November 2001 arXiv papers — page 13

M. Kachelriess

The level-crossing probability, local and global adiabaticity conditions are discussed for 2-flavour neutrino oscillations in matter with arbitrary mixing angle $θ$. Different approximations for the survival probability of supernova neutrinos are compared. Results of a combined likelihood analysis of the observed SN1987A neutrino signal and of the latest sol

Steven D. Bass

We emphasise the relation between the spin structure of the proton and the axial U(1) problem. New experiments motivated by the proton spin problem which could shed light on the nature of U(1) symmetry breaking in QCD are discussed.

J. P. Ma

In the heavy quark limit inclusive production rate of a heavy meson can be factorized, in which the nonperturbative effect related to the heavy meson can be characterized by matrix elements defined in the heavy quark effective theory. Using this factorization, predictions for the full spin density matrix of a spin-1 and spin-2 meson can be obtained and they

U. Cotti, L. Diaz-Cruz, C. Pagliarone, E. Vataga

We study the prospects to detect at hadron colliders the Lepton Flavour Violating Higgs decay H --> tau mu, which can reach substantial branching fractions in several extensions of the SM. Among them, the generic two higgs doublet model can be taken as a representative case where B.R.(H --> tau mu) can reach values of order 10^-1-10^-2. Bounds on the LFV fac

N. N. Nikolaev

A brief review of the modern QCD theory of diffractive DIS is given. The recent progress has been remarkably rapid, all the principal predictions from the color dipole approach to diffraction - the $(Q^2+m_V^2)$ scaling, the pattern of SCHNC, shrinkage of the diffraction cone in hard diffractive DIS, the strong impact of longitudinal gluons in inclusive $J/Ψ

A. Hebecker

It is the aim of this talk to review our understanding of the high-energy limit of QCD, focussing, in particular, on recent theoretical developments. After a brief introduction, I will recall why the true high-energy limit of QCD scattering processes is genuinly non-perturbative and why it has so far not been possible to apply lattice methods to this type of

P. Bialas, J. Wosiek

We present new results of the quenched simulations of the reduced D=4 supersymmetric Yang - Mills quantum mechanics for larger gauge groups SU(N), 2<N<9. The model, studied at finite temperature, reveals existence of the two distinct regions which may be precursors of a black hole and the elementary D0 branes phases of M-theory conjectured in the literature.

C. -J. D. Lin, G. Martinelli, C. T. Sachrajda, M. Testa

In this talk we discuss finite-volume computations of two-body hadronic decays below the inelastic threshold (e.g. $K\toππ$ decays). In particular we show how the relation between finite-volume matrix elements and physical amplitudes, recently derived by Lellouch and Lüscher, can be extended to all elastic states under the inelastic threshold. We also provid

H1 Calorimeter Group, E. Barrelet

The ionization probes used for monitoring the liquid argon purity in the H1 calorimeter are described and results of their operation in tests at CERN and during the period 1992 to the end of 1998 at HERA are given. The high sensitivity of the charge measurements leads to refined charge collection models, and to the observation of a variation of the ionizatio

D. Yu. Bolkhovityanov, R. G. Gromov, I. L. Pivovarov, A. A. Starostenko

Modern PC workstations often provide more CPU power than required for most control applications. On the other hand, the screen space is always in short supply. One possible solution is to use more PCs, but in fact we need only more screens, not more keyboards, mice etc. PC architecture allows using more than one videocard, and X Window protocol is also aware

Carmine Pagliarone, Elena Vataga

We present the most recent results of searches for physics beyond the Standard Model using the CDF and the D$\not$O detector at the Fermilab Tevatron Collider. All results shown correspond to analysis performed using the past 1992-1996 Fermilab Tevatron run I data (roughly 110 $pb^{-1}$ per each experiment). In particular we report on searches for scalar top

Ulrik Egede

The D0 meson can decay to the wrong sign K+pi- state either through a doubly Cabibbo suppressed decay or via mixing to the D0bar state followed by the Cabibbo favoured decay D0bar -> K+ pi-. We measure the rate of wrong sign decays relative to the Cabibbo favoured decay to (0.383 +- 0.044 +- 0.022)% and give our sensitivity to a mixing signal.

Nathalie Deruelle

We consider spherically symmetric matter configurations on a four dimensional &#34;brane&#34; embedded in a five dimensional $Z_2$-symmetric &#34;bulk&#34;. We write the junction conditions between the interior and exterior of these &#34;stars&#34;, treat a couple of static examples in order to point out the differences with ordinary four dimensional Einstei

S. C. Tiwari

The nature of time vis-a-vis relativity is critically examined. Based on the author&#39;s space-time interaction hypothesis of late 1970&#39;s, cosmological model with time-varying velocity of light is discussed.

