July 2000 arXiv papers — page 9

Konstantinos Georgatos

We introduce a simple generalization of Gardenfors and Makinson's epistemic entrenchment called partial entrenchment. We show that preferential inference can be generated as the sceptical counterpart of an inference mechanism defined directly on partial entrenchment.

Konstantinos Georgatos

This paper presents a bimodal logic for reasoning about knowledge during knowledge acquisition. One of the modalities represents (effort during) non-deterministic time and the other represents knowledge. The semantics of this logic are tree-like spaces which are a generalization of semantics used for modeling branching time and historical necessity. A finite

Per Arne Rikvold, M. Kolesik

We present analytic approximations for the field, temperature, and orientation dependences of the interface velocity in a two-dimensional kinetic Ising model in a nonzero field. The model, which has nonconserved order parameter, is useful for ferromagnets, ferroelectrics, and other systems undergoing order-disorder phase transformations driven by a bulk free

Francisco Vera

We studied, theoretically, the optical absorption spectra for a slightly asymmetric double quantum well (DQW), in the presence of electric and magnetic fields. Recent experimental results for a 10.18/3.82/9.61 nm GaAs Al(_{.33} )Ga(_{.67})As DQW show clearly the different behavior in the luminescence peaks for the indirect exciton (IX) and left direct excito

B. I. Belevtsev, I. V. Volchok, N. V. Dalakova, V. I. Dotsenko

A bulk polycrystalline sample of YBa_{2}Cu_{3}O_{7-δ} (δ\approx 0.1) has been irradiated by γ-rays with ^{60}Co source. Non-monotonic behavior of T_c (defined as the temperature at which normal resistance is halved) with increasing irradiation dose Φ(up to about 220 MR) is observed: T_c decreases at low doses (Φ\leq 50 MR) from initial value (\approx 93 K) b

Viktor K. Horváth, J. Rob Cressman, Walter I. Goldburg, Xiao-Lun Wu

There are different ways for fluid flow to become turbulent, but usually many instabilities take place before that. Among these instabilities the transition from laminar flow to vortex shedding carries significant practical importance. Here we study a flow, where at high enough flow rates, vortices are generated by a fixed obstacle (cylinder), which penetrat

A. Bovier, M. Eckhoff, V. Gayrard, M. Klein

In this letter we announce rigorous results that elucidate the relation between metastable states and low-lying eigenvalues in Markov chains in a much more general setting and with considerable greater precision as was so far available. This includes a sharp uncertainty principle relating all low-lying eigenvalues to mean times of metastable transitions, a r

Stefan J. Turneaure, Thomas R. Lemberger, John M. Graybeal

The sheet impedances, Z(w,T), of several superconducting a-Mo77Ge23 films and one In/InOx film have been measured in zero field using a two-coil mutual inductance technique at frequencies from 100 Hz to 100 kHz. Z(w,T) is found to have three contributions: the inductive superfluid, renormalized by nonvortex phase fluctuations; conventional vortex-antivortex

F. Mancini

A well-established method to deal with highly correlated systems is based on the expansion of the Green's function in terms of spectral moments. In the context of the Composite Operator Method one approximation is proposed: a set of n composite fields is assumed as fundamental basis and the dynamics is considered up to the order s. The resulting Green&#3

T. Temesvari, I. Kondor, C. De Dominicis

The reparametrization transformation between ultrametrically organised states of replicated disordered systems is explicitly defined. The invariance of the longitudinal free energy under this transformation, i.e. reparametrization invariance, is shown to be a direct consequence of the higher level symmetry of replica equivalence. The double limit of infinite

J. Gonzalez, F. Guinea, M. A. H. Vozmediano

The effects of the electron-electron interactions in a graphene layer are investigated. It is shown that short range couplings are irrelevant, and scale towards zero at low energies, due to the vanishing of density of states at the Fermi level. Topological disorder enhances the density of states, and can lead to instabilities. In the presence of sufficiently

P. Donohue, M. Tsuchiizu, T. Giamarchi, Y. Suzumura

We study a half filled ladder of spinless fermions. We show that contrarily to a single chain, the ladder becomes a Mott insulator for arbitrarily small repulsive interactions. We obtain the full phase diagram and physical quantities such as the charge gap. We show that there is only a single insulating phase for repulsive interactions, regardless of the ste

R. M. L. Evans

The conditions of multi-phase equilibrium are solved for generic polydisperse systems. The case of multiple polydispersity is treated, where several properties (e.g. size, charge, shape) simultaneously vary from one particle to another. By developing a perturbative expansion in the width of the distribution of constituent species, it is possible to calculate

