September 2000 arXiv papers — page 18

A. Alexandru, R. W. Haymaker

We examine the occurance of Z(2) and SO(3) vorticies and monopole distributions in the neighborhood of Wilson loops. We use the Tomboulis formulation, equivalent to the Wilson action, in which the links are invariant under Z(2) transformations and new plaquette variables carry the Z(2) degrees of freedom. This gives new gauge invariant observables to help ga

A. Alexandru, R. W. Haymaker

We explore simulations on periodic lattices in the Tomboulis $SO(3)\times Z(2)$ formulation. The dynamical variables are constrained. We propose an update algorithm that satisfies the constraints and is straightforward to implement. We show how boundary conditions put constraints on the configuration space.

A. Alexandru, R. W. Haymaker

We explore simulations on periodic lattices in the Tomboulis $SO(3) \times Z(2)$ formulation. We measure gauge invariant vortex counters for "thin", "thick" and "hybrid" vortex sheets in order to tag Wilson loops by the occurance of gauge invariant vortices linking them. We also measure projection vortex counters defined in the maxima

A. Alexandru, R. W. Haymaker

We study the configuration space of the Tomboulis $SO(3) \times Z(2)$ formulation with periodic boundary conditions. The dynamical variables are constrained by the required coincidence of Z(2) and SO(3) monopoles. Furthermore, there is an additional constraint coming from the boundary conditions. We propose an update algorithm that satisfies the constraints

H. C. G. Caldas, P. R. Silva

The spreading of quantum mechanical wave packets is studied in two cases. Firstly we look at the time behavior of the packet width of a free particle confined in the observable Universe. Secondly, by imposing the conservation of the time average of the packet width of a particle driven by a harmonic oscillator potential, we find a zero-point energy which fre

Steven D. Penn, Gregory M. Harry, Andri M. Gretarsson, Scott E. Kittelberger

We have measured the mechanical dissipation in a sample of fused silica drawn into a rod. The sample was hung from a multiple-bob suspension, which isolated it from rubbing against its support, from recoil in the support structure, and from seismic noise. The quality factor, Q, was measured for several modes with a high value of 57 million found for mode num

G. Esposito-Farese, D. Polarski

We consider scalar-tensor theories of gravity in an accelerating universe. The equations for the background evolution and the perturbations are given in full generality for any parametrization of the Lagrangian, and we stress that apparent singularities are sometimes artifacts of a pathological choice of variables. Adopting a phenomenological viewpoint, i.e.

D. V. Ahluwalia

This talk presents: (a) A quantum-mechanically induced violation of the principle of equivalence, and (b) Gravitationally-induced modification to the wave particle duality. In this context I note that the agreement between the predictions of general relativity and observations of the energy loss due to gravitational waves emitted by binary pulsars is just as

Edward Malec

The Schwarzschild spacetime is for electromagnetic waves like a nonuniform medium with a varying refraction index. A fraction of an outgoing radiation scatters off the curvature of the geometry and can be intercepted by a gravitational center. The amount of the intercepted energy is bounded above by the backscattered energy of an initially outgoing pulse of

Antonio Pulido, Alfredo Tiemblo, Romualdo Tresguerres

We present a suggestion on the interpretation of canonical time evolution when gravitation is present, based on the nonlinear gauge approach to gravity. Essentially, our proposal consists of an internal-time concept, with the time variable taken from the dynamical fields characteristic of the nonlinear realization of the internal time-translational symmetry.

D. Alves, P. R. A. Campos, A. T. C. Silva, J. F. Fontanari

The evolution of enzyme production is studied analytically using ideas of the group selection theory for the evolution of altruistic behavior. In particular, we argue that the mathematical formulation of Wilson's structured deme model ({\it The Evolution of Populations and Communities}, Benjamin/Cumings, Menlo Park, 1980) is a mean-field approach in whic

Xin Wan, R. N. Bhatt

We report results of a Monte Carlo study of doped, diluted magnetic semiconductors in the low carrier density (insulating) regime. We find that the system undergoes a transition from a paramagnet at high temperatures to a ferromagnet at low temperatures. However, in strong contrast to uniform systems, disorder effects dominate the entire collective behavior,

D. A. Dimitrov, H. Roder, A. R. Bishop

The effect of the powder average on the peak shapes and positions in neutron pair distribution functions of polycrystalline materials is examined. It is shown that for highly anisotropic crystals, the powder average leads to shifts in peak positions and to non-Gaussian peak shapes. The peak shifts can be as large as several percent of the lattice spacing.

