August 2002 arXiv papers — page 18

I. S. Glass, M. Schultheis

A complete sample of 174 M giants classified by Blanco (1986) and later than subtype M0 in the NGC6522 Baade's Window clear field has been investigated to establish some general properties of cool Bulge stars. Photometric information has been obtained from the MACHO database to search for variability and, where possible, to determine periods. Near- and m

Matthias Steinmetz

I review the current state of our understanding of the galaxy formation and evolution process from the modeler's perspective. With the advent of the cold dark matter model and the support of fast computers and advanced simulation techniques, there has been considerable progress in explaining the growth of structure on the largest scales and in reproducin

T. Kotani, S. Trushkin, E. K. Denissyuk, N. Kawakita

The detection of a massive jet-ejection event from SS433 with RXTE is reported. SS433 in its high state has been monitored with RXTE from 2001/11/09 (MJD = 52222) to 2001/11/25 (MJD = 52238), following a radio flare on 2001/11/02 (MJD = 52215). An irregular temporal variation with time scales of 100-1000 s appears in the light curve, and the amplitude increa

Kaspar von Braun, Mario Mateo, Kristin Chiboucas, Alex Athey

We report on photometry results of the equatorial globular clusters (GCs) M10 and M12. These two clusters are part of our sample of GCs which we are probing for the existence of photometrically varying eclipsing binary stars. During the search for binaries in M10 and M12, we discovered the signature of differential reddening across the fields of the clusters

W. N. Brandt, S. Kaspi

X-ray absorption and emission lines now serve as powerful diagnostics of the outflows from active galaxies. Detailed X-ray line studies of outflows have recently been enabled for a significant number of active galaxies via the grating spectrometers on Chandra and XMM-Newton. We will review some of the recent X-ray findings on active galaxy outflows from an o

Manasse R. Mbonye

We suggest an alternative framework for interpreting the current state of the visible universe. Our approach is based on a dynamical ``Cosmological Constant'' and the starting point is that a decaying vacuum produces matter. As we point out, such a dynamical Lambda is not incompatible with the general requirements of general relativity. By assuming i

J. Lowe, M. D. Scadron

First we extract the long-distance (LD) weak matrix element from certain data and give compatible theoretical estimates. We also link this LD scale to the single-quark-line (SQL) transition scale and then test the latter SQL scale against the decuplet weak decay amplitude ratio. Finally, we study LD decay. All of these experimental and theoretical values are

Rodolfo A. Diaz, R. Martinez, J. -Alexis Rodriguez

We constrain some lepton flavor violating vertices in the context of the two Higgs doublet model type III, assuming that the lightest scalar Higgs mass $% m_{h^{0}} $is about $115 $GeV. Specifically, based on the $g-2 $muon factor and the decay width of$ μ\to eγ$,$ $the following quite general bounds are obtained:$ 7.62\times 10^{-4}\lesssim ξ_{μτ}^{2}\lesss

S. Drozdz, J. Kwapien, F. Gruemmer, F. Ruf

Based on the tick-by-tick price changes of the companies from the U.S. and from the German stock markets over the period 1998-99 we reanalyse several characteristics established by the Boston Group for the U.S. market in the period 1994-95, which serves to verify their space and time-translational invariance. By increasing the time scales we find a significa

s Eye Collaboration

We have measured the cosmic ray spectrum above 10^17.2 eV using the two air fluorescence detectors of the High Resolution Fly's Eye observatory operating in monocular mode. We describe the detector, photo-tube and atmospheric calibrations, as well as the analysis techniques for the two detectors. We fit the spectrum to a model consisting of galactic and

Selman Akbulut

In 1987 S Cappell and J Shaneson constructed an s-cobordism H from the quaternionic 3-manifold Q to itself, and asked whether H or any of its covers are trivial product cobordism? In this paper we study H, and in particular show that its 8-fold cover is the product cobordism from S^3 to itself. We reduce the triviality of H to a question about the 3-twist sp

Nicolas Agrait, Alfredo Levy Yeyati, Jan M. van Ruitenbeek

Using remarkably simple experimental techniques it is possible to gently break a metallic contact and thus form conducting nanowires. During the last stages of the pulling a neck-shaped wire connects the two electrodes, the diameter of which is reduced to single atom upon further stretching. For some metals it is even possible to form a chain of individual a

W. Melnitchouk, A. W. Thomas

We re-examine the role of vector meson dominance in nuclear shadowing at low Q^2. We find that models which incorporate both vector meson and partonic mechanisms are consistent with both the magnitude and the Q^2 slope of the shadowing data.

