June 2002 arXiv papers — page 20

S. R. Saha, H. Sugawara, T. Namiki, Y. Aoki

The effect of uniaxial pressure (P_u) on the magnetic susceptibility (X), magnetization (M), and magnetoresistance (MR) of the heavy-fermion metamagnet CeRu2Si2 has been investigated. For the magnetic field along the tetragonal c axis, it is found that characteristic physical quantities, i.e., the temperature of the susceptibility maximum (T_max), the pagama

C. J. Bolech, S. S. Kancharla, G. Kotliar

We explore the use of exact diagonalization methods for solving the self consistent equations of the cellular dynamical mean field theory (CDMFT) for the one dimensional regular and extended Hubbard models. We investigate the nature of the Mott transition and convergence of the method as a function of cluster size as well as the optimal allocation of computa

L. Tessieri

We study the delocalisation transition which takes places in one-dimensional disordered systems when the random potential exhibits specific long-range correlations. We consider the case of weak disorder; using a systematic perturbative approach, we show how the delocalisation transition brings about a change of the scaling law of the inverse localisation len

John D. Weeks

By combining the upper and lower bounds to the free energy as given by the Gibbs inequality for two systems with the same intermolecular interactions but with external fields differing from each other only in a finite region of space Gamma, we show that the corresponding equilibrium densities must also differ from each other somewhere in Gamma. We note that

Rastko Sknepnek, Thomas Vojta

We study the quantum phase transition in the three-dimensional disordered itinerant antiferromagnet by Monte-Carlo simulations of the order-parameter field theory. We find strong evidence for the transition being controlled by an infinite-randomness fixed point: The dynamical scaling is activated, i.e., the logarithm of the energy scales like a power of the

A. D. Chernin

The structure and origin of the Friedmann integrals are analyzed within the framework of large extra dimensions proposed by Arkani-Hamed et all. (1998). It is demonstrated that the integrals might emerge from extra-dimension physics and reveal its signature. In the case of two extra dimensions, the integrals are expressed via the product $M_* R$ of the only

R. Paul Butler, Geoffrey W. Marcy, Steven S. Vogt, C. G. Tinney

The Geneva group has reported two Saturn-mass planets orbiting HD 83443 (K0V) with periods of 2.98 and 29.8 d. The two planets have raised interest in their dynamics because of the possible 10:1 orbital resonance and the strong gravitational interactions. We report precise Doppler measurements of HD 83443 obtained with the Keck/HIRES and the AAT/UCLES spectr

Robin Ciardullo, John J. Feldmeier, George H. Jacoby, Rachel Kuzio de Naray

We report the results of [OIII] lambda 5007 surveys for planetary nebulae (PNe) in NGC 2403, 3115, 3351, 3627, 4258, and 5866. Using on-band/off-band [OIII] and H-alpha images, we identify samples of PNe in these galaxies and derive distances using the planetary nebula luminosity function (PNLF). We then combine these measurements with previous data to compa

Leonidas A. Moustakas, R. Benton Metcalf

The Cold Dark Matter (CDM) model for galaxy formation predicts that a significant fraction of mass in the dark matter haloes that surround L L* galaxies is bound in substructures of mass 1E4-1E7Msun. The number of observable baryonic substructures (such as dwarf galaxies and globular clusters) falls short of these predictions by at least an order of magnitud

F. Bacciotti, T. P. Ray, R. Mundt, J. Eisloeffel

We have carried out a kinematical, high angular resolution (~ 0".1) study of the jet from DG Tau within 0."5 from the source (or 110 AU along this flow). We analysed line profiles extracted from a set of seven spectra taken with STIS on board the Hubble Space Telescope, with the slits parallel to the jet axis but displaced transversely every 0".0

Jeremy Heyl

Andersson et al. and Bildsten proposed that the spin of accreting neutron stars is limited by removal of angular momentum by gravitational radiation which increases dramatically with the spin frequency of the star. Both Bildsten and Andersson et al. argued that the r-modes of the neutron star for sufficiently quickly rotating and hot neutron stars will grow

H. Olofsson, D. Gonzalez Delgado, F. Kerschbaum, F. L. Schoeier

We have determined mass loss rates and gas expansion velocities for a sample of 69 M-type irregular (IRV; 22 objects) and semiregular (SRV; 47 objects) AGB-variables using a radiative transfer code to model their circumstellar CO radio line emission. We believe that this sample is representative for the mass losing stars of this type. The (molecular hydrogen

