May 1996 arXiv papers — page 8

Jean-Loup Gervais, Jean-François Roussel

We spell out the derivation of novel features, put forward earlier in a letter, of two dimensional gravity in the strong coupling regime, at $C_L=7$, 13, 19. Within the operator approach previously developed, they neatly follow from the appearence of a new cosmological term/marginal operator, different from the standard weak-coupling one, that determines the

Sanghyeon Chang, Claudio Coriano, Alon E. Faraggi

We investigate the cosmological constraints on exotic stable matter states which arise in realistic free fermionic superstring models. These states appear in the superstring models due to a ``Wilson--line'' breaking of the unifying non--Abelian gauge symmetry. In the models that we consider the unifying $SO(10)$ gauge symmetry is broken at the string

Edmond L. Berger, Xiaofeng Guo, Jianwei Qiu

We provide complete analytic expressions for the isolated prompt photon production cross section in $e^+e^-$ annihilation reactions through one-loop order in quantum chromodynamics (QCD) perturbation theory. Functional dependences on the isolation cone size $δ$ and isolation energy parameter $ε$ are derived. The energy dependence as well as the full angular

Michael Creutz, Michel Tytgat

Coupling gauge fields to the chiral currents from an effective Lagrangian for pseudoscalar mesons naturally gives rise to a species doubling phenomenon similar to that seen with fermionic fields in lattice gauge theory.

A. Bueno, J. Velasco

Available high energy data for both pp and pp total cross sections ($ 5 \ GeV \ < \ \sqrt s \ < \ 1.8 \ TeV$) are described by means of two well-known distinct parametrizations, characteristic of theoretical (``Regge-like&#34; expression) and experimental (``Froissart-Martin-like&#34; expression) practices, respectively. Both are compared from the statistica

Teimuraz Kopaleishvili, Akaki Rusetsky

A new version for the relativistic generalization of the wide class of static quark--antiquark confining potentials is suggested. The comparison of this approach with other ones, known in literature, is considered. With the use of Logunov--Tavkhelidze quasipotential approach the first--order retardation corrections to the heavy quarkonia mass spectrum are ca

Dennis Silverman

We consider the jet cross sections for gluons coupling to quarks with an anomalous chromomagnetic moment. We then apply this to the deviation and bounds from QCD found in the CDF and D0 Fermilab data, respectively, to find a range of possible values for the anomalous moments. The quadratic and quartic terms in the anomalous moments can fit to the rise of a d

S. A. Larin, P. Nogueira, T. van Ritbergen, J. A. M. Vermaseren

We present the analytic next-to-next-to-leading perturbative QCD corrections in the leading twist approximation for the moments N=2,4,6,8 of the flavour singlet deep inelastic structure functions F_2 and F_L. We calculate the three-loop anomalous dimensions of the corresponding singlet operators and the three-loop coefficient functions of the structure funct

J. Berger, A. Blotz, H. -C. Kim, K. Goeke

We show that under the assumption of dynamical symmetry breaking of electro weak interactions by a top quark condensate, motivated by the Top Mode Standard Model, the top quark in this effective theory can be considered then as chiral color soliton (qualiton). This is realized in an effective four-fermion interaction with chiral $SU(3)_c$ as well as $SU(2)_L

Wojciech Florkowski, Wojciech Broniowski

Temperature dependence of the quark condensate is studied in the Nambu--Jona-Lasinio model with meson loops. Substantial differences are found compared to the results with quark loops only.

A. Corsetti, A. Grau, G. Pancheri, Y. N. Srivastava

A model for the parton distributions of hadrons in impact parameter space has been constructed using soft gluon summation. This model incorporates the salient features of distributions obtained from the intrinsic transverse momentum behaviour of hadrons. Under the assumption that the intrinsic behaviour is dominated by soft gluon emission stimulated by the s

A. Blondel, F. M. Renard, L. Trentadue, C. Verzegnassi

We consider the virtual effects of a general type of Anomalous (triple) Gauge Couplings on various experimental observables in the process of electron-positron annihilation into a final fermion-antifermion state. We show that the use of a recently proposed &#34;$Z$-peak subtracted&#34; theoretical description of the process allows to reduce substantially the

J. Fujimoto, T. Ishikawa, T. Kaneko, K. Kato

grc4f is a Monte-Carlo package for generating e+e- to 4-fermion processes in the standard model. All of the 76 LEP-2 allowed fermionic final state processes evaluated at tree level are included in version 1.1. grc4f addresses event simulation requirements at e+e- colliders such as LEP and up-coming linear colliders. Most of the attractive aspects of grc4f co

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

The cross-section for the production of $t\bar{t}$ pairs in $e^+e^-$-annihilation via a virtual photon is determined up to order $α_s^2$. For the cm-energies of interest the effect of the top mass may not be considered as a small parameter and the full mass dependence must be included.

