreme kinematical region. We show that the proton spectra also has the same universal scaling behavior as that of pions, kaons and antiprotons. This supports our earlier proposition that the reaction mechanism leading to the emission of proton in extreme kinematical region is similar to the ones which cause sub-threshold particle productions.
A GAUGE THEORY OF SPIN-1/2 FIELD
Authors: SHIMA KAZUNARI
Published: November 2004

A gauge theory of spin-1/2 Dirac field in four-dimensional space-time is presented. The gauge invariant gravitational interaction is also investigated.
CP-VIOLATING EFFECTS IN SOME TWO-BODY BARYONIC DECAYS OF $B_s^0 - \bar B_s^0 $ MESONS
Authors: LIU JIAFU , WAN LINGDE , LU GONGRU
Published: November 2004

The partial-decay-rate asymmetries indicating the CP-violating effects in [Formula: see text] decays into two-body baryons are examined within the Kobayashi-Maskawa model. The branching ratios of the decays and the numbers of [Formula: see text] pairs needed for testing these effects are estimated. It turns out that the CP violation asymmetries and the branching ratios are generally small and it is difficult to test the effects in experiments.
ON TWO-DIMENSIONAL GRAVITY
Authors: BOSE S.K.
Published: November 2004

The field equations that result from the use of R2–the square of the Ricci scalar – in the gravitational action are studied in two dimensions. Some general features of the model are noted; in particular, the existence of a solution R=Λ. The form of the static vacuum metrics is obtained. The problem of cosmology is discussed.
GROUND STATE OF N HARMONICALLY BOUND ANYONS IN A MAGNETIC FIELD
Authors: CHITRA R.
Published: November 2004

The properties of the ground state of N anyons in an external magnetic field and a harmonic oscillator potential are computed in the large-N limit using the Thomas-Fermi approximation. The number of level crossings in the ground state as a function of the harmonic frequency, the strength and the direction of the magnetic field and N are also studied.
MATRIX MODELS WITHOUT MATRICES: FROM INTEGRABLE HIERARCHIES TO RECURSION RELATIONS
Authors: SEMIKHATOV A. M.
Published: November 2004

Virasoro constraints on integrable hierarchies and their consequences are studied using the formalism of dressing operators. The dressing-operator description allows one to perform entirely in intrinsically hierarchical terms a double-scaling limit which takes "discrete" (lattice) Virasoro-constrained hierarchies into continuum hierarchies subjected to their own Virasoro constraints. Certain equations derived as consequences of the constraints suggest an interpretation as recursion/loop equations, thus establishing a link with the field-theoretic description. Such a correspondence with two-dimensional gravity-coupled theories, which does not require going through the matrix formulation, is conjectured to hold for general integrable hierarchies of the r-matrix type (appropriately constrained). The example considered explicitly is that of the Virasoro-constrained Toda hierarchy which undergoes a scaling into the Virasoro-constrained KP hierarchy, which in turn can be reduced to N-KdV hierarchies subjected to a subset of the KP Virasoro constraints. The dressing-operator formulation also facilitates the analysis of symmetry algebras of constrained hierarchies. The Kac–Moody sl (N) algebra is identified as a symmetry of the N-KdV hierarchy, while for the Virasoro-constrained KP hierarchy its symmetry algebra is related to a member of the family of the W∞(J) algebras. In the supersymmetric case this method allows one to impose super-Virasoro constraints on the super-KP hierarchy consistently with all the SKP flows.
QUATERNION SOLUTIONS OF FOUR-DIMENSIONAL LIOUVILLE AND SINE-GORDON EQUATIONS
Authors: CHUNG WON-SANG , LEE JUNG-JAI , CHO JIN-HO
Published: November 2004

The quaternion solutions of four-dimensional Liouville and sine-Gordon equations are explicity obtained by using the quaternion basis.
BOSONIC CHERN-SIMONS FIELD THEORY OF ANYON SUPERCONDUCTIVITY
Authors: WEISS NATHAN
Published: November 2004

