September 2000 arXiv papers — page 7

M. I. Katsnelson, V. V. Dobrovitski, B. N. Harmon

Single-site measurement in a distributed macroscopic antiferromagnet is considered; we show that it can create antiferromagnetic sublattices at macroscopic scale. We demonstrate that the result of measurement depends on the symmetry of the ground state: for the easy-axis case the Neel state is formed, while for the easy-plane case unusual ``fan'' sub

Jose L. Cereceda

Relativistic causality, namely, the impossibility of signaling at superluminal speeds, restricts the kinds of correlations which can occur between different parts of a composite physical system. Here we establish the basic restrictions which relativistic causality imposes on the joint probabilities involved in an experiment of the Einstein-Podolsky-Rosen-Boh

Pavel L. Chapovsky

Theoretical model of the nuclear spin conversion in formaldehyde (H2CO) has been developed. The conversion is governed by the intramolecular spin-rotation mixing of molecular ortho and para states. The rate of conversion has been found equal 1.4*10^{-4}~1/s*Torr. Temperature dependence of the spin conversion has been predicted to be weak in the wide temperat

Sho Tanaka

We propose relativistic second quantization of matrix model of D particles in a general framework of nonlocal field theory based on Snyder-Yang's quantized space-time. Second-quantized nonlocal field is in general noncommutative with quantized space-time, but conjectured to become commutative with light cone time $X^+$. This conjecture enables us to find

Massimo Rontani, L. J. Sham

We propose a junction of metal and rare-earth compound semiconductor as the basis for a possible efficient low-temperature thermoelectric device. If an overlayer of rare earth atoms differing from the bulk is placed at the interface, very high values of the figure of merit ZT can be reached at low temperature. This is due to sharp variation of the transmissi

L. S. Braginsky, M. Yu. Zaharov, A. M. Gilinsky, V. V. Preobrazhenskii

The exciton decay rate at a rough interface in type-II semiconductor superlattices is investigated. It is shown that the possibility of recombination of indirect excitons at a plane interface essentially affects kinetics of the exciton photoluminescence at a rough interface. This happens because of strong correlation between the exciton recombination at the

F. Bertoldi, B. T. Draine, D. Rosenthal, R. Timmermann

Photodissociation regions (PDRs) and shocks give rise to conspicuous emission from rotationally and vibrationally excited molecular hydrogen. This line emission has now been studied with ISO and from the ground in great detail. A remarkable discovery has been that toward the Orion outflow and other shock-excited regions, the H_2 level populations show a very

Amir Levinson

The possibility that rapidly rotating supermassive black holes associated with quasar remnants may provide sites for the acceleration of ultra-high energy cosmic rays (UHECRs) is considered. It is shown that prodigious TeV emission through curvature losses is an important consequence of this mechanism. Given the measured UHECR flux, it is expected that nearb

S. Andreon

The deep near-infrared luminosity function of AC118, a cluster of galaxies at z=0.3, is presented. AC118 is a bimodal cluster, as evidenced both by our near-infrared images of lensed galaxies, by public X-ray Rosat images and by the spatial distribution of bright galaxies. Taking advantage of the extension and depth of our data, which sample an almost unexpl

J. D. Cohn, J. S. Bagla, Martin White

We use large volume, high resolution, N-body simulations of 3 different $Λ$CDM models, with different clustering strengths, to generate dark matter halo merging histories. Over the reliable range of halo masses, roughly galaxy groups to rich clusters of galaxies, we quantify the number density of major mergers for two different time intervals and compare wit

Gui-Lu Long, Yang Sun

The projected shell model implements shell model configuration mixing in the projected deformed basis. Our analysis on the recently observed superdeformed band in $^{36}$Ar suggests that the neutron and proton 2-quasiparticle and the 4-quasiparticle bands cross the superdeformed ground band at the same angular momentum. This constitutes a picture of band dis

M. Cadoni, P. Carta, D. Klemm, S. Mignemi

We show that two-dimensional (2D) AdS gravity induces on the spacetime boundary a conformally invariant dynamics that can be described in terms of a de Alfaro-Fubini-Furlan model coupled to an external source with conformal dimension two. The external source encodes the information about the gauge symmetries of the 2D gravity system. Alternatively, there exi

