September 1998 arXiv papers — page 2

Th. Busch, J. R. Anglin

We show that the energetic instability of dark solitons is associated with particle-like motion, and present a simple equation of motion, based on the Mössbauer effect, for dark solitons propagating in inhomogeneous Thomas-Fermi clouds. Numerical simulations support our theory. We discuss some experimental approaches.

A. Werner, F. Schmid, M. Mueller, K. Binder

A popular concept which describes the structure of polymer interfaces by ``intrinsic profiles'' centered around a two dimensional surface, the ``local interface position'', is tested by extensive Monte Carlo simulations of interfaces between demixed homopolymer phases in symmetric binary (AB) homopolymer blends, using the bond fluctuation mod

A. G. Green

The quantum Hall ferromagnet at filling fraction $ν= 1$ has some unusual properties due to the remarkable identity between the topological density of a spin distortion and the associated electrical charge density. We investigate the localization of spinwaves by coupling to a scalar disorder potential via their topological density. A low energy description of

D. D. Betts, J. Schulenburg, G. E. Stewart, J. Richter

Here we generate finite bipartite body-centred cubic lattices up to 32 vertices. We have studied the spin one half Heisenberg antiferromagnet by diagonalizing its Hamiltonian on each of the finite lattices and hence computing its ground state properties. By extrapolation of these data we obtain estimates of the T = 0 properties on the infinite bcc lattice. O

Uwe Hansen, Peter Vogl, Vincenzo Fiorentini

We present simulations of metallization morphologies under ionized sputter deposition conditions, obtained by a new theoretical approach. By means of molecular dynamics simulations using a carefully designed interaction potential, we analyze the surface adsorption, reflection, and etching reactions taking place during Al physical vapor deposition, and calcul

Yasumasa Hasegawa

The Josephson effect between triplet and singlet superconductors is studied. Josephson current can flow between triplet and singlet superconductors due to the spin-orbit coupling in the spin-triplet superconductor but it is finite only when triplet superconductor has $L_z=-S_z=\pm 1$, where $L_z$ and $S_z$ are the perpendicular components of orbital angular

Shiro Kawabata

We study the quantum-interference effect in the ballistic Aharonov-Bohm (AB) billiard. The wave-number averaged conductance and the correlation function of the non-averaged conductance are calculated by use of semiclassical theory. Chaotic and regular AB billiards have turned out to lead to qualitatively different semiclassical formulas for the conductance w

W. C. Wu, D. Branch, J. P. Carbotte

We investigate the universal electronic transport for a mixed $d_{x^2-y^2}$+s-wave superconductor in the presence of an anisotropic elliptical Fermi surface. Similar to the universal low-temperature transport predicted in a $d_{x^2-y^2}$-wave superconductor with a circular Fermi surface, anisotropic universal features are found in the low-temperature microwa

Ion-Olimpiu Stamatescu

We study some features of learning models based on "delayed" and undifferentiated reinforcement and realized by simple algorithms which may be considered of a very elementary nature. We show that a modification of the Hebb-rule works well for this problem in a neural network realization and study numerically its convergence properties. An illustratio

Lin-Wang Wang

One approximation is made to describe a M+1 electron many-body wavefunction by a M electron many-body wavefunction and a single electron wavefunction. Under this approximation, we have derived the Coulomb energy which relates the exciton energy $E_{exc}$ in a quantum dot with the quasiparticle band gap (defined as the difference between the ionization energy

Zoltan Kovacs, Laurent Wiesenfeld

We investigate the topological properties of invariant sets associated with the dynamics of scattering systems with three or more degrees of freedom. We show that the asymptotic separation of one degree of freedom from the rest in the asymptotic regime, a common property in a large class of scattering models, defines a dynamical object with phase space separ

Rainer Hegger, Holger Kantz, Thomas Schreiber

Nonlinear time series analysis is becoming a more and more reliable tool for the study of complicated dynamics from measurements. The concept of low-dimensional chaos has proven to be fruitful in the understanding of many complex phenomena despite the fact that very few natural systems have actually been found to be low dimensional deterministic in the sense

H. Velazquez, Simon D. M. White

We have carried out a set of self-consistent N-body simulations to study the interaction between disc galaxies and merging satellites with the aim of determining the disc kinematical changes induced by such events. We explore a region of the parameter space embracing satellites with different masses and internal structure and orbits of various eccentricities

