October 1998 arXiv papers — page 22

M. R. Hogerheijde, E. F. van Dishoeck, J. M Salverda, G. A. Blake

Aperture synthesis and single-dish (sub) millimeter molecular lines and continuum observations reveal in great detail the envelope structure of deeply embedded young stellar objects (SMM1, SMM2, SMM3, SMM4) in the densely star-forming Serpens Molecular Cloud. Resolved millimeter continuum emission constrains the density structure to a radial power law with i

Thomas S. Statler, Herwig Dejonghe, Tammy Smecker-Hane

A variety of modeling techniques is used with surface photometry from the literature and recently acquired high-accuracy stellar kinematic data to constrain the three-dimensional mass distribution in the luminous cuspy elliptical galaxy NGC 1700. First, we model the radial velocity field and photometry, and, using a Bayesian technique, estimate the triaxiali

Sidney van den Bergh

Important problems to which we would like to find answers are: What are the distances to the Large Magellanic Cloud (LMC) and the Small Magellanic Cloud (SMC)? What is the present distribution of stars, gas and dark matter in the Clouds, and how did it evolve? How, and where, did the Magellanic Clouds form, and how have their orbits evolved? Finally the rece

I. S. Booth, R. B. Mann

The popular Hamilton-Jacobi method first proposed by Brown and York for defining quasilocal quantities such as energy for spatially bound regions assumes that the spatial boundary is orthogonal to the foliation of the spacetime. Such a restriction is undesirable for both theoretical and computational reasons. We remove the orthogonality assumption and show t

H. W. Griesshammer

A computation of the NRQCD $\beta$ function both in the Lorentz gauge family and in the Coulomb gauge to one loop order endorses a velocity power counting scheme for dimensionally regularised NRQCD. In addition to the ultrasoft scale represented by bremsstrahlung gluons and the potential scale with Coulomb gluons and on-shell quarks, a soft r\'egime is ident

J. S. Sa' Martins, P. M. C. de Oliveira

Motivated by the decade-long debate over the issue of criticality supposedly observed in nuclear multifragmentation, we propose a dynamical lattice model to simulate the phenomenon. Its Ising Hamiltonian mimics a short range attractive interaction which competes with a thermal-like dissipative process. The results here presented, generated through an event-b

Shailesh Chandrasekharan

Qualitative features of Ginsparg-Wilson fermions, as formulated by Neuberger, coupled to two dimensional U(1) gauge theory are studied. The role of the Wilson mass parameter in changing the number of massless flavors in the theory and its connection with the index of the Dirac operator is studied. Although the index of the Dirac operator is not related to th

A. V. Bogdanov, A. S. Gevorkyan, A. G. Grigoryan, S. A. Matveev

A new formulation of the theory of quantum mechanical multichannel scattering for three-body collinear systems is proposed. It is shown, that in this simple case the principle of quantum determinism in the general case breaks down and we have a micro-irreversible quantum mechanics. The first principle calculations of the quantum chaos (wave chaos) were pursu

Paul M. Fishbane, Peter Kaus

Using recent data on neutrino oscillations, we argue that a hierarchical solution for neutrino masses in a three-family context is possible, and that the masses of the tau and mu neutrinos are very nearly determined within that possibility. We also examine the predictions of a model that determines neutrino and charged lepton mass matrices as well as its con

Paul G. Kwiat, Edo Waks, Andrew G. White, Ian Appelbaum

Using the process of spontaneous parametric down conversion in a novel two-crystal geometry, one can generate a source of polarization-entangled photon pairs which is orders of magnitude brighter than previous sources. We have measured a high level of entanglement between photons emitted over a relatively large collection angle, and over a 10-nm bandwidth. A

Kaiki Taro Inoue

Measurements of cosmic microwave background (CMB) anisotropy are ideal experiments for discovering the non-trivial global topology of the universe. To evaluate the CMB anisotropy in multiply-connected compact cosmological models, one needs to compute the eigenmodes of the Laplace-Beltrami operator. Using the direct boundary element method, we numerically obt

A. V. Kotikov, D. V. Peshekhonov

We propose a new approach for taking into account the Q^2 dependence of measured asymmetry A1. This approach is based on the similarity of the Q2 behaviour and the shape of the spin-dependent structure function g1(x,Q^2) and spin averaged structure function F3(x,Q^2). The analysis is applied on available experimental data.