D. V. Efremov, M. S. Mar'enko, M. A. Baranov, M. Yu. Kagan

High order perturbation theory corrections to the superfluid transition temperature in a weakly interacting Fermi gas with repulsive interaction are calculated. This involves calculating the contributions of third and fourth order diagrams in the gas parameter and taking into account effects of retardation. The contributions from both second, third and fourt

H. B. Weber, R. Häussler, H. v. Löhneysen, J. Kroha

We present data of transport measurements through a metallic nanobridge exhibiting diffusive electron transport. A logarithmic temperature dependence and a zero-bias anomaly in the differential conductance are observed, independent of magnetic field. The data can be described by a single scaling law. The theory of electron-electron interaction in disordered

F. Bernd Mueller-Allinger, Ana Celia Mota

We discuss the magnetic response of gold-niobium proximity cylinders in the temperature range 100 μK<T<9 K. The temperature dependence of the susceptibility in the diamagnetic regime is described well by the quasiclassical Eilenberger theory including an elastic mean-free path l. In the mesoscopic regime, the temperature dependence of the reentrant paramagne

Denis Ullmo, Tatsuro Nagano, Steven Tomsovic, Harold U. Baranger

We develop a semiclassical density functional theory in the context of quantum dots. Coulomb blockade conductance oscillations have been measured in several experiments using nanostructured quantum dots. The statistical properties of these oscillations remain puzzling, however, particularly the statistics of spacings between conductance peaks. To explore the

Luigi Foschini

The current philosophy of impact hazard considers the danger from small asteroids negligible. However, several facts claim for a revision of this philosophy. In this paper, some of these facts are reviewed and discussed. It is worth noting that while the impact frequency of Tunguska-like objects seems to be higher than previously estimated, the atmospheric f

R. I Klein, R. T. Fisher, C. F. McKee

We examine the conditions under which binary and multiple stars may form out of turbulent molecular cloud cores using high resolution 3-D, adaptive mesh refinement (AMR) hydrodynamics (Truelove et al., 1997, 1998; Klein, 1999). We argue that previous conclusions on the conditions for cloud fragmentation have limited applicability, since they did not allow fo

G. Schneider, Nicmos Idt/Eons Teams

The connection between the formation and growth of planetesimals into larger bodies and the circumstellar debris disks around young and nascent stars from which they arise has been the subject of continual speculation, discussion and inquiry, since the original scenario for such evolution was first expanded upon by Laplace (1796) following the general propos

G. Schneider, E. E. Becklin, P. J. Lowrance, B. A. Smith

A coronagraphic imaging survey of 65 nearby stars was conducted using the Near Infrared Camera and Multi-Object Spectrometer (NICMOS) on the Hubble Space Telescope by the Instrument Definition Team. Using these guaranteed time observations we searched for very low mass stellar and substellar (extra-solar giant planet and brown dwarf) companions to young main

Kenneth J. Mighell

I investigate the use of Pearson&#39;s chi-square statistic, the Maximum Likelihood Ratio statistic for Poisson distributions, and the chi-square-gamma statistic (Mighell 1999, ApJ, 518, 380) for the determination of the goodness-of-fit between theoretical models and low-count Poisson-distributed data. I demonstrate that these statistics should not be used t

K. A. Weaver

Preliminary results from an X-ray spectral study of Seyfert 1 galaxies with ASCA and RXTE are presented. From an analysis of X-ray reprocessing features of Compton reflection and Fe K-alpha fluorescence, it is found that iron line strength is not necessarily a good predictor of the amount of reflection. The variability properties of Fe K-alpha and reflection

J. H. Fan

The relation between the $γ$-ray and the emission line luminosities for a sample of 36 $γ$-ray loud blazars is investigated; an apparent correlation between them, $L_γ \propto L_{Line}^{0.69\pm0.11}$, with a correlation coefficient $r=0.741$ and a chance probability of $p = 1.9\times10^{-6}$, is found. It is found, however, that there is no intrinsic correla

J. F. Olive, D. Barret

Using RXTE/PCA data, we have studied the time lag (TL) properties of a sample of four accreting neutron stars (NSs), namely 1E1724-3045, GS1826-238, 4U1705-44 and 4U1728-34. The aim of the study is to identify the spectral and timing state(s) in which TLs are detected. Along this work, we have discovered TLs between the 7-40 keV hard and 2-7 keV soft photons

