December 1998 arXiv papers — page 5

Serge Galam, Bastien Chopard, Alexander Masselot, Michel Droz

A simple cellular automata model for a two-group war over the same territory is presented. It is shown that a qualitative advantage is not enough for a minority to win. A spatial organization as well a definite degree of aggressiveness are instrumental to overcome a less fitted majority. The model applies to a large spectrum of competing groups: smoker-non s

Ch. Gruber, J. Piasecki

We consider a one-dimensional system consisting of two infinite ideal fluids, with equal pressures but different temperatures T_1 and T_2, separated by an adiabatic movable piston whose mass M is much larger than the mass m of the fluid particules. This is the infinite version of the controversial adiabatic piston problem. The stationary non-equilibrium solu

Hidekazu Nojiri

We apply self-consistent second order perturbation theory (SCSOPT) with respect to the on-site repulsive interaction U to study the Hubbard model in two dimensions. We investigate single particle properties of the model over the entire doping range at zero temperature. It is shown that as doping decreases toward half-filling $ω$-mass enhancement factor incre

K. E. Nagaev

We argue that the nearly 1/3 suppression of shot noise in nondegenerate diffusive contacts recently obtained by Gonzalez et al. (cond-mat/9803372) is due to the specific choice of the energy-independent elastic scattering time.

Hikaru Kawamura

Superfluidity ordering of thin ^3He films is studied by Monte Carlo simulations based on a two-dimensional lattice spin model with Z_2\times U(1)\times SO(3) symmetry. Successive phase transitions with an intermediate `chiral' phase, in which the l-vector aligns keeping the phase of the condensate disordered, is found. Possible experiments to detect the

A. S. Alexandrov, A. M. Bratkovsky

The exchange interaction of polaronic carriers with localized spins leads to a ferromagnetic/paramagnetic transition in doped charge-transfer insulators with strong electron-phonon coupling. The relative strength of the exchange and electron-phonon interactions determines whether the transition is first or second order. A giant drop in the number of current

Tetsuo Hanaguri, Takashi Tsuboi, Yoshishige Tsuchiya, Ken-ichi Sasaki

In-plane complex surface impedance of a Bi2Sr2CaCu2Oy single crystal was measured in the mixed state at 40.8 GHz.The surface reactance, which is proportional to the real part of the effective penetration depth, increased rapidly just above the first-order vortex-lattice melting transition field and the second magnetization peak field.This increase is ascribe

Chunli Zhang, Eric Jeckelmann, Steven R. White

The spectral weight functions and the optical conductivity of the Holstein model are studied on a one-dimensional six-site lattice with periodic boundary conditions for three different electron concentrations: a single electron, two electrons of opposite spins, and half filling. A density matrix approach is used to obtain an optimal phonon basis and to trunc

L. C. Garcia de Andrade

The Meissner effect for superconductors in spacetimes with torsion is revisited. Two new physical interpretations are presented. The first considers the Landau-Ginzburg theory yields a new symmetry-breaking vacuum depending on torsion. In the second interpretation a gravitational Meissner torsional effect where when the Higgs field vanishes, torsion and elec

S. Jaimungal, M. H. S. Amin, G. Rose

A tight-binding model of electron dynamics in mesoscopic normal rings is studied using boundary conformal field theory. The partition function is calculated in the low energy limit and the persistent current generated as a function of an external magnetic flux threading the ring is found. We study the cases where there are defects and electron-electron inter

B. DeMarco, J. L. Bohn, J. P. Burke,, M. Holland

We have measured independently both s-wave and p-wave cross-dimensional thermalization rates for ultracold potassium-40 atoms held in a magnetic trap. These measurements reveal that this fermionic isotope has a large positive s-wave triplet scattering length in addition to a low temperature p-wave shape resonance. We have observed directly the p-wave thresho

R. J. Bursill

A variant of White's density matrix renormalisation group scheme which is designed to compute low-lying energies of one-dimensional quantum lattice models with a large number of degrees of freedom per site is described. The method is tested on two exactly solvable models---the spin-1/2 antiferromagnetic Heisenberg chain and a dimerised XY spin chain. To

L. G. S. Duarte, L. A. C. P. da Mota, H. P. de Oliveira, R. O. Ramos

A set of MapleV R.4/5 software routines for calculating the numerical evolution of dynamical systems and flexibly plotting the results is presented. The package consists of an initial condition generator (on which the user can impose quite general constraints), a numerical solving manager, plotting commands that allow the user to locate and focus in on regio

