July 1999 arXiv papers — page 18

B. A. Kniehl, A. Sirlin

We consider a hypothetical scenario in which the Higgs boson is absent, and attempt to constrain the mass scale Lambda of the new physics that would take its place. Using recent measurements of sin^2(theta_eff^lept) and M_W, we show that, in a class of theories characterized by simple conditions, the upper bound on Lambda is close to or smaller than the SM u

Ming-Yang Kao, Jie Wang

Given a multiset $X=\{x_1,..., x_n\}$ of real numbers, the {\it floating-point set summation} problem asks for $S_n=x_1+...+x_n$. Let $E^*_n$ denote the minimum worst-case error over all possible orderings of evaluating $S_n$. We prove that if $X$ has both positive and negative numbers, it is NP-hard to compute $S_n$ with the worst-case error equal to $E^*_n

P. M. Saffin

In the light of recent studies of BPS triple junctions in the Wess-Zumino model we describe techniques to construct infinite lattices using similar junctions. It is shown that whilst these states are only approximately locally BPS they are nevertheless stable to small perturbations, giving a metastable tiling of the plane.

Leonardo Angelini, Mario Pellicoro, Sebastiano Stramaglia

Dynamical scaling in a two-dimensional lattice model of chaotic maps, in contact with a thermal bath, is numerically studied. The model here proposed is equivalent to a conserved Ising model with coupligs which fluctuate over the same time scale as spin moves. When couplings fluctuations and thermal fluctuations are both important, this model does not belong

Charles Hellaby, Ariel Sumeruk, G. F. R. Ellis

Investigations of classical signature change have generally envisaged applications to cosmological models, usually a Friedmann-Lemaitre-Robertson-Walker model. The purpose has been to avoid the inevitable singularity of models with purely Lorentzian signature, replacing the neighbourhood of the big bang with an initial, singularity free region of Euclidean s

W. Kummer, D. V. Vassilevich

Hawking radiation in d=4 is regarded as a well understood quantum theoretical feature of Black Holes or of other geometric backgrounds with an event horizon. On the other hand, the dilaton theory emerging after spherical reduction and generalized dilaton theories only during the last years became the subject of numerous studies which unveiled a surprisingly

Jens O. Andersen

In this talk I briefly discuss the thermodynamics of the quark-gluon plasma The calculation of the free energy of a hot gluon plasma to leading order in hard-thermal-loop perturbation theory is outlined. The HTL free energy is compared with the weak-coupling expansion and lattice results.

F. Arleo, P. -B. Gossiaux, T. Gousset, J. Aichelin

The new high precision data on charmonium production in proton-nucleus collisions by the E866/NuSea collaboration at Fermilab allow - together with older data at lower energies - to fix a unique set of parameters for the standard production and absorption scenario of charmonium in a proton-nucleus reaction. In this scenario the c-cbar pair is formed in an oc

J. H. Reina, J. C. Granada, N. F. Johnson

The electromagnetic propagator associated with the localized collective magnetoplasmon excitations in a semiconductor superlattice with broken translational symmetry, is calculated analytically within linear response theory. We discuss the properties of these collective excitations in both radiative and non-radiative regimes of the electromagnetic spectra. W

R. T. Gangadhara, Shuji Deguchi, H. Lesch

Radiative transfer equations are derived and solved for the stimulated Raman scattering of water maser lines in the astrophysical plasmas with electron density of about 10^6 - 10^7 cm-3. In stimulated Raman scattering, the energy of water maser line is transferred to the side band modes: Stokes mode and anti-Stokes mode. The Stokes mode is easily produced by

A. Heidmann, P. F. Cohadon, M. Pinard

We study theoretically the internal thermal noise of a mirror coated on a plano-convex substrate. The comparison with a cylindrical mirror of the same mass shows that the effect on a light beam can be reduced by a factor 10, improving the sensitivity of high-precision optical experiments such as gravitational-wave interferometers.

