February 1999 arXiv papers — page 17

L. Zamick, N. Auerbach

The summed strength for transitions from the ground state of $^{12}C$ via the operators $\vec{s}t, \vec{\ell}t, rY't, r[Y's]^λt$ and $r[Y'\ell]^λt$ are calculated using the $ΔN = 0$ rotational model. If we choose the z component of the isospin operator $t_{z}$, the above operators are relevant to electromagnetic transitions; if we choose $t_{+}$

Youngman Kim, R. Rapp, G. E. Brown, Mannque Rho

A schematic two-level model consisting of a "collective" bosonic state and an "elementary" meson is constructed that provides interpolation from a hadronic description (a la Rapp/Wambach) to B/R scaling for the description of properties of vector mesons in dense medium. The development is based on a close analogy to the degenerate schematic m

Paul Norbury

We construct a large class of periodic instantons. Conjecturally we produce all periodic instantons. This confirms a conjecture of Garland and Murray that relates periodic instantons to orbits of the loop group acting on an extension of its Lie algebra.

Steven Dale Cutkosky

We give examples of nonsingular curves in projective 3 space such that the regularity of powers of their ideal sheaves are highly nonlinear. This is in constrast to the case of an ideal I in a polynomial ring, where the regularity of I^n is a linear polynomial in n for large n.

Won K. Park

We present a new proof of Pinchuk's theorem on the analytic continuation of a biholomorphic mapping from a strongly pseudoconvex analytic real hypersurface to a compact strongly pseudoconvex analytic real hypersurface in a complex euclidean space.

Won K. Park

We show a refined version of the existence and uniqueness theorem to Chern-Moser normal form. The class of nondegenerate real hypersurfaces in normal form has a natural group action. Umbilic point is defined via normal form. Nondegenerate analytic real hypersurfaces are locally biholomorphic to a real hyperquadric whenever every point is umbilic in this sens

Won K. Park

We present a proof of the existence and uniqueness theorem of a normalizing biholomorphic mapping to Chern-Moser normal form. The explicit form of the equation of a chain on a real hyperquadric is obtained. We show a family of normal forms of nondegenerate real hypersurfaces including Chern-Moser normal form.

Julien Bichon

The aim of this paper is to introduce and to investigate the analogues of torsors for compact quantum groups and to study their role in representation theory. Let A be a unitarizable Hopf *-algebra: we show that there is a category equivalence between *-fibre functors on unitary A-comodules and A-*-Galois extension endowed with a positive Haar measure.

Julien Bichon

In this paper we define and study the algebraic conterpart of sovereign monoidal categories : cosovereign Hopf algebras.

Julien Bichon

We determine the quantum automorphism groups of finite graphs. These are quantum subgroups of the quantum permutation groups defined by Wang. The quantum automorphism group is a stronger invariant for finite graphs than the usual one. We get a quantum dihedral group D4.

Andrei Tyurin

After the appearance of my preprint [T3] (Special Lagrangian geometry and slightly deformed algebraic geometry (spLag and sdAG), Warwick preprint 22/1998, alg-geom/9806006, 54 pp.). I received an e-mail from Cumrun Vafa, who recognized that the subject is closely related to that of his preprint [V] (Extending mirror conjecture to Calabi-Yau with bundles, hep

Eric D'Hoker, Daniel Z. Freedman, Samir D. Mathur, Alec Matusis

We construct the gauge field and graviton propagators in Euclidean AdS(d+1) space-time by two different methods. In the first method the gauge invariant Maxwell or linearized Ricci operator is applied directly to bitensor ansatze for the propagators which reflect their gauge structure. This leads to a rapid determination of the physical part of the propagato

J. Gegenberg, R. B. Mann

We construct a topological field theory which, on the one hand, generalizes BF theories in that there is non-trivial coupling to `topological matter fields'; and, on the other, generalizes the three-dimensional model of Carlip and Gegenberg to arbitrary dimensional manifolds. Like the three dimensional model, the theory can be considered to describe a gr

Mariano Cadoni, Salvatore Mignemi

We present a detailed discussion of the asymptotic symmetries of Anti-de Sitter space in two dimensions and their relationship with the conformal group in one dimension. We use this relationship to give a microscopical derivation of the entropy of 2d black holes that have asymptotically Anti-de Sitter behaviour. The implications of our results for the conjec

