August 2000 arXiv papers — page 8

Martin Welk

We study covariant differential calculus on the quantum spheres S_q^{N-1} which are quantum homogeneous spaces with coactions of the quantum groups O_q(N). The first part of the paper is devoted to first order differential calculus. A classification result is proved which says that for N>=6 there exist exactly two covariant first order differential calculi o

N. P. Brown, M. Dadarlat

We study the extension problem for quasidiagonal (QD) C*-algebras (i.e. when is an extension of QD C*-algebras again QD?). The main positive result states that in many instances an extension will remain QD provided that a certain boundary arising from the K-theory of the extension vanishes. A K-theoretic Hahn-Banach type property is also introduced for QD C*

Nathanial P. Brown

We give a detailed survey of the theory of quasidiagonal C*-algebras. The main structural results are presented and various functorial questions around quasidiagonality are discussed. In particular we look at what is currently known (and not known) about extensions, quotients, tensor products, ect. of quasidiagonal C*-algebras. We also point out how quasidia

Markus Fulmek

We prove a continued fraction expansion for a certain q--tangent function that was conjectured by Prodinger.

Ola Bratteli, Akitaka Kishimoto

We consider AF-flows, i.e., one-parameter automorphism groups of a unital simple C*-algebra which leave invariant the dense union of an increasing sequence of finite-dimensional *-subalgebras, and derive two properties for these; an absence of continuous symmetry breaking and a kind of real rank zero property for the almost fixed points.

Maks A. Akivis, Vladislav V. Goldberg

Finding examples of tangentially degenerate submanifolds (submanifolds with degenerate Gauss mappings) in an Euclidean space $R^4$ that are noncylindrical and without singularities is an important problem of differential geometry. The first example of such a hypersurface was constructed by Sacksteder in 1960. In 1995 Wu published an example of a noncylindric

T. Koide, M. Maruyama

We derive a new expansion of the Heisenberg equation of motion based on the projection operator method proposed by Shibata, Hashitsume and Shingū. In their projection operator method, a certain restriction is imposed on the initial state. As a result, one cannot prepare arbitrary initial states, for example a coherent state, to calculate the time development

Ion I. Cotăescu, Mihai Visinescu

We investigate the SO(4,1) gauge-invariant theory of the Dirac fermions in the external field of the Kaluza-Klein monopole, pointing out that the quantum modes can be recovered from a Klein-Gordon equation analogous to the Schr\" odinger equation in the Taub-NUT background. Moreover, we show that there is a large collection of observables that can be dir

Pablo Mora

In this paper we continue the study of the model proposed in the previous paper hep-th/0002077. The model consist of a system of extended objects of diverse dimensionalities, with or without boundaries, with actions of the Chern-Simons form for a supergroup. We also discuss possible connections with Superstring/M-theory.

Sze-Shiang Feng, Mu-Lin Yan

Using the proposed AdS/CFT correspondence, we calculate the correlators of operators of conformal field theory at the boundary of AdS$_{d+1}$ corresponding to the sine-Gordon model in the bulk.

Lai-Him Chan

I present a unified formulation of anomalous contributions in quantum field theories by calculating directly the effective action using the background field and covariant-derivative expansion technique. I use this method to determine uniquely the induced Chern-Simons term from the a Lorentz and CPT violating term in fermion QED Lagrangian. The outstanding am

C. A. Dominguez, M. Loewe

By using a thermal Finite Energy QCD Sum Rule, we are able to establish the temperature dependence of the $g_{ωρπ}(T)$ strong coupling. It turns out that this coupling decreases as a function of temperature, vanishing at the critical temperature. This corresponds to a possible deconfining phenomenological signal. This result, together with the Vector Meson D

Marek Zielinski

We present a study of high-$p_T$ photon and pion production in hadronic interactions, focusing on a comparison of the yields with expectations from next-to-leading order perturbative QCD (NLO pQCD). We examine the impact of phenomenological models of $k_T$ smearing (which approximate effects of additional soft-gluon emission) on absolute predictions for phot

Deirdre Black, Amir H. Fariborz, Joseph Schechter

We first review the work of the Syracuse group, which uses an effective chiral Lagrangian approach, on meson-meson scattering. An illustration providing evidence for the existence of a strange scalar resonance of mass around 900 MeV is given. An attempt to fit this $κ(900)$ together with a similarly obtained $σ(560)$ and the well known $a_0(980)$ and $f_0(98

H. -J. Pirner

We study the dynamics of Wilson lines near the light cone in QCD. Lattice simulations of the near light cone Hamiltonian in SU(2) show that the correlation mass at strong coupling vanishes at intermediate coupling, which signals a continuum transition on the light cone. We point out the possible relevance of this mass for high energy scattering.

