December 1999 arXiv papers — page 11

M. S. Golden, S. V. Borisenko, S. Legner, T. Pichler

We present a study of the topology of the normal state Fermi surface (FS) of the high Tc superconductor Bi2212 using angle-resolved photoemission. We present FS mapping experiments, recorded using unpolarised radiation with high (E,k) resolution, and an extremely dense sampling of k-space. In addition, synchrotron radiation-based ARPES has been used to prove

Andrea Capocci, Yi-Cheng Zhang

We study investment strategy in different models of financial markets, where the investors cannot reach a perfect knowledge about available assets. The investor spends a certain effort to get information; this allows him to better choose the investment strategy, and puts a selective pressure upon assets. The best strategy is then a compromise between diversi

Benno Tilch, Frank Schweitzer, Werner Ebeling

A model of Brownian particles with the ability to take up energy from the environment, to store it in an internal depot, and to convert internal energy into kinetic energy of motion, is discussed. The general dynamics outlined in Sect. 2 is investigated for the deterministic and stochastic particle's motion in a non-fluctuating ratchet potential. First,

David R. Dominguez Carreta, Elka Korutcheva

The mutual information, I, of the three-state neural network can be obtained exactly for the mean-field architecture, as a function of three macroscopic parameters: the overlap, the neural activity and the {\em activity-overlap}, i.e. the overlap restricted to the active neurons. We perform an expansion of I on the overlap and the activity-overlap, around th

Benno Tilch, Dirk Helbing

In this paper we study dependencies of fundamental diagrams, time gap distributions, and velocity-distance relations on vehicle types, lanes and/or measurement sites. We also propose measurement and aggregation methods that have more favourable statistical properties than conventional methods.

Lars Melwyn Jensen, Beom Jun Kim, Petter Minnhagen

The dynamic critical exponent z is determined from numerical simulations for the three-dimensional XY model subject to two types of dynamics, i.e. relaxational dynamics and resistively shunted junction (RSJ) dynamics, as well as for two different treatments of the boundary, i.e., periodic boundary condition (PBC) and fluctuating twist boundary condition (FTB

Nick E. Mavromatos, Sarben Sarkar

In the context of extended t-J models, with intersite Coulomb interactions of the form $-V\sum\limits_{< {i,j} >} {n_in_j}$, with n_i denoting the electron number operator at site i, nodal liquids are discussed. We use the spin-charge separation ansatz as applied to the nodes of a d-wave superconducting gap.Such a situation may be of relevance to the physics

Fabrizio Dolcini, Arianna Montorsi

We investigate in the Hartree Fock approximation the temperature and filling dependence of the superconducting $π$-phase for the Penson-Kolb-Hubbard model. Due to the presence of the pair-hopping term, the phase survives for repulsive values of the on-site Coulomb interaction, exhibiting an interesting filling and temperature dependence. The structure of the

Fabrizio Dolcini, Arianna Montorsi

We consider the most general form of extended Hubbard Hamiltonian conserving the total spin and number of electrons, and find all the 1-dimensional completely integrable models which can be derived from first degree polynomial solution of the Yang-Baxter equation. It is shown that such models are 96. They are identified with the 16-dimensional representation

M. Fleck, A. I. Lichtenstein, E. Pavarini, A. M. Oles

Using an exact diagonalization method within the dynamical mean-field theory we study stripe phases in the two-dimensional Hubbard model. We find a crossover at doping $δ\simeq 0.05$ from diagonal stripes to vertical site-centered stripes with populated domain walls, stable in a broad range of doping, $0.05<δ<0.17$. The calculated chemical potential shift $\

Holger Frahm, Nikita A. Slavnov

The magnetic susceptibility of systems from a class of integrable models for doped spin-$S$ Heisenberg chains is calculated in the limit of vanishing magnetic field. For small concentrations $x_h$ of the mobile spin-$(S-1/2)$ charge carriers we find an explicit expression for the contribution of the gapless mode associated to the magnetic degrees of freedom

M. V. Sadovskii

We review a certain class of (&#34;nearly&#34;) exactly solvable models of electronic spectrum of two-dimensional systems with fluctuations of short range order of &#34;dielectric&#34; (e.g. antiferromagnetic) or &#34;superconducting&#34; type, leading to the formation of anisotropic pseudogap state on certain parts of the Fermi surface. The models are based