R. R. Ross, A. C. Fabian, D. R. Ballantyne

Multiple reflection of X-rays may be important when an accretion disc and its hot corona have a complicated geometry, or if returning radiation due to gravitational light bending is important, or in emission from a funnel such as proposed in some gamma-ray burst models. We simulate the effects of multiple reflection by modifying the boundary condition for an

M. Cervino

In this contribution, I present the 90% confidence limits on the diagnostic diagrams of EW(WR bump) and L(WR bump)/L(Hb) ratio vs. EW(Hb) resulting from evolutionary synthesis models that include the statistical dispersion due to finite stellar populations in real star forming regions.

A. Cimatti, M. Mignoli, E. Daddi, L. Pozzetti

The K20 survey is an ESO VLT optical and near-infrared spectroscopic survey aimed at obtaining spectral information and redshifts of a complete sample of about 550 objects to K_s\leq20.0 over two independent fields with a total area of 52 arcmin^2. In this paper we discuss the scientific motivation of such a survey, we describe the photometric and spectrosco

F. Herpin, J. R. Goicoechea, J. R. Pardo, J. Cernicharo

We have observed with the 30-m IRAM telescope, the CSO telescope and the ISOsatellite (Infrared Space Observatory) the rotational lines of CO at millimeter, submillimeter and far infrared wavelengths in the direction of C-rich stellar objects at different stages of evolution : CRL 2688 (a very young Proto-Planetary Nebula), CRL 618 (a Proto-Planetary Nebula)

R. X. Xu, H. G. Wang, G. J. Qiao

According to two estimated relations between the initial period and the dynamo-generated magnetic dipole field of pulsars, we calculate the statistical distributions of pulsar initial periods. It is found that proto-pulsars are very likely to have rotation periods between 20 and 30 ms, and that most of the pulsars rotate initially at a period < 60 ms.

Nicole Homeier, John S. Gallagher, Anna Pasquali

We investigate the star cluster system in the starburst galaxy NGC 7673 using archival Hubble Space Telescope WFPC2 broad-band images. For the first time we are able to examine the internal structures of the prominent optical clumps in this galaxy. The clumps are composed of young stars, 16-33 % of which are in bright star clusters. We identify 268 star clus

A. Muecke, R. J. Protheroe, R. Engel, J. P. Rachen

We calculate the spectral energy distribution (SED) of electromagnetic radiation and the spectrum of high energy neutrinos from BL Lac objects in the context of the Synchrotron Proton Blazar Model. In this model, the high energy hump of the SED is due to accelerated protons, while most of the low energy hump is due to synchrotron radiation by co-accelerated

Michael D. Gregg, Robert H. Becker, Richard L. White, Gordon T. Richards

In an ongoing infrared imaging survey of quasars at Keck Observatory, we have discovered that the z=1.285 quasar SDSS J233646.2-010732.6 comprises two point sources with a separation of 1.67&#34;. Resolved spectra show that one component is a standard quasar with a blue continuum and broad emission lines; the other is a broad absorption line (BAL) quasar, sp

Scott W. Randall, Craig L. Sarazin, Paul M. Ricker

In the standard Cold Dark Matter model of structure formation, massive clusters form via the merger of smaller clusters. N-body/hydrodynamical simulations of merging galaxy clusters have shown that mergers can temporarily boost the X-ray luminosity and temperature of the merged cluster above the equilibrium values for the merged system. The cumulative effect

Douglas A. Swartz, Kajal K. Ghosh, Michael L. McCollough, Thomas G. Pannuti

A Chandra X-Ray Observatory ACIS-S imaging observation is used to study the population of X-ray sources in the nearby Sab galaxy M81 (NGC 3031). A total of 177 sources are detected with 124 located within the D25 isophote to a limiting X-ray luminosity of 3e36 ergs/cm2/s. Source positions, count rates, luminosities in the 0.3-8.0 keV band, limiting optical m

Adam Burrows, R. S. Ram, Peter Bernath, C. M. Sharp

In this paper, we calculate new line lists and opacities for the 12 bands of the A$^6Σ^{+}$ -- X$^6Σ^{+}$ transitions of the CrH molecule. Identified in objects of the new L dwarf spectroscopic class (many of which are brown dwarfs), as well as in sunspots, the CrH molecule plays an important role in the diagnosis of low-temperature atmospheres. As a tentati

