April 2000 arXiv papers — page 21

T. Binoth, G. Heinrich

We describe a constructive procedure to separate overlapping infrared divergences in multi-loop integrals. Working with a parametric representation in D=4-2*epsilon dimensions, adequate subtractions lead to a Laurent series in epsilon, where the coefficients of the pole- and finite terms are sums of regular parameter integrals which can be evaluated numerica

M. Yu. Kalmykov, O. Veretin

The $ε$-expansion of several two-loop self-energy diagrams with different thresholds and one mass are calculated. On-shell results are reduced to multiple binomial sums which values are presented in analytical form.

S. K. Adhikari, M. Casas, A. Puente, A. Rigo

The Cooper pair binding energy {\it vs.} center-of-mass-momentum dispersion relation for Bose-Einstein condensation studies of superconductivity is found in two dimensions for a renormalized attractive delta interaction. It crosses over smoothly from a linear to a quadratic form as coupling varies from weak to strong.

Ilan Tsafrir, Dror Sagi, Tamar Arzi, Marie-Alice Guedeau-Boudeville

We have studied the pearling instability induced on hollow tubular lipid vesicles by hydrophilic polymers with hydrophobic side groups along the backbone. The results show that the polymer concentration is coupled to local membrane curvature. The relaxation of a pearled tube is characterized by two different well-separated time scales, indicating two physica

Jens D. Noritzsch

We review Shuvaev's transformations, that relate off-forward parton distributions (OFPDs) to so-called effective forward parton distributions (EFPDs). The latter evolve like conventional forward partons. We express nonforward amplitudes, depending on OFPDs, directly in terms of EFPDs and construct a model for the EFPDs, which allows to consistently expre

Yaron Oz

In this talk we discuss two classes of examples of warped products of AdS spaces in the context of the AdS/CFT correspondence. The first class of examples appears in the construction of dual Type I' string descriptions to five dimensional supersymmetric fixed points with E_{N_f+1} global symmetry. The background is obtained as the near horizon geometry o

Rodrigo Ibata, Geraint F. Lewis, Michael Irwin, Edward Totten

An all high-latitude sky survey for cool carbon giant stars in the Galactic halo has revealed 75 such stars, of which the majority are new detections. Of these, more than half are clustered on a Great Circle on the sky which intersects the center of Sagittarius dwarf galaxy (Sgr) and is parallel to its proper motion vector, while many of the remainder are ou

Robert Fleischer, Daniel Wyler

We point out that the pure ``tree'' decays $B_c^\pm\to D^\pm_s D$ are particularly well suited to extract the CKM angle $γ$ through amplitude relations. In contrast to conceptually similar strategies using $B^\pm\to K^\pm D$ or $B_d\to K^{\ast0} D$ decays, the advantage of the $B_c$ approach is that the corresponding triangles have three sides of com

Kai Chen, Bo-yu Hou, Wen-Li Yang

We study the C_2 Ruijsenaars-Schneider(RS) model with interaction potential of trigonometric type. The Lax pairs for the model with and without spectral parameter are constructed. Also given are the involutive Hamiltonians for the system. Taking nonrelativistic limit, we obtain the Lax pair of C_2 Calogero-Moser model.

Vladimir Pestov

In this paper we further study links between concentration of measure in topological transformation groups, existence of fixed points, and Ramsey-type theorems for metric spaces. We prove that whenever the group $\Iso(\U)$ of isometries of Urysohn's universal complete separable metric space $\mathbb U$, equipped with the compact-open topology, acts upon

G. Vidal, W. Dür, J. I. Cirac

We present a family of tri-partite entangled states that, in an asymptotical sense, can be reversibly converted into EPR states shared by only two of parties (say B and C), and tripartite GHZ states. Thus we show that bipartite and genuine tripartite entanglement can be reversibly combined in several copies of a single tripartite state. For such states the c

P. Gosselin, H. mohrbach

We establish the renormalization group equation for the running action in the context of a one quantum particle system. This equation is deduced by integrating each fourier mode after the other in the path integral formalism. It is free of the well known pathologies which appear in quantum field theory due to the sharp cutoff. We show that for an arbitrary b

S. Albeverio, S. M. Fei, P. Kurasov

We study quantum mechanical systems with "spin"-related contact interactions in one dimension. The boundary conditions describing the contact interactions are dependent on the spin states of the particles. In particular we investigate the integrability of $N$-body systems with $δ$-interactions and point spin couplings. Bethe ansatz solutions, bound s

P. Gosselin, B. Grosdidier, H. Mohrbach

We establish the exact renormalization group equation for the potential of a one quantum particle system at finite and zero temperature. As an example we use it to compute the ground state energy of the anharmonic oscillator. We comment on an improvement of the Feynman Kleinert's variational method by the renormalization group.

