bluuebunny/crossref_metadata_2025 huggingface dataset:
CARRIER CAPTURE IN SEMICONDUCTOR QUANTUM WELL LASERS: A QUANTUM TRANSPORT ANALYSIS
Authors: REGISTER LEONARD F.
Published: May 2003

A quantum transport-based analysis of the essential physics of carrier capture in semiconductor quantum wells is presented. First, the past progression of models of carrier capture by quantum wells is briefly reviewed. Then carrier capture is modeled using the Schrödinger Equation Monte Carlo (SEMC) quantum transport simulator. In addition to reproducing familiar effects, these simulations exhibit significant effects associated with partial phase-coherence of the carrier wave-function across the well which cannot be modeled via classical or perturbative Golden Rule calculations, and address fundamental transport limitations often overlooked in Golden Rule calculations. However, this analysis also points to simple changes that could significantly improve, although not perfect, the treatment of carrier capture via these latter more conventional approaches.
STRUCTURAL AND ELECTRONIC PROPERTIES OF CARBON NANOTUBES
Authors: ERKOÇ ŞAKIR
Published: May 2003

The structural and electronic properties of optimized open-ended single-wall carbon nanotubes with zigzag geometry have been investigated. The calculations were performed using molecular mechanics, extended Hückel, and AM1–RHF semiempirical molecular orbital methods. It has been found that the density of states of the zigzag model is sensitive to the tube size and changes as the tube length increases. On the other hand the energetics of the tube shows an almost linear dependence to the tube length, and a converging characteristics with respect to the number of hexagons forming the tube.
PHASE TRANSITION OF A MODEL OF FLUID MEMBRANE
Authors: KOIBUCHI HIROSHI , YAMADA MITSURU
Published: May 2003

A model of fluid membrane, which is not self-avoiding, such as two-dimensional spherical random surface is studied by using Monte Carlo simulation. Spherical surfaces in R3 are discretized by piecewise linear triangle. Dynamical variables are the positions X of the vertices and the triangulation g. The action of the model is sum of area energy and bending energy times bending rigidity b. The bending energy and the specific heat are measured, and the critical exponents of the phase transitions are obtained by a finite-size scaling technique. We find that our model of fluid membrane undergoes a second order phase transition.
A COMPARATIVE STUDY OF EMPIRICAL POTENTIAL ENERGY FUNCTIONS: APPLICATIONS TO CLUSTERS
Authors: GÜNEŞ P. , ŞİMŞEK S. , ERKOÇ S.
Published: May 2003

We have made a comparative study for the empirical potential energy functions proposed and parametrized for coinacal metals, namely Cu, Ag, and Au. We have considered four different potential energy functions, and applied them to investigate the structural properties and energetics of clusters of the elements considered.
THE EFFECT OF PBC ON THE SIMULATION OF NANOTUBES
Authors: ERKOÇ ŞAKIR
Published: May 2003

The effect of the periodic boundary condition (PBC) on the structure and energetics of nanotubes has been investigated by performing molecular-dynamics computer simulation. Calculations have been realized by using an empirical many-body potential energy function for carbon. A single-wall carbon nanotube has been considered in the simulations. It has been found that the periodic boundary condition has no effect at low temperature (1 K), however, it plays an important role even at intermediate temperature (300 K).
DYNAMIC SCALING FOR FIRST-ORDER PHASE TRANSITIONS
Authors: ÖZOĞUZ BANU EBRU , GÜNDÜÇ YIĞIT , AYDIN MERAL
Published: May 2003

The critical behavior in short time dynamics for the q = 6 and 7 state Potts models in two-dimensions is investigated. It is shown that dynamic finite-size scaling exists for first-order phase transitions.
PARALLELIZATION AND IMPLEMENTATION OF THE NOABL PROGRAM ON CRAY T3E PARALLEL MACHINE
Authors: MASTRANGELO V. , MEHILLI I.
Published: May 2003

This paper presents the parallelization of the NOABL program and its implementation on CRAY T3E parallel machine. The NOABL program is utilized to simulate windfield over complex terrain. This program runs on a processor grid (from 2 to 50 processors). The results obtained, show the interest of parallelizing this program and the SLOR method.
COMMENTS ON SOME EXTINCTION MODELS
Authors: AHMED E. , ELETTREBY M. F. , AGIZA H. N.
Published: May 2003

It is shown that the parallel Bak–Sneppen model proposed by Sornette and Dornic can be used as an extinction model. Yet, to include the environmental effect, it may be better to augment it by a coherent noise rule. The resulting model simulates both the evolution and the extinction phenomena.
IMPLEMENTATION OF C⋆ BOUNDARY CONDITIONS IN THE HYBRID MONTE CARLO ALGORITHM
Authors: CARMONA JOSÉ MANUEL , D'ELIA MASSIMO , DI GIACOMO ADRIANO , LUCINI BIAGIO
Published: May 2003

In the study of QCD dynamics, C⋆ boundary conditions are physically relevant in certain cases. In this paper, we study the implementation of these boundary conditions in the lattice formulation of full QCD with staggered fermions. In particular, we show that the usual even-odd partition trick to avoid the redoubling of the fermion matrix is still valid in this case. We give an explicit implementation of these boundary conditions for the Hybrid Monte Carlo algorithm.
SINGLE-STEP QUANTUM SEARCH USING PROBLEM STRUCTURE
Authors: HOGG TAD
Published: May 2003

The structure of satisfiability problems is used to improve search algorithms for quantum computers and to reduce their required coherence times by using only a single coherent evaluation of problem properties. The structure of random k-SAT allows the determination of the asymptotic average behavior of these algorithms, showing they improve on the quantum algorithms, such as amplitude amplification, that ignore detailed problem structure but remain exponential for hard problem instances. Compared to good classical methods, the algorithm performs better, on average, for weakly and highly constrained problems, but worse for hard cases. The analytic techniques introduced here apply also to other quantum algorithms, supplementing the limited evaluation possible with classical simulations, and showing how quantum computing can use the ensemble properties of NP search problems.
CORRELATED RANDOM WALKS WITH A FINITE MEMORY RANGE
Authors: BIDAUX ROGER , BOCCARA NINO
Published: May 2003

