January 2000 arXiv papers — page 12

A. V. Gulov, V. V. Skalozub

The method of searching for signals of heavy virtual particles is developed. It is based on a renormalization group equation for the low energy effective Lagrangian and the decoupling theorem. As an application, the model independent search for Abelian Z' boson in four-fermion processes is analyzed. The basic one-loop renormalization group relation for t

N. H. Fuchs, M. Knecht, J. Stern

The form factors for the $K_{\ell 3}$ semileptonic decay are computed to order $O(p^4)$ in generalized chiral perturbation theory. The main difference with the standard $O(p^4)$ expressions consists in contributions quadratic in quark masses, which are described by a single divergence-free low-energy constant, $A_3$. A new simultaneous analysis is presented

Gary R. Goldstein

A hybrid model is presented for hyperon polarization that is based on perturbative QCD subprocesses and the recombination of polarized quarks with scalar diquarks. The updated hybrid model is applied to $p+p\to Λ+X$ and successfully reproduces the detailed kinematic dependence shown by the data. The hybrid model is extended to include pion beams and polarize

Ernest Ma

There are two basic theoretical approaches to obtaining neutrino mass and mixing. In the minimalist approach, one adds just enough new stuff to the Minimal Standard Model to get $m_ν\neq 0$ and $U_{αi} \neq 1$. In the holistic approach, one uses a general framework or principle to enlarge the Minimal Standard Model such that, among other things, $m_ν\neq 0$

F. Ferrer, J. A. Grifols

We explore the consequences of Bose-Einstein condensation on two-scalar-exchange mediated forces among bodies that sit in a boson gas. We find that below the condensation temperature the range of the forces becomes infinite while it is finite at temperatures above condensation.

M. R. Pennington

Ask a group of particle theorists about low energy hadron physics and they will say that this is a subject that belongs to the age of the dinosaurs. However, it is GeV physics that controls the outcome of every hadronic interaction at almost every energy. Confinement of quarks and gluons (and any other super-constituents) means that it is the femto-universe

L. Perivolaropoulos

It is shown that textures in 3+1 dimensions can be stabilized by partial gauging (semilocality) of the vacuum manifold such that topological unwinding by a gauge transformation is not possible. This introduction of gauge fields can be used to evade Derrick's theorem without higher powers of derivatives and prevent the usual collapse of textures by the ef

J. Kwiecinski, L. Motyka, A. De Roeck

We briefly present the motivation for studying the processes mediated by the QCD pomeron at high energy e+e- colliders. We describe the behaviour of the cross-section for the reaction gamma gamma to J/psi J/psi obtained from the BFKL equation with dominant non-leading corrections. We give the predictions for the rates of anti-tagged e+e- to e+e- J/psi J/psi

C. Destri, E. Manfredini

The $λϕ^4$ model in a finite volume is studied within a non-gaussian Hartree-Fock approximation (tdHF) both at equilibrium and out of equilibrium, with particular attention to the structure of the ground state and of certain dynamical features in the broken symmetry phase. The mean-field coupled time-dependent Schroedinger equations for the modes of the scal

C. Destri, E. Manfredini

The $λϕ^4$ model in a finite volume is studied in the infinite $N$ limit both at equilibrium and out of equilibrium, with particular attention to certain fundamental features of the broken symmetry phase. The numerical solution of the dynamical evolution equations shows that the zero-mode quantum fluctuations cannot grow macroscopically large starting from m

Liu zhixiu, Fu Jinghua, Liu Lianshou

The influence of multiplicity distribution (fluctuation of multiplicity in the event space) on the erraticity behaviour in high energy collisions is investigated via Monte Carlo simulation and compared with the experimental results from NA27 data. It is shown that, the erraticity phenomenon is insensitive to the multiplicity fluctuation. When the average mul

S. Y. Choi, M. Guchait, J. Kalinowski, P. M. Zerwas

The chargino $\tildeχ^\pm_{1,2}$ system can be reconstructed completely in $e^+e^-$ collisions. By measuring the total cross sections and the asymmetries with polarized beams in $e^+e^-\to\tildeχ_i^+ \tildeχ_j^- [i,j=1,2]$, the chargino masses and the gaugino-higgsino mixing angles of these states can be determined very accurately. If only the lightest charg

Alexander Kusenko

Supersymmetric extensions of the Standard Model predict the existence of Q-balls, some of which can be entirely stable. Both stable and unstable Q-balls can play an important role in cosmology. In particular, Affleck-Dine baryogenesis can result in a copious production of stable baryonic Q-balls, which can presently exist as a form of dark matter. Formation

E. Blucher

The first measurement of epsilon-prime / epsilon from the KTeV experiment at Fermilab is described.

