October 2003 arXiv papers — page 7

Audun Bakk, Ralf Metzler, Kim Sneppen

We investigate the sensitivity of production rates (activities) of the regulatory proteins CI (repressor) and Cro at the right operator (O_R}) of bacteriophage lambda. The DNA binding energies of CI, Cro, and RNA polymerase are perturbed to check the uncertainty of the activity, due to the experimental error, by means of a computational scattering method acc

Vitaly N. Golovach, Alexander Khaetskii, Daniel Loss

We study spin relaxation and decoherence in a GaAs quantum dot due to spin-orbit interaction. We derive an effective Hamiltonian which couples the electron spin to phonons or any other fluctuation of the dot potential. We show that the spin decoherence time $T_2$ is as large as the spin relaxation time $T_1$, under realistic conditions. For the Dresselhaus a

Rongliang Liu, Chang Sub Kim, G. D. Sanders, C. J. Stanton

We show that large amplitude, coherent acoustic phonon wavepackets can be generated and detected in In$_x$Ga$_{1-x}$N/GaN epilayers and heterostructures in femtosecond pump-probe differential reflectivity experiments. The amplitude of the coherent phonon increases with increasing Indium fraction $x$ and unlike other coherent phonon oscillations, both \textit

F. Penna, P. Tarazona

The dynamical properties of classical fluids at pico-liter scale attract experimentally and theoretically much attention in the soft-matter and biophysics communities, due to the appearance of the microfluidics, also called 'lab-on-a-chip', as one of the most relevance 21th century technologies. In this work we focus our attention on one of the key f

Esteban Moreno, F. J. Garcia-Vidal, L. Martin-Moreno

Surface modes are generally believed to be an undesirable feature of finite photonic crystals (PC), unlike point or line defect modes. However, it is possible to make the surface mode radiate by appropriate corrugation of the PC interface. In this paper we show theoretically that the coherent action of these surface indentations can be engineered to collimat

D. Bedeaux, S. Kjelstrup, J. M. Rubi

This paper shows how mesoscopic nonequilibrium thermodynamics can be applied to condensation and evaporation. By extending the normal set of thermodynamic variables with two internal variables, we are able to give a new theoretical foundation for a mechanism of condensation that has been proposed from molecular simulation results. The flux does not follow a

Claudia Acquisti, Paolo Allegrini, Patrizia Bogani, Marcello Buiatti

We investigate on a possible way to connect the presence of Low-Complexity Sequences (LCS) in DNA genomes and the nonstationary properties of base correlations. Under the hypothesis that these variations signal a change in the DNA function, we use a new technique, called Non-Stationarity Entropic Index (NSEI) method, and we prove that this technique is an ef

Paolo Allegrini, Paolo Grigolini, Luigi Palatella

In this paper we try to model certain features of human language complexity by means of advanced concepts borrowed from statistical mechanics. We use a time series approach, the diffusion entropy method (DE), to compute the complexity of an italian corpus of newspapers and magazines. We find that the anomalous scaling index is compatible with a simple dynami

Paolo Allegrini, Leone Fronzoni, Paolo Grigolini, Vito Latora

We prove the efficiency of a new method for the detection of crucial events that might have useful applications to the war against terrorism. This has to do with the search for rare but significant events, a theme of research that has been made of extreme importance by the tragedy of September 11. This method is applied here to defining the statistics of sei

Paolo Allegrini, Martina Giuntoli, Paolo Grigolini, Bruce J. West

Herein we consider various concepts of entropy as measures of the complexity of phenomena and in so doing encounter a fundamental problem in physics that affects how we understand the nature of reality. In essence the difficulty has to do with our understanding of randomness, irreversibility and unpredictability using physical theory, and these in turn under

J. Das, A. V. Mahajan, J. Bobroff, H. Alloul

We present the effect of Zn (S=0) and Cu (S=1/2) substitution at the Ni site of S=1 Haldane chain compound $Y_{2}BaNiO_{5}$. $^{89}$Y NMR allows us to measure the local magnetic susceptibility at different distances from the defects. The $^{89}$Y NMR spectrum consists of one central peak and several less intense satellite peaks. The shift of the central peak

F. Toschi, P. Capuzzi, S. Succi, P. Vignolo

We study the transition from the collisionless to the hydrodynamic regime in a two-component spin-polarized mixture of 40K atoms by exciting its dipolar oscillation modes inside harmonic traps. The time evolution of the mixture is described by the Vlasov-Landau equations and numerically solved with a fully three-dimensional concurrent code. We observe a mast