J. Javier Brey, A. Prados, B. Sanchez-Rey

A simple lattice model is used to study compaction in granular media. As in real experiments, we consider a series of taps separated by large enough waiting times. The relaxation of the density exhibits the characteristic inverse logarithmic law. Moreover, we have been able to identify analytically the relevant time scale, leading to a relaxation law indepen

Olav F. Syljuasen

Generalized rules for building and flipping clusters in the quantum Monte Carlo loop algorithm are presented for the XXZ-model in a uniform magnetic field along the Z-axis. As is demonstrated for the Heisenberg antiferromagnet it is possible from these rules to select a new algorithm which performs significantly better than the standard loop algorithm in str

ZEUS Collaboration

The e^+p charged-current deep inelastic scattering cross sections, $dσ/dQ^2$ for Q^2 between 200 and 60000 GeV^2, and $dσ/dx$ and $dσ/dy$ for Q^2 > 200 GeV^2, have been measured with the ZEUS detector at HERA. A data sample of 47.7 pb^-1, collected at a center-of-mass energy of 300 GeV, has been used. The cross section $dσ/dQ^2$ falls by a factor of about 50

M. Hirayama, M. Ueno

A formula constituting the non-Abelian Stokes theorem for general semi-simple compact gauge groups is presented. The formula involves a path integral over a group space and is applicable to Wilson loop variables irrespective of the topology of loops. Some simple expressions analogous to the 't Hooft tensor of a magnetic monopole are given for the 2-form

M. Fleischhauer, M. D. Lukin, A. B. Matsko, M. O. Scully

We analyze the above-threshold behavior of a mirrorless parametric oscillator based on resonantly enhanced four wave mixing in a coherently driven dense atomic vapor. It is shown that, in the ideal limit, an arbitrary small flux of pump photons is sufficient to reach the oscillator threshold. We demonstrate that due to the large group-velocity delays associa

Mitsuhiro Arikawa, Takashi Yamamoto, Yasuhiro Saiga, Yoshio Kuramoto

Dynamical charge structure factor $N(Q,ω)$ with $Q$ smaller than the Fermi wave number is derived analytically for the one-dimensional supersymmetric t-J model with $1/r^2$ interaction. Strong spin-charge separation in dynamics is found. $N(Q,ω)$ with given electron density does not depend on the spin polarization for arbitrary size of the system. In the the

E. Babaev, H. Kleinert

For an electron gas with delta-function attraction we investigate the crossover from weak- to strong-coupling supercoductivity in two and three dimensions. We derive analytic expressions for the stiffness of phase fluctuations and set up effective XY-models which serve to determine nonperturbatively the temperature of phase decoherence where superconductivit

M. Machida, T. Koyama, A. Tanaka, M. Tachiki

In order to clarify the ``superradiant'' conditions for the moving Josephson vortices to excite in-phase AC electromagnetic fields over all junctions, we perform large scale simulations of realistic dimensions for intrinsic Josephson junctions under the layer parallel magnetic field. Three clear step-like structures in the I-V curve are observed abov

SAGE Collaboration

The solar neutrino capture rate measured by the Russian-American Gallium Experiment (SAGE) on metallic gallium during the period January 1990 through December 1997 is 67.2 (+7.2-7.0) (+3.5-3.0) SNU, where the uncertainties are statistical and systematic, respectively. This represents only about half of the predicted Standard Solar Model rate of 129 SNU. All

Mladen Pavicic

It is shown that a monolithic total-internal-reflection resonator can be used for energy-exchange-free detections of objects without recoils. Related energy-exchange-free detection of "welcher Weg" is discussed and an experiment with an atom interferometer is proposed. The obtained results are in agreement with quantum theory.

Mladen Pavicic

A method for preparing a loophole-free four-photon Bell experiments which requires a detection efficiency of 67% is proposed. It enables realistic detection efficiencies of 75% at a visibility of 85%. Two type-II crystals each down convert one correlated photon pair and we entangle one photon from one pair with one photon from the other pair on a highly tran

Mladen Pavicic

We present an experiment which prepare entanglement between photons that nowhere interacted and whose paths nowhere crossed. The experiment puts together two photons from two (non-maximal) singlet-like photon pairs and make them interfere at an asymmetrical beam splitter. As a result one finds polarization correlations between the other companion photons fro

E. G. Kalnins, W. Miller, Ye. M. Hakobyan, G. S. Pogosyan

This work is devoted to the investigation of the quantum mechanical systems on the two dimensional hyperboloid which admit separation of variables in at least two coordinate systems. Here we consider two potentials introduced in a paper of C.P.Boyer, E.G.Kalnins and P.Winternitz, which haven't yet been studied. We give an example of an interbasis expansi