Miodrag L. Kulic, Martin Endres

We consider thin superconducting (S) films of thickness d $\ll ξ_{0}$, sandwiched between two ferromagnetic semiconducting insulators (FI) with differently orientated magnetizations - the FI-S-FI system. We calculate the dependence of the superconducting critical temperature on the orientation of the magnetization in the insulators and on the thickness of th

Qijin Chen, Ioan Kosztin, K. Levin

We explore a BCS Bose Einstein crossover scenario for $0 \leq T \leq T_c$ and its implications for the superfluid density and specific heat. The low lying excitations consist of nodal (fermionic) quasi-particles as well as excited (bosonic) pair states. Semi-quantitative comparison with cuprate data is reasonable, with no compelling indications for Landau pa

V. Perez-Munuzuri, M. N. Lorenzo

The effect of time-correlated zero-mean Gaussian noise on chaotic synchronization is analyzed experimentally in small-size arrays of Chua&#39;s circuits. Depending on the correlation time, an improvement of the synchronization is found for different values of the noise amplitude and coupling diffusion between circuits.

G. A. Bower, R. F. Green, A. C. Quillen, A. Danks

We have obtained new Hubble Space Telescope (HST) observations of M84, a nearby massive elliptical galaxy whose nucleus contains a 1.5 X 10^9 Msun dark compact object, which presumably is a supermassive black hole. Our Space Telescope Imaging Spectrograph (STIS) spectrum provides the first clear detection of emission lines in the blue (e.g., [O II] 3727, Hbe

David W. Koerner

A clear understanding of the chemical processing of matter, as it is transferred from a molecular cloud to a planetary system, depends heavily on knowledge of the physical conditions endured by gas and dust as these accrete onto a disk and are incorporated into planetary bodies. Reviewed here are astrophysical observations of circumstellar disks which trace

D. W. Koerner, J. Davy Kirkpatrick, I. N. Reid, J. Gizis

We present preliminary results of an imaging survey for companions to low-luminosity dwarfs with spectral types ranging from M7 to L9. A K-band study with the Near Infrared Camera (NIRC) at the Keck telescope discriminates against background sources by searching for common proper motion. A complimentary HST/WFPC2 snapshot survey is better able to resolve clo

J. Christopher Howk, Kenneth R. Sembach

We present a simple, effective approach for estimating the on-order backgrounds of spectra taken with the highest-resolution modes of the Space Telescope Imaging Spectrograph (STIS) on-board the Hubble Space Telescope. Our scheme for determining the on-order background spectrum uses polynomial fits to the inter-order scattered light visible in the two-dimens

Augusto Damineli, Andreas Kaufer, Bernhard Wolf, Otmar Stahl

We report the recovery of a spectroscopic event in eta Carinae in 1997/98 after a prediction by Damineli (1996). A true periodicity with P = 2020+-5 days (0.2% uncertainty) is obtained. The line intensities and the radial-velocity curve display a phase-locked behavior implying that the energy and dynamics of the event repeat from cycle to cycle. This rules o

E. Bica, C. M. Dutra

Surveys using CCD detectors are retrieving bright and faint cataloged clusters and revealing new ones in the Magellanic Clouds. This paper discusses the contribution of the OGLE Survey to the overall census of star clusters in the SMC. A detailed cross-identification indicates that the new objects in the SMC OGLE catalog are 46. The increase in the number of

A. Benoit, F. Zagury, N. Coron, M. De Petris

We have designed and built a large-throughput dual channel photometer, Diabolo. This photometer is dedicated to the observation of millimetre continuum diffuse sources, and in particular, of the Sunyaev-Zel&#39;dovich effect and of anisotropies of the 3K background. We describe the optical layout and filtering system of the instrument, which uses two bolomet

August A. Muench, Elizabeth A. Lada, Charles J. Lada

We present the results of numerical experiments designed to evaluate the usefulness of near-infrared luminosity functions for constraining the Initial Mass Function (IMF) of young stellar populations. From this numerical modeling, we find that the luminosity function of a young stellar population is considerably more sensitive to variations in the underlying

Eugeny Babichev, Vyacheslav Dokuchaev

The gravitational lensing of a relativistic fireball can produce the time delayed multiple images with quite different spectra and temporal patterns in contrast with a nonrelativistic source and hence can imitate the source recurrence. In particular, the enigmatic four multiple gamma-ray bursts detected during two days at October 1996 in the same sky region