C. Pennetta, E. Alfinito, L. Reggiani, S. Ruffo

We study the resistance fluctuation distribution of a thin film near electrical breakdown. The film is modeled as a stationary resistor networkunder biased percolation. Depending on the value of the external current,on the system sizes and on the level of internal disorder, the fluctuation distribution can exhibit a non-Gaussian behavior. We analyze this non

V. Garcia-Morales J. Cervera

We comment on letter ``Is Tsallis Thermodynamics Nonextensive?'' by E. Vives and A. Planes [Phys. Rev. Lett. 88, 020601 (2002) cond-mat/0106428]. It is pointed out that the Euler and Gibbs-Duhem equations derived in the letter can serve to justify an appropriate form for the Lagrange parameters controlling thermal equilibrium, without need of any cha

B. Rosenstein, Tran Minh-Tien

The interrelation between disorder and interactions in two dimensional electron liquid is studied beyond weak coupling perturbation theory. Strong repulsion significantly reduces the electronic density of states on the Fermi level. This makes the electron liquid more rigid and strongly suppresses elastic scattering off impurities. As a result the weak locali

M. Malki, M. Micoulaut, F. Chaimbault, Y. Vaills

Ion conducting $(CaO)_x(SiO_2)_{1-x}$ glasses and melts show a threshold behaviour in dc conductivity near $x=x_t=0.50$, with conductivities increasing linearly at $x>x_t$. We show that the behaviour can be traced to a rigid ($x<0.50$) to floppy ($x>0.50$) elastic phase transition near $x=x_t$. In the floppy phase, conductivity enhancement is traced to incre

Matthieu Micoulaut

Classical molecular dynamics simulations are used to study the structure of densified germanium dioxide ($GeO_2$). It is found that the coordination number of germanium changes with increasing density (pressure) while pressure released systems do not exhibit a marked change in local structure as compared to the virgin system. The structural modification with

M. Zhang, L. You

We discuss a proposal for the efficient generation of the maximally entangled atomic N-GHZ state in a spinor-1 condensate by driving internal state atomic Raman transitions using (classical) laser fields. We illustrate the dynamics in terms of a quantum Zeno subspace, and identify the resultant atomic elastic collision in facilitating the deterministic entan

J. Sugiyama, J. H. Brewer, E. J. Ansaldo, B. Hitti

Magnetism of layered cobaltites Na$_x$CoO$_2$ with $x$ = 0.6 and 0.9 has been investigated by a positive muon spin rotation and relaxation ($μ^+$SR) spectroscopy together with magnetic susceptibility and specific heat measurements, using single crystal samples in the temperature range between 250 and 1.8 K. Zero-field (ZF-) $μ^+$SR measurements on Na$_{0.9}$

Kang-Hun Ahn, Hangmo Yi

Using an exactly solvable model, we study low-energy properties of a one-dimensional spinless electron fluid contained in a quantum-mechanically moving wire located in a static magnetic field. The phonon and electric current are coupled via Lorentz force and the eigenmodes are described by two independent boson fluids. At low energies, the two boson modes ar

Glenn H. Fredrickson, Henri Orland

We examine statistical field theories of polymeric fluids in view of performing numerical simulations. The partition function of these systems can be expressed as a functional integral over real density fields. The introduction of density field variables serves to decouple interactions among non-bonded monomers, and renders the resulting effective Hamiltonia

Ruben Costa-Santos

We review recent results concerning finite size corrections to the Ising model free energy on lattices with non-trivial topology and curvature. From conformal field theory considerations two distinct universal terms are expected, a logarithmic term determined by the system curvature and a scale invariant term determined by the system shape and topology. Both

Ralf Bulla, Ning-Hua Tong, Matthias Vojta

We describe the generalization of Wilson&#39;s Numerical Renormalization Group method to quantum impurity models with a bosonic bath, providing a general non-perturbative approach to bosonic impurity models which can access exponentially small energies and temperatures. As an application, we consider the spin-boson model, describing a two-level system couple

T. Lisker, U. Heber, R. Napiwotzki, N. Christlieb

We report on the analysis of high-resolution optical spectra for 77 subdwarf B (sdB) stars from the ESO Supernova Ia Progenitor Survey. Effective temperature, surface gravity, and photospheric helium abundance are determined simultaneously by spectral line profile fitting of hydrogen and helium lines, and are found to be in agreement with previous studies of

Julia C. Lee

Highlights of interesting astrophysical discoveries are reviewed in the context of high resolution X-ray spectroscopy made possible with Chandra and XMM-Newton, and its relevance to atomic physics calculations and measurements is discussed. These spectra have shown that the overlap between astrophysics and atomic physics is stronger than ever, as discoveries