We study a family of correlated one-dimensional random walks with a finite memory range M. These walks are extensions of the Taylor's walk as investigated by Goldstein, which has a memory range equal to one. At each step, with a probability p, the random walker moves either to the right or to the left with equal probabilities, or with a probability q = 1 -p performs a move, which is a stochastic Boolean function of the M previous steps. We first derive the most general form of this stochastic Boolean function, and study some typical cases which ensure that the average value  of the walker's location after n steps is zero for all values of n. In each case, using a matrix technique, we provide a general method for constructing the generating function of the probability distribution of Rn; we also establish directly an exact analytic expression for the step–step correlations and the variance [Formula: see text] of the walk. From the expression of [Formula: see text], which is not straightforward to derive from the probability distribution, we show that, for n approaching infinity, the variance of any of these walks behaves as n, provided p > 0. Moreover, in many cases, for a very small fixed value of p, the variance exhibits a crossover phenomenon as n increases from a not too large value. The crossover takes place for values of n around 1/p. This feature may mimic the existence of a nontrivial Hurst exponent, and induce a misleading analysis of numerical data issued from mathematical or natural sciences experiments.
OPTIMIZATION OF PRODUCTION PLANNING PROBLEMS — A CASE STUDY FOR ASSEMBLY LINES
Authors: SCHNEIDER JOHANNES , BRITZE JÜRGEN , EBERSBACH ANJA , MORGENSTERN INGO , PUCHTA MARKUS
Published: May 2003

For a few years, Simulated Annealing (SA)1 and related Monte Carlo optimization algorithms like Threshold Accepting (TA)2 have become a useful means for optimizing various kinds of economic problems, like the Traveling Salesman Problem (TSP). In this paper, we concentrate on the production processes themselves because most costs are thereby incurred, such that a small relative improvement can lead to large savings. We will present an application of these physical optimization algorithms for a certain type of assembly lines which can be transferred to a TSP with additional constraints.
OPINION EVOLUTION IN CLOSED COMMUNITY
Authors: SZNAJD-WERON KATARZYNA , SZNAJD JÓZEF
Published: May 2003

A simple Ising spin model which can describe a mechanism of making a decision in a closed community is proposed. It is shown via standard Monte Carlo simulations that very simple rules lead to rather complicated dynamics and to a power law in the decision time distribution. It is found that a closed community has to evolve either to a dictatorship or a stalemate state (inability to take any common decision). A common decision can be taken in a "democratic way" only by an open community.
ECONOPHYSICS — A NEW AREA FOR COMPUTATIONAL STATISTICAL PHYSICS?
Authors: STAUFFER DIETRICH
Published: May 2003

A review is given on some recent applications of computational statistical physics methods to finance problems like the stock market.
COMPUTER SIMULATION OF PROFILES OF INTERFACES BETWEEN COEXISTING PHASES: DO WE UNDERSTAND THEIR FINITE SIZE EFFECTS?
Authors: BINDER KURT , MÜLLER MARCUS
Published: May 2003

Interfaces between coexisting phases are very common in condensed matter physics, and thus many simulations attempt to characterize their properties, in particular, the interfacial tension and the interfacial profile. However, while theory usually deals with the "intrinsic profile", the latter is not a straightforward output of a simulation: The actual profile (observed in simulations and/or experiments!) is broadened by lateral fluctuations. Therefore, in the usual simulation geometry of L × L × L (in three dimensions), where one chooses suitable boundary conditions to stabilize one or two interfaces of (minimal) area L × L, the profile (and in particular the interfacial width) depends on both linear dimensions L and D (parallel and perpendicular to the interface). Choosing recent simulations of interfaces between coexisting phases of unmixed binary polymer mixtures as an example, we show that this interfacial broadening is not a small correction, but has pronounced effects; for a reliable data analysis, it is (unfortunately!) necessary to vary L and D over a wide range. We present counterexamples to the widespread belief that for small linear dimensions, the intrinsic profile is straightforwardly recovered and speculate about conditions where this belief may be valid.
AN EMBEDDED RUNGE–KUTTA METHOD WITH PHASE-LAG OF ORDER INFINITY FOR THE NUMERICAL SOLUTION OF THE SCHRÖDINGER EQUATION
Authors: SIMOS T. E.
Published: May 2003

An embedded Runge–Kutta method with phase-lag of order infinity for the numerical integration of Schrödinger equation is developed in this paper. The methods of the embedded scheme have algebraic orders five and four. Theoretical and numerical results obtained for radial Schrödinger equation and for coupled differential equations show the efficiency of the new methods.
FRAGMENTATION FUNCTIONS FOR Bc AND $B^*_c$ MESONS WITH DEFINITE POLARIZATION
Authors: NOBARY M. A. GOMSHI , O'SATI T.
Published: May 2003

We present exact fragmentation functions for the production of S-wave Bc and [Formula: see text] mesons splitting out of a [Formula: see text]-antiquark. We distinguish transverse and longitudinal polarizations of [Formula: see text] which is important in hadronic spin properties of such states. Input parameters for our functions are quark masses, meson decay constants, and the transverse momentum for the hard production mechanism. Evolution of such functions from fragmentation scale up to an appropriate factorization scale are given. We compare our results with similar ones in the literature.
STUDY OF DIRECT CP ASYMMETRY IN B+→K0π+
Authors: MOHANTA RUKMANI
Published: May 2003

