July 1999 arXiv papers — page 11

A. V. Belitsky

We address the problem of solution of the QCD three-particle evolution equations which govern the Q-dependence of the chiral-even quark-gluon-quark and three-gluon correlators contributing to a number of asymmetries at leading order and the transversely polarized structure function g_2(x). The quark-gluon-quark case is completely integrable in multicolour li

Jerzy Lewandowski

We characterize a general solution to the vacuum Einstein equations which admits isolated horizons. We show it is a non-linear superposition -- in precise sense -- of the Schwarzschild metric with a certain free data set propagating tangentially to the horizon. This proves Ashtekar's conjecture about the structure of spacetime near the isolated horizon.

M. A. De Andrade, I. V. Vancea

We show that there exists a duality between the local coordinates and the solutions of the Klein-Gordon equation in curved spacetime in the same sense as in the Minkowski spacetime. However, the duality in curved spacetime does not have the same generality as in flat spacetime and it holds only if the system satisfies certain constraints. We derive these con

Hae-Young Kee, Yong Baek Kim, Kazumi Maki

We study spin excitations in a two dimensional p-wave superconductor with ${\vec Δ} = {\hat d}({\hat k}_1 \pm i {\hat k}_2)$ symmetry in the context of the newly discovered superconducting Sr$_2$RuO$_4$. The polarization and spectrum of spin wave excitations are identified and their experimental consequences are discussed.

R. De Pietri, L. Freidel, K. Krasnov, C. Rovelli

Boulatov and Ooguri have generalized the matrix models of 2d quantum gravity to 3d and 4d, in the form of field theories over group manifolds. We show that the Barrett-Crane quantum gravity model arises naturally from a theory of this type, but restricted to the homogeneous space S^3=SO(4)/SO(3), as a term in its Feynman expansion. From such a perspective, 4

S. F. Hassan

We obtain the T-duality transformations of space-time spinors (the supersymmetry transformation parameters, gravitinos and dilatinos) of type-II theories in curved backgrounds with an isometry. The transformation of the spinor index is shown to be a consequence of the twist that T-duality introduces between the left and right-moving local Lorentz frames. The

Joseph C. Weingartner, B. T. Draine

We model the photoelectric emission from and charging of interstellar dust and obtain photoelectric gas heating efficiencies as a function of grain size and the relevant ambient conditions. Using realistic grain size distributions, we evaluate the net gas heating rate for various interstellar environments, and find less heating for dense regions characterize

Alan Chodos

There are (at least) four numbers of physical and cosmological significance whose inferred values, when expressed in mass units, cluster in a window below 1 eV. These are: the neutrino mass, the neutrino chemical potential, the cosmological constant, and the size of two extra dimensions (if the fundamental scale of gravity is 1-10 TeV). In this note, we imag

T. H. Hansson, S. Viefers

Starting from recently proposed bosonic mean field theories for fully and partially polarized quantum Hall states, we construct corresponding effective low energy theories for the edge modes. The requirements of gauge symmetry and invariance under global O(3) spin rotations, broken only by a Zeeman coupling, imply boundary conditions that allow for edge spin

Katrin Reblinsky, Guido Kruse, Bhuvnesh Jain, Peter Schneider

The aperture mass has been shown in a series of recent publications to be a useful quantitative tool for weak lensing studies, ranging from cosmic shear to the detection of a mass-selected sample of dark matter haloes. Quantitative analytical predictions for the aperture mass have been based on a number of simplifying assumptions. In this paper, we test the

Kentaro Urasaki, Tetsuro Saso

Effects of electron correlation in FeSi are studied in terms of the two-band Hubbard model with the density of states obtained from the band calculation. Using the self-consistent second-order perturbation theory combined with the local approximation, the correlation effects are investigated on the density of states and the optical conductivity spectrum, whi

F. Laube, G. Goll, H. v. Löhneysen, M. Fogelström

The superconducting gap function of Sr$_2$RuO$_4$ was investigated by means of quasiparticle reflection and transmission at the normal conductor-superconductor interface of Sr$_2$RuO$_4$-Pt point contacts. We found two distinguishly different types of $dV/dI$ vs $V$ spectra either with a double-minimum structure or with a zero-bias conductance anomaly. Both