Jason X. Prochaska

I introduce and review the data and analysis techniques used to measure abundances in the damped Lya systems, quasar absorption-line systems associated with galaxies in the early Universe. The observations and issues associated with their abundance analysis are very similar to those of the Milky Way&#39;s interstellar medium. We measure gas-phase abundances

Ray Jayawardhana

Brown dwarfs, which straddle the mass range between stars and planets, appear to be common both in the solar neighborhood and in star-forming regions. Their ubiquity makes the question of their origin an important one both for our understanding of brown dwarfs themselves as well as for theories on the formation of stars and planets. Studies of young sub-stel

Neal J. Evans, the c2d Team

The SIRTF mission and the Legacy programs will provide coherent data bases for extra-galactic and Galactic science that will rapidly become available to researchers through a public archive. The capabilities of SIRTF and the six legacy programs are described briefly. Then the cores to disks (c2d) program is described in more detail. The c2d program will use

T. Abu-Zayyad, C. C. H. Jui, E. C. Loh

Issues relating to extensive air showers observation by a space-borne fluorescence detector and the effects of clouds on the observations are investigated using Monte Carlo simulation. The simulations assume the presence of clouds with varying altitudes and optical depths. Simulated events are reconstructed assuming a cloud-free atmosphere. While it is antic

David G. Gilbank, Richard G. Bower, F. J. Castander, B. L. Ziegler

Data from a new, wide field, coincident optical and X-ray survey, the X-ray Dark Cluster Survey (XDCS) are presented. This survey comprises simultaneous and independent searches for clusters of galaxies in the optical and X-ray passbands. Optical cluster detection algorithms implemented on the data are detailed. Two distinct optically selected catalogues are

Letizia Stanghellini

Planetary Nebulae (PNs) in the Magellanic Clouds offer the unique opportunity to study both the population and evolution of low- and intermediate-mass stars, in an environment that is free of the distance scale bias and the differential reddening that hinder the observations of the Galactic sample. The study of LMC and SMC PNs also offers the direct comparis

D. Saumon, M. S. Marley, K. Lodders

We present an analysis of brown dwarf model spectra in the mid-infrared spectral region (5 - 20 microns), in anticipation of data obtained with the Space Infrared Telescope Facility. The mid-infrared spectra of brown dwarfs are in several ways simpler than those in the near-infrared and yet provide powerful diagnostics of brown dwarf atmospheric physics and

G. Hasinger

Deep X-ray surveys have shown that the cosmic X-ray background (XRB) is largely due to the accretion onto supermassive black holes, integrated over the cosmic time. These surveys have resolved more than 80% of the 0.1-10 keV X-ray background into discrete sources. Optical spectroscopic identifications show that the sources producing the bulk of the X-ray bac

Letizia Stanghellini

Magellanic Cloud Planetary Nebulae (PNs) offer insight of both the population and evolution of low- and intermediate-mass stars, in environments that are free of the distance bias and the differential reddening that hinder the observations of the Galactic sample. The study of LMC and SMC PNs also offers the direct comparison of stellar populations with diffe

F. Akimoto, K. Kondou, A. Furuzawa, Y. Tawara

The core region is dominated by three rich Abell clusters and two poor clusters. Their spatial distributions of gas temperature and metal abundance provide us with information on the interactions and motions of member clusters. From eight ASCA pointing observations, temperature, abundance, and X-ray luminosity for five member clusters are similar to the othe

Eamonn Kerins

I discuss current and future applications of pixel lensing: the microlensing of unresolved stars. Pixel lensing is the tool of choice for studying the Macho dark matter content of external galaxies like Andromeda (M31), and is at the heart of an ambitious new proposal to undertake a census of low-mass stars and brown dwarfs in the M31 bulge.

G. Nelemans

I review the expected Galactic sources of gravitational waves, concentrating on the low-frequency domain and summarise the current observational and theoretical knowledge we have. A model for the Galactic population of close binaries, which is tested against the observations is used to predict the expected signal for the future space based gravitational wave

Filippo Fraternali, Tom Oosterloo, Rense Boomsma, Rob Swaters

Recent, high sensitivity, HI observations of nearby spiral galaxies show that their thin `cold&#39; disks are surrounded by thick layers (halos) of neutral gas with anomalous kinematics. We present results for three galaxies viewed at different inclination angles: NGC891 (edge-on), NGC2403 (i=60 deg), and NGC6946 (almost face-on). These studies show the pres

N. R. Napolitano, M. Capaccioli, M. Arnaboldi, M. R. Merrifield

We have found a correlation betwen the M/L global gradients and the structural parameters of the luminous components of a sample of 19 early-type galaxies. Such a correlation supports the hypothesis that there is a connection between the dark matter content and the evolution of the baryonic component in such systems.

