October 1999 arXiv papers — page 6

S. P. Kim, A. E. Santana, F. C. Khanna

Open systems acquire time-dependent coupling constants through interaction with an external field or environment. We generalize the Lewis-Riesenfeld invariant theorem to open system of quantum fields after second quantization. The generalized invariants and thereby the quantum evolution are found explicitly for time-dependent quadratic fermionic systems. The

Brian S. Mason, Steven T. Myers

We define a 90% complete, volume-limited sample of 31 z<0.1 x-ray clusters and present a systematic analysis of public ROSAT PSPC data on 22 of these objects. Our efforts are undertaken in support of the Penn/OVRO SZE survey, and to this end we present predictions for the inverse Compton optical depth towards all 22 of these clusters. We have performed detai

M. Patra, C. W. J. Beenakker

We analyse how nonclassical features of squeezed radiation (in particular the sub-Poissonian noise) are degraded when it is transmitted through an amplifying or absorbing medium with randomly located scattering centra. Both the cases of direct photodetection and of homodyne detection are considered. Explicit results are obtained for the dependence of the Fan

Ali Mostafazadeh

We use the Rayleigh-Schrödinger perturbation theory to calculate the corrections to the adiabatic geometric phase due to a perturbation of the Hamiltonian. We show that these corrections are at least of second order in the perturbation parameter. As an application of our general results we address the problem of the adiabatic geometric phase for a one-dimens

R. R. Puri, S. Arun Kumar, R. K. Bullough

We study the statistics of the atoms emerging from the cavity of a micromaser in a dynamical, discrete-time `stroboscopic&#39; description which takes into account the measurements made, in general, with imperfect efficiencies, on the states of the outcoming atoms. Inverted atoms enter stochastically, in general, with a binomial distribution in discrete time

S. Seshadri, S. Lakshmibala, V. Balakrishnan

Revivals of the coherent states of a deformed, adiabatically and cyclically varying oscillator Hamiltonian are examined. The revival time distribution is exactly that of Poincaré recurrences for a rotation map: only three distinct revival times can occur, with specified weights. A link is thus established between quantum revivals and recurrences in a coarse-

S. Seshadri, S. Lakshmibala, V. Balakrishnan

Wave packets in a system governed by a Hamiltonian with a generic nonlinear spectrum typically exhibit both full and fractional revivals. It is shown that the latter can be eliminated by inducing suitable geometric phases in the states, by varying the parameters in the Hamiltonian cyclically with a period T. Further, with the introduction of this natural tim

C. I. Barbosa, H. L. Harney

Bayesian inference is applied to the level fluctuations of two coupled microwave billiards in order to extract the coupling strength. The coupled resonators provide a model of a chaotic quantum system containing two coupled symmetry classes of levels. The number variance is used to quantify the level fluctuations as a function of the coupling and to construc

Nir Barnea, Winfried Leidemann, Giuseppina Orlandini

The method of effective interaction, traditionally used in the framework of an harmonic oscillator basis, is applied to the hyperspherical formalism of few-body nuclei (A=3-6). The separation of the hyperradial part leads to a state dependent effective potential. Undesirable features of the harmonic oscillator approach associated with the introduction of a s

Omar Mustafa, Thabit Barakat

The shifted-i expansion technique (SLET) is extended to solve for Dirac particle trapped in spherically symmetric scalar and/or 4-vector potentials. A parameter λ=0,1 is introduced in such a way that one can obtain the Klein-Gordon (KG) bound states from Dirac bound states. The 4-vector Coulomb, the scalar linear, and the equally mixed scalar and 4-vector po

R. Caseiro, J. -P. Francoise

The main result of this paper is the evidence of an explicit linearization of dynamical systems of Ruijsenaars-Schneider type and of the perturbations introduced by F. Calogero of these systems with all orbits periodic of same period. Several other systems share the existence of this explicit linearization, among them, the Calogero-Moser system (with and wit

Bjorn Poonen

We prove that for any t in Q, the curve 5 x^3 + 9 y^3 + 10 z^3 + 12((t^12-t^4-1)/(t^12-t^8-1))^3 (x+y+z)^3 = 0 in P^2 is a genus 1 curve violating the Hasse principle. An explicit Weierstrass model for its Jacobian E_t is given. The Shafarevich-Tate group of each E_t contains a subgroup isomorphic to Z/3 x Z/3.