Enrique Alvarez, Cesar Gomez

A candidate for the confining string of gauge theories is constructed via a representation of the ultraviolet divergences of quantum field theory by a closed string dilaton insertion, computed through the soft dilaton theorem. The resulting (critical) confining string is conformally invariant, singles out naturally $d=4$ dimensions, and can not be used to re

Theodora Ioannidou, George Papadopoulos, Paul Sutcliffe

We show that CPn sigma model solitons solve the field equations of a Dirac-Born-Infeld (DBI) action and, furthermore, we prove that the non-BPS soliton/anti-soliton solutions of the sigma model also solve the DBI equations. Using the moduli space approximation we compare the dynamics of the BPS sigma model solitons with that of the associated DBI solitons. W

Michael B. Green, Michael Gutperle, Hwang-h. Kwon

The linearized interactions of eleven-dimensional supergravity are obtained in a manifestly supersymmetric light-cone gauge formalism. These vertices are used to calculate certain one-loop processes involving external gravitini, antisymmetric three-form potentials and gravitons, thereby determining some protected terms in the effective action of M-theory com

J. E. Garcia-Ramos, J. M. Arias, J. Dukelsky, P. Van Isacker

An intrinsic-state formalism for IBM-4 is presented. A basis of deformed bosons is introduced which allows the construction of a general trial wave function which has Wigner's spin-isospin SU(4) symmetry as a particular limit. Intrinsic-state calculations are compared with exact ones showing good agreement.

J. Dolbeau

We report the status of the solar neutrino project called HELLAZ. In a high pressure and cooled TPC filled with helium, the detection of each ionisation electron of the track produced by the recoil electron from elastic scattering induced by solar neutrinos, will yield the low energy, high resolution solar neutrino spectrum. Two topics are presented ; test o

G. Belanger, F. Boudjema, J. Fujimoto, T. Ishikawa

A general non-linear gauge condition is implemented into GRACE, an automated system for the calculation of physical processes in high-energy physics. This new gauge-fixing is used as a very efficient means to check the results of large scale evaluation in the standard model computed automatically. We report on some systematic test-runs which have been perfor

A. A. Saghiri, J. Linkemann, M. Schmitt, D. Schwalm

Dielectronic recombination has been investigated for Delta-n = 1 resonances of ground-state Li+(1s^2) and for Delta-n = 0 resonances of metastable Li+(1s2s ^3S). The ground-state spectrum shows three prominent transitions between 53 and 64 eV, while the metastable spectrum exhibits many transitions with energies < 3.2 eV. Reasonably good agreement of R-matri

Alexey K. Mazur

Recently it has been found that stable and accurate molecular dynamics (MD) of B-DNA duplexes can be obtained in relatively inexpensive computational conditions with the bulk solvent represented implicitly, but the minor groove filled with explicit water (J. Am. Chem. Soc. 1998, 120, 10928). The present paper further explores these simulation conditions in o

Xue-Shang Feng, Yong Liu, Feng-Si Wei, Zhan-Yin Ye

In this paper, two classes of exact analytic time-dependent soultion of magnetic annihilation for incompressible magnetic fluid, have been obtained by solving the magnetohydrodynamic (MHD) equations directly. The solutions derived here possess scaling property with time $t$ as the scale factor. Based on these two solutions, we find that, for some given inflo

Armen Sedrakian, Umberto Lombardo

We study the neutron-proton pairing in nuclear matter as a function of isospin asymmetry at finite temperatures and the saturation density using realistic nuclear forces and Brueckner-renormalized single particle spectra. Our computation of the thermodynamic quantities shows that while the difference of the entropies of the superconducting and normal phases

Boris Tomasik, Urs Achim Wiedemann, Ulrich Heinz

Analyzing the m_t-spectrum and two-particle correlations of negative hadrons from 158 AGeV/c Pb+Pb collisions at slightly forward rapidities we find a (thermal) freeze-out temperature of about 100 MeV and transverse flow with <v_t> approximately 0.55c. The M_t-dependence of the correlation radii prefers a box-like transverse density profile over a Gaussian.

Q. B. Li, P. N. Shen

In the framework of $RGM$, the binding energy of the six quark system with strangeness s=-5 is systematically investigated under the SU(3) chiral constituent quark model. The single $Ξ^*Ω$ channel calculation with spins S=0 and 3 and the coupled $ΞΩ$ and $Ξ^*Ω$ channel calculation with spins S=1 and 2 are considered, respectively. The results show following

R. J. Furnstahl, Brian D. Serot

The implications of an effective field theory (EFT) interpretation of nuclear mean-field phenomenology are reviewed.