Taichiro kugo, Keisuke Ohashi

An off-shell formulation of two distinct tensor multiplets,a massive tensor multiplet and a tensor gauge multiplet, is presented in superconformal tensor calculus in five-dimensional space-time. Both contain a rank 2 antisymmetric tensor field, but there is no gauge symmetry in the former, while it is a gauge field in the latter. Both multiplets commonly hav

Paula Szkody, Scott F. Anderson, Gary Schmidt, Patrick B. Hall

Two newly identified magnetic cataclysmic variables discovered in the Sloan Digital Sky Survey (SDSS), SDSSJ155331.12+551614.5 and SDSSJ132411.57+032050.5, have spectra showing highly prominent, narrow, strongly polarized cyclotron humps with amplitudes that vary on orbital periods of 4.39 and 2.6 hrs, respectively. In the former, the spacing of the humps in

Robert V. Harlander, William B. Kilgore

The production cross section for pseudo-scalar Higgs bosons at hadron colliders is computed at next-to-next-to-leading order (NNLO) in QCD. The pseudo-scalar Higgs is assumed to couple only to top quarks. The NNLO effects are evaluated using an effective lagrangian where the top quarks are integrated out. The NNLO corrections are similar in size to those fou

Silas R. Beane, Martin J. Savage

We explore the quark-mass dependence of two-nucleon systems. Allowed regions for the scattering lengths in the 1S0 and 3S1 channels as functions of the light-quark masses are determined from the current uncertainty in strong-interaction parameters that appear at next-to-leading order in the effective field theory. Where experimental constraints are absent, a

R. D. McDonald, A. -K. Klehe, J. Singleton, W. Hayes

We determine the pressure dependence of the electron-phonon coupling in $κ$-(BEDT-TTF)$_{2}$Cu(SCN)$_{2}$ by comparison of high pressure Raman scattering and high pressure infrared (IR) reflectivity measurements. The Raman active molecular vibrations of the BEDT-TTF dimers stiffen by 0.1-1 %GPa$^{-1}$. In contrast, the corresponding modes in the IR spectrum

G. de Berredo-Peixoto

We investigate circularly symmetric static solutions in three-dimensional gravity with a minimally coupled massive scalar field. We integrate numerically the field equations assuming asymptotic flatness, where black holes do not exist and a naked singularity is present. We also give a brief review on the massless cases with cosmological constant.

D. C. Roberts, K. Burnett

We propose a method to probe states in the Mott insulator regime produced from a condensate in an optical lattice. We consider a system in which we create time-dependent number fluctuations in a given site by turning off the atomic interactions and lowering the potential barriers on a nearly pure Mott state to allow the atoms to tunnel between sites. We calc

Markku P. V. Stenberg, Tero T. Heikkilä

We study differential shot noise in mesoscopic diffusive normal-superconducting (NS) heterostructures at finite voltages where nonlinear effects due to the superconducting proximity effect arise. A numerical scattering-matrix approach is adopted. Through an NS contact, we observe that the shot noise shows a reentrant dependence on voltage due to the supercon

M. Awramik, M. Czakon

The last missing correction to the muon lifetime in the Standard Model at O(alpha^2) coming from gauge and Higgs boson loops is presented. The associated contribution to the parameter Delta r in the on-shell scheme ranges from 6 times 10^{-5} to -4 times 10^{-5} for Higgs boson masses from 100 GeV to 1 TeV. This result translates into a shift of the W boson

Carl M. Bender, Dorje C. Brody, Hugh F. Jones

It is shown that the standard formulation of quantum mechanics in terms of Hermitian Hamiltonians is overly restrictive. A consistent physical theory of quantum mechanics can be built on a complex Hamiltonian that is not Hermitian but satisfies the less restrictive and more physical condition of space-time reflection symmetry (PT symmetry). Thus, there are i

Doron Cohen

Pumping of charge (Q) in a closed ring geometry is not quantized even in the strict adiabatic limit. The deviation form exact quantization can be related to the Thouless conductance. We use Kubo formalism as a starting point for the calculation of both the dissipative and the adiabatic contributions to Q. As an application we bring examples for classical dis

M. Marder

Leaves and flowers frequently have a characteristic rippling pattern at their edges. Recent experiments found similar patterns in torn plastic. These patterns can be reproduced by imposing metrics upon thin sheets. The goal of this paper is to discuss a collection of analytical and numerical results for the shape of a sheet with a non--flat metric. First, a

