July 2001 arXiv papers — page 5

Ph. Boucaud, J. P. Leroy, H. Moutarde, J. Micheli

We present preliminary results on the computation of the QCD running coupling constant in the $\widetilde{MOM}$ scheme and Landau gauge with two flavours of dynamical Wilson quarks. Gluon momenta range up to about 7 GeV ($β=$ 5.6, 5.8 and 6.0) with a constant dynamical-quark mass. This range already allows to exhibit some evidence for a sizable $1/μ^2$ corre

Giovanni Amelino-Camelia

I show that a Planck-scale deformation of the relativistic dispersion relation, which has been independently considered in the quantum-gravity literature, can explain the surprising results of three classes of experiments: (1) observations of cosmic rays above the expected GZK limit, (2) observations of multi-TeV photons from the BL Lac object Markarian 501,

Csaba Csaki, Graham D. Kribs, John Terning

We examine new classes of GUT models where the GUT gauge group is broken by a 4D analogue of the Scherk-Schwarz mechanism. These models are inspired by ``deconstructed'' 5D Scherk-Schwarz orbifold models. However, no fine tuning of parameters or assumption of higher dimensional Lorentz invariance is necessary, and the number of lattice sites can be a

Paul K. Townsend, Marija Zamaklar

We obtain ADM and Komar surface integrals for the energy density, tension and angular momentum density of stationary $p$-brane solutions of Einstein's equations. We use them to derive a Smarr-type formula for the energy density and thence a first law of black brane mechanics. The intensive variable conjugate to the worldspace p-volume is an `effective&#3

Ramandeep S. Johal

We show that for general deformations of SU(2) algebra, the dynamics in terms of ladder operators is preserved. This is done for a system of precessing magnetic dipole in magnetic field, using the unitary phase operator which arises in the polar decomposition of SU(2) operators. It is pointed out that there is a single phase operator dynamics underlying the

G. Bowen, S. Bose

We show that standard teleportation with an arbitrary mixed state resource is equivalent to a generalized depolarizing channel with probabilities given by the maximally entangled components of the resource. This enables the usage of any quantum channel as a generalized depolarizing channel without additional twirling operations. It also provides a nontrivial

G. Kubon, H. Anklin, P. Bartsch, D. Baumann

Precise data on the neutron magnetic form factor G_{mn} have been obtained with measurements of the ratio of cross sections of D(e,e'n) and D(e,e'p) up to momentum transfers of Q^2 = 0.9 (GeV/c)^2. Data with typical uncertainties of 1.5% are presented. These data allow for the first time to extract a precise value of the magnetic radius of the neutro

M. Bouhmadi-Lopez, A. Zhuk

The stability of 5-D brane-world models under conformal perturbations is investigated. The analysis is carried out in the general case and then it is applied to particular solutions. It is shown that models with the Poincare and the de Sitter branes are unstable because they have negative mass squared of gravexcitons whereas models with the Anti de Sitter br

N. Kivel

We consider hard electroproduction of mesons at twist-3 level and focus our attention on helicity flip amplitudes corresponding to the production of transversely polarized mesons by transverse photons. We demonstrate that helicity-flip amplitude for the transversely polarized particles are closely related to the contributions of the matrix elements of the te

S. Dusuel, F. Vistulo de Abreu, B. Doucot

We present a renormalization group analysis of two-dimensional interacting fermion systems with a closed and partially flat Fermi surface. Numerical solutions of the one-loop flow equations show that for a bare local repulsion, the system evolves through three different regimes as the typical energy is lowered: a high-energy transient with a strong competiti

Koichi Izawa, Hidemasa Yamaguchi, Takahiko Sasaki, Yuji Matsuda

The thermal conductivity of organic superconductor kappa-(BEDT-TTF)2Cu(NCS)2 (Tc =10.4 K) has been studied in a magnetic field rotating within the 2D superconducting planes with high alignment precision. At low temperatures (T < 0.5 K), a clear fourfold symmetry in the angular variation, which is characteristic of a d-wave superconducting gap with nodes alon

