January 2001 arXiv papers — page 23

Kester W. Smith, Ian A. Bonnell

We have simulated encounters between planetary systems and single stars in various clustered environments. This allows us to estimate the fraction of systems liberated, the velocity distribution of the liberated planets, and the separation and eccentricity distributions of the surviving bound systems. Our results indicate that, for an initial distribution of

S. Michael Fall

This article outlines a method to interpret the extragalactic background light in terms of the large-scale, average properties of galaxies, including the comoving densities of stars and interstellar gas, metals, and dust. These quantities are related by a series of coupled conservation-type equations analogous to the equations of galactic chemical evolution.

Daniela Kirilova, Mihail Chizhov

We analyze the effects of lepton asymmetry on neutrino oscillations and on cosmological nucleosynthesis with active-sterile oscillating neutrinos. It is shown that small lepton asymmetries, L < 0.01, whose direct kinetic effect on nucleosynthesis is negligible, still effect nucleosynthesis considerably through their influence on oscillating neutrinos. Two di

S. Michael Fall

This article reviews three related topics: the extragalactic background l ight and its sources, evolution models for the dust absorption and emission in galaxies, and empirical constraints on these transfer pr ocesses in nearby starburst galaxies. It is intended that the material presented here will serve as an introduction to this Joint Discussion.

R. Capuzzo-Dolcetta

The interpretation of the difference observed between the radial distribution of globular clusters and that of halo-bulge stars in elliptical galaxies is discussed in terms of evolution of their globular cluster systems. I present a short summary of the evidence that dynamical evolution of globular cluster systems is not only able to explain the flattening o

R. Capuzzo-Dolcetta, I. Donnarumma

We studied and compared the radial profiles of globular clusters and of the stellar bulge component in three galaxies of the Fornax cluster observed with the WFPC2 of the HST. A careful comparative analysis of these distributions confirms that stars are more concentrated toward the galactic centres than globular clusters, in agreement with what was observed

A. Akylas, I. Georgantopoulos, A. Comastri

We investigate the X-ray spectra of the type-2 Seyfert galaxies NGC 7172 and ESO 103-G35, using BeppoSAX observations, separated by approximately one year. We find that the X-ray spectra of both NGC 7172 and ESO 103-G35 can be well fitted using a power-law model with an Fe K emission line at 6.4 keV. We did not find any statistically significant evidence for

P. Ciecielag, M. Chodorowski, A. Kudlicki

We use numerical simulations to study the relation between the velocity of the Local Group and its gravitational acceleration. This relation serves as a test for the kinematic origin of the CMB dipole and as a method for estimating beta. We calculate the misalignment angle between the two vectors and compare it to the observed value for the PSCz survey. The

I. Georgantopoulos, K. Nandra, A. Ptak

We present the first results of the hard (5-10 keV) ASCA GIS survey SHEEP (Search for the High Energy Extragalactic Population). We have analysed 149 fields covering an area of 39 sq. deg detecting 69 sources. Several of these appear to be associated with QSOs and Seyfert-1 galaxies but with hard X-ray spectra, probably due to high absorption. Indeed, the ha

S. Veilleux, G. Cecil, J. Bland-Hawthorn, P. L. Shopbell

Recent results from a multiwavelength survey of spatially resolved outflows in nearby active galaxies are presented. Optical Fabry-Perot and long-slit spectroscopic data are combined with VLA and ROSAT images, when available, to probe the warm, relativistic and hot gas components involved in the outflow. The emphasis is put on objects which harbor wide-angle

Christian Reichardt, Raul Jimenez, Alan Heavens

We derive physical parameters of galaxies from their observed spectrum, using MOPED, the optimized data compression algorithm of Heavens, Jimenez & Lahav 2000. Here we concentrate on parametrising galaxy properties, and apply the method to the NGC galaxies in Kennicutt&#39;s spectral atlas. We focus on deriving the star formation history, metallicity and dus

T. V. Shahbazyan, I. E. Perakis, M. E. Raikh

We study theoretically the luminescence from quantum dots of a ring geometry. For high excitation intensities, photoexcited electrons and holes form Fermi seas. Close to the emission threshold, the single-particle spectral lines aquire weak many-body satellites. However, away from the threshold, the discrete luminescence spectrum is completely dominated by m

