August 1997 arXiv papers — page 7

C. Henrique, M. A. Aguirre, A. Calvo, I. Ippolito

We report an experimental, numerical and theoretical study of the motion of a ball on a rough inclined surface. The control parameters are $D$, the diameter of the ball, $θ$, the inclination angle of the rough surface and $E_{ki}$, the initial kinetic energy. When the angle of inclination is larger than some critical value, $θ>θ_{T}$, the ball moves at a con

Daijiro Yoshioka

A theory of transport in the quantum Hall regime is developed for separately contacted double-layer electron systems. Inter-layer tunneling provides a channel for equilibration of the distribution functions in the two layers at the edge states. Resistances and transresistances for various configurations of the electrodes are calculated as functions of the in

Ronald E. Cohen

The first non-empirical computation of lattice thermal conductivity has been performed for MgO using molecular dynamics (MD), a non-empirical ionic model (the Variationally Induced Breathing (VIB) model), and Green-Kubo theory. The computation is first-principles in the sense that no parameters are fit to experiment. Results are presented at low pressure as

Tohru Koma, Hal Tasaki

We consider a quantum many-body system on a lattice with a continuous symmetry which exhibits a spontaneous symmetry breaking in its infinite volume ground states, but in which the order operator does not commute with the Hamiltonian. A typical example is the Heisenberg antiferromagnet with a Neel order. In the corresponding finite system, the symmetry break

John Carroll, David Weir

We address the issue of how to associate frequency information with lexicalized grammar formalisms, using Lexicalized Tree Adjoining Grammar as a representative framework. We consider systematically a number of alternative probabilistic frameworks, evaluating their adequacy from both a theoretical and empirical perspective using data from existing large tree

Lillian Lee

This thesis presents two similarity-based approaches to sparse data problems. The first approach is to build soft, hierarchical clusters: soft, because each event belongs to each cluster with some probability; hierarchical, because cluster centroids are iteratively split to model finer distinctions. Our second approach is a nearest-neighbor approach: instead

M. Gerin, T. G. Phillips, D. J. Benford, K. H. Young

We have detected the J=4-3 rotational transition of 12CO in absorption at z=0.89 towards the quasar PKS1830-211, but not the 12CO 5-4 or the 3P1-3P0 fine structure line of neutral carbon. The intervening molecular medium thus has a total 12CO column density of N(CO)~2x10^18 cm^-2, which corresponds to the large column density of molecular hydrogen of N(H2)=2

A. V. Sweigart, M. Catelan

Recent HST observations of the metal-rich bulge clusters NGC 6388 and NGC 6441 by Rich et al. (1997) have found that the horizontal branches (HBs) in these clusters slope upward with decreasing B-V. Such an upward slope in the HB morphology is not predicted by canonical HB models. Moreover, it cannot be produced by either a greater cluster age or enhanced ma

M. Gambera, A. Pagliaro, -

By means of numerical methods, we solve the equations of motion for the collapse of a shell of baryonic matter, made of galaxies and substructure falling into the central regions of a cluster of galaxies, taking into account the effect of the dynamical friction. The parameters on which the dynamical friction mainly depends are: the peaks' height, the num

David M. Goldberg

We discuss the prospect of deblending microlensing events by observing astrometric shifts of the lensed stars. Since microlensing searches are generally performed in very crowded fields, it is expected that stars will be confusion limited rather than limited by photon statistics. By performing simulations of events in crowded fields, we find that if we assum

G. G. Pooley, R. P. Fender

We present data on the monitoring of the Galactic X-ray transient GRS 1915+105 at 15 GHz with the Ryle Telescope. We have found quasi-periodic oscillations with periods in the range 20-40 min which are tentatively associated with the soft-X-ray variations on the same time-scale. The overall behaviour of the radio emission is shown to vary in a strong associa

Robert Schmidt, Rachel L. Webster, Geraint F. Lewis

In the gravitational lens system Q2237+0305 the cruciform quasar image geometry is twisted by ten degrees by the lens effect of a bar in the lensing galaxy. This effect can be used to measure the mass of the bar. We construct a new lensing model for this system with a power-law elliptical bulge and a Ferrers bar. The observed ellipticity of the optical isoph