Zhang Yang

The short supercoiled circular DNA molecules are shown to be glassy systems and canonical Metropolis Monte Carlo simulations of the systems tend to get stuck in local metastable energy basins. A novel Monte Carlo algorithm is developed to alleviate the problem of ``ergodicity breaking'' of the glassy systems, in which the Markov process is driven by

V. Kiryukhin, Y. J. Kim, K. J. Thomas, F. C. Chow

We report single crystal growth and magnetic susceptibility and neutron diffraction studies of the S=1/2 quasi-1D antiferromagnet CaCu2O3. The structure of this material is similar to that of the prototype two-leg spin-ladder compound SrCu2O3. However, the Cu-O-Cu bond angle in the ladder rungs in CaCu2O3 is equal to 123 deg, and therefore the magnetic inter

F. C. Alcaraz, R. Z. Bariev

The exact solution of the asymmetric exclusion problem with N distinct classes of particles (c = 1,2,...,N), with hierarchical order is presented. In this model the particles (size 1) are located at lattice points, and diffuse with equal asymmetric rates, but particles in a class c do not distinguish those in the classes c' >c from holes (empty sites). W

Michele Governale, Daniel Boese

We investigate the conductance properties of a hybrid ferromagnet-semiconductor structure consisting of a confined two-dimensional electron gas and a transverse ferromagnetic strip on top. Within the framework of the Landauer-Büttiker model, we develop an alternative way to consider magnetic fields. Our method describes devices ranging from a recently realiz

H. Hakkinen, R. N. Barnett, A. G. Scherbakov, U. Landman

Structural transformations, electronic spectra and ballistic transport in pulled gold nanowires are investigated with ab initio simulations, and correlated with recent measurements. Strain-induced yield of an initial double-strand wire results first in formation of a bent-chain which transforms upon further elongation to a linear atomic chain exhibiting dime

J. van Mourik, A. C. C. Coolen

We propose a general scheme in which disordered systems are allowed to sacrifice energy equi-partitioning and separate into a hierarchy of ergodic sub-systems (clusters) with different characteristic time-scales and temperatures. The details of the break-up follow from the requirement of stationarity of the entropy of the slower cluster, at every level in th

Andre G. Moreira, Roland R. Netz

We study the phase behavior of solutions consisting of positive and negative ions of valence z to which a third ionic species of valence Z>z is added. Using a discretized Debye-Hueckel theory, we analyze the phase behavior of such systems for different values of the ratio Z/z. We find, for Z/z>1.934, a three-phase coexistence region and, for Z/z>2, a closed

S. Sorella

We show that the standard Lanczos algorithm can be efficiently implemented statistically and self consistently improved, using the stochastic reconfigurat ion method, which has been recently introduced to stabilize the Monte Carlo sign problem instability. With this scheme a few Lanczos steps over a given variational wavefunction are possible even for large

I. Kezsmarki, Sz. Csonka, H. Berger, L. Forro

We carried out magnetotransport experiments under hydrostatic pressure in order to study the nature of the metal-insulator transition in BaVS$_3$. Scaling relations for $ρ(T,H,p)$ are established and the pressure dependence of the spin gap is determined. Our new results, in conjunction with a re-analysis of earlier specific heat and susceptibility data, demo

R. Bahnsen, H. Eckstein, W. Schattke, N. Fitzer

Quantum Monte Carlo methods have proven to predict atomic and bulk properties of light and non-light elements with high accuracy. Here we report on the first variational quantum Monte Carlo (VMC) calculations for solid surfaces. Taking the boundary condition for the simulation from a finite layer geometry, the Hamiltonian, including a nonlocal pseudopotentia

B. Camarota, F. Parage, F. Balestro, P. Delsing

We have studied niobium superconducting thin wires deposited onto a SrTiO$_{3}$ substrate. By measuring the reflection coefficient of the wires, resonances are observed in the superconducting state in the 130 MHz to 4 GHz range. They are interpreted as standing wave resonances of one-dimensional plasma modes propagating along the superconducting wire. The ex

