August 2004 arXiv papers — page 7

Gabriel G. Bes, Lionel Lamadon, Francois Trouilleux

A way of extracting French verbal chunks, inflected and infinitive, is explored and tested on effective corpus. Declarative morphological and local grammar rules specifying chunks and some simple contextual structures are used, relying on limited lexical information and some simple heuristic/statistic properties obtained from restricted corpora. The specific

Ch. Tsalidis, G. Orphanos, A. Iordanidou, A. Vagelatos

The aim of this paper is to present the R&D activities carried out at Neurosoft S.A. regarding the development of proofing tools for Modern Greek. Firstly, we focus on infrastructure issues that we faced during our initial steps. Subsequently, we describe the most important insights of three proofing tools developed by Neurosoft, i.e. the spelling checker, t

Florian Meier, Daniel Loss

Coherent Rabi oscillations between quantum states of superconducting micro-circuits have been observed in a number of experiments, albeit with a visibility which is typically much smaller than unity. Here, we show that the coherent coupling to background charge fluctuators [R.W. Simmonds et al., Phys. Rev. Lett. 93, 077003 (2004)] leads to a significantly re

W. P. Halperin, J. A. Sauls

Liquid 3He confined in silica aerogel provides us with a unique system to study the effects of quenched disorder on the properties of a strongly correlated quantum liquid. The superfluid phases display interplay between disorder and complex symmetry-breaking.

Hong-Yi Chen, C. S. Ting

Based on the $t-t'-U-V$ model with proper chosen parameters for describing the cuprate superconductors, it is found that near the optimal doping at low temperature ($T$), only the pure d-wave superconductivity ($d$SC) prevails and the antiferromagnetic (AF) order is completely suppressed. At higher $T$, the AF order with stripe modulation and the accompa

W. Pan, G. A. Csathy, D. C. Tsui, L. N. Pfeiffer

We have observed in a low density two-dimensional hole system (2DHS) of extremely high quality (with hole density p=1.6x10^{10} cm^{-2} and mobility μ=0.8x10^6 cm^2/Vs) that, as the 2DHS is continuously tilted with respect to the direction of the magnetic field, the ν=1/3 fractional quantum Hall effect (FQHE) state is weakened and its magnetoresistivity rise

Arkady I. Leonov, Valery S. Volkov

A constitutive theory for weak viscoelastic nematodynamics of Maxwell type is developed using the standard local approach of non-equilibrium thermodynamics. Along with particular viscoelastic and nematic kinematics, the theory uses the weakly elastic potential proposed by de Gennes for nematic solids and the LEP constitutive equations for viscous nematic liq

Alfredo A. Correa, Fernando A. Reboredo, C. A. Balseiro

We present a theoretical method for the design and optimization of quantum corrals with specific electronic properties. Taking advantage that spins are subject to a RKKY interaction that is directly controlled by the scattering of the quantum corral, we design corral structures that reproduce spin Hamiltonians with coupling constants determined a priori. We

L. Anton, R. A. Blythe, A. J. Bray

We consider the trapping reaction, $A+B\to B$, where $A$ and $B$ particles have a diffusive dynamics characterized by diffusion constants $D_A$ and $D_B$. The interaction with $B$ particles can be formally incorporated in an effective dynamics for one $A$ particle as was recently shown by Bray {\it et al}. [Phys. Rev. E {\bf 67}, 060102 (2003)]. We use this

G. Bussi, J. Menendez, J. Ren, M. Canonico

The lineshapes of the Raman excitation profiles for radial breathing modes in carbon nanotubes are shown to be strongly affected by interference effects that arise whenever strong optical transitions are separated by a small energy. This is the case in metallic zigzag and chiral tubes, where one-dimensional singularities in the electronic joint density of st

Andrea Alu, Filiberto Bilotti, Nader Engheta, Lucio Vegni

Recently, it has been experimentally shown by several other researchers in the physics community that a properly designed periodic corrugation of a metallic opaque screen may significantly enhance the power transmission through a sub-wavelength hole in the optical frequency band. Oliner, Jackson and their co-workers explained and justified this phenomenon as

Oleg L. Berman, Yurii E. Lozovik, David W. Snoke, Rob D. Coalson

Collective properties of a quasi-two-dimensional (2D) system of spatially indirect magnetoexcitons in coupled quantum wells (CQW) in high magnetic field $H$ were analyzed in the presence of disorder. The Hamiltonian of the dilute gas of magnetoexcitons with dipole-dipole repulsion in a random field has been reduced to the Hamiltonian of a dilute gas of dipol