Daniel R. Terno

Operators that are associated with several important quantities, like angular momentum, play a double role: they are both generators of the symmetry group and ``observables.'' The analysis of different splittings of angular momentum into "spin" and "orbital" parts reveals the difference between these two roles. We also discuss a relat

A. De Martino, E. V. Votyakov, D. H. E. Gross

We study the classical Antonov problem (of retrieving the statistical equilibrium properties of a self-gravitating gas of classical particles obeying Boltzmann statistics in space and confined in a spherical box) for a rotating system. It is shown that a critical angular momentum $λ_c$ (or, in the canonical language, a critical angular velocity $ω_c$) exists

Ludwik Dabrowski, Cesare Reina

SL_q(2) at odd roots of unity q^l =1 is studied as a quantum cover of the complex rotation group SO(3,C), in terms of the associated Hopf algebras of (quantum) polynomial functions. We work out the irreducible corepresentations, the decomposition of their tensor products and a coquasitriangular structure, with the associated braiding (or statistics). As an e

Catherine Heymans, Alan Heavens

Intrinsic alignments of galaxies can mimic to an extent the effects of shear caused by weak gravitational lensing. Previous studies have shown that for shallow surveys with median redshifts z_m = 0.1, the intrinsic alignment dominates the lensing signal. For deep surveys with z_m = 1, intrinsic alignments are believed to be a significant contaminant of the l

John Cardy, Makoto Katori

We consider a generalisation of the vicious walker problem in which N random walkers in R^d are grouped into p families. Using field-theoretic renormalisation group methods we calculate the asymptotic behaviour of the probability that no pairs of walkers from different families have met up to time t. For d>2, this is constant, but for d<2 it decays as a powe

Seungwon Baek, P. Ko, Wan Young Song

We show that there are qualitative differences in correlations among $(g-2)_μ$, $B\to X_s γ$, $B \to X_{s} l^+ l^-$ and $B_s \to μ^+ μ^-$ in various SUSY breaking mediation mechanisms: minimal supergravity (mSUGRA), gauge mediation (GMSB), anomaly mediation (AMSB), gaugino mediation ($\tilde{g}$MSB), weakly and strongly interacting string theories, and $D$ b

Andrea Erdas, Marcello Lissia

We calculate the conversion rate of high-energy neutrinos propagating in constant magnetic field into an electron-W pair (nu -> W + e) from the imaginary part of the neutrino self-energy. Using the exact propagators in constant magnetic field, the neutrino self-energy has been calculated to all order in the field within the Weinberg-Salam model. We obtain a

Detlef Duerr, Sheldon Goldstein, Roderich Tumulka, Nino Zanghi

We develop a theory based on Bohmian mechanics in which particle world lines can begin and end. Such a theory provides a realist description of creation and annihilation events and thus a further step towards a &#34;beable-based&#34; formulation of quantum field theory, as opposed to the usual &#34;observable-based&#34; formulation which is plagued by the co

Anders Vestergren, Jack Lidmar, Mats Wallin

The phase transition in a model for vortex lines in high temperature superconductors with columnar defects, i.e., linearly correlated quenched random disorder, is studied with finite size scaling and Monte Carlo simulations. Previous studies of critical properties have mainly focused on the limit of strongly screened vortex line interactions. Here the opposi

T. A. Lahde

The electromagnetic E1 and M1 transitions in heavy quarkonia ($c\bar c$, $b\bar b$, $c\bar b$) and the magnetic moment of the $B_c^\pm$ are calculated within the framework of the covariant Blankenbecler-Sugar (BSLT) equation. The aim of this paper is to study the effects of two-quark exchange current operators which involve the $Q\bar Q$ interaction, that ar

S. Dickmann, P. Hawrylak

We discuss the rate of relaxation of the total spin in the two-electron droplet in the vicinity of the magnetic field driven singlet-triplet transition. The total spin relaxation is attributed to spin-orbit and electron-phonon interactions. The relaxation process is found to depend on the spin of ground and excited states. This asymmetry is used to explain p

Yosuke Imamura

We reproduce the correspondence between open string states |n> and BMN operators O_n in N=2 supersymmetric gauge theory using a worldsheet computation with the relation <B|n>=O_n, where <B| is a boundary state of D3-branes. We regard the NS ground states and their excitations with respect to a bosonic oscillator as the states |n> and obtain a chiral operator

