March 1998 arXiv papers — page 5

Erik Koch

The formation of supershells observed in large metal clusters can be qualitatively understood from a periodic-orbit-expansion for a spherical cavity. To describe the changes in the supershell structure for different materials, one has, however, to go beyond that simple model. We show how periodic-orbit-expansions for realistic cluster potentials can be deriv

Yi-Cheng Zhang

This is an essay solicited by Europhysics News, published in its March/April 1998 issue with slight modifications. We outline some highlights of the econophysics models, especially the so-called Minority model of competition and evolution. Even without the usual math, this essay offers an analytical solution to the Minority model, revealing some key features

Ghyslain Boisvert, Normand Mousseau, Laurent J. Lewis

The rate of diffusion of a Cu adatom on the Cu(100) surface is calculated using thermodynamic integration within the transition state theory. The results are found to be in excellent agreement with the essentially exact values from molecular-dynamics simulations. The activation energy and related entropy are shown to be effectively independent of temperature

Morten Holm Pedersen, Markus Buttiker

The scattering matrix approach to phase-coherent transport is generalized to nonlinear ac-transport. In photon-assisted electron transport it is often only the dc-component of the current that is of experimental interest. But ac-currents at all frequencies exist independently of whether they are measured or not. We present a theory of photon-assisted electro

Alberto Parola, Luca Salasnich, Luciano Reatto

We investigate the form and stability of a cloud of atoms confined in a harmonic trap when the scattering length is negative. We find that, besides the known low density metastable solution, a new branch of Bose condensate appears at higher density when non locality effects in the attractive part are taken into account. The transition between the two classes

Alexandra Ilinskaia, Kirill Ilinski

We present a new representation of spin operators in terms of bosonic creation-annihilation operators. This representation allows us to formulate a new field-theoretical description of spin systems which is free of any constraints. The corresponding functional integral representations for thermodynamic quantities are given and the application to investigatio

J. M. R. Parrondo, J. M. Blanco, F. J. Cao, R. Brito

The efficiency of different types of Brownian motors is calculated analytically and numerically. We find that motors based on flashing ratchets present a low efficiency and an unavoidable entropy production. On the other hand, a certain class of motors based on adiabatically changing potentials, named reversible ratchets, exhibit a higher efficiency and the

P. K. Datta, A. M. Jayannavar

Dynamics of a particle in a perfect chain with one nonlinear impurity and in a perfect nonlinear chain under the action of dc field is studied numerically. The nonlinearity appears due to the coupling of the electronic motion to optical oscillators which are treated in adiabatic approximation. We study for both the low and high values of field strength. Thre

A. I. Belousov, Yu. E. Lozovik

Path Integral Quantum Monte Carlo simulation is used to study thermodynamic properties and a phase diagram of 2D quantum Josephson array, described by 2+1 XY model. The helicity and vorticity moduli, correlation function of phases and other characteristics of the system as functions of quantum parameter $q$ and temperature $T$ are studied ($q=2e/\sqrt{JC_0}$

Prof. Dr. Peter Fulde

A number of methods are discussed which may serve for a treatment of electron correlations in solids. When the electron correlations are relatively weak like in semiconductors or a number of ionic crystals one may start from a self-consistent field calculation and include correlations by quantum chemical methods. An incremental computational scheme enables u

Janne Ruostekoski, Dan F. Walls

We study the dynamics of a Bose-Einstein condensate in a double-well potential in the two-mode approximation. The dissipation of energy from the condensate is described by the coupling to a thermal reservoir of non-condensate modes. As a consequence of the coupling the self-locked population imbalance in the macroscopic quantum self-trapping decays away. We

Y. Suzumura, M. Tsuchiizu, G. Gruner

The effect of umklapp scattering on interchain hopping has been investigated for two-coupled chains of interacting electrons with half-filled band. By analyzing in terms of renormalization group method, we have found that interchain hopping is renormalized to zero and is confined when a gap induced by umklapp scattering becomes larger than a critical value.