Alejandro Ayala, Sangyong Jeon, Joseph Kapusta

We compute the Coulomb distortion produced by an expanding and highly charged fireball on the spectra of low transverse momenta and mid rapidity pions produced in central high energy heavy ion collisions. We compare to data on Au+Au at 11.6A GeV from E866 at the BNL AGS and of Pb+Pb at 158A GeV from NA44 at the CERN SPS. We match the fireball expanison veloc

The NA44 Collaboration

The NA44 Collaboration has measured yields and differential distributions of K+, K-, pi+, pi- in transverse kinetic energy and rapidity, around the center-of-mass rapidity in 158 A GeV/c Pb+Pb collisions at the CERN SPS. A considerable enhancement of K+ production per pi is observed, as compared to p+p collisions at this energy. To illustrate the importance

I. Passchier, R. Alarcon, Th. S. Bauer, D. Boersma

We report on the first measurement of spin-correlation parameters in quasifree electron scattering from vector-polarized deuterium. Polarized electrons were injected into an electron storage ring at a beam energy of 720~MeV. A Siberian snake was employed to preserve longitudinal polarization at the interaction point. Vector-polarized deuterium was produced b

C. P. Viazminsky

Incompressible fields are of a special importance in electrodynamics, fluid mechanics, and quantum mechanics. We shall derive a few expressions for such fields in a Riemannian manifold, and show how to generate an incompressible field from an arbitrary set of scalar differentiable functions. The concept of compressibility removing factors of an arbitrary vec

Bruce W. Jordan, Ron Livné

This paper considers a higher-dimensional generalization of the notion of Ramanujan graphs, defined by Lubotzky, Phillips, and Sarnak. Specifically the Ramanujan property is studied for cubical complexes which are uniformized by an ordered product of regular trees. We construct explicit arithmetic examples using quaternion algebras over totally real fields.

Wen-Chen Chi, Anly Li

In this paper a Kummer theory of division points over rank one Drinfeld A=Fq[T]-modules defined over global function fields was given. The results are in complete analogy with the classical Kummer theory of division points over the multiplicative algebraic group Gm defined over number fields.

Daniel C. Cohen, Peter Orlik

We use stratified Morse theory to construct a complex to compute the cohomology of the complement of a hyperplane arrangement with coefficients in a complex rank one local system. The linearization of this complex is shown to be the Orlik-Solomon algebra with the connection operator. Using this result, we establish the relationship between the cohomology sup

Fumiharu Kato

This is a revised version of a part of the author&#39;s preprint &#34;On p-adic uniformization of fake projective planes&#34; (preprint, Max-Planck-Institut fuer Mathematik, 1998 (121)). In this paper we construct explicitly a Shimura surface of PEL-type, associated to a certain unitary group, whose connected components are isomorphic to Mumford&#39;s fake p

Vladimir Hinich

We prove that the category of algebras over a cofibrant operad admits a closed model category structure. This leads to the notion of &#34;virtual operad algebra&#34; - the algebra over a cofibrant resolution of the given operad. In particular, virtual commutative algebras can serve to an algebraic description of homotopy p-tipes as in the recent preprint of

W. M. Oxbury, S. Ramanan

Let SU_C(2) denote the moduli variety of rank 2 semistable vector bundles with trivial determinant on an algebraic curve C. We prove that if C is trigonal then there exists a projective moduli variety N_C containing SU_C(2) as a subvariety and smooth of dimension 7g-14 away from SU_C(2). N_C parametrises Galois Spin(8)-bundles on the Galois closure of C over

J. L. Boldo, B. M. Pimentel, J. L. Tomazelli

In this work we study how the infrared sector of the interaction Hamiltonian can affect the construction of the S matrix operator of QED in (2+1) dimensions.