Tomohiro Matsuda

We examine the process of formation of the gaugino condensation within a Nambu-Jona-Lasinio type approach. We construct an effective Lagrangian description for the gaugino condensation which include a Weyl compensator superfield whose vacuum expectation value is related to the gaugino condensation.

V. Bornyakov, G. Schierholz

Non-abelian gauge theories can be cast into abelian gauge theories with monopoles. We ask what becomes of the instantons after abelian projection. Instantons are found to consist of closed dyon loops. It is shown that the electric charge of the dyons is quantized. The implication of this result for the dynamics of the Yang-Mills vacuum is briefly discussed.

U. K. Yang

Measurements of neutrino-nucleon and antineutrino-nucleon differential cross sections using the CCFR neutrino detector at Fermilab have been used to extract preliminary values of $R ={σ_L}/{σ_T}$ in the kinematic region $0.01<x<0.6$, and $4<Q^2<300$ GeV$^2$. The new data provide the first measurements of $R$ in the $x<0.1$ region. The $x$ and $Q^2$ dependenc

D. Bazeia, R. F. Ribeiro, E. Ventura, M. T. Thomaz

In this paper we follow the lines of recent works to investigate systems of two coupled real scalar fields defined by potentials that describe periodic interactions between the scalar fields. We work with polymeric chains containing periodic interactions between the coupled fields, and we investigate the topological sectors to obtain explicit soliton solutio

Swapan K. Pati, S. Ramasesha, Z. Shuai, J. L. Bredas

We extend the symmetrized density matrix renormalization group (SDMRG) method to compute the dynamic nonlinear optic coefficients for long chains. By computing correction vectors in the appropriate symmetry subspace we obtain the dynamic polarizabilities, $α_{ij}(ω)$, and third-order polarizabilities $γ_{ijkl}(ω,ω,ω)$ of the Hubbard and &#34;$U-V$&#34; chain

A. A. Golubov, B. A. Malomed, A. V. Ustinov

Theoretical model for the radiation linewidth in a multi-fluxon state of a long Josephson junction is presented. Starting from the perturbed sine-Gordon model with the temperature dependent noise term, we develop a collective coordinate approach which allows to calculate the finite radiation linewidth due to excitation of the internal degrees of freedom in t

Zhu-Pei Shi, John F. Cooke, Zhenyu Zhang, Barry M. Klein

An Fe/Au monatomic multilayer, consisting of alternating single Fe and Au layers, has been studied by means of the self-consistent full-potential linearized augmented plane wave method. We show by total energy minimization that this artificial thin film is in the tetragonal $L1_{0}$ ordered structure with the ratio of the interlayer spacing to the intralayer

V. B. Priezzhev

A new model of self-organized criticality is proposed. An algebra of operators is introduced which is similar to that used for the Abelian sandpile model. The structure of the configurational space is determined and the number of recurrent states is found.

D. Giri, K. Kundu

Electronic structures of undoped and doped cyclic polythiophene (PT) are studied using modified $σ$-bond compressibility model. Cyclic PT doped with odd number of bipolarons creates an aromatic polyene backbone containing (4$n$+2) $π$-electrons and the system is driven towards the quinoid form. Consequently, we find an insulator-metal transition for dopant c

H. A. Fertig, L. Brey, R. Cote, A. H. MacDonald

We propose an intrinsic maximum speed for dissipationless E cross B drift of Skyrmion quasiparticles in quantum Hall ferromagnets. When this speed is exceeded, Skyrmions can radiate spin-waves by making internal excitations which allow total spin to be conserved. Our proposal is illustrated by a time-dependent Hartree-Fock approximation calculation of the ex

