bluuebunny/crossref_metadata_2025 huggingface dataset:
PREDICTIVE CONTROL OF NONLINEAR SYSTEMS BASED ON IDENTIFICATION BY BACKPROPAGATION NETWORKS
Authors: HAO JIANBIN , VANDEWALLE JOOS , TAN SHAOHUA
Published: November 2004

Using the property of universal approximation of multilayer perceptron neural network, a class of discrete nonlinear dynamical systems are modeled by a perceptron with two hidden layers. A backpropagation algorithm is then used to train the model to identify the nonlinear systems to a desired level of accuracy. Based on the identified model, a one-step-ahead predictive control scheme is proposed in which the future control inputs are obtained through some nonlinear optimization process. Making use of the online learning properties of neural networks, the predictive control scheme is further developed into an adaptive one which is robust to the incompleteness of identification. Simulation results show that this neural control scheme works well even for some very complicated nonlinear systems.
HANDWRITTEN DIGIT RECOGNITION USING TWO-LAYER SELF-ORGANIZING MAPS
Authors: WU JING , YAN HONG , CHALMERS ANDREW
Published: November 2004

In this paper, we present a two-layer self-organizing neural network based method for handwritten digit recognition. The network consists of a base layer self-organizing map and a set of corresponding maps in the second layer. The input patterns are partitioned into subspace in the first layer. Patterns in a subspace are led to the second layer and a corresponding map is built according to the first layer performance. In the classification process, each pattern searches for several closest nodes from the base map and then it is classified into a specified class by determining the nearest model of the corresponding maps in the second layer. The new method yielded higher accuracy and faster performance than the ordinary self-organizing neural network.
CHARGE STRUCTURE IN THE Z0 AS A POSSIBLE ORIGIN OF RARE DECAYS Z0→l+l−γγ
Authors: BARSHAY SAUL , HEILIGER PATRICK
Published: November 2004

The possible rare direct decay Z0→l+l−γγ is a sensitive probe of structure in the Z0. It is possible that there is a mass distribution in high Mγγ, the invariant mass of two photons, which arises from structure in the Z0. This would lead to events with high Mγγ, over and above those that arise from bremsstrahlung. We find that such events could become evident when the data exceed about four million Z0 decays. We present quantitative results for the double distribution in the invariant masses, Mγγ and Mlī, and for the distribution in Mγγ. In the double distributions, Mγγ>45 GeV with Miī<35 GeV is favored.
PARTICLE CONTENT IN TOPOLOGICAL FIELD THEORIES
Authors: TOON ANDREW
Published: November 2004

By demanding that the path-integral measure of the topological field theories be metric-independent, we can derive powerful constraints on the particle content of a topological field theory as well as on the dimensionality of space-time. We also relate this metric independence to the number of degrees of freedom in the theory.
STRING LOOP THRESHOLD CORRECTIONS FOR ZN COXETER ORBIFOLDS
Authors: BAILIN D. , LOVE A. , SABRA W.A. , THOMAS S.
Published: November 2004

The moduli dependence of string loop threshold corrections to gauge coupling constants is investigated for those ZN Coxeter orbifolds with the property that some twisted sectors have fixed planes for which the six-torus T 6 cannot be decomposed into a direct sum T 4 ⊕ T 2 with the fixed plane lying in T 2.
ON COLLINEARIZATION OF QUARKS IN THE QUARK-GLUON DECAYS OF HEAVY ORTHOQUARKONIA
Authors: PARKHOMENKO A. YA. , SMIRNOV A.D.
Published: November 2004

The decay of heavy orthoquarkonium into quark-antiquark pair and two gluons is considered. The differential probability of the decay in the tree approximation is calculated and the probability distributions of quarks and gluons are obtained. The collinear enhancement of the bottomonium decay is shown to take place at the uū-, [Formula: see text] and [Formula: see text]-pairs production but is absent at the [Formula: see text]-pair production. Some other peculiarities of the considered decays are discussed.
HEAVY QUARKONIUM PHOTOPRODUCTION AT HIGH ENERGIES IN SEMIHARD APPROACH
Authors: SALEEV V.A. , ZOTOV N.P.
Published: November 2004

The heavy quark-antiquark bound states (J/Ψ, ϒ) photoproduction processes at very high energies are considered using the theory of semihard processes. The transverse momentum of the gluon, their longitudinal polarization and virtuality as well as the saturation effect in the gluon distribution function have been taken into account in the approach used here. The total and differential cross-sections of the J/Ψ and ϒ photoproduction have been calculated. For the case of J/Ψ, we obtained the remarkable difference between the predictions of the standard parton model and the approach used here.
TEMPERATURE DEPENDENCE OF THE QCD COUPLING
Authors: VAN EIJCK M.A. , STEPHENS C.R. , VAN WEERT CH. G.
Published: November 2004

We present a one-loop calculation of a gauge invariant QCD β-function. Using both momentum and temperature renormalization group equations we investigate the running coupling in the magnetic sector as a function of temperature and momentum scale. At fixed momentum scale we find that, in contrast to λɸ4 or QED, high temperature QCD is strongly coupled, even after renormalization group improvement. However, if the momentum scale is changed simultaneously with temperature in a specified manner, the coupling decreases. We also point out in what regime dimensional reduction occurs. Both the cases Nf smaller and larger than [Formula: see text] are discussed.
THE ELECTRIC DIPOLE MOMENT OF THE TOP
Authors: MAHMOOD SAJJAD
Published: November 2004

In an extension of the standard electroweak model with two-Higgs doublets the electric dipole moment of the top quark is estimated. It is observed that effects of Higgs exchange are significantly enhanced for a neutral Higgs boson lighter than the top quark.
PRODUCTION RATE OF PARTICLE PAIRS FROM A HOT QUANTUM-FIELD PLASMA WITH FINITE VOLUME
Authors: NIÉGAWA A. , TAKASHIBA K.
Published: November 2004

