bluuebunny/crossref_metadata_2025 huggingface dataset:
EXOTIC HADRONS OF MINIMAL PENTAQUARK $(qqqq{\bar q}) STATES
Authors: GAO HAIYAN , MA BO-QIANG
Published: May 2003

It is shown that the exotic non-qqq hadrons of pentaquark [Formula: see text] states can be clearly distinguished from the conventional qqq-baryon resonances or their hybrids if the flavor of [Formula: see text] is different from any of the other four quarks. We suggest the physical process [Formula: see text], which can be investigated at the Thomas Jefferson National Accelerator Facility (JLab), as an ideal process to search for the existence or non-existence of the exotic hadron of minimal pentaquark state [Formula: see text].
MIRROR WORLD VERSUS LARGE EXTRA DIMENSIONS
Authors: SILAGADZE Z. K.
Published: May 2003

Recently proposed low scale quantum gravity scenario is expected to have a significant impact on the mirror world hypothesis. Some aspects of this influence is investigated here, assuming that the fundamental gravity scale is near a TeV. It is shown that future colliders will be capable of producing the mirror matter, but an experimental signature, which will distinguish such events from the background, is not clear. The "smoking gun" signals of the mirror world would be an observation of decays like [Formula: see text]. But unfortunately the expected branching ratios are very small. Finally, it is shown that a mirror supernova will be quite a spectacular event for our world too, because a considerable amount of ordinary energy is expected to be emitted in the first few seconds.
WAVE PACKET APPROACH TO THE EQUAL-ENERGY/MOMENTUM/VELOCITY PRESCRIPTIONS OF NEUTRINO OSCILLATION
Authors: TAKEUCHI YOSHIHIRO , TAZAKI YUICHI , TSAI S. Y. , YAMAZAKI TAKASHI
Published: May 2003

Neutrino oscillation is discussed with emphasis placed more on its conceptual aspects. After reviewing the two conventional formulations, referred to as the equal-energy prescription and the equal-momentum prescription, wave packet treatments are developed for each of these two prescriptions. Both wave packets localized in space and those localized in time are considered, and, by invoking relativistic kinematics as well, the necessary conditions for oscillation to occur are derived, which appear to have a form more well-defined and quantitative than what have been noted before. Some phenomenological implications suggested by the wave packet treatments are briefly mentioned. Finally, as a possible third prescription, the equal-velocity prescription is given.
ON THE INTEGRABILITY OF THE BUKHVOSTOV–LIPATOV MODEL
Authors: AMEDURI MARCO , EFTHIMIOU COSTAS J. , GERGANOV BOGOMIL
Published: May 2003

The integrability of the Bukhvostov–Lipatov four-fermion model is investigated. It is shown that the classical model possesses a current of Lorentz spin-3, conserved both in the bulk and on the half-line for specific types of boundary actions. It is then established that the conservation law is spoiled at the quantum level — a fact that might indicate that the quantum Bukhvostov–Lipatov model is not integrable, contrary to what was previously believed.
CASIMIR ENERGY OF MASSLESS FERMIONS IN THE SLAB-BAG
Authors: DE PAOLA R. D. M. , RODRIGUES R. B. , SVAITER N. F.
Published: May 2003

The zero-point energy of a massless fermion field in the interior of two parallel plates in a D-dimensional space–time at zero temperature is calculated. In order to regularize the model, a mix between dimensional and zeta-function regularization procedure is used and it is found that the regularized zero-point energy density is finite for any number of space–time dimensions. We present a general expression for the Casimir energy of the fermionic field in such a situation.
A NON-ANTHROPIC ORIGIN FOR A SMALL COSMOLOGICAL CONSTANT
Authors: SIVARAM C.
Published: May 2003

An impressive variety of recent observations which include luminosity evolutions of high redshift supernovae strongly suggest that the cosmological constant (∧) is not zero. Even though the ∧-term may dominate cosmic dynamics at the present epoch, such a value for the vacuum energy is actually unnaturally small. The difficulties in finding a suitable explanation (based on fundamental physics) for such a small residual value for the cosmological term has led several authors to resort to an anthropic explanation for its existence. Here we present a few examples which invoke phase transitions in the early universe involving strong or electroweak interactions to show how the cosmical term of the correct observed magnitude can arise from fundamental physics involving gravity.
THE EFFECT OF Bπ CONTINUUM IN THE QCD SUM RULES FOR THE (0+,1+) HEAVY MESON DOUBLET IN HQET
Authors: ZHU SHI-LIN , DAI YUAN-BEN
Published: May 2003

We study the effect of Bπ continuum in the QCD sum rule analysis of the heavy meson doublet (0+,1+) in the leading order of heavy quark effective theory. New sum rules are derived for the leading order binding energy [Formula: see text] and pionic coupling constant g′.
GREEN–SCHWARZ SUPERSTRINGS ON AdS3 AND THE BOUNDARY N=4 SUPERCONFORMAL ALGEBRA
Authors: ITO KATSUSHI
Published: May 2003

We study the hybrid formulation of Green–Schwarz superstrings on AdS3 with NS flux and the boundary N=4 superconformal algebra. We show the equivalence between the NSR and GS superstrings by a field redefinition. The boundary N=4 superconformal algebra is realized by the free fields of the affine Lie superalgebra A(1|1)(1). We also consider the light-cone gauge and obtain the N=4 super-Liouville theory which describes the effective theory of the single long string near the singularities of the D1–D5 system.
FIELD CONFIGURATIONS AND THEIR INSTABILITY INDUCED BY HIGHER DIMENSIONS OF SPACE–TIME: AN EXAMPLE
Authors: MERSINI LAURA
Published: May 2003