V. Freilikher, M. Pustilnik, I. Yurkevich

Statistical properties of the transmittance ($T$) and reflectance ($R$) of an amplifying layer with one-dimensional disorder are investigated analytically. Whereas the transmittance at typical realizations decreases exponentially with the layer thickness $L$ just as it does in absorbing media, the average $\left\langle T\right\rangle $ and $\left\langle R\ri

Ulrich Werner, Raymond Fresard

We apply the muffin-tin effective medium approximation to calculate the temperature dependence of the resistivity and of the thermopower of amorphous and liquid metals. The results show unambiguously that a large resistivity is accompanied by a negative temperature coefficient, in agreement with the experimental situation. This behavior is shown to result fr

M. Boros, W. Eckert, F. Gallwitz, G. Goerz

In this paper we describe an approach to automatic evaluation of both the speech recognition and understanding capabilities of a spoken dialogue system for train time table information. We use word accuracy for recognition and concept accuracy for understanding performance judgement. Both measures are calculated by comparing these modules&#39; output with a

Peter Neuhaus, Udo Hahn

We present an approach to parallel natural language parsing which is based on a concurrent, object-oriented model of computation. A depth-first, yet incomplete parsing algorithm for a dependency grammar is specified and several restrictions on the degree of its parallelization are discussed.

Peter Neuhaus, Udo Hahn

We argue for a performance-based design of natural language grammars and their associated parsers in order to meet the constraints posed by real-world natural language understanding. This approach incorporates declarative and procedural knowledge about language and language use within an object-oriented specification framework. We discuss several message pas

Udo Hahn, Katja Markert, Michael Strube

We present a hybrid text understanding methodology for the resolution of textual ellipsis. It integrates conceptual criteria (based on the well-formedness and conceptual strength of role chains in a terminological knowledge base) and functional constraints reflecting the utterances&#39; information structure (based on the distinction between context-bound an

Caroline Nore, Theodore G. Shepherd

A reduced dynamical model is derived which describes the interaction of weak inertia-gravity waves with nonlinear vortical motion in the context of rotating shallow-water flow. The formal scaling assumptions are (i) that there is a separation in timescales between the vortical motion and the inertia-gravity waves, and (ii) that the divergence is weak compare

R. E. Prange

We directly combine ideas of the quasiclassical approximation with random matrix theory and apply them to the study of the spectrum, in particular to the two-level correlator. Bogomolny&#39;s transfer operator T, quasiclassically an NxN unitary matrix, is considered to be a random matrix. Rather than rejecting all knowledge of the system, except for its symm

Gregory L. Eyink, Jack Xin

We study Kraichnan&#39;s model of a turbulent scalar, passively advected by a Gaussian random velocity field delta-correlated in time, for every space dimension $d\geq 2$ and eddy-diffusivity (Richardson) exponent $0<ζ<2$. We prove that at zero molecular diffusivity, or $κ= 0$, there exist unique weak solutions in $L^2\left(Ω^{\otimes N}\right)$ to the singu

Izumi Murakami, Takako Kato

We have calculated X-ray and UV spectra of Be-like Fe (FeXXIII) ion in collisional-radiative model including all fine-structure transitions among the 2s^2, 2s2p, 2p^2, 2snl, and 2pnl levels where n=3 and 4, adopting data for the collision strengths by Zhang & Sampson (1992) and by Sampson, Goett, & Clark (1984). Some line intensity ratios can be used for the

Jeff Secker, William E. Harris

We have obtained new CCD photometry for a sample of $\simeq 800$ early-type galaxies (dwarf and giant ellipticals) in the central 700 arcmin$^2$ of the Coma cluster, complete in color and in magnitude to $R = 22.5$ mag ($M_R \simeq -12$ mag for $H_0 = 86$ km/sec/Mpc). The composite luminosity function for all galaxies in the cluster core (excluding NGC 4874

D. Fox, W. Lewin, B. Margon, J. van Paradijs

We report on 40 kiloseconds of ROSAT HRI observations of the globular cluster M92 (NGC 6341) and 20 kiloseconds of observations of the globular cluster M13 (NGC 6205). We find that the low-luminosity (10^{32.5} erg/sec at 7.5 kpc) source previously observed near the core of M92 with the ROSAT PSPC remains unresolved at HRI resolution; we can identify it with