We study the quantum field theory of non-relativistic bosons coupled to a Chern-Simons gauge field at nonzero particle density. This field theory is relevant to the study of anyon superconductors in which the anyons are described as bosons with a statistical interaction. We show that it is possible to find a mean field solution to the equations of motion for this system which has some of the features of Bose condensation. The mean field solution consists of a lattice of vortices each carrying a single quantum of statistical magnetic flux. We speculate on the effects of the quantum corrections to this mean field solution. We argue that the mean field solution is only stable under quantum corrections if the Chern-Simons coefficient N=2πθ/g2 is an integer. Consequences for anyon superconductivity are presented. A simple explanation for the Meissner effect in this system is discussed.
LOWER-DIMENSIONAL DIVERGENCES IN THE ABELIAN HIGGS MODEL
Authors: VARGAS M. , LUCIO J. L. M.
Published: November 2004

We consider the Abelian Higgs model to study a possible relation between the one- and two-loop quadratic divergences. We also comment on their gauge and renormalization scheme dependence.
QUANTUM DESCRIPTION FOR THE DECAY OF NSNS BRANE–ANTIBRANE SYSTEMS
Authors: KIM HONGSU
Published: November 2004

The stringy description for the instabilities in the RR charged [Formula: see text] pairs is now well understood in terms of the open string tachyon condensation. The quantum interpretation presumably via the stringy description for the instabilities in the NSNS-charged [Formula: see text] and [Formula: see text] pairs in IIA/IIB theories, however, has not been fully established yet. This would be partly because of the absence (for the [Formula: see text] case) or our relatively poor understanding (for the [Formula: see text] case) of their world-volume (gauge theory) dynamics. In the present work, using the well-known quantum description for instabilities in the RR-charged [Formula: see text] systems and in the M-theory brane–antibrane systems and invoking appropriate string dualities, the stringy nature of the instabilities in the NSNS-charged [Formula: see text] and [Formula: see text] systems both at strong and at weak couplings has been uncovered. For the annihilations to string vacua, the quantum, stringy interpretations are simple extensions of Sen's conjecture for those in RR-charged brane–antibrane systems.
PHYSICS AT γp COLLIDERS OF TeV ENERGIES
Authors: ALEKHIN S.I. , BOOS E.E. , BORODULIN V.I. , JIKIA G.V. , SLABOSPITSKY S.R. , SMIRNOV A. YU. , SULTANOV S.F.
Published: November 2004

Analysis of possibilities of the γp collider in the TeV energy range, realized on the basis of UNK and VLEPP projects, is performed. It is shown that such a collider substantially increases the range of physics phenomena accessible for investigations at ep colliders.
ON THE INTERACTIONS OF CHARGED PARTICLES WITH COSMIC STRING
Authors: KOGAN YA. I. , SELIVANOV K.G.
Published: November 2004

We discuss the scattering of charged particles on cosmic string. The cases of the small and large (comparing the string scale) momentum of particles are considered. Anisotropical amplitude which describes the action of the string’s “magnetic” field on the particles is obtained. Physical applications are briefly discussed.
ON THE DYNAMICS OF SPHERICALLY SYMMETRIC SYSTEMS IN QUANTUM GRAVITY
Authors: LOUSTO C.O. , MAZZITELLI F.D.
Published: November 2004

Within the formalism of quantum gravity, we consider a general metric with spherical symmetry and study under which circumstances it is possible to consistently reduce the number of degrees of freedom of the theory. In the case of separation of variables, we show that only the Kantowski-Sachs and Robertson-Walker geometries are consistent minisuperspaces. We analyze some minisuperspaces adequate for the study of the black hole physics, but we find that they are either trivial or inconsistent.
BRST QUANTIZATION OF POLYAKOV’S TWO-DIMENSIONAL GRAVITY II
Authors: ITOH KATSUMI
Published: November 2004

Two-dimensional supergravity coupled to the supersymmetric minimal models is quantized by the BRST method. We analysed the physical state condition and found that a state allowed in the physical spectrum must be a direct product of primary states in the matter and gravity sectors. The decoupling mechanism of the unphysical modes is quite similar to the first quantized string theory in the RNS formalism. The formula of KPZ for gravitational scaling dimensions is rederived from the physical state condition. This analysis is done in the conformal gauge.
N=3 AND N=4 SUPERCONFORMAL WZNW SIGMA MODELS IN SUPERSPACE I: GENERAL FORMALISM AND THE N=3 CASE
Authors: IVANOV E.A. , KRIVONOS S.O. , LEVIANT V.M.
Published: November 2004

In the present and accompanying papers we develop a manifestly invariant superfield description of N=3 and N=4 2D superconformal WZNW sigma models with U(1)×O(3) and U(1)×U(1)×O(4) as the bosonic target manifolds.

