November 1995 arXiv papers — page 2

Fabio Siringo, Renato Pucci, Giuseppe G. N. Angilella

The extended Hubbard Hamiltonian on a bcc lattice is studied at half-filling and for a finite hopping between next-nearest-neighbours, in mean-field approximation. An ionic insulating broken-symmetry phase is predicted for any hydrogenoid bcc solid in the density range 1.0 < r sub s < 2.6. The occurrence of an ionic phase would explain the failure to achieve

Cecilia Noguez, Sergio E. Ulloa

The optical properties of the 2$\times$1 reconstruction of the diamond (111) surface are investigated. The electronic structure and optical properties of the surface are studied using a microscopic tight-binding approach. We calculate the dielectric response describing the surface region and investigate the origin of the electronic transitions involving surf

R. K. Kamilla, X. G. Wu, J. K. Jain

The low energy neutral excitations of incompressible fractional quantum Hall states are called collective modes or magnetic excitons. This work develops techniques for computing their dispersion at general filling fractions for reasonably large systems. New structure is revealed; in particular, the collective mode at 1/3 is found to possess several minima, w

V. A. Kalatsky, V. L. Pokrovsky

We present a theory of the magnetic rare-earth nickel boride-carbides (RENi$_2$B$_2$C, RE=Ho, Er, Tm). Large total angular momentum allows one to employ semiclassical approximation and reduce the problem to the four-positional clock model. The latter gives a proper phase diagram in magnetic field-magnetic moment plane for varying directions of in-plane magne

E. L. Pollock, Jim Glosli

The three most common methods, Ewald, fast multipole (FMM) and the particle-particle particle-mesh (PPPM), used to compute the interactions in many body Coulombic systems are compared for single and multi-processor machines. The Ewald method is recommended for systems of a few hundred particles per processor or less. For larger systems the PPPM method is sug

Philip Resnik

This paper presents a new measure of semantic similarity in an IS-A taxonomy, based on the notion of information content. Experimental evaluation suggests that the measure performs encouragingly well (a correlation of r = 0.79 with a benchmark set of human similarity judgments, with an upper bound of r = 0.90 for human subjects performing the same task), and

Philip Resnik

Word groupings useful for language processing tasks are increasingly available, as thesauri appear on-line, and as distributional word clustering techniques improve. However, for many tasks, one is interested in relationships among word {\em senses}, not words. This paper presents a method for automatic sense disambiguation of nouns appearing within sets of

WonIl Lee, Geunbae Lee, Jong-Hyeok Lee

While most of the speech and natural language systems which were developed for English and other Indo-European languages neglect the morphological processing and integrate speech and natural language at the word level, for the agglutinative languages such as Korean and Japanese, the morphological processing plays a major role in the language processing since

M. Daoud, M. Kibler

Magnetic- and electric-dipole two-photon absorption (MED-TPA), recently introduced as a new spectroscopic technique for studying transitions between states of opposite parities, is investigated from a theoretical point of view. A new approximation, referred to as {\it weak quasi-closure approximation}, is used together with symmetry adaptation techniques to

Ben Moore

The detection of stars in the process of being tidally removed from globular clusters and dwarf spheroidals in the Galaxy&#39;s halo provides a strong constraint on their mass to light ratios and on the extent of their possible dark matter halos. If a significant dark matter component existed either within or beyond the observed stellar distribution, then st

Maurice H. P. M. van Putten

Bright features (`knots&#39;) in extragalactic jets are commonly associated with reheating of charged particles in regions with shocks or strong compression. We find a natural appearance of nozzles in simulations of toroidally magnetized jets, and propose this as a generic mechanism of knotted structures such as in the jet of 0800+608. Nozzles provide correl

Marco Castellani, Gianni Marconi, Roberto Buonanno

Deep CCD photometry (NTT, HST data) for the dwarf galaxy in Tucana is presented, down to V=27.5. Distance modulus and metallicity are derived, together with an estimate of the age of the galaxy.

Richard Easther

We present a new, exact scalar field cosmology for which the spectrum of scalar (density) perturbations can be calculated exactly. We use this exact result to the probe the accuracy of approximate calculations of the perturbation spectrum.