Vladimir G. Ivanov, Savely G. Karshenboim

Calculation of higher-order two-loop corrections is now a limiting factor in development of the bound state QED theory of the Lamb shift in the hydrogen atom and in precision determination of the Rydberg constant. Progress in the study of light hydrogen-like ions of helium and nitrogen can be helpful to investigate these uncalculated terms experimentally. To

D. H. T. Franco, M. S. Goes-Negrao, J. A. Helayel-Neto, A. R. Pereira

One discusses here the connection between σ-model gauge anomalies and the existence of a connection with torsion that does not flatten the Ricci tensor of the target manifold, by considering a number of non-symmetric coset spaces. The influence of an eventual anisotropy on a certain direction of the target manifold is also contemplated.

Ulf H. Danielsson, Alberto Guijosa, Martin Kruczenski

We examine the T-duality relation between 1+1 NCOS and the DLCQ limit of type IIA string theory. We show that, as long as there is a compact dimension, one can meaningfully define an `NCOS' limit of IIB/A string theory even in the absence of D-branes (and even if there is no B-field). This yields a theory of closed strings with strictly positive winding,

B. Carter, R. Brandenberger, A. -C. Davis, G. Sigl

This investigation is concerned with cosmological scenarios based on particle physics theories that give rise to superconducting cosmic strings (whose subsequent evolution may produce stable loop configurations known as vortons). Cases in which electromagnetic coupling of the string current is absent or unimportant have been dealt with in previous work. The

Boris Svistunov

We consider the ordering kinetics in a strongly non-equilibrium state of a (weakly) interacting Bose gas, characterized, on one hand, by large occupation numbers, and, on the other hand, by the absence of long-range order. Up to higher-order corrections in inverse occupation numbers, the evolution is described by non-linear Schrodinger equation with a turbul

Wei Cui, N. S. Schulz, F. K. Baganoff, M. W. Bautz

We present the discovery of peculiar extended X-ray emission around 1E1740.7-2942, a black hole candidate that is known to produce prominent, persistent radio jets. The data was obtained with the High-Energy Transmission Grating Spectrometer (HETGS) aboard the Chandra X-ray Observatory. The zeroth-order image reveals an elongated feature about 3" in leng

John S. Mulchaey

ROSAT observations indicate that approximately half of all nearby groups of galaxies contain spatially extended X-ray emission. The radial extent of the X-ray emission is typically 50-500 kpc or approximately 10-50% of the virial radius of the group. Diffuse X-ray emission is generally restricted to groups that contain at least one early-type galaxy. X-ray s

Steven B. Giddings, Emanuel Katz

We investigate aspects of the four-dimensional effective description of brane world scenarios based on warped compactification on anti-de Sitter space. The low-energy dynamics is described by visible matter gravitationally coupled to a ``dark'' conformal field theory. We give the linearized description of the 4d stress tensor corresponding to an arbi

P. F. Peterson, Th. Proffen, I. -K. Jeong, S. J. L. Billinge

High real-space resolution atomic pair distribution functions (PDFs) have been obtained from ZnSe(1-x)Te(x) using neutron powder diffraction. Distinct Zn-Se and Zn-Te nearest neighbor (nn) bonds, differing in length by delta_r= 0.14Angstroms, are resolved in the measured PDF allowing the evolution with composition of the individual bond-lengths to be studied

F. Carvalho, F. O. Durães, F. S. Navarra, M. Nielsen

We have applied the meson cloud model (MCM) to calculate the asymmetries in $D$ and $D_s$ meson production in high energy $Σ^-$-nucleus and $π^-$-nucleus collisions. We find a good agreement with recent data. Our results suggest that the asymmetries may decrease at large $x_F$.