Junichi Iwasaki

A surface theoretic view of non-perturbative quantum gravity as "spin-foams" was proposed by Baez. A possibility of constructing such a model was studied some time ago based on (2+1) dimensional general relativity as a reformulation of the Ponzano-Regge model in Riemannian spacetime. In the present work, a model based on (3+1) dimensional general rel

Lillian Lee

We study distributional similarity measures for the purpose of improving probability estimation for unseen cooccurrences. Our contributions are three-fold: an empirical comparison of a broad range of measures; a classification of similarity functions based on the information that they incorporate; and the introduction of a novel function that is superior at

Tetsuo Deguchi, Klaus Fabricius, Barry M. McCoy

We demonstrate that the six vertex model (XXZ spin chain) with $Δ=(q+q^{-1})/2$ and $q^{2N}=1$ has an invariance under the loop algebra of $sl_2$ which produces a special set of degenerate eigenvalues. For $Δ=0$ we compute the multiplicity of the degeneracies using Jordan Wigner techniques

Jyotipratim Ray Chaudhuri, Suman Kumar Banik, Deb Shankar Ray

We consider a system-reservoir model where the reservoir is modulated by an external noise. Both the internal noise of the reservoir and the external noise are stationary, Gaussian and are characterized by arbitrary decaying correlation functions. Based on a relation between the dissipation of the system and the response function of the reservoir driven by e

M. Raberto, G. Cuniberti, E. Scalas, M. Riani

We present a neural-network valuation of financial derivatives in the case of fat-tailed underlying asset returns. A two-layer perceptron is trained on simulated prices taking into account the well-known effect of volatility smile. The prices of the underlier are generated using fractional calculus algorithms, and option prices are computed by means of the B

S. Tarucha, D. G. Austing, Y. Tokura, W. G. van der Wiel

We determine the contributions from the direct Coulomb and exchange interactions to the total interaction in semiconductor artificial atoms. We tune the relative strengths of the two interactions and measure them as a function of the number of confined electrons. We find that electrons tend to have parallel spins when they occupy nearly degenerate single-par

Pengcheng Dai, H. A. Mook, S. M. Hayden, G. Aeppli

Inelastic neutron scattering was used to study the wavevector- and frequency-dependent magnetic fluctuations in single crystals of superconducting YBa$_2$Cu$_3$O$_{6+x}$. The spectra contain several important features, including a gap in the superconducting state, a pseudogap in the normal state and the much-discussed resonance peak. The appearance of the ps

Leonid B. Litinskii

An artificial neural network is usually treated as a whole system, being characterized by its ground state (the global minimum of the energy functional), the set of fixed points, their basins of attraction, etc. However, it is quite natural to suppose that a large network may consist of a set of almost autonome subnets. Each subnet works independently (or al

M. Capone, D. Feinberg, M. Grilli

It is shown that the layered antiferromagnetic order in stoechiometric LaMnO_3 cannot be understood purely from electronic interactions. On the contrary, it mainly results from strong cooperative Jahn-Teller deformations. Those involve a compression of the Mn-O octahedron along the c-axis (mode Q_3 < 0), while alternate Jahn-Teller deformations occur in the

Arnaud Buhot

Reply to A. Louis Comment: Fluid-solid phase-separation in hard-sphere mixtures is unrelated to bond-percolation

A. A. Louis

In a recent letter, Buhot proposes that entropy driven phase-separation in hard-core binary mixtures is directly related to a bond-percolation transition. However, at least for binary hard-sphere mixtures, calculations based on an accurate approximation to g_{ll}(r) demonstrate that n_b varies widely along the phase-boundaries calculated directly by simulati

Yasutami Takada, Manabu Kido

We study the effect of correlation on the Bragg reflection in the 3D electron gas, the 1D Luttinger liquid, and the 1D Hubbard model in an alternating periodic potential at half-filling. In the last system, we suggest a Luttinger-liquid-type quasi-metallic state in the crossover region from the band insulator to the Mott insulator. We explain the appearance

