July 2002 arXiv papers — page 16

Machiko Hatsuda, Kiyoshi Kamimura, Makoto Sakaguchi

We present a gauge invariant action for a superstring in the plane wave background with Ramond-Ramond (RR) five-form flux. The Wess-Zumino term is given explicitly in a bilinear form of the left invariant currents by introducing a fermionic center to define the nondegenerate group metric. The reparametrization invariance generators, whose combinations are co

Mei Xiaochun

Based on the original meanings of C, P, T transformations, a more perfect and rational scheme is advanced. According to new scheme, the propagation function of Femion would change a negative sign under C, T transformations, while that of boson does not. When the C, P, T transformations of transition probabilities are calculated, the results are similar to th

Armen M. Gulian, Kent S. Wood

We discuss possibilities of utilizing superconductors with Cooper condensates in triplet pairing states (where the spin of condensate pairs is S=1) for practical realization of quantum computers. Superconductors with triplet pairing condensates have features that are unique and cannot be found in the usual (singlet pairing, S=0) superconductors. The symmetry

Pascal Szriftgiser, Jean Ringot, Dominique Delande, Jean Claude Garreau

We experimentally show that the response of a quantum-chaotic system can display resonance lines sharper than the inverse of the excitation duration. This allows us to discriminate two neighboring frequencies with a resolution nearly 40 times better than the limit set by the Fourier inequality. Furthermore, numerical studies indicate that there is no limit,

Stefan Keppeler

We derive semiclassical quantization conditions for systems with spin. To this end one has to define the notion of integrability for the corresponding classical system which is given by a combination of the translational motion and classical spin precession. We determine the geometry of the invariant manifolds of this product dynamics which support semiclass

Stefano Mancini, David Vitali, Paolo Tombesi

We study the possibility to teleport an unkown quantum state onto the vibrational degree of freedom of a movable mirror. The quantum channel between the two parties is established by exploiting radiation pressure effects.

Fam Le Kien, K. Hakuta, A. V. Sokolov

We present a general analysis for the interaction of a probe laser radiation with a coherently prepared molecular Raman medium. We describe a general formalism which includes dispersive effects, such as group velocity and group velocity dispersion (GVD). When dispersion is negligible, the analysis is especially simple and insightful. We show that molecular o

Samuel L. Braunstein, Arun K. Pati

We investigate the issue of speed-up and the necessity of entanglement in Grover's quantum search algorithm. We find that in a pure state implementation of Grover's algorithm entanglement is present even though the initial and target states are product states. In pseudo-pure state implementations, the separability of the states involved defines an en

Lei Bao, Edward F. Redish

In this paper we present a method of modeling and analysis that permits the extraction and quantitative display of detailed information about the effects of instruction on a class's knowledge. The method relies on a congitive model that represents student thinking in terms of mental models. Students frequently fail to recognize relevant conditions that l

Juan A. Reyes-Nava, Ignacio L. Garzon, Marcela R. Beltran, Karo Michaelian

Thermal stability properties and the melting-like transition of Na_n, n=13-147, clusters are studied through microcanonical molecular dynamics simulations. The metallic bonding in the sodium clusters is mimicked by a many-body Gupta potential based on the second moment approximation of a tight-binding Hamiltonian. The characteristics of the solid-to-liquid t

I. R. Afnan, B. F. Gibson

An OBE potential model for the ^{1}S_0 S = -2 interaction is analyzed with emphasis on the role of coupling between the Lambda Lambda, N Xi, and Sigma Sigma channels. Singlet scalar exchange, an approximation to two-pion exchange, is significant in all channels; surprisingly, the one-pion exchange component is almost negligible. The size of the channel coupl

S. Fritsch, N. Kaiser

We extend a recent chiral approach to nuclear matter of Lutz et al. [Phys. Lett. B474 (2000) 7] by calculating the underlying (complex-valued) single-particle potential U(p,k_f) + i W(p,k_f). The potential for a nucleon at the bottom of the Fermi-sea, U(0,k_{f0})= - 20.0 MeV, comes out as much too weakly attractive in this approach. Even more seriously, the

W. Melnitchouk, A. W. Thomas

We review recent developments in the study of deep inelastic scattering from light nuclei, focusing in particular on deuterium, helium, and lithium. Understanding the nuclear effects in these systems is essential for the extraction of information on the neutron structure function.

