June 1999 arXiv papers — page 14

Venkatesh Gopal, Hema Ramachandran, A. K. Sood

We study the azimuthal variation in the backscattered intensity that is seen when polarised light is scattered by a turbid medium. We present experimental observations of these intensity variations in colloidal suspensions over a wide range of optical densities. For a medium composed of spherical scatterers, we have developed using Mie scattering theory and

V. Melik-Alaverdian, N. E. Bonesteel, G. Ortiz

The effects of Landau level mixing and finite thickness of the two-dimensional electron gas on the relative stability of skyrmion and single spin-flip excitations at Landau level filling factor $ν=1$ have been investigated. Landau level mixing is studied by fixed-phase diffusion Monte Carlo and finite thickness is included by modifying the effective Coulomb

Valentina S. U. Fazio, L. Komitov, S. T. Lagerwall, D. Möbius

Many nematic liquid crystals are not able to form stable monolayers at the air/water interface because of the lack of a polar headgroup. A possible way to obtain a monomolecular film with these compounds is to incorporate them into host monolayers of amphiphilic compounds. Stable monolayers containing a high fraction of the liquid crystal can be obtained. We

M. Fornari, M. Peressi, S. de Gironcoli, A. Baldereschi

We study in detail by means of ab-initio pseudopotential calculations the electronic structure of five-fold coordinated (T_5) defects in a-Si and a-Si:H, also during their formation and their evolution upon hydrogenation. The atom-projected densities of states (DOS) and an accurate analysis of the valence charge distribution clearly indicate the fundamental

S. D. M. Zwerschke, A. Manolescu, R. R. Gerhardts

We compare the quantum and the classical description of the two-dimensional motion of electrons subjected to a perpendicular magnetic field and a one-dimensional lateral superlattice defined by spatially periodic magnetic and electric fields of large amplitudes. We explain in detail the complicated energy spectra, consisting of superimposed branches of stron

Erik Luijten

An efficient Monte Carlo algorithm for the simulation of spin models with long-range interactions is discussed. Its central feature is that the number of operations required to flip a spin is independent of the number of interactions between this spin and the other spins in the system. In addition, critical slowing down is strongly suppressed. In order to il

Erik Luijten, Kurt Binder

We examine the crossover from classical to non-classical critical behaviour in two-dimensional systems with a one-component order parameter. Since the degree of universality of the corresponding crossover functions is still subject to debate, we try to induce non-universal effects by adding interactions with a second length scale. Although the crossover func

A. Suter, M. Mali, J. Ross, D. Brinkmann

We present a NMR pulse double-irradiation method which allows one to separate magnetic from quadrupolar contributions in the spin-lattice relaxation. The pulse sequence fully saturates one transition while another is observed. In the presence of a Delta m = 2 quadrupolar contribution, the intensity of the observed line is altered compared to a standard spin-

O. Kortlüke, V. N. Kuzovkov, W. von Niessen

We show the existence of internal stochastic resonance in a microscopic stochastic model for the oscillating CO oxidation on single crystal surfaces. This stochastic resonance arises directly from the elementary reaction steps of the system without any external input. The lattice gas model is investigated by means of Monte Carlo simulations. It shows oscilla

M. Guilleumas, L. P. Pitaevskii

Interaction between collective monopole oscillations of a trapped Bose-Einstein condensate and thermal excitations is investigated by means of perturbation theory. We assume spherical symmetry to calculate the matrix elements by solving the linearized Gross-Pitaevskii equations. We use them to study the resonances of the condensate induced by temperature whe

Qunqing Li, Z. D. Wang, Qiang-Hua Wang

The vortex dynamics of a d+is-wave superconductor is studied numerically by simulating the time-dependent Ginzburg-Landau equations. The critical fields, the free flux flow, and the flux flow in the presence of twin-boundaries are discussed. The relaxation rate of the order parameter turns out to play an important role in the flux flow. We also address brief

G. L. W. Hart, W. E. Pickett, E. Z. Kurmaev, D. Hartmann

The electronic structure of spinel-type Cu_(1-x)Ni_xRh_2S_4 (x = 0.0, 0.1, 0.3, 0.5, 1.0) and CuRh_2Se_4 compounds has been studied by means of X-ray photoelectron and fluorescent spectroscopy. Cu L_3, Ni L_3, S L_(2,3) and Se M_(2,3) X-ray emission spectra (XES) were measured near thresholds at Beamline 8.0 of the Lawrence Berkeley Laboratory's Advanced