A. M. Khokhlov, E. S. Oran, J. Craig Wheeler

This paper outlines a theoretical approach for predicting the onset of detonation in unconfined turbulent flames which is relevant both to problems of terrestrial combustion and to thermonuclear burning in Type Ia supernovae. Two basic assumuptions are made: 1) the gradient mechanism is the inherent mechanism that leads to DDT in unconfined conditions, and 2

K. A. Southwell, M. Livio, P. A. Charles, D. O&#39;Donoghue

We present spectroscopy and photometry of the LMC supersoft binary system RX~J0513.9-6951. We derive a refined spectroscopic period of P$=0.761\pm0.004$~d, which is consistent with the value obtained from long term photometric monitoring (P$=0.76278\pm0.00005$~d). We see bipolar outflow components of He{\sc ii} and H$β$, with velocities of $\sim 3800$\,km\,s

C. Alcock et al

Using the exceptional monitoring capabilities of the MACHO project we present here the optical history of the LMC supersoft source (SSS) RX~J0513.9-6951, for a continuous 3 year period. Recurring low states, in which the optical brightness drops by up to a magnitude, are observed at quasi-regular intervals. This provides a crucial insight into the nature of

E. Baron, P. H. Hauschildt, P. Nugent, D. Branch

Supernovae, with their diversity of compositions, velocities, envelope masses, and interactions are good testing grounds for probing the importance of NLTE in expanding atmospheres. In addition to treating H, He, Li I, O I, Ne I, Na I, and Mg II in NLTE, we use a very large model atom of Fe II to test the importance of NLTE processes in both SNe Ia and II. S

Murat Boratav

Over the last 30 years or so, a handful of events observed in ground-based cosmic ray detectors seem to have opened a new window in the field of high-energy astrophysics. These events have energies exceeding 5x10**19 eV (the region of the so-called Greisen-Zatsepin-Kuzmin spectral cutoff); they seem to come from no known astrophysical source; their chemical

Sacha Davidson

The ingredients required to create a magnetic field in the early Universe are identified, and compared with Sakharov&#39;s conditions for baryogenesis. It is also shown that a long range coherent magnetic field is not generated by the classical rolling Higgs vacuum expectation value during the electroweak phase transition.

Philip D. Mannheim

In this paper we identify a new regularity in the systematics of galactic rotation curves, namely we find that at the last detected points in galaxies of widely varying luminosity, the centripetal acceleration is found to have the completely universal form $v^2/R=c^2(γ_0+γ^{*}N^{*})/2$ where $γ_0$ and $γ^{*}$ are new universal constants and $N^{*}$ is the am

Luca Ciotti

The analytical phase-space distribution function (DF) of spherical self--consistent galaxy (or cluster) models, embedded in a dark matter halo, where both density distributions follow the Hernquist profile, with different total masses and core radii (hereafter called HH models), is presented. The concentration and the amount of the stellar and dark matter di

V. Karas

A simple, analytical fitting-formula for a photometric light curve of a source of light orbiting around a black hole is presented. The formula is applicable for sources on a circular orbit with radius smaller than 45 gravitational radii from the black hole. This range of radii requires gravitational focusation of light rays and the Doppler effect to be taken

R. A. Edelson et al

This paper combines data from the three preceding papers in order to analyze the multi-waveband variability and spectral energy distribution of the Seyfert~1 galaxy NGC~4151 during the December 1993 monitoring campaign. The source, which was near its peak historical brightness, showed strong, correlated variability at X-ray, ultraviolet, and optical waveleng

S. Kaspi et al

We present the results of an intensive ground-based spectrophotometric monitoring campaign of the Seyfert galaxy NGC~4151 for a period of over two months, with a typical temporal resolution of one day. Light curves for four optical continuum bands and the H$α$ and H$β$ emission lines are given. During the monitoring period, the continuum at 6925~Å varied by

D. M. Crenshaw et al

We present the results of an intensive ultraviolet monitoring campaign on the Seyfert 1 galaxy NGC 4151, as part of an effort to study its short time-scale variability over a broad range in wavelength. The nucleus of NGC 4151 was observed continuously with the {\it International Ultraviolet Explorer} (IUE) for 9.3 days, yielding a pair of LWP and SWP spectra

Brad K. Gibson

Working within the classic supernovae-driven wind framework for elliptical galaxy evolution, we perform a systematic investigation into the discrepancies between the predictions of three contemporary codes -- Arimoto & Yoshii (1987, A&A, 173, 23), Bressan et al. (1994, ApJS, 94, 63), and Gibson (1996a, MNRAS, 278, 829; 1996b, MNRAS, submitted). By being prim

Jungkai Alfred Chen

We prove that for any smooth projective variety $X$ of dimension $\geq 3$, there exists an integer $g_0=g_0(X)$, such that for any integer $g \geq g_0$, there exists a smooth curve $C$ in $X$ with $g(C)=g$.

