March 2002 arXiv papers — page 10

S. K. Lamoreaux, R. Golub

We present experimental measurements of the properties of a liquid "Fomblin" surface obtained by the quasielastic scattering of laser light. The properties include the surface tension and viscosity as a function of temperature. The results are compared to the measurements of the bulk fluid properties. We then calculate the upscattering rate of ultrac

S. G. Schirmer, I. C. H. Pullen, A. I. Solomon

The problem of identifying the dynamical Lie algebras of finite-level quantum systems subject to external control is considered, with special emphasis on systems that are not completely controllable. In particular, it is shown that the dynamical Lie algebra for an N-level system with equally spaced energy levels and uniform transition dipole moments, is a su

Thomas Breuer

Unsharp spin observables are shown to arise from the fact that a residual uncertainty about the actual alignment of the measurement device remains. If the uncertainty is below a certain level, and if the distribution misalignments is covariant under rotations, a Kochen-Specker theorem for the unsharp spin observables follows: There are finite sets of directi

G. Manfredi, M. R. Feix

The properties of an alternative definition of quantum entropy, based on Wigner functions, are discussed. Such definition emerges naturally from the Wigner representation of quantum mechanics, and can easily quantify the amount of entanglement of a quantum state. It is shown that smoothing of the Wigner function induces an increase in entropy. This fact is u

L. Solombrino

We inquire into some properties of diagonalizable pseudo-Hermitian operators, showing that their definition can be relaxed and that the pseudo-Hermiticity property is strictly connected with the existence of an antilinear symmetry. This result is then illustrated by considering the particular case of the complex Morse potential.

K. M. Fonseca-Romero, G. Useche-Laverde, F. Torres-Ardila

We consider the problem of carrying an initial Bloch vector to a final Bloch vector in a specified amount of time under the action of three control fields (a vector control field). We show that this control problem is solvable and therefore it is possible to optimize the control. We choose the physically motivated criteria of minimum energy spent in the cont

Alexander A. Klyachko, Alexander S. Shumovsky

We show that the maximum entanglement in a composite system corresponds to the maximum uncertainty and maximum correlation of local measurements.

William T. Buttler, Justin R. Torgerson, Steven K. Lamoreaux

We present a new fiber based quantum key distribution (QKD) scheme which can be regarded as a modification of an idea proposed by Inoue, Waks and Yamamoto (IWY) [1]. The scheme described here uses a single phase modulator and two differential delay elements in series at the transmitter that form an interferometer when combined with a third differential delay

Chui-Ping Yang, Shih-I Chu, Siyuan Han

We present a quantum error correction code which protects three quantum bits (qubits) of quantum information against one erasure, i.e., a single-qubit arbitrary error at a known position. To accomplish this, we encode the original state by distributing quantum information over six qubits which is the minimal number for the present task (see reference [1]). T

Jens U. Nockel

The smaller the size of a light-emitting microcavity, the more important it becomes to understand the effects of the cavity boundary on the optical mode profile. Conventional methods of laser physics, such as the paraxial approximation, become inapplicable in many of the more exotic cavity designs to be discussed here. Cavities in the shape of microdisks, pi

A. K. Mohanty, A. V. S. S. Narayana Rao

The so called long range correlation properties of DNA sequences are studied using the variance analyses of the density distribution of a single or a group of nucleotides in a model independent way. This new method which was suggested earlier has been applied to extract slope parameters that characterize the correlation properties for several intron containi

P. F. Bedaque, U. van Kolck

We review the effective field theories (EFTs) developed for few-nucleon systems. These EFTs are controlled expansions in momenta, where certain (leading-order) interactions are summed to all orders. At low energies, an EFT with only contact interactions allows a detailed analysis of renormalization in a non-perturbative context and uncovers novel asymptotic

N. E. Ligterink

We develop a model-independent analysis of hadronic scattering data in the resonance region, where the resonance shape follows from the matrix elements of a Hamiltonian. We investigate the rho meson in the tau decay. We demonstrate that the rho meson resonance in the two-pion decay of the tau lepton is described well through the coupling of a bare rho meson

H. Babacan, T. Babacan

Associative photoproduction of $ω$-meson and $N^{*}(1440)$ on nucleons, $γ+N\toω+N^{*}(1440)$, in the near threshold region is investigated in a framework employing effective Lagrangians. Besides $π$-exchange in t-channel, baryon exchanges, i.e. N- and $N^{*}$-exchanges, in the s- and u-channels are also taken into account in calculations of differential cro

Jens U. Nockel

Angular momentum ceases to be the preferred basis for identifying dynamical localization in an oval billiard at large excentricity. We give reasons for this, and comment on the classical phase-space structure that is encoded in the wave functions of ``leaky'' dielectric resonators with oval cross section.