Urs Achim Wiedemann

We study the gluon radiation spectrum off a hard in-medium produced quark in the multiple soft rescattering formalism of Baier-Dokshitzer-Mueller-Peigne-Schiff, and of Zakharov (BDMPS-Z). Its dependence on the quark and gluon energy, on the gluon transverse momentum, on the in-medium pathlength and on the rescattering properties of the nuclear medium is anal

The BABAR Collaboration, B. Aubert

Using a sample of 3.7 x 10^{6} Y(4S) --> B-anti-B events collected with the BABAR detector at the PEP-II storage ring, we search for the electroweak penguin decays B^+ --> K^+e^+e^-, B^+ --> K^+mu^+mu^-, B^0 --> K^{*0)e^+e^-, and B^0 --> K^{*0)mu^+mu^-. We observe no significant signals for these modes and set preliminary 90% C.L. upper limits of B(B^+ --> K

The BABAR Collaboration, B. Aubert

We present preliminary results of a search for several exclusive charmless hadronic B decays from electron-positron annihilation data collected by the BABAR detector near the Y(4S) resonance. These include three-body decay modes with final states h^{+/-}h^{-/+}h^{+/-} and h^{+/-}h^{-/+}pi^0, and quasi-two-body decay modes with final states X^0 h and X^0 K0S,

The BABAR Collaboration, B. Aubert

We present preliminary results of a search for charmless two-body B decays to charged pions and kaons using data collected by the BABAR detector at the Stanford Linear Accelerator Center's PEP-II storage ring. In a sample of 8.8 million produced B-anti-B pairs we measure the branching fractions B(B^0 --> pi^+pi^-) = (9.3^{+2.6}_{-2.3}^{+1.2}_{-1.4}) x 10

The BABAR Collaboration, B. Aubert

Electron-positron annihilation data collected by the BABAR detector near the Y(4S) resonance are used to study the inclusive decay of B mesons to D_S^(+/-) and D_S^(*+/-) mesons, where the D_S^(+/-) is reconstructed using the decay D_S^(+/-) --> phi pi^(+/-). The production fraction of inclusive D_S^((*)+/-) and the corresponding momentum spectra have been d

The BABAR Collaboration, B. Aubert

The b --> s gamma transition proceeds by a loop ``penguin'' diagram. It may be used to measure precisely the couplings of the top quark and to search for the effects of any new particles appearing in the loop. We present a preliminary measurement of the branching fraction of the exclusive decay, B^0 --> K^{*0}gamma. We use 8.6 x 10^6 B-anti-B decays

The BABAR Collaboration, B. Aubert

A preliminary study of time dependence of B^0-anti-B^0 oscillations using dilepton events is presented. The flavor of the B meson is determined by the charge sign of the lepton. To separate signal leptons from cascade and fake leptons we have used a method which combines several discriminating variables in a neural network. The time evolution of the oscillat

The BABAR Collaboration, B. Aubert

The two B^0 decay processes B^0 --> D^{*-}pi^+ and B^0 --> D^{*-}l^+nu have been studied by means of a partial reconstruction technique using a data sample collected with the BABAR detector at the PEP-II storage ring. To increase statistics, only the soft pi^- from the decay D^{*-} --> pi^-D^0 was used in association with either an oppositely-charged high-mo

The BABAR Collaboration, B. Aubert

B^0-anti-B^0 flavor oscillations are studied in e^+e^- annihilation data collected with the BABAR detector at center-of-mass energies near the Y(4S) resonance. One B is reconstructed in a hadronic or semileptonic decay mode, and the flavor of the other B in the event is determined with a tagging algorithm that exploits the relation between the flavor of the

The BABAR Collaboration, B. Aubert

Using 5.2 fb-1 of e^+e^- annihilation data recorded with the BABAR detector at the PEP-II storage ring while operating on the Y(4S) resonance, a sample of fully reconstructed B^0 decays in the hadronic modes B^0 -> D^{*-}pi^+ and B^0 -> D^{*-}rho^+ have been reconstructed. In this paper, a study of these events is reported, including preliminary measurements