D. Q. Lamb, G. R. Ricker, J. -L. Atteia, K. Hurley

The {\it HETE-2} (hereafter \HETE) French Gamma Telescope (FREGATE) and the Wide-field X-ray Monitor (WXM) instruments detected a short ($t_{50} = 360$ msec in the FREGATE 85-300 keV energy band), hard gamma-ray burst (GRB) that occurred at 1578.72 SOD (00:26:18.72 UT) on 31 May 2002. The WXM flight localization software produced a valid location in spacecra

G. G. Pavlov, V. E. Zavlin, D. Sanwal

The outstanding capabilities of the Chandra X-ray observatory have greatly increased our potential to observe and analyze thermal radiation from the surfaces of neutron stars (NSs). Such observations allow one to measure the surface temperatures and confront them with the predictions of the NS cooling models. Detection of gravitationally redshifted spectral

STAR Collaboration

Azimuthal anisotropy ($v_2$) and two-particle angular correlations of high $p_T$ charged hadrons have been measured in Au+Au collisions at $\sqrt{s_{NN}}$=130 GeV for transverse momenta up to 6 GeV/c, where hard processes are expected to contribute significantly. The two-particle angular correlations exhibit elliptic flow and a structure suggestive of fragme

Takemi Okamoto, Wayne Hu

We develop the formalism necessary to study four-point functions of the cosmic microwave background (CMB) temperature and polarization fields. We determine the general form of CMB trispectra, with the constraints imposed by the assumption of statistical isotropy of the CMB fields, and derive expressions for their estimators, as well as their Gaussian noise p

M. Geha, P. Guhathakurta, R. van der Marel

Keck/ESI spectroscopy is presented for six Virgo Cluster dwarf elliptical (dE) galaxies. The mean line-of-sight velocity and velocity dispersion are resolved as a function of radius along the major axis of each galaxy, nearly doubling the total number of dEs with spatially-resolved stellar kinematics. None of the observed objects shows evidence of strong rot

Jinwu Ye

By applying the simple and effective method developed to study the the gauge-invariant fermion Green function in $ 2+1 $ dimensional non-compact QED, we study the gauge-invariant Green function in $ 3+1 $ dimensional QED and $ 2+1 $ dimensional non-compact Chern-Simon theory. We also extend our results to the corresponding $ SU(M) $ non-Abelian gauge theorie

Ehud Altman, Assa Auerbach

We follow up on a recent suggestion by C. Orzel et. al., Science, 291, 2386 (2001), whereby bosons in an optical lattice would be subjected to a sudden parameter change from the Mott to the superfluid phase. We analyze the Bose Hubbard model with a modified coherent states path integral which can escribe - both - phases. The saddle point theory yields collec

Marcus Spradlin, Anastasia Volovich

In type IIB light-cone superstring field theory, the cubic interaction has two pieces: a delta-functional overlap and an operator inserted at the interaction point. In this paper we extend our earlier work hep-th/0204146 by computing the matrix elements of this operator in the oscillator basis of pp-wave string theory for all mu p^+ alpha'. By evaluating the

Alberto Santambrogio, Daniela Zanon

In a {\cal N}=1 superspace formulation of {\cal N}=4 Yang-Mills theory we obtain the anomalous dimensions of chiral operators with large R charge J \to \infty keeping g^2 N/J^2 finite, to all orders of perturbation theory in the planar limit. Our result proves the conjecture that the anomalous dimensions are indeed finite in the above limit. This amounts to

Felix Lev

We consider in detail an approach (proposed by the author earlier) where quantum states are described by elements of a linear space over a Galois field, and operators of physical quantities - by linear operators in this space. The notion of Galois fields (which is extremely simple and elegant) is discussed in detail and we also discuss the conditions when ou

Mark Bowick, Angelo Cacciuto, David R. Nelson, Alex Travesset

We attack generalized Thomson problems with a continuum formalism which exploits a universal long range interaction between defects depending on the Young modulus of the underlying lattice. Our predictions for the ground state energy agree with simulations of long range power law interactions of the form 1/r^{gamma} (0 < gamma < 2) to four significant digits

J. E. Prieto, F. Heigl, O. Krupin, G. Kaindl

X-ray absorption spectra in a wide energy range around the 4d-4f excitation threshold of Gd were recorded by total electron yield from in-plane magnetized Gd metal films. Matching the experimental spectra to tabulated absorption data reveals unprecedented short light absorption lengths down to 3 nm. The associated real parts of the refractive index for circu