Alexander S. Szalay, Peter Kunszt, Anirudha Thakar, Jim Gray

The next-generation astronomy archives will cover most of the universe at fine resolution in many wavelengths. One of the first of these projects, the Sloan Digital Sky Survey (SDSS) will create a 5-wavelength catalog over 10,000 square degrees of the sky. The 200 million objects in the multi-terabyte database will have mostly numerical attributes, defining

J. S. Dunlop

I review the current status of an on-going investigation into the stellar and dynamical ages of the oldest known galaxies at redshifts greater than 1. The spectroscopic data, when compared with the predictions of a range of recent evolutionary synthesis models, continue to indicate that the oldest galaxies at z = 1.5 are already at least 3 Gyr old. Moreover,

L. Portinari

We examine the dependence of stellar yields on the metallicity Z of the stellar population. This effect may be important for the very first chemical enrichment from Population III stars, at very low Z. In the range of massive stars, mass loss rates varying with Z have remarkable effects. We also estimate chemical yields from Very Massive Objects (from 120 to

S. Borgani, P. Rosati, R. Della Ceca, P. Tozzi

We use the ROSAT Deep Cluster Survey (RDCS) to trace the evolution of the cluster abundance out to $z\simeq 0.8$ and constrain cosmological models. We resort to a phenomenological prescription to convert masses into $X$-ray fluxes and apply a maximum-likelihood approach to the RDCS redshift- and luminosity-distribution. We find that, even changing the shape

D. Babusci, M. Giovannini

The sensitivity of a pair of VIRGO interferometers to gravitational waves backgrounds of cosmological origin is analyzed for the cases of maximal and minimal overlap of the two detectors. The improvements in the detectability prospects of scale-invariant and non-scale-invariant logarithmic energy spectra of relic gravitons are discussed.

Sang-Hyeon Ahn

Among a number of gamma ray bursts whose host galaxies are known, GRB971214 stands out for its high redshift $z\ge 3$ and the Ly$α$ emission line having a P-Cygni type profile, which is interpreted to be a direct consequence of the expanding supershell. From a profile fitting analysis we estimate the expansion velocity of the supershell $v_{exp} = 1500\kms$

M. H. van Kerkwijk, J. F. Bell, V. M. Kaspi, S. R. Kulkarni

We report on Keck and {\em Hubble Space Telescope} observations of the binary millisecond pulsar PSR B1855+09. We detect its white-dwarf companion and measure $\mv=25.90\pm0.12$ and $\mi=24.19\pm0.11$ (Vega system). From the reddening-corrected color, $(\mv-\mi)_0=1.06\pm0.21$, we infer a temperature $\Teff=4800\pm800 $K. The white-dwarf mass is known accura

A. Cavaliere, R. Giacconi, N. Menci

The current models of early star and galaxy formation are based upon the hierarchical growth of dark matter halos, within which the baryons condense into stars after cooling down from a hot diffuse phase. The latter is replenished by infall of outer gas into the halo potential wells; this includes a fraction previously expelled and preheated, due to momentum

Martin J. Rees

This brief introduction to the NATO ASI offers comments on current controversies, on the limits and prospects of cosmology in the coming decade, and on how the `sociology&#39; of our subject may change in the decades beyond that.

Vikram Dwarkadas

Recent observations have revealed the presence of a variety of small-scale ``micro-structures&#39;&#39; in Planetary Nebulae images. I discuss numerical hydrodynamics models of planetaries and outline the formation and growth of instabilities that may be seen in these models. It is possible that these may be the forerunners of some of the observed small-scal

K. Asano

The profile of Navarro, Frenk, and White (the NFW profile), which was derived from the {\it N}-body simulations of cold dark-matter halos, is a strong candidate for a galaxy or cluster profile. In order to check the usability of the NFW profile as a first approximation of a galaxy model, we studied the characteristic overdensity and scale radius of galaxies

M. Tosi

The field of chemical evolution modeling of the Galaxy is experiencing in the last years a phase of high activity and important achievements. There are, however, several open questions which still need to be answered. In this review I summarize what have been the most important achievements and what are some of the most urgent questions to be answered.