A. Kempf

In quantum theory, real degrees of freedom are usually described by operators which are self-adjoint. There are, however, exceptions to the rule. This is because, in infinite dimensional Hilbert spaces, an operator is not necessarily self-adjoint even if its expectation values are real. Instead, the operator may be merely symmetric. Such operators are not di

David Nolland, Paul Mansfield

We discuss the functional representation of fermions, and obtain exact expressions for wave-functionals of the Schwinger model. Known features of the model such as bosonization and the vacuum angle arise naturally. Contrary to expectations, the vacuum wave-functional does not simplify at large distances, but it may be reconstructed as a large time limit of t

Theodora Ioannidou, Paul Sutcliffe

We construct non-BPS dyon solutions of N=4 SU(n) supersymmetric Yang-Mills theory. These solutions are the worldvolume solitons which describe non-BPS Type IIB non-planar string junctions connecting n parallel D3-branes. The solutions are smooth deformations of the 1/4 BPS states which describe planar string junctions.

Masaru Kamata, Atsushi Nakamula

The ADHM construction, which yields (anti-)selfdual configurations in classical Yang-Mills theories, is applied to an infinite dimensional l^2 vector space, and as a consequence, a family of (anti-)selfdual configurations with a parameter q is obtained for SU(2) Yang-Mills theory. This l^2 formulation can be seen as a q-analog of Nahm&#39;s monopole construc

Robert L. Thews, Johann Rafelski

The B_C meson is the bound state of b-cbar whose recent detection is the first step toward completion of the spectroscopy of heavy quark mesonic states. The b-c states have properties that conveniently fill the gap between the J/Psi and Upsilon states. Thus it is probable that at RHIC the B_c mesons will serve as a probe of deconfined matter. We find that si

M. Carena, S. Mrenna, C. E. M. Wagner

We study the properties of the Higgs boson sector in the MSSM, putting special emphasis on radiative effects which can affect the discovery potential of the LHC, Tevatron and/or LEP colliders. We concentrate on the V b b-bar channel, with V=Z or W, and on the channels with diphoton final states, which are the dominant ones for the search for a light Standard

D. London

I review the prospects for the detection of Delta L=2 processes at future colliders. Except in contrived models, the process e- e- -> W- W- is unobservable at future linear colliders unless $\sqrt{s} \gsim 2$ TeV, due to constraints from neutrinoless double beta decay. As there are no analogous constraints on the Majorana mass of the $ν_μ$, mu- mu- -> W- W-

A. Bashir, A. Kizilersu, M. R. Pennington

We evaluate the analytic expression for the one-loop fermion-boson vertex in massless QED3 in an arbitrary covariant gauge. The result is written in terms of elementary functions of its momenta. The vertex is decomposed into a longitudinal part, that is fully responsible for ensuring the Ward and Ward-Takahashi identities are satisfied, and a transverse part

Mary Alberg, Ernest M. Henley, Gerald A. Miller

We use the meson cloud model of the nucleon to calculate distribution functions for $(\bar {d} - \bar{u})$ and $ \bar{d}/\bar{u}$ in the proton. Including the effect of the omega meson cloud, with a coupling constant $g_ω^2/4π\approx 8$, allows a reasonably good description of the data.

S. Scherer

We discuss the virtual Compton scattering amplitude $γ^\ast+π\to γ+π$ which enters the reaction $π^-+e^-\toπ^-+e^-+γ$. The low-energy scattering amplitude is divided into a model-independent part, involving only the electromagnetic form factor, and a residual part which contains structure information related specifically to (virtual) Compton scattering. In t

Flavio Pereira, Erasmo Ferreira

The dips observed in the differential cross sections of elastic pp and p$\bar{\rm p}$ scattering are studied in terms of the locations of the zeros of the real and imaginary parts of the amplitude and of the sign of real part at large $|t|$. It is confirmed that the differences in shapes of the dips in the pp and p$\bar{\rm p}$ systems are determined by a ch

R. Sekhar Chivukula, Nick Evans

The triviality of the scalar sector of the standard one-doublet Higgs model implies that this model is only an effective low-energy theory valid below some cut-off scale Lambda. For a heavy higgs this scale must be relatively low (10 TeV or less). Additional interactions coming from the underlying theory, and suppressed by the scale Lambda, give rise to mode

Christopher D. Carone

We present a model-independent analysis of the mass spectrum of nonstrange l=1 baryons in large N_c QCD. The 1/N_c expansion is used to select and order a basis of effective operators that spans the nine observables (seven masses and two mixing angles). Comparison to the data provides support for the validity of the 1/N_c expansion, but also reveals that onl

V. L. Eletsky, B. L. Ioffe, J. I. Kapusta

Our recent work on modifications of rho-mesons formed at the last stage of evolution of hadronic matter produced in heavy ion collisions is summarized. It is found that while the mass shift is on the order of a few tens of MeV, the width and spectral density become so broad that rho may lose its identity as a well defined resonance.