V. Ter-Antonyan

The dyon-oscillator duality presented in this lecture can be treated as a prototype of the Seiberg-Witten duality in nonrelativistic quantum mechanics. The key statement declares that in some spatial dimensions the oscillator-like systems are dual to the atoms composed of the electrical charged particle and dyon, i.e., monopoles provided by both magnetic and

A. Berard, y. Grandati, H. Mohrbach

We introduce the magnetic angular momentum as a consequence of the structure of the sO(3) Lie algebra defined by the Feynman brackets. The Poincare momentum and Dirac magnetic monopole appears as a direct result of this framework.

Lieu, Richard

The starting point of the theory of Special Relativity$^1$ is the Lorentz transformation, which in essence describes the lack of absolute measurements of space and time. These effects came about when one applies the Second Relativity Postulate to inertial observers. Here I demonstrate that there is a very elegant way of explaining how exactly nature enforces

Tohru Ohnuki, Daniel P. Snowden-Ifft, C. J. Martoff

A Negative Ion Time Projection Chamber was used to measure the field dependence of lateral and longitudinal diffusion for CS$_2$ anions drifting in mixtures of CS$_2$ and Ar at 40 Torr. Ion drift velocities and limits on the capture distance for electrons as a function of field and gas mixture are also reported.

A. Berard, H. Mohrbach, P. Gosselin

The dynamic of a classical system can be expressed by means of Poisson brackets. In this paper we generalize the relation between the usual non covariant Hamiltonian and the Poisson brackets to a covariant Hamiltonian and new brackets in the frame of the Minkowski space. These brackets can be related to those used by Feynman in his derivation of Maxwell'

Alexander Morozovsky

The introduction of transaction costs into the theory of option pricing could lead not only to the change of return for options, but also to the change of the volatility. On the base of assumption of the portfolio analysis, a new equation for option pricing with transaction costs is derived. A new solution for the option price is obtained for the time close

Zuo-Bing Wu, Jin-Yan Zeng

A method to determine the admissibility of symbolic sequences and to find the unstable periodic orbits corresponding to allowed symbolic sequences for the diamagnetic Kepler problem is proposed by using the ordering of stable and unstable manifolds. By investigating the unstable periodic orbits up to length 6, a one to one correspondence between the unstable

I. V. Krasovsky

The spectrum of Harper's equation is determined by the discriminant, which is a certain polynomial of degree Q if the commensurability parameter of Harper's equation is P/Q, where P, Q are coprime positive integers. A simple expression is indicated for the derivative of the discriminant at zero energy for odd Q. Three dominant terms of the asymptotic

Henri Epstein

We prove the existence of fixed points of p-tupling renormalization operators for interval and circle mappings having a critical point of arbitrary real degree r > 1. Some properties of the resulting maps are studied: analyticity, univalence, behavior as $r$ tends to infinity.

Dean L. Alvis, Michael K. Kinyon

The panstochastic analogue of Birkhoff's Theorem on doubly-stochastic matrices is proved in the case $n=5$. It is shown that this analogue fails when $n>1$, $n \ne 5$.

Richard W. Kenyon, James G. Propp, David B. Wilson

In this article, Temperley's bijection between spanning trees of the square grid on the one hand, and perfect matchings (also known as dimer coverings) of the square grid on the other, is extended to the setting of general planar directed (and undirected) graphs, where edges carry nonnegative weights that induce a weighting on the set of spanning trees.

Nitu Kitchloo, Krishnan Shankar

There has been renewed interest in $\mathbb{S}^3$-bundles over $\mathbb{S}^4$ since K. Grove and W. Ziller constructed metrics on nonnegative curvature on the total spaces of these bundles. In this paper we write down necessary and sufficient conditions for a CW complex to be homotopy equivalent to such a bundle. We also show that for a manifold homotopy equ

Helmut Prodinger

Garrett, Ismail, and Stanton gave a general formula that contains the Rogers-Ramanjuan identities as special cases. We show how easy this is when using a determinant that Schur introduced in 1917.

