November 1998 arXiv papers — page 7

Judith A. Irwin, Jayanne English, Barkat Sorathia

We have mapped 16 edge-on galaxies at 20 cm using the VLA. For 5 galaxies, we could form spectral index, energy and magnetic field maps. We find that all but one galaxy show evidence for non-thermal high latitude radio continuum emission, suggesting that cosmic ray halos are common in star forming galaxies. The high latitude emission is seen over a variety o

V. Kiryukhin, Y. J. Wang, F. C. Chou, M. A. Kastner

We report a synchrotron x-ray scattering study of the magnetoresistive manganite La_0.875Sr_0.125MnO_3. At low temperatures, this material undergoes an x-ray induced structural transition at which charge ordering of Mn^3+ and Mn^4+ ions characteristic to the low-temperature state of this compound is destroyed. The transition is persistent but the charge-orde

J. F. Beacom, P. Vogel

A future core-collapse supernova in our Galaxy will be detected by several neutrino detectors around the world. The neutrinos escape from the supernova core over several seconds from the time of collapse, unlike the electromagnetic radiation, emitted from the envelope, which is delayed by a time of order hours. In addition, the electromagnetic radiation can

Nobuko Fuchikami, Shunya Ishioka, Ken Kiyono

We present a simulation of a dripping faucet system. A new algorithm based on Lagrangian description is introduced. The shape of drop falling from a faucet obtained by the present algorithm agrees quite well with experimental observations. Long-term behavior of the simulation can reproduce period-one, period-two, intermittent and chaotic oscillations widely

Faruk Gungor

A classification of all possible realizations of the Galilei, Galilei-similitude and Schroedinger Lie algebras in three-dimensional space-time in terms of vector fields under the action of the group of local diffeomorphisms of the space $\R^3\times\C$ is presented. Using this result a variety of general second order evolution equations invariant under the co

Fabian H. L. Essler

Specific heat data for the quasi one dimensional quantum magnet Copper Benzoate (Cu(C_6D_5COO)_2 \cdot 3D_2O) is analyzed in the framework of an effective low-energy description in terms of a Sine-Gordon theory.

H. Kleinert

For a single membrane of stiffness kappa fluctuating between two planar walls of distance d, we calculate analytically the proportionality constant in the pressure law p proportional to T^2/kappa^2 d^3, in very good agreement with results from Monte Carlo simulations.

R. V. N. Melnik, A. J. Roberts

We consider problems of dynamic viscoelasticity taking into account the coupling of elastic and thermal fields. Efficient approximate models are developed and computational results on thermomechanical behaviour of shape-memory-alloy structures are presented.

Keith R. Dienes, Emilian Dudas, Tony Gherghetta

Recent theoretical developments have shown that extra spacetime dimensions can lower the fundamental GUT, Planck, and string scales. However, recent evidence for neutrino oscillations suggests the existence of light non-zero neutrino masses, which in turn suggests the need for a heavy mass scale via the seesaw mechanism. In this paper, we make several observ

G. B. Cleaver, A. E. Faraggi, D. V. Nanopoulos

The recent conjecture of possible equivalence between the string scale $M_S$ and the minimal supersymmetric standard model unification scale M_U ~ 2.5 x 10^{16} GeV is considered in the context of string models. This conjecture suggests that the observable gauge group just below the string scale should be SU(3)_C x SU(2)_L x U(1)_Y and that the SU(3)_C x SU(

Boris Lorbeer

In [1] new discretizations of the Euler top have been found. They can be discribed with a Lax pair with a spectral parameter on an elliptic curve. This is used in this paper to perform a finite gap integration.

Leopold Travis

An operation on species corresponding to the inner plethysm of their associated cycle index series is constructed. This operation, the inner plethysm of species, is generalized to n-sorted species. Polynomial maps on species are studied and used to extend inner plethysm and other operations to virtual species. Finally, inner plethysm and other operations on

M. Yu. Khlopov, A. S. Sakharov, A. L. Sudarikov

COSMOPARTICLE PHYSICS is the specific crossdisciplinary field of science, studying foundations of particle physics and cosmology in the combination of indirect cosmological, astrophysical and physical signatures of their fundamental relationship. The possibilities to elaborate unique theoretical grounds for cosmology and particle physics and to study quantit

