April 2000 arXiv papers — page 4

Dmitriy Boyarchenko

The main result of this paper is that every (separated) toric variety which has a semigroup structure compatible with multiplication on the underlying torus is necessarily affine. In the course of proving this statement, we also give a proof of the fact that every separated toric variety may be constructed from a certain fan in a Euclidean space. To our best

Maria Girardi

The dual of the James Tree space is asymptotically uniformly convex.

R. Kerner, B. Niemeyer

We construct the generalized version of covariant Z_3-graded differential calculus introduced by one of us (R.K.), and then extended to the case of arbitrary Z_N grading. Here our main purpose is to establish the recurrence formulae for the N-th power of covariant q-differential D_q = d_q + A and to analyze more closely the particular case of q being an Nth

Balint Toth

We prove that, with probability one, eventually there are no more than three favourite (i.e. most visited) sites of simple random walk. This partially answers a relatively long standing question of Pal Erdos and Pal Revesz.

Konrad Schmuedgen

A general approach to the well-behaved unbounded *-representations of a *-algebra X is proposed. Let B be a normed *-algebra equipped with a left action |> of X on B such that (x |> a)^+ b=a^+(x^+ |> b) for a,b\in B and x\in X. Then the pair (X,B) is called a compatible pair. For any continuous non-degenerate *-representation ρof B there exists a closed *-re

V. Abramov, R. Kerner

We investigate a particular realization of generalized q-differential calculus of exterior forms on a smooth manifold based on the assumption that the N-th power (N>2) of exterior differential is equal to zero. It implies the existence of cyclic commutation relations for the differentials of first order and their generalization for the differentials of highe

Tomek Bartoszynski

A set of reals A is called perfectly meager if A \cap P is meager in P, for every perfect set P. Marczewski asked if the product of perfectly meager sets is perfectly meager. In the paper it is shown that it is consistent that the answer to this question is positive. (It is known that it is also consistent that the answer is negative (Reclaw))

Te Sun Han

The asymptotically optimal hypothesis testing problem with the general sources as the null and alternative hypotheses is studied under exponential-type error constraints on the first kind of error probability. Our fundamental philosophy in doing so is first to convert all of the hypothesis testing problems completely to the pertinent computation problems in

Anderson Ilha, Clovis Wotzasek

It is proposed a new mechanism for the phenomenon of topological mass generation in three spacetime dimensions as the result of the interference of two opposite massless chiral modes. This mechanism, already used to produce the massive vectorial mode of the 2D Schwinger model, is here exploited to produce the gauge invariant massive mode of the Maxwell-Chern

J. Balog, P. Forgacs, L. Palla

An $S$-matrix is proposed for the two dimensional O(3) $σ$-model with a dynamical $θ$-term (axion model). Exploiting an Abelian T-duality transformation connecting the axion model to an integrable SU(2)$\times$U(1) symmetric principal $σ$-model, strong evidence is presented for the correctness of the proposed $S$-matrix by comparing the perturbatively calcul

M. D. Maia, E. M. Monte

A geometric theory of brane-worlds with large or non-compact extra dimensions is presented. It is shown that coordinate gauge independent perturbations of the brane-world correspond to the Einstein-Hilbert dynamics derived from the embeddings of the brane-world. The quantum states of a perturbation are described by Schrödinger's equation with respect to

Elizabeth H. Simmons

The origin of mass must lie in physics beyond the Standard Model. Dynamical electroweak symmetry breaking models like technicolor can generate masses for the W and Z bosons. Providing the large top quark mass and large top-bottom mass splitting while keeping rho parameter and flavor-changing neutral currents small requires new strong dynamics for the top and

A. B. Kaidalov, C. Merino, D. Pertermann

It is shown that the CKMT model for the nucleon structure function F2, taken as the initial condition for the NLO evolution equations in perturbative QCD, provides a good description of the HERA data when presented in the form of the logarithmic slopes of F2 vs x and Q2 (Caldwell-plot), in the whole available kinematic ranges. Also the results obtained for t

A. Mihara, A. A. Natale

Using the expression of the dynamical gluon mass obtained through the operator product expansion we discuss the relevance of gluon mass effects in the decays V -> hadrons (V = J/Psi, Upsilon). Relativistic and radiative corrections are also introduced to calculate alpha_s(m_c) and alpha_s(m_b) comparing them with other values available in the literature. The

J. A. M. Vermaseren, S. Moch

We show some of the mathematics that is being developed for the computation of deep inelastic structure functions to three loops. These include harmonic sums, harmonic polylogarithms and a class of difference equations that can be solved with the use of harmonic sums.

