January 2000 arXiv papers — page 4

A. V. Petukhov, D. Passerone, F. Ercolessi, E. Tosatti

Off-lattice Grand Canonical Monte Carlo simulations of the clean diamond (111) surface, based on the effective many-body Brenner potential, yield the $(2\times1)$ Pandey reconstruction in agreement with \emph{ab-initio} calculations and predict the existence of new meta-stable states, very near in energy, with all surface atoms in three-fold graphite-like bo

Nino Panagia, Martino Romaniello, Salvatore Scuderi, Robert P. Kirshner

We present the results of a study of the stellar population in a region of 30 pc radius around SN1987A, based on an analysis of multi-band HST-WFPC2 images. The effective temperature, radius and, possibly, reddening of each star were determined for 21,955 stars by fitting the measured broad band magnitudes to the ones calculated with model atmospheres. In ad

Ulf Leonhardt

Light experiences dielectric matter as an effective gravitational field and matter experiences light as a form of gravity as well. Light and matter waves see each other as dual space-time metrics, thus establishing a unique model in field theory. Actio et reactio are governed by Abraham's energy-momentum tensor and equations of state for quantum dielectr

F. D. M. Haldane, E H. Rezayi, Kun Yang

We report on results of systematic numerical studies of two-dimensional electron gas systems subject to a perpendicular magnetic field, with a high Landau level partially filled by electrons. Our results are strongly suggestive of a breakdown of translational symmetry and the presence of crystalline order in the ground state. This is in sharp contrast with t

Takayoshi Ohshima

A new concept concerning Cherenkov detector for particle identification by means of measuring both the Time-of-Propagation (TOP) and horizontal emission angle ($Φ$) of Cherenkov photons is described here. Some R&D works are also reported.

Wen-Li Yang, Yao-Zhong Zhang

We study the level-one irreducible highest weight representations of the quantum affine superalgebra $U_q[\hat{sl(N|1)}]$, and calculate their characters and supercharacters. We obtain bosonized q-vertex operators acting on the irreducible $U_q[\hat{sl(N|1)}]$-modules and derive the exchange relations satisfied by the vertex operators. We give the bosonizati

H. C. Rosu

Within unbroken SUSYQM and for zero factorization energy, I present an iterative generalization of Mielnik's isospectral method by employing a Schroedinger true zero mode in the first-step general Riccati solution and imposing the physical condition of normalization at each iterative step. This procedure leads to a well-defined multiple-parameter structu

D. M. Appleby

It is shown that the series derived by Mizrahi, giving the Husimi transform (or covariant symbol) of an operator product, is absolutely convergent for a large class of operators. In particular, the generalized Liouville equation, describing the time evolution of the Husimi function, is absolutely convergent for a large class of Hamiltonians. By contrast, the

S. F. Huelga, M. B. Plenio

Stochastic resonance shows that under some circumstances noise can enhance the response of a system to a periodic force. While this effect has been extensively investigated theoretically and demonstrated experimentally in classical systems, there is complete lack of experimental evidence within the purely quantum mechanical domain. Here we demonstrate that s

C. Jung, F. Leyvraz, T. H. Seligman

We use a factorization technique and representation of canonical transformations to construct globally valid closed form expressions without singularities of semi-classical wave functions for arbitrary smooth potentials over a one-dimensional position space.

Josiph Mladenov Rangelov

The object of this paper is to discuss the physical interpretation of quantum behaviour of Schrodinger electron (SchEl) and bring to light on the cause for the Heisenberg convenient operator way of its describing, using the nonrelativistic quantum mechanics laws and its mathematical results. We describe the forced stochastically diverse circular oscillation

Sergey Kurennoy

A general derivation of the beam coupling impedances produced by small discontinuities on the wall of the vacuum chamber of an accelerator is reviewed. A collection of analytical formulas for the impedances of small obstacles is presented.

C. Volpe, N. Auerbach, G. Colø, T. Suzuki

In view of the recent experiments on neutrino oscillations performed by the LSND and KARMEN collaborations as well as of future experiments, we present new theoretical results of the flux averaged $^{12}C(ν_e,e^-)^{12}N$ and $^{12}C(ν_μ,μ^-)^{12}N$ cross sections. The approaches used are charge-exchange RPA, charge-exchange RPA among quasi-particles (QRPA) a

V. K. Magas, Cs. Anderlik, L. P. Csernai, F. Grassi

Freeze-out of particles across 3-dimensional space-time hypersurface with space-like normal is discussed in a simple kinetic model. The final momentum distribution of emitted particles shows a non-exponential transverse momentum spectrum, which is in quantitative agreement with recently measured SPS pion and $h^-$ spectra.