Jaume Gomis, Hirosi Ooguri

We construct a Galilean invariant non-gravitational closed string theory whose excitations satisfy a non-relativistic dispersion relation. This theory can be obtained by taking a consistent low energy limit of any of the conventional string theories, including the heterotic string. We give a finite first order worldsheet Hamiltonian for this theory and show

M. Svec

Additivity of Breit-Wigner phases has been proposed to describe interfering resonances in partial waves in $ππ$ scattering. This assumption leads to an expression for partial wave amplitudes that involves products of Breit-Wigner amplitudes. We show that this expression is equivalent to a coherent sum of Breit-Wigner amplitudes with specific complex coeffici

A. V. Afanasev, I. Akushevich, N. P. Merenkov

Model independent radiative correction to the recoil proton polarization for the elastic electron-proton scattering is calculated within method of electron structure functions. The explicit expressions for the recoil proton polarization are represented as a contraction of the electron structure and the hard part of the polarization dependent contribution int

Georges Grunberg

A physical characterization of Landau singularities is emphasized, which should trace the lower boundary N_f^* of the conformal window in QCD and supersymmetric QCD. A natural way to disentangle ``perturbative'' from ``non-perturbative'' contributions to amplitudes below N_f^* is suggested. Assuming an infrared fixed point persists in the per

Alexei Tsygvintsev

We consider a plane polynomial vector field $P(x,y)dx+Q(x,y)dy$ of degree $m>1$. To each algebraic invariant curve of such a field we associate a compact Riemann surface with the meromorphic differential $ω=dx/P=dy/Q$. The asymptotic estimate of the degree of an arbitrary algebraic invariant curve is found. In the smooth case this estimate was already found

P. Chankowski, T. Farris, B. Grzadkowski, J. F. Gunion

We consider a CP-conserving two-Higgs-doublet type II model with a light scalar or pseudoscalar neutral Higgs boson ($\h=\hl$ or $\h=\ha$) that has no $ZZ/WW$ coupling and, thus, cannot be detected in $\epem\to Z\h$ (Higgs-strahlung) or $ν\antiν\h$ (via $WW$ fusion). Despite sum rules which ensure that the light $\h$ must have significant $t\anti t$ or $b\an

N. Pinto-Neto, E. Sergio Santini

We consider quantum geometrodynamics and parametrized quantum field theories in the framework of the Bohm-de Broglie interpretation. In the first case, and following the lines of our previous work [1], where a hamiltonian formalism for the bohmian trajectories was constructed, we show the consistency of the theory for any quantum potential, completing the sc

Eef van Beveren, George Rupp, Michael D. Scadron

We exploit the W-emission process to study the measured weak decay of the D(s,+)(1.9686) meson into f(0)(980) and a positively charged pion. We conclude that the scalar f(0)(980) meson contains mostly strange-antistrange flavors, which is supported by different model studies.

M. Karlovini, K. Rosquist, L. Samuelsson

We discuss the construction of perfect fluid stellar objects having optical geometries with multiple necks corresponding to spatially closed unstable lightlike geodesics. We prove that there exist physically reasonable models with arbitrarily many necks. We also show how a first order phase transition can give rise to quite pronounced secondary double necks.

Jefferson Lab Hall A Collaboration, N. Liyanage

We measured the cross section and response functions (R_L, R_T, and R_LT) for the 16O(e,e&#39;p) reaction in quasielastic kinematics for missing energies 25 <= E_miss <= 120 MeV at various missing momenta P_miss <= 340 MeV/c. For 25 < E_miss < 50 MeV and P_miss \approx 60 MeV/c, the reaction is dominated by single-nucleon knockout from the 1s1/2-state. At la

Giovanni Bonanno, Fabrizio Lillo, Rosario N. Mantegna

The high-frequency cross-correlation existing between pairs of stocks traded in a financial market are investigated in a set of 100 stocks traded in US equity markets. A hierarchical organization of the investigated stocks is obtained by determining a metric distance between stocks and by investigating the properties of the subdominant ultrametric associated

J. Rehacek, Z. Hradil, M. Jezek

An iterative algorithm for the reconstruction of an unknown quantum state from the results of incompatible measurements is proposed. It consists of Expectation-Maximization step followed by a unitary transformation of the eigenbasis of the density matrix. The procedure has been applied to the reconstruction of the entangled pair of photons.