N. M. Forster Schreiber

I present an atlas of near-infrared K-band spectra of 31 late-type giants and supergiants, and two carbon stars. The spectra were obtained at resolving powers of 830 and 2000, and have a signal-to-noise ratio of 100 or higher. These data are complemented with results from similar existing libraries in both K- and H-band, and are used to identify various tool

G. Gavazzi, A. Boselli, J. M. Vilchez, J. Iglesias-Paramo

We report on the filament of ionized gas found at the NE periphery of M87, the second brightest elliptical galaxy in the Virgo cluster. The object lies at 3.16 arcmin (15.7 kpc) projected distance of the nucleus of M87, and it coincides in position with the Eastern radio lobe of M87. Long slit spectroscopy confirmed the gaseus nature of this object, showing

Ralf Siebenmorgen

The mid infrared spectra of the starbursts show the 9.7$μm$ silicate absorption feature and strong mid infrared emission bands centered at 6.2, 7.7, and 11.3 $μ$m. Illustrative models of the {\it active} galaxies are presented: As the starbursts are most likely confined to the central region of the galaxy the radiative transfer in the nucleus is solved under

V. M. Lyuty, G. V. Zaitseva

UBV observations of the X-ray binary system A0535+26/V725 Tau at the Crimean Station of the Sternberg Astronomical Institute in 1980-1998 are presented. Based on our and published data, we analyze the photometric history of the star from 1898.

A. O. Jaunsen, J. Hjorth, G. Bjornsson, M. I. Andersen

We present extensive multi-colour (UBVR_CI_C) photometry of the optical afterglow of GRB 980519. Upon discovery, 8.3 hours after the burst, the source was decaying as a power law, (t-t_GRB)^alpha, with a rapid decay rate alpha_1 = - 1.73+-0.04. About 13 hours after the burst a steepening of the light-curve to alpha_2 = -2.22+-0.04 was observed. Within the fr

B. Larsson, R. Liseau, A. B. Men&#39;shchikov, G. Olofsson

ISO-LWS mapping observations of the Serpens molecular cloud core are presented. The spectral range is 50 - 200 micron and the map size is 8&#39; X 8&#39;. These observations suffer from severe source confusion at FIR wavelengths and we employ a Maximum Likelihood Method for the spectro-spatial deconvolution. The strong and fairly isolated source SMM1 FIRS1 p

F. Combes

Knowledge of the molecular component of the ISM is fundamental to understand star formation. The H2 component appears to dominate the gas mass in the inner parts of galaxies, while the HI component dominates in the outer parts. Observation of the CO and other lines in normal and starburst galaxies have questioned the CO-to-H2 conversion factor, and detection

R. Wielen, H. Jahreiss, C. Dettbarn, H. Lenhardt

We derive the astrometric orbit of the photo-center of the close pair alpha UMi AP (=alpha UMi Aa) of the Polaris multiple stellar system. The orbit is based on the spectroscopic orbit of the Cepheid alpha UMi A (orbital period of AP: 29.59 years), and on the difference Delta mu between the quasi-instantaneously measured HIPPARCOS proper motion of Polaris an

T. Affolder

We present a measurement of the W boson mass using data collected with the CDF detector during the 1994-95 collider run at the Fermilab Tevatron. A fit to the transverse mass spectrum of a sample of 30,115 W -> enu events recorded in an integrated luminosity of 84 pb^(-1) gives a mass Mw = 80.473 +- 0.065(stat.) +- 0.092(syst.) GeV/c^2. A fit to the transver

D. J. Helfand, E. V. Gotthelf, J. P. Halpern

(Abridged) We present high-resolution Chandra X-ray observations of PSR B0833-45, the 89 ms pulsar associated with the Vela supernova remnant. We have acquired two observations separated by one month to search for changes in the pulsar and its environment following an extreme glitch in its rotation frequency. We find a well-resolved nebula with a toroidal mo

Ori J. Ganor, Joanna L. Karczmarek

We study the Quantum-Mechanics on the hyper-Kahler manifold that is the blow-up of an $A_1$-singularity. This system is relevant for M(atrix)-theory as it was conjectured to describe scattering in the &#34;noncommutative&#34; deformation of a free 5+1D tensor multiplet in the sector with two units of longitudinal light-like momentum.