F. X. Timmes, S. E. Woosley, D. H. Hartmann, R. D. Hoffman

The production of the radioactive isotopes $^{44}$Ti and $^{60}$Co in all types of supernovae is examined and compared to observational constraints including Galactic $γ$--ray surveys, measurements of the diffuse 511 keV radiation, $γ$--ray observations of Cas A, the late time light curve of SN 1987A, and isotopic anomalies found in silicon carbide grains in

Simon P. Driver, Rogier A. Windhorst, Steven Phillipps, Paul D. Bristow

The interpretation of galaxy number counts in terms of cosmological models is fraught with difficulty due to uncertainties in the overall galaxy population (mix of morphological types, luminosity functions etc.) and in the observations (loss of low surface brightness images, image blending etc.). Many of these can be overcome if we use deep high resolution i

N. Mohan Kumar

Many examples of rank two bundles on ${\bf P}^4$ are constructed in positive characteristic. Construction depends on constructing certain special bundles on ${\bf P}^3$ which is shown to be equivalent to constructing bundles on ${\bf P}^4$ (in any characteristic). In fact this is true for projective spaces of any dimension.

C. Barbero, J. M. Cline, F. Krmpotic, D. Tadic

We examine in detail the predictions of the charged majoron model, introduced recently by Burgess and Cline, for 0+ --> 0+ double beta decay transitions. The relevant nuclear matrix elements are evaluated, within the quasiparticle random phase approximation, for 76Ge, 82Se, 100Mo, 128Te and 150Nd nuclei. The calculated transition rates turn out to be much sm

Mark de Wild Propitius, F. Alexander Bais

In these lecture notes, we present a self-contained discussion of planar gauge theories broken down to some finite residual gauge group H via the Higgs mechanism. The main focus is on the discrete H gauge theory describing the long distance physics of such a model. The spectrum features global H charges, magnetic vortices and dyonic combinations. Due to the

Alexander Polishchuk

A generalization of the Fourier-Mukai transform is proposed. The construction is based on analogy with the classical picture of representations of the Heisenberg group.

Per Ernstrom, Ansar Fayyazuddin

The chiral Dirac determinant is calculated using the overlap formalism of Narayanan and Neuberger. We compare the real and imaginary parts of the determinant with the continuum result for perturbative gauge field backgrounds and show that they are identical. Thus we find that the overlap formalism passes a crucial test.

E. H. Simmons, R. S. Chivukula, J. Terning

We review the connection between $m_t$ and the $Zb\bar b$ vertex in ETC models and discuss the resulting experimental constraint on models with weak-singlet ETC bosons. We mention several recent efforts to bring ETC models into agreement with this constraint, and explore the most promising one (non-commuting ETC) in detail.

Gardo Garnet Blado

The ring-shaped Hartmann potential $V = ησ^{2} ε_{0} \left( \frac{2 a_{0}}{r} - \frac{ηa_{0}^{2}}{r^{2} sin^{2} θ} \right)$ was introduced in quantum chemistry to describe ring-shaped molecules like benzene. In this article, fundamental concepts of supersymmetric quantum mechanics (SUSYQM) are discussed. The energy eigenvalues and (radial) eigenfunctions of

Fermin Aldabe

Recently, it was shown that zero modes in semiclassical soliton models do not lead to Yukawa couplings. We show that taking into account the contributions of the quantum soliton into the renormalization scheme, which cannot be done in semiclassical treatments, leads to a Yukawa coupling. A similar analysis should be possible for the Skyrmion, renewing the ho

Fermin Aldabe

I show that plane waves may not be used as asymptotic states in soliton models because they describe unphysical states. When asymptotic states are taken to be physical there is no T-matrix of $\cO(1)$.