Jamal Jalilian-Marian, Kostas Orginos, Ina Sarcevic

We present a detailed study of prompt photon production cross section in heavy-ion collisions in the central rapidity region at energy of $\sqrt{s}=5.5$ TeV, appropriate to LHC experiment. We include the next-to-leading order radiative corrections, $O(α_{em}α_s^2)$, nuclear shadowing and the parton energy loss effects. We find that the nuclear effects can re

J. C. Lee, P. M. Ogle, C. R. Canizares, H. L. Marshall

We present detailed evidence for a warm absorber in the Seyfert 1 galaxy MCG--6-30-15 and dispute earlier claims for relativistic O line emission. The HETG spectra show numerous narrow, unresolved (FWHM < 200 km/s) absorption lines from a wide range of ionization states of N, O, Mg, Ne, Si, S, Ar, and Fe. The O VII edge and 1s^2--1snp resonance line series t

M. Ostrowski, J. Bednarz

The first-order Fermi acceleration process at an ultra-relativistic shock wave is expected to create a particle spectrum with the unique asymptotic spectral index sigma_{gamma >> 1} approximately 2.2. Below, we discuss this result and differences in its various derivations, which -- explicitly or implicitly -- always require highly turbulent conditions downs

Charles Livingston

If a knot K has Seifert matrix V_K and has a prime power cyclic branched cover that is not a homology sphere, then there is an infinite family of non-concordant knots having Seifert matrix V_K.

Ian I. Kogan, Alex Kovner, Bayram Tekin

We draw an analogy between the deconfining transition in the 2+1 dimensional Georgi-Glashow model and the chiral phase transition in 3+1 dimensional QCD. Based on the detailed analysis of the former (hep-th/0010201) we suggest that the chiral symmetry restoration in QCD at high temperature is driven by the thermal ensemble of baryons and anti-baryons. The ch

F. Schlesener, A. Hanke, R. Klimpel, S. Dietrich

The depletion interaction between two parallel repulsive walls confining a dilute solution of long and flexible polymer chains is studied by field-theoretic methods. Special attention is paid to self-avoidance between chain monomers relevant for polymers in a good solvent. Our direct approach avoids the mapping of the actual polymer chains on effective hard

R. Foot

Over the last few years, many close orbiting ($\sim 0.05$ A.U.) large mass planets ($\sim M_{J}$) of nearby stars have been discovered. Their existence has been inferred from tiny Doppler shifts in the light from the star and in one case a transit has been observed. Because ordinary planets are not expected to be able to form this close to ordinary stars due

Charles R. Keeton, Piero Madau

The statistics of wide-separation (6&#39;&#39; < theta < 15&#39;&#39;) gravitational lenses constrain the amount of mass in the cores of dark matter halos on group and cluster mass scales. For a family of halo models with a central cusp $ρ\propto r^{-alpha}$ (1.0 <= alpha <= 1.9), the lack of wide-separation lenses in the large Cosmic Lens All-Sky Survey yie

M. Ostrowski

We shortly discuss several astrophysical scenarios leading to cosmic ray acceleration up to extremely high energies reaching the scale of 10^{20} eV. The processes suggested in the literature include acceleration at relativistic jet terminal shocks and shear boundary layers, shocks in large scale accretion flows onto supergalactic cosmic structures, particle

R. T. Senger, B. Tanatar

We study the energy-transfer rate for electrons in a double-quantum-well structure, where the layers are coupled through screened Coulomb interactions. The energy-transfer rate between the layers (similar to the Coulomb drag effect in which the momentum transfer rate is considered) is calculated as functions of electron densities, interlayer spacing, the tem

Jihn E. Kim, Bumseok Kyae, Hyun Min Lee

We present a self-tuning solution of the cosmological constant problem with one extra dimension which is curved with a warp factor. To separate out the extra dimension and to have a self-tuning solution, a three index antisymmetric tensor field is introduced with the $1/H^2$ term in the Lagrangian. The standard model fields are located at the $y=0$ brane. Th

Amitava Datta, Anirban Kundu, Abhijit Samanta

We show how the spectrum of the minimal anomaly-mediated supersymmetry breaking model can be constrained from the condition that the electroweak symmetry breaking minimum of the scalar potential is the deepest point in the field space. Applying the current experimental bounds and scanning over the whole parameter space, we rule out selectrons below 378 GeV a