In the first paper we start by recalling the basic elements of 2D superconformal superfield calculus. As a new result, we generalize the latter to the newly discovered U(1) -extended O(4) N=4 superconformal algebra. In particular, the existence of a new class of N=4 primary superfields labelled by the eigenvalues of the U(1) generator is pointed out. Further, we construct the N=3 superspace formulation of the U(1)×O(3) model. The self-contained definition of the N=3 supercurrent via the basic primary superfields of this model is given, both in classical and quantum cases, and the relevant SOPEs are written down. It is shown that the model, being actually N=4 supersymmetric, admits one more supercurrent which extends the N=3 superconformal algebra to the N=4 one mentioned above. We define the minimal quantum N=3 superfield representations adequate for the two important cases of fermionization of the [Formula: see text] Kac-Moody current corresponding to the levels k=0 and k=2 of the bosonic part of one of its [Formula: see text] components.
GENERALIZED COULOMB GAS MODELS WITH EXPONENTIAL INTERACTIONS AND A SERIES OF CENTRAL CHARGES
Authors: CHUNG MYUNG-HOON
Published: November 2004

The renormalization of the generalized Coulomb gas model with exponential interactions is studied. This model contains a bosonic vector field and several fermionic fields in the presence of a background charge vector. It is shown that the vectors associated with the exponential interactions should satisfy certain conditions for the action to be renormalizable. The conditions require the vectors to form a geometrical figure. In particular, models are considered where the vectors are root systems which form equilateral geometrical figures. Explicit β-functions are obtained for these models. They show several nontrivial fixed points at which the central charges of the system are evaluated. It is found that a renormalization group flow connects the extremal nontrivial fixed points. Some possible applications are indicated.
ON THE ALGEBRAIC STRUCTURE of QUANTUM GRAVITY IN TWO DIMENSIONS
Authors: Gervais Jean-Loup
Published: November 2004

Current progresses in understanding quantum gravity from the operator viewpoint are reviewed. They are based on the Uq(sl(2))-quantum-group structure recently put forward1,2, for the chiral components of the metric in the conformal gauge.
INTERMITTENCY IN PARTICLE COLLISIONS
Authors: PESCHANSKI R.
Published: November 2004

Some methods and concepts which are at the origin of and are presently relevant to the study of intermittency in multiparticle reactions are reviewed in an introductory and pedagogical way.
CLASSICAL INSTABILITY OF THE EINSTEIN-GAUSS-BONNET GRAVITY THEORY WITH COMPACTIFIED HIGHER DIMENSIONS
Authors: SOKOŁOWSKI LESZEK M. , GOLDA ZDZISŁAW A. , LITTERIO MARCO , AMENDOLA LUCA
Published: November 2004

The energy spectrum and stability of the effective theory resulting from the Einstein-Gauss-Bonnet gravity theory with compactified internal space are investigated. The internal space can evolve in its volume and/or shape, giving rise to a system of scalar fields in the external space-time. The resulting scalar-tensor theory of gravity has physically unacceptable properties. First of all, the scalar fields’ energy is indefinite and unbounded from below, and thereby the gravitational and scalar fields form a self-exciting system. In contradistinction to the case of multidimensional Einstein gravity, this inherent instability of the effective theory cannot be removed by field redefinitions in the process of dimensional reduction (e.g. by a conformal rescaling of the metric in four dimensions, as is done in the former case). To get a viable effective gravity theory one should discard either the geometric scalar fields or the Gauss-Bonnet term from the Lagrangian of the multidimensional theory. It is argued that it is the Gauss-Bonnet term that should be discarded.
QUANTUM CALCULATIONS OF HARMONIC-VIBRATIONAL TRANSITION PROBABILITIES IN COLLINEAR X2Y2 + X2Z2COLLISIONS
Authors: GÖGTAŞ FAHRETTIN , KOLSUZ NURI
Published: November 2004