J. F. Gomes, E. P. Gueuvoghlanian, G. M. Sotkov, A. H. Zimerman

Two new families of T-Dual integrable models of dyonic type are constructed. They represent specific $A_n^{(1)}$ singular Non-Abelian Affine Toda models having U(1) global symmetry. Their 1-soliton spectrum contains both neutral and U(1) charged topological solitons sharing the main properties of 4-dimensional Yang-Mills-Higgs monopoles and dyons. The semicl

A. Di Giacomo, H. G. Dosch, V. I. Shevchenko, Yu. A. Simonov

This review is aimed to demonstrate the basics and use of formalism of gauge-invariant nonlocal correlators in nonabelian gauge theories. Many phenomenologically interesting nonperturbative aspects of gluodynamics and QCD can be described in terms of correlators of the nonabelian field strength tensors. It is explained how the properties of correlator ensemb

M. Daoud, J. Douari

The generalization of the Jaynes-Cummings (GJC) Model is proposed. In this model, the electromagnetic radiation is described by a Hamiltonian generalizing the harmonic oscillator to take into account some nonlinear effects which can occurs in the experimental situations. The dynamical superalgebra and supercoherent states of the related model are explicitly

Yurii V. Brezhnev

We consider the solution of spectral problems with elliptic coefficients in the framework of the Hermite ansatz. We show that the search for exactly solvable potentials and their spectral characteristics is reduced to a system of polynomial equations solvable by the Gröbner bases method and others. New integrable potentials and corresponding solutions of the

Luc Blanchet, Guillaume Faye

The general relativistic corrections in the equations of motion and associated energy of a binary system of point-like masses are derived at the third post-Newtonian (3PN) order. The derivation is based on a post-Newtonian expansion of the metric in harmonic coordinates at the 3PN approximation. The metric is parametrized by appropriate non-linear potentials

J. Douari, Y. Hassouni

The construction of anyonic operators and algebra is generalized by using quons operators. Therefore, the particular versionof fractional supersymmetry is constructed on the two-dimensional lattice by associating two generalized anyons of different kinds. The fractional supersymmetry Hamiltonian operator is obtained on the two-dimensional lattice and the qua

M. C. Gonzalez-Garcia, C. Peña-Garay, Y. Nir, A. Yu. Smirnov

We study the phenomenological consequences of maximal and near-maximal mixing of the electron neutrino with other ($x$=tau and/or muon) neutrinos. We describe the deviations from maximal mixing in terms of a parameter $\epsilon\equiv1-2\sin^2\theta_{ex}$ and quantify the present experimental status for $|\epsilon|<0.3$. We find that the global analysis of so

International Gravitational Event Collaboration

We report the initial results from a search for bursts of gravitational radiation by a network of five cryogenic resonant detectors during 1997 and 1998. This is the first significant search with more than two detectors observing simultaneously. No gravitational wave burst was detected. The false alarm rate was lower than 1 per 10^4 years when three or more

F. Gastineau, J. Aichelin

Employing NEXUS, one of the most recent simulation programs for heavy ions collisions, we investigate in detail the Hanbury-Twiss correlation function for charged pions for reactions 158 GeV Pb+Pb. For this study we supplement the standard simulation program by electromagnetic interactions. We find that the string fragmentation introduces strong space-moment

Jonivar Skullerud, Anthony G. Williams

The Landau gauge quark propagator in momentum space is investigated using the O(a)-improved Sheikholeslami--Wohlert (SW) quark action with a tree-level mean-field improved coefficient c_sw. We have studied the unimproved definition of the quark propagator, as well as two different tree-level O(a)-improved propagators. The ultraviolet behavior of the free lat

M. Beccaria, F. M. Renard, C. Verzegnassi

We compute the MSSM one-loop contributions to the asymptotic energy behaviour of fermion-antifermion pair production at future lepton-antilepton colliders. Besides the conventional logarithms of Renormalization Group origin, extra SUSY linear logarithmic terms appear of &#34;Sudakov-type&#34;. In the TeV range their overall effect on a variety of observables

Eric J. Lentz, E. Baron, David Branch, P. H. Hauschildt

SN 1984A shows unusually large expansion velocities in lines from freshly synthesized material, relative to typical Type Ia Supernovae (SNe Ia). SN 1984A is an example of a group of SNe Ia which have very large blue-shifts of the P-Cygni features, but otherwise normal spectra. We have modeled several early spectra of SN 1984A with the multi-purpose NLTE mode

A. B. Balantekin

A combinatorial formula to generate U(N) character expansions is presented. It is shown that the resulting character expansion formulas greatly simplify a number of problems where integrals over the group manifolds need to be calculated. Several examples are given, including direct and very quick calculations of the Itzykson-Zuber integral and the finite vol