A. S. Sorin, P. H. M. Kersten

A detailed description is given for the construction of the deformation of the N=2 supersymmetric $α=1$ KdV-equation, leading to the recursion operator for symmetries and the zero-th Hamiltonian structure; the solution to a longstanding problem.

G. Sardanashvily

These Lectures summarize the relevant material on existent applications of jet manifold techniques to classical and quantum field theory. The following topics are included: 1. Fibre bundles, 2. Jet manifolds, 3. Connections, 4. Lagrangian field theory, 5. Gauge theory of principal connections, 6. Higher order jets, 7. Infinite order jets, 8. The variational

Demeter Krupka

In this paper we will be considering a basic geometric problem, the extension problem of classical Hamilton-Cartan variational theory to higher jet prolongations on fibered manifolds.

Ricardo Weder

In these lectures I give an introduction to the time-dependent approach to inverse scattering, that has been developed recently. The aim of this approach is to solve various inverse scattering problems with time-dependent methods that closely follow the physical (and geometrical) intuition of the scattering phenomena. This method has been applied to many lin

Christof Sparber, Peter A. Markowich, Norbert J. Mauser

We consider the Cauchy-problem for a class of scalar linear dispersive equations with rapidly oscillating initial data. The problem of high-frequency asymptotics of such models is reviewed,in particular we highlight the difficulties in crossing caustics when using (time-dependent) WKB-methods. Using Wigner measures we present an alternative approach to such

Sergei Anisov

We find the exact values of complexity for an infinite series of 3-manifolds. Namely, by calculating hyperbolic volumes, we show that c(N_n)=2n, where $c$ is the complexity of a 3-manifold and N_n is the total space of the punctured torus bundle over S^1 with monodromy 2&1 1&1 ^n$. We also apply a recent result of Matveev and Pervova to show that c(M_n) \ge

R. van der Hofstad, F. den Hollander, W. Koenig

In this paper we prove a large deviation principle for the empirical drift of a one-dimensional Brownian motion with self-repellence called the Edwards model. Our results extend earlier work in which a law of large numbers, respectively, a central limit theorem were derived. In the Edwards model a path of length $T$ receives a penalty $e^{-βH_T}$, where $ H_

R. van der Hofstad, F. den Hollander, W. Koenig

In this paper we present a new and flexible method to show that, in one dimension, various self-repellent random walks converge to self-repellent Brownian motion in the limit of weak interaction after appropriate space-time scaling. Our method is based on cutting the path into pieces of an appropriately scaled length, controlling the interaction between the

Ken Dykema

Let Q be any II_1-factor. It is shown that any standard lattice G can be realized as the standard invariant of a free product of (several) rescalings of Q. In particular, if Q has fundamental group equal to the positive reals and if P is the free product of infinitely many copies of Q, then P has subfactors giving rise to all possible standard invariants. Si

F. A. Grunbaum, I. Pacharoni, J. Tirao

The main purpose of this paper is to compute all irreducible spherical functions on $G={SL}(2,{\mathbb C})$ of arbitrary type $δ\in \hat K$, where $K={SU}(2)$. This is accomplished by associating to a spherical function $Φ$ on $G$ a matrix valued function $H$ on the three dimensional hyperbolic space ${\mathbb H}=G/K$. The entries of $H$ are solutions of two

Kentaro Hamachi

We study a quantum moment map and propose an invariant for $G$-invariant star products on a $G$-transitive symplectic manifold. We start by describing a new method to construct a quantum moment map for $G$-invariant star products of Fedosov type. We use it to obtain an invariant that is invariant under $G$-equivalence. In the last section we give two simple

M. Mueger, J. E. Roberts, L. Tuset

We give a pedagogical survey of those aspects of the abstract representation theory of quantum groups which are related to the Tannaka-Krein reconstruction problem. We show that every concrete semisimple tensor *-category with conjugates is equivalent to the category of finite dimensional non-degenerate *-representations of a discrete algebraic quantum group