Marco Tavani

We discuss some open problems concerning the origin and the emission mechanism of gamma-ray bursts (GRBs) in light of recent developments. If GRBs originate at extragalactic distances, we are facing four crises: (1) an energy crisis, models have to account for more than 10^{53} ergs of energy emitted in the gamma-ray energy band; (2) a spectral crisis, emiss

Zeljko Ivezic, Gillian R. Knapp

We find that AGB stars separate in the 25-12 vs. 12-K color-color diagram according to their chemistry (O, S vs. C) and variability type (Miras vs. SRb/Lb). While discrimination according to the chemical composition is not surprising, the separation of Miras from SRb/Lb variables is unexpected. We show that ``standard'' steady-state radiatively drive

C. Megan Urry

The past 20 years have seen phenomenal progress in our understanding of BL Lac objects. They form part of the blazar class, which are radio-loud AGN whose relativistic jets are aligned along our line of sight. Several critical milestones have helped establish this picture, first proposed at the Pittsburgh BL Lac meeting 20 years ago, most recently the EGRET

Gabriele Ghisellini

The recent BeppoSAX observations of the BL Lac objects Mkn 501 and 1ES 2344+514 have shown that the synchrotron spectrum of these objects peaks, in a v-vF(v) representation, at energies at or above 100 keV. One can wonder if these are the most extreme examples of hard synchrotron blazars, or if they are the first cases of a more numerous class of sources. He

H. Li, S. A. Colgate, M. Kusunose, R. V. E. Lovelace

The lack of our knowledge on how angular momentum is transported in accretion disks around black holes has prevented us from fully understanding their high energy emissions. We briefly highlight some theoretical models, emphasizing the energy flow and electron energization processes. More questions and uncertainties are raised from a plasma physics point of

S. Borgani, M. Plionis, E. Kolokotronis

We present an analysis of the 2-point correlation function, of the X-ray Brightest Abell-type Cluster sample (XBACs; Ebeling et al. 1998) and of the cosmological constraints that it provides. If ξ(r) is modelled as a power-law, we find r_0=26.0 +/- 4.5 Mpc/h and γ=2.0 +/-0.4, with errors corresponding to 2σuncertainties. Only a marginal increase of the corre

B. Pfeiffer, K. -L. Kratz, F. -K. Thielemann, J. J. Cowan

Proc. IX. Workshop on Nuclear Astrophysics, Ringberg Castle, Tegernsee, Bavaria; March 1998

P. Parma, M. Murgia, R. Morganti, A. Capetti

Two frequency observations, mainly at 1.4 and 5 GHz from the VLA, have been used to study spectral variations along the lobes of some nearby low luminosity radio galaxies that constitute a representative sample selected from the B2 catalogue. The variations of the spectral index have been interpreted as being due to synchrotron and inverse Compton losses and

D. Puy, M. Signore

The study of primordial chemistry of molecules adresses a number of interesting questions pertaining to the thermal balance of collapsing molecular protoclouds. In numerous astrophysical cases molecular cooling and heating influence dynamical evolution of the medium. The existence of a significant abundance of molecules can be crucial on the dynamical evolut

Thierry Contini, Daniel Schaerer, Daniel Kunth

Detection and analysis of Wolf-Rayet (WR) star populations in young starbursts is a powerful tool to reveal the properties of the star-forming events. We present new high S/N optical spectra of a sample of well-known WR galaxies, in which we detected for the first time the spectral signature of WC stars. The detailed comparison of WN and WC star populations

C. Wolf, K. Meisenheimer, H. -J. Roeser, CADIS team

We present follow-up spectroscopy to the Calar Alto Deep Imaging Survey (CADIS), reporting on the quasars in the CADIS 16h-field, and including preliminary data from two other fields. In this 10' x 10' field we found six quasars at redshift z>2.2 which are brighter than R=22 mag, while surface densities determined in previous surveys are reported to

L. Kuiper, W. Hermsen, F. Verbunt, T. Belloni

We report the detection of pulsed X-ray emission ($4.9σ$) from the binary millisecond pulsar PSR J0218+4232 in a 100 ks ROSAT HRI observation. The pulse profile shows a sharp main pulse and an indication for a second weaker pulse at $\sim$ 0.47 phase separation. The pulsed fraction is 37 \pm 13%. PSR J0218+4232 was several times in the field of view of the h

