February 2000 arXiv papers — page 11

M. Barthelemy, S. V. Buldyrev, S. Havlin, H. E. Stanley

We study the multifractal spectrum of the current in the two-dimensional random resistor network at the percolation threshold. We consider two ways of applying the voltage difference: (i) two parallel bars, and (ii) two points. Our numerical results suggest that in the infinite system limit, the probability distribution behaves for small current i as P(i) ~

L. Benfatto, S. Caprara, C. Di Castro

We describe the spectral properties of underdoped cuprates as resulting from a momentum-dependent pseudogap in the normal state spectrum. Such a model accounts, within a BCS approach, for the doping dependence of the critical temperature and for the two-parameter leading-edge shift observed in the cuprates. By introducing a phenomenological temperature depen

A. C. Fabian, I. Smail, K. Iwasawa, S. W. Allen

The powerful combination of the Chandra X-ray telescope, the SCUBA submillimetre-wave camera and the gravitational lensing effect of the massive galaxy clusters A2390 and A1835 has been used to place stringent X-ray flux limits on six faint submillimetre SCUBA sources and deep submillimetre limits on three Chandra sources which lie in fields common to both i

Adi Nusser

Analytic solutions for the evolution of cosmological linear density perturbations in the baryonic gas and collisionless dark matter are derived. The solutions are expressed in a closed form in terms of elementary functions, for arbitrary baryonic mass fraction. They are obtained assuming $Ω=1$ and a time independent comoving Jeans wavenumber, $k_J$. By worki

F. Caravaglios, F. Parodi, P. Roudeau, A. Stocchi

Within the Standard Model, a review of the current determination of the CKM unitarity triangle parameters is presented, using experimental constraints from the measurements of |epsilon_K|, V_ub/V_cb, Delta m_d and from the limit on Delta m_s, available by end 1999.

L. Kullmann, J. Kertesz, R. N. Mantegna

The clustering of companies within a specific stock market index is studied by means of super-paramagnetic transitions of an appropriate q-state Potts model where the spins correspond to companies and the interactions are functions of the correlation coefficients determined from the time dependence of the companies' individual stock prices. The method is

Maria E. Angulo, Guillermo A. Mena Marugan

Linearly polarized cylindrical waves in four-dimensional vacuum gravity are mathematically equivalent to rotationally symmetric gravity coupled to a Maxwell (or Klein-Gordon) field in three dimensions. The quantization of this latter system was performed by Ashtekar and Pierri in a recent work. Employing that quantization, we obtain here a complete quantum t

W. J. Zheng

By modeling the stripe phase in cuprates as spin gapped stripes coupled to the RVB liquid of preformed electron pairs, I derive the low energy effective theory of the RVB phase variable. It is found that the effect of stripe dynamics (including both longitudinal and transverse modes) leads to incipient temporal phase stiffness in the RVB liquid, which tunes

Savdeep Sethi, Mark Stern

We derive a set of equations for the wavefunction describing the marginal bound state of a single D0-brane with a single D4-brane. These are equations determining the vacuum of an N=8 abelian gauge theory with a charged hypermultiplet. We then solve these equations for the most general possible zero-energy solution using a Taylor series. We find that there a

N. A. Bahcall, R. Cen, R. Davé, J. P. Ostriker

We use large-scale cosmological simulations to estimate the mass-to-light ratio of galaxy systems as a function of scale, and compare the results with observations of galaxies, groups, clusters, and superclusters of galaxies. We find remarkably good agreement between observations and simulations. Specifically, we find that the simulated mass-to-light ratio i

C. Grojean

We advocate that the orbifold Z_2 symmetry of the gravity trapping model proposed by Randall and Sundrum can be seen, in appropriate coordinates, as a symmetry that exchanges the short distances with the large ones. Using diffeomorphism invariance, we construct extensions defined by patch glued together. A singularity occurs at the junction and it is interpr

Jay D. Salmonson, James R. Wilson, Grant J. Mathews

A model is proposed for gamma-ray bursts based upon a neutrino burst of about 10^52 ergs lasting a few seconds above a heated collapsing neutron star. This type of thermal neutrino burst is suggested by relativistic hydrodynamic studies of the compression, heating, and collapse of close binary neutron stars as they approach their last stable orbit, but may a

