bluuebunny/crossref_metadata_2025 huggingface dataset:
RADIATION FROM A UNIFORMLY ACCELERATED CHARGE IN THE OUTSKIRTS OF A WORMHOLE THROAT
Authors: ANCHORDOQUI LUIS A. , CAPOZZIELLO S. , LAMBIASE G. , TORRES DIEGO F.
Published: May 2003

Using traversable wormholes as theoretical background, we revisit a deep question of general relativity: Does a uniformly accelerated charged particle radiate? We particularize to the recently proposed gravitational Čerenkov radiation, that happens when the spatial part of the Ricci tensor is negative. If (3+1)Rii<0 the matter threading the gravitational field violates the weak energy condition. In this case, the effective refractive index for light is larger than 1, i.e. particles propagate faster than photons in that medium. This leads to a violation of the equivalence principle.
EXACT NONFACTORIZABLE ${\mathcal O}(\alpha_sg^2)$ TWO-LOOP CONTRIBUTION TO $Z\to b\bar b$
Authors: GHINCULOV ADRIAN , YAO YORK-PENG
Published: May 2003

For [Formula: see text], we calculate all the two-loop top-dependent Feynman graphs, which have mixed QCD and electroweak contributions that are not factorizable. To evaluate the graphs, without resorting to a mass expansion, we apply a two-loop extension of the one-loop Passarino–Veltman reduction. This is an analytic-numerical method, which first converts all diagrams into a set of ten standard scalar functions, and then integrates them numerically over the remaining Feynman parameters, with rapid convergence and high accuracy. We discuss the treatment of ir singularities within our methods. We do not resort to unitarity cuts of two-point functions for calculating decay rates; these are useful only to obtain an inclusive rate. For this reason, experimental cuts and the experimental ir energy resolution can be implemented in our calculation, once the corresponding one-loop gluon bremsstrahlung process is added to this calculation.
A NOTE ON (D(p-2), Dp) BOUND STATE AND NONCOMMUTATIVE YANG–MILLS THEORY
Authors: YOUM DONAM
Published: May 2003

We give a microscopic explanation for the recently observed equivalence among thermodynamics of supergravity solutions for Dp-branes with or without NS B-field and for D(p-2)-branes with vanishing B-field and two delocalized transverse directions by showing that these D-brane configurations are related to one another through T-duality transformations. This result also gives an evidence for the equivalence among the noncommutative and the ordinary Yang–Mills theories corresponding to the decoupling limits of the worldvolume theories of such D-brane configurations.
A MINIMAL MODEL FOR DILATONIC GRAVITY
Authors: FIZIEV P. P.
Published: May 2003

We study a new minimal scalar–tensor model of gravity with Brans–Dicke factor ω(Φ)≡0 and cosmological factor Π(Φ). The constraints on Π(Φ) from known gravitational experiments are derived. We show that almost any time evolution of the scale factor in a homogeneous isotropic Universe can be obtained via a properly chosen Π(Φ) and discuss the general properties of models of this type.
ON THE ROLE OF THE PLANCK MASS IN COLD ATOM BEAM SCATTERING BY A MASSIVE SPHERE
Authors: PINTO FABRIZIO
Published: May 2003

The scattering of a cold atomic beam by a perfectly conducting spherical mass when gravitational and quantum electrodynamical, retarded dispersion forces are simultaneously relevant allows one to naturally introduce and realistically measure the Planck mass in the laboratory.
THE FUNDAMENTAL COMMUTATOR FOR MASSLESS PARTICLES
Authors: RAZMI H. , ABBASSI AMIR H.
Published: May 2003

It is discussed that the usual Heisenberg commutation relation (CR) is not a proper relation for massless particles and that an alternative is obtained. The canonical quantization of the free electromagnetic (EM) fields based on the field theoretical generalization of this alternative is carried out. Without imposing the normal ordering condition, the vacuum energy is automatically zero. This can be considered as a solution to the EM fields vacuum catastrophe and a step toward managing the cosmological constant problem at least for the EM fields contribution to the state of vacuum.
INDUCED FIELD THEORY ON THE BRANE WORLD — GRAVITY, EXTRINSIC CURVATURE, AND GAUGE FIELDS
Authors: AKAMA KEIICHI , HATTORI TAKASHI
Published: May 2003

We show how the gravity, extrinsic curvature, and gauge field theories are induced on dynamically localized brane world. They should obey the Gauss–Codazzi–Ricci equation in addition to their own equations of motion. As an example, we derive the solitonic solution for curved domain wall in five dimensions in terms of gravity and extrinsic curvature fields of the brane, and then derive the effective action for their field theory on the brane.
NOTE ON TWO-DIMENSIONAL NONLINEAR GAUGE THEORIES
Authors: BIZDADEA C.
Published: May 2003

A two-dimensional nonlinear gauge theory that can be proposed for generalization to higher dimensions is derived by means of cohomological arguments.
SCINTILLATION CRYSTAL DETECTOR FOR LOW ENERGY NEUTRINO PHYSICS
Authors: WONG HENRY T. , LI JIN
Published: May 2003

A research collaboration among scientists from Taiwan, Mainland China and the United States has been set up since 1997 to initiate and pursue an experimental program in Neutrino and Astroparticle Physics. The theme of our efforts is the use of scintillating crystal detector for low-energy low-background experiments. The flagship experiment is based on CsI(Tl) crystals placed near the core of the Kuo-Sheng Nuclear Power Station in Taiwan to study low energy neutrino interactions. Various R&D projects are being pursued. A summary of our efforts and program is presented.
COMMENT ON THE POSSIBILITY OF A GEOMETRIC CONSTRAINT IN THE SCHRÖDINGER QUANTUM MECHANICS
Authors: MOSTAFAZADEH ALI
Published: May 2003

