November 1997 arXiv papers — page 2

Thomas Schwager, Thorsten Poeschel

We investigate the cooling rate of a gas of inelastically interacting particles. When we assume velocity dependent coefficients of restitution the material cools down slower than with constant restitution. This behavior might have large influence to clustering and structure formation processes.

Peter Sollich, Michael E Cates

A `polydisperse' system has an infinite number of conserved densities. We give a rational procedure for projecting its infinite-dimensional free energy surface onto a subspace comprising a finite number of linear combinations of densities (`moments'), in which the phase behavior is then found as usual. If the excess free energy of the system depends

S. V. Vyshenski

A peculiarity of the single-electron transistor effect makes it possible to observe this effect even in structures lacking a gate electrode altogether. The proposed method can be useful for experimental study of charging effects in structures with an extremely small central island confined between tunnel barriers like a nanometer-sized quantum dot or a macro

G. Juttner, A. Klumper, J. Suzuki

We present a novel treatment of finite temperature properties of the one-dimensional Hubbard model. Our approach is based on a Trotter-Suzuki mapping utilizing Shastry's classical model and a subsequent investigation of the quantum transfer matrix. We derive non-linear integral equations for three auxiliary functions which have a clear physical interpret

P. Fraundorf

We show that Bayesian inference, like that used in statistical mechanics, can guide the systematic construction of Fourier dark-field methods for localizing periodicity in near-field (e.g. scanning-tunneling and electron-phase-contrast) images. For crystals in an aperiodic field, the Fourier coefficient Ze^{i phi} combines with a prior estimate for backgroun

A. J. Coleman, E. P. Yukalova, V. I. Yukalov

A model of superconductivity is proposed taking into account repulsive particle interaction, mesoscopic phase separation and softening of crystalline lattice. These features are typical of many high-temperature superconductors. The main results obtained for the model are: (i) phase separation is possible only if repulsive forces play a significant role; (ii)

Xiang-Yu Ge, Mark D. Gould, Yao-Zhong Zhang, Huan-Qiang Zhou

A new two-parameter integrable model with quantum superalgebra $U_q[gl(3|1)]$ symmetry is proposed, which is an eight-state electron model with correlated single-particle and pair hoppings as well as uncorrelated triple-particle hopping. The model is solved and the Bethe ansatz equations are obtained.

Basilio X. Santiago, Rebecca A. W. Elson, Steinn Sigurdsson, Gerard F. Gilmore

We present V and I photometry of two open clusters in the LMC down to V ~ 26. The clusters were imaged with the Wide Field and Planetary Camera - 2 on board of the Hubble Space Telescope, as part of the Medium Deep Survey Key-Project. Both are low luminosity (Mv ~ -3.5), low mass systems (M ~ 10^3 Msolar). The chance discovery of these two clusters in two pa

Stephen E. Zepf

The traditional view of elliptical galaxies has been that they formed in a single, rapid burst of star formation at high redshift, and have evolved quiescently since that time. In opposition to this traditional view is evidence that at least some elliptical galaxies have formed from the merger of two disk galaxies. What has not been clear is which process is

P. Meszaros

Models of gamma ray bursts are reviewed in the light of recent observations of afterglows which point towards a cosmological origin. The physics of fireball shock models is discussed, with attention to the type of light histories and spectra during the gamma-ray phase. The evolution of the remnants and their afterglows is considered, as well as their implica

Takeshi Go Tsuru, Hironobu Matsumoto, Katsuji Koyama, Hiroshi Tomida

We compile X-ray data of clusters of galaxies at a wide range of redshift $z=0.0\sim1.0$ and compare X-ray luminosities, gas masses, iron abundances and iron masses of nearby clusters and those of distant clusters as a function of plasma temperature. All the date presented in this paper have been obtained only with \ASCA and/or \ROSAT. No evidence for a chan

S. B. Popov, V. M. Lipunov, M. E. Prokhorov, K. A. Postnov

We use "Scenario Machine" -- the population synthesis simulator -- to calculate the evolution of populations of selected types of X-ray sources after a starformation burst with the total mass in binaries (1--1.5) \cdot 10^6 M_{\odot}$ during the first 20 Myr after a burst. We present here the results of two sets of runs of the program. In the first s