J. J. Alvarez, C. Gomez

We show that Grover's algorithm defines a geodesic in quantum Hilbert space with the Fubini-Study metric. From statistical point of view Grover's algorithm is characterized by constant Fisher's function. Quantum algorithms changing complexity class as Shor's factorization does not preserve constant Fisher's information. An adiabatic quant

Jeffrey A. Barrett

In this paper I describe the history of the surreal trajectories problem and argue that in fact it is not a problem for Bohm's theory. More specifically, I argue that one can take the particle trajectories predicted by Bohm's theory to be the actual trajectories that particles follow and that there is no reason to suppose that good particle detectors

Arnold Neumaier

It is shown that, for a harmonic oscillator in the ground state, Bohmian mechanics and quantum mechanics predict values of opposite sign for certain time correlations. The discrepancy can be explained by the fact that Bohmian mechanics has no natural way to accomodate the Heisenberg picture, since the local expectation values that define the beables of the t

H. Kunz, J. Chapuis, A. Jory

We analyse the ground state of a particle in a double-well potential, with a cylindrical symmetry, and in the presence of a magnetic field. We find that the azimuthal quantum number m takes the values m = 0,1,2... when we increase the magnetic field. At critical values of the magnetic field, the ground state is twice degenerate. The magnetisation shows an os

D. M. Snyder

It is argued that there is a connection between the fundamental forces of electromagnetism and gravitation. This connection occurs because of: 1) the fundamental significance of the finite and invariant velocity of light in inertial reference frames in the special theory, and 2) the reliance of the general theory of relativity upon the special theory of rela

V. I. Dimitrov, F. Dönau, S. Frauendorf

A hybrid version the deformed nuclear potential is suggested, which combines a spherical Woods Saxon potential with a deformed Nilsson potential. It removes the problems of the conventional Nilsson potential in the mass 130 region. Based on the hybrid potential, tilted axis cranking calculations are carried out for the magnetic dipole band in ^{128}Ba.

Ulrich Heinz, Maurice Jacob

This "position paper" collects the scientific arguments behind the CERN Press Release of February 10, 2000, which announced evidence for the creation of a new state of matter in Pb-Pb collisions at the CERN SPS. The data on which this paper is based were presented in a special seminar at CERN on the same day, a recording of which can be accessed at h

Mark W. Paris, Vijay R. Pandharipande

The variational Monte Carlo method is used to find the ground state of six quarks confined to a cavity of diameter R_c, interacting via an assumed non-relativistic constituent quark model (CQM) Hamiltonian. We use a flux-tube model augmented with one-gluon and one-pion exchange interactions, which has been successful in describing single hadron spectra. The

Ju. M. Gavriljuk, V. V. Kuzminov, N. Ya. Osetrova, S. S. Ratkevich

Features of data accumulated at 1817 hours in the experimental search for 2K(2 ν)-capture decay mode of Kr-78 are discussed. The new limit for this decay half-life is found to be T_{1/2} > 2.3 *10^{20} yr. (90% C.L.).

Kestutis Staliunas, Victor J. Sanchez-Morcillo

The phenomenon of pattern formation in nonlinear optical resonators is commonly related to an off-resonance excitation mechanism, where patterns occur due to mismatch between the excitation and resonance frequency. In this paper we show that the patterns in nonlinear optics can also occur due to the interplay between diffractions of coupled field components.

G. A. Kuzmin

We present a conformal theory for intermittent scalar fields. As an example, we consider the energy flux from large to small scales in the developed turbulent flow. The conformal correlation functions are found in the inertial range of scales. In the simplest case, the theory leads to the log-normal model. Parameters of the model are expressed via integrals

G. I. Barenblatt, A. J. Chorin, V. M. Prostokishin

We demonstrate that the processing of the experimental data for the average velocity profiles obtained by J. M. Österlund (www.mesh.kth.se/$\sim$jens/zpg/) presented in [1] was incorrect. Properly processed these data lead to the opposite conclusion: they confirm the Reynolds-number-dependent scaling law and disprove the conclusion that the flow in the inter

Martin A. Guest, Takashi Otofuji

We describe a relation between the periodic one-dimensional Toda lattice and the quantum cohomology of the periodic flag manifold (an infinite-dimensional Kaehler manifold). This generalizes a result of Givental and Kim relating the open Toda lattice and the quantum cohomology of the finite-dimensional flag manifold. We derive a simple and explicit "diff