It is shown that the geometric constraint advocated in [R. S. Kaushal, Mod. Phys. Lett.A15, 1391 (2000)] is trivially satisfied. Therefore, such a constraint does not exist. We also point out another flaw in Kaushal's paper.
CHARGED SPIN-1/2 PARTICLE IN AN ARBITRARY MAGNETIC FIELD IN TWO SPATIAL DIMENSIONS: A SUPERSYMMETRIC QUANTUM MECHANICAL SYSTEM
Authors: CLARK T. E. , LOVE S. T. , NOWLING S. R.
Published: May 2003

It is shown that the 2×2 matrix Hamiltonian describing the dynamics of a charged spin-1/2 particle with g-factor 2 moving in an arbitrary, spatially dependent, magnetic field in two spatial dimensions can be written as the anticommutator of a nilpotent operator and its Hermitian conjugate. Consequently, the Hamiltonians for the two different spin projections form partners of a supersymmetric quantum mechanical system. The resulting supersymmetry algebra can then be exploited to explicitly construct the exact zero energy ground state wave function for the system. Modulo this ground state, the remainder of the eigenstates and eigenvalues of the two partner Hamiltonians form positive energy degenerate pairs. We also construct the spatially asymptotic form of the magnetic field which produces a finite magnetic flux and associated zero energy normalizable ground state wave function.
STUDY OF RADIATIVE LEPTONIC D MESON DECAYS
Authors: GENG C. Q. , LIH C. C. , ZHANG WEI-MIN
Published: May 2003

We study the radiative leptonic D meson decays of [Formula: see text], [Formula: see text] and D0→ l+l-γ (l=e, μ) within the light front quark model. In the standard model, we find that the decay branching ratios of [Formula: see text], [Formula: see text] and [Formula: see text] are 6.9×10-6 (7.7×10-5), 2.5×10-5 (2.6×10-4), and 6.0×10-6 (3.2×10-4), and that of D0→l+l-γ (l=e, μ) and [Formula: see text] are 6.3×10-11 and 2.7×10-16, respectively.
NEW LOCAL SYMMETRY FOR QED IN TWO DIMENSIONS
Authors: MALIK R. P.
Published: May 2003

A new local, covariant and nilpotent symmetry is shown to exist for the interacting BRST invariant U(1) gauge theory in two dimensions of space–time. Under this new symmetry, it is the gauge-fixing term that remains invariant and the corresponding transformations on the Dirac fields turn out to be the analogue of chiral transformations. The extended BRST algebra is derived for the generators of all the underlying symmetries, present in the theory. This algebra turns out to be the analogue of the algebra obeyed by the de Rham cohomology operators of differential geometry. Possible interpretations and implications of this symmetry are pointed out in the context of BRST cohomology and Hodge decomposition theorem.
GRAVITATIONAL HIGGS MECHANISM
Authors: KAKUSHADZE ZURAB , LANGFELDER PETER
Published: May 2003

We discuss the gravitational Higgs mechanism in domain wall background solutions that arise in the theory of five-dimensional Einstein–Hilbert gravity coupled to a scalar field with a nontrivial potential. The scalar fluctuations in such backgrounds can be completely gauged away, and so can be the graviphoton fluctuations. On the other hand, we show that the graviscalar fluctuations do not have normalizable modes. As to the four-dimensional graviton fluctuations, in the case where the volume of the transverse dimension is finite the massive modes are plane-wave normalizable, while the zero mode is quadratically normalizable. We then discuss the coupling of domain wall gravity to localized four-dimensional matter. In particular, we point out that this coupling is consistent only if the matter is conformal. This is different from the Randall–Sundrum case as there is a discontinuity in the δ-function-like limit of such a smooth domain wall — the latter breaks diffeomorphisms only spontaneously, while the Randall–Sundrum brane breaks diffeomorphisms explicitly. Finally, at the quantum level both the domain wall as well as the Randall–Sundrum setups suffer from inconsistencies in the coupling between gravity and localized matter, as well as the fact that gravity is generically expected to be delocalized in such backgrounds due to higher curvature terms.
SU(2) WZW D-BRANES AND QUANTIZED WORLD-VOLUME U(1) FLUX ON S2
Authors: KLING ALEXANDER , KREUZER MAXIMILIAN , ZHOU JIAN-GE
Published: May 2003

We discuss possible D-brane configurations on SU(2) group manifolds in the sigma model approach. When we turn the boundary conditions of the space–time fields into the boundary gluing conditions of chiral currents, we find that for all D-branes except the spherical D2-branes, the gluing matrices Rab depend on the fields, so the chiral Kac–Moody symmetry is broken, but conformal symmetry is maintained. Matching the spherical D2-branes derived from the sigma model with those from the boundary state approach we obtain a U(1) field strength that is consistent with flux quantization.
HIDDEN QUANTUM GROUP SYMMETRY IN 2-D FRACTIONAL SUPERSYMMETRY
Authors: EL KINANI E. H.
Published: May 2003

In this letter, we discuss how some quantum algebraic structures can be realized in terms of 2-D fractional supersymmetry generators. In particular, we show that there is a kind of quantum w∞-symmetry which induces the quantum enveloping U t( sl (2)) algebra.
MAXIMUM MASS–RADIUS RATIO FOR COMPACT GENERAL RELATIVISTIC OBJECTS IN SCHWARZSCHILD–DE SITTER GEOMETRY
Authors: MAK M. K. , DOBSON PETER N. , HARKO T.
Published: May 2003

Upper limits for the mass–radius ratio are derived for arbitrary general relativistic matter distributions in the presence of a cosmological constant. General restrictions for the redshift and total energy (including the gravitational contribution) for compact objects in the Schwarzschild–de Sitter geometry are also obtained in terms of the cosmological constant and of the mean density of the star.
CHARGED TOP-PION CORRECTIONS TO THE TOP QUARK PRODUCTION AT LC IN TC2 THEORY
Authors: YUE CHONGXING , LU GONGRU , SUN JUNFENG , LI WEIBIN
Published: May 2003