Ralf Klessen, Pavel Kroupa

Self-consistent simulations of the dynamical evolution of a low-mass satellite galaxy without dark matter are reported. The orbits have eccentricities 0.46 <= e <= 0.96 in a Galactic dark halo resembling our Milky Way. For the simulations, a particle-mesh code with nested sub-grids and a direct-summation N-body code running with the special purpose hardware

Mordecai-Mark Mac Low

This review summarizes the argument for molecular clouds being dominated by turbulence, most likely super-Alfvenic turbulence. Five lines of observational evidence are given: molecular linewidths and line shapes, nonequilibrium chemical abundances, fractal cloud shapes, measurements of the dispersion of dust extinction through clouds, and Zeeman measurements

David Elbaz

This short paper reviews some of the results obtained from ISO observations (ISOCAM and ISOPHOT) on galaxy clusters: Chap.1: &#34;Intracluster dust&#34;: new evidence for the presence of dust outside galaxies. Chap.2:&#34;Mid-Infrared Emission of Galaxies&#34; origin of the mid-IR emission. Chap.3:&#34;Star Formation in Nearby Clusters&#34; correlation of th

J. -O. Goussard, P. Haensel, J. L. Zdunik

Models of differentially rotating protoneutron stars are calculated, using realistic equations of state of dense hot matter. Various conditions within the stellar interior, corresponding to different stages of protoneutron star evolution, are considered. Families of differentially rotating models of a given baryon mass are calculated, using a two-parameter f

B. Anoushirvani, D. Enström, S. Fredriksson, J. Hansson

We investigate the possibility that gamma-ray bursts originate in a concentric spherical shell with a given average redshift and find that this is indeed compatible with the data from the third BATSE (3B) catalog. It is also shown that there is enough freedom in the choice of unknown burst properties to allow even for extremely large distances to the majorit

W. Collmar, J. J. Blom, K. Bennett, H. Bloemen

The COMPTEL experiment aboard the Compton Gamma-Ray Observatory (CGRO) has observed the gamma-ray blazar 3C 279 several times between April 1991 and September 1995. This paper reports on a consistent analysis of these observations using the most recent COMPTEL data analysis tools. Detections and non-detections of 3C 279 along the CGRO-mission indicate a time

Olivier Debarre

We apply the Yau-Zaslow-Beauville method to compute the Euler characteristic of the generalized Kummer varieties attached to a complex abelian surface (a calculation also done by Goettsche and Soergel by different methods). It is related to the number of genus 2 curves on an abelian surface.

Juan M. Maldacena

We show that the large $N$ limit of certain conformal field theories in various dimensions include in their Hilbert space a sector describing supergravity on the product of Anti-deSitter spacetimes, spheres and other compact manifolds. This is shown by taking some branes in the full M/string theory and then taking a low energy limit where the field theory on

O. J. P. Eboli, M. C. Gonzalez-Garcia, J. K. Mizukoshi

We analyze the potential of the Next Linear $e^+e^-$ Collider to study anomalous quartic vector-boson interactions through the processes $e^+ e^- \to W^+W^-Z$ and $ZZZ$. In the framework of $SU(2)_L \otimes U(1)_Y$ chiral Lagrangians, we examine all effective operators of order $p^4$ that lead to four-gauge-boson interactions but do not induce anomalous tril

Michael J. Hudson, Stephen D. J. Gwyn, Haakon Dahle, Nick Kaiser

A tangential distortion of background source galaxies around foreground lens galaxies in the Hubble Deep Field is detected at the 99.3% confidence level. An important element of our analysis is the use of photometric redshifts to determine distances of lens and source galaxies and rest-frame B-band luminosities of the lens galaxies. The lens galaxy halos obe

L. Conti, A. Donini, V. Gimenez, G. Martinelli

We compute several matrix elements of dimension-six four-fermion operators and extract their B-parameters. The calculations have been performed with the tree-level Clover action at $β= 6.0$. The renormalization constants and mixing coefficients of the lattice operators have been obtained non-perturbatively. In the $\MSbar$ renormalization scheme, at a renorm

A. Panaitescu, P. Meszaros

We present numerical simulations of Gamma-Ray Bursts arising from external shocks in the impulsive and wind models, including a weak or a strong coupling between electrons and protons plus magnetic fields, and analyze the burst features in each scenario. The dynamics of the ejecta and external medium are followed into the late stages of deceleration, in orde

R. A. Battye, J. Robinson, A. Albrecht

Final published version.