Masafumi Seriu

We study a fundamental issue in cosmology: Whether we can rely on a cosmological model to understand the real history of the Universe. This fundamental, still unresolved issue is often called the ``model-fitting problem (or averaging problem) in cosmology&#39;&#39;. Here we analyze this issue with the help of the spectral scheme prepared in the preceding stu

M. N. Vyalyi

In this paper we consider the computational complexity of the following problem. Let $f$ be a Boolean polynomial. What value of $f$, 0 or 1, is taken more frequently? The problem is solved in polynomial time for polynomials of degrees 1,2. The next case of degree 3 appears to be PP-complete under polynomial reductions in the class of promise problems. The pr

Samuel Ieong, Ming-Yang Kao, Tak-Wah Lam, Wing-Kin Sung

The paper investigates the computational problem of predicting RNA secondary structures. The general belief is that allowing pseudoknots makes the problem hard. Existing polynomial-time algorithms are heuristic algorithms with no performance guarantee and can only handle limited types of pseudoknots. In this paper we initiate the study of predicting RNA seco

M. E. Portnoi, I. Galbraith

The degree of ionisation of a two-dimensional electron-hole plasma is calculated in the low-density (Boltzmann) limit. The electron-hole interaction is considered for all states: optically active and inactive, bound and unbound. The theory is applied to exciton/free-carrier plasma in GaN-based quantum wells at room temperature.

J. Sirker, A. Klümper, K. Hamacher

The purpose of this paper is to investigate the ground-state properties of two-dimensional Heisenberg models on a square lattice with a given dimerization. Our aim is threefold: First, we want to investigate the dimensional transition from two to one dimension for three models consisting of weakly coupled chains for large dimerizations. Simple scaling argume

V. V. Nikolaev, M. E. Portnoi, I. Eliashevich

A numerical method based on the transfer matrix technique is developed to calculate the luminescence spectra of complex layered structures with photon recycling. Using this method we show a strong dependence of the emission spectra on the optical eigenmode structure of the device. The enhancement of the photon recycling and the LED external efficiency can be

D. A. Papaconstantopoulos, M. J. Mehl

We study superconductivity in Boron using first-principles LAPW calculations, the rigid-muffin-tin approximation and the McMillan theory. Our results point to an electron-phonon mechanism producing transition temperatures near 10K at high pressures in agreement with recent measurements.

V. V. Nikolaev, M. E. Portnoi

We study thermodynamic properties of spatially separated electron-hole plasma in double-layered systems using Green function formalism. The screening of the Coulomb interaction is considered in the framework of Thomas-Fermi approximation, and a qualitatively new mechanism of screening by indirect excitons is taken into account. The exciton density is shown t

Himadri S. Chakraborty, Rashid G. Nazmitdinov, Mohamed E. Madjet, Jan-M. Rost

We demonstrate that the current of photoelectrons from a quantum dot exhibits oscillations as a function of the photon energy owing to the predominant ionization from the dot boundary. In the Fourier reciprocal space of the photoelectron wave vector these oscillations reveal frequencies connected to the confinement range. We attribute the oscillation in the

V. M. Apalkov, M. E. Portnoi

We predict a double-resonant feature in the magnetic field dependence of the phonon-mediated mobility of a two-subband quasi-two-dimensional electron system. These resonances take place when two Landau levels corresponding to different size-quantized subbands are close to each other but do not coincide. We also discuss the effect of non-equilibrium phonons.

R. G. Nazmitdinov, N. S. Simonovic, Jan M. Rost

While the dynamics for three-dimensional axially symmetric two-electron quantum dots with parabolic confinement potentials is in general non-separable we have found an exact separability with three quantum numbers for specific values of the magnetic field. Furthermore, it is shown that the magnetic properties such as the magnetic moment and the susceptibilit

Ruixing Liang, D. A. Bonn, W. N. Hardy, Janice C. Wynn

High-purity and homogeneous YBa2Cu3Oy single crystals with carrier doping level near the AFM-SC boundary have been obtained in the oxygen content range between y = 6.340 and 6.370. The crystals are ortho-II phase at room temperature and undergo the orthorhombic to tetragonal transition at about 140_Degree_C. They show sharp superconducting transitions, with