R. Nebauer, J. Aichelin, the INDRA collaboration

We compare in detail central collisions Xe(50A MeV) + Sn, recently measured by the INDRA collaboration, with the Quantum Molecular Dynamics (QMD) model in order to identify the reaction mechanism which leads to multifragmentation. We find that QMD describes the data quite well, in the projectile/target region as well as in the midrapidity zone where also sta

Richard P. Sear

At low temperature, spheres with a very short-ranged attraction exist as a close-packed solid coexisting with an infinitely dilute gas. We find that the ratio of the interfacial tension between these two phases to the thermal energy diverges as the range of the attraction goes to zero. The large tensions when the interparticle attractions are short-ranged ma

Derek B. Leinweber, Ding H. Lu, Anthony W. Thomas

The quark mass dependence of nucleon magnetic moments is explored over a wide range. Quark masses currently accessible to lattice QCD, which lie beyond the regime of chiral perturbation theory (chiPT), are accessed via the cloudy bag model (CBM). The latter reproduces the leading nonanalytic behavior of chiPT, while modeling the internal structure of the had

Marco Bochicchio

We transform, by means of a fiberwise duality, the partition function of QCD on a product of two two-tori, into a four-dimensional sigma-model, whose target space is the cotangent space of unitary connections on the fiber torus fiberwise.

Marco Bochicchio

By means of a certain exact non-abelian duality transformation, we show that there is a natural embedding, dense in the sense of the distributions in the large-N limit, of parabolic Higgs bundles of rank N on a fiber two-dimensional torus into the QCD functional integral, fiberwise over the base two-dimensional torus of the trivial elliptic fibration on whic

A. G. White, P. K. Lam, M. S. Taubman, M. A. M. Marte

We report the first observation of the quantum effects of competing $χ^{(2)}$ nonlinearities. We also report new classical signatures of competition, namely clamping of the second harmonic power and production of nondegenerate frequencies in the visible. Theory is presented that describes the observations as resulting from competition between various $χ^{(2)

R. Gielerak, P. Lugiewicz

Covariant stochastic partial (pseudo-)differential equations are studied in any dimension. In particular a large class of covariant interacting local quantum fields obeying the Morchio-Strocchi system of axioms for indefinite quantum field theory is constructed by solving the analysed equations. The associated random cosurface models are discussed and some e

A. F. Kracklauer

It is observed that the proofs of hidden-variable no-go theorems depend on the `projection postulate,' which is seen to be contradictory with respect to spin operators in directions orthogonal to the magnetic field direction. In this light it is argued that it is less costly to abandon the projection postulate than to abandon locality and this in turn re

Daniel Ferenc

New developments in HPD design are presented, triggered by applications in high energy physics and astrophysics. The presented HPD designs are based on three innovations. (i) In order to achieve the highest possible surface coverage in a RICH detector, we introduced a photoelectron focussing method which is efficient to the periphery of the photocathode. (ii

T. K. Zywietz, J. Neugebauer, M. Scheffler, J. E. Northrup

We have studied the driving forces governing reconstructions on polar GaN surfaces employing first-principles total-energy calculations. Our results reveal properties not observed for other semiconductors, as for example a strong tendency to stabilize Ga-rich surfaces. This mechanism is shown to have important consequences on various surface properties: Nove

Preben Alstrom, Victor M. Eguiluz, Morten Colding-Jorgensen, Finn Gustafsson

A new Rayleigh-type instability is proposed to explain the `sausage-string' pattern of alternating constrictions and dilatations formed in blood vessels under influence of a vasoconstricting agent. Our theory involves the nonlinear elasticity characteristics of the vessel wall, and provides predictions for the conditions under which the cylindrical form

Andrei P. Kirilyuk

The fundamental impasses and ruptures in various domains of the canonical, unitary science, or the 'end of science', become the more and more evident. The natural unity of being is recovered within a universal nonperturbative method leading to the dynamic redundance paradigm. It is shown that the unreduced behaviour of any nontrivial (isolated) syste

Mary Silber, Anne C. Skeldon

Motivated by experimental observations of exotic standing wave patterns in the two-frequency Faraday experiment, we investigate the role of normal form symmetries in the pattern selection problem. With forcing frequency components in ratio m/n, where m and n are co-prime integers, there is the possibility that both harmonic and subharmonic waves may lose sta