K. Langanke, P. Vogel, E. Kolbe

We suggest that photons with energies between 5 and 10 MeV, generated by the ($ν,ν&#39;pγ$) and ($ν,ν&#39;nγ$) reactions on $^{16}$O, constitute a signal which allows a unique identification of supernova $ν_μ$ and $ν_τ$ neutrinos in water Čerenkov detectors. We calculate the yield of such $γ$ events and estimate that a few hundred of them would be detected i

Derek B. Leinweber, Xuemin Jin, R. J. Furnstahl

New QCD sum rules for nucleons in nuclear matter are derived from a mixed correlation function of spin-1/2 and spin-3/2 interpolating fields. These sum rules allow a determination of the scalar self-energy of the nucleon independent of the poorly known four-quark condensates. An analysis of these new sum rules in concert with previous nucleon sum rules from

J. Geiss, S. Hardt, H. Lenske, U. Mosel

Excited states of the nucleon are described as RPA configurations on a mean--field ground state taken from the MIT bag model. A residual interaction of a structure as in the Nambu--Jona--Lasinio model is used. The particle-hole states are coupled to good total angular momentum and isospin. Valence excitations of particle-hole type and quark--antiquark ($q\ov

W. C. Haxton

The addition of certain solutes to a water Cerenkov detector will introduce new charge-current channels for the detection of $ν_e$s. The experimental conditions necessary to exploit such signals - large volumes and very low backgrounds - should be reached for the first time in SuperKamiokande and SNO. I compare some of the more attractive possibilities ($^7$

Dmitry V. Alekseevsky, Vicente Cortés

We classify extended Poincaré Lie super algebras and Lie algebras of any signature (p,q), that is Lie super algebras and Z_2-graded Lie algebras g = g_0 + g_1, where g_0 = so(V) + V is the (generalized) Poincaré Lie algebra of the pseudo Euclidean vector space V = R^{p,q} of signature (p,q) and g_1 = S is the spinor so(V)-module extended to a g_0-module with

Vladimir V. Peller, Nicholas J. Young

Let $\A$ be the operator which assigns to each $m \times n$ matrix-valued function on the unit circle with entries in $H^\infty + C$ its unique superoptimal approximant in the space of bounded analytic $m \times n$ matrix-valued functions in the open unit disc. We study the continuity of $\A$ with respect to various norms. Our main result is that, for a clas

Daniel Gallo, Michael Kapovich, Albert Marden

Let θ:π_1(R) \to \PSL(2,\C) be a homomorphism of the fundamental group of an oriented, closed surface R of genus exceeding one. We will establish the following theorem. Theorem. Necessary and sufficient for θto be the monodromy representation associated with a complex projective stucture on R, either unbranched or with a single branch point of order 2, is th

Michael Christ, Song-Ying Li

No abstract available.

Michael Christ

No abstract available.

M. S. Baouendi, P. Ebenfelt, Linda Preiss Rothschild

We give conditions under which a germ of a holomorphic mapping in $\Bbb C^N$, mapping an irreducible real algebraic set into another of the same dimension, is actually algebraic. Let $A\subset \bC^N$ be an irreducible real algebraic set. Assume that there exists $\po \in A$ such that $A$ is a minimal, generic, holomorphically nondegenerate submanifold at $\p

John R. Klauder

Standard lattice-space formulations of quartic self-coupled Euclidean scalar quantum fields become trivial in the continuum limit for sufficiently high space-time dimensions, and in particular the moment generating functional for space-time smeared fields becomes a Gaussian appropriate to that of a (possibly generalized) free field. For sharp-time fields thi

Kris Thielemans, Stefan Vandoren

We investigate the gauging of conformal algebras with relations between the generators. We treat the $W_{5/2}$--algebra as a specific example. We show that the gauge-algebra is in general reducible with an infinite number of stages. We show how to construct the BV-extended action, and hence the classical BRST charge. An important conclusion is that this can

L. D. Paniak, G. W. Semenoff, R. J. Szabo

We derive a geometric integration formula for the partition function of a classical dynamical system and use it to show that corrections to the WKB approximation vanish for any Hamiltonian which generates conformal motions of some Riemannian geometry on the phase space. This generalizes previous cases where the Hamiltonian was taken as an isometry generator.