Tal Mor, Daniel R. Terno

We consider a disentanglement process in which local properties of an entangled state are preserved, while the entanglement between the subsystems is erased. Sufficient conditions for a perfect disentanglement (into product states and into separable states) are derived, and connections to the conditions for perfect cloning and for perfect broadcasting are ob

Ye. M. Hakobyan, G. S. Pogosyan

In this article we analyze the isotropic oscillator system on the two-dimensional sphere in the spherical systems of coordinates. The expansion coefficients for transitions between three spherical bases of the oscillator are calculated. It is shown that these coefficients are expressed through the Clebsch-Gordan coefficients for SU(2) group analytically cont

Jiunn-Wei Chen, Martin J. Savage

The cross section for n+p -> d+gamma is calculated at energies relevant to big bang nucleosynthesis using the recently developed effective field theory that describes the two-nucleon sector. The E1 amplitude is computed up to NNNLO and depends only upon nucleon-nucleon phase shift data. In contrast, the M1 contribution is computed up to NLO, and the four-nuc

Sean Gavin, Claude Pruneau

We propose that dramatic changes in the variances and covariance of protons and antiprotons can result if baryons approach chemical equilibrium in nuclear collisions at RHIC. To explore how equilibration alters these fluctuations, we formulate both equilibrium and nonequilibrium hadrochemical descriptions of baryon evolution. Contributions to fluctuations fr

Kei Iida

The dispersion relation and damping rate of longitudinal color plasmons in finite strange quark matter (strangelets) are evaluated in the limits of weak coupling, low temperature, and long wavelength. The property of the QCD vacuum surrounding a strangelet makes the frequency of the plasmons nearly the same as the color plasma frequency of bulk matter. The p

G. A. Lalazissis, D. Vretenar, P. Ring

Properties of transitional Lu and spherical Ta ground-state proton emitters are calculated with the Relativistic Hartree Bogoliubov (RHB) model. The NL3 effective interaction is used in the mean-field Lagrangian, and pairing correlations are described by the pairing part of the finite range Gogny interaction D1S. Proton separation energies, ground-state quad

V. A. Karmanov

The wave function in relativity is defined, in four-dimensional space, on a space-like three-dimensional plane. The plane, most close to the time-like region, is the light-front plane $ct+z=0$. Corresponding dynamical approach - the light-front dynamics - has considerable advantages. We describe, in a field-theoretical framework, the construction of light-fr

K. S. Kim, L. E. Wright

We report a significant improvement of an approximate method of including electron Coulomb distortion in electron induced reactions at momentum transfers greater than the inverse of the size of the target nucleus. In particular, we have found a new parametrization for the elastic electron scattering phase shifts that works well at all electron energies great

L. G. Moretto, L. Phair, G. J. Wozniak

The resilience to averaging over an initial energy distribution of reducibility and thermal scaling observed in nuclear multifragmentation is studied. Poissonian reducibility and the associated thermal scaling of the mean are shown to be robust. Binomial reducibility and thermal scaling of the elementary probability are robust under a broad range of conditio

Feng Luo

We discuss some applications of an intrinsic multipication in the space of simple loops in a surface.

Carol E. Fan

A version of a conjecture of McMullen is as follows: Given a hyperbolizable 3-manifold M with incompressible boundary, there exists a uniform constant K such that if N is a hyperbolic 3-manifold homeomorphic to the interior of M, then the injectivity radius based at points in the convex core of N is bounded above by K. This conjecture suggests that convex co

Leonard M. Smiley

Some formulae are given for the enumeration of certain types of dissections of the convex (n+2)-gon by non-crossing diagonals. The classical Schroeder and Motzkin numbers are addressed using a cataloguing tool, the "reversive symbol". The elementary details are referred to three Web addresses.

Mirroslav Yotov

We study the algebraic properties of the generalized Futaki invariant of an almost Fano variety and prove that it is in fact a pushforward to a point of an appropriate equivariant Chow cohomology class of the variety. This allows us to use Bott-type formulae for calculating the invariant. We show this use on some examples.