Udo Hartmann, Frank K. Wilhelm

Solid state quantum bits are a promising candidate for the realization of a scalable quantum computer, however, they are usually strongly limited by decoherence. We consider a double quantum dot charge qubit, whose basis states are defined by the position of an additional electron in the system of two laterally coupled quantum dots. The coupling of these two

Shmuel Sternklar, Er&#39;el Granot

We investigate the spectral response of a Brillouin amplifier in the frequency regime within the SBS bandwidth. This is done by amplitude modulating the pump with a low frequency, and therefore, unlike previous studies, the spectrum of the modulated pump is, in all cases, smaller than the SBS bandwidth. We show both theoretically and experimentally that unli

C. Sauerbier

This paper considers the question of P = NP in context of the polynomial time SAT algorithm. It posits proposition dependent on existence of conjectured problem that even where the algorithm is shown to solve SAT in polynomial time it remains theoretically possible for there to yet exist a non-deterministically polynomial (NP) problem for which the algorithm

Guo-Ping Guo, Guang-Can Guo

An experimental feasible scheme is proposed to generate Greenberger-Horne-Zeilinger (GHZ) type of maximal entanglement. Distinguishing from the previous schemes, this entanglement can be chosen between either atomic ensembles (stationary qubit) or individual photons (flying qubit), according to the difference applications we desire for it. The physical requi

Jonathan L. Feng, Konstantin T. Matchev, Yael Shadmi

Recent results announced as measurements of the muon&#39;s anomalous magnetic moment are in fact measurements of the muon&#39;s anomalous spin precession frequency. This precession frequency receives contributions from both the muon&#39;s anomalous magnetic and electric dipole moments. We note that all existing data cannot resolve this ambiguity, and the cur

Ying Jun Ma, Gui Lu Long, Fu Guo Deng, Feng Li

A cooperative multi-player quantum game played by 3 and 4 players has been studied. Quantum superposed operator is introduced in this work which solves the non-zero sum difficulty in previous treatment. The role of quantum entanglement of the initial state is discussed in details.

Dorje Brody, Lane Hughston, Joanna Syroka

The energy-based stochastic extension of the Schrodinger equation is perhaps the simplest mathematically rigourous and physically plausible model for the reduction of the wave function. In this article we apply a new simulation methodology for the stochastic framework to analyse formulae for the dynamics of a particle confined to a square-well potential. We

S. A. Babichev, J. Ries, A. I. Lvovsky

We employ the quantum state of a single photon entangled with the vacuum (|1,0>-|0,1>), generated by a photon incident upon a symmetric beam splitter, to teleport single-mode quantum states of light by means of the Bennett protocol. Teleportation of coherent states results in truncation of their Fock expansion to the first two terms. We analyze the teleporte

Eric Bach, Susan Coppersmith, Marcel Paz Goldschen, Robert Joynt

In this paper we analyze the behavior of quantum random walks. In particular we present several new results for the absorption probabilities in systems with both one and two absorbing walls for the one-dimensional case. We compute these probabilites both by employing generating functions and by use of an eigenfunction approach. The generating function method

C. Ishizuka, A. Ohnishi, K. Sumiyoshi

We investigate the liquid-gas phase transition of dense matter in supernova explosion by the relativistic mean field approach and fragment based statistical model. The boiling temperature is found to be high (T_{boil} >= 0.7 MeV for rho_B >= 10^{-7} fm^{-3}), and adiabatic paths are shown to go across the boundary of coexisting region even with high entropy.

X. Jiang, R. Gilman, R. Ransome, P. Markowitz

The reaction p(e,e^{prime}pi^+)X^0 was studied with two high resolution magnetic spectrometers to search for narrow baryon resonances. A missing mass resolution of 2.0 MeV was achieved. A search for structures in the mass region of 0.97 < M_{X^0} < 1.06 GeV yielded no significant signal. The yield ratio of p(e,e^{prime}pi^+)X^0/p(e,e^{prime}pi^+)n was determ

W. Xu

A high precision measurement of the transverse spin-dependent asymmetry A_{T&#39;} in ^3 vec{He}(vec{e},e&#39;) quasielastic scattering was performed in Hall A at Jefferson Lab at values of the squared four-momentum transfer, Q^2, between 0.1 and 0.6 (GeV/c)^2. A_{T&#39;} is sensitive to the neutron magnetic form factor, G_M^n. Values of G_M^n at Q^2 = 0.1 a