S. Groot Nibbelink, B. J. W. van Tent

We calculate the scalar gravitational and matter perturbations in the context of slow-roll inflation with multiple scalar fields, that take values on a (curved) manifold, to first order in slow roll. For that purpose a basis for these perturbations determined by the background dynamics is introduced and multiple-field slow-roll functions are defined. To obta

Chongxing Yue, Gongru Lu, Guoli Liu, Qingjun Xu

In the framework of topcolor-assisted technicolor(TC2) models, we calculate the contributions of flavor changing scalar couplings involved the neutral top-pion $π_{t}^{0}$ and top-Higgs $h_{t}^{0}$ to the branching ratio $B_{r}(t\longrightarrow cg)$. We find that the value of $B_{r}(t\longrightarrow cg)$ can reach $ 1\times10^{-3}$ with reasonable values of

J. Lamarcq, J. -P. Bouchaud, O. C. Martin, M. Mezard

We study numerically the local low-energy excitations in the 3-d Edwards-Anderson model for spin glasses. Given the ground state, we determine the lowest-lying connected cluster of flipped spins with a fixed volume containing one given spin. These excitations are not compact, having a fractal dimension close to two, suggesting an analogy with lattice animals

S. J. Smartt, G. F. Gilmore, C. A. Tout, S. T. Hodgkin

We present high quality ground-based VRI images of the site of the Type II-P SN1999em (in NGC1637) taken before explosion, which were extracted from the CFHT archive. We determine a precise position of the SN on these images to an accuracy of 0.17&#39;&#39;. The host galaxy is close enough (7.5 +/- 0.5 Mpc) that the bright supergiants are resolved as individ

F. Ya. Khalili

Electromagnetic rigidity which exists in large-scale optical resonators if pumping frequency is detuned from the eigenfrequency of resonator have sophisticated spectral dependence which allows to obtain sensitivity better than the Standard Quantum Limits both for the free test mass and the harmonic oscillator.

Ryutaroh Matsumoto

The stabilizer code is the most general algebraic construction of quantum error-correcting codes proposed so far. A stabilizer code can be constructed from a self-orthogonal subspace of a symplectic space over a finite field. We propose a construction method of such a self-orthogonal space using an algebraic curve. By using the proposed method we construct a

Gábor Csányi, Stefan Goedecker, T. A. Arias

We present a new density-matrix functional within the recently introduced framework for tensor-product expansions of the two-particle density matrix. It performs well both for the homogeneous electron gas as well as atoms. For the homogeneous electron gas, it performs significantly better than all previous density-matrix functionals, becoming very accurate f

Y. Abe, C. Hattori, M. Ito, M. Matsuda

In the four-dimensional effective theory from string compactification discrete flavor symmetries arise from symmetric structure of the compactified space and generally contain both the $R$ symmetry and non-$R$ symmetry. We point out that a new type of non-Abelian flavor symmetry can also appear if the compact space is non- commutative. Introducing the dihedr

D. Brace, B. L. Cerchiai, B. Zumino

In this paper, we describe a method for obtaining the nonabelian Seiberg-Witten map for any gauge group and to any order in theta. The equations defining the Seiberg-Witten map are expressed using a coboundary operator, so that they can be solved by constructing a corresponding homotopy operator. The ambiguities, of both the gauge and covariant type, which a

Andrei Khrennikov

We study the probabilistic consequences of the choice of the basic number field in quantum formalism. We demonstrate that by choosing a number field for a linear space representation of quantum model it is possible to describe various interference phenomena. We analyse interference of probabilistic alternatives induced by real, complex, hyperbolic (Clifford)

G. N. Rockwell, V. F. Hoffman, Th. Clausen, R. Blümel

Analytical arguments and numerical simulations suggest that the shapes of 3D microwave ionization curves measured by Koch and collaborators (see P. M. Koch and K. A. H. van Leeuwen, Phys. Rep. {\bf 255}, 289 (1995)) depend only weakly on the angular momentum of the atoms in the initial microcanonical ensemble, but strongly on the principal quantum number and

Berthold-Georg Englert, Krzysztof Wodkiewicz

We investigate the separability properties of quantum two-party Gaussian states in the framework of the operator formalism for the density operator. Such states arise as natural generalizations of the entangled state originally introduced by Einstein, Podolsky, and Rosen. We present explicit forms of separable and nonseparable Gaussian states.