The BABAR Collaboration, B. Aubert

We report on exclusive decays of B mesons into final states containing charmonium using data collected with the BABAR detector at the PEP-II storage rings. The charmonium states considered here are J/psi, psi(2S), and chi_C1. Branching fractions for several exclusive final states, a measurement of the decay amplitudes for the B0 --> J/psi K* decay, and measu

The BABAR Collaboration, B. Aubert

We reconstruct the charmonium mesons J/psi, psi(2S) and chi_C1 using a sample of 8.46 x 10^6 B-anti-B events collected by the BABAR detector operating at e^+e^- center of mass energies near the Y(4S) resonance. By measuring rates relative to the branching fraction of the J/psi, we obtain preliminary inclusive B branching fractions of (0.25+/-0.02+/-0.02)% to

The BABAR Collaboration, B. Aubert

We present a preliminary measurement of time-dependent CP-violating asymmetries in B0 -> J/psi K0S and B0 -> psi(2S) K0S decays recorded by the BABAR detector at the PEP-II asymmetric-energy B Factory at SLAC. The data sample consists of 9.0 fb-1 collected at the Y(4S) resonance and 0.8 fb-1 off-resonance. One of the neutral B mesons, produced in pairs at th

Taku Ishida

The first results of the K2K(KEK to Kamioka) long-baseline neutrino oscillation experiment are presented in this talk. In 1999 7.2x10^18 protons on target were delivered to the experiment. During this period of running there were 3 events fully contained in the Super-Kamiokande inner detector fiducial area which occurred during the beam spill timing window.

Scott A. Hughes

In its final year of inspiral, a stellar mass ($1 - 10 M_\odot$) body orbits a massive ($10^5 - 10^7 M_\odot$) compact object about $10^5$ times, spiralling from several Schwarzschild radii to the last stable orbit. These orbits are deep in the massive object's strong field, so the gravitational waves that they produce probe the strong field nature of th

V. Ferrari, K. D. Kokkotas

The excitation of the axial quasi-normal modes of a relativistic star by scattered particles is studied by evolving the time dependent perturbation equations. This work is the first step towards the understanding of more complicated perturbative processes, like the capture or the scattering of particles by rotating stars. In addition, it may serve as a test

Miles Osborne

We argue that some of the computational complexity associated with estimation of stochastic attribute-value grammars can be reduced by training upon an informative subset of the full training set. Results using the parsed Wall Street Journal corpus show that in some circumstances, it is possible to obtain better estimation results using an informative sample

Ion Androutsopoulos, Robert Dale

Selectional restrictions are semantic sortal constraints imposed on the participants of linguistic constructions to capture contextually-dependent constraints on interpretation. Despite their limitations, selectional restrictions have proven very useful in natural language applications, where they have been used frequently in word sense disambiguation, synta

M. D. Lumsden, B. C. Sales, D. Mandrus, S. E. Nagler

Magnetization and neutron diffraction measurements indicate long-range antiferromagnetic ordering below TN=4 K in the 2D, S=1/2 Heisenberg antiferromagnet K2V3O8. The ordered state exhibits ``weak ferromagnetism'' and novel, field-induced spin reorientations. These experimental observations are well described by a classical, two-spin Heisenberg model

C. J. Olson, C. Reichhardt, R. T. Scalettar, G. T. Zimanyi

Using numerical simulations of magnetically interacting vortices in disordered layered superconductors we obtain the static vortex phase diagram as a function of magnetic field and temperature. For increasing field or temperature, we find a transition from ordered straight vortices to disordered decoupled vortices. This transition is associated with a peak e

H. V. Kruis, I. Martin, A. V. Balatsky

We predict a resonance impurity state generated by the substitution of one Cu atom with a nonmagnetic atom, such as Zn, in the pseudogap state of a high-T_c superconductor. The precise microscopic origin of the pseudogap is not important for this state to be formed, in particular this resonance will be present even in the absence of superconducting fluctuati

E. S. Choi, J. S. Brooks, S. Y. Han, L. Balicas

We have employed uniaxial stress along the principal axes of the quasi-two dimensional organic superconductor $κ$--(BEDT-TTF)$_{2}$Cu(SCN)$_{2}$. The lattice anisotropy is thereby altered, with corresponding changes in the intermolecular transfer energies. The effect of uniaxial stress on the superconducting transition temperature $T_{c}$ and critical field

