May 1998 arXiv papers — page 2

Gerhard Ecker

Broken chiral symmetry has become the basis for a unified treatment of hadronic interactions at low energies. After reviewing mechanisms for spontaneous chiral symmetry breaking, I outline the construction of the low--energy effective field theory of the Standard Model called chiral perturbation theory. The loop expansion and the renormalization procedure fo

Luis M. A. Bettencourt, C. Wetterich

The time evolution of the correlation functions of an ensemble of anharmonic N-component oscillators with O(N) symmetry is described by a flow equation, exact up to corrections of order $1/N^2$. We find effective irreversibility. Nevertheless, analytical and numerical investigation reveals that the system does not reach thermal equilibrium for large times, e

Maarten F. L. Golterman, Ka Chun Leung

We use one-loop chiral perturbation theory to compare potential lattice computations of the K+ --> pi+ pi0 decay amplitude at m_K=2m_pi with the experimental value. We find that the combined one-loop effect due to this unphysical pion to kaon mass ratio and typical finite volume effects is still of order minus 20-30%, and appears to dominate the effects from

Daniel Kennefick

We examine the evolution, under gravitational radiation reaction, of slightly eccentric equatorial orbits of point particles around Kerr black holes. Our method involves numerical integration of the Sasaki-Nakamura equation. It is discovered that such orbits decrease in eccentricity throughout most of the inspiral, until shortly before the innermost stable c

Mauricio Barahona, Steven H. Strogatz

Using the lumped circuit equations, we derive a stability criterion for superconducting pinned states in two-dimensional arrays of Josephson junctions. The analysis neglects quantum, thermal, and inductive effects, but allows disordered junctions, arbitrary network connectivity, and arbitrary spatial patterns of applied magnetic flux and DC current injection

David Pettey, T. C. Lubensky, Darren Link

In thin films of smectic-C liquid crystals, localized regions containing additional smectic layers form circular inclusions that carry a topological charge. Such inclusions nucleate a companion topological defect. These inclusion-defect pairs are modeled as topological dipoles within the context of a one-coupling constant approximation to the 2D Frank free e

Daniel P. Arovas, Guillermo Gomez-Santos, Francisco Guinea

Ferromagnetic systems described by the double exchange model are investigated. At temperatures close to the Curie temperature, and for a wide range of doping levels, the system is unstable toward phase separation. The chemical potential decreases upon increasing doping, due to the significant dependence of the bandwidth on the number of carriers. The reducti

Frantisek Slanina

We investigate a simple model of dry friction based on extremal dynamics of asperities. At small velocities, correlations develop between the asperities, whose range becomes infinite in the limit of infinitely slow driving, where the system is self-organized critical. This collective phenomenon leads to effective aging of the asperities and results in veloci

Y. -K. Yu, P. L. Taylor, E. M. Terentjev

Lattice Monte-Carlo simulations were performed to study the equilibrium ordering in a two-dimensional nematic system with quenched random disorder. When the disordering field, which competes against the aligning effect of the Frank elasticity, is sufficiently strong, the long-range correlation of the director orientation is found to decay as a simple exponen

J. Christian Schoen, Paolo Sibani

We investigate the energy landscape of two dimensional network models for covalent glasses by means of the lid algorithm. For three different particle densities and for a range of network sizes, we exhaustively analyse many configuration space regions enclosing deep-lying energy minima. We extract the local densities of states and of minima, and the number o

Dirk Helbing

The game dynamical equations are derived from Boltzmann-like equations for individual pair interactions by assuming a certain kind of imitation behavior, the so-called proportional imitation rule. They can be extended to a stochastic formulation of evolutionary game theory which allows the derivation of approximate and corrected mean value and covariance equ

T. Hjelt, S. Herminghaus, T. Ala-Nissila, S. C. Ying

We consider the diffusion and spreading of chainlike molecules on solid surfaces. We first show that the steep spherical cap shape density profiles, observed in some submonolayer experiments on spreading polymer films, imply that the collective diffusion coefficient $D_C(θ)$ must be an increasing function of the surface coverage $θ$ for small and intermediat