Dmitri B. Chklovskii

In the primate primary visual area (V1), the ocular dominance pattern consists of alternating monocular stripes. Stripe orientation follows systematic trends preserved across several species. I propose that these trends result from minimizing the length of intra-cortical wiring needed to recombine information from the two eyes in order to achieve the percept

Dmitri B. Chklovskii

I consider a topographic projection between two neuronal layers with different densities of neurons. Given the number of output neurons connected to each input neuron (divergence) and the number of input neurons synapsing on each output neuron (convergence) I determine the widths of axonal and dendritic arbors which minimize the total volume of axons and den

Alexei Vazquez, Jose Marin-Antuña, O. Sotolongo-Costa

Force fluctuations in granular materials are investigated. A continuum equation is derived starting from a discrete model proposed in the literature. The influence of boundary conditions is investigated. For periodic boundary conditions the average weight is found to increase linearly with depth while it saturates to a constant value for absorbing boundary c

E. Zaremba, T. Nikuni, A. Griffin

Starting from an approximate microscopic model of a trapped Bose-condensed gas at finite temperatures, we derive an equation of motion for the condensate wavefunction and a quantum kinetic equation for the distribution function for the excited atoms. The kinetic equation includes collisions between the condensate and non-condensate atoms ($C_{12}$), in addit

Alexei Vazquez, O. Sotolongo-Costa

The avalanche statistics in a stochastic sandpile model where toppling takes place with a probability p is investigated. The limiting case p=1 corresponds to the Bak-Tang-Wiesenfeld (BTW) model with deterministic toppling rule. Based on the moment analysis of the distribution of avalanche sizes we conclude that for 0<p<p_c the model belongs to the DP univers

Th. Meyer, M. J. Bünner, A. Kittel, J. Parisi

Introduced as a model for hyperchaos, the generalized R&#34;ossler system of dimension N is obtained by linearly coupling N-3 additional degrees of freedom to the original R&#34;ossler equation. Under variation of a single control parameter, it is able to exhibit the chaotic hierarchy ranging from fixed points via limit cycles and tori to chaotic and, finall

M. J. Bünner, M. Popp, Th. Meyer, A. Kittel

We propose a method that is able to analyze chaotic time series, gained from exp erimental data. The method allows to identify scalar time-delay systems. If the dynamics of the system under investigation is governed by a scalar time-delay differential equation of the form $dy(t)/dt = h(y(t),y(t-τ_0))$, the delay time $τ_0$ and the functi on $h$ can be recove

Anton V. Runov

Anomalous scaling problem in the stochastic Navier-Stokes equation is treated in the framework of the field theoretical approach, successfully applied earlier to the Kraichnan rapid advection model. Two cases of the space dimensions d=2 and d->infinity, which allow essential simplification of the calculations, are analysed. The presence of infinite set of th

Shin-itiro Goto, Kazuhiro Nozaki

An approximate Poincare map near equally strong multiple resonances is reduced by means the method of averaging. Near the resonance junction of three degrees of freedom, we find that some homoclinic orbits ``whiskers&#39;&#39; in single resonance lines survive and form nearly periodic orbits, each of which looks like a pair of homoclinic orbits.

Y. -Z. Qian, G. J. Wasserburg

We present quantitative predictions for the abundances of r-process elements in stars formed very early in the Galactic history using a phenomenological two-component r-process model based on the I129 and Hf182 inventory in the early solar system. This model assumes that a standard mass of the ISM dilutes the debris from an individual supernova. High frequen

K. Petrovay, V. Martinez-Pillet, L. van Driel-Gesztelyi

In a statistical analysis of Debrecen Photoheliographic Results sunspot area data we find that the logarithmic deviation (log D)&#39; of the area decay rate D from the parabolic mean decay law (derived in the first paper in this series) follows a Gaussian probability distribution. As a consequence, the actual decay rate D and the its time average are also ch

Edward L. Fitzpatrick, D. Massa

We describe a new approach to fitting the UV-to-optical spectra of B stars to model atmospheres and present initial results. Using a sample of lightly reddened stars, we demonstrate that the Kurucz model atmospheres can produce excellent fits to either combined low dispersion IUE and optical photometry or HST FOS spectrophotometry, as long as the following c

Yun Wang, Neta Bahcall, Edwin L. Turner

We derive a simple empirical photometric redshift estimator using a training set of galaxies with multiband photometry and measured redshifts in the Hubble Deep Field (HDF). This estimator is model-independent; it does not use spectral templates. The dispersion between the estimated redshifts and the spectroscopically measured ones is small; the dispersions

Baikal Collaboration, presented by Zh. Dzhilkibaev

We review the present status of the Baikal Neutrino Project. The construction and performance of the large deep underwater Cherenkov detector NT-200 with 192 PMTs, which is currently taking data in Lake Baikal, are described. Some results from intermediate detector stages are presented.