S. Penati, A. Santambrogio, D. Zanon

We compute two-point functions of chiral operators Tr \Phi^3 in {\cal N}=4 SU(N) supersymmetric Yang-Mills theory to the order g^4 in perturbation theory. We perform explicit calculations using {\cal N}=1 superspace techniques and find that perturbative corrections to the correlators vanish for all N. While at order g^2 the cancellations can be ascribed to t

Avinash Dhar, Gautam Mandal, Spenta R. Wadia, K. P. Yogendran

The D1/D5 system is considered in the presence of the NS B field. An explicit supergravity solution in the asymptotically flat and near horizon limits is presented. Explicit mass formulae are presented in both cases. This solution has no D3 source branes and represents a true bound state of the D1/D5 system. We study the motion of a separated D1-brane in the

Gysbert Zwart

String theory compactified on a three-torus possesses an SL(5,Z) U-duality group. We investigate the realisation of this symmetry on the Born-Infeld theory on a three-brane, and discuss a U-duality covariant formulation of the BPS sector of the theory where the rank of the gauge group is treated on an equal footing with the fluxes.

M. Nishimura, Y. Tanii

It is shown that local symmetry transformations of the maximal AdS supergravity in seven-dimensional anti de Sitter space induce those of the N=(2,0) conformal supergravity on the six-dimensional boundary at infinity. Boundary values of the AdS supergravity fields form a supermultiplet of the conformal supergravity.

Jan Govaerts

Recent developments concerning canonical quantisation and gauge invariant quantum mechanical systems and quantum field theories are briefly discussed. On the one hand, it is shown how diffeomorphic covariant representations of the Heisenberg algebra over curved manifolds of non trivial topology involve topology classes of flat U(1) bundles. On the other hand

Georges Ripka, Bojan Golli

A chiral quark model is described which is regularized in terms of Lorentz invariant non-local interactions. The model is regularized to all loop orders and it ensures the proper quantization of the baryon number. It sustains bound hedgehog solitons which, after suitable centre of mass corrections, can adequately describe the nucleon.

Mike J. Cai, Mary K. Gaillard

The inflation model of Gaillard, Lyth and Murayama is revisited, with a systematic scan of the parameter space for dilaton stabilization during inflation.

S. Mrenna, G. L. Kane, Lian-Tao Wang

Once superpartners are discovered at colliders, the next challenge will be to determine the parameters of the supersymmetric Lagrangian. We illustrate how the relative phases of the gluino, SU(2), and U(1) gauginos and the Higgsino mass parameter mu can be measured at a hadron collider without ad hoc assumptions about the underlying physics, focusing on Ferm

I. Akushevich, A. Ilyichev, N. Shumeiko

The one-loop NLO radiative corrections to the observables in polarized DIS using assumption that a quark is an essential massive particle are considered. If compared with classical QCD formulae the obtained results are identical for the unpolarized and different for polarized sum rules, that can be explained as the influence of the finite quark mass effects

F. Del Aguila, J. Gluza, M. Zralek

We study the simplest Standard Model estension with only one extra right-handed neutrino. In this case there are two massless $m_{1,2}$ and two massive $m_{3,4}$ neutrinos, and in principle both solar and atmospheric anomalies can be described in two different scenarios, $m_3 << m_4$ (scheme I) and $m_3 \simeq m_4$ (scheme II). However, neither bi-maximal mi

Arnon Dar, A. De Rújula, Ulrich Heinz

Experiments at the Brookhaven National Laboratory will study collisions between gold nuclei at unprecedented energies. The concern has been voiced that ``strangelets&#39;&#39;-hypothetical products of these collisions - may trigger the destruction of our planet. We show how naturally occurring heavy-ion collisions can be used to derive a safe and stringent u

Toshitaka Tatsumi

Usually it is believed that the Hartree-Fock state of quark matter is a Fermi gas state with no polarisation of spins. We examine the possibility of the polarised quark liquid interacting with the one-gluon-exchange interaction. It is suggested that the Hartree-Fock state shows a spontaneous magnetic instability at low densities through the same mechanism as

Avinash Khare

Exactly twenty five years ago the world of high energy physics was set on fire by the discovery of a new particle with an unusually narrow width at 3095 MeV, known popularly as the $J/Ψ$ revolution. This discovery was very decisive in our understanding as well as formulating the current picture regarding the basic constituents of nature. I look back at the d