F. Durret, D. Gerbal, C. Lobo, C. Pichon

This paper is the fourth of a series dealing with the cluster of galaxies ABCG 85. Using our two extensive photometric and spectroscopic catalogues (with 4232 and 551 galaxies respectively), we discuss here three topics derived from optical data. First, we present the properties of emission line versus non-emission line galaxies, showing that their spatial d

L. Kuiper, W. Hermsen, J. M. Krijger, K. Bennett

We report the COMPTEL detection of pulsed $γ$-emission from PSR B1509-58 up to at least 10 MeV using data collected over more than 6 years. The 0.75-10 MeV lightcurve is broad and reaches its maximum near radio-phase 0.38, slightly beyond the maximum found at hard X-rays/ soft $γ$-rays. In the 10-30 MeV energy range a strong source is present in the skymap p

E. J. Kerins, N. W. Evans

The only microlensing events towards the Magellanic Clouds for which the location of the lens is strongly constrained are the two binary caustic crossing events. In at least one and possibly both cases, the lens lies at, or close to, the clouds themselves. On the face of it, this seems an improbable occurrence if the Galactic dark halo provides the bulk of t

Paul. A. Crowther

Recent progress in the quantitative analysis of Wolf-Rayet stars is reviewed, emphasising the role played by choice of spectral diagnostics, clumping and line blanketing on derived stellar properties. The ionizing properties of WR stars are discussed, based on clumped, line blanketed models for WN and WC stars. The role of metallicity and mass-loss is assess

A. C. Andersen, C. Jager, H. Mutschke, A. Braatz

We present here the first infrared spectra of meteoritic SiC grains. The mid-infrared transmission spectra of meteoritic SiC grains isolated from the Murchison meteorite were measured in the wavelength range 2.5--16.5 micron, in order to make available the optical properties of presolar SiC grains. These grains are most likely stellar condensates with an ori

O. A. Kuznetsov, M. E. Prokhorov, M. V. Sazhin, V. M. Chechetkin

We consider the dependence of the internal structure of a neutron star in a close binary system on the semi-major axis of the binary orbit, focusing on the case when the Roche lobes of the components are nearly filled. We adopt a polytropic equation of state. The temporal evolution of the semi-major axis and its dependence on the mass ratio of the binary com

Joel R. Primack, James S. Bullock, Rachel S. Somerville, Donn MacMinn

We present here the extragalactic background light (EBL) predicted by semi-analytic models of galaxy formation, and show how measurements of the absorption of gamma rays of $\sim$ TeV energies via pair production on the EBL can probe cosmology and the formation of galaxies. Semi-analytic models permit a physical treatment of the key processes of galaxy forma

K. Mannheim, R. J. Protheroe, J. P. Rachen

We obtain the maximum diffuse neutrino intensity predicted by hadronic photoproduction models of the type which have been applied to the jets of active galactic nuclei or gamma ray bursts. For this, we compare the proton and gamma ray fluxes associated with hadronic photoproduction in extragalactic neutrino sources with the present experimental upper limit o

Jose' P. S. Lemos

Gravitational collapse of radiation in an anti-de Sitter background is studied. For the spherical case, the collapse proceeds in much the same way as in the Minkowski background, i.e., massless naked singularities may form for a highly inhomogeneous collapse, violating the cosmic censorship, but not the hoop conjecture. The toroidal, cylindrical and planar c

L. G. Moretto, L. Beaulieu, L. Phair, G. J. Wozniak

The multiplicity distributions for individual fragment Z values in nuclear multifragmentation are binomial. The extracted maximum value of the multiplicity is found to depend on Z according to m=Z_0/Z, where Z_0 is the source size. This is shown to be a strong indication of statistical coverage of fragmentation phase space. The inferred source sizes coincide

Heinz Sorge

Elliptic flow of the hot, dense system which has been created in nucleus-nucleus collisions develops as a response to the initial azimuthal asymmetry of the reaction region. Here it is suggested that the magnitude of this response shows a ``kinky'' dependence on the centrality of collisions for which the system passes through a first-order or rapid t