A. M. Gilbert, J. R. Graham, I. S. McLean, E. E. Becklin

We present infrared spectroscopy of the Antennae Galaxies (NGC 4038/4039) with NIRSPEC at the W. M. Keck Observatory. We imaged the star clusters in the vicinity of the southern nucleus (NGC 4039) in 0.39&#34; seeing in K-band using NIRSPEC&#39;s slit-viewing camera. The brightest star cluster revealed in the near-IR (M_K(0) = -17.9) is insignificant optical

Yasushi Suto, Hiromitsu Magira, Kazuhiro Yamamoto

We present a theoretical formalism to predict the two-point clustering statistics (the power spectrum and the two-point correlation function), simultaneously taking account of the linear velocity distortion, the nonlinear velocity distortion (finger-of-god), the cosmological redshift-space distortion and the light-cone effect. To demonstrate the importance o

M. Marengo, G. G. Fazio, J. L. Hora, W. F. Hoffmann

AGB stars, the precursors of Planetary Nebulae, exhibit high rates of mass loss and eject material in the form of a slow (10-20 km/s), dusty molecular wind. The general belief that the dust component of AGB circumstellar envelopes have smooth density profiles and spherical symmetry have recently been shaken by new high resolution images, showing that clumpy

M. S. Oey, M. A. Dopita, J. C. Shields, R. C. Smith

We present a detailed comparison of optical H II region spectra to photoionization models based on modern stellar atmosphere models. We examine both spatially resolved and integrated emission-line spectra of the HII regions DEM L323, DEM L243, DEM L199, and DEM L301 in the Large Magellanic Cloud. The published spectral classifications of the dominant stars r

Adel Bilal, Jean-Pierre Derendinger, Roger Sauser

We carefully re-examine the issues of solving the modified Bianchi identity, anomaly cancellations and flux quantization in the S^1/Z_2 orbifold of M-theory using the boundary-free &#34;upstairs&#34; formalism, avoiding several misconceptions present in earlier literature. While the solution for the four-form G to the modified Bianchi identity appears to dep

Chong-Sun Chu, Frederic Zamora

We consider the open superstring ending on a D-brane in the presence of a constant NS-NS B field, using the Green-Schwarz formalism. Quantizing in the light-cone gauge, we find that the anti-commutation relations for the fermionic variables of superspace remain unmodified. We also derive the unbroken supersymmetry algebra living on the D-brane. This establis

T. Barreiro, B. de Carlos

We consider different cosmological aspects of Heterotic M-theory. In particular we look at the dynamical behaviour of the two relevant moduli in the theory, namely the length of the eleventh segment (pi rho) and the volume of the internal six manifold (V) in models where supersymmetry is broken by multiple gaugino condensation. We look at different ways to s

T. R. Taylor, C. Vafa

We show how turning on Flux for RR (and NS-NS) field strengths on non-compact Calabi-Yau 3-folds can serve as a way to partially break supersymmetry from N=2 to N=1 by mass deformation. The freezing of the moduli of Calabi-Yau in the presence of the flux is the familiar phenomenon of freezing of fields in supersymmetric theories upon mass deformations.

Shamit Kachru, Sheldon Katz, Albion Lawrence, John McGreevy

We study the F-terms in N=1 supersymmetric, d=4 gauge theories arising from D(p+3)-branes wrapping supersymmetric p-cycles in a Calabi-Yau threefold. If p is even the spectrum and superpotential for a single brane are determined by purely classical ($α^\prime \to 0$) considerations. If p=3, superpotentials for massless modes are forbidden to all orders in $α

P. Kaste, W. Lerche, C. A. Lutken, J. Walcher

B-type D-branes are constructed on two different K3-fibrations over IP_1 using boundary conformal field theory at the rational Gepner points of these models. The microscopic CFT charges are compared with the Ramond charges of D-branes wrapped on holomorphic cycles of the corresponding Calabi-Yau manifold. We study in particular D4-branes and bundles localize

P. H. Damgaard, K. Splittorff

Exploiting Virasoro constraints on the effective finite-volume partition function, we derive generalized Leutwyler-Smilga spectral sum rules of the Dirac operator to high order. By introducing $N_v$ fermion species of equal masses, we next use the Virasoro constraints to compute two (low-mass and large-mass) expansions of the partially quenched chiral conden