Jesus Salas, Alan D. Sokal

We have performed a high-precision Monte Carlo study of the dynamic critical behavior of the Swendsen-Wang algorithm for the two-dimensional 3-state Potts model. We find that the Li-Sokal bound ($τ_{int,E} \geq const \times C_H$) is almost but not quite sharp. The ratio $τ_{int,E} / C_H$ seems to diverge either as a small power ($\approx 0.08$) or as a logar

Adel Bilal, Frank Ferrari

We explicitly determine the global structure of the $SL(2,Z)$ bundle over the Coulomb branch of the moduli space of asymptotically free $N=2$ supersymmetric Yang-Mills theories with gauge group $SU(2)$ when massless hypermultiplets are present. For each relevant number of flavours, we show that there is a curve of marginal stability on the Coulomb branch, di

D. Arnaudon, M. Bauer, L. Frappat

We define on the universal enveloping superalgebra of osp(1|2n) a nonstandard adjoint action, endowing it with a module structure. This allows, in particular, to construct a bosonic operator which anticommutes with all the fermionic generators and which appears to be the square root of a certain Casimir operator.

D. Arnaudon, M. Bauer

A bosonic operator of U_q(osp(1|2)) that anticommutes with the fermionic generators appears to be useful to describe the relations in the centre of U_q(osp(1|2)) for q a root of unity (in the unrestricted specialisation). As in the classical case, it also simplifies the classification of finite dimensional irreducible representations.

J. Engel, K. Langanke, P. Vogel

Unlike their lighter counterparts, most odd-odd N=Z nuclei with mass A > 40 40 have ground states with isospin T=1, suggesting an increased role for the isovector pairing interaction. A simple SO(5) seniority-like model of this interaction reveals a striking and heretofore unnoticed interplay between like-particle and neutron-proton isovector pairing near N=

L. Caneschi, M. Lysiansky

We quantize the $SU(n)$ Wess-Zumino-Witten model in terms of left and right chiral variables choosing an appropriate gauge and we compare our results with the results that have been previously obtained in the algebraic treatment of the problem. The algebra of the chiral vertex operators in the fundamental representation is verified by solving appropriate Kni

Satya N. Majumdar, Clement Sire, Alan J. Bray, Stephen J. Cornell

The diffusion equation \partial_tϕ= \nabla^2ϕis considered, with initial condition ϕ( _x_ ,0) a gaussian random variable with zero mean. Using a simple approximate theory we show that the probability p_n(t_1,t_2) that ϕ( _x_ ,t) [for a given space point _x_ ] changes sign n times between t_1 and t_2 has the asymptotic form p_n(t_1,t_2) \sim [\ln(t_2/t_1)]^n(

Costas G. Papadopoulos

We study the sensitivity of the processes `e+ e- -> lepton (l) neutrino (v) quark (u) antiquark (d)&#39; at LEP2 energies on the non-standard trilinear gauge couplings (TGC), using the optimal observables method. All relevant leading logarithmic corrections to the tree-order cross section, as well as experimental resolution effects have been studied. Taking

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

In this paper we develop a theoretical framework which allows us to study excitations of the nucleon. Assuming an effective two-body interaction as a model for low-energy QCD, we derive a relativistic TDHF equation for a many-body system of quarks. To render the Dirac-sea contribution tothe mean field finite, we introduce a symmetry conserving regularization

Paul Mansfield, Rui Neves

We analyse boundary conformal field theories on random surfaces using the conformal gauge approach of David, Distler and Kawai. The crucial point is the choice of boundary conditions on the Liouville field. We discuss the Weyl anomaly cancellation for Polyakov`s non-critical open bosonic string with Neumann, Dirichlet and free boundary conditions. Dirichlet

Alexei Yung

The N=2 supersymmetric gauge theory with gauge group SU(2) is considered. The instanton field is calculated explicitly using the superfield formalism. The instanton-induced effects are encoded in the effective vertex in the Lagrangian. This vertex produces the large distance expansion of the low energy effective Lagrangian in derivatives of fields. The leadi