We use the model of L. Randall et al.3 to investigate the stability of allowed quantum field configurations. Firstly, we find that due to the topology of this five-dimensional model, there are two possible configurations of the scalar field, untwisted and twisted. They give rise to two types of instability. Secondly, when allowed to interact in the brane, the untwisted field is shown to be unstable even if it is at the true vacuum ground state as a result of one-loop corrections that arise from coupling with the twisted field. On the other hand, the twisted field can make the two three-branes (that are otherwise identical in their properties and geometry) distinguishable therefore causing an energy difference between them. That is due to the antiperiodicity of the twisted fields, when rotating with π to go from one three-brane to the other. This energy difference between the branes renders the fifth dimension unstable. This toy model is simple enough to use to illustrate a point that can be important for the general case of any high dimension model, namely: higher dimensions, besides many other effects can also induce more than one field configuration and that can have consequences (e.g. instabilities) even after reducing the problem to four dimensions.
CAN BLACK HOLES BE CREATED AT THE BIRTH OF THE UNIVERSE?
Authors: WU ZHONG CHAO
Published: May 2003

We study the quantum creation of black hole pairs in the (anti-)de Sitter space background. These black hole pairs in the Kerr–Newman family are created from constrained instantons. At the WKB level, for the chargeless and nonrotating case, the relative creation probability is the exponential of (the negative of) the entropy of the universe. Also for the remaining cases of the family, the creation probability is the exponential of (the negative of) one quarter of the sum of the inner and outer black hole horizon areas. In the absence of a general no-boundary proposal for open universes, we treat the creations of the closed and the open universes in the same way.
A SIMPLE DIRAC WAVE FUNCTION FOR A COULOMB POTENTIAL WITH LINEAR CONFINEMENT
Authors: FRANKLIN JERROLD
Published: May 2003

A simple analytical solution is found to the Dirac equation for the combination of a Coulomb potential with a linear confining potential. An appropriate linear combination of Lorentz scalar and vector linear potentials, with the scalar part dominating, can be chosen to give a simple Dirac wave function. The binding energy depends only on the Coulomb strength and is not affected by the linear potential. The method works for the ground state, or for the lowest state with l=j-1/2, for any j.
ON INFINITE QUON STATISTICS AND "AMBIGUOUS" STATISTICS
Authors: MELJANAC S. , MILEKOVIC M. , RISTIC R.
Published: May 2003

We critically examine a recent suggestion that "ambiguous" statistics is equivalent to infinite quon statistics and that it describes a dilute, nonrelativistic ideal gas of extremal black holes. We show that these two types of statistics are different and that the description of extremal black holes in terms of "ambiguous" statistics cannot be applied.
VECTOR COHERENT STATES FOR AFFINE SUPERALGEBRAS AND REPRESENTATIONS OF $\widehat{\rm \lc{osp}}(1|2)$
Authors: ZHANG R. B.
Published: May 2003

Vector coherent states associated with affine superalgebras are introduced, and those for [Formula: see text] are studied in detail. A new realization of all the irreducible highest weight representations of this affine superalgebra is obtained in terms of holomorphic super-differential operators in infinitely many Grassmannian and bosonic variables.
VARYING c COSMOLOGY AND PLANCK VALUE CONSTRAINTS
Authors: COULE D. H.
Published: May 2003

It has been suggested that by increasing the speed of light during the early universe various cosmological problems of standard big bang cosmology can be overcome, without requiring an inflationary phase. However, we find that as the Planck length and Planck time are then made correspondingly smaller, and together with the need that the universe should not re-enter a Planck epoch, the higher c models have very limited ability to resolve such problems. For a constantly decreasing c, the universe will quickly becomes quantum gravitationally dominated as time increases: the opposite to standard cosmology where quantum behaviour is only ascribed to early times.
QUASI SUPERSYMMETRY WITHIN THE STANDARD MODEL AND HIGGS MASS
Authors: DEO B. B. , SINGH L. P.
Published: May 2003

The 12 bosonic degrees of freedom of the standard model (SM) are exactly matched by fermionic degrees of freedom of a single colored quark, e.g. top. Indeed, we construct a charge involving top-quark, gauge and Higgs fields which satisfy usual supersymmetry algebra. The colored quark states behave like the superpartners of gauge and Higgs bosons and vice versa. When this SUSY is broken, a mass relation must be satisfied at the tree level from which the mass of the Higgs is predicted to be 300.5±11 GeV.
THE B→Xsl+l- AND B→Xsγ DECAYS WITH THE FOURTH GENERATION
Authors: HUANG CHAO-SHANG , HUO WU-JUN , WU YUE-LIANG
Published: May 2003

If the fourth generation fermions exist, the new quarks could influence the branching ratios of the decays of B→Xsγ and B→Xsl+l-. We obtain two solutions of the fourth generation CKM factor [Formula: see text] from the decay of B→ Xsγ. We use these two solutions to calculate the new contributions of the fourth generation quark to Wilson coefficients of the decay of B→ Xsl+l-. The branching ratio and the forward–backward asymmetry of the decay of B→ Xsl+l- in the two cases are calculated. Our results are quite different from that of SM in one case, almost the same in another case. If Nature chooses the former, the B meson decays could provide a possible test of the fourth generation existence.
HYDROGEN ATOM AS AN EIGENVALUE PROBLEM IN 3-D SPACES OF CONSTANT CURVATURE AND MINIMAL LENGTH
Authors: NIETO L. M. , SANTANDER M. , ROSU H. C.
Published: May 2003