V. M. Apalkov, M. E. Portnoi

In this work we study the properties of a two-subband quasi-two-dimensional electron system in a strong magnetic field when the electron filling factor is equal to four. When the cyclotron energy is close to the intersubband splitting the system can be mapped onto a four-level electron system with an effective filling factor of two. The ground state is eithe

V. M. Apalkov, M. E. Portnoi

We study the many-body effects in a two-subband quasi-two-dimensional electron system in a quantizing magnetic field at filling factor three. A manifestation of these effects in the phonon absorption spectroscopy is discussed. The electron system is mapped onto a two-level system with the separation between levels determined by the intersubband splitting and

A. Smogunov, A. Dal Corso, E. Tosatti

The lowest conductance step for a Ni nanocontact is anomalously small in comparison with the large expected number of conducting channels. We present electronic structure calculations for an extremely idealized Ni nanobridge consisting of just a monatomic nanowire. Our calculations show that no less than eight single spin bands cross the Fermi level in a non

J. Mur-Petit, A. Polls, H. -J. Schulze

We analyze the possibilities of pairing between two different fermion species in asymmetric matter at low density. While the direct interaction allows pairing only for very small asymmetries, the pairing mediated by polarization effects is always possible, with a pronounced maximum at finite asymmetry. We present analytical results up to second order in the

J. P. de Lima, L. L. Goncalves

The dynamic susceptibility $χ_{Q}^{zz}(ω)$ of the isotropic XY-model (s=1/2) on the alternating superlattice (closed chain) in a transverse field $h$ is obtained exactly at arbitrary temperatures. It is determined from the results obtained for the dynamic correlations $<S_{jn}^{z}(t)S_{lm}^{z}(0)>$, which have been calculated by introducing the generalized J

E. P. Stoll, P. F. Meier, T. A. Claxton

Point-ion models have been extensively used to determine &#34;hole numbers&#34; at copper and oxygen sites in high-temperature superconducting cuprate compounds from measured nuclear quadrupole frequencies. The present study assesses the reliability of point-ion models to predict electric field gradients accurately and also the implicit assumption that the v

Slaven Barisic, Ivana Mrkonjic, Ivan Kupcic

The strong, electronically induced anomaly in the spectrum of the longitudinal optical (LO) phonons propagating along the main axes of the CuO$_2$ plane is tentatively attributed to the oxygen-oxygen charge transfer between the two oxygens in the plane. It is argued that this charge transfer can be large and that it is strongly coupled to the zone boundary L

A. Cochard, L. Bureau, T. Baumberger

This paper presents the stability analysis of a system sliding at low velocities ($< 100 μ$m.s$^{-1}$) under a periodically modulated normal load, preserving interfacial contact. Experiments clearly evidence that normal vibrations generally stabilize the system against stick-slip oscillations, at least for a modulation frequency much larger than the stick-sl

Th. A. Maier, Th. Pruschke, M. Jarrell

We discuss spectra calculated for the 2D Hubbard model in the intermediate coupling regime with the dynamical cluster approximation, which is a non-perturbative approach. We find a crossover from a normal Fermi liquid with a Fermi surface closed around the Brillouin zone center at large doping to a non-Fermi liquid for small doping. The crossover is signalle

E. K. O. Hellén, M. J. Alava

Persistence is considered in diffusion--limited cluster--cluster aggregation, in one dimension and when the diffusion coefficient of a cluster depends on its size $s$ as $D(s) \sim s^γ$. The empty and filled site persistences are defined as the probabilities, that a site has been either empty or covered by a cluster all the time whereas the cluster persisten

V. M. Apalkov, M. E. Portnoi

We consider a line-shape of magnetoexciton photoluminescence from quantum wells when the disorder is sufficiently small. In this case the phonon-assisted optical transitions become important for the line formation. We study both inter-band and intra-band excitons. For inter-band excitons the width of a single peak emission line is calculated as a function of

H. Suderow, E. Bascones, A. Izquierdo, F. Guinea

We present high resolution tunneling spectroscopy data at very low temperatures on superconducting nanostructures of lead built with an STM. By applying magnetic fields, superconductivity is restricted to length scales of the order of the coherence length. We measure the tunneling conductance and analyze the phonon structure and the low energy DOS. We demons

J. Schmiegel, M. Greiner

We present a dynamical log-stable process for the spatio-temporal evolution of the energy-dissipation field in fully developed turbulence. The process is constructed from multifractal scaling relations required for two-point correlators of arbitrary order. n-point correlation functions are calculated analytically and interpreted in terms of generalised fusio