Nils Marchal, Stephane Peigne, Paul Hoyer

We extend to large transverse momentum pt an approach to quarkonium hadroproduction previously suggested for low pt. The dynamics involves a perturbative rescattering of the heavy quark pair off a comoving color field which originates from gluon radiation prior to the heavy quark production vertex. Assuming simple properties of the comoving field we find the

Debajyoti Choudhury, Dileep P. Jatkar, Uma Mahanta, Subrata Sur

We show that the Goldberger-Wise mechanism for the three 3-brane scenario proposed by Kogan et al. stabilizes the radion. We find that the system of 3-branes stabilizes in such a way that the loss in the scale factor is insignificant. That is, the negative tension brane chooses to stay close to the visible brane.

M. Nagy, M. K. Volkov, V. L. Yudichev

In a U(3)x U(3) quark chiral model of the Nambu-Jona-Lasinio type with the 't Hooft interaction, the ground scalar isoscalar mesons and a scalar glueball are described. The glueball (dilaton) is introduced into the effective meson Lagrangian written in a chirally symmetric form on the base of scale invariance. The singlet-octet mixing of scalar isoscalar

Reinhard Prix

The integrals of motion for a cylindrically symmetric stationary vortex are obtained in a covariant description of a mixture of interacting superconductors, superfluids and normal fluids. The relevant integrated stress-energy coefficients for the vortex with respect to a vortex-free reference state are calculated in the approximation of a ``stiff'',

Thibault Damour, Alexander Vilenkin

Cusps of cosmic strings emit strong beams of high-frequency gravitational waves (GW). As a consequence of these beams, the stochastic ensemble of gravitational waves generated by a cosmological network of oscillating loops is strongly non Gaussian, and includes occasional sharp bursts that stand above the rms GW background. These bursts might be detectable b

Naren Ramakrishnan

It is shown that personalization of web content can be advantageously viewed as a form of partial evaluation --- a technique well known in the programming languages community. The basic idea is to model a recommendation space as a program, then partially evaluate this program with respect to user preferences (and features) to obtain specialized content. This

David Eppstein

We describe software that searches for spaceships in Conway's Game of Life and related two-dimensional cellular automata. Our program searches through a state space related to the de Bruijn graph of the automaton, using a method that combines features of breadth first and iterative deepening search, and includes fast bit-parallel graph reachability and p

Walter Hofstetter

In this paper we introduce a new approach for calculating dynamical properties within the numerical renormalization group. It is demonstrated that the method previously used fails for the Anderson impurity in a magnetic field due to the absence of energy scale separation. The problem is solved by evaluating the Green function with respect to the reduced dens

Geza Toth, Craig S. Lent

Recent experiments have demonstrated a working cell suitable for implementing the Quantum-dot Cellular Automata (QCA) paradigm. These experiments have been performed using metal island clusters. The most promising approach to QCA operation involves quasi-adiabatically switching the cells. This has been analyzed extensively in gated semiconductor cells. Here

A. G. Galstyan, M. E. Raikh, Z. V. Vardeny

The emission spectrum of a dipole embedded in a semi-infinite photonic crystal is calculated. For simplicity we study the case in which the dielectric function is sinusoidally modulated only along the direction perpendicular to the boundary surface plane. In addition to oscillations of the emission rate with the distance of the dipole from the interface we a

S. Lefebvre, P. Wzietek, S. Brown, C. Bourbonnais

The phase diagram of the layered organic superconductor $κ$-(ET)$_{2}$Cu[N(CN)$_{2}$]Cl has been accurately measured from a combination of $^{1}$H NMR and AC susceptibility techniques under helium gas pressure. The domains of stability of antiferromagnetic and superconducting long-range orders in the pressure {\it vs} temperature plane have been determined.