Simon Villain-Guillot, Roland R. Netz, David Andelman, Michael Schick

Interfaces between lamellar and disordered phases, and grain boundaries within lamellar phases, are investigated employing a simple Landau free energy functional. The former are examined using analytic, approximate methods in the weak segregation limit, leading to density profiles which can extend over many wavelengths of the lamellar phase. The latter are s

Maria Morandi Cecchi, Luca Salasnich

The hydrocyclone is a tool used in different fields but mostly in mining industries to separate minerals. The minerals are put in a liquid or in a stable suspension of a chosen density which must be less than the density of the heavier minerals and greater than that of the lighter minerals. Because of the effect of the walls the flow in a hydrocyclone is the

Sudhir R. Jain

For ergodic adiabatic quantum systems, we study the evolution of energy distribution as the system evolves in time. Starting from the von Neumann equation for the density operator, we obtain the quantum analogue of the Smoluchowski equation on coarse-graining over the energy spectrum. This result brings out the precise notion of quantum diffusion.

P. A. Scowen, J. J. Hester, R. Sankrit, J. S. Gallagher

Using the Hubble Space Telescope and WFPC2 we have imaged the central 20pc of the giant H II region 30 Doradus nebula in three different emission lines. The images allow us to study the nebula with a physical resolution that is within a factor of two of that typical of ground based observations of Galactic H II regions. Most of the emission within 30 Dor is

Y. -Z. Qian, P. Vogel, G. J. Wasserburg

We discuss how detection of gamma-ray emission from the decay of r-process nuclei can improve our understanding of r-process nucleosynthesis. We find that a gamma-ray detector with a sensitivity of 10**(-7)/cm**2/s at 100-700 keV may detect the emission from the decay of Sb125, Cs137, Ce144, Eu155, and Os194 produced in a future Galactic supernova. In additi

M. Ostrowski

A mechanism of ultra-high energy cosmic ray acceleration in extragalactic radio sources, at the interface between the relativistic jet and the surrounding medium, is discussed as a supplement to the shock acceleration in `hot spots'. Due to crossing the tangential discontinuity of the velocity the particle can gain an amount of energy comparable to the e

Paolo Padovani, Eric Perlman, Paolo Giommi, Rita Sambruna

We have undertaken a survey for blazars by correlating the ROSAT WGACAT database with publicly available radio catalogs, restricting our candidate list to serendipitous flat-spectrum sources (alpha_r <= 0.7). We discuss here our survey methods, identification procedure and first results. Our survey is found to be ~ 95% efficient at finding blazars, a figure

Brian D. Fields, Keith A. Olive

We discuss the chemical evolution of dwarf irregular and blue compact galaxies in light of recent data, new stellar yields and chemical evolution models. We examine the abundance data for evidence of HII region self-enrichment effects, which would lead to correlations in the scatter of helium, nitrogen, and oxygen abundances around their mean trends. The obs

F. Raluy, P. Planesas, L. Colina

We have searched for molecular gas towards the nucleus of four galaxies known to harbor a water vapor megamaser. CO(1-->0) emission of NGC 2639 and NGC 5506 was strong enough to allow us to map their inner regions. Weak emission from Mrk 1210 was detected and Mrk 1 was not detected at all. We report the tentative detection of the CO(2-->1) line in NGC 5506.

A. W. Blain

Samples of high-redshift galaxies are easy to select in the millimetre/submillimetre (mm/submm) waveband using sensitive telescopes, because their flux density-redshift relations are expected to be flat, and so the selection function is almost redshift-independent at redshifts greater than 0.5. Source counts are expected to be very steep in the mm/submm wave

R. M. Sharples, S. E. Zepf, T. J. Bridges, D. A. Hanes

Optical multi-slit spectra have been obtained for 47 globular clusters surrounding the brightest Virgo elliptical NGC 4472 (M49). Including data from the literature, we analyze velocities for a total sample of 57 clusters and present the first tentative evidence for kinematic differences between the red and blue cluster populations which make up the bimodal

L. Perivolaropoulos

Using analytical methods and Monte Carlo simulations, we analyze new statistics designed to detect isolated step-like discontinuities which are coherent over large areas of Cosmic Microwave Background (CMB) pixel maps. Such coherent temperature discontinuities are predicted by the Kaiser-Stebbins effect to form due to long cosmic strings present in our prese

G. Matt, R. Barcaroli, T. Belloni, K. Beuermann

We report on the analysis of the ASCA and BeppoSAX X-ray observations of the polar system BL Hyi. Emission from both poles is apparent in both observations; the emission from the second pole varies from cycle to cycle, indicating non-stationary accretion there. The temperature of the post-shock region is estimated to be about 10 keV. Inclusion of both comple

Tariq Shahbaz

We describe a method of determining the system parameters in non-eclipsing interacting binaries. We find that the extent to which an observer sees the shape of the Roche-lobe of the secondary star governs the amount of distortion of the absorption line profiles. The width and degree of asymmetry of the phase-resolved absorption line profiles show a character