David R. Harrington

Some aspects of asymptotic freedom are discussed in the context of a simple two-particle non-relativisitic confining potential model. In this model asymptotic freedom follows from the similarity of the free-particle and bound state radial wave functions at small distances and for the same angular momentum and the same large energy. This similarity, which can

Li-gang Cao, Zhong-yu Ma

Single-particle resonant-states in the continuum are determined by solving scattering states of the Dirac equation with proper asymptotic conditions in the relativistic mean field theory (RMF). The regular and irregular solutions of the Dirac equation at a large radius where the nuclear potentials vanish are relativistic Coulomb wave functions, which are cal

Koichi Saito

Using the quark-meson coupling (QMC) model, we study nuclear matter from the point of view of quark degrees of freedom. Performing a re-definition of the scalar field in matter, we transform QMC to a QHD-type model with a non-linear scalar potential. The potentials obtained from QMC are compared with those of the relativistic mean-field models.

A. Yu. Orlov

We consider certain scalar product of symmetric functions which is parameterized by a function $r$ and an integer $n$. One the one hand we have a fermionic representation of this scalar product. On the other hand we get a representation of this product with the help of multi-integrals. This gives links between a theory of symmetric functions, soliton theory

C. Eugene Wayne, J. Douglas Wright

In order to investigate corrections to the common KdV approximation to long waves, we derive modulation equations for the evolution of long wavelength initial data for a Boussinesq equation. The equations governing the corrections to the KdV approximation are explicitly solvable and we prove estimates showing that they do indeed give a significantly better a

N. J. A. Sloane, B. Beferull-Lozano

The usual quantizer based on an n-dimensional lattice L maps a point x in R^n to a closest lattice point. Suppose L is the intersection of lattices L_1, ..., L_r. Then one may instead combine the information obtained by simultaneously quantizing x with respect to each of the L_i. This corresponds to decomposing R^n into a honeycomb of cells which are the int

N. J. A. Sloane, Vinay A. Vaishampayan

We consider Zador's asymptotic formula for the distortion-rate function for a variable-rate vector quantizer in the high-rate case. This formula involves the differential entropy of the source, the rate of the quantizer in bits per sample, and a coefficient G which depends on the geometry of the quantizer but is independent of the source. We give an expl

Hongbin Cui

This thesis studies the omega-categories associated with products of infinite-dimensional globes.

Biswaranjan Behera

We prove three results on wavelets for the Hardy space H^2(\R). All wavelets constructed so far for H^2(\R) are MSF wavelets. We construct a family of H^2-wavelets which are not MSF. An equivalence relation on H^2-wavelets is introduced and it is shown that the corresponding equivalence classes are non-empty. Finally, we construct a family of H^2-wavelets wi

Nicola Arcozzi, Biswaranjan Behera, Shobha Madan

We introduce a method to construct large classes of MSF wavelets of the Hardy space H^2(\R) and symmetric MSF wavelets of L^2(\R), and discuss the classification of such sets. As application, we show that there are uncountably many wavelet sets of L^2(\R) and H^2(\R). We also enumerate all symmetric wavelets of L^2(\R) with at most three intervals in the pos

Tom Farrell, Peter Linnell

We first prove that the Whitehead group of a torsion-free virtually solvable linear group vanishes. Next we make a reduction of the fibered isomorphism conjecture from virtually solvable groups to a class of virtually solvable Q-linear groups. Finally we prove an L-theory analogue for elementary amenable groups.

Alexei Bondal, Michel Van den Bergh

We give a sufficient condition for an Ext-finite triangulated category to be saturated. Saturatedness means that every contravariant cohomological functor of finite type to vector spaces is representable. The condition consists in existence of a strong generator. We prove that the bounded derived categories of coherent sheaves on smooth proper commutative an

Biswaranjan Behera

The dimension function D_psi of a band-limited wavelet is bounded by n if the support of its Fourier transform is contained in the interval [-{2^(n+2)/3}pi, {2^(n+2)/3}pi]. For each positive integer n and for each epsilon > 0, we construct a wavelet psi with support of $\hat psi$ contained in [-{2^(n+2)/3}pi, {2^(n+2)/3}pi + epsilon] such that D_psi > n on a

