July 2000 arXiv papers — page 3

Thomas DeGrand

I describe an implementation of the overlap action, which is built from an action which is itself an approximate overlap action. It appears to be about a factor of 15-20 less expensive to use, than the usual overlap action with the Wilson fermion action as its kernel. Ingredients include a fat link to suppress coupling to dislocations and a free field action

V. Azcoiti, A. Galante, V. Laliena

We reanalyze in the first part of this paper the old question of P and CT realization in QCD. The second part is devoted to establish general results on the phase structure of this model in the presence of a $θ$-vacuum term.

Sergio Caracciolo, Andrea Montanari, Andrea Pelissetto

We consider the short-distance behaviour of the product of the Noether O(N) currents in the lattice nonlinear sigma-model. We compare the numerical results with the predictions of the operator product expansion, using one-loop perturbative renormalization-group improved Wilson coefficients. We find that, even on quite small lattices (m a \approx 1/6), the pe

P. R. C. T. Pereira, Anzhong Wang

Cylindrical spacetimes with rotation are studied using the Newmann-Penrose formulas. By studying null geodesic deviations the physical meaning of each component of the Riemann tensor is given. These spacetimes are further extended to include rotating dynamic shells, and the general expression of the surface energy-momentum tensor of the shells is given in te

P. R. C. T. Pereira, Anzhong Wang

The general formulas of a non-rotating dynamic thin shell that connects two arbitrary cylindrical regions are given using Israel's method. As an application of them, the dynamics of a thin shell made of counter-rotating dust particles, which emits both gravitational waves and massless particles when it is expanding or collapsing, is studied. It is found

V. A. Savchenko, T. P. Shestakova, G. M. Vereshkov

Quantum geometrodynamics in extended phase space describes phenomenologically the integrated system ``a physical object + observation means (a gravitational vacuum condensate)''. The central place in this version of QGD belongs to the Schrodinger equation for a wave function of the Universe. An exact solution to the ``conditionally-classical'&#39

Lee Samuel Finn, Kip S. Thorne

Results are presented from high-precision computations of the orbital evolution and emitted gravitational waves for a stellar-mass object spiraling into a massive black hole in a slowly shrinking, circular, equatorial orbit. The focus of these computations is inspiral near the innermost stable circular orbit (isco)---more particularly, on orbits for which th

A. Scala, F. W. Starr, E. La Nave, H. E. Stanley

We present a detailed analysis of the free energy surface of a well characterized rigid model for water in supercooled states. We propose a functional form for the liquid free energy, supported by recent theoretical predictions [Y. Rosenfeld and P. Tarazona, Mol. Phys. {\bf 95}, 141 (1998)], and use it to locate the position of a liquid-liquid critical point

Francis W. Starr, Srikanth Sastry, Emilia La Nave, Antonio Scala

Relations between the thermodynamics and dynamics of supercooled liquids approaching a glass transition have been proposed over many years. The potential energy surface of model liquids has been increasingly studied since it provides a connection between the configurational component of the partition function on one hand, and the system dynamics on the other

Francis W. Starr, Thomas B. Schrøder, Sharon C. Glotzer

We perform molecular dynamics simulations of an idealized polymer melt surrounding a nanoscopic filler particle to probe the effects of a filler on the local melt structure and dynamics. We show that the glass transition temperature $T_g$ of the melt can be shifted to either higher or lower temperatures by appropriately tuning the interactions between polyme

Mariana Weissmann, H. Bonadeo

In an interesting new experiment the electronic structure of a magnetic atom adsorbed on the surface of Cu(111), observed by STM, was projected into a remote location on the same surface. The purpose of the present paper is to interpret this experiment with a model Hamiltonian, using ellipses of the size of the experimental ones, containing about 2300 atoms.

Eugene H. Kim

Recently, conductivity measurements were performed on the hole-doped two-leg ladder material Sr_{14-x}Ca_xCu_{24}O_{41}. In this work, we calculate the conductivity for doped two-leg ladders using a model of hole-pairs forming a strongly correlated liquid - a single component Luttinger liquid - in the presence of disorder. Quantum interference effects are ha

John J. Quinn, Arkadiusz Wojs, Jennifer J. Quinn, Arthur Benjamin

A Fermion to Boson transformation is accomplished by attaching to each Fermion a single flux quantum oriented opposite to the applied magnetic field. When the mean field approximation is made in the Haldane spherical geometry, the Fermion angular momentum $l_F$ is replaced by $l_B= l_F-{1\over2}(N-1)$. The set of allowed total angular momentum multiplets is