John M Sullivan

The ropelength of a knot is the quotient of its length by its thickness. We consider a family of energy functions for knots, depending on a power p, which approach ropelength as p increases. We describe a numerically computed trefoil knot which seems to be a local minimum for ropelength; there are nearby critical points for the p-energies, which are evidentl

Ivan Izmestiev, Michael Joswig

A canonical branched covering over each sufficiently good simplicial complex is constructed. Its structure depends on the combinatorial type of the complex. In this way, each closed orientable 3-manifold arises as a branched covering over the 3-sphere from some triangulation of S^3. This result is related to a theorem of Hilden and Montesinos. The branched c

Anand Dessai

Let $M$ be a $Spin$-manifold with $S^1$-action and let $σ\in S^1$ be of finite order. We show that the indices of certain twisted Dirac operators vanish if the action of $σ$ has sufficiently large fixed point codimension. These indices occur in the Fourier expansion of the elliptic genus of $M$ in one of its cusps. As a by-product we obtain a new proof of a

Z. Haba

We calculate the effective action in Yang-Mills and scalar ϕ^4 quantum field theory with quantized scale invariant metric treated non-perturbatively in d=4 dimensions. There is no charge renormalization in the one-loop order for matter fields. We show that the electromagnetic energy of point charges can be finite. The temperature dependence of the effective

Bindu A. Bambah, C. Mukku, M. S. Sriram, S. Lakshmibala

We review here the work done on the occurence of chaotic configurations in systems derived from Gauge theories. These include Yang-Mills and associated field theories with modifications including Chern Simons and Higgs fields.

Bo Feng, Yang-Hui He, Nicolas Moeller

We solve the problem of finding all eigenvalues and eigenvectors of the Neumann matrix of the matter sector of open bosonic string field theory, including the zero modes, and switching on a background B-field. We give the discrete eigenvalues as roots of transcendental equations, and we give analytical expressions for all the eigenvectors.

Z. Fodor, S. D. Katz, A. Ringwald

We consider the possibility that a large fraction of the ultrahigh energy cosmic rays are decay products of Z bosons which were produced in the scattering of ultrahigh energy cosmic neutrinos on cosmological relic neutrinos. We compare the observed ultrahigh energy cosmic ray spectrum with the one predicted in the above Z-burst scenario and determine the req

M. Fukugita, T. Yanagida

A `new&#39; scenario is proposed for baryogenesis. We show that delayed decay of coloured Higgs particles in grand unified theories may generate excess baryon number of the empirically desired amount, if the mass of the heaviest neutrino is in the range $0.02 {\rm eV}<m_{ν_3}< 0.8 {\rm eV}$, provided that neutrinos are of the Majorana type. The scenario acco

Matthias Frink, Bastian Kubis, Ulf-G. Meißner

We calculate the one-loop contributions to the difference Δ_{πK} between the isoscalar on-shell pion-kaon scattering amplitude at the Cheng-Dashen point and the scalar form factor Γ_K (2M_π^2) in the framework of three flavor chiral perturbation theory. These corrections turn out to be small. This is further sharpened by treating the kaons as heavy fields (t

De-Min Li, Hong Yu, Qi-Xing Shen

It is pointed out that the omission of the effects of the transition between quarkonia or the assumption that the transition between quarkonia is flavor-independent would result in the inconsistent results for the pseudoscalar meson nonet. It is emphasized that the mass relation of the non-ideal mixing meson nonets should incorporate the effects of the flavo

Masaaki Fujii, K. Hamaguchi, T. Yanagida

If the baryon asymmetry in the present universe is generated by decays of the $L H_u$ flat direction, the observed baryon asymmetry requires the mass of the lightest neutrino to be much smaller than the mass scale indicated from the atmospheric and solar neutrino oscillations. Such a small mass of the lightest neutrino leads to a high predictability on the r

W. J. Huo, T. F. Feng

We investigate the newly observed muon $g_μ-2$ anomaly in the framework of a sequential fourth generation model with a heavy fourth neutrino, $ν&#39;$. We find that $g_μ-2$ can exclude most values of $m_{ν&#39;}$ and put a very stringent constraint on the existence of the fourth generation. We also obtain bounds of a $4\times 4$ leptonic mixing matrix elemen