S. D. Tiwari, K. P. Rajeev

Nickel oxide nanoparticles are prepared by a sol gel method and characterized by x-ray diffraction and transmission electron microscope. Here we present measurements on temperature and field dependence of magnetization and time dependence of thermoremanent magnetization. Our conclusion based on these measurements is that the system shows spin glass like beha

Stephane Berciaud, Laurent Cognet, Gerhard Blab, Brahim Lounis

We introduce a new, highly sensitive, and simple heterodyne optical method for imaging individual non-fluorescent nano-objects. A two orders of magnitude improvement of the signal is achieved compared to previous methods. This allows for the unprecedented detection of individual small absorptive objects such as metallic clusters (of 67 atoms) or non-luminesc

A. Honecker, N. Fukushima, B. Normand, G. Chaboussant

We have obtained new inelastic neutron scattering (INS) data for the molecular magnet Mn12-acetate which exhibit at least six magnetic peaks in the energy range 5-35 meV. These are compared with a microscopic Heisenberg model for the 12 quantum spins localised on the Mn ions, coupled by four inequivalent magnetic exchange constants. A fit to the magnetic sus

N. Kristoffel, P. Rubin

A simple model of cuprate superconductivity with an electron spectrum prepared by doping is developed. The pair-transfer interaction couples the itinerant band with two components ("hot'' and "cold'') of the defect subsystem. There are basic defect-itinerant gaps quenched by progressive doping. Band overlaps appear as novel sources fo

B. Hosseinkhani, J. Zaanen

Using recent insights obtained in heavy fermion physics on the thermodynamic singularity structure associated with quantum phase transitions, we present here an experimental strategy to establish if the zero-temperature transition in the disordered two dimensional gas is a real quantum phase transition. We derive a overcomplete set of scaling laws relating t

Hsiao-Ping Hsu, Bernd A. Berg, Peter Grassberger

Treating realistically the ambient water is one of the main difficulties in applying Monte Carlo methods to protein folding. The solvent-accessible area method, a popular method for treating water implicitly, is investigated by means of Metropolis simulations of the brain peptide Met-Enkephalin. For the phenomenological energy function ECEPP/2 nine atomic so

Peter Grassberger

We describe a class of growth algorithms for finding low energy states of heteropolymers. These polymers form toy models for proteins, and the hope is that similar methods will ultimately be useful for finding native states of real proteins from heuristic or a priori determined force fields. These algorithms share with standard Markov chain Monte Carlo metho

N. Binggeli, M. Altarelli

The orbital, lattice, and spin ordering phenomena in KCuF3 are investigated by means of LDA+U calculations, based on ab-initio pseudopotentials.We examine the Cu-3d orbital ordering and the associated Jahn-Teller distortion in several different spin-ordered structures of KCuF3. The ground state is correctly predicted to be an A-type antiferromagnetic structu

M. Ghanashyam Krishna, M. Durga Prasad, V. Srinivasan

A possible universal definition for a nanostructured material based purely on experimental data available in literature for a wide variety of physical phenomena is proposed. It is suggested that for values of the ratio of sample volume, V to that of the unit cell volume, Vc, 10^5- 10^6 the samples behave as nanostructures. This is mirrored in the ratio of th

Marc Barthelemy, Alain Barrat, Romualdo Pastor-Satorras, Alessandro Vespignani

We review the main tools which allow for the statistical characterization of weighted networks. We then present two case studies, the airline connection network and the scientific collaboration network, which are representative of critical infrastructures and social systems, respectively. The main empirical results are (i) the broad distributions of various

Tomasz Dietl

Recent progress in understanding and controlling spintronic properties of (Ga,Mn)As and related compounds is contrasted to diverging experimental and theoretical results concerning the origin of high temperature ferromagnetism discovered in an ample class of magnetically doped wide-band-gap semiconductors.

Lorenzo Malavasi, Cristina Tealdi, Monica Amboage, M. Cristina Mozzati

The phase stability of the MgMn2O4 spinel has been studied by means of high-pressure X-ray diffraction for pressures up to 30 GPa. Two samples with different inversion degrees have been considered. Both spinels undergo a phase transition towards an orthorhombic structure (CaMn2O4-type). For the more inverted sample the transition pressure is at least 1 GPa l

V. V. Makhro

We present results of direct numerical calculations for the problem of quantum tunneling through the time-dependent potential barrier. Computations clearly demonstrate existence of the effect of the underbarrier resonance.