W. Cassing

We briefly review the dilepton experiments at BEVALAC/SIS and SPS energies for p+p, p+A and A+A collisions as well as our present understanding of the data within transport theoretical simulations. Since dileptons from p+A and A+A collisions in particular probe the in-medium spectral functions of vector mesons, a novel semiclassical off-shell transport appro

Sanjay K. Ghosh, Byron Jennings

Possible formation of $ρ$ nucleus bound state is studied in the framework of Walecka model. The bound states are found in different nuclei ranging from $^3He$ to $^{208}Pb$. These bound states may have a direct bearing on the recent experiments on the photoproduction of $ρ$ meson in the nuclear medium.

Ashwin Pande, Sitabhra Sinha, Rahul Pandit

We give a brief overview of systems that show spiral patterns and spatiotemporally chaotic states. We concentrate on two physical systems: (1) the oxidation of CO on Pt(110) and (2) ventricular fibrillation in hearts. The equations that have been suggested as simple models for these two different systems are closely related for they are both {\it excitable m

Paul B. Umbanhowar, Harry L. Swinney

Laboratory experiments are conducted to examine granular wave patterns near onset as a function of the container oscillation frequency f and amplitude A, layer depth H, and grain diameter D. The primary transition from a flat grain layer to standing waves occurs when the layer remains dilated after making contact with the container. With a flat layer and inc

Shunichi Tsuge

As contrast to the Maxwellian distribution, equilibrium distribution of the second kind or turbulent equilibrium is shown to exist under tertiary molecular chaos hypothesis to replace the classical binary chaos by Boltzmann. It is expressed as bimodal Maxwellians each mode differing by plus/minus root-mean-squares of fluctuations in macroscopic variables. Ch

M. Boiti, J-G. Caputo, J. Leon, F. Pempinelli

We report the observation of Raman solitons on numerical simulations of transient stimulated Raman scattering (TSRS) with small group velocity dispersion. The theory proceeds with the inverse scattering transform (IST) for initial-boundary value problems and it is shown that the explicit theoretical solution obtained by IST for a semi-infinite medium fits st

David Eisenbud, Mircea Mustata, Mike Stillman

We study the local cohomology modules H^i_B(R) for a reduced monomial ideal B in a polynomial ring R=k[X_1,...,X_n]. We consider a grading on R which is coarser than the Z^n-grading such that each component of H^i_B(R) is finite dimensional and we give an effective way to compute these components. Using Cox's description for sheaves on toric varieties, w

Thomas Friedrich

The aim of this short note is to announce the existence of a one-parameter family of left-invariant metrics on $S^3$ admitting WK-spinors. This family contains the two non-Einstein Sasakian metrics with WK-spinors on $S^3$, but does not contain the standard sphere $S^3$ with Killing spinors. Moreover, any simply-connected, complete Riemannian manifold $X^3 \

Michel Waldschmidt

We first propose two conjectural estimates on Diophantine approximation of logarithms of algebraic numbers. Next we discuss the state of the art and we give further partial results on this topic.

Maxim Kontsevich, Yan Soibelman

In present paper we develop the deformation theory of operads and algebras over operads. Free resolutions (constructed via Boardman-Vogt approach) are used in order to describe formal moduli spaces of deformations. We apply the general theory to the proof of Deligne's conjecture. The latter says that the Hochschild complex of an associative algebra carri

Patricio Gaete

In order to eliminate gauge variant degrees of freedom we study the way to introduce gauge invariant fields in pure non-Abelian Yang-Mills theory. Our approach is based on the use of the gauge-invariant but path-dependent variables formalism. It is shown that for a special class of paths these fields coincide with the usual ones in some definite gauges. The

E. Papantonopoulos, I. Pappa

We consider a three-dimensional brane-universe moving in a Type 0 String background. The motion induces on the brane a cosmological evolution which, for some range of the parameters, exhibits an inflationary phase.