Paul M. N. Feehan, Peter B. Kronheimer, Thomas G. Leness, Tomasz S. Mrowka

In this article we show that some of the recent results of Marino, Moore, and Peradze (math.DG/9812042, hep-th/9812055) -- in particular their conjecture that all closed, smooth four-manifolds with b_2^+ > 1 (and Seiberg-Witten simple type) are of `superconformal simple type' -- can be understood using a simple mathematical argument via the PU(2)-monopol

V. K. Dobrev

We give a group-theoretic interpretation of the AdS/CFT correspondence as relation of representation equivalence between representations of the conformal group describing the bulk AdS fields $ϕ$ and the coupled boundary fields $ϕ_0$ and ${\cal O}$. We use two kinds of equivalences. The first kind is equivalence between bulk fields and boundary fields and is

A. Yu. Alekseev, V. Schomerus

It is stated in the literature that D-branes in the WZW-model associated with the gluing condition J = - \bar{J} along the boundary correspond to branes filling out the whole group volume. We show instead that the end-points of open strings are rather bound to stay on `integer' conjugacy classes. In the case of SU(2) level k WZW model we obtain k-1 two dimen

David Kastor, Euy Soo Na

Monopole ``superpartner'' solutions are constructed by acting with finite, broken supersymmetry transformations on a bosonic N=2 BPS monopole. The terms beyond first order in this construction represent the backreaction of the the fermionic zero-mode state on the other fields. Because of the quantum nature of the fermionic zero-modes, the superpartne

P. Mathieu, M. A. Walton

The principal admissible representations of affine Kac-Moody algebras are studied, with a view to their use in conformal field theory. We discuss the generation of the set of principal admissible highest weights, concentrating mainly on $A_r^{(1)}$ at rational level $k$. A related algorithm is described that produces the Malikov-Feigen-Fuchs null vectors of

Jerrold Franklin

A simple analytical solution is found to the Dirac equation for the combination of a Coulomb potential with a linear confining potential. An appropriate linear combination of Lorentz scalar and vector linear potentials, with the scalar part dominating, can be chosen to give a simple Dirac wave function. The binding energy depends only on the Coulomb strength

M. Hirsch, J. W. F. Valle

We reanalyze the contributions to neutrinoless double beta ($\znbb$) decay from supersymmetry with explicit breaking of R-parity. Although we keep both bilinear and trilinear terms, our emphasis is put on bilinear R-parity breaking terms, because these mimic more closely the models where the breaking of R-parity is spontaneous. Comparing the relevant Feynman

M. Heerema, F. Ritort

We consider damage spreading transitions in the framework of mode-coupling theory. This theory describes relaxation processes in glasses in the mean-field approximation which are known to be characterized by the presence of an exponentially large number of meta-stable states. For systems evolving under identical but arbitrarily correlated noises we demonstra

Jack Lidmar, Mats Wallin

We study vortex lines in high-temperature superconductors with columnar defects produced by heavy ion irradiation. We reconsider scaling theory for the Bose glass transition with tilted magnetic fields, and propose, e.g., a new scaling form for the shape of the Bose glass phase boundary, which is relevant for experiments. We also consider Monte Carlo simulat

C. Barrabès, V. Frolov, R. Parentani

We study how fluctuations of the black hole geometry affect the properties of Hawking radiation. Even though we treat the fluctuations classically, we believe that the results so obtained indicate what might be the effects induced by quantum fluctuations in a self consistent treatment. To characterize the fluctuations, we use the model introduced by York in

H. D. Zeh

This is a brief reply to Goldstein's article on ``Quantum Theory Without Observers'' in Physics Today. It is pointed out that Bohm's pilot wave theory is successful only because it keeps Schrödinger's (exact) wave mechanics unchanged, while the rest of it is observationally meaningless and solely based on classical prejudice.

Wenfei Yu, Ti Pei Li, William Zhang, Shuang Nan Zhang

We report on an RXTE/PCA observation of Aql X-1 during its outburst in March 1997 in which, immediately following a Type-I burst, the broad-band 2-10 keV flux decreased by about 10% and the kilohertz QPO frequency decreased from 813+-3 Hz to 776+-4 Hz. This change in kHz QPO frequency is much larger than expected from a simple extrapolation of a frequency-fl

Eduardo Eyras, Yolanda Lozano

We construct the effective action of the KK-monopole in a massive Type IIA background. We follow two approaches. First we construct a massive M-theory KK-monopole from which the IIA monopole is obtained by double dimensional reduction. This eleven dimensional monopole contains two isometries: one under translations of the Taub-NUT coordinate and the other un