The production rate of scalar-particle pairs from finite temperature (T) plasma of massless-scalar particles confined in a cubic box of volume V is calculated. The Dirichlet boundary conditions are imposed on the wall of the box. The finite volume effect is found to be quite large at T=(2−3)×102 MeV and V=[(1−5)×10−13 cm ]3, the numerical values which have been estimated for the quark-gluon plasma produced in heavy-ion collisions at CERN SPS and LHC energies.
SEMICLASSICAL ANALYSIS OF THE ELASTIC SCATTERING OF PROTONS FROM 9Li AND 11Li
Authors: REGO R.A. , FREDERICO T. , HUSSEIN M.S.
Published: November 2004

We reproduce, with the aid of the WKB approximation, the general trend of the elastic scattering of 11 Li from a proton target at E Lab =62 MeV/A . The effect of the break up of halo neutrons is emphasized, when compared to the system p+9 Li at E Lab =60 MeV/A .
THRESHOLD NEUTRAL PION PHOTOPRODUCTION ON THE PROTON AND THE CLOUDY BAG MODEL
Authors: TABACHENKO A.N.
Published: November 2004

The energy dependence of the electric dipole amplitude, the total and differential cross-sections of the photoproduction of neutral pions off protons near threshold is given. The amplitude of process is a sum of the LET prediction and the additional term connected with the chiral symmetry breaking interaction. The simple K-matrix calculations are used to estimate the change in the electric dipole amplitude and the total and differential cross-sections between π0p and π+n thresholds.
COMPLEX q-MUTATOR ALGEBRA AND FRACTIONAL STATISTICS
Authors: MISHRA A.K. , RAJASEKARAN G.
Published: November 2004

We construct a q-deformed algebra of creation and destruction operators with ordered indices in which the deformation parameter is complex. Its consequences are studied and its relation to “fractional” statistics is pointed out.
MAJORANA-LIKE (j, 0) ⊕ (0, j) REPRESENTATION SPACES: CONSTRUCTION AND PHYSICAL INTERPRETATION
Authors: AHLUWALIA D.V. , JOHNSON M.B. , GOLDMAN T.
Published: November 2004

We present a formalism that extends the Majorana-construction to arbitrary spin (j, 0) ⊕ (0, j) representation spaces. For the example case of spin-one, a wave equation satisfied by the Majorana-like (1, 0) ⊕ (0, 1) spinors is constructed and its physical content explored. The (j, 0) ⊕ (0, j) Majorana-construct is found to possess an unusual classical and quantum field theoretic structure. Relevance of our formalism to parity violation, hadronic phenomenologies, and grand unified field theories is briefly pointed out.
THE INTERACTION OF QUANTIZED MATTER FIELDS WITH TORSION AND METRIC: NJL MODEL
Authors: SHAPIRO I. L.
Published: November 2004

We consider the interaction of matter fields with classical gravitational background in the framework of Nambu-Jona-Lasinio (NJL) model. Gravity includes not only metric but also independent torsion field. The renormalization group analysis shows that the matter-torsion interaction increases in a strong gravitational field and disappears at low energies.
CUBIC MASS RELATION IN SU(3) × U(1) ELECTROWEAK THEORY
Authors: FRAMPTON PAUL H. , KRASTEV PLAMEN I. , LIU JAMES T.
Published: November 2004

In the 331 model, lepton number may be explicitly broken by trilinear scalar self couplings. This leads to neutrino masses proportional to the cube of the corresponding charged lepton mass, with consequences for solar neutrinos and for hot dark matter.
DISCRETE SYMMETRY, NONCOMMUTATIVE GEOMETRY AND GRAVITY
Authors: MOHAMMEDI NOUREDDINE
Published: November 2004

We consider gravity using the formalism of a differential Z2-graded algebra of 2 × 2 matrices whose elements are differential forms on space-time. The connection and the orthonormal frame are extended to incorporate additional scalar and vector fields. The extended torsion-free constraints are solved for a simple case. The resulting action describes a set of scalar fields minimally coupled to Einstein-Hilbert gravity.
πº → γγ DECAY AND THE CONSTITUENT-QUARK VALUE FOR gA
Authors: DEAKIN A. S. , ELIAS V. , SCADRON M. D.
Published: November 2004

Consideration of the π° → γγ decay rate in effective models for low energy QCD suggests that the constituent-quark value of gA is quite close to unity.
WORMHOLES IN TWO-DIMENSIONAL DILATON GRAVITY
Authors: NOJIRI SHIN'ICHI , ODA ICHIRO
Published: November 2004

It is shown that the general solution of classical equations of motion in two-dimensional dilaton gravity proposed by Callan, Giddings, Harvey and Strominger (CGHS) includes a Lorentzian wormhole solution in addition to a black hole solution. We also show that matter perturbation of the wormhole by a shock wave leads to the formation of a black hole where the curvature singularity is cloaked by the global event horizon. It is also argued that the classical wormhole would be stable against quantum corrections.
ON A MEAN FIELD APPROXIMATION FOR HIGGS-YUKAWA SYSTEMS
Authors: ZENKIN SERGEI V.
Published: November 2004

We discuss the phase structure of a lattice Higgs-Yukawa system in the variational mean field approximation with contributions of fermionic determinant being calculated in a ladder approximation. In particular, we demonstrate that in this approximation the ferromagnetic phase in the Z2 model with naive fermions can appear as an artifact of a finite lattice and that the phase diagram for this model on infinite lattice changes qualitatively at space-time dimension D = 4 compared with those at D > 4.
CURIOSITIES AT c-EFFECTIVE = 1
Authors: FLOHR MICHAEL A. I.
Published: November 2004