Tai-Chung Cheng, Pei-Ming Ho, Mao-Chuang Yeh

We extend the perturbative approach developed in an earlier work to deal with Lagrangians which have arbitrary higher order time derivative terms for both bosons and fermions. This approach enables us to find an effective Lagrangian with only first time derivatives order by order in the coupling constant. As in the pure bosonic case, to the first order, the

Wilhelm I. Fushchych, Ivan Yu. Krivsky

The mass operator M is introduced as an independent dynamical variable which is taken as the translation generator P_4 of the inhomogenous De Sitter group. The classification of representations of the algebra P(1,4) of this group is performed and the corresponding P(1,4) invariant equations for variable-mass particles are written out. In this way we have suc

Fiona Hoyle, Michael S. Vogeley, J. Richard Gott, Michael Blanton

We present the topology of a volume-limited sample of 11,884 galaxies, selected from an apparent-magnitude limited sample of over 100,000 galaxies observed as part of the Sloan Digital Sky Survey (SDSS). The data currently cover three main regions on the sky: one in the Galactic north and one in the south, both at zero degrees declination, and one area in th

B. V. Geshkenbein

The ALEPH data on hadronic tau-decay is throughly analysed in the framework of QCD. The perturbative calculations are performed in 1-4-loop approximation. The analytical properties of the polarization operators are used in the whole complex q^2 plane. It is shown that the QCD prediction for R_{tau} agrees with the measured value R_{tau} not only for conventi

R. Kerner, R. B. Mann

We obtain a new exact equilibrium solution to the N-body problem in a one-dimensional relativistic self-gravitating system. It corresponds to an expanding/contracting spacetime of a circle with N bodies at equal proper separations from one another around the circle. Our methods are straightforwardly generalizable to other dilatonic theories of gravity, and p

Cong-Feng Qiao

The double J/psi production in p\bar{p} collision is revisited. It is found that the J/ψpair production rate at leading order with p_T > 4 GeV in conventional scheme is larger than the rate derived from color-octet mechanism by a factor of five. As the double J/psi production is shown to be attainable with data yet collected at the Tevatron detectors, experi

Frank Sottile, Thorsten Theobald

Let d_{k,n} and #_{k,n} denote the dimension and the degree of the Grassmannian G_{k,n} of k-planes in projective n-space, respectively. For each k between 1 and n-2 there are 2^{d_{k,n}} \cdot #_{k,n} (a priori complex) k-planes in P^n tangent to d_{k,n} general quadratic hypersurfaces in P^n. We show that this class of enumerative problem is fully real, i.

E. Eckhart

We report on a search for charmless hadronic B decays to the three-body final states, K0S h+ pi-, K+ h- pi0, K0S h+ pi0 (h+- denotes a charged pion or kaon), and their charge conjugates, using 13.5 fb^{-1} of integrated luminosity produced with center-of-mass energies near 10.6 GeV, and collected with the CLEO detector. We observe the decay B --> K0 pi+ pi-

Robert W. Johnson

Conventional lattice gauge theory assigns the lowest spin compatible with the symmetry channel of a given operator to the state coupling to that operator. Operators on a cubic lattice, however, are only defined on angles of pi/2, hence states with spin equal modulo 4 may overlap significantly. This paper explores a new technique for generating lattice operat

J. Cayssol, T. Kontos, G. Montambaux

We investigate the ground state current of an isolated hybrid normal/superconducting ring (NS ring), threaded by an Aharonov-Bohm magnetic flux. We calculate the excitation spectrum of the ring for any values of the lengths of the normal metal and of the superconductor. We describe the nonlinear flux dependence of the energy levels above and below the gap ed

Paola Gori-Giorgi, John P. Perdew

We construct analytic formulas that represent the coupling-constant-averaged pair distribution function $\gxcav(r_s,ζ, k_Fu)$ of a uniform electron gas with density parameter $r_s =(9π/4)^{1/3}/k_F$ and relative spin polarization $ζ$ over the whole range $0<r_s<\infty$ and $-1<ζ<1$, with energetically-unimportant long range ($u\to \infty$) oscillations avera