B. L. Cerchiai, J. Madore, S. Schraml, J. Wess

As an example of a noncommutative space we discuss the quantum 3-dimensional Euclidean space $R^3_q$ together with its symmetry structure in great detail. The algebraic structure and the representation theory are clarified and discrete spectra for the coordinates are found. The q-deformed Legendre functions play a special role. A completeness relation is der

Eric Leichtnam, Wolfgang Lueck

We extend the notion of the symmetric signature $σ(\bar{M},r)$ in L^n(R) for a compact n-dimensional manifold M without boundary, a reference map r from M to BG and a homomorphism of rings with involutions from ZG to R to the case with boundary $\partial M$, where $(\bar{M},\bar{\partial M}) \to (M,\partial M)$ is the G-covering associated to r. We need the

Dirk Kreimer

We discuss shuffle identities between Feynman graphs using the Hopf algebra structure of perturbative quantum field theory. For concrete exposition, we discuss vertex function in massless Yukawa theory.

Reza Abbaspur

In this paper we investigate about several configurations of two intersecting branes at arbitrary angles. We choose the viewpoint of a brane source and a brane probe and use the low-energy dynamics of p-branes. For each p-brane this dynamics is governed by a generic DBI action including a WZ term, which couples to the SUGRA background of the other brane. The

F. V. Gubarev, V. I. Zakharov

We consider the quantum mechanical notion of the geometrical (Berry) phase in SU(2) gauge theory, both in the continuum and on the lattice. It is shown that in the coherent state basis eigenvalues of the Wilson loop operator naturally decompose into the geometrical and dynamical phase factors. Moreover, for each Wilson loop there is a unique choice of U(1) g

H. Mohrbach, A. Berard, P. Gosselin

It is shown that next-nearest-neighbor interactions may lead to unusual paramagnetic or ferromagnetic phases which physical content is radically different from the standard phases. Actually there are several particles described by the same quantum field in a manner similar to the species doubling of the lattice fermions. We prove the renormalizability of the

A. Misra

The axial-gauge boson propagator contains 1/(n.k)^p-type singularities. These singularities have generally been treated by inventing prescriptions for them. We propose an alternative procedere for treating these singularities in the path-integral formalism using the known way of treating the 1/k^{2n}-type singularities in Lorentz-type gauges. For this purpos

Andre Sopczak

The latest preliminary combined results of the Higgs boson searches from the LEP experiments ALEPH, DELPHI, L3 and OPAL are presented. A general scan of the MSSM parameters is performed and leads to stringent lower mass limits and for the first time excludes low tan(beta) values.

Alex Kovner, J. Guilherme Milhano, Heribert Weigert

We analyze the relation between evolution equations at low x that have been derived in different approaches in the last several years. We show that the equation derived by Balitsky and Kovchegov is obtained from the Jalilian-Marian-Kovner-Leonidov-Weigert (JKLW) equation in the limit of small induced charge density. We argue that the higher nonlinearities re

B. Borasoy

We calculate the electric dipole moments of the neutron and the Lambda within the framework of heavy baryon chiral perturbation theory. They are induced by strong CP-violating terms of the effective Lagrangian in the presence of the vacuum angle theta_0. The construction of such a Lagrangian is outlined and we are able to give an estimate for theta_0.

S. Banerjee, R. Basu, M. Dittmar, R. V. Gavai

This is the report of the QCD working group at WHEPP 6. Discussions and work on heavy ion collisions, polarised scattering, and collider phenomenology are reported.

Michael Gronau, Dan Pirjol

We consider two SU(3) breaking parameters, $R_1(m_B)$ and $R_2(m_B)$, appearing in a relation between $B^+\to Kπ$ and $B^+\toππ$ amplitudes, which plays an important role in determining the weak phase $γ$. We identify an isospin-related quantity $R_2(m_D)$ measured in $D$ decays, exhibiting large SU(3) breaking which is likely due to nonfactorizable effects.