D. H. E. Gross

Microcanonical thermodynamics (MCTh) is contrasted to canonical thermodynamics (CTh). At phase transitions of 1.order the two ensembles are NOT equivalent even in the thermodynamic limit . Energy fluctuations do not vanish and phase separations are suppressed in CTh. A proper treatment of fluctuations is neccessary. MCTh allows to address even isolated small

Sergei Sergeenkov

The thermoelectric response of SND configuration is considered within the generalized Ginzburg-Landau theory for a homogeneous admixture of s-wave and d-wave superconductors. The resulting thermopower (TP) is found to strongly depend on the relative phase θ=ϕ_s-ϕ_d between the two superconductors. Two independent mechanisms are shown to contribute to the TP.

David A. Schneider, Kathleen F. McCoy

This paper reports on the recognition component of an intelligent tutoring system that is designed to help foreign language speakers learn standard English. The system models the grammar of the learner, with this instantiation of the system tailored to signers of American Sign Language (ASL). We discuss the theoretical motivations for the system, various dif

Karen Sparck Jones

This position paper suggests that progress with automatic summarising demands a better research methodology and a carefully focussed research strategy. In order to develop effective procedures it is necessary to identify and respond to the context factors, i.e. input, purpose, and output factors, that bear on summarising and its evaluation. The paper analyse

Barron Koralesky, D. A. Frail, W. M. Goss, M. J. Claussen

We present the results of VLA observations in the ground-state hydroxyl (OH) transition at 1720 MHz toward 20 supernova remnants (SNRs). We detect compact emission from four objects. For three of these objects (G32.8-0.1, G337.8-0.1, and G346.6-0.2), we argue that the emission results from masers which are shock-excited due to the interaction of the SNR and

Sergey A. Silich, Guillermo Tenorio-Tagle

Two dimensional calculations of the evolution of remnants generated by the strong mechanical energy deposited by stellar clusters in dwarf galaxies (M \si $10^9 - 10^{10}$ \msun) are presented. The evolution is followed for times longer than both the blowout time and the presumed span of energy injection generated by a coeval massive stellar cluster. The rem

Steinn Sigurdsson, Chris Mihos, Lars Hernquist, Colin Norman

We present $N$--body models for triaxial elliptical galaxies or halos of galaxies, which are fully self--gravitating, have near constant axis ratio as a function of radius and a $r^{-1}$ central density cusp. Preliminary investigation suggests the model are stable and orbit analysis shows no indication of chaotic orbits. The models provide a starting point f

Eduardo Telles, Steve Maddox

We address the question of whether violent star formation in HII galaxies is induced by low mass companions by describing statistically their local environment as estimated by the correlation function. We argue that even if low mass companions were mainly intergalactic HI clouds, their optical counterparts should be detectable at faint limits of the Automati

Torsten A. Ensslin, Peter L. Biermann, Ulrich Klein, Sven Kohle

Simulations of structure formation in the Universe predict accretion shock waves at the boundaries of the large-scale structures as sheets, filaments, and clusters of galaxies. If magnetic fields are present at these shocks, particle acceleration should take place, and could contribute to the observed cosmic rays of high energies. When the radio plasma of an

B. Paul, A. R. Rao

We report the discovery of low frequency quasi-periodic oscillations centered at 0.11 Hz in the newly discovered 221 s X-ray pulsar XTE J1858+034. Among about 30 known transient X-ray pulsars this is the sixth source in which QPOs have been observed. If the QPOs are produced because of inhomogeneities in the accretion disk at the magnetospheric boundary, the

Laura Ferrarese, Fabio Bresolin, Robert C. Kennicutt,, Abhijit Saha

We report the detection of Cepheids and a new distance to the spiral galaxy NGC 2541, based on data obtained with the Wide Field and Planetary Camera 2 on board the Hubble Space Telescope (HST). A total of 25 exposures (divided into 13 epochs) are obtained using the F555W filter (transformed to Johnson V), and nine exposures (divided into five epochs) using

L. Pasquini, T. Belloni

We present optical identification and high-resolution spectroscopy of ROSAT sources in the field of the old open cluster M 67. For the first time it is possible to analyze coronal and chromospheric activity of active stars in a solar-age cluster, and to compare it with field stars. ROSAT observed the high X-ray luminosity tail of the cluster sources. In agre