M. A. Ivanov, Yu. L. Kalinovsky, P. Maris, C. D. Roberts

Dyson-Schwinger equation (DSE) studies show that the b-quark mass-function is approximately constant, and that this is true to a lesser extent for the c-quark. These observations provide the basis for a study of the leptonic and semileptonic decays of heavy pseudoscalar mesons using a ``heavy-quark'' limit of the DSEs. When exact, this limit reduces

M. Wojcik, S. Drozdz

Based on an explicit verification of the coupling matrix elements between the 1p1h and 2p2h states we propose a new method of selecting the most important 2p2h states responsible for fragmentation effects. In this way the dimensionality of the problem is reduced, such that the computation becomes feasible and the spreading of the strength is realistic, as ve

R. Rapp, J. W. Durso, Z. Aouissat, G. Chanfray

We address the problem of pion production in low energy $π$-nucleus collisions. For the production mechanism we assume a simple model consisting of a coherent sum of single pion exchange and the excitation---followed by the decay into two pions and a nucleon---of the $N^*(1440)$ resonance. The production amplitude is modified by the final state interaction b

Berndt Muller

We discuss the various physics aspects of hypothetical, coherent excitations of the pion field caused by spontaneously generated local distortions of the chiral order parameter. Such distortions, which may occur in the expansion of a hot fireball created in relativistic nuclear collisions, may be influenced or even triggered by the interaction with strong el

TRI collaboration, J. Bisplinghoff, J. Ernst, P. D. Eversheim

A novel test of time-reversal invariance in proton-deuteron scattering is planned as an internal target transmission experiment at the cooler synchrotron COSY. The P-even, T-odd observable is the polarization correlation $A_{y,xz}$ of the total cross section measured using a polarized internal proton beam (polarization $p_y$) and an internal polarized deuter

G. Hunter, P. Ecimovic, I. Schlifer, I. M. Walker

Spherical Harmonics, $Y_\ell^m(θ,ϕ)$, are derived and presented (in a Table) for half-odd-integer values of $\ell$ and $m$. These functions are eigenfunctions of $L^2$ and $L_z$ written as differential operators in the spherical-polar angles, $θ$ and $ϕ$. The Fermion Spherical Harmonics are a new, scalar and angular-coordinate-dependent representation of fer

Jacob Mostovoy

We show that the loop spaces of real projective spaces are topologically approximated by the spaces of rational maps from RP(1) to RP(n). As a byproduct of our constructions we obtain an interpretation of the Kronecker characteristic (degree) of an ornament via particle spaces.

Giovanna Carnovale

We work out a theory of integrability on the braided covector Hopf algebra and braided vector Hopf algebra of type A_n as introduced by Kempf and Majid. Starting by their definition of braided Fourier transform we prove n-dimensional analogues to results by Koornwinder expressing the correspondence between products of q^2-Gaussians times monomials and produc

Christian Kassel, Vladimir Turaev

For any finite-dimensional Lie bialgebra $g$, we construct a bialgebra $A_{u,v}(g)$ over the ring $C[u][[v]]$, which quantizes simultaneously the universal enveloping bialgebra $U({g})$, the bialgebra dual to $U(g^*)$, and the symmetric bialgebra $S(g)$. We call $A_{u,v}(g)$ a biquantization of $S(g)$. We show that the bialgebra $A_{u,v}(g^*)$ quantizing $U(

O. Foda, B. Leclerc, M. Okado, J. -Y. Thibon

Starting from known $q$-analogues of ordinary SU(n) tensor products multiplicities, we introduce $q$-analogues of the fusion coefficients of the WZW conformal field theories associated with SU(n). We conjecture combinatorial interpretations of these polynomials, which can be proved in special cases. This allows us to derive in a simple way various kinds of b

Andre de Gouvea, Alexander Friedland, Hitoshi Murayama

Seiberg duality in supersymmetric gauge theories is the claim that two different theories describe the same physics in the infrared limit. However, one cannot easily work out physical quantities in strongly coupled theories and hence it has been difficult to compare the physics of the electric and magnetic theories. In order to gain more insight into the equ