Matthias Mayr, Adriana Moreo, Jose A. Verges, Jeanette Arispe

The resistivity $ρ_{dc}$ of manganites is studied using a random-resistor-network, based on phase-separation between metallic and insulating domains. When percolation occurs, both as chemical composition and temperature vary, results in good agreement with experiments are obtained. Similar conclusions are reached using quantum calculations and microscopic co

J. Chiaverini, J. N. Eckstein, I. Bozovic, S. Doniach

The large flux-flow velocity behavior of the high temperature superconductor BSCCO in the mixed state is studied by measurement of the current-voltage characteristic as a function of temperature and magnetic field direction. We find strong evidence for vortex-antivortex pairs that are excited by quantum fluctuations and contribute to the dissipation when dis

A. P. Nielsen, A. B. Cawthorne, P. Barbara, F. C. Wellstood

We have measured a paramagnetic Meissner effect in Nb-Al2O3-Nb Josephson junction arrays using a scanning SQUID microscope. The arrays exhibit diamagnetism for some cooling fields and paramagnetism for other cooling fields. The measured mean magnetization is always less than 0.3 flux quantum (in terms of flux per unit cell of the array) for the range of cool

Christoph Kopper, Walter Pedra

We study the critical behaviour of symmetric $ϕ^4_4$ theory including irrelevant terms of the form $ϕ^{4+2n}/Λ_0^{2n}$ in the bare action, where $Λ_0$ is the UV cutoff (corresponding e.g. to the inverse lattice spacing for a spin system). The main technical tool is renormalization theory based on the flow equations of the renormalization group which permits

A. D. Mirlin, P. Woelfle

In a recent Letter, Taras-Semchuk and Efetov reconsider the problem of electron localization in a random magnetic field in two dimensions. They claim that due to the long-range nature of the vector potential correlations an additional term appears in the effective field theory ($σ$-model) of the problem, leading to delocalization at the one-loop level. This

Zhi-Feng Huang, Dietrich Stauffer

A stochastic genetic model for biological aging is introduced bridging the gap between the bit-string Penna model and the Pletcher-Neuhauser approach. The phenomenon of exponentially increasing mortality function at intermediate ages and its deceleration at advanced ages is reproduced for both the evolutionary steady-state population and the genetically homo

Tim Wilkens, Richard M. Martin

Quantum Monte Carlo methods are used to study a quantum phase transition in a 1D Hubbard model with a staggered ionic potential (D). Using recently formulated methods, the electronic polarization and localization are determined directly from the correlated ground state wavefunction and compared to results of previous work using exact diagonalization and Hart

G. Franzese, M. Yamada, H. E. Stanley

We improve a lattice model of water introduced by Sastry, Debenedetti, Sciortino, and Stanley to give insight on experimental thermodynamic anomalies in supercooled phase, taking into account the correlations between intra-molecular orientational degrees of freedom. The original Sastry et al. model including energetic, entropic and volumic effect of the orie

Teemu Pohjola, Herbert Schoeller, Gerd Schön

Motivated by recent experiments, in which the Kondo effect has been observed for the first time in a double quantum-dot structure, we study electron transport through a system consisting of two ultrasmall, capacitively-coupled dots with large level spacing and charging energy. Due to strong interdot Coulomb correlations, the Kondo effect has two possible sou

Jaume Masoliver, Miquel Montero, Alan McKane

A dynamical model based on a continuous addition of colored shot noises is presented. The resulting process is colored and non-Gaussian. A general expression for the characteristic function of the process is obtained, which, after a scaling assumption, takes on a form that is the basis of the results derived in the rest of the paper. One of these is an expan

M. Cristina Marchetti

The fabrication of artificial pinning structures allows a new generation of experiments which can probe the properties of vortex arrays by forcing them to flow in confined geometries. We discuss the theoretical analysis of such experiments in both flux liquids and flux solids, focusing on the Corbino disk geometry. In the liquid, these experiments can probe

W. Goeb, W. Liebich, W. Lang, I. Puica

Measurements of the Hall effect and the resistivity in twinned YBa2Cu3O7-delta thin films in magnetic fields B oriented parallel to the crystallographic c-axis and to the twin boundaries reveal a double sign reversal of the Hall coefficient for B below 1 T. In high transport current densities, or with B tilted off the twin boundaries by 5 degrees, the second