We discuss the contributions of PGBs (technipions, top-pions) to the top quark production at the high energy e+e- linear collider (LC) experiments in TC2 theory. We find that the corrections to the production cross-section [Formula: see text] mainly come from top-pions. The corrections of the charged top-pions are significantly large in most of the parameter space. With reasonable value of the parameters, the correction to [Formula: see text] can reach about 8% which may be detected at LC experiments.
SU(2) GLUON PROPAGATOR ON A COARSE ANISOTROPIC LATTICE
Authors: CHEN YING , HE BING , LIN HE , WU JI-MIN
Published: May 2003

We calculated the SU(2) gluon propagator in Landau gauge on an anisotropic coarse lattice with the improved action. The standard and improved schemes are used to fix the gauge in this work. Even on the coarse lattice the lattice gluon propagator can be well described by a function of the continuous momentum. The effect of the improved gauge fixing scheme is found not to be apparent. Based on the Marenzoni's model, the mass scale and the anomalous dimension are extracted and can be reasonably extrapolated to the continuum limit with the values α~0.3 and M~600 MeV . We also extract the physical anisotropy ξ from the gluon propagator due to the explicit ξ dependence of the gluon propagator.
NORMALIZED WEYL-TYPE ⋆-PRODUCT ON KÄHLER MANIFOLDS
Authors: MASUDA TAKUYA
Published: May 2003

We define a normalized Weyl-type ⋆-product on general Kähler manifolds. Expanding this product perturbatively we show that the cumbersome term, which appears in a Berezin-type product, does not appear at least in the first order of ℏ. This means a normalization factor, which is introduced by Reshetikhin and Takhtajan for a Berezin-type product, is unnecessary for our Weyl-type product at that order.
THE NERNST THEOREM AND THE ENTROPY OF A CYLINDRICAL BLACK HOLE
Authors: REN ZHAO , ZHANG LICHUN , WU YUEQIN
Published: May 2003

Under nonspherical coordinates, the free energy and the entropy of a scalar field are calculated in terms of the brick-wall method on the background of a nonasymptotically flat cylindrical black hole. It is shown that the entropy is not only related to the area of an outer horizon but also function of inner horizon at nonasymptotically flat space–time, when a black hole has both inner and outer horizons. Further, the entropy expressed by location parameter of outer and inner horizons approaches zero, when the radiation temperature of a black hole approaches zero. It satisfies the Nernst theorem and can be taken as Planck absolute entropy of a black hole.
TYPE 0 BRANE INFLATION FROM MIRAGE COSMOLOGY
Authors: PAPANTONOPOULOS E. , PAPPA I.
Published: May 2003

We consider a three-dimensional brane-universe moving in a type 0 string background. The motion induces on the brane a cosmological evolution which, for some range of the parameters, exhibits an inflationary phase.
WHY IS THE HIDDEN SECTOR INVISIBLE?
Authors: POLLOCK M. D.
Published: May 2003

The hidden sector of the E8×E′8 heterotic superstring theory of Gross et al. can in principle contain additional "shadow" matter, interacting only gravitationally with the real world in which we live. The SU (3)′ C × SU (2)′ L × U (1)′ Y shadow configuration symmetric to the standard model has been ruled out by Kolb et al. from nucleosynthesis arguments, combined with the existence of three light neutrinos. In the absence of inflation and of entropy enhancement by the out-of-equilibrium decay of an unstable particle, the same exclusion applies to the unbroken E′8 hidden gauge group, assuming thermodynamical equilibrium with the observable sector E6 group, and consequently all breaking chains E′8→ G1×G2×⋯, since they can only reduce the effective number of four-dimensional degrees of freedom g eff . The hidden sector would then appear to be in its vacuum state, which implies the absence of all condensates as well, if their potentials are positive semi-definite. In this case, and if there is no anomalous U(1) symmetry in the observable sector, the QCD axion is the model-independent axion, whose decay constant [Formula: see text] (where [Formula: see text] is the strong-interaction coupling parameter) requires a fine-tuning of the initial value of this axion field to ai/fa≲3×10-3, in order not to overclose the Universe today, supersymmetry being broken by gauge mediation. Vice versa, if ai/fa~1, then hidden-sector gaugino condensation is necessary for there to be a sufficiently massive gravitino, whose decay can increase the entropy. Astronomical microlensing observations may help to discriminate between these two cases.
ON NONCOMMUTATIVE SOLITONS
Authors: SOLOVYOV A.
Published: May 2003

We consider (2+1)-dimensional classical noncommutative scalar field theory. The general ansatz for a radially symmetric solution is obtained. Some exact solutions are presented. Their possible physical meaning is discussed. The case of finite θ is discussed qualitatively and illustrated by some numerical results.
VIOLATIONS OF LORENTZ COVARIANCE IN LIGHT FRONT QUARK MODELS
Authors: BODOOR K. , WEBER H. J. , FREDERICO T. , BEYER M.
Published: May 2003

Electromagnetic form factors of the nucleon from relativistic quark models are analyzed: Results from null-plane projection of the Feynman triangle diagram are compared with a Bakamjian–Thomas model. The magnetic form factors of the models differ by about 15% at spacelike momentum transfer 0.5 GeV2, while the charge form factors are much closer. Spurious contributions to electromagnetic form factors due to violations of rotational symmetry are eliminated for both models. One method changes magnetic form factors by about 10%, whereas the charge form factors remain nearly the same. Another one changes the charge form factor of the Bakamjian–Thomas model by more than 50%.
THE COMPOSITE OPERATOR (CJT) FORMALISM IN THE (λφ4 + ηφ6)D=3 MODEL AT FINITE TEMPERATURE
Authors: AÑAÑOS G. N. J. , SVAITER N. F.
Published: May 2003