A. N. F. Aleixo, A. B. Balantekin, M. A. Candido Ribeiro

A class of shape-invariant bound-state problems which represent transition in a two-level system introduced earlier are generalized to include arbitrary energy splittings between the two levels as well as intensity-dependent interactions. We show that the couple-channel Hamiltonians obtained correspond to the generalizations of the nonresonant and intensity-

R. Srikanth

In order to understand whether nonlocality implies information transfer, a quantum optical experimental test, well within the scope of current technology, is proposed. It is essentially a delayed choice experiment as applied to entangled particles. The basic idea is: given two observers sharing position-momentum entangled photons, one party chooses whether s

A. Vidiella-Barranco, Luis M. Arevalo-Aguilar, H. Moya-Cessa

We present a method of solving master equations which may describe, in their most general form, phase sensitive processes such as decay and amplification. We make use of the superoperator technique.

K. J. Resch, J. S. Lundeen, A. M. Steinberg

We demonstrate suppression and enhancement of spontaneous parametric down- conversion via quantum interference with two weak fields from a local oscillator (LO). Pairs of LO photons are observed to upconvert with high efficiency for appropriate phase settings, exhibiting an effective nonlinearity enhanced by at least 10 orders of magnitude. This constitutes

Matthew J. Donald

In ``Quantum Evolution: Life in the Multiverse&#39;&#39; (HarperCollins, 2000), ISBN 0-00-255948-X, 0-00-655128-9, Johnjoe McFadden makes far-reaching claims for the importance of quantum physics in the solution of problems in biological science. In this review, I discuss the relevance of unitary wavefunction dynamics to biological systems, analyse the inver

Osamu Hirota, Masahide Sasaki

Properties of entangled states based on nonorthogonal states are clarified. Especially, it is shown that they can have complete degree of entanglement.

Wim van Dam, Sean Hallgren

We introduce the Shifted Legendre Symbol Problem and some variants along with efficient quantum algorithms to solve them. The problems and their algorithms are different from previous work on quantum computation in that they do not appear to fit into the framework of the Hidden Subgroup Problem. The classical complexity of the problem is unknown despite the

Th. Udem, S. A. Diddams, K. R. Vogel, C. W. Oates

The frequency comb created by a femtosecond mode-locked laser and a microstructured fiber is used to phase coherently measure the frequencies of both the Hg^+ and Ca optical standards with respect to the SI second as realized at NIST. We find the transition frequencies to be f_Hg=1 064 721 609 899 143(10) Hz and f_Ca=455 986 240 494 158(26) Hz, respectively.

M. Tada, Y. Kishimoto, M. Shibata, K. Kominato

A coupled microwave-cavity system of cylindrical TM$_{010}$ single-mode has been developed to search for dark matter axions around 10 $μ{\rm eV}$(2.4 GHz) with the Rydberg-atom cavity detector at 10 mK range temperature. One component of the coupled cavity (conversion cavity) made of oxygen-free high-conductivity copper is used to convert an axion into a sin

Alexander Rauh

There is renewed interest in the question of whether the Navier-Stokes equations (NSE), one of the fundamental models of classical physics and widely used in engineering applications, are actually self-consistent. After recalling the essential physical assumptions inherent in the NSE, the notion of weak solutions, possible implications for the energy conserv

Alexander Rauh

A comparative discussion of the normal form and action angle variable method is presented in a tutorial way. Normal forms are introduced by Lie series which avoid mixed variable canonical transformations. The main interest is focused on establishing a third integral of motion for the transformed Hamiltonian truncated at finite order of the perturbation param

Alexander Rauh

A generalized Lyapunov method is outlined which predicts global stability of a broad class of dissipative dynamical systems. The method is applied to the complex Lorenz model and to the Navier-Stokes equations. In both cases one finds compact domains in phase space which contain the omega sets of all trajectories, in particular the fixed points, limit cycles

S. A. Fayans, S. V. Tolokonnikov, E. L. Trykov, D. Zawischa

The foundation of the local energy-density functional method to describe the nuclear ground-state properties is given. The method is used to investigate differential observables such as the odd-even mass differences and odd-even effects in charge radii. For a few isotope chains of spherical nuclei, the calculations are performed with an exact treatment of th

M. Betigeri, J. Bojowald, A. Budzanowski, A . Chatterjee

The present data support a large anisotropy in accordance with phase shift predictions and in contrast to another recent experiment.