John D. McCarthy

An interesting question in symplectic topology, which was posed by C. H. Taubes, concerns the topology of closed (i.e. compact and without boundary) connected oriented three dimensional manifolds whose product with a circle admits a symplectic structure. The only known examples of such manifolds are those which fiber over a circle. Taubes asked whether these

Q-Han Park, H. J. Shin

We generalize the Lund-Regge model for vortex string dynamics in 4-dimensional Minkowski space to the arbitrary n-dimensional case. The n-dimensional vortex equation is identified with a nonabelian sine-Gordon equation and its integrability is proven by finding the associated linear equations of the inverse scattering. An explicit expression of vortex coordi

K. Lee, Q-Han Park, H. J. Shin

We study the Lund-Regge equation that governs the motion of strings in a constant background antisymmetric tensor field by using the duality between the Lund-Regge equation and the complex sine-Gordon equation. Similar to the cases of vortex filament configurations in fluid dynamics, we find various exact solitonic string configurations which are the analogu

M. Gasperini

This is a contracted version of a series of lectures for graduate and undergraduate students given at the {\sl "VI Seminario Nazionale di Fisica Teorica"} (Parma, September 1997), at the Second Int. Conference {\sl "Around VIRGO"} (Pisa, September 1998), and at the Second {\sl SIGRAV} School on {\sl "Gravitational Waves in Astrophysics, C

E. Gozzi, D. Mauro

In this paper we re-express the Schouten-Nijenhuis, the Frölicher-Nijenhuis and the Nijenhuis-Richardson brackets on a symplectic space using the extended Poisson brackets structure present in the path-integral formulation of classical mechanics.

Alexios P. Polychronakos

We study a system of nonabelian anyons in the lowest Landau level of a strong magnetic field. Using diagrammatic techniques, we prove that the virial coefficients do not depend on the statistics parameter. This is true for all representations of all nonabelian groups for the statistics of the particles and relies solely on the fact that the effective statist

K. Schoutens

I comment on the paper hep-th/9808013 by A. Berkovich and B.M. McCoy.

Kevin Cahill

These notes are intended to provide an introduction to supersymmetry. The notes begin with supersymmetric quantum mechanics and the basic properties of spinor fields. The supersymmetry of simple theories of spin-zero and spin-one-half fields is discussed with emphasis upon the charges that generate the transformations of supersymmetry. Abelian and non-abelia

S. M. H. Wong

We examine the effects of color screening on the transition of a parton plasma into a hadron gas at RHIC energies. It is found that as expected, color screening posed itself as a significant barrier for hadronization. Parton-hadron conversion would therefore be delayed and prolonged when compared to that occuring in a vacuum. Due to the on-going expansion, t

R. Kinnunen, D. Denegri

We present a first study of the channel H, A -> tau+tau -> h+ + h- + X in CMS at high m(A) values where no triggering difficulties are expected with QCD jets. At present the tau selection is based solely on the presence of a hard isolated track in the "tau" jet, but further refinements based on calorimeter collimation or impact parameter selections a

Paramita Adhya, D. Rai Chaudhuri

We investigate the effect of B+L - violating anomalous generation of massive right-handed neutrinos on their decoupling, when the right-handed neutrino mass is considerably greater than the right-handed gauge boson masses. Considering normal annihilation channels, the Lee-Weinberg type of calculation, in this case, gives an upper bound of about 700 Gev, whic

A. Widom, Y. Srivastava, J. Swain

Up to second order in alpha, vacuum electro-magnetic corrections to weak interaction induced charged particle lifetimes have been previously studied. In the laboratory, stopped muon lifetimes are measured in a condensed matter medium whose radiation impedance differs from that of the vacuum. The resulting condensed matter corrections to first order in $α$ do

G. V. Vlasov

We develope a theory of sound in a relativistic superfluid with quantum vortices. The vortices are presented by vortex fluid. For a particular separable model we find new modes of which a non-relativistic superfluid is deprived.

Gregory Mahlon

We improve the McLerran-Venugopalan model by introducing a charge-density correlation function which is consistent with the observation that nucleons carry no net color charge. The infrared divergence in the transverse coordinates that was present in the McLerran-Venugoplan model is eliminated by the enforcement of color neutrality.