Nicolas J. Cerf, Mohamed Bourennane, Anders Karlsson, Nicolas Gisin

We consider two quantum cryptographic schemes relying on encoding the key into qudits, i.e. quantum states in a d-dimensional Hilbert space. The first cryptosystem uses two mutually unbiased bases (thereby extending the BB84 scheme), while the second exploits all the d+1 available such bases (extending the six-state protocol for qubits). We derive the inform

Kazuyuki Fujii

The aim of this paper is to introduce our idea of Holonomic Quantum Computation (Computer). Our model is based on both harmonic oscillators and non-linear quantum optics, not on spins of usual quantum computation and our method is moreover completely geometrical. We hope that therefore our model may be strong for decoherence.

Apoorva Patel

Does quantum dynamics play a role in DNA replication? What type of tests would reveal that? Some statistical checks that distinguish classical and quantum dynamics in DNA replication are proposed.

Stephan I. Tzenov

Based on the Renormalization Group method, a reduction of non integrable multi-dimensional hamiltonian systems has been performed. The evolution equations for the slowly varying part of the angle-averaged phase space density, and for the amplitudes of the angular modes have been derived. It has been shown that these equations are precisely the Renormalizatio

Ana Damjanovic, Ioan Kosztin, Klaus Schulten

The dynamics of pigment-pigment and pigment-protein interactions in light-harvesting complexes is studied with a novel approach which combines molecular dynamics (MD) simulations with quantum chemistry (QC) calculations. The MD simulations of an LH-II complex, solvated and embedded in a lipid bilayer at physiological conditions (with total system size of 87,

Subrata Pal, C. M. Ko, Z. Y. Zhang

Using a multiphase transport model, we study the production of a new strange dibaryon (ΩΩ)_{0+} in dense hadronic matter formed in relativistic heavy ion collisions. The (multi-)strange baryons (Ξand Ω) are produced by strangeness-exchange reactions between antikaons and hyperons in the pure hadronic phase. The rescattering between the omegas at midrapidity

J. E. Amaro, M. B. Barbaro, J. A. Caballero, T. W. Donnelly

A set of fully relativistic one-pion-exchange electromagnetic operators is developed for use in one-particle emission reactions induced by electrons. To preserve the gauge invariance of the theory additional pionic correlation operators are required beyond the usual meson-exchange current operators. Of these, in the present work emphasis is placed on the sel

C. Keil, H. Lenske

The density dependent relativistic hadron field theory is used to describe single particle properties of Lambda hypernuclei. The discussion focuses on the spin-orbit systematics in the relativistic mean-field formalism by discussing general effects of the Lambda continuum threshold and the delocalization of the Lambda wave function. Theoretical predictions f

S. Boffi

A critical review is presented of recent data on direct one- and two-nucleon emission obtained in electron scattering at NIKHEF, Mainz and JLab. In the case of (e,e$&#39;$p) reactions attention is focussed on extracting spectroscopic factors, looking at medium effects on the bound nucleon form factors, and investigating nuclear transparency. The possibility

G. Boffetta, I. M. Sokolov

Relative dispersion in fully developed turbulence is investigated by means of direct numerical simulations. Lagrangian statistics is found to be compatible with Richardson description although small systematic deviations are found. The value of the Richardson constant is estimated as $C_2 \simeq 0.55$, in a close agreement with recent experimental findings [

R. Blümel, Yu. Dabaghian

Based on an exact trace formula for a one-dimensional ray-splitting system, we derive novel combinatorial identities for cyclic binary sequences (Pólya necklaces).