B. Dubrulle

We use an analytic toy model of turbulent convection to show that most of the scaling regimes are spoiled by logarithmic corrections, in a way consistent with the most accurate experimental measurements available nowadays. This sets a need for the search of new measurable quantities which are less prone to dimensional theories.

Kevin R. Vixie, Gary L. Sandine

The problem of determining three-dimensional density fields from single two-dimensional projections is hopelessly underdetermined without additional assumptions. While parameterized inversions are typically used to solve this problem, we present theoretical results along a different route to the elimination of indeterminacy. Suppose that we have a series of

Franc Forstneric, Jasna Prezelj

Let X be a Stein manifold and let Y be a complex manifold which admits a spray in the sense of Gromov (Oka&#39;s principle for holomorphic sections of elliptic bundles, J. Amer. Math. Soc. 2, pp. 851-897 (1989)). We prove that for every closed complex subvariety X_0 of X and for every continuous map f_0 from X to Y whose restriction to X_0 is holomorphic the

Franc Forstneric

We construct closed complex submanifolds of dimension three in C^5 which are differential complete intersections but not holomorphic complete intersections. We also prove a homotopy principle concerning the removal of intersections of holomorphic mappings from Stein manifolds to complex Euclidean spaces C^d with certain closed complex subvarities of C^d.

Craig R Guilbault

The notion of an open collar is generalized to that of a pseudo-collar. Important properties and examples are discussed. The main result gives conditions which guarantee the existence of a pseudo-collar structure on the end of an open n-manifold (n > 6). This paper may be viewed as a generalization of Siebenmann&#39;s famous collaring theorem to open manifol

Alexander M. Chebotarev

Mean values of some observables describing quantum interaction between the Bose field in a cavity and a movable mirror can be represented as expectations of rapidly oscillating functions w.r.t. the Poisson measure with a large mean value ($N\approx 10^{23}$) corresponding to the average number of photons in laser beam. Straightforward summation of the series

Yoshinori Namikawa

In this paper we shall prove that the singular locus of a symplectic singularity has no codimension 3 irreducible components. As a corollary, a symplectic singularity is terminal if and only if its singular locus has codimension $\geq 4$. It is hoped that a symplectic singularity has much stronger properties.

David De Wit

We detail the automatic construction of R matrices corresponding to (the tensor products of) the (0|α) families of highest-weight representations of the quantum superalgebras U_q[gl(m|n)]. These representations are irreducible, contain a free complex parameter α, and are 2^{mn} dimensional. Our R matrices are actually (sparse) rank 4 tensors, containing a to

Mark Gross

We explore a number of examples of special Lagrangian fibrations on non-compact Calabi-Yau manifolds invariant under torus actions. These include fibrations on crepant resolutions of canonical toric singularities (already found by Goldstein), proper versions of these fibrations, and fibrations on flat deformations of canonical toric singularities. We do this

Jussi Kalkkinen, Dario Martelli

We discuss Holographic Renormalization Group equations in the presence of fermions and form fields in the bulk. The existence of a holographically dual quantum field theory for a given bulk gravity theory imposes consistency conditions on the ranks of the form fields, the fermion - form field couplings, and leads to a novel Ward identity.

A. Ioannisian

We discuss the phenomenological consequences of theories which describe sterile neutrinos in large extra dimensions. We show that the Kaluza-Klein tower of the singlet neutrinos, albeit tiny individual contribution in electroweak processes, act cumulatively, giving rise to non-universality of the weak interactions of the light neutrinos and to flavour-violat

Miloslav Znojil

Supersymmetry between bosons and fermions is modeled within PT- symmetric quantum mechanics. A non-Hermitian alternative to the Witten&#39;s supersymmetric quantum mechanics is obtained.

Isabela P. Cavalcante, J. Sá Borges

Pion-pion scattering amplitude obtained from one-loop Chiral Perturbation Theory (ChPT) is crossing symmetric, however the corresponding partial-wave amplitudes do not respect exact unitarity relation. There are different approaches to get unitarized results from ChPT. Here we consider the inverse amplitude method (IAM) and, using the Roskies relations, we m

Shigenori Kagiyama, Akira Minaka, Akihiro Nakamura

The evolution of matter produced in nucleus collisions is investigated in the frame work of the simplified fluid equation, where the compressible bag model is used as the equation of state for hadrons. It is shown that the quark-gluon phase is easily achieved in RHIC experiments, and that the typical structure of the phase transition, however, may be difficu

