bluuebunny/crossref_metadata_2025 huggingface dataset:
OBSERVATION OF NEUTRAL CURRENT CHARM PRODUCTION IN νμFe SCATTERING AT THE TEVATRON
Authors: Alton A. , Adams T. , Avvakumov S. , de Barbaro L. , de Barbaro P. , Bernstein R. H. , Bodek A. , Bolton T. , Brau J. , Buchholz D. , Budd H. , Bugel L. , Conrad J. , Drucker R. B. , Fleming B. T. , Formaggio J. , Frey R. , Goldman J. , Goncharov M. , Harris D. A. , Johnson R. A. , Kim J. H. , Koutsoliotas S. , Lamm M. J. , Marsh W. , Mason D. , McDonald J. , McFarland K. S. , McNulty C. , Naples D. , Nienaber P. , Romosan A. , Sakumoto W. K. , Schellman H. , Shaevitz M. H. , Spentzouris P. , Stern E. G. , Suwonjandee N. , Vakili M. , Vaitaitis A. , Yang U. K. , Yu J. , Zeller G. P. , Zimmerman E. D.
Published: April 2003

We report on the first observation of open charm production in neutral current deep inelastic neutrino scattering as seen in the NuTeV detector at Fermilab. The production rate is shown to be consistent with a pure gluon-Z0 boson production model, and the observed level of charm production is used to determine the effective charm mass.
NEUTRINO PHYSICS AT NEUTRINO FACTORIES
Authors: WHISNANT K.
Published: April 2003

The physics capabilities of neutrino beams from neutrino factories are briefly presented for both three- and four-neutrino models.
OPAL SEARCHES FOR PROMPT LIGHT GRAVITINO PRODUCTION AT LEP
Authors:   Representing the OPAL Collaboration., KRIEGER PETER
Published: April 2003

Results of searches for the signatures of promptly decaying light gravitinos are presented, based on data collected using the OPAL detector at LEP. This paper focuses primarily on updates to the results of published analyses of approximately 182 pb -1 taken at [Formula: see text] in 1998. These updates are based on analysis of data collected in the energy range of [Formula: see text] in the year 2000. All results from this data sample are preliminary.
SEARCH FOR SGOLDSTINO IN e+e- COLLISIONS AT $\sqrt{S}$ FROM 189 TO 202 GEV WITH THE DELPHI EXPERIMENT
Authors: PIOTTO ENRICO
Published: April 2003

Recent theoretical studies have proposed new phenomenological scenarios where the gravitino is light and the sgoldstino can be light and so be detectable at LEP. A novelty of this framework is that the sgoldstino being a SM particle, its decay chains do not involve other supersymmetric particles, like the LSP (lightest supersymmetric particle), which could escape detection and lead to final states with missing energy. A search for sgoldstino has been performed, for the first time, in DELPHI. At LEP2 sgoldstinos are mainly produced accompanied by a photon. This process is followed by S decay into two gluons or two photons, leading to final states with three photons or two jets and one photon. Sgoldstino phenomenology, production mechanisms, the decay chains and the particle width, will be discussed. Since no evidence for this particle has been found, the limits on parameter space have been set.
SEARCH FOR SUSY WITH $/\kern-7.2pt E_T$ AND JETS AT CDF
Authors:   Representing the CDF Collaboration., HAAS RICHARD
Published: April 2003

Events with signatures involving large missing transverse energy [Formula: see text] are among the quintessential search modes for R-parity conserving supersymmetry. CDF has conducted two recent analyses for supersymmetry which use [Formula: see text] and jets. The [Formula: see text] and monojet signature is employed to determine process independent limits for the production of new physics beyond the Standard Model and then applied to models of spontaneous breaking of supersymmetry to determine limits on the supersymmetry breaking parameter and the gravitino mass. Direct searches for scalar top and scalar bottom quarks within the framework of supersymmetric models are performed using a signature of [Formula: see text] and two heavy flavor jets. Since the data is found to be consistent with Standard Model expectations, limits are determined in the mass planes [Formula: see text] and [Formula: see text].
Search for an LSP Gluino from Stop Decay
Authors: VERDIER PATRICE
Published: April 2003

In some supersymmetric models, the gluino [Formula: see text] could be light and stable, and would hadronize to form R-hadrons. Data collected by the DELPHI detector at centre-of-mass energy from 189 to 202 GeV corresponding to an integrated luminosity of 384 pb -1 have been used to search for R-hadrons from stop decay. The observed number of events is in agreement with the Standard Model predictions. Results are presented in terms of excluded regions in the plane [Formula: see text]
STANDARD MODEL HIGGS COMBINED RESULT FROM CDF
Authors:   On behalf of the CDF Collaboration., DA COSTA JOÃO GUIMARÃES
Published: April 2003

The Tevatron is expected to be most sensitive to the Standard Model Higgs in its associated production with a W or Z boson. The Collider Detector at Fermilab (CDF) has performed individual searches for such production in each decay channel of the vector boson, assuming that the Higgs decays to [Formula: see text]. These searches use data collected by CDF during the 1992-95 run. The individual results are reviewed, and a combined cross section limit is presented.
SEARCH FOR MAGNETIC MONOPOLES WITH THE MACRO DETECTOR
Authors:   For the MACRO Collaboration. See Ref. for a complete list., SITTA MARIO
Published: April 2003

Massive rare particles have been searched for in the penetrating cosmic radiation using the MACRO apparatus at the Gran Sasso National Laboratories. Liquid scintillators, streamer tubes and nuclear track detectors have been used to search for magnetic monopoles (MMs). Based on no observation of such signals, stringent flux limits are established for MMs as slow as a few 10-5c. The methods based on the scintillator and on the nuclear track subdetectors were also applied to search for nuclearites. Preliminary results of the searches for charged Q-balls are also presented.
GROUP THEORY FACTORS FOR FEYNMAN DIAGRAMS
Authors: VAN RITBERGEN T. , SCHELLEKENS A. N. , VERMASEREN J. A. M.
Published: April 2003