Matthew G. Zinno

A connection is made between the Krammer representation and the Birman-Murakami-Wenzl algebra. Inspired by a dimension argument, a basis is found for a certain irrep of the algebra, and relations which generate the matrices are found. Following a rescaling and change of parameters, the matrices are found to be identical to those of the Krammer representation

Andrei Okounkov

We give a representation-theoretic proof of the formula for correlation functions of z-measures obtained by Borodin and Olshanski in math.RT/9904010. This paper is historically preceding my paper math.RT/9907127.

Zakir F. Seidov

Classical problem of random triangle in square is solved by simple and transparent geometrical method.

Alexander Kurganov, Doron Levy

We present a new third-order, semi-discrete, central method for approximating solutions to multi-dimensional systems of hyperbolic conservation laws, convection-diffusion equations, and related problems. Our method is a high-order extension of the recently proposed second-order, semi-discrete method in [16]. The method is derived independently of the specifi

Jacek Brodzki, Roger Plymen

We construct a Chern character map from the K-theory of the reduced C^* algebra of the p-adic GL(n) with values in the periodic cyclic homology of the Schwartz algebra of this group. We prove that this map is an isomorphism after tensoring with C by comparing an explicit formula, stated in the algebraic case by Cuntz and Quillen, with the classical Chern cha

Alan Dow, Klaas Pieter Hart

We show that hereditarily indecomposable spaces can be characterized by a special instance of the Intermediate Value Theorem in their rings of continuous functions.

Pavel Etingof, Shlomo Gelaki

In 1997 we proved that any triangular semisimple Hopf algebra over an algebraically closed field k of characteristic 0 is obtained from the group algebra k[G] of a finite group G, by twisting its comultiplication by a twist in the sense of Drinfeld. In this paper, we generalize this result to not necessarily finite-dimensional cotriangular Hopf algebras. Nam

Paul Federbush

We continue our study of gravity described by the action density (-g)^(1/2)(R_ik^2+bR^2); and look for cosmological solutions of gravity coupled to dust, for the closed isotropic model. There is a solution that at t approaches zero has for the radius, a(t)=t/3^(1/2); in the absence of dust this solution holds for all time.

J. Zinn-Justin

Renormalization group, and in particular its Quantum Field Theory implementation has provided us with essential tools for the description of the phase transitions and critical phenomena beyond mean field theory. We therefore review the methods, based on renormalized phi^4_3 quantum field theory and renormalization group, which have led to a precise determina

Sergei Kuzenko, Stefan Theisen

We review recent results on the general structure of two- and three- point functions of the supercurrent and the flavor current of N = 2 superconformal field theories.

Thomas Boettner, Sergei V. Ketov, Thomas Lau

We find a manifestly N=3 supersymmetric generalization of the four-dimensional Euler-Heisenberg (four-derivative, or F^4) part of the Born-Infeld action in light-cone gauge, by using N=3 light-cone superspace.

W. Mueck, K. S. Viswanathan, I. V. Volovich

In brane world models our universe is considered as a brane imbedded into a higher dimensional space. We discuss the behaviour of geodesics in the Randall-Sundrum background and point out that free massive particles cannot move along the brane only. The brane is repulsive, and matter will be expelled from the brane into the extra dimension. This is rather un

Frederik Roose

In this note the open string partition function is analyzed carefully in a way to reveal the group-theoretical aspects. For the simple cases of ADE orbifolds with regular Chan-Paton action a prescription for consistent boundary states is given. In the process of outlining how they encode McKay correspondence, we argue that this results from a non-trivial con

Jose Wudka

These lectures provide an introduction to effective theories concentrating on the basic ideas and providing some simple applications

E. L. Koschmieder

From the well-known decays of the particles follows that the mesons and baryons consist of a $γ$-branch and a neutrino branch. From the well-known masses of the particles follows that the masses of the $γ$-branch particles are integer multiples of the mass of the $π^0$ meson, within 3%, in spite of differences in spin, isospin, strangeness and charm. The ave