Diego Bellisai

In presence of string solitons, index theorems for the generalised Dirac operators have to be revisited. We show that in supersymmetric configurations the fermionic operators decouple, so that there are no mixing effects between different fermions in the index theorems. We extend the index theorems in presence of torsion to the generic case of manifolds with

Kimball A. Milton

Recently it was shown how to formulate the finite-element equations of motion of a non-Abelian gauge theory, by gauging the free lattice difference equations, and simultaneously determining the form of the gauge transformations. In particular, the gauge-covariant field strength was explicitly constructed, locally, in terms of a path ordered product of expone

Ambar Ghosal, Asim K. Ray

We demonstrate that almost degenerate Dirac neutrinos of mass of few eV and transition magnetic moment of the order of ${10}^{-11}$ $μ_B$ can be obtained in an ${SU(2)}_L\times {U(1)}_Y$ model with $S_3\times Z_3\times Z_4$ discrete symmetry and appropriate Higgs fields. Transition magnetic moment of the Dirac neutrino arises from to the contribution of lept

Martina Brisudova, Robert Perry

We present the first numerical QCD bound state calculation based on a renormalization group-improved light-front Hamiltonian formalism. The QCD Hamiltonian is determined to second order in the coupling, and it includes two-body confining interactions. We make a momentum expansion, obtaining an equal-time-like Schrodinger equation. This is solved for quark-an

Frank E. Close

Lectures at VII Jorge Andre Swieca Summer School in Nuclear Physics; Brasil; Jan 22 - Feb 4 1995. To be published by Plenum Press (C.A.Amaral Nunes ed.)

W. I. Giersche, C. R. Munz

The electromagnetic form factor for the $K^0$ is calculated in a covariant formulation of the Salpeter equation for $q\bar q$ - bound states, which has been presented recently for the mass spectrum, decay properties and form factors of the light pseudoscalar and vector mesons. The $K^0$ charge radius dependence on the difference between strange and down cons

F. O. Duraes, F. S. Navarra, C. A. A. Nunes, G. Wilk

We discuss leading charm production in connection with energy deposition in the central rapidity region. Special attention is given to the correlation between production in central and fragmentation regions. If the fraction of the reaction energy released in the central region increases the asymmetry in the $x_F$ distributions of charmed mesons will become s

Chris Quigg

Opening Lecture at the Second Rencontres du Vietnam, October 21-28, 1995.

Ludger Hannibal

It is shown that if antiparticles are realized in quantum field theory by negative frequency states, which nevertheless have positive energy density, the resulting theory provides a qualitative explanation for the experiments on the neutral K mesons, without assumming any symmetry violation.

Georges Grunberg

The connection between renormalons and power corrections is investigated for the typical infrared renormalon integral assuming the effective coupling constant has an infrared fixed point of an entirely perturbative origin. It is shown the full answer differs from the Borel sum by a power correction.

A. Arbuzov, D. Bardin, J. Bluemlein, L. Kalinovskaya

A description of the Fortran program HECTOR for a variety of semi-analytical calculations of radiative QED, QCD, and electroweak corrections to the double-differential cross sections of NC and CC deep inelastic charged lepton proton (or lepton deuteron) scattering is presented. HECTOR originates from the substantially improved and extended earlier programs H

R. M. Godbole, D. P. Roy, K. Sridhar

We compute the contributions to large-$p_T$ $J/ψ$ production at HERA coming from fragmentation of gluons and charm quarks. We find that the charm quark fragmentation contribution dominates over the direct production of $J/ψ$ via photon-gluon fusion at large-$p_T$, while the gluon fragmentation is negligibly small over the whole range of $p_T$. An experimenta

Francesco Murgia, Paul Kessler, Joseph Parisi

Using a non--relativistic gluon bound--state model for glueballs (G), we compute the subprocess $q\,\bar q\, \to\, G\,π$, and we therefrom derive the yield of the overall reaction $p\,\bar p\, \to\, G\,πX$, assuming the glueball and the pion to be emitted with their transverse momenta large, opposite and approximately equal. Numerical results are presented i

T. Hotta, K. -I. Izawa, T. Yanagida

We propose a supersymmetric hypercolor SU(3)_H gauge theory interacting strongly at the grand unification scale, in which the hyperquark condensation breaks SU(5)_GUT down to SU(3)_C x SU(2)_L without unbroken U(1)_Y at the classical level. However, we show that the broken U(1)_Y symmetry is restored by quantum mechanical effects and hence there remains the

K. G. Chetyrkin, J. H. Kuehn, M. Steinhauser

The real and imaginary part of the vacuum polarisation function $Π(q^2)$ induced by a massive quark is calculated in perturbative QCD up to order $α_s^2$. The method is described and the results are presented. This extends the calculation by Källén and Sabry from two to three loops.