We present algorithms for the group independent reduction of group theory factors of Feynman diagrams. We also give formulas and values for a large number of group invariants in which the group theory factors are expressed. This includes formulas for various contractions of symmetric invariant tensors, formulas and algorithms for the computation of characters and generalized Dynkin indices and trace identities. Tables of all Dynkin indices for all exceptional algebras are presented, as well as all trace identities to order equal to the dual Coxeter number. Further results are available through efficient computer algorithms.
SPIN-DEPENDENT DIFFERENTIAL CROSS SECTIONS AT SMALL ANGLES AT RHIC ENERGIES
Authors: AKCHURIN N. , GOLOSKOKOV S. V. , SELYUGIN O. V.
Published: April 2003

Spin-dependent pomeron effects are analyzed for elastic pp scattering and calculations for spin-dependent differential cross sections, analyzing power and double-spin correlation parameters are carried out for the energy range of the Relativistic Heavy Ion Collider (RHIC) at BNL. In this energy range, [Formula: see text], the structure of pomeron–proton coupling can be measured at RHIC with colliding polarized proton beams.
INDUCED PARITY VIOLATION ANOMALY FOR THE PROCA FIELD IN A THREE-DIMENSIONAL SPACE–TIME
Authors: BEZERRA DE MELLO E. R. , MOSTEPANENKO V. M.
Published: April 2003

In this paper we develop diagrammatic computations of spontaneous parity-violating anomalies for a complex massive vector field (Proca field) induced by its interaction with an electromagnetic field in a three-dimensional space–time. We also calculate the effective potential energy between two charged particles in Maxwell–Chern–Simons theory in a nonrelativistic limit.
ONE-INSTANTON PREDICTIONS OF A SEIBERG–WITTEN CURVE FROM M THEORY: THE SYMMETRIC REPRESENTATION OF SU(N)
Authors: ENNES ISABEL P. , RHEDIN HENRIC , NACULICH STEPHEN G. , SCHNITZER HOWARD J.
Published: April 2003

We consider N = 2 supersymmetric Yang–Mills theories in four dimensions with gauge group SU (N) for N larger than 2. Using the cubic curve for a matter hypermultiplet transforming in the symmetric representation, obtained from M theory by Landsteiner and Lopez, we calculate the prepotential up to the one-instanton correction. We treat the curve as being approximately hyperelliptic and perform a perturbation expansion for the Seiberg–Witten differential to get the one-instanton contribution. We find that it reproduces the correct result for one loop, and we obtain the prediction for that curve for the one-instanton correction term.
COMPOSITE TWO-HIGGS MODELS (GENERAL PART)
Authors: ANDRIANOV A. A. , ANDRIANOV V. A. , YUDICHEV V. L. , RODENBERG R.
Published: April 2003

Quark models with four-fermion interaction including derivatives of fields in the strong coupling regime are used to implement composite-Higgs extensions of the Standard Model. In this approach the dynamical breaking of chiral symmetry occurs in two (or more) channels (near polycritical values for coupling constants), giving rise to two (or more) composite Higgs doublets. Two types of models are built for which Flavor Changing Neutral Currents (FCNC) are naturally suppressed. In the first Model I the second Higgs doublet is regarded as a radial excitation of the first one. In the second Model II the quasilocal Yukawa interaction with Higgs doublets reduces at low energies to a conventional local one where each Higgs doublet couples to a definite charge current and its v.e.v. brings the mass either to up- or to down-components of fermion doublets. For the special configuration of four-fermion coupling constants the dynamical CP violation in the Higgs sector appears as a result of complexity of v.e.v. for Higgs doublets.
SO(10) UNIFICATION IN NONCOMMUTATIVE GEOMETRY REVISITED
Authors: WULKENHAAR RAIMAR
Published: April 2003

We investigate the SO(10) unification model in a Lie-algebraic formulation of noncommutative geometry. The SO(10) symmetry is broken by a 45-Higgs and the Majorana mass term for the right neutrinos (126-Higgs) to the standard model structure group. We study the case where the fermion masses are as general as possible, which leads to two 10-multiplets, four 120-multiplets and two additional 126-multiplets of Higgs fields. This Higgs structure differs considerably from the two Higgs multiplets 16 ⊗ 16* and 16c ⊗ 16* used by Chamseddine and Fröhlich. We find the usual tree level predictions of noncommutative geometry: [Formula: see text], [Formula: see text] and g2=g3 as well as mH≤ mt.
F THEORY VACUA IN FOUR DIMENSIONS AND TORIC THREEFOLDS
Authors: MOHRI KENJI
Published: April 2003

We investigate D=4, N=1 F theory models realized by type IIB string compactification on toric threefolds. Massless spectra, gauge symmetries, phase transitions associated with divisor contractions and flops, and nonperturbative superpotentials are analyzed using elementary toric methods.
THE RICCION, THE INSTANTON AND PRIMORDIAL INFLATION
Authors: SRIVASTAVA S. K.
Published: April 2003

It is shown that R2 and R3 terms dominate over the Einstein–Hilbert term in the gravitational action till the energy mass scale M ≥ 8.4 × 108 GeV. In the presence of these higher derivative terms, the action for Riccions is obtained with quartic self-interaction potential. It is interesting to see that the instanton solution for Riccions gives rise to primordial inflation without any phase transition or symmetry breaking.
DUALITY AND COSMOLOGICAL COMPACTIFICATION OF SUPERSTRINGS WITH UNBROKEN SUPERSYMMETRY
Authors: JASSAL H. K. , MUKHERJEE A. , SAXENA R. P.
Published: April 2003