D. R. Hamann

A globally-adaptive curvilinear coordinate formalism is shown to be easily convertible to a class of curvilinear transformations locally optimized around atom sites by a few parameters. Parameter transferability is established for a demanding test case, and the results of the two methods are shown to be comparable. Computational efficiencies realized in the

A. Barhdadi, G. Cohen-Solal

A simplified theoretical model for the constant-magnitude steady-state surface photovoltage (SPV) technique is developed. Emphasis is placed on the determination of the minority carrier diffusion length L in the particular case for which the sample thickness is quite lower than the true value of L. The model is derived from the theoretical basis with the ass

E. Bielejec, J. Ruan, Wenhao Wu

We report on the tunneling density of states (DOS) in ultrathin and strongly disordered Be films quench-condensed at 20 K. Above 5 K, the DOS shows the well-known logarithmic anomaly at the Fermi level. Only in a narrow temperature range near 2 K is the DOS linearly dependent on energy, as predicted by Efros and Shklovskii. However, both the zero-bias conduc

Ch. Wälti, H. R. Ott, Z. Fisk, J. L. Smith

Reply to cond-mat/0007006 by Gloos

J. Eroles, G. Ortiz, A. V. Balatsky, A. R. Bishop

We investigate the electronic dynamics in the underdoped cuprates focusing on the effects of one-dimensional charge stripes. We address recent experimental Angular-Resolved Photoemission Spectra results on (La$_{1.28}$Nd$_{0.6}$Sr$_{0.12}$)CuO$_4$. We find that various inhomogeneous models can account for the distribution of quasiparticle weights close to mo

S. Koval, J. Kohanoff, R. L. Migoni, A. Bussmann-Holder

The origin of ferroelectricity in KH_2PO_4 (KDP) is studied by first-principles electronic structure calculations. In the low-temperature phase, the collective off-center ordering of the protons is accompanied by an electronic charge delocalization from the "near" and localization at the "far" oxygen within the O-H...O bonds. Electrostatic fo

Hendrik Meyer, Oliver Biermann, Roland Faller, Dirk Reith

We implemented a coarse-graining procedure to construct mesoscopic models of complex molecules. The final aim is to obtain better results on properties depending on slow modes of the molecules. Therefore the number of particles considered in molecular dynamics simulations is reduced while conserving as many properties of the original substance as possible. W

Dirk Reith, Hendrik Meyer, Florian Mueller-Plathe

We develop coarse-grained force fields for poly (vinyl alcohol) and poly (acrylic acid) oligomers. In both cases, one monomer is mapped onto a coarse-grained bead. The new force fields are designed to match structural properties such as radial distribution functions of various kinds derived by atomistic simulations of these polymers. The mapping is therefore

G. Caldarelli, A. Capocci

The stable marriage problem has been introduced in order to describe a complex system where individuals attempt to optimise their own satisfaction, subject to mutually conflicting constraints. Due to the potential large applicability of such model to describe all the situation where different objects has to be matched pairwise, the statistical properties of

J. Schiøtz, T. Leffers, B. N. Singh

Recent experiments by Kiritani et al. have revealed a surprisingly high rate of vacancy production during high-speed deformation of thin foils of fcc metals. Virtually no dislocations are seen after the deformation. This is interpreted as evidence for a dislocation-free deformation mechanism at very high strain rates. We have used molecular-dynamics simulati

Per Lyngs Hansen, Rudi Podgornik, V. Adrian Parsegian

The osmotic coefficient of B-DNA in water may, in moderately dilute solutions, deviate as much as 100 % from predictions based on a simple 'counterion condensation' theory. We determine the results for osmotic properties via a cell model description of the ionic atmosphere near a cylindrical polyelectrolyte. The cell model predictions for the osmotic

R. Piasecki, A. Czainski

In this Rapid Research Note the application of recently introduced [Physica A 277 (2000) 157] entropic measure S_Delta of spatial disorder for systems of finite-sized objects is presented. In the thermodynamic limit the critical behaviour of coarsened lattice model of random two-phase systems is illustrated for certain grain size distributions (GSDs) and cho

Markus Kindermann, Christof Wetterich

The phase transitions of liquid Helium 3 are described by truncations of an exact nonperturbative renormalization group equation. The location of the first order transition lines and the jump in the order parameter are computed quantitatively. At the triple point we find indications for partially universal behaviour. We suggest experiments that could help to