M. W. Krasny

In high centre-of-mass energy lepton-nucleon collisions the space-time time resolution of partonic processes can be {\it fine-tuned} within a dynamical range which is unattainable in hadronic collisions. Replacing nucleons by nuclei of variable atomic number enables one to tune the strength of colour forces. The experimental program of high energy electron-n

M. Ciafaloni, D. Colferai, G. P. Salam

We propose a simple model for studying small-x physics in which we take only the collinearly enhanced part of leading and subleading kernels, for all possible transverse momentum orderings. The small-x equation reduces to a second order differential equation in t=log k^2/Lambda^2 space, whose perturbative and strong-coupling features are investigated both an

G. Battistoni, A. Ferrari, P. Lipari, T. Montaruli

An extensive 3-dimensional Monte Carlo calculation of the atmospheric neutrino flux is in progress with the FLUKA Monte Carlo code. The results are compared to those obtained under the 1-dimensional approximation, where secondary particles and decay products are assumed to be collinear to the primary cosmic ray, as usually done in most of the already existin

Z. Burda, J. Jurkiewicz, A. Krzywicki

We put fermions and define the Dirac operator and spin structures on a randomly triangulated 2d manifold.

A. Krzywicki

The non-perturbative, lattice field theory approach towards the quantization of Euclidean gravity is reviewed. Included is a tentative summary of the most significant results and a presentation of the current state of art.

F. Farchioni, I. Hip, C. B. Lang

We study the eigenvalue spectrum of different lattice Dirac operators (staggered, fixed point, overlap) and discuss their dependence on the topological sectors. Although the model is 2D (the Schwinger model with massless fermions) our observations indicate possible problems in 4D applications. In particular misidentification of the smallest eigenvalues due t

A. Di Giacomo

A review is presented of what we understand of colour confinement in QCD. Lattice formulation provides evidence that QCD vacuum is a dual superconductor: the chromoelectric field of a $q\bar q$ pair is constrained by dual Meissner effect into a dual Abrikosov flux tube and the static potential energy is proportional to the distance.

E. Elizalde

Different aspects concerning the rigorous definition of the traces and determinants of the operators involved in a procedure ---proposed by Neuberger and others--- for avoiding fermion doublers on the lattice, are considered. A result of the analysis is that it seems unclear that the consequences derived from the independent treatment of the traces of the tw

M. N. Achasov, V. M. Aulchenko, A. V. Berdyugin, A. V. Bozhenok

SND (Spherical Neutral Detector) is a general purpose nonmagnetic detector, successfully operating at Novosibirsk VEPP-2M collider during last four years in the center of mass energy range from 400 MeV up to 1400 MeV. Its crucial part is a 3-layer, fine grained, spherical NaI(Tl) electromagnetic calorimeter consisted of 1632 individual counters. Here we pres

M. Apollonio, A. Baldini, C. Bemporad, E. Caffau

We present new results based on the entire CHOOZ data sample. We find (at 90% confidence level) no evidence for neutrino oscillations in the anti_nue disappearance mode, for the parameter region given by approximately Delta m**2 > 7 x 10**-4 eV^2 for maximum mixing, and sin**2(2 theta) = 0.10 for large Delta m**2. Lower sensitivity results, based only on the

T. Hadig

This paper summarizes a talk presented at the Durham HERA &#39;98 Workshop. We compare the features that are available in NLO pQCD programs and demonstrate that understanding where in phase space NLO calculations are accurate is vital for extracting information from measurements at the HERA experiments.