B. P. Kosyakov

This paper discusses in a systematical way exact retarded solutions to the classical SU(N) Yang-Mills equations with the source composed of several colored point particles. A new method of finding such solutions is reviewed. Relying on features of the solutions, a toy model of quark binding is suggested. According to this model, quarks forming a hadron are i

Federico Berruto

In this thesis, I use the strong coupling expansion to investigate the multiflavor lattice Schwinger models in the hamiltonian formalism using staggered fermions. In particular, I am interested in analysing the mapping of these gauge theories onto quantum spin-1/2 antiferromagnetic Heisenberg chains. Exploting this mapping, the chiral symmetry breaking patte

J. M. Evans, M. Hassan, N. J. MacKay, A. J. Mountain

We report on investigations of local (and non-local) charges in bosonic and supersymmetric principal chiral models in 1+1 dimensions. In the bosonic PCM there is a classically conserved local charge for each symmetric invariant tensor of the underlying group. These all commute with the non-local Yangian charges. The algebra of the local charges amongst thems

F. E. Close, G. A. Schuler

We demonstrate that the azimuthal dependence of central meson production in hadronic collisions, when suitably binned, provides unambiguous tests of whether the Pomeron couples like a conserved vector-current to protons. We discuss the possibility of discriminating between q-qbar and glueball production in such processes. Our predictions apply also to meson

Sandro Ambrosanio, James D. Wells

One way to suppress flavor changing neutral currents or CP violating processes in supersymmetry is to make at least some of the first two generations' scalars superheavy (above ~20 TeV). We summarize the motivations and challenges, theoretically and phenomenologically, for superheavy supersymmetry. We then argue for more viable alternatives on the superh

Alekhin Sergey

We performed NLO QCD fit of combined SLAC/BCDMS/NMC DIS data at high $x$. Model independent x-shape of high twist contribution to structure function $F_L$ is extracted. Twist-4 contribution is found to be in fair agreement with the predictions of infrared renormalon model. Twist-6 contribution exhibits weak tendency to negative values, although in the whole

S. Fujimoto, S. Kato, M. Murata, T. Suzuki

We study the perfect lattice actions of abelian-projected SU(2) gluodynamics. Using the BKT and duality transformations on the lattice, an effective string model is derived from the direction-dependent quadratic monopole action, obtained numerically from SU(2) gluodynamics in maximally abelian gauge. The string tension and the restoration of continuum rotati

John C. Baez

This is a nontechnical introduction to recent work on quantum gravity using ideas from higher-dimensional algebra. We argue that reconciling general relativity with the Standard Model requires a `background-free quantum theory with local degrees of freedom propagating causally'. We describe the insights provided by work on topological quantum field theor

László Á. Gergely

We study the two-dimensional (2D) dilatonic model describing a massless scalar field minimally coupled to the spherically reduced Einstein-Hilbert gravity. The general solution of this model is given in the case when a Killing vector is present. When interpreted in four dimensions, the solution describes either a static or a homogeneous collision of incoming

Kirill Krasnov

In the loop approach to quantum gravity the spectra of operators corresponding to such geometrical quantities as length, area and volume become quantized. However, the size of arising quanta of geometry in Planck units is not fixed by the theory itself: a free parameter, sometimes referred to as Immirzi parameter, is known to affect the spectrum of all geome

Abhay Ashtekar, Kirill Krasnov

Non-perturbative quantum general relativity provides a possible framework to analyze issues related to black hole thermodynamics from a fundamental perspective. A pedagogical account of the recent developments in this area is given. The emphasis is on the conceptual and structural issues rather than technical subtleties. The article is addressed to post-grad

E. W. Carlson, S. A. Kivelson, V. J. Emery, E. Manousakis

Phase fluctuations of the superconducting order parameter play a larger role in the cuprates than in conventional BCS superconductors because of the low superfluid density of a doped insulator. In this paper, we analyze an XY model of classical phase fluctuations in the high temperature superconductors using a low-temperature expansion and Monte Carlo simula