The cosmological compactification of D=10, N=1 supergravity–super-Yang–Mills theory obtained from superstring theory is studied. The constraint of unbroken N=1 supersymmetry is imposed. A duality transformation is performed on the resulting consistency conditions. The original equations as well as the transformed equations are solved numerically to obtain new configurations with a nontrivial scale factor and a dynamical dilaton. It is shown that various classes of solutions are possible, which include cosmological solutions with no initial singularity.
DUALITY SYMMETRIES IN NONLINEAR GAUGE THEORIES
Authors: ARAKI MINAKO , TANII YOSHIAKI
Published: April 2003

Duality symmetries are discussed for nonlinear gauge theories of (n-1)th rank antisymmetric tensor fields in general even dimensions d=2n. When there are M field strengths and no scalar fields, the duality symmetry groups should be compact. We find conditions on the Lagrangian required by compact duality symmetries and show an example of duality invariant nonlinear theories. We also discuss how to enlarge the duality symmetries to noncompact groups by coupling scalar fields described by nonlinear sigma models.
INTERACTION OF NON-PARALLEL D1-BRANES
Authors: MATUSIS ALEC
Published: April 2003

We find the potential per unit length between two nonintersecting D1-branes as a function of their relative angle.
ANALYSIS OF SOLAR NEUTRINO FLUX FROM THE EXISTING SOLAR NEUTRINO DETECTORS
Authors: RAYCHAUDHURI PROBHAS
Published: April 2003

It is suggested that the experimental data on the solar neutrino flux as measured in the existing solar neutrino detectors (e.g. Homestake, Kamiokande II and III, Gallex and Sage) vary with the solar activity cycle to a very high level of statistical significance. We have applied the run test and the change point test to the nine sets of solar neutrino flux that have been generated by the Monte-Carlo simulation with production rate and background parameters that are typical of those in the actual Homestake experiment. Homestake solar neutrino flux data show anticorrelation with sunspot numbers from 1970 to February 1994 at a very high level of statistical significance. However, the Kamiokande solar neutrino flux data show correlation with the sunspot number data at a significant level. Again it is shown that out of nine Monte-Carlo-simulated data only three indicate a variation within the period from 1970 to February 1992, but these three Monte-Carlo-simulated solar neutrino flux data do not show significant anticorrelation with the sunspot number data. The solar neutrino flux data from Gallex and Sage show not only variation within the measurement period, i.e. from January 1990 to October 1995, but are also correlated with the sunspot numbers. The Kamiokande solar neutrino flux data not only show variation from January 1987 to February 1995 but are also correlated with the sunspot number data. The variation of solar neutrino flux data within the solar activity cycle and anticorrelation/correlation indicates that the solar activity cycle is due to the pulsating character of the nuclear energy generation inside the core of the sun.
EFFECTS OF NONSTANDARD INTERACTIONS FOR THE ENERGY SPECTRUM OF SECONDARY LEPTONS IN $e^+ e^-\to
t\bar t$
Authors: BRZEZIŃSKI LONGIN , GRZADKOWSKI BOHDAN , HIOKI ZENRŌ
Published: April 2003

The process of top-quark pair production followed by semileptonic decays at future high-energy e+ e- linear colliders is investigated as a possible test of physics beyond the Standard Model. Assuming the most general nonstandard forms for [Formula: see text], [Formula: see text] and Wtb couplings, the energy spectrum of the single lepton ℓ± and the energy correlation of ℓ+ and ℓ- emerging from the process [Formula: see text] are calculated. Expected precision of the nonstandard-parameter determination is estimated adopting the recently-proposed optimal method.
THE HEAT KERNEL IN CURVED SPACE IN TERMS OF CLASSICAL VARIABLES
Authors: MARTIN L. , MCKEON D. G. C.
Published: April 2003

Using functional methods introduced by Onofri, the heat kernel matrix element Mxy= for an elliptic operator H in curved space is unambiguously represented in terms of functional derivatives of an expression which solely involves classical variables. To illustrate how this can be used, the lowest order term in the Schwinger–DeWitt expansion for Mxx is computed.
ISRAEL–WILSON–PERJÉS SOLUTIONS IN HETEROTIC STRING THEORY
Authors: HERRERA-AGUILAR ALFREDO , KECHKIN OLEG
Published: April 2003

We present a simple algorithm to obtain solutions that generalize the Israel–Wilson–Perjés class for the low energy limit of heterotic string theory toroidally compactified from D=d+3 to three dimensions. A remarkable map existing between the Einstein–Maxwell (EM) theory and the theory under consideration allows us to solve directly the equations of motion making use of the matrix Ernst potentials connected with the coset matrix of heterotic string theory.1 For the particular case d=1 (if we put n=6, the resulting theory can be considered as the bosonic part of the action of D=4, N=4 supergravity) we obtain explicitly a dyonic solution in terms of one real 2×2-matrix harmonic function and 2n real constants (n being the number of Abelian vector fields). By studying the asymptotic behavior of the field configurations we define the charges of the system. They satisfy the Bogomol'nyi–Prasad–Sommerfield (BPS) bound.
SPINNING PARTICLES ON SPACELIKE HYPERSURFACES AND THEIR REST FRAME DESCRIPTION
Authors: BIGAZZI FRANCESCO , LUSANNA LUCA
Published: April 2003