An old result of Stevenson [Phys. Rev.59, 842 (1941)] concerning the Kepler–Coulomb quantum problem on the three-dimensional (3-D) hypersphere is considered from the perspective of the radial Schrödinger equations on 3-D spaces of any (either positive, zero or negative) constant curvature. Further to Stevenson, we show in detail how to get the hypergeometric wave function for the hydrogen atom case. Finally, we make a comparison between the "space curvature" effects and minimal length effects for the hydrogen spectrum.
GENERALIZED FERMI PARTITION FUNCTION OBTAINED VIA COHERENT STATE REPRESENTATION OF THE DENSITY OPERATOR
Authors: FAN HONG-YI , ZOU HUI , FAN YUE
Published: May 2003

We generalize the well-known partition function of Fermi harmonic oscillator (H =ω(f+f + ½))[Formula: see text] to [Formula: see text] for Fermi system described by the n-mode fermionic Hamiltonian [Formula: see text]. This result is derived via constructing the fermionic coherent state representation of the density operator [Formula: see text] in which [Formula: see text] is identified as exp {-β Γ Π}.
CONFORMAL INVARIANCE AND WAVE-PARTICLE DUALITY
Authors: MOTAVALI H. , SALEHI H. , GOLSHANI M.
Published: May 2003

We present a conformally invariant generalized form of the free particle action by connecting the wave and particle aspects through gravity. Conformal invariance breaking is introduced by choosing a particular configuration of dynamical variables. This leads to the geometrization of the quantum aspects of matter.
A Z2 × Z2 ORIENTIFOLD WITH SPONTANEOUSLY BROKEN SUPERSYMMETRY
Authors: COTRONE A. L.
Published: May 2003

We present a Z2 × Z2 four-dimensional orientifold in which supersymmetry is broken by a temperature-like Scherk–Schwarz mechanism. As usual in this type of models, at the tree-level the breaking affects only the branes tangent to the direction involved by the SS deformation, and it can propagate only through radiative corrections to other sectors, where the gauge group is broken. The result is a non-chiral model with gauge group Usp (16)⊗2× Usp (8)⊗4.
FATHER TIME I: DOES THE COSMIC MICROWAVE BACKGROUND RADIATION PROVIDE A UNIVERSAL ARROW OF TIME?
Authors: DASTIDAR T. K. RAI
Published: May 2003

It was demonstrated in a recent paper (Mod. Phys. Lett.A13, 1265 (1998), hep-th/9902020) that the existence of a nonthermodynamic arrow of time at the atomic level is a fundamental requirement for conservation of energy in matter-radiation interaction. In this letter we show that the cosmic microwave background radiation can provide this time's arrow to all particles in the universe that are acted on by the electromagnetic field.
ANALYSIS OF A RENORMALIZATION GROUP EQUATION USING THE PROLONGATION METHOD
Authors: BRACKEN PAUL
Published: May 2003

The renormalization group equation in quantum field theory is reviewed. The prolongation method is applied to a simplified version of the resulting equation. A system of first order differential equations results which determine the coefficients in the prolonged vector field. Finally, we show how this system can be solved in several cases to determine solutions of these equations.
ON FURTHER REPRESENTATIONS OF THE TWO-BODY CALOGERO ALGEBRA
Authors: DEBERGH N. , REMEZO L.
Published: May 2003

Supplementary finite-dimensional irreducible representations of the dynamical algebra subtending the two-body Calogero model are constructed by pointing out the corresponding differential realizations.
OCTET MAGNETIC MOMENTS WITH NULL INSTANTONS AND SEMIBOSONIZED NAMBU–JONA-LASINIO MODEL
Authors: BUKINA ELENA N.
Published: May 2003

It is shown that the difference between the magnetic moment results in the quark model with null instantons and semibosonized Nambu–Jona-Lasinio model lies in the symmetry properties of the meson cloud contributions.
ON HOLOMORPHIC EFFECTIVE ACTIONS OF HYPERMULTIPLETS COUPLED TO EXTERNAL GAUGE SUPERFIELDS
Authors: BUCHBINDER I. L. , SAMSONOV I. B.
Published: May 2003

We study the structure of holomorphic effective action generated by hypermultiplet models interacting with background super-Yang–Mills fields. A general form of holomorphic effective action depending on background fields is found for hypermultiplet belonging to arbitrary representation of any semisimple compact Lie group spontaneously broken to its maximal Abelian subgroup. Resulting effective action is defined by the superfield strengths lying in Cartan subalgebra of the gauge algebra. The applications of the obtained results to hypermultiplets in fundamental and adjoint representations of the SU (n), SO (n), Sp (n) groups are considered.
FLAVOR-OSCILLATION CLOCKS, CONTINUOUS QUANTUM MEASUREMENTS AND A VIOLATION OF EINSTEIN EQUIVALENCE PRINCIPLE
Authors: CAMACHO A.
Published: May 2003

The relation between Einstein equivalence principle and a continuous quantum measurement is analyzed in the context of the recently proposed flavor-oscillation clocks, an idea pioneered by Ahluwalia and Burgard (Gen. Rel. Grav.29, 681(E) (1997)). We will calculate the measurement outputs if a flavor-oscillation clock, which is immersed in a gravitational field, is subject to a continuous quantum measurement. Afterwards, resorting to the weak equivalence principle, we obtain the corresponding quantities in a freely falling reference frame. Finally, comparing this last result with the measurement outputs that would appear in a Minkowskian space–time it will be found that they do not coincide, in other words, we have a violation of Einstein equivalence principle. This violation appears in two different forms, namely: (i) the oscillation frequency in a freely falling reference frame does not match with the case predicted by general relativity, a feature previously obtained by Ahluwalia; (ii) the probability distribution of the measurement outputs, obtained by an observer in a freely falling reference frame, does not coincide with the results that would appear in the case of a Minkowskian space–time. Concerning this last difference, the probability distribution differs in two directions. Firstly, the maximum, as function of the energy of the system (that emerges if we calculate first the probability distribution in the original curved manifold and then, resorting to the weak equivalence principle, we find the corresponding expression in a freely falling reference frame) is shifted with respect to the case in which the system is in a Minkowskian space–time. Secondly, the magnitude of this maximum is not equal to the respective quantity predicted by general relativity. In other words, we obtain two new theoretical results that predict a violation of Einstein equivalence principle, and that could be measured.
ON THE QUANTIZATION OF THE GS TYPE IIB SUPERSTRING ACTION ON AdS3 WITH NSNS FLUX
Authors: PESANDO I.
Published: May 2003