C. A. Collins

A primeval galaxy represents the earliest stages of a galaxy's life and as such provides clues to the early history of the Universe and the evolution of stars and galaxies. Over the last 20 years astronomers have been engaged in the quest to detect the faint signals from these objects, believed to lie at a distance comparable with the size of the Univers

Bradford W. Greeley, William P. Blair, Knox S. Long, John C. Raymond

Using the Hopkins Ultraviolet Telescope (HUT), we have obtained 850-1850 angstrom spectra of the magnetic cataclysmic variable star AM Her in the high state. These observations provide high time resolution spectra of AM Her in the FUV and sample much of the orbital period of the system. The spectra are not well-modelled in terms of simple white dwarf (WD) at

Wei Cui

I review the observed temporal X-ray properties of Galactic black hole candidates and the status of theoretical modeling of these properties. Like spectral X-ray properties, which has so far attracted most of the attention, the temporal properties, such as power spectral density, hard X-ray time lags, and coherence functions, contain information on some of t

Eric C. Ford, Michiel van der Klis, Jan van Paradijs, Mariano Mendez

In recent observations with the Rossi X-Ray Timing Explorer we have detected two simultaneous quasi-periodic oscillation (QPO) peaks in the low mass X-ray binary and atoll source 4U 1735-44. The lower and higher frequency QPOs have frequencies varying between 632 and 729 Hz, and 982 and 1026 Hz, respectively. The fractional rms amplitudes are 3.7 to 8.1% and

C. Mendes de Oliveira, N. Drory, U. Hopp, R. Bender

The MUNICS project is an ongoing imaging survey designed to cover 3 sq. degrees in V,R,I,J,K&#39;. We describe here partial results of the project concerning the clustering properties of K&#39; < 19.5 galaxies in scales of 3.6&#39;&#39; to 63.0&#39;&#39; over an area of $\sim 800 arcmin^2$. We present K&#39; data for a sample of 20 fields, five of which cont

E. Jehin, P. Magain, C. Neuforge, A. Noels

Accurate relative abundances have been obtained for a sample of 21 mildly metal-poor stars from the analysis of high resolution and high signal-to-noise spectra. With these accurate results, correlations between relative abundances have been searched for, with a special emphasis on the neutron capture elements. This analysis shows that the r elements are clo

P J Outram, B J Boyle, R F Carswell, P C Hewett

We report on high resolution observations (R=35000) of the Hubble Deep Field South QSO J2233-606 obtained with the University College London Echelle Spectrograph at the AAT. We present spectral data and an associated absorption line list for the wavelength region 3530 < lambda < 4390A. The data has a mean signal-to-noise ratio in the continuum of approximate

V. Le Brun, M. Viton, B. Milliard

We present the observation of a new intermediate redshift damped Lyman-alpha absorption system candidate, discovered in the course of a spectroscopic follow-up for identifying the sources detected in a 150 A wide bandpass UV-imaging survey at 2000 A. The system displays very strong MgII and FeII lines and a high FeII/MgII ratio, which, following photoionizat

Rupert A. C. Croft, David H. Weinberg, Max Pettini, Lars Hernquist

We measure the linear power spectrum of mass density fluctuations at redshift z=2.5 from the \lya forest absorption in a sample of 19 QSO spectra, using the method introduced by Croft et al. (1998). The P(k) measurement covers the range 2π/k ~ 450-2350 km/s (2-12 comoving \hmpc for Ω=1). We examine a number of possible sources of systematic error and find no

B. W. Miller, J. M. Lotz, H. C. Ferguson, M. Stiavelli

The specific globular cluster frequencies (S_N) for 24 dwarf elliptical (dE) galaxies in the Virgo and Fornax Clusters and the Leo Group imaged with the Hubble Space Telescope are presented. Combining all available data, we find that for nucleated dEs --- which are spatially distributed like giant ellipticals in galaxy clusters --- S_N(dE,N)=6.5 +- 1.2 and S

Robert Schwarz, Jochen Greiner

We report the discovery of a new AM Herculis system as the counterpart of the bright and very soft X-ray source RX J0803.4-4748 found serendipitously in a ROSAT PSPC pointing. Optical photometry showed deep (2 mag) variations with a period of ~137 min placing RX J0803.4-4748 right into the period gap. The modulation can be interpreted in terms of cyclotron b