A new spinning particle with a definite sign of the energy is defined on spacelike hypersurfaces after a critical discussion of the standard spinning particles. It is the pseudoclassical basis of the positive energy [Formula: see text] [or negative energy [Formula: see text]] part of the [Formula: see text] solutions of the Dirac equation. The study of the isolated system of N such spinning charged particles plus the electromagnetic field leads to their description in the rest frame Wigner-covariant instant form of dynamics on the Wigner hyperplanes orthogonal to the total four-momentum of the isolated system (when it is timelike). We find that on such hyperplanes these spinning particles have a nonminimal coupling only of the type "spin–magnetic field," like the nonrelativistic Pauli particles to which they tend in the nonrelativistic limit. The Lienard–Wiechert potentials associated with these charged spinning particles are found. Then, a comment is made on how to quantize the spinning particles respecting their fibered structure describing the spin structure.
COASTING COSMOLOGIES WITH TIME DEPENDENT COSMOLOGICAL CONSTANT
Authors: PIMENTEL LUIS O. , DIAZ-RIVERA LUZ M.
Published: April 2003

The effect of a time dependent cosmological constant is considered in a family of scalar-tensor theories. Friedmann–Robertson–Walker cosmological models for vacuum and perfect fluid matter are found. They have a linear expansion factor, the so-called coasting cosmology, the gravitational "constant" decreases inversely with time; that is these models satisfy the Dirac Hypotheses. The cosmological "constant" decreases inversely with the square of time, therefore we can have a very small value for it at present time.
ON THE BOUND STATES IN A NONLINEAR QUANTUM FIELD THEORY OF A SPINOR FIELD WITH HIGHER DERIVATIVES
Authors: MITOV A. D. , STOILOV M. N. , STOYANOV D. Ts.
Published: April 2003

We consider a model with higher derivatives for a spinor field with Fermi-type self-interaction. The problem of two-particle bound states is investigated with the help of the Bethe–Salpeter equation. It is shown that a scalar bound state exists when the coupling constant has a very finely tuned magnitude.
FERMION-SECTOR FRUSTRATED SU(4) AS A PREONIC PRECURSOR OF THE STANDARD MODEL
Authors: ADLER STEPHEN L.
Published: April 2003

We give a model for composite quarks and leptons based on the semisimple gauge group SU(4), with the preons in the 10 representation; this choice of gauge gluon and preon multiplets is motivated by the possibility of embedding them in an N=6 supergravity multiplet, with the preons and antipreons both in the 20 of SU(6). Hypercolor singlets are forbidden in the fermionic sector of this theory; we propose that the SU(4) symmetry spontaneously breaks to SU (3)× U (1), with the binding of triality nonzero preons and gluons into composites, and with the formation of a color singlet condensate that breaks the initial Z12 vacuum symmetry to Z6. The spin ½ fermionic composites have the triality structure of a quark–lepton family, and the initial Z12 symmetry implies that there are six massless families, which mix to give three distinct families below the scale of the condensate. The spin 1 triality zero composites of the color triplet SU(4) gluons, when coupled to the condensate and with the color singlet representation of the 10 acting as a doorway state, lead to weak interactions of the fermionic composites through an SU(2) gauge algebra. The initial Z12 symmetry implies that this SU(2) gauge algebra structure is doubled, which in turn permits the corresponding independent gauge bosons to couple to chiral components of the composite fermions. Since the U(1) couples to the 10 representation as B-L, an effective SU (2)L× SU (2)R × U (1)B-L electroweak theory arises at the condensate scale, with all composites having the correct electric charge structure. Assuming a mechanism for forming composite Higgs bosons, the Z12→ Z6 symmetry breaking chain implies that below the condensate scale there can be two sets of discrete chiral Z6 triplets of Higgs doublets, as required by a phenomenological model for the CKM matrix that we have analyzed in detail elsewhere. A renormalization group analysis of the SU(4) model shows that the conversion by binding of one 10 of SU(4) to 12 triplets of SU(3) can give a very large, calculable hierarchy ratio between the SU(4) and the hadronic mass scales.
MULTIFRACTALITY AND INTERMITTENCY STUDY OF ULTRARELATIVISTIC 32S–AgBr AND 16O–AgBr INTERACTIONS: FURTHER EVIDENCE OF A NONTHERMAL PHASE TRANSITION
Authors: GHOSH DIPAK , DEB ARGHA , CHATTOPADHYAY RINI , JAFRY ABDUL KAYUM , LAHIRI MADHUMITA , BISWAS BISWANATH , PURKAIT KRISHNADAS , DAS SUSOBHAN , ROYCHOUDHURY JAYANTA , DAS SUNIL , (SARKAR) SHARMILA ROY
Published: April 2003

This paper presents an analysis of medium energy target protons emitted in 32 S–AgBr interactions at 200 AGeV and 16 O–AgBr interactions at 60 AGeV in terms of scaled factorial moments up to the fifth order. The study gives evidence of a nonthermal phase transition in the 32 S–AgBr data. The multifractal nature of the particle spectra has also been observed using a new method proposed by F. Takagi.
THE BOUND STATE EQUATION FOR TWO GLUONS AND ITS SOLUTION
Authors: CUI J. Y. , WU J. M.
Published: April 2003

We derive the bound state equation for two gluons in relativistic quantum field theory, i.e. the Bethe–Salpeter (BS) equation for two gluons. To solve it, we choose the kernel as the sum of a one-gluon exchange potential, a contact interaction and a linear confining potential. Under instantaneous approximation, this BS equation is solved numerically. The spectrum and the BS wave function of the glueballs are obtained in this framework. The numerical results are in agreement with that of recent lattice calculation.
CONTINUOUS APPROXIMATION OF BINOMIAL LATTICES
Authors: GRASSI V. , LEO R. A. , SOLIANI G. , SOLOMBRINO L.
Published: April 2003