Angel M. Uranga

We consider several properties of a set of anti-D$p$-branes in the presence of orientifold $p$-planes in type II theory. This system breaks all the supersymmetries of the theory, but is free of tachyons. In particular, we center on the case of a single anti-D$p$-brane stuck at a negatively charged orientifold $p$-plane, and study its strong coupling behaviou

J. Eisert, M. Wilkens

We consider entanglement-assisted remote quantum state manipulation of bi-partite mixed states. Several aspects are addressed: we present a class of mixed states of rank two that can be transformed into another class of mixed states under entanglement-assisted local operations with classical communication, but for which such a transformation is impossible wi

G. C. Barker, Anita Mehta

We describe the surface properties of a simple lattice model of a sandpile that includes evolving structural disorder. We present a dynamical scaling hypothesis for generic sandpile automata, and additionally explore the kinetic roughening of the sandpile surface, indicating its relationship with the sandpile evolution. Finally, we comment on the surprisingl

Thomas Buchert, Martin Kerscher, Christian Sicka

Averaging and evolving inhomogeneities are non-commuting operations. This implies the existence of deviations of an averaged model from the standard Friedmann-Lemaitre cosmologies. We quantify these deviations, encoded in a backreaction parameter, in the framework of Newtonian cosmology. We employ the linear theory of gravitational instability in the Euleria

G. Arcioni, M. A. Vazquez-Mozo

The thermodynamics of gauge theories on the noncommutative plane is studied in perturbation theory. For U(1) noncommutative Yang-Mills we compute the first quantum correction to the ideal gas free energy density and study their behavior in the low and high temperature regimes. Since the noncommutativity scale effectively cutoff interactions at large distance

A. Andrasi

We test the renormalization of Wilson operators and the Mandelstam- Leibbrandt gauge in the case when the sides of the loop are parallel to the n, n* vectors used in the M-L gauge. Graphs which in the Feynman gauge are free of ultra-violet divergences, in the M-L gauge show double divergences and single divergences with non-local Si and Ci functions. These n

Guy Bonneau

We analyse in a systematic way the (non-)compact n-dimensional Einstein Weyl spaces equipped with a cohomogeneity-one metric. With no compactness hypothesis, we prove that, as soon as the (n-1)-dimensional space is an homogeneous reductive Riemannian space with an unimodular group of left-acting isometries G 1)a non-exact Einstein-Weyl stucture may exist onl

C. S. Lim, Bungo Taga

We work in theories with both light and heavy particles. A method to obtain an effective low energy action with respect to the light particle is presented. Thanks to Wilsonian renormalization, we obtain effective actions with finite number of local operators describing possible non-decoupling effects of heavy particles. The validity of the method is first ch

Fotini Markopoulou

A review is given of recent work aimed at constructing a quantum theory of cosmology in which all observables refer to information measurable by observers inside the universe. At the classical level the algebra of observables should be modified to take into account the fact that observers can only give truth values to observables that have to do with their b

A. M. Shvaika

A general scheme to calculate dynamical susceptibilities of strongly correlated electron systems within the dynamical mean field theory is developed. Approach is based on an expansion over electron hopping around the atomic limit (within the diagrammatic technique for site operators: projection and Hubbard ones) in infinite dimensions. As an example, the Fal

Shoichi Ichinose

We present a new regularization method, for d dim (Euclidean) quantum field theories in the continuum formalism, based on the domain wall configuration in (1+d) dim space-time. It is inspired by the recent progress in the chiral fermions on lattice. The wall &#34;height&#34; is given by 1/M, where M is a regularization mass parameter and appears as a (1+d) d

Eri Asakawa, Jun-ichi Kamoshita, Akio Sugamoto, Isamu Watanabe

We present the effects of heavy CP-even (H) and CP-odd (A) Higgs bosons on the production cross section of the process $γγ$ $\to t\bar{t}$ at the energy around the mass poles of the Higgs bosons. It is found that the interference between H and A with the small mass gap, as well as the ones between Higgs bosons and the continuum, contributes to the cross sect

L. A. Kalyakin

Small perturbation of the Liouville equation under smooth initial data is considered. Asymptotic solution which is available for a long time interval is constructed by the two scale method.