T. Miyaji, G. Hasinger, M. Schmidt

We present the results and parameterization of the 0.5-2 keV Luminosity Function of AGNs from various ROSAT Surveys, ranging from the ROSAT bright Survey from the ROSAT All-Sky Survey (RASS) to the Ultra-Deep survey on the Lockman hole. A Luminosity-dependent density evolution model, where the density evolution rate drops at low luminosities, gives an excell

Y. P. Jing

The density profile and the clustering of dark matter (DM) halos are two very important ingredients for understanding many observations of galaxies. In this talk, I present our new results for these two quantities from a large set of high quality N-body simulations. We show that in an Einstein de Sitter Universe about 35 percent of the halos could not be fit

Peter Schuecker, Hans Böhringer

The likelihood filter for cluster detection introduced by Postman et al. is generalized by using standard procedures and models originally developed in the theory of point processes. The generalized method has the advantage of being less biased at the expense of some higher computational effort.

R. Brent Tully

A large luminosity--linewidth template sample is now available, improved absorption corrections have been derived, and there are a statistically significant number of galaxies with well determined distances to supply the zero point. A revised estimate of the Hubble Constant is H_0=77 +-4 km/s/Mpc where the error is the 95% probability statistical error. Syst

D. Geisler, A. Sarajedini

We have obtained CCD photometry in the Washington system C,T1 filters for some 850,000 objects associated with 10 Galactic globular clusters and 2 old open clusters. These clusters have well-known metal abundances, spanning a metallicity range of 2.5 dex from [Fe/H]~-2.25 to +0.25 at a spacing of ~0.2 dex. Analogous to the method employed by Da Costa and Arm

Jonathan Arons

After discussion of observational constraints on the nature of the MHD wind coupling between the Crab Pulsar and the Crab Nebula, the theory of transverse relativistic shock structure is reviewed and applied to the interpretation of the wisps in the Nebula as the manifestation of the distributed wind termination shock structure, energetically dominated by he

Samir Salim, Andrew Gould

Using the ground-based V and I photometry of a sample of stars from the Groth Strip, we obtain the first empirical calibration of the F606W and F814W Hubble Space Telescope WFPC2 filters for 0.5<V-I<4.5. We present results in the form of corrections that need to be applied to the two synthetic calibrations currently in use. Both calibrations are found to req

Burak Ozbagci

Let M be a smooth 4-manifold which admits a genus g Lefschetz fibration over D^2 or S^2. We develop a technique to compute the signature of M using the global monodromy of this fibration.

Matthew Parry, Richard Easther

We inaugurate a framework for studying preheating and parametric resonance after inflation without resorting to any approximations, either in gravitational perturbation theory or in the evolution of the field(s). We do this by numerically solving the Einstein field equations in the post-inflationary universe. In this letter we show how to compare our results

Philip R. Page

We demonstate from heavy quark symmetry that the width of D(2637) claimed by the DELPHI Collaboration is inconsistent with any bound state with one charm quark predicted in the D(2637) mass region, except possibly D*_3, D_2 or D&#39;. The former two possibilities are favoured by heavy quark mass relations.

N. Read, E. Rezayi

The Pfaffian quantum Hall states, which can be viewed as involving pairing either of spin-polarized electrons or of composite fermions, are generalized by finding the exact ground states of certain Hamiltonians with k+1-body interactions, for all integers k > 0. The remarkably simple wavefunctions of these states involve clusters of k particles, and are rela

Arjun Berera, Marcelo Gleiser, Rudnei O. Ramos

A quantum field theory warm inflation model is presented that solves the horizon/flatness problems. The model obtains, from the elementary dynamics of particle physics, cosmological scale factor trajectories that begin in a radiation dominated regime, enter an inflationary regime and then smoothly exit back into a radiation dominated regime, with nonnegligib

Andrew Gould, Nikolay Andronov

A major problem in the interpretation of microlensing events is that the only measured quantity, the Einstein time scale t_E, is a degenerate combination of the three quantities one would like to know, the mass, distance, and speed of the lens. This degeneracy can be partly broken by measuring either a &#34;parallax&#34; or a &#34;proper motion&#34; and comp