A. C. Fabian, X. Barcons, O. Almaini, K. Iwasawa

We propose a model for the source of the X-ray background (XRB) in which low luminosity active nuclei (L<10^43 erg/s) are obscured by nuclear starbursts within the inner 100pc. The obscuring material covers most of the sky as seen from the central source, rather than being distributed in a toroidal structure, and hardens the averaged X-ray spectrum by photoe

Kyoko Matsushita, Kazuo Makishima, Yasushi Ikebe, Etsuko Rokutanda

ASCA observations of NGC 4636 and a southern region have revealed extended X-ray emission to a radius of about 300 kpc from the galaxy. The symmetric nature of the observed surface brightness around NGC 4636 indicates its association to this galaxy rather than to the Virgo cluster. Model independent estimation of the gravitational mass profile shows a flatte

M. E. Putman, M. Bureau, J. R. Mould, L. Staveley-Smith

The Fornax cluster galaxy FCC 35 shows an unusual multiply-peaked integrated HI profile (Bureau, Mould & Staveley-Smith 1996). We have now observed FCC 35 with the Australia Telescope Compact Array (ATCA) and have found a compact HI source with M_{HI} = 2.2 x 10^{8} M_{sun}, and a spatially overlapping complex of HI gas with the same mass. By combining optic

M. H. Hettler, A. N. Tahvildar-Zadeh, M. Jarrell, T. Pruschke

We introduce an extension of the dynamical mean field approximation (DMFA) which retains the causal properties and generality of the DMFA, but allows for systematic inclusion of non-local corrections. Our technique maps the problem to a self-consistently embedded cluster. The DMFA (exact result) is recovered as the cluster size goes to one (infinity). As a d

Changhyun Ahn, Kyungho Oh, Radu Tatar

We use the M theory approach in the presence of an orientifold O6 plane to understand some aspects of the moduli space of vacua for N=1 supersymmetric $SO(N_c)/Sp(N_c)$ gauge theories in four dimensions. By exploiting some general properties of the O6 orientifold, we reproduce some results obtained previously with an orientifold O4 plane when the flavor grou

K. Barron, C. Dong, G. Mason

Let V be a vertex operator algebra, and for k a positive integer, let g be a k-cycle permutation of the vertex operator algebra V^{\otimes k}. We prove that the categories of weak, weak admissible and ordinary g-twisted modules for the tensor product vertex operator algebra V^{\otimes k} are isomorphic to the categories of weak, weak admissible and ordinary

Friedemann Brandt, Joaquim Gomis, Joan Simón

We show that the symmetries of effective D-string actions in constant dilaton backgrounds are directly related to homothetic motions of the background metric. In presence of such motions, there are infinitely many nonlinearly realized rigid symmetries forming a loop (or loop like) algebra. Near horizon (AdS) D3 and D1+D5 backgrounds are discussed in detail a

Giacomo M. D&#39;Ariano, Michael Vasilyev, Prem Kumar

A self-homodyne detection scheme is proposed to perform two-mode tomography on a twin-beam state at the output of a nondegenerate optical parametric amplifier. This scheme has been devised to improve the matching between the local oscillator and the signal modes, which is the main limitation to the overall quantum efficiency in conventional homodyning. The f

Vipul Periwal, Øyvind Tafjord

D-brane backgrounds are specified in closed string theories by holes with appropriate mixed Dirichlet and Neumann boundary conditions on the string worldsheet. As presently stated, the prescription defining D-brane backgrounds is such that the Einstein equation is not equivalent to the condition for scale invariance on the string worldsheet. A modified D-bra

J. Ibanez, I. Olasagasti

The asymptotic behaviour of a family of inhomogeneous scalar field cosmologies with exponential potential is studied. By introducing new variables we can perform an almost complete analysis of the evolution of these cosmologies. Unlike the homogeneous case (Bianchi type solutions), when k^2<2 the models do not isotropize due to the presence of the inhomogene

G. Wilk, Z. Wlodarczyk

The inelasticity of hadron-carbon nucleus collisions in the energy region exceeding 100 TeV is estimated from the carbon-emulsion chamber data at Pamirs to be $<K_C> = 0.65\pm 0.08$. When combined with the recently presented data on hadron-lead nucleus collisions taken at the same energy range it results in the $K\sim A^{0.086}$ mass number dependence of ine