D. Manske, I. Eremin, K. H. Bennemann

Using as a model the Hubbard Hamiltonian we determine various basic properties of electron-doped cuprate superconductors like ${Nd}_{2-x}{Ce}_{x}{CuO}_{4}$ and ${Pr}_{2-x}{Ce}_{x}{CuO}_{4}$ for a spin-fluctuation-induced pairing mechanism. Most importantly we find a narrow range of superconductivity and like for hole-doped cuprates $d_{x^{2}-y^{2}}$ - symmet

Behnam Farid

We consider a specific generalisation to spatial dimensions d greater than one of a formalism based upon conservation laws and the associated Ward identities, that exactly solves the one-dimensional Luttinger model, and expose its inadequacies for d > 1. We conclude that findings arrived at through application of this generalised formalism concerning systems

J. T. Devreese, S. N. Klimin, V. M. Fomin, F. Brosens

We find for the first time the ground state energy and the optical absorption spectra for N electrons (holes) interacting with each other and with the longitudinal optical (LO) phonons at an arbitrary electron-phonon coupling strength $α$ in a parabolic confinement potential. A recently developed path integral formalism for identical particles is used in ord

D. L. Feder, M. S. Pindzola, L. A. Collins, B. I. Schneider

Dark soliton states of Bose-Einstein condensates in harmonic traps are studied both analytically and computationally by the direct solution of the Gross-Pitaevskii equation in three dimensions. The ground and self-consistent excited states are found numerically by relaxation in imaginary time. The energy of a stationary soliton in a harmonic trap is shown to

Claudio Castellano, Joachim Krug

The roughness of vapor-deposited thin films can display a nonmonotonic dependence on film thickness, if the smoothening of the small-scale features of the substrate dominates over growth-induced roughening in the early stage of evolution. We present a detailed analysis of this phenomenon in the framework of the continuum theory of unstable homoepitaxy. Using

Behnam Farid

We consider the Haldane bosonisation scheme in d spatial dimensions as applied to a realistic model of interacting fermions in d=2 and unequivocally demonstrate failure of this scheme in d > 1, specifically in d=2. In addition to tracing back this failure to its origin, we show that {\sl nothing} as regards the true metallic state of the model under consider

O. Benichou, A. M. Cazabat, J. De Coninck, M. Moreau

In this paper, which completes our earlier short publication [Phys. Rev. Lett. 84, 511 (2000)], we study dynamics of a hard-core tracer particle (TP) performing a biased random walk in an adsorbed monolayer, composed of mobile hard-core particles undergoing continuous exchanges with a vapor phase. In terms of an approximate approach, based on the decoupling

R. Rajesh, Satya N. Majumdar

We calculate exactly the two point mass-mass correlations in arbitrary spatial dimensions in the aggregation model of Takayasu. In this model, masses diffuse on a lattice, coalesce upon contact and adsorb unit mass from outside at a constant rate. Our exact calculation of the variance of mass at a given site proves explicitly, without making any assumption o

Y. -J. Wang, A. A. Nersesyan

A nonperturbative analytical description of the SU(2)_1 quantum critical point in an explicitly dimerized two-leg spin-1/2 Heisenberg ladder is presented. It is shown that this criticality essentially coincides with that emerging in a weakly dimerized spin-1 chain with a small Haldane gap. The approach is based on the mapping onto an SO(3)-symmetric model of

G. Aichmayr, M. D. Martin, H. van der Meulen, C. Pascual

We investigated the carrier and light trapping in GaInAs/AlGaAs single quantum well laser structures by means of time resolved photoluminescence and Raman spectroscopy. The influence of the shape and depth of the confinement potential and of the cavity geometry was studied by using different AlGaAs/GaAs short-period superlattices as barriers. Our results sho

D. E. Steinhauer, C. P. Vlahacos, F. C. Wellstood, Steven M. Anlage

We describe the use of a near-field scanning microwave microscope to image the permittivity and tunability of bulk and thin film dielectric samples on a length scale of about 1 micron. The microscope is sensitive to the linear permittivity, as well as to nonlinear dielectric terms, which can be measured as a function of an applied electric field. We introduc

A. Mourachkine

We present a phenomenological model of high-Tc superconductivity in hole-doped cuprates: a Magnetic Coupling between Stripes (MCS) model. The MCS model is based upon experimental facts, namely, the presence of (i) stripes, (ii) spin fluctuations, and (iii) two order parameters (for pairing and long-range phase coherence) in hole-doped cuprates. We discuss al

S. N. Dorogovtsev, J. F. F. Mendes, A. N. Samukhin

We generalize the Barabási--Albert's model of growing networks accounting for initial properties of sites and find exactly the distribution of connectivities of the network $P(q)$ and the averaged connectivity $\bar{q}(s,t)$ of a site $s$ in the instant $t$ (one site is added per unit of time). At long times $P(q) \sim q^{-γ}$ at $q \to \infty$ and $\bar