Francis Comets, Roberto Fernandez, Pablo A. Ferrari

We present a perfect simulation algorithm for stationary processes indexed by Z, with summable memory decay. Depending on the decay, we construct the process on finite or semi-infinite intervals, explicitly from an i.i.d. uniform sequence. Even though the process has infinite memory, its value at time 0 depends only on a finite, but random, number of these u

N. Ryde, F. L. Schoeier

We have modelled the circumstellar envelope of {\it o} Ceti (Mira) using new observational constraints. These are obtained from photospheric light scattered in near-IR vibrational-rotational lines of circumstellar CO molecules at 4.6 micron: absolute fluxes, the radial dependence of the scattered intensity, and two line ratios. Further observational constrai

Qiuping A. Wang

Statistical mechanics is generalized on the basis of an information theory for inexact or incomplete probability distributions. A parameterized normalization is proposed and leads to a nonextensive entropy. The resulting incomplete statistical mechanics is proved to have the same theoretical characteristics as Tsallis one based on the conventional normalizat

Archana Pai, Sanjeev Dhurandhar, Sukanta Bose

A data-analysis strategy based on the maximum-likelihood method (MLM) is presented for the detection of gravitational waves from inspiraling compact binaries with a network of laser-interferometric detectors having arbitrary orientations and arbitrary locations around the globe. The MLM is based on the network likelihood ratio (LR), which is a function of ei

G. M. Pritula, V. E. Vekslerchik

Stationary structures in a classical isotropic two-dimensional continuous Heisenberg ferromagnetic spin system are studied in the framework of the (2+1)-dimensional Landau-Lifshitz model. It is established that in the case of \vec S (\vec r, t)= \vec S (\vec r - \vec v t) the Landau-Lifshitz equation is closely related to the Ablowitz-Ladik hierarchy. This r

K. Takehana, T. Takamasu, M. Hase, G. Kido

The doping effect of the folded phonon mode at 98 cm$^{-1}$ was investigated on the Si-doped CuGeO$_3$ by magneto-optical measurements in far-infrared (FIR) region under high magnetic field. The folded phonon mode at 98 cm$^{-1}$ appears not only in the dimerized (D) phase but also in the dimerized-anitiferromagnetic (DAF) phase on the doped CuGeO$_3$. The s

Fuad M. Saradzhev

We study the self-interaction effects for the Dirac particle moving in an external field created by static charges in (1+1)-dimensions. Assuming that the total electric charge of the system vanishes, we show that the asymptotically linearly rising part of the external potential responsible for nonexistence of bound states in the external field problem withou

Curtis Manning, Hyron Spinrad

Radio galaxies characteristically have strong Lya emission lines. However, a few have Lya equivalent widths that are substantially weaker in relation to other emission lines. One in particular was studied by Dey etal (1995), MG 1019+0535 (z=2.765). We report on our reduction of Infrared Space Observatory (ISO}) data in the 160 micron-band for this galaxy. We

Alexei Trifonov, Gunnar Bjork, Jonas Soderholm, Tedros Tsegaye

In an interferometer, path information and interference visibility are incompatible quantities. Complete determination of the path will exclude any possibility of interference, rendering the visibility zero. However, if the composite object and probe state is pure, it is, under certain conditions, possible to trade the path information for improved (conditio

R. M. Serra, N. G. de Almeida, C. J. Villas-Boas, M. H. Y. Moussa

We propose a reliable scheme for engineering a general cavity-field state. This is different from recently presented strategies,where the cavity is supposed to be initially empty and the field is built up photon by photon through resonant atom-field interactions. Here, a coherent state is previously injected into the cavity. So, the Wigner distribution funct

Matteo G. A. Paris

A conditional scheme to prepare optical superposition of the vacuum and one-photon states using linear elements (beam splitters and phase-shifters) and avalanche photodetectors is suggested.

Dominik Janzing, Thomas Beth

We consider unitary dynamical evolutions on n qubits caused by time dependent pair-interaction Hamiltonians and show that the running time of a parallelized two-qubit gate network simulating the evolution is given by the time integral over the chromatic index of the interaction graph. This defines a complexity measure of continuous and discrete quantum algor

A. R. Usha Devi

We carryout a comparative study of spin distributions defined over the sphere for bipartite quantum spin assemblies. We analyse Einstein-Podolsky-Rosen-Bohm (EPRB) spin correlations in a spin-s singlet state using these distributions. We observe that in the classical limit EPRB spin distributions turn out to be delta functions, thus reflecting the perfect an

Bao-An Li

The neutron-proton differential flow is shown to be a very useful probe of the isospin-dependence of the nuclear equation of state (EOS). This novel approach utilizes constructively both the isospin fractionation and the nuclear collective flow as well as their sensitivities to the isospin-dependence of the nuclear EOS. It also avoids effectively uncertainti