Quantum-mechanical calculations of harmonic-vibrational transition probabilities were reported for nonreactive collinear X2Y2 + X2Z2 collisions. Calculations are carried out for C2H2 + C2H2, C2H2 + C2D2 and C2D2 + C2D2 systems. The dependence of transition probabilities on doubly and triply degenerate states was investigated.
STRING CONTRIBUTIONS IN 3D Z2 AND Z5 GAUGE MODELS
Authors: CASELLE M. , GLIOZZI F. , VINTI S. , FIORE R. , PROVERO P.
Published: November 2004

We describe a high precision Monte Carlo test on Z2 and Z5 gauge models in 3D. Wilson loops of size 2≤R, T≤12 are measured and values of the string tension σ are extracted. These values fulfil asymptotic scaling if and only if the string contributions, namely the quantum fluctuations of the surfaces bordered by Wilson loops, are properly taken into account. As a byproduct of our analysis we find the signature of the finite thickness of these flux tubes.
THE TOP QUARK CONDENSATE IN THE PRESENCE OF HIGHER-DIMENSIONAL OPERATORS
Authors: MANNAN SAMJID H. , KING STEPHEN F.
Published: November 2004

We study a [Formula: see text] model of composite Higgs with higher-dimensional operators in the presence of QCD. QCD interactions are inserted at the level of the gap equation and we find that the corrections tend to significantly increase the strength of the higher-dimensional operators needed to produce a given mt. However, it is still possible to bring down both mt and the UV cutoff substantially.
KINKS AND BOUNCES FROM ZERO MODES
Authors: CASAHORRAN JAVIER , NAM SOONKEON
Published: November 2004

We describe a general method of obtaining nonlinear models possessing either topological or nontopological classical solutions. In particular, the program can be carried out when the so-called stability equations are derived from group-theoretical arguments. Using Schrödinger-like equations with Pöschl-Teller potential, which is related to SU(2), we obtain interesting field theories labeled by a natural number l. We also consider Rosen-Morse potential, which is related to SL (2, C), getting a new family of models. Previously known examples, such as sine-Gordon, Φ4 and Liouville theory, are obtained in this context.
KL → π0 γγ AND RELATED DECAYS
Authors: HAMBYE THOMAS
Published: November 2004

We present a phenomenological review of the decay KL → π0γγ, through the two dominant contributions of the π loop and vector meson dominance mechanisms. We have paid particular attention to consistency on the one hand between recent experimental measurements and theoretical models of KL → π0γγ decay and on the other hand between KL → π0γγ and other rather similar decays as KS → γγ, KL → γγ and η → π0γγ.
FLIPPED SU(5) × U(1) IN SUPERCONFORMAL MODELS
Authors: BAILIN D. , KATECHOU E. K. , LOVE A.
Published: November 2004

Flipped SU (5) × U (1) models are constructed in the framework of tensoring of N = 2 superconformal minimal models quotiented by discrete symmetries. Spontaneous breaking of flipped SU (5) × U (1) and extra U(1) factors in the gauge group along F-flat directions of the effective potential is studied.
SCALE-SETTING WITHOUT THE HIGGS MECHANISM: NON-ABELIAN SYMMETRY
Authors: ANDERSON J. T.
Published: November 2004

For the non-Abelian Higgs model it is shown that the coupled equations of motion for Aμ, ϕ and ϕ* have nonanalytic singularities which must be removed if the equations are integrable. Current conservation is found to remove the singularities in the vector-field equation and give a mass scale independent of V and the Higgs mechanism. The self-consistent field solutions for Aμ and the ϕ fields give either (1) the Higgs mechanism, zero current and the pure-gauge solution, or (2) nonzero current, a gauge-covariant solution and the mass scale independent of V and the Higgs mechanism.
GEOMETRIC REGULARIZATION AND GAUGE INVARIANCE IN CHERN–SIMONS THEORIES
Authors: ASOREY MANUEL , FALCETO FERNANDO
Published: November 2004