Matthias R Gaberdiel, Peter Goddard

A new rigorous approach to conformal field theory is presented. The basic objects are families of complex-valued amplitudes, which define a meromorphic conformal field theory (or chiral algebra) and which lead naturally to the definition of topological vector spaces, between which vertex operators act as continuous operators. In fact, in order to develop the

Andrzej Trautman

Odd-dimensional Riemannian spaces that are non-orientable, but have a pin structure, require the consideration of the twisted adjoint representation of the corresponding pin group. It is shown here how the Dirac operator should be modified, also on even-dimensional spaces, to make it equivariant with respect to the action of that group when the twisted adjoi

Seung-Kook Kim, Yong-Wan Kim, Young-Jai Park

We show how to systematically derive the complete set of the gauge transformations of different types of the gauge invariant models, which are the chiral Schwinger and CP$^1$ with Chern-Simons term, in the Lagrangian Formalism.

Csaba Csaki, Hitoshi Murayama

We examine N=1 supersymmetric gauge theories which confine in the presence of a tree-level superpotential. We show the confining spectra which satisfy the 't Hooft anomaly matching conditions and give a simple method to find the confining superpotential. Using this method we fix the confining superpotentials in the simplest cases, and show how these supe

Oliver Haschke, Werner Ruehl

We construct exactly solvable models for four particles moving on a real line or on a circle with translation invariant two- and four-particle interactions.

H. W. Griesshammer

Progress towards a complete velocity power counting in non-relativistic effective field theories, especially NRQCD, is motivated and summarised.

S. Bar-Shalom, G. Eilam

We discuss the prospects - within several models - for the observation of CP-violation (CPV) in top decays and production. The outlook looks best for t -> bW at the LHC (MSSM CPV), t -> b τν_τat TeV3, LHC and NLC (H^+ CPV), p p-bar -> t b-bar + X at TeV3 (MSSM CPV), p p -> t t-bar + X at the LHC (MSSM CPV and neutral Higgs CPV) and for e^+ e^- -> t t-bar h,

R. Barbier, C. Berat, M. Besancon, P. Binetruy

This report summarizes the work of the "R-parity violation group" of the French Research Network (GDR) in Supersymmetry, concerning the physics of supersymmetric models without conservation of R-parity at HERA, LEP, Tevatron and LHC and limits on R-parity violating couplings from various processes. The report includes a discussion of the recent searc

O. L. G. Peres

I summarize here the results of a global fit to the full data set corresponding to 33.0 kt-yr of data of the Super-Kamiokande experiment as well as to all other experiments in order to compare the active-active and active-sterile neutrinos oscillation channels to the atmospheric neutrino anomaly.

M. Axenides, E. Floratos, A. Kehagias

We demonstrate the existence of non-abelian non-topological solitons such as Q-balls in the spectrum of Wess-Zumino models with non-abelian global symmetries. We conveniently name them Q-superballs and identify them for short as Q-sballs. More specifically, we show that in contrast to the non-supersymmetric case, they arise in renormalizable potentials with

Jyh-Liong Lim

WE propose a new unified evolution equation for parton distribution functions appropriate for both large and small Bjorken x. Compared with the Ciafaloni- Catani-Fiorani-Marchesini equation, the cancellation of soft poles between virtual and real gluon emissions is made explicitly without introducing infrared cutoffs, next-to-leading contributions to the Sud

M. Anselmino, M. Boglione, F. Murgia

Single spin asymmetries in polarized proton(antiproton) + proton -> pion + X have been measured to be large. They can be understood within perturbative QCD by introducing new k_perp and spin dependences in fragmentation and/or distribution functions. We discuss first how these effects in distribution functions alone can account for existing data and predict

J. -M. Frère

The investigation of a proposed glueball filter in proton-proton collisions led us to show that its action is in fact easily understood in terms of kinematics. While the procedure proposed stays of interest in reducing background when lookingfor centrally produced resonances of specified spin and parity, we stress that it can be put to advantage in giving ac

M. Anselmino, M. Bertini, F. Murgia, P. Quintairos

As confirmed by some recent LEP data on phi, K^* and D^*0 production, final state interactions in quark fragmentation may give origin to non-zero values of the off-diagonal element rho_{1,-1} of the helicity density matrix of vector mesons produced in e^+ e^- annihilations: we give estimates for rho_{1,-1} of vector mesons with a large x_E and collinear with