S. Fujiyama, M. Takigawa, N. Motoyama, H. Eisaki

The nuclear spin-lattice relaxation rate ($1/T_{1}$) has been measured in the single crystals of hole doped two-leg ladder compounds Sr$_{14-x}$Ca$_{x}$Cu$_{24}$O$_{41}$ and in the undoped parent material La$_6$Ca$_8$Cu$_{24}$O$_{41}$. Comparison of $1/T_{1}$ at the Cu and the two distinct oxygen sites revealed that the major spectral weight of low frequency

M. E. S. Borelli, H. Kleinert, Adriaan M. J. Schakel

A stack of tensionless membranes with nonlinear curvature energy and vertical harmonic interaction is studied. At low temperatures, the system forms a lamellar phase. At a critical temperature, the stack disorders vertically in a melting-like transition.

Julien Kockelkoren, Hugues Chaté

Angelini, Pellicoro, and Stramaglia [Phys. Rev. E {\bf 60}, R5021 (1999), cond-mat/9907149] (APS) claim that the phase ordering of two-dimensional systems of sequentially-updated chaotic maps with conserved ``order parameter'' does not belong, for large regions of parameter space, to the expected universality class. We show here that these results ar

T. Winiecki, B. Jackson, J. F. McCann, C. S. Adams

Above a critical velocity, the dominant mechanism of energy transfer between a moving object and a dilute Bose-Einstein condensate is vortex formation. In this paper, we discuss the critical velocity for vortex formation and the link between vortex shedding and drag in both homogeneous and inhomogeneous condensates. We find that at supersonic velocities soun

Julien Kockelkoren, Anaël Lemaître, Hugues Chaté

The peculiar phase-ordering properties of a lattice of coupled chaotic maps studied recently (A. Lema\^ıtre & H. Chaté, {\em Phys. Rev. Lett.} {\bf 82}, 1140 (1999)) are revisited with the help of detailed investigations of interface motion. It is shown that ``normal'', curvature-driven-like domain growth is recovered at larger scales than considered

O. Entin-Wohlman, Y. Levinson, Yu. M. Galperin

The dc current induced by a coherent surface acoustic wave (SAW) of wave vector q in a ballistic channel of length L is calculated. The current contains two contributions, even and odd in q. The even current exists only in a asymmetric channel, when the electron reflection coefficients r_1 and r_2 at both channel ends are different. The direction of the even

Holger Fehske, Michael Holicki, Alexander Weiße

The interplay of charge, spin and lattice degrees of freedom is studied for quasi-one-dimensional electron and spin systems coupled to quantum phonons. Special emphasis is put on the influence of the lattice dynamics on the Peierls transition. Using exact diagonalization techniques the ground-state and spectral properties of the Holstein model of spinless fe

S. E. Skipetrov, R. Maynard

We show that intensity of a wave created by a source embedded inside a three-dimensional disordered medium exhibits a non-universal space-time correlation which depends explicitly on the short-distance properties of disorder, source size, and dynamics of disorder in the immediate neighborhood of the source. This correlation has an infinite spatial range and

Mitsuaki Takigawa, Masanori Ichioka, Kazushige Machida

The temperature and field dependences of the site-selective nuclear spin relaxation time T_1 around vortices are studied comparatively both for s-wave and d-wave superconductors, based on the microscopic Bogoliubov-de Gennes theory. Reflecting low energy electronic excitations associated with the vortex core, the site selective temperature dependences deviat

V. Avila-Reese, E. Vázquez-Semadeni

We study turbulent dissipation in the ISM and explore some implications for galaxy formation and evolution using 2D MHD numerical simulations of compressible fluids. The turbulent kinetic energy E_k is injected by stellar sources formed self-consistently in the simulation. In the ISM-like fluid, regimes of both forced and decaying turbulence coexist. In the

Carl H. Gibson, Rudolph E. Schild

We examine recent results of two kinds of microlensing experiments intended to detect galactic dark matter objects, and we suggest that the lack of short period star-microlensing events observed for stars near the Galaxy does not preclude either the ``rogue planets'' identified from quasar-microlensing by Schild 1996 as the missing-mass of a lens gal

A. C. Fabian, K. Iwasawa, C. S. Reynolds, A. J. Young

An intrinsically narrow line emitted by an accretion disk around a black hole appears broadened and skewed as a result of the Doppler effect and gravitational redshift. The fluorescent iron line in the X-ray band at 6.4-6.9keV is the strongest such line and is seen in the X-ray spectrum of many active galactic nuclei and, in particular, Seyfert galaxies. It