David Garber, Mina Teicher, Uzi Vishne

One of the open questions in the geometry of line arrangements is to what extent does the incidence lattice of an arrangement determine its fundamental group. Line arrangements of up to 6 lines were recently classified by K.M. Fan, and it turns out that the incidence lattice of such arrangements determines the projective fundamental group. We use actions on

Tomek Bartoszynski

We show that the Dual Borel Conjecture implies that ${\mathfrak d}> \aleph_1$ and find some topological characterizations of perfectly meager and universally meager sets.

L. Bonavero, F. Campana, J. A. Wiśniewski

We classify complex projective manifolds $X$ for which there exists a point $a$ such that the blow-up of $X$ at $a$ is Fano.

Yoshihiro Ônishi

In this paper we generalize the formula of Frobenius-Stickelberger and the formula of Kiepert to genus-three case. The latter is well-known determinant expression for any division polynomial of any elliptic curve.

Ashok Das, J. Maharana, A. Melikyan

The collision of plane waves corresponding to massless states of closed string is considered in $D$-dimensional space-time. The reduced tree level effective action is known to be manifestly $O(d,d)$ invariant, $d$ being the number of transverse spatial dimensions in the collision process. We adopt a coset space reformulation of the effective two dimensional

Koji Hashimoto

Using recently proposed non-linearly realized supersymmetry in non-Abelian gauge theory corrected to the order (alpha&#39;)^2, we derive the non-linear BPS equations in the background B-field for the U(2) monopoles and instantons. We show that these non-Abelian non-linear BPS equations coincide with the non-commutative anti-self-dual equations via the Seiber

Lev Kofman

I review the theory of preheating after inflation, focusing on the recently found tachyonic preheating in the theories with spontaneous symmetry breaking. This occurs due to the tachyonic instability of the scalar field near the top of its effective potential. Contrary to the common expectation, tachyonic instability converts most of the energy into that of

R. Adhikari, G. Rajasekaran

We consider L-violating Supersymmetric Models to explain the recent muon $g_μ -2$ deviation from the Standard Model. The order of trilinear L-violating couplings which we require also generate neutrino mass which is somewhat higher than expected unless one considers highly suppressed $L-R$ mixing of sfermions. However, without such fine tuning for sfermions

Carlo Bemporad, Giorgio Gratta, Petr Vogel

The status of neutrino oscillation searches employing nuclear reactors as sources is reviewed. This technique, a direct continuation of the experiments that proved the existence of neutrinos, is today an essential tool in investigating the indications of oscillations found in studying neutrinos produced in the sun and in the earth&#39;s atmosphere. The low-e

A. Masiero, O. Vives

Supersymmetry exhibts new sources of CP violation. We discuss the implications of these new contributions to CP violation both in the K and B physics. We show that CP violation puts severe constraints on low energy SUSY, but it represents also a promising ground to look for signals of new physics.

A. Donini, D. Meloni

We compare the physical reach of a Neutrino Factory in the 2+2 and 3+1 four-family models, with similar results in the two schemes; in both cases huge CP-violating effects can be observed with a near detector in the $ν_μ\to ν_τ$ channel. We also study the capability of long baseline experiments (optimized for the study of the three-family mixing parameter sp

Markus Schumacher

This letter reviews the potential of a high luminosity e+e- linear collider (LC) in the precision study of the Higgs boson profile. The complementarity with the Large Hadron Collider (LHC) Higgs physics program is briefly discussed.

Aseshkrishna Datta, Abdelhak Djouadi, Monoranjan Guchait, Yann Mambrini

We analyze the cascade decays of the scalar quarks and gluinos of the Minimal Supersymmetric extension of the Standard Model, which are abundantly produced at the Large Hadron Collider, into heavier charginos and neutralinos which then decay into the lighter ones and charged Higgs particles, and show that they can have substantial branching fractions. The pr

A. Papa

The Balitsky-Fadin-Kuraev-Lipatov (BFKL) approach for the cross sections at high energy $\sqrt s$ in perturbative QCD is briefly reviewed. The role of gluon Reggeization in the derivation of the BFKL equation and its compatibility with $s$-channel unitarity (``bootstrap&#39;&#39;) are discussed.