Per Lyngs Hansen, Rudi Podgornik, Daniel Svenšek, V. Adrian Parsegian

We present a systematic statistical mechanical analysis of the conformational properties of a stiff polyelectrolyte chain with intrachain attractions that are due to counterion correlations. We show that the mean-field solution corresponds to an Euler-like buckling instability. The effect of the conformational fluctuations on the buckling instability is inve

Sergei Maslov, Chao Tang, Yi-Cheng Zhang

We report our findings of an 1/f power spectrum for the total amount of sand in directed and undirected Bak-Tang-Wiesenfeld models confined on narrow stripes and driven locally. The underlying mechanism for the 1/f noise in these systems is an exponentially long configuration memory giving rise to a very broad distribution of time scales. Both models are sol

E. Ben-Naim, P. L. Krapivsky

In a recent paper (cond-mat/9901130), the spatial distribution of unvisited sites in the one-dimensional single-species annihilation process was investigated. It was claimed that this distribution is characterized by a new length scale, and that the corresponding dynamical exponent depends upon the initial concentration. We show numerically that this asserti

V. Bellani, E. Diez, R. Hey, L. Toni

We study the electronic properties of GaAs-AlGaAs superlattices with intentional correlated disorder by means of photoluminescence and vertical dc resistance. The results are compared to those obtained in ordered and uncorrelated disordered superlattices. We report the first experimental evidence that spatial correlations inhibit localization of states in di

Anthony Roberts, Mark Knackstedt

We investigate the effective properties (conductivity, diffusivity and elastic moduli) of model random composite media derived from Gaussian random fields and overlapping hollow spheres. The morphologies generated in the models exhibit low percolation thresholds and give a realistic representation of the complex microstructure observed in many classes of com

C. Rascon, A. O. Parry, A. Sartori

We consider fluid wetting on a corrugated substrate using effective interfacial Hamiltonian theory and show that breaking the translational invariance along the wall can induce an 'unbending' phase transition in addition to unbinding. Both first order and second order unbending transitions can occur at and out of coexistence. Results for systems with

Susanna C. Manrubia, Damian H. Zanette

We study a stochastic multiplicative process with reset events. It is shown that the model develops a stationary power-law probability distribution for the relevant variable, whose exponent depends on the model parameters. Two qualitatively different regimes are observed, corresponding to intermittent and regular behaviour. In the boundary between them, the

Ph. Bourges, Y. Sidis, H. F. Fong, B. Keimer

Key features of antiferromagnetic dynamical correlations in high-$T_C$ superconductors cuprates are discussed. In underdoped regime, the sharp resonance peak, occuring exclusively in the SC state, is accompanied by a broader contribution located around $\sim$ 30 meV which remains above $T_C$. Their interplay may induce incommensurate structure in the superco

M. J. Bijlsma, H. T. C. Stoof

We calculate the excitation frequencies of the low-lying modes of a trapped Bose-condensed gas at nonzero temperatures. We include in our calculation the dynamics of the noncondensed cloud, and find agreement with experimental results if we assume that in the experiment both the in-phase and out-of-phase monopole modes are excited simultaneously. In order to

Christoph Theis, Rolf Schilling

We show that the intermediate scattering function $S_n(q,t)$ for neutron scattering (ns) can be expanded naturely with respect to a set of molecular correlation functions that give a complete description of the translational and orientational two-point correlations in the liquid. The general properties of this expansion are discussed with special focus on th

ChangSoo Park, Sahng-Kyoon Yoo, D. K. Park, Dal-Ho Yoon

We investigate the escape rate of the biaxial nanospin particle with a magnetic field applied along the easy axis. The model studied here is described by the Hamiltonian ${\cal H} = -AS_z^2 - BS_x^2 - HS_z, (A>B>0)$. By reducing this Hamiltonian to a particle one, we derive, for the first time, an effective particle potential for this model and find an analy

N. Hasselmann, A. H. Castro Neto, C. Morais Smith, Y. Dimashko

We study the influence of disorder and lattice effects on the striped phase and the incommensurate spin fluctuations of the cuprates and nickelates. Starting from a phenomenological model of a discrete quantum string on a lattice with disorder, we derive the renormalisation group equations in leading order in the lattice and disorder strength. Three regimes