Yupeng Wang, P. Schlottmann

A Coqblin-Schrieffer impurity of spin $S$ coupled to the boundary of an open SU(N)-invariant $t-J$ chain with $N = 2S+2$ is studied. The model is integrable as a function of one coupling parameter $v$ for arbitrary spin and band filling. The system is coupled to a reservoir of electrons and as a function of the chemical potential the host chain has a critica

Tsunehiro Kobayashi, Toshiki Shimbori

Free energies and other thermodynamical quantities are investigated in canonical and grand canonical ensembles of statistical mechanics involving unstable states which are described by the generalized eigenstates with complex energy eigenvalues in the conjugate space of Gel'fand triplet. The theory is applied to the systems containing parabolic potential

T. A. S. Haddad, S. T. R. Pinho, S. R. Salinas

We review recent investigations of the critical behavior of ferromagnetic $q$-state Potts models on a class of hierarchical lattices, with exchange interactions according to some deterministic but aperiodic substitution rules. The problem is formulated in terms of exact recursion relations on a suitable parameter space. The analysis of the fixed points of th

E. Xanthopoulos, M. Norbury, A. Karidis, N. Jackson

We present results from VLBA+Effelsberg 1.7 GHz, VLBA 8.4 GHz and VLBA 15 GHz observations of the JVAS gravitational lens system B1030+074. The VLBA+Effelsberg 1.7 GHz data with 3 mas resolution reveal a detailed 60 mas jet structure in the strong A component of the lens system and maybe a first hint of the corresponding jet structure in the faint component

S. Dos Santos

The temperature profile (TP) of the intracluster medium (ICM) is of primeval importance for deriving the dynamical parameters of the largest equilibrium systems known in the universe, in particular their total mass profile. Analytical models of the ICM often assume that the ICM is isothermal or parametrize the TP with a polytropic index. This parameter is aj

Ravi K. Sheth, Lam Hui, Antonaldo Diaferio, Roman Scoccimarro

We write the correlation function of dark matter particles, xi(r), as the sum of two terms - one which accounts for nonlinear evolution, and dominates on small scales, and another which is essentially the term from linear theory, and dominates on large scales. We use models of the number and spatial distribution of haloes and halo density profiles to describ

Ravi K. Sheth, Antonaldo Diaferio

We present a simple model for the shape of the distribution function of galaxy peculiar velocities. We show how both nonlinear and linear theory terms combine to produce a distribution which has an approximately Gaussian core with exponential wings. The model is easily extended to study how the statistic depends on the type of particle used to trace the velo

Claudia Travaglio, Daniele Galli, Andreas Burkert

We present a stochastic model based on the Monte Carlo technique to study the inhomogeneous chemical evolution of the Galactic halo. In particular, we consider the local enrichment and subsequent mixing of the interstellar gas resulting from bursts of star formation, following explicitly the fragmentation and coalescence of interstellar gas clouds. The model

Luis Borgonovo, Felix Ryde

We study the hardness-intensity correlation (HIC) in gamma-ray bursts (GRBs). In particular, we analyze the decay phase of pulse structures in their light curves. The study comprises a sample of 82 long pulses selected from 66 long bursts observed by BATSE on the Compton Gamma-Ray Observatory. We find that at least 57% of these pulses have HICs that can be w

E. Puddu, E. De Filippis, V. Strazzullo, S. Andreon

We discuss the implementation and validation of a procedure aimed to detect groups and clusters of galaxies in DPOSS catalogs.

Povilas Palunas, T. B. Williams

We present axisymmetric maximum disk mass models for a sample of 74 spiral galaxies taken from the southern sky Fabry-Perot Tully-Fisher survey (Schommer et al. 1993). The sample contains galaxies spanning a large range of morphologies and having rotation widths from 180 km/sec to 680 km/secs. For each galaxy we have an I-band image and a 2-d H_alpha velocit

F. Frontera, E. Palazzi, A. A. Zdziarski, F. Haardt

We report on the 0.5--200 keV spectral properties of Cyg X-1 observed at different epochs with the Narrow Field Instruments of the BeppoSAX satellite. The source was in its soft state during the first observation of 1996 June. In the second observation of 1996 September, the source had parameters characteristic to its hard state. A soft X-ray excess, a broad