W. Becker, J. Trümper

As a result of recent observations with ROSAT and ASCA the number of rotation-powered pulsars seen at X-ray energies has increased substantially. In this paper we review the phenomenology of the observed X-ray emission properties. At present 27 pulsars are detected, representing a wide range of ages (10^3 - 7 x 10^9 yrs), magnetic field strength (10^8 - 10^1

M. Feroci, F. Frontera, E. Costa, D. Dal Fiume

The Italian-Dutch satellite for X-ray Astronomy BeppoSAX is successfully operating on a 600 km equatorial orbit since May 1996. We present here the in-flight performances of the Gamma Ray Burst Monitor experiment during its first year of operation. The GRBM is the secondary function of the four CsI(Na) slabs primarily operating as an active anticoincidence o

Felix Ryde, Juri Poutanen, Roland Svensson, Stefan Larsson

A broad band X-, gamma-ray spectral study of the Seyfert 2 galaxy NGC 7172 is presented. We use our ASCA observations from May 1995 and combine these with the CGRO OSSE data from March 1995. The only Seyfert 2 galaxy previously to have been modelled over such a broad spectral range is NGC 4945. We find that the most probable model for the data is an absorbed

Marcin Sawicki, H. K. C. Yee

Broadband optical and IR spectral energy distributions are determined for spectroscopically confirmed z>2 Lyman break objects in the Hubble Deep Field. These photometric data are compared to spectral synthesis models which take into account the effects of metallicity and of internal reddening due to dust. It is found that, on average, Lyman break objects are

I. M. Avruch, A. S. Cohen, J. Lehar, S. R. Conner

We have produced deep radio maps of the double quasar 0957+561 from multiple-epoch VLA observations. To achieve high sensitivity to extended structure we have re-reduced the best available 1.6 GHz observations and have combined 5 GHz data from multiple array configurations. Regions of faint emission approximately 15 arcsec north and south of the radio source

Bernd Bruegmann

The standard approach to the numerical evolution of black hole data using the ADM formulation with maximal slicing and vanishing shift is extended to non-symmetric black hole data containing black holes with linear momentum and spin by using a time-independent conformal rescaling based on the puncture representation of the black holes. We give an example for

Todor Stanev, Alberto Franceschini

We use the new results of the HEGRA detector on the TeV gamma-ray emission from MKN 501 to set upper limits on the energy density of the cosmic infrared background (CIRB). Contrary to previous interpretations of the gamma-ray spectrum of MKN 421 as showing an intergalactic absorption cutoff at 5 TeV, the observed spectrum of MKN 501 extends beyond 10 TeV and

S. D. Hern, J. M. Stewart

We have examined, repeated and extended earlier numerical calculations of Berger and Moncrief for the evolution of unpolarized Gowdy T3 cosmological models. Our results are consistent with theirs and we support their claim that the models exhibit AVTD behaviour, even though spatial derivatives cannot be neglected. The behaviour of the curvature invariants an

J. Blümlein, S. Kurth

The Mellin-transforms of the next-to-leading order Wilson coefficients of the longitudinal structure function are evaluated.

Rainer W. Kuhne

The possibility of the existence of magnetic charges is one of the greatest unsolved issues of the physics of this century. The concept of magnetic monopoles has at least two attractive features: (i) Electric and magnetic fields can be described equivalently. (ii) In contrast to quantum electrodynamics models of monopoles are able to explain the quantization

J. Cline, M. Joyce, K. Kainulainen

We calculate the baryon asymmetry generated at the electroweak phase transition in the minimal supersymmetric standard model, treating the particles in a WKB approximation in the bubble wall background. A set of diffusion equations for the particle species relevant to baryon generation, including source terms arising from the CP violation associated with the

David A. Kosower

Collider data can play an important role in determining the parton distribution functions of the nucleon. I present a formalism which makes it possible to use next-to-leading order calculations in such a determination, while minimizing the amount of numerical computation required.

V. M. Braun

I explain current theoretical ideas on higher-twist (hadronization) corrections to physical observables in QCD.

