August 1999 arXiv papers — page 2

Weimin Chen, J. P. Franck, J. Jung

We report anomalous features in the normal-state resistivity of single crystalline Bi_2Sr_2CaCu_2O_8 whiskers near some characteristic temperature T* \~ 250 K. From these varied oxygen-doping samples, the resistance (R) was found to deviate {\it upward} from the linear-T relation for T< T*, while R keeps decreasing with T. The deviation, $ΔR \equiv R - (a +

Beom Jun Kim, Petter Minnhagen

The flux-noise spectra around the Kosterlitz-Thouless transition are obtained from simulations of the two-dimensional resistively shunted junction model. In particular the dependence on the distance $d$ between the pick-up coil and the sample is investigated. The typical experimental situation corresponds to the large-$d$ limit and a simple relation valid in

S. Lepri, L. Rondoni, G. Benettin

We test the applicability of the Gallavotti-Cohen fluctuation formula on a nonequilibrium version of the periodic Ehrenfest wind-tree model. This is a one-particle system whose dynamics is rather complex (e.g. it appears to be diffusive at equilibrium), but its Lyapunov exponents are nonpositive. For small applied field, the system exhibits a very long trans

Dennis Zaritsky

We present an analysis of line-of-sight extinction measurements obtained using data from the Magellanic Clouds Photometric Survey, which provides 4-filter photometry for millions of stars in the Large Magellanic Cloud. We find that visual extinctions are typically larger by several tenths of a magnitude for stars with effective temperatures > 12000 K, than f

Daniel A. Dale, Riccardo Giovanelli

We have obtained Tully-Fisher (TF) measurements for some 3000 late-type galaxies in the field and in 76 clusters distributed throughout the sky between 10 and 200\h Mpc. The cluster data are applied to the construction of an I band TF template, resulting in a relation with a scatter of 0.35 magnitudes and a zero-point accurate to 0.02 magnitudes. Peculiar mo

J. O. Burns, C. Loken, K. Roettiger, E. Rizza

New adaptive mesh refinement N-body + hydrodynamics numerical simulations are used to illustrate the complex and changing cluster environments in which many radio galaxies live and evolve. Groups and clusters of galaxies form at the intersections of filaments where they continue to accrete gas and dark matter to the present day. The accretion process produce

L. Piro, A. De Rosa, M. Dadina, F. Nicastro

We will present some results on the broad--band observations of BeppoSAX of the bright Seyfert galaxies NGC 4151 and NGC 5548.

Luis Teodoro, Enzo Branchini, Carlos Frenk, Will Saunders

We perform a detailed comparison of the IRAS PSCz and 1.2-Jy spherical harmonic coefficients of the density and velocity fields in redshift space. The monopole terms predicted from the two surveys show some differences. The mismatch between the velocity monopoles arises from faint sources and disappears when extracting a PSCz subsample of galaxies with fluxe

Thomas H. Reiprich, Hans Boehringer

Using the brightest clusters in the ROSAT All-Sky Survey we compiled an X-ray flux-limited sample of galaxy clusters. The clusters have been reanalysed using ROSAT PSPC pointed observations if possible. The gravitational mass has been determined individually for each cluster in a homogeneous way assuming hydrostatic equilibrium. The mass function has been de

R. W. Kuhne

Webb et al. presented preliminary evidence for a time-varying fine-structure constant. We show Teller&#39;s formula for this variation to be ruled out within the Einstein-de Sitter universe, however, it is compatible with cosmologies which require a large cosmological constant.

David Burstein

How elliptical galaxy dynamics relate to galaxy structure, stellar populations, spiral galaxies and environment are reviewed. The evidence assembled shows that most, if not all, galaxies originally classified as gE contain disks within them. Taken together, the existing evidence are most consistent with the gravitational, hierarchical, clustering, merging (H

G. Wegner, L. N. da Costa, M. V. Alonso, M. Bernardi

The ENEAR project is an all-sky survey of nearby early-type galaxies. About 2200 new spectra and R-band images of over 1500 galaxies together with published data were assembled into a large catalog containing over 2000 objects with cz, sigma, photometric data, and line strengths on a uniform system. From this extensive database a magnitude-limited sample has

J. Lehar, A. Buchalter, R. McMahon, C. Kochanek

We have found three gravitational lenses (two are new) by observing 34 likely FIRST radio lobes with APM galaxy counterparts. We expect to find $\sim30$ such lenses in over the next few years, which will significantly improve lensing constraints on galaxy structure and cosmology.