D. Bardin, G. Passarino, L. Kalinovskaya, P. Christova

In this paper we describe the present status and our plans for the realization of next phases of the CalcPHEP project aimed at the theoretical support of experiments at modern and future accelerators: TEVATRON, LHC, electron Linear Colliders (LC&#39;s) i.e. TESLA, NLC, CLIC, and muon factories. Within this project, we are creating a four-level computer syste

J. W. Moffat

Spacetime geometry is treated as a fluctuating, stochastic quantum system allowing an effective quantum gravity solution to the cosmological constant problem. A Focker-Planck equation for the probability density of spacetime metric fluctuations is solved for an FRW universe and the most probable value for the metric scale factor R is for a very small cosmolo

H. Wittig

I report on cost estimates and algorithmic performance in simulations using 2 flavours of non-perturbatively O(a) improved Wilson quarks together with the Wilson plaquette action.

A. G. Agnese, M. La Camera

A one-parameter family of static and spherically symmetric solutions to Einstein equations with a traceless energy-momentum tensor is found. When the nonzero parameter $β$ lies in the open interval $(0,1)$ one obtains traversable Lorentzian wormholes. One also obtains naked singularities when either $β< 0$ or $β> 1$ and the Schwarzschild black hole for $β= 1

Gerhard Rein

Spacetimes with collisionless matter evolving from data on a compact Cauchy surface with hyperbolic symmetry are shown to be timelike and null geodesically complete in the expanding direction, provided the data satisfy a certain size restriction.

David Bremner, Alexander Golynski

In this note we consider the problem of manufacturing a convex polyhedral object via casting. We consider a generalization of the sand casting process where the object is manufactured by gluing together two identical faces of parts cast with a single piece mold. In this model we show that the class of convex polyhedra which can be enclosed between two concen

Soumen Chakrabarti, Mukul M. Joshi, Kunal Punera, David M. Pennock

The Web graph is a giant social network whose properties have been measured and modeled extensively in recent years. Most such studies concentrate on the graph structure alone, and do not consider textual properties of the nodes. Consequently, Web communities have been characterized purely in terms of graph structure and not on page content. We propose that

B. Noheda, D. E. Cox, G. Shirane, Z. -G. Ye

Synchrotron x-ray powder diffraction measurements have been performed on unpoled ceramic samples of (1-x)PbMg(1/3)Nb(2/3)O3-xPbTiO3 (PMN-xPT) with 30%<= x<= 39% as a function of temperature around the morphotropic phase boundary (MPB), which is the line separating the rhombohedral and tetragonal phases in the phase diagram. The experiments have revealed very

J. E. Guyer, W. J. Boettinger, J. A. Warren, G. B. McFadden

We present the first application of phase field modeling to electrochemistry. A free energy functional that includes the electrostatic effect of charged particles leads to rich interactions between concentration, electrostatic potential, and phase stability. The present model, explored for the equilibrium planar interface, properly predicts the charge separa

Richard Metzler, Andreas Engel

We study the game of Dots-and-Boxes from a statistical point of view. The early game can be treated as a case of Random Sequential Adsorption, with a jamming transition that marks the beginning of the end-game. We derive set of differential equations to make predictions about the state of the lattice at the transition, and thus about the distribution of aval

W. Nolting, C. Santos

We study correlation effects and temperature dependencies in the electronic structure of thin ferromagnetic local-moment films. In a first step the Kondo-lattice model is investigated as a candidate for a proper representation of local-moment ferromagnets. Magnetic and electronic key-quantities as the Curie-temperature and the quasiparticle density of states

M. Leone, A. Vazquez, A. Vespignani, R. Zecchina

We present a detailed study of the phase diagram of the Ising model in random graphs with arbitrary degree distribution. By using the replica method we compute exactly the value of the critical temperature and the associated critical exponents as a function of the minimum and maximum degree, and the degree distribution characterizing the graph. As expected,

S. G. Bhongale, R. Walser, M. J. Holland

Using the prescription of the nonequilibrium statistical operator method, we derive a non-Markovian generalization to the kinetic theory described by Walser {\sl et al.} [Phys. Rev. A {\bf 59}, 3878 (1999)]. Quasi-particle damping and effects arising from the finite duration of a collision are introduced to include terms beyond the Born approximation. Such a

Maia Angelova, A. Frank

An algebraic model based on Lie-algebraic and discrete symmetry techniques is applied to the analysis of thermodynamic vibrational properties of molecules. The local anharmonic effects are described by a Morse-like potential and the corresponding anharmonic bosons are associated with the SU(2) algebra. A vibrational high-temperature partition function and th