Noriyuki Oshimo

We discuss CP asymmetries in $B^0$-meson decays and \BsBs mixing within the framework of the supersymmetric standard model (SSM). It is shown that \BdBd and \KK mixings could receive sizable new contributions through box diagrams mediated by the charginos and charged Higgs bosons. This implies that the CP-violating phase of the Cabibbo-Kobayashi-Maskawa matr

S. Hashimoto, H. Matsufuru

We compute the Isgur-Wise function using heavy quark effective theory formulated on the lattice. The non-relativistic kinetic energy term of the heavy quark is included to the action as well as terms remaining in the infinite quark mass limit. The classical velocity of the heavy quark is renormalized on the lattice and we determine the renormalized velocity

Antonio Campos, Enric Verdaguer

Semiclassical Einstein-Langevin equations for arbitrary small metric perturbations conformally coupled to a massless quantum scalar field in a spatially flat cosmological background are derived. Use is made of the fact that for this problem the in-in or closed time path effective action is simply related to the Feynman and Vernon influence functional which d

B. L. Hu

Developments in theoretical cosmology in the recent decades show a close connection with particle physics, quantum gravity and unified theories. Answers or hints to many fundamental questions in cosmology like the homogeneity and isotropy of the Universe, the sources of structure formation and entropy generation, and the initial state of the Universe can be

B. L. Hu

We note that in general there exist two basic aspects in any branch of physics, including cosmology - one dealing with the attributes of basic constituents and forces of nature, the other dealing with how structures arise from them and how they evolve. Current research in quantum and superstring cosmology is directed mainly towards the first aspect, even tho

B. L. Hu

In recent years a statistical mechanics description of particles, fields and spacetime based on the concept of quantum open systems and the influence functional formalism has been introduced. It reproduces in full the established theory of quantum fields in curved spacetime and contains also a microscopic description of their statistical properties, such as

O. Klein, D. Goldhaber-Gordon, C. de C. Chamon, M. A. Kastner

The temperature dependence of conductance resonances is used to measure the evolution with the magnetic field of the average level spacing $Δε$ of a droplet containing $\sim 30$ electrons created by lateral confinement of a two-dimensional electron gas in GaAs. $Δε$ becomes very small ($< 30μ$eV) near two critical magnetic fields at which the symmetry of the

A. Honecker, I. Peschel

The one-dimensional forest-fire model including lightnings is studied numerically and analytically. For the tree correlation function, a new correlation length with critical exponent ν~ 5/6 is found by simulations. A Hamiltonian formulation is introduced which enables one to study the stationary state close to the critical point using quantum-mechanical pert

Gu Yan, Tom C. Lubensky

We use a set of simplified non-linear Langevin equations to study the hydrodynamic excitations in a nematic liquid crystal. We calculate the one-loop self-energy corrections in the long wavelength limit.

F. Bonetto, G. Gallavotti, G. Gentile, V. Mastropietro

Moser&#39;s invariant tori for a class of nonanalytic quasi integrable even hamiltonian systems are shown to be analytic in the perturbation parameter. We do so by exhibiting a summation rule for the divergent series (``Lindstedt series&#34;) that formally define them. We find additional cancellations taking place in the formal series, besides the ones alrea

Vishal Mehra, Ramakrishna Ramaswamy

We study the variation of Lyapunov exponents of simple dynamical systems near attractor-widening and attractor-merging crises. The largest Lyapunov exponent has universal behaviour, showing abrupt variation as a function of the control parameter as the system passes through the crisis point, either in the value itself, in the case of the attractor-widening c

Stephen D. Landy, Alexander S. Szalay, David C. Koo

We have studied galaxy two-point angular correlations as a function of color using 4-m plate photometry in two independent fields. Each field consists of over 2900 galaxies with magnitudes 20<B_J <23.5 in an area of approximately 750 arcmin^2 . We find that the autocorrelation amplitude of the bluest 15% of galaxies is surprisingly strong, with a relative in