G. Cvetic

Recently it has been pointed out that diagonal Padé approximants to truncated perturbative series in gauge theories have the remarkable property of being independent of the choice of the renormalization scale as long as the gauge coupling parameter $α(p^2)$ is taken to evolve according to the one-loop renormalization group equation -- i.e., in the large-$β_0

Sergio A. Cannas

We introduce a stochastic cellular automaton with power law spatial decaying long-range interactions. In some limit this model reduces to the Domany-Kinzel cellular automaton. Monte Carlo and mean field calculations of the phase diagram of the model for different ranges of interactions are compared.

Kiyohide Nomura, Atsuhiro Kitazawa

Berezinskii-Kosterlitz-Thouless (BKT) transition, the transition of the 2D sine-Gordon model, plays an important role in the low dimensional physics. We relate the operator content of the BKT transition to that of the SU(2) Wess-Zumino-Witten model, using twisted boundary conditions. With this method, in order to determine the BKT critical point, we can use

D. Boer, R. Jakob, P. J. Mulders

We present the leading unpolarized and single spin asymmetries in inclusive two-hadron production in electron-positron annihilation at the Z pole. The azimuthal dependence in the unpolarized differential cross section of almost back-to-back hadrons is a leading cos(2 phi) asymmetry, which arises solely due to the intrinsic transverse momenta of the quarks. A

Giulio Magli

The general exact solution describing the dynamics of anisotropic elastic spheres supported only by tangential stresses is reduced to a quadrature using Ori&#39;s mass-area coordinates. This leads to the explicit construction of the root equation governing the nature of the central singularity. Using this equation, we formulate and motivate on physical groun

E. S. Cheb-Terrab, A. D. Roche

A systematic algorithm for building integrating factors of the form mu(x,y&#39;) or mu(y,y&#39;) for non-linear second order ODEs is presented. When such an integrating factor exists, the algorithm determines it without solving any differential equations. Examples of ODEs not having point symmetries are shown to be solvable using this algorithm. The scheme w

R. G. Edwards, U. M. Heller, T. R. Klassen

The ALPHA collaboration has determined the O(a) improved Wilson quark action for lattice spacings $a\leq 0.1$ fm, in the quenched approximation. We extend this result to coarser lattices, $a\leq 0.17$ fm, and calculate the hadron spectrum on them. The large range of lattice spacings obtained by combining our results with earlier ones on finer lattices, allow

Metin Gurses, Atalay Karasu

We give the conditions for a system of N- coupled Korteweg de Vries(KdV) type of equations to be integrable. Recursion operators of each subclasses are also given. All examples for N=2 are explicitly given.

Jarmo Hietarinta, Claude Viallet

We present a number of second order maps, which pass the singularity confinement test commonly used to identify integrable discrete systems, but which nevertheless are non-integrable. As a more sensitive integrability test, we propose the analysis of the complexity (``algebraic entropy&#39;&#39;) of the map using the growth of the degree of its iterates: int

Andrew J. Bordner

Integrability of the quantum Boussinesq equation for c=-2 is demonstrated by giving a recursive algorithm for generating explicit expressions for the infinite number of commuting charges based on a reduction of the W(infinity) algebra. These charges exist for all spins $s \geq 2$. Likewise, reductions of the W(infinity/2) and W((1+infinity)/2) algebras yield

Granddon D. Yen, Mark I. Gorenstein, Walter Greiner, Shin Nan Yang

We recapitulate a thermodynamically consistent excluded volume hadron gas model and examine its differences with other ``thermal models&#39;&#39; used in the literature. Preliminary experimental data for particle number ratios in the collisions of Au+Au at the BNL AGS (11$A$ GeV/$c$) and Pb+Pb at the CERN SPS (160$A$ GeV/$c$) are analyzed. For equal values o

Qiang Zhao, Zhenping Li, C. Bennhold

A quark model approach to the photoproduction of vector mesons off nucleons is proposed. Its starting point is an effective Lagrangian of the interaction between the vector meson and the quarks inside the baryon. This paper develops the formalism and highlights the dynamical roles of s-channel resonances. It is demonstrated that the proposed approach is idea