Y. Kamishima, L. Ornea

We study two kinds of transformation groups of a compact locally conformally Kahler (l.c.K.) manifold. First we study compact l.c.K. manifolds with parallel Lee form by means of the existence of a holomorphic l.c.K. flow. Next, we introduce the Lee-Cauchy-Riemann (LCR) transformations as a class of diffeomorphisms preserving the specific G-structure of l.c.K

Stefano Bolognesi, Kenichi Konishi

Magnetic monopoles having non-Abelian charges have been found recently to play a crucial role in the infrared in a class of supersymmetric gauge theories. We argue that these "dual quarks" can naturally be identified with the non-Abelian magnetic monopoles of the type first discussed by Goddard, Nuyts and Olive. Our argument is based on a few simple

A. Belhaj, J. J. Manjarin, P. Resco

Using the algebraic geometry method of Berenstein and Leigh for the construction of the toroidal orbifold (T^2 x T^2 x T^2) / (Z_2 x Z_2) with discrete torsion and considering local K3 surfaces, we present non-commutative aspects of the orbifolds of product of K3 surfaces. In this way, the ordinary complex deformation of K3 can be identified with the resolut

Poul Olesen, Francesco Sannino

We consider the Maldacena-Nunez supergravity solution corresponding to N=1 super Yang-Mills within the approach by Di Vecchia, Lerda and Merlatti. We show that if one uses the radial distance as a field theory scale, the corresponding beta function has an infrared fixed point. Assuming this to be a physical property for all four dimensional non-singular reno

Tarek Ibrahim, Pran Nath

A review is given of CP violation in a broad class of models based on supersymmetry, superstrings and brane models. Such models contain typically large CP violating phases which affect a variety of supersymmetric phenomenon at low energies and affect search for supersymmetry at colliders and in dark matter experiments. We focus here on few such phenomena, sp

Alexey A. Petrov

The Standard Model contribution to D0-anti-D0 mixing is dominated by the contributions of light s and d quarks. Neglecting the tiny effects due to b quark, both mass and lifetime differences vanish in the limit of SU(3) symmetry. Thus, the main challenge in the Standard Model calculation of the mass and width difference in the D0-anti-D0 system is to estimat

Antonio De Felice, Salah Nasri, Mark Trodden

The simplest explanation for early time acceleration (inflation) and the late time acceleration indicated by recent data is that they have a common origin. We investigate another generic cosmological implication of this possiblity, that the baryon asymmetry of the universe may be generated in such models. We identify several novel features of baryogenesis in

Stefano Forte

We review the way intense neutrino beams at the front-end of a muon storage ring can be used to probe the structure of hadrons. Specifically, we discuss how the polarized and unpolarized flavor structure of the nucleon can be disentangled in inclusive deep-inelastic scattering, and how less inclusive measurements can shed light on various aspects of hadron s

B. G. Zakharov

We study the coherent final state interaction of an energetic parton produced in AA collisions caused by the change in the cutoff scale and running coupling constant from the vacuum to QGP. We demonstrate that the contribution of this new mechanism to the energy loss may be of the order of magnitude of the induced gluon radiation. However, an accurate evalua

Kacer Zalewski

Numerous models have been proposed to describe the Bose-Einstein correlations in multiple particle production processes. In the present paper we describe a generalization, which includes many previous models as special cases and, therefore, can be useful for work of comparison. We apply the powerful methods of eigenfunction expansions and generating function

Andrea Piccione

This thesis is devoted to the study of some aspects of perturbative QCD, and in particular to the development of high-precision techniques for the extraction of physical parameters such as structure functions, parton distributions, and the strong coupling from the analysis of deep inelastic scattering data. First, we will discuss scaling violations of single

Zhi-zhong Xing

We show that both the weak phase βand the strong phase δ_d can be determined from the time-dependent measurement of B_d -> D^{*\pm} D^{\mp} decays, whose final states are non-CP eigenstates. It is also possible to extract βfrom B_d -> D^{*\pm} D^{*\mp} transitions without doing the angular analysis. Possible final-state rescattering effects in B_d -> D^{(*)\

Thomas Becher, Kirill Melnikov

We present a method of computing any one-loop integral in lattice perturbation theory by systematically expanding around its continuum limit. At any order in the expansion in the lattice spacing, the result can be written as a sum of continuum loop integrals in analytic regularization and a few genuine lattice integrals (``master integrals''). These