Inger Jorgensen, Marijn Franx, Per Kjaergaard

We have analyzed the Fundamental Plane (FP) for a sample of 226 E and S0 galaxies in ten clusters of galaxies. For photometry in Gunn r the best fitting plane is log r_e=1.24 log sigma - 0.82 log <I>_e + cst. The scatter is 0.084 in log r_e. The slope of the FP is not significantly different from cluster to cluster. The residuals of the FP correlate weakly w

R. Canal, P. Ruiz-Lapuente, A. Burkert

The occurrence and properties of Type Ia supernovae (SNe Ia) in single-degenerate binary systems (white dwarf [WD] + nondegenerate companion) is examined for galaxies of different types, and as a function of redshift. The rates and characteristics (peak luminosities, expansion velocities of the ejecta) expected from the explosion of mass-accreting WDs in sym

S. Wallington, C. S. Kochanek, R. Narayan

We present a new algorithm for inverting poorly resolved gravitational lens systems using the maximum entropy method (MEM). We test the method with simulations and then apply it to an 8 GHz VLA map of the radio ring lens MG1654+134. We model the lens as a singular isothermal sphere embedded in an external shear field and find the critical radius of the lens

J. L. Zdunik

The role of direct URCA reactions in damping of the gravitational radiation driven instability is discussed. The temperature at which bulk viscosity suppresses completely this instability is calculated. The results are obtained analytically using recent calculations performed in the case of bulk viscosity due to the modified URCA processes (Lindblom 1995; Yo

Simon P. Driver, Rogier A. Windhorst, Richard E. Griffiths

We summarise recent Hubble Space Telescope results on the morphology of faint field galaxies. Our two principle results are: (1) the galaxies responsible for the faint blue excess have late-type/irregular morphology and (2) the number counts of normal galaxies, ellipticals and early-type spirals, are well fit by standard no-evolution models implying that the

Simon P. Driver, Rogier A. Windhorst, Richard E. Griffiths

We discuss the observations leading to the Faint Blue Galaxy problem and the uncertainties upon which faint galaxy models are based. Using deep Hubble Space Telescope (HST) imaging with the Wide Field Planetary Camera (WFPC2), we show how morphological information has been used to shed new light on the problem. Initial results indicate that the giant galaxie

Steven Phillipps, Simon P. Driver

Recent redshift surveys have shown that the excess galaxies seen in faint galaxy number counts (above those expected given the local galaxy luminosity function) are not evolved giants at high redshifts, but low to moderate luminosity objects at more modest redshifts. This has led to the suggestion that there was once an additional population of dwarf galaxie

Simon P. Driver, Rogier A. Windhorst, Eric J. Ostrander, William C. Keel

We determine the morphological mix of field galaxies down to $m_{I}\simeq 24.25$ mag ($m_{B}\sim 26.0$ mag) from a single ultradeep HST WFPC2 image in both the $V_{606}$ and $I_{814}$ filters. In total, we find 227 objects with $m_{I}\le 24.5$ mag and classify these into three types: ellipticals (16%), early-type spirals (37%) and late-type spirals/Irregular

A. Fernandez-Soto, X. Barcons, R. Carballo, J. K. Webb

The influence of a foreground QSO on the lyman a forest of another QSO with higher redshift has been investigated by analyzing the spectra of three such objects at redshifts $z=2 - 2.7$. This influence is not contaminated by any projection effects, as opposed to the inverse effect along the line of sight, where incomplete coverage of the QSO continuum emitti

Scott Axelrod

The large $k$ asymptotics (perturbation series) for integrals of the form $\int_{\cal F}\mu e^{i k S}$, where $\mu$ is a smooth top form and $S$ is a smooth function on a manifold ${\cal F}$, both of which are invariant under the action of a symmetry group ${\cal G}$, may be computed using the stationary phase approximation. This perturbation series can be e

Claude LeBrun

It is shown that there are infinitely many compact orientable smooth 4-manifolds which do not admit Einstein metrics, but nevertheless satisfy the strict Hitchin-Thorpe inequality 2 chi > 3 |tau|. The examples in question arise as non-minimal complex algebraic surfaces of general type, and the method of proof stems from Seiberg-Witten theory.