U. Heber, I. N. Reid, K. Werner

Three members of the new class of pulsating sdB stars (sdBV or EC 14026 stars) are analysed from Keck HIRES spectra using line blanketed NLTE and LTE model atmospheres. Atmospheric parameters (Teff, log g, He/H), metal abundances and rotational velocities are determined. As is typical for sdB stars, all programme stars are found to be helium deficient, with

A. Fontana, S. D'Odorico, F. Poli, E. Giallongo

We present and compare in this paper new photometric redshift catalogs of the galaxies in three public fields: the NTT Deep Field, the HDF-N and the HDF-S. Photometric redshifts have been obtained for thewhole sample, by adopting a $χ^2$ minimization technique on a spectral library drawn from the Bruzual and Charlot synthesis models, with the addition of dus

S. J. Smartt, K. A. Venn, P. L. Dufton, D. J. Lennon

High-resolution, high signal-to-noise spectral data are presented for four young B-type stars lying towards the Galactic Centre. Determination of their atmospheric parameters from their absorption line profiles, and uvby photometric measurement of the continua indicate that they are massive objects lying slightly out of the plane, and were probably born in t

H. S. Zhao, N. W. Evans

The off-centered "bar" of the Large Magellanic Cloud (LMC) is commonly assumed, for simplicity's sake, to lie in the same plane as the LMC disk. Relaxing this assumption to the extent allowed by the observations, we can drastically change our interpretation of the microlensing events towards the LMC. We propose that the off-centered ``bar'&#3

Stephen Eales, Simon Lilly, Tracy Webb, Loretta Dunne

We have used SCUBA to survey an area of 50 square arcmin, detecting 19 sources down to a 3sigma sensitivity limit of 3.5 mJy at 850 microns. We have used Monte-Carlo simulations to assess the effect of source confusion and noise on the SCUBA fluxes and positions, finding that the fluxes of sources in the SCUBA surveys are significantly biased upwards and tha

Toshifumi Futamase, Masahiro Takada

We investigate the dependence of cosmological parameters on the number count of peaks (local maxima and minima) in the cosmic microwave background (CMB) sky. The peak statistics contains the whole information of acoustic oscillations in the angular power spectrum $C_l$ over $l$-space and thus it can place complementary constraints on the cosmological paramet

S. C. Chapman, D. Scott, C. Borys, M. Halpern

We summarize the main results from our SCUBA survey of Lyman-break galaxies (LBGs) at z~3. Analysis of our sample of LBGs reveals a mean flux of S850=0.6$\pm$0.2 mJy, while simple models of emission based on the UV properties predict a mean flux about twice as large. Known populations of LBGs are expected to contribute flux to the weak sub-mm source portion

L. Knox, A. Cooray, D. Eisenstein, Z. Haiman

The large-scale structure of high-redshift galaxies produces correlated anisotropy in the far-infrared background (FIRB). In regions of the sky where the thermal emission from Galactic dust is well below average, these high-redshift correlations may be the most significant source of angular fluctuation power over a wide range of angular scales, from about 7&

Noam Shomron

We calculate the blocks of the category of finite-dimensional representations of W(0,n), with n > 2, and show that all are of wild type. As an application, we show that the centre of the universal enveloping algebra is trivial.

Marshall M Cohen, Colin Rourke

We use Klyachko's methods to prove that the natural map G to G-hat, where G is a torsion-free group and G-hat is obtained by adding a new generator t and a new relator w, is surjective only if w is conjugate to gt or gt^{-1} for some g in G. This solves a special case of the surjectivity problem for group extensions, raised by Cohen [Whitehead torsion, g

Anindya Datta, Partha Konar, Biswarup Mukhopadhyaya

We investigate signals of the lightest neutral Higgs in an R-parity violating supersymmetric model through the vector boson fusion mechanism. Assuming that R-parity is violated through lepton number, and locating regions in the parameter space where decays of such a neutral scalar into a pair of lightest neutralinos can be significant, we proceed to calculat

Guillaume Dubus, Rita S. J. Kim, Kristen Menou, Paula Szkody

We report on optical spectroscopic observations of the X-ray Transient XTE J1118+480 covering the period from April 7, 2000 to July 4, 2000. The spectrum is characterized by weak, broad, double-peaked Balmer and He lines on top of a blue continuum of slope p ~ 1/3, as expected for an optically-thick accretion disk. The weak Bowen blend seen in our spectra ma