Harald A. Forbert, Siu A. Chin

By decomposing the important sampled imaginary time Schrödinger evolution operator to fourth order with positive coefficients, we derived a number of distinct fourth order Diffusion Monte Carlo algorithms. These sophisticated algorithms require higher derivatives of the drift velocity and local energy and are more complicated to program. However, they allowe

E. Epelbaum, H. Kamada, A. Nogga, H. Witala

We employ the chiral nucleon-nucleon potential derived using the method of unitary transformation up to next-to-next-to-leading order (NNLO) to study bound and scattering states in the two-nucleon system. The predicted partial wave phase shifts and mixing parameters for higher energies and higher angular momenta beyond the ones which are fitted are mostly we

L. E. Marcucci

The results of a new calculation of the astrophysical S-factor for the proton weak capture on 3He are here reviewed. The methods used to obtain very accurate initial and final state wave functions and to construct the nuclear weak current operator are described. Finally the implications of these results for the Super-Kamiokande solar neutrino data are discus

Sylvie Oliffson Kamphorst, Sonia Pinto de Carvalho

We investigate the existence of elliptic islands for a special family of periodic orbits of a two-parameter family of maps corresponding to the billiard problem on the elliptical stadium. The hyperbolic or elliptical character of these orbits is also investigated. Depending on the parameters, we obtain upper bounds of ellipticity for this special family as a

Michael R. Douglas

We give an overview of recent work on Dirichlet branes on Calabi-Yau threefolds which makes contact with Kontsevich&#39;s homological mirror symmetry proposal, proposes a new definition of stability which is appropriate in string theory, and provides concrete quiver categories equivalent to certain categories of branes on CY. To appear in the proceedings of

Mihail N. Kolountzakis, Michael Papadimitrakis

We give a short proof of the fact that there are no measurable subsets of Euclidean space (in dimension d > 2), which, no matter how translated and rotated, always contain exactly one integer lattice point. In dimension d=2 (the original Steinhaus problem) the question remains open.

Francois Labourie

The main result is the construction of ergodic transversal measures of full support on the space of all k-surfaces of a compact hyperbolic 3-manifold. This space is a laminated space, each of its leaf being identified with a &#34;complete&#34; k-surface, i.e. a surface of constant (extrinsic) curvature k, where k belongs to ]0,1[. Elsewhere, this space has b

Frederic Helein, Pascal Romon

We study Hamiltonian stationary Lagrangian surfaces in C^2, i.e. Lagrangian surfaces in C^2 which are stationary points of the area functional under smooth Hamiltonian variations. Using loop groups, we propose a formulation of the equation as a completely integrable system. We construct a Weierstrass type representation and produce all tori through either th

Finlay Thompson

The notion of a quaternionic gerbe is presented as a new way of bundling algebraic structures over a four manifold. The structure groupoid of this fibration is described in some detail. The Euclidean conformal group R*SO(4) appears naturally as a (non-commutative) monoidal structure on this groupoid. Using this monoidal structure we indicate the existence of

Alexander Postnikov

The group (Z/nZ)^2 is shown to act on the Gromov-Witten invariants of the complex flag manifold. We also deduce several corollaries of this result.

K. Alladi, A. Berkovich

Given integers i,j,k,L,M, we establish a new double bounded q-series identity from which the three parameter (i,j,k) key identity of Alladi-Andrews-Gordon for Goellnitz&#39;s (big) theorem follows if L, M tend to infinity. When L = M, the identity yields a strong refinement of Goellnitz&#39;s theorem with a bound on the parts given by L. This is the first ti

Fedele Lizzi, Gianpiero Mangano, Gennaro Miele

We observe that the main feature of the Randall-Sundrum model, used to solve the hierarchy problem, is already present in a class of Yang-Mills plus gravity theories inspired by noncommutative geometry. Strikingly the same expression for the Higgs potential is found in two models which have no apparent connection. Some speculations concerning the possible re

C. P. Natividade, A. de Souza Dutra, H. Boschi-Filho

We study the presence of symmetry transformations in the Faddeev-Jackiw approach for constrained systems. Our analysis is based in the case of a particle submitted to a particular potential which depends on an arbitrary function. The method is implemented in a natural way and symmetry generators are identified. These symmetries permit us to obtain the absent