The direct CP asymmetry (aCP) for the process B+→π+K0 is studied including the contributions arising from both the QCD and electroweak penguins and the long range inelastic final state interactions (IFSI). The usually neglected space-like penguins and the annihilation contributions are also taken into account in our analysis. The next-to-leading order low energy effective Hamiltonian and BSW model are used to evaluate the weak transition matrix elements. The effect of space-like and annihilation diagrams are studied using the Lepage and Brodsky model. We found that as a result of FSI, the CP asymmetry and the branching ratio are suppressed slightly in comparison to no FSI situation, but the obtained branching ratio with FSI agrees very well with the present experimental value. With our predicted value of aCP~1010, charged B mesons are required to resolve the CP asymmetry experimentally at 3σ level.
WHAT DOES E8 KNOW ABOUT 11 DIMENSIONS?
Authors: KOGAN IAN I. , WHEATER JOHN F.
Published: May 2003

We discuss some possible relationships in gauge theories, string theory and M-theory in the light of some recent results obtained in gauge-invariant supersymmetric quantum mechanics. In particular, this reveals a new relationship between the gauge group E8 and 11-dimensional space.
MATTER ENHANCED NEUTRINO OSCILLATIONS WITH A REALISTIC EARTH DENSITY PROFILE
Authors: FREUND MARTIN , OHLSSON TOMMY
Published: May 2003

We have investigated matter enhanced neutrino oscillations with a mantle-core-mantle step function and a realistic Earth matter density profile in both a two- and a three-neutrino scenario. We found that the realistic Earth matter density profile can be well approximated with the mantle-core-mantle step function and that there could be an influence on the oscillation channel νμ→ντ due to resonant enhancement of one of the mixing angles.
PHENOMENOLOGY OF THE FLAVOR-ASYMMETRY IN THE LIGHT-QUARK SEA OF THE NUCLEON
Authors: GLÜCK M. , REYA E.
Published: May 2003

A phenomenological ansatz for the flavor-asymmetry of the light sea distributions of the nucleon, based on the Pauli exclusion principle, is proposed. This ansatz is compatible with the measured flavor-asymmetry of the unpolarized sea distributions, [Formula: see text], of the nucleon. A prediction for the corresponding polarized flavor-asymmetry is presented and shown to agree with predictions of (chiral quark–soliton) models which successfully reproduced the flavor-asymmetry of the unpolarized sea.
A NOTE ON THE QUADRATIC DIVERGENCE IN HYBRID REGULARIZATION
Authors: NITTOH KOH-ICHI
Published: May 2003

We consider the quadratic divergence of the Yang–Mills theory when we use the hybrid regularization method consisting of higher covariant derivative terms and the Pauli–Villars fields. By explicit calculation of the diagrams, we show that the higher derivative terms for the ghost fields are necessary for the complete cancellation of the quadratic divergence.
DARBOUX CLASS OF COSMOLOGICAL FLUIDS WITH TIME-DEPENDENT ADIABATIC INDICES
Authors: ROSU H. C.
Published: May 2003

A one-parameter family of time-dependent adiabatic indices is introduced for any given type of cosmological fluid of constant adiabatic index by a mathematical method belonging to the class of Darboux transformations. The procedure works for zero cosmological constant at the price of introducing a new constant parameter related to the time dependence of the adiabatic index. These fluids can be the real cosmological fluids that are encountered at cosmological scales and they could be used as a simple and efficient explanation for the recent experimental findings regarding the present day accelerating universe. In addition, new types of cosmological scale factors, corresponding to these fluids, are presented.
GRAVITATIONAL LENSING STATISTICS AS A PROBE OF DARK ENERGY
Authors: ZHU ZONG-HONG
Published: May 2003

By using the comoving distance, we derive an analytic expression for the optical depth of gravitational lensing, which depends on the redshift to the source and the cosmological model characterized by the cosmic mass density parameter Ωm, the dark energy density parameter Ωm and its equation of state ωx = px/ρx. It is shown that, the larger the dark energy density and the more negative its pressure, the higher is the gravitational lensing probability. This fact can provide an independent constraint for dark energy.
THE sp(3) BRST SYMMETRY FOR REDUCIBLE DYNAMICAL SYSTEMS
Authors: CONSTANTINESCU RADU , IONESCU CARMEN
Published: May 2003

This letter focuses on the matter of the Hamiltonian description of reducible dynamical systems using the BRST technique. We will have in mind important examples as the Freedman–Townsend one or the bosonic string, both endowed with an sp (3) BRST symmetry. For the first time, for such type of theories, a structure of the extended phase space will be proposed, as well as the forms of the BRST charges and of the extended Hamiltonian.
SUPERSYMMETRY IN 2+2 DIMENSIONS
Authors: BRANDT F. T. , MCKEON D. G. C. , SHERRY T. N.
Published: May 2003

The analysis of spinors in 2+2 dimensions is reviewed. The two most basic supersymmetry algebras in this space are considered. In the simpler case, the supersymmetry generators are Majorana spinors. In the other algebra we consider, the supersymmetry generators are Dirac spinors. Consistency with having a positive definite Hilbert space is shown to be impossible in both of these particular cases.
ZERO MODES IN FINITE RANGE MAGNETIC FIELDS
Authors: ADAM C. , MURATORI B. , NASH C.
Published: May 2003

We find a class of fermion zero modes of Abelian Dirac operators in three-dimensional Euclidean space where the gauge potentials and the related magnetic fields are nonzero only in a finite space region.
EXACT SOLUTION OF THE DIRAC EQUATION FOR A SINGULAR CENTRAL POWER POTENTIAL
Authors: BOSE SUBIR K. , SCHULZE-HALBERG AXEL
Published: May 2003

We compute an exact solution of the Dirac equation for a certain power law potential that consists of two parts: a scalar and a vector, where the latter contains a Coulomb term. We obtain energies that turn out to depend only on the strength of the Coulomb part of the potential, but not on the remaining power law part. We show that our ansatz also yields a bound state solution for the lowest excited state.