Karim Benakli

We study some phenomenological implications of models where the scale of quantum gravity effects lies much below the four-dimensional Planck scale. These models arise from M-theory vacua where either the internal space volume is large or the string coupling is very small. We provide a critical analysis of ways to unify electroweak, strong and gravitational i

F. Melia, M. Fatuzzo, F. Yusef-Zadeh, S. Markoff

Sgr A East is a very prominent elongated shell structure surrounding (though off-centered from) the Galactic nucleus. Its energetics (~4x10^52 ergs), based on the power required to carve out the radio synchrotron remnant within the surrounding dense molecular cloud, appear to be extreme compared to the total energy (~10^51 ergs) released in a typical superno

A. M. Beloborodov

The hard X-rays in Cyg X-1 and similar black hole sources are possibly produced in an active corona atop an accretion disk. We suggest that the observed weakness of X-ray reflection from the disk is due to bulk motion of the emitting hot plasma away from the reflector. A mildly relativistic motion causes aberration reducing X-ray emission towards the disk. T

M. Talevi

We present results for the hadron spectrum and static quark potential from a simulation with two flavours of $O(a)$ improved dynamical Wilson fermions at $β=5.2$. We address the issues of sea quark dependence of observables and finite-size effects.

Sheldon Stone

This paper summarizes current results for rare non-hadronic b decay processes. The world average Br(b -> s gamma)=(3.14 +/-0.48)x10^(-4) is in agreement with the standard model prediction. Upper limits on b-> s l^+ l^- and b -> l^+ l^- are also given. Finally B^- -> l^- nu upper limits are presented as well as the world average value of (255+/- 21 +/- 28) Me

Gunnar S. Bali, Peter Boyle

We investigate bottomonia splittings by solving a Schrodinger-Pauli-type equation with parametrisations of QCD potentials around those that have been determined previously in lattice simulations. This is done both, in the continuum and on finite lattices with resolutions ranging from a=0.2 fm down to a=0.025 fm and extent of up to 12 fm or 144^3 lattice poin

Renyue Cen, Jeremiah P. Ostriker

We analyze a new large-scale ($100h^{-1}$Mpc) numerical hydrodynamic simulation of the popular $Λ$CDM cosmological model, including in our treatment dark matter, gas and star-formation, on the basis of standard physical processes. The method, applied with a numerical resolution of $<200h^{-1}$kpc (which is still quite coarse for following individual galaxies

Michael Fleischhauer, Susanne F. Yelin

Generalized single-atom Maxwell-Bloch equations for optically dense media are derived taking into account non-cooperative radiative atom-atom interactions. Applying a Gaussian approximation and formally eliminating the degrees of freedom of the quantized radiation field and of all but a probe atom leads to an effective time-evolution operator for the probe a

Daniel Cremers, Andreas Mielke

The Henon-Heiles Hamiltonian was introduced in 1964 as a mathematical model to describe the chaotic motion of stars in a galaxy. By canonically transforming the classical Hamiltonian to a Birkhoff-Gustavson normalform Delos and Swimm obtained a discrete quantum mechanical energy spectrum. The aim of the present work is to first quantize the classical Hamilto

Rudolph C. Hwa

A method is proposed to analyze the heartbeat waveform that can yield a reliable characterization of the structure after only a few pulses. The measure suggested is entropy index that is related to the one found effective in describing chaotic behaviors in a wide variety of physical systems. When applied to the ECG data that include ventricular fibrillation,

I. S. Towner, J. C. Hardy

The value of the $V_{ud}$ matrix element of the Cabibbo-Kobayashi-Maskawa (CKM) matrix can be derived from nuclear superallowed beta decays, neutron decay, and pion beta decay. We survey current world data for all three. Today, the most precise value of $V_{ud}$ comes from the nuclear decays; however, the precision is limited not by experimental error but by

F. Barranco, R. A. Broglia, G. Gori, E. Vigezzi

The induced pairing interaction arising from the exchange of collective surface vibrations among nucleons moving in time reversal states close to the Fermi energy is found to lead to values of the pairing gap which are similar to those experimentally observed.