K. R. S. Balaji, Amol S. Dighe, R. N. Mohapatra, M. K. Parida

We show that the neutrino mixing pattern with the large mixing required for the atmospheric neutrino problem and the small mixing angle MSW solution for the solar neutrino problem can be naturally generated through radiative magnification, even though all the mixing angles at the seesaw scale may be small. This can account for the neutrino anomalies as well

Joannis Papavassiliou, Kostas Philippides

We present a model-independent method for determining anomalous gauge boson couplings from ongoing and future e^{+}e^{-} -> W^{+} W^{-} experiments. First we generalize an already existing method, which relies on the study of four observables constructed through appropriate projections of the unpolarized differential cross-section. In particular, we retain b

P. J. Dervan, A. Signer, W. J. Stirling, A. Werthenbach

This article reviews some recent developments in the analysis of anomalous triple and quartic vector boson couplings that have been discussed at the UK Phenomenology Workshop on Collider Physics 1999 in Durham.

A. A. Bykov, V. Yu. Popov, T. I. Rashba, V. B. Semikoz

We have found allowed squared mass difference, magnetic field, mixing angle - regions for the Resonant Spin-Flavor Precession Solution to the Solar Neutrino Problem fitted with the data of all acting solar neutrino experiments. The typical mass difference region varying in dependence on the mixing angle is allowed for some discrete magnetic field regions in

D. London, N. Sinha, R. Sinha

The $b\to d$ penguin amplitude receives contributions from internal $u$, $c$ and $t$-quarks. We show that it is impossible to measure the weak phase of any of these penguin contributions without theoretical input. However, a single assumption involving the hadronic parameters makes it possible to obtain the weak phase and test for the presence of new physics

Dimitri Bourilkov

A combined analysis of the data on Bhabha scattering at centre-of-mass energies 183 and 189 GeV from the LEP experiments ALEPH, L3 and OPAL is performed to search for effects of TeV strings in quantum gravity models with large extra dimensions. No statistically significant deviations from the Standard Model expectations are observed and lower limit on the st

N. Tanimoto, I. Nakano, M. Sakuda

We set limits on the magnetic moment and charge radius of the tau neutrino by examining an extra contribution to the electroweak process $e^+ e^- \to ν\barνγ$ using VENUS, TOPAZ and AMY results. We find that $κ(ν_τ) < 9.1\times{10}^{-6}$ (i.e. $μ(ν_τ) < 9.1\times{10}^{-6}μ_B, μ_B = e/2m_e$) and $<r^2 > < 3.1\times{10}^{-31}$cm$^2$ with Poisson statistics by

E. L. Koschmieder, T. H. Koschmieder

In order to explain the empirical integer multiple rule for the stable mesons and baryons presented in the preceding paper we assume that the particles are held together in a cubic nuclear lattice. This is a novel approach to the particles, based on the fact that the range of the weak nuclear force is only a thousandth of the diameter of the nucleon, and tha

J. Ambjorn, D. V. Boulatov, N. Kawamoto, Y. Watabiki

We study numerically the phase structure of a model of 3D gravity interacting with scalar fermions. We measure the 3D counterpart of the &#34;string&#34; susceptibility exponent as a function of the inverse Newton coupling $α$. We show that there are two phases separated by a critical point around $α_c \simeq 2$. The numerical results support the hypothesis

L3 Collaboration

We report on measurements of hadronic and leptonic cross sections and leptonic forward-backward asymmetries performed with the L3 detector in the years 1993-95. A total luminosity of 103 pb^-1 was collected at centre-of-mass energies \sqrt{s} ~ m_Z and \sqrt{s} ~ m_Z +/- 1.8 GeV which corresponds to 2.5 million hadronic and 245 thousand leptonic events selec

J. W. Maluf, A. A. Sousa

We consider the most general class of teleparallel theories of gravity quadratic in the torsion tensor, and carry out a detailed investigation of its Hamiltonian formulation in the time gauge. Such general class is given by a three-parameter family of theories. A consistent implementation of the Legendre transform reduces the original theory to a one-paramet

H. Salehi, H. R. Sepangi, F. Darabi

We study the breakdown of conformal symmetry in a conformally invariant gravitational model. The symmetry breaking is introduced by defining a preferred conformal frame in terms of the large scale characteristics of the universe. In this context we show that a local change of the preferred conformal frame results in a Hamilton-Jacobi equation describing a pa

