August 1999 arXiv papers — page 18

Duncan A. Forbes, Alejandro I. Terlevich

We discuss recent developments on the age and metallicity distribution for early type galaxies in different environments.

Charles L. Curry, Christopher F. McKee

We construct spherical, hydrostatic models of dense molecular cores and Bok globules consisting of two distinct, spatially separate gas components: a central, isothermal region surrounded by a negative-index, polytropic envelope. The clouds are supported against their own self-gravity by a combination of thermal, mean magnetic, and turbulent wave pressure. T

E. Bertone, G. Tagliaferri, G. Ghisellini, A. Treves

The Infrared Space Observatory (ISO) observed the BL Lac object PKS 2155-304 16 times from 1996, May 7 to June 8, with both the ISOCAM camera and the ISOPHOT photometer, as part of a more general multiwavelength campaign. Two additional observations were performed on 1996, November 23 and 1997, May 15. This is the first time that there are simultaneous mid a

Eric Slezak, Florence Durret, Jean Guibert, Catarina Lobo

We present two catalogues of galaxies in the direction of the rich cluster Abell 496. The first one includes 3,879 galaxies located in a region of roughly 1.3 degrees from the cluster centre. It has been obtained from a list of more than 35,000 galaxy candidates detected by scanning part of a Schmidt photographic plate taken in the b_J band. Positions are ve

M. J. Hardcastle

I present four-frequency radio observations of the wide-angle tail radio galaxy 3C130. By a technique of simulated observations, I assess the systematic errors in the data due to the varying uv plane coverage in the different observations used. Using spectral tomography I show that, at least in the southern plume, the source can be represented by a two-compo

A. Pagliaro, V. Antonuccio-Delogu, U. Becciani, M. Gambera

We present and discuss a method to identify substructures in combined angular-redshift samples of galaxies within Clusters. The method relies on the use of Discrete Wavelet Transform (hereafter DWT) and has already been applied to the analysis of the Coma cluster (Gambera et al. 1997). The main new ingredient of our method with respect to previous studies li

F. J. Molster, L. B. F. M. Waters, N. R. Trams, H. van Winckel

We present infrared spectroscopy and imaging of AFGL~4106. The 2.4-5 micron ISO-SWS spectrum reveals the presence of a cool, luminous star (T_eff ~ 3750 K) in addition to an almost equally luminous F star (T_eff ~ 7250 K). The 5-195 micron SWS and LWS spectra are dominated by strong emission from circumstellar dust. We find that the dust consists of amorphou

A. C. Fabian

The mass density of massive black holes observed locally is consistent with the hard X-ray Background provided that most of the radiation produced during their growth was absorbed by surrounding gas. A simple model is proposed here for the formation of galaxy bulges and central black holes in which young spheroidal galaxies have a significant distributed com

E. Oliva, L. Origlia, R. Maiolino, A. F. M. Moorwood

High quality infrared spectra of active galaxies including the stellar absorption features of Si at 1.59 um, CO(6,3) at 1.62 um, and CO(2,0) at 2.29 um are used to measure the stellar mass to light ratio at 1.65 um (M_H/L) and investigate the occurrence circum--nuclear starbursts. We find that old and powerful starbursts are relatively common in obscured AGN

Paolo Molaro, Piercarlo Bonifacio, Miriam Centurion, Giovanni Vladilo

A high-resolution, high signal-to-noise HIRES-Keck spectrum of APM 08279+5255 reveals a feature in the HI Ly alpha profile of the zabs=3.514 absorber at the expected position of the corresponding DI Lyalpha line. The absorber shows a relatively simple velocity structure, with a major component detected in several metallic lines including CII, CIV, SiII, SiII

Joerg Sanner, Michael Geffert, Jens Brunzendorf, Juergen Schmoll

We present CCD photometry and a proper motion study of the young open star cluster, NGC 581 (M 103). Fitting isochrones to the colour magnitude diagram, we found an age of 16 +/- 4 Myr and a distance of roughly 3 kpc for this cluster. The proper motion study identifies 77 stars of V=14.5 mag or brighter to be cluster members. We combine membership determinat

G. De Zotti, C. Gruppioni, P. Ciliegi, C. Burigana

We have derived the relationship between polarization and intensity fluctuations due to point sources. In the case of a Poisson distribution of a population with uniform evolution properties and constant polarization degree, polarization fluctuations are simply equal to intensity fluctuations times the average polarization degree. Conservative estimates of t