Ya. A. Berdnikov, A. N. Ivanov, V. F. Kosmach, N. I. Troitskaya

The proton energy spectrum and the angular distribution of the probability of the $Λ^+_c$ -> p + $K^-$ + $π^+$ decay for the polarized $Λ^+_c$ and the unpolarized proton are calculated in the effective quark model with chiral U(3) X U(3) symmetry incorporating Heavy Quark Effective theory (HQET) and Chiral perturbation theory at the quark level (CHPT)$_q$. T

A. Kirk, the WA102 Collaboration

A study of central meson production as a function of the difference in transverse momentum (dPT) of the exchanged particles shows that undisputed qqbar mesons are suppressed at small dPT whereas the glueball candidates are enhanced. In addition, the production cross section for different resonances depends strongly on the azimuthal angle between the two outg

C. Boros, J. T. Londergan, A. W. Thomas

By comparing structure functions measured in neutrino and charged lepton deep inelastic scattering, one can test the validity of parton charge symmetry. New experiments allow us to make such tests, which set rather tight upper limits on parton charge symmetry violation [CSV] for intermediate Bjorken $x$, but which appear to show sizable CSV effects at small

I. Lazanu, M. Rujoiu

A re-analysis of some $\bar{p}p$ and $\bar{p}n$ data, at rest and in flight, obtained in bubble chamber experiments, is presented. The ($π^{+}π^{-}$) and ($K_{S}K_{S}$) final states for the channels (2$π^{-}π^{+}$) and ($K_{S}K_{S}π$) are investigated. Evidence for a narrow meson resonance structure, cautiously suggested as $f_{0} (1500)$, is given. In the (

L. D. Paniak, G. W. Semenoff

The thermodynamic problem of a gas of static quarks carrying U(N) charges and interacting with each other via U(N) electric gauge fields is formulated and solved in the large N limit. In a lattice theory, the solution can be found in any dimension. In particular, in 1+1-dimensions, the continuum model can also be solved. In that case, and when the quarks are

Jens Erler, Paul Langacker

We review the experimental and theoretical status of the standard electroweak theory, and its fundamental parameters. We obtain the global best fit result for the Standard Model Higgs boson of M_H = 107^{+67}_{-45} GeV, and find the 95% upper limit of 255 GeV. Parameters describing physics beyond the Standard Model are discussed as well. Particular emphasis

R. C. Brower, D. Chen, J. Negele, K. Orginos

We study the Abelian projection of an instanton in $R^3 \times S^1$ as a function of temperature (T) and non-trivial holonomic twist ($ω$) of the Polyakov loop at infinity. These parameters interpolate between the circular monopole loop solution at T=0 and the static 't Hooft-Polyakov monopole/anti-monopole pair at high temperature.

M. Faber, J. Greensite, S. Olejnik

We consider projections of SU(2) lattice link variables onto Z(2) center and U(1) subgroups, with and without gauge-fixing. It is shown that in the absence of gauge-fixing, and up to an additive constant, the static quark potential extracted from projected variables agrees exactly with the static quark potential taken from the full link variables; this is an

M. Goeckeler, R. Horsley, V. Linke, D. Pleiter

We present first results for light hadron masses, quark masses and decay constants in the continuum limit using O(a) improved fermions at three different values of the gauge coupling β.

F. Ronga

A measurement of the flux of neutrino-induced muons using the MACRO detector is presented. Different event topologies, corresponding to different neutrino parent energies can be detected. The upward throughgoing muon sample is the larger event sample. The observed upward-throughgoing muons are 26% fewer than expected and the zenith angle distribution does no

H. N. Núñez-Yépez

We study the dynamical effects in the scale factors due to the scalar $ϕ$-field at the early stages of a supposedly anisotropic Universe expansion in connection with the problem of the initial singularity in the scalar-tensor cosmology of Jordan-Brans-Dicke. This is done by considering the behaviour of the general analytical solutions for the homogeneous mod

Victor M. Zhuravlev, Serguey V. Chervon, Dmitriy Yu. Shabalkin

An effective chiral model of a plane-symmetric gravitational field is considered. Isometries of the target space of the model are described and exact solutions corresponding to the isometric ansatz method are obtained. New exact solutions are found using the method of functional parameters. The solutions obtained are Bäcklund transforms of solutions of the d