Yoshio Kuramoto, Hiroaki Kusunose

Possibility of a novel pseudo-scalar (octupole) order is studied theoretically for orbitally degenerate systems with strong spin-orbit coupling such as Ce$_x$La$_{1-x}$B$_6$. It is discussed that coexistence of an octupole order parameter and antiferromagnetic fluctuation should lead to drastic softening of the elastic constant by a mode-mixing effect. Nonli

Anirban Chakraborti, Bibhas Bhattacharyya, Arunava Chakrabarti

We present an analytical method of studying &#34;extended&#34; electronic eigenstates of a diamond hierarchical lattice, which may be taken as the simplest of the hierarchical models recently proposed for stretched polymers. We use intuitive arguments and a renormalization-group method to determine the distribution of amplitudes of the wave functions corresp

Stefan Wessel, Stephan Haas

The spectral and thermodynamic response of segmented quantum spin chains is analyzed using a combination of numerical techniques and finite-size scaling arguments. Various distributions of segment lengths are considered, including the two extreme cases of quenched and annealed averages. As the impurity concentration is increased, it is found that (i) the int

G. Soucail, N. Ota, H. Bohringer, O. Czoske

We present a detailed analysis of the mass distribution in the rich and distant cluster of galaxies Cl0024+17. X-ray data come from both a deep ROSAT/HRI image of the field (Bohringer et al. 1999) and ASCA spectral data. Using a wide field CCD image of the cluster, we optically identify all the faint X-ray sources, whose counts are compatible with deep X-ray

Silvia Alencar, Gibor Basri

We present a spectral analysis of 30 T Tauri stars observed with the Hamilton echelle spectrograph over more than a decade. One goal is to test magnetospheric accretion model predictions. Observational evidence previously published supporting the model, such as emission line asymmetry and a high frequency of redshifted absorption components, are considered.

Masatoshi Imanishi, Shiro Ueno

We report the detection of a 9.7 $μ$m silicate dust absorption feature toward the Cygnus A nucleus. Its optical depth is, however, significantly smaller than that expected from the dust extinction toward the background $L$-band emission region ($A_{\rm V}$ $\sim$ 150 mag). We argue that the most likely explanation for the small optical depth is that the obsc

Harald Ebeling, Alastair Edge, J. Patrick Henry

We present first results from the MAssive Cluster Survey (MACS), a new large-scale X-ray survey designed to find and characterize very massive, distant clusters of galaxies. Based on X-ray detections in the ROSAT All-Sky Survey, MACS aims to compile a sample of more than 200 X-ray luminous clusters at z>0.3, about 50 times the number of EMSS clusters in the

Harald Ebeling, Christopher Mullis, Brent Tully

We discuss the design and current status of the CIZA survey, the first systematic X-ray search for clusters of galaxies in the Galactic plane region. So far, we have compiled a sample of more than 70 X-ray selected clusters at |b|<20 deg, 80% of which were previously unknown. Upon its completion the CIZA cluster catalogue will complement the existing galaxy

David Tytler, John M. O&#39;Meara, Nao Suzuki, Dan Lubin

Big Bang Nucleosynthesis (BBN) is the synthesis of the light nuclei, Deuterium, He3, He4 and Li7, during the first few minutes of the universe. This review concentrates on recent improvements in the measurement of the primordial (after BBN, and prior to modification) abundances of these nuclei. We mention improvement in the standard theory, and the non-stand

Leonid M. Ozernoy, Nick N. Gorkavyi, Tanya Taidakova

Using numerical simulations, we examine the structure of a cometary population near a massive planet, such as a giant planet of the Solar system, starting with one-planet approximation (the Sun plus one planet). By studying the distributions of comets in semimajor axis, eccentricity, pericenter, and apocenter distances, we have revealed several interesting f

N. Prantzos, S. Boissier

Assuming that damped Lyman-alpha(DLA) systems are galactic discs, we calculate the corresponding evolution of metal abundances. We use detailed multi-zone models of galactic chemical evolution (reproducing successfully the observed properties of disc galaxies) and appropriate statistics (including geometrical propability factors) to calculate the average met