A. E. Bondar, S. I. Eidelman, A. I. Milstein, N. I. Root

We demonstrate that a simple model successfully describing experimental data for the process $\epm\to 4π$ can also qualitatively account for the data of CLEOII and ALEPH obtained recently for the decay $τ\to 4πν_τ$. The model is based on the assumption of the $a_1(1260)π$ and $ωπ$ dominance as intermediate states. Our observation is in contrast with the clai

M. Cacciari, F. Chlebana, L. Sinclair, M. Weber

We present a summary of the Hadronic Final States parallel sessions of the DIS99 Workshop. Topics were presented over two days and included both theoretical and experimental talks. Recent progress in the understanding of QCD in deep inelastic scattering, e^+e^- collisions, and in gamma and p collisions was discussed.

F. A. Harris

Recent results obtained from the BES psi(2S) data are summarized, including the measurement of the branching ratio of the J/psi to leptons, B(J/psi -> l^+ l^-) = 5.87 +/- 0.04 +/- 0.09, many psi(2S) and chi_c branching ratios, information on the rho-pi puzzle, and measurements of the mass of the chi_c0, m(chi_c0) = 3414.1 +/- 0.6 +/- 0.8 MeV, and the eta_c,

James E. Lidsey, Carlos Romero, Reza Tavakol, Steve Rippl

A little known theorem due to Campbell is employed to establish the local embedding of a wide class of 4-dimensional spacetimes in 5-dimensional Ricci-flat spaces. An embedding for the class of n-dimensional Einstein spaces is also found. The local nature of Campbell's theorem is highlighted by studying the embedding of some lower-dimensional spaces.

Brandon Carter

Superfluid condensates are known to occur in contexts ranging from laboratory liquid helium to neutron stars, and are also likely to occur in cosmological phenomena such as axion fields. In the zero temperature limit, such condensates are describable at a mesoscopic level by irrotational configurations of simple relativistic perfect fluid models. The general

Davide Turcato, Paul McFetridge, Fred Popowich, Janine Toole

We describe a method for automatically generating Lexical Transfer Rules (LTRs) from word equivalences using transfer rule templates. Templates are skeletal LTRs, unspecified for words. New LTRs are created by instantiating a template with words, provided that the words belong to the appropriate lexical categories required by the template. We define two meth

Tom Barclay Jim Gray Don Slutz

The TerraServer stores aerial, satellite, and topographic images of the earth in a SQL database available via the Internet. It is the world's largest online atlas, combining five terabytes of image data from the United States Geological Survey (USGS) and SPIN-2. This report describes the system-redesign based on our experience over the last year. It also

V. J. Goldman

I present a brief survey of important recent developments in the quantum Hall effect. The review covers both fractional and integer regimes, from an experimentalist's perspective. The topics include direct measurement of fractional charge, composite fermion Fermi surface, spin textures, and edge state (chiral Luttinger liquid) dynamics.

Anupam Garg

Certain spin Hamiltonians that give rise to tunnel splittings that are viewed in terms of interfering instanton trajectories, are restudied using a discrete WKB method, that is more elementary, and also yields wavefunctions and preexponential factors for the splittings. A novel turning point inside the classically forbidden region is analysed, and a general

Matthias H. Hettler, Peter J. Hirschfeld

We propose that the low temperature discrepancy between simple d-wave models of the microwave conductivity and existing experiments on single crystals of YBCO can be resolved by including the scattering of quasiparticles from "holes" of the order parameter at impurity sites. Within a framework proposed previously, we find in particular excellent agre

P. W. Brouwer, Yuval Oreg, B. I. Halperin

We study the statistical distribution of the ground state spin for an ensemble of small metallic grains, using a random-matrix toy model. Using the Hartree Fock approximation, we find that already for interaction strengths well below the Stoner criterion there is an appreciable probability that the ground state has a finite, nonzero spin. Possible relations

J. J. A. Baselmans, B. J. van Wees, T. M. Klapwijk

We have studied the critical current of a diffusive superconductor - normal metal - superconductor (SNS) Josephson junction as a function of the electron energy distribution in the normal region. This was realized in a 4 terminal device, in which a mesoscopic gold wire between two electron reservoirs is coupled in its center to two superconducting electrodes

Ingve Simonsen, Damien Vandembroucq, Stephane Roux

Electromagnetic wave scattering from a perfectly reflecting self-affine surface is considered. Within the framework of the Kirchhoff approximation, we show that the scattering cross section can be exactly written as a function of the scattering angle via a centered symmetric Levy distribution for general roughness amplitude, Hurst exponent and wavelength of