V. S. Fadin, R. Fiore, A. Papa

We calculate the quark part of the kernel of the generalized non-forward BFKL equation at non-zero momentum transfer $t$ in the next-to-leading logarithmic approximation. Along with the quark contribution to the gluon Regge trajectory, this part includes pieces coming from the quark-antiquark production and from the quark contribution to the radiative correc

G. Lazarides

A moderate extension of the minimal supersymmetric standard model which includes a U(1)_(B-L) gauge group (B and L being the baryon and lepton number) and a Peccei-Quinn symmetry, U(1)_PQ, is presented. The hybrid inflationary scenario is automatic and `natural' in this model. The mu problem of the minimal supersymmetric standard model is solved by coupl

M. Hirayama, M. Kanno, M. Ueno, H. Yamakoshi

The consistency condition of the Faddeev-Niemi ansatz for the gauge-fixed massless SU(2) gauge field is discussed. The generality of the ansatz is demonstrated by obtaining a sufficient condition for the existence of the three-component field introduced by Faddeev and Niemi. It is also shown that the consistency conditions determine this three-component fiel

T. Kinoshita, M. Nio

The contribution of the $α^3$ single electron-loop vacuum-polarization diagrams to the Lamb shift of the muonic hydrogen has been evaluated recently by two independent methods. One uses the exact parametric representation of the vacuum-polarization function while the other relies on the Padé approximation method. High precision of these values offers an oppo

Naoki Itoh, Satoshi Nozawa, Yasuharu Kohyama

We extend the formalism of the relativistic thermal and kinematic Sunyaev-Zel'dovich effects and include the polarization of the cosmic microwave background photons. We consider the situation that a cluster of galaxies is moving with a velocity \vec{v} with respect to the cosmic microwave background radiation. In the present formalism, polarization of th

T. Kinoshita, M. Nio

The sixth-order electron-loop vacuum-polarization contribution to the $2P_{1/2} - 2S_{1/2}$ Lamb shift of the muonic hydrogen ($μ^{-} p^+$ bound state) has been evaluated numerically. Our result is 0.007608(1) meV. This eliminates the largest uncertainty in the theoretical calculation. Combined with the proposed precision measurement of the Lamb shift it wil

Taekoon Lee

The goldstino-matter interactions given by the Goldberger-Treiman relations can receive higher dimensional operator corrections of $ O(q^{2}/M^{2})$, where $M$ denotes the mass of the mediators through which SUSY breaking is transmitted. These corrections in the gauge mediated SUSY breaking models arise from loop diagrams, and an explicit calculation of such

Fritz Gesztesy, Helge Holden

We develop a systematic approach to the classical Boussinesq (cBsq) hierarchy based on an elementary polynomial recursion formalism. Moreover, the gauge equivalence between the cBsq and AKNS hierarchies is studied in detail and used to provide an effortless derivation of algebro-geometric solutions and their theta function representations of the cBsq hierarc

Fritz Gesztesy, Helge Holden

An elementary yet remarkable similarity between the Cole-Hopf transformation relating the Burgers and heat equation and Miura's transformation connecting the KdV and mKdV equations is studied in detail.

S. Lafortune, B. Grammaticos, A. Ramani

We study the projective systems in both continuous and discrete settings. These systems are linearizable by construction and thus, obviously, integrable. We show that in the continuous case it is possible to eliminate all variables but one and reduce the system to a single differential equation. This equation is of the form of those singled-out by Painlevé i

Y. Nutku

The real homogeneous Monge-Ampère equation in one space and one time dimensions admits infinitely many Hamiltonian operators and is completely integrable by Magri's theorem. This remarkable property holds in arbitrary number of dimensions as well, so that among all integrable nonlinear evolution equations the real homogeneous Monge-Ampère equation is dis

A. S. Carstea

Extending the gauge-invariance principle for τfunctions of the standard bilinear formalism to the supersymmetric case, we define N=1 supersymmetric Hirota operators. Using them, we bilinearize SUSY KdV-type equations (KdV, Sawada-Kotera, Hirota-Satsuma). The solutions for multiple collisions of super-solitons and extension to SUSY sine-Gordon are also discus