Salvatore Capozziello, Ruggiero de Ritis

We extend the Wald cosmic no-hair theorem to a general class of scalar-tensor nonminimally coupled theories of gravity where ordinary matter is also present in the form of a perfect fluid. We give a set of conditions for obtaining a de Sitter expansion independently of any initial conditions, generalizing the treatment of such a problem as given by Wald. Fin

A. Bialas, R. Peschanski

The contribution to diffraction dissociation of virtual photons due to quasi-elastic scattering of the $q$-$\bar q$ component is calculated in the framework of the QCD dipole picture. Both longitudinal and transverse components of the cross-section are given. It is shown that, at fixed mass of the diffractively produced system, quantum mechanical interferenc

J. Hisano, T. Moroi, K. Tobe, M. Yamaguchi

Event rates of various lepton flavor violating processes in the minimal supersymmetric SU(5) model are calculated, using exact formulas which include Yukawa vertices of lepton-slepton-Higgsino. We find subtlety in evaluating event rates due to partial cancellation between diagrams. This cancellation typically reduces the event rates significantly, and the si

V. L. Vereschagin

Problem of asymptotic description for global solutions to the six Painleve equations was investigated. Elliptic anzatzes and appropriate modulation equations were written out.

A. A. Tseytlin

We present string-theory derivation of the semiclassical entropy of extremal dyonic black holes in the approach based on conformal sigma model (NS-NS embedding of the classical solution). We demonstrate (resolving some puzzles existed in previous related discussions) that the degeneracy responsible for the entropy is due to string oscillations in four transv

Knut Smoczyk

We derive some important geometric identities for Lagrangian submanifolds immersed in a K\"ahler manifold and prove that there exists a canonical way to deform a Lagrangian submanifold by a parabolic flow through a family of Lagrangian submanifolds if the ambient space is a Ricci-flat Calabi-Yau manifold.

I. I. Mazin, R. J. Hemley, A. F. Goncharov, M. Hanfland

We present a unified view of orientational ordering in phases I, II, and III of solid hydrogen. Phases II and III are orientationally ordered, while the ordering objects in phase II are angular momenta of rotating molecules, and in phase III the molecules themselves. This concept provides quantitative explanation of the vibron softening, libron and roton spe

C. Tzanakis, A. P. Grecos, P. Hatjimanolaki

The formalism of generalized Wigner transformations developped in a previous paper, is applied to kinetic equations of the Lindblad type for quantum harmonic oscillator models. It is first applied to an oscillator coupled to an equilibrium chain of other oscillators having nearest-neighbour interactions. The kinetic equation is derived without using the so c

Constantinos Tzanakis, Alkis P. Grecos

Generalised Wigner and Weyl transformations of quantum operators are defined and their properties, as well as those of the algebraic structure induced on the phase-space are studied. Using such transformations, quantum linear evolution equations are given a phase-space representation. In particular this is done for the general kinetic equation of the Lindbla

Christopher A. Fuchs

The engine that powers quantum cryptography is the principle that there are no physical means for gathering information about the identity of a quantum system&#39;s state (when it is known to be prepared in one of a set of nonorthogonal states) without disturbing the system in a statistically detectable way. This situation is often mistakenly described as a

Wojciech Hubert Zurek, Raymond Laflamme

We show how to carry out quantum logical operations (controlled-not and Toffoli gates) on encoded qubits for several encodings which protect against various 1-bit errors. This improves the reliability of these operations by allowing one to correct for one bit errors which either preexisted or occurred in course of operation. The logical operations we conside

Hiromichi Nakazato, Mikio Namiki, Saverio Pascazio, Yoshiya Yamanaka

We examine whether the chaotic behavior of classical systems with a limited number of degrees of freedom can produce quantum dephasing, against the conventional idea that dephasing takes place only in large systems with a huge number of constituents and complicated internal interactions. On the basis of this analysis, we briefly discuss the possibility of de

Urs Burri

It was shown by Goussarov that Vassiliev invariants are polynomials in the gleams for a fixed Turaev shadow. In this paper we show that Vassiliev invariants are almost characterized by this fact. We also prove that the space of knot invariants which are polynomials in the gleams is bigger than the Vassiliev subspace.