R. G. Dias

We present the solution of the one-dimensional t-V model with twisted boundary conditions in the strong coupling limit, t<<V and show that this model can be mapped onto the strong coupling Hubbard chain threaded by a fictitious flux proportional to the total momentum of the charge carriers. The high energy eigenstates are characterized by a factorization of

P. Jönsson, P. Svedlindh, P. Nordblad, M. F. Hansen

A highly concentrated (17 vol.%) Fe-C nano-particle system, with a narrow size distribution $d = 5.4\pm 0.4$ nm, has been investigated using magnetic ac susceptibility measurements covering a wide range of frequencies (17 mHz - 170 Hz). A dynamic scaling analysis gives evidence for a phase transition to a low temperature spin-glass-like phase. The critical e

F. Vistulo de Abreu, B. Doucot

We develop a controlled weak coupling renormalization group (RG) approach to itinerant electrons. Within this formalism we rederive the phase diagram for two-dimensional (2D) non-nested systems. Then we study how nesting modifies this phase diagram. We show that competition between p-p and p-h channels, leads to the manifestation of unstable precursor fixed

D. A. Parshin, C. Laermans

The direct proportionality relation between the boson peak maximum in glasses, $ω_b$, and the Ioffe-Regel crossover frequency for phonons, $ω_d$, is established. For several investigated materials $ω_b = (1.5\pm 0.1)ω_d$. At the frequency $ω_d$ the mean free path of the phonons $l$ becomes equal to their wavelength because of strong resonant scattering on qu

T. Prikhna, W. Gawalek, V. Moshchil, A. Surzhenko

The Tm-Ba-Cu-O solder can be successfully used to produce a superconductive joint between MT-YBCO parts. The peculiarities of solidification, phase formation, structure transformations and electromagnetic properties of MT-YBCO soldered with TmBa2Cu3O7-d are discussed.

M. Ya. Amusia, V. R. Shaginyan

A model of a strongly correlated electron liquid based on the fermion condensation (FC) is applied to the consideration of high temperature superconductors in its superconducting and normal states. Within our model the appearance of FC presents a boundary, separating the region of strongly interacting electron liquid from the region of strongly correlated el

C. Manwart, S. Torquato, R. Hilfer

A simulated annealing algorithm is employed to generate a stochastic model for a Berea and a Fontainebleau sandstone with prescribed two-point probability function, lineal path function, and ``pore size&#39;&#39; distribution function, respectively. We find that the temperature decrease of the annealing has to be rather quick to yield isotropic and percolati

E. Brézin, De Dominicis

The replicated field theory of the random field Ising model involves the couplings of replicas of different indices. The resulting correlation functions involve a superposition of different types of long distance behaviours. However the $n=0$ limit allows one to discuss the renormalization group properties in spite of this phenomenon. The attraction of pairs

Satoshi Yukawa

A quantum analogue of the Jarzynski equality is constructed. This equality connects an ensemble average of exponentiated work with the Helmholtz free-energy difference in a nonequilibrium switching process subject to a thermal heat bath. To confirm its validity in a practical situation, we also investigate an open quantum system that is a spin 1/2 system wit

J. E. Hirsch

We have recently proposed that superconductivity may be understood as driven by the undressing of quasiparticles as the superconducting state develops. Similarly we propose here that ferromagnetism in metals may be understood as driven by the undressing of quasiparticles as the ferromagnetic state develops. In ferromagnets, the undressing is proposed to occu

T. Rauscher, R. D. Hoffman, S. E. Woosley, F. -K. Thielemann

The majority of nuclear reactions in astrophysics involve unstable nuclei which are not fully accessible by experiments yet. Therefore, there is high demand for reliable predictions of cross sections and reaction rates by theoretical means. The majority of reactions can be treated in the framework of the statistical model (Hauser-Feshbach). The global parame

Pierre Binetruy, Joseph Silk

It has been recently argued that higher dimensional gravity theories may manifest themselves not only at short microscopic distances but also at large cosmological scales. We study the constraints that cosmic microwave background measurements set on such large distance modifications of the gravitational potential.