Hume A. Feldman, Adrian L. Melott

We compare the statistical properties of structures normal and transverse to the line of sight which appear in observational data from redshift surveys. We present a statistic which can quantify this effect in a conceptually different way from standard analyses of distortions of the power-spectrum or correlation function. From tests with N-body experiments,

M. H. van Kerkwijk, V. M. Kaspi, A. R. Klemola, S. R. Kulkarni

We report on Keck and Hubble Space Telescope optical observations of the eclipsing binary pulsar system PSR B1718-19, in the direction of the globular cluster NGC 6342. These reveal a faint star ($m_{\rm F702W}=25.21\pm0.07$; Vega system) within the pulsar&#39;s 0\farcs5 radius positional error circle. This may be the companion. If it is a main-sequence star

M. A. Garrett

The angular resolution of the proposed Square Kilometre Array, SKA, must be extended towards the milliarcsecond scale if it is to resolve the distant starburst galaxies that are likely to dominate the radio source counts at micro and sub-microJy flux levels. This paper considers the best way of extending SKA&#39;s angular resolution towards the milliarcsecon

M. Schultheis, S. Ganesh, G. Simon, A. Omont

DENIS observations in the J (1.2 micron) and K_S (2.15 micron) bands together with isochrones calculated for the RGB and AGB phase are used to draw an extinction map of the inner Galactic Bulge. The uncertainty in this method is mainly limited by the optical depth of the Bulge itself. A comparison with fields of known extinction shows a very good agreement.

P. D. Lynam, C. A. Collins, P. A. James, H. Boehringer

We are engaged in an investigation of the relationship between the properties of BCG candidates and X-ray characteristics of their host clusters for a flux-limited sample of ~250 ACO clusters from the ROSAT all-sky survey. We aim to search for the convergence scale of bulk streaming flows within the ~300 Mpc defined by this sample. X-ray selection provides s

D. Grupe, K. Beuermann, K. Mannheim, H. -C. Thomas

We present the emission line properties of a sample of 76 bright soft X-ray selected ROSAT Active Galactic Nuclei. All optical counterparts are Seyfert 1 galaxies with rather narrow permitted lines, strong optical FeII line blends, and weak forbidden lines. By selection, they also have steep soft X-ray spectra when compared with typical Seyfert 1 galaxies. W

Jorge Melnick, Roberto Terlevich, Elena Terlevich

We re-investigated the use of the Hubble diagram to measure the cosmological constant ($Λ$) and the mass density of the Universe ($Ω_M$). We find an important focusing effect in $Λ$ for redshifts about 3. This effect implies that the apparent magnitude of a standard candle at redshifts z=2-3 has almost no dependence on $Λ$ for $Ω_M>0.2$. This means that $Ω_M

Alfred Krabbe, Hans-Peter Roeser

SOFIA, the Stratospheric Observatory For Infrared Astronomy mounted on-board a Boeing 747SP will open a new era in MIR/FIR astronomy. Starting in 2002, SOFIA will offer German and American astronomers a unique platform, providing regular access to the entire MIR and FIR wavelength range between 5 micron and 300 micron part of which is otherwise inaccessible

J. E. Pesce, C. M. Urry, M. O&#39;Dowd, R. Scarpa

We analyze images of BL Lacertae objects obtained with the {\it Hubble Space Telescope} WFPC2 and the F814W filter. The nine objects cover a redshift range of 0.19 to 0.997. The relatively deep images are sufficient to detect galaxies at least one magnitude below M$^{*}_{I}$ (--21.4) and in most cases to three magnitudes below M$^{*}$. Galaxy enhancement ove

M. A. Hendry, S. Rauzy

We obtain a robust, non-parametric, estimate of the Hubble constant from galaxy linear diameters calibrated using HST Cepheid distances. Our method is independent of the parametric form of the diameter function and the spatial distribution of galaxies and is insensitive to Malmquist bias. We include information on the galaxy rotation velocities; unlike Tully

N. Straumann

After a short history of the $Λ$-term it is explained why the (effective) cosmological constant is expected to obtain contributions from short-distance-physics, corresponding to an energy scale of at least 100 GeV. The actual tiny value of the cosmological constant in any natural scale of units represents, therefore, one of the deepest mysteries of present d