Guey-Lin Lin

We compute the branching ratio of inclusive $B \to η&#39; X_s$ decay based upon the QCD anomaly mechanism: $b\to s+g^*\to s+g+η&#39;$. To obtain a reliable $B \to η&#39; X_s$ branching ratio, we calculate the $b\to s+g^*$ form factors up to the next-to-leading-logarithmic(NLL) approximation. We point out that the Standard Model prediction for $B\to η&#39; X_

Kang Young Lee, Seong Chan Park, H. S. Song, Jeonhyeon Song

Top quark pair production at photon-photon colliders is studied in low scale quantum gravity scenario. From the dependence of the cross sections on the spin configuration of the top quark and anti-quark, we introduce a new observable, top spin asymmetry. It is shown that there exists a special top spin basis where with the polarized parent electron beams the

B. Dressler, K. Goeke, M. V. Polyakov, P. Schweitzer

We investigate the role of the flavor asymmetry of the nucleon&#39;s polarized antiquark distributions in Drell-Yan lepton pair production in polarized nucleon-nucleon collisions at HERA (fixed-target) and RHIC energies. It is shown that the large polarized antiquark flavor asymmetry predicted by model calculations in the large-N_c limit (chiral quark-solito

Jifeng Yang

In the full effective potential (EFP) approach, we find that spontaneous symmetry breaking (SSB) can, with the convexity of the full EFP, lead to the prediction of the IR confinement of Higgs particles, adding difficulty to the experimental identification of Higgs particles. The short distance behaviors remain intact. The whole presentation is given in the u

Robert G. Edwards, Urs M. Heller, Joe Kiskis, Rajamani Narayanan

We compute the low lying spectrum of the overlap Dirac operator in the deconfined phase of finite-temperature quenched gauge theory. It suggests the existence of a chiral condensate which we confirm with a direct stochastic estimate. We show that the part of the spectrum responsible for the chiral condensate can be understood as arising from a dilute gas of

H. Neuberger

This introductory presentation describes the Overlap Dirac Operator, why it could be useful in numerical QCD, and how it can be implemented.

L3 Collaboration

A search for the lightest neutral scalar and neutral pseudoscalar Higgs bosons in the Minimal Supersymmetric Standard Model is performed using 176.4 pb^-1 of integrated luminosity collected by L3 at a center-of-mass energy of 189 GeV. No signal is observed, and the data are consistent with the expected Standard Model background. Lower limits on the masses of

The SELEX Collaboration, U. Dersch

Total cross sections for Sigma- and pi- on beryllium, carbon, polyethylene and copper as well as total cross sections for protons on beryllium and carbon have been measured in a broad momentum range around 600GeV/c. These measurements were performed with a transmission technique adapted to the SELEX hyperon-beam experiment at Fermilab. We report on results o

Akos Csilling

The reaction e+ e- -> e+ e- gamma* gamma* -> e+ e- hadrons is analysed for quasi-real virtual photons using data collected by the L3 detector during the LEP high energy runs at sqrt(s) = 183 and 189 GeV. Preliminary results on the cross sections sigma(e+e- -> e+e- hadrons) and sigma(gamma gamma -> hadrons) are given in the interval 5 GeV < W_{gamma gamma} <

Alessandro P. S. de Moura, Patricio S. Letelier

We study the motion of light in the gravitational field of two Schwarzschild black holes, making the approximation that they are far apart, so that the motion of light rays in the neighborhood of one black hole can be considered to be the result of the action of each black hole separately. Using this approximation, the dynamics is reduced to a 2-dimensional

Giovanni Amelino-Camelia

A handful of recent papers has been devoted to proposals of experiments capable of testing some candidate quantum-gravity phenomena. These lecture notes emphasize those aspects that are most relevant to the questions that come to mind when one is exposed for the first time to these research developments: How come theory and experiments are finally meeting in

J. Katz, J. Bicak, D. Lynden-Bell

Conformastationary metrics have been derived by Perjes and by Israel and Wilson as source-free solutions of the Einstein-Maxwell equations. By analogy with the conformastatic metrics which have charged dust sources it was assumed that conformastationary metrics would be the external metrics of charged dust in steady motion. However for axially symmetric conf

Francis J. Alexander, Ulrich H. Gerlach

The Maxwell field equations relative to a uniformly accelerated frame, and the variational principle from which they are obtained, are formulated in terms of the technique of geometrical gauge invariant potentials. They refer to the transverse magnetic (TM) and the transeverse electric (TE) modes. This gauge invariant &#34;2+2&#34; decomposition is used to s

Jacek Jezierski

The energy at null infinity is presented with the help of a simple example of a massless scalar field in Minkowski spacetime. It is also discussed for Einstein gravity. In particular, various aspects of the loss of the energy in the radiating regime are shown.