T. Rauscher, F. Rembges, H. Schatz, M. Wiescher

The hydrogen-rich accreted envelopes of neutron stars in binary systems are the site for the rapid proton capture nucleosynthethic process (rp-process), which involves nuclei close to the proton dripline. An overview of the relevant reactions and nuclear properties for rp-process studies is given, along with motivations for further experimental nuclear physi

Axel Brandenburg, Kandaswamy Subramanian

It is shown that ambipolar diffusion as a toy nonlinearity leads to very similar behaviour of large scale turbulent dynamos as full MHD. This is demonstrated using both direct simulations in a periodic box and a closure model for the magnetic correlation functions applicable to infinite space. Large scale fields develop via a nonlocal inverse cascade as desc

Keith S. Noll, T. R. Geballe, S. K. Leggett, Mark S. Marley

We have detected weak absorption features produced by the strong nu(3) methane band at 3.3 microns in two L dwarfs, 2MASSW J1507476-162738 and 2MASSI J0825196+211552, classified by Kirkpatrick et al. (2000) as spectral types L5 and L7.5 respectively. These absorptions occur in objects warmer than any in which methane previously has been detected, and mark th

Scott J. Wolk, Rebecca T. Cover, Ray Jayawardhana, Thomas J. Hearty

We present optical and infrared photometry of stars near the MBM 12 dark cloud. The optical data indicate that there are about 40 candidate pre-main sequence stars in the same area currently occupied by eight bona-fide PMS stars. Analysis of 2MASS data suggests that 60% of PMS candidates have been detected. Some of these show evidence of optically thick disk

Jianjun Xu, Philip Hardee, James Stone

The effect of optically thin radiative cooling on the Kelvin-Helmholtz instability of three dimensional jets is investigated via linear stability theory and nonlinear hydrodynamical simulation. Two different cooling functions are considered: radiative cooling is found to have a significant effect on the stability of the jet in each case. The wavelengths and

M. Lopez-Corredoira, F. Garzon, P. L. Hammersley

From an analysis of the stars remaining in central regions of the Galaxy after subtracting those belonging to the disc and the bulge, we deduce that the inner bulge must have an extra young population with respect the rest of the bulge. It is shown that there is a higher ratio of very bright stars in the central bulge than than there is in the outer bulge. T

Katherine Freese, Brian Fields, David Graff

The nature of the dark matter in the Universe is one of the outstanding questions in astrophysics. In this talk, I address possible stellar baryonic contributions to the 50-90% of our Galaxy that is made of unknown dark matter. First I show that faint stars and brown dwarfs constitute only a few percent of the mass of the Galaxy. Next, I show that stellar re

Helio V. Fagundes

The results of a previous paper by the author [Astrophys. J. 470, 43 (1996) are improved, through a more reliable technique for finding the location of sources whose images are on the surface of last scattering.

J. Knodlseder

The morphology and stellar content of the Cygnus OB2 association has been determined using 2MASS infrared observations in the J, H, and K bands. The analysis reveals a spherically symmetric association of 2 deg in diameter with a half light radius of 13&#39;, corresponding to Rh = 6.4 pc at an assumed distance of 1.7 kpc. The interstellar extinction for memb

F. Tavecchio, L. Maraschi R. M. Sambruna, C. M. Urry

We propose that the X-ray emission detected by Chandra from the 100-kiloparsec-scale jet of PKS 0637-752 is produced through inverse Compton scattering of the Cosmic Microwave Background (CMB). We analyze the physical state of the jet and show that inverse Compton scattering from the CMB is consistent with equipartition for a moderate beaming of the emission

Naohito Nakasato, Toshikazu Shigeyama

The long-term evolution of supernova remnants (SNRs) in the primordial interstellar medium (ISM) with an inhomogeneous structure is calculated to investigate metal enrichment of the primordial gas. For this purpose, we have constructed a parallel 3-D hydrodynamics code incorporating the radiative cooling and self-gravity. The self-gravity and radiative cooli

Tim de Zeeuw, Ronnie Hoogerwerf, Jos de Bruijne

Milli-arcsecond astrometry provided by Hipparcos and by radio observations makes it possible to retrace the orbits of nearby runaway stars and pulsars with sufficient accuracy to identify their parent stellar cluster or association. For two cases it is even possible to deduce the specific formation scenario. The runaway star zeta Oph and PSR J1932+1059 are t

D. Fadda, D. Elbaz, P. -A. Duc, H. Flores

We present the results of infrared observations of Abell 1689 which was observed with ISOCAM, at 6.7\mic and 15\mic, and ISOPHOT at 200\mic. The cluster galaxies detected above a sensitivity limit of 0.15 mJy in the 6.7\mic band, whose emission is mostly dominated by their stellar component, show optical colors similar to the overall cluster population and a