H. Daisaka, S. Ida

We investigate the formation of spatial structure in dense, self-gravitating particle systems such as Saturn's B-ring through local $N$-body simulations to clarify the intrinsic physics based on individual particle motion. In such a system, Salo (1995) showed that the formation of spatial structure such as wake-like structure and particle grouping (clump

Maria Lugaro, Ernst Zinner, Roberto Gallino, Sachiko Amari

Although mainstream SiC grains, the major group of presolar SiC grains found in meteorites, are believed to have originated in the expanding envelope of asymptotic giant branch (AGB) stars during their late carbon-rich phases, their Si isotopic ratios show a distribution that cannot be explained by nucleosynthesis in this kind of stars. Previously, this dist

J. E. Horvath

Based on observational facts and a variety of theoretical arguments we discuss in this work the possibility that pulsars in Low-Mass Binary Pulsar systems could be strange stars rather than neutron stars. It is shown that, although subject to reasonable uncertainties, the consideration of the physics of the SQM core and thin normal crusts leads to the predic

J. A. Garcia-Barreto, H. Aceves, O. Kuhn, G. Canalizo

Optical red spectra of a set of 18 bright barred spiral galaxies are presented. The study is aimed at determining the local kinematics, and the physical conditions of ionized gas in the compact nucleus (inside a diameter of 5") and in the circumnuclear regions (inside a diameter of 20"). Only 8 galaxies showed bright emission from their east and west

M. E. J. Newman, R. G. Palmer

We review recent work aimed at modeling species extinction over geological time. We discuss a number of models which, rather than dealing with the direct causes of particular extinction events, attempt to predict overall statistical trends, such as the relative frequencies of large and small extinctions, or the distribution of the lifetimes of species, gener

Jeremy Michelson, Andrew Strominger

The quantum mechanics of N slowly-moving charged BPS black holes in five-dimensional ${\cal N}=1$ supergravity is considered. The moduli space metric of the N black holes is derived and shown to admit 4 supersymmetries. A near-horizon limit is found in which the dynamics of widely separated black holes decouples from that of strongly-interacting, near-coinci

Sanjay Hortikar, Mark Srednicki

We derive a trace formula for $\sum_n A_{nn}B_{nn}...δ(E-E_n)$, where $A_{nn}$ is the diagonal matrix element of the operator $A$ in the energy basis of a chaotic system. The result takes the form of a smooth term plus periodic-orbit corrections; each orbit is weighted by the usual Gutzwiller factor times $A_p B_p ...$, where $A_p$ is the average of the clas

Francisco J. Solis, Monica Olvera de la Cruz

The collapse of flexible polyelectrolytes in a solution of multivalent counterions is studied by means of a two state model. The states correspond to rod-like and spherically collapsed conformations respectively. We focus on the very dilute monomer concentration regime where the collapse transition is found to occur when the charge of the multivalent salt is

Graciela Gelmini, Alexander Kusenko

Decays of superheavy relic particles may produce extremely energetic neutrinos. Their annihilations on the relic neutrinos can be the origin of the cosmic rays with energies beyond the Greisen-Zatsepin-Kuzmin cutoff. The red shift acts as a cosmological filter selecting the sources at some particular value z_e, for which the present neutrino energy is close

V. Dmitrašinović, K. Kubodera, F. Myhrer, T. Sato

We discuss the results of a systematic calculation of the next-to-next-to-leading order amplitude for the pp -> ppπ^0 S-wave production at the threshold in heavy-baryon chiral perturbation theory. We find six new diagrams, two of which can be viewed as vertex corrections, of 15 - 20 %, to the pion-exchange graph, whereas the rest are much larger, one exceedi

Stefan Kettemann, Peter Fulde, Peter Strehlow

Low temperature properties of glasses are derived within a generalized tunneling model, considering the motion of charged particles on a closed path in a double-well potential. The presence of a magnetic induction field B violates the time reversal invariance due to the Aharonov-Bohm phase, and leads to flux periodic energy levels. At low temperature, this e

D. Garfinkle, C. Gundlach

In numerically constructing a spacetime that has an approximate timelike Killing vector, it is useful to choose spacetime coordinates adapted to the symmetry, so that the metric and matter variables vary only slowly with time in these coordinates. In particular, this is a crucial issue in numerically calculating a binary black hole inspiral. An approximate h