T. Banks, L. Susskind

The force between like sign BPS saturated objects generally vanishes. This is a reflection of the fact that BPS states are really massless uncharged particles with nonvanishing momenta in compactified directions. Two like sign BPS objects with zero relative velocity can be viewed as a boosted state of two neutral massless particles in a state of vanishing re

Michael Birkel, Harald Fritzsch

It is shown that the QCD anomaly may lead to an abnormal mixing behavior of the axial vector mesons similar to the pseudoscalar mesons. These mixing effects, involving a gluonic axial vector state, generate a non-vanishing strange quark component in the nucleon. They reduce the matrix element of the singlet axial vector in comparison to the value obtained in

D. Hadjimichef, G. Krein, S. Szpigel, J. S. da Veiga

Starting from the Fock space representation of hadron bound states in a quark model, a change of representation is implemented by a unitary transformation such that the composite hadrons are redescribed by elementary-particle field operators. Application of the unitary transformation to the microscopic quark Hamiltonian gives rise to effective hadron-hadron,

D. I. Kazakov, M. Yu. Kalmykov, I. N. Kondrashuk, A. V. Gladyshev

In the context of the standard SUSY GUT scenario, we present a detailed analysis of the softly broken finite supersymmetric grand unified theory. The model, albeit non-minimal, remains very rigid due to the requirement of finiteness. It is based on the $SU(5)$ gauge group and is UV finite to all orders of perturbation theory. It contains three generations of

José P. S. Lemos, Vilson T. Zanchin

Einstein-Maxwell equations with a cosmological constant are analyzed in a four dimensional stationary spacetime admitting in addition a two dimensional group $G_2$ of spatial isometries. Charged rotating open and closed black string solutions are found.

D. Poilblanc, T. Sakai, D. J. Scalapino, W. Hanke

Polaronic effects are investigated in the two dimensional t--J model (describing Cu spins and holes of the planes in high-$T_c$ cuprates) in the presence of in-plane dynamic oxygen breathing modes. We focus on the effect of dynamic multi-phonon modes. Spin and charge structure factors are computed. We found evidence for self-localisation of the holes and {\i

S. Komineas, N. Papanicolaou

A direct link between the topological complexity of ferromagnetic media and their dynamics has recently been established through the construction of unambiguous conservation laws as moments of a topological vorticity. In the present paper we carry out this program under completely realistic conditions, with due account of the long-range magnetostatic field a

A. Szomoru, J. H. van Gorkom, M. D. Gregg, M. A. Strauss

We discuss the results of a VLA HI survey of the Bootes void and compare the distribution and HI properties of the void galaxies to those of galaxies found in a survey of regions of mean cosmic density. The Bootes survey covers 1100 Mpc$^{3}$, or $\sim$ 1\% of the volume of the void and consists of 24 cubes of typically 2 Mpc * 2 Mpc * 1280 km/s, centered on

A. Szomoru, J. H. van Gorkom, M. D. Gregg

We present the results of a neutral hydrogen survey of the Bootes void carried out with the VLA in D-array. The survey covers $\sim 1100$ Mpc$^{3}$, about 1\% of the volume of the void as defined by Kirshner \etal 1987. We observed 24 fields, centered on known void galaxies; 16 of these were detected in HI. Eighteen uncataloged companion galaxies were discov

K. Hamacher, M. Weierstall

Event shape and charged particle inclusive distributions determined from 750 000 hadronic Z events measured with the DELPHI detector at LEP are presented. The statistical and systematic precision of this data allows for a decisive confrontation with Monte Carlo models of the hadronization process and a better understanding of the structure of the Z hadronic

E. Abdalla, M. C. B. Abdalla, K. D. Rothe

In this work we study the zero-charge sector of massive two-dimensional Quantum Chromodynamics in the decoupled formulation. We find that some general features of the massless theory, concerning the constraints and the right- and left-moving character of the corresponding BRST currents, survive in the massive case. The implications for the integrability prop

L. Rozansky

We present a mathematically clean review of our previous results on 1/K expansion of the colored Jones polynomial and on perturbative invariants of 3d rational homology spheres. We also prove that perturbative invariants defined through the stationary phase surgery formula are invariant under Kirby moves.