U. Munari, T. Tomov, L. Tomasella, T. Zwitter

The spectroscopic and photometric evolution of the 1999 outburst of the eclipsing and recurrent nova U Sco is presented. The photometric evolution closely matches that of the previous events. The FWZI=10,000 km/sec for emission lines at maximum has decreased to 4000 km/sec by day +23, with continuous and dramatic changes in the line profiles. No nebular line

Sarbani Basu, H. M. Antia

Ring diagram analysis can be used to study large scale velocity fields in the outer part of the solar convection zone. All previous works assume that the peak profiles in the solar oscillation power spectrum are symmetric. However, it has now been demonstrated that the peaks are not symmetric. In this work we study how the explicit use of asymmetric peak pro

P. -A. Duc, E. Brinks, V. Springel, B. Pichardo

Whereas it is well known that gas may be driven into the core of merging disks, fueling a central AGN or a nuclear starburst, recent studies have shown that a significant fraction of the stellar/gaseous components is expelled into the intergalactic medium along tidal tails. The tidal debris might be dispersed in the intergalactic/intracluster medium where it

David Merritt

A retrospective of Martin Schwarzschild&#39;s work on galaxy dynamics.

F. R. Ferraro, M. Messineo, F. Fusi Pecci, M. A. De Palo

A catalog including a set of the most recent Color Magnitude Diagrams (CMDs) is presented for a sample of 61 Galactic Globular Clusters (GGCs). We used this data-base to perform an homogeneous systematic analysis of the evolved sequences (namely, Red Giant Branch (RGB), Horizontal Branch (HB) and Asymptotic Giant Branch (AGB)). Based on this analysis, we pre

Stephen Holland, Pat Cote, James E. Hesser

We used the Wide Field Planetary Camera 2 aboard the Hubble Space Telescope to search for globular clusters in the inner regions of the nearby giant elliptical galaxy NGC 5128. This galaxy is believed to be the product of a merger between a large elliptical galaxy and a small late-type spiral between 160 and 500 Myr ago. We identified 21 globular cluster can

Steen Hannestad

Measurements of the Cosmic Microwave Background Radiation (CMBR) provide a powerful tool for measuring the primary cosmological parameters. However, there is a large degree of parameter degeneracy in simultaneous measurements of the matter density, Omega_m, and the Hubble parameter, H_0. In the present paper we use the presently available CMBR data together

P. Kahabka, H. W. Hartmann, A. N. Parmar, I. Negueruela

BeppoSAX detected luminous 0.2-2.0 keV supersoft X-ray emission from the recurrent nova U Sco ~19-20 days after the peak of the optical outburst in February 1999. U Sco is the first recurrent nova to be observed during a luminous supersoft X-ray phase. Non-LTE white dwarf atmosphere spectral models (together with a ~0.5 keV optically thin thermal component)

HongSheng Zhao

The shape of a galaxy is constrained both by mechanisms of formation (dissipational vs. dissipationless) and by the available orbit families (the shape and amount of regular and stochastic orbits). It is shown that, despite the often very flattened shapes of banana and fish orbits, these boxlet orbits generally do not fit a triaxial galaxy in detail because,

David C. Koo

Masses of galaxies are beginning to be measured systematically at redshifts z > 0.3. Such data provide powerful and unique links and clues to theories, simulations, and our understanding of early galaxy formation and evolution. Discriminating masses of different kinds (e.g., dark matter, old stars, HI gas) remains difficult, but a wide variety of techniques

Daniel Schaerer

Methods for the determination of star formation rates (SFR) from integrated populations are reviewed. We discuss the assumptions and underlying uncertainties (e.g. IMF slope, M_up, metallicity, SF history etc.) used in the calibrations of UV, FIR, Halpha, and [OII] indicators. The ``universality&#39;&#39; of empirically calibrated indicators such as [OII] is

M. Chaves

This paper has been withdrawn by the author because the conclusions reached in it are incorrect.