Michael Harvanek, Martin J. Hardcastle

We present VLA radio maps in total intensity and polarization at 1.4, 4.9 and 8.4 GHz of fifteen 3CR radio galaxies for which good maps showing the large-scale radio structure have not previously been available. Previously unknown cores are detected in several sources and a bright one-sided jet in 3C 287.1 is mapped for the first time; several other jet-like

Paul P. van der Werf

This review discusses the current status of our knowledge of emission by dust and molecular gas in high redshift radio galaxies, and the uncertainties in the derivation of physical parameters from these data. The similarity of far-infrared luminous, gas-rich high redshift radio galaxies and local ultraluminous infrared galaxies (ULIGs) is discussed. Given th

Puragra Guhathakurta, Zodiac T. Webster, Brian Yanny, Donald P. Schneider

We present F555W (V), F439W (B), and F336W (U) photometry of 9507 stars in the central 2' of the dense, post core collapse cluster M30 (NGC 7099) derived from HST WFPC2 images. These data are used to study the mix of stellar populations in the central region of the cluster. Forty eight blue straggler stars are identified and are found to be strongly conc

Finn Larsen

The near horizon geometry of four-dimensional black holes in the dilute gas regime is AdS_3 x S^2, and the global symmetry group is SU(2) x USp(6). This is exploited to calculate their perturbation spectrum using group theoretical methods. The result is interpreted in terms of three extreme M5-branes, orthogonally intersecting over a common string. We also c

Sudip Chakravarty, Steven Kivelson, Chetan Nayak, Klaus Voelker

Recent experiments on the two dimensional electron gas in various semiconductor devices have revealed an unexpected metal-insulator transition and have challenged the previously held assumption that there is no such transition in two dimensions. While the experiments are still at the stage of rapid development, it is becoming evident that they cannot be unde

Gary T. Horowitz, Donald Marolf

We discuss quotients of Anti-de Sitter (AdS) spacetime by a discrete group in light of the AdS-CFT correspondence. Some quotients describe closed universes which expand from zero volume to a maximum size and then contract. Maldacena's conjecture suggests that they should be represented in string theory by suitable quotients of the boundary conformal field th

Paul S. Aspinwall, David R. Morrison

We consider the F-theory description of non-simply-connected gauge groups appearing in the E8 x E8 heterotic string. The analysis is closely tied to the arithmetic of torsion points on an elliptic curve. The general form of the corresponding elliptic fibration is given for all finite subgroups of E8 which are applicable in this context. We also study the clo

Saumen Datta, R. V. gavai

This paper is being withdrawn as its main results are already included in section 2 of the paper hep-lat/9901006.

Hans A. Bethe, G. E. Brown

We consider the merging of high-mass black-hole binaries of the Cyg X-1 type, in which the O-star companion becomes a neutron star following a supernova explosion. Our estimated rate of mergers, $\sim 2\times 10^{-5} yr^{-1}$ for the Galaxy, is relatively low because of the paucity of high-mass black holes. None the less, because of their high masses, these

Belal E. Baaquie

Lagrangians for gauge fields and matter fields can be constructed from the infinite dimensional Kac-Moody algebra and group. A continuum regularization is used to obtain such generic lagrangians, which contain new nonlinear and asymmetric interactions not present in gauge theories based on compact Lie groups. This technique is applied to deriving the Yang-Mi

Satya N. Majumdar, Alan J. Bray

We introduce a parameter $p$, called partial survival, in the persistence of stochastic processes and show that for smooth processes the persistence exponent $θ(p)$ changes continuously with $p$, $θ(0)$ being the usual persistence exponent. We compute $θ(p)$ exactly for a one-dimensional deterministic coarsening model, and approximately for the diffusion equ

Mordehai Milgrom

Why does there appear in the modified dynamics (MOND) an acceleration constant, a0, of cosmological significance? An intriguing possibility is that MOND, indeed inertia itself--as embodied in the actions of free particles and fields, is due to effects of the vacuum. Either cosmology enters local dynamics by affecting the vacuum, and inertia in turn, through