Matthias Arnsdorf

We discuss the action of the configuration operators of loop quantum gravity. In particular, we derive the generalised eigenbasis for the Wilson loop operator and show that the transformation between this basis and the spin-network basis is given by an expansion in terms of Chebyshev polynomials. These results are used to construct states which approximate c

Shmuel Kaniel, Yakov Itin

A scalar model of gravity is considered. We propose Lorentz invariant field equation $\square f = kη_{ab}f_{,a}f_{,b}$. The aim of this model is to get, approximately, Newton&#39;s law of gravity. It is shown that $f=-\frac 1k\ln(1-k\frac mr)$ is the unique spherical symmetric static solution of the field equation. $f$ is taken to be the field of a particle

Daniel Cartin

Recently, there has been a revival of interest in the Lanczos potential of the Weyl conformal tensor. Previous work by Novello and Neto has been done with the linearized Lanczos potential as a model of a spin-2 field, which depends on a massless limit of the field. In this paper, we look at an action based on a massless potential, and show that it is classic

Mark-Jan Nederhof

Several methods are discussed that construct a finite automaton given a context-free grammar, including both methods that lead to subsets and those that lead to supersets of the original context-free language. Some of these methods of regular approximation are new, and some others are presented here in a more refined form with respect to existing literature.

Prasan Roy, S. Seshadri, S. Sudarshan, Siddhesh Bhobe

Complex queries are becoming commonplace, with the growing use of decision support systems. These complex queries often have a lot of common sub-expressions, either within a single query, or across multiple such queries run as a batch. Multi-query optimization aims at exploiting common sub-expressions to reduce evaluation cost. Multi-query optimization has h

Victor Gurarie, Yong Baek Kim

The double-layer electron system with total filling factor $ν=1/2$ can be regarded as two separate Fermi-liquid-like states with $ν=1/4$ when the layer separation is sufficiently large and there is no tunneling. The weak tunneling in this state suffers an orthogonality catastrophe and it becomes irrelevant. Using the symmetric and antisymmetric combinations

T. A. S. Haddad, S. T. R. Pinho, S. R. Salinas

We investigate the effects of geometric fluctuations, associated with aperiodic exchange interactions, on the critical behavior of $q$-state ferromagnetic Potts models on generalized diamond hierarchical lattices. For layered exchange interactions according to some two-letter substitutional sequences, and irrelevant geometric fluctuations, the exact recursio

D. C. Johnston

Experiments of various types on the metallic transition metal oxide compound LiV_{2}O_{4} with the fcc normal-spinel structure are reviewed. The low-temperature T < 10 K data consistently indicate heavy fermion (HF) behaviors characteristic of those of the heaviest-mass f-electron HF compounds. A crossover is observed above about 50 K in the magnetic suscept

E. Ya. Sherman, M. Fischer, P. Lemmens, P. H. M. van Loosdrecht

We show that the asymmetric crystal environment of the V site in the ladder compound NaV$_{2}$O$_{5}$ leads to a strong coupling of vanadium 3d electrons to phonons. This coupling causes fluctuations of the charge on the V ions, and favors a transition to a charge-ordered state at low temperatures. In the low temperature phase the charge fluctuations modulat

F. Cordero, R. Cantelli, M. Ferretti

The anelastic spectrum of La{2-x}Sr{x}CuO{4} (x = 0, 0.008, 0.019, 0.032) has been measured down to 1.5 K, in order to see the effect of doping on the intrinsic lattice fluctuations already found in stoichiometric La{2}CuO{4}, and identified with tunneling driven tilt modes of the O octahedra. Slight doping with Sr causes a drastic increase of the transition

S. Brazovski, N. Kirova

We suggest a theoretical picture for distributions of plastic deformations experienced by a sliding Charge Density Wave in the course of the conversion from the normal current at the contact to the collective one in the bulk. Several mechanisms of phase slips via creation and proliferation of dislocations are compared. The results are applied to space resolv

T. Rejec, A. Ramsak, J. H. Jefferson

The conductance through a quantum wire of cylindrical cross section and a weak bulge is solved exactly for two electrons within the Landauer-Buettiker formalism. We show that this &#39;open&#39; quantum dot exhibits spin-dependent Coulomb blockade resonances resulting in two anomalous structure on the rising edge to the first conductance plateau, one near 0.