Volkhard Buchholtz, Thorsten Poeschel

We discuss a new optimization strategy, which considerably improves the effectivity of evolutionary algorithms applied to a certain class of optimization problems. The basic principle is to solve first a simpler related problem, which is constructed by introducing additional degrees of freedom to the landscape. Starting from the solution in this simplified l

L. Arrachea

We study a mesoscopic metallic ring threaded by a magnetic flux which varies linearly in time PhiM(t)=Phi t with a formalism based in Baym-Kadanoff-Keldysh non-equilibrium Green functions. We propose a method to calculate the Green functions in real space and we consider an experimental setup to investigate the dynamics of the ring by recourse to a transport

Y. Blum, A. Tsukernik, M. Karpovski, A. Palevski

We report on experimental studies of superconductor-ferromagnet layered structures. Strong oscillations of the critical supercurrent were observed with the thickness variation of the ferromagnet. Using known microscopic parameters of Ni, we found reasonable agreement between the period of oscillations and the decay of the measured critical current, and theor

Joachim Sjostrand, Anders Eklund, Anders Karlhede

We study the softening of the edge modes of the compact ferromagnetic v=1 Quantum Hall edge as the strength of the confining potential decreases. To obtain a realistic potential we use a displaced background charge plane. We find a phase transition into a spin textured edge for g<0.012 (g is the ratio betwen the Zeeman and Coulomb energies).

Beata Ziaja, Abraham Szoeke, David van der Spoel, Janos Hajdu

Here we describe model calculations to follow the spatio-temporal evolution of secondary electron cascades in diamond. The band structure of the insulator has been explicitly incorporated into the calculations as it affects ionizations from the valence band. A Monte-Carlo model was constructed to describe the path of electrons following the impact of a singl

F. Haas, G. Manfredi, M. Feix

The dynamics of a quantum plasma can be described self-consistently by the nonlinear Schroedinger-Poisson system. Here, we consider a multistream model representing a statistical mixture of N pure states, each described by a wavefunction. The one-stream and two-stream cases are investigated. We derive the dispersion relation for the two-stream instability an

M. J. Calderón, G. Gómez-Santos, L. Brey

We have studied the critical temperature of Diluted Magnetic Semiconductors by means of Monte Carlo simulations and Coherent-Potential-Approximation (CPA) calculations. In our model for this syste m, the magnetic ions couple with the carriers through an antiferromagnetic exchange interaction, $J$, and an electrostatic interaction $W$. The effective impurity

S. Heinrichs, P. Maass

We develop a theory for the inclusion of adatom interactions in second layer nucleation occurring in epitaxial growth. The interactions considered are due to ring barriers between pairs of adatoms and binding energies of unstable clusters. The theory is based on a master equation, which describes the time development of microscopic states that are specified

Thorsten Poeschel, Clara Saluena, Thomas Schwager

Given an assembly of viscoelastic spheres with certain material properties, we raise the question how the macroscopic properties of the assembly will change if all lengths of the system, i.e. radii, container size etc., are scaled by a constant. The result leads to a method to scale down experiments to lab-size.

Nikolai V. Brilliantov, Thorsten Poeschel

We investigate the evolution of the velocity distribution function of a granular gas composed of viscoelastic particles in the homogeneous cooling state, i.e. before clustering occurs. The deviation of the velocity distribution function from the Maxwellian distribution is quantified by a Sonine polynomials expansion. The first non-vanishing Sonine coefficien

Atushi Ishikawa, Tadao Suzuki, Masashi Tomoyose

The results of R^2 dynamical random surface model (2-dimensional quantum gravity with a $R^2$ term) are applied to explain the personal income distribution. A scale invariance exists if there is not the $R^2$ term in the action. The R^2 term provides a typical scale and breaks the scale invariance explicitly in the low and middle income range. A new distribu

Virgile. Viasnoff, Francois Lequeux, D. J. Pine

A multispeckle technique for efficiently measuring correctly ensemble-averaged intensity autocorrelation functions of scattered light from non-ergodic and/or non-stationary systems is described. The method employs a CCD camera as a multispeckle light detector and a computer-based correlator, and permits the simultaneous calculation of up to 500 correlation f