A. Sevostyanov

In this paper we study the Poisson-Lie version of the Drinfeld-Sokolov reduction defined in q-alg/9704011, q-alg/9702016. Using the bialgebra structure related to the new Drinfeld realization of affine quantum groups we describe reduction in terms of constraints. This realization of reduction admits direct quantization. As a byproduct we obtain an explicit e

Bastian Bergerhoff

We discuss the universal critical behavior of a selfinteracting scalar field theory at finite temperature as obtained from approximate solutions to nonperturbative renormalization group (RG) equations. We employ a formulation of the RG-equations in real-time formalism which is particularly well suited for a discussion of the thermal behavior of theories whic

A. Sevostyanov

We obtain a family of new combinatorial identities for symmetric formal power series.

A. Sevostyanov

We propose a method for reduction of quantum systems with arbitrary first class constraints. An appropriate mathematical setting for the problem is homology of associative algebras. For every such an algebra $A$ and its subalgebra B with an augmentation e there exists a cohomological complex which is a generalization of the BRST one. Its cohomology is an ass

J. Podolsky

Gravitational waves which are smooth and contain two asymptotically flat regions are constructed from the homogeneous pp-waves vacuum solution. Motion of free test particles is calculated explicitly and the limit to an impulsive wave is also considered.

Yu Shi

This paper has been superseded by quant-ph/9908074.

R. A. M. J. Wijers, T. J. Galama

We have calculated synchrotron spectra of relativistic blast waves, and find predicted characteristic frequencies that are more than an order of magnitude different from previous calculations. For the case of an adiabatically expanding blast wave, which is applicable to observed gamma-ray burst (GRB) afterglows at late times, we give expressions to infer the

S. Roche

Quantum transport for different systems is investigated by developing the Kubo formula on a basis of orthogonal polynomials. Results on quantum Hall systems are presented with particular attention to metal insulator transitions and new universalities. Other potential applications of the present method for RKKY mesoscopic interaction and insight for large sca

Greg L. Bryan, Marie Machacek, Peter Anninos, Michael L. Norman

In this paper we critically examine predictions of the Lya forest within the standard cold dark matter (SCDM) model, paying particular attention to the low end of the column-density distribution. We show in particular that the width of these lines, typically measured by the b-parameter of a Voigt profile, is sensitive to spatial resolution in numerical simul

Siang Peng Oh, David N. Spergel, Gary Hinshaw

There is enormous potential to advance cosmology from statistical characterizations of cosmic microwave background sky maps. The angular power spectrum of the microwave anisotropy is a particularly important statistic. Existing algorithms for computing the angular power spectrum of a pixelized map typically require O(N^3) operations and O(N^2) storage, where

Micho Durdevich, Hanna E. Makaruk, Robert Owczarek

A generalization of the results of Rasetti and Zanardi concerning avoiding errors in quantum computers by using states preserved by evolution is presented. The concept of dynamical symmetry is generalized from the level of classical Lie algebras and groups to the level of dynamical symmetry based on quantum Lie algebras and quantum groups (in the sense of Wo

B. Piraux, R. M. Potvliege

The probability that an atom of hydrogen, initially in the 5g(m=4) state, survives a 90-fs pulse of 620 nm wavelength is calculated both by direct integration of the time-dependent Schroedinger equation and by a Floquet calculation. The two methods give virtually identical results. The survival probability calculated for a one-electron model of neon, for the

G. Q. Li, C. Gale

Through the analysis of HELIOS-3 data obtained at the CERN SPS, we demonstrate the importance of secondary processes for dilepton production in heavy-ion collisions in the intermediate invariant mass region. We find that while the dilepton spectra between 1 to 2.5 GeV from proton-induced reactions can be attributed to the decay of primary vector mesons, char

Alexander Krasulin

In this part of the series five-dimensional tangent vectors are introduced first as equivalence classes of parametrized curves and then as differential-algebraic operators that act on scalar functions. I then examine their basic algebraic properties and their parallel transport in the particular case where space-time possesses a special local symmetry. After

J. Hausen, P. Heinzner

Let K be a compact Lie group and G its complexification. For a not necessarily reduced Stein K-space X we show that there is a complex space Z endowed with a holomorphic action of the universal complexification G of K that contains X as an open K-stable subset. The correspondence is functorial. As our main result we prove that every coherent K-sheaf on X ext

Doron Zeilberger

It is remarked that Dave Robbins's Expression for the integral of an alternant over the unit simplex (math.CO/9805108) follows immediately from an excercise in Polya-Szego.