P. N. Timonin

A mean-field model of Ising spin glass with the Hamiltonian being a sum of the infinite-range ferromagnetic and random antiferromagnetic interactions is studied. It is shown that this model has phase transition in external magnetic field into inergodic spin glass phase with a number of metastable states. The thermodynamic properties of metastable states are

Dirk Reith, Florian Mueller-Plathe

The aim of this study is to understand deeper the thermal diffusion transport process (Ludwig-Soret effect) at the microscopic level. For that purpose, the recently developed reverse nonequilibrium molecular dynamics method was used to calculate Soret coefficients of various systems in a systematic fashion. We studied binary Lennard-Jones (LJ) fluids near th

N. Gov, E. Akkermans

We propose a new theoretical approach to the excitation spectrum of superfluid ${^4}He$. It is based on the assumption that, in addition to the usual Feynman density fluctuations, there exist localized modes which describe the short range behaviour in the liquid associated with microscopic cores of quantiz ed vortices. We describe in a phenomenological way t

J. M. van Ruitenbeek

The electrical transport properties of atomic-scale conductors are reviewed, with an emphasis on the relations of this problem with studies on quantum size effects in metallic clusters. A brief introduction is given of the natural formalism for discussing electron transport in ballistic conductors: the Landauer theory. After introducing the experimental tech

H. Kachkachi, M. Nogues, E. Tronc, D. A. Garanin

We study the finite-size and surface effects on the thermal and spatial behaviors of the magnetisation of a small magnetic particle. We consider two systems: 1) A box-shaped isotropic particle of simple cubic structure with either periodic or free boundary conditions. This case is treated analytically using the isotropic model of D-component spin vectors in

N. Gov, E. Polturak

We propose a new way to treat nuclear magnetism of solid $^{3}$He. We argue that the magnetic interaction arises indirectly as a consequence of correlated zero-point motion of the ions. This motion lowers the energy of the ground state, and results in a coherent state of oscillating electric dipoles. Distortion of the electronic wavefunctions leads to hyperf

Satoshi Ishizaka, Kazuo Nakamura

It is clarified for the first time that solitons originating from the dipolar interaction in ferromagnetic nano-particle arrays are stably created. The characteristics can be well controlled by the strength of the dipolar interaction between particles and the shape anisotropy of the particle. The soliton can propagate from a particle to a neighbor particle a

Saburo Takahashi, Hiroshi Imamura, Sasamichi Maekawa

We theoretically study the spin-dependent transport in a ferromagnet/superconductor/ferro-magnet double barrier tunnel junction. The spin-polarized tunneling currents give rise to spin imbalance in the superconductor. The resulting nonequilibrium spin density suppresses the superconductivity with increase of the tunneling currents. We focus on the effect of

Boyu Hou, Kangjie Shi, Ruihong Yue, Shaoyou Zhao

In this paper, we discuss the effect of the arbitrary spin impurities to the spin-1/2 and spin-1 XXZ model. The effect of ground state, the free energy, the magnetic susceptibility, the specific heat and the Kondo temperature are given by using the thermodynamic Bethe ansatz equation.

Andreas Mielke

A Hubbard model with a N_d-fold degenerate single-particle ground state has ferromagnetic ground states if the number of electrons is less or equal to N_d. It is shown rigorously that the local stability of ferromagnetism in such a model implies global stability: The model has only ferromagnetic ground states, if there are no single spin-flip ground states.

Boyu Hou, Kangjie Shi, Ruihong Yue, Shaoyou Zhao

In this paper, we show the integrability of spin-1/2 XXZ Heisenberg chain with two arbitrary spin boundary Impurities. By using the fusion method, we generalize it to the spin-1 XXZ chain. Then the eigenvalues of Hamiltonians of these models are obtained by the means of Bethe ansatz method.