A. E. Allahverdyan, Th. M. Nieuwenhuizen

In a glassy system different degrees of freedom have well-separated characteristic times, and are described by different temperatures. The stationary state is essentially non-equilibrium. A generalized statistical thermodynamics is constructed and a universal variational principle is proposed. Entropy production and energy dissipation occur at a constant rat

Z. Ropka, Michalski, R. J. Radwanski

We have studied properties of the one-3d-electron cation (Ti 3+, V 4+ ions) under the action of the low-symmetry crystal field in the presence of the spin- orbit coupling. Very anomalous temperature dependences of the magnetic susceptibility chi (T) have been obtained as resulting from the off-cubic lattice distortion provided the intra-atomic spin-orbit cou

R. J. Radwanski, Z. Ropka

It has been shown that relativistic spin-orbit effects have enormous influence on the electronic structure of the correlated electron systems 3dn. The s-o coupling produces the fine electronic structure with a large number of low- energy, < 10 meV, localized states, These states affect enormously electronic and magnetic properties of 3d-ion compounds at low-

Mikito Koga

We study a realistic Kondo model for crystal field quartet ground states having magnetic and non-magnetic (quadrupolar) exchange couplings with conduction electrons, using the numerical renormalization group method. We focus on a local effect dependent on singlet excited states coupled to the quartet, which reduces the non-magnetic coupling significantly and

A. V. Lopatin, L. B. Ioffe

We investigate the barriers separating metastable states in the spherical p-spin glass model using the instanton method. We show that the problem of finding the barrier heights can be reduced to the causal two-real-replica dynamics. We find the probability for the system to escape one of the highest energy metastable states and the energy barrier correspondi

M. T. Batchelor, M. Maslen

We find families of integrable n-leg spin-1/2 ladders and tubes with general isotropic exchange interactions between spins. These models are equivalent to su(N) spin chains with N=2^n. Arbitrary rung interactions in the spin tubes and ladders induce chemical potentials in the equivalent spin chains. The potentials are n-dependent and differ for the tube and

B. P. van Zyl

We present a general approach for the construction of the exact local-energy-density functionals for a uniform N-dimensional electronic system in a magnetic field. For arbitrary dimension, we obtain explicit expressions for the matter, kinetic, and exchange density functionals. In the zero-field limit, we recover the usual N-dimensional Thomas-Fermi theory.

M. Watzlawek, G. Naegele

We report on calculations of the reduced sedimentation velocity $U/U_{0}$ in homogenous suspensions of strongly and weakly charged colloidal spheres as a function of particle volume fraction $ϕ$. For dilute suspensions of strongly charged spheres at low salinity, $U/U_{0}$ is well represented by the parametric form $1-pϕ^α$ with a fractional exponent $α=1/3$

Sang-Yoon Kim, Youngtae Kim

Bifurcations associated with stability of the saddle fixed point of the Poincaré map, arising from the unstable equilibrium point of the potential, are investigated in a forced Duffing oscillator with a double-well potential. One interesting behavior is the dynamic stabilization of the saddle fixed point. When the driving amplitude is increased through a thr

R. Muradian, S. Carneiro, R. Marques

In this letter we establish a connection between two-exponent radius-mass power laws for cosmic objects and previously proposed two-exponent Regge-like spin-mass relations. A new, simplest method for establishing the coordinates of Chandrasekhar and Eddington points is proposed.

David Kirkman, David Tytler, Scott Burles, Dan Lubin

We have discovered a third quasar absorption system which is consistent with a low deuterium to hydrogen abundance ratio, D/H = 3.4 times 10^-5. The z ~ 2.8 partial Lyman limit system towards QSO 0130-4021 provides the strongest evidence to date against large D/H ratios because the H I absorption, which consists of a single high column density component with

Stuart Bowyer, Thomas W. Berghoefer, Eric Korpela

We report a new analysis of diffuse EUV emission in clusters of galaxies. We find the cluster emission is strongly influenced by the variation of the telescope sensitivity over the field of view and upon the details of the subtraction of the EUV emission for the X-ray plasma. We investigate these effects on Abell 1795, Abell 2199, and the Coma cluster. When

G. Setti, G. Brunetti, A. Comastri

It is pointed out that copius X-rays from the lobes of FRII radio galaxies are expected as a natural consequence of the unification linking FRIIs and radio-loud quasars. The detection of extended X-ray emission from 3C 219, likely due to Inverse Compton scattering of the IR photons from a hidden quasar with the relativistic electrons in the lobes, provides t