I. V. Yurkevich, Igor V. Lerner

We modify a nonlinear sigma model (NLSM) for the description of a granulated disordered system in the presence of both the Coulomb repulsion and the Cooper pairing. We show that under certain controlled approximations this model is reduced to the Bose-Hubbard (or ``dirty-boson&#39;&#39;) model with renormalized coupling constants. We obtain a more general ef

Vestislav Apostolov, Tedi Draghici, Andrei Moroianu

It is proved that a compact Kahler manifold whose Ricci tensor has two distinct, constant, non-negative eigenvalues is locally the product of two Kahler-Einstein manifolds. A stronger result is established for the case of Kahler surfaces. Irreducible Kahler manifolds with two distinct, constant eigenvalues of the Ricci tensor are shown to exist in various si

William Bialek, Ilya Nemenman, Naftali Tishby

We define {\em predictive information} $I_{\rm pred} (T)$ as the mutual information between the past and the future of a time series. Three qualitatively different behaviors are found in the limit of large observation times $T$: $I_{\rm pred} (T)$ can remain finite, grow logarithmically, or grow as a fractional power law. If the time series allows us to lear

Irit Maor, Ram Brustein, Paul J. Steinhardt

Supernova searches have been been suggested as a method for determining precisely the current value and time variation of the equation of state, $w$, of the dark energy component responsible for the accelerated expansion of the Universe. We show that the method is fundamentally limited by the fact that luminosity dista nce depends on $w$ through a multiple i

A. Acin, J. I. Latorre, P. Pascual

The decay of ortho-positronium into three photons produces a physical realization of a pure state with three-party entanglement. Its quantum correlations are analyzed using recent results on quantum information theory, looking for the final state which has the maximal amount of GHZ-like correlations. This state allows for a statistical dismissal of local rea

A. D. Baute, I. L. Egusquiza, J. G. Muga

The transmitted wave that results from a collision of a wave packet which is initially to the left of a potential barrier depends in general on the amplitudes of negative momenta of the initial state. The exact form of this dependence is shown and the importance of this classically forbidden effect is illustrated with numerical examples. Special care is take

Sergio De Filippo

The localization length for the center of mass motion of a matter lump, induced by gravitation, is obtained, without using any phenomenological constants. Its dependence from mass and volume is consistent both with unitary evolution of microscopic particles and with the classical behavior of macroscopic bodies required to account for wave function collapse i

G L Long, H Y Yan, Y s Li, C C Tu

The quantum nature of bulk ensemble NMR quantum computing --the center of recent heated debate, is addressed. Concepts of the mixed state and entanglement are examined, and the data in a 2 qubit liquid NMR quantum computation are analyzed. It is pointed out that the key problem in the current debate is the understanding of entanglement in a mixed state syste

Michol Massini, Mauro Fortunato, Stefano Mancini, Paolo Tombesi

We present a tomographic method for the reconstruction of the full entangled quantum state for the cyclotron and spin degrees of freedom of an electron in a Penning trap. Numerical simulations of the reconstruction of several significant quantum states show that the method turns out to be quite accurate.

M. S. Shahriar, P. R. Hemmer, S. Lloyd, J. A. Bowers

A quantum computer that stores information on two-state systems called quantum bits or qubits must be able to address and manipulate individual qubits, to effect coherent interactions between pairs of qubits, and to read out the value of qubits.1,2 Current methods for addressing qubits are divided up into spatial methods, as when a laser beam is focused on a

Fritz DeJongh

We show that Compton scattering can be used to cool TeV-scale muon beams, and we derive analytical expressions for the equilibrium transverse angular spread, longitudinal energy spread, and power requirements. We find that a factor of a few thousand reduction in emittance is possible for a 3 TeV muon collider.

A. G. Khachatryan

Longitudinal and transverse behavior of magnetic field of relativistic nonlinear three-dimensional plasma wave is investigated. It is shown that the magnetic field of the wave is different from zero and performs higher frequency oscillations compared to the plasma electron frequency. An increase in the nonlinearity leads to strengthening of magnetic field. T

Evgenii Narimanov, Partha Mitra

We consider the communication channel given by a fiber optical transmission line. We develop a method to perturbatively calculate the information capacity of a nonlinear channel, given the corresponding evolution equation. Using this technique, we compute the decrease of the channel capacity to the leading order in the perturbative parameter for fiber optics

Isabela P. Cavalcante, Manoel R. Robilotta

We consider the interaction of two skyrmions in the framework of the sudden approximation. The widely used product ansatz is investigated. Its failure in reproducing an attractive central potential is associated with terms that violate G-parity. We discuss the construction of alternative ansätze and identify a plausible solution to the problem.