Tom Bridgeland, Antony Maciocia

Given a non-singular variety with a K3 fibration f : X --> S we construct dual fibrations Y --> S by replacing each fibre X_s of f by a two-dimensional moduli space of stable sheaves on X_s. In certain cases we prove that the resulting scheme Y is a non-singular variety and construct an equivalence of derived categories of coherent sheaves \Phi : D(Y) --> D(

A. Anastassov, CLEO Collaboration

We present the first observation of the decay B->J/psi phi K. Using 9.6 million B meson pairs collected with the CLEO detector, we have observed 10 fully reconstructed B->J/psi phi K candidates, whereas the estimated background is 0.5+/-0.2 events. We obtain a branching fraction of Br(B->J/psi phi K) = (8.8+3.5/-3.0(stat)+/-1.3(syst))*10^-5. This is the firs

Hans U Boden, Christopher M Herald, Paul A Kirk, Eric P Klassen

New methods for computing a variety of gauge theoretic invariants for homology 3-spheres are developed. These invariants include the Chern-Simons invariants, the spectral flow of the odd signature operator, and the rho invariants of irreducible SU(2) representations. These quantities are calculated for flat SU(2) connections on homology 3-spheres obtained by

Marco Peloso, Francesca Rosati

Attention has been recently drawn towards models in which inflation and quintessence schemes are unified. In such `quintessential inflation' models, a unique scalar field is required to play both the role of the inflaton and of the late-time dynamical cosmological constant. We address the issue of the initial conditions for quintessence in this context a

Ingo Runkel

In this paper expressions are given for the bulk and boundary structure constants of D-series Virasoro minimal models on the upper half plane. It is the continuation of an earlier work on the A-series. The solution for the boundary theory is found first and then extended to the bulk. The modular invariant bulk field content is recovered as the maximal set of

Tatsuo Komori, Hajime Yoshino, Hajime Takayama

Using Monte Carlo simulations, we have studied isothermal aging of three-dimensional Ising spin-glass model focusing on quasi-equilibrium behavior of the spin auto-correlation function. Weak violation of the time translational invariance in the quasi-equilibrium regime is analyzed in terms of {\it effective stiffness} for droplet excitations in the presence

F. Maca, M. Kotrla, O. S. Trushin

Energy barriers for different moves of a single Rh adatom in the vicinity of steps on Rh(111) surface are studied with molecular statics. Interatomic interactions are modeled by the semi-empirical many-body Rosato-Guillope-Legrand potential. We calculate systematically barriers for the descent at straight steps, steps with the kink and small islands as well

M. V. Feigel'man, A. I. Larkin, M. A. Skvortsov

The effect of Coulomb interaction upon superconductive proximity effect in disordered metals is studied, employing newly developed Keldysh functional approach (cond-mat/9907358). We have calculated subgap Andreev conductance between superconductor and 2D dirty film, as well as Josephson coupling via such a film. Both two qualitatively different Coulomb effec

Bastian Kubis, Ulf-G. Meißner

We evaluate the vector and scalar form factor of the pion in the presence of virtual photons at next-to-leading order in two-flavor chiral perturbation theory. We also consider the scalar and tensor pion form factors of the energy-momentum tensor. We find that the intrinsic electromagnetic corrections are of the expected size for the vector form factor and v

Imseok Yang, Ekkehard Lange, Gabriel Kotliar

We investigate the paramagnetic-metal-to-antiferromagnetic-metal and antiferromagnetic-metal-to- antiferromagnetic-insulator transitions using a slave-boson mean-field theory. To this effect, we discuss the ground state of the half-filled Hubbard model as a function of t'/t and correlation strength U, where t and t' are the hopping amplitudes between

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

We discuss the quark parton structure of the $\Lambda$ baryon and the fragmentation of quarks into $\Lambda$ baryons. We show that the hyperfine interaction, responsible for the $\Delta$-$N$ and $\Sigma^0$-$\Lambda$ mass splittings, leads not only to sizeable SU(3) and SU(6) symmetry breaking in the quark distributions of the $\Lambda$, but also to significa

Yongqiang Xue, Supriyo Datta

At any metal-carbon nanotube interface there is charge transfer and the induced interfacial field determines the position of the carbon nanotube band structure relative to the metal Fermi-level. In the case of a single-wall carbon nanotube (SWNT) supported on a gold substrate, we show that the charge transfers induce a local electrostatic potential perturbat