E. M. Schlegel, W. P. Blair, R. A. Fesen

Analysis of 80 ksec ASCA and 60 ksec ROSAT HRI observations of the face-on spiral galaxy NGC 6946 are presented. The ASCA image is the first observation of this galaxy above ~2 keV. Diffuse emission may be present in the inner ~4' extending to energies above ~2-3 keV. In the HRI data, fourteen point-like sources are detected, the brightest two being a so

K. D. Concannon, J. A. Rose, N. Caldwell

We report on the strengths of three spectral indicators - Mg_2, Hbeta, and Hn/Fe - in the integrated light of a sample of 100 field and cluster E/S0 galaxies. The measured indices are sensitive to age and/or and metallicity variations within the galaxy sample. Using linear regression analysis for data with non-uniform errors, we determine the intrinsic scatt

M. E van den Ancker, A. G. G. M. Tielens, P. R Wesselius

We present the results of ISO SWS and LWS grating scans towards the embedded Young Stellar Objects (YSOs) S106 IR and Cep A East. Emission from the pure rotational lines of H2 and the infrared fine structure lines of [C II], [O I], [S I], [Si II] and [Fe II], as well as absorption bands due to H2O, CO and CO2 ice were detected toward Cep A. In S106 we detect

James Binney

Because we know little about the Galactic force-field away from the plane, the Galactic mass distribution is very ill-determined. I show that a microlensing survey of galaxies closer than 50 Mpc would enable us to map in three dimensions the Galactic density of stellar mass, which should be strictly less than the total mass density. A lower limit can be plac

John E. Gizis, David G. Monet, I. Neill Reid, J. Davy Kirkpatrick

We have combined 2MASS and POSS II data in a search for nearby ultracool (later than M6.5) dwarfs with K_s<12. Spectroscopic follow-up observations identify 53 M7 to M9.5 dwarfs and seven L dwarfs. The observed space density is 0.0045 +- 0.0008 M8-M9.5 dwarfs per cubic parsec, without accounting for biases, consistent with a mass function that is smooth acro

Andrei M. Beloborodov

The fraction of a fireball kinetic kinetic energy that can be radiated away by internal shocks is sensitive to the amplitude of initial fluctuations in the fireball. We give a simple analytical description for dissipation of modest-amplitude fluctuations and confirm it with direct numerical simulations. At high amplitudes, the dissipation occurs in a non-lin

H. Plana, P. Amram, C. Mendes de Oliveira, C. Balkowski

We present new observations of $Hα$ emission in the Hickson Compact Group 18 (HCG 18) obtained with a scanning Fabry-Perot interferometer. The velocity field does not show motions of individual group members but, instead, a complex common velocity field for the whole group. The gas distribution is very asymmetric with clumps of maximum intensity coinciding w

P. Sikivie, W. Kinney

The late infall of cold dark matter onto an isolated galaxy such as our own produces flows with definite velocity vectors at any physical point in the galactic halo. It also produces caustics which are places where the dark matter density is very large. The outer caustics are topological spheres whereas the inner caustics are rings. The self-similar model of

J. Guy, C. Renault, F. A. Aharonian, M. Rivoal

The TeV and X-ray data obtained by the imaging Cherenkov telescope CAT and X-ray satellite BeppoSAX during the remarkable flare of Mkn 501 in April 16, 1997 are used to constrain the flux of the Cosmic Infrared Background (CIB) using different CIB models. We show that a non-negligible absorption of gamma-rays due to the CIB could take place already in the lo

Evgeny G. Berezhko, Heinrich J. Voelk

Calculations of the expected TeV $γ$-ray emission, produced by accelerated cosmic rays (CRs) in nuclear collisions, from supernova remnants evolving in a uniform interstellar medium (ISM) are presented. The aim is to study the sensitivity of $γ$-ray production to a physical parameter set. Apart from its general proportionality to N_H, it is shown that the $γ

Evgeny G. Berezhko, Heinrich J. Voelk

The contribution of the Source Cosmic Rays (SCRs), confined in Supernova Remnants, to the diffuse high energy \gr emission above 1 GeV from the Galactic disk is studied. \grs produced by the SCRs have a much harder spectrum compared with those generated by the Galactic Cosmic Rays which occupy a much larger residence volume uniformly. SCRs contribute less th