Carmen Morales, Joaquin Trapero, Jose F. Gomez, Alvaro Gimenez

We present the far ultraviolet spectrum of alpha Virginis taken with EURD spectrograph on-board MINISAT-01. The spectral range covered is from ~900 to 1080 A with 5 A spectral resolution. We have fitted Kurucz models to IUE spectra of alpha Vir and compared the extension of the model to our wavelengths with EURD data. This comparison shows that EURD fluxes a

J. Hwang, H. Noh

We derive power spectra of the scalar- and tensor-type structures generated in an inflation model based on a massive non-minimally coupled scalar field with the strong coupling assumption. We make analyses in both the original-frame and the conformally transformed Einstein-frame. We derive contributions of both structures to the anisotropy of the cosmic micr

Michael Blanton

I perform a joint counts-in-cells analysis of galaxies of different spectral types using the Las Campanas Redshift Survey (LCRS). Using a maximum-likelihood technique to fit for the relationship between the density fields of early- and late-type galaxies, I find a relative linear bias of $b=0.76\pm 0.02$. This technique can probe the nonlinearity and stochas

M. Harwit, R. J. Protheroe, P. L. Biermann

The recent detection of gamma radiation from Mkn 501 at energies as high as 25 TeV suggests stringent upper bounds on the diffuse, far infrared, extragalactic radiation density. The production of electron-positron pairs through photon-photon collisions would prevent gamma photons of substantially higher energies from reaching us across distances of order 100

Harvey B. Richer, Brad Hansen, Marco Limongi, Alessandro Chieffi

Using a new grid of models of cooling white dwarfs, we calculate isochrones and luminosity functions in the Johnson-Kron/Cousins and HST filter sets for systems containing old white dwarfs. These new models incorporate a non-grey atmosphere which is necessary to properly describe the effects of molecular opacity at the cool temperatures of old white dwarfs.

Israel Quiros, Rolando Bonal, Rolando Cardenas

We tudy flat Friedmann-Robertson-Walker cosmology in Brans-Dicke-type theories of gravitation with minimal coupling between the scalar field and the matter fields in the Einstein frame (general relativity with an extra scalar field) for arbitrary values of the Brans-Dicke parameter $ω>-{3/2}$. It is shown that the cosmological singularity occuring in the Ein

H. G. Blundell, S. Godfrey, G. Hay, E. S. Swanson

A quark model calculation of the processes gamma gamma -> pi+ pi- and gamma gamma -> pi0 pi0 is performed. At tree level, only charged pions couple to the initial state photons and neutral pions are not expected in the final state. However, a small but significant gamma gamma -> pi0 pi0 cross section is observed. We demonstrate that this may be accounted for

A. Losev, N. Nekrasov, S. Shatashvili

We study instanton-corrected renormalization group flow in the two dimensional sigma models and four dimensional gauge theory. In two dimensions we do that by replacing the non-linear supersymmetric ${\IC\IP}^{N-1}$ model by the gauged linear sigma model which is in the same universality class. We compare the moduli spaces of the instantons in the non-linear

D. Blaschke, T. Klaehn, D. N. Voskresensky

The effect of color superconductivity on the cooling of quark stars and neutron stars with large quark cores is investigated. Various known and new quark-neutrino processes are studied. As a result, stars being in the color flavor locked (CFL) color superconducting phase cool down extremely fast. Quark stars with no crust cool down too rapidly in disagreemen

X. Leoncini, L. Kuznetsov, G. M. Zaslavsky

A system of three point vortices in an unbounded plane has a special family of self-similarly contracting or expanding solutions: during the motion, vortex triangle remains similar to the original one, while its area decreases (grows) at a constant rate. A contracting configuration brings three vortices to a single point in a finite time; this phenomenon kno

S. Hellerman, J. Polchinski

We study the supersymmetric quantum mechanical systems that arise from discrete light cone quantization of theories with minimal supersymmetry in various dimensions. These systems, which have previously arisen in the study of black hole moduli spaces, are distinguished by having fewer fermionic fields than the familiar Kähler and hyper-Kähler models.

Maxim Pospelov, Adam Ritz

We present a detailed study of the electric dipole moment of the neutron induced by a vacuum theta angle within the framework of QCD sum rules. At next-to-next-to leading order in the operator product expansion, we find the result d_n(θ) = 2.4 x 10^{-16} θe cm, to approximately 40% precision. With the current experimental bound this translates into a limit o

M. Encinosa, Ray N. O&#39;Neal,

The Schrodinger equation for a charged particle constrained to a curved surface in the presence of a vector potential is derived using the method of forms. In the limit that the particle is brought infinitesimally close to the surface, a term arises that couples the component of the vector potential normal to the surface to the mean curvature of the surface.