Alvio Renzini

Clusters of galaxies allow a direct estimate of the metallicity and metal production yield on the largest scale so far. The ratio of the total iron mass in the ICM to the total optical luminosity of the cluster (the iron mass-to-light-ratio) is the same for all clusters which ICM is hotter than $\sim 2$ keV, and the elemental proportions (i.e. the [$α$/Fe] r

Alvio Renzini

There is now ample evidence that most - perhaps all - galactic spheroids host a supermassive BH at their center. This has been assessed using a variety of observational techniques, from stellar and/or gas dynamics to megamasers. Yet another promising technique is offered by the case of the Virgo elliptical NGC 4552, in which early HST/FOC observations reveal

K. Kikuchi, C. Itoh, A. Kushino, T. Furusho

Based on mapping observations with ASCA, an unusual hot region with a spatial extent of 1 square degree was discovered between M87 and M49 at a center coordinate of R. A. = 12h 27m 36s and Dec. = $9^\circ18&#39;$ (J2000). The X-ray emission from the region has a 2-10 keV flux of $1 \times 10^{-11}$ ergs s$^{-1}$ cm$^{-2}$ and a temperature of $kT \gtrsim 4$

D. Clowe, N. Trentham, J. Tonry

We investigate the possible existence of a high-redshift (z=1) cluster of galaxies associated with the QSO lens system MG2016+112. From an ultra-deep R- and less deep V- and I-band Keck images and a K-band mosaic from UKIRT, we detect ten galaxies with colors consistent with the lensing galaxy within 225h^{-1} kpc of the z=1.01 lensing galaxy. This represent

Jishnu Dey, Subharthi Ray, Xiang-Dong Li, Mira Dey

There are about 2000 gamma ray burst (GRB) events known to us with data pouring in at the rate of one per day. While the afterglows of GRBs in radio, optical and X-ray bands are successfully explained by the fireball model, a significant difficulty with the proposed mechanisms for GRBs is that a small amount ($\le 10^{-6} M_{\odot}$) of baryons in the ejecta

Raymond E. White, Renato A. Dupke

Analysis of spatially resolved ASCA spectra of the intracluster gas in Abell 496 confirms that metal abundances increase toward the center. We also find spatial gradients in several abundance ratios, indicating that the fraction of iron from SN Ia increases toward the cluster center. The dominant metal enrichment mechanism near the cluster center must theref

Wayne Hu

Weak lensing of CMB anisotropies and polarization for the power spectra and higher order statistics can be handled directly in harmonic-space without recourse to real-space correlation functions. For the power spectra, this approach not only simplifies the calculations but is also readily generalized from the usual flat-sky approximation to the exact all-sky

Bruce A. Campbell, Kirk Kaminsky

The role of the (dynamical) dilaton in the vortices associated with the spontaneous breaking of an anomalous U(1) from heterotic string theory is examined. We demonstrate how the anomaly (and the coupling to the dilaton/axion) can appear in the Lagrangian and associated field equations as a controlled perturbation about the standard Nielsen-Olesen equations.

Nick Dorey, S. Prem Kumar

We calculate the exact values of the holomorphic observables of {\cal N}=4 supersymmetric SU(N) Yang-Mills theory deformed by mass terms which preserve {\cal N}=1 SUSY. These include the chiral condensates in each massive vacuum of the theory as well as the central charge which determines the tension of BPS saturated domain walls interpolating between these

J. B. Kogut, M. A. Stephanov, D. Toublan, J. J. M. Verbaarschot

We study QCD-like theories with pseudoreal fermions at finite baryon density. Such theories include two-color QCD with quarks in the fundamental representation of the color group as well as any-color QCD with quarks in the adjoint color representation. In all such theories the lightest baryons are diquarks. At zero chemical potential $μ$ they are, together w

Peter. W. Gorham

We revisit and extend the analysis supporting a 60 year-old suggestion that cosmic rays air showers resulting from primary particles with energies above 10^{18} eV should be straightforward to detect with radar ranging techniques, where the radar echoes are produced by scattering from the column of ionized air produced by the shower. The idea has remained cu

Daniel M. Kaplan

During the 1990s an international collaboration has been studying the possibility of constructing and operating a high-energy high-luminosity $μ^+μ^-$ collider. Such a machine could be the approach of choice to extend our discovery reach beyond that of the LHC. More recently, a growing collaboration is exploring the potential of a stored-muon-beam &#34;neutr