Eugene Demler, Shou-Cheng Zhang

Within the t-J model of copper-oxides, the condensation energy can be related to the change in the dynamical spin structure factor between the superconducting and the normal states. By analyzing previous experimental data, we show that the change associated with the resonant neutron scattering peak found in $YBa_2Cu_3O_7$ can quantitatively account for the c

T. Bartsch, J. Main, G. Wunner

Gutzwiller's trace formula for the semiclassical density of states in a chaotic system diverges near bifurcations of periodic orbits, where it must be replaced with uniform approximations. It is well known that, when applying these approximations, complex predecessors of orbits created in the bifurcation ("ghost orbits") can produce pronounced si

Rabindra N. Mohapatra, Vigdor L. Teplitz

We propose that the massive compact halo objects (MACHOs) observed in the recent microlensing experiments with an apparent best fit mass of about $0.5 M_{\odot}$ are objects made out of ``mirror'' baryonic matter rather than familiar baryons. Such a possibility arises naturally within the framework of mirror matter models proposed recently to accomod

Belinda J. Wilkes, Eric J. Hooper, Kim K. McLeod, Martin S. Elvis

ISO provides a key new far-infrared window through which to observe the multi-wavelength spectral energy distributions (SEDs) of quasars and active galactic nuclei (AGN). It allows us, for the first time, to observe a substantial fraction of the quasar population in the far-IR, and to obtain simultaneous, multi-wavelength observations from 5--200 microns. Wi

Catherine E. Grant, David N. Burrows

We report on distance determinations for two high Galactic latitude cloud complexes, G192-67 and MBM 23-24. No distance determination exists in the literature for either cloud. Thirty-four early type stars were observed towards the two clouds, more than half of which have parallaxes measured by the Hipparcos satellite. For the remaining stars we have made sp

G. B. Taylor, C. S. Silver, J. S. Ulvestad, C. L. Carilli

We present VLBA observations at 0.33 and 0.61 GHz, and VLA observations between 5 and 22 GHz, of subkiloparsec scale radio emission from Mrk 231. In addition to jet components clearly associated with the AGN, we also find a smooth extended component of size 100 - 1000 pc most probably related to the purported massive star forming disk in Mrk 231. The diffuse

Dean C. Hines, Gary D. Schmidt, Paul S. Smith

We report the discovery of significant linear polarization (p > 1%) in the hyperluminous z=3.87 BALQSO APM~08279+5255. The polarization spectrum is complex, with properties similar to those of other, lower redshift but more highly polarized BALQSOs. The resonance emission lines are unpolarized while the absorption troughs show polarization similar to or high

U. D. J. Gieseler, J. G. Kirk, Y. A. Gallant, A. Achterberg

In the theory of diffusive acceleration at oblique shock fronts the question of the existence of a discontinuity of energetic particle density is contentious. The resolution of this problem is interesting from a theoretical point of view, and potentially for the interpretation of observations of particle densities at heliospheric shocks and of high-resolutio

Antonio Mario Magalhaes, Claudia V. Rodrigues

Polarization observations yield otherwise unobtainable information about the geometrical structure of unresolved objects. In this talk we review the evidences for non-spherically symmetric structures around Luminous Hot Stars from polarimetry and what we can learn with this technique. Polarimetry has added a new dimension to the study of the envelopes of Lum

G. C. Sloan, T. L. Hayward, L. J. Allamandola, J. D. Bregman

Long-slit 8-13 um spectroscopy of the nebula around NGC 1333 SVS reveals spatial variations in the strength and shape of emission features which are probably produced by polycyclic aromatic hydrocarbons (PAHs). Close to SVS 3, the 11.2 um feature develops an excess at ~10.8-11.0 um, and a feature appears at ~10 um. These features disappear with increasing di

Elisabeth Vangioni-Flam, Reuven Ramaty, Michel Casse

The most energetic part of the electromagnetic spectrum bears the purest clues to the synthesis of atomic nuclei in the universe. The decay of radioactive species, synthesized in stellar environments and ejected into the interstellar medium, gives rise to specific gamma ray lines. The observations gathered up to now show evidence for radioactivities througho