Chun Liu, Jeonghyeon Song

Three light sterile neutrinos (ν_e^s, ν_μ^s and ν_τ^s) are introduced to accommodate all the available neutrino data: the atmospheric neutrino anomaly is explained by ν_μ-ν_μ^s oscillation with maximal mixing; the solar one is due to ν_e-ν_e^s oscillation of small angle Mikheyev-Smirnov-Wolfenstein type; the Liquid Scintillation Neutrino Detector data is fro

Milind V. Diwan, Hong Ma

We have examined the physics and the experimental feasibility of studying various kaon decay processes in which the polarization of a muon in the final state is measured. Valuable information on CP violation, the quark mixing (CKM) matrix, and new physics can be obtained from such measurements. We have considered muon polarization in K_L to mu+ mu- and K to

Valery Telnov

Photon colliders (gamma-gamma, gamma-e) are based on backward Compton scattering of laser light off the high energy electrons of linear colliders. Recent study has shown that the gamma-gamma luminosity in the high energy peak can reach 0.3--0.5 L (e+e-). Typical cross sections of interesting processes in gamma-gamma collisions are higher than those in e+e- c

P. D. Grannis

We summarize some of the main physics questions that will serve to define the linear e+e- collider program, and comment on issues that confront the world community in making such a collider a reality.

I. V. Kanatchikov

A geometric prequantization formula for the Poisson-Gerstenhaber bracket of forms found within the DeDonder-Weyl Hamiltonian formalism earlier is presented. The related aspects of covariant geometric quantization of field theories are sketched. In particular, the importance of the framework of Clifford and spinor bundles and superconnections in this context

Federico Fontana, Davide Rocchesso

Waveguide Meshes are efficient and versatile models of wave propagation along a multidimensional ideal medium. The choice of the mesh geometry affects both the computational cost and the accuracy of simulations. In this paper, we focus on 2D geometries and use multidimensional sampling theory to compare the square, triangular, and hexagonal meshes in terms o

K. W. Madison, F. Chevy, V. Bretin, J. Dalibard

Using a focused laser beam we stir a $^{87}$Rb Bose-Einstein condensate confined in a magnetic trap. We observe that the steady states of the condensate correspond to an elliptic cloud, stationary in the rotating frame. These steady states depend nonlinearly on the stirring parameters (amplitude and frequency), and various solutions can be reached experiment

L. A. Falkovsky

Zone-center phonon frequencies of polar lattices are calculated for uniaxial crystals from the symmetry arguments. Long-range Coulomb forces and crystal anisotropy are explicitly taken into account. Free-carrier contributions into a dielectric constant are included. The angular dispersion of optical-phonon modes is compared with data for hexagonal 6H-SiC pol

D. Thirumalai, D. K. Klimov

We discuss recent theoretical developments in the study of simple lattice models of proteins. Such models are designed to understand general features of protein structures and mechanism of folding. Among the topics covered are (i) the use of lattice models to understand the selection of the limited set of viable protein folds; (ii) the relationship between s

M. Keller, W. Metzner, U. Schollwoeck

We solve the attractive Hubbard model for arbitrary interaction strengths within dynamical mean-field theory. We compute the transition temperature for superconductivity and analyze electron pairing in the normal phase. The normal state is a Fermi liquid at weak coupling and a non-Fermi liquid state with a spin gap at strong coupling. Away from half-filling,

B. Jancovici, L. Šamaj

A two-component Coulomb gas confined by walls made of ideal dielectric material is considered. In two dimensions at the special inverse temperature $β= 2$, by using the Pfaffian method, the system is mapped onto a four-component Fermi field theory with specific boundary conditions. The exact solution is presented for a semi-infinite geometry of the dielectri

Kelly R. Patton, Michael R. Geller

We calculate the rate of energy flow between two macroscopic bodies, each in thermodynamic equilibrium at a different temperature, and joined by a weak mechanical link. The macroscopic solids are assumed to be electrically insulating, so that thermal energy is carried only by phonons. To leading order in the strength of the weak link, modeled here by a harmo

L. Šamaj

The model under consideration is a semi-infinite two-dimensional two-component plasma (Coulomb gas), stable against bulk collapse for the dimensionless coupling constant $β<2$, in contact with a dielectric wall of dielectric constant $=0$. The model is mapped onto an integrable sine-Gordon theory with a ``free&#39;&#39; Neumann boundary condition. Using rece