Andrew Akeroyd, Abdesslam Arhrib, El-Mokhtar Naimi

We compute the fermionic radiative contributions to the decay $H^+ \to W^{+(*)} A^0$ in the framework of models with two Higgs doublets (2HDM), for the case of an on-shell and off-shell W. We show that, in the majority of the cases, current measurements of the $ρ$ parameter suggest $M_{H^{\pm}}\ge M_A$ and such decays could invalidate current charged Higgs s

Yu. Arestov, F. R. A. Simao

The Pomeron-gluon-gluon interaction is considered in the QCD-based model for the charmed baryon production in the process Pomeron + p --> Λ_c^+ + X. The polarization of the produced heavy quark is induced effectively through the non-perturbative long-range interaction with the gluon field of the type [sigma*rotA]. The x_F-dependence of Λ_c^+ polarization, P_

Ewald Wessels

Bondi's approach to the construction of a coordinate system is used with a different choice of gauge, in accordance with which the radial coordinate r is an affine parameter, to cast the metric tensor into a form suitable for use with the Newman-Penrose null tetrad formalism. The choice of tetrad has the result that the equations and all the functions th

Petr Chvosta, Noelle Pottier

We consider the one-dimensional diffusion of a particle on a semi-infinite line and in a piecewise linear random potential. We first present a new formalism which yields an analytical expression for the Green function of the Fokker-Planck equation, valid for any deterministic construction of the potential profile. The force is then taken to be an asymmetric

R. Benzi, L. Biferale, G. Ruiz-Chavarria, S. Ciliberto

Multiscale correlation functions in high Reynolds number experimental turbulence, numerical simulations and synthetic signals are investigated. Fusion Rules predictions as they arise from multiplicative, almost uncorrelated, random processes for the energy cascade are tested. Leading and sub-leading contribution, in the inertial range, can be explained as ar

Peter Lundqvist, Jesper Sollerman, Alak Ray, Bruno Leibundgut

We present optical data gathered by the VLT Test Camera in the V-band at the radio (interferometric) position of PSR1706-44. We find no optical counterpart to the pulsar in the VLT image. At a distance of 2.7 arcsec from a nearby bright star, the 3-sigma upper limit to the pulsar magnitude above the background is V = 25.5. Within an error circle of 1.0 arcse

C. D. Dowell, D. C. Lis, E. Serabyn, M. Gardner

Using the 20-pixel camera SHARC, we have surveyed the 350 micron emission from a 60 arcminute by 12 arcminute region in the Galactic center. A comparable region has been observed at 800 microns by Lis & Carlstrom (1994); the SHARC map has better spatial resolution and sensitivity to extended emission, however. This paper introduces several features not visib

I. Neill Reid, Suzanne L. Hawley

We have used both the Low-Resolution Imaging Spectrograph and the HIRES echelle spectrograph on the Keck telescopes to obtain spectra of twelve candidate members of the Hyades cluster identified by Leggett and Hawkins (1988, 1989). All of the objects are chromospherically-active, late-type M-dwarfs, with H$α$ equivalent widths varying from 1 to 30Å. Based on

I. Neill Reid

We have used the Low-Resolution Imaging Spectrograph on the Keck II telescope to observe the brown dwarf candidate D04 (Hawkins et al, 1998). The spectrum matches that of a spectral-type M7 dwarf, implying a photospheric temperature of $\approx 2600$K. This is consistent with the available (R-I)$_C$ and (I-K) colours. If the parallax measured by Hawkins et a

Peter Erwin, Linda S. Sparke

We present results from a preliminary analysis of a recently-completed, multicolor imaging survey of nearby, early-type barred galaxies in the field, carried out with the WIYN telescope and supplemented with archival HST images. This forms a reasonably complete sample of nearby, bright, barred S0 and Sa galaxies in the field. The excellent seeing provided by

Daniel Stern, Arjun Dey, Hyron Spinrad, Leslie Maxfield

We present optical identifications and redshifts for seventeen new high-redshift radio sources. Fifteen of these sources are radio galaxies; the remaining two are high-redshift, steep-spectrum, radio-loud quasars. These objects were discovered as part of an ongoing study of compact (theta < 10 arcsec), moderately steep spectrum (alpha(1.4 GHz;4.8 GHz) > 0.75