S. Garcia-Burillo, F. Combes, A. Eckart, L. J. Tacconi

The NUGA project is the first high-resolution (0.5&#39;&#39;-1&#39;&#39;) CO survey of low luminosity AGN including the full sequence of activity types (Seyfert 1--2 and LINERs). NUGA aims to study systematically the different mechanisms for gas fueling of the AGN. In order to reach the critical spatial scales for AGN feeding (<100 pc), we are undertaking hi

R. I. Hynes, P. A. Charles, L. van Zyl, A. Barnes

We present WHT and VLT spectroscopy of MM Ser, the optical counterpart to Ser X-1. We deblend the red spectra of the two close stars identified by Wachter (1997) and show that the brighter of the two is responsible for the Halpha and HeI emission, hence confirming that this is the true counterpart of the X-ray source. We also identify several HeII and NIII l

S. Borgani, G. Murante, V. Springel, A. Diaferio

We present results on the X-ray properties of clusters and groups of galaxies, extracted from a large hydrodynamical simulation. We used the GADGET code to simulate a LambdaCDM model within a box of 192 Mpc/h on a side, with 480^3 dark matter particles and as many gas particles. The simulation includes radiative cooling, star formation and supernova feedback

J. -P. Roques, S. Schanne, A. von Kienlin, J. Knödlseder

The SPI instrument has been launched on-board the INTEGRAL observatory on October 17, 2002. SPI is a spectrometer devoted to the sky observation in the 20 keV-8 MeV energy range using 19 germanium detectors. The performance of the cryogenic system is nominal and allows to cool the 19 kg of germanium down to 85 K with a comfortable margin. The energy resoluti

Stéphane Schanne, B. Cordier, M. Gros, D. Attié

SPI, the Spectrometer on board the ESA INTEGRAL satellite, to be launched in October 2002, will study the gamma-ray sky in the 20 keV to 8 MeV energy band with a spectral resolution of 2 keV for photons of 1 MeV, thanks to its 19 germanium detectors spanning an active area of 500 cm2. A coded mask imaging technique provides a 2 deg angular resolution. The 16

Peter Erwin, Juan Carlos Vega Beltran, Alister W. Graham, John E. Beckman

We present a detailed morphological, photometric, and kinematic analysis of two barred S0 galaxies with large, luminous inner disks inside their bars. We show that these structures, in addition to being geometrically disk-like, have exponential profiles (scale lengths $\sim$ 300--500 pc) distinct from the central, non-exponential bulges. We also find them to

D. J. Price, J. J. Monaghan

In this paper we show how a Lagrangian variational principle can be used to derive the SPMHD (smoothed particle magnetohydrodynamics) equations for ideal MHD. We also consider the effect of a variable smoothing length in the SPH kernels after which we demonstrate by numerical tests that the consistent treatment of terms relating to the gradient of the smooth

D. J. Price, J. J. Monaghan

In this paper we show how the Smoothed Particle Hydrodynamics (SPH) equations for ideal magnetohydrodynamics (MHD) can be written in conservation form with the positivity of the dissipation guaranteed. We call the resulting algorithm Smoothed Particle Magnetohydrodynamics (SPMHD). The equations appear to be accurate, robust and easy to apply and do not suffe

J. -Ch. Hamilton, A. Benoît, the Archeops Collaboration

\Archeops is a balloon--borne instrument dedicated to measuring cosmic microwave background (CMB) temperature anisotropies at high angular resolution ($\sim$ 12 arcmin.) over a large fraction (30%) of the sky in the (sub)millimetre domain (from 143 to 545 GHz). We describe the results obtained during the last flight: the \Archeops estimate of the CMB angular

J. -Ch. Hamilton

CMB data analysis is in general done through two main steps : map-making of the time data streams and power spectrum extraction from the maps. The latter basically consists in the separation between the variance of the CMB and that of the noise in the map. Noise must therefore be deeply understood so that the estimation of CMB variance (the power spectrum) i

V. Antonuccio-Delogu, U. Becciani, D. Ferro

FLY is a parallel treecode which makes heavy use of the one-sided communication paradigm to handle the management of the tree structure. In its public version the code implements the equations for cosmological evolution, and can be run for different cosmological models. This reference guide describes the actual implementation of the algorithms of the public