I. Camps, S. S. Makler, H. M. Pastawski, L. E. F. Foa Torres

The aim of this work is to describe the behavior of a device capable to generate high frequency (~THz) acoustic phonons. This device consists in a GaAs-AlGaAs double barrier heterostructure that, when an external bias is applied, produces a high rate of longitudinal optical LO phonons. These LO phonons are confined and they decay by stimulated emission of a

E. M. Terentjev, M. Warner

We develop a continuum theory of linear viscoelastic response in oriented monodomain nematic elastomers. The expression for dissipation function is analogous to the Leslie-Ericksen version of anisotropic nematic viscosity; we propose the relations between the anisotropic rubber moduli and new viscous coefficients. A new dimensionless number is introduced, wh

I. Camps, S. S. Makler

We make an adaptation of laser modelling equations to describe the behavior of a phonon laser (saser). Our saser consists of an AlGaAs/GaAs double barrier heterostructure designed to generate an intense beam of transversal acoustic (TA) phonons. To study our system, we begin with a Hamiltonian that describes the decay of primary longitudinal optical phonons

V. Kataev, K. -Y. Choi, M. Grüninger, U. Ammerahl

Electron spin resonance data of Cu^{2+} ions in La_{14-x}Ca_{x}Cu_{24}O_{41} crystals (x=9,11,12) reveal a very large width of the resonance line in the paramagnetic state. This signals an unusually strong anisotropy of ~10% of the isotropic Heisenberg superexchange in the Cu-O chains of this compound. The strong anisotropy can be explained by the specific g

M. Felici, G. Caldarelli, A. Gabrielli, L. Pietronero

We study the Bak-Sneppen model in the probabilistic framework of the Run Time Statistics (RTS). This model has attracted a large interest for its simplicity being a prototype for the whole class of models showing Self-Organized Criticality. The dynamics is characterized by a self-organization of almost all the species fitnesses above a non-trivial threshold

G. Parisi, R. Petronzio, F. Rosati

A renormalization group transformation suitable for spin glass models and, more generally, for disordered models, is presented. The procedure is non-standard in both the nature of the additional interactions and the coarse graining transformation, that is performed on the overlap probability measure (which is clearly non-Gibbsian). Universality classes are t

M. Eremin, I. Eremin, S. Varlamov

The analytical expression for dynamical charge susceptibility in layered cuprates has been derived in the frame of singlet-correlated band model beyond random-phase-approximation (RPA) scheme. Our calculations performed near optimal doping regime show that there is a peak in real part of the charge susceptibility $χ({\bf q},ω)$ at {\bf Q} = ($π$, $π$) at str

M. Itakura

We investigate the isotropic-anisotropic phase transition of the two-dimensional XY model with six-fold anisotropy, using Monte Carlo renormalization group method. The result indicates difficulty of observing asymptotic critical behavior in Monte Carlo simulations, owing to the marginal flow at the fixed point.

Evgenii E. Narimanov, Harold U. Baranger, Nicholas R. Cerruti, Steven Tomsovic

We develop a semiclassical theory of Coulomb blockade peak heights in chaotic quantum dots. Using Berry&#39;s conjecture, we calculate the peak height distributions and the correlation functions. We demonstrate that the corrections to the corresponding results of the standard statistical theory are non-universal and can be expressed in terms of the classical

A. K. Arzhnikov, L. V. Dobysheva

This work deals with the analysis of experimental data on the average magnetization of $Fe_{1-x}Me_x$ (Me=Sn,Si) disordered alloys, the average and local hyperfine fields (HFF) at the Fe nuclei. The effect of the metalloid concentration on the HFF is studied with the help of the results of first- principles calculations of ordered alloys. The disorder is tak

R. Coldea, D. A. Tennant, A. M. Tsvelik, Z. Tylczynski

The ground-state ordering and dynamics of the two-dimensional (2D) S=1/2 frustrated Heisenberg antiferromagnet Cs_2CuCl_4 is explored using neutron scattering in high magnetic fields. We find that the dynamic correlations show a highly dispersive continuum of excited states, characteristic of the RVB state, arising from pairs of S=1/2 spinons. Quantum renorm

S. Prunet, P. A. R. Ade, J. J. Bock, J. R. Bond

We describe here an iterative method for jointly estimating the noise power spectrum from a CMB experiment&#39;s time-ordered data, together with the maximum-likelihood map. We test the robustness of this method on simulated Boomerang datasets with realistic noise.