Lior M. Burko

We study analytically the Cauchy horizon singularity inside spherically-symmetric charged black holes, coupled to a spherical self-gravitating, minimally-coupled, massless scalar field. We show that all causal geodesics terminate at the Cauchy horizon at a null singularity, which is weak according to the Tipler classification. The singularity is also deforma

Dan Solomon

It is well known that there can be negative energy densities in quantum field theory. Most of the work done in this area has involved free non-interacting systems. In this paper we show how a quantum state with negative energy density can be formulated for a Dirac field interacting with an Electromagnetic field. It will be shown that, for this case, there ex

David Eppstein, Marshall W. Bern, Brad Hutchings

We describe simple linear time algorithms for coloring the squares of balanced and unbalanced quadtrees so that no two adjacent squares are given the same color. If squares sharing sides are defined as adjacent, we color balanced quadtrees with three colors, and unbalanced quadtrees with four colors; these results are both tight, as some quadtrees require th

Olivier Devillers, Franco P. Preparata

An efficient technique to solve precision problems consists in using exact computations. For geometric predicates, using systematically expensive exact computations can be avoided by the use of filters. The predicate is first evaluated using rounding computations, and an error estimation gives a certificate of the validity of the result. In this note, we stu

Krzysztof R. Apt, Andrea Schaerf

The aim of the Alma project is the design of a strongly typed constraint programming language that combines the advantages of logic and imperative programming. The first stage of the project was the design and implementation of Alma-0, a small programming language that provides a support for declarative programming within the imperative programming framework

M. J. Graf, S. -K. Yip, J. A. Sauls

We report new theoretical results and analysis for the transport properties of superconducting UPt3 based on the leading models for the pairing symmetry. We use Fermi surface data and the measured inelastic scattering rate to show that the low-temperature thermal conductivity and transverse sound attenuation in the A and B phase of UPt3 are in excellent agre

K. Schaadt, A. Kudrolli

The parametric variation of the eigenfrequencies of a chaotic plate is measured and compared to random matrix theory using recently calculated universal correlation functions. The sensitivity of the flexural modes of the plate to pressure is used to isolate this symmetry class of modes and simplify the data analysis. The size of the plate is used as the exte

H. Pastoriza, S. Candia, G. Nieva

By means of a novel technique of rotating the applied current we have directly measured the influence of twin boundaries on the vortex motion in a YBa$_2$Cu$_3$O$_7$ single crystal. The results indicate that the effect of twin planes on the vortex dynamics starts to develop below a certain temperature, being responsible for an anisotropic viscosity in the vo

A. E. Dementyev, N. N. Kuzma, P. Khandelwal, S. E. Barrett

The Knight shift and the nuclear spin-lattice relaxation rate 1/T1 of Ga-71 nuclei are measured in GaAs quantum wells at Landau level filling factor nu = 1/2 using optically pumped NMR. The temperature dependences of these data are compared with predictions of a weakly-interacting composite fermion model. Our measurements of the electron spin polarization an

A. H. MacDonald, Matthew P. A. Fisher

We propose a quantum stripe (smectic) coupled-Luttinger-liquid model for the anisotropic states which occur in two-dimensional electron systems with high-index partial Landau level filling, $ν^{*} = ν- \lbrackν\rbrack$. Perturbative renormalization group calculations establish that interaction terms neglected in this model are relevant - probably driving the

Yu. S. Barash

Influence of surface pair breaking, barrier transmission and phase difference on quasiparticle bound states in junctions with d-wave superconductors is examined. Based on the quasiclassical theory of superconductivity, an approach is developed to handle interface bound states. It is shown in SIS&#39; junctions that low energy bound states get their energies

Giorgio Mazzeo, Reimer Kuehn

The equilibrium ensemble approach to disordered systems is used to investigate the critical behaviour of the two dimensional Ising model in presence of quenched random site dilution. The numerical transfer matrix technique in semi- infinite strips of finite width, together with phenomenological renormalization and conformal invariance, is particularly suited

P. S&#34;ule, S. Kurth, V. Van Doren

Various orbital-dependent exchange-only potentials are studied which exhibit correct long-range asymptotic behaviour. We present the first application of these potentials for polymers and by one of these potentials for molecules. Kohn-Sham type calculations have been carried out for polyethylene in order to make valuable comparison of these potentials with e

Y. -P. Pellegrini, M. Barthelemy, G. Perrin

A formulation of variational principles in terms of functional integrals is proposed for any type of local plastic potentials. The minimization problem is reduced to the computation of a path integral. This integral can be used as a starting point for different approximations. As a first application, it is shown how to compute to second-order the weak-disord

Anders Johansen, Didier Sornette

Twenty-two significant bubbles followed by large crashes or by severe corrections in the Argentinian, Brazilian, Chilean, Mexican, Peruvian, Venezuelan, Hong-Kong, Indonesian, Korean, Malaysian, Philippine and Thai stock markets indices are identified and analysed for log-periodic signatures decorating an average power law acceleration. We find that log-peri