Luca Salasnich

The Bose-Einstein condensate (BEC) of a dilute gas of bosons is well described by the three-dimensional Gross-Pitaevskii equation (3D GPE), that is a nonlinear Schrodinger equation. By imposing a transverse confinement the BEC can travel only in the cylindrical axial direction. We show that in this case the BEC with attractive interaction admits a 3D bright

Junjiro Noguchi, Joerg Winkelmann

A uniform bound of intersection multiplicities of curves and divisors on abelian varieties is proved by algebraic geometric methods. It extends and improves a result obtained by A. Buium with a different method based on Kolchin&#39;s differential algebra. The problem is modeled after the abc-Conjecture of Masser-Oesterle for abelian varieties over the functi

Arvind Rajaraman

We construct supergravity solutions for D-branes in nontrivial flux backgrounds. We revisit the issue of charge quantization in this framework, and show that in these backgrounds, charge need not be quantized. We also show in a particular example that the semiclassical description of branes produces integral charges.

O. A. Battistel, G. Dallabona

The origin of the radiatively induced Lorentz and CPT violations, in perturbative evaluations, of an extended version of QED, is investigated. Using a very general calculational method, concerning the manipulations and calculations involving divergent amplitudes, we clearly identify the possible sources of contributions for the violating terms. We show that

M. A. Grebeniuk, V. D. Ivashchuk, V. N. Melnikov

Black p-brane solutions for a wide class of intersection rules and Ricci-flat ``internal&#39;&#39; spaces are considered. They are defined up to moduli functions H_s obeying non-linear differential equations with certain boundary conditions imposed. A new solution with intersections corresponding to the Lie algebra A_3 is obtained. The functions H_1, H_2 and

Edi Gava, K. S. Narain

We study the duality between IIB string theory on a pp-wave background, arising as a Penrose limit of the AdS_3 times S^3 times M, where M is T^4 (or K3), and the 2D CFT which is given by the N=(4,4) orbifold (M)^N/S_N, resolved by a blowing-up mode. After analizying the action of the supercharges on both sides, we establish a correspondence between the stat

Parampreet Singh, Naresh Dadhich

We study the system of Schwarzschild anti de Sitter (S-AdS) bulk and FRW brane for localization of gravity; i.e. zero mass gravitons having ground state on the brane, and thereby recovering the Einstein gravity with high energy correction. It has been known that gravity is not localized on AdS brane with AdS bulk. We prove the general result that gravity is

N. Kidonakis, E. Laenen, S. Moch, R. Vogt

We describe calculations of b b-bar production to next-to-next-to-leading order (NNLO) and next-to-next-to-leading logarithm (NNLL) near threshold in pp interactions. Our calculations are in good agreement with the b b-bar total cross section measured by HERA-B.

Charalampos Anastasiou, Kirill Melnikov

We compute the total cross-section for direct production of the pseudoscalar Higgs boson in hadron collisions at next-to-next-to-leading order (NNLO) in perturbative QCD. The O(alpha_s^2) QCD corrections increase the NLO production cross-section by approximately 20-30 per cent.

Aida X. El-Khadra, Michael Luke

We review the current status of determinations of the b-quark mass, m_b. We describe the theoretical tools required for determining m_b, with particular emphasis on effective field theories both in the continuum and on the lattice. We present several definitions of m_b and highlight their advantages and disadvantages. Finally, we discuss the determinations o

John Ellis

On the occasion of the Tenth Conference on String Phenomenology in 2011, I review the dramatic progress since 2002 in experimental tests of fundamental theoretical ideas. These include the discovery of (probably fermionic) extra dimensions at the LHC, the discovery of dark matter particles, observations of charged-lepton flavour violation, the debut of quant

S. V. S. Sastry

The photon emission rates from the quark gluon plasma have been studied considering LPM suppression effects. The integral equation for the transverse vector function (f(p)) that consists of multiple scattering effects has been solved using self-consistent iterations method. Empirical fits to the peak positions of the distributions from iteration method have

H. E. Jackson

HERMES is a second generation experiment to study the spin structure of the nucleon, in which measurements of the spin dependent properties of semi-inclusive deep-inelastic lepton scattering are emphasized. Data have been accumulated for semi-inclusive pion, kaon, and proton double-spin asymmetries, as well as for high-p_T hadron pairs, and single-spin azimu

The SELEX Collaboration, M. Mattson

We observe a signal for the doubly charmed baryon Xi_cc^+ in the charged decay mode Xi_cc^+ --> Lambda_c^+ K- pi+ in data from SELEX, the charm hadro-production experiment at Fermilab. We observe an excess of 15.9 events over an expected background of 6.1 +/- 0.5 events, a statistical significance of 6.3sigma. The observed mass of this state is (3519 +/- 1)

A. Kreisel

An extended study of exclusive vector meson production in e,p interactions has been performed by the H1 and the ZEUS collaborations at the HERA collider. Recent measurements are reported and discussed within the framework of the dipole model and pQCD.