Some perturbative aspects of Chern–Simons theories are analyzed in a geometric-regularization framework. In particular, we show that the independence from the gauge condition of the regularized theory, which insures its global meaning, does impose a new constraint on the parameters of the regularization. The condition turns out to be the one that arises in pure or topologically massive Yang–Mills theories in three-dimensional space–times. One-loop calculations show the existence of nonvanishing finite renormalizations of gauge fields and coupling constant which preserve the topological meaning of Chern–Simons theory. The existence of a (finite) gauge-field renormalization at one-loop level is compensated by the renormalization of gauge transformations in such a way that the one-loop effective action remains gauge-invariant with respect to renormalized gauge transformations. The independence of both renormalizations from the space–time volume indicates the topological nature of the theory.
THE GRAPH-REPRESENTATION APPROACH TO TOPOLOGICAL FIELD THEORY IN 2 + 1 DIMENSIONS
Authors: MARTIN STEPHEN P.
Published: November 2004

An alternative definition of topological quantum field theory in 2 + 1 dimensions is discussed. The fundamental objects in this approach are not gauge fields as in the usual approach, but nonlocal observables associated with graphs. The classical theory of graphs is defined by postulating a simple diagrammatic rule for computing the Poisson bracket of any two graphs. The theory is quantized by exhibiting a quantum deformation of the classical Poisson-bracket algebra, which is realized as a commutator algebra on a Hilbert space of states. The wave functions in this "graph representation" approach are functionals on an appropriate set of graphs. This is in contrast to the usual "connection representation" approach, in which the theory is defined in terms of a gauge field and the wave functions are functionals on the space of flat spatial connections modulo gauge transformations.
THE BACKLUND TRANSFORMATION, VIRASORO ALGEBRA, AND SYMMETRIES RELATED TO THE CYLINDRICALLY SYMMETRIC SELF-DUAL YANG–MILLS EQUATION
Authors: CHOWDHURY A. ROY , SEN D. C.
Published: November 2004

We have obtained the Backlund transformation and symmetry generators for the cylindrically symmetric self-dual Yang–Mills equation through a gauge transformation ∈ SL(2, c). It is shown that there exists a subclass of transformations which generate a Virasoro algebra under commutation. It is also demonstrated how new solutions can be generated from the old ones.
STANDING WAVE GROUND STATE IN HIGH DENSITY, ZERO TEMPERATURE QCD AT LARGE NC
Authors: DERYAGIN D. V. , YU. GRIGORIEV D. , RUBAKOV V. A.
Published: November 2004

Chiral symmetry breaking in QCD at zero temperature and high fermionic density is studied in the limit NC → ∞. We evaluate the effective action in the ladder approximation and integrate out fermions by introducing the bilocal field Σ(x, y), which enters the action as the mass operator for fermions. It is argued that at large fermionic chemical potential the mass operator Σ(x, y) has a small but nonvanishing expectation value. The condensate of the field Σ(x, y) and the fermionic condensate [Formula: see text] are inhomogeneous and anisotropic, so that the ground state has the structure of the standing wave with respect to these order parameters. Unlike possible color superconductivity, this symmetry breaking occurs to the leading order in 1/NC.
INFRARED SINGULARITIES OF GLUON GREEN'S FUNCTIONS AND THE QUASIPOTENTIAL OF A TWO-QUARK INTERACTION IN QUANTUM CHROMODYNAMICS
Authors: ARKHIPOV A. A.
Published: November 2004

The influence of infrared singularities of gluon Green's functions on the character of two-quark forces in QCD is investigated.
DOES STOCHASTIC ANALYTIC REGULARIZATION PROVIDE QUANTUM FIELD THEORIES?
Authors: MARTIN C. P.
Published: November 2004

We analyze whether the so-called method of stochastic analytic regularization is suitable as an intermediate step for constructing perturbative renormalized quantum field theories. We choose a λϕ3 in six dimensions to prove that this regularization method does not in general provide a quantum field theory. This result seems to apply to any field theory with a quadratically UV-divergent stochastic two-point function, for instance λϕ4 and gauge theories in four dimensions.
ON THE WEINBERG MODEL OF CP VIOLATION
Authors: CHENG HAI-YANG
Published: November 2004