Naresh Dadhich

We propose that for non-localizable energy distribution the relevant energy condition is determined by the gravitational field energy which is negative for positive non-gravitational energy. That is negativity of the non-localized energy is the &#34;positive&#34; energy condition. This would have direct application and relevance for a black hole on the brane

Jin Young Kim

We consider the motion of the brane universe moving in a background bulk space of tachyonic and non-tachyonic type 0B string theory. The effective densities are calculated for both cases and they show different power law behavior. Brane inflation for non-tachyonic type 0B background has the same power law behavior as that for type IIB background. The brane i

Diego Bellisai, Jose&#39; M. Isidro, Marco Matone

We show that the recently proposed formulation of noncommutative N=2 Super Yang-Mills theory implies that the commutative and noncommutative effective coupling constants τ(u) and τ_{nc}(u) coincide. We then introduce a key relation which allows to find a nontrivial solution of such equation, thus fixing the form of the low-energy effective action. The depend

Brent D. Nelson

We study the phenomenology of a class of models describing modular invariant gaugino condensation in the hidden sector of a low-energy effective theory derived from the heterotic string. Placing simple demands on the resulting observable sector - such as proper electroweak symmetry-breaking, superpartner spectra consistent with current limits and neutralino

Hilmar Forkel

We construct improved QCD sum rules for the nucleon magnetic moments by implementing direct-instanton contributions to the operator product expansion of the nucleon correlator in a magnetic background field. The instanton contributions are found to affect only those sum rules which had previously been considered unstable. The new sum rules show a high degree

V. N. Baier

The coherent scattering of photon in the Coulomb field (the Delbrück scattering) is considered for the momentum transfer $Δ\ll m$ in the frame of the quasiclassical operator method. In high-energy region this process occurs over rather long distance. The process amplitude is calculated taking into account the multiple scattering of particles of the intermedi

G. L. Fogli, E. Lisi, A. Marrone, D. Montanino

We briefly review the current status of standard oscillations of atmospheric neutrinos in schemes with two, three, and four flavor mixing. It is shown that, although the pure ν_μ-->ν_τchannel provides an excellent 2νfit to the data, one cannot exclude, at present, the occurrence of additional subleading ν_μ-->ν_e oscillations (3νschemes) or of sizable ν_μ-->

Thomas Mannel, Stefan Recksiegel

We discuss the non-perturbative and the radiative corrections to inclusive B decays from the point of view known from QED corrections to high energy e^+ e^- processes. Here the leading contributions can be implemented through the so called ``radiator function&#39;&#39; which corresponds to the shape function known in heavy hadron decays. In this way some new

M. R. Pennington

Minkowski and Ochs have recently argued that the small two photon coupling of a conjectured $σ(600)$ is so small that it is likely to be a glueball. We ask whether this can be so or whether it is simply gauge invariance that produces the observed low mass suppression?

R. Buras, D. V. Semikoz

A large lepton asymmetry could be generated in the Early Universe by oscillations of active to sterile neutrinos with a small mixing angle sin 2 θ< 10^-2. The final order of magnitude of the lepton asymmetry ηis mainly determined by its growth in the last stage of evolution when the MSW resonance dominates the kinetic equations. In this paper we present a si

O. Nachtmann, A. Rauscher

The single-particle inclusive differential cross-section for a reaction $a+b\to c+X$ is written as imaginary part of a correlation function in a forward scattering amplitude for $a+b\to a+b$ in a modified effective theory. In this modified theory the interaction Hamiltonian $\tilde H_I$ equals $H_I$ of the original theory up to a certain time. Then there is

Kazuyuki Kanaya

Results of a systematic lattice QCD simulation with two degenerate flavors of sea quarks, identified as dynamical u and d quarks, are presented. The simulation was performed on a dedicated parallel computer, called CP-PACS, developed at the University of Tsukuba. Clear dynamical quark effects are observed in the light hadron mass spectrum and in the light qu

Herbert Neuberger

Noncompact chiral abelian gauge theories are defined on the lattice using the overlap formalism. The main definitions are presented, the role of anomaly cancelation is discussed, and the triviality issue in four dimensions is explained.

Herbert Neuberger

The main ideas behind the new ways to preserve chiral symmetries for lattice fermions are presented. The discussion is focused on vector-like fermions, the case relevant for lattice QCD.