Xinwei Kong, Finn Ravndal

Using a recently developed effective field theory for the interactions of nucleons at non-relativistic energies, we calculate the Coulomb corrections to proton-proton scattering. Including the dimension-eight derivative interaction in PDS regularization scheme, we obtain a modified Jackson-Blatt relation for the scattering lengths which is found to be phenom

G. B. Taylor, C. P. O&#39;Dea, A. B. Peck, A. M. Koekemoer

We present sensitive, high resolution Very Long Baseline Array (VLBA) observations of the central 0.3 arcsec of PKS 2322-123 at 1.3 and 5 GHz. These observations reveal straight and symmetric jets emerging from both sides of an inverted spectrum core. The 21 cm line of atomic hydrogen is detected in absorption against the core and eastern jet with substantia

A. Tanzini, O. S. Ventura, L. C. Q. Vilar, S. P. Sorella

The BRST cohomology of the N=2 supersymmetric Yang-Mills theory in four dimensions is discussed by making use of the twisted version of the N=2 algebra. By the introduction of a set of suitable constant ghosts associated to the generators of N=2, the quantization of the model can be done by taking into account both gauge invariance and supersymmetry. In part

Ilja Schmelzer

We introduce additional restriction into &#34;general ether theory&#34; - a generalization of Lorentz ether theory to gravity - which fixes the signs of the cosmological constants in this theory. This leads to an oscillating universe, thus, solves the cosmological horizon problem without inflation. We prove the equivalence of the Lagrangian of this theory wi

E. Marinari, C. Naitza, G. Parisi, M. Picco

In a comment cond-mat/9811080 to our paper (PRL, vol 81, 1698 (1998)) H. Bokil, A. Bray, B. Drossel and M. Moore claimed that we have reached wrong conclusions. We show here why their claims are not correct, especially when compared to the analysis of reference cond-mat/9808140.

Paul Benioff

Besides their use for efficient computation, quantum computers are a base for studying quantum systems that create valid physical theories using mathematics and physics. An essential part of the validation process for quantum mechanics is the development of a coherent theory of mathematics and quantum mechanics together. Such a theory should combine mathemat

R. A. Klemm, C. T. Rieck, K. Scharnberg

The symmetry operations of the crystal groups relevant for the high temperature superconductors HgBa2CuO4+x (Hg1201), YBa2Cu3O7-x (YBCO), and Bi2Sr2CaCu2O8+x (BSCCO) are elucidated. The allowable combinations of the superconducting order parameter (OP) components are presented for both the angular momentum and lattice representations. For tetragonal Hg1201,

M. A. Nielsen

Suppose Alice and Bob jointly possess a pure state, $|ψ\ra$. Using local operations on their respective systems and classical communication it may be possible for Alice and Bob to transform $|ψ\ra$ into another joint state $|ϕ\ra$. This Letter gives necessary and sufficient conditions for this process of entanglement transformation to be possible. These cond

Maria L. Ekiel-Jezewska

This paper is an introductory guide to many-particle hydrodynamic interactions. Basic concepts of the fluid dynamics are assumed to be known. Experience in the Stokes equations is useful but not necessary. The study is estimated to fit five sessions about three hours each.

Daniel S. Fisher, Pierre Le Doussal, Cecile Monthus

Sinai&#39;s model of diffusion in one-dimension with random local bias is studied by a real space renormalization group which yields exact results at long times. The effects of an additional small uniform bias force are also studied. We obtain analytically the scaling form of the distribution of the position $x(t)$ of a particle, the probability of it not re

S. Jeschonnek, T. W. Donnelly

We investigate the reactions D(e,e&#39;p)n and D(\vec e,e&#39;p)n at GeV energies and discuss the opportunities to distinguish between different models for the nuclear ground state by measuring the response functions. In calculating the final-state interaction (FSI) we employ Glauber theory, and we also include relativistic effects in the electromagnetic cur

Frank Klingl, Sungsik Kim, Su Houng Lee, Philippe Morath

We investigate the masses of the lowest c\bar{c} states, the J/psi and eta_c, in nuclear matter using QCD sum rules. Up to dimension four, the differences between the operator product expansions in vacuum and in medium arise from the density-dependent change in the gluon condensate and from a new contribution proportional to the nucleon expectation value of

Remo Garattini

A simple model of spacetime foam, made by $N$ wormholes in a semiclassical approximation, is taken under examination. We show that the qualitative behaviour of the fluctuation of the metric conjectured by Wheeler is here reproduced.