Richard E. Borcherds, E. Freitag, R. Weissauer

The theta series of the two unimodular even positive definite lattices of rank 16 are known to be linearly dependent in degree at most 3 and linearly independent in degree 4. In this paper we consider the next case of the 24 Niemeier lattices of rank 24. The associated theta series are linearly dependent in degree at most 11 and linearly independent in degre

Konrad Schmuedgen

A class of well-behaved *-representations of a q-deformed Heisenberg algebra is studied and classified.

R. Debalme

Our goal here is to give a simple proof of the non integrable version of Brody's characterisation theorem.

Qing Zhou

Let $Σ$ be a hyperbolic link with $m$ components in a 3-dimensional manifold $X$. In this paper, we will show that the moduli space of marked hyperbolic cone structures on the pair $(X, Σ)$ with all cone angle less than $2π/3$ is an $m$-dimensional open cube, parameterized naturally by the $m$ cone angles. As a corollary, we will give a proof of a special ca

S. Deser

I discuss two novel results in D=11 Supergravity. The first establishes, in two complementary ways, a no-go theorem that, in contrast to all D<11, a cosmological extension of the theory does not exist. The second deals with the structure of (on-shell) four-point invariants. These are important both for establishing existence of the lowest (2-loop) order cand

J. Barcelos-Neto, Ashok Das

We study the 0+1 dimensional Chern-Simons theory at finite temperature within the framework of derivative expansion. We obtain various interesting relations, solve the theory within this framework and argue that the derivative expansion is not a suitable formalism for a study of the question of large gauge invariance.

Thomas C. Kraan, Pierre van Baal

We discuss the newly found exact instanton solutions at finite temperature with a non-trivial Polyakov loop at infinity. They can be described in terms of monopole constituents and we discuss in this context an old result due to Taubes how to make out of monopoles non-trivial topological charge configurations, with possible applications to abelian projection

Laurent Baulieu, Peter West

We describe a generalization of Yang--Mills topological field theory for Abelian two-forms in six dimensions. The connection of this theory by a twist to Poincaré supersymmetric theories is given. We also briefly consider interactions and the case of self-dual three-forms in eight dimensions.

N. Dragon, U. Theis

We derive consistent superfield constraints for the linear vector-tensor multiplet with gauged central charge. The central charge transformations and the action turn out to be nonpolynomial in the gauge field.

Xu-Dong Luo, Xing-Chang Song, Shi-Kun Wang, Ke Wu

A quantum dynamical $\check{R}$-matrix with spectral parameter is constructed by fusion procedure. This spin-1 $\check{R}$-matrix is connected with Lie algebra $so(3)$ and does not satisfy the condition of translation invariance.

S. Pratik Khastgir

The exact quantum $S$-matrices and conserved charges are known for affine Toda field theories(ATFTs). In this note we report on a new type of bi-linear sum rules of conserved quantities derived from these exact $S$ matrices. They exist when there is a multiplicative identity among $S$-matrices of a particular ATFT. Our results are valid for simply laced as w

Michael Bershadsky, Tony Pantev, Vladimir Sadov

We present evidence that the CHL string in eight dimensions is dual to F-theory compactified on an elliptic K3 with a $Γ_{0}(2)$ monodromy group. The monodromy group $Γ_{0}(2)$ allows one to turn on the flux of an antisymmetric two form along the base. The $B_{μν}$ flux is quantized and therefore the moduli space of the CHL string is disconnected from the mo

K. Goulianos, J. Montanha

In standard Regge theory with a pomeron intercept a(0)=1+ε, the contribution of the tripe-pomeron amplitude to the t=0 differential cross section for single diffraction dissociation has the form dσ/dM^2(t=0) \sim s^{2ε}/(M^2)^{1+ε}. For ε>0, this form, which is based on factorization, does not scale with energy. From an analysis of p-p and p-pbar data from f