The moduli space of all rational conformal quantum field theories with effective central charge c eff = 1 is considered. Whereas the space pf unitary theories essentially forms a manifold, the nonunitary ones form a fractal which lies dense in the parameter plane. Moreover, the points of this set are shown to be in one-to-one correspondence with the elements of the modular group for which an action on this set is defined.
INTRINSIC CHARM IN PROTON AND J/ψ PHOTOPRODUCTION AT HIGH ENERGIES
Authors: SALEEV V. A.
Published: November 2004

J/ψ and open charm photoproduction on charm quarks in a proton via partonic subprocess γc → J/ψc are discussed based on the perturbative theory of quantum chromodynamics and nonrelativistic quark model. It is shown that the value and energy dependence of the cross-section for such process depend remarkably on the choice of charm distribution function in a proton. In the region of small z = EJ/Eγ < 0.2 the contribution of the γc → J/ψc subprocess in the inelastic J/ψ photoproduction spectra is larger than the contribution of the photon-gluon fusion subprocess. At the energy range of HERA collider charm quarks contribution in the total inclusive J/ψ photoproduction cross-section may be equal to 60% of the dominant contribution of photon-gluon fusion mechanism.
TENSOR INTEGRALS FOR TWO-LOOP STANDARD MODEL CALCULATIONS
Authors: KREIMER DIRK
Published: November 2004

We give a new method for the reduction of tensor integrals to finite integral representations and uv divergent analytic expressions. This includes a new method for the handling of the γ-algebra.
COMPLEX q-ANALYSIS AND SCALAR FIELD THEORY ON A q-LATTICE
Authors: UBRIACO MARCELO R.
Published: November 2004

We develop the basic formalism of complex q-analysis to study the solutions of second order q-difference equations which reduce, in the q → 1 limit, to the ordinary Laplace equation in Euclidean and Minkowski space. After defining an inner product on the function space we construct and study the properties of the solutions, and then apply this formalism to the Schrödinger equation and two-dimensional scalar field theory.
DILATON INDUCED QUANTUM INFLATION-COMPACTIFICATION AND POSSIBILITY OF TRANSITION TO CLASSICAL ERA
Authors: GUENDELMAN E.I. , KAGANOVICH A.B.
Published: November 2004

In many interesting models, including superstring theories, a vacuum with negative cosmological constant is predicted. For quantum cosmology (in higher dimensions) in the presence of coherent dilaton excitations and a negative cosmological constant, the role of cosmic time can be understood and we can then predict the existence of a “quantum inflationary phase” for some dimensions and a simultaneous “quantum deflationary phase” for the remaining dimensions. We discuss qualitatively how it may be possible to exit from this inflation-compactification era and give an example which involves a transition to a phase with zero cosmological constant which allows a classical description at late times.
SWIMMING OF MICRO-ORGANISMS VIEWED FROM STRING AND MEMBRANE THEORIES
Authors: KAWAMURA MASAKO , SUGAMOTO AKIO , NOJIRI SHIN’ICHI
Published: November 2004

Swimming of micro-organisms is studied from a viewpoint of extended objects (strings and membranes) swimming in the incompressible fluid of low Reynolds number. The flagellated motion is analyzed in two-dimensional fluid, by using the method developed in the ciliated motion with the Joukowski transformation. Discussion is given on the conserved charges and the algebra which are associated with the area (volume)-preserving diffeomorphisms giving the swimming motion of micro-organisms. It is also suggested that the N-point string- and membrane-like amplitudes are useful for studying the collective swimming motion of micro-organisms when fluctuation of the vorticity distribution exists in the sticky or rubber-like fluid.
DAVEY-STEWARTSON EQUATION FROM A ZERO CURVATURE AND A SELF-DUALITY CONDITION
Authors: BRUNELLI J.C. , DAS ASHOK
Published: November 2004

We derive the two equations of Davey-Stewartson type from a zero curvature condition associated with SL(2, ℝ) in (2+1) dimensions. We show in general how a (2+1)dimensional zero curvature condition can be obtained from the self-duality condition in (3+3) dimensions and show in particular how the Davey-Stewartson equations can be obtained from the self-duality condition associated with SL(2, ℝ) in (3+3) dimensions.
ON STRING THEORY INTERACTING WITH TWO-DIMENSIONAL GRAVITY
Authors: BUCHBINDER I.L. , SHAPIRO I.L. , SIBIRYAKOV A.G.
Published: November 2004

The approach is proposed to unification of the string theory and the two-dimensional gravity. Three classically equivalent forms are given. The one-loop counterterms are calculated in harmonic and conformal gauges. The relation between the counterterms for different classically equivalent variants of the theory and for the different gauge choices are studied.
A STRING MODEL WITH ONE PHYSICAL STATE
Authors: STOILOV M. , STOYANOV D.
Published: November 2004

Further investigation on a bosonic string model with second class constraints is carried out. The physical space of the model is built up. It is shown, using analogy with the point particle with additional space-time gauge symmetry, that there is only one physical state in the model corresponding to an antisymmetric second rank tensor.
HAMILTONIAN REDUCTION AND TOPOLOGICAL CONFORMAL ALGEBRA IN c<1 NON-CRITICAL STRINGS
Authors: ITO KATSUSHI , KANNO HIROAKI
Published: November 2004

We study the Hamiltonian reduction of affine Lie superalgebra sl(2|1)(1). Based on a scalar Lax operator formalism, we derive the free field realization of the classical topological algebra which appears in the c≤1 non-critical strings. In the quantum case, we analyze the BRST cohomology to get the quantum free field expression of the algebra.
ON THE LOCAL HAMILTONIAN STRUCTURE OF VECTOR FIELDS
Authors: CREHAN P.
Published: November 2004

We derive a canonical form for smooth vector fields on ℜn+1. We use this to demonstrate the local multi-Hamiltonian nature of the corresponding flows. Associated with the canonical form is an inhomogeneous linear PDE whose solutions provide conserved measures. These can be used to construct the local Hamiltonians.
THREE-MANIFOLD INVARIANTS ARISING FROM Uq(osp(1|2))
Authors: ZHANG R.B.
Published: November 2004