T. M. Aliev, G. Hiller, E. O. Iltan

We calculate the leading logarithmic QCD corrections to the decay B_s --> γγin the two Higgs doublet model (2HDM) including O_7 type long distance effects and estimate the restrictions of the 2HDM parameters, tanβand m_H, using the experimental data of B --> X_s γdecay provided by the CLEO collaboration. A lower bound for the charged Higgs mass m_H as a func

Julian Lee

We present the Hamiltonian formulation of the bosonic Dirichlet p-brane action. We rewrite the recently proposed quadratic D-brane action in terms of generalized shift vector and lapse function. The first class and the second class constraints are explicitly separated for the bosonic case. We then impose the gauge conditions in such a way that only time-inde

Gaetano Fiore

Any deformation of a Weyl or Clifford algebra can be realized through a change of generators in the undeformed algebra. q-Deformations of Weyl or Clifford algebrae that were covariant under the action of a simple Lie algebra g are characterized by their being covariant under the action of the quantum group $U_q g$. We present a systematic procedure for deter

E. K. Sklyanin

For the sl_2 Gaudin model (degenerated quantum integrable XXX spin chain) an exponential generating function of correlators is calculated explicitely. The calculation relies on the Gauss decomposition for the SL_2 loop group. From the generating function a new explicit expression for the correlators is derived from which the determinant formulas for the norm

E. S. Kovalenko, N. A. Zabotin

The idea of new diagnostics method for the small-scale irregular structures of magnetically confined plasma is suggested in the present paper. The method can be based on measurements of intensity attenuation of the normal sounding waves. Anomalous attenuation arises due to multiple scattering effects investigated earlier for ionospheric radio propagation. It

P. Navratil, B. R. Barrett, W. E. Ormand

We use a $4\hbarΩ$ shell-model calculation with a two-body effective interaction derived microscopically from the Reid93 potential to calculate the isospin-mixing correction for the 10C->10B superallowed Fermi transition. The effective interaction takes into account the Coulomb potential as well as the charge dependence of T=1 partial waves. Our results sugg

M. C. Cambiaggio, A. M. F. Rivas, M. Saraceno

We show that a many-body Hamiltonian that corresponds to a system of fermions interacting through a pairing force is an integrable problem, i.e. it has as many constants of the motion as degrees of freedom. At the classical level this implies that the Time-dependent Hartree-Fock- Bogoliubov dynamics is integrable and at the quantum level that there are conse

F. Simkovic, J. Schwieger, G. Pantis, Amand Faessler

A large Hilbert space is used for the calculation of the nuclear matrix elements governing the light neutrino mass mediated mode of neutrinoless double beta decay of Ge76, Mo100, Cd116, Te128 and Xe136 within the proton-neutron quasiparticle random phase approximation (pn-QRPA) and the renormalized QRPA with proton-neutron pairing (full-RQRPA) methods. We ha

Franz-Viktor Kuhlmann, Salma Kuhlmann

Based on the work of Hahn, Baer, Ostrowski, Krull, Kaplansky and the Artin-Schreier theory, and stimulated by a paper of S. Lang in 1953, the theory of real places and convex valuations has witnessed a remarkable development and has become a basic tool in the theory of ordered fields and real algebraic geometry. In this paper, we take a further step by addin

V. E. R. Lemes, C. Linhares de Jesus, C. A. G. Sasaki, S. P. Sorella

Classical three dimensional Yang-Mills is seen to be related to the topological Chern-Simons term through a nonlinear but fully local and covariant gauge field redefinition. A classical recursive cohomological argument is provided.

R. Jackiw

Charged matter spin-1 fields enjoy a nonelectromagnetic gauge symmetry when interacting with vacuum electromagnetism, provided their gyromagnetic ratio is 2.

Manoelito M. de Souza

We discuss the physical meaning and the geometric interpretation of causality implementation in classical field theories. Causality is normally implemented through kinematical constraints on fields but we show that in a zero-distance limit they also carry a dynamical information, which calls for a revision of our standard concepts of interacting fields. The

Detlev Buchholz, Rainer Verch

The concept of scaling algebra provides a novel framework for the general structural analysis and classification of the short distance properties of algebras of local observables in relativistic quantum field theory. In the present article this method is applied to the simple example of massive free field theory in s = 1,2 and 3 spatial dimensions. Not quite

I. P. Ennes, A. V. Ramallo, J. M. Sanchez de Santos

We review some results recently obtained for the conformal field theories based on the affine Lie superalgebra osp(1|2). In particular, we study the representation theory of the osp(1|2) current algebras and their character formulas. By means of a free field representation of the conformal blocks, we obtain the structure constants and the fusion rules of the

Joaquim Prades

The value of the light quark masses combination $m_u + m_d$ is analized using QCD-Hadron Duality. A detailed analysis of both the perturbative QCD [to four-loops] and the hadronic parametrization needed is done. The result we get is $[m_u + m_d] (1 GeV^2) = (12.8 \pm 2.5)$ MeV ($[m_u + m_d] (4 GeV^2) = (9.8 \pm 1.9)$ MeV) in the $\barMS$ scheme.