Douglas C. Leonard, Alexei V. Filippenko, Aaron J. Barth, Thomas Matheson

We present optical spectropolarimetry obtained at the Keck-II 10-m telescope on 1998 March 7 UT along with total flux spectra spanning the first 494 days after discovery (1998 March 2 UT) of the peculiar type IIn supernova (SN) 1998S. The SN is found to exhibit a high degree of linear polarization, implying significant asphericity for its continuum-scatterin

Mladen Pavicic

A nonclassical feature of the fourth-order interference at a beam splitter, that genuine photon spin singlets are emitted in predetermined directions even when incident photons are unpolarized, has been used in a proposal for an experiment that imposes quantum spin correlation on truly independent photons. In the experiment, two photons from two such singlet

Harry Paul, Mladen Pavicic

We show that with an efficiency exceeding 99% one can use a monolithic total-internal-reflection resonator in order to ascertain the presence of an object without transferring a quantum of energy to it. We also propose an experiment on the probabilistic meaning of the electric field that contains only a very few photons.

A. Carlini, A. Hosoya

We present a quantum probabilistic algorithm which tests with a polynomial computational complexity whether a given composite number is of the Carmichael type. We also suggest a quantum algorithm which could verify a conjecture by Pomerance, Selfridge and Wagstaff concerning the asymptotic distribution of Carmichael numbers smaller than a given integer.

Tetsufumi Tanamoto

We investigated the quantum gates of coupled quantum dots, theoretically, when charging effects can be observed. We have shown that the charged states in the qubits can be observed by the channel current of the MOSFET structure.

Gh. Adam, S. Adam

A subtractionless method for solving Fermi surface sheets ({\tt FSS}), from measured $n$-axis-projected momentum distribution histograms by two-dimensional angular correlation of the positron-electron annihilation radiation ({\tt 2D-ACAR}) technique, is discussed. The window least squares statistical noise smoothing filter described in Adam {\sl et al.}, NIM

Igor S. Aranson, Boris A. Malomed, Len M. Pismen, Lev S. Tsimring

It is shown numerically and analytically that the front propagation process in the framework of the Swift-Hohenberg model is determined by periodic nucleation events triggered by the explosive growth of the localized zero-eigenvalue mode of the corresponding linear problem. We derive the evolution equation for this mode using asymptotic analysis, and evaluat

Yuji Igarashi, Katsumi Itoh, Ken Nakanishi, Kazuhiro Ogura

In the optimal velocity model with a time lag, we show that there appear multiple exact solutions in some ranges of car density, describing a uniform flow, a stable and an unstable congested flows. This establishes the presence of subcritical Hopf bifurcations. Our analytic results have far-reaching implications for traffic flows such as hysteresis phenomena

Bingfeng Ding, Jurij Darewych

We consider particle-antiparticle bound states in the scalar Yukawa (Wick-Cutkosky) model. The variational method in the Hamiltonian formalism of quantum field theory is employed. A reformulation of the model is studied, in which covariant Green's functions are used to solve for the mediating field in terms of the particle fields. A simple Fock-state var

Toshiki Maruyama, Tetsuo Hatsuda

We propose a microscopic simulation for quark many-body system based on molecular dynamics. Using color confinement and one-gluon exchange potentials together with the meson exchange potentials between quarks, we construct nucleons and nuclear/quark matter. Statistical feature and the dynamical change between confinement and deconfinement phases are studied

Sagar A. Pandit, Anil D. Gangal

In Ref.~\cite{Sag} we proposed a geometric formulation of generalized Nambu mechanics. In the present paper we extend the class of Nambu systems by replacing the stringent condition of constancy of 3-form by closedness. We also explore the connection between continuous groups of symmetries and conservation laws for such systems. The Noether theorem for gener

Palle E. T. Jorgensen

Let $U$ be an operator in a Hilbert space $\mathcal{H}_{0}$, and let $\mathcal{K}\subset\mathcal{H}_{0}$ be a closed and invariant subspace. Suppose there is a period-2 unitary operator $J$ in $\mathcal{H}_{0}$ such that $JUJ=U^*$, and $PJP \geq 0$, where $P$ denotes the projection of $\mathcal{H}_{0}$ onto $\mathcal{K}$. We show that there is then a Hilbert

Masanori Asakura

In this paper, we show some applications to algebraic cycles by using higher Abel-Jacobi maps which were defined in [the author: Motives and algebraic de Rham cohomology]. In particular, we prove that the Beilinson conjecture on algebraic cycles over number fields implies the Bloch conjecture on zero-cycles on surfaces. Moreover, we construct a zero-cycle on