A. Deppman, N. Bianchi, E. De Sanctis, M. Mirazita

The forward Compton scattering amplitude for carbon and lead have been calculated from total photoabsorption cross section data by using dispersion relations. The results show a large difference between the scattering amplitudes for nuclei and the free nucleon, above the $Δ$ region. The forward Compton scattering cross sections have been calculated and compa

M. Eskef, D. Pelte, FOPI collaboration

The mass distributions of baryon resonances populated in near-central collisions of Au on Au and Ni on Ni are deduced by defolding the $p_t$ spectra of charged pions by a method which does not depend on a specific resonance shape. In addition the mass distributions of resonances are obtained from the invariant masses of $(p, π^{\pm})$ pairs. With both method

Neal J. Fowler

The universal C*-algebras of discrete product systems generalize the Toeplitz- Cuntz algebras and the Toeplitz algebras of discrete semigroups. We consider a semigroup P which is quasi-lattice ordered in the sense of Nica, and, for a product system p:E\to P, we study those representations of E, called covariant, which respect the lattice structure of P. We i

Zhen-Qing Chen, Renming Song

For a symmetric $α$-stable process $X$ on $\RR^n$ with $0<α<2$, $n\geq 2$ and a domain $D \subset \RR^n$, let $L^D$ be the infinitesimal generator of the subprocess of $X$ killed upon leaving $D$. For a Kato class function $q$, it is shown that $L^D+q$ is intrinsic ultracontractive on a Hölder domain $D$ of order 0. This is then used to establish the conditi

Zhen-Qing Chen, Renming Song

Martin boundaries and integral representations of positive functions which are harmonic in a bounded domain $D$ with respect to Brownian motion are well understood. Unlike the Brownian case, there are two different kinds of harmonicity with respect to a discontinuous symmetric stable process. One kind are functions harmonic in $D$ with respect to the whole p

Jonathan P. McCammond

In a pair of recent papers (one to appear and one forthcoming), the author develops a general version of small cancellation theory applicable in higher dimensions, and then applies this theory to the Burnside groups of sufficiently large exponent. The present article gives a brief introduction to the methods and techniques involved in the proofs. Many of the

Jonathan L. King

A proof is sketched of the Polynomial Conjecture of the author (circulated as preprint &#34;Brick Tiling and Monotone Boolean Functions&#34;, available at the http://www.math.ufl.edu/~squash/tilingstuff.html url) which says that the family of minimal tilable-boxes grows polynomially with dimension. An important ingredient of the argument is translating the p

Thomas Brady, Jonathan P. McCammond

In this article we construct a piecewise Euclidean, non-positively curved 2-complex for the 3-generator Artin groups of large type. As a consequence we show that these groups are biautomatic. A slight modification of the proof shows that many other Artin groups are also biautomatic. The general question (whether all Artin groups are biautomatic) remains open

Kevin P. Knudson

Let A be the coordinate ring of an affine elliptic curve (over an infinite field k) of the form X-{p}, where X is projective and p is a closed point on X. Denote by F the function field of X. We show that the image of H_*(GL_2(A),Z) in H_*(GL_2(F),Z) coincides with the image of H_*(GL_2(k),Z). As a consequence, we obtain numerous results about the K-theory o

E B Davies

We prove sharp L^2 boundary decay estimates for the eigenfunctions of certain second order elliptic operators acting in a bounded region, and of their first order space derivatives, using only the Hardy inequality. We then deduce bounds on the change of the eigenvalues when the region is reduced slightly in size, subject to DBCs.

A Isaev, O Ogievetsky, P Pyatov

The Cayley-Hamilton-Newton identities which generalize both the characteristic identity and the Newton relations have been recently obtained for the algebras of the RTT-type. We extend this result to a wider class of algebras M(R,F) defined by a pair of compatible solutions of the Yang-Baxter equation. This class includes the RTT-algebras as well as the Refl

Riccardo Benedetti, Carlo Petronio

We introduce and analyze the characteristic foliation induced by a contact structure on a branched surface, in particular a branched standard spine of a 3-manifold. We extend to (fairly general) singular foliations of branched surfaces the local existence and uniqueness results which hold for genuine surfaces. Moreover we show that global uniqueness holds wh

Masahiko Miyamoto

We introduce theta-functions of VOA-modules and show that the space spanned by them has a modular invariance property.