Caroline H Thompson

Another Bell test &#34;loophole&#34; - imperfect rotational invariance - is explored, and novel realist ideas on parametric down-conversion as used in recent &#34;quantum entanglement&#34; experiments are presented. The usual quantum theory of entangled systems assumes we have rotational invariance (RI), so that coincidence rates depend on the difference onl

N. David Mermin

A recent claim that finite precision in the design of real experiments ``nullifies&#39;&#39; the impact of the Kochen-Specker theorem, is shown to be unsupportable, because of the continuity of probabilities of measurement outcomes under slight changes in the experimental configuration.

Miloslav Znojil

We deform the real potential of Poeschl and Teller by a shift of its coordinate in imaginary direction. We show that the new model remains exactly solvable. Its bound states are constructed in closed form. Wave functions are complex and proportional to Jacobi polynomials. Some of them diverge in the Hermitian limit. In contrast, all their energies prove real

Qiong-gui Lin

The scattering of Dirac particles by symmetric potentials in one dimension is studied. A Levinson theorem is established. By this theorem, the number of bound states with even (odd) parity, $n_+$ ($n_-$), is related to the phase shifts $η_+(\pm E_k)$ [$η_-(\pm E_k)$] of scattering states with the same parity at zero momentum as follows: $$η_\pm(μ)+η_\pm(-μ)\

A. G. Kofman, G. Kurizki

We point out that the quantum Zeno effect, i.e., inhibition of spontaneous decay by frequent measurements, is observable only in spectrally finite reservoirs, i.e., in cavities and waveguides, using a sequence of evolution-interrupting pulses or randomly-modulated CW fields. By contrast, such measurements can only accelerate decay in free space.

Pierre Astier, Alessandro Cardini, Robert D. Cousins, Antoine Letessier-Selvon

We give an overview of track fitting using the Kalman filter method in the NOMAD detector at CERN, and emphasize how the wealth of by-product information can be used to analyze track breakpoints (discontinuities in track parameters caused by scattering, decay, etc.). After reviewing how this information has been previously exploited by others, we describe ex

K. Schwarzschild

Communication by K. Schwarzschild to the Prussian Academy of Sciences, dealing with the gravitational field of a sphere of incompressible fluid.

C. Figueira de Morisson Faria, A. Fring, R. Schrader

Stabilization is still a somewhat controversial issue concerning its very existence and also the precise conditions for its occurrence. The key quantity to settle these questions is the ionization probability, for which hitherto no computational method exists which is entirely agreed upon. It is therefore very useful to provide various consistency criteria w

R. M. Davidson, N. Mathur, N. C. Mukhopadhyay

We investigate the electroproduction of eta mesons below a center of momentum energy of 1.6 GeV, with particular emphasis on the roles of the N*(1535) and N*(1520) resonances. Using the effective Lagrangian approach, we show that the transverse helicity amplitude of the N*(1535) can be extracted with good accuracy from the new eta electroproduction data, und

B. v. Przewoski, J. T. Balewski, J. Doskow, H. O. Meyer

The spin correlation coefficent combinations A_{xx}+A_{yy} and A_{xx}-A_{yy}, the spin correlation coefficients A_{xz} and A_{zz}, and the analyzing power were measured for \vec p \vec p --> d pi^+ between center-of-mass angles 25 deg \leq θ\leq 65 deg at beam energies of 350.5, 375.0 and 400.0 MeV. The experiment was carried out with a polarized internal ta

G. Kälbermann

The decay of a soliton in a trapped state inside a well is shown numerically. Bound states of a kink in an attractive well, both centered and off center are found. Their stability is studied. Unstable soliton solutions inside a repulsive barrier are also found.

G. Kälbermann

The nature of the interaction of a soliton with an attractive well is elucidated using a model of two interacting point particles. The system shows the existence of trapped states at positive kinetic energy, as well as reflection by an attractive impurity, as found when a topological soliton scatters off an attractive well.

Pablo A. Ferrari, Pierre Picco

We consider the contour representation of the infinite volume Ising model at low temperature. Fix a subset V of Z^d, and a (large) N such that calling G_{N,V} the set of contours of length at least N intersecting V, there are in average one contour in G_{N,V} under the infinite volume &#34;plus&#34; measure. We find bounds on the total variation distance bet

Pablo A. Ferrari, Alejandro Maass, Servet Martinez, Peter Ney

Consider a finite Abelian group (G,+), with |G|=p^r, p a prime number, and F: G^N -> G^N the cellular automaton given by {F(x)}_n= A x_n + B x_{n+1} for any n in N, where A and B are integers relatively primes to p. We prove that if P is a translation invariant probability measure on G^Z determining a chain with complete connections and summable decay of cor

Ola Bratteli, Palle E. T. Jorgensen

The spectral properties of the Ruelle transfer operator which arises from a given polynomial wavelet filter are related to the convergence question for the cascade algorithm for approximation of the corresponding wavelet scaling function.