Juan Carlos D'Olivo, Jose F. Nieves

We calculate the nucleon contribution to the electromagnetic vertex of a neutrino in a background of particles, including the effect of the anomalous magnetic moment of the nucleons. Explicit formulas for the form factors are given in various physical limits of practical interest. Several applications of the results are mentioned, including the effect of an

J. André, T. Sjöstrand

We propose a simple scheme to start a parton-shower evolution description from a given jet configuration in $e^+ e^-$ annihilation events. This allows a convenient combination of the full angular information content of matrix elements with the detailed sub-jet structure of parton showers, and should give a realistic overall description of event properties. E

Nora Brambilla, Antonio Vairo

The complete $ q\bar{q}$ semirelativistic interaction is obtained as a gauge-invariant function of the Wilson loop and its functional derivatives. The approach is suitable for analytic evaluations as well as for lattice calculations. Here we consider three different models for the Wilson loop non-perturbative behaviour and discuss the related semirelativisti

Robert Fleischer

A brief review of CP violation in $K$ and $B$ decays is given. While the observables $\varepsilon$ and Re$(\varepsilon'/\varepsilon)$ describing CP violation in neutral $K$ decays do not allow a powerful test of the CKM mechanism of CP violation, rare $K\to\pi\nu\overline{\nu}$ decays and in particular the $B$-meson system are much more promising in this res

A. A. Kozhevnikov

The question of classical topological stability of the gauge vortex defects is reanalyzed upon taking into account the quantum perturbative effects. The purely Abelian Higgs string remains stable while the coupling of the effectively Abelian Z-string (with the fixed zero upper component of the scalar doublet) to the fermions of the minimal standard model is

V. G. Baryshevsky

The equations describing the T-violating photon scattering by a diffraction grating have been obtained. It is shown, that the T-violating rotation of the photon polarization plane appear under diffraction in a noncenter symmetrical diffraction grating. The rotation angle gives rise sharply, when the conditions of the photon resonance transmission are satisfi

J. Ignatius

The dynamical growth rate of bubbles nucleating in relativistic plasma in thermal first-order phase transitions is analyzed. The framework is a hydrodynamical model which consists of relativistic fluid and an order parameter field. The results of analytical approximations and numerical simulations coincide well.

Wilfried Buchmuller

Analytic estimates of screening masses in the symmetric, high-temperature phase of the SU(2)-Higgs model are reviewed. The size of the mass gap in the symmetric phase is closely related to the critical Higgs mass where the first-order electroweak phase transition changes to a smooth crossover. We also discuss some conjectures concerning the connection betwee

Tommaso Dorigo

We present the latest results of the searches for new particles in hadronic final states performed in proton-antiproton collisions at a center of mass energy of 1.8 TeV. The large data samples collected with the CDF and D0 detectors at the Tevatron collider between 1992 and 1995 allow searches for low cross section phenomena in dijet and multijet events, des

Claude Amsler

This report reviews the achievements of the Crystal Barrel experiment at the Low Energy Antiproton Ring (LEAR) at CERN. During seven years of operation Crystal Barrel has collected very large statistical samples in pbarp annihilation, especially at rest and with emphasis on final states with high neutral multiplicity. The measured rates for annihilation into

Thibault Damour, Bala R. Iyer, B. S. Sathyaprakash

The order of the post-Newtonian expansion needed, to extract in a reliable and accurate manner the fully general relativistic gravitational wave signal from inspiralling compact binaries, is explored. A class of approximate wave forms, called P-approximants, is constructed based on the following two inputs: (a) The introduction of two new energy-type and flu