Schuyler Cullen, Maxim Perelstein, Michael E. Peskin

Arkani-Hamed, Dimopoulos, and Dvali have proposed that the fundamental gravitational scale is close to 1 TeV, and that the observed weakness of gravity at long distances is explained by the presence of large extra compact dimensions. If this scenario is realized in a string theory of quantum gravity, the string excited states of Standard Model particles will

The JLAB t20 collaboration, D. Abbott

Tensor polarization observables (t20, t21 and t22) have been measured in elastic electron-deuteron scattering for six values of momentum transfer between 0.66 and 1.7 (GeV/c)^2. The experiment was performed at the Jefferson Laboratory in Hall C using the electron HMS Spectrometer, a specially designed deuteron magnetic channel and the recoil deuteron polarim

D. Belitz, T. R. Kirkpatrick

It is shown that the Anderson-Mott metal-insulator transition of paramagnetic, interacting disordered electrons in an external magnetic field is in the same universality class as the transition from a ferromagnetic metal to a ferromagnetic insulator discussed recently. As a consequence, large corrections to scaling exist in the magnetic-field universality cl

W. Klein, Harvey Gould, J. Tobochnik, F. J. Alexander

We show that the structure of the fluctuations close to spinodals and mean-field critical points is qualitatively different than the structure close to non-mean-field critical points. This difference has important implications for many areas including the formation of glasses in supercooled liquids. In particular, the divergence of the measured static struct

Ralf Meyer

Let G be a locally compact group. We describe elements of KK^G (A,B) by equivariant homomorphisms, following Cuntz&#39;s treatment in the non-equivariant case. This yields another proof for the universal property of KK^G: It is the universal split exact stable homotopy functor. To describe a Kasparov triple (E, phi, F) by an equivariant homomorphism, we have

Stanislaw Mrowczynski, Markus H. Thoma

Anisotropic systems of quarks and gluons, which at least for sufficiently short space-time intervals can be treated as homogeneous and static, are considered. The gluon polarization tensor of such a system is explicitly computed within the semiclassical kinetic and Hard Loop diagrammatic theories. The equivalence of the two approaches is demonstrated. The qu

V. Berezinsky

The current status of origin of Ultra High Energy Cosmic Rays (UHECR) is reviewed, with emphasis given to elementary particle solutions to UHECR problem, namely to Topological Defects and Super-Heavy Dark Matter (SHDM) particles. The relic superheavy particles are very efficiently produced at inflation. Being protected by gauge discrete symmetries, they can

V. Gogohia, Gy. Kluge

Using the effective potential approach for composite operators, we have formulated a general method how to calculate the truly nonperturbative vacuum energy density in the axial gauge QCD quantum models of its ground state. It is defined as integrated out the truly nonperturbative part of the full gluon propagator over the deep infrared region (soft momentum

M. Kachelriess

The KARMEN experiment observes a time anomaly in events induced by pion decay at rest. This anomaly can be ascribed to the production of a new weakly interacting particle X with mass m_X\sim 34 MeV. We show that a recently proposed identification of the X particle with the lightest neutralino χin the frame work of the MSSM with broken R parity is in contradi

B. Badelek, M. Krawczyk, J. Kwiecinski, A. M. Stasto

A parametrisation of the real photon structure function F_2^gamma in the low Q^2, low x region is formulated. It includes both the VMD and the QCD components, the latter suitably extrapolated to the low Q^2 region and based on arbitrary parton distributions in the photon. The parametrisation used together with the GRV and GRS&#39; parton densities describes

Sankalpa Ghosh, R. Rajaraman

In this paper we study in detail different types of topological solitons which are possible in bilayer quantum Hall systems at filling fraction $ν=1$ when spin degrees of freedom are included. Starting from a microscopic Hamiltonian we derive an effective energy functional for studying such excitations. The gauge invariance and $CP^{3}$ character of this ene

P. P. Avelino, C. J. A. P. Martins, G. Rocha

We discuss constraints on so-called `varying speed of light theories&#39; coming from the physics of the early universe. Specifically, we consider the position of the first acoustic peak of the CMB angular power spectrum, showing that the recent determination of its position by various CMB experiments, in particular BOOMERanG/NA, can be used to constrain the

F. E. Close, A. Kirk, G. Schuler

We explain the phi and t dependences of mesons with JPC = 0-+, 0++,1++, 2-+ and 2++ produced in the central region of pp collisions. For the 0++ and 2++ sector this reveals a systematic behaviour in the data that appears to distinguish between qqbar and non-qqbar or glueball candidates.