David Kazhdan, Alexander Polishchuk

In this paper we consider the analogue of the Sato's functional equation for the prehomogeneous vector spaces over finite fields. The corresponding character sums depend on a relative invariant on such a space and an irreducible representation of the group of components of the stabilizer of a generic point. The proof is based on the Picard-Lefschetz form

Samuel R. Kaplan

Solutions to the collinear three-body problem which do not end in triple collision pass through an infinite number of binary collisions. Given three masses, we show that four geometric quantities generate a finite description of itineraries of binary collisions. In the best circumstances, this description is semi-conjugate to a Poincare map of the flow. For

Crainic Marius

REVISED VERSION: We have re-organized the paper, and included some new results. Most important, we prove that the (truncated) Weil complexes compute the cyclic cohomology of the Hopf algebra (see the new Theorem 7.3). We also include a short discussion on the uni-modulare case, and the computation for $H= U_q(sl_2)$. THE OLD ABSTRACT: We give a construction

Swapna Mahapatra

In this note, we review various seemingly different ways of obtaining Eguchi-Hanson metric with or without a cosmological constant term. Interestingly, the conformal class of metric corresponding to hyperbolic $n$-monopole solution obtained from the generalized Gibbons-Hawking ansatz, reduces to the Eguchi-Hanson metric in a particular limit. These results,

A. Chamblin, M. J. Perry, H. S. Reall

We study the D8-branes of the Romans massive IIA supergravity theory using the coupled supergravity and worldvolume actions. D8 branes can be regarded as domain walls with the jump in the extrinsic curvature at the brane given by the Israel matching conditions. We examine the restrictions that these conditions place on extreme and non-extreme solutions and f

Ken-Ichi Aoki, Keiichi Morikawa, Jun-Ichi Sumi, Haruhiko Terao

The non-perturbative renormalization group equation for the Wilsonian effective potential is given in a certain simple approximation scheme in order to study chiral symmetry breaking phenomena dynamically induced by strong gauge interactions. The evolving effective potential is found to be non-analytic in infrared, which indicates spontaneous generation of t

Ken-Ichi Aoki, Keiichi Morikawa, Jun-Ichi Sumi, Haruhiko Terao

The critical dynamics of the chiral symmetry breaking induced by gauge interaction is examined in the Wilson renormalization group framework in comparison with the Schwinger-Dyson approach. We derive the beta functions for the four-fermi couplings in the sharp cutoff renormalzation group scheme, from which the critical couplings and the anomalous dimensions

Dimitri Polyakov

We perform the derivation of the two-point correlation function in N=4 D=4 super Yang-Mills theory from superstring theory by computing the dilaton scattering amplitude in the NSR formulation of superstring theory on $AdS_5\times{S^5}$

Mohammad R. Ahmady

We examine our previous conjecture that the eta' intermediate resonance has the dominant role in the long distance contributions to B decay into two photons and a strange final state hadron. We calculate the branching ratio of the exclusive B-> K eta'-> K photon photon decay using the nonspectator mechanism for eta' production in charmless hadron

Pervez Hoodbhoy, Xiangdong Ji

Although the matrix element of the gluon spin operator in nucleon helicity states is known to be independent of some special choices of gauge, we show that it is not invariant under a general gauge transformation. We find that there exists a simple means of obtaining the matrix element in a different choice of gauge from a calculation made in one specific ga

H. G. Dosch, F. S. Navarra, M. Nielsen, M. Rueter

We calculate the nonperturbative $J/Ψ-N$ and $Ψ'-N$ cross sections with the model of the stochastic vacuum which has been succesfully applied in many high energy reactions. We also give a quantitative discussion of pre-resonance formation and medium effects.

G. M. Shore

The radiative decays $η'(η)\rtaγγ$ are discussed. The modifications of the conventional PCAC formulae due to the gluonic contribution to the flavour singlet axial anomaly are given. The decay constants satisfy a modified Dashen formula which generalises the Witten--Veneziano formula for the mass of the $η'$. It is shown how the topological susceptibi

Mikhail Bilenky, Arcadi Santamaria

We review the information about a potentially strong non-standard four-neutrino interaction that can be obtained from available experimental data. By using LEP results and nucleosynthesis data we find that a contact four-fermion neutrino interaction that involve only left-handed neutrinos or both left-handed and right-handed neutrinos cannot be stronger than

I. V. Akushevich, S. V. Chekanov

The measurement of the polarized gluon distribution function Delta_G/G using current-target correlations in the Breit frame of deep inelastic scattering is proposed. The approach is illustrated using a Monte Carlo simulation of polarized $ep$-collisions for HERA energies.