Zheng-Tao Wei, Mao-Zhi Yang

The pion electromagnetic form factor with leading and next-to-leading twist corrections are studied in the framework of pQCD approach. We find that, at small momentum transfer regions, Sudakov effects cannot provide a strong enough suppression of the non-perturbative contributions coming from large transverse separations, but at large momentum transfer regio

S. H. Kettell

The experimental program for the study of the rare kaon decays, K -> pnn, is summarized. A review of recent results is provided along with a discussion of prospects for the future of this program. The primary focus of the world-wide kaon program is the two golden modes: K+ -> pnn and KL -> pnn. The first step in an ambitious program to precisely measure both

Belle Collaboration, A. Drutskoy

The B -> D^{(*)} K^- K^{(*)0} decays have been observed for the first time. The branching fractions of the B -> D^{(*)} K^- K^{(*)0} decay modes are measured. Significant signals are found for the B -> D^{(*)} K^- K^{*0} and B^- -> D^0 K^- K^0_S decay modes. The invariant mass and polarization distributions for the K^-K^{*0} and K^-K^0_S subsystems have been

Michael Edmund Tobar, John Gideon Hartnett, James David Anstie

A new Michelson-Morley experiment is proposed by measuring the beat frequency of two near degenerate modes with orthogonal propagation in a single spherical resonator. The unique properties of the experiment allow: 1. Substantial common mode rejection of some noise sources: 2. Simple calculation of the signal if Special Relativity is violated. We show that o

M. Alves

This note deals with the possibility of non-trivial cosmological solutions given by quantum corrections in the framework of the Jackiw-Telteiboim model to the bidimensional gravity. The resulting model shows that the quantum corrections transform, in some cases, the classical solution into a more interesting one with initial singularity.

Filippo Maimone, Sergio De Filippo

It is shown that the Newtonian limit of a stable realization of HD gravity leads to a sharp transition, around 10^{11} proton masses, from the wavelike properties of microscopic particles to the classical behaviour of macroscopic bodies. Besides, due to nonunitarity, a pure state is expected to evolve into a microcanonical ensamble leading to thermal equilib

Ahmed Helmy

In this study, the concept of small worlds is investigated in the context of large-scale wireless ad hoc and sensor networks. Wireless networks are spatial graphs that are usually much more clustered than random networks and have much higher path length characteristics. We observe that by adding only few random links, path length of wireless networks can be

Konstantin Korovin, Andrei Voronkov

We show the NP-completeness of the existential theory of term algebras with the Knuth-Bendix order by giving a nondeterministic polynomial-time algorithm for solving Knuth-Bendix ordering constraints.

Bart Verheij

In the present paper, the existence and multiplicity problems of extensions are addressed. The focus is on extension of the stable type. The main result of the paper is an elegant characterization of the existence and multiplicity of extensions in terms of the notion of dialectical justification, a close cousin of the notion of admissibility. The characteriz

Ulrich Neumerkel, Stefan Kral

We present GUPU, a side-effect free environment specialized for programming courses. It seamlessly guides and supports students during all phases of program development, covering specification, implementation, and program debugging. GUPU features several innovations in this area. The specification phase is supported by reference implementations augmented wit

James Aspnes

It is well known that the consensus problem cannot be solved deterministically in an asynchronous environment, but that randomized solutions are possible. We propose a new model, called noisy scheduling, in which an adversarial schedule is perturbed randomly, and show that in this model randomness in the environment can substitute for randomness in the algor

Daniel Knapp, Catherine Kallin, A. John Berlinsky, Rachel Wortis

We present the results of quantum-mechanical calculations, using the singular gauge transformation of Franz and Tesanovic, of the rate of planar Cu spin-lattice relaxation due to electron spin-flip scattering in the mixed state of high-Tc cuprate superconductors. The results show a non-monotonic temperature and frequency dependence that differs markedly from

Gustavo A. Narvaez, George Kirczenow

We present microscopic transport calculations of the tunneling spectra of non-magnetic metal nanoparticles. We show that charge fluctuations give rise to tunneling resonances of a new type. Positive and negative fluctuations have differing kinetics and thus account for previously unexplained spectral features that are found experimentally under only forward