Harald Grosse, Thomas Krajewski, Raimar Wulkenhaar

We prove by explicit calculation that Feynman graphs in noncommutative Yang-Mills theory made of repeated insertions into itself of arbitrarily many one-loop ghost propagator corrections are renormalizable by local counterterms. This provides a strong support for the renormalizability conjecture of that model.

R. Manvelyan, H. J. W. Mueller-Kirsten, J. -Q. Liang, Yunbo Zhang

It has recently been shown that the equation of motion of a massless scalar field in the background of some specific p branes can be reduced to a modified Mathieu equation. In the following the absorption rate of the scalar by a D3 brane in ten dimensions is calculated in terms of modified Mathieu functions of the first kind, using standard Mathieu coefficie

J. Ambjorn, J. Jurkiewicz, R. Loll

We review some recent attempts to extract information about the nature of quantum gravity, with and without matter, by quantum field theoretical methods. More specifically, we work within a covariant lattice approach where the individual space-time geometries are constructed from fundamental simplicial building blocks, and the path integral over geometries i

V. Ch. Zhukovsky, N. A. Peskov

The massive SU(2) gauge field theory coupled with fermions is considered in 2+1 dimensions. Quark energy spectrum and radiative shift in constant external nonabelian field, being exact solution of the gauge field equations with the Chern-Simons term, are calculated. Under the condition $m = θ/4$ the quark state is shown to be supersymmetric.

Oleg Lebedev, Will Loinaz, Tatsu Takeuchi

We analyze the one loop corrections to hadronic Z decays in an R-parity violating extension to the Minimal Supersymmetric Standard Model (MSSM). Performing a global fit to all the hadronic observables at the Z-peak, we obtain stringent constraints on the R-violating couplings constants lambda' and lambda''. As a result of the strong constraints f

Michael J. Longo

There have been many suggestions that there are extra spatial dimensions "outside" of our normal (3+1)-dimensional space. Generally it is assumed that electromagnetic and hadronic fields are restricted to the normal dimensions, while gravity can extend into the extra dimensions. Thus a hadron or lepton is confined in a potential well, and excited sta

A. H. Hoang, M. Beneke, K. Melnikov, T. Nagano

Using non-relativistic effective theories, new next-to-next-to-leading order (NNLO) QCD corrections to the total $t\bar t$ production cross section at the Linear Collider have been calculated recently. In this article the NNLO calculations of several groups are compared and the remaining uncertainties are discussed. The theoretical prospects for an accurate

N. Borghini, W. N. Cottingham, R. Vinh Mau

We study the quark-hadron phase transition within an effective model of QCD, and find that in a reasonable range of the main parameters of the model, bodies with quark content between $10^{-2}$ and 10 solar masses can have been formed in the early universe. In addition, we show that a significant amount of entropy is released during the transition. This may

S. F. Novaes

We present a primer on the Standard Model of the electroweak interaction. Emphasis is given to the historical aspects of the theory's formulation. The radiative corrections to the Standard Model are presented and its predictions for the electroweak parameters are compared with the precise experimental data obtained at the Z pole. Finally, we make some re

Serge B. Afanas'ev

The quantum Dirac-like equation and the QED vertex operator for a composite particle are suggested. The vertex operator and the fermionic propagator are connected by the QED Ward identity. It is shown that all of the Feynman QED-integrals for a three-component particle are finite with some suggestion about large momentum dependence of the vertex operator. Th

Barry R. Holstein

A brief introduction to the subject of chiral perturbation theory ($χ$pt) is given, including a discussion of effective field theory and application to the upcoming Bates virtual Compton scattering measurement.

M. Pentia

The low-energy QCD predictions to be tested by the DIRAC experiment are revised. The experimental method, the setup characteristics and capabilities, along with first experimental results are reported. Preliminary analysis shows good detector performance: alignment error via $Λ$ mass measurement $m_Λ= 1115.6 MeV/c^2$ with $σ= 0.92 MeV/c^2$, $p π^-$ relative

N. Arteaga-Romero, C. Carimalo, V. G. Serbo

This paper deals with the production of orthodimuonium (OM) ($μ^{+} μ^{-}$ atom in triplet state) in collisions of high-energy electrons with nuclei or atoms. This reaction was previously studied by Holvik and Olsen [Phys. Rev. D 35, 2124 (1987)] on the basis of a bremsstrahlung mechanism where OM is produced by only one virtual photon. In the present paper