I. Juhász, Lajos Soukup, Z. Szentmiklóssy

In this paper we first formulate several ``combinatorial principles&#39;&#39; concerning kappa \times omega matrices of subsets of omega and prove that they are valid in the generic extension obtained by adding any number of Cohen reals to any ground model V, provided that the parameter kappa is an omega-inaccessible regular cardinal in V. Then we present a

B. D. Keister, W. N. Polyzou

The possibility of non-causal signal propagation is examined for various theories of dense matter. This investigation requires a discussion of definitions of causality, together with interpretations of spacetime position. Specific examples are used to illustrate the satisfaction or violation of causality in realistic calculations.

V. A. Kazakov

A recently introduced model of dually weighted planar graphs is solved in terms of an elliptic parametrization for some particular collection of planar graphs describing the 2D $R^2$ quantum gravity. Along with the cosmological constant $λ$ one has a coupling $β$ in the model corresponding to the $R^2$-coupling constant. It is shown that for any value of $β$

Matthias Blau, Ian Jermyn, George Thompson

Using gauge theory and functional integral methods, we derive concrete expressions for the partition functions of BF theory and the U(1|1) model of Rozansky and Saleur on $Σx S^{1}$, both directly and using equivalent two-dimensional theories. We also derive the partition function of a certain non-abelian generalization of the U(1|1) model on mapping tori an

A. Abdesselam, V. Rivasseau

We introduce a new type of cluster expansion which generalizes a previous formula of Brydges and Kennedy. The method is especially suited for performing a phase-space multiscale expansion in a just renormalizable theory, and allows the writing of explicit non-perturbative formulas for the Schwinger functions. The procedure is quite model independent, but for

A. E. Chubykalo, M. W. Evans, R. Smirnov-Rueda

A charge $q$ moving in a reference laboratory system with constant velocity {\bf V} in the $X$-axis produces in the $Z$-axis a longitudinal, phase free, vacuum magnetic field which is identified as the radiated ${\bf B}^{(3)}$ field of Evans, Vigier and others.

Lina Paria, Afsar Abbas

Using a geometric model for the study of the structure of hadrons, we study baryons having one, two and three heavy quarks. The study reveals diquark structure in baryons with one and two heavy quarks but not with three heavy identical quarks.

R. Haeckl, V. Hund, H. Pilkuhn

The relativistic motion of an isolated two--body system (bound or unbound) of given lab energy $K^{0}$ in QED is separated into cms motion and relative motion. The relative motion equation ${\cal K}_{L} ψ_{L} ({\bf r}_{L} ) =0$ contains the momentum eigenvalue ${\bf K}$ of the cms motion. It is greatly simplified by a binary boost to the atomic rest frame, w

Joan Sola

We discuss the one-loop quantum corrections to the top quark width and to the hadronic widths of the Higgs bosons of the MSSM, and emphasize the results obtained in particular regions of the MSSM parameter space which have been proposed to alleviate the anomalies observed in the decay modes of the $Z$ into $b\bar{b}$ and $c\bar{c}$. We find that the correcti

S. M. Bilenky, W. M. Alberico, C. Giunti, C. Maieron

Talk presented by S.M. Bilenky at the Adriatico Research Conference on &#34;Trends in Collider Spin Physics&#34;, ICTP, Trieste, December 1995.

Mikhail Braun, Gian Paolo Vacca, Giovanni Venturi

The equation for the hard pomeron with a running coupling introduced on the basis of the bootstrap requirement is solved numerically. Two supercritical pomerons are found with the intercept minus 1 of the leading one of the order 0.35-0.5 and that of the subleading one half as large. The contribution of multipomeron exchanges is found to be essential only at

A. H. Mueller, G. P. Salam

This paper studies two related questions in high energy onium-onium scattering: the probability of producing an unusually large number of particles in a collision, where it is found that the cross section for producing a central multiplicity proportional to $k$ should decrease exponentially in $\sqrt{k}$. Secondly, the nature of gluon (dipole) evolution when

H. Nunokawa, Y. -Z. Qian, A. Rossi, J. W. F. Valle

It has been noted for a long time that, in some circumstances, {\sl massless} neutrinos may be {\sl mixed} in the leptonic charged current. Conventional neutrino oscillation searches in vacuum are insensitive to this mixing. We discuss the effects of resonant massless-neutrino conversions in the dense medium of a supernova. In particular, we show how the det