A. N. Parmar, T. Oosterbroek, A. Orr, M. Guainazzi

We present 3 methods for the subtraction of non-cosmic and unresolved cosmic backgrounds observed by the Low-Energy Concentrator Spectrometer (LECS) on-board BeppoSAX. Removal of these backgrounds allows a more accurate modeling of the spectral data from point and small-scale extended sources. At high (>|25| degree) galactic latitudes, subtraction using a st

Yu. R. Rivin, V. N. Obridko

The paper contains some arguments in support of time variations of the high-speed flux of solar neutrino

Elisabeth Vangioni-Flam, Michel Casse

Light element nucleosynthesis is an important chapter of nuclear astrophysics. Specifically, the rare and fragile light nuclei Lithium, Beryllium and Boron (LiBeB) are not generated in the normal course of stellar nucleosynthesis (except Li7) and are, in fact, destroyed in stellar interiors. This characteristic is reflected in the low abundance of these simp

Bing Zhang, B. H. Hong, G. J. Qiao

Based on definitions, two joint-criteria, namely, the optical-thin constraint and the energy budget constraint, are proposed to judge whether the emission nature of radio pulsars is incoherent or obligatory to be coherent. We find that the widely accepted criterion, $kT_B \le ε$, is not a rational criterion to describe the optical-thin condition, even for th

Jacco Vink, M. Concetta Maccarone, Jelle S. Kaastra, Teresa Mineo

We present deconvolved narrow band images of Cas A as observed by the MECS instrument on the BeppoSAX X-ray satellite. The images show that Cas A has different morphologies in the continuum and line bands. This difference points towards a synchrotron origin for part of the X-ray continuum of Cas A. Going to the hardest continuum band we find that the emissio

Patrick Petitjean, R. Srianand

Results of a careful analysis of the highly ionized absorption systems, observed over the redshift range 2.198--2.2215 in the zem=2.24 HDFS-QSO J2233-606, are presented. Strong OVI and NeVIII absorptions are detected. Most of the lines show signature of partial coverage which varies from species to species. This can be understood if the clouds cover the cont

R. Cayrel, Y. Lebtreton, P. Morel

The relationship between the respective depletion factors for 6Li and 7Li in metal-poor stars is studied for two simple models of depletion by nuclear burning by mixing with deeper layers, below the bottom of the convective zone. The depletion of 6Li is usually much larger than the depletion of 7Li because it occurs during the pre-mainsequence already.

S. De Grandi, H. Böhringer, L. Guzzo, S. Molendi

We describe the selection of an X-ray flux-limited sample of bright clusters of galaxies in the southern hemisphere, based on the first analysis of the ROSAT All-Sky Survey data (RASS1). The sample is constructed starting from an identification of candidate clusters in RASS1, and their X-ray fluxes are remeasured using the Steepness Ratio Technique. This met

Paola Andreani, Alberto Franceschini, Gianluigi Granato

We test emission models of circum-nuclear dust torii around quasars, at low and high redshifts, by using a large collection of photometric data for an unbiased sample of 120 optically-selected objects with millimetric and sub-millimetric fluxes, including new unpublished data. Under the assumption that the dust is heated by a point-like source with a power-l

Xiaohui Fan

We present a simulation of the spatial, luminosity and spectral distributions of four types of stellar objects. We simulate: (1) Galactic stars, based on a Galactic structure model, a stellar population synthesis model, stellar isochrones, and stellar spectral libraries; (2) white dwarfs, based on model atmospheres, the observed luminosity function, mass dis

I. Felix Mirabel, Luis F. Rodriguez

Black holes of stellar mass and neutron stars in binary systems are first detected as hard X-ray sources using high-energy space telescopes. Relativistic jets in some of these compact sources are found by means of multiwavelength observations with ground-based telescopes. The X-ray emission probes the inner accretion disk and immediate surroundings of the co

J. Christopher Howk, Blair D. Savage

We present high resolution BV images of 12 edge-on spiral galaxies observed with the WIYN 3.5-m telescope. These images were obtained to search for extraplanar (|z| > 0.4 kpc) absorbing dust structures similar to those previously found in NGC 891 (Howk & Savage 1997). Our imaged galaxies include a sample of seven massive L_*-like spiral galaxies within D<25

A. Mondragón, E. Rodríguez-Jáuregui

This paper has been withdrawn by the authors, and instead we have replaced hep-ph/9807214 by this new version.