E. -M. Ilgenfritz, B. V. Martemyanov, M. Müller-Preussker, S. Shcheredin

Finite temperature Euclidean SU(2) lattice gauge fields generated in the confinement phase close to the deconfinement phase transition are subjected to cooling. The aim is to identify long-living, almost-classical local excitations which carry (generically non-integer) topological charge. Two kinds of spatial boundary conditions (fixed holonomy and standard

Michael Baake, Bernd Sing

Unlike the (classical) Kolakoski sequence on the alphabet {1,2}, its analogue on {1,3} can be related to a primitive substitution rule. Using this connection, we prove that the corresponding bi-infinite fixed point is a regular generic model set and thus has a pure point diffraction spectrum. The Kolakoski-(3,1) sequence is then obtained as a deformation, wi

V. K. Dubrovich, M. Yu. Khlopov

Primordial superheavy particles, considered as the source of Ultra High Energy Cosmic Rays (UHECR) and produced in local processes in the early Universe, should bear some strictly or approximately conserved charge to be sufficiently stable to survive to the present time. Charge conservation makes them to be produced in pairs, and the estimated separation of

Peter Lee, Sanefumi Moriyama, Jongwon Park

We use the supergravity modes to clarify the role of the prefactor in the light-cone superstring field theory on PP-wave background. We verify some of the proposals of the recent paper hep-th/0205089 and give further evidence for the correspondence between N=4 SYM gauge theory and string theory on PP-wave. We also consider energy-preserving processes and fin

ZEUS Collaboration

Diffractive production of D*+-(2010) mesons in deep inelastic scattering has been measured with the ZEUS detector at HERA using an integrated luminosity of 44.3 pb-1. Diffractive charm production is identified by the presence of a large rapidity gap in the final state of events in which a D*+-(2010) meson is reconstructed in the decay channel D*+ -> (D0 -> K

Clemens Berger, Ieke Moerdijk

We give sufficient conditions for the existence of a model structure on operads in an arbitrary symmetric monoidal model category. General invariance properties for homotopy algebras over operads are deduced.

X. Calmet

We discuss a two scalar doublets model which induces the Higgs mechanism by means of a seesaw mechanism. This model naturally predicts a light Higgs scalar whose mass is suppressed by the grand unification scale. The model predicts an intermediate scale between the electroweak symmetry breaking scale and the grand unification scale at $10^9$ GeV. Below this

S. V. Naydenov, V. D. Ryzhikov, B. V. Grinyov, E. K. Lisetskaya

For reconstruction of the spatial structure and thicknesses of complex objects and materials, it is proposed to use multi-radiography with detection of X-ray or gamma-radiation by combined detector arrays of scintillator-photodiode type. Experimental studies have been carried out of the energy dependence of sensitivity of dual-energy inspection systems based

C. Mitra, Z. Hu, P. Raychaudhuri, S. Wirth

We report on a X-ray absorption spectroscopic (XAS) study on a thin film of La0.7Ce0.3MnO3, a manganite which was previously only speculated to be an electron doped system. The measurements clearly show that the cerium is in the Ce(IV) valence state and that the manganese is present in a mixture of Mn2+ and Mn3+ valence states. These data unambiguously demon

V. I. Yukalov

The stability of solutions to evolution equations with respect to small stochastic perturbations is considered. The stability of a stochastic dynamical system is characterized by the local stability index. The limit of this index with respect to infinite time describes the asymptotic stability of a stochastic dynamical system. Another limit of the stability

Yoshiaki Koma, Miho Koma, Dietmar Ebert, Hiroshi Toki

The effective string action of the color-electric flux tube in the U(1) x U(1) dual Ginzburg-Landau (DGL) theory is studied by performing a path-integral analysis by taking into accountthe finite thickness of the flux tube. The DGL theory, corresponding to the low-energy effective theory of Abelian-projected SU(3) gluodynamics, can be expressed as s [U(1)]^{

Hua Yang, Qing Wang, Qin Lu

Parameters of Gasser Leutwyler chiral Lagrangian are proved saturated by dynamical quark self energy Sigma(k^2) in a gauge invariant, nonlocal, dynamical quark model.