This work is an extension of Franklins result.7
STOCHASTIC DIFFERENTIAL EQUATIONS FOR THE CONTINUOUS SPONTANEOUS LOCALIZATION MODEL
Authors: SANTOS L. F. , ESCOBAR C. O.
Published: May 2003

We extend Vink's method [J. C. Vink, Phys. Rev.A48, 1808 (1993)], developed for an isolated quantum system, to an open quantum system consisting of a free particle interacting with its surrounding through a random potential, which causes the spontaneous localization of its wave function. We then obtain the stochastic differential equations (SDE) underlying its evolution. These SDE help us to observe the effects of the environment upon the movement of the particle.
NONCOMMUTATIVE OPEN STRINGS FROM DIRAC QUANTIZATION
Authors: KIM WON TAE , OH JOHN J.
Published: May 2003

We study Dirac commutators of canonical variables on D-branes with a constant Neveu–Schwarz two-form field by using the Dirac constraint quantization method, and point out some subtleties appearing in previous works in analyzing constraint structure of the brane system. Overcoming some ad hoc procedures, we obtain desirable noncommutative coordinates exactly compatible with the result of the conformal field theory in recent literatures. Furthermore, we find interesting commutator relations of other canonical variables.
FRACTAL INDEX, CENTRAL CHARGE AND FRACTONS
Authors: DA CRUZ WELLINGTON , DE OLIVEIRA ROSEVALDO
Published: May 2003

We introduce the notion of fractal index associated with the universal class h of particles or quasiparticles, termed fractons which obey specific fractal statistics. A connection between fractons and conformal field theory (CFT)-quasiparticles is established taking into account the central charge c[ν] and the particle-hole duality ν↔1/ν, for integer-value ν of the statistical parameter. In this way, we derive the Fermi velocity in terms of the central charge as [Formula: see text]. The Hausdorff dimension h which labeled the universal classes of particles and the conformal anomaly are therefore related. Following another route, we also established a connection between Rogers dilogarithm function, Farey series of rational numbers and the Hausdorff dimension.
MOVING MIXED BRANES IN COMPACT SPACE–TIME
Authors: KAMANI DAVOUD
Published: May 2003

In this letter we present a general description of two moving branes in the presence of the field Bμν and gauge fields [Formula: see text] and [Formula: see text] on them, in space–time that some of its directions are compact on tori. Some examples are considered to elucidate this general description. Also the contribution of the massless states to the interaction is extracted. Boundary state formalism is a useful tool for these considerations.
NON-ABELIAN PERMITTIVITY OF QUARK–GLUON PLASMA DUE TO THE SELF-INTERACTION OF FIELD
Authors: CHEN JI-SHENG , LI JIA-RONG
Published: May 2003

From the semiclassical kinetic equations and the mean field equation of quark–gluon plasma, the contribution of the color field self-coupling to the non-Abelian permittivity at the leading order in the weak coupling constant is analyzed. The nonlinear frequency drift has been estimated for the k=0 modes.
A THOUGHT EXPERIMENT WITH CLOCKS IN STATIC GRAVITY
Authors: OKUN L. B.
Published: May 2003

In order to directly demonstrate that in static gravitational field the rate of clocks increases with their distance from the source, a simple thought experiment is proposed.
OBTAINING THE SPIN OF THE PROTON FROM THE SPINS OF THE QUARKS
Authors: SRIVASTAVA Y. N. , WIDOM ALLAN
Published: May 2003

Employing the experimental electroweak interactions between quarks and leptons, the spin of the proton may easily be understood in terms of the spins of the constituent quarks.
DUAL MEISSNER EFFECT IN THE INFRARED REGION OF QCD WITH QUARKS
Authors: PARTHASARATHY R.
Published: May 2003

Motivated by the suggestion of 't Hooft and Mandelstam that magnetic monopoles must play a crucial role in the ir region of QCD and that of Nambu that dual Meissner effect as a mechanism of confinement, QCD in this region is described by the magnetic symmetry of Cho. The standard SU(3) QCD action with quarks is considered which now contains the monopole configurations. A dual action is constructed and mass term for the dual Abelian field is generated by gauge mixing mechanism. The effective dual action thus obtained exhibits dual Meissner effect.
DYNAMICAL MASS AND PARITY CONDENSATE IN VARYING TOPOLOGICAL MASS
Authors: MATSUYAMA TOYOKI , NAGAHIRO HIDEKO
Published: May 2003

We investigate how a dynamical mass of a fermion is affected by a topological mass of a gauge field in a Maxwell–Chern–Simons QED3 coupled with a two-component fermion. The dynamical mass and also a parity condensate are estimated by using a nonperturbative Schwinger–Dyson method. In particular, we study a limit of vanishing the topological mass in detail and clarify a link between theories with and without a Chern–Simons term in a nonperturbative level.
BOSONIC STRING — KALUZA–KLEIN THEORY EXACT SOLUTIONS USING 5D–6D DUALITIES
Authors: HERRERA-AGUILAR ALFREDO , KECHKIN OLEG V.
Published: May 2003

We present explicit formulas which allow one to transform a general solution of the 6D Kaluza–Klein theory compactified on a three-torus into a special solution of the 6D bosonic string theory compactified on a three-torus, as well as into the general solution of the 5D bosonic string theory compactified on a two-torus. We construct a new family of extremal solutions of the 3D chiral equation for the SL(4, R)/SO(4) coset matrix and interpret it in terms of the component fields of these three duality related theories.
NON-HERMITIAN OSCILLATOR-LIKE HAMILTONIANS AND λ-COHERENT STATES REVISITED
Authors: BECKERS JULES , DEBERGH NATHALIE , CARIÑENA JOSÉ F. , MARMO GIUSEPPE
Published: May 2003