Hai-Yang Cheng, Hsiang-nan Li, Kwei-Chou Yang

We show that the controversies on the gauge dependence and the infrared singularity emerged in the generalized factorization approach for nonleptonic heavy meson decays within the framework of the operator product expansion can be resolved by perturbative QCD factorization theorem. Gauge invariance of the decay amplitude is maintained under radiative correct

Xiao-jun Li, M. Schick

We introduce a microscopic model of a lipid with a charged headgroup and flexible hydrophobic tails, a neutral solvent, and counter ions. Short-ranged interactions between hydrophilic and hydrophobic moieties are included as are the Coulomb interactions between charges. Further, we include a short-ranged interaction between charges and neutral solvent, which

Anton Kapustin, Matthew J. Strassler

We present an identity relating the partition function of N=4 supersymmetric QED to that of its dual under mirror symmetry. The identity is a generalized Fourier transform. Many known properties of abelian theories can be derived from this formula, including the mirror transforms for more general gauge and matter content. We show that N=3 Chern-Simons QED an

L. Benet, T. H. Seligman

We propose a generic mechanism for the formation of narrow rings in rotating systems. For this purpose we use a system of discs rotating about a common center lying well outside the discs. A discussion of this system shows that narrow rings occur, if we assume non-interacting particles. A saddle-center bifurcation is responsible for the relevant appearance o

C. Jarzynski, O. Mazonka

We introduce a simple, discrete model of Feynman&#39;s ratchet and pawl, operating between two heat reservoirs. We solve exactly for the steady-state directed motion and heat flows produced, first in the absence and then in the presence of an external load. We show that the model can act both as a heat engine and as a refrigerator. We finally investigate the

Michael Steiner

The advent of Bell&#39;s inequalities provoked the possibility that entangled quantum phenomena is non-local in nature. Since teleportation only requires a finite amount of classical information, i.e. two bits, the author asks whether or not it is possible to further characterize the nature of internal correlation in terms of information. Towards this end, t

X. G. Feng, Dragana Popovic, S. Washburn

The temperature dependence of conductivity $σ(T)$ in the metallic phase of a two-dimensional electron system in silicon has been studied for different concentrations of local magnetic moments. The local moments have been induced by disorder, and their number was varied using substrate bias. The data suggest that in the limit of $T\to 0$ the metallic behavior

Yu. A. Simonov

Short distance static quark--antiquark interaction is studied systematically using the background perturbation theory with nonperturbative background described by field correlators. A universal linear term $\frac{6N_cα_sσr}{2π}$ is observed at small distance $r$ due to the interference between perturbative and nonperturbative contributions. Possible modifica

M. Buttiker

A brief overview is presented of recent work which investigates the time-dependent relaxation of charge and its spontaneous fluctuations on mesoscopic conductors in the proximity of gates. The leading terms of the low frequency conductance are determined by a capacitive or inductive emittance and a dissipative charge relaxation resistance. The charge relaxat

C. Daskaloyannis, K. Kanakoglou, I. Tsohantjis

The aim of this paper is to show that there is a Hopf structure of the parabosonic and parafermionic algebras and this Hopf structure can generate the well known Hopf algebraic structure of the Lie algebras, through a realization of Lie algebras using the parabosonic (and parafermionic) extension of the Jordan Schwinger map. The differences between the Hopf

V. G. Kac, A. V. Smilga

We consider the pure supersymmetric Yang--Mills theories placed on a small 3-dimensional spatial torus with higher orthogonal and exceptional gauge groups. The problem of constructing the quantum vacuum states is reduced to a pure mathematical problem of classifying the flat connections on 3-torus. The latter problem is equivalent to the problem of classific

A. Ino, C. Kim, M. Nakamura, T. Yoshida

We report on the result of angle-resolved photoemission (ARPES) study of La$_{2-x}$Sr$_x$CuO$_4$ (LSCO) from an optimally doped superconductor ($x=0.15$) to an antiferromagnetic insulator ($x=0$). Near the superconductor-insulator transition (SIT) $x\sim 0.05$, spectral weight is transferred with hole doping between two coexisting components, suggesting a mi