G. Manfredi, F. Haas

It is shown that, for a large class of statistical mixtures, the Wigner-Poisson (or Hartree) system can be reduced to an effective Schroedinger-Poisson system, in which the Schroedinger equation contains a new nonlinearity. For the case of a zero-temperature one-dimensional electron gas, this additional nonlinearity is of the form Psi^4. In the long waveleng

Andrew C. T. Wong, Hua Sun, K. W. Yu

The theoretical investigations on electrorheological (ER) fluids are usually concentrated on monodisperse systems. Real ER fluids must be polydisperse in nature, i.e., the suspended particles can have various sizes and/or different dielectric constants. An initial approach for these studies would be the point-dipole (PD) approximation, which is known to err

Tim Biggs, Anne-Katrin Klehe, John Singleton, David Bakker

Details of the Fermi-surface topology of deuterated $κ$-(BEDT-TTF)$_2$Cu(NCS)$_2$ ~have been measured as a function of pressure, and compared with equivalent measurements of the undeuterated salt. We find that the superconducting transition temperature is much more dramatically suppressed by increasing pressure in the deuterated salt. It is suggested that th

Karen S. Bjorkman, Anatoly S. Miroshnichenko, David McDavid, Tatiana M. Pogrosheva

We present the results of recent multicolor photometric and high-resolution spectroscopic observations of the bright Be star Pi Aquarii. Observational data collected from the literature were used to study the star&#39;s variations over the last four decades. The star is identified with the IR sources F22227+0107 in the IRAS Faint Point Source catalog and MSX

Andrew E. Dolphin, Robert C. Kennicutt,

We present a statistical system that can be used in the study of cluster populations. The basis of our approach is the construction of synthetic cluster color-magnitude-radius diagrams (CMRDs), which we compare with the observed data using a maximum likelihood calculation. This approach permits a relatively easy incorporation of incompleteness (a function of

P. Cox, A. Omont, S. G. Djorgovski, F. Bertoldi

Using the IRAM interferometer we have detected J=4-3 and 5-4 CO line emission toward the radio quiet quasar PSS2322+1944. At a redshift of z_CO=4.1199 this is the fourth and strongest detection of CO at z>4. The velocity-integrated CO J=4-3 and J=5-4 line fluxes are 4.21+-0.40 and 3.74+-0.56 Jy km/s, and the linewidth is ~300 km/s. The CO J=10-9 line was sea

Rami Doron, Ehud Behar

The theoretical intensities of the soft X-ray Fe XVII lines arising from 2l-3l&#39; transitions are reexamined using a three-ion collisional-radiative model that includes the contributions to line formation of radiative recombination (RR), dielectronic recombination (DR), resonant excitation (RE), and inner-shell collisional ionization (CI), in addition to t

Steven A. Balbus, John F. Hawley

We review numerical simulations of MHD turbulence. The last decade has witnessed fundamental advances both in the technical capabilities of direct numerical simulation, and in our understanding of key physical processes. Magnetic fields tap directly into the free energy sources in a sufficiently ionized gas. The result is that adverse angular velocity and ad

M. Orito, T. Kajino, G. J. Mathews, Y. Wang

We reanalyze the cosmological constraints on the existence of a net universal lepton asymmetry and neutrino degeneracy based upon the latest high resolution CMB sky maps from BOOMERANG, DASI, and MAXIMA-1. We generate likelihood functions by marginalizing over $(\omegab h^2,\xinumt, \xinue, Ω_Λ,h,n)$ plus the calibaration uncertainties. We consider flat $Ω_M

W. S. Dias, B. S. Alessi, A. Moitinho, J. R. D. Lepine

We have compiled a new catalogue of open clusters in the Galaxy which updates the previous catalogues of Lynga (1987) and of Mermilliod (1995) (included in the WEBDA database). New objects and new data, in particular, data on kinematics (proper motions) that were not present in the old catalogues, have been included. Virtually all the clusters (1537) present

A. Finoguenov, R. P. Kudritzki, C. Jones

We propose a method to test for the presence of intracluster star-light using X-ray binaries as a trace population. We discuss a particular application of this method to observations of the Virgo cluster.