R. A. d&#39;Inverno, M. R. Dubal, E. A. Sarkies

This paper is part of a long term program to Cauchy-characteristic matching (CCM) codes as investigative tools in numerical relativity. The approach has two distinct features: (i) it dispenses with an outer boundary condition and replaces this with matching conditions at an interface between the Cauchy and characteristic regions, and (ii) by employing a comp

Yuk Tung Liu, Kip S. Thorne

An analysis is given of thermoelastic noise (thermal noise due to thermoelastic dissipation) in finite sized test masses of laser interferometer gravitational-wave detectors. Finite-size effects increase the thermoelastic noise by a modest amount; for example, for the sapphire test masses tentatively planned for LIGO-II and plausible beam-spot radii, the inc

Luis M. Rocha, Johan Bollen

We discuss how distributed designs that draw from biological network metaphors can largely improve the current state of information retrieval and knowledge management of distributed information systems. In particular, two adaptive recommendation systems named TalkMine and @ApWeb are discussed in more detail. TalkMine operates at the semantic level of keyword

Luis M. Rocha

Two different types of agency are discussed based on dynamically coherent and incoherent couplings with an environment respectively. I propose that until a private syntax (syntactic autonomy) is discovered by dynamically coherent agents, there are no significant or interesting types of closure or autonomy. When syntactic autonomy is established, then, becaus

R. Gates, P. Katis, N. Sabadini, R. F. C. Walters

We present a theory of automata with boundary for designing, modelling and analysing distributed systems. Notions of behaviour, design and simulation appropriate to the theory are defined. The problem of model checking for deadlock detection is discussed, and an algorithm for state space reduction in exhaustive search, based on the theory presented here, is

Hisamitsu Mukaida, Yoshinori Sakamoto

We reconsider stability of the non-trivial fixed point in $6-ε$ dimensional effective action for the random field Ising model derived by Brézin and De Dominicis. After expansion parameters of physical observables are clarified, we find that the non-trivial fixed point in $6-ε$ dimensions is stable, contrary to the argument by Brézin and De Dominicis. We also

A. Diaz-Ortiz, J. M. Sanchez, J. L. Moran-Lopez

Confinement effects on the phase transitions in antiferromagnets are studied as a function of the surface coupling v and the surface field h for bcc(110) films. Unusual topologies for the phase diagram are attained for particular combinations of v and h. It is shown that some of the characteristics of the finite-temperature behavior of the system are driven

E. Orignac, R. Citro

The Raman scattering spectra from magnetic excitations in an antiferromagnetic spin-1/2 two leg ladder is investigated for weak and strong interladder coupling. In the first case, a cusp in the Raman intensityis obtained at a frequency twice the gap. In the second case, a peak at twice the gap replaces the cusp. We discuss the relevance of our calculation to

S. Das Sarma, Jaroslav Fabian, Xuedong Hu, Igor Zutic

Selected problems of fundamental importance for spintronics and spin-polarized transport are reviewed, some of them with a special emphasis on their applications in quantum computing and coherent control of quantum dynamics. The role of the solid-state environment in the decoherence of electron spins is discussed. In particular, the limiting effect of the sp

Eugene M. Chudnovsky, Jonathan R. Friedman

We study macroscopic quantum tunneling of the magnetic moment in a single-domain particle placed above the surface of a superconductor. Such a setup allows one to manipulate the height of the energy barrier, preserving the degeneracy of the ground state. The tunneling amplitude and the effect of the dissipation in the superconductor are computed.

M. A. Boselli, A. Ghazali, I. C. da Cunha Lima

The magnetic order resulting from a confinement-adapted Ruderman-Kittel-Kasuya-Yosida indirect exchange between magnetic moments in the metallic phase of a AlAs/Ga(1-x)Mn(x)As quantum well is studied by Monte Carlo simulation. This coupling mechanism involves magnetic moments and carriers (holes), both coming from the same Mn(2+) ions. It leads to a paramagn

H. Predel, H. Buhmann, L. W. Molenkamp, R. N. Gurzhi

We have studied experimentally and theoretically the influence of electron-electron collisions on the propagation of electron beams in a two-dimensional electron gas for excess injection energies ranging from zero up to the Fermi energy. We find that the detector signal consists of quasiballistic electrons, which either have not undergone any electron-electr