W. Prellier, Ph. Lecoeur, B. Mercey

Mixed-valence perovskite manganites (Re$_{1-x}$A$_{x}$MnO$_{3}$ where Re=rare earth, A=alkaline earth) provide a unique opportunity to study the relationships between the structure and the magnetotransport properties due to an interplay among charge carriers, magnetic coupling, orbital ordering and structural distortion. This makes these compounds very excit

Z. Tavassoli, R. P. Sear

Homogeneous nucleation of the new phase of one transition near a second phase transition is considered. The system has two phase transitions, we study the nucleation of the new phase of one of these transitions under conditions such that we are near or at the second phase transition. The second transition is an Ising-like transition and lies within the coexi

Ajay Nandgaonkar, D. G. Kanhere, Nandini Trivedi

We study the phase diagram of flux lines in superconductors with columnar pins. Based on numerical exact diagonalisation simulations on small clusters, we get two phases of vortices: A low temperature pinned glass with diverging tilt modulus and a high temperature delocalised entangled vortex liquid. For random potential disorder we find a new phase transiti

Shi-Jian Gu, You-Quan Li, Zu-Jian Ying

On the basis of Bethe ansatz solution of one dimensional SU(4) Hubbard-like model, we study its thermodynamics properties by means of Yang-Yang thermodynamics Bethe ansatz. The Landé $g$ factor is taken into account so as to describe electrons with orbital degeneracy. The free energy at low temperature is given and the specific heat both in strong coupling a

Lorenzo Fortunato

An evolving yeast colony is simulated by means of a cellular automaton that takes care of many important features of the system under study. A complete survey of the properties of the colony is done and a set of scaling relations is found, together with the analysis of the critical exponents. The Family-Vicsek relation between them is verified to a good accu

Keshav N. Shrivastava

There are surface modes on the Bose-Einstein condensed Na atoms so that the number of vortices diverges when the stirring frequency becomes equal to that of the surface waves. We introduce the finite life time of the surface modes so that the number of vortices becomes finite. Usually the number of vortices is a linear function of the stirring frequency. We

Akira Koyama, Takashi Yamamoto, Koji Fukao, Yoshihisa Miyamoto

Molecular process of crystallization from an oriented amorphous state was reproduced by molecular dynamics simulation for a realistic polyethylene model. Initial oriented amorphous state was obtained by uniaxial drawing an isotropic glassy state at 100 K. By the temperature jump from 100 K to 330 K, there occurred the crystallization into the fiber structure

I. P. McCulloch, A. Juozapavicius, A. Rosengren, M. Gulacsi

Using a non-Abelian density matrix renormalization group method we determine the phase diagram of the Kondo lattice model in one dimension, by directly measuring the magnetization of the ground-state. This allowed us to discover a second ferromagnetic phase missed in previous approaches. The phase transitions are found to be continuous. The spin-spin correla

M. Pissas, G. Kallias, M. Hofmann, D. M. Többens

We studied the crystal and magnetic structure of the La$_{1-x}$Ca$_{x}$MnO$_{3}$ compound for $x=0.8$ and $x=0.85$. At T=300 K both samples are paramagnetic with crystallographic symmetry $Pnma$. At low temperatures they undergo a monoclinic distortion from orthorhombic $Pnma$-type structure with $a_p\sqrt{2}\times 2a_p\times a_p\sqrt{2}$ to a monoclinic str

M. J. Qin, G. Li, H. K. Liu, S. X. Dou

The magnetic levitation forces of a superconducting disk (SC) levitated by a cylindrical permanent magnet (PM) have been calculated from first principles for superconductors with finite thickness. The current $j(ρ,z)$ and field $B(ρ,z)$ profiles in the SC in the non-uniform magnetic field generated by the PM have been derived. The levitation force is observe

N. L. Bobrov, P. N. Chubov, Yu. G. Naidyuk, L. V. Tyutrina

The superconducting order parameter and electron-phonon interaction (EPI) in a MgB$_{2}$ c-axis oriented thin film are investigated by point contacts (PCs). Two superconducting gaps $Δ_{Small}\approx 2.6$ meV and $Δ_{Large}\approx 7.4$ meV have been established, which fairly well correspond to the theoretical gap ratio 1:3. The reconstructed PC EPI function

V. Meden, W. Metzner, U. Schollwoeck, K. Schoenhammer

Using a fermionic renormalization group method we present a simple real space picture of the strong influence an impurity has on the electronic properties of a Luttinger liquid. We compute the flow of the renormalized impurity potential for a single impurity over the entire energy range - from the microscopic scale of a lattice-fermion model down to the low-