Howard Baer, Pedro G. Mercadante, Xerxes Tata, Yili Wang

We examine signals for sparticle production at the CERN Large Hadron Collider (LHC) within the framework of gauge mediated supersymmetry breaking models with a low SUSY breaking scale for four different model lines, each of which leads to qualitatively different signatures. We first examine the reach of the LHC via the canonical E_T^miss and multilepton chan

Sinya Aoki, Taku Izubuchi, Yoshinobu Kuramashi, Yusuke Taniguchi

We study the chiral properties and the validity of perturbation theory for domain wall fermions in quenched lattice QCD at beta=6.0. The explicit chiral symmetry breaking term in the axial Ward-Takahashi identity is found to be very small already at Ns=10, where Ns is the size of the fifth dimension, and its behavior seems consistent with an exponential deca

Alvaro Montero

We study the properties of vortex-like configurations which are solutions of the SU(N) Yang-Mills classical equations of motion. We show that these solutions are concentrated along a two-dimensional wall with size growing with the number of colors.

CDF Collaboration

We report the results of a search for second and third generation leptoquarks using 88 ${pb}^{-1}$ of data recorded by the Collider Detector at Fermilab. Color triplet technipions, which play the role of scalar leptoquarks, are investigated due to their potential production in decays of strongly coupled color octet technirhos. Events with a signature of two

D. A. Asner

Using a sample of 4.7/fb integrated luminosity accumulated with the CLEO II detector at the Cornell Electron Storage Ring (CESR), we investigate the mass spectrum and resonant structure in tau->Kpipi decays. We measure the relative fractions of K1(1270) and K1(1400) resonances in these decays, as well as the K1 masses and widths. Our fitted K1 resonances are

D. E. Jaffe

The /\c->pKpi yield has been measured in a sample of two-jet continuum events containing a both an anticharm tag (Dbar) as well as an antiproton (e+e- -> Dbar pbar X), with the antiproton in the hemisphere opposite the Dbar. Under the hypothesis that such selection criteria tag e+e- -> Dbar pbar (/\c) X events, the /\c->pkpi branching fraction can be determi

Philip D. Mannheim

We discuss our understanding of the equivalence principle in both classical mechanics and quantum mechanics. We show that not only does the equivalence principle hold for the trajectories of quantum particles in a background gravitational field, but also that it is only because of this that the equivalence principle is even to be expected to hold for classic

B. L. Hu, Nicholas. G. Phillips

From calculations of the variance of fluctuations and of the mean of the energy density of a massless scalar field in the Minkowski vacuum as a function of an intrinsic scale defined by the world function between two nearby points (as used in point separation regularization) we show that, contrary to prior claims, the ratio of variance to mean-squared being

David Wallace

This is an introduction to quantum gravity, aimed at a fairly general audience and concentrating on what have historically two main approaches to quantum gravity: the covariant and canonical programs (string theory is not covered). The quantization of gravity is discussed by analogy with the quantization of the electromagnetic field. The conceptual and techn

Fredrik Andersson

By the method of rho-integration we obtain all Lanczos potentials L_{ABCA'} of the Weyl spinor that, in a certain sense, are aligned to a geodesic shear-free expanding null congruence. We also obtain all spinors H_{ABA'B'}=Q_{AB}o_{A'}o_{B'}, Q_{AB}=Q_{(AB)} satisfying nabla_{(A}{}^{B'}H_{BC)A'B'}=L_{ABCA'}. We go on to pr

Marcus Hutter

Decision theory formally solves the problem of rational agents in uncertain worlds if the true environmental prior probability distribution is known. Solomonoff's theory of universal induction formally solves the problem of sequence prediction for unknown prior distribution. We combine both ideas and get a parameterless theory of universal Artificial Int

James Delgrande, Torsten Schaub

We present a general, consistency-based framework for belief change. Informally, in revising K by A, we begin with A and incorporate as much of K as consistently possible. Formally, a knowledge base K and sentence A are expressed, via renaming propositions in K, in separate languages. Using a maximization process, we assume the languages are the same insofar

Ligang Chen, Marco Falcioni, Michael W. Deem

We suggest that disordered framework aluminums and non-framework cations can create a disordered electrostatic potential in zeolites that can lead to a discrepancy between diffusivities measured by microscopic and macroscopic experimental techniques. We calculate the value of the discrepancy and the characteristic time scale at which it occurs for several io