Sean A. Hayward, Shinji Mukohyama, M. C. Ashworth

We consider two non-statistical definitions of entropy for dynamic (non-stationary) black holes in spherical symmetry. The first is analogous to the original Clausius definition of thermodynamic entropy: there is a first law containing an energy-supply term which equals surface gravity times a total differential. The second is Wald's Noether-charge metho

Andreas Siebert

This paper presents a multiscale decomposition algorithm. Unlike standard wavelet transforms, the proposed operator is both linear and shift invariant. The central idea is to obtain shift invariance by averaging the aligned wavelet transform projections over all circular shifts of the signal. It is shown how the same transform can be obtained by a linear fil

Lex Weaver, Chris Johnson

A distributed heap storage manager has been implemented on the Fujitsu AP1000 multicomputer. The performance of various pre-fetching strategies is experimentally compared. Subjective programming benefits and objective performance benefits of up to 10% in pre-fetching are found for certain applications, but not for all. The performance benefits of pre-fetchin

J. S. Sa' Martins, P. M. C. de Oliveira

We present a dynamical and dissipative lattice model, designed to mimic nuclear multifragmentation. Monte-Carlo simulations with this model show clear signature of critical behaviour and reproduce experimentally observed correlations. In particular, using techniques devised for finite systems, we could obtain two of its critical exponents, whose values are i

Lev P. Gor`kov

For the vortex lattice in an anisotropic superconductor with well-separated cores (Hc1<<B<<Hc2) it is shown that sizable de Haas-van Alphen oscillations are caused by the levels` crossing of the energy threshold separating localized and extended states of excitations moving in the average magnetic field,B.

Jose D. Munoz, Hans J. Herrmann

We propose a way of implementing the Broad Histogram Monte Carlo method to systems with continuous degrees of freedom, and we apply these ideas to investigate the three-dimensional XY-model with periodic boundary conditions. We have found an excellent agreement between our method and traditional Metropolis results for the energy, the magnetization, the speci

Matthias J. Graf

We investigate the electronic transport coefficients in unconventional superconductors at low temperatures, where charge and heat transport are dominated by electron scattering from random lattice defects. We discuss the features of the pairing symmetry, Fermi surface, and excitation spectrum which are reflected in the low temperature heat transport. For tem

Zoltan Csahok, Tamas Vicsek

A simple self-driven lattice-gas model for collective biological motion is introduced. We find weakly first order phase transition from individual random walks to collective migration. A mean-field theory is presented to support the numerical results.

Christoph Bennemann, Wolfgang Paul, J&#34;org Baschnagel, Kurt Binder

We present results from Molecular Dynamics simulations of the thermal glass transition in a dense polymer melt. In previous work we compared the simulation data with the idealized version of mode coupling theory (MCT) and found that the theory provides a good description of the dynamics above the critical temperature. In order to investigate the influence of

Francesco Ancilotto, Philippe Blandin, Flavio Toigo

We have studied the fragmentation of Li11+ clusters into the two experimentally observed products (Li9+,Li2) and (Li10+,Li) The ground state structures for the two fragmentation channels are found by Molecular Dynamics Simulated Annealing in the framework of Local Density Functional theory. Energetics considerations suggest that the fragmentation process is

Jian-Sheng Wang

We show explicitly that the broad histogram single-spin-flip random walk dynamics does not give correct microcanonical average even in one dimension. The dynamics violates detailed balance condition by an amount which decreases with system size. As a result, in distribution different configurations with the same energy can have different probabilities. We pr

Luis G. C. Rego, George Kirczenow

We introduce a generalized approach to one-dimensional (1D) conduction based on Haldane&#39;s concept of fractional statistics (FES) and the Landauer formulation of transport theory. We show that the 1D ballistic thermal conductance is independent of the statistics obeyed by the carriers and is governed by the universal quantum $ (π^2 k^2_B T)/(3h) $ in the

A. Mourachkine

The paper has been withdrawn by the author because the observed effect has a different origin.

C. Chandre, H. R. Jauslin

We review a formulation of a renormalization-group scheme for Hamiltonian systems with two degrees of freedom. We discuss the renormalization flow on the basis of the continued fraction expansion of the frequency. The goal of this approach is to understand universal scaling behavior of critical invariant tori.