Gautam I. Menon, Chandan Dasgupta, T. V. Ramakrishnan

We study muon-spin rotation (muSR) spectra in the mixed phase of highly anisotropic layered superconductors, specifically Bi_2+xSr_2-xCaCu_2O_8+delta (BSCCO), by modeling the fluid and solid phases of pancake vortices using liquid-state and density functional methods. The role of thermal fluctuations in causing motional narrowing of muSR lineshapes is quanti

Leonid P. Pryadko, Efrat Shimshoni, Assa Auerbach

We study a geometry-dependent effect of long-range Coulomb interactions on quantum Hall (QH) tunneling junctions. In an X-shaped geometry, duality relates junctions with opening angles alpha and (pi - alpha). We prove that duality between weak tunneling and weak backscattering survives in the presence of long range interactions, and that their effects are pr

Karsten Flensberg, Qian Niu, Michael Pustilnik

Single-electron transport driven by surface acoustic waves (SAW) through a narrow constriction, formed in two-dimensional electron gas, is studied theoretically. Due to long-range Coulomb interaction, the tunneling coupling between the electron gas and the moving minimum of the SAW-induced potential rapidly decays with time. As a result, nonadiabaticiy sets

Alessandro P. S. de Moura, Patricio S. Letelier

We study the planar motion of test particles in gravitational fields produced by an external material halo, of the type found in many astrophysical systems, such as elliptical galaxies and globular clusters. Both the Newtonian and the general-relativistic dynamics are examined, and in the relativistic case the dynamics of both massive and massless particles

Andrew E. Dolphin

HST F555W and F814W photometry of a portion of the WLM galaxy are presented. The distance modulus is determined via fitting of the entire color-magnitude diagram to be (m-M)_0 = 24.88 +/- 0.09, which is consistent with the RGB tip distance. The galaxy&#39;s measurable star formation history appears to have begun no more than 12 Gyr ago, with about half of WL

V. Celebonovic

The forms of two astrophysically applicable equations of state (EOS) are compared: the EOS proposed within the semiclassical theory of dense matter developed by P.Savic and R.Kasanin,and the universal equation of state introduced by Vinet et al.Some similarities between them are discussed and possibilities of astrophysical tests are pointed out.

B. T. Gaensicke, K. Beuermann, D. de Martino, H. -C. Thomas

We present low-state IUE spectroscopy of the ROSAT-discovered polar RXJ1313.2-3259. The SWP spectrum displays a broad Lyman alpha absorption profile, which can be fitted with a two-temperature model of a white dwarf of Twd=15000K with a hot spot of Tspot=34000K which covers f~0.01 of the white dwarf surface. The white dwarf temperature is atypically low for

Renee C. Kraan-Korteweg

A deep optical galaxy search in the southern Milky Way - aimed at reducing the width of the Zone of Avoidance - revealed 3279 galaxy candidates above the diameter limit of D > 0.2 arcmin, of which only 112 (3.4%) were previously catalogued. The surveyed region (266 < l < 296 and -10 < b < +8) lies in the extension of the Hydra and Antlia clusters - where a s

A. M. Khokhlov

Thermonuclear explosions of Type Ia supernovae (SNIa) involve turbulent deflagrations, detonations, and possibly a deflagration-to-detonation transition. A phenomenological delayed detonation model of SNIa successfully explains many observational properties of SNIa including monochromatic light curves, spectra, brightness - decline and color - decline relati

A. Pospieszalska-Surdej, J. Surdej, A. Detal, C. Jean

It is now possible to directly access, via the Internet, a bibliographical database on Gravitational Lensing (GL) literature. The Interactive Gravitational Lensing Bibliography (IGLB) totalizes more than 2400 titles of published articles in scientific journals and meeting proceedings (except those fully dedicated to Gravitational Lenses) as well as papers su

C. Jean, J. -F. Claeskens, J. Surdej

A 4-m International Liquid Mirror Telescope (ILMT) is being built in the north of Chile by an international consortium and will become operational in two years from now. We present here a short description of the telescope as well as estimates of the microlensing, macrolensing and weak lensing effects expected from a deep, multicolor imaging survey made with

I. Panchenko

We estimate the relativistic binaries merger rate and redshift distribution population synthesis of an ensemble of evolving close binaries. Results of such simulations definitely depend on the cosmic star formation rate history, which is different in galaxies of different types. This leads to a difference in merger rate in spiral and elliptical galaxies, whi

R. P. Kudritzki, J. Puls, D. J. Lennon, K. A. Venn

The Balmer lines of four A Ia - supergiants (spectral type A0 to A3) and fourteen B Ia and Ib - supergiants (spectral type B0 to B3) in the solar neighbourhood are analyzed by means of NLTE unified model atmospheres to determine the properties of their stellar winds, in particular their wind momenta. As in previous work for O-stars (Puls et al.) a tight rela