Pushpalatha C. Bhat, Russell Gilmartin, Harrison B. Prosper

We have studied the potential of the CDF and DZero experiments to discover a low-mass Standard Model Higgs boson, during Run II, via the processes $p\bar{p}$ -> WH -> $\ellνb\bar{b}$, $p\bar{p}$ -> ZH -> $\ell^{+}\ell^{-}b\bar{b}$ and $p\bar{p}$ -> ZH ->$ν\barν b\bar{b}$. We show that a multivariate analysis using neural networks, that exploits all the infor

Frederic D. R. Bonnet, Patrick Fitzhenry, Derek B. Leinweber, Mark R. Stanford

The action and topological charge are used to determine the relative rates of standard cooling and smearing algorithms in pure SU(3)-color gauge theory. We consider representative gauge field configurations on $16^3\times 32$ lattices at $\beta=5.70$ and $24^3\times 36$ lattices at $\beta=6.00$. We find the relative rate of variation in the action and topolo

C. S. Kim, Yeong Gyun Kim, Cai-Dian Lu, Takuya Morozumi

We present the angular distribution of the rare B decay, $B \to K^* (\to K π) \ell^+ \ell^-$. By studying the azimuthal angle distribution in the low invariant mass region of dileptons, we can probe new physics effects efficiently. In particular, this distribution is found to be quite sensitive to the ratio of the contributions from two independent magnetic

H. N. Núñez-Yépez, E. Guillaumín-España, R. P. Martínez-y-Romero, A. L. Salas-Brito

The momentum representation is seldom used in quantum mechanics courses. Some students are thence surprised by the change in viewpoint when, in doing advanced work, they have to use the momentum rather than the coordinate representation. In this work, we give an introduction to quantum mechanics in momentum space, where the Schrödinger equation becomes an in

F. D. R. Bonnet, Derek B. Leinweber, Anthony G. Williams

Quantum field theories underlie all of our understanding of the fundamental forces of nature. The are relatively few first principles approaches to the study of quantum field theories [such as quantum chromodynamics (QCD) relevant to the strong interaction] away from the perturbative (i.e., weak-coupling) regime. Currently the most common method is the use o

W. A. Hofer

The fundamental equations of particle motion lead to a modified Poisson equation including dynamic charge. This charge derives from density oscillations of a particle; it is not discrete, but continuous. Within the dynamic model of hydrogen it accounts for all features of electron proton interactions, its origin are density oscillations of the proton. We pro

Leonid Ya. Kobelev

A theory of time and space with fractional dimensions (FD) of time and space ($d_α, α=t,{\bf r})$ defined on multifractal sets is proposed. The FD is determined (using principle of minimum the functionals of FD) by the energy densities of Lagrangians of known physical fields. To describe behaviour of functions defined on multifractal sets the generalizations

Alexander Volya, Vladimir Zelevinsky

This paper has been withdrawn by the authors

Al. H. Raduta, Ad. R. Raduta

A modified version is in preparation.

Al. H. Raduta, Ad. R. Raduta

The sharp microcanonical multifragmentation model from [Al. H. Raduta and Ad. R. Raduta, Phys. Rev. C 55, 1344 (1997); Phys. Rev. C, in press] is employed for evaluating the nuclear caloric curve predictions of nine isotopic thermometers for three representative nuclei. Evaluations are performed for both primary decay and asymptotic stages. Effects of the se

Stephen P. Weppner, Charlotte Elster, Ofir Garcia

We investigate the use of proton-nucleus elastic scattering experiments using secondary beams of 6He and 8He to determine the physical structure of these nuclei. The sensitivity of these experiments to nuclear structure is examined by using four different nuclear structure models with different spatial features using a full-folding optical potential model. T

C. Chandre, R. S. MacKay

We construct an approximate renormalization transformation for Hamiltonian systems with three degrees of freedom in order to study the break-up of invariant tori with three incommensurate frequencies which belong to the cubic field $Q(τ)$, where $τ^3+τ^2-2τ-1=0$. This renormalization has two fixed points~: a stable one and a hyperbolic one with a codimension