Helio J. Rocha-Pinto, John Scalo, Walter Maciel, Chris Flynn

The star formation rate history of the Milky Way is derived using the chromospheric age distribution for 552 stars in the solar neighborhood. The stars sample birthsites distributed over a very large range of distances because of orbital diffusion, and so give an estimate of the global star formation rate history. The derivation incorporates the metallicity

Joseph Lykken, Satyanarayan Nandi

We study scenarios in which there is a hierarchy of two sets of large compactified extra dimensions. One particularly interesting case has a single millimeter size extra dimension and five TeV^{-1} size dimensions. The Standard Model gauge bosons have Kaluza-Klein excitations with respect to one of the TeV scale dimensions. We discuss astrophysical constrain

A. Abd El-Hady, Jusak Tandean

We recalculate the leading nonanalytic contributions to the amplitudes for hyperon nonleptonic decays in chiral perturbation theory. Our results partially disagree with those calculated before, and include new terms previously omitted in the P-wave amplitudes. Although these modifications are numerically significant, they do not change the well-known fact th

D. K. Jackson, M. Nicodemi, G. Perkins, N. A. Lindop

We study vortex clustering in type II Superconductors. We demonstrate that the ``second peak&#39;&#39; observed in magnetisation loops may be a dynamical effect associated with a density driven instability of the vortex system. At the microscopic level the instability shows up as the clustering of individual vortices at (rare) preferential regions of the pin

Christopher J. Fewster, Edward Teo

Quantum inequalities (QI&#39;s) provide lower bounds on the averaged energy density of a quantum field. We show how the QI&#39;s for massless scalar fields in even dimensional Minkowski space may be reformulated in terms of the positivity of a certain self-adjoint operator - a generalised Schroedinger operator with the energy density as the potential - and h

S. P. Shukla, M. Shayegan, S. R. Parihar, S. A. Lyon

We report tilted-field magnetotransport measurements of two-dimensional electron systems in a 200 Angstrom-wide Al(0.13)Ga(0.87)As quantum well. We extract the energy gap for the quantum Hall state at Landau level filling ν=1 as a function of the tilt angle. The relatively small effective Lande g-factor (g ~ 0.043) of the structure leads to skyrmionic excita

Attila Csoto

In standard potential-model descriptions of the Be7(p,gamma)B8 reaction the Be7+p spectroscopic factors S appear in the cross section. We argue that the microscopic substructure effects which are represented by S are short-ranged and cannot affect the asymptotic normalization of the wave function. We believe that the standard way of describing reactions in a

Attila Csoto

We search for low-lying resonances in the B8 and Li8 nuclei using a microscopic cluster model and a variational scattering method, which is analytically continued to complex energies. After fine-tuning the nucleon-nucleon interaction to get the known 1+ state of B8 at the right energy, we reproduce the known spectra of the studied nuclei. In addition, our mo

Eldad Bettelheim, Oded Agam, Nadav M. Shnerb

Diffusion limited reaction of the Lotka-Volterra type is analyzed taking into account the discrete nature of the reactants. In the continuum approximation, the dynamics is dominated by an elliptic fixed-point. This fixed-point becomes unstable due to discretization effects, a scenario similar to quantum phase transitions. As a result, the long-time asymptoti

David M. J. Calderbank

I show that solutions of the SU(infinity) Toda field equation generating a fixed Einstein-Weyl space are governed by a linear equation on the Einstein-Weyl space. From this, obstructions to the existence of Toda solutions generating a given Einstein-Weyl space are found. I also give a classification of Einstein-Weyl spaces arising from the Toda equation in m

L. Biferale, I. Daumont, T. Dombre, A. Lanotte

A study of anomalous scaling in models of passive scalar advection in terms of singular coherent structures is proposed. The stochastic dynamical system considered is a shell model reformulation of Kraichnan model. We extend the method introduced in \cite{DDG99} to the calculation of self-similar instantons and we show how such objects, being the most singul

Alexander Burinskii

We consider the $AdS_5$ solution deformed by a non-constant dilaton interpolating between the standard AdS (UV region) and flat boundary background (IR region). We show that this dilatonic solution can be generalized to the case of a non-flat boundaries provided that the metric of the boundaries satisfies the vacuum Einstein field equations. As an example, w

K. Anguige

We prove the existence of a class of plane symmetric perfect-fluid cosmologies with a (-1/3, 2/3, 2/3) Kasner-like singularity. These solutions of the Einstein equations depend on two smooth functions of one space coordinate. They are constructed by solving a symmetric hyperbolic system of Fuchsian equations.