Hideo Hasegawa

Dynamics of an ensemble of $N$-unit FitzHugh-Nagumo (FN) neurons subject to white noises has been studied by using a semi-analytical dynamical mean-field (DMF) theory in which the original $2 N$-dimensional {\it stochastic} differential equations are replaced by 8-dimensional {\it deterministic} differential equations expressed in terms of moments of local a

Jeeva Anandan

The conflict between the locality of general relativity, reflected in its space-time description, and the non-locality of quantum mechanics, contained in its Hilbert space description, is discussed. Gauge covariant non-local observables that depend on gauge fields and gravity as well as the wave function are used in order to try to understand and minimize th

Wilhelm I. Fushchych

In Ukrain. J. Phys., 1967, V.12, N 5, p.741-746 it was shown how, for a given (discrete) mass spectrum of elementary or hypothetical particles, it was possible to construct a non-trivial algebra G containing a Poincare algebra P as a subalgebra so that the mass operator, defined throughout the space where one of the irreducible representations G is given, is

B. Bagchi, C. Quesne

We discuss certain features of pseudo-Hermiticity and weak pseudo-Hermiticity conditions and point out that, contrary to a recent claim, there is no inconsistency if the correct orthogonality condition is used for the class of pseudo-Hermitian, PT-symmetric Hamiltonians of the type $H_β = [p + {\rm i} βν(x)]^2/2m + V(x)$.

Mendel Sachs

Two of Lanczos&#39; seminal contributions in physics that are not generally known about in the physics community are discussed and commented in relation to more recent investigations: First, his integral formulation of the Schroedinger equation that he published just before Schroedinger himself published his differential equation formulation of quantum mecha

Wilhelm I. Fushchych, Ivan Yu. Krivsky

This paper is a continuation and elaboration of our brief notice quant-ph/0206057 (Nucl. Phys. B, 1968, 7, 79) where some approach to the variable-mass problem was proposed. Here we have found a definite realization of irreducible representations of the inhomogeneous group P(1,n), the group of translations and rotations in (1+n)-dimensional Minkowski space,

Wang Xiang-bin

We show that the Innsbruck quantum teleportation experiment(Bouwmeester D et al, Nature 390, 575(1997)) can be modified by using the polarized beam splitter. In this modified scheme, Bob does not have to do any meassurement and an unknown state from Victor can be verified to be teleported to Bob from Alice by the currently exisiting technology, i.e., by usin

Apoorva Patel

Information is often encoded as an aperiodic chain of building blocks. Modern digital computers use bits as the building blocks, but in general the choice of building blocks depends on the nature of the information to be encoded. What are the optimal building blocks to encode structural information? This can be analysed by substituting the operations of addi

Alexandra Viel, K. Birgitta Whaley

We present a comparative study of the rotational characteristics of various molecule-doped 4He clusters using quantum Monte Carlo techniques. The theoretical conclusions obtained from both zero and finite temperature Monte Carlo studies confirm the presence of two different dynamical regimes that correlate with the magnitude of the rotational constant of the

Valery P. Dmitriyev

The Lorentz force can be obtained from Maxwell&#39;s equations in the Coulomb gauge provided that we assume that the electric portion of the force acted on a charge is known, and the magnetic component is perpendicular to the velocity of motion of the charged particle.

E. Miyata, M. Miki, J. Hiraga, H. Kouno

We have employed a mesh experiment for back-illuminated (BI) CCDs. BI CCDs possess the same structure to those of FI CCDs. Since X-ray photons enter from the back surface of the CCD, a primary charge cloud is formed far from the electrodes. The primary charge cloud expands through diffusion process until it reaches the potential well that is just below the e

B. Bassalleck, A. Berdoz, C. Bradtke, R. Bröders

Spin transfer observables for the strangeness-production reaction Antiproton-Proton -> Antilambda-Lambda have been measured by the PS185 collaboration using a transversely-polarized frozen-spin target with an antiproton beam momentum of 1.637 GeV/c at the Low Energy Antiproton Ring at CERN. This measurement investigates observables for which current models o

Francisco Vera

The complex branched structure of lightning induce scientists to think that dielectric breakdown is a very complicated phenomena, we will show that this is not true and that simulating the structure of lightning is an easy task, but depends strongly on boundary conditions. In this work we will introduce a new way of understanding the origin of this tortuous

A. I. Bobenko, Yu. B. Suris

We extend integrable systems on quad-graphs, such as the Hirota equation and the cross-ratio equation, to the non-commutative context, when the fields take values in an arbitrary associative algebra. We demonstrate that the three-dimensional consistency property remains valid in this case. We derive the non-commutative zero curvature representations for thes

Kira V. Khmelnytskaya, Vladislav V. Kravchenko, Vladimir S. Rabinovich

We propose a new class of fundamental solutions for the numerical analysis of boundary value problems for the Maxwell equations. We prove completeness of systems of such fundamental solutions in appropriate Sobolev spaces on a smooth boundary and support the relevancy of our approach by numerical results.