John E. Norris, Timothy C. Beers, Sean G. Ryan

We report high-resolution, high-signal-to-noise, observations of the extremely metal-poor double-lined spectroscopic binary CS 22876-032. The system has a long period : P = 424.7 $\pm$ 0.6 days. It comprises two main sequence stars having effective temperatures 6300 K and 5600 K, with a ratio of secondary to primary mass of 0.89 $\pm$ 0.04. The metallicity o

Andrea Ferrara, Max Pettini, Yuri Shchekinov

We investigate the evolution of the metallicity of the intergalactic medium (IGM) with particular emphasis on its spatial distribution. We propose that metal enrichment occurs as a two step process. First, supernova (SN) explosions eject metals into relatively small regions confined to the surroundings of star-forming galaxies. From a comprehensive treatment

Andrew Bunker, Hyron Spinrad, Daniel Stern, Rodger Thompson

In this article we investigate the morphology and stellar populations of high-redshift galaxies through multi-waveband HST imaging and ground-based spatially-resolved spectroscopy. We study the redshift evolution of galaxy morphology in the Hubble Deep Field, using the deep IDT-NICMOS near-infrared HST imaging coupled with spectroscopic and photometric redsh

A. J. S. Hamilton, Max Tegmark, Nikhil Padmanabhan

We present a state-of-the-art linear redshift distortion analysis of the recently published IRAS Point Source Catalog Redshift Survey (PSCz). The procedure involves linear compression into 4096 Karhunen-Loeve modes culled from a potential pool of about 3 x 10^5 modes, followed by quadratic compression into three separate power spectra, the galaxy-galaxy, gal

The CDF collaboration, T. Affolder

We have measured the polarization of J/Psi and Psi(2S) mesons produced in p\bar{p} collisions at \sqrt{s} = 1.8 TeV, using data collected at CDF during 1992-95. The polarization of promptly produced J/Psi [Psi(2S)] mesons is isolated from those produced in B-hadron decay, and measured over the kinematic range 4[5.5] < P_T < 20 GeV/c and |y| < 0.6. For P_T \g

HERMES Collaboration, A. Airapetian

Measurements of the cross section for exclusive virtual-photoproduction of rho^0 mesons from hydrogen are reported. The data were collected by the HERMES experiment using 27.5 GeV positrons incident on a hydrogen gas target in the HERA storage ring. The invariant mass W of the photon-nucleon system ranges from 4.0 to 6.0 GeV, while the negative squared four-

Andrew Cumming, Lars Bildsten

The rotation rates of six weakly-magnetic neutron stars accreting in low-mass X-ray binaries have most likely been measured by Type I X-ray burst observations with RXTE. The nearly coherent oscillations detected during the few seconds of thermonuclear burning are most simply understood as rotational modulation of brightness asymmetries on the neutron star su

Mark Baker

Cluster computing is not a new area of computing. It is, however, evident that there is a growing interest in its usage in all areas where applications have traditionally used parallel or distributed computing platforms. The growing interest has been fuelled in part by the availability of powerful microprocessors and high-speed networks as off-the-shelf comm

L. Ya. Glozman

The implications of chiral symmetry for the quark model are discussed. In particular its connection with the meson-baryon approach is outlined. It is stressed that in the closure approximation, where the intermediate baryon states are used instead of the original quark basis, it is imperative to take into account the whole infinite tower of the radially exci

N. Stefanakis, N. Flytzanis

Phenomenological Ginzburg-Landau theory is used to calculate the possible spontaneous vortex states that may exist at corner junctions of $d_{x^2-y^2}+ix$-wave, (where $x=s$ or $x=d_{xy}$) and s-wave superconductors. We study the magnetic flux and the critical current modulation with the junction orientation angle $θ$, the magnitude of the order parameter, a

Laurent Proville, Serge Aubry

The bound states of two electrons in the adiabatic Holstein-Hubbard model are studied numerically in one and two dimensions from the anticontinuous limit. This model involves a competition between a local electron-phonon coupling (with a classical lattice) which tends to form pairs of electrons and the repulsive Hubbard interaction $U \geq 0$ which tends to

Michael Byrne

Hubble&#39;s correlation of red-shift with distance reveals that the universe is expanding, and that spacetime curvature has increased over time. And since time and space have equal status as dimensions, an object moving through time experiences increasing spatial curvature due to expansion, just as it does when moving through space towards a massive body. S