I. M. Sokolov

Typical man-made locomotive devices use reversible gears, as cranks, for transforming reciprocating motion into directed one. Such gears are holonomic and have the transduction efficiency of unity. On the other hand, a typical gear of molecular motors is a ratchet rectifier, which is irreversible. We discuss what properties of rectifier mostly influence the

Richard P. Sear

Colloidal particles are not simple rigid particles, in general an isolated particle is a system with many degrees of freedom in its own right, e.g., the counterions around a charged colloidal particle.The behaviour of model colloidal particles, with a simple phenomenological model to account for these degrees of freedom, is studied. It is found that the inte

E. N. M. Cirillo, G. Gonnella, A. Pelizzola

The phase diagram of a vertex model introduced by P. Di Francesco (Nucl. Phys. B 525, 507 1998) representing the configurations of a square lattice which can fold with different bending energies along the main axes and the diagonals has been studied by Cluster Variation Method. A very rich structure with partially and completely folded phases, different diso

Peter Horak, Helmut Ritsch

We study the zero temperature dynamics of Bose-Einstein condensates in driven high-quality optical cavities in the limit of large atom-field detuning. We calculate the stationary ground state and the spectrum of coupled atom and field mode excitations for standing wave cavities as well as for travelling wave cavities. Finite cavity response times lead to dam

C. E. Gough, P. J. Thomas, J. C. Fenton, G. Yang

Intrinsic c-axis tunnelling in the superconducting state has been measured in zero and finite fields in small mesa structures fabricated on the surface of 2212-BSCCO single crystals. The temperature dependence of the zero-field critical current and quasi-particle conductance is related to microscopic d-wave models in the presence of impurity scattering. The

Giovanni Gallavotti

Two very different problems that can be studied by renormalization group methods are discussed with the aim of showing the conceptual unity that renormalization group has introduced in some areas of theoretical Physics. The two problems are: the ground state theory of a one dimensional quantum Fermi liquid and the existence of quasi periodic motions in class

G. Perla Menzala, V. V. Konotop

We prove global existence and uniqueness of solutions of some important nonlinear lattices which include the Fermi-Pasta-Ulam (FPU) lattice. Our result shows (on a particular example) that the FPU lattice with high nonlinearity and its continuum limit display drastically different behaviour with respect to blow up phenomenon.

S. I. Simdyankin, S. N. Taraskin, M. Dzugutov, S. R. Elliott

A structural model of a one-component $σ$-phase crystal has been constructed by means of molecular dynamics simulation. The phonon dispersion curves and the vibrational density of states were computed for this model. The dependence of the vibrational properties on the thermodynamical parameters was investigated. The vibrational density of states of the $σ$-p

Vladislav Popkov, Gunter M. Schuetz

We investigate the stationary states of one-dimensional driven diffusive systems, coupled to boundary reservoirs with fixed particle densities. We argue that the generic phase diagram is governed by an extremal principle for the macroscopic current irrespective of the local dynamics. In particular, we predict a minimal current phase for systems with local mi

P. Szabo, P. Samuely, A. G. M. Jansen, J. Marcus

The de Gennes and Maki theory of gapless superconductivity for dirty superconductors is used to interpret the tunneling measurements on the strongly type-II high-Tc oxide-superconductor Ba1-xKxBiO3 in high magnetic fields up to 30 Tesla. We show that this theory is applicable at all temperatures and in a wide range of magnetic fields starting from 50 percent

C. Panagopoulos, B. D. Rainford, J. R. Cooper, C. A. Scott

We have performed muon spin relaxation and low field ac-susceptibility measurements in a series of high quality samples of La_{2-x}Sr_xCuO_4 (x=0.08-0.24) as a function of temperature. Superconductivity is found to coexist with low temperature spin glass order up to the optimally doped region where the normal state pseudogap also closes. The systematic deple

Josep Bonet Avalos, Allan D. Mackie

Simulation results of the thermal conductivity ${\cal L}$ of Dissipative Particle Dynamics model with Energy Conservation (DPDE) are reported. We also present an analysis of the transport equations and the transport coefficients for DPDE based on a local equilibrium approximation. This approach is valid when the particle-particle thermal conductivity $λ$ and