Mikhail Shubin

We study a sequence of connections which is associated with a Riemannian metric and an almost symplectic structure on a manifold. We prove that if this sequence is trivial (i.e. constant) or 2-periodic, then the manifold has a canonical Kähler structure.

Stephan Endrass

For a double solid $V\to P_3(C)$ branched over a surface $B\subset P_3(C)$ with only ordinary nodes as singularities, we give a set of generators of the divisor class group $Pic(\tilde{V}})$ in terms of contact surfaces of $B$ with only superisolated singularities in the nodes of $B$. As an application we give a condition when the integral cohomology of $\ti

E. Elizalde, Yu. I. Shil&#39;nov

Dynamical symmetry breaking is investigated for a four-fermion Nambu-Jona-Lasinio model in external electromagnetic and gravitational fields. An effective potential is calculated in the leading order of the large-N expansion using the proper-time Schwinger formalism. Phase transitions accompanying a chiral symmetry breaking in the Nambu-Jona-Lasinio model ar

Sergio Cacciatori, Daniela Zanon

In the framework of special Kahler geometry we consider the supergravity-matter system which emerges on a K3-fibered Calabi-Yau manifold. By applying the rigid limit procedure in the vicinity of a conifold singularity we compute the Kahler potential of the scalars and the kinetic matrix of the vectors to first order in the gravitational coupling.

Masaru Kamata, Atsushi Nakamula

We present a q-analogue of Nahm&#39;s formalism for the BPS monopole, which gives self-dual gauge fields with a deformation parameter q. The theory of the basic hypergeometric series is used in our formalism. In the limit q -> 1 the gauge fields approach the BPS monopole and Nahm&#39;s result is reproduced.

P. Gosdzinsky, A. Romeo

Values for the vacuum energy of scalar fields under Dirichlet and Neuman boundary conditions on an infinite clylindrical surface are found, and they happen to be of opposite signs. In contrast with classical works, a complete zeta function regularization scheme is here applied. These fields are regarded as interesting both by themselves and as the key to des

David Hochberg, Carmen Molina-Paris, Juan Perez-Mercader, Matt Visser

The existence of fluctuations together with interactions leads to scale-dependence in the couplings of quantum field theories for the case of quantum fluctuations, and in the couplings of stochastic systems when the fluctuations are of thermal or statistical nature. In both cases the effects of these fluctuations can be accounted for by solutions of the corr

Y. S. Myung

We resolve the entropy problem in the AdS$_3$/CFT correspondence by introducing both the normalizable and non-normalizable bulk modes. On the boundary, the normalizable Liouville states gives us $c=1$ conformal field theory(CFT), whereas the non-normalizable Liouville states provide $c = {3 \ell \over 2 G}$ CFT. Such (boundary) non-normalizable modes come fr

Alan Kostelecky

In this talk, a brief summary is given of the possibility of using neutral-kaon oscillations to bound CPT- and Lorentz-breaking parameters in an extension of the minimal standard model.

Liang Zuo-tang

We show that the polarization of hyperons observed in high energy collisions using unpolarized hadron beams and unpolarized nucleon or nuclear targets is closely related to the left-right asymmetries observed in single spin inclusive hadron production processes. The relationship is most obvious for the production of the hyperons which have only one common va

O. Juraev

We study and solved Schwinger-Dayson equation for massive quarks in the quark model. Interaction potential is choose as sum oscillator and Coulomb terms. The calculation show us that negative energy of quark exist under $m_{o} \ll \Vo$ i.e. when mass quark is less that parameters of scale. Us are offered to use asymptotical behaviour at the solutions Schwing

S. V. Goloskokov

We study $pp$ scattering at high energies and moderately large momentum transfer using a QCD--based model in which the proton is viewed as being composed of a quark and a diquark. This model leads to spin asymmetries which are neither small nor vanish at high energies. The predicted ratio of helicity flip and non-flip amplitudes is about 0.2-0.3 and $A_n$ as

S. V. Goloskokov

We study the dependencies of spin asymmetries in diffractive leptoproduction on the spin structure of the pomeron coupling. It is shown that the $A_{ll}$ asymmetry in diffractive processes is proportional to the fraction of the initial proton momentum $x_p$ carried off by the pomeron. The resulting asymmetries decrease with increasing energy for diffractive

Jong-Phil Lee, Chun Liu, H. S. Song

L=1 excited heavy baryon masses are analyzed by heavy quark and large N_c expansions. In heavy quark limit, mass is parameterized by Λ-bar and it is expanded further by spin-flavor breaking operators to the zeroth order of 1/N_c. Expanding coefficients will be fixed by more data on the excited baryons in the near future.