Viviane M de Oliveira, J F Fontanari

The statistical properties of the local optima (metastable states) of the infinite range Ising spin glass with p-spin interactions in the presence of an external magnetic field h are investigated analytically. The average number of optima as well as the typical overlap between pairs of identical optima are calculated for general p. Similarly to the thermodyn

Kisor Mukhopadhyay, Abhijit Pal, Soumen Kumar Roy

A planar square lattice model with 3-d spins interacting with nearest neighbours through a potential -$εP_4 (cos θ_{ij})$ is studied by Monte Carlo technique. Lattice sizes from 10$\times$10 to 30$\times$30 are considered for calculating various thermodynamic averages. A 80$\times$80 lattice has been used to obtain the pair correlation function. To accuratel

Alexander J. Wagner, J. M. Yeomans

In this article we use a lattice-Boltzmann simulation to examine the effects of shear flow on a equilibrium droplet in a phase separated binary mixture. We find that large drops break up as the shear is increased but small drops dissolve. We also show how the tip-streaming, observed for deformed drops, leads to a state of dynamic equilibrium.

R. Martonak, W. Paul, K. Binder

In this paper we present a Path Integral Monte Carlo (PIMC) simulation of the orthorhombic phase of crystalline polyethylene, using an explicit atom force field with unconstrained bond lengths and angles. This work represents a quantum extension of our recent classical simulation (J. Chem. Phys. 106, 8918 (1997)). It is aimed both at exploring the applicabil

Peter F. Arndt, Thomas Heinzel, Vladimir Rittenberg

We consider a model in which positive and negative particles diffuse in an asymmetric, CP-invariant way on a ring. The positive particles hop clockwise, the negative counterclockwise and oppositely-charged adjacent particles may swap positions. Monte-Carlo simulations and analytic calculations suggest that the model has three phases; a "pure" phase i

M. Hagiwara, Y. Narumi, K. Kindo, M. Kohno

Susceptibility and high field magnetization measurements have been performed on powder samples of an $S$=1 bond alternating chain compound [\{Ni(333-tet)($μ$-N$_3$)\}$_n$](ClO$_4$)$_n$ (333-tet=tetraamine N,N'-bis(3-aminopropyl)-1,3-propanediamine). As the temperature is decreased, the susceptibility exhibits a round maximum at around 120 K and decreases

Tohru Koma, Hal Tasaki

We consider the classical XY model (O(2) nonlinear sigma-model) on a class of lattices with the (fractal) dimensions 1<D<2. The Berezinskii&#39;s harmonic approximation suggests that the model undergoes a phase transition in which the low temperature phase is characterized by stretched exponential decay of correlations. We prove an exponentially decaying upp

Ido Dagan, Lillian Lee, Fernando Pereira

We compare four similarity-based estimation methods against back-off and maximum-likelihood estimation methods on a pseudo-word sense disambiguation task in which we controlled for both unigram and bigram frequency. The similarity-based methods perform up to 40% better on this particular task. We also conclude that events that occur only once in the training

Jens-Uwe Moeller

The DIAlogue MOdel Learning Environment supports an engineering-oriented approach towards dialogue modelling for a spoken-language interface. Major steps towards dialogue models is to know about the basic units that are used to construct a dialogue model and possible sequences. In difference to many other approaches a set of dialogue acts is not predefined b

Carl Dettmann, Predrag Cvitanovic&#39;

We investigate intermittent diffusion using cycle expansions, and show that a truncation based on cycle stability achieves reasonable convergence.

A. V. Sweigart

The observed abundance variations in globular cluster red giants indicate that these stars may be mixing helium from the hydrogen shell outward into the envelope, presumably as a result of internal rotation. We have investigated the implications of such helium mixing for both the red- giant-branch (RGB) and horizontal-branch (HB) phases by computing a number

Gerhardt R. Meurer

Estimates of the total metal production rate (\dotρ_Z) and star formation rate at z > 2 are based on Lyman break systems observed in the rest-frame ultraviolet (UV). These observations are very sensitive to dust obscuration. Here I elucidate and refine the Meurer et al. (1997) method for calculating UV obscuration, presenting new relationships which accurate