D0 Collaboration

We report on measurements of inclusive cross sections times branching fractions into electrons for W and Z bosons produced in ppbar collisions at sqrts=1.8 TeV.From an integrated luminosity of 84.5 inverse pb recorded in 1994--1995 using the D0 detector at the Fermilab Tevatron, we determine sigma(ppbar->W+X)B(W->e nu) = 2310 +- 10(stat) +- 50(syst) +- 100(l

Mathias Puetz, Kurt Kremer, Gary S. Grest

We present results of molecular dynamics simulations of very long model polymer chains analyzed by various experimentally relevant techniques. The segment motion of the chains is found to be in very good agreement with the repatation model. We also calculated the plateau-modulus G_N. The predicitions of the entanglement length N_e from G_N and from the mean

G. W. Gibbons, C. A. R. Herdeiro

The geodesics of the rotating extreme black hole in five spacetime dimensions found by Breckenridge, Myers, Peet and Vafa are Liouville integrable and may be integrated by additively separating the Hamilton-Jacobi equation. This allows us to obtain the Stäckel-Killing tensor. We use these facts to give the maximal analytic extension of the spacetime and disc

P. F. Bedaque, H. -W. Hammer, U. van Kolck

We apply the effective field theory approach to the three-nucleon system. In particular, we consider S=1/2 neutron-deuteron scattering and the triton. We show that in this channel a unique nonperturbative renormalization takes place which requires the introduction of a single three-body force at leading order. With one fitted parameter we find a good descrip

In-Saeng Suh, G. J. Mathews

Recently, several white dwarfs with very strong surface magnetic fields have been observed. In this paper we explore the possibility that such stars could have sufficiently strong internal fields to alter their structure. We obtain a revised white dwarf mass-radius relation in the presence of strong internal magnetic fields. We first derive the equation of s

Ken Ohsuga, Masayuki Umemura

By considering the radiative force by a circumnuclear starburst as well as an AGN, we analyze the equilibrium configuration and the stability of dusty gas in the circumnuclear regions. It is found that the radiative force by an intensive starburst can support a stable gaseous wall with a scale-height of several hundred parsecs. Moreover, by taking the simple

Ralph Blumenhagen, Anamaria Font, Dieter Lust

We construct non-supersymmetric four dimensional gauge theories arising as effective theories of D-branes placed on various singularities in Type 0B string theory. We mostly focus on models which are conformal in the large N limit and present both examples appearing on self-dual D3-branes on orbifold singularities and examples including orientifold planes. M

J. Schaffner-Bielich

The effective restoration of the chiral U(A)(1) symmetry in strong interactions is studied using the linear chiral SU(3)xSU(3) model at finite temperatures. We find that the disappearance of the chiral anomaly causes a considerable change in the meson mass spectrum. We propose several signals for detecting this chiral phase in ultrarelativistic heavy-ion col

Angel Ballesteros, Enrico Celeghini, Francisco J. Herranz

The Lie bialgebras of the (1+1) extended Galilei algebra are obtained and classified into four multiparametric families. Their quantum deformations are obtained, together with the corresponding deformed Casimir operators. For the coboundary cases quantum universal R-matrices are also given. Applications of the quantum extended Galilei algebras to classical i

J. Gamboa

An exact expression for the Green function of a purely fermionic system moving on the manifold $\Re \times Σ^{D-1}$, where $Σ^{D-1}$ is a $(D-1)$-torus, is found. This expression involves the bosonic analog of $χ_n = e^{inθ}$ corresponding to the irreducible representation for the n-th class of homotopy and in the fermionic case for D=2 and 3, $χ_n$ is a mea

E. Gaztanaga, G. B. Dalton

We present CCD photometry for galaxies around 204 bright (m_Z < 15.5) Zwicky galaxies in the equatorial extension of the APM Galaxy Survey, sampling and area over 400 square degrees, which extends 6 hours in right ascension. We fit a best linear relation between the Zwicky magnitude system, m_Z, and the CCD photometry, B, by doing a likehood analysis that co

Sanjay

We analyse the leading logarithmic singularities in direct and crossed channel limit of the four-point functions in dilaton-axion sector of type IIB supergravity on $AdS_{5}$ in AdS/CFT correspondence. Logarithms do not cancel in the full correlator in both channels.