Niels Asger Mortensen, Karsten Flensberg, Antti-Pekka Jauho

Quasiballistic 1D quantum wires are known to have a conductance of the order of 2e^2/h, with small sample-to-sample fluctuations. We present a study of the transconductance G_12 of two Coulomb-coupled quasiballistic wires, i.e., we consider the Coulomb drag geometry. We show that the fluctuations in G_12 differ dramatically from those of the diagonal conduct

S. Anantha Ramakrishna, N. Kumar

We re-examine and correct an earlier derivation of the distribution of the Wigner phase delay time for wave reflection from a long one-dimensional disordered conductor treated in the continuum limit. We then numerically compare the distributions of the Wigner phase delay time and the dwell time, the latter being obtained by the use of an infinitesimal imagin

C. S. Kochanek, N. Dalal

The properties of multiple image gravitational lenses require a fractional surface mass density in satellites of f=0.02 (0.006 < f < 0.07 at 90% confidence) that is consistent with the expectations for CDM. The characteristic satellite mass scale, 10^6-10^9 Msun, is also consistent with the expectations for CDM. The agreement between the observed and expecte

M. Douspis, P. G. Ferreira

The angular power spectrum of the Cosmic Microwave Background has been measured out to sufficiently small angular scale to encompass a few acoustic oscillations. We use a phenomenological fit to the angular power spectrum to quantify the statistical significance of these oscillations and discuss the cosmological implications of such a finding.

Martino Romaniello, Nino Panagia, Salvatore Scuderi, Robert P. Kirshner

We present a new technique based on multi-band near ultraviolet and optical photometry to measure both the stellar intrinsic properties, ie luminosity and effective temperature, and the interstellar dust extinction along the line of sight to hundreds of stars per square arcminute. The yield is twofold. On the one hand, the resulting reddening map has a very

Woong-Tae Kim, Eve C. Ostriker

Intermediate-scale spurs are common in spiral galaxies, but perhaps most distinctively evident in a recent HST image of M51 (Scoville & Rector 2001). We investigate, using time-dependent numerical MHD simulations, how such spurs could form (and subsequently fragment) from the interaction of a gaseous ISM with a stellar spiral arm. We model the gaseous medium

D. M. Alexander, C. Vignali, F. E. Bauer, W. N. Brandt

The multi-wavelength properties of Very Red Objects (VROs; I-K>=4) are largely unknown as many of these sources are optically faint (I>=24) and undetected at most wavelengths. Here we provide constraints on the X-ray properties of VROs using the 1 Ms Chandra exposure of an 8.4&#39;x8.4&#39; region within the Hawaii Flanking-Field area containing the HDF-N. W

Miguel A. de Avillez, Mordecai-Mark Mac Low

In order to understand the time scales for complete mixing in a supernova-driven ISM we used the model of Avillez (2000) to follow the mixing and dispersal of inhomogeneities with different length scales. We included tracer fields to follow the inhomogeneities in kpc-scale simulations with different supernova rates. We find that an initially inhomogeneous IS

Y. R. Fernandez, D. C. Jewitt, S. S. Sheppard

We have measured the mid-infrared thermal continua from two Centaurs, inactive (8405) Asbolus and active 95P=(2060) Chiron, and have constrained their geometric albedos, p, and effective radii, R, with the Standard Thermal Model for slow rotators. These are the first such measurements of Asbolus; we find R=33 km +/- 2 km and p=0.12 +/- 0.03. This albedo is h

Marco Lombardi, Peter Schneider, Carlos Morales-Merino

The parameter-free reconstruction of the surface-mass density of clusters of galaxies is one of the principal applications of weak gravitational lensing. From the observable ellipticities of images of background galaxies, the tidal gravitational field (shear) of the mass distribution is estimated, and the corresponding surface mass density is constructed. Th

F. Crawford, B. M. Gaensler, V. M. Kaspi, R. N. Manchester

We report on Australia Telescope Compact Array observations in the direction of the young high-magnetic-field radio pulsar PSR J1119-6127. In the resulting images we identify a non-thermal radio shell of diameter 15 arcminutes, which we classify as a previously uncataloged young supernova remnant (SNR), G292.2-0.5. This SNR is positionally coincident with PS