M. Burkardt, H. El-Khozondar

In the light-front formulation of field theory, it is possible to write down a chirally invariant mass term. It thus appears as if one could solve the species doubling problem on a light-front quantized transverse lattice in a chirally invariant way. However, upon introducing link fields and after renormalizing, one finds exactly the same LF Hamiltonian as i

A. Leike

The phenomenological constraints on extra neutral gauge bosons at present and at future colliders are reviewed. Special attention is paid to the influence of radiative corrections, systematic errors, and kinematic cuts on the Z&#39; constraints. Simple estimates of the Z&#39; constraints from different reactions are derived. They make the physical origin of

A. Ringwald, F. Schrempp

A ``fiducial&#39;&#39; kinematical region for our calculations of instanton (I)-induced processes at HERA within I-perturbation theory is extracted from recent lattice simulations of QCD. Moreover, we present the finalized I-induced cross-sections exhibiting a strongly reduced residual dependence on the renormalization scale.

Elena N. Bukina, Vladimir M. Dubovik, Valentin E. Kuznetsov

We discuss the transition radiation of a neutrino induced by its toroid dipole moment ($τ$) when crossing the interface between two different media with different refraction indices. A neutrino of 1 MeV energy emits approximately $10^{-40}$ keV at $τ=e\sqrt{2}G_F/π^2$. This effect depends very slightly on the neutrino mass and has a finite value in the massl

M. Heyssler, V. A. Khoze, W. J. Stirling

Hadronic radiation provides a tool to distinguish different topologies of colour flow in hard scattering processes. We study the structure of hadronic flow corresponding to Higgs production and decay in high-energy hadron-hadron collisions. In particular, the signal gg -> H -> b anti-b and background gg -> b anti-b processes are shown to have very different

B. Bunk

The fractional inverse $M^{-γ}$ (real $γ>0$) of a matrix $M$ is expanded in a series of Gegenbauer polynomials. If the spectrum of $M$ is confined to an ellipse not including the origin, convergence is exponential, with the same rate as for Chebyshev inversion. The approximants can be improved recursively and lead to an iterative solver for $M^γx = b$ in Kry

CDF Collaboration, F. Abe et. al

We have observed bottom-charm mesons B_c via the decay mode Bc -> J/psi lepton neutrino in 1.8 TeV p-bar p collisions using the CDF detector at the Fermilab Tevatron. A fit of background and signal contributions to the J/psi + lepton mass distribution yielded 20.4 +6.2 -5.5 events from B_c mesons. A fit to the same distribution with background alone was reje

M. S. Alam

The CLEOII detector at the Cornell e+ e- storage ring CESR has been used to search for the two-photon production of the $f_J(2220)$ decaying into pi+ pi-. No evidence for a signal is found in data corresponding to an integrated luminosity of 4.77/fb and a 95% CL upper limit on $Γ_{two-photon} * BR{pi+ pi-}$ of 2.5 eV is set. If this result is combined with t

Karen Camarda, Edward Seidel

We consider the numerical evolution of black hole initial data sets, consisting of single black holes distorted by strong gravitational waves, with a full 3D, nonlinear evolution code. These data sets mimic the late stages of coalescing black holes. We compare various aspects of the evolution of axisymmetric initial data sets, obtained with this 3D code, to

Amso Harpaz, Noam Soker

The emission of radiation by a uniformly accelerated charge is analyzed. According to the standard approach, a radiation is observed whenever there is a relative acceleraion between the charge and the observer. Analyzing difficulties that arose in the standard approach, we propose that a radaition is created whenever a relative acceleration between the charg

E. Sorensen, I. Affleck, D. Augier, D. Poilblanc

A simple intuitive picture of spin-Peierls antiferromagnets arises from regarding the elementary excitations as S=1/2 solitons. In a strictly one-dimensional system these excitations are assumed not to form bound-states and to be repelled by impurities. Couplings to the three-dimensional lattice are assumed to produce an effective confining potential which b

S. Redner, P. L. Krapivsky

We investigate the zero-temperature coarsening dynamics of a chain of Ising spins with a nearest-neighbor ferromagnetic and an nth-neighbor antiferromagnetic interactions. For sufficiently large antiferromagnetic interaction, the ground state consists of $n$ consecutive up spins followed by n down spins, etc. We show that the asymptotic coarsening into this