R. Hoogerwerf, J. H. J. de Bruijne, P. T. de Zeeuw

Milli-arcsecond astrometry provided by Hipparcos and by radio observations makes it possible to retrace the orbits of some of the nearest runaway stars and pulsars to determine their site of origin. The orbits of the runaways AE Aurigae and mu Columbae and of the eccentric binary iota Orionis intersect each other about 2.5 Myr ago in the nascent Trapezium cl

A. Capetti, E. J. Schreier, D. J. Axon, S. Young

We report results from HST/NICMOS 2 micron imaging polarimetry of the central region of Centaurus A. In the vicinity of the nucleus we observe a complex polarization structure which we explain by a combination of scattering of nuclear light and dichroic polarization associated with the dust lane. The scattered nuclear radiation is found in an angular region

A. Capetti, E. Trussoni, A. Celotti, L. Feretti

We consider archival ROSAT and HST observations of five FRI radio galaxies and isolate their nuclear emission from that of the host galaxy. This enable us to determine the Spectral Energy Distributions (SED) of their nuclei spanning from the radio to the X-ray band. They cannot be described as single power-laws but require the presence of an emission peak lo

J. G. Funes S. J, E. M. Corsini

The conference Galaxy Disks and Disk Galaxies, sponsored by the Vatican Observatory, was held in June 12-16, 2000 at the Pontifical Gregorian University, in Rome (Italy). The meeting hosted about 230 participants coming from 30 countries. The very full program consisted of 29 review papers, 34 invited talks, and more than 180 posters. The meeting covered top

M. Guainazzi, A. N. Parmar, T. Oosterbroek

A BeppoSAX survey of bright Neutron Star (NS) systems in globular clusters, together with the results obtained on Galactic LMXRB, suggests that a two-component model is a reasonable description of the 0.1-200 keV spectra. At energies lower than a few keV, a thermal component dominates, either due to the direct view of the NS surface, to the emission of the b

R. Della Ceca, V. Braito, V. Beckmann, I. Cagnoni

We will briefly discuss the X-ray spectral properties of the objects in the ASCA Hard Serendipitous Survey (HSS) sample and its present AGN contents. We also present X-ray spectroscopy of two Type 2 AGN belonging to the sample.

R. Della Ceca, V. Braito, I. Cagnoni, T. Maccacaro

We summarize here some of the main results we have reached so far in the ASCA Hard Serendipitous Survey, a survey program conducted in the 2-10 keV energy band. In particular we will discuss the number-flux relationship, the 2-10 keV spectral properties of the sources, and the cross-correlation of the ASCA sources with ROSAT sources.

J. -P. Macquart, D. B. Melrose

We present a physical interpretation for the generation of circular polarization resulting from the propagation of radiation through a magnetized plasma in terms of a rotation measure gradient, or `Faraday wedges&#39;. Criteria for the observability of scintillation-induced circular polarization are identified. Application of the theory to the circular polar

Licia Verde, Marc Kamionkowski, Joseph J. Mohr, Andrew J. Benson

We show that the distribution of the sizes and temperatures of clusters can be used to constrain cosmological models. The size-temperature (ST) distribution predicted in a flat Gaussian cluster-abundance-normalized Omega_0=0.3 model agrees well with the fairly tight ST relation observed. A larger power-spectrum amplitude sigma_8 would give rise to a larger s

Aurel Bulgac, Piotr Magierski

Homogeneous neutron matter at subnuclear densities becomes unstable towards the formation of inhomogeneities. Depending on the average value of the neutron density one can observe the appearance of either bubbles, rods, tubes or plates embeded in a neutron gas. We estimate the quantum corrections to the ground state energy (which could be termed either shell

Hubert Klahr, D. N. C. Lin

There have been several model analyses of the near and mid IR flux from the circumstellar ring around HR4796A. In the vicinity of a young star, the possibility that the dust ring is embedded within a residual protostellar gas disk cannot be ruled out. In a gas-rich environment, larger sizes ($>100 μm$) are needed for the particles to survive the radiative bl

Robert L. Thews, Martin Schroedter, Johann Rafelski

In high energy heavy ion collisions at the Relativistic Heavy Ion Collider (RHIC) at Brookhaven and the Large Hadron Collider (LHC) at CERN, each central event will contain multiple pairs of heavy quarks. if a region of deconfined quarks and gluons is formed, a new mechanism for the formation of heavy quarkonium bound states will be activated. This is a resu