C. R. Keeton, C. S. Kochanek, E. E. Falco

We combine photometry and lens modeling to study the properties of 17 gravitational lens galaxies between z=0.1 and 1. Most of the lens galaxies are passively evolving early-type galaxies, with a few spirals. The colors, scale lengths, and ellipticities of lens galaxies are similar to those of the general population of early-type galaxies, although there may

Arnon Dar

Recent observations with the Hubble Space Telescope have discovered in the nearest planetary nebula, the Helix Nebula, thousands of gigantic comet-like objects with planet like masses in a ring around the central brilliant star at a distance comparable to our own Oort cloud of comets. We propose that such circumstellar rings of planets exist around most star

Abraham Loeb, Rosalba Perna

The afterglow of a cosmological Gamma-Ray Burst (GRB) should appear on the sky as a narrow emission ring of radius 3x10^{16}cm(t/day)^{5/8} which expands faster than light. After a day, the ring radius is comparable to the Einstein radius of a solar mass lens at a cosmological distance. Thus, microlensing by an intervening star can modify significantly the l

R. I. Hynes, C. A. Haswell, R. P. Fender, C. R. Shrader

During 1996 the soft-X-ray transient and superluminal jet source GRO J1655-40 was observed in outburst with a multiwavelength campaign including HST, RXTE, CGRO and ground based facilities. Here we focus on a key question raised by the observations: where and how does the outburst optical flux originate? Any model must not only fit the optical spectra, but m

C. A. Haswell, R. I. Hynes

Hubble Space Telescope Observations of Black Hole X-Ray Transients are discussed in the context of the disk instability outburst model. We focus on the multiwavelength campaign following GRO J1655-40 through the summer 1996 outburst.

Sergei Y. Sazonov, Rashid A. Sunyaev, Oleg V. Terekhov, Niels Lund

We present the catalogue of gamma-ray bursts observed with the WATCH all-sky monitor on board the GRANAT satellite during the period December 1989 to September 1994. The cosmic origin of 95 bursts comprising the catalogue is confirmed either by their localization with WATCH or by their detection with other GRB experiments. For each burst its time history and

Jean Bellissard, Carlos J Camacho, Armelle Barelli, Francisco Claro

Using the results obtained by the non commutative geometry techniques applied to the Harper equation, we derive the areas distribution of random walks of length $ N $ on a two-dimensional square lattice for large $ N $, taking into account finite size contributions.

L. Brambila-Paz, H. Lange

Let $E$ be a vector bundle of rank $r\geq 2$ on a smooth projective curve $C$ of genus $g \geq 2$ over an algebraically closed field $K$ of arbitrary characteristic. For any integer with $1\le k\le r-1$ we define $${\se}_k(E):=k°E-r\max°F.$$ where the maximum is taken over all subbundles $F$ of rank $k$ of $E$. The ${s}_k$ gives a stratification of the modul

Frank Tony Smith

From sets and simple operations on sets, a Feynman Checkerboard physics model is constructed that allows computation of force strength constants and constituent mass ratios of elementary particles, with a Lagrangian structure that gives a Higgs scalar particle mass of about 146 GeV and a Higgs scalar field vacuum expectation value of about 252 GeV, giving a

Yasunori Nomura, Kazuhiro Tobe

We analyze a direct-transmission model of dynamical SUSY breaking previously proposed. In the model the gravitino mass is naturally smaller than $1~\KEV$, which is required from the standard cosmology. We find that there are many distinguishable features from in other models: for example the so-called GUT relation among the gaugino masses does not hold even

Jeremy Michelson

The moduli space metric for an arbitrary number of extremal black holes in four dimensions with arbitrary relatively supersymmetric charges is found.

Soren Bay, P. Lambropoulos, K. Molmer

We investigate an atomic $Λ$-system with one transition coupled to a laser field and a flat continuum of vacuum modes and the other transition coupled to field modes near the edge of a photonic band gap. The system requires simultaneous treatment of Markovian and non-Markovian dissipation processes, but the photonic band gap continuum can not be eliminated w

Weiqiang Wang

We construct irreducible modules V_α, α\in \C over W_3 algebra with c = -2 in terms of a free bosonic field. We prove that these modules exhaust all the irreducible modules of W_3 algebra with c = -2. Highest weights of modules V_α, α\in \C with respect to the full (two-dimensional) Cartan subalgebra of W_3 algebra are (α(α-1)/2, α(α-1)(2α-1)/6). They are pa