F. Simkovic, G. Pantis, Amand Faessler

We have performed a critical analysis of different approximation schemes for the calculation of two-neutrino double beta decay (TNDBD) matrix elements. We have shown that within the single-particle approximation of nuclear Hamiltonian the TNDBD matrix element is equal to zero. The (renormalized) quasiboson approximation scheme imply for TNDBD transition oper

E. Alvarez, J. Borlaf, J. H. León

In this paper the complete geometrical setting of (lowest order) abelian T-duality is explored with the help of some new geometrical tools (the reduced formalism). In particular, all invariant polynomials (the integrands of the characteristic classes) can be explicitly computed for the dual model in terms of quantities pertaining to the original one and with

Giuliano Preparata, She-Sheng Xue

A variational calculation is presented of the ADM-energy of the quantized gravitational field around a wormhole solution of the classical Einstein&#39;s equations. One finds the energy of such state to be in general lower than the perturbative ground state, in which the quantized gravity field fluctuates around flat (Euclidean) space-time. As a result the st

Andre Lukas, Burt A. Ovrut, Daniel Waldram

In the low energy limit of for M-theory on S^1/Z_2, we calculate the gaugino condensate potential in four dimensions using the background solutions due to Horava. We show that this potential is free of delta-function singularities and has the same form as the potential in the weakly coupled heterotic string. A general flux quantization rule for the three-for

A. A. Deriglazov, A. V. Galajinsky

We suggest a super Poincaré invariant action for closed eleven dimensional superstring. The sector of physical variables $x^i$, $θ_a$, $\barθ_{\dot a}$, with $a,\dot a=1...8$ and $x^i$ the transverse part of the D=11 $x^μ$ coordinate is shown to possess free dynamics.

Elsebeth Schroder, Ola Tornkvist

We derive an exact equation of motion for a non-relativistic vortex in two- and three-dimensional models with a complex field. The velocity is given in terms of gradients of the complex field at the vortex position. We discuss the problem of reducing the field dynamics to a closed dynamical system with non-locally interacting strings as the fundamental degre

Markus Ringner

We show how a difference in the correlation length longitudinally and transversely, with respect to the jet axis in e+e- annihilation, arises naturally in a model for Bose-Einstein correlations based on the Lund string model. The difference is more apparent in genuine three-particle correlations and they are therfore a good probe for the longitudinal stretch

J. Soffer, O. V. Teryaev

The effects, originating from the longitudinal gluon polarization, are considered. We derive the analogue of the Wandzura-Wilczek relation for the light-cone distributions of polarized gluons in a transversely polarized nucleon. The short distance cross-section is entirely due to the intrinsic transverse momenta of gluon in the nucleon, in complete analogy t

Jan Govaerts

Two recent low energy precision experiments are considered, in order to illustrate how limits set by these measurements for couplings beyond the Standard Model are complementary to high energy constraints.

Stephan narison

I briefly review the estimate of the gluonia masses, decay and mixings in QCD with massless quarks from QCD spectral sum rules and some low-energy theorems. The data in the $0^{++}$ channel can be explained with some maximal gluonium-quarkonium mixing schemes, which then suggest a large violation of the OZI rule, similar to the case of the $η&#39;$ in the $U

N. Fornengo, C. Giunti, C. W. Kim, J. Song

The propagation of neutrinos in a gravitational field is studied by developing a method of calculating a covariant quantum-mechanical phase in a curved space-time. The result is applied to neutrino propagation in the Schwarzschild metric.

A. A. Penin, A. A. Pivovarov

Long distance contribution to the $K^0-\bar K^0$ mixing is taken into account consistently and the corrections to the naive duality result represented by the famous box diagram are found to be small. Estimates are given in the leading order of the chiral perturbation theory.

W. Hollik

This talk summarizes topical theoretical work for tests of the electroweak theory and reviews the status of the electroweak Standard Model in view of the recent precision data reported at the 1997 summer conferences.

C. D. Froggatt, H. B. Nielsen

We describe a fit to the charged fermion mass hierarchy using the chiral quantum numbers of the maximal anti-grand unification group $SMG^3 \times U(1)_f$, where $SMG \equiv SU(3) \times SU(2) \times U(1)$. This fit suggests a set of Higgs fields responsible for the breakdown, near the Planck scale, of $SMG^3 \times U(1)_f$ to the Standard Model group.