H. Aussel, C. J. Cesarsky, D. Elbaz, J. -L. Starck

We have developed a new ISOCAM data reduction technique based on wavelet analysis, especially designed for the detection of faint sources in mid-infrared surveys. This method, the Pattern REcognition Technique for Isocam data (PRETI) has been used to reduce the observations of the Hubble Deep Field (HDF) and flanking fields with ISOCAM at 6.75 (LW2) and 15 m

C. W. Lee, H. M. Lee, H. B. Ann, K. H. Kwon

We have performed Smoothed Particle Hydrodynamic (SPH) simulations to study the response of molecular clouds in the Galactic disk to a rotating bar and their subsequent evolution in the Galactic Center (GC) region. The Galactic potential in our models is contributed by three axisymmetric components (massive halo, exponential disk, compact bulge) and a non-ax

L. D. Matthews, W. van Driel, J. S. Gallagher

This paper explores the adherence of 47 extreme late-type galaxies to the B- and V-band Tully-Fisher relations defined by a sample of local calibrators. In both bands we find the mean luminosity at a given line width for extreme late-type spirals to lie below that predicted by standard Tully-Fisher relations. While many of the extreme late-type spirals do fo

X. Barcons, R. Carballo, M. T. Ceballos, R. S. Warwick

We have discovered an obscured active galaxy at redshift z = 1.246 identified with the ROSAT X-ray source RX J1011.2+5545. We report on multiwavelength observations of this source and discuss its X-ray, optical and radio properties. This is the first X-ray selected, obscured active galaxy at high redshift to be shown to be radio-loud, with a radio counterpar

R. M. Kippen, K. Hurley, G. N. Pendleton

We investigate the angular distribution of gamma-ray bursts using the largest catalog of well-localized events that is currently available---combined BATSE/Ulysses burst locations. We present the preliminary spatial analysis of 415 BATSE/Ulysses bursts included in the BATSE 4B catalog. We find that the locations are consistent with large- and small-scale iso

Peter B. Stetson

Charge-transfer effects in photometry with Wide Field Planetary Camera 2 aboard the Hubble Space Telescope are investigated by a comparison of WFPC2 observations with groundbased photometry for the Galactic globular clusters omega Centauri and NGC 2419. Simple numerical formulae describing the fraction of lost signal as functions of position on the detector,

P. Goldreich, Y. Wu

We investigate dynamical interactions between turbulent convection and g-mode pulsations in ZZ Ceti variables (DAVs). Since our understanding of turbulence is rudimentary, we are compelled to settle for order of magnitude results. A key feature of these interactions is that convective response times are much shorter than pulsation periods. Thus the dynamical

Matthew J. Graham, Roger G. Clowes, Luis E. Campusano

We apply a simple statistical method (Derenzo & Hildebrand 1969) to estimating the completeness of quasar surveys. It requires that an area has been covered by two or more, preferably different, selection techniques. We use three suitable data sets with separate selections from: variability and UV-excess (170 quasars); objective prism and UV-excess (141 quas

R. Mignani

Only 1% of the Isolated Neutron Star (INS) population has been identified in the optical, albeit with different degrees of confidence. Optical observations of INSs are reviewed and their emission properties discussed in an evolutionary framework.

Mario Livio

The existing disk instability model for dwarf nova eruptions is reviewed, in the light of recent progress in the understanding of angular momentum transport in accretion disks. It is proposed that the standard lower branch in the ``S-curve&#39;&#39; in the effective temperature-surface density plane may not exist. Rather, angular momentum transport may be su

H. Krüger, E. Grün, A. Graps, A. Heck

We report on dust measurements obtained during the seventh orbit of the Galileo spacecraft about Jupiter. %which had a close flyby at Ganymede. The most prominent features observed are highly time variable dust streams recorded throughout the Jovian system. The impact rate varied by more than an order of magnitude with a 5 and 10 hour periodicity, which show

Stefanie Komossa, Hartmut Schulz

We present a spectral and spatial analysis of the nuclear and circumnuclear X-ray emission of the prominent southern starburst/Seyfert galaxy NGC 1365. To describe the X-ray spectrum of the core source, we favour a two-component model consisting of about equally strong contributions from a Raymond-Smith plasma (with ~cosmic abundances) and a powerlaw. The or