Emmanuel Nezri, Jean Orloff

We study the link between neutrino oscillations and leptogenesis in the minimal framework assuming an SO(10) see-saw mechanism with 3 families. Dirac neutrino masses being fixed, the solar and atmospheric data then generically induce a large mass-hierarchy and a small mixing between the lightest right-handed neutrinos, which fails to produce sufficient lepto

Reimer Kuehn, Alois Würger

We investigate effects of interactions between substitutional defects on the properties of defect crystals at low temperatures, where defect motion is governed by quantum effects. Both, thermal and dynamical properties are considered. The influence of interactions on defect motion is described via a collective effect. Our treatment is semiclassical in the se

Pierre-Henri Chavanis, Clément Sire

This paper is devoted to a statistical analysis of the velocity fluctuations arising from a random distribution of point vortices in two-dimensional turbulence. Exact results are derived for the correlations in the velocities occurring at two points separated by an arbitrary distance. We find that the spatial correlation function decays extremely slowly with

Frantisek Slanina, Miroslav Kotrla

We investigate a model of evolving random network, introduced by us previously {[}{\it Phys. Rev. Lett.} {\bf 83}, 5587 (1999){]} . The model is a generalization of the Bak-Sneppen model of biological evolution, with the modification that the underlying network can evolve by adding and removing sites. The behavior and the averaged properties of the network d

Bohdan Grzadkowski, Zenro Hioki

An optimal-observable analysis of the angular and energy distributions of the leptons and bottom quarks in the process e+e- --> tt-bar --> l^{+-}/b(b-bar)... has been performed in order to measure the most general top-quark couplings to gauge bosons at polarized linear colliders. The optimal beam polarization for determination of each coupling has been found

Shin Nakamura

We consider bosonic noncritical strings as QCD strings and we present a basic strategy to construct them in the context of Liouville theory. We show that Dirichlet boundary conditions play important roles in generalized Liouville theory. Specifically, they are used to stabilize the classical configuration of strings and also utilized to treat tachyon condens

S. Yu. Sakovich

Integrability of the differential constraints arising from the singularity analysis of two (1+1)-dimensional second-order evolution equations is studied. Two nonlinear ordinary differential equations are obtained in this way, which are integrable by quadratures in spite of very complicated branching of their solutions.

Guang-Ming Zhang, Lu Yu

The ground-state phase diagram of a half-filled anisotropic Kondo lattice model is calculated within a mean-field theory. For small transverse exchange coupling $J_{\perp}<J_{\perp c1}$, the ground state shows an antiferromagnetic long-range order with finite staggered magnetizations of both localized spins and conduction electrons. When $J_{\perp}>J_{\perp

Sze Kui Ng

We propose a new gauge theory of quantum electrodynamics (QED) and quantum chromodynamics (QCD) from which we derive knot invariants such as the Jones polynomial. Our approach is inspired by the work of Witten who derived knot invariants from quantum field theory based on the Chern-Simon Lagrangian. From our approach we can derive new knot invariants which e

Koh&#39;ichiro Hara, Ichiro Ohba

We present a proposal for the estimation of Büttiker-Landauer traversal time based on the visibility of transmission current. We analyze the tunneling phenomena with a time-dependent potential and obtain the time-dependent transmission current. We found that the visibility is directly connected to the traversal time. Furthermore, this result is valid not onl

J. H. Yoon

A set of exact quasi-local conservation equations is derived from the Einstein&#39;s equations using the first-order Kaluza-Klein formalism of general relativity in the (2,2)-splitting of 4-dimensional spacetime. These equations are interpreted as quasi-local energy, momentum, and angular momentum conservation equations. In the asymptotic region of asymptoti

A. Suzuki, H. Park, K2K collaboration

We describe the construction and performance of a scintillating fiber detector used in the near detector for the K2K (KEK to Kamioka, KEK E362) long baseline neutrino oscillation experiment. The detector uses 3.7 m long and 0.692 mm diameter scintillating fiber coupled to image-intensifier tubes (IIT), and a CCD camera readout system. Fiber sheet production

I. Tsukada, J. Takeya, T. Masuda, K. Uchinokura

Weak ferromagnetism of quasi-one-dimensional S = 1/2 antiferromagnet BaCu$_2$Ge$_2$O$_7$ is studied by the magnetization measurement. The spontaneous magnetization appears along the b axis. The local symmetry between the in-chain nearest neighbor spins allows the presence of Dzyaloshinskii-Moriya interaction, and the only possible spatial configuration of th