Miroslav Pardy

The power spectrum formula of the synchrotron radiation generated by the electron and positron moving at the opposite angular velocities in homogenous magnetic field is derived in the Schwinger version of quantum field theory. The asymptotical form of this formula is found. It is surprising that the spectrum depends periodically on radiation frequency omega

K. R. Nasriddinov, B. N. Kuranov, U. A. Khalikov, T. A. Merkulova

The τ\to (a_1 h)^- ν_τ decays of the τ-lepton are studied using the method of phenomenological chiral Lagrangians. The expression of weak hadronic currents between pseudoscalar and axial-vector meson states is obtained. Calculated partial widths for these decays are compared with the available experimental data.

Ikuo Ichinose, Keiichi Nagao

In the previous paper we developed a strong-coupling expansion for the lattice QCD with the overlap fermions and showed that Lüsher's "extended" chiral symmetry is spontaneously broken in some parameter region of the overlap fermions. In this paper, we obtain a low-energy effective action and show that there exist quasi-Nambu-Goldsone bosons whic

Max Klein

Latest results on structure functions, as available at the Lepton-Photon Symposium 1999, are presented. This report focusses on three experimental areas: new structure function measurements, in particular from HERA at low x and high Q2; results on light and heavy flavour densities; determinations of the gluon distribution and of alpha_s. As the talk was deli

F. Ronga

The results of experiments on atmospheric neutrinos are summarized, with the important exception of Superkamiokande. The main emphasis is given to the Soudan-2 and MACRO experiments. Both experiments observe atmospheric neutrino anomalies in agreement with nu_mu-->> nu_tau oscillations with maximum mixing. The nu_mu-->> nu_sterile oscillation is disfavored b

Takahiro Tanaka, Hideyuki Tagoshi

We discuss a method to analyze data from interferometric gravitational wave detectors focusing on the technique of hierarchical search to detect gravitational waves from inspiraling binaries. For this purpose, we propose new coordinates to parameterize the template space. Using our new coordinates, we develop several new techniques for two step search, which

Yuri N. Obukhov

We consider the classical theory of the Dirac massive particle in the Riemann-Cartan spacetime. We demonstrate that the translational and the Lorentz gravitational moments, obtained by means of the Gordon type decompositions of the canonical energy-momentum and spin currents, are consistently coupled to torsion and curvature, as expected.

Chiang-Mei Chen, James M. Nester

The various roles of boundary terms in the gravitational Lagrangian and Hamiltonian are explored. A symplectic Hamiltonian-boundary-term approach is ideally suited for a large class of quasilocal energy-momentum expressions for general relativity. This approach provides a physical interpretation for many of the well-known gravitational energy-momentum expres

Reinaldo J. Gleiser, Manuel H. Tiglio

We derive the general exact vacuum metrics associated with a stationary (non static), non rotating, cylindrically symmetric source. An analysis of the geometry described by these vacuum metrics shows that they contain a subfamily of metrics that, although admitting a consistent time orientation, display "exotic" properties, such as "trapping"

Manuel H. Tiglio

By noticing that, in open 2+1 gravity, polarized surfaces cannot converge in the presence of timelike total energy momentum (except for a rotation of 2 pi), we give a simple argument which shows that, quite generally, closed timelike curves cannot exist in the presence of such energy condition.

Wentao T. Lu, F. Y. Wu

The density of the Fisher zeroes, or zeroes of the partition function in the complex temperature plane, is determined for the Ising model in zero field as well as in a pure imaginary field i Pi/2. Results are given for the simple-quartic, triangular, honeycomb, and the kagome lattices. It is found that the density diverges logarithmically at points along its

W. -J. Tzeng, F. Y. Wu

We consider the problem of enumerating spanning trees on lattices. Closed-form expressions are obtained for the spanning tree generating function for a hypercubic lattice of size N_1 x N_2 x...x N_d in d dimensions under free, periodic, and a combination of free and periodic boundary conditions. Results are also obtained for a simple quartic net embedded on

Norman Biggs, Robert Shrock

We present exact calculations of the zero-temperature partition function for the q-state Potts antiferromagnet (equivalently, the chromatic polynomial) for two families of arbitrarily long strip graphs of the square lattice with periodic boundary conditions in the transverse direction and (i) periodic (ii) twisted periodic boundary conditions in the longitud