K. Hirota, N. Oumi, T. Matsumura, H. Nakao

Antiferroquadrupolar (AFQ) ordering has been conjectured in several rare-earth compounds to explain their anomalous magnetic properties. No direct evidences for AFQ ordering, however, have been reported. Using the resonant x-ray scattering technique near the Dy L_III absorption edge, we have succeeded in observing the AFQ order parameter in DyB2C2 and analyz

M. A. Nielsen

This note quantifies the continuity properties of entanglement: how much does entanglement vary if we change the entangled quantum state just a little? This question is studied for the pure state entanglement of a bipartite system and for the entanglement of formation of a bipartite system in a mixed state.

Wen-Xiu Ma, Si-Ming Zhu

This paper aims to show that there exist non-symmetry constraints which yield integrable Hamiltonian systems through nonlinearization of spectral problems of soliton systems, like symmetry constraints. Taking the AKNS spectral problem as an illustrative example, a class of such non-symmetry constraints is introduced for the AKNS system, along with two-dimens

A. A. Barybin

A unified electrodynamic approach to the guided-wave excitation theory is generalized to the waveguiding structures containing a hypothetical space-dispersive medium with drifting charge carriers possessing simultaneously elastic, piezoelectric and magnetic properties. Substantial features of our electrodynamic approach are: (i) the allowance for medium loss

A. A. Ketsaris

Transformation rules for coordinates, velocities and accelerations in accelerated reference frames are derived. A generalized approach of the special relativity is taken for a basis. A 7-dimensional space including projections of velocity vector as three additional coordinates to time and geometric coordinates is studied. Turns in pseudoplane (dt,dv) of this

Franz Gross

In response to recent critcism, we show how to define the spectator equations for negative energies so that charge conjugation invariance is preserved. The result, which emerges naturally from the application of spectator principles to systems of particles with negative energies, is to replace all factors of the external energies $W_i$ by $\sqrt{W^2_i}$, ins

L. Trache, A. Azhari, H. L. Clark, C. A. Gagliardi

We present the results of a search for optical model potentials for use in the description of elastic scattering and transfer reactions involving stable and radioactive p-shell nuclei. This was done in connection with our program to use transfer reactions to obtain data for nuclear astrophysics, in particular for the determination of the astrophysical S_17 f

Agata Olariu

A number of medieval coins from the Brukenthal Museum, Sibiu, Romania have been analyzed by the means of three methods: gamma transmission, X-ray fluoresecence and neutron activation analysis. The values of the concentrations of the elements determined given by the three methods are discussed.

Agata Olariu

Ancient Dacian ceramics, from three different establishments from Romanian territory have been analyzed by neutron activation analysis. A series of elements has been determined: Ba, Eu, K, La, Mn, Na, Sc, Sm. Ba is the element that could be considered to differentiate relatively the three groups of ceramics.

T. A. Larsson

I construct lowest-energy representations of non-centrally extended algebras of Noether symmetries, including diffeomorphisms and reparametrizations of the observer&#39;s trajectory. This may be viewed as a new scheme for quantization. First classical physics is formulated as the cohomology of a certain Koszul-Tate (KT) complex, using not only fields and ant

Mikhail Khovanov

We construct a bigraded cohomology theory of links whose Euler characteristic is the Jones polynomial.

Tom Fowler

Given a coloring of the edges of the complete graph on n vertices in k colors, by considering the neighbors of an arbitrary vertex it follows that there is a monochromatic diameter two subgraph on at least 1+(n-1)/k vertices. We show that for $k \ge 3$ this is asymptotically best possible, and that for k=2 there is always a monochromatic diameter two subgrap

Alexander Brudnyi

We study the structure of the maximal ideal space $M(H^{\infty})$ of the algebra $H^{\infty}=H^{\infty}(\Di)$ of bounded analytic functions defined on the open unit disk $\Di\subset\Co$. Based on the fact that $dim\ M(H^{\infty})=2$ we prove for $H^{\infty}$ the matrix-valued corona theorem. Our results heavily rely on the topological construction describing

Taras E. Panov

We refer to an action of the group Z/p (p here is an odd prime) on a stably complex manifold as simple if all its fixed submanifolds have the trivial normal bundle. The important particular case of a simple action is an action with only isolated fixed points. The problem of cobordism classification of manifolds with simple action of Z/p was posed by V.M.Buch

Roelof Koekoek

We derive inversion formulas involving orthogonal polynomials which can be used to find coefficients of differential equations satisfied by certain generalizations of the classical orthogonal polynomials. As an example we consider special symmetric generalizations of the Hermite polynomials.