T. E. Clark, S. T. Love

A generalization of the Akulov-Volkov effective Lagrangian governing the self interactions of the Nambu-Goldstone fermions associated with spontaneously broken extended supersymmetry as well as their coupling to matter is presented and scrutinized. The resulting currents associated with R-symmetry, supersymmetry and space-time translations are constructed an

A. Masiero, O. Vives

We analyze CP violation and Flavor Changing effects in a general Minimal Supersymmetric extension of the Standard Model with arbitrary non-universal soft-breaking terms. We show that, in this conditions, large FCNC effects are naturally expected in the Kaon system, even in the absence of quark-squark flavor misalignment. On the other hand, the B system is on

F. del Aguila, M. Perez-Victoria, J. Santiago

Models with new vector-like quarks can produce observable quark mixing effects which are forbidden in the Standard Model. We classify all such models and write down the effective Lagrangian that results from integrating out the new quarks. We study the relations between neutral and charged currents and discuss how to distinguish among the different possibili

Christopher T. Hill, Pierre Ramond

Certain static soliton configurations of gauge fields in 4+1 dimensions correspond to the instanton in 4-Euclidean dimensions ``turned on its side,&#39;&#39; becoming a monopole in 4+1. The periodic instanton solution can be used with the method of images to construct solutions satisfying D-brane boundary conditions. The $θ$-term on the brane becomes a topol

S. Pacetti, Y. Srivastava

A previously successful dispersive method has been applied to understand different values for $R(\sqrt{s} = 5 ÷7.5 GeV)$ obtained by MARK I and Crystal Ball collaborations. We compute $R$ in the disputed region with data from outside this region and asymptotic behavior given by the standard model with 5 quark flavors, and find agreement with the Crystal Ball

S. De Franceschi, S. Sasaki, J. M. Elzerman, W. G. van der Wiel

We report transport measurements on a semiconductor quantum dot with a small number of confined electrons. In the Coulomb blockade regime, conduction is dominated by cotunneling processes. These can be either elastic or inelastic, depending on whether they leave the dot in its ground state or drive it into an excited state, respectively. We are able to discr

Mustapha Ishak, Luke Chamandy, Nicholas Neary, Kayll Lake

An explicit necessary condition for the occurrence of resonance scattering of axial gravitational waves, along with the internal trapping of null geodesics, is proposed for static spherically symmetric perfect fluid solutions to Einstein's equations. Some exact inhomogeneous solutions which exhibit this trapping are given with special attention to boundary c

N. Kivel, M. V. Polyakov, A. Schafer, O. V. Teryaev

We present a derivation of Wandzura-Wilczek (WW) like relations for skewed parton distributions. It is demonstrated for photon-pion scattering that the skewed twist-3 parton distributions contributing to the DVCS amplitude have discontinuities at the points $x=\pmξ$ in the WW approximation. This may lead to a violation of factorisation for the twist-3 DVCS a

S. Esposito, G. Mangano, A. Melchiorri, G. Miele

We test different Big Bang Nucleosynthesis scenarios using the recent results on the Cosmic Microwave Background Anisotropies provided by the BOOMERanG and MAXIMA-1 experiments versus the observed abundances of 4He, D and 7Li. The likelihood analysis, based on Bayesian approach, shows that, in the case of high deuterium abundance, Y_D=(2.0\pm0.5) 10^{-4}, bo

Marek Pajda, Josef Kudrnovsky, Ilja Turek, Vaclav Drchal

The effective exchange interactions of magnetic overlayers Fe/Cu(001) and Co/Cu(001) covered by a Cu-cap layer of varying thickness were calculated in real space from first principles. The effective two-dimensional Heisenberg Hamiltonian was constructed and used to estimate magnon dispersion laws, spin-wave stiffness constants, and overlayer Curie temperatur

Gaetano Fiore, Harold Steinacker, Julius Wess

We show that the braided tensor product algebra $A_1\underline{\otimes}A_2$ of two module algebras $A_1, A_2$ of a quasitriangular Hopf algebra $H$ is equal to the ordinary tensor product algebra of $A_1$ with a subalgebra of $A_1\underline{\otimes}A_2$ isomorphic to $A_2$, provided there exists a realization of $H$ within $A_1$. In other words, under this a

Nicolas Boulanger, Thibault Damour, Leonardo Gualtieri, Marc Henneaux

We investigate, in any spacetime dimension >=3, the problem of consistent couplings for a finite collection of massless, spin-2 fields described, in the free limit, by a sum of Pauli-Fierz actions. We show that there is no consistent (ghost-free) coupling, with at most two derivatives of the fields, that can mix the various &#34;gravitons&#34;. In other word