F. Crawford, M. J. Pivovaroff, V. M. Kaspi, R. N. Manchester

We describe a sensitive targeted search campaign at Parkes to find faint young radio pulsars using the center beam of the 20-cm multibeam receiver. The high frequency of the receiver mitigates scattering effects which can dominate profiles of distant pulsars at low frequencies and prevent detection. The targets included several composite supernova remnants (

Patrick Cote, Michael J. West, R. O. Marzke

We analyze the metallicity distributions of globular clusters belonging to 28 early-type galaxies in the survey of Kundu & Whitmore (2001). A Monte Carlo algorithm which simulates the chemical evolution of galaxies that grow hierarchically via dissipationless mergers is used to determine the most probable protogalactic mass function for each galaxy. Contrary

Peter D. Edmonds, Craig O. Heinke, Jonathan E. Grindlay, Ronald L. Gilliland

We present the results of a search for optical counterparts to the two quiescent low mass X-ray binaries (X5 and X7) in the globular cluster 47 Tucanae, using high quality Chandra and HST images. A faint blue (V=21.7; U-V=0.9) star within 0.03&#34; of the eclipsing system X5 shows variability on both short and long timescales, and is the counterpart of the X

E. Kellogg, J. A. Pedelty, R. G. Lyon

We report Chandra ACIS-S3 x-ray imaging and spectroscopy of the R Aquarii binary system that show a spatially resolved two-sided jet and an unresolved central source. This is the first published report of such an x-ray jet seen in an evolved stellar system comprised of ~2-3 solar masses. At E < 1 keV, the x-ray jet extends both to the northeast and southwest

I. Baraffe, G. Chabrier, F. Allard, Hauschildt

We analyse pre-Main Sequence evolutionary tracks for low mass stars with masses $m \le 1.4 \msol$ based on the Baraffe et al. (1998) input physics. We also extend the recent Chabrier et al. (2000) evolutionary models based on dusty atmosphere to young brown dwarfs down to one mass of Jupiter. We analyse current theoretical uncertainties due to molecular line

Scott J. Kenyon, Benjamin C. Bromley

We use a new multiannulus planetesimal accretion code to investigate the evolution of a planetesimal disk following a moderately close encounter with a passing star. The calculations include fragmentation, gas and Poynting-Robertson drag, and velocity evolution from dynamical friction and viscous stirring. We assume that the stellar encounter increases plane

B. Schulz, S. Huth, R. J. Laureijs, J. A. Acosta-Pulido

All observations by the aperture photometer (PHT-P) and the far-infrared (FIR) camera section (PHT-C) of ISOPHOT included reference measurements against stable internal fine calibration sources (FCS) to correct for temporal drifts in detector responsivities. The FCSs were absolutely calibrated in-orbit against stars, asteroids and planets, covering wavelengt

Nicola Masetti

An apparent sudden change in the outburst recurrence time displayed by the Rapid Burster occurred around the end of 1999. The time between consecutive outbursts shrinked from ~200 to ~100 days somewhere between November 1999 and March 2000. In parallel, the average peak intensity also decreased of a factor about 2 in all outbursts occurred after November 199

M. Haverkorn, P. Katgert, A. G. de Bruyn

We present multi-frequency polarization observations of the diffuse radio synchrotron background modulated by Faraday rotation, in two directions of positive latitude. No extended total intensity I is observed, which implies that total intensity has no structure on scales smaller than approximately a degree. Polarized intensity and polarization angle, howeve

R. J. R. Williams, J. E. Dyson

We study the structure of shocks in clumpy media, using a multifluid formalism. As expected, shocks broaden as they weaken: for sufficiently weak shocks, no viscous subshock appears in the structure. This has significant implications for the survival of dense clouds in regions overrun by shocks in a wide range of astrophysical circumstances, from planetary n

R. Barnard, M. Balucinska-Church, A. P. Smale, M. J. Church

We report results from analysis of the observations of the dipping low mass X-ray binary XB 1323-619 made with BeppoSAX} and Rossi-XTE. The dust-scattered halo contributes significantly in this source, and the observation made with BeppoSAX on 1997 August was used to provide MECS radial intensity profiles at several energies. From these, the halo fractions w

G. Gilmore

Eddington, COROT, MONS, KEPLER, and the other asteroseismology and planet finding missions, obtain extremely high photometric quality time-series data as their primary purpose. Similar quality data are potentially, and in some designs actually, being obtained for very many other sources in the telescope field of view, in addition to the primary mission targe