A systematic analysis of a continuous version of a binomial lattice, containing a real parameter γ and covering the Toda field equation as γ→∞, is carried out in the framework of group theory. The symmetry algebra of the equation is derived. Reductions by one-dimensional and two-dimensional subalgebras of the symmetry algebra and their corresponding subgroups, yield notable field equations in lower dimensions whose solutions allow us to find exact solutions to the original equation. Some reduced equations turn out to be related to potentials of physical interest, such as the Fermi–Pasta–Ulam and the Killingbeck potentials, and others. An instantonlike approximate solution is also obtained which reproduces the Eguchi–Hanson instanton configuration for γ→∞. Furthermore, the equation under consideration is extended to n+1 dimensions. A spherically symmetric form of this equation, studied by means of the symmetry approach, provides conformally invariant classes of field equations comprising remarkable special cases. One of these (n=4) enables us to establish a connection with the Euclidean Yang–Mills equations, another appears in the context of Differential Geometry in relation to the so-called Yamabe problem. All the properties of the reduced equations are shared by the spherically symmetric generalized field equation.
IRREDUCIBLE HAMILTONIAN APPROACH TO THE FREEDMAN–TOWNSEND MODEL
Authors: BIZDADEA C. , NEGRU I. , SALIU S. O.
Published: April 2003

The irreducible BRST symmetry for the Freedman–Townsend model is derived. In addition, a comparison with the standard reducible approach is made.
THE INCOMPLETENESS OF KRUSKAL–SZEKERES SPACETIME
Authors: GAUTREAU RONALD
Published: April 2003

Novikov has developed a reference system built around times measured by radially moving geodesic clocks that is equivalent to Kruskal–Szekeres coordinates. From analysis of the construction of Novikov's reference system, I give arguments showing that the reference system is not maximally extended, as is commonly reported in the literature. On both Novikov and Kruskal–Szekeres spacetime diagrams, the left-hand side, corresponding to negative values of the spatial coordinate, should not be included when describing a physical spacetime. In turn, this means we have to rethink widely-accepted concepts such as black and white holes that arise from the usual picture of a maximally-extended Kruskal–Szekeres spacetime.
FUSION OF STRINGS VS. PERCOLATION AND THE TRANSITION TO THE QUARK–GLUON PLASMA
Authors: BRAUN M. A. , PAJARES C. , RANFT J.
Published: April 2003

In most of the models of hadronic collisions, the number of exchanged color strings grows with energy and atomic numbers of the projectile and target. At high string densities interaction between them becomes important, which should melt them into the quark–gluon plasma state in the end. It is shown that under certain reasonable assumptions about the string interaction, a phase transition to the quark–gluon plasma indeed takes place in the system of many color strings. It may be of the first or second order, depending on the particular mechanism of the interaction. The critical string density is about unity in both cases. In the latter case the percolation of strings occurs above the critical density. The critical density may have already been reached in central Pb–Pb collisions at 158A GeV.
INFRARED DIVERGENCE IN QED3 AT FINITE TEMPERATURE
Authors: LEE DOMINIC , METIKAS GEORGIOS
Published: April 2003

We consider various ways of treating the infrared divergence which appears in the dynamically generated fermion mass, when the transverse part of the photon propagator in N flavour QED 3 at finite temperature is included in the Matsubara formalism. This divergence is likely to be an artifact of taking into account only the leading order term in the [Formula: see text] expansion when we calculate the photon propagator and is handled here phenomenologically by means of an infrared cutoff. Inserting both the longitudinal and the transverse part of the photon propagator in the Schwinger–Dyson equation, we find the dependence of the dynamically generated fermion mass on the temperature and the cutoff parameters. It turns out that consistency with certain statistical physics arguments imposes conditions on the cutoff parameters. For parameters in the allowed range of values we find that the ratio r=2* Mass (T=0)/critical temperature is approximately 6, consistent with previous calculations which neglected the transverse photon contribution.
COLLECTIVE AND RELATIVE VARIABLES FOR A CLASSICAL KLEIN–GORDON FIELD
Authors: LONGHI G. , MATERASSI M.
Published: April 2003

In this paper a set of canonical collective variables is defined for a classical Klein–Gordon field and the problem of the definition of a set of canonical relative variables is discussed.

This last point is approached by means of a harmonic analysis in momentum space. This analysis shows that the relative variables can be defined if certain conditions are fulfilled by the field configurations.

These conditions are expressed by the vanishing of a set of conserved quantities, referred to as supertranslations since as canonical observables they generate a set of canonical transformations whose algebra is the same as that which arises in the study of the asymptotic behavior of the metric of an isolated system in General Relativity.9
COULOMB INTERACTION BETWEEN TWO CHARGED PARTICLES ON A CONE
Authors: DE S. BARBOSA A. , BEZERRA DE MELLO E. R. , BEZERRA V. B.
Published: April 2003

In this paper we investigate the dynamics of two charged particles on conical space in the context of nonrelativistic quantum mechanics. This is a difficult analytic problem, different from the flat case, and for this reason only the approximation method provides some information about this system. We also analyze the behavior of a point electric dipole on this background space and show that it experiences a repulsive self-force of topological origin.
GENERALIZED HYBRID DERIVATIVE COUPLING MODEL WITH DILATON FIELD TO STUDY PHASE TRANSITION FROM NUCLEAR MATTER TO QUARK MATTER
Authors: MALAKAR BINAY , SARKAR SASABINDU
Published: April 2003