H. Y. Chan, T. S. Lo, P. M. Hui, N. F. Johnson

We study, both numerically and analytically, a Binary-Agent-Resource (B-A-R) model consisting of N agents who compete for a limited resource 1/2<L/N <1, where L is the maximum available resource per turn for all N agents. As L increases, the system exhibits well-defined plateaux regions in the success rate which are separated from each other by abrupt transi

Olivier C. Martin

A sketch of the chapter appearing under the same heading in the book ``New Optimization Algorithms in Physics&#39;&#39; (A.K. Hartmann and H. Rieger, Eds.) is given. After a general introduction to spin glasses, important aspects of heuristic algorithms for tackling these systems are covered. Some open problems that one can hope to resolve in the next few ye

L. Sheng, D. Y. Xing, D. N. Sheng

We study electron tunneling through two small ferromagnetic dots. Quantum charge fluctuations and interdot coupling make each Coulomb peak of the conductance at zero interdot coupling split across. The interdot tunnel coupling is determined by the relative orientation of magnetizations of the two dots, leading to different splitting energies of the Coulomb p

H. Hong, Hyunggyu Park, M. Y. Choi

We study collective behavior of locally coupled limit-cycle oscillators with random intrinsic frequencies, spatially extended over $d$-dimensional hypercubic lattices. Phase synchronization as well as frequency entrainment are explored analytically in the linear (strong-coupling) regime and numerically in the nonlinear (weak-coupling) regime. Our analysis sh

L. Sheng, D. Y. Xing, D. N. Sheng

Using the closed-time path integral approach, we nonperturbatively study inelastic tunneling of electrons via magnetic impurities in the barrier accompanied by phonon emission in a magnetic tunnel junction. The spectrum density of phonon emission is found to show a power-law infrared singularity $\simω^{-(1-g)}$ with $g$ the dimensionless electron-phonon cou

B. Militzer E. L. Pollock

Nuclear reaction rates in plasmas depend on the overlap (contact) probability of the reacting ions. Path integral Monte Carlo (PIMC) calculations are used here to determine these contact probabilities, g(0), for the one component plasma (OCP) with emphasis on many-body quantum effects which can lead to order of magnitude changes. An intuitive explanation for

Heiko Bauke, Stephan Mertens

Energy spectra of disordered systems share a common feature: if the entropy of the quenched disorder is larger than the entropy of the dynamical variables, the spectrum is locally that of a random energy model and the correlation between energy and configuration is lost. We demonstrate this effect for the Edwards-Anderson model, but we also discuss its unive

M. O. Goerbig, P. Lederer, C. Morais Smith

The Hall-resistance curve of a two-dimensional electron system in the presence of a strong perpendicular magnetic field is an example of self-similarity. It reveals plateaus at low temperatures and has a fractal structure. We show that this fractal structure emerges naturally in the Hamiltonian formulation of composite fermions. After a set of transformation

J. C. Xavier, E. Miranda

We present results for the correlation exponent K_rho of the Tomonaga-Luttinger liquid description of the one-dimensional Kondo lattice as a function of conduction electron density and coupling constant. It is obtained from the first derivative of the Fourier transform of the charge-charge correlation function. We also show that the spin correlation function

Karl Glazebrook, Jeffrey Tober, Scott Thomson, Joss Bland-Hawthorn

We report the results of a deep 3D imaging survey of the Hubble Deep Field North using the Taurus Tunable Filter and the William Herschel Telescope. This survey was designed to search for new line emitting populations of objects missed by other techniques and to measure the cosmic star-formation rate density from a line-selected survey. We observed in three

E. Fenimore, D. Palmer, M. Galassi, T. Tavenner

The Swift Burst Alert Telescope (BAT) is a huge (5200 cm2) coded aperture imager that will detect gamma-ray bursts in real time and provide a location that the Swift satellite will use to slew the optical and x-ray telescopes. The huge size of BAT is a challenge for the on-board triggering: a change as small as 1% is equivalent to a 1 sigma statistical varia

E. E. Fenimore, K. McLean, D. Palmer, S. Barthelemy

The Swift satellite will be a self-contained observatory that will bring new capabilities to the observing of the early afterglow emission of Gamma-ray Bursts. Swift is completely autonomous and will do all of the observations without help from the ground. There are three instruments on Swift. A large (5200 sq cm) coded aperture imager will locate the bursts

K. McLean, E. E. Fenimore, D. Palmer, S. Barthelmy

Swift has two main types of ``rate&#39;&#39; triggers: short and long. Short trigger time scales range from 4ms to 64ms, while long triggers are 64ms to ~ 16 seconds. While both short and long trigger have criteria with one background sample (traditional ``one-sided&#39;&#39; triggers), the long triggers can also have criteria with two background samples (``

Michel Cure, Diego Rial

The topological analysis from Bjorkman (1995) for the standard model that describes the winds from hot stars by Castor, Abbott & Klein (1975) has been extended to include the effect of stellar rotation and changes in the ionization of the wind. The differential equation for the momentum of the wind is non--linear and transcendental for the velocity gradient.