Luca Marinelli, B. I. Halperin, S. H. Simon

The quasiparticle spectrum of a two-dimensional d-wave superconductor in the mixed state, H_{c1} << H << H_{c2}, is studied both analytically and numerically using the linearized Bogoliubov-de Gennes equation. We consider various values of the &#34;anisotropy ratio&#34; v_F/v_Delta for the quasiparticle velocities at the Dirac points, and we examine the impl

M. Biehl, R. Kuehn, I. -O. Stamatescu

We show that a straightforward extension of a simple learning model based on the Hebb rule, the previously introduced Association-Reinforcement-Hebb-Rule, can cope with &#34;delayed&#34;, unspecific reinforcement also in the case of structured data and lead to perfect generalization.

M. J. Calderon, L. Brey

We perform Monte Carlo simulations to obtain quantitative results for the anomalous Hall resistance, R_A, observed in colossal magnetoresistance manganites. R_A arises from the interaction between the spin magnetization and topological defects via spin-orbit coupling. We study these defects and how they are affected by the spin-orbit coupling within the fram

G. Mihaly, I. Kezsmarki, F. Zamborszky, L. Forro

Long missing basic experiments in the normal phase of the anisotropic electron system of TMTSF2PF6 were performed. Both the Hall effect and the ab&#39;-plane conduction anisotropy are directly addressing the unconventional electrical properties of this Bechgaard salt. We found that the dramatic reduction of the carrier density deduced from recent optical dat

Miroslav Kotrla, Joachim Krug, Pavel Smilauer

The effect of impurities on epitaxial growth in the submonolayer regime is studied using kinetic Monte Carlo simulations of a two-species solid-on-solid growth model. Both species are mobile, and attractive interactions among adatoms and between adatoms and impurities are incorporated. Impurities can be codeposited with the growing material or predeposited p

N. M. Plakida, V. S. Oudovenko

A microscopical theory of electronic spectrum and superconductivity is formulated within the two-dimensional anisotropic t-J model with t_{x}\neq t_{y} and J_{x}\neq J_{y}. Renormalization of electronic spectrum and superconductivity mediated by spin-fluctuations are investigated within the Eliashberg equation in the weak coupling approximation. The gap func

J. Richter, C. Waidacher, K. W. Becker

We present the first calculation of the electron-energy loss spectrum of infinite one-dimensional undoped CuO_3 chains within a multi-band Hubbard model. The results show good agreement with experimental spectra of Sr_2CuO_3. The main feature in the spectra is found to be due to the formation of Zhang-Rice singlet-like excitations. The q-dependence of these

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

The instabilities induced on a two-dimensional system of correlated electrons by the anisotropies of its Fermi line are analyzed on general grounds. Simple scaling arguments allow to predict the opening of a superconducting gap with a well-defined symmetry prescribed by the geometry of the Fermi line. The same arguments predict a critical dimension of 3/2 fo

W. Westerburg, D. Reisinger, G. Jakob

By pulsed-laser deposition epitaxial thin films of Sr_2FeMoO_6 have been pre- pared on (100) SrTiO_3 substrates. Already for a deposition temperature of 320 C epitaxial growth is achieved. Depending on deposition parameters the films show metallic or semiconducting behavior. At high (low) deposition temperature the Fe,Mo sublattice has a rock-salt (random) s

S. A. Crooker, E. Johnston-Halperin, D. D. Awschalom, R. Knobel

Low-temperature magneto-photoluminescence studies of negatively charged excitons (X- trions) are reported for n-type modulation-doped ZnSe/Zn(Cd,Mn)Se quantum wells over a wide range of Fermi energy and spin-splitting. The magnetic composition is chosen such that these magnetic two-dimensional electron gases (2DEGs) are highly spin-polarized even at low magn

Heather L. Morrison, Mario Mateo, Edward W. Olszewski, Paul Harding

We describe a major survey of the Milky Way halo designed to test for kinematic substructure caused by destruction of accreted satellites. We use the Washington photometric system to identify halo stars efficiently for spectroscopic followup. Tracers include halo giants (detectable out to more than 100 kpc), blue horizontal branch stars, halo stars near the