Allan D. Mackie, Josep Bonet Avalos

The stochastic differential equations for a model of dissipative particle dynamics, with both total energy and total momentum conservation at every time-step, are presented. The algorithm satisfies detailed balance as well as the fluctuation-dissipation theorems that ensure that the proper thermodynamic equilibrium can be reached. Macroscopic equilibrium pro

Bambi Hu, Baowen Li, Peiqing Tong

The propagation of an initially localized excitation in one dimensional incommensurate, quasiperiodic and random systems is investigated numerically. It is discovered that the time evolution of variances $σ^2(t)$ of atom displacements depends on the initial condition. For the initial condition with nonzero momentum, $σ^2(t)$ goes as $t^α$ with $α=1$ and 0 fo

Chung-Yu Mou, Tzay-ming Hong

The effective Hamiltonian for two dimensional quantum wells with rough interfaces is formally derived. Two new terms are generated. The first term is identified to the local energy level fluctuations, which was introduced phenomenologically in the literature for interface roughness scattering but is now shown to be valid only for an infinite potential well o

W. J. Zheng

The stripe phase in high Tc cuprates is modeled as a single stripe coupled to the RVB spin liquid background by the single particle hopping process. In normal state, the strong pairing correlation inherent in RVB state is thus transfered into the Luttinger stripe and drives it toward spin-gap formation described by Luther-Emery Model. The establishment of gl

Hyun C. Lee, S. -R. Eric Yang

Two one-dimensional Luttinger liquid systems coupled by Hund&#39;s coupling are studied by the renormalization group and the non-abelian bosonization methods. It is found that the Hund&#39;s coupling is always relevant irrespective of the repulsive interaction between electrons within each chain. The properties of the resulting strong coupling fixed point ar

B. Novosyadlyj, R. Durrer, S. Gottloeber, V. N. Lukash

The possibility of determining cosmological parameters on the basis of a wide set of observational data including the Abell-ACO cluster power spectrum and mass function, peculiar velocities of galaxies, the distribution of Ly-$α$ clouds and CMB temperature fluctuations is analyzed. Using a $χ^2$ minimization method, assuming $Ω_Λ+Ω_{\rm{matter}} =1 $ and no

Emilios T. Harlaftis, Alexei V. Filippenko

The advent of the large effective apertures of the Keck telescopes has resulted in the determination with unprecedented accuracy of the mass functions and mass ratios of faint (R ~ 21 mag) X-ray transients (GS 2000+25, GRO J0422+32, Nova Oph 1977, Nova Vel 1993), as well as constraining the main-sequence companion star parameters and producing images of the

M. A. Gurwell, D. O. Muhleman

We report new interferometric observations of the CO (2-1) rotational transition on Titan. We find that the spectrum is best fit by a uniform profile of 52 ppm, with estimated errors of 6 ppm (40 to 200 km) and 12 ppm (200 to 300 km).

Stefi A. Baum, Patrick J. McCarthy

We present the results of an analysis of the large scale velocity fields of the ionized gas associated with powerful radio galaxies. Long-slit spectra of 52 objects provide a sample of resolved velocities that span a wide range of redshifts, radio and emission-line luminosities. Line widths reaching 1000 km/s and resolved velocity fields with amplitudes of u

W. J. Percival, L. Miller, J. A. Peacock

In this paper we describe the Bayesian link between the cosmological mass function and the distribution of times at which isolated halos of a given mass exist. By assuming that clumps of dark matter undergo monotonic growth on the time-scales of interest, this distribution of times is also the distribution of `creation&#39; times of the halos. This monotonic

D. Matthew Scott, Denis A. Leahy, Robert B. Wilson

Ginga and Rossi X-ray Timing Explorer (RXTE) observations have allowed an unprecedented view of the recurrent systematic pulse shape changes associated with the 35-day cycle of Hercules X-1, a phenomenon currently unique among the known accretion-powered pulsars. We present observations of the pulse shape evolution. An explanation for the pulse evolution in

Dimitri Bourilkov

We present first preliminary data from the L3+Cosmics experiment and results from Monte Carlo simulations of multi-muon events as observed 30 m underground.