S. Chatterjee, P. S. Joarder

A self-consistent, thermodynamic approach is employed to derive the wave energy of a magnetohydrodynamic system within the harmonic approximation and to obtain the familiar dispersion relation from the resulting equation of motion. The evolution of the system due to an external perturbation is studied by a linear response formalism, that also gives the energ

V. N. Zhuravlev, T. Maniv, I. D. Vagner, P. Wyder

The propagation of a streamer near an insulating surface under the influence of a transverse magnetic field is theoretically investigated. In the weak magnetic field limit it is shown that the trajectory of the streamer has a circular form with a radius that is much larger than the cyclotron radius of an electron. The charge distribution within the streamer

R. Z. Zhdanov

We suggest a generalization of the Lie algebraic approach for constructing quasi-exactly solvable one-dimensional Schroedinger equations which is due to Shifman and Turbiner in order to include into consideration matrix models. This generalization is based on representations of Lie algebras by first-order matrix differential operators. We have classified ine

Melissa A. Lampert, Carmen Molina-Paris

Following a relativistic heavy ion collision, the quark-gluon plasma produced eventually undergoes a chiral phase transition. We assume that during this phase transition one can describe the dynamics of the system by the linear $σ$ model and that the expansion can be thought of as mostly radial. Because the $σ$ model is an effective field theory there is an

A. Saalfeld, G. Piller, L. Mankiewicz

In QCD the gauge-invariant gluon polarization Delta G in a nucleon can be defined either in a non-local way as the integral over the Ioffe-time distribution of polarized gluons, or in light-cone gauge as the forward matrix element of the local topological current. We have investigated both possibilities within the framework of QCD sum rules. Although the top

The OPAL Collaboration, K. Ackerstaff et al

Production of events with hadronic and leptonic final states has been measured in e^+e^- collisions at centre-of-mass energies of 130-172 GeV, using the OPAL detector at LEP. Cross-sections and leptonic forward-backward asymmetries are presented, both including and excluding the dominant production of radiative Z γevents, and compared to Standard Model expec

Stephen W. Leonard, Eric Poisson

The gravitational radiation originating from a compact binary system in circular orbit is usually expressed as an infinite sum over radiative multipole moments. In a slow-motion approximation, each multipole moment is then expressed as a post-Newtonian expansion in powers of v/c, the ratio of the orbital velocity to the speed of light. The bare multipole tru

P. Breitenlohner, G. Lavrelashvili, D. Maison

Recent progress in understanding of the internal structure of non-Abelian black holes is discussed. Talk given at the international Workshop on The Internal Structure of Black Holes and Spacetime Singularities, Haifa, Israel, June 29 -- July 3, 1997.

J. A. Clayhold, Z. H. Zhang, A. J. Schofield

We study the temperature-dependence of thermoelectric transport in proton-irradiated thin films of the high Tc cuprate Tl2212. All the anomalous transport conductivities are affected by the irradiation but maintain their non-Fermi liquid forms. We note however that the anomalous temperature dependence of the thermopower scales precisely with the temperature

Qijin Chen

45-degree rotated epitaxial diamond nucleation on both (001) and {111} planes of a silicon substrate was observed using chemical vapor deposition with nucleation enhancement by electron emission. The epitaxial relationship between diamond and Si is D(001)//Si(001) and D<100>//Si<110> in both cases. While the case of diamond nucleation on Si(001) may be expla

Takahiko Matsubara, Ayako Yoshisato, Masahiro Morikawa

Among several analytic approximations for the growth of density fluctuations in the expanding Universe, Zel&#39;dovich approximation in Lagrangian coordinate scheme is known to be unusually accurate even in mildly non-linear regime. This approximation is very similar to the Padé approximation in appearance. We first establish, however, that these two are act

Bohdan Paczynski

The Space Interferometry Mission (SIM), with its launch date planned for 2005, has as its goal astrometry with ~ 1 micro-arcsecond accuracy for stars as faint as 20th mag. If the SIM lives to expectations it can be used to measure astrometric displacements in the light centroid caused by gravitational microlensing in the events detected photometrically from

Mirjam Cvetic, Finn Larsen

We review the classical thermodynamics and the greybody factors of general (rotating) non-extreme black holes and discuss universal features of their near-horizon geometry. We motivate a microscopic interpretation of general black holes that relates the thermodynamics of an effective string theory to the geometry of the black hole in the vicinity of both the

H. Aoki

We consider origins of the baryon asymmetry which we observe today. We review the progress of electroweak-scale baryogenesis, and show a new mechanism, string-scale baryogenesis.