G. J. Gounaris, F. M. Renard

We investigate the potential of a muon collider for testing the presence of anomalous Higgs boson couplings. We consider the case of a light (less than $160 GeV$) Higgs boson and study the effects on the Higgs branching ratios and total width, which could be induced by the non standard couplings created by a class of dim=6 $SU(3)\times SU(2)\times U(1)$ gaug

A. V. Leonidov, D. M. Ostrovsky

The transverse energy flow generated by minijets in hadron and nuclear collisions into a given rapidity window in the central region is calculated in the next-to-leading (NLO) order in QCD at RHIC and LHC energies. The NLO transverse energy production in pp collisions cross sections are larger than the LO ones by the factors of K_{RHIC} ~ 1.9 and K_{LHC} ~ 2

Peter B. Renton

The couplings of the fermions to the Z boson are of great importance in establishing the validity of the Standard Model and in looking for physics beyond it. The couplings of the b-quark to the Z boson have been the subject of much experimental study and theoretical interpretation. The apparent excess in the value of $\Rbbz$, the ratio of the partial width o

L. I. Tsaregorodtsev, N. N. Medvedev

The radiation spectrum of a classical charged particle (electron) moving in the de Sitter universe, has been calculated. The de Sitter metric is taken in the quasi-Euclidean Robertson-Walker form. It is shown that in the de Sitter spacetime an electron radiates as if it moved in a constant and homogeneous electric field with the strength vector E collinear t

E. Louis, F. Guinea, M. P. Lopez-Sancho, J. A. Verges

The interactions between holes in the Hubbard model, in the low density, intermediate to strong coupling limit, are investigated by systematically improving mean field calculations. The Configuration Interaction basis set is constructed by applying to local Unrestricted Hartree-Fock configurations all lattice translations and rotations. It is shown that this

Amihay Hanany, Yang-Hui He

We study orbifolds of ${\cal N} = 4$ U(n) super-Yang-Mills theory given by discrete subgroups of SU(2) and SU(3). We have reached many interesting observations that have graph-theoretic interpretations. For the subgroups of SU(2), we have shown how the matter content agrees with current quiver theories and have offered a possible explanation. In the case of

V. Suneeta, R. K. Kaul, T. R. Govindarajan

The entropy of the BTZ black hole is computed in the Ponzano-Regge formulation of three-dimensional lattice gravity. It is seen that the correct semi-classical behaviour of entropy is reproduced by states that correspond to all possible triangulations of the Euclidean black hole.

Peter A. Clarkson, Nalini Joshi, Andrew Pickering

The second Painlevé hierarchy is defined as the hierarchy of ordinary differential equations obtained by similarity reduction from the modified Korteweg-de Vries hierarchy. Its first member is the well-known second Painlevé equation, P2. In this paper we use this hierarchy in order to illustrate our application of the truncation procedure in Painlevé analysi

Harvey R. Brown, Erik Sjoeqvist, Guido Bacciagaluppi

It is argued that the topological approach to the (anti-)symmetrisation condition for the quantum state of a collection of identical particles, defined in the `reduced&#39; configuration space, is particularly natural from the perspective of de Broglie-Bohm pilot-wave theory.

S. B. Bravyi, A. Yu. Kitaev

A new type of local-check additive quantum code is presented. Qubits are associated with edges of a 2-dimensional lattice whereas the stabilizer operators correspond to the faces and the vertices. The boundary of the lattice consists of alternating pieces with two different types of boundary conditions. Logical operators are described in terms of relative ho

T. D. Shoppa, S. E. Koonin, R. Seki

We investigate quantal perturbations of the interferometric correlations of charged bosons by the Coulomb field of an instantaneous, charged source. The source charge increases the apparent source size by weakening the correlation at non-zero relative momenta. The effect is strongest for pairs with a small total momentum and is stronger for kaons than for pi

P. Navratil, B. R. Barrett, W. Gloeckle

We discuss the appearance of spurious solutions of few-body equations for Faddeev amplitudes. The identification of spurious states, i.e., states that lack the symmetry required for solutions of the Schroedinger equation, as well as the symmetrization of the Faddeev equations is investigated. As an example, systems of three and four electrons, bound in a har