We discuss the three-dimensional λφ4+ηφ6 theory in the context of the 1/N expansion at finite temperature. We use the method of the composite operator (CJT) for summing a large set of Feynman graphs. We analyze the behavior of the thermal square mass and the thermal coupling constant in the low and high temperature limits. The existence of the tricritical point at some temperature is found using this method.
IS Ue3 REALLY RELATED TO THE SOLAR NEUTRINO SOLUTIONS?
Authors: HABA N. , SUZUKI TOMOHARU
Published: May 2003

It is important to measure Ue3 in the lepton flavor mixing matrix in order to understand the structure of Majorana neutrino mass matrix. Recently it is conjectured that the measurement of Ue3 would discriminate one solution among various solar neutrino ones provided that the three mass eigenvalues of neutrinos have the relation m1≪m2≪m3 or m1~m2≪m3. In this letter we show that this conjecture is rather restrictive and the relation [Formula: see text] is derived by a nontrivial assumption and Ue3 cannot discriminate among solar neutrino oscillation solutions without the information on another physical parameter.
MASSIVE SUPERPARTICLE WITH TENSORIAL CENTRAL CHARGES
Authors: FEDORUK S. , ZIMA V. G.
Published: May 2003

We construct the manifestly Lorenz-invariant formulation of the N = 1, D=4 massive superparticle with tensorial central charges. The model contains a real parameter k and at k≠0 possesses one κ-symmetry while at k=0 the number of κ-symmetry is two. The equivalence of the formulations at all k≠0 is obtained. The local transformations of κ-symmetry are written. It is considered using the index spinor for construction of the tensorial central charges. The equivalence at classical level between the massive D=4 superparticle with one κ-symmetry and the massive D=4 spinning particle is obtained.
γγ→γZ SCATTERING AND ITS RELATED PROCESSES
Authors: DONG FANG-XIAO , ZHOU XIAN-JIAN
Published: May 2003

The analytic helicity amplitudes of Z→3γ, γγ→Zγ and γZ→γγ via W-loop and charged scalar-loop are presented. There is some difference between our results and those in Ref. 13 for Z→3γ via W-loop and fermion-loop, which has different physical meanings. We have calculated the unpolarized and polarized cross-sections for γγ→γZ process. We find that the total cross-section of γγ→γZ is larger than that of γγ→γγ at 500 GeV of γγ c.m.s. energy. In principle this process provides a test of the non-Abelian nature of the standard model.
ARE SOME HOST GALAXIES OFSNe IaACTUALLY BLUESHIFTING?
Authors: BASU D.
Published: May 2003

Supernova explosions of type Ia (SNe Ia) are now extensively used as "standard candles" in modern cosmology, viz. in constructing the Hubble's diagram and hence in determining various cosmological parameters. One of the most important quantities used in such analyses is the redshift of the host galaxy, which, in its turn, is determined by identifying the observed spectral lines with search lines known in the laboratory. The importance of the correct identification is therefore appreciated. The present work considers the possibility of misidentification of the observed lines. Alternative identification at higher wavelengths leads to blueshifts. Its implication in modern cosmology is discussed. A tentative model of the universe to interpret the results is proposed.
INVESTIGATION OF A NEW ANALYTIC RUNNING COUPLING IN QCD
Authors: NESTERENKO A. V.
Published: May 2003

The mathematical properties of the new analytic running coupling (NARC) in QCD are investigated. This running coupling naturally arises under "analytization" of the renormalization group equation. One of the crucial points in our consideration is the relation established between the NARC and its inverse function. The latter is expressed in terms of the so-called Lambert W function. This relation enables one to present explicitly the NARC in the renorminvariant form and to derive the corresponding β function. The asymptotic behavior of this β function is examined. The consistent estimation of the parameter Λ QCD is given.
MASS GENERATION AND THE DYNAMICAL ROLE OF THE KATOPTRON GROUP
Authors: TRIANTAPHYLLOU GEORGE
Published: May 2003

Heavy mirror fermions along with a new strong gauge interaction capable of breaking the electroweak gauge symmetry dynamically were recently introduced under the name of katoptrons. Their main function is to provide a viable alternative to the Standard-Model Higgs sector. In such a framework, ordinary fermions acquire masses after the breaking of the strong katoptron group which allows mixing with their katoptron partners. The purpose of this letter is to study the elementary-scalars-free mechanism responsible for this breaking and its implications for the fermion mass hierarchies.
GLUEBALL SPIN
Authors: SINGLETON D.
Published: May 2003

The spin of a glueball is usually taken as coming from the spin (and possibly the orbital angular momentum) of its constituent gluons. In light of the difficulties in accounting for the spin of the proton from its constituent quarks, the spin of glueballs is re-examined. The starting point is the fundamental QCD field angular momentum operator written in terms of the chromoelectric and chromomagnetic fields. First, we look at the possible restrictions placed on the structure of glueballs from the requirement that the QCD field angular momentum operator should satisfy the standard commutation relationships. This analysis can be compared to the electromagnetic charge/monopole system, where the requirement that the total field angular momentum obey the angular momentum commutation relationships places restrictions (i.e. the Dirac condition) on the system. Second, we look at the expectation value of the field angular momentum operator under some simplifying assumptions.
ALGEBRAIC CONSTRUCTION OF 't HOOFT'S QUANTUM EQUIVALENCE CLASSES
Authors: SUN C. P. , LIU X. F. , YU S. X.
Published: May 2003

Most recently 't Hooft has postulated (G. 't Hooft, Class. Quantum Grav.16, 3263 (1999)) that quantum states at the "atomic scale" can be understood as equivalence classes of primordial states governed by a dissipative deterministic theory underlying quantum theory at the "Planck scale". Defining invariant subspaces clearly for primordial states according to a given evolution, we mathematically reformulate 't Hooft's theory as a quotient space construction with the time-reversible evolution operator induced naturally. With this observation and some analysis, 't Hooft's theory is generalized beyond his case where the evolution at the "Planck scale" is a power of a one-time-step evolution or the time is discrete.
FIELD THEORIES FROM THE RELATIVISTIC LAW OF MOTION
Authors: SINGH PARAMPREET , DADHICH NARESH
Published: May 2003