F. Hofmann, C. M. Keil, H. Lenske

The density dependent relativistic hadron field (DDRH) theory is applied to strongly asymmetric nuclear matter and finite nuclei far off stability. A new set of in-medium meson-nucleon vertices is derived from Dirac-Brueckner Hartree-Fock (DBHF) calculations in asymmetric matter, now accounting also for the density dependence of isovector coupling constants.

G. Widman, T. Schreiber, B. Rehberg, A. Hoeft

We investigate several quantifiers of the electroencephalogram (EEG) signal with respect to their ability to indicate depth of anesthesia. For 17 patients anesthetized with Sevoflurane, three established measures (two spectral and one based on the bispectrum), as well as a phase space based nonlinear correlation index were computed from consecutive EEG epoch

D. Neshev, A. Dreischuh, G. G. Paulus, H. Walther

Numerical simulations on the evolution of step-screw and edge-screw optical phase dislocations in bulk saturable self-defocusing nonlinear media are presented, with emphasis on their ability to induce steering waveguides for signal beams (pulses). Two schemes for directional coupling of such signals, both ensuring reasonable coupling-to-cross-talk efficiency

Jochen Koenigsmann

By two well-known results, one of Ax, one of Lubotzky and van den Dries, a profinite group is projective iff it is isomorphic to the absolute Galois group of a pseudo-algebraically closed field. This paper gives an analogous characterization of relatively projective profinite groups as absolute Galois groups of regularly closed fields.

Lucy Lifschitz, Dave Witte

Let F be a local field of positive characteristic, and let G be either a Heisenberg group over F, or a certain (nonabelian) two-dimensional unipotent group over F. If H is an arithmetic subgroup of G, we provide an explicit description of every automorphism of H. From this description, it follows that every automorphism of H virtually extends to a virtual au

Patrick M. Gilmer, Jianyuan Zhong

Let $k$ be a subring of the field of rational functions in $x, v, s$ which contains $x^{\pm 1}, v^{\pm 1}, s^{\pm 1}$. If $M$ is an oriented 3-manifold, let $S(M)$ denote the Homflypt skein module of $M$ over $k$. This is the free $k$-module generated by isotopy classes of framed oriented links in $M$ quotiented by the Homflypt skein relations: (1) $x^{-1}L_

Lorenzo D&#39;Ambrosio

The purpose of this paper is to study the approximation of vector valued mappings defined on a subset of a normed space. We investigate Korovkin-type conditions under which a given sequence of linear operators becomes a so-called approximation process. First, we give a sufficient condition for this sequence to approximate the class of bounded, uniformly cont

Vyjayanthi Chari, Andrew Pressley

We study the universal integrable modules W_q(m) of level zero for quantum affine sl_2 and a family of maximal finite--dimensional quotients of these modules. We show that these all have dimension 2^m. Using this, we are able to realize W_q(m) as the space of invariants of a reprsentation of the Hecke algebra H_m. We also give a conjecture in the general cas

J. X. Lu, S. Roy, H. Singh

We investigate how the four-dimensional noncommutative open string/Yang-Mills theory behaves under a general non-perturbative quantum $SL(2,Z)$ symmetry transformation. We discuss this by considering D3 branes in a constant background of axion, dilaton, and electric and magnetic fields (including both $ {\bf E} \perp {\bf B}$ and {\bf E}$||${\bf B} cases) in

P. Bantay

It is shown that traces of mapping classes of finite order may be expressed by Verlinde-like formulae. The 3D topological argument is explained, and the resulting trace identities for modular matrix elements are presented.

A. Akhmetshin, Y. Volvovsky

Following the recent paper by J. F. van Diejen and H. Puschmann we investigate the behavior of zeros of the finite-gap solutions to the Schrodinger equation. As a result, a new system of particles on a punctured Riemann surface is constructed. It is shown to be Hamiltonian and integrable.

M. Daoud, J. Douari, Y. Hassouni

We show that the Yang-Baxter equation is equivalent to the associativity of the algebra generated by non-commuting link operators. Starting from these link operators we build out the (FFZ) algebras, the $s\ell_q (2)$ is derived by considering a special combination of the generators of (FFZ) algebra.