Jason Pruet, Kevork Abazajian, George M. Fuller

We demonstrate a qualitatively new aspect of the dynamics of Gamma-Ray Burst (GRB) fireballs: the development of a substantial dispersion in the proton component in fireballs in which neutron decoupling occurs and is sufficiently pronounced. This effect depends sensitively on the neutron to proton ratio in the fireball, becoming more dramatic with increasing

A. K. Motovilov, W. Sandhas, S. A. Sofianos, E. A. Kolganova

The 4He3 system is investigated using a hard-core version of the Faddeev differential equations and realistic 4He-4He interactions. We calculate the binding energies of the 4He trimer but concentrate in particular on scattering observables. The atom-diatom scattering lengths are calculated as well as the atom-diatom phase shifts for center of mass energies u

Yuan-Zhong Zhang

It says in the report$^1$ by Wang et al. that a negative group velocity $u=-c/310$ is obtained and that a pulse advancement shift 62-ns is measured. The authors claim that the negative group velocity is associated with superluminal light propagation and that the pulse advancement is not at odds with causality or special relativity. However, it is shown here

Sami I. Muslih

Systems with singular higher order- Lagrangians are investigated by using the extended form of the canonical method. Besides, the canonical path integral formulation is generalized using the Hamilton- jacobi formulation to investigate singular systems

Maen Odeh, Omar Mustafa

The pseudoperturbative shifted - $l$ expansion technique PSLET is generalized for states with arbitrary number of nodal zeros. Bound- states energy eigenvalues for two truncated coulombic potentials are calculated using PSLET. In contrast with shifted large-N expansion technique, PSLET results compare excellently with those from direct numerical integration.

Vladimir V. Kisil

The aim of the paper is to popularise nilpotent Lie groups (notably the Heisenberg group and alike) in the context of Clifford analysis and related models of mathematical physics. It is argued that these groups are underinvestigated in comparison with other classical branches of analysis. We list five general directions which seem to be promising for further

John Lott

We show that a noncompact manifold with bounded sectional curvature, whose ends are sufficiently Gromov-Hausdorff close to rays, has a finite dimensional space of square-integrable harmonic forms. In the special case of a finite-volume manifold with pinched negative sectional curvature, we show that the essential spectrum of the p-form Laplacian is the union

Shaohui Zhai

We compute the capacity region of the s-sender Multiple Access Adder Channel in information theory and obtain an explicit description of this region as only one polyhedron, instead of a convex hull of infinitely many polyhedrons. We obtain this by proving a conjecture raised by Lindstrom in 1975, which in turn follows from certain convexity results, both con

Osman Mucuk, Ilhan Icen

A groupoid is a small category in which each morphism has an inverse. A topological groupoid is a groupoid in which both sets of objects and morphisms have topologies such that all groupoid structure maps are continuous. The notion of monodromy groupoid of a topological groupoid generalises those of fundamental groupoid and universal covering. It was earlier

Ilhan Icen, Osman Mucuk

The notion of local subgroupoids as generalition of a local equivalence relations was defined by the first author and R.Brown. Here we investigate some relations between transitive components and coherence properties of the local subgroupoids.

Shaohui Zhai

Suppose we are given a set of t coins which look identical, but a known number s of them are counterfeit, with a known weight different from the others. Our problem is to locate the counterfeits by weighing subsets of the t coins, with as few weighings as possible. Despite a large literature on this problem, it remains wide open for s>2. In this paper, we gi

John Lott

We analyze the limit of the spectrum of a geometric Dirac-type operator under a collapse with bounded diameter and bounded sectional curvature. In the case of a smooth limit space B, we show that the limit of the spectrum is given by the spectrum of a certain first-order differential operator on B, which can be constructed using superconnections. In the case

Stephen L. Adler

We consider generic N=1 supersymmetric matter coupled to linearized N=1 supergravity through the multiplet of currents. By completing the square, we find the effective action giving the leading supergravity induced correction to the matter dynamics, expressed explicitly as a quadratic form in the components of the current multiplet. The effective action is s

Jungil Lee

Next-to-leading order corrections to fragmentation functions in a light-cone gauge are discussed. This gauge simplifies the calculation by eliminating many Feynman diagrams at the expense of introducing spurious poles in loop integrals. As an application, the short-distance coefficients for the color-octet $^3S_1$ term in the fragmentation function for a glu