From the relativistic law of motion we attempt to deduce the field theories corresponding to the force law being linear and quadratic in four-velocity of the particle. The linear law leads to the vector gauge theory which could be the Abelian Maxwell electrodynamics or the non-Abelian Yang–Mills theory. On the other hand, the quadratic law demands space–time metric as its potential which is equivalent to demanding the principle of equivalence. It leads to the tensor theory of gravitational field — general relativity. It is remarkable that a purely dynamical property of the force law leads uniquely to the corresponding field theories.
TESTING RECIPROCITY AND CPT-INVARIANCE FOR NEUTRAL KAONS
Authors: DASS G. V.
Published: May 2003

We point out that the time–reversal–invariant explanation of the recently observed CPLEAR asymmetry is valid at the level of less than three standard deviations; this asymmetry has been claimed to be the first direct observation of time–reversal–noninvariance in the neutral kaon system. We note how, by avoiding the assumptions made at present, future data may provide model-independent tests of structural T- and CPT-invariances of the neutral kaon complex.
THE ACCELERO-MAGNETIC FIELD, THOMAS PRECESSION AND AN EQUIVALENCE PRINCIPLE FOR SPIN
Authors: UNNIKRISHNAN C. S.
Published: May 2003

In the weak field limit of Einstein gravity, there are gravitational analogues of the vector potential and the magnetic field. The equivalence principle guides us to a magnetic-like interaction arising from inertial acceleration. The spin precession due to this accelero-magnetic field is identified as the Thomas precession. Hence the torque that is responsible for the precession of the spin is identified as resulting from a physical interaction with a magnetic-like inertial-field. Once the equivalence principle is assumed to some accuracy, well supported by precision tests, this implies that the average effect of the accelero-magnetic field on a classical or quantum gyroscope is the same as that of the gravito-magnetic field on a gyroscope. Precision spectroscopy of spin-orbit doublets in atoms is hence an indirect high precision test of the existence and properties of the gravito-magnetic field. This also implies that the planned and current experiments will not see any deviations from the predictions of general relativity. This line of thought is extended to a brief discussion on the possibility of formulating an independent equivalence principle for the spin.
ANOTHER ALTERNATIVE TO COMPACTIFICATION: NONCOMMUTATIVE GEOMETRY AND RANDALL–SUNDRUM MODELS
Authors: LIZZI FEDELE , MANGANO GIANPIERO , MIELE GENNARO
Published: May 2003

We observe that the main feature of the Randall–Sundrum model, used to solve the hierarchy problem, is already present in a class of Yang–Mills plus gravity theories inspired by noncommutative geometry. Strikingly the same expression for the Higgs potential is found in two models which have no apparent connection. Some speculations concerning the possible relationships are given.
GLOBAL PHASE TIME AND PATH INTEGRAL FOR STRING COSMOLOGICAL MODELS
Authors: GIRIBET GASTÓN , SIMEONE CLAUDIO
Published: May 2003

A global phase time is identified for homogeneous and isotropic cosmological models yielding from the low energy effective action of closed bosonic string theory. When the Hamiltonian constraint allows for the existence of an intrinsic time, the quantum transition amplitude is obtained by means of the usual path integral procedure for gauge systems.
FROISSART–MARTIN BOUND IN SPACES WITH COMPACT EXTRA DIMENSIONS
Authors: PETROV V. A.
Published: May 2003

We generalize the Froissart–Martin upper bound for the scattering amplitude in spaces with compactified extra dimensions.
CMB WITH QUINTESSENCE: ANALYTIC APPROACH AND CMBFAST
Authors: CROOKS JAMES L. , DUNN JAMES O. , FRAMPTON PAUL H. , NG Y. JACK , ROHM RYAN M.
Published: May 2003

A particular kind of quintessence is considered, with equation of motion pQ/ρQ=-1, corresponding to a cosmological term with time-dependence Λ(t)=Λ(t0)(R(t0)/R(t))P which we examine initially for 0≤P<3. Energy conservation is imposed, as is consistency with big-bang nucleosynthesis, and the range of allowed P is thereby much restricted to 0≤P<0.2. The position of the first Doppler peak is computed analytically and the result combined with analysis of high-Z supernovae to find how values of Ωm and ΩΛ depend on P. Some comparison is made to the CMBFAST public code.
QUANTUM CORRECTIONS TO THE ENTROPY OF EXTREME REISSNER–NORDSTRÖM BLACK HOLES
Authors: QIU WEIGANG , XU JIANJUN , SU RU-KENG , WANG BIN
Published: May 2003

Using brick wall model, the first quantum corrections to the extreme Reissner–Nordström black hole entropy due to scalar field as well as electromagnetic field have been calculated. Different quantum entropy values have been obtained for two different kinds of extreme black holes.
MASS EFFECTS ON THE NUCLEON SEA STRUCTURE FUNCTIONS
Authors: KIM SUN MYONG
Published: May 2003

Nucleon sea structure functions are studied using Dokshitzer–Gribov–Lipatov–Altarelli–Parisi (DGLAP) equations with the massive gluon–quark splitting kernels for strange and charm quarks, the massless gluon–quark splitting kernels for up and down quarks, and the massless kernels for all other splitting parts. The SU (2)f flavor symmetry for two light quarks, "up" and "down", is assumed. Glück–Reya–Vogt (GRV) and Martin–Roberts–Stirling (MRS) sets are chosen to be the base structure functions at [Formula: see text]. We evolve the sea structure functions from [Formula: see text] to Q2= 50 GeV 2 using the base structure function sets and DGLAP equations. Some (about 10%) enhancement is found in the strange quark distribution functions at low x (<0.1) in leading order of the DGLAP equations compared to results directly from those structure function sets at the value of Q2=50 GeV 2. We provide the value of κ and also show the behavior of [Formula: see text] after the evolution of structure functions.
TENSOR–SCALAR TORSION
Authors: GRUVER CHARRO , HAMMOND RICHARD , KELLY P. F.
Published: May 2003