We quantize the type IIB string action on AdS3⊗S3 with pure NSNS background and show that it is equivalent to Liouville with periodic boundary condition plus free fermions.
$gg\rightarrow\gamma\bar ff$ IN THE STRONGLY INTERACTING PHASE OF THE MSSM
Authors: DEMIR D. A.
Published: May 2003

[Formula: see text] scattering is discussed in the strongly interacting phase of the MSSM. The rate for the decay [Formula: see text] is computed in the MSSM and SM, and the values of the Higgs–sfermion coupling needed for the former to dominate on the latter are identified. It is found that the MSSM signal dominates on the SM for Higgs–sfermion couplings well below the one needed for developing stopponium bound states via Higgs mediation.
WEAK-QES EXTENSIONS OF THE CALOGERO MODEL
Authors: BRIHAYE Y. , KOSINSKI P.
Published: May 2003

We construct families of Hamiltonians extending the Calogero model and such that a finite number of eigenvectors can be computed algebraically.
SPECTROSCOPY AT B-FACTORIES USING HARD PHOTON EMISSION
Authors: BENAYOUN M. , EIDELMAN S. I. , IVANCHENKO V. N. , SILAGADZE Z. K.
Published: May 2003

The process of hard photon emission by initial electrons (positrons) at B-factories is discussed. It is shown that studies of the bottomonium spectroscopy will be feasible for the planned integrated luminosity of the B-factory experiments.
Ωccc PRODUCTION VIA FRAGMENTATION AT LHC
Authors: SALEEV V. A.
Published: May 2003

In the framework of the leading order of perturbative QCD and the nonrelativistic quark–diquark model of baryons we have obtained fragmentation function for c-quark to split into Ωccc baryon. It is shown that at LHC one can expect 1.8 × 103 events with Ωccc at p⊥>5 GeV/c and |y|<1 per year.
POSSIBLE INSTABILITY OF THE VACUUM IN A STRONG MAGNETIC FIELD
Authors: CALUCCI GIORGIO
Published: May 2003

The possibility that a static magnetic field may decay through production of electron positron pairs is studied. The conclusion is that this decay cannot happen through production of single pairs, as in the electric case, but only through the production of a many-body state, since the mutual magnetic interactions of the created pairs play a relevant role.

The investigation is made in view of the proposed existence of huge magnetic field strengths around some kind of neutron stars.
ON THE ROLE OF CHAOS IN THE AdS/CFT CONNECTION
Authors: RAMA S. KALYANA , SATHIAPALAN B.
Published: May 2003

The question of how infalling matter in a pure state forms a Schwarzschild black hole that appears to be at nonzero temperature is discussed in the context of the AdS/CFT connection. It is argued that the phenomenon of self-thermalization in nonlinear (chaotic) systems can be invoked to explain how the boundary theory, initially at zero temperature self thermalizes and acquires a finite temperature. Yang–Mills theory is known to be chaotic (classically) and the imaginary part of the gluon self-energy (damping rate of the gluon plasma) is expected to give the Lyapunov exponent. We explain how the imaginary part would arise in the corresponding supergravity calculation due to absorption at the horizon of the black hole.
HOPF MAP AND QUANTIZATION ON SPHERE
Authors: IKEMORI HITOSHI , KITAKADO SHINSAKU , OTSU HIDEHARU , SATO TOSHIRO
Published: May 2003

Quantization of a system constrained to move on a sphere is considered by taking a square root of the "on sphere condition". We arrive at the fiber bundle structure of the Hopf map in S2 and S4. This leads to more geometrical understanding of monopole and instanton gauge structures that emerge in the course of quantization.
IS SUPERSYMMETRIC QUANTUM MECHANICS COMPATIBLE WITH DUALITY?
Authors: CAPDEQUI-PEYRANÈRE M.
Published: May 2003

Supersymmetry applied to quantum mechanics has given new insights in various topics of theoretical physics like analytically solvable potentials, WKB approximation or KdV solitons. Duality plays a central role in many supersymmetric theories such as Yang–Mills theories or strings models. We investigate the possible existence of some duality within supersymmetric quantum mechanics.
A QUANTUM POTENTIAL APPROACH FOR THE GRAVITATIONAL SCHRÖDINGER EQUATION AND ITS REDUCTION INTO THE LANE–EMDEN EQUATION OF INDEX 2
Authors: LAN DANG MONG
Published: May 2003

It is shown that the eigenvalue equation in the Jones' treatment of gravitational self-energy may be obtained from a model of extended particles using the quantum potential in the causal interpretation of quantum mechanics and reduced to the Lane–Emden equation of index 2 that has been discussed extensively in the theory of stellar evolution.
N=4 SUGAWARA CONSTRUCTION ON $\widehat{{\rm sl}(2|1)}$, $\widehat{{\rm sl}(3)}$ AND mKdV-TYPE SUPERHIERARCHIES
Authors: IVANOV E. , KRIVONOS S. , TOPPAN F.
Published: May 2003