J. Koekoek, R. Koekoek

We look for spectral type differential equations satisfied by the generalized Jacobi polynomials, which are orthogonal on the interval [-1,1] with respect to a weight function consisting of the classical Jacobi weight function together with two point masses at the endpoints of the interval of orthogonality. We show that such a differential equation is unique

Udo Hertrich-Jeromin

Using a quaternionic calculus, the Christoffel, Darboux, Goursat, and spectral transformations for discrete isothermic nets are described, with their interrelations. The Darboux and spectral transformations are used to define discrete analogs for cmc-1 surfaces in hyperbolic space and to obtain a discrete version of Bryant&#39;s Weierstrass type representati

Saharon Shelah, Pauli Vaisanen

We prove that if ZF is consistent then ZFC+GCH is consistent with the following statement: There is for every k<omega a model of cardinality aleph_1 which is L_{infty,omega_1}-equivalent to exactly k non-isomorphic models of cardinality aleph_1. In order to get this result we introduce ladder systems and colourings different from the ``standard&#39;&#39; cou

Timothy J. Hollowood

We examine ADHM multi-instantons in the conformal N=2 supersymmetric Sp(N) gauge theory with one anti-symmetric tensor and four fundamental hypermultiplets. We argue that the ADHM construction and measure can also be deduced from purely field theoretic considerations and also from the dynamics of D-instantons in the presence of D3-branes, D7-branes and an or

Bertfried Fauser

Recently Daviau showed the equivalence of ordinary matrix based Dirac theory -formulated within a spinor bundle S_x \simeq C^4_x-, to a Clifford algebraic formulation within space Clifford algebra CL(R^3,delta) \simeq M_2(C) \simeq P \simeq Pauli algebra (matrices) \simeq H \oplu H \simeq biquaternions. We will show, that Daviau&#39;s map theta : C^4 \mapsto

Kasper Olsen

This thesis discusses various aspects of duality in quantum field theory and string theory. In the first part we consider duality in topological quantum field theories, concentrating on the Donaldson and Seiberg-Witten theories as (dual) approaches to the study of four-manifolds. Lower-dimensional variants of these theories are also discussed. In the second

Xiang-Song Chen, Wei-Min Sun, Fan Wang, Amand Faessler

Based on a canonically derived path integral formalism, we demonstrate that the perturbative calculation of the matrix element for gauge dependent operators has crucial difference from that for gauge invariant ones. For a gauge dependent operator ${\cal O}(ϕ)$ what appears in the Feynman diagrams is not ${\cal O} (ϕ)$ itself, but the gauge-transformed one ${

Richard C. Brower, Samir D. Mathur, Chung-I Tan

The discrete spectrum of fluctuations of the metric about an $AdS^5$ black hole background are found. These modes are the strong coupling limit of so called glueball states in a dual 3-d Yang-Mills theory with quantum numbers $J^{PC} = 2^{++}, 1^{-+}, 0^{++}$. For the ground state modes, we find the mass relation: $m(0^{++}) < m(2^{++}) < m(1^{-+})$. Contrar

Tsippy R. Mendelson

We apply the concept of helicity from classical hydrodynamics to elucidate two problematical issues in cosmic string physics. Helicity, the space integral of the scalar product of a velocity-like field with its vorticity field (curl), can be defined for a complex scalar field in analogy with fluids. We dwell on the topological interpretation of helicity as r

Elizabeth H. Simmons

The top quark is by far the heaviest known fermion [1]. In consequence, experiment is just beginning to explore its properties, and some of them may yet prove to be distinctly non-standard. The very size of the top quark&#39;s mass even hints at the possibility of a special role for top in electroweak symmetry breaking. This talk examines the top quark in th

B. Melic, B. Nizic, K. Passek

We comment on the results of a complete leading-twist next-to-leading order QCD analysis of the spacelike pion electromagnetic form factor at large-momentum transfer Q. For the asymptotic distribution amplitude, we have examined the sensitivity of the predictions to the choice of the renormalization scale. The results show that, regarding the size of the rad

Mary Alberg, Ernest M. Henley

We use the meson cloud model to calculate $\bar{d}(x) - \bar{u}(x)$ and $ \bar{d}(x)/\bar{u}(x)$ in the proton. We show that a modification of the symmetric, perturbative part of the light quark sea provides better agreement with the ratio $ \bar{d}(x)/\bar{u}(x).