J. P. Rodriguez

The uniformly frustrated layered XY model is analyzed in its Villain form. A decouple pancake vortex liquid phase is identified. It is bounded by both first-order and second-order decoupling lines in the magnetic field versus temperature plane. These transitions, respectively, can account for the flux-lattice melting and for the flux-lattice depinning observ

S. H. Chun, M. B. Salamon, Y. Tomioka, Y. Tokura

When heated through the magnetic transition at Tc, La0.7Ca0.3MnO3 changes from a band metal to a polaronic insulator. The Hall constant R_H, through its activated behavior and sign anomaly, provides key evidence for polaronic behavior. We use R_H and the Hall mobility to demonstrate the breakdown of the polaron phase. Above 1.4Tc, the polaron picture holds i

Matthias Otto

Non-equilibrium phenomena occur not only in physical world, but also in finance. In this work, stochastic relaxational dynamics (together with path integrals) is applied to option pricing theory. A recently proposed model (by Ilinski et al.) considers fluctuations around this equilibrium state by introducing a relaxational dynamics with random noise for inte

Kenji Morita, Shin Muroya, Hiroki Nakamura, Chiho Nonaka

We will numerically investgate two-particle correlation function of CERN--SPS 158 A GeV Pb+Pb central collisions in detail based on a (3+1)-dimensional relativistic hydrodynamical model with first order phase transition. We use the Yano-Koonin-Podgoretski\uı parametrization as well as the usual Cartesian parametrization and analyze the pair momentum dependen

Ximing Fang, Xiwen Zhu, Mang Feng, Xi&#39;an Mao

Quantum dense coding has been demonstrated experimentally in terms of quantum logic gates and circuits in quantum computation and NMR technique. Two bits of information have been transmitted through manipulating one of the maximally entangled two-state quantum pair, which is completely consistent with the original ideal of Bennett-Wiesner proposal. Although

Yosuke Imamura

We derive relations between type 0 and type II D-brane configurations under the T-duality suggested by Bergman and Gaberdiel and confirm that the massless fields on D-branes are identical to those on the dual D-brane configurations. Furthermore, we discuss dualities of type 0 and type II NS5-branes and find that the dual of an unwrapped type 0 NS5-brane is a

A. A. Broyles

Wave functions are generally written with arguments consisting of sets of ``particle&#39;&#39; coordinates and quantum numbers. Pauli derived a principle governing the exchange of pairs of sets that differ only in their spatial and spin component $(m_s)$ coordinates. This principle states that an exchange of two of these sets produces the same wave function

Gennady P. Berman, Gary D. Doolen, Vladimir I. Tsifrinovich

We investigate the influence of superpositional wave function oscillations on the performance of Shor&#39;s quantum algorithm for factorization of integers. It is shown that the wave function oscillations can destroy the required quantum interference. This undesirable effect can be routinely eliminated using a resonant pulse implementation of quantum computa

Avinash Khare, Uday Sukhatme

Using the formalism of supersymmetric quantum mechanics, we obtain a large number of new analytically solvable one-dimensional periodic potentials and study their properties. More specifically, the supersymmetric partners of the Lame potentials ma(a+1)sn^2(x,m) are computed for integer values a=1,2,3,.... For all cases (except a=1), we show that the partner

Richard L. Hall

We consider a single particle which is bound by a central potential and obeys the Dirac equation. We compare two cases in which the masses are the same but Va < Vb, where V is the time-component of a vector potential. We prove generally that for each discrete eigenvalue E whose corresponding (large and small) radial wave functions have no nodes, it necessari

Tal Mor, Pawel Horodecki

In this work we show that teleportation is a special case of a generalized Einstein, Podolsky, Rosen (EPR) non-locality. Based on the connection between teleportation and generalized measurements we define conclusive teleportation. We show that perfect conclusive teleportation can be obtained with any pure entangled state, and it can be arbitrarily approache

WonYoung Hwang, Jeong-Young Ji, Jongbae Hong

The concept of wavefunction reduction should be introduced to standard quantum mechanics in any physical processes where effective reduction of wavefunction occurs, as well as in the measurement processes. When the overlap is negligible, each particle obey Maxwell-Boltzmann statistics even if the particles are in principle described by totally symmetrized wa

James Ax, Simon Kochen

The Copenhagen Interpretation describes individual systems, using the same Hilbert space formalism as does the statistical ensemble interpretation (SQM). This leads to the well-known paradoxes surrounding the Measurement Problem. We extend this common mathematical structure to encompass certain natural bundles with connections over the Hilbert sphere S. This

J. C. A. Barata, W. F. Wreszinski

We present a new convergent strong coupling expansion for two-level atoms in external periodic fields, free of secular terms. As a first application, we show that the coherent destruction of tunnelling is a third-order effect. We also present an exact treatment of the high-frequency region, and compare it with the theory of averaging. The qualitative frequen

Alessandro B. Romeo

In this final report, I briefly reflect on two parallel teaching experiences as tutor. Besides, I briefly view such experiences in interaction with my research work, private life and new teaching position. In harmony with my conception of teaching, I avoid the standard formal style of reports and try an interactive dialogue with the reader.