Gen Yoneda, Hisa-aki Shinkai

We present a first-order symmetric hyperbolic system in the Ashtekar formulation of general relativity for vacuum spacetime. We add terms from constraint equations to the evolution equations with appropriate combinations, which is the same technique used by Iriondo, Leguizamón and Reula [Phys. Rev. Lett. 79, 4732 (1997)]. However our system is different from

N. L. Chuprikov

On the basis of the transfer matrix technique an analytical method to investigate the stationary states, for an electron in one-dimensional periodic structures in an external electrical field, displaying the symmetry of the problem is developed. These solutions are shown to be current-carrying. It is also shown that the electron spectrum for infinite structu

Ashoke Sen

Many string theories contain states which are not BPS, but are stable due to charge conservation. In many cases the description of these states in the strong coupling limit remains unknown despite the existence of a weakly coupled dual theory. However, we show that in some cases duality symmetries in string theory do enable us to identify these states in the

Robert E. Shirey, Hale V. Bradt, Alan M. Levine, Edward H. Morgan

We present Rossi X-ray Timing Explorer (RXTE) All-Sky Monitor observations of the X-ray binary Circinus X-1 which illustrate the variety of intensity profiles associated with the 16.55 d flaring cycle of the source. We also present eight observations of Cir X-1 made with the RXTE Proportional Counter Array over the course of a cycle wherein the average inten

Yuri Ozhigov

Let $f$ denote length preserving function on words. A classical algorithm can be considered as $T$ iterated applications of black box representing $f$, beginning with input word $x$ of length $n$. It is proved that if $T=O(2^{n/(7+e)}), e >0$, and $f$ is chosen randomly then with probability 1 every quantum computer requires not less than $T$ evaluations of

J. R. Mureika

Track and field world records have risen and fallen throughout the history of the sport. A recent rash of record-breaking performances has prompted the question: &#34;How good can we get?&#34;. This article offers a review of several attempts to answer this question, based on mathematical modeling of key physiological processes. The predictions are compared

U. D. J. Gieseler, J. G. Kirk

Mahan [J. Math. Phys. 36, 6758 (1995)] has calculated the transmission coefficient and angular distribution of particles which enter a thick slab at normal incidence and which diffuse in the slab with linear anisotropic, non-absorbing, scattering. Using orthogonality relations derived by McCormick & Kuscer [J. Math. Phys. 6, 1939 (1965); 7, 2036 (1966)] for

N. A. Zabotin, A. G. Bronin, G. A. Zhbankov

The problem of radio wave reflection from an optically thick plane monotonous layer of magnetized plasma is considered at present work. The plasma electron density irregularities are described by spatial spectrum of an arbitrary form. The small-angle scattering approximation in the invariant ray coordinates is suggested for analytical investigation of the ra

Bruno Poizat, Frank Olaf Wagner

If $G$ is an omega-stable group with a normal definable subgroup $H$, then the Sylow-$2$-subgroups of $G/H$ are the images of the Sylow-$2$-subgroups of $G$.

A. Libgober

We show how Chern classes of a Calabi Yau hypersurface in a toric Fano manifold can be expressed in terms of the holomorphic at a maximal degeneracy point period of its mirror. We also consider the relation between Chern classes and the periods of mirrors for complete intersections in Grassmanian Gr(2,5).

Laszlo Lempert

We prove that the equation d-bar u = f can be solved on a ball B(R) of radius R in the Banach space l^1 if f is a closed Lipschitz continuous (0,1) form on B(R). We also present examples of closed (0,1) forms f of various regularities on the spaces l^p that are not exact. In particular, in the first result above, it is not enough to assume that f is merely c

Alexander Verbovetsky

This paper is devoted to the horizontal (``characteristic&#39;&#39;) cohomology of systems of differential equations. Recent results on computing the horizontal cohomology via the compatibility complex are generalized. New results on the Vinogradov C-spectral sequence and the Krasil&#39;shchik C-cohomology are obtained. As an application of general theory, t

Christian Blanchet

We construct modular categories from Hecke algebras at roots of unity. For a special choice of the framing parameter, we recover the Reshetikhin-Turaev invariants of closed 3-manifolds constructed from the quantum groups U_q sl(N) by Reshetikhin-Turaev and Turaev-Wenzl, and from skein theory by Yokota. We then discuss the choice of the framing parameter. Thi