The local Sugawara constructions of the "small" N=4 SCA in terms of supercurrents of N=2 extensions of the affine [Formula: see text] and [Formula: see text] algebras are investigated. The associated super mKdV type hierarchies induced by N=4 SKdV ones are defined. In the [Formula: see text] case the existence of two nonequivalent Sugawara constructions is found. The "long" one involves all the affine [Formula: see text] currents, while the "short" one deals only with those from the subalgebra [Formula: see text]. As a consequence, the [Formula: see text]-valued affine superfields carry two nonequivalent mKdV type super-hierarchies induced by the correspondence between "small" N=4 SCA and N=4 SKdV hierarchy. However, only the first hierarchy possesses genuine global N=4 supersymmetry. We discuss peculiarities of the realization of this N=4 supersymmetry on the affine supercurrents.
BLACK HOLE FORMATION IN BIDIMENSIONAL DILATON GRAVITY COUPLED TO SCALAR MATTER SYSTEMS
Authors: ALVES M. , BAZEIA D. , BEZERRA V. B.
Published: May 2003

This work deals with the formation of black hole in bidimensional dilaton gravity coupled to scalar matter fields. We investigate two scalar matter systems, one described by a sixth power potential and the other defined with two scalar fields containing up to the fourth power in the fields. The topological solutions that appear in these cases allow the formation of black holes in the corresponding dilaton gravity models.
ENTANGLED EIGENSTATES AND SQUEEZING OPERATOR FOR COMPLEX SCALAR FIELDS
Authors: FAN HONG-YI , CHEN ZENG-BING
Published: May 2003

We derive the entangled eigenstate ‖ξ> of complex scalar fields ϕ and ϕ† in the Fock space. The ‖ξ> state is found to embed the entanglement possessed by the Einstein–Podolsky–Rosen states in quantum mechanics. The ‖ξ> set spans a complete and orthonormal representation. The advantage of the new <ξ‖-representation helps us to derive the normally ordered forms of the squeezing and charge conjugate operators for complex scalar fields rather easily.
NEUTRINO MASSES AND MIXINGS
Authors: XUE SHE-SHENG
Published: May 2003

We propose a novel theoretical understanding of neutrino masses and mixings, which is attributed to the left–right symmetric feature of the regularized standard model at short distances. We try to explain the smallness of Dirac neutrino masses and the decoupling of the right-handed neutrino as a free particle. Neutrino masses and mixing angles are completely related to each other in the Schwinger–Dyson equations for their self-energy functions. The solutions to these equations and a possible pattern of masses and mixings are discussed.
LOCAL SYMMETRIES IN THE AdS7/CFT6 CORRESPONDENCE
Authors: NISHIMURA MADOKA , TANII YOSHIAKI
Published: May 2003

It is shown that local symmetry transformations of the maximal AdS supergravity in seven-dimensional anti de Sitter space induce those of the N=(2,0) conformal supergravity on the six-dimensional boundary at infinity. Boundary values of the AdS supergravity fields form a supermultiplet of the conformal supergravity.
GLOBAL MONOPOLE AS DUAL-VACUUM SOLUTION IN KALUZA–KLEIN SPACE–TIME
Authors: DADHICH NARESH , PATEL L. K. , TIKEKAR R.
Published: May 2003

By the application of the duality transformation, which implies interchange of active and passive electric parts of the Riemann curvature (equivalent to interchanging Ricci and Einstein tensors), it is shown that the global monopole solution in the Kaluza–Klein space–time is dual to the corresponding vacuum solution. Further we also obtain solution dual to flat space which would in general describe a massive global monopole in four-dimensional Euclidean space and would have massless limit analogous to the four-dimensional dual-flat solution.
SUPERSYMMETRY OF PARAFERMIONS
Authors: KLISHEVICH SERGEI , PLYUSHCHAY MIKHAIL
Published: May 2003

We show that the single-mode parafermionic type systems possess supersymmetry, which is based on the symmetry of characteristic functions of the parafermions related to the generalized deformed oscillator of Daskaloyannis et al. The supersymmetry is realized in both unbroken and spontaneously broken phases. As in the case of parabosonic supersymmetry observed recently by one of the authors, the form of the associated superalgebra depends on the order of the parafermion and can be linear or nonlinear in the Hamiltonian. The list of supersymmetric parafermionic systems includes usual parafermions, finite-dimensional q-deformed oscillator, q-deformed parafermionic oscillator and parafermionic oscillator with internal Z2 structure.
HIGH TEMPERATURE LIMIT OF THE N=2 MATRIX MODEL
Authors: BAL SUBRATA , SATHIAPALAN B.
Published: May 2003

The high temperature limit of a system of two D-0 branes is investigated. The partition function can be expressed as a power series in β (inverse temperature). The leading term in the high temperature expression of the partition function and effective potential is calculated exactly. Physical quantities like the mean square separation can also be exactly determined in the high temperature limit.
ON THE INVERSE OF TWO-MODE BOSON OPERATORS (a-b†) AND (a†-b)
Authors: FAN HONG-YI , SUN ZHI-HU , ZOU HUI
Published: May 2003

We study the properties of the inverse of two-mode boson operators (a-b†) and (a†-b), by constructing the charged bosonic orthogonal state |q, r>, where r denotes the radius. We show that in |q, r> representation (a†-b)-1 and (a-b†)-1 lowers and ascends the charge quantum number q, respectively, which resembles the behavior of single-mode inverse operator [Formula: see text] in Fock space.
COMPUTATION OF THE CENTRAL CHARGE FOR THE LEADING ORDER OF THE N = 2 SUPER-YANG–MILLS EFFECTIVE ACTION
Authors: WOLF SYLVAIN
Published: May 2003