L. A. Barreiro, J. R. Campanha, R. E. Lagos

We present a systematic expansion of Kramers equation in the high friction limit. The latter is expanded within an operator continued fraction scheme. The relevant operators include both temporal and spatial derivatives and a covariant derivate or gauge like operator associated to the potential energy. Trivially, the first order term yields the Smoluchowsky

Janusz A. Holyst, Krzysztof Kacperski, Frank Schweitzer

We study phase transitions in models of opinion formation which are based on the social impact theory. Two different models are discussed: (i) a cellular--automata based model of a finite group with a strong leader where persons can change their opinions but not their spatial positions, and (ii) a model with persons treated as active Brownian particles inter

Debanand Sa, C. Gros

An effective intra- and inter-ladder charge-spin hamiltonian for the quarter-filled ladder compound $α'$-NaV$_2$O$_5$ has been derived by using the standard canonical transformation method. In the derivation, it is clear that a finite inter-site Coulomb repulsion is needed to get a meaningful result otherwise the perturbation becomes ill-defined. Various

Andrej Gendiar, Anton Surda

The Density Matrix Renormalization Group (DMRG) method with periodic boundary conditions is introduced for two dimensional classical spin models. It is shown that this method is more suitable for derivation of the properties of infinite 2D systems than the DMRG with open boundary conditions despite the latter describes much better strips of finite width. For

L. Šamaj, I. Travěnec

The model under consideration is a two-dimensional two-component plasma, stable against collapse for the dimensionless coupling constant $β<2$. The combination of a technique of renormalized Mayer expansion with the mapping onto the sine-Gordon theory provides the full thermodynamics of the plasma in the whole stability range of $β$. The explicit forms of th

I. V. Krasovsky

The spectral determinant det(H-εI) of the Azbel-Hofstadter Hamiltonian H is related to Onsager&#39;s partition function of the 2D Ising model for any value of magnetic flux Φ=2πP/Q through an elementary cell, where P and Q are coprime integers. The band edges of H correspond to the critical temperature of the Ising model; the spectral determinant at these (a

Ladislav Šamaj

In a Coulomb fluid confined to a domain $V$, the dielectric susceptibility tensor $χ_V$ depends on the shape of $V$, even in the thermodynamic $V\to\infty$ limit. This paper deals with the classical two-dimensional one-component plasma formulated in an elliptic $V$-domain, equilibrium statistical mechanics is used. For the dimensionless coupling constant $Γ=

Zhong-Wen Ouyang, Le-Man Kuang

We study quantum dynamics of three dressed Bose-Einstein condensates in a high-Q cavity. The quasiparticle excitation spectrum of this system is found numerically. The stability of the quasiparticle excitation is analyzed. It is shown that there exist instabilities in the excitation spectrum.

E. Hodby, G. Hechenblaikner, O. M. Marago&#39;, J. Arlt

We report on the realisation of a stiff magnetic trap with independently adjustable trap frequencies, $ω_z$ and $ω_r$, in the axial and radial directions respectively. This has been achieved by applying an axial modulation to a Time-averaged Orbiting Potential (TOP) trap. The frequency ratio of the trap, $ω_z / ω_r$, can be decreased continuously from the or

Y. Kafri, D. Biron, M. R. Evans, D. Mukamel

The coarsening process in a class of driven systems is studied. These systems have previously been shown to exhibit phase separation and slow coarsening in one dimension. We consider generalizations of this class of models to higher dimensions. In particular we study a system of three types of particles that diffuse under local conserving dynamics in two dim

Rajesh Narayanan, Thomas Vojta

We study the quantum phase transition of an itinerant antiferromagnet with cubic anisotropy in the presence of quenched disorder, paying particular attention to the locally ordered spatial regions that form in the Griffiths region. We derive an effective action where these rare regions are described in terms of static annealed disorder. A one loop renormaliz

Guy Auberson, Sudhir R. Jain, Avinash Khare

We obtain the exact ground state and a part of the excitation spectrum in one dimension on a line and the exact ground state on a circle in a case where N particles are interacting via nearest- and next-to-nearest neighbour interactions. Further, using the exact ground-state, we establish a mapping between these N-body problems and the short-range Dyson mode