L. Ya. Glozman

Beyond the scale of spontaneous breaking of chiral symmetry light and strange baryons should be considered as systems of three constituent quarks with confining interaction and a chiral interaction that is mediated by Goldstone bosons between the constituent quarks. The flavor-spin structure and sign of the short-range part of the Goldstone boson exchange in

W. Hollik

The calculation of electroweak precision observables in the MSSM is reviewed. The description of the 1997 data and the results of updated global fits are discussed in comparison with the Standard Model.

M. N. Achasov, A. V. Berdyugin, A. V. Bozhenok, A. D. Bukin

Preliminary results on the study of e+e- --> phi(1020) --> pi0 pi0 gamma, eta pi0 gamma processes from SND experiment at VEPP-2M collider in Novosibirsk are presented. Branching ratios of rare radiative phi --> pi0 pi0 gamma and phi --> pi0 eta gamma decays are measured: B(phi --> pi0 pi0 gamma ) = (1.1 +- 0.2) * 10^-4 (invariant mass (pi0 pi0) < 800 MeV), B

ARGUS Collaboration

Using the ARGUS detector at the $e^+ e^-$ storage ring DORIS II, we have measured the Michel parameters $ρ$, $ξ$, and $ξδ$ for $τ^{\pm}\to l^{\pm} ν\barν$ decays in $τ$-pair events produced at center of mass energies in the region of the $Υ$ resonances. Using $τ^\mp \to ρ^\mp ν$ as spin analyzing tags, we find $ρ_{e}=0.68\pm 0.04 \pm 0.08$, $ξ_{e}= 1.12 \pm

Joakim Nystrand, Spencer Klein

This presentation will show the feasibility of studying two-photon interactions in the STAR experiment at RHIC. Signals, detection efficiencies, backgrounds, triggering and analysis techniques will be discussed.

John D. Barrow

We review recent progress in the study of varying constants and attempts to explain the observed values of the fundamental physical constants. We describe the variation of $G$ in Newtonian and relativistic scalar-tensor gravity theories. We highlight the behaviour of the isotropic Friedmann solutions and consider some striking features of primordial black ho

Lluis Bel

We construct a distinguished set of positive and negative energy modes of the Klein-Gordon equation for any Born frame of reference in Minkowski&#39;s space-time. Unlike the case of a galilean frame of reference it is unclear whether this set of modes may be an appropriate basis to define the vacuum of a quantized scalar field in an accelerated cavity.

Winfried Zimdahl

With the help of a conformal, timelike Killing-vector we define generalized equilibrium states for cosmological fluids with particle production. For massless particles the generalized equilibrium conditions require the production rate to vanish and the well known ``global&#39;&#39; equilibrium of standard relativistic thermodynamics is recovered as a limitin

F. Babalievski

Two basic approaches to the cluster counting task in the percolation and related models are discussed. The Hoshen-Kopelman multiple labeling technique for cluster statistics is redescribed. Modifications for random and aperiodic lattices are sketched as well as some parallelised versions of the algorithm are mentioned. The graph-theoretical basis for the spa

M. Heerema, F. Ritort

We examine the problem of damage spreading in the off-equilibrium mode coupling equations. The study is done for the spherical $p$-spin model introduced by Crisanti, Horner and Sommers. For $p>2$ we show the existence of a temperature transition $T_0$ well above any relevant thermodynamic transition temperature. Above $T_0$ the asymptotic damage decays to ze

Goutam Tripathy, Mustansir Barma

We study the effect of quenched spatial disorder on the steady states of driven systems of interacting particles. Two sorts of models are studied: disordered drop-push processes and their generalizations, and the disordered asymmetric simple exclusion process. We write down the exact steady-state measure, and consequently a number of physical quantities expl

Horacio M. Pastawski, Gonzalo Usaj

The Quantum Zeno Effect (QZE) implies that a too frequent ($ω_ϕ\to \infty)$ observation of a quantum system would trap it in its initial state, even though it would be able to evolve to some other state if not observed. In our scheme, interacting spins in a 3-d cubic lattice, ``observe&#39;&#39; each other with a frequency $ω_ϕ$ $\propto \sqrt{J_x^2+J_y^2+J_