K. Gallmeister, B. Kampfer, O. P. Pavlenko

An analysis of the dilepton measurements in the reactions Pb(158 A$\cdot$GeV) + Au, Pb points to a unique thermal source contributing to the invariant mass and transverse momentum spectra. Effects of the flow pattern are discussed.

K. Fialkowski, R. Wit

We discuss the Bose-Einstein interference effect in multiparticle production. After a short review of various methods of implementation of this effect into Monte Carlo generators the weight method is presented in more detail and used to analyze the data for hadronic Z0 decays. In particular, we consider the possibility of deducing the two-particle weight fac

S. M. Harun-or-Rashid, Tatsuo Kobayashi, Hitoshi Shimabukuro

We study F-term inflation in M-theory with and without five-brane moduli fields. We show the slow rolling condition is not satisfied in M-theory without five-brane moduli fields, but it can be satisfied in the case with non-vanishing F-terms of five-brane moduli fields.

V. S. Fadin, R. Fiore, M. I. Kotsky, A. Papa

We calculate in the next-to-leading approximation the non-forward quark impact factors for both singlet and octet color representation in the $t$-channel. The integral representation of the octet impact factor in the general case of arbitrary space-time dimension and massive quark flavors is used to check the so-called "second bootstrap condition" fo

V. S. Fadin, R. Fiore, M. I. Kotsky, A. Papa

We calculate in the next-to-leading approximation the non-forward gluon impact factors for arbitrary color state in the $t$-channel. In the case of the octet state we check the so-called "second bootstrap condition" for the gluon Reggeization in QCD, using the integral representation for the impact factors. The condition is fulfilled in the general c

D. P. Roy

The atmospheric and solar neutrino oscillation data suggest hierarchical neutrino masses with at least one large mixing. The simplest see-saw models for reconciling the two features are U(1) extensions of the SM with flavour dependent gauge charges. I discuss a minimal model of this type containing two heavy right-handed neutrinos, which have normal Dirac co

M. -P. Lombardo

Experiments with imaginary chemical potential and Glasgow method carried out in two interrelated models - four dimensional QCD in the infinite coupling limit, and one dimensional QCD - support the point of view expressed by the title.

M. Gockeler, R. Horsley, H. Oelrich, D. Petters

A fully non-perturbative lattice determination of the up/down and strange quark masses is given for quenched QCD using both, $O(a)$ improved Wilson fermions and ordinary Wilson fermions. For the strange quark mass with $O(a)$ improved fermions we obtain $m^{\msbar}_s(μ=2 {GeV}) = 105(4) {MeV}$, using the interquark force scale $r_0$. Due to quenching problem

Jani Lukkarinen

We define a natural coarse-graining procedure which can be applied to any closed equilibrium quantum system described by a density matrix ensemble and we show how the coarse-graining leads to the Gaussian and canonical ensembles. After this motivation, we present two ways of evaluating the Gaussian expectation values with lattice simulations. The first one i

KTeV Collaboration

We report the first observation of a manifestly CP violating effect in the K(L)->pi+pi-e+e- decay mode. A large asymmetry was observed in the distribution of these decays in the CP-odd and T-odd angle phi between the decay planes of the e+e- and pi+pi- pairs in the K(L) center of mass system. After acceptance corrections, the overall asymmetry is found to be

D0 Collaboration, B. Abbott

We report the results of a study of color coherence effects in ppbar collisions based on data collected by the D0 detector during the 1994-1995 run of the Fermilab Tevatron Collider, at a center of mass energy sqrt(s) = 1.8 TeV. Initial-to-final state color interference effects are studied by examining particle distribution patterns in events with a W boson

P. N. Burrows

A summary is presented of the key strong-interaction measurements that could be made at a high-energy, high-luminosity e+e- collider

The OPAL Collaboration, G. Abbiendi

From an analysis of the ionisation energy loss of charged particles selected from a sample of 147926 e+e- -> tau+tau- candidates recorded in the OPAL detector at e+e- centre-of-mass energies near the Z0 resonance, we determine the branching ratios: BR(tau- -> nu_tau K- pi- pi+ (pi0)) = 0.343 +- 0.073 +- 0.031 % BR(tau- -> nu_tau K- pi- K+ (pi0)) = 0.159 +- 0