Hideto Fukazawa, Yoshiteru Maeno

We have grown single crystals of electron doping system Ca2-xLaxRuO4 (0.00 <= x <= 0.20) by a floating zone method. The first order metal/non-metal transition and canted antiferromagnetic ordering occur for 0.00 < x < 0.15, similar to those in the bandwidth controlled system Ca2-xSrxRuO4 (CSRO). However, comparing with CSRO, we found a rather different metal

T. Roessler, J. B. Page

Using an efficient optimal control scheme to determine the exciting fields, we theoretically demonstrate the optical creation of vibrational intrinsic localized modes (ILMs) in anharmonic perfect lattices with realistic interatomic potentials. For systems with finite size, we show that ILMs can be excited directly by applying a sequence of femtosecond visibl

Nobuhisa Okazaki, Kiyomi Okamoto, Toru Sakai

We study the magnetization process of the $S=1/2$ antiferromagnetic spin ladder in the presence of the second and the third-neighbor couplings which lead to frustration with the typical nearest-neighbor coupling. We use degenerate perturbation theory and level spectroscopy analysis of the numerical diagonalization data of the Hamiltonian for finite systems.

Belal E. Baaquie, L. C. Kwek, M. Srikant

We apply path integration techniques to obtain option pricing with stochastic volatility using a generalized Black-Scholes equation known as the Merton and Garman equation. We numerically simulate the option prices using the technique of path integration. Using market data, we determine the parameters of the model. It is found that the market chooses a speci

G. Baskaran

We critically look at Senthil Fisher constructions of quantum number fractionization in cuprates. The first construction, while mathematically correct is of limited relevance to cuprates. The second one has a missing local U(1) symmetry. Once this aspect is repaired, it reveals itself as the U(1) RVB gauge theory construction of quantum number fractionizatio

C. Gilles, P. Bonville, K. K. W. Wong, S. Mann

The magnetic behaviour of nanoparticles of antiferromagnetic ferritin has been investigated by 57Fe Mossbauer absorption spectroscopy and magnetisation measurements, in the temperature range 2.5K-250K and with magnetic fields up to 7T. Samples containing nanoparticles with an average number of Fe atoms ranging from 400 to 2500 were studied. The value of the

Fridolin Weber

It is generally agreed on that the tremendous densities reached in the centers of neutron stars provide a high-pressure environment in which numerous novel particles processes are likely to compete with each other. These processes range from the generation of hyperons to quark deconfinement to the formation of kaon condensates and H-matter. There are theoret

J. A. Eisner, S. R. Kulkarni

The technique of radial velocity (RV) has produced spectacular discoveries of short-period Jovian mass objects around a fraction (5 to 10%) of nearby G stars. Although we expect Jovian planets to be located in long-period orbits of decades or longer (if our solar system is any guide), detecting such planets with RV technique is difficult due to smaller veloc

Geraint F. Lewis, Scott C. Chapman

We present the first submillimetre observations of the z=2.36 broad absorption line system Hawaii 167. Our observations confirm the hypothesis that Hawaii 167 contains a massive quantity of dust, the optical depth of which is sufficient to completely extinguish our ultraviolet view of a central, buried quasar. Hawaii~167&#39;s submillimetre luminosity and as

A. Pasquali, M. S. Brigas, G. De Marchi

We present NICMOS NIC3 observations of the Galactic globular cluster NGC 288, taken South - East at 2.4 times the cluster&#39;s half-light radius in the J and H bands. We have detected the cluster main sequence down to J~25 and H~24. The corresponding luminosity function covers the range 3<M_H<9 and peaks at M_H~6.8. The theoretical tracks of Baraffe et al.

Julian H. Krolik

Numerous variations have been proposed on the original suggestion by Blandford and Znajek that magnetic fields could be used to extract rotational energy from black holes. A new categorization of these variations is proposed so that they may be considered in a systematic way. &#34;Black hole spindown&#34; is defined more precisely, distinguishing decrease in

R. Launhardt

The Bok globule CB230 (L1177) contains an active, low-mass star-forming core which is associated with a double NIR reflection nebula, a collimated bipolar molecular outflow, and strong mm continuum emission. The morphology of the NIR nebula suggests the presence of a deeply embedded, wide binary protostellar system. High-angular resolution observations now r

M. Simon, A. Dutrey, S. Guilloteau

We have used the high sensitivity and resolution of the IRAM interferometer to produce sub-arcsecond 12CO 2-1 images of 9 protoplanetary disks surrounding T Tauri stars in the Taurus-Auriga cloud (7 singles and 2 binaries). The images demonstrate the disks are in Keplerian rotation around their central stars. Using the least square fit method described in Gu