The properties of isospin symmetric nuclear matter and its phase transition to quark matter at zero temperature have been investigated in the framework of generalized hybrid derivative coupling model by including the contribution of dilation field. We have compared the results of different models in presence and in absence of dilaton field. The effect of dilaton field becomes prominent as the density increases. The most striking feature of this work is that in presence of dilaton field the vector meson contribution to total energy density is approximately proportional to ρ4/3 instead of ρ2 when the density ρ is extremely high.
TUNNELING AND NUCLEATION RATE IN THE $(\frac{\lambda}{4!} \phi^4 +\frac{\sigma}{6!} \phi^6)_3$ MODEL
Authors: FLORES GABRIEL H. , SVAITER N. F. , RAMOS RUDNEI O.
Published: April 2003

We evaluate both the vacuum decay rate at zero temperature and the finite temperature nucleation rate for the [Formula: see text] model. Using the thin-wall approximation, we obtain the bounce solution for the model and we were also able to give the approximate eigenvalue equations for the bounce.
REISSNER–NORDSTROM BLACK HOLES AND STRINGS WITH RESCALED TENSION
Authors: HALYO EDI
Published: April 2003

We show that extreme and nonextreme Reissner–Nordstrom black holes in five dimensions can be described by closed fundamental strings with two charges in a magnetic five-brane. Due to the five-brane background, the string oscillator number and tension are rescaled whereas the mass remains fixed. The black hole mass is given by the sum of the five-brane and string masses. Its entropy however is given by only that of the string with the tension rescaling taken into account. We also show that the emission of a low energy scalar from the slightly nonextreme string matches the Hawking radiation expected from the black hole.
REDUCTION PROBLEM FOR FOUR WAVE INTERACTION AND THE CLASSICAL r MATRIX
Authors: CHOUDHURY A. GHOSE , CHOWDHURY A. ROY
Published: April 2003

Integrable nonlinear partial differential equations, describing the process of four-wave interaction are derived by means of the reduction procedure. Explicit multisoliton solutions are constructed by formulating a degenerate Reimann–Hilbert problem; while the analytic structure of the Lax operators in the complex plane is used to deduce general Backlund transformations. Conservation laws are derived and the Hamiltonian structure is used to deduce a new form of the classical r matrix, which in turn is used to prove the integrability of our model in case of nontrivial boundary conditions. Lastly the corresponding Quantum R-matrix is derived in the lattice approximation and is seen to be related to an eight-vertex model.
ON MASSIVE VECTOR BOSONS AND ABELIAN MAGNETIC MONOPOLES IN D = (3 + 1): A POSSIBLE WAY TO QUANTIZE THE TOPOLOGICAL MASS PARAMETER
Authors: MOURA-MELO WINDER A. , PANZA N. , HELAYËL-NETO J. A.
Published: April 2003

An Abelian gauge model, with vector and two-form potential fields linked by a topological mass term mixing the two Abelian factors, is shown to exhibit Dirac-like magnetic monopoles in the presence of a matter background. In addition, considering a "nonminimal coupling" between the fermions and the tensor fields, we obtain a generalized quantization condition that involves, among others, the topological mass parameter. Also, it is explicitly shown that one-loop (finite) corrections do not shift the value of such a mass parameter.
YUKAWA COUPLING CONTRIBUTION TO MAGNETIC FIELD INDUCED DYNAMICAL MASS
Authors: FERRER EFRAIN J. , DE LA INCERA VIVIAN
Published: April 2003

By solving the gap equation in the quenched, ladder approximation for an Abelian gauge model with Yukawa interaction in the presence of a constant magnetic field, we show that the Yukawa interactions enhance the dynamical generation of fermion mass. The theory is then studied at finite temperature, where we prove that the critical magnetic field, required for the mass generation to be important at temperatures comparable to the electroweak critical temperature, can be substantially decreased due to the Yukawa coupling.
COHOMOLOGICAL FIELD THEORY APPROACH TO MATRIX STRINGS
Authors: SUGINO FUMIHIKO
Published: April 2003

In this paper we consider IIA and IIB matrix string theories which are defined by two-dimensional and three-dimensional super Yang–Mills theory with the maximal supersymmetry, respectively. We exactly compute the partition function of both of the theories by mapping to a cohomological field theory. Our result for the IIA matrix string theory coincides with the result obtained in the infrared limit by Kostov and Vanhove, and thus gives a proof of the exact quasiclassics conjectured by them. Further, our result for the IIB matrix string theory coincides with the exact result of IKKT model by Moore, Nekrasov and Shatashvili. It may be an evidence of the equivalence between the two distinct IIB matrix models arising from different roots.
DESCENT RELATIONS AMONG BOSONIC D-BRANES
Authors: SEN ASHOKE
Published: April 2003

We show that the tachyonic kink solution on a pair of D-p-branes in the bosonic string theory can be identified with the D-(p-1)-brane of the same theory. We also speculate on the possibility of obtaining the D-(p-1)-brane as a tachyonic lump on a single D-p-brane. We suggest a possible reinterpretation of the first result which unifies these two apparently different descriptions of the D-(p-1)-brane.
HIDDEN SYMMETRIES IN QUANTUM FIELD THEORIES FROM EXTENDED COMPLEX NUMBERS
Authors: BASEILHAC PASCAL
Published: April 2003

The two-dimensional space–time sine–Gordon field theory is extended algebraically within the n-dimensional space of extended complex numbers. This field theory is constructed in terms of an adapted extension of standard vertex operators. A whole set of nonlocal conserved charges is constructed and studied in this framework. Thereby, an algebraic nonperturbative description is possible for this n-1 parameters family of quantum field theories. Known results are obtained for specific values of the parameters, especially in relation to affine Toda field theories. Different (dual)-models can then be described in this formalism.
THE EXCLUSIVE $\bar B \to\pi e^+ e^-$ AND $\bar B\to \rho e^+ e^-$ DECAYS IN THE TWO HIGGS DOUBLET MODEL WITH FLAVOR CHANGING NEUTRAL CURRENTS
Authors: ILTAN E. O.
Published: April 2003