J. M. G. Vilar, J. M. Rubí

We show that scaling arguments are very useful to analyze the dynamics of periodically modulated noisy systems. Information about the behavior of the relevant quantities, such as the signal-to-noise ratio, upon variations of the noise level, can be obtained by analyzing the symmetries and invariances of the system. In this way, it is possible to predict dive

C. J. Perez, F. Ritort

We examine the dynamics of the Kuramoto model with a new analytical approach. By defining an appropriate set of moments the dynamical equations can be exactly closed. We discuss some applications of the formalism like the existence of an effective Hamiltonian for the dynamics. We also show how this approach can be used to numerically investigate the dynamica

X. S. Chen, V. Dohm

We demonstrate that the standard O(n) symmetric $ϕ^{4}$ field theory does not correctly describe the leading finite-size effects near the critical point of spin systems on a $d$-dimensional lattice with $d > 4$. We show that these finite-size effects require a description in terms of a lattice Hamiltonian. For $n \to \infty$ and $n=1$ explicit results are gi

Andreas Schadschneider

Cellular automata have turned out to be important tools for the simulation of traffic flow. They are designed for an efficient impletmentation on the computer, but hard to treat analytically. Here we discuss several approaches for an analytical description of the Nagel-Schreckenberg (NaSch) model and its variants. These methods yield the exact solution for t

M. Benakli, S. Raghavan, A. Smerzi, S. Fantoni

We consider a Bose-Einstein condensate (BEC) of $N$ atoms of repulsive interaction $\sim U_0$, in an elliptical trap, axially pierced by a Gaussian-intensity laser beam, forming an effective (quasi-2D) toroidal trap with minimum at radial distance $ρ= ρ_p$. The macroscopic angular momentum states $Ψ_l(ρ,θ) \sim \sqrt{N}Φ_l(ρ) e^{i l θ}$ for integer $l$ sprea

Jianjun Xie, Matthias Scheffler

Lattice relaxations, surface phonon spectra, surface energies, and work functions are calculated for Rh(100) and Rh(110) surfaces using density-functional theory and the full-potential linearized augmented plane wave method. Both, the local-density approximation and the generalized gradient approximation to the exchange-correlation functional are considered.

V. I. Yukalov

The theory of mesoscopic fluctuations is applied to inhomogeneous solids consisting of chaotically distributed regions with different crystalline structure. This approach makes it possible to describe statistical properties of such mixture by constructing a renormalized Hamiltonian. The relative volumes occupied by each of the coexisting structures define th

Alex Hansen, Mogens H. Jensen, Kim Sneppen, Giovanni Zocchi

We present a statistical mechanics treatment of the stability of globular proteins which takes explicitly into account the coupling between the protein and water degrees of freedom. This allows us to describe both the cold and the warm unfolding, thus qualitatively reproducing the known thermodynamics of proteins.

D. M. Whittaker

Microcavity inhomogeneous line widths are calculated numerically using a microscopic two dimensional model of the polariton interaction with quantum well disorder. The calculations show show that in most structures the line widths are determined by disorder scattering between polariton and exciton states. This is because motional narrowing effectively remove

C. M. Wei, A. Gross, M. Scheffler

The presence of sulfur atoms on the Pd(100) surface is known to hinder the dissociative adsorption of hydrogen. Using density-functional theory and the full-potential linear augmented plane-wave method, we investigate the potential energy surface (PES) of the dissociative adsorption of H_2 on the sulfur covered Pd(100) surface. The PES is changed significant

E. Bascones, G. Gomez-Santos, J. J. Saenz

Recent experiments on atomic-scale metallic contacts have shown that the quantization of the conductance appears clearly only after the average of the experimental results. Motivated by these results we have analyzed a simplified model system in which a narrow neck is randomly coupled to wide ideal leads, both in absence and presence of time reversal invaria

Haye Hinrichsen, Hari M. Koduvely

The local persistence probability P_l(t) that a site never becomes active up to time t, and the global persistence probability P_g(t) that the deviation of the global density from its mean value rho(t)-<ρ(t)> does not change its sign up to time t are studied in a one-dimensional directed percolation process by Monte Carlo simulations. At criticality, startin