Michael G. Eastwood, C. Robin Graham

The Lewy extension theorem asserts the holomorphic extendability of CR functions defined in a neighborhood of a point on a hypersurface in C^{n+1}. The edge-of-the-wedge theorem asserts the extendability of holomorphic functions defined in wedges in C^{n+1} with edge a maximally real submanifold. In this article we prove under suitable hypotheses the holomor

Kiran S. Kedlaya

In an earlier preprint (math.AG/9810142) we gave an explicit description of the algebraic closure of the field of power series over a field of characteristic p, in terms of &#34;generalized power series&#34;. In this paper, we give an analogous description of the algebraic closure of the fraction field of the Witt ring of a field of characteristic p, using a

Kiran S. Kedlaya

We answer a question of Abhyankar by constructing an algebraic closure of the field of power series over a field of positive characteristic, using &#34;generalized power series&#34;. (The corresponding construction in characteristic 0 dates back to Newton.)

Olaf Lechtenfeld, Alexander D. Popov

We study the action of picture-changing and spectral flow operators on a ground ring of ghost number zero operators in the chiral BRST cohomology of the closed N=2 string and describe an infinite set of symmetry charges acting on physical states. The transformations of physical string states are compared with symmetries of self-dual gravity which is the effe

Oliver Schnetz

We present an analytic calculation of the first transcendental in phi^4-Theory that is not of the form zeta(2n+1). It is encountered at 6 loops and known to be a weight 8 double sum. Here it is obtained by reducing multiple zeta values of depth <= 4. We give a closed expression in terms of a zeta-related sum for a family of diagrams that entails a class of p

O. M. Del Cima, D. H. T. Franco, J. A. Helayel-Neto, O. Piguet

In this comment we discuss some serious inconsistencies presented by Gomes, Malacarne and da Silva in their paper, Phys.Rev. D60 (1999) 125016 (hep-th/9908181).

V. Kaplunovsky, J. Sonnenschein, S. Theisen, S. Yankielowicz

The heterotic $E_8\times E_8$ string compactified on an orbifold $T^4/\IZ_N$ has gauge group $G\times G&#39;$ with (massless) states in its twisted sectors which are charged under both gauge group factors. In the dual M-theory on $(T^4/\IZ_N)\otimes(S^1/\IZ_2)$ the two group factors are separated in the eleventh direction and the G and G&#39; gauge fields ar

Ian I. Kogan, Alexei M. Tsvelik

We show that $SL(2;C)/SU(2)$ model which had been recently proposed to describe the behaviour of the local densities of states at the plateau transition in Integer Quantum Hall effect, has logarithmic operators. They unusual properties are studied in this letter.

Matthew J. Strassler

Abelian theories in three dimensions can have linearly confining phases as a result of monopole-instantons, as shown, for SU(2) Yang-Mills theory broken to its abelian subgroup, by Polyakov. In this article the generalization of this phase for N=2 supersymmetric abelian theories is identified, using a dual description. Topologically stable BPS-saturated and

Vincenzo Branchina

By considering the gradient expansion for the wilsonian effective action S_k of a single component scalar field theory truncated to the first two terms, the potential U_k and the kinetic term Z_k, I show that the recent claim that different expansion of the fluctuation determinant give rise to different renormalization group equations for Z_k is incorrect. T

William E. Brown, Juan P. Garrahan, Ian I. Kogan, Alex Kovner

We extend the gauge invariant variational approach of Phys. Rev. D52 (1995) 3719, hep-th/9408081, to theories with fermions. As the simplest example we consider the massless Schwinger model in 1+1 dimensions. We show that in this solvable model the simple variational calculation gives exact results.

R. Acharya, P. Narayana Swamy

We establish that in Quantum Chromodynamics (QCD) at zero temperature, SU_{L+R}(N_F) exhibits the vector mode conjectured by Georgi and SU_{L-R}(N_F) is realized in either the Nambu-Goldstone mode or else Q_5^a is also screened from view at infinity. The Wigner-Weyl mode is ruled out unless the beta function in QCD develops an infrared stable zero.