Previous λ-deformed non-Hermitian Hamiltonians with respect to the usual scalar product of Hilbert spaces dealing with harmonic oscillator-like developments are (re)considered with respect to a new scalar product in order to take into account their property of self-adjointness. The corresponding deformed λ-states lead to new families of coherent states according to the DOCS, AOCS and MUCS points of view.
CLOSED TIMELIKE CURVES IN (2+1)-AdS GRAVITY
Authors: VALTANCOLI P.
Published: May 2003

We build the (2+1)-AdS gravity generalization of the Gott time machine using a first-order formalism for solving the scattering of point sources. The two-body dynamics is solved by two invariant masses, whose difference is simply related to the total angular momentum of the system. We show how to build a time machine when at least one of the two invariant masses is no more real but acquires an imaginary part.
η′K PUZZLE OF B MESON DECAYS AND NEW PHYSICS EFFECTS IN THE TC2 MODEL
Authors: XIAO ZHENJUN , LI WENJUN , LU GONGRU , GUO LIBO
Published: May 2003

Using the low energy effective Hamiltonian with the generalized factorization, we calculate the new physics contributions to B→π+π-, Kπ and Kη′ in the topcolor-assisted-technicolor (TC2) model, and compare the results with the available data. By using [Formula: see text] preferred by the CLEO data of B→π+π-decay, we find that the new physics enhancements to B→ Kη′ decays are significant in size, ~ 50% with respect to the standard model predictions, insensitive to the variations of input parameters and hence provide a simple and plausible new physics interpretation for the observed unexpectedly large B→ Kη′ decay rates.
N=4 SUPERSYMMETRIC YANG–MILLS THEORY ON ORBIFOLD-T4/Z2
Authors: JINZENJI MASAO , SASAKI TORU
Published: May 2003

We derive the partition function of N=4 supersymmetric Yang–Mills theory on orbifold-T4/Z2. In classical geometry, K3 surface is constructed from the orbifold-T4/Z2. Along the same way as the orbifold construction, we construct the partition function of K3 surface from orbifold-T4/Z2. The partition function is given by the product of the contribution of the untwisted sector of T4/Z2, and that of the twisted sector of T4/Z2, i.e. [Formula: see text] curve blowup formula.
WAVELET ANALYSIS FOR RANDOM PROCESSES
Authors: LI ZHIMING , WANG QIN , WU YUANFANG
Published: May 2003

The role of wavelet transformation in the study of random processes is investigated. It is shown that wavelet transformation does not change the scaling index of random multiplicative cascade process. On the other hand, for pure random process, wavelet transformation is able to suppress the trivial fluctuations, coming from probability conservation, which will show an apparent increase in moments with the diminishing of bin size.
ENERGY DISTRIBUTION OF A CHARGED REGULAR BLACK HOLE
Authors: RADINSCHI I.
Published: May 2003

We calculate the energy distribution of a charged regular black hole using the energy–momentum complexes of Einstein and Møller.
PROJECTORS FOR THE FUZZY SPHERE
Authors: VALTANCOLI P.
Published: May 2003

All fiber bundles with a given set of characteristic classes can be considered as particular projections of a more general bundle called a universal classifying space. This notion of projector valued field, a global definition of connections and gauge fields, may be useful in defining vector bundles for noncommutative base spaces. In this letter we derive the projector valued field for the fuzzy sphere, define noncommutative n-monopole configurations, and check that in the classical limit, using the machinery of noncommutative geometry, the corresponding topological charges (Chern class) are integers.
NON-NEWTONIAN GRAVITY, FLUCTUATIVE HYPOTHESIS AND THE SIZES OF ASTROPHYSICAL STRUCTURES
Authors: CAPOZZIELLO SALVATORE , DE MARTINO SALVATORE , DE SIENA SILVIO , ILLUMINATI FABRIZIO
Published: May 2003

We show that the characteristic sizes of astrophysical and cosmological structures, where gravity is the only overall relevant interaction assembling the system, have a phenomenological relation to the microscopic scales whose order of magnitude is essentially ruled by the Compton wavelength of the proton. This result agrees with the absence of screening mechanisms for the gravitational interaction and could be connected to the presence of Yukawa correcting terms in the Newtonian potential which introduces typical interaction lengths. Furthermore, we are able to justify, in a straightforward way, the Sanders-postulated mass of a vector boson considered in order to obtain the characteristic sizes of galaxies.
CASIMIR ENERGY AND REALISTIC MODEL OF DILUTE DIELECTRIC BALL
Authors: MARACHEVSKY VALERY N.
Published: May 2003

The Casimir energy of a dilute homogeneous nonmagnetic dielectric ball at zero temperature is derived analytically for the first time for an arbitrary physically possible frequency dispersion of dielectric permittivity ε(iω). A microscopic model of dielectrics is considered, divergences are absent in calculations because an average interatomic distance λ is a physical cutoff in the theory. This fact has been overlooked earlier, which led to divergences in various macroscopic approaches to the Casimir energy of connected dielectrics.
SINGLE SCALAR TOP PRODUCTION WITH POLARIZED BEAMS IN ep COLLISIONS AT HERA
Authors: KITAMURA SHOICHI , KON TADASHI , KOBAYASHI TETSURO
Published: May 2003

From the point of view of the R-parity breaking supersymmetric model, we propose a scalar top (stop) search with longitudinally polarized electron [Formula: see text] and positron [Formula: see text] beams which will soon be available at the upgraded HERA. Fully polarized e- or e+ beams could produce the stop two times as much as unpolarized beams, while they increase background events due to the process of the standard model by ~ 30% in comparison with unpolarized ones. We show that right-handed e+ beams at HERA is efficient to produce the stop in the model. With 1 fb-1 of integrated luminosity we estimate to reach in the coupling constant λ′131 for masses of the stop in the range 160–400 GeV. We can set a 95% confidence level exclusion limit for λ′131 > 0.01–0.05 in the stop mass range of 240–280 GeV if no signal of the stop is observed. We also point out that y(= Q2/sx) distributions of e+ coming from the stop shows different behavior from those of the standard model.
FOCK SPACE STRUCTURE FOR THE SIMPLEST PARASUPERSYMMETRIC SYSTEM
Authors: YANG WEIMIN , JING SICONG
Published: May 2003