Lisa Hales, Sean Hallgren

We isolate and generalize a technique implicit in many quantum algorithms, including Shor's algorithms for factoring and discrete log. In particular, we show that the distribution sampled after a Fourier transform over ${\mathbb Z}_p$ can be efficiently approximated by transforming over ${\mathbb Z}_q$ for any q in a large range. Our result places no res

Geert Jan van Oldenborgh, Gerrit Burgers, Albert Klein Tank

In a statistical analysis of more than a century of data we find a strong connection between strong warm El Nino winter events and high spring precipitation in a band from Southern England eastwards into Asia. This relationship is an extension of the connection mentioned by Kiladis and Diaz (1989), and much stronger than the winter season teleconnection that

C. Schwarz, M. Campbell, R. Goeppert, E. H. M. Heijne

The performance of hybrid GaAs pixel detectors as X-ray imaging sensors were investigated at room temperature. These hybrids consist of 300 mu-m thick GaAs pixel detectors, flip-chip bonded to a CMOS Single Photon Counting Chip (PCC). This chip consists of a matrix of 64 x 64 identical square pixels (170 mu-m x 170 mu-m) and covers a total area of 1.2 cm**2.

P. Navratil, B. R. Barrett

We use equations for Faddeev amplitudes to solve the shell-model problem for four nucleons in the model space that includes up to 14 hbar Omega harmonic-oscillator excitations above the unperturbed ground state. Two- and three-body effective interactions derived from the Reid93 and Argonne V8' nucleon-nucleon potentials are used in the calculations. Bind

L. J. Abu-Raddad, J. Piekarewicz, A. J. Sarty, R. A. Rego

We study the coherent photoproduction of pseudoscalar mesons---particularly of neutral pions---placing special emphasis on the various sources that put into question earlier nonrelativistic-impulse-approximation calculations. These include: final-state interactions, relativistic effects, off-shell ambiguities, and violations to the impulse approximation. We

A. Yu. Illarionov, G. I. Lykasov

A detailed analysis of processes of the type NN -> dπis presented taking into account the exchange graphs of a nucleon and a pion. A large sensitivity of polarization observables to the off-mass shell effects of nucleons inside the deuteron is shown. The influence of the inclusion of the P-wave in the deuteron wave function (DWF) is studied. We have analyzed

R. Dutta

We investigate the effect of neutrino trapping on kaon condensation process and Equation of State (EOS) in a newly formed neutron star which is less than several seconds old. Using nonlinear relativistic mean field model, we find that the presence of neutrino shifts the threshold for kaon condensation and muon production to much higher density. We also studi

C. A. Bertulani, D. T. de Paula, V. G. Zelevinsky

We study the bremsstrahlung radiation of a tunneling charged particle in a time-dependent picture. In particular, we treat the case of bremsstrahlung during alpha-decay, which has been suggested as a promissing tool to investigate the problem of tunneling times. We show deviations of the numerical results from the semiclassical estimates. A standard assumpti

M. Hannawald, T. Kautzsch, A. Woehr, W. B. Walters

The use of chemically selective laser ionization combined with beta-delayed neutron counting at CERN/ISOLDE has permitted identification and half-life measurements for 623-ms Mn-61 up through 14-ms Mn-69. The measured half-lives are found to be significantly longer near N=40 than the values calculated with a QRPA shell model using ground-state deformations f

Daniel Henry Gottlieb

Fields of Lorentz transformations on a space--time are related to tangent bundle self isometries. In other words, a gauge transformation with respect to the Minkowski metric on each fibre. Any such isometry can be expressed, at least locally, as the exponential $e^F$ where $F$ is antisymmetric with respect to the metric. We find there is a homotopy obstructi

Simon Scott

It is shown that the determinant line bundle associated to a family of Dirac operators over a closed partitioned manifold has a canonical Hermitian metric with compatible connection whose curvature satisfies an additivity formula with contributions from the families of Dirac operators over the two halves. This curvature form is the natural differential repre

Yossi Lonke

Let $f(j,k,n)$ denote the expected number of $j$-faces of a random $k$-section of the $n$-cube. A formula for $f(0,k,n)$ is presented, and for $j\geq 1$, a lower bound for $f(j,k,n)$ is derived, which implies a precise asymptotic formula for $f(n-m,n-l,n)$ when $1\leq l<m$ are fixed integers and $n\to\8$.