Nikolaos Kidonakis, J. F. Owens

The resummation of threshold logarithms for direct photon production cross sections in hadronic collisions is presented. The resummation is based on the factorization properties of the cross section and is formulated at next-to-leading logarithmic or higher accuracy. Full analytical and numerical results for the next-to-next-to-leading order expansion of the

Chi-Keung Chow, Thomas D. Cohen

We demonstrate in a model independent way that, in the combined heavy quark and large N_c limit, there exists a new contracted U(4) symmetry which connects orbitally excited heavy baryons to the ground states.

E. V. Bugaev, B. V. Mangazeev, Y. V. Shlepin

The nondiagonal generalized vector dominance model (GVDM) of photoabsorption is elaborated using QCD-motivated picture of the (gamma)-(q,anti q) - transition and subsequent meson dominated scattering of the (q, anti q)-pair on the nucleon. The relativistic constituent quark model for a description of the meson (q, anti q)-wave functionsis used. The meson-nuc

Yu. A. Simonov

New equations are derived for meson and baryon Green&#39;s functions in a systematic method using the QCD Lagrangian and large N_c approximation as a starting point. The equations are shown to contain both confinement dynamics and chiral symmetry breaking. Linear Regge trajectories are demonstrated for the solutions.

Zhiqing Zhang

A precise proton structure function F_2 at low x is measured. The data is interpreted in the framework of QCD with an extraction of gluon density xg. The charm contribution to F_2 is determined in an extended kinematic range. Neutral and charged current cross-sections at high Q^2 are also measured and compared with the Standard Model predictions.

Carl E. Carlson

Hard semiexclusive processes provide an opportunity to design effective currents to probe specific parton distributions and to probe in leading order parton distributions that fully inclusive reactions probe only via higher order corrections. High transverse momentum pion photoproduction is an example of a such a process. We discuss the perturbative and soft

Darwin Chang, A. Zee

We review and remark on models of radiatively induced neutrino Majorana masses and oscillations. It is pointed out that while the models are capable of accounting for the observed solar and atmospheric neutrino oscillation, some of them can also induce neutrinoless double beta decay and $\mu^-$ -- $e^+$ conversion in nuclei large enough to be potentially obs

A. V. Belitsky, A. Freund, D. Müller

We present a formalism and explicit results for two-loop flavor singlet evolution kernels of skewed parton distributions in the minimal subtraction scheme. This approach avoids explicit multiloop calculations in QCD and is based on the known pattern of conformal symmetry breaking in this scheme as well as constraints arising from the graded algebra of the $\

F. Carvalho, F. O. Durães, F. S. Navarra, M. Nielsen

We apply the Meson Cloud Model to the calculation of nonsinglet parton distributions in the nucleon sea, including the octet and the decuplet cloud baryon contributions. We give special attention to the differences between nonstrange and strange sea quarks, trying to identify possible sources of SU(3) flavor breaking. A analysis in terms of the $κ$ parameter

R. Casalbuoni, S. De Curtis, D. Guetta

The present contribution reports a study of the effects of anomalous gauge and fermionic couplings in the process $e^+e^- -> W^+W^-$ at the Next Linear Collider focusing in particular on the option of polarized beams. We conclude that polarized beams with adjustable degree of polarization would constitute a very significant tool in the search for new physics

B. Dressler, M. V. Polyakov

We show that the instanton model of the QCD vacuum indicates the parametric smallness of the twist-3 contributions to the polarized structure function h_L. This smallness is related to the diluteness of the QCD instanton vacuum.

Shi-yuan Li, Zong-guo Si, Qu-bing Xie, Qun Wang

According to the basic properties of QCD, colour reconnection effects can occur in hadronic processes at high energies. The comparison of $e^{+}e^{-}\to Z^0Z^0\to q\bar{q}q&#39;\bar{q&#39;}$ events with the superposition of $Z^0\to q\bar{q}$ and $Z^0\to q&#39;\bar{q&#39;}$ events from LEP1 would provide an unambiguous model-independent probe. We show that at

Hai-Yang Cheng

Implications of recent CLEO measurements of hadronic charmless B decays are discussed.