A. Kricker, B. Spence, I. Aitchison

We characterise the cabling operations on the weight systems of finite type knot invariants. The eigenvectors and eigenvalues of this family of operations are described over the cable eigenbasis. The action of immanent weight systems on general Feynman diagrams is considered, and the highest eigenvalue cabling eigenvectors are shown to be dual to the immanen

A. Losev, G. Moore, N. Nekrasov, S. Shatashvili

We present an explicit construction for the central extension of the group $\Map(X, G)$ where $X$ is a compact manifold and $G$ is a Lie group. If $X$ is a complex curve we obtain a simple construction of the extension by the Picard variety $\Pic(X)$. The construction is easily adapted to the extension of $\Aut(E)$, the gauge group of automorphisms of a nont

Phung Ho Hai

We show that a quantum super matrix in standard format is invertible if and only if its block matrices of even entries are invertible. We prove the q-analog of the well-known formula for the Berezinian.

L. S. F. Olavo

In our previous papers we were interested in making a reconstruction of quantum mechanics according to classical mechanics. In this paper we suspend this program for a while and turn our attention to a theme in the frontier of quantum mechanics itself---that is, the formation of operators. We then investigate all the subtleties involved in forming operators

Michel Dubois-Violette

We discuss in some generality aspects of noncommutative differential geometry associated with reality conditions and with differential calculi. We then describe the differential calculus based on derivations as generalization of vector fields, and we show its relations with quantum mechanics. Finally we formulate a general theory of connections in this frame

J&#34;urgen Fuchs, Bert Schellekens, Christoph Schweigert

We describe the resolution of field identification fixed points in coset conformal field theories in terms of representation spaces of the coset chiral algebra. A necessary ingredient from the representation theory of Kac Moody algebras is the recently developed theory of twining characters and orbit Lie algebras, as applied to automorphisms representing ide

Douglas A. Kurtze

In pattern forming systems such as Rayleigh-Benard convection or directional solidification, a large number of linearly stable, patterned steady states exist when the basic, simple steady state is unstable. Which of these steady states will be realized in a given experiment appears to depend on unobservable details of the system&#39;s initial conditions. We

Yurii I. Lyubarskii, Kristian Seip

We describe the complete interpolating sequences for the Paley-Wiener spaces $L^p_π$ ($1<p<\infty$) in terms of Muckenhoupt&#39;s $(A_p)$ condition. For $p=2$, this description coincides with those given by Pavlov (1979), Nikol&#39;skii (1980), and Minkin (1992) of the unconditional bases of complex exponentials in $L^2(-π,π)$. While the techniques of these

Mark de Wild Propitius

This thesis deals with planar gauge theories in which some gauge group G is spontaneously broken to a finite subgroup H. The spectrum consists of magnetic vortices, global H charges and dyonic combinations exhibiting topological Aharonov-Bohm interactions. Among other things, we review the Hopf algebra D(H) related to this residual discrete H gauge theory, w

T. Banks, L. Susskind

We discuss string theory vacua which have the wrong number of spacetime dimensions, and give a crude argument that vacua with more than four large dimensions are improbable. We then turn to two dimensional vacua, which naively appear to violate Bekenstein&#39;s entropy principle. A classical analysis shows that the naive perturbative counting of states is un

Gerald Dunne, Theodore Hall

We study the formation of vacuum condensates in $2+1$ dimensional QED in the presence of inhomogeneous background magnetic fields. For a large class of magnetic fields, the condensate is shown to be proportional to the inhomogeneous magnetic field, in the large flux limit. This may be viewed as a {\it local} form of the {\it integrated} degeneracy-flux relat

Miguel A. Martin-Delgado, German Sierra

We review some of our recent results concerning the relationship between the Real-Space Renormalization Group method and Quantum Groups. We show this relation by applying real-space RG methods to study two quantum group invariant Hamiltonians, that of the XXZ model and the Ising model in a transverse field (ITF) defined in an open chain with appropriate boun

José P. S. Lemos, Vilson T. Zanchin

It is shown how to transform the three dimensional BTZ black hole into a four dimensional cylindrical black hole (i.e., black string) in general relativity. This process is identical to the transformation of a point particle in three dimensions into a straight cosmic string in four dimensions.