S. Arunagiri

We estimate the renormalon corrections to the inclusive decay rate of heavy hadrons. We assume the gluon mass term $λ^2 \gg `^2$ to imitate the short distance nonperturbative effects. It is found that the the inclusive decay rates are corrected by an amount of about 0.2 $Γ_0$ for $B$ meson and 0.21 $Γ_0$ for baryon. This is significant in view of the discrep

Stephan Narison

Within the increasing experimental evidence of the existence of the I=0 scalar low mass and wide σmeson, we review the {\it first} analysis of its quark and gluon substructure from QCD spectral sum rules and some low-energy theorems. The present data favour equal components of \bar uu+ \bar dd and of gg in its wave function, which make the wide sigma and the

A. A. Pivovarov

Results of analytical calculations for heavy quark systems in higher orders of perturbation theory are overviewed. I discuss baryons with one finite mass quark in the next-to-leading order and heavy quark pair production near the threshold within NRQCD.

S. Baek, J. -H. Jang, P. Ko, J. H. Park

We show that, on the contrary to the usual claims, fully supersymmetric CP violations in the kaon system are possible through the gluino mediated flavor changing interactions. Both $ε_K$ and ${\rm Re} (ε' / ε_K)$ can be accommodated for relatively large $\tanβ$ without any fine tunings or contradictions to the FCNC and EDM constraints.

Arkadii A. Popov, Sergey V. Sushkov

An analitical approximation of $<ϕ^2>$ for a scalar field in a static spherically symmetric wormhole spacetime is obtained. The scalar field is assumed to be both massive and massless, with an arbitrary coupling $ξ$ to the scalar curvature, and in a zero temperature vacuum state.

L. S. Schulman

The second law of thermodynamics - the usual statement of the arrow of time - has been called the most fundamental law of physics. It is thus difficult to conceive that a single dynamical system could contain subsystems, in significant mutual contact, possessing opposite thermodynamic arrows of time. By examining cosmological justification for the usual arro

L. C. Garcia de Andrade

Density linear perturbations in Einstein-Cartan two fluid cosmologies where the outer model is an isotropic Friedmann solution with closed model while the inner model is a flat anisotropic Einstein-Cartan (EC) cosmology with shear are computed by taking into consideration superhorizon situations.This situation is in agreement with the present isotropy of the

N. V. Voshchinnikov, D. A. Semenov

The temperatures of prolate and oblate spheroidal dust grains in the envelopes of stars of various spectral types are calculated. Homogeneous particles with aspect ratios {\small $a/b \le 10$} composed of amorphous carbon, iron, dirty ice, various silicates, and other materials are considered. The temperatures of spherical and spheroidal particles were found

Jun Ogura, Nobuyori Ohuo, Yasufumi Kojima

We examined the profiles and polarization properties of emission lines originating from the extremely relativistic region of Kepler disks. Because the emission region is more localized to the inner part, e.g., a few times the black hole radius, the profiles, and polarization properties are remarkably modified. The black hole spin significantly affects the pr

D. A. Semenov, N. V. Voshchinnikov

Observational data for dusty comets are summarized and systemized. The dependence of the linear polarization on various parameters (the phase angle, wavelength, etc.) is analyzed. An ensemble of aligned spheroidal particles having various sizes and chemical compositions is used to fit the linear and circular polarization observed for the comet Halley.

Nikolai V. Voshchinnikov

The albedo and dichroic polarization of spheroidal particles are studied. For the description of the phase function two asymmetry parameters $g_{||}$ and $g_{\bot}$ characterizing the anisotropy in forward/backward and left/right directions are introduced and calculated. The consideration is based on the solution to the light scattering problem by the Separa

I. G. Zacharia, D. Goldhaber-Gordon, G. Granger, M. A. Kastner

We report the temperature dependence of the zero-bias conductance of a single-electron transistor in the regime of weak coupling between the quantum dot and the leads. The Fano line shape, convoluted with thermal broadening, provides a good fit to the observed asymmetric Coulomb charging peaks. However, the width of the peaks increases more rapidly than expe

Ruben Cordero, Efrain Rojas

We develop the dynamics of the chiral superconducting membranes (with null current) in an alternative geometric approach either making a Lagrangian description and a Hamiltonian point of view. Besides of this, we show the equivalence of the resulting descriptions to the one known Dirac-Nambu-Goto (DNG) case. Integrability for chiral string model is obtained