A theory of gravity with torsion is examined in which the torsion tensor is constructed from the exterior derivative of an antisymmetric rank-two potential plus the dual of the gradient of a scalar field. Field equations for the theory are derived by demanding that the action be stationary under variations with respect to the metric, the antisymmetric potential, and the scalar field. A material action is introduced and the equations of motion are derived. The correct conservation law for rotational angular momentum plus spin is observed to hold in this theory.
EXACT SOLUTION OF THE SCHWINGER MODEL WITH COMPACT U(1)
Authors: LINARES ROMÁN , URRUTIA LUIS F. , VERGARA J. DAVID
Published: May 2003

The exact solution of the Schwinger model with compact gauge group U(1) is presented. The compactification is imposed by demanding that the only surviving true electromagnetic degree of freedom c has angular character. Not surprisingly, this topological condition defines a version of the Schwinger model which is different from the standard one, where c takes values on the line. The main consequences are: The spectra of the zero modes is not degenerated and does not correspond to the equally spaced harmonic oscillator, both the electric charge and a modified gauge-invariant chiral charge are conserved (nevertheless, the axial-current anomaly is still present) and, finally, there is no need to introduce a θ-vacuum. A comparison with the results of the standard Schwinger model is pointed out along the text.
THE RATIOS OF ENERGY LOSSES THROUGH PHOTONEUTRINO PROCESS IN SUPERSTRING INSPIRED E6 MODEL AND IN THE STANDARD MODEL
Authors: AYDEMIR AYTEKIN , AYDIN COSKUN , SEVER RAMAZAN
Published: May 2003

In general E6 inspired model which has two additional U(1) symmetries at the string scale whose one combination is a light enough vector boson Z(θ), we compute the contribution of Zθ to the [Formula: see text] scattering at the aim of calculating the energy loss. We find that the two U(1)'s must be combined at 90° to have a significant contribution.
THE EINSTEIN EQUATION IN A THEORY OF STRINGS
Authors: KAR SAYAN
Published: May 2003

We show, using purely classical considerations and logical extrapolation of results belonging to point particle theories, that the metric background field in which a string propagates must satisfy an Einstein or an Einstein-like equation. Additionally, there emerge restrictions on the worldsheet curvature, which seems to act as a source for space–time gravity, even in the absence of other matter fields.
MACROLENSING SIGNATURES OF LARGE-SCALE VIOLATIONS OF THE WEAK ENERGY CONDITION
Authors: SAFONOVA MARGARITA , TORRES DIEGO F. , ROMERO GUSTAVO E.
Published: May 2003

We present a set of simulations of the macrolensing effects produced by large-scale cosmological violations of the energy conditions. These simulations show how the appearance of a background field of galaxies is affected when lensed by a region with an energy density equivalent to a negative mass ranging from 1012 to 1017|M⊙|. We compare with the macrolensing results of equal amounts of positive mass, and show that, contrary to the usual case where tangential arc-like structures are expected, there appear radial arcs — runaway filaments — and a central void. These results make the cosmological macrolensing produced by space–time domains where the weak energy conditions are violated, observationally distinguishable from standard regions. Whether large domains with negative energy density indeed exist in the universe can now be decided by future observations of deep fields.
FIELD REDEFINITION INVARIANCE IN QUANTUM FIELD THEORY
Authors: APFELDORF KARYN M. , CAMBLONG HORACIO E. , ORDÓÑEZ CARLOS R.
Published: May 2003

The issue of field redefinition invariance of path integrals in quantum field theory is re-examined. A "paradox" is presented involving the reduction to an effective quantum-mechanical theory of a (d+1)-dimensional free scalar field in a Minkowskian space–time with compactified spatial coordinates. The implementation of field redefinitions both before and after the reduction suggests that operator-ordering issues in quantum field theory should not be ignored.
ULTRALIGHT SCALARS AND SPIRAL GALAXIES
Authors: DVALI GIA , GABADADZE GREGORY , SHIFMAN M.
Published: May 2003

We study some possible astrophysical implications of a very weakly coupled ultralight dilaton-type scalar field. Such a field may develop an (approximately stable) network of domain walls. The domain wall thickness is assumed to be comparable with the thickness of the luminous part of the spiral galaxies. The walls provide trapping for galactic matter. This is used to motivate the very existence of the spiral galaxies. A zero-mode existing on the domain wall is a massless scalar particle confined to (1+2) dimensions. At distances much larger than the galaxy/wall thickness, the zero-mode exchange generates a logarithmic potential, acting as an additional term with respect to Newton's gravity. The logarithmic term naturally leads to constant rotational velocities at the periphery. We estimate the scalar field coupling to the matter energy–momentum tensor needed to fit the observable flat rotational curves of the spiral galaxies. The value of this coupling turns out to be reasonable — we find no contradiction with the existing data.
DUAL METRICS FOR A CLASS OF RADIATIVE SPACE–TIMES
Authors: BĂLEANU D. , BAŞKAL S.
Published: May 2003

Second-rank nondegenerate Killing tensors for some subclasses of space–times admitting parallel null one-planes are investigated. Lichnérowicz radiation conditions are imposed to provide a physical meaning to space–times whose metrics are described through their associated second-rank Killing tensors. Conditions under which the dual space–times retain the same physical properties are presented.
BOUNDING THE TAU NEUTRINO MAGNETIC MOMENT FROM THE PROCESS $e^+e^-\rightarrow\gamma\nu\bar\nu$
Authors: AYDEMIR AYTEKIN , SEVER RAMAZAN
Published: May 2003