Bao-An Li, Bin Zhang, Andrew T. Sustich, C. M. Ko

Using a relativistic transport model, we study the azimuthal momentum asymmetry of kaons with fixed transverse momentum, i.e., the differential flow, in heavy-ion collisions at beam momentum of 6 GeV/c per nucleon, available from the Alternating Gradient Synchrotron (AGS) at the Brookhaven National Laboratory (BNL). We find that in the absence of kaon potent

C. Bahri, D. J. Rowe

The phenomenological symplectic model with a Davidson potential is used to construct rotational states for a rare-earth nucleus with microscopic wave functions. The energy levels and E2 transitions obatined are in remarkably close agreement (to within a few percent) with those of the rotor model with vibrational shape fluctuations that are adiabatically deco

J. C. R. Bloch, Yu. L. Kalinovsky, C. D. Roberts, S. M. Schmidt

Two-body pion-radiating and weak decays of light axial-vector mesons and the rho are studied as a phenomenological application of the QCD Dyson-Schwinger equations. Models based on the rainbow-ladder truncation are capable of providing a good description and, in particular, yield the correct sign and magnitude of the a1 -> rho pi and b1 -> omega pi D/S ratio

K. Sasaki, T. Inoue, M. Oka

Decays of $Λ$ in nuclei, nonmesonic mode, are studied by using the $ΛN \to NN$ weak transition potential derived from the meson exchange mechanism and the direct quark mechanism. The decay rates are calculated both for the $Λ$ in symmetric nuclear matter and light hypernuclei. We consider the exchange of six mesons ($π, K, η, ρ, ω, K^\ast$). The form factor

Il-Tong Cheon, Myung KI Cheoun

The recent TRIUMF experiment for $μ^- p \to n ν_μ γ$ gave a surprising result that the induced pseudoscalar coupling constant $g_P$ was larger than the value obtained from $μ^- p \to n ν_μ$ experiment as much as 44 %. Reexamining axial vector current on the gauge theory, we found an additional term to the matrix element of Beder and Fearing which was used to

Birger B. Back

This paper presents a selective historical perspective of fission research over the last thirty-five years while Ray Nix has made central contributions to the field. The emphasis is placed on early studies of the shell stabilized secondary minimum in the static fission barrier and on the dynamic properties of fission of hot nuclei, which have recently been t

David P. Blecher, Christian Le Merdy

Let $A$ be a unital Banach algebra. We give a characterization of the left Banach $A$-modules $X$ for which there exists a commutative unital $C^*$-algebra $C(K)$, a linear isometry $i\colon X\to C(K)$, and a contractive unital homomorphism $θ\colon A\to C(K)$ such that $i(a\cdotp x) =θ(a)i(x)$ for any $a\in A, x\in X$. We then deduce a &#34;commutative&#34;

Jian Zhou

We explain how deformation theories of geometric objects such as complex structures, Poisson structures and holomorphic bundle structures lead to differential Gerstenhaber or Poisson algebras. We use homological perturbation theory to obtain $A_{\infty}$ algebra structures and some canonically defined deformations of such structures on the cohomology. We for

Charles F. Dunkl, Donald E. Ramirez

Exact expressions are given for the distribution function of the ratio of a weighted sum of independent chi-squared variables to a single chi-square variable, scaled appropriately. This distribution is the generalization of the classical F distribution to mixtures of chi-squared variables. The distribution is given in terms of the Lauricella functions. The t

Olga Plamenevskaya

Jeffrey and Kirwan suggested expressions for intersection pairings on the reduced space of a Hamiltonian G-space in terms of multiple residues. In this paper we prove a residue formula for symplectic volumes of reduced spaces of a quasi-Hamiltonian SU(2)-space. The definition of quasi-Hamiltonian G-spaces was recently introduced by Alekseev, Malkin and Meinr