The central charge in the N=2 super-Yang–Mills theory plays an essential role in the work of Seiberg and Witten as it gives the mass spectrum of the BPS states of the quantum theory. Our aim in this letter is to present a direct computation of this central charge for the leading order (in a momentum expansion) of the effective action. We will consider the N=2 super-Yang–Mills theory with gauge group SU(2). The leading order of the effective action is given by the same holomorphic function ℱ appearing in the low energy U(1) effective action.
DIRAC RELATION AND RENORMALIZATION GROUP EQUATIONS FOR ELECTRIC AND MAGNETIC FINE STRUCTURE CONSTANTS
Authors: LAPERASHVILI L. V. , NIELSEN H. B.
Published: May 2003

The quantum field theory describing electric and magnetic charges and revealing a dual symmetry was developed in the Zwanziger formalism. The renormalization group (RG) equations for both fine structure constants — electric α and magnetic [Formula: see text] — were obtained. It was shown that the Dirac relation is valid for the renormalized α and [Formula: see text] at the arbitrary scale, but these RG equations can be considered perturbatively only in the small region: 0.25≲α, [Formula: see text] with [Formula: see text] given by the Dirac relation: [Formula: see text].
CONFORMAL FIELD THEORY, QUANTUM GROUP AND BERRY PHASE
Authors: BANDYOPADHYAY P.
Published: May 2003

From an analysis of the relationship between the conformal field theory in 1+1 dimension, the Chern–Simons theory in 2+1 dimension and chiral anomaly in 3+1 dimension, we study here the relationship between the central charge c, Chern–Simons coupling k and the Berry phase factor μ where the phase is given by ei2πμ which is associated with the chiral anomaly and their association with the quantum symmetry in the framework of the Landau problem of 2D electron gas in a magnetic field. A possible link between the deformation parameter q of the deformed algebra Uq( SL (2)) with these parameters is suggested. It is also shown how a Zp spin system is realized for a quantum space and the parameter p is linked up with the deformation parameter q and; in turn with the central charge c and the Berry phase factor μ. Finally some implications of this result in a statistical system are discussed.
ELECTROWEAK THEORY WITHOUT HIGGS BOSONS
Authors: NICHOLSON ANGUS F. , KENNEDY DALLAS C.
Published: May 2003

A perturbative SU (2)L× U (1)Y electroweak theory containing W, Z, photon, ghost, lepton and quark fields, but no Higgs or other fields, gives masses to W, Z and the nonneutrino fermions by means of an unconventional choice for the unperturbed Lagrangian and a novel method of renormalization. The renormalization extends to all orders. The masses emerge on renormalization to one loop. To one loop the neutrinos are massless, the A↔Z transition drops out of the theory, the d quark is unstable and S matrix elements are independent of the gauge parameter ξ.
THE PARISI–SOURLAS MECHANISM IN YANG–MILLS THEORY?
Authors: MAGPANTAY J. A.
Published: May 2003

The Parisi–Sourlas mechanism is exhibited in pure Yang–Mills theory. Using the new scalar degrees of freedom derived from the nonlinear gauge condition, we show that the nonperturbative sector of Yang–Mills theory is equivalent to a 4D O(1, 3) sigma model in a random field. We then show that the leading term of this equivalent theory is invariant under supersymmetry transformations where [Formula: see text] is unchanged. This leads to dimensional reduction proving the equivalence of the nonperturbative sector of Yang–Mills theory to a 2D O(1, 3) sigma model.
QUANTUM TOPOLOGY CHANGE IN (2+1)d
Authors: BALACHANDRAN A. P. , BATISTA E. , COSTA e SILVA I. P. , TEOTONIO-SOBRINHO P.
Published: May 2003

The topology of orientable (2+1) space–times can be captured by certain lumps of nontrivial topology called topological geons. They are the topological analogs of conventional solitons. We give a description of topological geons where the degrees of freedom related to topology are separated from the complete theory that contain metric (dynamical) degrees of freedom. The formalism also allows us to investigate processes of quantum topology change. They correspond to creation and annihilation of quantum geons. Selection rules for such processes are derived.
BRST COHOMOLOGY AND HODGE DECOMPOSITION THEOREM IN ABELIAN GAUGE THEORY
Authors: MALIK R. P.
Published: May 2003

We discuss the Becchi–Rouet–Stora–Tyutin (BRST) cohomology and Hodge decomposition theorem for the two-dimensional free U(1) gauge theory. In addition to the usual BRST charge, we derive a local, conserved and nilpotent co(dual)-BRST charge under which the gauge-fixing term remains invariant. We express the Hodge decomposition theorem in terms of these charges and the Laplacian operator. We take a single photon state in the quantum Hilbert space and demonstrate the notion of gauge invariance, no-(anti)ghost theorem, transversality of photon and establish the topological nature of this theory by exploiting the concepts of BRST cohomology and Hodge decomposition theorem. In fact, the topological nature of this theory is encoded in the vanishing of the Laplacian operator when equations of motion are exploited. On the two-dimensional compact manifold, we derive two sets of topological invariants with respect to the conserved and nilpotent BRST- and co-BRST charges and express the Lagrangian density of the theory as the sum of terms that are BRST- and co-BRST invariants. Mathematically, this theory captures together some of the key features of both Witten- and Schwarz-type of topological field theories.
ON THE STRUCTURE OF PHYSICAL SPACE
Authors: WISNIVESKY DANIEL
Published: May 2003