P. Bozek

We solve the in-medium T-matrix equation at finite temperature including the off-shell propagation of nucleons. In this way a self-consistent spectral function for the nucleons is obtained. The results are compared to a calculation using the quasiparticle approximation in the T-matrix equation. Also the effective in-medium cross sections for the two cases ar

J. Ryckebusch, D. Debruyne, W. Van Nespen

The polarization degrees-of-freedom in electronuclear two-nucleon knockout reactions are discussed. Model calculations for the unpolarized $^{16}$O(e,e$&#39;$pp) cross sections at ($\mid \vec{q} \mid$,$ω$)=(210 MeV,300 MeV/c) are compared to recently obtained data. Predictions for the polarization observables in electronuclear two-nucleon knockout are presen

O. Yu. Denisov, S. D. Kuksa, G. I. Lykasov

The production of pions by antiproton-deuteron annihilation at rest is analyzed. Assuming the possible existence of two delta-isobars in a deuteron some enhancement in the distribution over the invariant mass of two negative charged pions is predicted.

J. Smejkal, E. Truhlik, F. C. Khanna

The transition operator for the radiative capture of mesons mu minus by protons is constructed starting from a chiral Lagrangian of the N-pi-rho-a_1-omega system obtained within the approach of hidden local symmetries. The transition operator is gauge invariant and satisfies exactly the CVC and PCAC equations.

Silviu Olariu

The neutron yields observed in inertial confinement fusion experiments for higher convergence ratios are about two orders of magnitude smaller than the neutron yields predicted by one-dimensional models, the discrepancy being attributed to the development of instabilities. We consider the possibility that ignition and a moderate gain could be achieved with e

Pierluigi Contucci, Peter Kleban, Andreas Knauf

We analyze the Farey spin chain, a one dimensional spin system with effective interaction decaying like the squared inverse distance. Using a polymer model technique, we show that when the temperature is decreased below the (single) critical temperature T_c=1/2, the magnetization jumps from zero to one.

Stephen Montgomery-Smith, Alexander R. Pruss

We give a comparison inequality that allows one to estimate the tail probabilities of sums of independent Banach space valued random variables in terms of those of independent identically distributed random variables. More precisely, let X_1,...,X_n be independent Banach-valued random variables. Let I be a random variable independent of X_1,...,X_n and unifo

Huai-Dong Cao, Bennett Chow

This article reports recent developments of the research on Hamilton&#39;s Ricci flow and its applications.

Stefaan Vaes

In this paper we present a generalization of the Radon-Nikodym theorem proved by Pedersen and Takesaki. Given a normal, semifinite and faithful (n.s.f.) weight $ϕ$ on a von Neumann algebra M and a strictly positive operator $δ$, affiliated with M and satisfying a certain relative invariance property with respect to the modular automorphism group $σ^ϕ$ of $ϕ$

Hursit Onsiper

In this paper, we investigate the moduli of surfaces of general type admitting genus 2 fibrations with irregularity q = g_b + 1, where g_b >= 2 is the genus of the base. We prove that smooth fibrations are parametrized by a unique component in the moduli space. The same result applies to nonsmooth fibrations with special values of g_b. In the general case, w

Marco Andreatta

Let X be a smooth projective variety of dimension n on which a simple Lie group G acts regularly and non trivially. Then X is not minimal in the sense of the Minimal Model Program. In the paper we work out a classification of X via the Minimal Model Program under the assumption that the dimension of X is small with the respect to the dimension of G. More pre

Hai-cang Ren

The path integral of a gauge theory is studied in Coulomb-like gauges. The Christ-Lee terms of operator ordering are reproduced {\it{within}} the path integration framework. In the presence of fermions, a new operator term, in addition to that of Christ-Lee, is discovered. Such kind of terms is found to be instrumental in restoring the invariance of the effe

Alfredo Herrera-Aguilar, Oleg Kechkin

Using the Ernst potential formulation we construct all it finite symmetry transformations which preserve asymptotics of the bosonic fields of the (d+3)--dimensional low--energy heterotic string theory compactified on a d--torus. We combine all the dynamical variables into a single (d+1)X(d+1+n)--dimensional matrix potential which linearly transforms under th

M. Gattobigio, A. Liguori, M. Mintchev

The nonlinear Schrodinger equation on the half line with mixed boundary condition is investigated. After a brief introduction to the corresponding classical boundary value problem, the exact second quantized solution of the system is constructed. The construction is based on a new algebraic structure, which is called in what follows boundary algebra and whic