Valerio Bozza, Gabriele Veneziano

Generalizing previous work, we study the collision of massless superstring plane waves in D space-time dimensions within an explicitly O(D-2,D-2)-invariant set of field equations. We discuss some general properties of the solutions, showing in particular that they always lead to the formation of a singularity in the future. Using the above symmetry, we obtai

Jaydeep Majumder, Ashoke Sen

A system containing a pair of non-BPS D-strings of type IIA string theory on an orbifold, representing a single D2-brane wrapped on a nonsupersymmetric 2-cycle of a Calabi-Yau 3-fold with $(h^{(1,1)},h^{(1,2)})$ = (11,11), is analyzed. In certain region of the moduli space the configuration is stable. We show that beyond the region of stability the system ca

J. R. Hiller

A method for the nonperturbative calculation of scattering amplitudes and cross sections is discussed in the context of light-cone quantization. The Lanczos-based recursion method of Haydock is suggested for the computation of matrix elements of the resolvent for the light-cone Hamiltonian, from which the T-matrix can be constructed. The scattering of compos

Amitava Datta, Shyamapada Maity, Anindya Datta

In scenarios with relatively light down squarks, motivated, e.g., by SO(10) D terms, jets + missing $E_T$ signals can be observed at the luminosity upgraded Tevatron even if the squarks are much heavier than the gluinos and the common gaugino mass ($M_{1/2}$) at $M_G$ lies above the LEP allowed lower bound. In the conventional mSUGRA model with heavy squarks

Fritz W. Bopp

We begin to briefly survey the experimental and conceptual side of baryon transfers in particle scattering. A discussion of baryon transfers in heavy ion scattering follows. It shortly reviews existing string model concepts, which were found to be consistent with the data. With this motivation we turn to a more careful consideration of the relevant topologic

Herbi Dreiner, Peter Richardson, Mike Seymour

We consider the resonant production of sleptons via R-parity violation in hadron-hadron collisions followed by supersymmetric gauge decays of the sleptons. We look at decay modes which lead to the production of a like-sign dilepton pair. The dominant production mechanism giving this signature is the resonant production of a charged slepton followed by a deca

I. Antoniadis, K. Benakli

We review the status of low-scale string theories and large extra-dimensions. After an overview on different string realizations, we discuss some of the main important problems and we summarize present bounds on the size of possible extra-dimensions from collider experiments.

G. Moortgat-Pick, A. Bartl, H. Fraas, W. Majerotto

We study the production processes e^+ e^- -> chi^+_i chi^-_j, i,j=1,2, and e^+ e^- -> chi^0_m chi^0_n, m,n=1,...,4, working out the advantages of polarizing both beams. For e^+ e^- -> chi^+_1 chi^-_1 with chi^-_1 -> chi^0_1 e^- nu and e^+ e^- -> chi^0_1 chi^0_2 with chi^0_2 -> chi^0_1 e^+ e^- we perform a detailed analysis, including the complete spin correl

D. Fliegner, A. Retey, J. A. M. Vermaseren

The present paper is the first of a series of papers reporting on the parallelization of the symbolic manipulation program FORM on different parallel architectures. Part I deals with workstation clusters using dedicated network hardware and the messages passing libraries (MPI and PVM). After a short introduction to the sequential version of FORM a detailed a

M. Chaichian, K. Huitu, Z. -H. Yu

We study the production of $(t+\bar{t}) \tilde{g}$ at the hadron colliders in an R-parity ($R_{p}$) violating supersymmetric model. This process provides us with information not only about $R_{p}$ violation, but may also help us in detecting the supersymmetry itself. It is possible to detect an $R_{p}$ violating signal (with single gluino production) at the

J. P. Zibin, R. Brandenberger, Douglas Scott

We study the class of two-field inflationary Universe models λϕ^4/4 + g^2χ^2ϕ^2/2, in which parametric resonance during the initial stages of reheating can lead to an exponential amplification of the amplitude of cosmological fluctuations. Employing both analytical arguments and numerical simulations, we determine the time at which backreaction of fluctuatio

Gerry Bunce, Naohito Saito, Jacques Soffer, Werner Vogelsang

Colliding beams of 70% polarized protons at up to $\sqrt{s}$=500 GeV, with high luminosity, L=2$\times10^{\rm 32}$ cm$^{-2}$sec$^{-1}$, will represent a new and unique laboratory for studying the proton. RHIC-Spin will be the first polarized-proton collider and will be capable of copious production of jets, directly produced photons, and $W$ and $Z$ bosons.