In a class of E6 inspired models with a light additional neutral vector boson, we discuss the effects of the magnetic moment of the tau neutrino by analyzing [Formula: see text] at the Z-pole. We take into account present scenarios for the extra Abelian group and vary extra neutral gauge boson mass beyond the present experimental exclusion limits. The present LEP experimental results prove that we can set an upper bound on the magnetic moment of the tau neutrino: κντ≤ 1.83× 10-6.
UNIFYING GAUGE INTERACTION AND GRAVITY IN A TOY MODEL
Authors: LIU YAO-YANG , SUN LA-ZHEN , ZHANG YUAN-ZHONG , JIANG XIANG-DONG
Published: May 2003

A supersymmetric vector-like standard model without leptons is suggested to investigate the unification between gauge interactions and gravity under two-loop approximation for gauge interactions and one-loop string correction for gravitation. It is found that two intermediate mass scales are needed where the lower mass scale may be accessible in laboratory in future and the higher mass scale is of the order of 1016 GeV .
CP VIOLATION IN NEUTRINO MIXING MATRIX AND LEPTOGENESIS
Authors: LIU YONG , SARKAR UTPAL
Published: May 2003

The CP violation required in leptogenesis may have different origin, but in an effective theory they are all related to the rephasing invariant CP violating measures in the mixing matrix of the leptonic sector. We point out that with our present knowledge of the mixing angles it is possible to estimate the maximum allowed value for all the rephasing invariant measures of CP violation in the leptonic sector. In the effective three-generation scenario there are three CP violating rephasing invariant measures. We show that only one rephasing invariant measure enters the lepton number conserving processes while the other two enter the lepton number violating processes. In the bimaximal mixing case, the lepton number conserving measure of CP violation vanishes while the two lepton number violating rephasing invariant measures of CP violation remain nonzero, which could contribute to the lepton asymmetry of the universe.
CHIRAL STRING IN A CURVED SPACE: GRAVITATIONAL SELF-ACTION
Authors: GRATS YU. V. , ROSSIKHIN A. A. , SBOICHAKOV A. O.
Published: May 2003

We analyze the effective action describing the linearized gravitational self-action for a classical superconducting string in a curved space–time. It is shown that the divergent part of the effective action is equal to zero for both Nambu–Goto and chiral super-conducting strings.
NUCLEUS POLARIZABILITY CONTRIBUTION TO THE HYDROGEN–DEUTERIUM ISOTOPE SHIFT
Authors: FAUSTOV R. N. , MARTYNENKO A. P.
Published: May 2003

The correction to the hydrogen–deuterium isotope shift due to the proton and deuteron polarizability is evaluated on the basis of modern experimental data on the structure functions of inelastic lepton–nucleus scattering. The numerical value of this contribution is equal to 63 ± 12 Hz.
SLAVNOV–TAYLOR IDENTITY FOR NONEQUILIBRIUM QUARK–GLUON PLASMA
Authors: OKANO K.
Published: May 2003

Within the closed-time-path formalism of nonequilibrium QCD, we derive a Slavnov–Taylor (ST) identity for the gluon polarization tensor. The ST identity takes the same form in both Coulomb and covariant gauges. Application to quasi-uniform quark–gluon plasma (QGP) near equilibrium or nonequilibrium quasistationary QGP is made.
DETECTION OF NEUTRINOS FROM PHOTONS AT HIGH REDSHIFT
Authors: GUPTA NAYANTARA , BHATTACHARYYA D. P.
Published: May 2003

We have calculated the neutrino induced muon events in kilometer scale neutrino telescope from neutrinos produced by photons emitted from relic particles, monopolonium and necklaces at high redshift as suggested by Kusenko and Postma. The atmospheric background neutrino flux has also been calculated using the primary nucleon spectra from latest measurements of JACEE near the top of the atmosphere.
A PHYSICAL EXPLANATION FOR THE TILDE SYSTEM IN THERMO FIELD DYNAMICS
Authors: MI DONG , SONG HE-SHAN , AN YING
Published: May 2003

For a two-body quantum system, any pure state can be represented by a biorthogonal expression by means of Schmidt decomposition. Using this in the composite system which includes a thermodynamic system and its surroundings, it is found that the tilde system in thermo field dynamics is just the surroundings of the real system.
METHOD OF COMPLEX PATHS AND GENERAL COVARIANCE OF HAWKING RADIATION
Authors: SHANKARANARAYANAN S. , SRINIVASAN K. , PADMANABHAN T.
Published: May 2003

We apply the technique of complex paths to obtain Hawking radiation in different coordinate representations of the Schwarzschild space–time. The coordinate representations we consider do not possess a singularity at the horizon unlike the standard Schwarzschild coordinate. However, the event horizon manifests itself as a singularity in the expression for the semiclassical action. This singularity is regularized by using the method of complex paths and we find that Hawking radiation is recovered in these coordinates indicating the covariance of Hawking radiation. This also shows that there is no correspondence between the particles detected by the model detector and the particle spectrum obtained by the quantum field theoretic analysis — a result known in other contexts as well.
ON THE AMPLIFICATION OF COSMOLOGICAL NON-MAXWELLIAN FIELDS IN CURVED BACKGROUND
Authors: OLIVEIRA A. L.
Published: May 2003

We study the influence of the gravitational field of Friedmann geometries upon an electromagnetic potential, through the Proca electromagnetic theory in a Dirac æther. The results are compared with those as foreseen by the Maxwellian theory in curved space–time. Our findings show that strong amplification effects of electromagnetic fields are a distinctive possibility. Thence we discuss some related topics.
DUAL BRST SYMMETRY FOR QED
Authors: MALIK R. P.
Published: May 2003