Mikalai Birukou

This work analyses main features that should be present in knowledge representation. It suggests a model for representation and a way to implement this model in software. Representation takes care of both low-level sensor information and high-level concepts.

G. Kotliar, S. Y. Savrasov

We review the basic ideas of the dynamical mean field theory (DMFT) and some of the insights into the electronic structure of strongly correlated electrons obtained by this method in the context of model Hamiltonians. We then discuss the perspectives for carrying out more realistic DMFT studies of strongly correlated electron systems and we compare it with e

Carolina Brito, Igor S. Aranson, Hugues Chate

We study the disordered, multi-spiral solutions of two-dimensional homogeneous oscillatory media for parameter values at which the single spiral/vortex solution is fully stable. In the framework of the complex Ginzburg-Landau (CGLE) equation, we show that these states, heretofore believed to be static, actually evolve on ultra-slow timescales. This is achiev

A. A. Bokov, Z. -G. Ye

A monoclinic phase was recently discovered near the morphotropic phase boundary in several high-performance piezoelectric perovskite solid solutions, but its properties have not been reported. In this paper the dielectric, piezo- and ferroelectric properties of the monoclinic Pm phase in the (1-x)Pb(Mg1/3Nb2/3)O3 -xPbTiO3 perovskite system are studied. In a

B. J. LeRoy, A. C. Bleszynski, M. A. Topinka, R. M. Westervelt

We measure the energy distribution of electrons passing through a two-dimensional electron gas using a scanning probe microscope. We present direct spatial images of coherent electron wave flow from a quantum point contact formed in a GaAs/AlGaAs two-dimensional electron gas using a liquid He cooled SPM. A negative voltage is placed on the tip, which creates

Victo S. Filho, Arnaldo Gammal, Lauro Tomio

We determine the quantitative effect, in the maximum number of particles and other static observables, due to small anharmonic terms added to the confining potential of an atomic condensed system with negative two-body interaction. As an example of how a cubic or quartic anharmonic term can affect the maximum number of particles, we consider the trap paramet

P. Nordblad, A. Broddefalk, R. Mathieu, P. Blomqvist

Some physical properties of bcc Fe/V and Fe/Co (001) superlattices are reviewed. The dependence of the magnetic anisotropy on the in-plane strain introduced by the lattice mismatch between Fe and V is measured and compared to a theoretical derivation. The dependence of the magnetic anisotropy (and saturation magnetisation) on the layer thickness ratio Fe/Co

A. L. Kuzemsky

In order to account for competition and interplay of localized and itinerant magnetic behaviour in correlated many body systems with complex spectra the various types of spin-fermion models have been considered in the context of the Irreducible Green&#39;s Functions (IGF) approach. Examples are generalized d-f model and Kondo-Heisenberg model. The calculatio

A. A. Sukhanov, V. I. Omelchenko, G. A. Orlova

The temperature and field dependences of the trapped magnetic fields and of the frozen magnetoresistance of (Pb)Bi-Sr-Ca-Cu-O ceramics and Bi-based magnetron films are investigated. It is found that in the resistive transition region of granular Bi-HTSC the trapped magnetic fields become highly inhomogeneous and alternating in sign at scale of less than 50 m

Karel Vyborny, Ludvik Smrcka

Common models describing magnetotransport properties of periodically modulated two--dimensional systems often either directly start from a semiclassical approach or give results well conceivable within the semiclassical framework. Recently, magnetoresistance oscillations have been found on samples with strong unilateral modulation and short period (d=15 nm)

A. L. Kuzemsky

Some physical implications involved in a new concept, termed the &#34;quantum protectorate&#34; (QP), are developed and discussed. This is done by considering the idea of quantum protectorate in the context of quantum theory of magnetism. It is suggested that the difficulties in the formulation of quantum theory of magnetism at the microscopic level, that ar

Luca Salasnich

We analyze the periodic tunneling of a Bose-Einstein condensate in a double-well potential which has an oscillating energy barrier. We show that the dynamics of the Bose condensate critically depends on the frequency $ω$ of the oscillating energy barrier. In the regime of periodic macroscopic quantum tunneling (PMQT) with frequency $ω_J$, the population imba