Leonid Burakovsky, Dean L. Preston, Richard R. Silbar

We present a theory of the melting of elemental solids as a dislocation-mediated phase transition. We model dislocations near melt as non-interacting closed strings on a lattice. In this framework we derive simple expressions for the melting temperature and latent heat of fusion that depend on the dislocation density at melt. We use experimental data for mor

Naoko Nakagawa, Kunihiko Kaneko

To understand the mechanism allowing for the long-term storage of excess energy in proteins, we study a Hamiltonian system consisting of several coupled pendula in partial contact with a heat bath. It is found that energy storage is possible when the motion of each pendulum switches between oscillatory (vibrational) and rotational (phase-slip) modes. The sto

Nariya Uchida

Properties of disordered nematic elastomers and gels are theoretically investigated with emphasis on the roles of non-local elastic interactions and crosslinking conditions. Networks originally crosslinked in the isotropic phase lose their long-range orientational order by the action of quenched random stresses, which we incorporate into the affine-deformati

David Mukamel

Phase transitions and critical behavior of driven systems are reviewed. Models exhibiting phase transitions, spontaneous symmetry breaking, phase separation and coarsening processes in d=1 dimension are discussed.

Cristina Chiappini, Francesca Matteucci

In this work we explore the effects of adopting an initial mass function (IMF) variable in time on the chemical evolution of the Galaxy. In order to do that we adopt a chemical evolution model which assumes two main infall episodes for the formation of the Galaxy. We study the effects on such a model of different IMFs. First, we use a theoretical one based o

Mark Dickinson

The Hubble Deep Fields continue to be a valuable resource for studying the distant universe, particularly at z>2 where their comoving volume becomes large enough to encompass several hundred L* galaxies or their progenitors. Here I present recent results from a near-infrared imaging survey of the HDF-North with NICMOS, which provides structural and photometr

Mark Dickinson

We have carried out a deep infrared imaging survey (1.1um and 1.6um) of the Hubble Deep Field North (HDF-N) using NICMOS on board the Hubble Space Telescope. The combined WFPC2+NICMOS data set lets us study galaxy morphologies, colors and luminosities at common rest frame wavelengths over a broad range of redshifts, e.g., in the V-band out to z=2. Here, I il

H. K. C. Yee, S. L. Morris, H. Lin, R. G. Carlberg

The Canadian Network for Observational Cosmology (CNOC2) Field Galaxy Redshift Survey is a spectroscopic/photometric survey of faint galaxies over 1.5 square degrees of sky with a nominal spectroscopic limit of R_c=21.5 mag. The primary goals of the survey are to investigate the evolution of galaxy clustering and galaxy populations over the redshift range of

Paul D. Feldman, Eric B. Burgh, Samuel T. Durrance, Arthur F. Davidsen

Far-ultraviolet spectra of Venus and Mars in the range 820-1840 A at 4 A resolution were obtained on 13 and 12 March 1995, respectively, by the Hopkins Ultraviolet Telescope (HUT), which was part of the Astro-2 observatory on the Space Shuttle Endeavour. Longward of 1250 A, the spectra of both planets are dominated by emission of the CO Fourth Positive band

James Robinson

I compare various semi-analytic models for the bias of dark matter halos with halo clustering properties observed in recent numerical simulations. The best fitting model is one based on the collapse of ellipsoidal perturbations proposed by Sheth, Mo & Tormen (1999), which fits the halo correlation length to better than 8 per cent accuracy. Using this model,

I. F. Mirabel, D. B. Sanders, E. Le Floc&#39;h

Present knowledge indicates that gamma-ray bursts are linked with massive stars. They will become invaluable probes of the early universe and galaxy formation. In the future, it will be possible to use gamma-ray bursts for two purposes: 1) to probe the history of massive star formation in the Universe by the rate of occurence of gamma-ray bursts, and 2) for

V. S. Beskin, I. V. Kuznetsova

The Grad--Shafranov approach to the problem of the structure of the black hole magnetosphere is discussed. For the double transonic flow, the number of boundary conditions in the pair creation region is shown to be sufficient to determine not only the longitudinal electric current, but also the angular velocity of a flow as a solution to a problem. As a resu

J. Marti, I. F. Mirabel, S. Chaty, L. F. Rodriguez

We present near infrared spectroscopy of the superluminal microquasar \grs\ obtained with the first unit of the VLT (Based on observations collected at the European Southern Observatory, Chile (ESO No 63.H-0261).) and the ISAAC spectro-imager. The emission features detected in the VLT data have been identified as He I, Br $γ$, He II and Na I. The detection o