Michael Farber, Andrew Ranicki

We use noncommutative localization to construct a chain complex which counts the critical points of a circle-valued Morse function on a manifold, generalizing the Novikov complex. As a consequence we obtain new topological lower bounds on the minimum number of critical points of a circle-valued Morse function within a homotopy class, generalizing the Novikov

Joseph Krasil&#39;shchik, Alexander Verbovetsky

These lecture notes are a systematic and self-contained exposition of the cohomological theories naturally related to partial differential equations: the Vinogradov C-spectral sequence and the C-cohomology, including the formulation in terms of the horizontal (characteristic) cohomology. Applications to computing invariants of differential equations are disc

Thomas Heinzl

We review the foundations as well as a number of important applications of light-cone dynamics. Topics covered are: relativistic particle dynamics, reparametrization invariance, Dirac&#39;s front form, light-cone quantization of fields via Schwinger&#39;s quantum action principle or Faddeev-Jackiw reduction, light-cone vacuum and wave functions, zero modes a

Michael Teper

We summarise what lattice simulations have to say about the physical properties of continuum SU(N) gauge theories in 3+1 dimensions. The quantities covered are: the glueball mass spectrum, the confining string tension, the temperature at which the theory becomes deconfined, the topological susceptibility, the value of the scale Lambda{MS-bar} that governs th

M. Mintchev, E. Ragoucy, P. Sorba, Ph. Zaugg

We show an algebra morphism between Yangians and some finite W-algebras. This correspondence is nicely illustrated in the framework of the Non Linear Schrodinger hierarchy. For such a purpose, we give an explicit realization of the Yangian generators in terms of deformed oscillators.

H. Itoyama, A. Tsuchiya

We derive the Schwinger-Dyson/loop equations for the USp(2k) matrix model which close among the closed and open Wilson loop variables. These loop equations exhibit a complete set of the joining and splitting interactions required for the nonorientable Type I superstrings. The open loops realize the SO(2n_f) Chan-Paton factor and their linearized loop equatio

L. Mankiewicz, G. Piller, A. Radyushkin

We investigate the exclusive electroproduction of pi^+ mesons from nucleons. To leading twist, leading order alpha_s accuracy the corresponding production amplitude can be decomposed into pseudovector and pseudoscalar parts. Both can be expressed in terms of quark double distribution functions of the nucleon. While the pseudovector contribution is connected

Sheldon L. Glashow

This report, adapted from my talk at the 1998 Ettore Majorana Subnuclear School at Erice, proffers speculative explanations of the strong CP problem and the existence of cosmic rays beyond the GZK bound. It is based on works done with Sidney Coleman and Howard Georgi.

J. G. Koerner, A. A. Pivovarov, K. Schilcher

We present a discussion on how to define the running electromagnetic coupling constant at $M_Z$ or some other intermediate scale as e.g. $m_Υ$. We argue that a natural definition consistent with general requirements of the renormalization group should be based on Euclidean values of the momentum of the photon propagator as the appropriate scale. We demonstra

L. Pasquali, M. H. Reno, I. Sarcevic

Using next-to-leading order perturbative QCD, we find that the charm contribution to the atmospheric lepton fluxes dominates over the conventional ones from pi and K decays for energies higher than 10^5 GeV. We also discuss theoretical uncertainties involved in the calculations and compare our results with previous evaluations.

N. N. Nikolaev, V. R. Zoller

The running BFKL equation gives rise to a series of moving poles in the complex j-plane. Corresponding eigenfunctions (color dipole cross sections) are the oscillating functions of the color dipole size $r$. The first nodes for all sub-leading solutions (color dipole cross sections) accumulate at $r_1\sim 0.1 fm$. Therefore the processes dominated by the dip

Emanuel Norrbin

I present the main aspects of open charm production in $π^-\p$ collisions in the context of the Lund String Fragmentation Model as implemented in the Monte Carlo program PYTHIA. The emphasis is on the transition from large to small strings and the dependence on model parameters. A modified version is presented and compared with experimental results both on a

M. B. Gay Ducati, V. P. Goncalves

The description of the dynamics at high density parton regime is one of the main open questions of the strong interactions theory. In this paper we address the shadowing corrections (SC) in the scaling violations of the $F_2$ structure function using the eikonal approach. We propose a procedure to estimate the distinct contributions to the SC for $F_2$ and i

R. Fiore, L. L. Jenkovszky, F. Paccanoni

Exclusive diffractive photoproduction of heavy vector mesons (V=phi, J/psi and Upsilon) at HERA is studied in a model employing a dipole Pomeron exchange (P) with an inelastic gamma-P-V vertex. The model is fitted to the data on dsigma/dt, B and elastic sigma for Q^2=0 and beyond the threshold region. The elastic cross sections for both phi and J/psi photopr

A. Bialas

Introductory talk at the Session on Correlations and Fluctuations of the XXVII International Symposium on Multiparticle Dynamics held in Delphi, Greece, from 6th till 11th of September 1998.