A. L. Kuzemsky

The Green-function technique, termed the irreducible Green functions (IGF) method, that is a certain reformulation of the equation-of motion method for double-time temperature dependent Green functions is presented. This method was developed to overcome some ambiguities in terminating the hierarchy of the equations of motion of double-time Green functions an

S. O. Demokritov, C. Bayer, S. Poppe, M. Rickart

The manipulation of the antiferromagnetic interlayer coupling in the epitaxial Fe/Cr/Fe(001) trilayer system by moderate 5 keV He ion beam irradiation has been investigated experimentally. It is shown that even for irradiation with very low fluences (10^14 ions/cm^2) a drastic change in strength of the coupling appears. For thin Cr-spacers (below 0.6 - 0.7 n

Takehide Miyazaki, Hidefumi Hiura, Toshihiko Kanayama

We present a density-functional (DF) study of structures of Si cage clusters that encapsulate metal atoms. As a prototypical example, the case of WSi$_{n}$ clusters is shown. To obtain the low-energy clusters in efficient and unbiased ways, genetic-like geometry updates have been performed for generating inputs for subsequent local optimizations within DF ca

Amit Dutta, Diptiman Sen

We study the XYZ spin-1/2 chain placed in a magnetic field pointing along the x-axis. We use bosonization and a renormalization group analysis to show that the model has a non-trivial fixed point at a certain value of the XY anisotropy a and the magnetic field h. Hence, there is a line of critical points in the plane (a,h) on which the system is gapless, eve

Shi X. Dou, Joseph Horvat, Saeid Soltanian, Xiao L. Wang

The nano-SiC doped MgB2/Fe wires were fabricated using a powder-in-tube method and an in-situ reaction process. The depression of Tc with increasing SiC doping level remained rather small due to the counterbalanced effect of Si and C co-doping. The high level SiC co-doping allowed creation of the intra-grain defects and nano-inclusions, which act as effectiv

S. Ingvarsson, L. Ritchie, X. Y. Liu, Gang Xiao

We observe a strong correlation between magnetization relaxation and electrical resistivity in thin Permalloy (Ni$_{81}$Fe$_{19}$, ``Py&#39;&#39;) films. Electron scattering rates in the films were affected by varying film thickness and deposition conditions. This shows that the magnetization relaxation mechanism is analogous to ``bulk&#39;&#39; relaxation,

J. Cviklinski, A. R. Tajbakhsh, E. M. Terentjev

The macroscopic shape of liquid crystalline elastomers strongly depends on the order parameter of the mesogenic groups. This order can be manipulated if photoisomerisable groups, e.g. containing N=N bonds, are introduced into the material. We have explored the large photo-mechanical response of such an azobenzene-containing nematic elastomer at different tem

A. N. Salgueiro

We derive a particle number-conserving rate equation for the ground state and for the elementary excitations of a bosonic system which is in contact with a gas of a different species (sympathetic cooling). We use the Giradeau-Arnowitt method and the model derived by Lewenstein et. al. with an additional assumption: the high-excited levels thermalize much fas

Maxim M. Korshunov, Sergei G. Ovchinnikov

In present work the effective singlet-triplet model for CuO2-layer on the grounds of multiband p-d model of strongly correlated electrons is obtained. The resulting Hamiltonian has a form of generalized singlet-triplet t-t&#39;-J model for p-type superconductors and form of usual t-t&#39;-J model for n-type superconductors. In the mean field approximation in

Tod R. Lauer

Application of deconvolution algorithms to astronomical images is often limited by variations in PSF structure over the domain of the images. One major difficulty is that Fourier methods can no longer be used for fast convolutions over the entire images. However, if the PSF is modeled as a sum of orthogonal functions that are individually constant in form ov

S. G. Djorgovski, R. Brunner, A. Mahabal, R. Williams

There has been an unprecedented and continuing growth in the volume, quality, and complexity of astronomical data sets over the past few years, mainly through large digital sky surveys. Virtual Observatory (VO) concept represents a scientific and technological framework needed to cope with this data flood. We review some of the applied statistics and computi

Susan R. Trammell, Robert W. Goodrich

We present narrow-band H-alpha, [S II], and [O I] Hubble Space Telescope images of the young planetary nebula GL 618. This object is a compact, bipolar nebula that is currently undergoing the transition from asymptotic giant branch star to planetary nebula. Our images confirm the presence of at least three highly collimated outflows emanating from the centra