L. Biferale, P. Gualtieri, F. Toschi

Some pressure and pressure-velocity correlation in a direct numerical simulations of a three-dimensional turbulent flow at moderate Reynolds numbers have been analyzed. We have identified a set of pressure-velocity correlations which posseses a good scaling behaviour. Such a class of pressure-velocity correlations are determined by looking at the energy-bala

John H. Van Drie

IIt is demonstrated that the entropy of statistical mechanics and of information theory, $S({\bf p}) = -\sum p_i \log p_i $ may be viewed as a measure of correlation. Given a probability distribution on two discrete variables, $p_{ij}$, we define the correlation-destroying transformation $C: p_{ij} \to π_{ij}$, which creates a new distribution on those same

N. Ilieva, W. Thirring

We construct a pair potential which in a scaling limit leads to a Hamiltonian that generates co-existing mean-field and superconducting phases. Depending on the relative values of the coupling constants, the superconducting phase may exist at arbitrarily high temperatures.

Eugene Karolinsky

Let $G$ be a complex reductive connected algebraic group equipped with the Sklyanin bracket. A classification of Poisson homogeneous $G$-spaces with connected isotropy subgroups is given. This result is based on Drinfeld&#39;s correspondence between Poisson homogeneous $G$-spaces and Lagrangian subalgebras in the double $D(g)$ (here $g = Lie G$). A geometric

Gerd-Eberhard Dethloff, Steven Shin-Yi Lu

We generalize Demailly&#39;s construction of projective jet bundles and strictly negatively curved pseudometrics on them to the logarithmic case. We establish this logarithmic generalization explicitly via coordinates, just as Noguchi&#39;s generalization of the jets used by Green-Griffiths. As a first application, we give a metric proof for the logarithmic

Martin Schaden

The local action of an SU(2) gauge theory in general covariant Abelian gauges and the associated equivariant BRST symmetry that guarantees the perturbative renormalizability of the model are given. I show that a global SL(2,R) symmetry of the model is spontaneously broken by ghost-antighost condensation at arbitrarily small coupling and leads to propagators

Giorgio Calucci

The possibility that a static magnetic field may decay through production of electron positron pairs is studied. The conclusion is that this decay cannot happen through production of single pairs, as in the electric case, but only through the production of a many-body state, since the mutual magnetic interactions of the created pairs play a relevant role. Th

Ron Donagi, Burt A. Ovrut, Tony Pantev, Daniel Waldram

We present a class of N=1 supersymmetric ``standard&#39;&#39; models of particle physics, derived directly from heterotic M-theory, that contain three families of chiral quarks and leptons coupled to the gauge group SU(3)_C X SU(2)_L X U(1)_Y. These models are a fundamental form of ``brane world&#39;&#39; theories, with an observable and hidden sector each c

Y. Brihaye, M. Desoil

The standard model of electroweak interactions is minimally coupled to gravity and the response of the spherically symmetric solutions -the sphaleron and the bisphaleron- to gravity is emphasized. For a given value of the Higgs mass $M_H$, several branches of solutions exist which terminate into cusp-catastrophy at some ($M_H$-depending) critical value of th

A. A. Deriglazov

Closed bosonic string with different normal ordering constants $a \ne \bar a$ for the right and the left moving sectors is considered. One immediate consequence of this choice is absence of tachyon in the physical state spectrum. Selfconsistency of the resulting model in the &#34;old covariant quantization&#34; (OCQ) framework is studyed. The model is manife

G. K. Savvidy

I emphasize analogy between Dp-branes in string theories and solitons in gauge theories comparing their common properties and showing differences. We will show that for certain excitations of the string/D3-brane system Neumann boundary conditions emerge from the Born-Infeld dynamics. The excitations which are coming down the string with a polarization along

J. Balog, M. Niedermaier, F. Niedermayer, A. Patrascioiu

The intrinsic 4-point coupling, defined in terms of a truncated 4-point function at zero momentum, provides a well-established measure for the interaction strength of a QFT. We show that this coupling can be computed non-perturbatively and to high accuracy from the form factors of an (integrable) QFT. The technique is illustrated and tested with the Ising mo