Nicolas Borghini, Phuong Mai Dinh, Jean-Yves Ollitrault

The methods currently used to measure azimuthal distributions of particles in heavy ion collisions assume that all azimuthal correlations between particles result from their correlation with the reaction plane. However, other correlations exist, and it is safe to neglect them only if azimuthal anisotropies are much larger than 1/sqrt(N), with N the total num

Christof Gattringer, Ivan Hip, C. B. Lang

We construct a 4-d lattice Dirac operator D using a systematical expansion in terms of simple operators on the lattice. The Ginsparg-Wilson equation turns into a system of coupled equations for the expansion coefficients of D. We solve these equations for a finite parametrization of D and find an approximate solution of the Ginsparg-Wilson equation. We analy

P. H. Damgaard, U. M. Heller, R. Niclasen, K. Rummukainen

We compute by Monte Carlo methods the individual distributions of the $k$th smallest Dirac operator eigenvalues in QCD, and compare them with recent analytical predictions. We do this for both massless and massive quarks in an SU(3) gauge theory with staggered fermions. Very precise agreement is found in all cases. As a simple by-product we also extract the

Xavier Gracia, Josep M. Pons

For a dynamical system defined by a singular Lagrangian, canonical Noether symmetries are characterized in terms of their commutation relations with the evolution operators of Lagrangian and Hamiltonian formalisms. Separate characterizations are given in phase space, in velocity space, and through an evolution operator that links both spaces.

Marek Pajda, Josef Kudrnovsky, Ilja Turek, Vaclav Drchal

We have calculated Heisenberg exchange parameters for bcc-Fe, fcc-Co, and fcc-Ni using the scalar-relativistic spin-polarized Green function technique within the tight-binding linear muffin-tin orbital method and by employing the magnetic force theorem to calculate total energy changes associated with a local rotation of magnetization directions. We have als

Edwin Langmann

We obtain a second quantization of the elliptic Calogero-Sutherland (eCS) model by constructing a quantum field theory model of anyons on a circle and at a finite temperature. This yields a remarkable identity involving anyon correlation functions and providing an algorithm for solving of the eCS model. The eigenfunctions obtained define an elliptic generali

R. Mathieu, P. Nordblad, D. N. H. Nam, N. X. Phuc

Dynamic magnetic properties of $\mathrm{Y_{0.7}Ca_{0.3}MnO_{3}}$ are reported. The system appears to attain local ferromagnetic order at $T_{\mathrm{SRF}} \approx 70$ K. Below this temperature the low field magnetization becomes history dependent, i.e. the zero field cooled (ZFC) and field cooled (FC) magnetization deviate from each other and closely logarit

C. Sochichiu

We show that in the presence of U(1) noncommutative gauge interaction the noncommutative tachyonic system exhibits solitonic solutions for finite value of the noncommutativity parameter.

Laszlo E. Szabo, Arthur Fine

A recent analysis by de Barros and Suppes of experimentally realizable GHZ correlations supports the conclusion that these correlations cannot be explained by introducing local hidden variables. We show, nevertheless, that their analysis does not exclude local hidden variable models in which the inefficiency in the experiment is an effect not only of random

S. Hesselbach, F. Franke, H. Fraas

In extended supersymmetric models with additional singlet Higgs fields displaced vertices could be observed if the decay width of the next-to-lightest supersymmetric particle becomes very small due to a singlino dominated LSP. We study the supersymmetric parameter space where displaced vertices of the second lightest neutralino exist in the NMSSM and an E6 i

J. Finkelstein

State-vectors resulting from collapse along the forward light cone from a measurement interaction can be used for the attribution of both local and non-local properties.