K. B. Kwitter, R. B. C. Henry

This paper summarizes a project designed to study abundances in a sample of planetary nebulae representing a broad range in progenitor mass and metallicity. We collect abundances of C, N, and O determined for the entire sample and compare them with theoretical predictions of planetary nebula abundances from a grid of intermediate-mass star models. We find ve

R. B. C. Henry, M. G. Edmunds, J. Koeppen

We employ analytical and numerical chemical evolution models to study observed trends in abundance ratios involving carbon, nitrogen, and oxygen. Several sets of published stellar yields for both intermediate-mass and massive stars are considered, and the most appropriate sets are selected through the use of analytical models. These yields are then used in t

A. W. Strong, I. V. Moskalenko

A new numerical model of particle propagation in the Galaxy has been developed, which allows the study of cosmic-ray and gamma-ray production and propagation in 2D or 3D, including a full reaction network. This is a further development of the code which has been used for studies of cosmic ray reacceleration, Galactic halo size, antiprotons and positrons in c

Ilian T. Iliev, Paul R. Shapiro

An analytical model is presented for the postcollapse equilibrium structure of virialized objects which condense out of a low-density cosmological background universe, either matter-dominated or flat with a cosmological constant. This generalizes the model we derived previously for an Einstein-de Sitter (EdS) universe. The model is based upon the assumption

Piotr T. Zycki

I review observational data on X-ray energy spectra and variability of Seyfert 1 and Narrow Line Seyfert 1 galaxies, and compare them to black hole binary (BHB) systems. There seems to be greater similarity of time averaged properties (i.e. energy spectra) than time variability between the supermassive and stellar-mass black hole accreting systems. Energy sp

J. U. Fynbo, P. Moller, B. Thomsen

In a ongoing programme aimed at studying galaxy counterparts of Damped Ly-alpha Absorbers (DLAs) we have obtained high resolution deep I-band imaging data of the field around the z_em = 0.457 BAL QSO Q2112+059. In the literature this QSO is listed to have a candidate DLA at z_abs = 0.2039 along the line of sight. After subtraction of the QSO Point Spread Fun

Gordon T. Richards, S. A. Laurent-Muehleisen, Robert H. Becker, Donald G. York

We present high resolution radio data at 3.5 and 20 cm from the VLA in the A configuration for 144 quasars with known CIV absorption line properties. Using these measurements, we compare and contrast a number of quasar orientation indicators. These quantities are used to study the velocity distribution of CIV absorption lines as a function of quasar orientat

Gordon T. Richards

Moderate resolution spectra have been recorded for a sample of radio-selected QSOs (z=2.5) discovered in the ``Faint Images of the Radio Sky at Twenty centimeters&#39;&#39; (FIRST) VLA survey. This work is motivated by the study of a heterogeneous set of QSO absorption line spectra that showed that as many as 36% of the absorbers normally thought to be inter

G. B. Lima Neto, V. Pislar, J. Bagchi

We report the observation of the Intra-Cluster Medium (ICM) of Abell 85 by the X-ray satellite BeppoSAX. We have both analysed the spectrum obtained in the central 8 arcmin circular region centred on the Very Steep Spectrum Radio Source (VSSRS) and the spectra from a number of sub-regions. Analysis of the spectra allowed us to independently obtain new estima

John S. Carr, Robert D. Mathieu, Joan R. Najita

We present the discovery of CO fundamental ro-vibrational emission from the classical T Tauri spectroscopic binary DQ Tau. The high-resolution infrared echelle spectra reveal emission lines from both the v=1 and v=2 vibrational levels with line widths of roughly 70 km/s. The average CO excitation temperature is approximately 1200 K. We model the spectra as a

A. N. Parmar, L. Sidoli, T. Oosterbroek, P. A. Charles

The nearby galaxy M33 was observed by the imaging X-ray instruments on-board BeppoSAX. Two observations at different phases of the 105.9 day intensity cycle of the luminous central source X-8 failed to reveal the expected modulation, suggesting that it is probably transitory. Similar behavior has been observed from several X-ray binary sources. This strength