Sameer Gupta

We compute Teitelboim's causal propagator in the context of canonical loop quantum gravity. For the Lorentzian signature, we find that the resultant power series can be expressed as a sum over branched, colored two-surfaces with an intrinsic causal structure. This leads us to define a general structure which we call a ``causal spin foam''. We als

Donald Marolf

This contribution to the proceedings of the 1999 Canadian Conference on General Relativity and Relativistic Astrophysics is a brief exposition of earlier work, with Sumati Surya (hep-th/9805121) Amanda Peet (hep-th/9903213), addressing certain results in higher dimensional supergravity that are related to black hole no-hair theorems. Its purpose is to descri

László Á. Gergely, Zoltán I. Perjés, Mátyás Vasúth

The true and eccentric anomaly parametrizations of the Kepler motion are generalized to quasiperiodic orbits, by considering perturbations of the radial part of the kinetic energy in a form of a series of negative powers of the orbital radius. A toolchest of methods for averaging observables as functions of the energy $E$ and angular momentum $L$ is develope

P. Mitra

Majumdar--Papapetrou multi--black-hole solutions of the Einstein--Maxwell equations are considered in four and higher dimensions. The Euclidean action with boundary conditions appropriate to the canonical ensemble is shown to lead to zero entropy.

M. Reza Sadr-Lahijany, Antonio Scala, Sergey~V. Buldyrev, H. Eugene Stanley

We use a one-dimensional (1d) core-softened potential to develop a physical picture for some of the anomalies present in liquid water. The core-softened potential mimics the effect of hydrogen bonding. The interest in the 1d system stems from the facts that closed-form results are possible and that the qualitative behavior in 1d is reproduced in the liquid p

Angsula Ghosh, Sadhan K. Adhikari

The temperature dependencies of specific heat and spin susceptibility of a coupled $d_{x^2-y^2} +id_{xy}$ superconductor in the presence of a weak $d_{xy}$ component are investigated in the tight-binding model (1) on square lattice and (2) on a lattice with orthorhombic distortion. As the temperature is lowered past the critical temperature $T_c$, first a le

Bahman Davoudi, Mohammad Kohandel

We study the phase diagram of the flux lines using the mapping to 2D bosons in the self-consistent-field approximation of Singwi, Tosi, Land, and Sjolander (STLS). The pair correlation function, static structure factor, interaction energy, and spectrum of the excited energies are calculated over a wide range of the parameters in this approximation. These qua

Rouzbeh Gerami, Mohammad R. Ejtehadi

A non-Markovian stochastic predator-prey model is introduced in which the prey are immobile plants and predators are diffusing herbivors. The model is studied by both mean-field approximation (MFA)and computer simulations. The MFA results a series of bifurcations in the phase space of mean predator and prey densities, leading to a chaotic phase. Because of e

M. Sanquer, M. Specht, L. Ghenim, S. Deleonibus

We investigate coherent transport in Si:MOSFETs with nominal gate lengths 50 to 100nm and various widths at very low temperature. Independent of the geometry, localized states appear when G=e^{2}/h and transport is dominated by resonant tunnelling through a single quantum dot formed by an impurity potential. We find that the typical size of the relevant impu

A. Mourachkine

The phase diagram of order parameters for pairing and phase coherence in hole-doped cuprates is discussed. By examining carefully some recent inelastic neutron scattering data obtained on hole-doped cuprates and heavy fermion compound UPd2Al3 in which the superconductivity is mediated by spin fluctuations, we conclude that the coherent gap in hole-doped cupr

Rodrigo A. Ibata, Geraint F. Lewis, Michael J. Irwin, Joseph Lehar

We present a suite of observations of the recently identified ultraluminous BAL quasar APM 08279+5255, taken both in the infra-red with the NICMOS high resolution camera on board the Hubble Space Telescope, and at 3.5cm with the Very Large Array. With an inferred luminosity of ~5x10^15 Solar luminosities, APM 08279+5255 is apparently the most luminous system

Kenneth R. Sembach, J. Christopher Howk, Robert S. I. Ryans, Francis P. Keenan

We present model calculations of ionization fractions for elements in the warm (log T = 4), low-density photoionized interstellar medium (WIM) of the Milky Way. We model the WIM as a combination of overlapping low-excitation H II regions having n(HII)/n(H) > 0.8. Our standard model incorporates an intrinsic elemental abundance pattern similar to that found f