We present the leading logarithmic QCD corrections to the matrix element of the decay b→de+e- in the two Higgs doublet model with tree level flavor changing currents (model III). We continue studying the differential branching ratio and the CP-violating asymmetry for the exclusive decays B→πe+e- and B→ρe+e- and analysing the dependencies of these quantities on the selected model III parameters, ξU,D, including the leading logarithmic QCD corrections. Further, we present the forward–backward asymmetry of dileptons for the decay B→ρe+e- and discuss the dependencies to the model III parameters. We observe that there is a possibility to enhance the branching ratios and suppress the CP-violating effects for both decays in the framework of the model III. Therefore, the measurements of these quantities will be an efficient tool to search the new physics beyond the SM.
THE q-BOSON REALIZATIONS OF THE QUANTUM GROUP Uq(Cn)
Authors: BURDÍK Č. , NAVRÁTIL O.
Published: April 2003

We give explicit realization for the quantum enveloping algebras Uq(Cn). To obtain recurrence formulae we extend simply the algebra Uq(Cn) to [Formula: see text], for which Uq(Cn) is a subalgebra. In these formulae the generators of the algebra are expressed by means of 2n-1 canonical q-boson pairs and one auxiliary representation of [Formula: see text].
SYMPLECTIC MATRIX, GAUGE INVARIANCE AND DIRAC BRACKETS FOR SUPER-QED
Authors: ALVES D. T. , CHEB-TERRAB E. S.
Published: April 2003

The calculation of Dirac brackets (DB) using a symplectic matrix approach but in a Hamiltonian framework is discussed, and the calculation of the DB for the supersymmetric extension of QED (super-QED) is shown. The relation between the zero-mode of the pre-symplectic matrix and the gauge transformations admitted by the model is verified. A general prescription to construct Lagrangians linear in the velocities is also presented.
3D–4D INTERLINKAGE OF qqq WAVE FUNCTIONS UNDER 3D SUPPORT FOR PAIRWISE BETHE–SALPETER KERNELS
Authors: MITRA A. N.
Published: April 2003

Using the method of Green functions within the framework of a Bethe–Salpeter formalism characterized by a pairwise qq interaction under the Markov–Yukawa transversality principle (MYTP) which gives Lorentz-covariant 3D support to the BS kernel, the 4D BS amplitude for three identical spinless quarks is reconstructed from the corresponding 3D quantities which satisfy a fully connected 3D BSE. This result is a three-body generalization of a similar 3D–4D interlinkage for the corresponding two-body wave functions found earlier under identical conditions of a Lorentz-covariant 3D support to the corresponding BS kernel, ("CIA" for short), for the [Formula: see text] interaction. (The generalization from spinless to fermion quarks is straightforward).

To set "CIA" for 3D kernel support in the context of contemporary approaches to the qqq baryon problem, a model scalar 4D qqq BSE with pairwise contact interactions simulating the NJL–Faddeev equations, is worked out fully and compared with the "CIA" vertex function which reduces exactly to the 4D NJL–Faddeev form in the limit of zero spatial range. This consistency check is part of a detailed accounting of the CIA vertex structure whose physical motivation stems from the role of spectroscopy when considered as an integral part of any QCD-motivated dynamical investigation.
p-BRANES, POISSON-SIGMA MODELS AND EMBEDDING APPROACH TO (p+1)-DIMENSIONAL GRAVITY
Authors: BANDOS IGOR A. , KUMMER WOLFGANG
Published: April 2003

A generalization of the embedding approach for d-dimensional gravity based upon p-brane theories is proposed. We prove that the D-dimensional p-brane coupled to an antisymmetric tensor field of rank (p+1) provides the dynamical basis for the description of d=(p+1)-dimensional gravity in the isometric embedding formalism. By that we mean that the equations of motion following from this action describe any (p+1)-dimensional space–time (at least locally) once the antisymmetric tensor field is chosen appropriately. "Physical" matter appears in such an approach as a manifestation of a D-dimensional antisymmetric tensor (generalized Kalb–Ramond) background.

For the simplest case, the Lorentz harmonic formulation of the bosonic string in a Kalb–Ramond background and its relation to a first order Einstein–Cartan approach for (d=2)-dimensional gravity is analyzed in some detail. We show that a general Poisson-sigma model structure emerges in this case. For the minimal choice of a free D=3 string an interesting "dual" formulation is found which has the structure of a Jackiw–Teitelboim theory, coupled minimally to a massive scalar field.

Our approach is intended to serve as a preparation for the study of d-dimensional supergravity theory, either starting from the generalized action of free supersymmetric (d-1)-branes or D(d-1)-branes, or from the corresponding geometric equations ("rheotropic" conditions).
INTERACTION OF TACHYONS WITH MATTER
Authors: TOMASCHITZ ROMAN
Published: April 2003

A new interaction mechanism of superluminal particles with matter is suggested. Tachyons are described by a real Proca field with negative mass square, coupled to a current of subluminal matter. The potential of a static point source in this field theory is a damped periodic function with 1/r-decay. We treat this potential as a perturbation of the Coulomb potential, and study its effects on cross-sections and energy levels. In the limit of large impact parameter, the periodicity of the potential has a pronounced effect on the classical cross-section, which gets singular at the accumulating extrema of the scattering angle. In this limit we define the cross-section wave mechanically, by semiclassical rainbow scattering. The impact of the tachyon potential on the energy levels of hydrogen and hydrogenic ions is calculated by means of Bohr–Sommerfeld quantization. Estimates for the tachyon mass (3 keV) and the coupling constant of the tachyon potential are derived on the basis of high-precision Lamb shift measurements.
KNOWLEDGE-BASED SHAPE-FROM-SHADING
Authors: BARNES NICK , LIU ZHI-QIANG
Published: April 2003