Anne Schilling, S. Ole Warnaar

In this paper it is shown that the one-dimensional configuration sums of the solvable lattice models of Andrews, Baxter and Forrester and the string functions associated with admissible representations of the affine Lie algebra A$_1^{(1)}$ as introduced by Kac and Wakimoto can be exploited to yield a very general class of conjugate Bailey pairs. Using the re

Ilka Agricola

Sei G eine zusammenhängende reduktive komplexe algebraische Gruppe, die auf einer glatten affinen komplexen Varietät M wirke, und bezeichne $\Diff[G]{M}$ die G-invarianten algebraischen Differentialoperatoren auf M. Zerlegt man den Koordinatenring $\Aff{\C}{M}$ in G-isotypische Komponenten, so zeigen wir, daß die hierbei auftretenden Vielfachheitenräume irre

Jean-Yves Welschinger

The aim of this article is to obtain restrictions on complex orientations of dividing real J-curves of almost-complex manifolds. This problem comes from real algebraic geometry and the main result is a congruence generalising Arnol&#39;d, Rokhlin, Mishachev, Zvonilov and Mikhalkin &#39;s previous results. This congruence is obtained with a canonical map defi

Steven Corley

An initial step is taken in investigating the duality between the near horizon region of a four dimensional extremal Reissner-Nordstrom black hole and the n-particle, N=4 Calogero model as conjectured by Gibbons and Townsend. Specifically we compute the mass spectrum of d=4, N=8 supergravity about the Bertotti-Robinson solution and find the corresponding set

Franco Ferrari, Ignazio Lazzizzera

In this work we derive certain topological theories of transverse vector fields whose amplitudes reproduce topological invariants involving the interactions among the trajectories of three and four random walks. This result is applied to the construction of a field theoretical model which describes the statistical mechanics of an arbitrary number of topologi

Abbas Ali

Classification of N=4 superconformal symmetries in two dimensions is re-examined. It is proposed that apart from SU(2) and $SU(2)\times SU(2)\times U(1)$ their Kac-Moody symmetry can also be $SU(2)\times(U(1))^4$. These superconformal symmetries and corresponding algebras are named small, large and middle ones respectively. Operator product expansions for th

Masato Arai, Noriaki Kitazawa

To obtain some exact results of U(1) gauge theory (QED), we construct the low energy effective action of N=2 supersymmetric QED with a massless matter and Fayet-Iliopoulos term, assuming no confinement. The harmonic superspace formalism for N=2 extended supersymmetry makes the construction easy. We analyze the vacuum structure and find no vacuum. It suggests

A. Bashir, J. Lorenzo Diaz-Cruz

We study Schwinger-Dyson equation for fermions in Yukawa and Wess-Zumino models, in terms of dynamical mass generation and the wavefunction renormalization function. In the Yukawa model with $γ_5$-type interaction between scalars and fermions, we find a critical coupling in the quenched approximation above which fermions acquire dynamical mass. This is shown

Felipe J. Llanes-Estrada, Stephen R. Cotanch

Results from an extensive relativistic many-body analysis utilizing a realistic effective QCD Hamiltonian are presented for the meson spectrum. A comparative numerical study of the BCS, TDA and RPA treatments provides new, significant insight into the condensate structure of the vacuum, the chiral symmetry governance of the pion and the meson spin, orbital a

S. J. Huber, M. Reuter, M. G. Schmidt

The gluon spin coupling to a Gaussian correlated background gauge field induces an effective tachyonic gluon mass. It is momentum dependent and vanishes in the UV only like 1/p^2. In the IR, we obtain stabilization through a positive m^2_{conf}(p^2) related to confinement. Recently a purely phenomenological tachyonic gluon mass was used to explain the linear

J. -M. Gerard, J. Weyers

In inclusive decays of the $Ψ$ (3097), electromagnetic and gluonic annihilation amplitudes add incoherently, namely they are 90$^\circ$ out of phase. We argue that this incoherence must persist in each exclusive decay channel. For inclusive $Ψ&#39;$ (3686) decays, we suggest the absence of a significant direct annihilation amplitude into three gluons and pro

M. Czakon, M. Zralek, J. Gluza

We have renormalized a classical left-right model with a bidoublet, and left and right triplets in the Higgs sector. We focus on oblique corrections and show the interplay between the top quark, heavy neutrinos and Higgses contribution to the muon $Δr$ parameter. In the SM, custodial symmetry prevents large oblique corrections to appear. Although in LR model