Prasanta K. Tripathy

We study the supersymmetric extension of the gauged $ O(3) $ sigma model in $ 2+1 $ dimensions and find the supersymmetry algebra. We also discuss soliton solutions in case the Maxwell term is replaced by the Born-Infeld term. We show that by appropriate choice of the potential, the self-dual equations in the Born-Infeld case coincide with those of the Maxwe

H. Kleinert

We show that in field systems with U(1)-symmetry, first-order transitions are nucleated by vortex lines, not bubbles, thus calling for a reinvestigation of the Kibble mechanism for the phase transition of the early universe.

V. P. Gusynin, A. W. Schreiber, T. Sizer, A. G. Williams

In this paper we study dynamical chiral symmetry breaking in dimensionally regularized quenched QED within the context of Dyson-Schwinger equations. In D < 4 dimensions the theory has solutions which exhibit chiral symmetry breaking for all values of the coupling. To begin with, we study this phenomenon both numerically and, with some approximations, analyti

L. Martinovic

A residual gauge symmetry, exhibited by light-front gauge theories quantized in a finite volume, is analyzed at the quantum level. Unitary operators, which implement the symmetry, transform the trivial Fock vacuum into an infinite set of degenerate coherent-state vacua. A fermionic component of the vacuum emerges naturally without the need to introduce a Dir

John R. Klauder

A redesigned starting point for covariant ϕ^4_n, n\ge 4, models is suggested that takes the form of an alternative lattice action and which may have the virtue of leading to a nontrivial quantum field theory in the continuum limit. The lack of conventional scattering for such theories is understood through an interchange of limits.

Nuno D. Antunes, Luis M. A. Bettencourt, Wojciech H. Zurek

We report the first large scale numerical study of the dynamics of the second order phase transition of a U(1) $λϕ^4$ theory in three spatial dimensions. The transition is induced by a time-dependent temperature drop in the heat bath to which the fields are coupled. We present a detailed account of the dynamics of the fields and vortex string formation as a

M. Batista, R. J. M. Covolan

The Regge-Mueller formalism is used to describe the inclusive spectrum of the proton in $p p$ collisions. From such a description the energy dependences of both average inelasticity and leading proton multiplicity are calculated. These quantities are then used to establish the connection between the average charged particle multiplicities measured in {\bf $e

L. H. Orr, T. Andre, T. Stelzer

Top quark events in hadron collisions often contain additional hadronic jets from gluon bremsstrahlung off the quarks and gluons in the hard subprocesses. Such extra jets must be taken into account in attempts to reconstruct the momentum of the top quark from those of its decay products. We have performed a complete calculation of gluon radiation in top prod

Lynne H. Orr, W. J. Stirling

The production of a pair of jets with large rapidity separation in hadron-hadron collisions, and of forward jets in deep inelastic scattering, can in principle be used to test the predictions of the BFKL equation. However in practice kinematic constraints lead to a strong suppression of BFKL effects for these processes. This is illustrated using a BFKL Monte

A Anselm, N Dombey

We discuss the possibility that fermions bind due to Higgs or pseudoscalar exchange. It is reasonable to believe on qualitative grounds that this can occur for fermions with a mass larger than 800-900 GeV. An exchange of a pseudoscalar boson leads in the non-relativistic limit to an unacceptable potential which behaves like 1/r^3 at the origin. We show that

Wojciech Krolikowski

An explicit form of charged--lepton mass matrix, predicting $ m_τ= 1776.80 $~MeV from the experimental values of $ m_e $ and $ m_μ$ (in good agreement with the experimental figure $ m_τ= 1777.05^{+0.29}_{-0.26}$ MeV), is applied to three neutrinos $ν_e $, $ν_μ$, $ν_τ$ in order to correlate tentatively their masses and mixing parameters. While for charged lep

Tetsuya Shiromizu, Tomoko Uesugi, Mayumi Aoki

We study the excited states of the Q-balls by performing stationary perturbation on the spherical Q-balls. We find the exact solution of the stationary perturbation of the global Q-ball with thin wall approximation. For local Q-balls we solve the equations of motion for the perturbative part approximately by using expansion about the coupling constant. Furth

M. C. Gonzalez-Garcia

I review the status of neutrino masses and mixings in the light of the solar and atmospheric neutrino data. The result from the LSND experiment and the possible role of neutrinos as hot dark matter are also included. I also discuss the simplest schemes proposed to reconcile these data which include a light sterile neutrino in addition to the three standard o

S. Alekhin, V. Borodulin, A. Celikel, M. Kantar

The recent proposals concerning the usage of the real polarized gamma beam, obtained by the Compton backscattering of the laser photons off the electron beams from either the linear or circular accelerators were considered. The heavy quark photoproduction process giving a unique opportunity to measure polarized gluon distribution was investigated.