Cheongho Han

Due to the choice of very dense star fields for a higher event rate, the current microlensing searches suffer from large uncertainties caused by blending effect. To measure light variations of microlensing events free from the effect of blending, a newly developed method of Differential Image Analysis (DIA) was proposed for microlensing searches. However, ev

Cheongho Han, Ho-Il Kim, Kyungae Chang, Seong-Hong Park

Recently, Heyrovský & Sasselov (1999) investigated the sensitivity of {\it single-lens} gravitational microlensing event light curves to small spots and found that during source transit events spots can cause deviations in amplification larger than 2%, and thus be detectable. In this paper, we explore the feasibility of spot detection from the observations o

Belinda J. Wilkes, Eric J. Hooper, Kim K. McLeod, Martin S. Elvis

The NASA/ISO Key Project on active galactic nuclei (AGN) seeks to better understand the broad-band spectral energy distributions (SEDs) of these sources from radio to X-rays, with particular emphasis on infrared properties. The ISO sample includes a wide variety of AGN types and spans a large redshift range. Two subsamples are considered herein: 8 high-redsh

W. Raphael Hix, Michael S. Smith, Anthony Mezzacappa, Sumner Starrfield

The observable consequences of a nova outburst depend sensitively on the details of the thermonuclear runaway which initiates the outburst. One of the more important sources of uncertainty is the nuclear reaction data used as input for the evolutionary calculations. A recent paper by Starrfield, Truran, Wiescher, & Sparks (1998) has demonstrated that changes

M. L. McConnell, K. Bennett, H. Bloemen, W. Collmar

In previous work, we have used data from the first three years of the CGRO mission to assemble a broad-band $γ$-ray spectrum of the galactic black hole candidate Cygnus X-1. Contemporaneous data from the COMPTEL, OSSE and BATSE experiments on CGRO were selected on the basis of the hard X-ray flux (45--140 keV) as measured by BATSE. This provided a spectrum o

Nikos Prantzos

Spiral galaxies offer a unique opportunity to study the role of star formation in galaxy evolution and to test various theoretical star formation schemes. I review some recent relevant work on the evolution of spiral galaxies. Detailed models are used for the chemical and spectrophotometric evolution, with metallicity dependent stellar yields, tracks and spe

J. Boger, R. L. Hahn, J. B. Cumming

It has been suggested by various authors that a significant anticorrelation exists between the Homestake solar neutrino data and the sunspot cycle. Some of these claims rest on smoothing the data by taking running averages, a method that has recently undergone criticism. We demonstrate that no significant anticorrelation can be found in the Homestake, data,

Stefano Liberati, Bruce A. Bassett, Carmen Molina-Paris, Matt Visser

Variable-Speed-of-Light (VSL) cosmologies are currently attracting much interest as a possible alternative to cosmological inflation. We discuss the fundamental geometrodynamic aspects of VSL cosmologies, and provide several alternative implementations. These implementations provide a large class of VSL cosmologies that pass the zeroth-order consistency test

Steve van Straaten, Eric C. Ford, Michiel van der Klis, Mariano Mendez

We study the correlations between timing and X-ray spectral properties in the low mass X-ray binary 4U 0614+09 using a large (265-ks) data set obtained with the Rossi X-ray Timing Explorer. We find strong quasi-periodic oscillations (QPOs) of the X-ray flux, like the kilohertz QPOs in many other X-ray binaries with accreting neutron stars, with frequencies r

Marek A. Abramowicz, Jean-Pierre Lasota, Igor V. Igumenshchev

We show that recently published assertions that advection dominated accretion flows (ADAFs) require the presence of strong winds are unfounded because they assume that low radiative efficiency in flows accreting at low rates onto black holes implies vanishing radial energy and angular momentum fluxes through the flow (which is also formulated in terms of the

Ignazio Bombaci, Bhaskar Datta

We study the conversion of a neutron star to a strange star as a possible energy source for gamma-ray bursts. We use different recent models for the equation of state of neutron star matter and strange quark matter. We show that the total amount of energy liberated in the conversion is in the range of (1-4) 10^{53} ergs (one order of magnitude larger than pr

Duncan A. Forbes, Karen L. Masters, Dante Minniti, Pauline Barmby

Prompted by a new catalogue of M31 globular clusters, we have collected together individual metallicity values for globular clusters in the Local Group. Although we briefly describe the globular cluster systems of the individual Local Group galaxies, the main thrust of our paper is to examine the collective properties. In this way we are simulating the dissi