The algebraic approach to three-manifold invariants developed by Reshetikhin and Turaev is extended to the quantum supergroup Uq(osp(1|2)). A set of new topological invariants is obtained, which depend on a family of complex parameters.
ON THE MULTILEVEL FIELD-ANTIFIELD FORMALISM WITH THE MOST GENERAL LAGRANGIAN HYPERGAUGES
Authors: BATALIN I.A. , TYUTIN I.V.
Published: November 2004

The multilevel field-antifield formalism is constructed in a geometrically covariant way without imposing the unimodularity conditions on the hypergauge functions. Thus the version given in Refs. 1 and 2 can be extended to cover the most general case of Lagrangian surface bases. It is shown that the extra measure factors, required to enter the gauge-independent functional integrals, can be included naturally into the multilevel scheme by modifying the boundary conditions to the quantum master equation.
PHOTOPRODUCTION OF ETA MESONS ON NUCLEI AS A UNIQUE PROBE OF THE COHERENT, ISOSCALAR VECTOR-MESON FIELD NEAR THE NUCLEAR SURFACE
Authors: BARSHAY S. , BRAMON A.
Published: November 2004

With the partial width for η→2γ determined by recent measurements in the process e+e−→e+e−η, we re-examine older data on the Primakoff effect. We show that photoproduction on nuclei can be used to determine the strength and the A-dependence of the coherent, isoscalar vector-meson field of the nuclei.
A PHENOMENOLOGICAL THEORY OF FERMION MASSES AND MIXINGS
Authors: HUNG P.Q.
Published: November 2004

A phenomenological theory of fermion masses and mixings is constructed within the framework of a four-family symmetry. It is found that the most favored set of relevant CKM elements are |Vus| ≈ 0.222, |Vcb| ≈ 0.044, |Vub/Vcb| ≈ 0.082, |Vud| ≈ 0.974, |Vcs| ≈0.9736, |Vcd| ≈ 0.224 with [Formula: see text]. The top quark mass is predicted to be 258 GeV at 1 GeV with its physical mass approximately in the range of 153 GeV to 165 GeV. Some remarks on the relationship between the lepton sector and the quark sector will be made.
THE EFFECT OF DYNAMICAL GAUGE FIELD ON THE CHIRAL FERMION ON A BOUNDARY
Authors: AOKI HAJIME , ISO SATOSHI , NISHIMURA JUN , OSHIKAWA MASAKI
Published: November 2004

We study the effect of dynamical gauge field on the Kaplan’s chiral fermion on a boundary in the strong gauge coupling limit in the extra dimension. To all orders of the hopping parameter expansion, we prove exact parity invariance of the fermion propagator on the boundary. This means that the chiral property of the boundary fermion, which seems to survive even in the presence of the gauge field from a perturbative point of view, is completely destroyed by the dynamics of the gauge field.
BFV QUANTIZATION OF RELATIVISTIC SPINNING PARTICLES WITH A SINGLE BOSONIC CONSTRAINT
Authors: RABELLO SILVIO J. , VAIDYA ARVIND N.
Published: November 2004

Using the BFV approach we quantize a pseudoclassical model of the spin-1/2 relativistic particle that contains a single bosonic constraint, contrary to the usual locally supersymmetric models that display first and second class constraints.
HIDDEN HIGGS PARTICLE
Authors: KOVALENKO S.G.
Published: November 2004

A modification of the standard model of electroweak interactions with the nonlocal Higgs sector is proposed. Proper form of nonlocality makes Higgs particles unobservable after the electroweak symmetry breaking. They appear only as a virtual state because their propagator is an entire function. We discuss some specific consequences of this approach comparing it with the conventional standard model.
CRITICAL SCALING IN THE MATRIX MODEL ON A BETHE TREE
Authors: BOULATOV D.V.
Published: November 2004

The matrix model with a Bethe tree embedding space (coincides at large N with the Kazakov-Migdal “induced QCD” model1) is investigated. We further elaborate the Riemann-Hilbert approach of Ref. 2 assuming certain holomorphic properties of the solution. The critical scaling (an edge singularity of the density) is found to be [Formula: see text][Formula: see text] arccos D, for |D|<1, and [Formula: see text] arccos [Formula: see text] for D>1. Explicit solutions are constructed at D=1/2 and D=∞.
HILBERT-EINSTEIN ACTION FROM INDUCED GRAVITY COUPLED WITH SCALAR FIELD
Authors: SHAPIRO I.L.
Published: November 2004

Quantum theory of conformal factor coupled with matter fields is investigated. The more simple case of the purely classical scalar matter is considered. The conformal factor contribution to the effective potential of scalar field is calculated. Then the possibility of the first order phase transition is explored and the induced values of Newtonian and cosmological constants are calculated.
GLOBAL COUNTERPART OF k-POINCARÉ ALGEBRA AND COVARIANT WAVE FUNCTIONS
Authors: MAŚLANKA PAWEL
Published: November 2004

The global counterpart of k-Poincaré algebra is considered. The induced representations of this group are described. The explicit form of the covariant wave functions in the ‘minimal’ (in Weinberg’s sense) case is given.
RENORMALIZATION GROUP EFFECTS IN THE CONFORMAL SECTOR OF 4D QUANTUM GRAVITY WITH MATTER
Authors: ODINTSOV S. , PERCACCI R.
Published: November 2004

We discuss the “gravitationally dressed” beta functions in the Gross-Neveu model interacting with 2d Liouville theory and in SU(N) gauge theory interacting with the conformal sector of 4d quantum gravity. Among the effects we suggest one may feel that the gravitational dressing are the minimum of the effective potential and the running of the gauge coupling.
MESIC MOLECULES OF LIGHT NUCLEI IN THE OSCILLATOR REPRESENTATION
Authors: DINEYKHAN M. , EFIMOV G.V.
Published: November 2004