S. H. Pawar, P. M. Shirage, D. D. Shivagan

A pathway to high Tc and Jc with superconducting hetero-nano structures of Tl-2223/Al are reported first time. Two dimensional nano-stripe structure at the interface of Tl-2223/Al was fabricated with room temperature electrochemical complexing technique. The confinement of the charge transport along the hetero-nano stripes at the interface was studied at dif

Jure Demsar, Dragan Mihailovic, Viktor V. Kabanov

In this report we review recent experimental results on photoexcited carrier relaxation dynamics on high temperature superconductors (HTSC) probed by a femtosecond time-resolved optical spectroscopy, and compare the results with the data obtained on quasi two dimensional charge density waves. In these experiments, a femtosecond laser pump pulse excites elect

Manuela Minozzi, Guido Caldarelli, Luciano Pietronero, Stefano Zapperi

We study the acoustic emission produced by micro-cracks using a two-dimensional disordered lattice model of dynamic fracture, which allows to relate the acoustic response to the internal damage of the sample. We find that the distributions of acoustic energy bursts decays as a power law in agreement with experimental observations. The scaling exponents measu

Jonathan P. K. Doye, Shaun C. Hendy

We have located the global minimum for all lead clusters with up to 160 atoms using a glue potential to model the interatomic interactions. The lowest-energy structures are not face-centred cubic as suggested previously. Rather, for N<40 the majority of structures are decahedral or hexagonal close-packed, and beyond this size the structures do not correspond

Y. P. Shkolnikov, E. P. De Poortere, E. Tutuc, M. Shayegan

By measuring the angles at which the Landau levels overlap in tilted magnetic fields (the coincidence method), we determine the splitting of the conduction-band valleys in high-mobility two-dimensional (2D) electrons confined to AlAs quantum wells. The data reveal that, while the valleys are nearly degenerate in the absence of magnetic field, they split as a

R. Lopez-Sandoval, G. M. Pastor

A density functional theory (DFT) of lattice fermion models is presented, which uses the single-particle density matrix gamma_{ij} as basic variable. A simple, explicit approximation to the interaction-energy functional W[gamma] of the Hubbard model is derived from exact dimer results, scaling properties of W[gamma] and known limits. Systematic tests on the

Fabrizio Lillo, J. Doyne Farmer, Rosario N. Mantegna

We study the average price impact of a single trade executed in the NYSE. After appropriate averaging and rescaling, the data for the 1000 most highly capitalized stocks collapse onto a single function, giving average price shift as a function of trade size. This function increases as a power that is the order of 1/2 for small volumes, but then increases mor

A. Yu. Grosberg

Scaling arguments are used to analyze the size of topologically constrained closed ring polymer with excluded volume. It is found that there exists a finite range of polymer thickness (excluded volume) in which self-avoidance is unimportant and polymer swelling compared to the Gaussian size is entirely due to the topological constraints.

Armen M. Gulian, Kent S. Wood

Symmetry of the order parameter in some triplet superconductors corresponds to doubly-degenerate chiral states. We predict that in a sufficiently small sample this degeneracy can be lifted via macroscopic quantum tunneling. Moreover, if the initial state is prepared correspondingly, &#39;instanton&#39;-like quantum behavior is possible in a single-domain sam

Misha Turlakov, Anthony J. Leggett

The third moment frequency sum rule for the density-density correlation function is rederived in the presence of Umklapp processes. Upper and lower bounds on the electron-electron Coulomb energy are derived in two-dimensional and three-dimensional media, and the Umklapp processes are shown to be crucial in determining the spectrum of the density fluctuations

Bertrand Berche, Christophe Chatelain

The influence of uncorrelated, quenched disorder on the phase transition of two dimensional Potts models will be reviewed. After an introduction where the conditions of relevance of quenched randomness on phase transitions are exemplified by experimental measurements, the results of perturbative and numerical investigations in the case of the Potts model wil

O. Petracic, S. Sahoo, Ch. Binek, W. Kleemann

Ac susceptibility measurements were performed on discontinuous magnetic multilayers [Co80Fe20(t)/Al2O3(3nm)]x10, t = 0.9 and 1.0nm, by Superconducting Quantum Interference Device (SQUID) magnetometry. The CoFe forms nearly spherical ferromagnetic single-domain nanoparticles in the diamagnetic Al2O3 matrix. Due to dipolar interactions and random distribution