Harald Fritzsch

The mass problem in particle physics for other fields is discussed. While the problem of the nuclear masses has been resolved within the QCD framework, 3 parameters of the ``Standard Model&#39;&#39; are related to the fermion sector. The origin of the ferion masses remains unresolved. We discuss attempts to explain the observed hierarchical features of the m

M. Gluck, E. Reya, M. Stratmann

The feasibility of an experimental determination of the parton distributions of virtual photons at high energy $ep$ colliders is studied in the context of the DESY-HERA collider. Recently proposed parton densities of virtual photons are utilized to evaluate the appropriate production processes and their relevant kinematical regions. It is demonstrated that h

Marc Blatter, Ferenc Niedermayer

We present a new fixed point action for SU(3) lattice gauge theory, which has --- compared to earlier published fixed point actions --- shorter interaction range and smaller violations of rotational symmetry in the static $q\bar{q}$-potential even at shortest distances.

Rafe Mazzeo, Frank Pacard

We extend the results and methods of \cite{MP} to prove the existence of constant positive scalar curvature metrics $g$ which are complete and conformal to the standard metric on $S^N \setminus Λ$, where $Λ$ is a disjoint union of submanifolds of dimensions between 0 and $(N-2)/2$. The existence of solutions with isolated singularities occupies the majority

G. E. Castilla, S. Chakravarty

Nonlinear $σ$-model is an ubiquitous model. In this paper, the $O(N)$ model where the $N$-component spin is a unit vector, ${\bf S}^2=1$,is considered. The stability of this model with respect to gradient operators $(\partial_μ{\bf S}\cdot \partial_ν{\bf S})^s$, where the degree $s$ is arbitrary, is discussed. Explicit two-loop calculations within the scheme

C. Wengel, A. P. Young

We investigate the critical behavior of the gauge glass model for the vortex glass transition in three-dimensional superconductors, including screening of the interaction between vortices. A Monte Carlo study of the linear resistivity and a scaling analysis of current--voltage characteristics indicates that screening destroys the finite--temperature transiti

Agustin E. Gonzalez, Guillermo Ramirez-Santiago

In the volume fraction range (0.005,0.08), we have obtained the temporal evolution of the structure factor $S(q)$, in extensive numerical simulations of both diffusion-limited and reaction-limited colloid aggregation in three dimensions. We report the observation of scaling of this structure function in the diffusion-limited case, analogous to a spinodal dec

Alexander Nazarenko, Elbio Dagotto

We calculate the dispersion of a hole in ${\rm CuO_2}$ bilayers and 3D antiferromagnets, using the self-consistent Born approximation (SCBA) to the $t-J$ model. Superconductivity and the symmetry of its order parameter are studied introducing a nearest-neighbor density-density attraction induced by short range antiferromagnetic (AF) fluctuations, as describe

Pamela W. Jordan

I examine how terminological languages can be used to manage linguistic data during NL research and development. In particular, I consider the lexical semantics task of characterizing semantic verb classes and show how the language can be extended to flag inconsistencies in verb class definitions, identify the need for new verb classes, and identify appropri

Marc Dymetman

We present, in easily reproducible terms, a simple transformation for offline-parsable grammars which results in a provably terminating parsing program directly top-down interpretable in Prolog. The transformation consists in two steps: (1) removal of empty-productions, followed by: (2) left-recursion elimination. It is related both to left-corner parsing (w

Michael Strube

We extend the centering model for the resolution of intra-sentential anaphora and specify how to handle complex sentences. An empirical evaluation indicates that the functional information structure guides the search for an antecedent within the sentence.

Michael Strube, Udo Hahn

Based on empirical evidence from a free word order language (German) we propose a fundamental revision of the principles guiding the ordering of discourse entities in the forward-looking centers within the centering model. We claim that grammatical role criteria should be replaced by indicators of the functional information structure of the utterances, i.e.,

Alexander Rosen, Joel N. Bregman, Daniel D. Kelson

In a previous paper, we calculated numerical hydrodynamic models of the interstellar medium in the Galaxy, which suggested that hot gas (T $\ge$ 3 $\times$ 10$^5$ K) has a filling factor near 50\% in the midplane (Rosen \& Bregman 1995, ApJ 440, 634). Here we extend the work to examine the X-ray emission characteristics of the best model and calculate a vari