Yuval Z. Flicker, Claus Scheiderer, R. Sujatha

A theorem of Grothendieck asserts that over a perfect field k of cohomological dimension one, all non-abelian H^2-cohomology sets of algebraic groups are trivial. The purpose of this paper is to establish a formally real generalization of this theorem. The generalization -- to the context of perfect fields of virtual cohomological dimension one -- takes the

L. Barbieri Viale, V. Srinivas

We define, in a purely algebraic way, 1-motives $Alb^{+}(X)$, $Alb^{-}(X)$, $Pic^{+}(X)$ and $Pic^{-}(X)$ associated with any algebraic scheme $X$ over an algebraically closed field of characteristic zero. For $X$ over $\C$ of dimension $n$ the Hodge realizations are, respectively, $H^{2n-1}(X)(n)$, $H_{1}(X)$, $H^{1}(X)(1)$ and $H_{2n-1}(X)(1-n)$.

Robin Hartshorne, Mireille Martin-Deschamps, Daniel Perrin

Let $A$ be a noetherian ring and $R_A$ be the graded ring $A[X,Y,Z,T]$. In this article we introduce the notion of a triad, which is a generalization to families of curves in ${\bf P}^3_A$ of the notion of Rao module. A triad is a complex of graded $R_A$-modules $(L_1 \to L_0 \to L_{-1})$ with certain finiteness hypotheses on its cohomology modules. A pseudo

Danny Calegari

We investigate the combinatorial analogues, in the context of normal surfaces, of taut and transversely measured (codimension 1) foliations of 3-manifolds. We establish that the existence of certain combinatorial structures, a priori weaker than the existence of the corresponding foliation, is sufficient to guarantee that the manifold in question satisfies c

Victor V. Batyrev, Ionut Ciocan-Fontanine, Bumsig Kim, Duco van Straten

In this paper we propose and discuss a mirror construction for complete intersections in partial flag manifolds $F(n_1, ..., n_l, n)$. This construction includes our previous mirror construction for complete intersection in Grassmannians and the mirror construction of Givental for complete flag manifolds. The key idea of our construction is a degeneration of

Paolo Lipari, Maurizio Lusignoli

The simplest explanation for the atmospheric neutrino anomaly is the transition of muon neutrinos and antineutrinos into states of different flavor. Data from the reactor experiment Chooz, and the measurement of the energy and angle distribution of electron--like events in Super--Kamiokande put strong constraints on $ν_μ$--$ν_e$ mixing, but the transitions $

Y. Matiounine, J. Smith, W. L. van Neerven

We present the two-loop corrected operator matrix elements contributing to the scale evolution of the longitudinal spin structure function $g_1(x,Q^2)$ calculated up to finite terms which survive in the limit $ε= N - 4 \to 0$. These terms are needed to renormalize the local operators up to third order in the strong coupling constant $α_s$. Further the expres

Borut Bajc, Antonio Riotto, Goran Senjanovic

Large charge density, unlike high temperature, may lead to nonrestoration of global and gauge symmetries. Supersymmetric GUTs with the appealing scenario of unification scale being generated dynamically naturally contain global continuous $R$ symmetries. We point out that the presence of a large $R$ charge in the early Universe can lead to GUT symmetry nonre

F. W. Bopp, R. Engel, J. Ranft

A model for the production of large rapidity gaps being implemented in the Monte Carlo event generator PHOJET is discussed. In this model, high-mass diffraction dissociation exhibits properties similar to hadron production in non-diffractive hadronic collisions at high energies. Hard diffraction is described using leading-order QCD matrix elements together w

L. Motyka, K. Zalewski

A model based on a nonrelativistic potential supplemented by spin dependent terms of the Breit-Fermi type is described. This model reproduces the known masses of the $\bar{b}b$ quarkonia within 1MeV and the known masses of the $\bar{c}c$ quarkonia within 5MeV. Many predictions are made, some of them, e.g. for the fine splittings of the high $L$ states of the

M. G. Ryskin, Yu. M. Shabelski, A. G. Shuvaev

We calculate $p_T$-dependences of diffractive vector meson photo- and electroproduction in electron-proton collisions with and without proton dissociation at small momenta transfers. The calculated slopes are in good agreement with the data.

S. S. Gershtein, V. V. Kiselev, A. K. Likhoded, A. V. Tkabladze

Theoretical predictions on the $B_c$ meson properties are reviewed.