Jay D. Salmonson, James R. Wilson

In this paper we present a model for the short (< second) population of gamma-ray bursts (GRBs). In this model heated neutron stars in a close binary system near their last stable orbit emit neutrinos at large luminosities (~ 10^53 ergs/sec). A fraction of these neutrinos will annihilate to form an electron-positron pair plasma wind which will, in turn, expa

T. S. Metcalfe, M. Salaris, D. E. Winget

During helium burning in the core of a red giant, the relative rates of the 3&alpha and ^{12}C(&alpha,&gamma)^{16}O reactions largely determine the final ratio of carbon to oxygen in the resulting white dwarf star. The uncertainty in the 3&alpha reaction at stellar energies due to the extrapolation from high-energy laboratory measurements is relatively small

Chun S. J. Pun, Eli Michael, Svetozar A. Zhekov, Richard McCray

We report and interpret HST/STIS long-slit observations of the optical and ultraviolet (1150 - 10270 Angstrom) emission-line spectra of the rapidly brightening Spot 1 on the equatorial ring of SN 1987A between 1997 September and 1999 October (days 3869 -- 4606 after outburst). The emission is caused by radiative shocks created where the supernova blast wave

Roberto Soria, Albert K. H. Kong

The face-on spiral galaxy M74 (NGC 628) was observed by XMM on 2002 February 2. In total, 21 sources are found in the inner 5&#39; from the nucleus (after rejection of a few sources associated to foreground stars). Hardness ratios suggest that about half of them belong to the galaxy. The higher-luminosity end of the luminosity function is fitted by a power-l

A. De Rosa, L. Piro, F. Fiore, P. Grandi

BeppoSAX observed the Seyfert 1 galaxy NGC 3783 for ~ 5 days from 1998 June 6 to 1998 June 10. The average flux during the observation was F(2-10 keV) ~ 6 X 10^{-11} erg cm^-2 s^-1. The long exposure provided a very high quality spectrum that exhibits all the typical features of Seyfert 1s. The high energy cut-off of the intrinsic continuum, at E_c=340+560/-

B. W. Miller, J. Turner, M. Takamiya, D. Simons

We give an overview of the current and future IFU capabilities on the Gemini 8-m telescopes. The telescopes are well-suited to integral field spectroscopy and both telescopes will have optical and near-infrared IFUs within the next few years. Commissioning for the GMOS IFU on Gemini North has begun recently and it is now available to the community. Future in

E. Lastennet, J. Fernandes, Th. Lejeune

Johnson BVRI photometric data for individual components of binary systems have been provided by ten Brummelaar et al. (2000). This is essential because such binaries could play a critical role in calibrating the single-star stellar evolution theory. While they derived the effective temperature from their estimated spectral type, we infer metallicity-dependen

F. Matteucci

In this series of lectures I discuss the basic principles and the modelling of the chemical evolution of galaxies. In particular, I present models for the chemical evolution of the Milky Way galaxy and compare them with the available observational data. From this comparison one can infer important constraints on the mechanism of formation of the Milky Way as

M. A. Urbaneja, A. Herrero, R. P. Kudritzki, F. Bresolin

We present terminal velocities of M33 B-supergiants, obtained from STIS HST spectra as part of our programme to investigate the Wind Momentum -- Luminosity Relationship (WLR) in the Local Group. Terminal velocities are derived from their NV, CIV, and SiIV resonance lines in UV spectra. Comparing with IUE spectra of Galactic B-supergiants we found evidence of

F. Mantovani, W. Junor, R. Ricci, D. J. Saikia

Two Compact Steep-spectrum Sources (CSSs), 0548+165 and 1524-136, chosen from a list of CSSs with polarization percentages that decrease with decreasing frequency and high rotation measure values (RM > 450 rad/m**2) on arcsecond scales, were observed with the VLBA at 4.9 and 8.4 GHz. RM values up to ~10**4 rad/m**2 were found in several regions along the jet

A. Smialkowski, M. Giller, W. Michalak

Ultra High Energy (UHE) particles coming from discrete extragalactic sources are potential candidates for EAS events above a few tens of EeV. In particular, galaxies with huge infrared luminosity triggered by collision and merging processes are possible sites of UHECR acceleration. Using the PSCz catalogue of IR galaxies we calculate a large scale anisotropy

Berrie Giebels, Elliott D. Bloom, Warren Focke, Gary Godfrey

This paper reports X-ray spectral observations of a relatively nearby z = 0.048 BL Lacertae (BL Lac) object 1ES1959+650, which is a potential TeV emitter. The observations include 31 short pointings made by the Unconventional Stellar Aspect (USA) Experiment on board the Advanced Research and Global Observation Satellite (ARGOS), and 17 pointings by the PCA o