T. Foglizzo

In the radial flow of gas into a black hole (i.e. Bondi accretion), the infall of any entropy or vorticity perturbation produces acoustic waves propagating outward. The dependence of this acoustic flux on the shape of the perturbation is investigated in detail. This is the key process in the mechanism of the entropic-acoustic instability proposed by Foglizzo

Alberto Noriega-Crespo

The Infrared Space Observatory (ISO) was an extremely successful european space mission that gave us an unparallel view of the Universe in the infrared, and provided us with hundreds of observations of star forming regions and bipolar outflows. Three of the instrument teams, in charge of the infrared camera (CAM) and the two spectrometers at short and long w

M. C. Maccarone, T. Mineo, A. Preite-Martinez

We have performed the first detailed spatially resolved spectroscopy of Cas A in the 1.6-10 keV energy range, using data taken with the MECS spectrometer on board the BeppoSAX Observatory. We performed a spatial deconvolution of the data and eventually generated a set of spectra, covering a region of about 3 arcmin radius around the centre of Cas A. The resu

Masayuki Akiyama

In this paper, results of optical identification of ASCA surveys are summarized. To understand luminous AGNs in the z<1 universe, the ASCA AGN sample is still better than samples of AGNs from deep Chandra or XMM-Newton surveys. Combining the identified sample of AGNs from ASCA Large Sky Survey and Medium Sensitivity Survey, the sample of hard X-ray selected

Michael Eracleous, Jules P. Halpern

Motivated by the X-ray properties of the galaxy NGC 3065, we have obtained new optical spectra which reveal that it has a low-ionization nuclear emission-line region (LINER) as well as broad Balmer emission lines, establishing it as an active galactic nucleus. We also examined an older spectrum from the CfA Redshift Survey which, lacking broad Balmer lines,

Nicholas A. Bond, Chris W. Churchill, Jane C. Charlton, Steven S. Vogt

The intervening z=0.7443 Mg II absorption system in the spectrum of MC 1331+170 shows an unusual series of line pairs, each with velocity separations of 30 km/s. These lines could be explained as the shells of expanding superbubbles residing in the outer regions of an edge-on spiral galaxy visible in the optical image of the MC 1331+170 field. The color and

Paul P. van der Werf, Kirsten Kraiberg Knudsen, Ivo Labb&#39;e, Marijn Franx

Can the submillimetre counts and background be produced by applying a locally derived extinction correction to the population of Lyman break galaxies? We investigate the submillimetre emission of two strongly lensed Lyman break galaxies (MS1512+36-cB58 and MS1358+62-G1) and find that the procedure that is used to predict the submillimetre emission of the Lym

Sumanta Tewari, Hae-Young Kee, Chetan Nayak, Sudip Chakravarty

We calculate the spin-spin and current-current correlation functions in states exhibiting d_{{x^2}-{y^2}}-density wave (DDW) order, d_{{x^2}-{y^2}} superconducting order (DSC), or both types of order. The spin-spin correlation functions in a state with both DDW and DSC order and in a state with DDW order alone, respectively, illuminate the resonant peak seen

Yun Wang, Peter M. Garnavich

Observations of high redshift supernovae imply an accelerating Universe which can only be explained by an unusual energy component such as vacuum energy or quintessence. To assess the ability of current and future supernova data to constrain the properties of the dark energy, we allow its density to have arbitrary time-dependence, $ρ_X(z)$. This leads to an

J. A. S. Lima, R. Silva, A. R. Plastino

The kinetic foundations of Tsallis&#39; nonextensive thermostatistics are investigated through Boltzmann&#39;s transport equation approach. Our analysis follows from a nonextensive generalization of the ``molecular chaos hypothesis&#34;. For $q>0$, the $q$-transport equation satisfies an $H$-theorem based on Tsallis entropy. It is also proved that the collis

Jonathan L. Rosner

We discuss the history of CP violation and its manifestations in kaon physics, its explanation in terms of phases of the Cabibbo-Kobayashi-Maskawa matrix describing charge-changing weak quark transitions, predictions for experiments involving $B$ mesons, and the light it can shed on physics beyond the Standard Model.

Danny Calegari

We show that for a taut foliation F with one-sided branching of an atoroidal 3-manifold M, one can construct a pair of genuine laminations with solid torus complementary regions which bind every leaf of F in a geodesic lamination. These laminations come from a universal circle, a refinement of the universal circles proposed by Thurston, which maps monotonely