Gabriela Miu, Torbjorn Sjostrand

In the description of the production properties of gauge bosons (W+/W-, Z0, gamma) at colliders, the lowest-order graph normally is not sufficient. The contributions of higher orders can be introduced either by an explicit order-by-order matrix-element calculation, by a resummation procedure or by a parton-shower algorithm. Each approach has its advantages a

R. Fiore, L. L. Jenkovszky, F. Paccanoni

Hadron diffraction dissociation is considered in the dipole Pomeron model where the Pomeron is represented by a double pole in the J-plane. We find that unitarity is satisfied without decoupling of the triple Pomeron vertex. The reaction bar{p}+p --> bar{p}+X is analysed.

B. Tseng

Using the next-to-leading order QCD-corrected effective Hamiltonian, charmless exclusive nonleptonic decays of the $B_s$ meson into $η$ or $η&#39;$ are calculated within the generalized factorization approach. Nonfactorizable contributions are included with two different treatments. Some subtleties involved are discussed.

O. Borisenko, P. Skala

We consider the 2D SU(N) principal chiral model and discuss a vortex condensation mechanism which could explain the existence of a non-zero mass gap at arbitrarily small values of the coupling constant. The mechanism is an analogue of the vortex condensation mechanism of confinement in 4D non-Abelian gauge theories. We formulate a sufficient condition for th

S. Bethke

Recent results on jet physics and tests of QCD from hadronic final states in $e^+e^-$ annihilation at PETRA and at LEP are reviewed, with special emphasis on hadronic event shapes, charged particle production rates, properties of quark and gluon jets and determinations of $α_s$. The data in the entire energy range from PETRA to LEP-2 are in broad agreement w

Nathan F. Lepora

We show that significant anisotropy in electromagnetic propagation generates a distinctive signature in the microwave background. The anisotropy may be determined by looking at the cross correlator of the $E$-mode and $B$-mode polarisation spectrum.

J. Makela, P. Repo

We consider a possibility that the entropy of a Schwarzschild black hole has two different interpretations: The black hole entropy can be understood either as an outcome of a huge degeneracy in the mass eigenstates of the hole, or as a consequence of the fact that the interior region of black hole spacetime is separated from the exterior region by a horizon.

S. N. Vergeles

An anomaly-free quantum theory of a relativistic string is constructed in two-dimensional space-time. The states of the string are found to be similar to the states of a massless chiral quantum particle. This result is obtained by generalizing the concept of an ``operator&#39;&#39; in quantum field theory.

S. N. Vergeles

On the basis of dynamic quantization method we build in this paper a new mathematically correct quantization scheme of gravity. In the frame of this scheme we develop a canonical formalism in tetrad-connection variables in 4-D theory of pure gravity. In this formalism the regularized quantized fields corresponding to the classical tetrad and connection field

J. Hashida, S. Mukaigawa, T. Muta, K. Ohkura

Chiral phase transitions driven by space-time curvature effects are investigated in de Sitter space in the supersymmetric Nambu-Jona-Lasinio model with soft supersymmetry breaking. The model is considered to be suitable for the analysis of possible phase transitions in inflationary universe. It is found that a restoration of the broken chiral symmetry takes

Patrick R Brady, Mike J Cai

This article reviews classical and quantum aspects of critical phenomena in gravitational collapse. We pay special attention to the origin of the scaling law for black hole mass, and to phase transitions in which black hole formation turns on at finite mass. We present some new results for perfect fluids with pressure proportional to density.

Jorge Kurchan

Recent analytical developments in glass theory are equally relevant to the understanding of anomalous rheology, with characteristic features such as the Reynolds dilatancy and the driving-power dependence of the viscosity arising naturally. A notion of effective temperature based on the fluctuation-dissipation relation can be introduced in the limit of small