T. Ekholm, P. Lanoix, P. Teerikorpi, P. Fouque

We have extended the discussion of Paper II (Ekholm et al. 1999) to cover also the backside of the Local Supercluster (LSC) by using 96 galaxies within Theta<30 deg from the adopted centre of LSC and with distance moduli from the direct B-band Tully-Fisher relation. In order to minimize the influence of the Malmquist bias we required log V_max>2.1 and sigma_

Elisabeth Vangioni-Flam, Michel Casse

The various modes of spallative LiBeB production are summarized, and classified according to their dependence or independence on the abundance of medium heavy elements (CNO) illustrated by that of oxygen in the interstellar medium. The predictions of the models are confronted to the available observational correlations (Be, B vs O). Clearly, a primary mechan

H. Andernach, O. V. Verkhodanov, N. V. Verkhodanova

We used radio source catalogues accessible from the CATS database (http://cats.sao.ru) to establish radio continuum spectra for decametric radio sources in the UTR-2 catalogue (Braude et al., 1978--1994). From these, we select a sample of 23 sources with ultra steep radio spectra (α<=-1.2, S ~ ν^α) and present accurate positions and sizes from FIRST and NVSS

S. Eikenberry, K. Matthews, M. Muno, P. Blanco

We present simultaneous infrared and X-ray observations of the Galactic microquasar GRS 1915+105 using the Palomar 5-m telescope and Rossi X-ray Timing Explorer on July 10, 1998 UT. Over the course of 5 hours, we observed 6 faint infrared (IR) flares with peak amplitudes of $\sim 0.3-0.6 $ mJy and durations of $\sim 500-600 $ seconds. These flares are associ

P. Blasi, A. V. Olinto, A. Stebbins

We study the spectral distortions of the cosmic microwave background radiation induced by the Sunyaev-Zel&#39;dovich (SZ) effect in clusters of galaxies when the target electrons have a modified Maxwell-Boltzmann distribution with a high-energy non-thermal tail. Bremsstrahlung radiation from this type of \\ electron distribution may explain the supra-thermal

Piotr Popowski

I explore the consequences of making the RR Lyrae and clump giant distance scales consistent in the solar neighborhood, Galactic bulge and Large Magellanic Cloud (LMC). I employ two major assumptions: 1) that the absolute magnitude - metallicity, M_V(RR) - [Fe/H], relation for RR Lyrae stars is universal, and 2) that absolute I-magnitudes of clump giants, M_

Guy D. Moore

We present an entirely analytic, leading log order determination of the friction an electroweak bubble wall feels during a first order electroweak phase transition. The friction is dominated by W bosons, and gives a wall velocity parametrically ~ alpha_w, and numerically small, ~ .01 -- 0.1 depending on the Higgs mass.

G. M. Zhao

The coexistence of ferromagnetism and metallic conduction in doped manganites has long been explained by a double-exchange model in which the ferromagnetic exchange arises from the carrier hopping. We evaluate the zero-temperature spin stiffness D(0) and the Curie temperature T_{C} on the basis of the double-exchange model using the measured values of the ba

Valeria Ferrari, Marco D&#39;Andrea, Emanuele Berti

In this paper we consider the Extra-solar Planetary Systems recently discovered in our Galaxy as potential sources of gravitational waves. We estimate the frequency and characteristic amplitude of the radiation they emit due to the orbital motion, using the quadrupole formalism. In addition, we check whether the conditions needed for the resonant excitation

F. Bruckmann, T. Heinzl, T. Tok, A. Wipf

We calculate the Faddeev-Popov operator corresponding to the maximally Abelian gauge for gauge group SU(N). Specializing to SU(2) we look for explicit zero modes of this operator. Within an illuminating toy model (Yang-Mills mechanics) the problem can be completely solved and understood. In the field theory case we are able to find an analytic expression for

S. Trimper, U. C. Taeuber, G. M. Schuetz

The dynamics of a coupled two-component nonequilibrium system is examined by means of continuum field theory representing the corresponding master equation. Particles of species A may perform hopping processes only when particles of different type B are present in their environment. Species B is subject to diffusion-limited reactions. If the density of B par