M. Oevers, C. Davies, J. Shigemitsu

According to the Narnhofer Thirring Theorem interacting systems at finite temperature cannot be described by particles with a sharp dispersion law. It is therefore mandatory to develop new methods to extract particle masses at finite temperature. The Maximum Entropy method offers a path to obtain the spectral function of a particle correlation function direc

Steven R. Blusk

We present a summary of top quark physics results from Run 1 at CDF using the Run 1 data sample of 106 pb$^{-1}$. In addition to the precursory measurements of the top quark mass and $\ttbar$ cross section, we have performed a number of other analyses which test the consistency of the $\ttbar$ data sample with the standard model (SM). Deviations from SM expe

SELEX Collaboration, M. Iori

Preliminary results on asymmetry for Lc produced by Sigma-,pi- and p beams at xf>0.2 and precise measurements of the Lc,D0 and Ds lifetimes are presented.

M. N. Achasov, S. E. Baru, K. I. Beloborodov, A. V. Berdyugin

A search for direct production of C-even resonances a2(1320) and f2(1270) in e+e- annihilation was performed with SND detector at VEPP-2M e+e- collider. The upper limits of electronic widths of these mesons were obtained at 90% confidence level: Gamma(a2(1320) \to e+e-) < 0.56 eV, Gamma(f2(1270) \to e+e-) < 0.11 eV.

Eloy Ayón-Beato, Alberto García

The Bardeen model -- the first regular black hole model in General Relativity -- is reinterpreted as the gravitational field of a nonlinear magnetic monopole, i.e., as a magnetic solution to Einstein equations coupled to a nonlinear electrodynamics.

William A. Hiscock

Several recent possible counterexamples to the Chronology Protection Conjecture are critically examined. The ``adapted&#39;&#39; Rindler vacuum state constructed by Li and Gott for a conformal scalar field in Misner space is extended to nonconformally coupled and self-interacting scalar fields. For these fields, the vacuum stress-energy always diverges on th

Alex Brodsky, Stephane Durocher, Ellen Gethner

A drawing of a graph G in the plane is said to be a rectilinear drawing of G if the edges are required to be line segments (as opposed to Jordan curves). We assume no three vertices are collinear. The rectilinear crossing number of G is the fewest number of edge crossings attainable over all rectilinear drawings of G. Thanks to Richard Guy, exact values of t

Gerard Escudero, Lluis Marquez, German Rigau

This paper describes a set of comparative experiments, including cross-corpus evaluation, between five alternative algorithms for supervised Word Sense Disambiguation (WSD), namely Naive Bayes, Exemplar-based learning, SNoW, Decision Lists, and Boosting. Two main conclusions can be drawn: 1) The LazyBoosting algorithm outperforms the other four state-of-the-

Rajkumar Buyya, David Abramson, Jon Giddy

The availability of powerful microprocessors and high-speed networks as commodity components has enabled high performance computing on distributed systems (wide-area cluster computing). In this environment, as the resources are usually distributed geographically at various levels (department, enterprise, or worldwide) there is a great challenge in integratin

Mark Baker, Rajkumar Buyya, Dan Hyde

When you first heard people speak of Piles of PCs, the first thing that came to mind may have been a cluttered computer room with processors, monitors, and snarls of cables all around. Collections of computers have undoubtedly become more sophisticated than in the early days of shared drives and modem connections. No matter what you call them, Clusters of Wo

Alon Efrat, Piotr Indyk, Suresh Venkatasubramanian

In this paper we present algorithms for a number of problems in geometric pattern matching where the input consist of a collections of segments in the plane. Our work consists of two main parts. In the first, we address problems and measures that relate to collections of orthogonal line segments in the plane. Such collections arise naturally from problems in

Jaewook Joo, Viktor Oudovenko

We present clear numerical evidence for the coexistence of metallic and insulating dynamical mean field theory(DMFT) solutions in a half-filled single-band Hubbard model with bare semicircular density of states at finite temperatures. Quantum Monte Carlo(QMC) method is used to solve the DMFT equations. We discuss important technical aspects of the DMFT-QMC w

D. Lilliehook, J. E. Furneaux

We have reexamined data on the possible two dimensional metal-insulator transition at B=0 in Si-MOSFETs using a nonlinear regression method to extract all scaling parameters in a single fit. By keeping track of the magnitude of errors in the data we can use the normalized mean square deviation χ^2 of the fit as a quantitative measure of how well the data is

T. J. Newman, Will Loinaz

We study the evolution of a random initial field under pure diffusion in various space dimensions. From numerical calculations we find that the persistence properties of the system show sharp transitions at critical dimensions d1 ~ 26 and d2 ~ 46. We also give refined measurements of the persistence exponents for low dimensions.