The mesic molecules (HμNZ), where H is the hydrogen isotopes (p, d, t) and NZ are nuclei with charges Z=2, 3, 4, …and masses MZ=2Zmp, are studied. The energy values of the ground state for the mesic molecules of light nuclei have been calculated by using the oscillator representation method. The dependence of the binding energies of the muonic molecules on nuclear charges and the critical values of nuclear charges are obtained.
NONPERTURBATIVE β-FUNCTION IN QUANTUM CHROMODYNAMICS
Authors: SISSAKIAN A.N. , SOLOVTSOV I.L. , SOLOVTSOVA O.P.
Published: November 2004

We propose a method by which it is possible to go beyond the scope of quantum chromodynamics perturbation theory. By using a new small parameter we formulate a systematic nonperturbative expansion and derive a renormalization β-function in quantum chromodynamics.
CHARGED AND NEUTRAL CURRENTS IN THE 331 MODEL WITH RIGHT-HANDED NEUTRINOS
Authors: LONG H.N. , TRAN TUAN A.
Published: November 2004

Charged and neutral currents in the 331 model with right-handed neutrinos in the triplets are investigated. We show that the model not only is simpler than Pisano-Pleitez-Frampton’s model in the Higgs sector but also gives the couplings of neutrinos with the Z bosons consistent with the standard model.
EXACT STRING SOLUTIONS IN (2 + 1)-DIMENSIONAL DE SITTER SPACE-TIME
Authors: DE VEGA H. J. , MIKHAILOV A. V. , SÁNCHEZ N.
Published: November 2004

Exact and explicit string solutions in de Sitter space-time are found. (Here, the string equations reduce to a sinh-Gordon model). A new feature without flat space-time analogy appears: starting with a single worldsheet, several (here two) strings emerge. One string is stable and the other (unstable) grows as the universe grows. Their invariant size and energy either grow as the expansion factor or tend to constant. Moreover, strings can expand (contract) for large (small) universe radius at a different rate than the universe does.
TRAJECTORY-COHERENT STATES AND THE HEISENBERG'S UNCERTAINTY RELATION
Authors: KARAVAYEV A. G.
Published: November 2004

In this paper we investigate the problem of minimizing the Heisenberg's uncertainty relation with the trajectory-coherent states. The conditions of minimization for Hamiltonian and trajectory are obtained. We show that the trajectory-coherent states minimize the Heisenberg's uncertainty relation for special Cauchy problem of the Schrödinger equation only.
BOUNDARY DYNAMICS IN DILATON GRAVITY
Authors: DAS SUMIT R. , MUKHERJI SUDIPTA
Published: November 2004

We study the dynamics of the boundary in two-dimensional dilaton gravity coupled to N massless scalars. We rederive the boundary conditions of Refs. 1 and 3 in a way which makes the requirement of reparametrization invariance and the role of conformal anomaly explicit. We then study the semiclassical behavior of the boundary in the N = 24 theory in the presence of an incoming matter wave with a constant energy flux spread over a finite interval. There is a critical value of the matter energy density below which the boundary is stable and all the matter is reflected back. For energy densities greater than this critical value there is a similar behavior for small values of the total energy thrown in. However, when the total energy exceeds another critical value the boundary exhibits a runaway behavior and the space-time develops singularities and horizons.
QUANTUM EFFECTS ASSOCIATED WITH AN ELECTRICALLY NEUTRAL MASSLESS PARTICLE IN A BERTOTTI-ROBINSON UNIVERSE
Authors: VILLALBA VÍCTOR M.
Published: November 2004

In this article we obtain, by separation of variables, an exact solution to the Dirac equation with anomalous momentum for an electrically neutral massless particle in a Bertotti-Robinson universe. We discuss the phenomenon of particle creation in this model.
A COMMENT ON THE ODD FLOWS FOR THE SUPERSYMMETRIC KdV EQUATION
Authors: RAMOS EDUARDO
Published: November 2004

In a recent paper Dargis and Mathieu introduced integrodifferential odd flows for the supersymmetric KdV equation. These flows are obtained from the nonlocal conservation laws associated with the fourth root of its Lax operator. In this note I show that only half of these flows are of the standard Lax form, while the remaining half provide us with Hamiltonians for an SKdV-type reduction of a new supersymmetric hierarchy. This new hierarchy is shown to be closely related to the Jacobian supersymmetric KP-hierarchy of Mulase and Rabin. A detailed study of the algebra of additional symmetries of this new hierarchy reveals that it is isomorphic to the super-W1+∞ algebra, thus making it a candidate for a possible interrelationship between superintegrability and two-dimensional supergravity.
CONFORMAL SECTOR IN D=6 QUANTUM GRAVITY
Authors: ODINTSOV SERGEI D. , ROMEO AUGUST
Published: November 2004

We discuss the conformal factor dynamics in D=6. Accepting the proposal that higher derivative dimensionless terms in the anomaly-induced effective action may be dropped, we obtain a super-renormalizable (like in D=4) effective theory for the conformal factor. The one-loop analysis of this theory gives the anomalous scaling dimension for the conformal factor and provides a natural mechanism to solve the cosmological constant problem.
ON THE WARD IDENTITIES AT FINITE TEMPERATURE
Authors: DAS ASHOK , HOTT MARCELO
Published: November 2004

We show in both 1+1 and 3+1 dimensions that, contrary to the recent suggestions, the contribution of the fermion loop to the polarization tensor is manifestly transverse at finite temperature. Some subtleties associated with the Ward identities at finite temperature are also pointed out.
UNIVERSAL PARAMETRIZATION FOR QUARK AND LEPTON SUBSTRUCTURE
Authors: AKAMA KEIICHI , TERAZAWA HIDEZUMI
Published: November 2004