Steven A. Balbus

An exact nonlinear scaling transformation is presented for the local three-dimensional dynamical equations of motion for differentially rotating disks. The result is relevant to arguments that have been put forth claiming that numerical simulations lack the necessary numerical resolution to resolve nonlinear instabilities that are supposedly present. We show

H. Liszt, R. Lucas, J. H. Black

We used the Plateau de Bure Interferometer to search for $λ$3mm absorption lines of HOC+ from local diffuse and translucent clouds occulting compact extragalactic mm-wave continuum sources. We detected HOC+ in three directions with column densities only 70-120 times below those of the HCO+ isomer, a factor 5-50 higher than typically found in dense dark gas b

N. N. Chugai, R. A. Chevalier, P. Lundqvist

We propose a model to account for the bolometric light curve, quasi-continuum and the Ca II emission features of the peculiar type Ia supernova (SN) 2002ic, which exploded in a dense circumstellar envelope. The model suggests that the SN Ia had the maximum possible kinetic energy and that the ejecta expand in an approximately spherically symmetric (possibly

L. C. Gallo, Th. Boller, W. N. Brandt, A. C. Fabian

The XMM-Newton observation of the narrow-line quasar NAB 0205+024 reveals three striking differences since it was last observed in the X-rays with ASCA. Firstly, the 2-10 keV power-law is notably steeper. Secondly, a hard X-ray flare is detected, very similar to that seen in I Zw 1. Thirdly, a strong and broad emission feature is detected with the bulk of it

Gordon T. Richards, Robert C. Nichol, Alexander G. Gray, Robert J. Brunner

We present a catalog of 100,563 unresolved, UV-excess (UVX) quasar candidates to g=21 from 2099 deg^2 of the Sloan Digital Sky Survey (SDSS) Data Release One (DR1) imaging data. Existing spectra of 22,737 sources reveals that 22,191 (97.6%) are quasars; accounting for the magnitude dependence of this efficiency, we estimate that 95,502 (95.0%) of the objects

Michael A. Weinstein, Gordon T. Richards, Donald P. Schneider, Joshua D. Younger

We present an empirical algorithm for obtaining photometric redshifts of quasars using 5-band Sloan Digital Sky Survey (SDSS) photometry. Our algorithm generates an empirical model of the quasar color-redshift relation, compares the colors of a quasar candidate with this model, and calculates possible photometric redshifts. Using the 3814 quasars of the SDSS

B. Jonkheid, F. G. A. Faas, G. -J. van Zadelhoff, E. F. van Dishoeck

A model is presented which calculates the gas temperature and chemistry in the surface layers of flaring circumstellar disks using a code developed for photon-dominated regions. Special attention is given to the influence of dust settling. It is found that the gas temperature exceeds the dust temperature by up to several hundreds of Kelvins in the part of th

I. Kamp, C. P. Dullemond

Models for the structure of protoplanetary disks have so far been based on the assumption that the gas and the dust temperature are equal. The gas temperature, an essential ingredient in the equations of hydrostatic equilibrium of the disk, is then determined from a continuum radiative transfer calculation, in which the continuum opacity is provided by the d

Nicola La Palombara, Patrizia Caraveo, Roberto Mignani, Evanthia Hatziminaoglou

Most counterparts of the identified low-latitude gamma-ray sources are Isolated Neutron Stars (INSs). They are characterized by an extremely high value of the X/optical flux ratio, therefore a systematic X-ray/optical coverage of the fields of unidentified low-latitude gamma-ray sources is the best way to unveil possible INS counterparts. Since the low-latit

Frederic Pont, Francois Bouchy, Didier Queloz, Nuno Santos

We report the discovery of a transiting hot Jupiter around OGLE-TR-111, from our radial velocity follow-up of OGLE transiting candidates in Carina. The planet has a mass of 0.53 +- 0.11 M_J and a radius of 1.0 +0.13-0.06 R_J. Three transiting exoplanets have already been found among OGLE candidates, all with periods near 1.5 days. The planet presented here,