A. P. Schoenmakers, A. G. de Bruyn, H. J. A. Röttgering, H. van der Laan

Giant radio sources form the linear size extreme of the extra-galactic radio source population. Using the WENSS survey, we have selected a complete sample of these sources. We have investigated the properties of their radio structures. We find, among other things, that these sources are old (50-100 Myr) and have higher advance velocities than smaller sources

L. F. Olsen, H. E. Jorgensen, M. Scodeggio, L. da Costa

Clusters of galaxies are important targets in observationally cosmology, as they can be used both to study the evolution of the galaxies themselves and to constrain cosmological parameters. Here we report on the first results of a major effort to build up a sample of distant galaxy clusters to form the basis for further studies within those fields. We search

Antonella Vallenari, Giovanni Carraro, Andrea Richichi

We present and discuss new photometric data obtained with an IR camera in the J and K pass-bands for the intermediate age open clusters IC 166 (936 stars in total) and NGC 7789 (1030 stars in total). Ic 166 is a poorly studied open cluster for which no IR data was availabele previoulsy, while NGC 7789 is a well studied open cluster. We show that IC 166 is of

W. Hofmann

Based on data and Monte-Carlo simulations of the HEGRA IACT system, improved analysis techniques were developed for the determination of the shower geometry and shower energy from the multiple Cherenkov images. These techniques allow, e.g., to select subsamples of events with better than 3&#39; angular resolution, which are used to limit the rms radius of th

HEGRA Collaboration, W. Hofmann, G. Hermann, A. Konopelko

For stereoscopic systems of imaging atmospheric Cherenkov telescopes (IACTs), a key parameter to optimize the sensitivity for VHE gamma-ray point sources is the intertelescope spacing. Using pairs of telescopes of the HEGRA IACT system, the sensitivity of two-telescope stereo IACT systems is studied as a function of the telescope spacing, ranging from 70 m t

James R. Graham

Due to its simultaneous deep imaging and integral field spectroscopic capability, an Imaging Fourier Transform Spectrograph (IFTS) is ideally suited to the Next Generation Space Telescope (NGST) mission, and offers opportunities for tremendous scientific return in many fields of astrophysical inquiry. We describe the operation and quantify the advantages of

Motokazu Takizawa

We investigate the dynamical evolution of clusters of galaxies and their observational consequences during off-center mergers, explicitly considering the relaxation process between ions and electrons in intracluster medium by N-body and hydrodynamical simulations. In the contracting phase a bow shock is formed between the two subclusters. The observed temper

Volker Beckmann, Norbert Bade, Olaf Wucknitz

We present optical spectroscopy data that allowed a measurement of the redshift for the X-ray selected BL Lacertae object 1517+656. With a redshift of z = 0.702 this object has an absolute magnitude of B = -26.4 and is also an extremely powerful radio and X-ray source. Although being a high frequency peaked BL Lac, this object is one of the most luminous BL

William G. Mathews, Fabrizio Brighenti

Observational constraints and theoretical arguments indicate that cooled interstellar gas in bright elliptical galaxies forms into a young stellar population throughout the region within the half-light radius. The young population has a bottom-heavy, but optically luminous IMF extending to 1 - 2 M_sun. When the colors and spectral features of this young popu

A. S. Fruchter, W. M. Goss

We have obtained deep multifrequency radio observations of seven globular clusters using the Very Large Array and the Australia Telescope Compact Array. Five of these, NGC 6440, NGC 6539, NGC 6544, NGC 6624 and Terzan 5 had previously been detected in a shallower survey for steep spectrum radio sources in globular clusters (Fruchter and Goss 1990). The sixth

Michael C. Liu, Arjun Dey, James R. Graham, Charles C. Steidel

We have discovered an excess of extremely red objects (EROs) surrounding the z=2.69 quasar QSO 1213-0017 (UM 485). Optical/IR colors for these galaxies are consistent with z=1-2 ellipticals, and there are at least 5 galaxies with spectroscopic redshifts at <z>=1.31. Keck optical spectra for 3 of the red galaxies show rest-frame UV breaks resembling local ell

M. Pierre

While the concept of &#34;clustering&#34; primarily refers to galaxies, the fact is that galaxies can be neglected - at least in terms of mass - when considering the continuous competition between accretion and relaxation processes of dark matter and gas, which control the dynamical life of galaxy clusters. Gravity is certainly the driving force in cluster f