Andrzej Czarnecki, Kirill Melnikov, Alexander Yelkhovsky

We study binding corrections to the gyromagnetic factor g_e of an electron in hydrogen-like ions. We argue that the leading order binding effects in radiative corrections Delta g_rad are universal to all orders in alpha/pi and the complete result reads Delta g_rad = (g_free - 2) [1+(Z alpha)^2/6] + O[alpha/pi (Zalpha)^4]. The theoretical uncertainty in the p

Philip R. Page

Symmetrization selection rules for the decay of four-quark states to two J=0 mesons are analysed in a non - field theoretic context with isospin symmetry. The OZI allowed decay of an isoscalar J^PC = (1,3,...)^{-+} exotic state to eta&#39; eta or f_0&#39; f_0 is only allowed for four-quark components of the state containing one s sbar pair, providing a filte

James V. Steele

Merons, conjectured as a semiclassical mechanism for color confinement in QCD, are topological charge-1/2, singular solutions to the classical Yang-Mills equations of motion. I will discuss how lattice techniques can extend the study of merons to nonsingular stationary solutions without destroying properties believed to be essential for confinement, and how

Thomas Lippert

The Wilson fermion determinant can be written as product of the determinants of two hermitian positive definite matrices. This formulation allows to simulate non-degenerate quark flavors by means of the hybrid Monte Carlo algorithm. A major numerical difficulty is the occurrence of nested inversions. We construct a Uzawa iteration scheme which treats the nes

John W. Negele

Lattice field theory provides a quantitative tool to study the role of nonperturbative semiclassical configurations in QCD. This talk briefly reviews our present understanding of the role of instantons in QCD and describes in detail new developments in the study of merons on the lattice.

John W. Negele

The use of lattice QCD to understand hadron structure is described, with particular emphasis on exploring the role of glue.

T. Bergfeld, CLEO Collaboration

We search for the decays of the $B^0$ meson into $e^+e^-$, $μ^+μ^-$ $e^{\pm}μ^{\mp}$ pairs in a sample of $9.7\times 10^6$ $B{\bar B}$ pairs recorded by CLEO detector. No signal is found, and the following upper limits on the corresponding branching fractions are established: $<8.3\times 10^{-7}$, $<6.1\times 10^{-7}$, $< 15\times 10^{-7}$ at 90% confidence

R. Ammar, CLEO Collaboration

Using data recorded with the CLEO II and CLEO II.V detector configurations at the Cornell Electron Storage Rings, we report the first observation and mass measurement of the $Σ_c^{*+}$ charmed baryon, and an updated measurement of the mass of the $Σ_c^+$ baryon. We find $M(Σ_c^{*+})-M(Λ_c^+)$= 231.0 +- 1.1 +- 2.0 MeV, and $M(Σ_c^{+})-M(Λ_c^+)$= 166.4 +- 0.2

The OPAL collaboration, G. Abbiendi

Searches for the neutral Higgs bosons h0 and A0, are used to obtain limits on the Type II Two Higgs Doublet Model (2HDM(II)) with no CP-violation in the Higgs sector and no additional particles besides the five Higgs bosons. The analysis combines approximately 170 pb-1 of data collected with the OPAL detector at sqrt{s} ~ 189 GeV with previous runs at sqrt{s

Martin Pohl

I summarise the physics opportunities and experimental challenges at future Linear Colliders, using material from the recent ECFA/DESY workshop on the subject as well as contributions to the series of worldwide studies. For reasons of economy, the discussion is restricted to the European Tesla project and to its electron-positron mode only.

J P Scott

Using 3.9 $pb^{-1}$ of data from ep $\ra$ eX interactions recorded using the ZEUS detector in 1997,the proton structure function, F$_2$, has been measured in the range 0.015 GeV$^2$ $<$ Q$^2 <$ 0.65 GeV$^2$ and $6 \times 10^{-7} < x < 1 \times 10^{-3}$. The analysis is based on data taken incorporating new detector components. Compared with the previous anal

A. Safonov, for CDF Collaboration

Recent CDF results on inclusive momentum distributions and multiplicities of particles in restricted cones around jets are compared to predictions using the Modified Leading Log Approximation. We found that MLLA gives a very reasonable description of jet fragmentation for a wide range of energies. Model parameters are extracted separately from the multiplici

Moncy V. John

In this thesis, the implications of a new cosmological model are studied, which has features similar to that of decaying vacuum cosmologies. Decaying vacuum (or cosmological constant Λ) models are the results of attempts to resolve the problems that plague the standard hot big bang model - the problems which elude a satisfactory solution even after the two d