Michael Balogh, Warrick J. Couch, Ian Smail, Richard G. Bower

(Abridged) We present results of an H-alpha survey in the rich cluster A1689 at z=0.18, using the LDSS++ spectrograph on the AAT. We obtained spectra covering redshifted H-alpha for 522 galaxies brighter than I=22.5, covering a field of 8.7&#39;X8.7&#39;. We detect H-alpha emission in 46 of these galaxies; accounting for selection effects due to sampling and

R. S. Warwick

Observational programmes currently underway with both Chandra and XMM-Newton are set to revolutionize our view of our own Galaxy. This is fortunate since the X-ray band can provide crucial diagnostics in the quest to understand the composition and structure of the Galaxy and the high energy processes which influence its evolution. Here we review several area

Ranjeev Misra, R. E. Taam

The vertical structure of optically thick accretion disks is investigated in the two-zone approximation. The disk is divided into an underlying disk and a corona, where the latter is defined as the upper surface layers for which the effective optical depth is unity. It is found that a significant part of the accretion flow (or dissipation rate) can take plac

Giulio Auriemma

In this paper we compare the results of the MACRO detector at Gran Sasso, that is the largest neutrino telescope operated before the year 2k, with theoretical predictions of the neutrino emission from some promising targets, such as blazars and GRB&#39;s. In particular we propose a new statistical method, justified by the maximum entropy principle, for asses

Norbert Straumann

In this article the cosmological constant problems, as well as the astronomical evidence for a cosmologically significant homogeneous exotic energy density with negative pressure (quintessence), are reviewed for a broad audience of physicists and mathematicians. After a short history of the cosmological term it is explained why the (effective) cosmological c

F. Matteucci, A. Pipino

We have compared the results from a model for the chemical evolution of an elliptical galaxy with initial luminous mass of 2x10^10 M_sun and effective radius of 2 kpc with the recent abundance determinations for the Lyman-break galaxy MS 1512-cB58 at a redshift z=2.7276. After correcting the iron abundance determination for the presence of dust we concluded

Albert A. Zijlstra, T. R. Bedding, J. A. Mattei

The Mira variable R Hydrae is well known for its declining period, which Wood & Zarro (1981) attributed to a possible recent thermal pulse. Here we investigate the long-term period evolution, covering 340 years, going back to its discovery in AD 1662. Wavelets are used to determine both the period and semi-amplitude. We show that the period decreased linearl

V. Castellani, S. Degl&#39;Innocenti, P. G. Prada Moroni, V. Tordiglione

By relying on recently improved Hipparcos parallaxes for the Hyades, Pleiades and Ursa Major clusters we find that stellar models with updated physical inputs nicely reproduce the location in the color magnitude diagram of main sequence stars of different metallicities. Stars in the helium burning phase are also discussed, showing that the luminosity of gian

Albert A. Zijlstra, Ronald Weinberger

We present the discovery of a huge (19$\arcmin$ $\times$ 16$\arcmin$) dust ring surrounding a bright (V = 10.60) red star. The dust ring has, at D = 700 pc, a diameter of 4 pc, and a central hole of ~1.5 pc across. Part of the shell is also seen as an absorption nebulosity. The star is classified as a M3III AGB star. Among AGB stars its detached shell is of

P. Varniere, J. Rodriguez, M. Tagger

The Accretion-Ejection Instability has been proposed to explain the low frequency Quasi-Periodic Oscillation (QPO) observed in low-mass X-Ray Binaries, in particular Black-Hole candidates. Its frequency, typically a fraction of the Keplerian frequency at the disk inner radius, is exactly in the range indicated by observations. The variations of the frequency

J. Rodriguez, P. Varniere, M. Tagger, Ph. Durouchoux

This is the first of two papers in which we address the physics of the low-frequency Quasi-Periodic Oscillation (QPO) of X-ray binaries, in particular those hosting a black hole. We discuss and repeat the recent analysis and spectral modelling of the micro-quasar GRO J1655 by Sobczak et al (2000, hereafter SMR), and compare it with GRS 1915; this leads us to

T. Kato

HL CMa is a Z Cam-type dwarf nova which was discovered as an Einstein X-ray source. In addition to normal outbursts and standstills, we noticed the presence of &#34;the third&#34; outbursting state. During this period, the star showed weak outbursts with a long outburst cycle length. We propose that this phenomenon is caused by a heating on the accretion dis