E. Carretti, M. Zannoni, C. Macculi, S. Cortiglioni

The role of systematic errors induced by thermal fluctuations is analyzed for the SPOrt experiment with the aim at estimating their impact on the measurement of the Cosmic Microwave Background Polarization (CMBP). The transfer functions of the antenna devices from temperature to data fluctuations are computed, by writing them in terms of both instrument and

Katsuaki Asano, Fumio Takahara

We propose a new mechanism to screen the electric field in the pulsar polar cap. Previous studies have shown that if an electron beam from the stellar surface is accelerated to energies high enough to create electron-positron pairs, the required electric field parallel to the magnetic field lines is too strong to be screened out by the produced pairs. We arg

D. M. Palmer, E. Fenimore, M. Galassi, K. McLean

The BAT instrument tells the Swift satellite where to point to make immediate follow-up observations of GRBs. The science software on board must efficiently process gamma-ray events coming in at up to 34 kHz, identify rate increases that could be due to GRBs while disregarding those from known sources, and produce images to accurately and rapidly locate new

V. P. Egorova, A. V. Glushkov, A. A. Ivanov, S. P. Knurenko

The energy spectrum of UHECRs is discussed on the basis of the Yakutsk array database analysis. In the region E=0.1 to 30 EeV the showers are detected under trigger-500, while at energies above 30 EeV the whole acceptance area for trigger-1000 is used in order to utilize all the data available in the region of GZK cutoff.

D. A. Green, M. Lacy, S. Bhatnagar, E. L. Gates

Radio and near-infared observations towards the steep spectrum Galactic plane radio source WKB 0314+57.8 are presented, in order to clarify the nature of this source. The radio observations include archival and survey data, together with new Giant Metrewave Radio Telescope observations at 617 MHz. The near-infrared observations are in the J and K bands, from

Y. Z. Fan, D. M. Wei, Bing Zhang

(Please note that the abstract has been significantly shorted) We investigate Gamma-ray Burst (GRB) internal shocks with moderate magnetization, with the magnetization parameter $σ$ ranging from 0.001 to 10. Possible magnetic dissipation in the stripped magnetized shells is also taken into account through introducing a parameter $k$ ($0<k\leq 1$), which is t

Tadeusz Wibig, Arnold W. Wolfendale

It is often claimed that there should be a &#39;GZK cut-off&#34; in the flux of extragalactic cosmic rays, arising from interactions between the cosmic rays and the cosmic micro-wave background photons (e.g. 1 and 2). Some experiments (3 and 4) show particles of even higher energy than this value and this has led to claims for exotic processes (e.g. 5 and 6)

Y. Z. Fan, D. M. Wei, C. F. Wang

In the Poynting Flux dominated outflow (the initial ratio of the electromagnetic energy flux to the particle energy flux $σ_0\gg1$) model for Gamma-ray bursts, nearly half of the internally dissipated magnetic energy is converted into the prompt $γ-$ray energy emission and the rest is converted into the kinetic energy of the outflow. Consequently, at the end

J. W. Moffat

The problem of explaining the acceleration of the expansion of the universe and the observational and theoretical difficulties associated with dark matter and dark energy are discussed. The possibility that Einstein gravity does not correctly describe the large-scale structure of the universe is considered and an alternative gravity theory is proposed as a p

F. Shekh-Momeni, J. Samimi

In this model a collimated ultra-relativistic ejecta collides with an amorphous dense cloud surrounding the central engine, producing gamma-rays via synchrotron process. The ejecta is taken as a standard candle, while assuming a gaussian distribution in thickness and density of the surrounding cloud. Due to the cloud high density, the synchrotron emission wo

Alexios P. Polychronakos

We derive the hamiltonian and canonical structure for arbitrary deformations of a phase space (quantum Hall) droplet on a general manifold of any dimension. The derivation is based on a transformation that decouples the Casimirs of the density Poisson structure. The linearized theory reproduces the edge state chiral action of the droplets, while the nonlinea

Viacheslav P. Belavkin, Giacomo Mauro D&#39;Ariano, Maxim Raginsky

We define and study a fidelity criterion for quantum channels, which we term the minimax fidelity, through a noncommutative generalization of maximal Hellinger distance between two positive kernels in classical probability theory. Like other known fidelities for quantum channels, the minimax fidelity is well-defined for channels between finite-dimensional al

Tuhin Roy

We make a detailed analysis of gauge coupling unification in supersymmetry. When the Standard Model gauge group is embedded in a Grand Unified Theory, new particles often appear below the GUT scale in order to predict the right phenomenology at low energy. While these new particles are beyond the reach of accelerator experiments, they change the prediction o