Jeffrey D. Scargle

Identification of local structure in intensive data -- such as time series, images, and higher dimensional processes -- is an important problem in astronomy. Since the data are typically generated by an inhomogeneous Poisson process, an appropriate model is one that partitions the data space into cells, each of which is described by a homogeneous (constant e

L. Ya. Glozman, D. O. Riska

The implications of the pion (meson) degrees of freedom for baryon properties, taken at the constituent quark and baryon levels are compared. It is shown that there is a dramatic qualitative difference between two approaches.

N. A. Sidorov, A. V. Sinitsyn

The theorem on the existence of bifurcation points of the stationary solutions for the Vlasov-Maxwell system with bifurcation direction is proved.

A. V. Sinitsyn

On the basis of generalization of upper and lower solution method to the singular two point boundary value problems, the existence theorem of solutions for the system, which models a process of magnetic insulation in plasma is proved.

George Japaridze, Wolf-Dieter Nowak, Avto Tkabladze

We investigate $J/ψ$ photoproduction asymmetries in the framework of the NRQCD factorization approach. It is shown that the color octet contribution leads to large uncertainties in the predicted asymmetries which rules out the possibility to precisely measure the gluon polarization in the nucleon through this final state. For small values of the color octet

Y. Liu, O. Miyamura, A. Nakamura, T. Takaishi

SU(2) lattice gauge theory with dynamical fermion at non-zero chemical potential and at finite temperature is studied. We focus on the influence of chemical potential for quark condensate and mass of pseudoscalar meson at finite temperature. Hybrid Monte Carlo simulations with $N_f=8$ staggered fermions are carried out on $12 \times 12\times 24 \times 4$ lat

I. G. Lang L. I. Korovin, D. A. Contreras-Solorio, S. T. Pavlov

It has been shown that the non-sinusoidal character oscillations appear in the transmitted, reflected and absorbed light fluxes when light pulses irradiate a semiconductor quantum well (QW), containing a set of a large number of the equidistant energy levels of electronic excitations. The oscillation amplitude is comparable to the flux values for the short p

A. V. Moiseev

The results of $H_α$ and [NII]$λ6583$ observations of the spiral galaxy NGC 1084 at the SAO 6m telescope with a Fabry-Perot interferometer are presented. The complex structure of the emission line profile has revealed the presence of giant star formation regions (``spur&#39;&#39;) in the NE part of the galaxy. In this region the $H_α$ line shows two distinct

Colin Borys, Scott Chapman, Mark Halpern, Douglas Scott

We present an 11 X 11 arcminute map centred on the Hubble Deep Field taken at 850 microns with the SCUBA camera on the JCMT. The map has an average one-sigma sensitivity to point sources of about 2.3 mJy and thus probes the brighter end of the sub-mm source counts. We find 7 sources with a flux greater than 9 mJy (roughly 4 sigma), and therefore estimate N(>

E. Pignatelli, J. C. Vega Beltran, J. E. Beckman, E. M. Corsini

We present V-band surface photometry and major-axis kinematics of stars and ionized gas of three early-type spiral galaxies, namely NGC 772, NGC 3898 and NGC 7782. For each galaxy we built a self-consistent Jeans model for the stellar kinematics, adopting the light distribution of bulge and disc derived by means of a two-dimensional parametric photometric de

W. Brandner, S. Sheppard, H. Zinnecker, L. Close

Observations of the rho Ophiuchi star forming region with VLT ANTU and ISAAC under 0.35&#34; seeing conditions reveal two bipolar reflection nebulosities intersected by central dust lanes. The sources (OphE-MM3 and CRBR 2422.8-3423) can be identified as spatially resolved circumstellar disks viewed close to edge-on, similar to edge-on disk sources discovered

Ruben Cordero, Efrain Rojas

We present a geometrical canonical description for superconducting membranes. We consider a general action which includes a general class of superconducting extended objects (strings and domain walls). The description is inspired in the ADM framework of general relativity but, instead of the standard canonical variables a different kind of phase space is con