S. G. Lebedev

In this work some probable consequences of introduction of discrete medium - carrier for fields of a substance are considered. The given medium is thinked as a set of harmonic oscillators filling all space. Discrete medium is introduced on an image and similarity of a crystalline lattice of a condensed matter. The particles - excitation are concentrated in s

Qiong-gui Lin

The Aharonov-Bohm-Coulomb potentials in two dimensions may describe the interaction between two particles carrying electric charge and magnetic flux, say, Chern--Simons solitons, or so called anyons. The scattering problem for such two-body systems is extended to the relativistic case, and the scattering amplitude is obtained as a partial wave series. The el

R. E. Stoner, R. L. Walsworth

We compared the frequency shift of the 21Ne Zeeman resonance induced by polarized Rb vapor to the shift induced in the 3He Zeeman resonance. The 3He/Rb shift has recently been measured with high precision, permitting the conversion of our differential measurement to an absolute value for the 21Ne/Rb shift. We report a value of K = 31.8 +/- 2.8 for the Rb/21N

C. Farina, F. C. Santos, A. C. Tort

It is well known that for the case of two neutral but electrically polarizable atoms the consideration or not of retardation effects on the dispersive van der Waals force between them leads essentially to different power laws for the forces; while the retarded force is proportional to $1/r^8$, where $r$ is the distance between the atoms, the non-retarded for

A. Facco, M. Pasini, V. Zviagintsev

A single gap, 352 MHz superconducting reentrant cavity for 5-100 MeV beams has been designed and it is presently under construction. This development is being done in the framework of a 30 mA proton linac project for nuclear waste transmutation. Mechanical, cryogenic and rf design characteristics of such cavities will be described.

A. V. Afanasjev, P. Ring, I. Ragnarsson

The importance of deformation changes and the possible role of proton-neutron pairing correlations on the properties of paired band crossings at superdeformation in the $A\sim 60$ mass region have been analyzed. The present analysis, supported in part by the cranked relativistic Hartree-Bogoliubov calculations for the SD band in $^{60}$Zn, suggests that when

Adrian Dumitru, Steffen Bass

We present results on the evolution of <p_t> with energy, for hadrons emerging from hadronization of a quark-gluon plasma possibly produced in high-energy heavy-ion collisions. We find that BNL-RHIC energy corresponds to the previously predicted plateau of <p_t>, reminiscent of the assumed first-order QCD phase transition. Heavy hadrons are the best messenge

C. P. Panos, S. E. Massen, C. G. Koutroulos

We calculate the information entropy of single-particle states in position-space $S_{r}$ and momentum-space $S_{k}$ for a nucleon in a nucleus, a $Λ$ particle in a hypernucleus and an electron in an atomic cluster. It is seen that $S_{r}$ and $S_{k}$ obey the same approximate functional form as functions of the number of particles, $S_{r}$ ({\rm or} $S_{k})

K. A. Bugaev, M. I. Gorenstein, I. N. Mishustin, W. Greiner

An exact analytical solution of the statistical multifragmentation model is found in thermodynamic limit. The system of nuclear fragments exhibits a 1-st order liquid-gas phase transition. The peculiar thermodynamic properties of the model near the boundary between the mixed phase and the pure gaseous phase are studied.

T. Engeland, M. Hjorth-Jensen, E. Osnes

We present a brief overview of microscopic nuclear structure approaches to nuclei with mass number from 100 to 132. The emphasis is on the shell model and theories for deriving effective interactions starting from the free interactions between nucleons. New results for (105,106,107)Sb are presented.

Mannque Rho

We reinterpret Landau-Migdal Fermi-liquid theory of nuclear matter as an effective chiral field theory with a Fermi surface. The effective field theory is formulated in terms of a chiral Lagrangian with its {\it mass and coupling parameters} scaling a la Brown-Rho and with the Landau-Migdal parameters identified as the fixed points of the field theory. We sh

M. Gurses, K. Zheltukhin

We give a general method for constructing recursion operators for some equations of hydrodynamic type, admitting a nonstandard Lax representation. We give several examples for N=2 and N=3 containing the equations of shallow water waves and its generalizations with their first two higher symmetries and their recursion operators. We also discuss a reduction of

Lluis Torner, Juan P. Torres, Ole Bang

We address the robustness of quadratic solitons with periodic non-conservative perturbations. We find the evolution equations for guiding-center solitons under conditions for second-harmonic generation in the presence of periodic multi-band loss and gain. Under proper conditions, a robust guiding-center soliton formation is revealed.

M. R. Grasselli

We present the construction of an infinite dimensional Banach manifold of quantum mechanical states on a Hilbert space H using different types of small perturbations of a given Hamiltonian. We provide the manifold with a flat connection, called the exponential connection, and comment on the possibility of introducing the dual mixture connection.

Xavier Gracia

The fibre derivative of a bundle map is studied in detail. In the particular case of a real function, several constructions useful to study singular lagrangians are presented. Some applications are given; in particular, a geometric construction useful to solve the Euler-Lagrange equation of a singular lagrangian. A free particle in a curved space-time is stu