Jean-Philippe Uzan, Nathalie Deruelle, Alain Riazuelo

We consider a perfectly homogeneous, isotropic and spatially flat universe which undergoes a sudden phase transition producing topological defects. We assume that these defects form a coherent network which scales like the background density during the radiation and matter dominated eras, and describe them in terms of a few free functions. We carefully model

Darwin Chang, We-Fu Chang, Wai-Yee Keung

We calculate the two-loop contributions to the electric dipole moments of the electron and the neutron mediated by charged Higgs in a generic supersymmetric theories. The new contributions are originated from the potential CP violation in the trilinear couplings of the charged Higgs bosons to the scalar-top or the scalar-bottom quarks. These couplings did no

I. L. Buchbinder, D. M. Gitman, V. A. Krykhtin, V. D. Pershin

We investigate the problems of consistency and causality for the equations of motion describing massive spin two field in external gravitational and massless scalar dilaton fields in arbitrary spacetime dimension. From the field theoretical point of view we consider a general classical action with non-minimal couplings and find gravitational and dilaton back

Ko Honda

We develop new techniques in the theory of convex surfaces to prove complete classification results for tight contact structures on lens spaces, solid tori, and T^2 X I. Erratum: In this note we seek to remedy errors which appeared in version 2 and were propagated in subsequent papers.

Q. B. Li, P. N. Shen

The binding energy of the six quark system with strangeness s=-3 is investigated under the chiral SU(3) constituent quark model in the framework of $RGM$. The calculations of the single $NΩ$ channel with spin S=2 and the single $ΔΩ$ channel with spin S=3 are performed. The results show that both systems could be dibaryons and the interaction induced by the c

Elliott H. Lieb, Peter Schupp

We rigorously establish some exact properties of reflection symmetric spin systems with antiferromagnetic crossing bonds: At least one ground state has total spin zero and a positive semidefinite coefficient matrix. The crossing bonds obey an ice rule. This augments some previous results which were limited to bipartite spin systems and is of particular inter

Dharma P. Gupta, Martin E. Muldoon

N. Kishore, Proc. Amer. Math. Soc. 14 (1963), 523, considered the Rayleigh functions sigma_n, sums of the negative even powers of the (non-zero) zeros of the Bessel function J_nu(z) and provided a convolution type sum formula for finding sigma_n in terms of sigma_1, ...,sigma_{n-1}. His main tool was the recurrence relation for Bessel functions. Here we exte

Massimo Blasone, Petr Jizba

In the framework of the Closed-Time-Path formalism, we show how topological defects may arise in Quantum Field Theory as result of a localized (inhomogeneous) condensation of particles. We demonstrate our approach on two examples; kinks in the $2D λψ^{4}$ theory (both at zero and finite temperature) and vortices in the complex $4D λψ^{4} $ theory.

Jukka Maalampi, Nikolai Romanenko

We consider the reaction ee -> q,q,qbar,qbar as a test of lepton number non-conservation in the framework of the left-right-symmetric electroweak model. The main contributions to this process are due to Majorana neutrino exchange in t-channel and doubly charged Higgs (Delta(--)) exchange in s-channel with a pair of right-handed weak bosons (WR) as intermedia

S. W. Ham, S. K. OH, H. S. Song

The spontaneous violation of the CP symmetry in the next-to-minimal supersymmetric standard Model (NMSSM) is investigated. It is found that the spontaneous violation of the CP symmetry can occur in the Higgs sector of the NMSSM for a wide region of the parameter space of the model, at the 1-loop level where the radiative corrections due to the top quark and

H. Kleinert, B. Van den Bossche

In contrast to common belief, the chirally symmetric Nambu--Jona-Lasinio model does not contain massless pions, due to strong chiral fluctuations. Although quarks acquire spontaneously a nonzero constituent mass $M$, pions have a nonzero mass equal to the mass of $ \s $-mesons, both being of the order of $M$. This result is found in several cutoff schemes. O

U. Sharan

We construct a model to study the impact of instantons on the low lying eigenvalue spectrum of the Dirac operator. The model is by necessity, approximate, though it does incorporate the important symmetries of the underlying field theory. The model also reproduces classical results in the appropriate limits. We find that generic instanton ensembles lead to a

B. Shapiro

A monochromatic point source, embedded in a three-dimensional disordered medium, is considered. The resulting intensity pattern exhibits a new type of long-range correlations. The range of these correlations is infinite and their magnitude, normalized to the average intensity, is of order $1/k_0 \ell$, where $k_0$ and $\ell$ are the wave number and the mean