V. K. Petrov

In the limit of $ξ\simeq a_σ/a_τ\to \infty $ the gluodynamics without the magnetic part of action ($S_M\sim 1/ξ$) is considered as a self-contained model. The model is studied analytically in the continuum limit on an extremely large lattice ($N_τ\to \infty $). Scaling conditions for critical temperature and string tension are considered. The model shows tri

W. Bietenholz, H. Dilger

We discuss the behavior of free perfect staggered fermions and truncated versions thereof. The study includes flavor non-degenerate masses. We suggest a new blocking scheme, which provides excellent locality of the perfect lattice action. A truncation procedure adequate for the structure of staggered fermions is applied. We consider spectral and thermodynami

Sergio Petrera

This talk reports a subset of the topics discussed at TAUP97. The topics are: nucleon decay, supermassive monopoles, Neutrino Astrophysics and Cosmic Ray Physics.

A. Kirk

The non-Abelian nature of QCD suggests that particles that have a gluon constituent, such as glueballs or hybrids, should exist. Experiments WA76, WA91 and WA102 have performed a dedicated search for these states in central production using the CERN Omega Spectrometer. Several non-qqbar candidates have been observed. This paper presents a study of central me

Luis P. Chimento, Diego Pavon

The evolution of a class of inhomogeneous spherically symmetric universe models possessing a varying cosmological term and a material fluid, with an adiabatic index either constant or not, is studied.

R. O. Vallejos, C. Anteneodo

We investigate the thermodynamics of model systems exhibiting two-scale fractal spectra. In particular, we present both analytical and numerical studies on the temperature dependence of the vibrational and electronic specific heats. For phonons, and for bosons in general, we show that the average specific heat can be associated to the average (power law) den

Redouane Fakir

It is by now established that, remarkably, the addition of noise to a nonlinear system may sometimes facilitate, rather than hamper the detection of weak signals. This phenomenon, usually referred to as stochastic resonance, was originally associated with strictly periodic signals, but it was eventually shown to occur for stationary aperiodic signals as well

S. Kamal, Ruixing Liang, A. Hosseini, D. A. Bonn

We have succeeded in growing very high purity (99.995%) YBa_2Cu_3O_{7-delta} crystals in BaZrO_3 crucibles and have measured Delta-lambda(T) and R_s(T) at 1 GHz in crystals with various oxygen treatments. For an oxygen vacancy level of delta=0.007, Delta-lambda and R_s essentially reproduce our previous results and show no sign of the existence of the two or

Alexander E. Lobkovsky, J. S. Langer

We study two closely related, nonlinear models of a viscoplastic solid. These models capture essential features of plasticity over a wide range of strain rates and applied stresses. They exhibit inelastic strain relaxation and steady flow above a well defined yield stress. In this paper, we describe a first step in exploring the implications of these models

Xiaoqun Wang

Using the Density Matrix Renormalization Group method, we determined the phase diagram of a frustrated antiferromagnetic spin-$\frac 1 2$ ladder at zero temperature. Two spin-gapped phases, the Haldane phase and the singlet phase, are identified. A phase transition between the two phases occurs at any non-zero value of frustration coupling $J_{\times}$. On t

M. R. Jarvis, R. Perez, F. M. van Bouwelen, M. C. Payne

Mechanically induced degradation of diamond, as occurs during polishing, is studied using total--energy pseudopotential calculations. The strong asymmetry in the rate of polishing between different directions on the diamond (110) surface is explained in terms of an atomistic mechanism for nano--groove formation. The post--polishing surface morphology and the

Marek Cieplak, Achille Giacometti, Amos Maritan, Andrea Rinaldo

Two distinct models for self-similar and self-affine river basins are numerically investigated. They yield fractal aggregation patterns following non-trivial power laws in experimentally relevant distributions. Previous numerical estimates on the critical exponents, when existing, are confirmed and superseded. A physical motivation for both models in the pre

C. Hartwigsen, S. Goedecker, J. Hutter

We generalize the concept of separable dual-space Gaussian pseudopotentials to the relativistic case. This allows us to construct this type of pseudopotential for the whole periodic table and we present a complete table of pseudopotential parameters for all the elements from H to Rn. The relativistic version of this pseudopotential retains all the advantages

Akinori Nishino, Hideaki Ujino, Miki Wadati

Using a similarity transformation that maps the Calogero model into $N$ decoupled quantum harmonic oscillators, we construct a set of mutually commuting conserved operators of the model and their simultaneous eigenfunctions. The simultaneous eigenfunction is a deformation of the symmetrized number state (bosonic state) and forms an orthogonal basis of the Hi