Luis Bento

It is shown that a true Nambu-Goldstone (NG) boson develops a coherent long-range field whenever the charge associated with it that is carried by the other particles is not conserved in a macroscopic scale. The source of a NG field is the time rate of quantum number violation. If the lepton numbers are spontaneously broken at a scale below 1 TeV, the neutrin

Alan Kostelecky, Charles Lane

Constraints from clock-comparison experiments on violations of Lorentz and CPT symmetry are investigated in the context of a general Lorentz-violating extension of the standard model. The experimental signals are shown to depend on the atomic and ionic species used as clocks. Certain experiments usually regarded as establishing comparable bounds are in this

W. Schäfer, J. Speth

We revisit the evaluation of the pionic mechanism of the $\bar{u}-\bar{d}$-asymmetry in the proton structure function. Our analysis is based on the unitarity relation between contributions of different mechanisms to the inclusive particle production and the total photoabsorption cross-section (i.e. the proton structure function). We reanalyze the role of iso

Blazenka Melic

Using a modified perturbative approach that includes the Sudakov resummation and transverse degrees of freedom we analyze the penguin-induced B -> pi phi decay. The perturbative method enables us to include nonfactorizable contributions and to control virtual momenta appearing in the process. The calculation supports the results obtained in the standard BSW

Paul Hoyer

There are indications of a faith transition in QCD: The strong coupling may freeze at a sufficiently low value to make PQCD relevant even in the confining regime. The properties of PQCD at low Q^2 depend on the asymptotic field configuration assumed at t=\pm\infty. A change in the iεprescription of the free propagators is equivalent to including quarks and g

T. Gehrmann

The spin physics parallel sessions at this workshop made a critical review of the physics potential of future experiments on polarized nucleons, with an emphasis on the potential impact of polarized electron-proton collisions at HERA. A summary of the results and discussions from these sessions is presented in this article.

Toru. Goto, Yasuhiro Okada, Yasuhiro Shimizu

Flavor changing neutral current processes in B and K decays in the supergravity model are revisited taking into account the recent progress of Higgs boson search experiments at LEP. Possible deviations of B^0--$\bar{B}^0$ mixing, the CP violating K^0--$\bar{K}^0$ mixing parameter $ε_K$ from the standard model predictions are reduced significantly in a small

Jan Ambjorn, K. N. Anagnostopoulos, R. Loll

The phase diagram of 2d Lorentzian quantum gravity (LQG) coupled to conformal matter is studied. A phase transition is observed at $c=c_{\rm crit}$ ($1/2<c_{\rm crit}<4$) which can be thought of as the analogue of the $c=1$ barrier of Euclidean quantum gravity (EQG). The non--trivial properties of the quantum geometry are discussed.

L. A. Averchenkova, V. K. Petrov

Monte Carlo simulations are carried out on the (3+1)-dimensional Z(2) anisotropic lattice model, and a new method to simulate extremely anisotropic lattice systems with discrete symmetries is proposed. Dependence of the temporal and spatial average plaquette, Wilson loops on the anisotropy parameter is presented.

Nilmani Mathur, S. J. Dong, K. F. Liu, N. C. Mukhopadhyay

We calculate the form factor of the quark energy momentum tensor and thereby extract the quark orbital angular momentum of the nucleon. The calculation is done on a quenched $16^3 \times 24$ lattice at $β= 6.0$ and with Wilson fermions at $κ$ = 0.148, 0.152, 0.154 and 0.155. We calculate the disconnected insertion stochastically which employs the $Z_2$ noise

M. N. Chernodub, F. V. Gubarev, M. I. Polikarpov, V. I. Zakharov

We discuss how infrared region influence on short distance physics via new object, called ``short string&#39;&#39;. This object exists in confining theories and violates the operator product expansion. Most analytical results are obtained for the dual Abelian Higgs theory, while phenomenological arguments are given for QCD.