Richard J. N. Brown, Duncan A. Forbes, Markus Kissler-Patig, Jean P. Brodie

An excellent candidate for a young elliptical, or `protoelliptical&#39; galaxy is NGC 1700. Here we present new B, V and I band imaging using the Keck telescope and reanalyse existing V and I band images from the Hubble Space Telescope. After subtracting a model of the galaxy from the Keck images NGC 1700 reveals two symmetric tidal tail-like structures. If

K. Pottschmidt, J. Wilms, M. A. Nowak, W. A. Heindl

We present the long term evolution of the frequency-dependent X-ray time lags of the black hole candidate Cygnus X-1 as measured in 1996 and 1998 with the Rossi X-ray Timing Explorer (RXTE). Lag spectra measured during the 1996 June soft state are very similar to those seen during 1996 December and most of 1998 while Cyg~X-1 was in its hard state. During sta

Robert Popham, Rashid Sunyaev

We present solutions for the structure of the boundary layer where the accretion disk meets the neutron star, which is expected to be the dominant source of high-energy radiation in low-mass X-ray binaries which contain weakly magnetized accreting neutron stars. We find that the main portion of the boundary layer gas is hot (> ~10^8 K), low in density, radia

Paul Sommers

A cosmic ray observatory with full-sky coverage can exploit standard anisotropy analysis methods that do not work if part of the celestial sphere is never seen. In particular, the distribution of arrival directions can be fully characterized by a list of spherical harmonic coefficients. The dipole vector and quadrupole tensor are of special interest, but the

F. D. Seward, M. A. Alpar, C. Flanagan, U. Kiziloglu

The ROSAT HRI was used to monitor X-ray emission from the Vela Pulsar. Six observations span 2-1/2 years and 3 glitches. The summed data yield a determination of the pulse shape, and X-ray emission from the pulsar is found to be 12 % pulsed with one broad and two narrow peaks. One observation occurred 15 days after a large glitch. No change in pulse structur

G. Matt, D. de Martino, B. T. Gaensicke, I. Negueruela

Temporal and spectral analyses from BeppoSAX observations of AM Her performed during both an intermediate and a high state are presented and discussed. Optical observations taken a few days after the X-ray ones are also presented. During the intermediate state observation, the source was in its &#34;normal&#34;, one-pole accretion mode. In the high state it

K. -H. Hofmann, U. Beckmann, T. Bloecker, V. Coude du Foresto

We present K-band observations of five Mira stars with the IOTA interferometer. The interferograms were obtained with the FLUOR fiber optics beam combiner which provides high-accuracy visibility measurements in spite of time-variable atmospheric conditions. For the Mira stars X Oph, R Aql, RU Her, R Ser, and V CrB we derived the uniform-disk diameters 11.7 m

R. Barbon, G. Carraro, U. Munari, T. Zwitter

BVI photometry (from South Africa Astron. Obs.), Echelle high resolution spectroscopy and AFOSC integral field spectroscopy (from Asiago, Italy) of the young open cluster NGC 6604 are presented. Age, distance, reddening, membership, radial and rotational velocities are derived and discussed. An age of 5 million years, a distance of 1.7 kpc and a reddening E(

Keisuke Taniguchi, Takashi Nakamura

Solutions to equilibrium sequences of irrotational binary polytropic stars in Newtonian gravity are expanded in a power of $ε=a_0/R$, where R and $a_0$ are the orbital separation of the binary system and the radius of each star for $R=\infty$. For each order of $ε$, we should solve ordinary differential equations for arbitrary polytropic indices n. We show s

B. Dirsch, T. Richtler, W. P. Gieren, M. Hilker

We investigate, on the basis of CCD Stroemgren photometry, the ages and metallicities of six LMC clusters together with their surrounding field population. The clusters and metallicities are: NGC1651 (in the range [Fe/H]=-0.65 dex to -0.41 dex), NGC1711 (-0.57+/-0.17 dex), NGC 1806 (-0.71+/-0.23 dex), NGC2031 (-0.52+/-0.21 dex) and NGC2136/37 (-0.55+/-0.23 d