Alexander Kusenko

At high red shift, the temperature of cosmic microwave background is sufficiently high for the ultrahigh-energy photons to pair-produce muons and pions through interactions with the background photons. At the same time, the radio background and magnetic fields are too weak to drain energy out of the electromagnetic cascade before the muons and pions are prod

A. de la Varga, D. Reimers, D. Tytler, T. Barlow

Detailed analysis of the spectral lines from two low redshift damped Lyman alpha absorbers (DLA) confirms that they are a heterogeneous population. Both systems have low metal abundances of approximately 0.05 to 0.1 solar. The abundance pattern of the DLA at z=1.15 towards HE 0515-4414 shows dust depletion comparable to that found in our Galaxy, while the sy

James Binney

An energetic argument implies that a galaxy like the Milky Way is blowing a powerful wind that carries away most of the heavy elements currently synthesized and has impacted the IGM out to at least 180 kpc. Rich clusters of galaxies appear to be closed systems in which most heavy elements are ejected from galaxies. More supernovae are required than the yield

L. Decin, C. Waelkens, K. Eriksson, B. Gustafsson

We present a detailed spectroscopic study of a sample of bright, mostly cool, stars observed with the Short-Wavelength Spectrometer (SWS) on board the Infrared Space Observatory (ISO), which enables the accurate determination of the stellar parameters of the cool giants, but also serves as a critical review of the ISO-SWS calibration.

T. Di Salvo, M. Méndez, M. van der Klis, E. Ford

We study the timing properties of the bursting atoll source 4U 1728-34 as a function of its position in the X-ray color-color diagram. In the island part of the color-color diagram (corresponding to the hardest energy spectra) the power spectrum of 4U 1728-34 shows several features such as a band-limited noise component present up to a few tens of Hz, a low

Hyun Kyu Lee, Hui-Kyung Kim

The effect of an accretion disk on the Blandford-Znajek process and the evolution of a black hole are discussed using a simplified system for the black hole - accretion disk in which the accretion rate is supposed to be dominated by the strong magnetic field on the disk. The evolutions of the mass and the angular momentum of the black hole are formulated and

P. Englmaier, D. Rigopoulou, S. Mengel

The prominent interacting galaxy pair NGC 4038/9 contains many active star-forming regions and is continuously forming new star clusters. We present a self-consistent n-body model for this system which includes an SPH gas component. The model qualitatively explains the apparent concentration of gas in the so-called overlap region between the two nuclei as a

Peter G. Jonker, Mariano Mendez, Michiel van der Klis

We report the discovery of a third kilohertz quasi-periodic oscillation (kHz QPO) in the power spectra of the low-mass X-ray binaries 4U 1608-52 (6.3 sigma), 4U 1728-34 (6.0 sigma), and 4U 1636-53 (3.7 sigma) which is present simultaneously with the previously-known kHz QPO pair. The new kHz QPO is found at a frequency that is 52.8+-0.9 Hz, 64+-2 Hz, 58.4+-1

Pierre-Alain Duc, Elias Brinks

Galactic collisions trigger a number of phenomena, such as transportation inward of gas from distances of up to kiloparsecs from the center of a galaxy to the nuclear region, fuelling a central starburst or nuclear activity. The inverse process, the ejection of material into the intergalactic medium by tidal forces, is another important aspect and can be stu

Agnieszka Janiuk, Bozena Czerny

The standard accretion discs are known to be thermally and viscously unstable over a certain range of temperatures. In the inner disc regions there may develop radiation pressure driven instability, which is possibly related to the rapid variability detected in AGNs in the UV range. In the outer disc develops the ionization instability, similar to that in th

Shigeyuki Karino, Shin&#39;ichirou Yoshida, Shijun Yoshida, Yoshiharu Eriguchi

We have developed a new numerical scheme to solve r-mode oscillations of {\it rapidly rotating polytropic stars} in Newtonian gravity. In this scheme, Euler perturbations of the density, three components of the velocity are treated as four unknown quantities together with the oscillation frequency. For the basic equations of oscillations, the compatibility e

Agnieszka Janiuk, Bozena Czerny, Aneta Siemiginowska

Physical mechanism responsible for high viscosity in accretion disks is still under debate. Parameterization of the viscous stress as $αP$ proved to be a successful representation of this mechanism in the outer parts of the disk, explaining the dwarf novae and X-ray novae outbursts as due to ionization instability. We show that this parameterization can be a