Hideaki Ujino, Akinori Nishino, Miki Wadati

We demonstrate an algebraic construction of all the simultaneous eigenfunctions of the conserved operators for distinguishable particles governed by the Calogero Hamiltonian. Our construction is completely parallel to the construction of the Fock space for decoupled quantum harmonic oscillators. The simultaneous eigenfunction does not coincide with the non-s

Sitabhra Sinha, Bikas K. Chakrabarti

The phenomenon of Stochastic Resonance (SR) is observed in a completely deterministic setting - with thermal noise being replaced by one-dimensional chaos. The piecewise linear map investigated in the paper shows a transition from symmetry-broken to symmetric chaos on increasing a system parameter. In the latter state, the chaotic trajectory switches between

G. Chartas, D. Chuss, W. Forman, C. Jones

Analysis of several recent ROSAT HRI observations of the gravitationally lensed system Q0957+561 has led to the detection at the 3sigma level of the cluster lens containing the primary galaxy G1. The total mass was estimated by applying the equation of hydrostatic equilibrium to the detected hot intracluster gas for a range of cluster core radii, cluster siz

P. Madau, M. Della Valle, N. Panagia

Ongoing searches for supernovae (SNe) at cosmological distances have recently started to provide a link between SN Ia statistics and galaxy evolution. We use recent estimates of the global history of star formation to compute the theoretical Type Ia and Type II SN rates as a function of cosmic time from the present epoch to high redshifts. We show that accur

Amancio C. S. Friaca, Roberto J. Terlevich

We present the results of a numerical code that combines multi-zone chemical evolution with 1-D hydrodynamics to follow in detail the evolution and radial behaviour of gas and stars during the formation of elliptical galaxies. We use the model to explore the links between the evolution and formation of elliptical galaxies and QSO activity. The knowledge of t

B. Scott Gaudi, Richard M. Naber, Penny D. Sackett

Microlensing is increasingly gaining recognition as a powerful method for the detection and characterization of extra-solar planetary systems. Naively, one might expect that the probability of detecting the influence of more than one planet on any single microlensing light curve would be small. Recently, however, Griest & Safizadeh (1998) have shown that, fo

Adi Nusser, Ravi Sheth

We develop a model for the growth of dark matter halos and use it to study their evolved density profiles. In this model, halos are spherical and form by quiescent accretion of matter in clumps, called satellites. The halo mass as a function of redshift is given by the mass of the most massive progenitor, and is determined from Monte-Carlo realizations of th

M. J. Hardcastle

I present 1.5- and 8.4-GHz observations with all configurations of the NRAO VLA of the wide-angle tail source 3C130. The source has a pair of relatively symmetrical, well-collimated inner jets, one of which terminates in a compact hot spot. Archival ROSAT PSPC data confirm that 3C130&#39;s environment is a luminous cluster with little sign of sub-structure i

A. Refregier, S. T. Brown

The measurement of shape parameters of sources in astronomical images is usually performed by assuming that the underlying noise is uncorrelated. Spatial noise correlation is however present in practice due to various observational effects and can affect source shape parameters. This effect is particularly important for measurements of weak gravitational len

Neta A. Bahcall, Xiaohui Fan

The existence of the three most massive clusters of galaxies observed so far at z>0.5 is used to constrain the mass density parameter of the universe, Omega, and the amplitude of mass fluctuations, sigma_8. We find Omega=0.2 (+0.3,-0.1), and sigma_8=1.2 (+0.5,-0.4) (95 %). We show that the existence of even the single most distant cluster at z=0.83, MS1054-0

T. J. Davidge

Images recorded through broad (J, H, K), and narrow (CO, and 2.2micron continuum) band filters are used to investigate the photometric properties of bright (K < 13.5) stars in a 6 x 6 arcmin field centered on the SgrA complex. The giant branch ridgelines in the (K, J-K) and (K, H-K) color-magnitude diagrams are well matched by the Baade&#39;s Window (BW) M g

Dongsu Ryu, Hyesung Kang, Peter L. Biermann

We consider the possibility that cosmic magnetic field, instead of being uniformly distributed, is strongly correlated with the large scale structure of the universe. Then, the observed rotational measure of extra-galactic radio sources would be caused mostly by the clumpy magnetic field in cosmological filaments/sheets rather than by a uniform magnetic fiel

Simon Prunet, Shiv K. Sethi, Francois R. Bouchet

We present a method of subtracting the foreground contamination for the measurement of CMB polarization. We calculate the resultant errors on CMB polarization and temperature-polarization cross correlation power spectra for the high frequency instrument (HFI) aboard Planck Surveyor, and estimate the corresponding errors on cosmological parameters.