Dirk Helbing

It is shown, that the Boltzmann-like equations allow the formulation of a very general model for behavioral changes. This model takes into account spontaneous (or externally induced) behavioral changes and behavioral changes by pair interactions. As most important social pair interactions imitative and avoidance processes are distinguished. The resulting mod

S. M. Clarke, E. M. Terentjev

Randomly disordered (polydomain) liquid crystalline elastomers align under stress. We study the dynamics of stress relaxation before, during and after the Polydomain-Monodomain transition. The results for different materials show the universal ultra-slow logarithmic behaviour, especially pronounced in the region of the transition. The data is approximated ve

Christian M. Dury, Gerald H. Ristow

Using discrete element methods, we study numerically the dynamics of the size segregation process of binary particle mixtures in three-dimensional rotating drums, operated in the continuous flow regime. Particle rotations are included and we focus on different volume filling fractions of the drum to study the interplay between the competing phenomena of mixi

F. Brosens, J. T. Devreese, L. F. Lemmens

For a fermion gas with equally spaced energy levels, the density and the pair correlation function are obtained. The derivation is based on the path integral approach for identical particles and the inversion of the generating functions for both static responses. The density and the pair correlation function are evaluated explicitly in the ground state of a

V. M. Krasnov, N. Mros, A. Yurgens, D. Winkler

Modulation of the critical current across layers, Ic(H), of stacked Josephson junctions (SJJs) as a function of an applied magnetic field parallel to the junction planes is studied theoretically and experimentally for different junction lengths and coupling parameters. It is shown that the Ic(H) patterns of long SJJs are very complicated without periodicity

A. L. Korzhenevskii, K. Herrmanns, H. -O. Heuer

Real crystals almost unavoidably contain a finite density of dislocations. We show that this generic type of long--range correlated disorder leads to a breakdown of the conventional scenario of critical behavior and standard renormalization group techniques based on the existence of a simple, homogeneous ground state. This breakdown is due to the appearance

K. Maisinger, U. Schollwoeck, S. Brehmer, H. J. Mikeska

We investigate the specific heat and magnetisation of a ferrimagnet with gS=1 and S=1/2 spins in a finite magnetic field using the transfer matrix DMRG down to T=0.025J. Ferromagnetic gapless and antiferromagnetic gapped excitations for H=0 lead to rich thermodynamics for H > 0. While the specific heat is characterized by a generic double peak structure, mag

F. J. Garcia-Vidal, J. M. Pitarke, J. B. Pendry

We analyse from a theoretical point of view the optical properties of arrays of carbon nanotubes filled with silver. Dependence of these properties on the different parameters involved is studied using a Transfer Matrix formalism able to work with tensor-like dielectric functions and including the full electromagnetic coupling between the nanotubes. We find

A. Weisse, G. Bouzerar, H. Fehske

In the past different models for the magnetic salt vanadyl pyrophosphate (VOPO) were discussed. Neither a spin ladder nor an alternating chain are capable to describe recently measured magnetic excitations. In this paper we propose a 2D model that fits better to experimental observations.

P. Hebraud, F. Lequeux

In this paper, we introduce a simple mode-coupling model for concentrated suspensions under flow . This model exhibits a jamming transition, and stress vs shear rate relations which are very similar to experimental results. Namely newtonian regime or yield stress are followed by a slow variation of the stress for higher shear rates, and by an apparent newton

W. Selke, M. Bisani

The dynamics of steps on crystal surfaces is considered. In general, the meandering of the steps obeys a subdiffusive behaviour. The characteristic asymptotic time laws depend on the microscopic mechanism for detachment and attachment of the atoms at the steps. The three limiting cases of step-edge diffusion, evaporation-condensation and terrace diffusion ar

Oleg Derzhko, Taras Krokhmalskii

We have considered a numerical scheme for the calculation of the equilibrium properties of spin-1/2 XY chains. Within its frames it is necessary to solve in the last resort only the 2N\times 2N eigenvalue and eigenvector problem but not the 2^N\times 2^N one as for an arbitrary system consisting of N spins 1/2. To illustrate the approach we have presented so