M. A. T. Groenewegen, R. D. Oudmaijer

We analyse a sample of 236 Cepheids from the Hipparcos catalog, using the method of ``reduced parallaxes&#39;&#39; in V, I, K and the reddening-free ``Wesenheit-index&#39;&#39;. We compare our sample to those considered by Feast & Catchpole (1997) and Lanoix et al. (1999). We stress the importance of two systematic effects which influence the distance to the

Frits Paerels, Jean Cottam, Masao Sako, Duane A. Liedahl

We present a preliminary analysis of the 1--10 keV spectrum of the massive X-ray binary Cyg X-3, obtained with the High Energy Transmission Grating Spectrometer on the Chandra X-ray Observatory. The source reveals a richly detailed discrete emission spectrum, with clear signatures of photoionization-driven excitation. Among the spectroscopic novelties in the

Inseok Song, J. -P. Caillault, David Barrado y Navascues, John Stauffer

We have estimated the ages of eight late-type Vega-like stars by using standard age dating methods for single late-type stars, e.g., location on the color magnitude diagram, Li 6708 angstrom absorption, CaII H&K emission, X-ray luminosity, and stellar kinematic population. With the exception of the very unusual pre-main sequence star system HD 98800, all the

A. J. Leonardi, G. Worthey

Two absorption line indices, Ca II and Hdelta/FeI4045, measured from high resolution spectra are used with evolutionary synthesis models to verify the presence of a young stellar population in NGC 5018. The derived age of this population is about ~2.8 Gyr with a metallicity roughly solar and it completely dominates the integrated light of the galaxy near 400

Robert Braun, W. Butler Burton

A distinct sub-class of anomalous velocity HI emission features has emerged from recent high quality surveys of the Local Group environment, namely the compact high velocity clouds (CHVCs). A program of high-resolution imaging with the Westerbork array and the Arecibo telescope has begun to provide many insights into the nature of these objects. Elongated co

Delphine Porquet, Jacques Dubau

We present He-like line ratios (resonance, intercombination and forbidden lines) for totally and partially photoionized media. For solar plasmas, these line ratios are already widely used for density and temperature diagnostics of coronal (collisional) plasmas. In the case of totally and partially photoionized plasmas, He-like line ratios allow for the deter

Manami Sasaki, Frank Haberl, Wolfgang Pietsch

All 543 pointed observations of the ROSAT High Resolution Imager (HRI) with exposure times higher than 50 sec in a field of 10 deg x 10 deg covering the Large Magellanic Cloud (LMC) were analyzed. A catalogue was produced containing 397 X-ray sources with their properties measured by the HRI. The list was cross-correlated with the ROSAT Position Sensitive Pr

F. Mayet

The Alpha Magnetic Spectrometer (AMS) was flown in june 1998 on board of the space shuttle Discovery (flight STS-91) at an altitude ranging between 320 and 390 km. This preliminary version of AMS included an Aerogel Threshold Cherenkov detector (ATC) to separate antiprotons from electron background, for momenta less than 3.5 GeV/c. In this paper, the design

Naoki Seto

Smoothing operation to make continuous density field from observed point-like distribution of galaxies is crucially important for topological or morphological analysis of the large-scale structure, such as, the genus statistics or the area statistics (equivalently the level crossing statistics). It has been pointed out that the adaptive smoothing filters are

M. Amenomori

In 1997, the BL Lac Object Mrk 501 entered a very active phase and was the brightest source in the sky at TeV energies, showing strong and frequent flaring. Using the data obtained with a high density air shower array that has been operating successfully at Yangbajing in Tibet since 1996, we searched for gamma-ray signals from this source during the period f

R. F. Mushotzky, L. L. Cowie, A. J. Barger, K. A. Arnaud

The origin of the hard (2-10 keV) X-ray background has remained mysterious for over 35 years. Most of the soft (0.5-2 keV) X-ray background has been resolved into discrete sources, which are primarily quasars; however, these sources do not have the flat spectral shape required to match the X-ray background spectrum. Here we report the results of an X-ray sur

V. Avila-Reese, C. Firmani

We propose and show that the dependence of the internal face-on dust absorption upon B-band luminosity reported by Wang & Heckman (1996) for a sample of late-type galaxies may explain the empirical color-magnitude and color Tully-Fisher relations of disk galaxies. Thus, in order to explain these relations, it is not necessary to evoke star formation and gas