Igor V. Igumenshchev

Convection-dominated accretion flow (CDAF) is a promising model to explain underluminous accreting black holes in X-ray binaries and galactic nuclei. I discuss effects of angular momentum transport in viscous hydrodynamical and MHD CDAFs. In hydrodynamical CDAFs, convection transports angular momentum inward, and this together with outward convection transpo

S. D. Hornstein, A. M. Ghez, A. Tanner, M. Morris

The recent detection of a 3-hr X-ray flare by the Chandra Observatory has raised the possibility of enhanced emission over a broad range of wavelengths from Sgr A*, the suspected 2.6 x 10^6 solar mass black hole at the Galactic Center, during a flaring event. We have, therefore, reconstructed 3-hr data sets from 2 micron speckle and adaptive optics images (t

M. Boettcher, J. Chiang

We are presenting a detailed parameter study of the time-dependent electron injection and kinematics and the self-consistent radiation transport in jets of intermediate and low-frequency peaked BL Lac objects. Using a time-dependent, combined synchrotron-self-Compton and external-Compton jet model, we study the influence of variations of several essential mo

T. Shanks, P. D. Allen, F. Hoyle, N. R. Tanvir

We first discuss why the uncomfortable fine-tuning of the parameters of the Lambda-CDM cosmological model provides continuing, strong motivation to investigate Hubble&#39;s Constant. Then we review evidence from the HST Key Project that there is a significant scale error between raw Cepheid and Tully-Fisher distances. An analysis of mainly HST Distance Scale

M. Lopez-Corredoira, A. Cabrera-Lavers, F. Garzon, P. L. Hammersley

We have pursued two different methods to analyze the old stellar population near the Galactic plane, using data from the 2MASS survey. The first method is based on the isolation of the red clump giant population in the color-magnitude diagrams and the inversion of its star counts to obtain directly the density distribution along the line of sight. The second

Lung-Yih Chiang, Pavel Naselsky, Peter Coles

The identification and extraction of non-Gaussian signals is one of the main cosmological challenges facing future experimental measurements of the cosmic microwave background temperature pattern. We present a generalized statistical measure based on a novel technique representation of Fourier phases using the return map. We show that this method is both rob

Charles B. Leffert

In an apparently unexplored region of relativistic spacetime, a simple thought experiment demonstrates that conjoined Lorentz transformations predict a proper clock at rest will run backwards and that prediction violates the logical principle of causality. Shown first in a modification of the standard clock paradox thought experiment, this fault carries over

R. A. Street, D. L. Pollacco, A. Fitzsimmons, F. P. Keenan

SuperWASP is a fully robotic, ultra-wide angle survey for planetary transits. Currently under construction, it will consist of 5 cameras, each monitoring a 9.5 x 9.5 deg field of view. The Torus mount and enclosure will be fully automated and linked to a built-in weather station. We aim to begin observations at the beginning of 2003.

Shin Watanabe, Masayuki Akiyama, Yoshihiro Ueda, Kouji Ohta

We present the first results of the Chandra and optical follow-up observations of hard X-ray sources detected in the ASCA Medium Sensitivity Survey (AMSS). Optical identifications are made for five objects. Three of them show either weak or absent optical narrow emission lines and are at low redshift <z>~0.06. One of them is a broad line object at z=0.910 an

D. Mehlert, S. Noll, I. Appenzeller, R. P. Saglia

Using a sample of 57 VLT FORS spectra in the redshift range 1.37<z<3.40 (selected mainly from the FORS Deep Field survey) and a comparison sample with 36 IUE spectra of local (z ~ 0) starburst galaxies we derive CIV and SiIV equivalent width values and estimate metallicities of starburst galaxies as a function of redshift. Assuming that a calibration of the

Benoit Vandame

This paper presents some of the main aspects of the software library that has been developed for the reduction of optical and infrared images, an integral part of the end-to-end survey system being built to support public imaging surveys at ESO. Some of the highlights of the new library are: unbiased estimates of the background, critical for deep IR observat

Marcelo Castellanos, Angeles I. Diaz, Elena Terlevich

The ionising stellar populations of eleven HII regions in the spiral galaxies: NGC628, NGC925, NGC1232 and NGC1637, all of them reported to have solar or oversolar abundances according to empirical calibrations, have been analysed using stellar population synthesis models. Four of the observed regions in the sample, show features which indicate the presence