The Weinberg three-Higgs-doublet model of CP violation and its phenomenological implications are reviewed. CP violation which arises solely from charged-Higgs-boson exchange can be accommodated in the kaon system, but it is not compatible with the constraints inferred from the neutron electric dipole moment dn and from B physics. Therefore, charged-Higgs-boson exchange cannot be the dominant source of CP violation observed in KL decays. Limits on CP violation mediated by neutral-Higgs-boson exchange are derived from the dn induced by the mechanism of Barr and Zee.
ANOTHER “COSMOLOGICAL” CONSTANT
Authors: BENGTSSON INGEMAR , PELDÁN PETER
Published: November 2004

Capovilla, Jacobson and Dell have found a one-parameter family of field equations which coincides with Einstein’s equations when the parameter is set to zero. The basic variable is an SO(3) vector potential. For generic values of the parameter, we show that the solutions of the field equations may be interpreted in terms of Riemannian geometry. The space-time metric is expressible in terms of the field strengths. The connection between the SO(3) fibers and the tangent space of space-time is not that of the tetrad formalism. The metric is not Ricci flat. Coupling to a massless scalar field is given as an example of matter couplings. Spherically symmetric solutions are given. In the nonrelativistic limit there is a deviation from Newton’s inverse square law, and this is used to set an observational bound on the parameter.
BRST INVARIANCE OF A DISCRETIZED PATH INTEGRAL AND OPERATOR ORDERING OF THE WHEELER-DEWITT EQUATION IN A ONE-VARIABLE MINISUPERSPACE MODEL
Authors: SHIMIZU KATSUTARO , WADA SUMIO
Published: November 2004

We construct a discretized path integral for a one-variable minisuperspace model of gravity, which is made gauge-invariant by extending the method of Fradkin and Vilkovisky. Then we derive the Wheeler-DeWitt equation. The operator ordering of its kinetic term is fixed and turns out to be that of the Laplace-Beltrami operator.
THE ORIGIN OF GAUGE SYMMETRIES IN INTEGRABLE SYSTEMS OF THE KdV TYPE
Authors: BAKAS IOANNIS , DEPIREUX DIDIER A.
Published: November 2004

Generalized systems of integrable nonlinear differential equations of the KdV type are considered from the point of view of self-dual Yang-Mills theory in space-times with signature (2, 2). We present a systematic method for embedding the rth flows of the SL (N) KdV hierarchy with N≥2 and rN the corresponding equations can be described in a similar fashion, provided that (in general) the rank of the gauge group increases accordingly. Certain connections of this formalism with WN algebras are also discussed. Finally, we obtain a new class of nonlinear systems in two dimensions by introducing self-dual Ansätze associated with the [Formula: see text] algebras of Bershadsky and Polyakov.
EXTRINSIC GEOMETRY OF STRINGS AND THE GAUSS MAP OF SURFACES IN ℝn
Authors: PARTHASARATHY R. , VISWANATHAN K.S.
Published: November 2004

A two-dimensional Euclidean string world sheet realized as a conformal immersion in ℝn is mapped into the Grassmannian G2,n through the generalized Gauss map. In order for the Grassmannian to represent tangent planes to a given surface, n–2 integrability conditions must be satisfied by the G2,n fields. These conditions are explicitly derived for arbitrary n by realizing G2,n as a quadric in [Formula: see text]. Both the intrinsic and the extrinsic geometrical properties of the string world sheet are expressed in terms of the Kähler σ model fields.
GENERALIZED MODELS WITH EXPONENTIAL INTERACTIONS: THE TRIANGLE MODEL
Authors: CHUNG MYUNG-HOON
Published: November 2004

Generalized models are considered with exponential interactions and in the presence of a background charge vector. In order for the action to be renormalizable, the vectors involved in the exponential interactions should form a geometrical figure. Along renormalization-group flows, the shape of the figure changes, but not its topology. The β functions describing the figure distortion are obtained in general. When the corresponding geometrical figure is a triangle, the model is investigated in detail. This “triangle model” has nine running coupling parameters, among which three parameters describe the shape of the triangle. From the nine β functions of the model, the fixed points are found and their stability is determined. By using the exact results for the fixed points and their stability, the general structure of the renormalization-group flows is discussed.
A NEW METHOD OF CALCULATING MASSIVE FEYNMAN DIAGRAMS: VERTEX-TYPE FUNCTIONS
Authors: KOTIKOV A.V.
Published: November 2004