George Chavchanidze

In the present paper correspondence between non-Noether symmetries and bi-Hamiltonian structures is disscussed. We show that in regular Hamiltonian systems presence of the global bi-Hamiltonian structure is caused by symmetry of the space of solution. As an example well known bi-Hamiltonian realisation of Korteweg- De Vries equation is disscussed.

M. R. Grasselli, R. F. Streater

We show that, in finite dimensions, the only monotone metrics for which the (+1) and (-1) affine connections are mutually dual are constant multiples of Bogoliubov-Kubo-Mori metric

S. Assaf, L. Chen, T. Cheslack-Postava, B. Cooper

A dual approach to defining the triangle sequence (a type of multidimensional continued fraction algorithm, initially developed in NT/9906016) for a pair of real numbers is presented, providing a new, clean geometric interpretation of the triangle sequence. We give a new criterion for when a triangle sequence uniquely describes a pair of numbers and give the

D. Z. Djokovic, F. Szechtman

We equip the complex polynomial algebra C[t] with the involution which is the identity on C and sends t to -t. Answering a question raised by V.G. Kac, we show that every hermitian or skew-hermitian matrix over this algebra is congruent to the direct sum of 1 by 1 matrices and 2 by 2 matrices with zero diagonal. Morevover, we show that if two n by n hermitia

Ethan Bolker, Victor Guillemin, Tara Holm

In this article, we discuss some classical problems in combinatorics which can be solved by exploiting analogues between graph theory and the theory of manifolds. One well-known example is the McMullen conjecture, which was settled twenty years ago by Richard Stanley by interpreting certain combinatorial invariants of convex polytopes as the Betti numbers of

Mohamed Boucetta

The notion of Poisson manifold with compatible pseudo-metric was introduced by the author in [1]. In this paper, we introduce a new class of Lie algebras which we call a pseudo-Rieamannian Lie algebras. The two notions are strongly related: we prove that a linear Poisson structure on the dual of a Lie algebra has a compatible pseudo-metric if and only if the

Victor Rotger

Let V_D be the Shimura curve over \Q attached to the indefinite rational quaternion algebra of discriminant D. In this note we investigate the group of automorphisms of V_D and prove that, in many cases, it is the Atkin-Lehner group. Moreover, we determine the family of bielliptic Shimura curves over \bar \Q and over \Q and we use it to study the set of rati

Pietro Corvaja, Umberto Zannier

We study integral points on affine surfaces by means of a new method, relying on the Subspace Theorem. Under suitable assumptions on the divisor at infinity, we prove that the integral points are contained in a curve. As a corollary, we prove that there are only finitely many quadratic integral points on an affine curve with five points at infinity.

John A. G. Roberts, Michael Baake

We determine the symmetries and reversing symmetries within G, the group of real planar polynomial automorphisms, of area-preserving nonlinear polynomial maps L in generalised standard form, L: x&#39;=x+p(y), y&#39;=y+q(x&#39;), where p and q are polynomials. We do this by using the amalgamated free product structure of G. Our results lead to normal forms fo

Markus Reineke

We study a monoid associated to complex semisimple Lie algebras, called the quantic monoid. Its monoid ring is shown to be isomorphic to a degenerate quantized enveloping algebra. Moreover, we provide normal forms and a straightening algorithm for this monoid. All these results are proved by a realization in terms of representations of quivers, namely as the

A. Chakrabarti, R. Chakrabarti

Modified braid equations satisfied by generalized ${\hat R}$ matrices (for a {\em given} set of group relations obeyed by the elements of ${\sf T}$ matrices ) are constructed for q-deformed quantum groups $GL_q (N), SO_q (N)$ and $Sp_q (N)$ with arbitrary values of $N$. The Baxterization of ${\hat R}$ matrices, treated as an aspect complementary to the {\em

Gabriel Baditoiu, Stere Ianus

We get obstructions to existence of semi-Riemannian submersions with totally umbilic fibres.

Ilya Kapovich, Alexei Myasnikov, Paul Schupp, Vladimir Shpilrain

We give a precise definition of ``generic-case complexity&#39;&#39; and show that for a very large class of finitely generated groups the classical decision problems of group theory - the word, conjugacy and membership problems - all have linear-time generic-case complexity. We prove such theorems by using the theory of random walks on regular graphs.