Paul B. Slater

We demonstrate --- using the case of the two-dimensional quantum systems --- that the &#34;natural measure on the space of density matrices describing N-dimensional quantum systems&#34; proposed by Zyczkowski et al (quant-ph/9804024) does not belong to the class of normalized volume elements of monotone metrics on the quantum systems. Such metrics possess th

Holger Mack, Dietmar G. Fischer, Matthias Freyberger

We analyze the estimation of a finite ensemble of quantum bits which have been sent through a depolarizing channel. Instead of using the depolarized qubits directly, we first apply a purification step and show that this improves the fidelity of subsequent quantum estimation. Even though we lose some qubits of our finite ensemble the information is concentrat

Jindong Zhou, Yong-de Zhang

Unknown quantum pure states of arbitrary but definite S-level of a particle can be transferred onto a group of remote two-level particles through two-level EPRs as many as the number of those particles in this group. We construct such a kind of teleportation, the realization of which need a nonlocal unitary transformation to the quantum system that is made u

T. C. Ralph

Our criteria for continuous variable quantum teleportation [T.C.Ralph and P.K.Lam, Phys.Rev.Lett. {\bf 81}, 5668 (1998)] take the form of sums, rather than products, of conjugate quadrature measurements of the signal transfer coefficients and the covariances between the input and output states. We discuss why they have this form. We also discuss the physical

Jijun Zhao, Jinlan Wang, Guanghou Wang

We have developed a transferable nonorthogonal tight-binding total energy model for germanium and use it to study small clusters. The cohesive energy, bulk modulus, elastic constants of bulk germanium can be described by this model to considerably good extent. The calculated bulk phase diagram for germanium agrees well with LDA results. The geometries and bi

Arezky H. Rodriguez, J. Marin-Antuna, H. Rodriguez-Coppola, C. Dopazo

The Surface Green Function Matching analysis (SGFM) is used to study the normal modes of the interface oscillations between two non-mixed fluids by considering the difference in their densities and viscosities. The limiting case of viscous-inviscid system is used for comparison. The role of the viscosity and the density ratios on the momentum exchange and on

Arezky H. Rodriguez, J. Marin-Antuna, H. Rodriguez-Coppola

The matching conditions at the interface between two non-mixed fluids at rest are obtained directly using the equation of movement of the whole media. This is a non-usual point of view in hydrodynamics courses and our aim is to fix ideas about the intrinsic information contained in the matching conditions, on fluids in this case. Afterward, it is analyzed th

S. Hillert, R. Ischebeck, U. C. Müller, S. Roth

Test measurements on the silicon pixel detector for the beam trajectory monitor at the free electron laser of the TESLA test facility are presented. To determine the electronic noise of detector and read-out and to calibrate the signal amplitude of different pixels the 6 keV photons of the manganese K line are used. Two different methods determine the spatia

D. A. Varshalovich, A. Y. Potekhin, A. V. Ivanchik

One of the topical problems of contemporary physics is a possible variability of the fundamental constants. Here we consider possible variability of two dimensionless constants which are most important for calculation of atomic and molecular spectra (in particular, the X-ray ones): the fine-structure constant α=e^2/\hbar c and the proton-to-electron mass rat

B. Roy, B. K. Chatterjee, Mala Das, S. C. Roy

Superheated droplets are proven to be excelent detectors for neutrons and could be used as a neutron dosimeter. To detect accurately the volume of the vapour formed upon nucleation and hence to observe the nucleation quantitatively an air displacement system has been developed.

Rob de Ruyter van Steveninck, Alexander Borst, William Bialek

In the past decade, a small corner of the fly&#39;s visual system has become an important testing ground for ideas about coding and computation in the nervous system. A number of results demonstrate that this system operates with a precision and efficiency near the limits imposed by physics, and more generally these results point to the reliability and effic

Jan Govaerts, Jose-Luis Lucio-Martinez

Nuclear muon capture on the proton and $^3$He is considered both within and beyond the Standard Model in terms as general as is possible. Explicit and precise analytic expressions for all possible observables are given, assuming only a Dirac neutrino in the limit of vanishing mass. These results allow both for precision tests of the Standard Model and new ph

Yongseok Oh, Alexander I. Titov, T. -S. Harry Lee

We have investigated exclusive photoproduction of light vector mesons ($ω$, $ρ$ and $ϕ$) on the nucleon at low energies. In order to explore the questions concerning the so-called missing nucleon resonances, we first establish the predictions from a model based on the Pomeron and meson exchange mechanisms. We have also explored the contributions due to the m