Matthew Young

The Katz-Sarnak philosophy predicts that statistics of zeros of families of L-functions are strikingly universal. However, subtle arithmetical differences between families of the same symmetry type can be detected by calculating lower-order terms of the statistics of interest. In this paper we calculate lower-order terms of the 1-level density of some famili

Juan M. Romero, Adolfo Zamora

We show that the two-time physics model leads to a mechanical system with Dirac brackets consistent with the Snyder noncommutative space. An Euclidean version of this space is also obtained and it is shown that both spaces have a dual system describing a particle in a curved space-time.

Qi Chen, Thang Le

Almost integral TQFTs were introduced by Gilmer [Duke Math. J. 125 (2004) 389--413]. The aim of this paper is to modify the TQFT of the category of extended 3-cobordisms given by Turaev (in his book: Quantum invariants of knots and 3-manifolds) to obtain an almost integral TQFT.

Stephon Alexander, Katrin Becker, Melanie Becker, Keshav Dasgupta

We complete the duality cycle by constructing the geometric transition duals in the type IIB, type I and heterotic theories. We show that in the type IIB theory the background on the closed string side is a Kahler deformed conifold, as expected, even though the mirror type IIA backgrounds are non-Kahler (both before and after the transition). On the other ha

Yasuhiro Abe, V. P. Nair, Mu-In Park

Classical ${\cal N}=4$ Yang-Mills theory is defined by the superspace constraints. We obtain a solution of a subset of these constraints and show that it leads to the maximally helicity violating (MHV) amplitudes. The action which leads to the solvable part of the constraints is a Wess-Zumino-Witten (WZW) action on a suitably extended superspace. The non-MHV

Andreas Faltenbacher, Andrey V. Kravtsov, Daisuke Nagai, Stefan Gottloeber

We study motions of galaxies in galaxy clusters formed in the concordance LCDM cosmology. We use high-resolution cosmological simulations that follow dynamics of dark matter and gas and include various physical processes critical for galaxy formation: gas cooling, heating and star formation. Analysing motions of galaxies and the properties of intracluster ga

Kunihito Ioka, Peter Meszaros

We investigate the radio afterglows of gamma-ray bursts (GRBs) and hypernovae (HNe) at high redshifts and quantify their detectability, as well as their potential usefulness for 21 cm absorption line studies of the intergalactic medium (IGM) and intervening structures. We examine several sets of source and environment model parameters that are physically pla

A. M. Ghezelbash, R. B. Mann

We present new M2 and M5 brane solutions in M-theory based on transverse Atiyah-Hitchin space and other self-dual geometries. One novel feature of these solutions is that they have bolt-like fixed points yet still preserve 1/4 of the supersymmetry. All the solutions can be reduced down to ten dimensional intersecting brane configurations.

Luis Anchordoqui, Haim Goldberg, Carlos Nunez

A striking aspect of the recently proposed split supersymmetry is the existence of heavy gluinos which are metastable because of the very heavy squarks which mediate their decay. In this paper we correlate the expected flux of these particles with the accompanying neutrino flux produced in inelastic $pp$ collisions in distant astrophysical sources. We show t

Leonardo Navarro Carvalho

Among (isotopy classes of) automorphisms of handlebodies those called irreducible (or generic) are the most interesting, analogues of pseudo-Anosov automorphisms of surfaces. We consider the problem of isotoping an irreducible automorphism so that it is most efficient (has minimal growth rate) in its isotopy class. We describe a property, called tightness, o

A. Sengupta

In this paper we employ the topological-multifuncoctional mathematical language and techniques of non-injective illposedness developed earlier to formulate a notion of ChaNoXity -- Chaos-Nonlinearity-Complexity -- in describing the specifically nonlinear dynamical evolutionary processes of Nature. Non-bijective ill-posedness is the natural mode of expression

Burghard Gruter, Reinhard Alkofer, Axel Maas, Jochen Wambach

The Dyson-Schwinger equations of Landau-gauge Yang-Mills theory for the gluon and ghost propagators are investigated. Numerical results are obtained within a truncation scheme which has proven to be successful at vanishing temperature. For temperatures up to 250 MeV we find only minor quantitative changes in the infrared behaviour of the gluon and ghost prop