Jia-Sheng Xu, Hong-An Peng

We present a study of associated jpsi + gamma production through double Pomeron exchange at energies reached at the Fermilab Tevatron and CERN LHC based on the Ingelman-Schlein model for hard diffractive scattering and the factorization formalism of nonrelativistic QCD for quarkonia production. We find that this process (p + pbar \to p + pbar + jpsi + gamma

Frederic Teubert

The measurements performed at LEP and SLC have substantially improved the precision of the test of the Minimal Standard Model. The precision is such that there is sensitivity to pure weak radiative corrections. This allows to indirectly determine the top mass (\mt=161$\pm$8 GeV), the W-boson mass (\MW=80.37$\pm$0.03 GeV), and to set an upper limit on the the

H. C. Eggers, M. Greiner, P. Lipa

It has long been a puzzle how to solve random multiplicative cascade structures analytically. We present an analytical solution found recently in the form of a simple pedagogical example of the general case.

I. Ivanisevic, V. Lumelsky

This paper discusses the feasibility of using configuration space (C-space) as a means of visualization and control in operator-guided real-time motion of a robot arm manipulator. The motivation is to improve performance of the human operator in tasks involving the manipulator motion in an environment with obstacles. Unlike some other motion planning tasks,

H. T. Kung, S. Y. Wang

A TCP trunk is an IP tunnel under TCP control, capable of carrying packets from any number of user flows. By exploiting properties of TCP, a TCP trunk provides elastic and reliable transmission over a network, and automatically shares the network fairly with other competing trunks. Moreover, by aggregating user flows into a single trunk flow, TCP trunking ca

J. P. Martin-Flatin

In this paper, we show how Web technologies can be used effectively to (i) address some of the deficiencies of traditional IP network management platforms, and (ii) render these expensive platforms redundant. We build on the concept of embedded management application, proposed by Wellens and Auerbach, and present two models of network management application

L. Sheng, D. N. Sheng, C. S. Ting

The double-exchange model for the Mn oxides with orbital degeneracy is studied with including on-site Coulomb repulsion, Jahn-Teller (J-T) coupling and doping-induced disorder. In the strong interaction limit, it is mapped onto a single-band Anderson model, in which all scattering mechanisms can be treated on an equal footing. A sharp rise in the mean square

Antonino Marco Saitta, Stefano de Gironcoli, Stefano Baroni

The electronic and optical properties of (Zn,Mg)(S,Se) wide-gap solid solutions are studied using ab initio techniques and starting from the previously determined atomistic structure of the alloy. Compositional disorder is shown to close substantially the gap with respect to the predictions of the virtual-crystal approximation. The bowing of the fundamental

Maria de Sousa Vieira

We show that chaos is present in the symmetric two-block Burridge-Knopoff model for earthquakes. This is in contrast with previous numerical studies, but in agreement with experimental results. In this system, we have found a rich dynamical behavior with an unusual route to chaos. In the three-block system, we see the appearance of synchronized chaos, showin

T. Lofwander, G. Johansson, V. S. Shumeiko, G. Wendin

We study theoretically the ac Josephson effect in voltage biased planar junctions of d-wave superconductors. For some orientations of the superconductors a current peak is found at finite voltage in the current-voltage characteristics. We pick out the relevant physical processes and write down an analytical formula for the current which clearly shows how the

Maksim Skorobogatiy

The nature of physical processes can depend substantially on the dimensionality of a system. One such example are buckling instabilities, which arise from the competition between axial compression and bending in elastic filaments. Thus, coiling of a jet of viscous fluid falling on a substrate (honey poured on a toast) \cite{maha1,griffiths} behaves quite dif