Andrea Montanari, Federico Ricci-Tersenghi

We consider the dynamics of a diluted mean-field spin glass model in the aging regime. The model presents a particularly rich heterogeneous behavior. In order to catch this behavior, we perform a **spin-by-spin analysis** for a **given disorder realization**. The results compare well with the outcome of a static calculation which uses the ``survey propagatio

Giorgio Parisi, Nicolas Sourlas

We show by numerical simulations that the correlation function of the random field Ising model (RFIM) in the critical region in three dimensions has very strong fluctuations and that in a finite volume the correlation length is not self-averaging. This is due to the formation of a bound state in the underlying field theory. We argue that this non perturbativ

N. Garcia, M. Nieto-Vesperinas

Answer to Comment by J.B. Pendry on&#34; Left-handed materials do not make a perfect lens&#34; by N. Garcia and M. Nieto-Vesperinas

T. Nakajima, H. Kageyama, H. Yoshizawa, Y. Ueda

New metal-ordered manganites RBaMn_{2}O_{6} have been synthesized and investigated in the structures and electromagnetic properties. RBaMn_{2}O_{6} can be classified into three groups from the structural and electromagnetic properties. The first group (R = La, Pr and Nd) has a metallic ferromagnetic transition, followed by an A-type antiferromagnetic transit

P. Debray, V. Gurevich, R. Klesse, R. S. Newrock

The presence of pronounced electronic correlations in one-dimensional systems strongly enhances Coulomb coupling and is expected to result in distinctive features in the Coulomb drag between them that are absent in the drag between two-dimensional systems. We review recent Fermi and Luttinger liquid theories of Coulomb drag between ballistic one-dimensional

S. H. Pawar, A. B. Jadhav, P. M. Shirage, D. D. Shivagan

A complexing molecule electrodeposition technique has been developed for the deposition of low cost, lightweight MgB2 films, for the first time. Different deposition parameters such as bath composition, deposition potential, current density, deposition time were studied and optimized to give uniform, homogeneous and sticky films. The MgB2 films were deposite

Takahiro Hatano, David Jou

The meaning of temperature in nonequilibrium thermodynamics is considered by using a forced harmonic oscillator in a heat bath, where we have two effective temperatures for the position and the momentum, respectively. We invent a concrete model of a thermometer to testify the validity of these different temperatures from the operational point of view. It is

U. Tartaglino, E. Tosatti, D. Passerone, F. Ercolessi

Strain can affect the morphology of a crystal surface, and cause modifications of its reconstruction even when weak, as in the case of mechanical bending. We carried out calculations of strain-dependent surface free energy and direct bending simulations demonstrating the change of incommensurate reconstruction in Au(111) under strain, in good agreement with

T. Papenbrock, A. N. Salgueiro, H. A. Weidenmueller

We study two sets of rate equations for sympathetic cooling of harmonically trapped Bose gases. Calculations for mixtures of Na-Rb and Li-Cs show that both sets yield similar results for the cooling times. The equilibration rates are in fair agreement with each other and differ considerably from classical rates. The onset of Bose-Einstein condensation is rat

Cheongho Han, Wonyong Han

Although many methods of detecting extra-solar planets have been proposed and successful implementation of some of these methods enabled a rapidly increasing number of exoplanet detections, little has been discussed about the method of detecting satellites around exoplanets. In this paper, we test the feasibility of detecting satellites of exoplanets via mic

N. Ryde, D. L. Lambert, M. J. Richter, J. H. Lacy

We report detections of pure rotation lines of OH and H2O in the K1.5 III red-giant star Arcturus (alpha Bootis) using high-resolution, infrared spectra covering the regions 806-822 cm-1 (12.2-12.4 um) and 884-923 cm-1 (10.8-11.3 um). Arcturus is the hottest star yet to show water-vapor features in its disk-averaged spectrum. We argue that the water vapor li

Jane C. Charlton

High resolution rest frame UV quasar absorption spectra covering low and high ionization species, as well as the Lyman series lines, provide remarkably detailed information about the gaseous phases of galaxies and their environments. For redshifts less than 1.5, many important chemical transitions remain in the observed ultraviolet wavelength range. I presen