A universal parametrization for possible quark and lepton substructure is advocated in terms of quark and lepton form factors. It is emphasized that the lower bounds on compositeness scale, Λc, to be determined experimentally depend strongly on their definitions in composite models. From the recent HERA data, it is estimated to be Λc>50 GeV , 0.4 TeV and 10 TeV, depending on the parametrizations with a single-pole form factor, a contact interaction and a logarithmic form factor, respectively.
AZIMUTHAL CORRELATION FOR COHERENT SOURCES IN PHASE TRANSITION
Authors: HWA RUDOLPH C. , LAM C.S.
Published: November 2004

We present a formulation of the correlation problem in the transverse plane of high-energy nuclear collisions. The correlation variable is the azimuthal angle between two transverse momenta. We assume that the effects of quark-hadron phase transition are manifested in the existence of a coherence angle χ and a parameter ε characterizing the irreducible correlation. We then derive the consequences on the observable two-particle correlation function.
REPLY TO “ON THE DEFINITENESS OF THE CONFORMAL ANOMALY IN NONCONFORMAL GAUGES”
Authors: ABE MITSUO , NAKANISHI NOBORU
Published: November 2004

On the ambiguity arising in the derivation of the critical dimension of bosonic string in the covariant gauge shown by the present authors, there appears a critical paper by Mödritsch. A reply to this criticism is made by pointing out his misunderstanding about how the ambiguity arises.
QUARK-GLUON VERTEX AND STRUCTURE OF MESONS AND DIQUARKS
Authors: STAINSBY S.J. , CAHILL R.T.
Published: November 2004

Two quark propagators with different analytic structure are employed in Bethe-Salpeter type equations for the pion and scalar diquark form factors. One of the quark propagators has been calculated with the inclusion of a trivial (bare) quark-gluon vertex and, as a consequence, contains a complex conjugate pair of logarithmic branch points. The other quark propagator is obtained using a non-trivial (dressed) vertex ansatz and is entire, with an essential singularity at infinity. The effects of these different quark propagators on the BSE solutions are compared.
SYMMETRY PRINCIPLES TOWARD SOLUTIONS OF THE μ PROBLEM
Authors: KIM JIHN E. , NILLES HANS PETER
Published: November 2004

We stress that a natural solution of the μ problem requires two ingredients: a symmetry that would enforce μ=0 as well as the occurrence of a small breaking parameter that generates a nonzero μ. It is suggested that both the Peccei-Quinn symmetry and the spontaneously broken R symmetry may be the sources of the needed μ term in the minimal supersymmetric standard model provided that they are spontaneously broken at a scale 1010–1012 GeV . To solve the strong CP problem with a hidden sector confining group, both of these symmetries are needed in superstring models with an anomalous U (1)A.
TOPOLOGICAL MANIFESTATIONS IN CLASSICAL MECHANICS: DISCRETE ALLOWED AND FORBIDDEN STATES OF MOTION
Authors: VARMA RAM K.
Published: November 2004

Consequences of the topology of the configuration space of a Hamiltonian dynamical system are considered for a coherent system of trajectories. It is shown that when the space is multiply-connected and therefore the action integral is multivalued, the allowed states of motion (labeled by the initial data) are constrained to a discrete set by the requirement that the action be single-valued. One thus obtains a quantum-like discretization of allowed states of motion even in classical mechanics. Such discrete “allowed” and “forbidden” states have indeed been observed in the classical mechanical system of charged particles in a magnetic field. The relationship of this formalism with a Schrödinger-like formalism for the latter problem given earlier is discussed.
QUANTUM THEORY OF NON-ABELIAN DIFFERENTIAL FORMS AND LINK POLYNOMIALS
Authors: BRODA BOGUSLAW
Published: November 2004

A topological quantum field theory of non-Abelian differential forms is investigated from the point of view of its possible applications to description of polynomial invariants of higher-dimensional two-component links. A path-integral representation of the partition function of the theory, which is a highly on-shell reducible system, is obtained in the framework of the antibracket-antifield formalism of Batalin and Vilkovisky. The quasi-monodromy matrix, giving rise to corresponding skein relations, is formally derived in a manifestly covariant non-perturbative manner.
SOLVING THE WARD IDENTITIES OF IRRATIONAL CONFORMAL FIELD THEORY
Authors: HALPERN M.B. , OBERS N.A.
Published: November 2004

The affine-Virasoro Ward identities are a system of nonlinear differential equations which describe the correlators of all affine-Virasoro constructions, including rational and irrational conformal field theory. We study the Ward identities in some detail, with several central results. First, we solve for the correlators of the affine-Sugawara nests, which are associated with the nested subgroups g⊃h1⊃…⊃hn. We also find an equivalent algebraic formulation which allows us to obtain global solutions across the set of all affine-Virasoro constructions. A particular global solution is discussed which gives the correct nest correlators, exhibits braiding for all affine-Virasoro correlators, and shows good physical behavior, at least for four-point correlators at high level on simple g. In rational and irrational conformal field theory, the high-level fusion rules of the broken affine modules follow the Clebsch-Gordan coefficients of the representations.
ON THE EXACT OPERATOR FORMALISM OF TWO-DIMENSIONAL LIOUVILLE QUANTUM GRAVITY IN MINKOWSKI SPACE-TIME
Authors: KAZAMA YOICHI , NICOLAI HERMANN
Published: November 2004