Howard D. Trottier

First results from simulations of improved actions for both gauge fields and staggered fermion fields in three dimensional QCD are presented. This work provides insight into some issues of relevance to lattice theories in four dimensions. In particular, the renormalization of the bare lattice coupling is dramatically reduced when the tree-level $O(a^2)$ impr

Christian Wieczerkowski

The tree formula, which relates proper and connected vertices, is shown to be the solution to a Hamilton-Jacobi equation.

S. Aoki, R. Frezzotti, P. Weisz

The clover coefficient $\csw$ is computed at one loop order of perturbation theory for improved gluon actions including six-link loops. The O(a) improvement coefficients for the dimension three isovector composite operators bilinear in the quark fields are also calculated.

S. Willocq

We review recent B+, B0d and b-baryon lifetime measurements performed by the LEP, SLD and CDF collaborations. Lifetime ratios of tau(B+) / tau(B0d) = 1.070 +/- 0.027 and tau(b baryon) / tau(B0d) = 0.77 +/- 0.04 are obtained using all existing measurements. The ratio between charged and neutral B meson lifetimes is in good agreement with theory but the ratio

Neil C. Rowe

We consider information retrieval when the data, for instance multimedia, is coputationally expensive to fetch. Our approach uses &#34;information filters&#34; to considerably narrow the universe of possiblities before retrieval. We are especially interested in redundant information filters that save time over more general but more costly filters. Efficient

Marino Miculan

In this paper, we present a formalization of Kozen&#39;s propositional modal $μ$-calculus, in the Calculus of Inductive Constructions. We address several problematic issues, such as the use of higher-order abstract syntax in inductive sets in presence of recursive constructors, the encoding of modal (``proof&#39;&#39;) rules and of context sensitive grammars

Denis V. Juriev

The article is devoted to a problem of elaboration of the real-time interactive videosystems for accelerated nonverbal cognitive computer and telecommunications. The proposed approach is based on the using of droems (dynamically reconstructed objects of experimental mathematics) and interpretational figures as pointers to them. Four paragraphs of the article

Satoshi Horie, Osamu Watanabe

We propose an algorithm of generating hard instances for the Satisfying Assignment Search Problem (in short, SAT). The algorithm transforms instances of the integer factorization problem into SAT instances efficiently by using the Chinese Remainder Theorem. For example, it is possible to construct SAT instances with about 5,600 variables that is as hard as f

N. Miyakawa, J. F. Zasadzinski, L. Ozyuzer, P. Guptasarma

New tunneling data are reported in underdoped Bi2Sr2CaCu2O8-d using superconductor-insulator-superconductor break junctions. Energy gaps, Delta, of 51+2, 54+2 and 57+3 meV are observed for three crystals with Tc=77, 74, and 70 K respectively. These energy gaps are nearly three times larger than for overdoped crystals with similar Tc. Detailed examination of

Bernardo A. Huberman, Dirk Helbing

We present an economics-based method for deciding the optimal rates at which vehicles are allowed to enter a highway. The method exploits the naturally occuring fluctuations of traffic flow and is flexible enough to adapt in real time to the transient flow characteristics of road traffic. Simulations based on realistic parameter values show that this strateg

Angela Foerster, Jon Links, Itzhak Roditi

We present a new integrable model for correlated electrons which is based on a $so(5)$ symmetry. By using an $η$-pairing realization we construct eigenstates of the Hamiltonian with off-diagonal long-range order. It is also shown that these states lie in the ground state sector. We exactly solve the model on a one-dimensional lattice by the Bethe ansatz.