Samir Salim, Andrew Gould

Revised NLTT (New Luyten Catalogue of Stars With Proper Motions Larger than Two Tenths of an Arcsecond) contains improved astrometry and new optical/infrared photometry for the vast majority of NLTT stars lying in the overlap of regions covered by POSS I and by the 2MASS release, approximately 44% of the sky. The epoch 2000 positions are typically accurate t

D. Falceta-Goncalves, V. Jatenco-Pereira, Z. Abraham

Massive binary star systems are not uncommon, and neither the supersonic collision of their winds. In the present work we study these shocks and the further consequences on wind structure. The post-shock gas is a warm and high-density environment, which allows dust to form and grow. We show that this growth is fast, of just a few hours. An application for et

Gastao B. Lima Neto, Florence Durret

From ROSAT data, the bright X-ray cluster Abell 85 was found to show a roughly symmetrical shape, on to which are superimposed several features, among which: (1) a blob or group of galaxies falling on to the main cluster, with the gas in the impact region probably hotter and the galaxies in that zone showing enhanced star formation; (2) a filament, either di

Pasquale Blasi

The search for gamma radiation in clusters of galaxies represents a precious tool to investigate the history of these large scale structures. Clusters or sources within them accelerate cosmic rays, as demonstrated by the detection of radio halos, hard X-rays and UV emission, and confine them over cosmological time scales. Nonthermal and thermal phenomena may

Michael L. Balogh, R. G. Bower, Ian Smail, B. L. Ziegler

We present the first spectroscopic survey of intrinsically low Lx clusters at z>>0, with HST WFPC2 imaging and ground-based spectroscopy. We study 172 confirmed cluster members in a sample of ten clusters at z=0.23-0.3, with Lx<4.E43 h^{-2} ergs/s. The core of each cluster is imaged with WFPC2 in the F702W filter, and the spectroscopic sample is statisticall

D. Guetta, C. Distefano, A. Levinson, E. Waxman

We discuss the possibility that microquasar jets may be powerful emitters of TeV neutrinos. We estimate the neutrino fluxes produced by photopion production in the jets of a sample of identified microquasars and microquasar candidates, for which available data enables rough determination of the jet parameters. We demonstrate that in several of the sources co

M. L. Balogh, R. G. Bower

The globally-averaged star formation rate in the Universe has been steadily declining since at least z~1. This may be due either to very local processes operating within the average galaxy, or to external, environmental effects. Specifically, the build-up of structure may be responsible for terminating star formation in some galaxies and thus decreasing the

Xiang-Ping Wu

I will briefly review various analytic approaches to understanding the contents and properties of the hot X-ray emitting gas contained in clusters and groups. Special emphases are given to the following three issues: (1)Reconstruction of the gas distribution in groups and clusters from a (joint) analysis of X-ray, SZ and gravitational lensing observations; (

Saleem Zaroubi, Enzo Branchini, Yehuda Hoffman, Luiz N. da Costa

We apply a new algorithm, called the Unbiased Minimal Variance (hereafter UMV) estimator, to reconstruct the cosmic density and peculiar velocity fields in our local universe from the SEcat catalog of peculiar velocities comprising both early (ENEAR) and late type (SFI) galaxies. The reconstructed fields are compared with those predicted from the IRAS PSCz g

E. Pian, R. Falomo, R. C. Hartman, L. Maraschi

PKS 0537-441, a bright gamma-ray emitting blazar, was observed at radio, optical, UV and X-ray frequencies during various EGRET pointings, often quasi-simultaneously. In 1995 the object was found in an intense emission state at all wavelengths. BeppoSAX observations made in 1998, non-simultaneously with exposures at other frequencies, allow us to characteriz

Marcus Brueggen, Christian R. Kaiser

The hot plasma permeating clusters of galaxies often shows a central peak in the X-ray surface brightness that is coincident with a drop in entropy. This is taken as evidence for a cooling flow where the radiative cooling in the central regions of a cluster causes a slow subsonic inflow. Searches in all wavebands have revealed significantly less cool gas tha

P. Saracco, M. Longhetti, P. Severgnini, R. Della Ceca

A near-IR low-resolution spectroscopic follow-up of a complete sample of K<18.5 EROs has started at the 3.5 m Telescopio Nazionale Galileo (TNG, La Palma, Canary Islands) by using a prism disperser AMICI. The sample has been selected from the Munich Near-IR Cluster Survey (MUNICS). The project aims at revealing massive galaxies at z>1.2 and at estimating the