Marek Cieplak, Trinh Xuan Hoang, Mai Suan Li

Scaling of folding properties of proteins is studied in a toy system -- the lattice Go model with various two- and three- dimensional geometries of the maximally compact native states. Characteristic folding times grow as power laws with the system size. The corresponding exponents are not universal. Scaling of the thermodynamic stability also indicates size

S. Trebst, N. Elstner, H. Monien

We report results from a systematic strong-coupling expansion of a spin-1/2 Heisenberg chain coupled to Einstein phonons. In the non-adiabatic regime this model is used to describe zero temperature properties of CuGeO3. The linked cluster expansion allows the determination of observables in the thermodynamic limit preserving the full lattice dynamics without

S. Caprara, C. Castellani, C. Di Castro, M. Grilli

We present a coherent scenario for the physics of cuprate superconductors, which is based on a charge-driven inhomogeneity, i.e. the ``stripe phase&#39;&#39;. We show that spin and charge critical fluctuations near the stripe instability of strongly correlated electron systems provide an effective interaction between the quasiparticles, which is strongly mom

K. Sasaki, Z. F. Ezawa

We make a semiclassical analysis of thermal pair creations of quasiparticles at various filling factors in quantum Hall systems. It is argued that the gap energy is reduced considerably by the Coulomb potential made by impurities. It is also shown that a tunneling process becomes important at low temperature and at strong magnetic field. We fit typical exper

Christoph Richard

We apply a framework for the description of random tilings without height representation, which was proposed recently, to the special case of quasicrystalline random tilings. Several important examples are discussed, thereby demonstrating the consistency of this alternative description with the conventional one. We also clarify the latter by deriving a group

M. Knupfer, T. Pichler, M. S. Golden, J. Fink

We have performed momentum dependent electron energy-loss studies of the electronic excitations in sexithiophene and compared the results to those from parent oligomers. Our experiment probes the dynamic structure factor S(q,omega)and we show that the momentum dependent intensity variation of the excitations observed can be used to extract the size of the el

M. Fischer, P. Lemmens, G. Els, G. Güntherodt

We present a detailed analysis of light scattering experiments performed on the quarter-filled spin ladder compound $α^\prime$-NaV$_{2}$O$_{5}$ for the temperature range 5 K$\le$T$\le$300 K. This system undergoes a phase transition into a singlet ground state at T=34 K accompanied by the formation of a super structure. For T$\leq$34 K several new modes were

C. Godreche, J. M. Luck

We pursue our investigation of the non-equilibrium dynamics of the Backgammon model, a dynamical urn model which exhibits aging and glassy behavior at low temperature. We present an analytical study of the scaling behavior of the local correlation and response functions of the density fluctuations of the model, and of the associated fluctuation- dissipation

Holger Frahm, Constantin Sobiella

The low temperature magnetization process of antiferromagnetic spin-S chains doped with mobile spin-(S-1/2) carriers is studied in an exactly solvable model. For sufficiently high magnetic fields the system is in a metallic phase with a finite gap for magnetic excitations. In this phase which exists for a large range of carrier concentrations x the zero temp

S. E. Barnes

Intermediate spin, which occurs in the theory of anyons, can also be exhibited by mesoscopic magnetic particles. The necessary broken time reversal symmetry is due to a suitably directed magnetic field. As a function of this field a system passes periodically through points which correspond to whole or half-integer spin. Intermediate spin is defined by field

S. Daul, R. M. Noack

We investigate the ground-state phase diagram of the half-filled one-dimensional Hubbard model with next-nearest-neighbor hopping using the Density-Matrix Renormalization Group technique as well as an unrestricted Hartree-Fock approximation. We find commensurate and incommensurate disordered magnetic insulating phases and a spin-gapped metallic phase in addi

Sumio Ishihara, Sadamichi Maekawa

In layered manganites with orbital and charge orderings, the degeneracy of the Mn $4p$ orbitals as well as the $3d$ ones is lifted by the effects of the $4p$ bands and the local Coulomb interactions. We formulate the atomic scattering factor for the resonant x-ray scattering in the memory function method by taking into account these effects on an equal footi