Paolo Ciafaloni

Future lepton colliders will provide a powerful tool for making precision experiments at energies that will range typically between 500 GeV and 2 TeV. At such high energies, one loop electroweak corrections are bigger than one could naively expect a priori. Thus, the calculation of higher order electroweak effects (and possibly their resummation) might be ne

Aiichi Iwazaki

We show that axionic boson stars collide with isolated old neutron stars with strong magnetic field ($>10^8$ Gauss) and causes the neutron stars to radiate X ray by heating them. Surface temperatures of such neutron stars becomes$10^5 K \sim 10^6 K$. We suggest that these are possible candidates for X ray sources observed in ROSAT Survey. We discuss a possib

SESAM Collaboration, A. Spitz, H. Hoeber, N. Eicker

We estimate the QCD coupling constant from a lattice calculation of the bottomonium spectrum. The second order perturbative expansion of the plaquette expectation value is employed to determine alpha_S at a scale set by the 2S-1S and 1P-1S level splittings. The latter are computed in NRQCD in a dynamical gauge field background with two degenerate flavours of

G. P. Zeller, T. Adams, A. Alton, S. Avvakumov

The NuTeV experiment at Fermilab presents a determination of the electroweak mixing angle. High purity, large statistics samples of muon-neutrino and muon-antineutrino events allow the use of the Paschos-Wolfenstein relation. This considerably reduces systematic errors associated with charm production and other sources. With Standard Model assumptions, this

A. P. Heinson

This paper presents the latest measurements of the properties of the top quark as determined by the DZero and CDF collaborations at the Fermilab Tevatron ppbar collider. Both experiments have studied the all-hadronic decay mode of ttbar events. The top quark measurement has been refined over the past year, with the addition of new channels and a re-evaluatio

Giovanni Landi

We review some work done with C. Rovelli on the use of the eigenvalues of the Dirac operator on a curved spacetime as dynamical variables, the main motivation coming from their invariance under the action of diffeomorphisms. The eigenvalues constitute an infinite set of ``observables&#39;&#39; for general relativity and can be taken as variables for an invar

A. W. Whinnett

We study boson stars in Brans Dicke gravity and use them to illustrate some of the properties of three different mass definitions: the Schwarzschild mass, the Keplerian mass and the Tensor mass. We analyse the weak field limit of the solutions and show that only the Tensor mass leads to a physically reasonable definition of the binding energy. We examine num

Lisa Ferro, Marc Vilain, Alexander Yeh

Grammatical relationships are an important level of natural language processing. We present a trainable approach to find these relationships through transformation sequences and error-driven learning. Our approach finds grammatical relationships between core syntax groups and bypasses much of the parsing phase. On our training and test set, our procedure ach

Gert Veldhuijzen van Zanten, Gosse Bouma, Khalil Sima&#39;an, Gertjan van Noord

The NWO Priority Programme Language and Speech Technology is a 5-year research programme aiming at the development of spoken language information systems. In the Programme, two alternative natural language processing (NLP) modules are developed in parallel: a grammar-based (conventional, rule-based) module and a data-oriented (memory-based, stochastic, DOP)

Sabine Glesner, Karl Stroetmann

We show that the question whether a term is typable is decidable for type systems combining inclusion polymorphism with parametric polymorphism provided the type constructors are at most unary. To prove this result we first reduce the typability problem to the problem of solving a system of type inequations. The result is then obtained by showing that the so

Dmitri B. Chklovskii, Alexei A. Koulakov

We propose a theory for ocular dominance (OD) patterns in mammalian primary visual cortex. This theory is based on the premise that OD pattern is an adaptation to minimize the length of intra-cortical wiring. Thus we can understand the existing OD patterns by solving a wire length minimization problem. We divide all the neurons into two classes: left-eye dom

L. Ozyuzer, J. F. Zasadzinski, N. Miyakawa

Tunneling spectra are reported for Bi_{2}Sr_{2}CaCu_{2}O_{8+δ} (Bi-2212) over a wide doping range using superconductor-insulator-superconductor (SIS) break junctions. The energy gap inferred from the tunneling data displays a remarkable monotonic dependence on doping, increasing to very large values in the underdoped region even as T_c decreases. This leads

Anupam Garg

The spin Hamiltonian that describes the molecular magnet Fe$_8$ has biaxial symmetry with mutually perpendicular easy, medium, and hard magnetic axes. Previous calculations of the ground state tunnel splittings in the presence of a magnetic field along the hard axis are extended, and the meaning of the previously discovered oscillation of this splitting is f