We extend the recently invented method of calculating massive Feynman integrals, namely the differential equations method, to vertex-type diagrams. As an example, for calculations of one-and two-loop diagrams we show that by analogy with propagator-type diagrams this method is a simple procedure for evaluating the result without calculating D-space integrals (for dimensional regularization).
POSITIVE ENERGY TEST OF POINCARÉ GAUGE THEORY
Authors: CHERN DE-CHING , NESTER JAMES M. , YO HWEI-JANG
Published: November 2004

The positive total energy test is applied to the Poincaré Gauge Theory of gravity. Both the asymptotically flat and asymptotically constant negative curvature case are considered. The test shows that in either case, the theory with generic values for the parameters is not viable.
THE FREEDMAN-TOWNSEND MODEL IN TWO AND THREE DIMENSIONS
Authors: MCKEON D.G.C.
Published: November 2004

Using a mechanism similar to that employed by Freedman and Townsend in four dimensions, we discuss a variety of two- and three-dimensional gauge theories. The simplest of these models is equivalent to the nonlinear sigma model; another corresponds to a massive vector theory. In three dimensions, there exists a gauge invariance associated with the auxiliary vector ϕμa; when we quantize, this is accommodated using both the Batalin-Vilkovisky configuration space formalism and the Batalin-Fradkin-Vilkovisky configuration space formalism. Explicit one-loop calculations in the simplest two-dimensional model are carried out. The regularization used is a variant of operator regularization, allowing one to remain in two dimensions, hence circumventing problems associated with definition of the antisymmetric tensor εμν. This model is renormalizable, with renormalization mixing the scalar field ϕa and the transverse component of the vector field Vμa.
QUANTUM-ELECTRODYNAMIC PROCESSES IN A RADIATION-DOMINATED ROBERTSON-WALKER UNIVERSE
Authors: BUCHBINDER I.L. , TSAREGORODTSEV L.I.
Published: November 2004

Quantum electrodynamics in an expanding Robertson-Walker universe with the line element ds2=dt2 – a2(t)(dx2+dy2+dz2) (radiation-dominated universe) is considered. The differential probability of bremsstrahlung of an electron in the external gravitational field and the differential probability of an electron-positron pair and photon creation from the vacuum are calculated by using the perturbative S-matrix formalism. The behavior of these probabilities in different kinematic regions is investigated. The total probabilities are shown to be finite. In conclusion, the total probability of a pair and photon creation from vacuum We is compared with the total probability of pair production due to an expansion of the universe W0. The comparison shows that We=1.9·10−2W0 at about the Compton time of an electron.
EQUIVALENCE OF ZN ORBIFOLDS AND LANDAU-GINZBURG MODELS
Authors: CHUN E.J. , LAUER J. , NILLES H.P.
Published: November 2004

We show that Landau-Ginzburg models with modality one are equivalent to ZN orbifold models on two-dimensional tori. The identification of the primary field content is given and the operator product coefficients of the twisted sectors are computed explicitly.
GRADED GL(1|1) BRST SYMMETRY IN COVARIANT QUANTIZATION OF SUPERSYMMETRIC CHIRAL BOSONS AND HETEROTIC STRINGS
Authors: YU FENG , WU YONG-SHI
Published: November 2004

We present a covariant path integral quantization of supersymmetric chiral bosons (leftons and rightons). An infinite set of auxiliary scalar superfields are introduced to convert the second-class chiral constraint into first-class ones. Our gauge-fixed action has an extended BRST symmetry described by the graded algebra GL(1|1). A regularization respecting this symmetry is proposed to deal with the contributions of the infinite towers of auxiliary fields and associated ghosts and is verified to lead to the desired partition function. We apply our formulation to give a covariant quantization of the heterotic-type NSR strings, and show that (super)conformal anomalies from all unphysical degrees of freedom are cancelled, even in noncritical dimensions. Our treatment does not suffer from Siegel gauge anomaly, because of the use of linear chiral constraints.