In this paper, we study the problem of recovering approximate shape from the shading of a three-dimensional object in a single image when knowledge about the object is available. The application of knowledge-based methods to low-level image processing tasks will help overcome problems that arise from processing images using a pixel-based approach. Shape-from-shading has generally been approached by precognitive vision methods where a standard operator is applied to the image based on assumptions about the imaging process and generic properties of what appears. This paper explores some advantages of applying knowledge and hypotheses about what appears in the image. The knowledge and hypotheses used here come from domain knowledge and edge-matching. Specifically, we are able to find solutions to some problems that cannot be solved by other methods and gain advantages in terms of computation speed over similar approaches. Further, we can fully automate the derivation of the approximate shape of an object. This paper demonstrates the efficacy of using knowledge in the basic operation of an early vision operator, and so introduces a new paradigm for computer vision that may be applied to other early vision operators.
RECIPROCAL-WEDGE TRANSFORM IN ACTIVE STEREO
Authors: LI ZE-NIAN , TONG FRANK
Published: April 2003

The Reciprocal-Wedge Transform (RWT) facilitates space-variant image representation. In this paper a V-plane projection method is presented as a model for imaging using the RWT. It is then shown that space-variant sensing with this new RWT imaging model is suitable for fixation control in active stereo that exhibits vergence and versional eye movements and scanpath behaviors. A computational interpretation of stereo fusion in relation to disparity limit in space-variant imagery leads to the development of a computational model for binocular fixation. The vergence-version movement sequence is implemented as an effective fixation mechanism using the RWT imaging. A fixation system is presented to show the various modules of camera control, vergence and version.
A NOVEL FORWARD–BACKWARD SMOOTHING-BASED LEARNING SUBSPACE METHOD FOR RECOGNITION OF RADAR TARGETS
Authors: HUANG DE-SHUANG
Published: April 2003

This paper proposes a novel Forward–Backward Smoothing-Based Learning Subspace Method (FBSLSM), which can satisfy the equirements of being insensitive to the order of presentation of the training samples, and is of faster convergence speed. This method is applied to the recognition of simulating High Resolution Radar (HRR) targets (two for ships, one for chaff). Moreover, for recognition of HRR targets, a new selection method of subspace dimensionality is given. The computer simulating experiments show that the corresponding performance of proposed FBSLSM such as rate of correct recognition and convergence speed is better than that of the ALSM presented by Oja.
GENERATING 2-D SPACE MAPS FROM UNKNOWN ENVIRONMENTS
Authors: BOURBAKIS NIKOLAOS G.
Published: April 2003

This paper deals with the development of 2-D space maps during navigation in unknown environments, by synthesizing the shapes of consecutive free spaces. Each shape extracted from each current-free navigation space is represented by attributed graphs. Thus, the synthesis of the shapes is based on the synthesis of graphs for the generation of new graph forms that represent the new shape traveled by an autonomous robot. Illustrative examples from a space with obstacles are presented.
A FAST RULE-BASED PARAMETER FREE DISCRETE HOUGH TRANSFORM
Authors: GENSWEIN B. M. A. , YANG YEE-HONG
Published: April 2003

This paper introduces a new discrete Hough transform, DHT, that pre-computes discrete line information (rules) and uses this information to detect line segments in the image. Pre-computing line information removes the need for run-time line calculations and the associated parameters. The proposed approach does not depend on the parameterization of a straight line and is formulated based on the discrete domain. This new DHT is compared with selected existing techniques to demonstrate the large reduction in computation time achieved by this new approach, while not sacrificing accuracy.
BOUNDED RATIONALITY AND ALTERNATING-OFFER BARGAINING
Authors: MAULEON ANA , VANNETELBOSCH VINCENT J.
Published: April 2003

One form of bounded rationality is a breakdown in the commonality of the knowledge that the players are rational. In Rubinstein's two-person alternating-offer bargaining game, assuming time preferences with constant discount factors, common knowledge of rationality is necessary for an agreement on a subgame perfect equilibrium (SPE) partition to be reached (if ever). In this note, assuming time preferences with constant costs of delay, we show that common knowledge of rationality is not necessary to reach always an agreement on a SPE partition. This result is robust to a generalisation, time preferences with constant discount factors and costs of delay, if the players are sufficiently patient.
SOLUTION SURFACES AND GENERALIZED PATHS IN NON-LINEAR STRUCTURAL MECHANICS
Authors: ERIKSSON ANDERS , PACOSTE COSTIN
Published: April 2003

The paper describes how quasi-static, conservative instability problems can be seen in a multi-dimensional context, and how one- and two-dimensional solution manifolds can reveal further information on the structural response. The discussed viewpoint can be seen as the natural extension of the common one-dimensional path-following methods, when additional variables are introduced to describe the parameter dependence in structural response, instability analyses and optimization. The paper describes the general setting of the generalized equilibrium problems, and discusses their numerical treatment for the cases of resulting one- and two-dimensional solution sets. Numerical examples show some applications of these models, and describe the possibilities and properties of the obtained solution sets.
CONTENT-BASED RETRIEVAL OF MULTIMEDIA INFORMATION
Authors: FENG DAGAN (DAVID)
Published: April 2003

The recent information explosion has led to massively increased demand for multimedia data storage and retrieval techniques. Content-based retrieval is an important alternative and complement to the traditional keyword-based searching for multimedia data and can greatly enhance information management. For the last ten years, the Biomedical and Multimedia Information Technology (BMIT) Group and recently the Center for Multimedia Signal Processing (CMSP) have conducted systematic studies and research activities on this topic. Some of the works relating to content-based image/video retrieval and their applications are briefly presented in this paper.