Franz-Josef Elmer

Two different controlling methods are proposed to stabilize unstable continuous-sliding states of a dry-friction oscillator. Both methods are based on a delayed-feedback mechanism well-known for stabilizing periodic orbits in deterministic chaos. The feedback variable is the elastic deformation. The control parameter is either the sliding velocity or the nor

Carl P. Dettmann, Per Dahlqvist

We compute the diffusion coefficient and the Lyapunov exponent for a diffusive intermittent map by means of cycle expansion of dynamical zeta functions. The asymptotic power law decay of the coefficients of the relevant power series are known analytically. This information is used to resum these power series into generalized power series around the algebraic

Alejandro Gangui

We report briefly on a recent analysis of the texture-induced CMB radiation three-point correlation function of temperature anisotropies as predicted by an analytical model. We specialize our analysis to both large-scales (e.g., for COBE-DMR, where we compare our prediction with the actual four-year data) and intermediate-scales. We show how the latter case

Alejandro Gangui, Edgard Gunzig

In this article we review recent work aimed at showing explicitly the influence of electromagnetic self corrections on the dynamics of a circular vortex line endowed with a current at first order in the coupling between the current and the self-generated electromagnetic field.

Eiichiro Komatsu, Toshifumi Futamase

We investigate a possibility to restrict the chaotic inflationary scenario with &#34;large&#34; nonminimally coupled inflaton(&#34;phi&#34;) field considered by Fakir and Unruh by means of the observed CMBR anisotropy. We calculate the contributions of the long wavelength gravitational waves generated in the inflationary period to CMBR anisotropy quadrupole

Norbert Langer, Alexander Heger

We summarize the present status of the predictions of massive star models for the evolution of their surface properties. After discussing luminosity, temperature and chemical composition, we focus on the question whether massive stars may arrive at critical rotation during their evolution, either on the main sequence or in later stages. We find both cases to

L. Portinari, C. Chiosi, A. Bressan

New detailed stellar yields of several elemental species are derived for massive stars in a wide range of masses (from 6 to 120 Msol) and metallicities (Z= 0.0004, 0.004, 0.008, 0.02, 0.05). Our calculations are based on the Padova evolutionary tracks and take into account recent results on stellar evolution, such as overshooting and quiescent mass-loss, pay

J A Sellwood

The radial distribution of mass in a disk galaxy is strongly constrained by its rotation curve. The separate contributions from the individual stellar populations and dark matter (DM) are not easily disentangled, however, especially since there is generally no feature to indicate where the component dominating the central attraction switches from luminous to

J. -P. Kneib

Gravitational Lensing is an efficient tool to probe: the mass distribution of collapsed systems: galaxies and clusters; high redshift objects thanks to the gravitational amplification; and the geometry of the Universe. I will review here some important aspects of lensing and related issues in observational cosmology.

J. F. Gallimore, A. J. Holloway, A. Pedlar, C. G. Mundell

We present 0.15 arcsec (56 pc) resolution MERLIN observations of neutral hydrogen (HI) 21 cm absorption detected towards the arcsecond-scale radio jet of the Seyfert 1.5 galaxy Markarian 6. Absorption is detected only towards a bright, compact radio feature located, in projection, ~ 380 pc north of the likely location of the optical nucleus. Based on compari

B. E. J. Pagel, L. Portinari

The slope Delta Y/Delta Z is a quantity of interest in relation to stellar evolution, the initial mass function and the determination of the primordial helium abundance. In this paper we estimate Delta Y/Delta Z from fine structure in the Main Sequence of nearby stars from Hipparcos data for stars with Z \leq Zsun and find a value of about 3, which is consis

B. M. Gaensler, R. N. Manchester, A. J. Green

We present Australia Telescope Compact Array (ATCA) observations of the supernova remnant (SNR) G296.8-00.3. A 1.3-GHz continuum image shows the remnant to have a complex multi-shelled appearance, with an unusual rectangular strip running through its centre. HI absorption yields a kinematic distance to the remnant of 9.6+/-0.6 kpc, from which we estimate an

A. D. Reid, R. W. Hunstead, M. M. Pierre

As part of an extensive radio--IR--optical--X-ray study of ROSAT clusters of galaxies in the Hydra region we have observed the bimodal Abell cluster A3528, located in the core of the Shapley Supercluster (z ~ 0.053), with the Molonglo Observatory Synthesis Telescope at 843 MHz and the Australia Telescope Compact Array at 1.4 and 2.4 GHz. This is part I in a