A detailed re-examination is made of the exact operator formalism of two-dimensional Liouville quantum gravity in Minkowski space-time with the cosmological term fully taken into account. Making use of the canonical mapping from the interacting Liouville field into a free field, we focus on the problem of how the Liouville exponential operator should be properly defined. In particular, the condition of mutual locality among the exponential operators is carefully analyzed, and a new solution, which is neither smoothly connected nor relatively local to the existing solution, is found. Our analysis indicates that, in Minkowski space-time, coupling gravity to matter with central charge d<1 is problematical. For d=1, our new solution appears to be the appropriate one; for this value of d, we demonstrate that the operator equation of motion is satisfied to all orders in the cosmological constant with a certain regularization. As an application of the formalism, an attempt is made to study how the basic generators of the ground ring get modified due to the inclusion of the cosmological term. Our investigation, although incomplete, suggests that in terms of the canonically mapped free field the ground ring is not modified.
DIFFICULTIES OF AN INFRARED EXTENSION OF DIFFERENTIAL RENORMALIZATION
Authors: AVDEEV L. V. , KAZAKOV D. I. , KONDRASHUK I. N.
Published: November 2004

We investigate the possibility of generalizing the differential renormalization of D. Z. Freedman, K. Johnson and J. I. Latorre in an invariant fashion to theories with infrared divergencies via an infrared [Formula: see text] operation. Two-dimensional σ models and the four-dimensional ɸ4-theory diagrams with exceptional momenta are used as examples, while dimensional renormalization serves as a test scheme for comparison. We write the basic differential identities of the method simultaneously in co-ordinate and momentum space, introducing two scales which remove ultraviolet and infrared singularities. A consistent set of Fourier-transformation formulae is derived. However, the values for tadpole-type Feynman integrals in higher orders of perturbation theory prove to be ambiguous, depending on the order of evaluation of the subgraphs. In two dimensions, even earlier than this ambiguity manifests itself, renormalization-group calculations based on the infrared extension of differential renormalization lead to incorrect results. We conclude that the procedure of extended differential renormalization does not perform the infrared [Formula: see text] operation in a self-consistent way.
GAUGE THEORY BASED ON NONLINEAR LIE SUPERALGEBRAS AND STRUCTURE OF 2D DILATON SUPERGRAVITY
Authors: IKEDA NORIAKI
Published: November 2004

We construct a gauge theory based on general nonlinear Lie superalgebras. The generic form of "dilaton" supergravity is derived from nonlinear super-Poincaré algebra, which exhibits a gauge-theoretical formulation in two-dimensional gravitation theory, and clarifies the symmetry structure of two-dimensional dilaton supergravity.
ON THE LANDAU–GINZBURG DESCRIPTION OF $(A_1^{(1)})^{\oplus N}$ INVARIANTS
Authors: FUCHS JÜRGEN , KREUZER MAXIMILIAN
Published: November 2004

We search for a Landau–Ginzburg interpretation of nondiagonal modular invariants of tensor products of minimal n = 2 superconformal models, looking in particular at automorphism invariants and at some exceptional cases. For the former we find a simple description as Landau–Ginzburg orbifolds, which reproduces the correct chiral rings as well as the spectra of various Gepner type models and orbifolds thereof. On the other hand, we are able to prove for one of the exceptional cases that this conformal field theory cannot be described by an orbifold of a Landau–Ginzburg model with respect to a manifest linear symmetry of its potential.
A LARGE CLASS OF NEW GRAVITATIONAL AND AXIONIC BACKGROUNDS FOR FOUR-DIMENSIONAL SUPERSTRINGS
Authors: KIRITSIS E. , KOUNNAS C. , LÜST D.
Published: November 2004

A large class of new 4D superstring vacua with nontrivial/singular geometries, space–time supersymmetry and other background fields (axion, dilaton) are found. Killing symmetries are generic and are associated with nontrivial dilaton and antisymmetric tensor fields. Duality symmetries preserving N = 2 superconformal invariance are employed to generate a large class of explicit metrics for noncompact 4D Calabi–Yau manifolds with Killing symmetries. We comment on some of our solutions which have interesting singularity properties and cosmological interpretation.
FINITE CASIMIR EFFECT IN QUANTUM FIELD THEORY
Authors: BLASI A. , COLLINA R. , SASSARINI J.
Published: November 2004

The computation of the Casimir effect is directly linked to the modification of the vacuum energy due to the presence of boundaries. In order to have complete control of the short distance behavior also near the boundary, the analysis is performed in the precise framework of a local, renormalizable quantum field theory which includes the boundary contributions. We show that the presence of soft terms at the boundary, needed to implement Robin's conditions, introduces a free parameter in the final, finite answer, a parameter which has no natural normalization condition within the scheme. We discuss in detail a free massless scalar field in R3 with plane and cylindric boundaries; in particular the second case, where the boundary soft term is essential to remove sub-leading short distance divergencies, suffers the mentioned indeterminacy, which might be removed by a phenomenological interpretation relating the soft term to a microscopic description of the boundary.
STABLE QUASIPARTICLE PICTURE IN THERMAL QUANTUM FIELD PHYSICS
Authors: CHU H. , UMEZAWA H.
Published: November 2004

It is well known that physical particles are thermally dissipative at finite temperature. In this paper we reformulate both the equilibrium and nonequilibrium thermal field theories in terms of stable quasiparticles. We will redefine the thermal doublets, the double tilde conjugation rules and the thermal Bogoliubov transformations so that our theory can be consistent for most general situations. All operators, including the dissipative physical particle operators, are realized in a Fock space defined by the stable quasiparticles. The propagators of the physical particles are expressed in terms of the operators of such stable quasiparticles, which is a simple diagonal matrix with the diagonal elements being the temporal step functions, same as the propagators in the usual quantum field theory without thermal degrees of freedom. The proper self-energies are also expressed in terms of these stable quasiparticle propagators. This formalism inherits the definition of on-shell self-energy in the usual quantum field theory. With this definition, a self-consistent renormalization is formulated which leads to quantum Boltzmann equation and the entropy law. With the aid of a doublet vector algebra we have an extremely simple recipe for computing Feynman diagrams. We apply this recipe to several examples of equilibrium and nonequilibrium two-point functions, and to the kinetic equation for the particle numbers.
ANALYSIS OF SERIES CONVERGENCE IN VARIATIONAL PERTURBATION THEORY AND GAUSSIAN EFFECTIVE POTENTIAL
Authors: SISSAKIAN A.N. , SOLOVTSOV I.L. , SHEVCHENKO O. YU.
Published: November 2004