Christian Gruber

In this review we present a biased review of the ground state properties of the Falicov-Kimball models in 1,2 and infinite dimensions, considering either fermions or hard-core bosons. In particular we want to show the very rich structure that these models exhibit and to point out the analogies and differences associated with the statistic of the quantum part

Shu-dong Zhang

We study the scaling behaviors of a time-dependent fiber-bundle model with local load sharing. Upon approaching the complete failure of the bundle, the breaking rate of fibers diverges according to $r(t)\propto (T_f-t)^{-ξ}$, where $T_f$ is the lifetime of the bundle, and $ξ\approx 1.0$ is a quite universal scaling exponent. The average lifetime of the bundl

Branislav Nikolic, Philip B. Allen

We calculate the conductance of a circular constriction of radius $a$ in an insulating diaphragm which separates two conducting half-spaces characterized by the mean free path $\ell$. Our exact result interpolates between the Maxwell conductance in diffusive ($\ell \ll a$) and the Sharvin conductance in ballistic ($\ell \gg a$) transport regime. Following th

John Schliemann, Franz G. Mertens

We examine spin vortices in ferromagnetic quantum Heisenberg models with planar anisotropy on two-dimensional lattices. The symmetry properties and the time evolution of vortices built up from spin-coherent states are studied in detail. Although these states show a dispersion typical for wave packets, important features of classical vortices are conserved. M

Saburo Higuchi

A Hamiltonian cycle of a graph is a closed path that visits every vertex once and only once. It has been difficult to count the number of Hamiltonian cycles on regular lattices with periodic boundary conditions, e.g. lattices on a torus, due to the presence of winding modes. In this paper, the exact number of Hamiltonian cycles on a random trivalent fat grap

A. C. Goncalves, M. -P. Veron-Cetty, P. Veron

In a previous paper (Veron et al. 1997) we presented medium resolution (3.4 A FWHM) spectroscopic observations of 15 &#34;transition objects&#34;, selected for having an ambiguous location in the Veilleux & Osterbrock (1987) diagnostic diagrams, and showed that most of them were in fact &#34;composite&#34;, this being due to the simultaneous presence on the

John Scalo

Observations have not yielded convincing results concerning the form of the stellar initial mass function (IMF) or its variations in space and time, so it is proposed that theoretical models may provide useful guidance. Several classes of theoretical models for the physics controlling the IMF are reviewed, emphasizing the dependence of the results on the pro

Elizabeth J. Barton, Benjamin C. Bromley, Margaret J. Geller

We use self-consistent N-body models, in conjunction with models of test particles moving in galaxy potentials, to explore the initial effects of interactions on the rotation curves of spiral galaxies. Using nearly self-consistent disk/bulge/halo galaxy models (Kuijken & Dubinski 1995), we simulate the first pass of galaxies on nearly parabolic orbits; we va

C. J. Taylor, J. R. Thorstensen, J. Patterson

We present time-resolved spectroscopy and photometry of the bright cataclysmic variable LS Peg (= S193). The Balmer lines exhibit broad, asymmetric wings Doppler-shifted by about 2000 km/s at the edges, while the HeI lines show phase-dependent absorption features strikingly similar to SW Sextantis stars, as well as emission through most of the phase. The CII

M. Breger, A. A. Pamyatnykh, H. Pikall, R. Garrido

This paper examines the mode identification and presents pulsation models for FG Vir, for which 24 frequencies have been detected. Histograms of the frequency spacings show peaks which are identified with adjacent radial orders and rotational splitting. Pulsational $\ell$ values are deduced for eight modes by comparing the observed photometric phase lags bet

C. H. Ishwara-Chandra, D. J. Saikia, V. K. Kapahi, P. J. McCarthy

We present total-intensity and linear-polarization observations made with the Very Large Array at $λ$20 and 6 cm of a representative sample of 42 radio galaxies and quasars selected from the Molonglo Complete Sample. The sources have been chosen to be of large size to probe the depolarizing medium on these scales using our present data and later with observa

John G. Spitzak, Stephen E. Schneider

In a 21 cm neutral hydrogen survey of approximately 55 sq deg out to a redshift of cz=8340 km/s, we have identified 75 extragalactic HI sources. These objects comprise a well-defined sample of extragalactic sources chosen by means that are independent of optical surface brightness selection effects. In this paper we describe the Arecibo survey procedures and