We show the existence of a co(dual)-BRST symmetry for the usual BRST invariant Lagrangian density of an Abelian gauge theory in two dimensions of space–time where a U(1) gauge field is coupled to the Noether conserved current (constructed by the Dirac fields). Under this new symmetry, it is the gauge-fixing term that remains invariant and the symmetry transformations on the Dirac fields are analogous to the chiral transformations. This interacting theory is shown to provide a tractable field theoretical model for the Hodge theory. The Hodge dual operation is shown to correspond to a discrete symmetry in the theory and the extended BRST algebra for the generators of the underlying symmetries turns out to be reminiscent of the algebra obeyed by the de Rham cohomology operators of differential geometry.
CREATION OF OPEN UNIVERSES AND CFT/AdS DUALITY
Authors: BOUHMADI MARIAN , GARAY LUIS J. , GONZÁLEZ-DÍAZ PEDRO F.
Published: May 2003

By replacing the singularity of the Hawking–Turok instanton for a regular asymptotically anti-de Sitter Euclidean wormhole, we conjecture that there may exist a holographic duality between CFT on the boundary of anti-de Sitter space and the Lorentzian isotropic open universes obtained by continuing the wormhole instanton according to the Hawking–Turok prescription.
INAPPROPRIATENESS OF THE RINDLER QUANTIZATION
Authors: NIKOLIĆ HRVOJE
Published: May 2003

It is argued that the Rindler quantization is not a correct approach to study the effects of acceleration on quantum fields. First, the "particle"-detector approach based on the Minkowski quantization is not equivalent to the approach based on the Rindler quantization. Second, the event horizon, which plays the essential role in the Rindler quantization, cannot play any physical role for a local noninertial observer.
ON RELATION BETWEEN WEYL AND KONTSEVICH QUANTUM PRODUCTS: DIRECT EVALUATION UP TO THE ℏ3-ORDER
Authors: ZOTOV A.
Published: May 2003

In his celebrated paper Kontsevich has proved a theorem which manifestly gives a quantum product (deformation quantization formula) and states that changing coordinates leads to gauge equivalent star products. To illuminate his procedure, we make an arbitrary change of coordinates in the Weyl (Moyal) product and obtain the deformation quantization formula up to the third order. In this way, the Poisson bivector is shown to depend on ℏ and not to satisfy the Jacobi identity. It is also shown that the values of coefficients in the formula obtained follow from associativity of the star product.
CANONICAL APPROACH TO 2D INDUCED GRAVITY
Authors: POPOVIĆ D. S. , SAZDOVIĆ B.
Published: May 2003

Using canonical method the Liouville theory has been obtained as a gravitational Wess–Zumino action of the Polyakov string. From this approach it is clear that the form of the Liouville action is the consequence of the bosonic representation of the Virasoro algebra, and that the coefficient in front of the action is proportional to the central charge and measures the quantum braking of the classical symmetry.
AMBIGUITY IN SOURCE FLUX OF COSMIC/ASTROPHYSICAL NEUTRINOS: EFFECTS OF BI-MAXIMAL MIXING AND QUANTUM-GRAVITY INDUCED DECOHERENCE
Authors: AHLUWALIA D. V.
Published: May 2003

For high energy cosmic neutrinos Athar, Jeźabek, and Yasuda (AJY) have recently shown that the existing data on neutrino oscillations suggest that cosmic neutrino flux at the AGN/GRB source, F(νe):F(νμ):F(ντ) ≈ 1:2:0, oscillates to F(νe):F(νμ):F(ντ) ≈ 1:1:1. These results can be confirmed at AMANDA, Baikal, ANTARES and NESTOR, and other neutrino detectors with a good flavor resolution. Here, we rederive the AJY result from quasi bi-maximal mixing, and show that observation of F(νe):F(νμ):F(ντ) ≈ 1:1:1 does not necessarily establish cosmic neutrino flux at the AGN/GRB source to be F(νe):F(νμ):F(ντ) ≈ 1:2:0. We also note that if the length scale for the quantum-gravity induced decoherence for astrophysical neutrinos is of the order of a Mpc, then independent of the MNS matrix, the Liu–Hu–Ge (LHG) mechanism would lead to flux equalization for the cosmic/astrophysical neutrinos.
PARTICLE CREATION BY MOVING SPHERICAL SHELL IN THE DYNAMICAL CASIMIR EFFECT
Authors: SETARE M. R. , SAHARIAN A. A.
Published: May 2003

The creation of massless scalar particles from the quantum vacuum by spherical shell with time varying radius is studied. In the general case of motion the equations are derived for the instantaneous basis expansion coefficients. The examples are considered when the mean number of particles can be explicitly evaluated in the adiabatic approximation.
BLACK HOLE PHYSICS, CONFINING SOLUTIONS OF SU(3)-YANG– MILLS EQUATIONS AND RELATIVISTIC MODELS OF MESONS
Authors: GONCHAROV YU. P.
Published: May 2003

The black hole physics techniques and results are applied to find a set of exact solutions of the SU(3)-Yang–Mills equations in Minkowski space–time in the Lorentz gauge. All the solutions contain only the Coulomb-like or linear in r components of SU(3)-connection. This allows one to obtain some possible exact and approximate solutions of the corresponding Dirac equation that can describe the relativistic bound states. Possible application to the relativistic models of mesons is also outlined.
EXACT SOLUTIONS FOR SELF-DUAL SU(2) GAUGE THEORY WITH AXIAL SYMMETRY
Authors: ZET G. , MANTA V. , BANDAC C.
Published: May 2003

A model of SU(2) gauge theory is constructed in terms of local gauge-invariant variables defined over a four-dimensional space–time endowed with axial symmetry. A metric tensor gμν is defined starting with the components [Formula: see text] of the strength tensor and its dual [Formula: see text]. The components gμν are interpreted as new local gauge-invariant variables. Imposing the condition that the new metric coincides with the initial metric we obtain the field equations for the considered ansatz. We obtain the same field equations using the condition of self-duality. It is concluded that the self-dual variables are compatible with the axial symmetry of the space–time. A family of analytical solutions of the gauge field equations is also obtained. The solutions have the confining properties. All the calculations are performed using the GRTensorII computer algebra package, running on the MapleV platform.