Yasmin Friedmann, Francois Bouchet

We are investigating to what extent one can use a P(D) analysis to extract number counts of unclustered sources from maps of the far infrared background. Currently available such maps, and those expected to emerge in near future are dominated by confusion noise due to poor resolution. We simulate background maps with an underlying two slope model for N(S) an

K. Gillmon, J. S. Sanders, A. C. Fabian

We present an X-ray absorption analysis of the high-velocity system (HVS) in NGC 1275 using results from a deep 200 ks Chandra observation. We are able to describe the morphology of the HVS in more detail than ever before. We present an HST image for comparison, and note close correspondence between the deepest X-ray absorption and the optical absorption. A

A. Usero, S. Garcia-Burillo, A. Fuente, J. Martin-Pintado

We have studied the feedback influence that the central engine of the Seyfert 2 galaxy NGC 1068 may have on the chemistry of the 200 pc circumnuclear gas disk (CND). With this purpose, we have conducted a multi-species/multi-transition survey of molecular gas in the CND of NGC 1068 using the IRAM 30m telescope. Abundances of several molecular species have be

M. Srinivasa Rao, Sujan Sengupta

The mean intensity of planetary nebulae with an expanding atmosphere is modeled by considering dusty and dust-free atmospheres. The bulk matter density is determined from the adopted velocity field through the equation of continuity. The gas is assumed to consist of hydrogen and helium and the gas-to-dust mass ratio is taken to be $3\times10^{-4}$. The Rayle

X. Dupac, J. -P. Bernard, N. Boudet, M. Giard

We present a compilation of PRONAOS-based results concerning the temperature dependence of the dust submillimeter spectral index, including data from Galactic cirrus, star-forming regions, dust associated to a young stellar object, and a spiral galaxy. We observe large variations of the spectral index (from 0.8 to 2.4) in a wide range of temperatures (11 to

H. Jerjen, Bruno Binggeli, Fabio D. Barazza

We have employed FORS1/2+VLT to acquire deep B and R CCD images of 16 dwarf elliptical galaxies in the direction of the Virgo cluster. For each dwarf we measure the R-band surface brightness fluctuation (SBF) magnitude \bar{m}_R and the (B-R) colour in a number of fields at different galactocentric distances. From the field-to-field variation of the two quan

S. C. Ellis, L. R. Jones

K band observations of the galaxy populations of three high redshift (z=0.8-1.0), X-ray selected, massive clusters are presented. The observations reach a depth of K=21.5, corresponding to K*+3.5 mag. The evolution of the galaxy properties are discussed in terms of their K band luminosity functions and the K band Hubble diagram of brightest cluster galaxies.

M. Ruderman

A young neutron star with large spin-down power is expected to be closely surrounded by an e+/- pair plasma maintained by the conversion of gamma-rays associated with the star&#39;s polar-cap and/or outer-gap accelerators. Cyclotron-resonance scattering by the e- and e+ within several radii of such neutron stars prevents direct observations of thermal X-rays

Stirling A. Colgate, Renyue Cen, Hui Li, Nathan Currier

A scenario is put forth for the formation of supermassive black holes at the centers of galaxies. It depends upon the formation of a Mestel disk with a flat rotation curve, where the mass is proportional to r and thickness to 1/r. Such disks should form from the collapse of uniformly rotating, isolated, gaseous clouds, either proto-galactic, galaxy-mass damp

A. Fotopoulos, A. A. Tseytlin

We consider open superstring partition function Z on the disc in time-dependent tachyon background T= f(x_i) e^{m x_0} where the profile function f depends on spatial coordinates. We compute Z to second order in derivatives of f and compare the result with some previously suggested effective actions depending only on the first derivatives of the tachyon fiel

J. A. Aguilar-Saavedra, G. C. Branco, F. R. Joaquim

We introduce a parametrization of the effects of radiative corrections from new physics on the charged lepton and neutrino mass matrices, studying how several relevant quantities describing the pattern of neutrino masses and mixing are affected by these corrections. We find that the ratio omega = sin theta / tan theta_atm is remarkably stable, even when rela

M Tegmark, M Blanton, M Strauss, F Hoyle

We measure the large-scale real-space power spectrum P(k) using a sample of 205,443 galaxies from the Sloan Digital Sky Survey, covering 2417 square degrees with mean redshift z~0.1. We employ a matrix-based method using pseudo-Karhunen-Loeve eigenmodes, producing uncorrelated minimum-variance measurements in 22 k-bands of both the clustering power and its a