Sergei Sergeenkov

The change of the Josephson supercurrent density of a weakly-connected granular superconductor in response to externally applied arbitrary thermal gradient dT/dx (nonlinear Seebeck effect) is considered within a model of 3D Josephson junction arrays. For dT/dx>(dT/dx)_c, where (dT/dx)_c is estimated to be of the order of 10^4 K/m for YBCO ceramics with an av

M. W. Pieper, F. Wiekhorst, T. Wolf

We investigated the type of the carriers doped in the CuO$_2$-planes of non-superconducting Pr$_{1+x}$Ba$_{2-x}$Cu$_3$O$_7$ single crystals by nuclear magnetic resonance of Pr and chain-site Cu. The different spectra in the solid solution system show that the holes in Pr-rich crystals are localized in states similar to the ones in stoichiometric samples, tha

Avinash Singh

A self-consistent spin-fluctuation theory is developed to obtain T_N vs. U for the half-filled Hubbard antiferromagnet in the whole U/t range. Good agreement is obtained in the strong coupling limit with the high-temperature series-expansion result for the equivalent Heisenberg model. Quantum, spin-fluctuation correction to the sublattice magnetization is al

Terrence Harvey, Sandra Carberry

Our experience with a critiquing system shows that when the system detects problems with the user&#39;s performance, multiple critiques are often produced. Analysis of a corpus of actual critiques revealed that even though each individual critique is concise and coherent, the set of critiques as a whole may exhibit several problems that detract from concisen

D. V. Ramana Reddy, A. Sen, G. L. Johnston

We investigate the dynamical behaviour of two limit cycle oscillators that interact with each other via time delayed coupling and find that time delay can lead to amplitude death of the oscillators even if they have the same frequency. We demonstrate that this novel regime of amplitude &#34;death&#34; also exists for large collections of coupled identical os

A. M. Selvam, S. Fadnavis

Atmospheric flows exhibit long-range spatiotemporal correlations manifested as the fractal geometry to the global cloud cover pattern concomitant with inverse power law form for power spectra of temporal fluctuations on all space-time scales ranging from turbulence(centimeters-seconds) to climate(kilometers-years). Long-range spatiotemporal correlations are

Eric Agol, Julian Krolik

MHD turbulence is generally believed to have two important functions in accretion disks: it transports angular momentum outward, and the energy in its shortest wavelength modes is dissipated into the heat that the disks radiate. In this paper we examine a pair of mechanisms which may play an important role in regulating the amplitude and spectrum of this tur

Martin D. Weinberg

An expansion of a density field or particle distribution in basis functions which solve the Poisson equation both provides an easily parallelized n-body force algorithm and simplifies perturbation theories. The expansion converges quickly and provides the highest computational advantage if the lowest-order potential-density pair in the basis looks like the u

A. P. Schoenmakers, K. -H. Mack, L. Lara, H. J. A. Roettgering

We present the results of a detailed analysis of the newly discovered 15 arcmin large FRII-type radio galaxy WNB 0313+683. It has a redshift of 0.0901 +/- 0.0002 and a projected linear size of 2.0 Mpc. Using multi-frequency radio data from the WENSS and NVSS surveys, the VLA, the WSRT and the 100m Effelsberg telescope, we have derived the age of the source (

D. Marsden, D. E. Gruber, W. A. Heindl, M. R. Pelling

We report on the discovery of a new pulsating X-ray source during Rossi X-ray Timing Explorer observations of a low galactic latitude field centered at RA (J2000) = 19 hr 05 m 43 s and Dec (J2000) = +08 deg 58 arcmin 48 arcsec. Significant pulsations were detected by both the PCA and HEXTE instruments aboard RXTE at a fundamental period of 89.17 +/- 0.02 sec

P. Ciliegi, R. G. McMahon, G. Miley, C. Gruppioni

We have used the Very Large Array(VLA) in C configuration to carry out a sensitive 20cm radio survey of regions of sky that have been surveyed in the Far Infra-Red over the wavelength range 5-200 microns with ISO as part of the European Large Area ISO Survey(ELAIS). As usual in surveys based on a relatively small number of overlapping VLA pointings the flux