Samuel Conner, Asantha Cooray, Andre Fletcher, Bernard Burke

We present radio and optical observations of MG0248+0641, which contains a kiloparsec-scale ring-like structure in one of its radio lobes. The radio observations show a typical core-double morphology: a central core between two lobes, each of which has a hotspot. The western radio lobe appears as a nearly continuous ring, with linear polarization electric fi

Pavel Etingof, Alexander Varchenko

The quantum dynamical Yang-Baxter (QDYB) equation is a useful generalization of the quantum Yang-Baxter (QYB) equation introduced by Gervais, Neveu, and Felder. The QDYB equation and its quasiclassical analogue (the classical dynamical Yang-Baxter equation) arise in several areas of mathematics and mathematical physics (conformal field theory, integrable sys

Roselyn M. Abbiw-Jackson, William Langford

&#34;Mayer waves&#34; are long-period (6 to 12 seconds) oscillations in arterial blood pressure, which have been observed and studied for more than 100 years in the cardiovascular system of humans and other mammals. A mathematical model of the human cardiovascular system is presented, incorporating parameters relevantto the onset of Mayer waves. The model is

M. M. Boyce, J. Treurniet, P. J. S. Watson

It has been shown that the string-flip potential model reproduces most of the bulk properties of nuclear matter, with the exception of nuclear binding. Furthermore, it was postulated that this model, with the inclusion of the colour-hyperfine interaction, should produce binding. In some recent work a modified version of the string-flip potential model was de

Damien M. Pierce, Jens Erler

We discuss the results of a global fit to precision data in supersymmetric models. We consider both gravity- and gauge-mediated models. As the superpartner spectrum becomes light, the global fit to the data typically results in larger values of chi^2. We indicate the regions of parameter space which are excluded by the data. We discuss the additional effect

The OPAL Collaboration, K. Ackerstaff et al

We report a measurement of the B^0_s meson lifetime from B_s^0 -> D^-_s X decays, where D_s^- mesons are reconstructed in the D_s^- -> phi pi^- and D_s^- -> K^{*0} K^- decay channels. From approximately 3.7 million hadronic Z^0 decays recorded by the OPAL detector at LEP a sample is selected containing 911 +/- 83 candidates, of which 519 +/- 136 are estimate

The OPAL Collaboration, K. Ackerstaff et al

Helicity density matrix elements for inclusive K*(892)^0 mesons from hadronic Z^0 decays have been measured over the full range of K^*0 momentum using data taken with the OPAL experiment at LEP. A preference for occupation of the helicity zero state is observed at all scaled momentum x_p values above 0.3, with the matrix element rho_00 rising to 0.66 +/- 0.1

The OPAL Collaboration, K. Ackerstaff et al

The production rates of D^*+/- mesons in charm and bottom events at centre-of-mass energies of about 91 GeV and the partial width of primary cc(bar) pairs in hadronic Z^0 decays have been measured at LEP using almost 4.4 million hadronic Z^0 decays collected with the OPAL detector between 1990 and 1995. Using a combination of several charm quark tagging meth

The OPAL Collaboration, K. Ackerstaff et al

The inclusive production of prompt photons with energy above 10 GeV is measured using the OPAL detector in hadronic Z^0 decays at LEP. In contrast to previous measurements, the prompt photons were not required to be isolated. The production rate and energy spectrum are found to be in agreement with QCD predictions for the quark-to-photon fragmentation functi

The OPAL Collaboration, K. Ackerstaff et al

New measurements are presented of the photon structure function F_2^gamma(Q) at four values of Q^2 between 9 and 59 GeV/c^2 based on data collected with the OPAL detector at centre-of-mass energies of 161-172 GeV, with a total integrated luminosity of 18.1 pb^-1. The evolution of F_2^gamma with Q^2 in bins of x is determined in the Q^2 range from 1.86 to 135