Daniel Dominguez

We study the dynamics of vortices in strongly disordered $d=2$ Josephson junction arrays and superconducting films driven by a current. We find a dynamic phase transition in vortex flow at a current $I_p>I_c$. Below $I_p$ there is plastic flow characterized by an average-velocity correlation length scale $ξ_v$ in the direction of motion, which diverges when

X. S. Chen, V. Dohm

We present a perturbative calculation of finite-size effects near $T_c$ of the $ϕ^4$ lattice model in a $d$-dimensional cubic geometry of size $L$ with periodic boundary conditions for $d > 4$. The structural differences between the $ϕ^4$ lattice theory and the $ϕ^4$ field theory found previously in the spherical limit are shown to exist also for a finite nu

N. Gayathri, A. K. Raychaudhuri

In this paper we report the results of electrical resistivity (1.5K < T <300K) and point contact spectroscopy (PCS) measurements on single crystals of metallic sodium tungsten bronze with varying sodium content. We have shown that the electron-phonon coupling function as measured through PCS can explain quantitatively the large temperature dependence of resi

K. Binder, J. Baschnagel, C. Bennemann, W. Paul

Two coarse-grained models for polymer chains in dense glass-forming polymer melts are studied by computer simulation: the bond-fluctuation model on a simple cubic lattice, where a bond-length potential favors long bonds, is treated by dynamic Monte Carlo methods, and a bead-spring model in the continuum with a Lennard-Jones potential between the beads is tre

D. Duque, P. Tarazona, E. Chacon

A microscopic model which has proven useful in describing amphiphilic aggregates as inhomogeneities of a fluid is extended here to study the case of a two component surfactant mixture. We have chosen an effective interaction between the amphiphiles that mimics the mixture of cationic--anionic surfactants. In agreement with experiments, and other theoretical

Anatoly A. Ignatov, Antti-Pekka Jauho

The current responsivity of a semiconductor superlattice THz-photon detector is calculated using an equivalent circuit model which takes into account the finite matching efficiency between a detector antenna and the superlattice in the presence of parasitic losses. Calculations performed for currently available superlattice diodes show that both the magnitud

K. Samokhin

We study analytically the asymptotic behaviour of the average probability P(n,t) for the trajectory of a 2D Brownian particle wandering in the presence of randomly distributed traps to wind n times around a given point after a time t. It is shown that P(n,t)\sim\exp(-c\sqrt{t}) (1+x^2)^{-1} with x\sim n/\sqrt{t}, where the first exponent represents a well kn

Tom Chou

We study the effects of solute interactions on osmotic transport through pores. By extending single-file, single-species kinetic models to include entrance of solute into membrane pores, we model the statistical mechanics of competitive transport of two species across membrane pores. The results have direct applications to water transport across biomembrane

S. Flach

We analyze the properties of breathers (time periodic spatially localized solutions) on chains in the presence of algebraically decaying interactions $1/r^s$. We find that the spatial decay of a breather shows a crossover from exponential (short distances) to algebraic (large distances) decay. We calculate the crossover distance as a function of $s$ and the

Christophe Chatelain, Pierre Emmanuel Berche, Bertrand Berche

We investigate the influence of aperiodic modulations of the exchange interactions between nearest-neighbour rows on the phase transition of the two-dimensional eight-state Potts model. The systems are studied numerically through intensive Monte Carlo simulations using the Swendsen-Wang cluster algorithm for different aperiodic sequences. The transition poin

B. Chopard, M. Droz, J. Magnin, Z. Rácz

The effect of dissociation of the invading electrolyte on the formation of Liesegang bands is investigated. We find, using organic compounds with known dissociation constants, that the spacing coefficient, 1+p, that characterizes the position of the n-th band as x_n ~ (1+p)^n, decreases with increasing dissociation constant, K_d. Theoretical arguments are de

J. Zhong, H. -B. Schuttler

We develop a simple diagrammatic low-energy boson exchange strong-coupling model for an antiferromagnetically correlated polaronic metal. Important low-temperature features of such a model are (i) a large polaronic mass enhancement $Z$ and a strongly narrowed, low-energy, near-Fermi-level van Hove resonance peak in the interacting density of states at temper

S. Park, H. Jeong, B. Kahng

We perform Monte Carlo simulations on stochastic models such as the Wolf-Villain (WV) model and the Family model in a modified version to measure mean separation $\ell$ between islands in submonolayer regime and damping time $\tilde t$ of layer-by-layer growth oscillations on one dimension. The stochastic models are modified, allowing diffusion within interv