A. C. Fabian, J. C. Lee, W. N. Brandt, K. Iwasawa

We report on two observations of the Seyfert galaxy IRAS18325-5926 made in 1997 December and 1998 February with the Rossi X-ray Timing Explorer (RXTE). We find evidence for periodicities in the resulting X-ray lightcurves which are shorter than the 58~ks period found from data of the source taken in 1997 March with the imaging satellite ASCA. It is therefore

B. M. Gaensler, B. W. Stappers, D. A. Frail, S. Johnston

We report on Australia Telescope Compact Array observations of the ~10^5 yr old pulsar PSR B0906-49. In an image containing only off-pulse emission, we find a weak, slightly extended source coincident with the pulsar&#39;s position, which we argue is best interpreted as a pulsar wind nebula (PWN). A trail of emission extending behind the pulsar aligns with t

Edi Halyo

We obtain three and four dimensional conformal field theories with less than maximal supersymmetry by using their supergravity duals. These supergravity theories are type II on $AdS_5 \times CP^2$, IIA on $AdS_4 \times CP^3$, IIB on $AdS_5 \times S^5/Z_k$ and D=11 supergravity on $AdS_4 \times S^7/Z_k$. They are obtained from the spherically compactified ten

Koushik Ray

We study issues pertaining to the Ricci-flatness of metrics on orbifolds resolved by D-branes. We find a Kähler metric on the three-dimensional orbifold $\C^3/\Z_3$, resolved by D-branes, following an approach due to Guillemin. This metric is not Ricci-flat for any finite value of the blow-up parameter. Conditions for the envisaged Ricci-flat metric for fini

V. S. Berezinsky, P. Blasi, A. Vilenkin

We argue that due to various restrictions cosmic strings and monopole-string networks are not likely to produce the observed flux of ultra-high energy cosmic rays (UHECR). Among the topological defects studied so far, the most promising UHECR sources are necklaces and monopolonia. Other viable sources which are similar to topological defects are relic superh

Jose A. Freire, Daniel P. Arovas

We examine the Gross-Pitaevskii (GP) model for Bose-Einstein condensates in parabolic traps with attractive interactions. The decay of metastable condensates is investigated by applying the instanton formalism to the GP field theory. Employing various dynamical trial states, we derive within a coherent state path integral approach a collective coordinate des

A. Ali, G. Hiller

We compute the leading order (in $α_s$) perturbative QCD and power ($1/m_b^2)$ corrections to the hadronic invariant mass and hadron energy spectra in the decay $B \to X_s \ell^+ \ell^-$ in standard model. This is done both by using the heavy quark expansion technique (HQET) and a perturbative-QCD improved Fermi motion (FM) model which takes into account $B$

Jaume Garriga, Takahiro Tanaka, Alexander Vilenkin

In the context of open inflation, we calculate the probability distribution for the density parameter $Ω$. A large class of two field models of open inflation do not lead to infinite open universes, but to an ensemble of inflating islands of finite size, or ``quasi-open&#39;&#39; universes, where the density parameter takes a range of values. Assuming we are

A. Bartl, E. Christova, T. Gajdosik, W. Majerotto

The energy spectra of the b and bbar quarks in e+e- -> t tbar with t -> b W (tbar -> bbar W) are calculated assuming CP violation in the production process. Expressions for the corresponding CP violating asymmetries and optimal observables that determine the imaginary parts of the electric and weak dipole moment form factors of the top are derived. It is sho

I. Bars, C. Deliduman, O. Andreev

We construct a duality between several simple physical systems by showing that they are different aspects of the same quantum theory. Examples include the free relativistic massless particle and the hydrogen atom in any number of dimensions. The key is the gauging of the Sp(2) duality symmetry that treats position and momentum (x,p) as a doublet in phase spa

A. Armoni, A. Brandhuber

We use type IIB brane configurations which were recently suggested by Hanany and Zaffaroni to study four dimensional N=1 supersymmetric gauge theories. We calculate the one loop beta function and realize Seiberg&#39;s duality using a particular configuration. We also comment on the anomaly cancelation condition in the case of chiral theories and the beta fun