Guinevere Kauffmann, Stephane Charlot

In hierarchical models of galaxy formation, ellipticals form from the merging of disk galaxies drawn together by gravity as their surrounding dark halos coalesce. Using semi-analytic techniques, we are able to follow the merging, star formation and chemical enrichment histories of galaxies for a given choice of cosmological parameters. We calculate the ages

S. F. Sanchez, J. I. Gonzalez-Serrano

Deep $B$ and $R$ band images (R<24 and B<25) have been obtained of a field of $\sim 6 \times 6$ arcmin around seven radio-loud quasars with $1<z<1.6$. A statistically significant excess of faint ($22.5<B\le 23.5$ and $22<R\le 23.0$) galaxies was found, on scales of $r < 160&#39;&#39;$ around the quasars ($>3σ_{N{exp}}$). The galaxies have magnitudes compatib

M. Gliozzi, G. Bodo, G. Ghisellini

We calculate the minimum value of the power in kinetic bulk motion of the galactic superluminal source GRS 1915+105. This value far exceeds the Eddington luminosity for accretion onto a black hole of 10 solar masses. This large value severely limits the possible carriers of the kinetic luminosity at the base of the jet, and favours a jet production and accel

Roberto Soria

We conducted spectroscopic and photometric observations of the optical counterpart of the X-ray transient RX J0117.6-7330 in the Small Magellanic Cloud, during a quiescent state. The primary star is identified as a B0.5 IIIe, with mass M = (18 +/- 2) M(sun) and bolometric magnitude M(bol) = -7.4 +/- 0.2. The main spectral features are strong H-alpha emission

J. Papaloizou, C. Terquem, R. Nelson

The formation, structure and evolution of protoplanetary discs is considered. The formation of giant planets within the environment of these models is also discussed.

D. R. Garnett, G. A. Shields, M. Peimbert, S. Torres-Peimbert

We present measurements of the gas-phase C/O abundance ratio in six H II regions in the spiral galaxies M101 and NGC 2403, based on ultraviolet spectroscopy using the Faint Object Spectrograph on the Hubble Space Telescope. The C/O ratios increase systematically with O/H in both galaxies, from log C/O approximately -0.8 at log O/H = -4.0 to log C/O approx. -

O. G. Balev, P. Vasilopoulos

A {\it microscopic} treatment of fundamental edge magnetoplasmons (EMPs) along the edge of a double quantum well (DQW) is presented for strong magnetic fields, low temperatures, and total filling factor ν=2. It is valid for lateral confining potentials that Landau level (LL) flattening can be neglected. The cyclotron and Zeeman energies are assumed larger th

C. Wexler, Alan T. Dorsey

We present a study of the excitations of the edge of a two-dimensional electron droplet in a magnetic field in terms of a contour dynamics formalism. We find that, beyond the usual linear approximation, the non-linear analysis yields soliton solutions which correspond to uniformly rotating shapes. These modes are found from a perturbative treatment of a non-

Erich Poppitz

We consider the generation of Fayet-Iliopoulos terms at one string loop in some recently found N=1 open string orbifolds with anomalous U(1) factors with nonvanishing trace of the charge. Low-energy field theory arguments lead one to expect a one loop quadratically divergent Fayet-Iliopoulos term. We show that a one loop Fayet-Iliopoulos term is not generate

Vittorio Del Duca, Carl R. Schmidt

We compute the virtual next-to-leading corrections to the Lipatov vertex in the helicity-amplitude formalism. These agree with previous results by Fadin and collaborators, in the conventional dimensional-regularization scheme. We discuss the choice of reggeization scale in order to minimize its impact on the next-to-leading-logarithmic corrections to the BFK

Burak Ozbagci, András I. Stipsicz

We construct noncomplex smooth 4-manifolds which admit genus-2 Lefschetz fibrations over S^2. The fibrations are necessarily hyperelliptic, and the resulting 4-manifolds are not even homotopy equivalent to complex surfaces. Furthermore, these examples show that fiber sums of holomorphic Lefschetz fibrations do not necessarily admit complex structures.

Y. Ashkenazy, M. Lewkowicz, J. Levitan, S. Havlin

Multiresolution Wavelet Transform and Detrended Fluctuation Analysis have been recently proven as excellent methods in the analysis of Heart Rate Variability, and in distinguishing between healthy subjects and patients with various dysfunctions of the cardiac nervous system. We argue that it is possible to obtain a distinction between healthy subjects/patien