Jean-Loic Kneur, Marcus B. Pinto

In the framework of the O(N) three-dimensional effective scalar field model for homogeneous dilute weakly interacting Bose gases we use the 1/N expansion to evaluate, within the large N limit, the parameter r_c which is directly related to the critical chemical potential mu_c. This quantity enters the order-a^2 n^{2/3} coefficient contributing to the critica

Samuel Friot, David Greynat, Eduardo De Rafael

The correlation function of a $V-A$ current with a $V+A$ current is discussed within the framework of QCD in the limit of a large number of colours $N_c$. Applications to the evaluation of chiral condensates of dimension six and higher, as well as to the matrix elements of the $Q_7$ and $Q_8$ electroweak penguin operators are discussed. A critical comparison

Jose Natario

We find a class of warp drive spacetimes possessing Newtonian limits, which we then determine. The same method is used to compute Newtonian limits of the Schwarzschild solution and spatially flat Friedmann-Robertson-Walker cosmological models.

Christian Hoerhammer, Helmut Buettner

We study the influence of entanglement on the relation between the statistical entropy of an open quantum system and the heat exchanged with a low temperature environment. A model of quantum Brownian motion of the Caldeira-Leggett type - for which a violation of the Clausius inequality has been stated by Th.M. Nieuwenhuizen and A.E. Allahverdyan [Phys. Rev.

X. Kang, Y. P. Jing, H. J. Mo, G. Boerner

We model the galaxy formation in a series of high-resolution N-body simulations using the semi-analytical approach. Unlike many earlier investigations based on semi-analytical models, we make use of the subhalos resolved in the $N$-body simulations to follow the mergers of galaxies in dark halos, and we show that this is pivotal in modeling correctly the gal

Laszlo Gergely, Emily Leeper, Roy Maartens

At high energies on a cosmological brane of Randall-Sundrum type, particle interactions can produce gravitons that are emitted into the bulk and that can feed a bulk black hole. We generalize previous investigations of such radiating brane-worlds by allowing for a breaking of Z_2-symmetry, via different bulk cosmological constants and different initial black

N. Bouche, M. T. Murphy, C. Peroux

We study the cross-correlation between 212 MgII quasar absorption systems and \~20,000 Luminous Red Galaxies (LRGs) selected from the Sloan Digital Sky Survey Data Release 1 in the redshift range 0.4<z<0.8. The MgII systems were selected to have 2796 & 2803 rest-frame equivalent widths >=1.0 Angstrom and identifications confirmed by the FeII 2600 or MgI 2852

Tommy Burch, Christof Gattringer, Andreas Schäfer

Using a ``wall&#39;&#39; of quark point sources, we invert the chirally improved Dirac operator to create an ``incoherent&#39;&#39; collection of quark propagators which originate from all spatial points of the source time slice. The lowest-order NRQCD approximation is used to create heavy-quark propagators from the same wall source. However, since the numer

N. C. Santos, F. Bouchy, M. Mayor, F. Pepe

In this letter we present the discovery of a very light planetary companion to the star mu Ara (HD160691). The planet orbits its host once every 9.5days, and induces a sinusoidal radial velocity signal with a semi-amplitude of 4.1 m/s, the smallest Doppler amplitude detected so far. These values imply a mass of m2 sini = 14 earth-masses. This detection repre

Armen Sedrakian

Type-I proton superconducting cores of neutron stars break up in a magnetic field into alternating domains of superconducting and normal fluids. We examine two channels of superfluid-normal fluid friction where (i) rotational vortices are decoupled from the non-superconducting domains and the interaction is due to the strong force between protons and neutron

Bergfinnur Durhuus, Thordur Jonsson

We prove the existence of global solutions to the Cauchy problem for noncommutative nonlinear wave equations in arbitrary even spatial dimensions where the noncommutativity is only in the spatial directions. We find that for existence there are no conditions on the degree of the nonlinearity provided the potential is positive. We furthermore prove that nonli

Martin Hallnäs, Edwin Langmann, Cornelius Paufler

As is well-known, there exists a four parameter family of local interactions in 1D. We interpret these parameters as coupling constants of delta-type interactions which include different kinds of momentum dependent terms, and we determine all cases leading to many-body systems of distinguishable particles which are exactly solvable by the coordinate Bethe An

Masaru Fukunaga, Tetsuya Onogi

We propose a method to determine the CKM matrix element $|V_{ub}|$ using the global $q^2$ dependence of the dispersive bound on the form factors for $B\to πlν$ decay. Since the lattice calculation of the $B\to πlν$ form factor is limited to the large $q^2$ regime, only the experimental data in a limited kinematic range can be used in a conventional method. I