Reuben Thieberger

This work is a continuation of a previous publication {Thieberger and Spiegel,astro-ph/0204485} concerning the use of two dimensional catalogues in unraveling the large scale distribution of galaxies. Since the data in two-dimensional catalogues are more plentiful than those in three dimensions, the luminosity method can be helpful in using two dimensional d

Amaya Moro-Martin, Renu Malhotra

The dust produced in the Kuiper Belt (KB) spreads throughout the Solar System forming a dust disk. We numerically model the orbital evolution of KB dust and estimate its equilibrium spatial distribution and its brightness and spectral energy distributions (SED), assuming greybody absorption and emission by the dust grains. We show that the planets modify the

Hideyuki Kamaya, Joseph Silk

It has recently been argued that the unidentified SCUBA objects (USOs) are a thick disk population of free-floating dense, compact galactic gas clumps at a temperature of about 7 K. The characteristic mass scale is constrained to be on the order of a Jupiter mass, and the size is about 10 AU. A typical galactic USO is located at a distance from the sun of ab

P. J. E. Peebles, Bharat Ratra

Physics invites the idea that space contains energy whose gravitational effect approximates that of Einstein&#39;s cosmological constant, Lambda; nowadays the concept is termed dark energy or quintessence. Physics also suggests the dark energy could be dynamical, allowing the arguably appealing picture that the dark energy density is evolving to its natural

I. A. Shovkovy, P. J. Ellis

The thermal conductivity of the color-flavor locked phase of dense quark matter is calculated. The dominant contribution to the conductivity comes from photons and Nambu-Goldstone bosons associated with the breaking of baryon number, both of which are trapped in the quark core. Because of their very large mean free path the conductivity is also very large. T

Chenyang Wang, Jim Harrington, John Preskill

We study the +/- J random-plaquette Z_2 gauge model (RPGM) in three spatial dimensions, a three-dimensional analog of the two-dimensional +/- J random-bond Ising model (RBIM). The model is a pure Z_2 gauge theory in which randomly chosen plaquettes (occuring with concentration p) have couplings with the ``wrong sign&#39;&#39; so that magnetic flux is energet

Y. Attaourti, B. Manaut

The first differential cross section for Mott scattering of a Dirac-Volkov electron is reviewed. The expression (26) derived by Szymanowski et al. [Physical Review A {\bf 56}, 3846,(1997)] is corrected. In particular, we disagree with the expression of $(\frac{dσ}{dΩ})$ they obtained and we give the exact coefficients multiplying the various Bessel functions

S. Itza-Ortiz, N. S. Rebello, D. Zollman, M. Rodriguez-Achach

We investigate studnets&#39; use of words used in everyday language as well as in physics. We find students are more likely to identify and explain the meaning of the word as it is used in physics when they have become familiar with the associated physical variables.

J. E. Hirsch

A model to describe electronic correlations in energy bands is considered. The model is a generalization of the conventional Hubbard model that allows for the fact that the wavefunction for two electrons occupying the same Wannier orbital is different from the product of single electron wavefunctions. We diagonalize the Hamiltonian exactly on a four-site clu

Y. Lemperiere, E. P. S. Shellard

We present analytic and numerical results for the evolution of currents on superconducting strings in the classical $U(1) \times U(1)$ model. We derive an energy functional for the currents and charges on these strings, establishing rigorously that minima should exist in this model for loops of finite size (vortons) if both charge and current are present on

P. Grandclement, V. Kalogera, A. Vecchio

We consider the problem of searching for gravitational waves emitted during the inspiral phase of binary systems when the orbital plane precesses due to relativistic spin-orbit coupling. Such effect takes place when the spins of the binary members are misaligned with respect to the orbital angular momentum. As a first step we assess the importance of precess

Victo S. Filho, T. Frederico, Arnaldo Gammal, Lauro Tomio

The dynamics of a nonconservative Gross-Pitaevskii equation for trapped atomic systems with attractive two-body interaction is numerically investigated, considering wide variations of the nonconservative parameters, related to atomic feeding and dissipation. We study the possible limitations of the mean field description for an atomic condensate with attract