Structure of the state-vector space for a system consisting of one mode para-Bose and one mode para-Fermi degree of freedom with the same parastatistics order p is studied and a complete, orthonormal set of basis vectors in this space is constructed. There is an intrinsic double degeneracy for state vectors with m parabosons and n parafermions, where m ≠ 0, n ≠ 0 and n ≠ p. It is also shown that the degeneracy plays a key role in realization of exact supersymmetry for such a system.
OFF-SHELL TACHYON AMPLITUDES: ANALYTICITY AND PROJECTIVE INVARIANCE
Authors: CUOMO FRANCESCO , NICODEMI FRANCESCO , PETTORINO ROBERTO , PEZZELLA FRANCO , SABELLA GIANLUCA , MAROTTA RAFFAELE
Published: May 2003

We compute off-shell three- and four-tachyon amplitudes at tree level by using a prescription based on the requirement of projective invariance. In particular we show that the off-shell four-tachyon amplitude can be put in the same form as the corresponding on-shell one, exhibiting therefore the same analyticity properties. This is shown both for the bosonic and for the fermionic strings. The result obtained in the latter case can be extended to the off-shell four-tachyon amplitude in type 0 theory.
NONCOMMUTATIVE GEOMETRY, QUANTUM NONLOCALITY AND STOCHASTIC QUANTIZATION
Authors: GHOSH PRADIP
Published: May 2003

The problem of localization of relativistic particle in quantum physics originates from the fact that position variable is non-Hermitian in nature. Kalney1 in a series of papers, has tried to construct a position operator for a massive as well as massless particle in a unified way incorporating Lorentz invariance. His observation of non-Hermitian and non-normal nature of position operator suggests that it gives rise to the possibility of getting more information from complex eigenvalues. Kalney and Toledo2 have considered that a relativistic particle may not be a point particle and position be extended to certain region. Non-Hermitian nature of position variable is suitable for description of such extended body as each coordinate is associated with a pair of variables.
TRANSVERSE ISOTROPY IN IDENTICAL PARTICLE SCATTERING
Authors: CANTO L. F. , DONANGELO R. , HUSSEIN M. S.
Published: May 2003

It is pointed out that the cross-section for the scattering of identical charged bosons is isotropic over a broad angular range around 90° when the Sommerfeld parameter has a critical value, which depends exclusively on the spin of the particle. This effect is not limited to either Coulomb scattering or bosons, and, as illustrated in the shadow scattering of identical hadrons, may lead to interesting physical effects.
COSMOLOGY IN SCALAR–TENSOR THEORY AND ASYMPTOTICALLY de SITTER UNIVERSE
Authors: SEN A. A. , SEN S.
Published: May 2003

We have investigated the cosmological scenarios with a four-dimensional effective action which is connected with multidimensional, supergravity and string theories. The solution for the scale factor is such that initially universe undergoes a decelerated expansion but in late times it enters into the accelerated expansion phase. In fact, it asymptotically becomes a de Sitter universe. The dilaton field in our model is a decreasing function of time and it becomes a constant in late time resulting the exit from the scalar–tensor theory to the standard Einstein's gravity. Also the dilaton field results in the existence of a positive cosmological constant in late times.
NEUTRALINO DARK MATTER ELASTIC SCATTERING IN A FLAT AND ACCELERATING UNIVERSE
Authors: LAHANAS A. B. , SPANOS V. C. , NANOPOULOS D. V.
Published: May 2003

In SUGRA inspired supersymmetric models with universal boundary conditions for the soft masses, the scalar cross-section σ scalar for the elastic neutralino–nucleon scattering is in general several orders of magnitude below the sensitivity of current experiments. For large tan β and low M1/2, m0 values, the theoretically predicted σ scalar can approach the sensitivity of these experiments (≈ 10-6 pb ) being at the same time in agreement with recent cosmological data, which impose severe restrictions on the CDM relic density, and with accelerator experiments which put lower bounds on sparticle and Higgs boson masses. Further improvement of the sensitivity of DAMA and CDMS experiments will probe the large tan β region of the parameter space in the vicinity of the boundaries of the parameter space allowed by chargino and Higgs searches.
ON A LIE ALGEBRAIC APPROACH OF QUASI-EXACTLY SOLVABLE POTENTIALS WITH TWO KNOWN EIGENSTATES
Authors: BRIHAYE Y. , DEBERGH N. , NDIMUBANDI J.
Published: May 2003

We compare two recent approaches of quasi-exactly solvable Schrödinger equations, the first one being related to finite-dimensional representations of sl (2, R) while the second one is based on supersymmetric developments. Our results are then illustrated on the Razavy potential, the sextic oscillator and a scalar field model.
THE CARDY–VERLINDE FORMULA AND CHARGED TOPOLOGICAL AdS BLACK HOLES
Authors: YOUM DONAM
Published: May 2003

We consider the brane universe in the bulk background of the charged topological AdS black holes. The evolution of the brane universe is described by the Friedmann equations for a flat or an open FRW-universe containing radiation and stiff matter. We find that the temperature and entropy of the dual CFT are simply expressed in terms of the Hubble parameter and its time derivative, and the Friedmann equations coincide with thermodynamic formulas of the dual CFT at the moment when the brane crosses the black hole horizon. We obtain the generalized Cardy–Verlinde formula for the CFT with an R-charge, for any values of the curvature parameter k in the Friedmann equations.
ON A UNIFIED APPROACH TO AVERAGE PHASE SPACE DENSITY IN SOME SULPHUR-INDUCED HIGH ENERGY NUCLEAR COLLISIONS
Authors: BHATTACHARYYA S. , DE BHASKAR
Published: May 2003