Thomas Mannel, Frank J. Tackmann

Owing to the fact that m_c^2 ~ m_b Λ_QCD, the endpoint region of the charged lepton energy spectrum in the inclusive decay B -> X_c l ν_l is affected by the Fermi motion of the initial-state b quark bound in the B meson. This effect is described in QCD by shape functions. Including the mass of the final-state quark, we find that a different set of operators

N. M. Zubarev, O. V. Zubareva

Near-critical behavior of the free surface of an ideally conducting liquid in an external electric field is considered. Based on an analysis of three-wave processes using the method of integral estimations, sufficient criteria for hard instability of a planar surface are formulated. It is shown that the higher-order nonlinearities do not saturate the instabi

Fei Wang, Jin Min Yang

In the Affleck-Dine mechanism of baryogenesis, non-topological solitons called Q-balls can be formed. In this work we study the Q-balls which decay during the Big Bang Nucleosythesis (BBN) era. We show that such late-decaying baryonic Q-balls with lifetime of about 10^3 s can provide a new developing mechanism for the BBN through a rolling baryon to photon r

S. -K. Choi, S. L. Olsen

We report the observation of a near-threshold enhancement in the omega-J/psi invariant mass distribution for exclusive B-->K omega J/psi decays. The results are obtained from a 253 fb-1 data sample that contains 275 million BB-bar meson pairs that were collected near the Upsilon(4S) resonance with the Belle detector at the KEKB asymmetric energy e+e- collide

M. Hasegawa, K. Kaneko, T. Mizusaki

The structure of the $N \approx Z$ nuclei $^{66}$Ge and $^{68}$Ge is studied by the shell model on a spherical basis. The calculations with an extended $P+QQ$ Hamiltonian in the configuration space ($2p_{3/2}$, $1f_{5/2}$, $2p_{1/2}$, $1g_{9/2}$) succeed in reproducing experimental energy levels, moments of inertia and $Q$ moments in Ge isotopes. Using the r

M. Kawamura, H. Yaguchi, N. Kikugawa, Y. Maeno

We have investigated the magnetic field and temperature dependence of the tunneling spectra of the eutectic system Sr2RuO4-Ru. Electric contacts to individual Ru lamellae embedded in Sr2RuO4 enable the tunneling spectra at the interface between ruthenate and a Ru microinclusion to be measured. A zero bias conductance peak (ZBCP) was observed in the bias volt

Jairo Bochi, Bassam Fayad, Enrique Pujals

We show that a stably ergodic diffeomorphism can be $C^1$ approximated by a diffeomorphism having stably non-zero Lyapunov exponents.

Paul B. Slater

We pursue a number of analytical directions, motivated to some extent initially by the possibility of developing a methodology for formally proving or disproving a certain conjecture of quantum-theoretical relevance (quant-ph/0308037). It asserts that the 15-dimensional volume occupied by the separable two-qubit density matrices is (\sqrt{2}-1)/3, as measure

C. Henkel, A. M. Steane, R. Kaiser, J. Dalibard

A novel atomic beam splitter, using reflection of atoms off an evanescent light wave, is investigated theoretically. The intensity or frequency of the light is modulated in order to create sidebands on the reflected de Broglie wave. The weights and phases of the various sidebands are calculated using three different approaches: the Born approximation, a semi

C. Henkel, J. -Y. Courtois, A. Aspect

We present a semiclassical perturbation method for the description of atomic diffraction by a weakly modulated potential. It proceeds in a way similar to the treatment of light diffraction by a thin phase grating, and consists in calculating the atomic wavefunction by means of action integrals along the classical trajectories of the atoms in the absence of t

Hongwei Yu, L. H. Ford

We study the Brownian motion of a charged test particle coupled to electromagnetic vacuum fluctuations near a perfectly reflecting plane boundary. The presence of the boundary modifies the quantum fluctuations of the electric field, which in turn modifies the motion of the test particle. We calculate the resulting mean squared fluctuations in the velocity an

K. -P. Marzlin, S. Ghose, B. C. Sanders

In an open system, the geometric phase should be described by a distribution. We show that a geometric phase distribution for open system dynamics is in general ambiguous, but the imposition of reasonable physical constraints on the environment and its coupling with the system yields a unique geometric phase distribution that applies even for mixed states, n

Manuel A. Ballester

The problem of the estimation of multiple phases (or of commuting unitaries) is considered. This is a sub-model of the estimation of a completely unknown unitary operation where it has been shown in recent works that there are considerable improvements by using entangled input states and entangled measurements. Here it is shown that when estimating commuting