Changbom Park, J. Richard Gott, Y. J. Choi

We have studied topology of the distribution of the high redshift galaxies identified in the Hubble Deep Field (HDF) North and South. The two-dimensional genus is measured from the projected distributions of the HDF galaxies at angular scales from $3.8&#39;&#39;$ to $ 6.1&#39;&#39;$. We have also divided the samples into three redshift slices with roughly eq

S. Behar, M. Carmeli

A general-relativistic theory of cosmology, the dynamical variables of which are those of Hubble&#39;s, namely distances and redshifts, is presented. The theory describes the universe as having a three-phase evolution with a decelerating expansion followed by a constant and an accelerating expansion, and it predicts that the universe is now in the latter pha

D. Rusin, Max Tegmark

We investigate the frequency of two- and four-image gravitational lens systems in the Jodrell-VLA Astrometric Survey (JVAS) and Cosmic Lens All-Sky Survey (CLASS), and the possible implications for dark matter halo properties. A simple lensing statistics model, which describes lens galaxies as singular isothermal ellipsoids with a projected axis ratio distri

Andrew Chamblin, Harvey S. Reall, Hisa-aki Shinkai, Tetsuya Shiromizu

We study charged brane-world black holes in the model of Randall and Sundrum in which our universe is viewed as a domain wall in asymptotically anti-de Sitter space. Such black holes can carry two types of ``charge&#39;&#39;, one arising from the bulk Weyl tensor and one from a gauge field trapped on the wall. We use a combination of analytical and numerical

Tarek Ibrahim, Pran Nath

One loop contributions to the Higgs boson masses and mixings from the chargino sector consisting of the chargino, the W, and the charged Higgs boson ($χ^+-W-H^+$) exchanges and including the effects of large CP violating phases are computed. It is found that the chargino sector makes a large contribution to the mixings of the CP even and the CP odd Higgs sec

R. N. Mohapatra

A brief overview of the important theoretical issues in neutrino physics is presented and some of the current ideas for addressing them in the framework of the seesaw mechanism of neutrino masses are discussed. Among the topics discussed are ways to understand maximal mixing pattern among the three neutrino species, both uni-maximal and bimaximal kinds. Cons

F. M. L. Almeida, Y. A. Coutinho, J. A. Martins Simoes, M. A. B. do Vale

New heavy Majorana and Dirac neutrinos production at future electron-muon colliders are investigated. The production of a single heavy neutrino is shown to be more relevant than pair production when comparing cross sections and neutrino mass ranges. The process $e^\pm μ^\mp \longrightarrow ν \ell^{\pm} W^{\mp}$ is studied including on-shell and off-shell hea

A. Decourchelle, D. C. Ellison, J. Ballet

We have developed a simple model to investigate the modifications of the hydrodynamics and non-equilibrium ionization X-ray emission in young supernova remnants due to nonlinear particle acceleration. In nonlinear, diffusive shock acceleration, the heating of the gas to X-ray emitting temperatures is strongly coupled to the acceleration of cosmic ray ions. I

Matthias Klein, Raul Rabadan

We discuss compact four-dimensional Z_N x Z_M type IIB orientifolds. We take a systematic approach to classify the possible models and construct them explicitely. The supersymmetric orientifolds of this type have already been constructed some time ago. We find that there exist several consistent orientifolds for each of the discrete groups Z_2 x Z_2, Z_2 x Z

Charles Livingston

In answer to a question of Long, Flapan constructed an example of a prime strongly positive amphicheiral knot that is not slice. Long had proved that all such knots are algebraically slice. Here we show that the concordance group of algebraically slice knots contains an infinitely generated free subgroup that is generated by prime strongly positive amphichei

H. Ness, S. A. Shevlin, A. J. Fisher

We present a technique to calculate the transport properties through one-dimensional models of molecular wires. The calculations include inelastic electron scattering due to electron-lattice interaction. The coupling between the electron and the lattice is crucial to determine the transport properties in one-dimensional systems subject to Peierls transition

Mohsen Alishahiha, Yaron Oz

In the first part of this letter, we analyse the supergravity dual descriptions of six-dimensional field theories realized on the worldvolume of (p,q) five-branes (OD5 theory). We show that in order for the low-energy gauge theory description to be valid the theta parameter must be rational. Irrational values of theta require a strongly coupled string descri