M. A. Braun

Equation for the sum of BFKL pomeron fan diagrams is rederived by direct summation and solved numerically for rapidities $y\leq 50$. At high rapidities y>20 the resulting cross-sections for the scattering of a longitudinally polarized $q\bar q$ pair on the nucleus cease to depend on its transverse dimension and tend to a constant limit 0.1768 $R_A^2$, which

Guillermo Cortiñas

Let $I$,$J$ be small categories and $C:I\times J@>>>\CAT$ a functor to the category of small categories. We show that if $I$ has a final object then the canonical map $\operatorname{hocolim}_J\operatorname{holim}_IC@>>>\operatorname{holim}_I \operatorname{hocolim}_JC$ is a strong homotopy equivalence.

Chang-qi Cao, Liu Yu-Xi, Hui Cao

In low density regime, the fluorescence of Frenkel exitons in crystal slab can be studied without the aid of rotating wave and Mackoffian approximation. The equations for the case of double and triple lattice-layers are now solved exactly to give the eigen decay rates, frequency shifts and the statistical properties of the fields.

O. Yaremchuk

A new approach to quantum mechanics based on independence of the Continuum Hypothesis is proposed. In one-dimensional case, it is shown that the properties of the set of intermediate cardinality coincide with quantum phenomenology.

Arnold Neumaier

A unified conceptual foundation of classical and quantum physics is given, free of undefined terms. Ensembles are defined by extending the `probability via expectation&#39; approach of Whittle to noncommuting quantities. This approach carries no connotations of unlimited repeatability; hence it can be applied to unique systems such as the universe. Precise c

L. Viola, E. M. Fortunato, S. Lloyd, C. -H. Tseng

We revisit the phenomenon of quantum stochastic resonance in the regime of validity of the Bloch equations. We find that a stochastic resonance behavior in the steady-state response of the system is present whenever the noise-induced relaxation dynamics can be characterized via a single relaxation time scale. The picture is validated by a simple nuclear magn

M. Fleischhauer, M. D. Lukin

We identify form-stable coupled excitations of light and matter (``dark-state polaritons&#39;&#39;) associated with the propagation of quantum fields in Electromagnetically Induced Transparency. The properties of the dark-state polaritons such as the group velocity are determined by the mixing angle between light and matter components and can be controlled b

William D. Walker

The purpose of this paper is to present mathematical evidence that electromagnetic near-field waves and wave groups, generated by an oscillating electric dipole, propagate much faster than the speed of light as they are generated near the source, and reduce to the speed of light at about one wavelength from the source. The speed at which wave groups propagat

B. G. Sidharth

The correct perihelion precession was recently deduced within the frame work of a time varying Gravitational constant G. Here, we deduce also the observed gravitational bending of light and flattening of galactic rotational curves.

D. N. Poenaru, B. Dobrescu, W. Greiner

A three-center phenomenological model able to explain, at least from a qualitative point of view, the difference in the observed yield of a particle-accompanied fission and that of binary fission was developed. It is derived from the liquid drop model under the assumption that the aligned configuration, with the emitted particle between the light and heavy f

V. Guimaraes, J. J. Kolata, D. Bazin, B. Blank

The single-nucleon knockout reactions 9Be(14B, 13B + gamma)X and 197Au(14B, 13B + gamma)X, at an incident energy of 60 MeV per nucleon, have been used to probe the structure of 14B and of the core fragment 13B. A dominant 2s configuration is deduced for the neutron in the ground state of 14B. The longitudinal momentum distribution for this state is consisten

Daniel T. Kaplan

Analysis of the PPF chaos control method used in biological experiments shows that it can robustly control a wider class of systems than previously believed, including those without stable manifolds. This can be exploited to find the locations of unstable periodic orbits by varying the parameters of the control system.

Theodore C. Belding

A computer simulation, such as a genetic algorithm, that uses IEEE standard floating-point arithmetic may not produce exactly the same results in two different runs, even if it is rerun on the same computer with the same input and random number seeds. Researchers should not simply assume that the results from one run replicate those from another but should v

John H. van Drie

The equations of parallel transport for a non-linear connection on phase space are examined. It is shown that, for a free-particle Lagrangian, the connection term first-order in momentum reproduces the geodesic equation of General Relativity and the term zeroth-order in the momentum reproduces the Lorentz electromagnetic force law. Hence from one mathematica