H. Salehi, Y. Bisabr, H. Ghafarnejad

The Hadamard state condition is used to analyze the local constraints on the two-point function of a quantum field conformally coupled to a background geometry. Using these constraints we develop a scalar tensor theory which controls the coupling of the stress-tensor induced by the two-point function of the quantum field to the conformal class of the backgro

H. Salehi, Y. Bisabr

We present a model in which the breackdown of conformal symmetry of a quantum stress-tensor due to the trace anomaly is related to a cosmological effect in a gravitational model. This is done by characterizing the traceless part of the quantum stress-tensor in terms of the stress-tensor of a conformal invariant classical scalar field. We introduce a conforma

Paul S. Aspinwall

These are notes based on lectures given at TASI99. We review the geometry of the moduli space of N=2 theories in four dimensions from the point of view of superstring compactification. The cases of a type IIA or type IIB string compactified on a Calabi-Yau threefold and the heterotic string compactified on K3xT2 are each considered in detail. We pay specific

M. Suzuki

I present a critical account of the final-state interaction (FSI) in two-body B decays from viewpoint of the hadron picture. I emphasize that the phase and the magnitude of decay amplitude are related to each other by a dispersion relation. In a model phase of FSI motivated by experiment, I illustrate how much the magnitude of amplitude can deviate from its

A. Djouadi, W. Kilian, M. Muhlleitner, P. M. Zerwas

To establish the Higgs mechanism {\it sui generis} experimentally, the Higgs self-interaction potential must be reconstructed. This task requires the measurement of the trilinear and quadrilinear self-couplings, as predicted in the Standard Model or in supersymmetric theories. The couplings can be probed in multiple Higgs production at high-luminosity e+e- l

D. Cormier, R. Holman

The accelerated expansion of the Universe measured by high redshift Type Ia Supernovae observations is explained using the non-equilibrium dynamics of naturally soft boson fields. Spinodal instabilities inevitably present in such systems yield a very attractive mechanism for arriving at the required equation of state at late times, while satisfying all the k

F. Cano, S. Liuti

We examine the low Bjorken $x$ gluon distribution in nuclei in the asymptotic region.

Giorgio Calucci, Marco Dazzi Giorgio Calucci, Marco Dazzi

Informations about the spatial structure of parton distribution within the hadron are provided by the ratios between the inclusive cross sections for a pair of jets, two pairs of jets, three pairs of jets..., and so on. It results, however that these ratios depend not only on the spatial distribution but also, and even more, on the multiplicity distribution

F. Buccella, O. Pisanti, L. Rosa

A large class of polarized and unpolarized deep inelastic data is successfully described with Fermi-Dirac functions for the non-diffractive part of quark parton distributions. The NLO approach used here improves the agreement with experiment of the previous LO work. We get a broader distribution for the strange parton s(x) than for sbar(x).

Guido Altarelli, Richard D. Ball, Stefano Forte

This is an extended and pedagogically oriented version of our recent work, in which we proposed an improvement of the splitting functions at small x which overcomes the apparent problems encountered by the BFKL approach.

Yu. A. Kubyshin, P. G. Tinyakov

The propagator in the instanton background in the -lambda phi^4 scalar model in four dimensions is studied. Leading and sub-leading terms of its asymptotics for large momenta and its on-shell double residue are calculated. These results are applied to the analysis of the initial state and initial-final state corrections and the calculation of the next-to-lea

M. Hirai

Polarized parton distribution functions are determined by using asymmetry A_1 data from longitudinally polarized deep inelastic scattering experiments. From our χ^2 analysis, polarized u-valence, d-valence, antiquark, and gluon distributions are obtained. We propose one set of leading-order distributions and two sets of next-to-leading-order ones as the long

T. Manke

We present non-perturbative results for the spectrum of heavy quarkonia. Using an anisotropic formulation of Lattice QCD we achieved an unprecedented control over statistical and systematic errors. We also study relativistic corrections to the leading order predictions for heavy hybrids and conventional bound states.

P. Desgrolard, M. Giffon, E. Martynov, E. Predazzi

We have investigated several models of Pomeron and Odderon contributions to high energy elastic $pp$ and $\bar p p$ scattering. The questions we address concern their role in this field, the behavior of the scattering amplitude (or of the total cross-section) at high energy, and how to fit all high energy elastic data. The data are extremely well reproduced