M. Tegmark, M. Strauss, M. Blanton, K. Abazajian

We measure cosmological parameters using the three-dimensional power spectrum P(k) from over 200,000 galaxies in the Sloan Digital Sky Survey (SDSS) in combination with WMAP and other data. Our results are consistent with a ``vanilla&#39;&#39; flat adiabatic Lambda-CDM model without tilt (n=1), running tilt, tensor modes or massive neutrinos. Adding SDSS inf

Gianluca Calcagni

In the context of an inflationary Randall-Sundrum Type II braneworld (RS2) we calculate spectral indices and amplitudes of cosmological scalar and tensor perturbations, up to second order in slow-roll parameters. Under very simple assumptions, extrapolating next-order formulae from first-order calculations in the case of a de Sitter brane, we see that the de

Nissim Kanekar, Jayaram N Chengalur

We describe a new technique to measure variations in the fundamental parameters $α$ and $y \equiv m_e/m_p$, using the sum of the frequencies of cm-wave OH ``main&#39;&#39; lines. The technique is $\sim$ three orders of magnitude more sensitive than that of Chengalur & Kanekar (2003), which utilised only the four 18cm OH lines. The increase in sensitivity ste

Nissim Kanekar, Ravi Subrahmanyan, Jayaram N. Chengalur, Vicky Safouris

We report high spectral resolution Australia Telescope Compact Array HI 21 cm observations resulting in the detection of the warm neutral medium (WNM) of the Galaxy in absorption against two extragalactic radio sources, PKS 1814-637 and PKS 0407-658. The two lines of sight were selected on the basis of the simplicity of their absorption profiles and the stre

Mateusz Ruszkowski, Marcus Bruggen, Mitchell C. Begelman

We simulate the effects of viscous dissipation of waves that are generated by AGN activity in clusters of galaxies. We demonstrate that the amount of viscous heating associated with the dissipation of these waves can offset radiative cooling rates in cooling flow clusters of galaxies. This heating mechanism leads to spatially distributed and approximately sy

A. Aguayo, I. I. Mazin, D. J. Singh

Ni$_3$Al and Ni$_3$Ga are closely related materials on opposite sides of a ferromagnetic quantum critical point. The Stoner factor of Ni is virtually the same in both compounds and the density of states is larger in Ni$_3$Ga. So, according to the Stoner theory, it should be more magnetic, and, in LDA calculations, it is. However, experimentally, it is a para

Michael L. Norman, Brian W. O&#39;Shea, Pascal Paschos

We examine the dynamical evolution and statistical properties of the supernova ejecta of massive primordial stars in a cosmological framework to determine whether this first population of stars could have enriched the universe to the levels and dispersions seen by the most recent observations of the Lyman-Alpha forest. We evolve a lambda CDM model in a 1 Mpc

Sukanta Basu, Efi Foufoula-Georgiou, Fernando Porté-Agel

Fractal Interpolation has been proposed in the literature as an efficient way to construct closure models for the numerical solution of coarse-grained Navier-Stokes equations. It is based on synthetically generating a scale-invariant subgrid-scale field and analytically evaluating its effects on large resolved scales. In this paper, we propose an extension o

M. Serone, M. Trapletti

A precise correspondence between freely-acting orbifolds (Scherk-Schwarz compactifications) and string vacua with NSNS flux turned on is established using T-duality. We focus our attention to a certain non-compact Z_2 heterotic freely-acting orbifold with N=2 supersymmetry (SUSY). The geometric properties of the T-dual background are studied. As expected, th

C. Henkel, M. Nest, P. Domokos, R. Folman

We propose an optical ring interferometer to observe environment-induced spatial decoherence of massive objects. The object is held in a harmonic trap and scatters light between degenerate modes of a ring cavity. The output signal of the interferometer permits to monitor the spatial width of the object&#39;s wave function. It shows oscillations that arise fr

Ralph Blumenhagen

Supersymmetric orientifolds of four dimensional Gepner Models are constructed in a systematic way. For all levels of the Gepner model being odd the generic expression for both the A-type and the B-type Klein bottle amplitude is derived. The appearing massless tadpoles are canceled by introducing appropriate boundary states of Recknagel/Schomerus(RS). After d

Nikolaos Kidonakis, Alexander Belyaev

We calculate flavor-changing neutral-current (FCNC) processes involving top-quark production via anomalous tqV couplings at the Tevatron and HERA colliders. We cover the FCNC processes p pbar -> t Z, p pbar -> t gamma, p pbar -> t t, and e p -> e t. We go beyond leading order and include the effects of soft-gluon corrections through next-to-next-to-leading o