E. Laurikainen, H. Salo, P. Rautiainen

Bar strengths are compared between active and non-active galaxies for a sample of 43 barred galaxies. The relative bar torques are determined using a new technique (Buta and Block 2001), where maximum tangential forces are calculated in the bar region, normalized to the axisymmetric radial force field. We use JHK images of the 2 Micron All Sky Survey. We sho

Boris T. Gaensicke, H. -J. Hagen, D. Engels

We have initiated a dedicated search for new CVs, selecting candidates on the base of their spectroscopic properties in the Hamburg Quasar Survey (HQS), which lead up to now to the identification of 50 new CVs and a dozen good candidates. Using the HQS data of the previously known CVs for extensive tests of our selection scheme, we demonstrate that our surve

Chih-Yueh Wang, Roger A. Chevalier

We use two-dimensional hydrodynamical simulations to investigate the properties of dense ejecta clumps (bullets) in a core collapse supernova remnant, motivated by the observation of protrusions probably caused by clumps in the Vela supernova remnant. The ejecta, with an inner flat and an outer steep power law density distribution, were assumed to freely exp

Jesús Maíz-Apellániz, Lucas Cieza, John W. MacKenty

We have used WFPC2 VRI observations to calculate the distances to three nearby galaxies, NGC 4214, UGC 685, and UGC 5456 using the tip of the red giant branch method. Our values for NGC 4214 (2.94 +/- 0.18 Mpc) and UGC 685 (4.79 +/- 0.30 Mpc) are the most precise measurementes of the distances to these objects ever made. For UGC 5456 the data do not allow us

Stan Kurtz, Jose Franco

We review some recent observational results on the properties of ultracompact HII regions, in particular the presence of extended continuum emission surrounding ultracompact sources and the discovery of a new class of so-called ``Hypercompact&#39;&#39; HII regions. In addition, we discuss recent attempts to probe the density structure within UC HII regions u

Manolis Plionis, Spyros Basilakos

Using a sample of 903 APM clusters we investigate whether their dynamical status, as evidenced by the presence of significant substructures, is related to the large-scale structure of the Universe. We find that the cluster dynamical activity is strongly correlated with the tendency of clusters to be aligned with their nearest neighbour and in general with th

U. G. Jorgensen, A. C. Andersen

Inside carbonaceous chondrite meteorites are tiny dust particles which, when heated, release noble gases with an isotopic composition different from what is found anywhere else in the solar system. For this reason it is believed that these grains are (inter)stellar dust which survived the collapse of the interstellar cloud that became the solar system. We wi

Daniel A. Spielman, Shang-Hua Teng

We introduce the smoothed analysis of algorithms, which is a hybrid of the worst-case and average-case analysis of algorithms. In smoothed analysis, we measure the maximum over inputs of the expected performance of an algorithm under small random perturbations of that input. We measure this performance in terms of both the input size and the magnitude of the

Alexey Anisimov

In this paper we provide a detailed numerical study of the influence of thermal effects on the original picture of AD baryogenesis. These effects are found to modify the results greatly in some cases. We estimate the baryon/entropy ratio and provide numerical results on the typical behavior of the charge as a function of the strength of the potential and oth

Adrian Kent

A bit string commitment protocol securely commits $N$ classical bits in such a way that the recipient can extract only $M<N$ bits of information about the string. Classical reasoning might suggest that bit string commitment implies bit commitment and hence, given the Mayers-Lo-Chau theorem, that non-relativistic quantum bit string commitment is impossible. N

Michael P. Muno, Ronald A. Remillard, Deepto Chakrabarty

Low-mass X-ray binaries containing weakly magnetized neutron stars may be divided into two classes, Z and atoll sources, based in large part upon the patterns which they trace in plots of two X-ray colors. In this paper, we examine color-color diagrams of nine atoll sources and five Z sources using data from the Rossi X-ray Timing Explorer. The five-year spa

Tancredi Carli

Recent theoretical developments to calculate cross sections of hadronic objects in the high energy limit are summarised and experimental attempts to establish the need for new QCD effects connected with a resummation of small hadron momentum fractions x are reviewed. The relation between small-$x$ parton dynamics and the phenomenon of diffraction is briefly

Jim Conant, Karen Vogtmann

In two seminal papers Kontsevich used a construction called_graph homology_ as a bridge between certain infinite dimensional Lie algebras and various topological objects, including moduli spaces of curves, the group of outer automorphisms of a free group, and invariants of odd dimensional manifolds. In this paper, we show that Kontsevich&#39;s graph complexe