T. Belloni, S. Dieters, M. E. van den Ancker, R. P. Fender

We present the results of the analysis of RXTE, BATSE and optical/infrared data of the 1998 outburst of the X-ray transient system XTE J0421+560 (CI Cam). The X-ray outburst shows a very fast decay (initial e-folding time ~0.5 days, slowing down to ~2.3 days). The X-ray spectrum in the 2-25 keV band is complex, softening considerably during decay and with st

J. M. Shull, D. Roberts, M. L. Giroux, S. V. Penton

We compute the ionizing radiation field at low redshift, arising from Seyferts, QSOs, and starburst galaxies. This calculation combines recent Seyfert luminosity functions, extrapolated ultraviolet fluxes from our IUE-AGN database, and a new intergalactic opacity model based on Hubble Space Telescope and Keck Ly-alpha absorber surveys. At z = 0 for AGN only,

P. N. Appleton, V. Charmandaris, C. Horellou, I. F. Mirabel

We present the first mid-infrared (Mid-IR) ($\lambda5-15μ$m) and radio continuum ($λλ$20,~6 and 3.6 cm) observations of the star-forming collisional ring galaxy VII Zw 466 and its host group made with the Infrared Space Observatory and the NRAO Very Large Array. A search was also made for CO line emission in two of the galaxies with the Onsala 20m radio tele

I. Owsianik, J. E. Conway, A. G. Polatidis

We present an analysis of multi-epoch global VLBI observations of the Compact Symmetric Objects: 2352+495 and 0710+439 at 5 GHz. Analysis of data spread over almost two decades shows strong evidence for an increase in separation of the outer components of both sources at a rate of ~0.2 h^{-1} c (for q_{0}=0.5 and H_{0}=100 h kms^{-1} Mpc^{-1}). Dividing the

Stefanie Komossa, Hans Boehringer, John P. Huchra

We present an investigation of the X-ray properties of 13 LINERs based on ROSAT all-sky survey and pointed PSPC and HRI observations. Several sources are studied for the first time in X-rays. The X-ray spectra are best described by a powerlaw with photon index Gamma ~ -2.0 or thermal emission from gas with very subsolar abundances. The luminosities range bet

S. R. Dicker, S. J. Melhuish, R. D. Davies, C. M. Gutierrez

The paper presents the first results obtained with the Jodrell Bank - IAC two-element 33 GHz interferometer. The instrument was designed to measure the level of the Cosmic Microwave Background (CMB) fluctuations at angular scales of 1 - 2 degrees. The observations analyzed here were taken in a strip of the sky at Dec = +41 deg with an element separation of 1

W. Benz, E. Asphaug

We use a smooth particle hydrodynamics method (SPH) to simulate colliding rocky and icy bodies from cm-scale to hundreds of km in diameter, in an effort to define self-consistently the threshold for catastrophic disruption. Unlike previous efforts, this analysis incorporates the combined effects of material strength (using a brittle fragmentation model) and

Rosa M. Gonzalez Delgado, Claus leitherer, Timothy Heckman

We present evolutionary stellar population synthesis models to predict the spectrum of a single-metallicity stellar population, with a spectral sampling of 0.3 A in five spectral regions between 3700 and 5000 A. The models, which are optimized for galaxies with active star formation, synthesize the profiles of the hydrogen Balmer series (Hb, Hg, Hd, H8, H9,

Rosa M. Gonzalez Delgado, Claus Leitherer

We present a grid of synthetic profiles of stellar H Balmer and HeI lines at optical wavelengths with a sampling of 0.3 A. The grid spans a range of effective temperature 4000 K < Teff < 50000 K, and gravity 0.0 < log g < 5.0 at solar metallicity. For Teff > 25000 K, NLTE stellar atmosphere models are computed using the code TLUSTY (Hubeny 1988). For cooler

J. Chiang, C. S. Reynolds, O. M. Blaes, M. A. Nowak

We present simultaneous observations by EUVE, ASCA, and RXTE of the type~1 Seyfert galaxy NGC 5548. These data indicate that variations in the EUV emission (at $\sim 0.2 $keV) appear to lead similar modulations in higher energy ($\ga 1 $keV) X-rays by $\sim$10--30 ks. This is contrary to popular models which attribute the correlated variability of the EUV, U