Attilio Cucchieri

We evaluate numerically the momentum-space gluon propagator in the lattice Landau gauge, for three- and four-dimensional pure SU(2) lattice gauge theory. Although there are large finite-size effects, we always observe, in the limit of large lattice volumes, a gluon propagator decreasing in the infrared limit. This result can be interpreted in a straightforwa

Pablo Garcia-Abia, Wolfgang Lohmann

We report on the accuracy of the measurement of the Higgs boson mass and the total cross section of the process e+e- -> ZH that would be achieved in a linear collider operating at a centre-of-mass energy of 350 GeV, assuming an integrated luminosity of 500 (1/fb). For that we have exploited the recoil mass off the Z using its leptonic decays into electron an

CCFR Collaboration, B. H. Tamminga, T. Adams, A. Alton

Analyses of structure functions (SFs) from neutrino and muon deep inelastic scattering data have shown discrepancies in F2 for x < 0.1. A new SF analysis of the CCFR collaboration data examining regions in x down to x=.0015 and 0.4 < Q^2 < 1.0 is presented. Comparison to corrected charged lepton scattering results for F2 from the NMC and E665 experiments are

V. Dzhunushaliev, H. -J. Schmidt

The spherically symmetric solutions in Weyl gravity interacting with U(1) or SU(2) gauge fields are examined. It is shown that these solutions are conformally equivalent to an infinite flux tube with constant (color) electric and magnetic fields. This allows us to say that Weyl gravity has in some sense a classical confinement mechanism. We discuss a possibl

Riuji Mochizuki, Takayuki Suga

In this paper it is explicitly demonstrated that the energy conservation law is kept when a detector uniformly accelerated in the Minkowski vacuum is excited and emits a particle. This fact had been hidden in conventional approaches in which detectors were considered to be forced on trajectories. To lift the veil we suggest a detector model written in terms

B. Maiorov, G. Nieva, E. Osquiguil

We present an exhaustive analysis of transport measurements performed in twinned YBa2Cu3O7 single crystals which stablishes that the vortex solid-liquid transition is first order when the magnetic field H is applied at an angle theta away from the direction of the twin planes. We show that the resistive transitions are hysteretic and the V-I curves are non-l

K. Senouci, N. Zekri

A simple Kronig-Penney model is used to study the effect of nonlinear interactions on the electronic properties of ordered and disordered electrified chains. In the case of ordered potentials, we found that the nonlinearity suppresses the Wannier-Stark effect caused by the electric field. In the case of disordered potentials, the nonlinearity gives rise to a

C. M. Newman, D. L. Stein

We study analytically M-spin-flip stable states in disordered short-ranged Ising models (spin glasses and ferromagnets) in all dimensions and for all M. Our approach is primarily dynamical and is based on the convergence of a zero-temperature dynamical process with flips of lattice animals up to size M and starting from a deep quench, to a metastable limit.

G. Delfino, G. T. Barkema, John Cardy

The high-temperature susceptibility of the $q$-state Potts model behaves as $Γ|T-T_c|^{-γ}$ as $T\to T_c+$, while for $T\to T_c-$ one may define both longitudinal and transverse susceptibilities, with the same power law but different amplitudes $Γ_L$ and $Γ_T$. We extend a previous analytic calculation of the universal ratio $Γ/Γ_L$ in two dimensions to the

Jan Govaerts, Geoffrey Stenuit, Damien Bertrand, Olivier van der Aa

New vortex solutions to the Landau-Ginzburg equations are described. These configurations, which extend the well known Abrikosov and giant magnetic vortex ones, consist of a succession of ring-like supercurrent vortices organised in a concentric pattern, possibly bound to a giant magnetic vortex then lying at their center. The dynamical and thermodynamic sta

F. D. Buzatu, G. Jackeli

The canonical transformation diagonalizing the one-particle tight binding Hamiltonian for an alternating chain with two non-equivalent sites per unit cell has been used to introduce the Hubbard-like interactions (on-site, inter-site, bond-site and intra-bond) in the corresponding two-band model. The considerations have been restricted to the particular case,

Tobias Brandes, Jun&#39;ichi Inoue, Akira Shimizu

We present theoretical results for superradiance, i.e. the collective coherent decay of a radiating system, in a semiconductor heterostructure under a strong quantizing magnetic field. We predict a strong peak (`Dicke-peak&#39;) in the emission intensity as a function of time, which should be observable after a short initial excitation of electrons into the