D. Band, J. Matteson, M. Briggs, W. Paciesas

The absence of a BATSE line detection in a gamma-ray burst spectrum during the mission&#39;s first six years has led to a statistical analysis of the occurrence of lines in the BATSE burst database; this statistical analysis will still be relevant if lines are detected. We review our methodology, and present new simulations of line detectability as a functio

David Band, Dieter Hartmann

Various burst origin scenarios require a host object in the burst error box or near a well-located position. For example, a host galaxy should be present in the standard cosmological models. We present a methodology which evaluates whether the observed detections and nondetections of potential host objects in burst error boxes are consistent with the presenc

David Band, Lyle Ford

Previous studies of the evolution of gamma-ray burst spectra have generally relied on fitting sequences of spectra. These studies usually were confined to bright bursts and often lacked sufficient temporal resolution. We have developed techniques which sacrifice spectral resolution for temporal resolution. First, the crosscorrelations between intensity light

David Band, Michael Koenig, Anton Chernenko

Linear State Space Modeling determines the hidden autoregressive (AR) process in a noisy time series; for an AR process the time series&#39; current value is the sum of current stochastic ``noise&#39;&#39; and a linear combination of previous values. We present preliminary results from modeling a sample of 4 channel BATSE LAD lightcurves. We determine the or

Christof Zalka

I improve the tight bound on quantum searching by Boyer et al. (quant-ph/9605034) to a matching bound, thus showing that for any probability of success Grovers quantum searching algorithm is optimal. E.g. for near certain success we have to query the oracle pi/4 sqrt{N} times, where N is the size of the search space. I also show that unfortunately quantum se

J. Gómez-Gomar, M. Hernanz, J. José, J. Isern

Classical novae are important producers of radioactive nuclei, such as be7, n13, f18, na22 and al26. The disintegration of these nuclei produces positrons (except for be7) that through annihilation with electrons produce photons of energies 511 keV and below. Furthermore, be7 and na22 decay producing photons with energies of 478 keV and 1275 keV, respectivel

Oswaldo M. Del Cima, Daniel H. T. Franco, Jose A. Helayel-Neto, Olivier Piguet

Considering three-dimensional Chern-Simons theory, either coupled to matter or with a Yang-Mills term, we show the validity of a trace identity, playing the role of a local form of the Callan-Symanzik equation, in all orders of perturbation theory. From this we deduce the vanishing of the $β$-function associated to the Chern-Simons coupling constant and the

M. V. Cougo-Pinto, C. Farina, A. Tort, J. Rafelski

We obtain using Schwinger&#39;s proper time approach the Casimir-Euler-Heisenberg effective action of fermion fluctuations for the case of an applied magnetic field. We implement here the compactification of one space dimension into a circle through anti-periodic boundary condition. Aside of higher order non-linear field effects we identify a novel contribut

Carsten Gundlach

Near the black hole threshold in phase space, the black hole mass as a function of the initial data shows the "critical scaling" M \simeq C (p-p_*)^\gamma, where p labels a family of initial data, p_* is the value of p at the threshold, and the critical exponent \gamma is universal for a given matter model. The black hole charge Q obeys a similar law. To com

Ettore Remiddi

It is by now well established that, by means of the integration by part identities, all the integrals occurring in the evaluation of a Feynman graph of given topology can be expressed in terms of a few independent master integrals. It is shown in this paper that the integration by part identities can be further used for obtaining a linear system of first ord

A. Bassetto, G. Nardelli

Classical vacuum - pure gauge - solutions of Euclidean two-dimensional SU(2) Yang-Mills theories are studied. Topologically non-trivial vacua are found in a class of gauge group elements isomorphic to $S_2$. These solutions are unexpectedly related to the solution of the non-linear O(3) model and to the motion of a particle in a periodic potential.

D. A. Trifonov

The Barut-Girardello coherent states (BG CS) representation is extended to the noncompact algebras u(p,q) and sp(N,R) in (reducible) quadratic boson realizations. The sp(N,R) BG CS take the form of multimode ordinary Schrödinger cat states. Macroscopic superpositions of 2^{n-1} sp(N,R) CS (2^n canonical CS, n=1,2,...) are pointed out which are overcomplete i