The Average Phase Space Density (APSD) of very high energy nuclear collisions at the total "freeze-out" temperature offers an indirect but convenient tool to assess the merit and worth of the pionisation models. We have attempted to apply here a specific multiple production model with a view to estimating the APSD of pions for a set of sulphur-induced ultrarelativistic heavy-ion collisions in a unified manner, to compare them finally with the experiment-based results of NA35 and NA44-groups at CERN and also with the calculational results based on the thermal model. The specific implications of the present approach have also been pointed out in the end.
INFLATON POTENTIAL RECONSTRUCTION IN EINSTEIN–CARTAN COSMOLOGY
Authors: GARCIA DE ANDRADE L. C.
Published: May 2003

An extension of the reconstruction of inflaton potential in general relativistic cosmology to space–times with spin–torsion density is undertaken. Torsion effects are shown to decrease when the number of e-folds increases and are important only at the early stages of the inflation. The potential is computed in terms of a generalized equation of state and when the spin–torsion density is high and a chaotic inflation potential is found. A particle creation model in Einstein–Cartan cosmology is also shown to lead to chaotic inflation potential in de Sitter space–time.
(1/2, 1/2) REPRESENTATION SPACE — AN ab initio CONSTRUCT
Authors: AHLUWALIA D. V. , KIRCHBACH M.
Published: May 2003

A careful ab initio construction of the finite-mass (1/2, 1/2) representation space of the Lorentz group reveals it to be a spin-parity multiplet. In general, it does not lend itself to a single-spin interpretation. We find that the (1/2, 1/2) representation space for massive particles naturally bifurcates into a triplet and a singlet of opposite relative intrinsic parties. The textbook separation into spin-1 and spin-0 states occurs only for certain limited kinematical settings. We construct a wave equation for the (1/2, 1/2) multiplet, and show that the particles and antiparticles in this representation space do not carry a definite spin but only a definite relative intrinsic parity. In general, both spin-1 and spin-0 are covariantly inseparable inhabitants of massive vector fields. This last observation suggests that scalar particles, such as the Higgs, are natural inhabitants of massive (1/2, 1/2) representation space.
SCALAR–SCALAR BOUND STATE IN NONCOMMUTATIVE SPACE
Authors: HAGHIGHAT M. , LORAN F.
Published: May 2003

Bethe–Salpeter equation in the noncommutative space for a scalar–scalar bound state is considered. It is shown that in the nonrelativistic limit, the effect of spatial noncommutativity appears as if there exists a magnetic dipole moment coupled to each particle.
JORDANIAN QUANTUM SPHERES
Authors: CHAKRABARTI R. , SEGAR J.
Published: May 2003

We introduce and investigate a one-parameter family of quantum spaces invariant under the left (right) co-action of the group-like element [Formula: see text] of the Jordanian function algebra Fun h( SL (2)). These spaces may be regarded as Jordanian quantization of the two-dimensional spheres.
Λ0 POLARIZATION IN EXCLUSIVE AND INCLUSIVE p-NUCLEUS REACTIONS
Authors: FÉLIX JULIÁN
Published: May 2003

Both Λ0 polarization from inclusive and exclusive p-Nucleus reactions follow the same trend as function of xF and [Formula: see text]. It is valid for -1.0<xF<+1.0 and 0.0<PT<2.0 GeV/c and for Nucleus=p, Be, Cu, W and Pb. The value of a depends on the target nature: it is -(0.443 ± 0.037), in exclusive pp reactions; -(0.376 ± 0.024), in inclusive pp reactions; -(0.232 ± 0.012), in inclusive p Be reactions; -(0.124 ± 0.015), in inclusive p Cu reactions; -(0.274 ± 0.023), in inclusive p W reactions; -(0.147 ± 0.023), in inclusive p Pb reactions. It is independent of the beam energy. And this equation is the most simple bilinear form that describes Λ0 polarization in -1.0<xF<+1.0 and 0.0<PT<2.0 GeV/c .
S-MATRICES FOR SPINOR PARTICLES ON SCHWARZSCHILD BLACK HOLES
Authors: FIRSOVA N. E.
Published: May 2003

The scattering problems arising when considering the contribution of the topologically inequivalent configurations of the spinors on Schwarzschild black holes to the Hawking radiation are correctly stated. The corresponding S-matrices are described and presented in the form convenient to numerical computations.
HAMILTON–JACOBI SOLUTION TO SOLITON PATHS AND TRIANGULAR MASS RELATION IN TWO-DIMENSIONAL EXTENDED SUPERSYMMETRIC THEORY
Authors: MOTOYUI NOBUYUKI , TOMINAGA SHOGO , YAMADA MITSURU
Published: May 2003

D=2, N=2 generalized Wess–Zumino theory is investigated by the dimensional reduction from D=4, N=1 theory. For each solitonic configuration (i,j), the classical static solution is solved by the Hamilton–Jacobi method of equivalent one-dimensional classical mechanics. It is easily shown that the Bogomol'nyi mass bound is saturated by these solutions and triangular mass inequality [Formula: see text] is automatically satisfied.
COVARIANT TWO-POINT FUNCTION FOR MINIMALLY COUPLED SCALAR FIELD IN de SITTER SPACE–TIME
Authors: TAKOOK MOHAMMAD VAHID
Published: May 2003