In this paper we develop a theory based on the postulate that the environment where physical phenomena take place is the space of four complex parameters of the linear group of transformations. Using these parameters as fundamental building blocks we construct ordinary space–time and the internal space. Lorentz invariance is built in the definition of external space, while the symmetry of the internal space, S(1)×SU(2) results as a consequence of the identification of the external coordinates. Thus, special relativity and the electroweak interaction symmetry ensue from the properties of the basic building blocks of physical space. Since internal and external space are derived from a common structure, there is no need to bring into the theory any additional hypothesis to account for the microscopic nature of the internal space, nor to introduce symmetry breaking mechanisms that would normally be required to force a splitting of the internal and external symmetries. As an outcome of the existence of a basic structure underlying the external space–time, the weak and electromagnetic coupling constants are not independent and the Weinberg weak mixing angle is derived from the theory. In this new theory, there is an interrelationship between external and internal transformations, which leads to the quantization of electric charge. Finally we conclude that the electroweak gauge theory can be regarded as a consequence of Einstein's general theory of relativity. The proposed theory represents an extension of the normally accepted theory and includes it as a particular case. This paper is an attempt to formulate a new framework in which the physical phenomena take place, and to explore some of its consequences.
COSMIC BIREFRINGENCE WITHIN THE FRAMEWORK OF HETEROTIC STRING THEORY
Authors: DAS PRASANTA , JAIN PANKAJ , MUKHERJI SUDIPTA
Published: May 2003

Low energy string theory predicts the existence of an axion field which can lead to cosmic birefringence. We solve the electromagnetic wave equations in the presence of such an axion and a dilaton field in order to determine their effect on the polarization of light. We find that the presence of dilaton field leads to a nontrivial modification of the final result. We comment on the possibility of discovering such an effect by observations of radio wave polarizations from distant radio galaxies and quasars. We have also determined the limits on the string theory parameters that are imposed by the current radio polarization data.
LEPTON NUMBERS IN THE FRAMEWORK OF NEUTRINO MIXING
Authors: BILENKY S. M. , GIUNTI C.
Published: May 2003

In this short review we discuss the notion of lepton numbers. The strong evidence in favor of neutrino oscillations obtained recently in the super-Kamiokande atmospheric neutrino experiment and in solar neutrino experiments imply that the law of conservation of family lepton numbers Le, Lμ and Lτ is strongly violated. We consider the states of flavor neutrinos νe, νμ and ντ and we discuss the evolution of these states in space and time in the case of nonconservation of family lepton numbers due to the mixing of light neutrinos. We discuss and compare different flavor neutrino discovery experiments. We stress that experiments on the search for νμ→ντ and νe→ντ oscillations demonstrated that the flavor neutrino ντ is a new type of neutrino, different from νe and νμ. In the case of neutrino mixing, the lepton number (only one) is connected with the nature of massive neutrinos. Such a conserved lepton number exists if massive neutrinos are Dirac particles. We review possibilities to check in future experiments whether the conserved lepton number exists.
INSTANTON-SPHALERON TRANSITION IN THE d=2 ABELIAN–HIGGS MODEL ON A CIRCLE
Authors: PARK D. K. , MÜLLER-KIRSTEN H. J. W. , LIANG J. Q. , SHURGAIA A. V.
Published: May 2003

The transition from the instanton-dominated quantum regime to the sphaleron-dominated classical regime is studied in the d=2 Abelian–Higgs model when the spatial coordinate is compactified to S1. Contrary to the noncompactified case, this model allows both sharp first-order and smooth second-order transitions depending on the size of the circle. This finding may make the model a useful toy model for the analysis of baryon number violating processes. Since the model can to a large extent be treated analytically, it can also serve as a transparent prototype for the application of our method to more complicated cases, such as those in higher dimensions.
POLARIZATION VECTORS AND DOUBLET STRUCTURE IN PLANAR FIELD THEORY
Authors: BANERJEE RABIN , CHAKRABORTY BISWAJIT , SCARIA TOMY
Published: May 2003

We establish the equivalence of the Maxwell–Chern–Simons–Proca model to a doublet of Maxwell–Chern–Simons models defined in a variety of covariant gauges. This equivalence is shown to hold at the level of polarization vectors of the basic fields. The analysis is done in both Lagrangian and Hamiltonian formalisms and compatible results are obtained. A similar equivalence with a doublet of self and anti-self dual models is briefly discussed.
SPIN-STATISTICS THEOREM IN PATH INTEGRAL FORMULATION
Authors: FUJIKAWA KAZUO
Published: May 2003

We present a coherent proof of the spin-statistics theorem in path integral formulation. The local path integral measure and Lorentz-invariant local Lagrangian, when combined with the Green functions defined in terms of time ordered products, ensure causality regardless of statistics. The Feynman m-iε prescription ensures the positive energy condition regardless of statistics, and the abnormal spin-statistics relation for both the spin-0 scalar particles and spin-1/2 Dirac particles is excluded if one imposes the positive norm condition in conjunction with Schwinger's action principle. The minus commutation relation between one Bose and one Fermi field arises naturally in the path integral. The Feynman m-iε prescription also ensures a smooth continuation to Euclidean theory, for which the use of the Weyl anomaly is illustrated to exclude the abnormal statistics for the scalar and Dirac particles not only in four-dimensional theory but also in two-dimensional theory.
BPS BOUND STATES OF D6-BRANES AND LOWER-DIMENSIONAL D-BRANES
Authors: SATO MATSUO
Published: May 2003

We construct 1/8, 1/4, and 1/2 BPS solutions spanned by diagonal elements of U (N) constant fluxes in the (6+1)-dimensional U (N) super Yang–Mills theory on T6 with topological stability. These solutions represent BPS bound states of D0, D2, D4, and D6 branes. The consistency with the D-brane charge conservation implies that unstable D0–D2–D6-brane systems in a B field decay to the BPS solutions, in which lower-dimensional D-branes are dissolved in D6-branes.
STABILITY OF BOSE–EINSTEIN CONDENSATES CONFINED IN TRAPS
Authors: TSURUMI TAKEYA , MORISE HIROFUMI , WADATI MIKI
Published: May 2003