G. Pietrzynski, A. Udalski

We present the list of potential multiple star clusters from the central part of the SMC. Presented systems were selected from the catalog of star clusters from the SMC. We find 23 suspected cluster pairs and 4 triple systems. The statistical analysis suggests that many of them may constitute physical systems. Size, equatorial coordinates and age of presente

G. Pietrzynski, A. Udalski

We present determination of age of clusters from 2.4 square degree region of the SMC bar. The photometric data were taken from the BVI maps of the SMC and catalog of clusters in this galaxy obtained during the OGLE-II microlensing survey. For 93 well populated SMC clusters their age is derived with the standard procedure of isochrone fitting. The distributio

M. Disertori, V. Rivasseau

This is a companion paper to cond-mat/9907130. Using the method of continuous renormalization group around the Fermi surface and the results of cond-mat/9907130, we achieve the proof that a two-dimensional jellium interacting system of Fermions at low temperature T is a Fermi liquid (analytic in the coupling constant g) for g < const./|log T| and satisfying

M. Disertori, V. Rivasseau

Using the method of continuous renormalization group around the Fermi surface, we prove that a two-dimensional jellium interacting system of Fermions at low temperature T is a Fermi liquid (analytic in the coupling constant g) for g < const/|logT|, and satisfying uniform bounds on the first and second derivatives of the selfenergy. This bound is also a step

Daniel Loss, Eugene V. Sukhorukov

Addressing the feasibilty of quantum communication with electrons we consider entangled spin states of electrons in a double-dot which is weakly coupled to in--and outgoing leads. We show that the entanglement of two electrons in the double-dot can be detected in mesoscopic transport and noise measurements. In the Coulomb blockade and cotunneling regime the

Jongsoo Yoon, C. C. Li, D. Shahar, D. C. Tsui

A magnetic field applied parallel to the two-dimensional hole system in the GaAs/AlGaAs heterostructure, which is metallic in the absence of an external magnetic field, can drive the system into insulating at a finite field through a well defined transition. The value of resistivity at the transition is found to depend strongly on density.

John H. Schwarz

The T-dual formulation of Type I superstring theory, sometimes called Type I&#39; theory, has a number of interesting features. Here we review some of them including the role of D0-branes and D8-branes in controlling possible gauge symmetry enhancement.

Wayne Hu

Secondary CMB anisotropies and polarization provide a laboratory to study structure formation in the reionized epoch. We consider the kinetic Sunyaev-Zel&#39;dovich effect from mildly nonlinear large-scale structure and show that it is a natural extension of the perturbative Vishniac effect. If the gas traces the dark matter to overdensities of order 10, as

C. S. Lam, Gregory Mahlon

We improve the McLerran-Venugopalan model for the gluon distribution functions in very large nuclei by imposing the condition that the nucleons should be color neutral. We find that enforcing color neutrality cures the infrared divergences in the transverse coordinates which are present in the McLerran-Venugopalan model. Since we obtain well-defined expressi

Hongwei Yu, L. H. Ford

We discuss how compactified extra dimensions may have potentially observable effects which grow as the compactification scale decreases. This arises because of lightcone fluctuations in the uncompactified dimensions which can result in the broadening of the spectral lines from distant sources. We analyze this effect in a five dimensional model, and argue tha

Alexander D. Mirlin

The article reviews recent developments in the theory of fluctuations and correlations of energy levels and eigenfunction amplitudes in diffusive mesoscopic samples. Various spatial geometries are considered, with emphasis on low-dimensional (quasi-1D and 2D) systems. Calculations are based on the supermatrix sigma-model approach. The method reproduces, in s

Kevin L. Haglin

Production of J/$ψ$ from nucleus-nucleus reactions depends sensitively on the dissociation cross section with light hadrons. Effective lagrangian methods are used to describe the hadronic degrees of freedom, including strangeness and charm. Cross sections with pions, rho mesons, kaons and nucleons having magnitudes 4--8 mb are found, and with steep threshold

A. Pagnani, G. Parisi, F. Ricci-Tersenghi

We numerically study a disordered model for the RNA secondary structure and we find that it undergoes a phase transition, with a breaking of the replica symmetry in the low temperature region (like in spin glasses). Our results are based on the exact evaluation of the partition function.