Alessandro Pelizzola, Marco Pretti

Motivated by a recent proposal of a Bethe approximation for the triangular Ising antiferromagnet [Phys. Rev. B {\bf 56}, 8241 (1997)], which seems to predict a disordered phase at any temperature in zero field, we analyze in some detail several mean-field like approximations for this model, namely the Bethe approximation itself, the cluster variation method

Lorenz Bartosch, Peter Kopietz

We present an efficient algorithm for obtaining the gauge-invariant gradient expansion of the local density of states and the free energy of a clean superconductor. Our method is based on a new mapping of the semiclassical linearized Gorkov equations onto a pseudo-Schroedinger equation for a three-component wave-function psi(x), where one component is direct

Masahiro Fukushima, Hideo Suganuma, Hiroshi Toki

We study color confinement properties of the multi-instanton system, which seems to carry an essence of the nonperturbative QCD vacuum. Here we assume that the multi-instanton system is characterized by the infrared suppression of instantons as $f(ρ)\sim ρ^{-5}$ for large size $ρ$. We first investigate a monopole-clustering appearing in the maximally abelian

W. Bednarek, R. J. Protheroe

We determine the physical parameters (magnetic field and Doppler factor) of the homogeneous synchrotron self-Compton model allowed by the observed X-ray to gamma-ray spectra and variability of Markarian~501 during the 15-16 April 1997 flaring activity. We find that magnetic fields between 0.07 G and 0.6 G and Doppler factors between 12 and 36 could fit (depe

Achille Stocchi

In this paper a review of the LEP analyses on $B^0 - \bar{B}^0$ oscillations and on the measurement of $|V_{ub}|/|V_{cb}|$ is presented . These measurements are of fundamental importance in constraining the $ρ$ and $η$ parameters of the CKM matrix. A review of the current status of the $V_{CKM}$ matrix determination is also given.

G. M. D&#39;Ariano, M. G. A. Paris, M. F. Sacchi

We perform the exact numerical diagonalization of the Hamiltonians that describe both degenerate and nondegenerate parametric amplifiers, by exploiting the conservation laws pertaining each device. We clarify the conditions under which the parametric approximation holds, showing that the most relevant requirement is the coherence of the pump after the intera

Jaroslav Hruby

We define an anti-quantum bit state via analogous way as the anti-state in Particle Physics.We show the quantum information Feymann diagrams for the teleportations and superdense coding, which preserve the information flow. The role of information vacuum and anihilation between error information and anti-information is mentioned for the stability of quantum

Gediminas Juzeliunas

Recently Drummond and Hillery [Phys. Rev.A 59, 691(1999)] presented a quantum theory of dispersion based on the analysis of a coupled system of the electromagnetic field and atoms in the multipolar QED formulation. The theory has led to the explicit mode-expansions for various field-operators in a homogeneous medium characterized by an arbitrary number of re

Terry Rudolph

A scheme is described that allows Alice to communicate to Bob where on earth she is, even though she doesn&#39;t know herself. The situation described shows how the generalization of a recent result of Gisin and Popescu [quant-ph/9901072] could be useful.

B. A. Zon

A theoretical derivation is given for the formula describing N-electron ionization of atom by a dc field and laser radiation in tunneling regime. Numerical examples are presented for noble gases atoms.

K. Morawetz, V. Špička, P. Lipavský, Ch. Kuhrts

The incorporation of realistic trajectories of two-particle scattering into existing BUU or QMD codes meets considerable difficulties. We propose a method of replacing the scattering event by a tractable non-local scenario reproducing the correct asymptotics. The first principle derivation justifies the use of corresponding nonlocal kinetic equations. The no

G. L. Long, H. Y. Ji, E. G. Zhao

Comprehensive evidences of the SU(3) limit in the spdf interacting boson model, a dynamical symmetry describing octupole vibration in rotational nucleus, are found in the spectrum, E2 and E1 transition rates, and relative intensities in $^{158}$Gd. This gives a good example of rotational nucleus with octupole vibration in rare-earth region.