Bose–Einstein condensation has been realized as dilute atomic vapors. This achievement has generated immense interest in this field. This article review of recent theoretical research into the properties of trapped dilute-gas Bose–Einstein condensates. Among these properties, stability of Bose–Einstein condensates confined in traps is mainly discussed. Static properties of the ground state are investigated by using the variational method. The analysis is extended to the stability of two-component condensates. Time-development of the condensate is well-described by the Gross–Pitaevskii equation which is known in nonlinear physics as the no nlinear Schrödinger equation. For the case that the inter-atomic potential is effectively attractive, a singularity of the solution emerges in a finite time. This phenomenon which we call collapse explains the upper bound for the number of atoms in such condensates under traps.
A REMARK ON ONE-DIMENSIONAL MANY-BODY PROBLEMS WITH POINT INTERACTIONS
Authors: ALBEVERIO SERGIO , DABROWSKI LUDWIK , FEI SHAO-MING
Published: May 2003

The integrability of one-dimensional quantum mechanical many-body problems with general contact interactions is extensively studied. It is shown that besides the pure (repulsive or attractive) δ-function interaction there is another singular point interactions which gives rise to a new one-parameter family of integrable quantum mechanical many-body systems. The bound states and scattering matrices are calculated for both bosonic and fermionic statistics.
ENERGY GAP IN THE HUBBARD MODEL
Authors: DIDUKH L. , DOVHOPYATY YU. , SKORENKYY YU.
Published: May 2003

A new variant of the generalized Hartree–Fock approximation for calculation of single-particle Green function in the Hubbard model is proposed. The calculated single-particle energy spectrum allows to study metal–insulator transition. Dependences of the energy gap width and the polar states concentration on model parameters are obtained. Conditions of a metallic and an insulating state realisation are found.
1/f NOISES OF HOMOPOLAR AND HETEROPOLAR SEMICONDUCTORS
Authors: GASPARYAN F. V. , MELKONYAN S. V. , AROUTIOUNYAN V. M. , ASRIYAN H. V.
Published: May 2003

The low-frequency noise spectral density with the 1/f spectrum for homopolar and heteropolar semi-conductors is theoretically obtained taking into account conduction electron–optical phonon interactions. The analytical expressions of the spectral density and Hooge's α H parameter are presented. The analytical temperature dependence of Hooge's parameter is compared with experimental data for n-Si and n-GaAs.
POSITRONIUM FORMATION IN CARBON FULLERENES — MYTH OR REALITY?
Authors: RANGANATHAIAH C.
Published: May 2003

Positron lifetimes in C 60 and C 70 fullerenes have been measured using Positron Lifetime technique. The analyzed lifetime spectra yields a single lifetime component in agreement with the earlier measurements. XRD measurements have also been used to characterize the fullerene samples. The C 60 and C 70 fullerenes have regular crystallographic face centered cubic structure with lattice constant a = 14.149 Å and 14.903 Å respectively in good agreement with the literature data. The present positron results clearly support the conclusion that positrons do not form positronium in fullerenes.
INTERATOMIC SURFACES IN CONDENSED SYSTEMS: A QUANTUM-CLASSICAL ANALYSIS
Authors: DELLE SITE L.
Published: May 2003

We analyze the concept of interatomic surface in condensed systems whose properties are calculated with an ab initio approach. Two different criteria for defining such a surface are considered: a classical criterion known as "Bader criterion" and a quantum criterion based on the quantum dynamical behavior of the electrons. Next the classical and quantum approach are combined to obtain a general definition of interatomic surface which is valid from both quantum and classical point of view. The two criteria are presented in the form of partial differential equations and their basic properties are discussed. The relevance of the theory analyzed for a practical implementation in molecular modeling is also discussed.
CRITICAL EXPONENTS OF THE TRANSPORT PROPERTIES AT THE B2⇔IC⇔C(R) TRANSITIONS IN Ti-Ni-Me SHAPE MEMORY ALLOYS
Authors: KOLOMYTSEV V. , NEVDACHA V. , BATAILLARD L. , GOTTHARDT R.
Published: May 2003

Critical behaviour of the physical properties at the B2⇔IC ⇔C(R) phase transitions in TiNi-based shape memory alloys has been analyzed in the frame of the charge density wave (CDW) model. Variation of total resistance at the Peierls-type B2⇔IC ⇔C(R) transition in TiNiMe (Me=Cr, Fe, Al, Ge) alloys has been found to be a sum of the β-phase normal contribution, fluctuating CDW resistance ρ f (T) in the incommensurate state and resistance change due to the energy gap formation ρc(T) in the commensurate state. The fitting parameters such as the energy gap at saturation Δ(0) and the number of electrons involved in the process of the CDW's formation ψ(0) have been determined as a function of the alloy chemical composition and thermal treatment at moderate temperature. The critical resistive fluctuations in the incommensurate phase follow a power law dρ f /dt*~t*m with critical exponent m=-1. In the frame of the CDW model this means that the process of electron scattering from periodic distortion is strongly limited to a definite plane of the crystal and system is two-dimensional. The change of ρ c with temperature is controlled by the activation energy law corresponding to electron single excitations through the gap Δ(T), with a varying ψ(T) effective number of the electrons involved in the process. The total enthalpy measured during cooling is compared with the heat calculated for the energy gap opening at the Fermi level during the IC⇒C(R) transition in the frame of the Shottky anomaly approximation. Both values are of the same order. When hydrostatic pressure is applied to the material, a small drop in the conductivity is observed around P~2 GPa and interpreted as CDW pinning by commensurability locking at a temperature higher than the transition temperature at normal pressure.