Sidney van den Bergh

Hubble's view that the Local Group (LG) is "a typical, small group of nebulae which is isolated in the general field" is confirmed by modern data. The total number of certain and probable Group members presently stands at 35. The half- mass radius of the LG is Rh = 350 kpc, and the zero-velocity surface has a radius Ro = 1.18 +/- 0.15 Mpc. The to

Eric Agol, Julian Krolik

Magnetic connections to the plunging region can exert stresses on the inner edge of an accretion disk around a black hole. We recompute the relativistic corrections to the thin-disk dynamics equations when these stresses take the form of a time-steady torque on the inner edge of the disk. The additional dissipation associated with these stresses is concentra

Duncan A. Forbes, Edward Polehampton, Ian R. Stevens, Jean P. Brodie

Here we present new optical data from the Hubble Space Telescope of the NGC 253 central region, which reveal numerous discrete sources in a ring--like structure. This is combined with data at infrared, millimeter, radio and X-ray wavelengths to examine the nature of these discrete sources and the nucleus itself. We find that the majority of optical/IR/mm sou

R. Barbon, V. Buondi', E. Cappellaro, M. Turatto

Ten years after the publication of the previous release, we present a new edition of the Asiago Supernova Catalogue updated to December 31, 1998 and containing data for 1447 supernovae and their parent galaxies\footnote{Tables 1 and 2 are only available in electronic form at the CDS via anonymous ftp to cdsarc.u-strasbg.fr (130.79.128.5) or via http://cdsweb

Florence Durret, Paul Felenbok, Catarina Lobo, Eric Slezak

We present a catalogue of velocities for 466 galaxies in the direction of the cluster Abell 496, in a region covering about 160' x 160' (9.2 x 9.2 Mpc for an average redshift for Abell 496 of 0.0331, assuming H$_0$=50 km s$^{-1}$ Mpc$^{-1}$). This catalogue includes previously published redshifts by Proust et al. (1987), Quintana and Ramirez (1990) a

Yu. N. Efremov, S. Ehlerova, J. Palous

We discuss differences in shapes, expansion velocities and fragmentation times of structures created by an energy deposition from a single Gamma Ray Burst (GRB) or an OB association to the ISM. After the initial inflation, supershells produced by GRBs are almost static or slowly expanding, contrary to more rapidly expanding supershells created by OB associat

Gavin Ramsay, Mark Cropper, Kinwah Wu, Keith Mason

We have detected the optical counterpart of the proposed double degenerate polar RX J1914+24. The I band light curve is modulated on the 9.5 min period seen in X-rays. There is no evidence for any other periods. No significant modulation is seen in J. The infrared colours of RX J1914+24 are not consistent with a main sequence dwarf secondary star. Our ASCA s

R. K. Manchanda

The paper is withdrawn due to certain inherent problem in the public archival data of BATSE which may have modulation due to satellite precession.

Wentian Li, Jens Reich

There are 512 two-locus, two-allele, two-phenotype, fully-penetrant disease models. Using the permutation between two alleles, between two loci, and between being affected and unaffected, one model can be considered to be equivalent to another model under the corresponding permutation. These permutations greatly reduce the number of two-locus models in the a

A. Yu. Alekseev, A. Recknagel, V. Schomerus

The geometry of D-branes can be probed by open string scattering. If the background carries a non-vanishing B-field, the world-volume becomes non-commutative. Here we explore the quantization of world-volume geometries in a curved background with non-zero Neveu-Schwarz 3-form field strength H = dB. Using exact and generally applicable methods from boundary c

D. P. Bennett, S. H. Rhie, A. C. Becker, N. Butler

The study of extra-solar planetary systems has emerged as a new discipline of observational astronomy in the past few years with the discovery of a number of extra-solar planets. The properties of most of these extra-solar planets were not anticipated by theoretical work on the formation of planetary systems. Here we report observations and light curve model

William E. Brown, James T. Liu, Hai-cang Ren

Color superconductivity is a possible phase of high density QCD. We present a systematic derivation of the transition temperature, T_C, from the QCD Lagrangian through study of the di-quark proper vertex. With this approach, we confirm the dependence of T_C on the coupling g, namely $T_C \sim μg^{-5} e^{-κ/g}$, previously obtained from the one-gluon exchange