L. Scheck, M. A. Aloy, J. M. Marti, J. L. Gomez

We study the influence of the matter content of extragalactic jets on their morphology, dynamics and emission properties. For this purpose we consider jets of extremely different compositions including pure leptonic and baryonic plasmas. Our work is based on two-dimensional relativistic hydrodynamic simulations of the long-term evolution of powerful extragal

S. W. Allen, R. W. Schmidt, A. C. Fabian

We present Chandra observations of RXJ1347.5-1145, the most X-ray luminous cluster of galaxies known. We report the discovery of a region of relatively hot, bright X-ray emission, located approximately 20 arcsec to the southeast of the main X-ray peak, at a position consistent with the region of enhanced Sunyaev-Zeldovich effect reported by Komatsu et al. (2

Belle Collaboration, K. Abe

We present a measurement of the Cabibbo-Kobayashi-Maskawa (CKM) matrix element |Vcb| using a 10.2 fb^{-1} data sample recorded at the Υ(4S) resonance with the Belle detector at the KEKB asymmetric e^+e^- storage ring. By extrapolating the differential decay width of the \bar{B}^0 --> D^{*+}e^-\barν decay to the kinematic limit at which the D^{*+} is at rest

Gottfried Curio, Boris Kors, Dieter Lust

We discuss fluxes of RR and NSNS background fields in type II string compactifications on non-compact Calabi-Yau threefolds together with their dual brane description which involves bound states of branes. Simultaneously turning on RR and NSNS 2-form fluxes in an 1/2 supersymmetric way can be geometrically described in M-theory by a SL(2,Z) family of metrics

S. R. Granade, M. E. Gehm, K. M. O&#39;Hara, J. E. Thomas

We achieve degeneracy in a mixture of the two lowest hyperfine states of $^6$Li by direct evaporation in a CO$_2$ laser trap, yielding the first all-optically produced degenerate Fermi gas. More than $10^5$ atoms are confined at temperatures below $4 μ$K at full trap depth, where the Fermi temperature for each state is $8 μ$K. This degenerate two-component m

R. Blaauwgeers, V. B. Eltsov, G. Eska, A. P. Finne

The first realization of instabilities in the shear flow between two superfluids is examined. The interface separating the A and B phases of superfluid He-3 is magnetically stabilized. With uniform rotation we create a state with discontinuous tangential velocities at the interface, supported by the difference in quantized vorticity in the two phases. This s

Adrian Kent

A significant branch of classical cryptography deals with the problems which arise when mistrustful parties need to generate, process or exchange information. As Kilian showed a while ago, mistrustful classical cryptography can be founded on a single protocol, oblivious transfer, from which general secure multi-party computations can be built. The scope of m

Daniele Faenzi

The Tango bundle T over P^5 is proved to be the pull-back of the twisted Cayley bundle C(1) via a map f : P^5 --> Q_5 existing only in characteristic 2. The Frobenius morphism F factorizes via such f. Using f the cohomology of T is computed in terms of F^*(C), Sym^2(C), C and the tensor product of S by C, while these are computed by applying Borel-Bott-Weil

F. Gelis, A. Peshier

In this paper, we consider the diffractive photoproduction of quark-antiquark pairs in peripheral heavy ion collisions. The color field of the nuclei is treated within the Colored Glass Condensate model. The cross-section turns out to be very sensitive to the value of the saturation scale.

Uros Seljak

Abundance of rich clusters in local universe is currently believed to provide the most robust normalization of power spectrum at a scale of 10 Mpc. This normalization depends very sensitively on the calibration between virial mass M and temperature T, which is usually taken from simulations. Uncertainties in the modelling, such as gas cooling and heating, ca

Bernd Kuckert

The proof of a recent result by Guido and Longo establishing the equivalence of the KMS-condition with complete $β$-boundedness is shortcut and generalized in such a way that a covariant version of the theorem is obtained.

Vijay Balasubramanian, Asad Naqvi

We propose a correspondence between the physics of certain small charge black holes in AdS_k x S^l and large charge black holes in AdS_l x S^k. The curvature singularities of these solutions arise, following Myers and Tafjord, from a condensate of giant gravitons. When the number of condensed giants N_g is much greater than the number of background branes N,

Volker Runde, Nico Spronk

The notion of operator amenability was introduced by Z.-J. Ruan in 1995. He showed that a locally compact group G is amenable if and only if its Fourier algebra A(G) is operator amenable. In this paper, we investigate the operator amenability of the Fourier-Stieltjes algebra B(G) and of the reduced Fourier-Stieltjes algebra B_r(G). The natural conjecture is