M. Post, U. Mosel

We estimate the resonance coupling strength $f_{RNω}$ and $f_{RNρ}$ from a Vector Meson Dominance (VMD) analysis. The isoscalar and isovector part of the photon coupling are obtained separately from helicity amplitudes. The reliability of this approach is tested by comparing VMD predictions for $f_{RNρ}$ with values obtained from fitting the hadronic decay w

Utpal Chattopadhyay, Amitava Datta, Anindya Datta, Aseshkrishna Datta

Thanks to the focus point phenomenon, it is quite {\it natural} for the minimal SUGRA model to have a large soft scalar mass m_0 > 1 TeV. A distinctive feature of this model is an inverted hierarchy, where the lighter stop has a significantly smaller mass than the other squarks and sleptons. Consequently, the gluino is predicted to decay dominantly via stop

Eric R. Sharpe

In this article we shall outline a derivation of the analogue of discrete torsion for the M-theory three-form potential. We find that some of the differences between orbifold group actions on the C field are classified by H^3(G, U(1)). We also compute the phases that the low-energy effective action of a membrane on T^3 would see in the analogue of a twisted

Hanno Sahlmann, Rainer Verch

Some years ago, Radzikowski has found a characterization of Hadamard states for scalar quantum fields on a four-dimensional globally hyperbolic spacetime in terms of a specific form of the wavefront set of their two-point functions (termed `wavefront set spectrum condition&#39;), thereby initiating a major progress in the understanding of Hadamard states and

B. Chakraborty, Subir Ghosh, R. P. Malik

The $CP^1$ model with Hopf interaction is quantised following the Batalin-Tyutin (BT) prescription. In this scheme, extra BT fields are introduced which allow for the existence of only commuting first-class constraints. Explicit expression for the quantum correction to the expectation value of the energy density and angular momentum in the physical sector of

A. T. Banin, I. L. Buchbinder, N. G. Pletnev

We study one-loop effective action of hypermultiplet theory coupled to external N=2 vector multiplet. We formulate this theory in N=1 superspace and develop a general approach to constructing derivative expansion of the effective action based on an operator symbol technique adopted to N=1 supersymmetric field models. The approach under consideration allows t

J. S. Høye, I. Brevik, J. B. Aarseth

The Casimir free energy for a system of two dielectric concentric nonmagnetic spherical bodies is calculated with use of a quantum statistical mechanical method, at arbitrary temperature. By means of this rather novel method, which turns out to be quite powerful (we have shown this to be true in other situations also), we consider first an explicit evaluatio

S. Moghimi-Araghi, S. Rouhani, M. Saadat

We study logarithmic conformal field theories (LCFTs) through the introduction of nilpotent conformal weights. Using this device, we derive the properties of LCFT&#39;s such as the transformation laws, singular vectors and the structure of correlation functions. We discuss the emergence of an extra energy momentum tensor, which is the logarithmic partner of

K. Tsushima, A. Sibirtsev, A. W. Thomas

Results for the $\pi + N \to \Lambda, \Sigma + K$ reactions in nuclear matter of Ref. nucl-th/0004011 are presented. To evaluate the in-medium modification of the reaction amplitude as a function of the baryonic density we introduce relativistic, mean-field potentials for the initial, final and intermediate mesonic and baryonic states in the resonance model.

Ibrahim Fatkullin, Konstantin Kladko, Igor Mitkov, A. R. Bishop

We study thermal relaxation in ordered arrays of coupled nonlinear elements with external driving. We find, that our model exhibits dynamic self-organization manifested in a universal stretched-exponential form of relaxation. We identify two types of self-organization, cooperative and anti-cooperative, which lead to fast and slow relaxation, respectively. We

Daniel Kleppner, Roman Jackiw

On the occasion of the 100th anniversary of the birth of the quantum idea, the development, achievements, and promises of quantum mechanics are described.

Caslav Brukner, Anton Zeilinger

Motivated by Hall&#39;s recent comment in quant-ph/0007116 we point out in some detail the essence of our reasoning why we believe that Shannon&#39;s information is not an adequate choice when defining the information gain in quantum measurements as opposed to classical observations.

X. X. Yi, S. X. Yu

A method of exactly solving the master equation is presented in this letter. The explicit form of the solution is determined by the time evolution of a composite system including an auxiliary system and the open system in question. The effective Hamiltonian governing the time evolution of the composed system are derived from the master equation. Two examples