Francisco J. Herranz, Mariano Santander

Expansions of Lie algebras are the opposite process of contractions. Starting from a Lie algebra, the expansion process goes to another one, non-isomorphic and less abelian. We propose an expansion method based in the Casimir invariants of the initial and expanded algebras and where the free parameters involved in the expansion are the curvatures of their as

Eduardo D. Sontag

In this expository paper, which covers material presented at the NATO Advanced Study Institute &#34;Nonlinear Analysis, Differential Equations, and Control&#34; (Montreal, Jul/Aug 1998), we deal with several questions related to stability and stabilization of nonlinear finite-dimensional continuous-time systems. We review the basic problem of feedback stabil

Eduardo D. Sontag, Y. Wang

This paper presents necessary and sufficient characterizations of several notions of input to output stability. Similar Lyapunov characterizations have been found to play a key role in the analysis of the input to state stability property, and the results given here extend their validity to the case when the output, but not necessarily the entire internal st

Eduardo D. Sontag, Y. Qiao

This paper studies controllability properties of recurrent neural networks. The new contributions are: (1) an extension of the result in the previous paper &#34;Complete controllability of continuous-time recurrent neural networks&#34; (Sontag and Sussmann) to a slightly different model, where inputs appear in an affine form, (2) a formulation and proof of a

S. Finashin

Consider a real algebraic variety, $\R X$, of dimension $d$. If its complexification, $\C X$, is a rational homology manifold (at least in a neighborhood of $\R X$), then the intersection form in $\C X$ defines a bilinear form in $d$-homologies of $\R X$. Analizing it, one can obtain an information about $\R X$, as it was done by V.I.Arnold in the case of no

Joachim Kock

On a space of stable maps, the psi classes are modified by subtracting certain boundary divisors. The top products of modified psi classes, usual psi classes, and classes pulled back along the evaluation maps are called twisted descendants; it is shown that in genus 0, they admit a complete recursion and are determined by the Gromov-Witten invariants. One mo

Miklós Bóna, Richard Ehrenborg

We combinatorially prove that the number $R(n,k)$ of permutations of length $n$ having $k$ runs is a log-concave sequence in $k$, for all $n$. We also give a new combinatorial proof for the log-concavity of the Eulerian numbers.

Hua-Huai Chern

The author tries to derive the asymptotic expression of the large eigevalues of some vectorial Sturm-Liouville differential equations. A precise description for the formula of the square root of the large eiegnvalues up to the $O(1/n)$-term is obtained.

Paul M. N. Feehan, Thomas G. Leness

The present article is the first in a series whose ultimate goal is to prove the Kotschick-Morgan conjecture concerning the wall-crossing formula for the Donaldson invariants of a four-manifold with b^+ = 1. The conjecture asserts that the wall-crossing terms due to changes in the metric depend at most on the homotopy type of the four-manifold and the degree

D. Drinen, N. Sieben

Several relations on graphs, including primitive equivalence, explosion equivalence and strong shift equivalence, are examined and shown to preserve either the graph groupoid, a construction of Kumjian, Pask, Raeburn, and Renault, or the groupoid of a pointed version of the graph. Thus these relations preserve either the isomorphism class or the Morita equiv

Ignatios Antoniadis, J. -Pierre Derendinger, Costas Kounnas

We derive a universal thermal effective potential, which describes all possible high-temperature instabilities of the known N=4 superstrings, using the properties of gauged N=4 supergravity. These instabilities are due to three non-perturbative thermal dyonic modes, which become tachyonic in a region of the thermal moduli space. The latter is described by th

D. R. Karakhanyan, R. Kirschner

In the leading log approximation and at large $N_C$ the interaction of two fermionic and one gluonic reggeons is described by an integrable system corresponding to an open spin chain.

A. Gorsky, A. Mironov

Integrable systems underlying the Seiberg-Witten solutions for the N=2 SQCD with gauge groups SO(n) and Sp(n) are proposed. They are described by the inhomogeneous XXX spin chain with specific boundary conditions given by reflection matrices. We attribute reflection matrices to orientifold planes in the brane construction and briefly discuss its possible def

Serguei B. Isakov, Gustavo Lozano, Stéphane Ouvry

The quantum mechanics and thermodynamics of SU(2) non-Abelian Chern-Simons particles (non-Abelian anyons) in an external magnetic field are addressed. We derive the N-body Hamiltonian in the (anti-)holomorphic gauge when the Hilbert space is projected onto the lowest Landau level of the magnetic field. In the presence of an additional harmonic potential, the