Rui L. Fernandes

Several new invariants for Lie algebroids have been discovered recently. We give an overview of these invariants and establish several relationships between them.

I. Biswas, L. Brambila-Paz, P. E. Newstead

Let X be a nonsingular projective algebraic curve of genus g\ge3. We consider the moduli space M of stable bundles of fixed determinant with rank n and degree d coprime and d>n(2g-2). There is a universal bundle on XxM and we consider the direct image of this bundle on M. With the given restriction on d, this is a bundle W called the Picard bundle. Our main

A Doikou, P P Martin

We use the structural similarity of certain Coxeter Artin Systems to the Yang--Baxter and Reflection Equations to convert representations of these systems into new solutions of the Reflection Equation. We construct certain Bethe ansatz states for these solutions, using a parameterisation suggested by abstract representation theory.

Paolo Valtancoli

We consider a matrix model depending on a parameter $λ$ which permits the fuzzy sphere as a classical background.By expanding the bosonic matrices around this background ones recovers a U(1) (U(n)) noncommutative gauge theory on the fuzzy sphere. To check classical stability of this background, we look for new classical solutions of this model and find them

Horacio E. Camblong, Carlos R. Ordonez

A Green&#39;s function approach is presented for the D-dimensional inverse square potential in quantum mechanics. This approach is implemented by the introduction of hyperspherical coordinates and the use of a real-space regulator in the regularized version of the model. The application of Sturm-Liouville theory yields a closed expression for the radial ener

N. Fornengo

Neutralinos are natural candidates for cold dark matter in many realizations of supersymmetry. We briefly review our recent results in the evaluation of neutralino relic abundance and direct detection rates in a class of supergravity models.

D. Abbaneo

The current status of experimental searches for Bs oscillations is reviewed. The three ALEPH analyses have been improved since Summer 2001, and submitted for publication. The combination of all available analyses is presented and discussed.

The OPAL collaboration, G. Abbiendi

This paper describes topological searches for neutral scalar bosons S0 produced in association with a Z0 boson via the Bjorken process e+e- -> S0Z0 at centre-of-mass energies of 91 GeV and 183-209 GeV. These searches are based on studies of the recoil mass spectrum of Z0 -> e+e- and mu+mu- events on a search for S0Z0 with Z0 -> nunu bar and S0 -> e+e- or pho

The OPAL collaboration, G. Abbiendi

The production of charm quarks is studied in deep-inelastic electron-photon scattering using data recorded by the OPAL detector at LEP at normal e+e- centre-of-mass energies from 183 to 209 GeV. The charm quarks have been identified by full reconstruction of charged D* mesons using their decays into D0pi with the D0 observed in two decay modes with charged p

The CDF Collaboration

We report a measurement of the ratio of the bottom quark production cross section in antiproton-proton collisions at 630 GeV to 1800 GeV using bottom quarks with transverse momenta greater than 10.75 GeV identified through their semileptonic decays and long lifetimes. The measured ratio sigma(630)/sigma(1800) = 0.171 +/- .024 +/- .012 is in good agreement wi

V. D. Ryzhikov, N. G. Starzhinskiy, S. V. Naydenov, E. K. Lisetskaya

Theoretical background and data on the ways of practical realization are presented, related to the problem of detection of dangerous organic objects (explosives, drugs, etc.) in the presence of other organic substances with atomic number differing by no more than 20-30%. For this purpose, multi-energy X-ray introscopy is used. It has been shown that the &#34

Melvyn J. Shochet

An overview is presented of the experimental talks given at the XXXVIIth Rencontres de Moriond QCD session.

D. Levkov, C. Rebbi, V. A. Rubakov

We consider a minisuperspace model for a closed universe with small and positive cosmological constant, filled with a massive scalar field conformally coupled to gravity. In the quantum version of this model, the universe may undergo a tunneling transition through an effective barrier between regions of small and large scale factor. We solve numerically the

M. Abramowicz, I. Bengtsson, V. Karas, K. Rosquist

It is shown that optical geometry of the Reissner-Nordstrom exterior metric can be embedded in a hyperbolic space all the way down to its outer horizon. The adopted embedding procedure removes a breakdown of flat-space embeddings which occurs outside the horizon, at and below the Buchdahl-Bondi limit (R/M=9/4 in the Schwarzschild case). In particular, the ho