R. Lisboa, M. Malheiro, A. S. de Castro, P. Alberto

A generalized relativistic harmonic oscillator for spin 1/2 particles is studied. The Dirac Hamiltonian contains a scalar $S$ and a vector $V$ quadratic potentials in the radial coordinate, as well as a tensor potential $U$ linear in $r$. Setting either or both combinations $Σ=S+V$ and $% Δ=V-S$ to zero, analytical solutions for bound states of the correspon

Jatush V. Sheth

We measure the geometry, topology and morphology of the superclusters in mock SDSS catalogues prepared by Cole et al.(1998). The mock catalogues refer to $τ$CDM and $Ł$CDM {\em flat} cosmological models and are populated by galaxies so that these act as biased tracers of mass, conforming with the correlation function measured using APM catalogue. We compute

Sandra Marcello

We show that the set of periods of an automorphism of the affine plane defined over a $p$-adic field is bounded above by a constant independent from the automorphism. We deduce from this result a new proof in arithmetic dynamics of the Silverman&#39;s conjecture in dimension 2.

Maciej Horowski, Goce Chadzitaskos, Anatol Odzijewicz, Agnieszka Tereszkiewicz

We present exact solutions of a class of models, which describe the parametric down conversion of photons. The Hamiltonians of this models are related to the classes of finite orthogonal polynomials. The spectra and explicit expressions for eigenvectors of this Hamiltonians are obtained.

J. M. Isidro

On classical phase spaces admitting just one complex-differentiable structure, there is no indeterminacy in the choice of the creation operators that create quanta out of a given vacuum. In these cases the notion of a quantum is universal, i.e., independent of the observer on classical phase space. Such is the case in all standard applications of quantum mec

P. Muehlich, T. Falter, U. Mosel

We investigate inclusive omega photoproduction off complex nuclei, concentrating on the feasibility to examine a possible in-medium change of the omega meson properties by observing the pi^0 gamma invariant mass spectrum. The simulations are performed by means of a BUU transport model including a full coupled-channel treatment of the final state interactions

T. Prager, L. Schimansky-Geier

We study a non Markovian three state model, subjected to an external periodic signal. This model is intended to describe an excitable systems with periodical driving. In the limit of a small amplitude of the external signal we derive expressions for the spectral power amplification and the signal to noise ratio as well as for the inter-spike interval distrib

B. Militello, P. Aniello, A. Messina

A novel result concerning Raman coupling schemes in the context of trapped ions is obtained. By means of an operator perturbative approach, it is shown that the complete time evolution of these systems (in the interaction picture) can be expressed, with a high degree of accuracy, as the product of two unitary evolutions. The first one describes the time evol

Alfred Rosenberg, Alejandra Recio-Blanco, Macarena Garcia-Marin

We present BV photometry centered on the globular cluster M54 (NGC 6715). The color-magnitude diagram clearly shows a blue horizontal branch extending anomalously beyond the zero age horizontal branch theoretical models. These kinds of horizontal branch stars (also called ``blue hook&#39;&#39; stars), which go beyond the lower limit of the envelope mass of c

M. Balasubramaniam, S. Kumarasamy, N. Arunachalam, Raj K. Gupta

A new semiempirical formula, with only three parameters, is proposed for cluster decay half-lives. The parameters of the formula are obtained by making a least square fit to the available experimental data. The calculated half-lives are compared with an other model-independent scaling law proposed earlier by Horoi {\it et al}. Also, the calculated results of

J. E. Prieto, I. Markov

The wetting of the homogeneously strained wetting layer by dislocation-free three-dimensional islands belonging to an array has been studied. The array has been simulated as a chain of islands in 1+1 dimensions. It is found that the wetting depends on the density of the array, the size distribution and the shape of the neighbor islands. Implications for the

V. P. Mineev

The linear equations for transverse spin dynamics in weakly polarised degenerate Fermi liquid with arbitrary relationship between temperature and polarization are derived from Landau-Silin phenomenological kinetic equation with general form of two-particle collision integral. The temperature and polarization dependence of the spin current relaxation time is

Sameer M. Ikhdair, Ramazan Sever

We calculate the $c\bar{b}$ mass spectrum, the splitting values and some other properties in the framework of the semi-relativistic equation by applying the shifted large-N expansion technique. We use seven different central potentials together with an improved QCD-motivated interquark potentials calculated to two loops in the modified minimal-subtraction $%