Jeng-Bang Yau, Jeng-Ping Lu, Harindran C. Manoharan, Mansour Shayegan

Measurements of commensurability oscillations in GaAs/AlGaAs two-dimensional (2D) hole systems grown on GaAs (311)A substrates reveal a remarkable anisotropy: the amplitude of the measured commensurability oscillations along the [$\bar{2}$33] direction is about 100 times larger than along [01$\bar{1}$]. For 2D electron systems at similar interfaces, however,

B. Goodman, R. A. Serota

We study small conducting particles and thin films in an oscillating longitudinal electric field. We find the charge, current, and field distribution in the particle, the polarizability and the electric dipole absorption. We account for Thomas-Fermi screening by adding a Fick&#39;s diffusion term to Ohm&#39;s law. Alternatively, we describe a particle as a d

R. Shankar

I furnish details of the hamiltonian theory of the FQHE developed with Murthy for the infrared, which I subsequently extended to all distances and apply it to Jain fractions ν= p/(2ps + 1). The explicit operator description in terms of the CF allows one to answer quantitative and qualitative issues, some of which cannot even be posed otherwise. I compute act

Igor I. Smolyaninov, Vitaliy V. Zavyalov

Two-dimensional electron system on the liquid helium surface is one of the leading candidates for constructing large analog quantum computers (P.M. Platzman and M.I. Dykman, Science 284, 1967 (1999)). Similar electron systems on the surfaces of solid hydrogen or solid neon may have some important advantages with respect to electrons on liquid helium in quant

Federico Becca, Luca Capriotti, Sandro Sorella, Alberto Parola

We give upper and lower bounds for the ground-state energy of the infinite-U Hubbard model. In two dimensions, using these bounds we are able to rule out the possibility of phase separation between the undoped-insulating state and an hole-rich state.

Karlo Penc, Robert Lacaze

The low energy spectrum of the ferromagnetic Kondo lattice model on a N-site complete graph extended with on-site repulsion is obtained from the underlying spl(2,1) algebra properties in the strong coupling limit. The ferromagnetic ground state is realized for 1 and N+1 electrons only. We identify the large density of states to be responsible for the suppres

Karlo Penc, Walter Stephan

The single-particle spectral function and the density response of a two band Emery model for CuO chains is calculated for large on-site Cu repulsion U and large on-site energy difference Δ. For U>>U-Δ>>t the eigenfunctions are products of charge and spin parts, which allows analytical calculation of spectral functions in that limit. For other parameters nume

O. V. Derzhko, V. M. Myhal

The density functional approach is used to study the gas-to-liquid and liquid-to-gas nucleation phenomena in a fluid of two-level atoms in an external electrical field. The influence of the field on the surface tension and nucleation and cavitation barriers is discussed.

Martin H. Muser, Philipp Schoffel

We comment on the stability analysis of alpha-quartz under pressure by Gregoryanz et al., Phys. Rev. Lett. 84, 3117 (2000). The proper stability criterion for solids under pressure has to be formulated in terms of Birch coefficients rather than in terms of elastic constants. We show that the fictitious (extrapolated) stable phase of alpha-quartz above a pres

You-Quan Li

In the talk, I briefly demonstrate the quantum theory for mesoscopic electric circuits and its applications. In the theory, the importance of the charge discreteness in a mesoscopic electric circuit is addressed. As a result, a new kind of commutation relation for electric charge and current occurred inevitably. The charge representation, canonical current r

O. Ujsaghy, J. Kroha, L. Szunyogh, A. Zawadowski

The conduction electron density of states nearby a single magnetic impurity, as measured recently by scanning tunneling microscopy (STM), is calculated. It is shown that the Kondo effect induces a narrow Fano resonance as an intrinsic feature in the conduction electron density of states. The line shape varies with the distance between STM tip and impurity, i