Olivier Collet

A rigourous Monte Carlo method for protein folding simulation on lattice model is introduced. We show that a parameter which can be seen as the rigidity of the conformations has to be introduced in order to satisfy the detailed balance condition. Its properties are discussed and its role during the folding process is elucidated. This method is applied on sma

A. A. Norton, R. K. Ulrich, R. I. Bush, T. D. Tarbell

We report on the spatial distribution of magnetogram oscillatory power and phase angles between velocity and magnetogram signals as observed with the Michelson Doppler Imager. The dataset is 151.25 arcsec times 151.25 arcsec containing sunspot from Dec 2, 1997 with a temporal sampling interval of 60 seconds and spatial sampling of 0.605 arcsec. Simultaneousl

Michael J. Kaufman, Mark G. Wolfire, David J. Hollenbach, Michael L. Luhman

Photodissociation Region (PDR) models are computed over a wide range of physical conditions, from those appropriate to giant molecular clouds illuminated by the interstellar radiation field to the conditions experienced by circumstellar disks very close to hot massive stars. These models use the most up-to-date values of atomic and molecular data, the most c

Uros Seljak, Matias Zaldarriaga

We show that clusters of galaxies induce step-like wiggles on top of the cosmic microwave background (CMB). The direction of the wiggle is parallel to the large scale gradient of CMB allowing one to isolate the effect from other small scale fluctuations. The effect is sensitive to the deflection angle rather than its derivative (shear or magnification) and i

Aparna Chitre, U. C. Joshi

We present the results of a detailed morphological analysis of ten starburst galaxies selected from the Markarian catalogue of uv-excess objects. CCD surface photometry of these galaxies was carried out based on observations made in B, V (Johnson) and R, I (Kron-Cousins) band passes. We present the radial variations of surface brightness, ellipticity, positi

S. D. Van Dyk, C. Y. Peng, A. J. Barth, A. V. Filippenko

The locations of supernovae in the local stellar and gaseous environment in galaxies contain important clues to their progenitor stars. Access to this information, however, has been hampered by the limited resolution achieved by ground-based observations. High spatial resolution Hubble Space Telescope (HST) images of galaxy fields in which supernovae had bee

A. Treves, E. Pian, F. Scaltriti, E. Palazzi

In this contribution two papers on the BL Lac object PKS 2155-304 are presented. They are based on our program of systematic intensive optical monitoring in search of fast variability events. In the first paper the results of a CCD photometric campaign conducted at ESO (La Silla, Chile) on 6-14 July 1998, for a total time on the source of ~30 hours. Some pec

S. M. Bradbury, I. H. Bond, A. C. Breslin, J. H. Buckley

We give an overview of the current status and scientific goals of VERITAS, a proposed hexagonal array of seven 10 m aperture imaging Cherenkov telescopes. The selected site is Montosa Canyon (1390 m a.s.l.) at the Whipple Observatory, Arizona. Each telescope, of 12 m focal length, will initially be equipped with a 499 element photomultiplier camera covering

C. Afonso, C. Alcock, S. H. Rhie, A. Udalski et al.

We fit the data for the binary-lens microlensing event MACHO 98-SMC-1 from 5 different microlensing collaborations and find two distinct solutions characterized by binary separation d and mass ratio q: (d,q)=(0.54,0.50) and (d,q)=(3.65,0.36), where d is in units of the Einstein radius. However, the relative proper motion of the lens is very similar in the tw

I. Mazzitelli, F. D&#39;Antona, P. Ventura

We present results from new, detailed computations of lithium production by hot bottom burning (HBB) in asymptotic giant branch (AGB) stars of intermediate mass. The dependance of lithium production on stellar mass, metallicity, mass loss rate, convection and overshooting are discussed. In particular, nuclear burning, turbulent mixing and convective overshoo

Silvia Behar, Moshe Carmeli

Observations show that for disk galaxies the fourth power of the circular velocity of stars around the core of the galaxy is proportional to the luminosity L. This is known as the Tully-Fisher law. Since L is proportional to the mass M of the galaxy, it follows that the fourth power of the circular velocity is proportional to M. Newtonian mechanics, however,

K. Shiidsuka, S. Ida

The ratio of the vertical velocity dispersion to radial one (sigma_z / sigma_R) of self-gravitating bodies in various disc potentials is investigated through two different numerical methods (statistical compilation of two-body encounters and N-body simulations). The velocity dispersion generated by two-body relaxation is considered. The ratio is given as a f