Takashi Nakamura

We assume that internal shocks of Gamma Ray Bursts (GRBs) consist of multiple sub-jets with a collimation half-angle $\sim {\rm several }\timesγ_i^{-1}$, where $γ_i$ is the Lorenz factor of each sub-jet. If by chance a sub-jet is first emitted off-axis from the line of sight, the observed peak energy can be in the X-ray region. Next if by chance a subsequent

S. M. White, R. J. Thomas, J. W. Brosius, M. R. Kundu

We present a measurement of the abundance of Fe relative to H in the solar corona using a technique which differs from previous spectroscopic and solar wind measurements. Our method combines EUV line data from the CDS spectrometer on SOHO with thermal bremsstrahlung radio data from the VLA. The coronal Fe abundance is derived by equating the thermal bremsstr

S. Seager, B. A. Whitney, D. D. Sasselov

The close-in extrasolar giant planets [CEGPs], $\ltorder$ 0.05 AU from their parent stars, may have a large component of optically reflected light. We present theoretical optical photometric light curves and polarization curves for the CEGP systems, from reflected planetary light. Different particle sizes of three condensates are considered. In the most refl

Norbert A&#39;Campo

This is the paper as published. The topology of a complex plane curve singularity with real branches is deduced from any real deformation having delta crossings. An example of the computation of the global geometric monodromy of a polynomial mapping is added.

A. V. Kotikov, L. N. Lipatov

We study next-to-leading corrections to the integral kernel of the BFKL equation for high energy cross-sections in QCD and in supersymmetric gauge theories. The eigenvalue of the BFKL kernel is calculated in an analytic form as a function of the anomalous dimension γof the local gauge-invariant operators and their conformal spin n. For the case of an extende

Roberto Casadio, Benjamin Harms

We study the evaporation of black holes in space-times with extra dimensions of size L. We first obtain a potential which describes the expected behaviors of very large and very small black holes and then show that a (first order) phase transition, possibly signaled by an outburst of energy, occurs in the system when the horizon shrinks below L from a larger

Yshai Avishai, Anatoly Golub, Andrei D. Zaikin

Novel effects emerge from an interplay between multiple Andreev reflections and Coulomb interaction in quantum dot coupled to superconducting leads and subject to a finite potential bias $V$. Combining an intuitive physical picture with rigorous path integral formalism we evaluate the current $I$ through the dot and find that the interaction shifts the subha

Stefan Scheel, Ludwig Knoll, Tomas Opatrny, Dirk-Gunnar Welsch

Dielectric four-port devices play an important role in optical quantum information processing. Since for causality reasons the permittivity is a complex function of frequency, dielectrics are typical examples of noisy quantum channels, which cannot preserve quantum coherence. To study the effects of quantum decoherence, we start from the quantized electromag

Pierre-Yves Gaillard

The category O of BGG can be thought of as a category of sheaves over the flag variety F in the sense that the algebra E of self-extensions of the trivial object of O is isomorphic to the cohomology algebra of the flag variety. A deformation of O&#39; - giving rise to a &#34;new&#34; algebra E&#39; - can be thought of as a (possibly noncommutative) deformati

G. Sardanashvily

Smooth composite bundles provide the adequate geometric description of classical mechanics with time-dependent parameters. We show that the Berry&#39;s phase phenomenon is described in terms of connections on composite Hilbert space bundles.

V. B. Svetovoy, M. V. Lokhanin

Linear in temperature correction to the Casimir force is discussed. The correction is important for small separations between bodies tested in the recent experiments and disappears in the case of perfect conductors.

V. Kuznetsov, P. Vanhaecke

We present a geometric construction of Backlund transformations and discretizations for a large class of algebraic completely integrable systems. To be more precise, we construct families of Backlund transformations, which are naturally parametrized by the points on the spectral curve(s) of the system. The key idea is that a point on the curve determines, th

Eiji Ogasa

We introduce ribbon-moves of 2-knots, which are operations to make 2-knots into new 2-knots by local operations in B^4. (We do not assume the new knots is not equivalent to the old ones.) Let L_1 and L_2 be 2-links. Then the following hold. (1) If L_1 is ribbon-move equivalent to L_2, then we have μ(L_1)=μ(L_2). (2) Suppose that L_1 is ribbon-move equivalent