Tohru Eguchi, Hiroaki Kanno

We apply the method of geometric transition and compute all genus topological closed string amplitudes compactified on local {\bf F}_0 by making use of the Chern-Simons gauge theory. We find an exact agreement of the results of our computation with the formula proposed recently by Nekrasov for {\cal N}=2 SU(2) gauge theory with two parameters βand \hbar. βis

Giuseppe Luca Celardo, Carlos Pineda, Marko Žnidarič

We analyze the influence of errors on the implementation of the quantum Fourier transformation (QFT) on the Ising quantum computer (IQC). Two kinds of errors are studied: (i) due to spurious transitions caused by pulses and (ii) due to external perturbation. The scaling of errors with system parameters and number of qubits is explained. We use two different

Hwang Lee, Ulvi H. Yurtsever, Pieter Kok, George M. Hockney

We study the properties of a photodetector that has a number-resolving capability. In the absence of dark counts, due to its finite quantum efficiency, photodetection with such a detector can only eliminate the possibility that the incident field corresponds to a number of photons less than the detected photon number. We show that such a {\em non-photon} num

Guo-Ping Guo, Guang-Can Guo

Here we present an experimentally feasible scheme to entangle flying qubit (individual photon with polarization modes) and stationary qubit (atomic ensembles with long-lived collective excitations). This entanglement integrate two different species can act as a critical element for the coherent transform of quantum information between flying and stationary q

Peng Xue, Guang-Can Guo

We describe an experimental scheme of preparing multipartite W class of maximally entangled states between many atomic ensembles. The scheme is based on laser manipulation of atomic ensembles and single-photon detection, and well fits the status of the current experimental technology. In addition, we show one of the applications of the kind of W class states

G. Geloni, E. Saldin, E. Schneidmiller, M. Yurkov

As a consequence of motions driven by external forces, self-fields originate within an electron bunch, which are different from the static case. In the case of magnetic external forces acting on an ultrarelativistic beam, the longitudinal self-interactions are responsible for CSR (Coherent Synchrotron Radiation)-related phenomena, which have been studied ext

Martin Erik Horn, Helmut F. Mikelskis

Holography as a subject is neglected largely in current physics lessons and in school books. Even though this topic might be complex, it is applicable and viable in the world that we live in. Holography lends itself to further develop knowledge with regard to inference optics. However, misconceptions of students impede the learning process. Research conducte

Ilya V. Shadrivov, Andrey A. Sukhorukov, Yuri S. Kivshar, Alexander A. Zharov

We study both linear and nonlinear surface waves localized at the interface separating a left-handed medium (i.e. the medium with both negative dielectric permittivity and negative magnetic permeability) and a conventional (or right-handed) dielectric medium. We demonstrate that the interface can support both TE- and TM-polarized surface waves - surface pola

B. Julia-Diaz, A. Valcarce, P. Gonzalez, F. Fernandez

By means of a NN to NN*(1440) transition potential derived in a parameter-free way from a quark-model based NN potential, we determine simultaneously the $πNN^*(1440)$ and $σNN^*(1440)$ coupling constants. We also present a study of the target Roper excitation diagram contributing to the $p(d,d&#39;)$ reaction.

V. G. Nosov, A. M. Kamchatnov

A consistent theory is developed of the volume energy oscillations of spherical nuclei due to sharpness of the Fermi distribution boundary for quasiparticles. The lowest value of the oscillating part of the energy corresponds to a magic nucleus. A formula is obtained for the corresponding limiting momentum of a quasiparticle and it is shown that we have here

J. L. Lecouey

The three-body description of two-neutron halo nuclei relies on the two-body interactions between the constituents. In order to provide constraints on calculations devoted to $^{14}$Be and $^{17}$B, neutron unbound states of $^{13}$Be and $^{16}$B have been investigated by one-proton knockout. The experimental techniques and results are discussed here.

P. Winter, H. -H. Adam, A. Budzanowski, R. Czyzykiewicz

Motivated by the ongoing discussion concerning the nature of the scalar resonances f0(980) and a0(980), the COSY-11 collaboration has taken exclusive data on the pp->ppK+K- reaction near the production threshold. A first total cross section sigma=(1.80+-0.27+0.28-0.35)nb for the excess energy Q=17 MeV has been determined. In contrary to the eta, omega and et

J. Kiener, M. Gros, V. Tatischeff, D. Attie

Gamma-ray angular distributions for the resonances at Ep = 550 keV and 1747 keV of the radiative capture reaction 13-C(p,g)14-N have been measured, using intense proton beams on isotopically pure 13-C targets. Relative intensities for the strongest transitions were extracted with an accuracy of typically five per cent, making these resonances new useful gamm