Andrew M. Smith, Nicholas R. Collins, William H. Waller, Morton S. Roberts

Far ultraviolet FUV imagery of the edge-on, Sc/SBd galaxy, NGC 4631 reveals very strong FUV emission, resulting from active star formation, uniformly distributed along the galactic mid- plane. Multi-band imagery, HI and HII position-velocity curves and extinction considerations all imply that the emission is from the outer edges of the visible galaxy. The ov

M. V. Kuzmenko

A nonrelativistic equation for the system of two interacting particles within the framework of a model with noncommuting operators of coordinates and momenta of different particles is proposed, and a self-consistent system of equations for the wave function of every quantum state is deduced. Solutions for the lowest states of a hydrogenlike atom are found, a

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

Optically pumped nuclear magnetic resonance measurements of Ga-71 spectra were carried out in an n-doped GaAs/Al0.1Ga0.9As multiple quantum well sample near the integer quantum Hall ground state Nu=1. As the temperature is lowered (down to T~0.3 K), a ``tilted plateau&#39;&#39; emerges in the Knight shift data, which is a novel experimental signature of quas

F. Finelli, S. Khlebnikov

We study numerically evolution of metric perturbations during reheating in a model with two fields and a strong parametric resonance. Our calculation is fully nonlinear and includes gravity but is restricted to spherical symmetry. In this model, super-Hubble metric perturbations can grow during reheating only due to effects nonlinear in fluctuations of the f

Philip D. Mannheim

We show that the embedding of either a static or a time dependent maximally 3-symmetric brane with non-zero spatial curvature $k$ into a non-compactified $AdS_5$ bulk does not yield exponential suppression of the geometry away from the brane. Implications of this result for brane-localized gravity are discussed.

Aurel Bulgac, Piotr Magierski

We briefly review the significance of quantum corrections in the total energy of systems with voids: bubble nuclei, atomic clusters and the inhomogeneous phase of neutron stars.

T. Coleman, M. G. Olsson, S. Veseli

We demonstrate that the B->D(*) l nu form factors can be accurately predicted given the slope parameter rho^2 of the Isgur-Wise function. Only weak assumptions, consistent with lattice results, on the wavefunction for the light degrees of freedom are required to establish this result. We observe that the QCD and 1/m_Q corrections can be systematically repres

A. R. Barker, S. H. Kettell

We review the current status of the field of rare kaon decays. The study of rare kaon decays has played a key role in the development of the standard model, and the field continues to have significant impact. The two areas of greatest import are the search for physics beyond the standard model and the determination of fundamental standard-model parameters. D

J. Bartels, S. Gieseke, C. -F. Qiao

As a first step towards the computation of the NLO corrections to the photon impact factor in the $γ^*γ^* \to γ^* γ^*$ scattering process, we calculate the one loop corrections to the coupling of the reggeized gluon to the $γ^*\to q\bar{q}$ vertex. We list the results for the Feynman diagrams which contribute: all loop integrations are carried out, and the r

John H. Reina, Luis Quiroga, Neil F. Johnson

A major question for condensed matter physics is whether a solid-state quantum computer can ever be built. Here we discuss two different schemes for quantum information processing using semiconductor nanostructures. First, we show how optically driven coupled quantum dots can be used to prepare maximally entangled Bell and Greenberger-Horne-Zeilinger states

Ram Brustein, David Eichler, Stefano Foffa, David H. Oaknin

It is suggested that the Minkowski vacuum of quantum field theories of a large number of fields N would be gravitationally unstable due to strong vacuum energy fluctuations unless an N dependent sub-Planckian ultraviolet momentum cutoff is introduced. We estimate this implied cutoff using an effective quantum theory of massless fields that couple to semi-cla

C. Baccigalupi, C. Burigana, F. Perrotta, G. De Zotti

We have analyzed the available polarization surveys of the Galactic emission to estimate to what extent it may be a serious hindrance to forthcoming experiments aimed at detecting the polarized component of Cosmic Microwave Background (CMB) anisotropies. Regions were identified for which independent data consistently indicate that depolarization must be smal

H. Falomir, P. A. G. Pisani

We study the stationary problem of a charged Dirac particle in (2+1) dimensions in the presence of a uniform magnetic field B and a singular magnetic tube of flux Phi = 2 pi kappa/e. The rotational invariance of this configuration implies that the subspaces of definite angular momentum l+1/2 are invariant under the action of the Hamiltonian H. We show that,