In a recent paper,1 it has been shown that negative norm states are indispensable for a fully covariant quantization of the minimally coupled scalar field in de Sitter space. Their presence, while leaving unchanged the physical content of the theory, offers an automatic and covariant renormalization of the vacuum energy divergence. This paper is a completion of our previous work. An explicit construction of the covariant two-point function of the "massless" minimally coupled scalar field in de Sitter space is given, which is free of any infrared divergence. The associated Schwinger commutator function and retarded Green's function are calculated in a fully gauge-invariant way, which also means coordinate independent.
CANCELLATION OF UV DIVERGENCES IN THE ${\mathcal N} = 4$ SUSY NONLINEAR SIGMA MODEL IN THREE DIMENSIONS
Authors: INAMI TAKEO , SAITO YORINORI , YAMAMOTO MASAYOSHI
Published: May 2003

We study the uv properties of the three-dimensional [Formula: see text] SUSY nonlinear sigma model whose target space is T*(CPN-1) (the cotangent bundle of CPN-1) to higher orders in the 1/N expansion. We calculate the β-function to next-to-leading order and verify that it has no quantum corrections at leading and next-to-leading orders.
LOCAL PHYSICAL COORDINATES FROM SYMPLECTIC PROJECTOR METHOD
Authors: DE ANDRADE M. A. , SANTOS M. A. , VANCEA I. V.
Published: May 2003

The basic arguments underlying the symplectic projector method are presented. By this method, local free coordinates on the constraint surface can be obtained for a broader class of constrained systems. Some interesting examples are analyzed.
QUASI-EXACTLY SOLVABLE N×N-MATRIX SCHRÖDINGER OPERATORS
Authors: BRIHAYE YVES , HARTMANN BETTI
Published: May 2003

New examples of matrix quasi-exactly solvable Schrödinger operators are constructed. One of them constitutes a matrix generalization of the quasi-exactly solvable anharmonic oscillator, the corresponding invariant vector space is constructed explicitly. Matrix generalizations of the Lamé equation are also investigated.
GENERALIZED CONTINUITY EQUATION AND MODIFIED NORMALIZATION IN PT-SYMMETRIC QUANTUM MECHANICS
Authors: BAGCHI B. , QUESNE C. , ZNOJIL M.
Published: May 2003

The continuity, equation relating the change in time of the position probability density to the gradient of the probability current density is generalized to PT-symmetric quantum mechanics. The normalization condition of eigenfunctions is modified in accordance with this new conservation law and illustrated with some detailed examples.
THE LANDAU PROBLEM AND NONCOMMUTATIVE QUANTUM MECHANICS
Authors: GAMBOA J. , MÉNDEZ F. , LOEWE M. , ROJAS J. C.
Published: May 2003

We explore the conditions under which noncommutative quantum mechanics and the Landau problem are equivalent theories. If the potential in noncommutative quantum mechanics is chosen as V=Ωℵ with ℵ defined in the text, then for the value [Formula: see text] (which measures the noncommutative effects of the space), the Landau problem and noncommutative quantum mechanics are equivalent theories in the lowest Landau level. For other systems one can find different values for [Formula: see text] and, therefore, the possible bounds for [Formula: see text] should be searched in a physical independent scenario. This last fact could explain the different bounds for [Formula: see text] found in the literature.
THE EFFECTIVE MASS OF NUCLEON UNDER THE CONDITION OF PHASE TRANSITION
Authors: SHU SONG , JING MEN , LI JIA-RONG
Published: May 2003

Based on the Walecka model, we mainly discuss how the effective mass of nucleon changes under the condition of phase transition. We indicate that the effective mass of nucleon changes non-monotonically with temperature and chemical potential when the phase transition occurs.
THE CONTRIBUTION OF THE VERTICAL PART OF THE REAL-TIME CONTOUR IN FINITE TEMPERATURE FIELD THEORY: FINITE TEMPERATURE FIELD THEORY
Authors: AL-NAGHMOOSH ALI , AL-THOYAIB SULEIMAN S. , TAHA M. O.
Published: May 2003

We investigate the contribution of the vertical part of the real-time contour in finite temperature field theory. For this purpose we parametrize the contour C in the complex x0-plane by a single real parameter t. We prove the existence of a nonvanishing vertical contribution.
ELECTRICALLY CHARGED EINSTEIN–BORN–INFELD BLACK HOLES WITH MASSIVE DILATON
Authors: YAZADJIEV STOYTCHO S. , FIZIEV PLAMEN P. , BOYADJIEV TODOR L. , TODOROV MICHAIL D.
Published: May 2003

We numerically construct static and spherically symmetric electrically charged black hole solutions in Einstein–Born–Infeld gravity with massive dilaton. The numerical solutions show that the dilaton potential allows many more black hole causal structures than the massless dilaton. We find that depending on the black hole mass and charge and the dilaton mass, the black holes can have either one, two, or three horizons. The extremal solutions are also found. As an interesting peculiarity we note that there are extremal black holes with an inner horizon and with triply degenerated horizon.
THE ν - N CHARGED CURRENT CROSS-SECTION AT LOW ENERGY
Authors: HERNÁNDEZ KLARA GOIZ , GODINA NAVA J. J.
Published: May 2003

We reanalyze the neutrino–nucleon charged current (CC) cross-section with particular attention to the energy range Eν ≤ 10 GeV . We use new experimental data to obtain the form factors involved in the calculation of the cross-section, and discuss possible consequences for the interpretation of the measurements of the atmospheric fluxes obtained by deep underground detectors.
SPONTANEOUS PHYSICAL COMPACTIFICATION OF THE EXTRA DIMENSIONS
Authors: LI TIANJUN
Published: May 2003

We conjecture that the extra dimensions are physical noncompact at high energy scale or high temperature; after the symmetry breaking or cosmological phase transition, the bulk cosmological constant may become negative, and then, the extra dimensions may become physical compact at low energy scale. We show this in a five-dimensional toy brane model with three parallel three-branes and a real bulk scalar whose potential is temperature-dependent. We also point out that after the global or gauge symmetry breaking, or the supersymmetry breaking in supergravity theory, the spontaneous physical compactification of the extra dimensions might be realized.