The properties of convergence are studied for the series in the variational perturbation theory for the φ4(d) model. The nonperturbative Gaussian effective potential is derived from a more general approach, the variational perturbation theory. Various versions of the variational procedure are explored and the preference of the anharmonic variational procedure in view of convergence of the obtained series is argued.
NONPERTURBATIVE CONDITIONS FOR LOCAL WEYL INVARIANCE ON A CURVED WORLD-SHEET
Authors: SCHNITTGER JENS , ELLWANGER ULRICH
Published: November 2004

We investigate Weyl anomalies on a curved world-sheet to the second order in a weak field expansion. Using a local version of the exact renormalization group equations, we obtain nonperturbative results for the tachyon/graviton/dilaton system. We discuss the elimination of redundant operators, which play a crucial role for the emergence of target space covariance. Performing the operator product expansion on a curved world-sheet allows us to obtain the nonperturbative contributions to the dilaton β function. We find the β functions, after suitable field redefinitions, to be related to a target space effective action through a κ function involving derivatives. Also, we can establish a nonperturbative Curci-Paffuti relation including the tachyon β function.
TECHNIDILATON PHENOMENOLOGY AND PROSPECTS FOR PRODUCTION
Authors: HALYO EDI
Published: November 2004

An effective Lagrangian for the technidilaton and its interactions with matter is constructed. Properties of the technidilaton are compared with those of the Higgs boson. Technidilaton decays and production channels are investigated. Main technidilaton decays are suppressed compared to the Higgs boson and the most important production mechanism is due to gluon fusion. Prospects for technidilaton production and detection at e+e− colliders and SSC are examined. LEP 1, LEP 2 and SSC can find or rule out a technidilaton with a mass up to 10 GeV, 40 GeV and 230 GeV respectively.
MODELS OF CP VIOLATION EXCLUSIVELY VIA NEUTRAL-SCALAR EXCHANGE
Authors: LAVOURA L.
Published: November 2004

I suggest a two-Higgs-doublet model in which CP violation is mediated only by the neutral Higgs bosons, via the mechanism of scalar-pseudoscalar mixing. In this model there is no CP violation in the exchange of either W bosons or charged Higgs bosons. The model has only two basic CP-violating quantities. I remark that other models of this kind, but with more than two Higgs doublets, may also be built.
LOCAL GAUGE FIELDS BASED ON A U(1) GAUGE THEORY IN LOOP SPACE
Authors: DEGUCHI SHINICHI , NAKAJIMA TADAHITO
Published: November 2004

We present a U(1) gauge theory defined in loop space, the space of all loops in Minkowski space. On the basis of the U(1) gauge theory, we derive a local field theory of the second-rank antisymmetric tensor field (Kalb-Ramond field) and the Stueckelberg formalism for a massive vector field; the second-rank antisymmetric tensor field and the massive vector field are regarded as parts of a U(1) gauge field on the loop space. We also consider the quantum theories of the second-rank antisymmetric tensor field and the massive vector field on the basis of a BRST formalism for the U(1) gauge theory in loop space. In addition, reparametrization invariance in the U(1) gauge theory is discussed in detail.
A CLASS OF MODELS WITH LARGE NEUTRINO MAGNETIC MOMENT
Authors: CHANG DARWIN , KEUNG W.-Y. , PHILLIPS IVAN
Published: November 2004

We show how a list of symmetry principles can be used to generate a class of models in which the neutrino masses are suppressed while relatively large magnetic moments are allowed. The simplest example is a model for neutrino mass proposed by Zee some time ago. We show how the model can be improved based on the symmetry principle and we also demonstrate other models in this class which avoid some of the weakness in the simplest model.
COMPARISON OF THE ANOMALOUS AND NONANOMALOUS GENERALIZED SCHWINGER MODELS VIA THE FUNCTIONAL FORMALISM
Authors: DUTRA ALVARO DE SOUZA
Published: November 2004

We calculate the Green functions of the two versions of the generalized Schwinger model, the anomalous and the nonanomalous one, in their higher order Lagrangian density form. Furthermore, it is shown through a sequence of transformations that the bosonized Lagrangian density is equivalent to the former, at least for the bosonic correlation functions. The introduction of the sources from the beginning, leading to a gauge-invariant source term, is also considered. It is verified that the two models have the same correlation functions only if the gauge-invariant sector is taken into account. Finally, there is presented a generalization of the Wess-Zumino term, and its physical consequences are studied, in particular the appearance of gauge-dependent massive excitations.
THERMODYNAMICS OF A FREE q-FERMION GAS
Authors: DUTT RANABIR , GANGOPADHYAYA ASIM , KHARE AVINASH , SUKHATME UDAY P.
Published: November 2004

We study the thermodynamics of a q-fermion gas for complex values of q on the unit circle. Special emphasis is given to the study of the virial coefficients and the specific heat of this gas. In particular, it is shown that if any state can accommodate up to p q-fermions, then the first p virial coefficients of such a gas are the same as that of a gas of free bosons. Explicit expressions for the deviation of higher virial coefficients from the corresponding values for a Bose gas are obtained. Further, as for ordinary fermions, it is shown that the specific heat of a q-fermion gas at low temperature is proportional to T. Numerical computations show that the derivative of the specific heat as a function of T has no discontinuity.
RADIATIVE DECAYS OF LIGHT MESONS IN THE STRAIGHT-LINE STRING THEORY
Authors: BERDNIKOV E.B.
Published: November 2004

The radiative transitions of light mesons are considered in the relativistic string model. The predictions for the decay rates of the light I=1 mesons and K mesons are presented.