B. Aubert, the BABAR Collaboration

We present preliminary results of a search for the decay B^0 --> a_0^+(980)pi^- among 22.7 million Upsilon(4S)-->B-anti-B pairs collected by the BABAR detector at PEP-II. Using improved background suppression techniques and optimal signal extraction for rare decay searches, an excess of events over expected background is observed at the level of 3.7 standard

B. Aubert

We present a preliminary measurement of the time-dependent CP-violating asymmetry parameters S_pipi and C_pipi in neutral B decays to the pi^+/-pi^-/+ CP eigenstate, and an updated preliminary measurement of the charge asymmetry A_Kpi in B --> K^+/-pi^-/+ decays. Event yields and $\CP$-violation parameters are determined simultaneously from a multidimensiona

Alfredo G. Cocco

Considerations based on particle physics (in particular the so-called see-saw mechanism) and on cosmology, in relation to the Dark Matter question, motivated the search for numu nutau oscillation in the region of small mixing angles. We present here the outcome of the short-baseline programme carried out at CERN by the CHORUS and NOMAD experiments. Both expe

K. Abe

We report a search for the flavor-changing neutral current decay $B \to X_{s} \ell^{+} \ell^{-}$ using a 29.5 fb$^{-1}$ data sample accumulated at the $Υ(4S)$ resonance with the Belle detector at the KEKB $e^{+}e^{-}$ storage ring. We observe evidence for $B\to Kμ^+μ^-$ and report the preliminary branching fraction of ${\cal B}(B \to K μ^{+} μ^{-}) = (0.99^{

L. Herrera, N. O. Santos, A. F. F. Teixeira, A. Z. Wang

We study Levi-Civita metric for values of its sigma parameter in the range 0< sigma<infinity. We show that the value sigma=1/2 makes the axial and angular coordinates switch meaning. We present its geodesics and a physical source satisfying the energy conditions for all the range of sigma. This source allows us to obtain an energy per unit length which agree

Sergio M. C. V. Goncalves

We study the occurrence of shell crossing in spherical weakly charged dust collapse in the presence of a non-vanishing cosmological constant. We find that shell crossing always occurs from generic time-symmetric regular initial data, near the center of the matter configuration. For non-time-symmetric initial data, the occurrence---or lack thereof---of shell

Hideki Ishihara

Big bang of the Friedmann-Robertson-Walker (FRW)-brane universe is studied. In contrast to the spacelike initial singularity of the usual FRW universe, the initial singularity of the FRW-brane universe is point-like from the viewpoint of causality including gravitational waves propagating in the bulk. Existence of null singularities (seam singuralities) is a

Elizabeth D. Dolan

The NEOS Server 4.0 provides a general Internet-based client/server as a link between users and software applications. The administrative guide covers the fundamental principals behind the operation of the NEOS Server, installation and trouble-shooting of the Server software, and implementation details of potential interest to a NEOS Server administrator. Th

Branislav K. Nikolic, J. K. Freericks, P. Miller

We present fully self-consistent calculations of the thermodynamic properties of three-dimensional clean SNS Josephson junctions, where S is an s-wave short-coherence-length superconductor and N is a clean normal metal. The junction is modeled on an infinite cubic lattice such that the transverse width of the S is the same as that of the N, and its thickness

S. I. Woods, J. R. Kirtley, Shouheng Sun, R. H. Koch

A direct probe of superparamagnetism was used to determine the complete anisotropy energy distribution of Co nanoparticle films. The films were composed of self-assembled lattices of uniform Co nanoparticles 3 nm or 5 nm in diameter, and a variable temperature scanning-SQUID microscope was used to measure temperature-induced spontaneous magnetic noise in the

Henry Cejtin, Jan Edler, Allan Gottlieb, Robert Helling

Using a fast tree-searching algorithm and a Pentium cluster, we enumerated all the sequences and compact conformations (structures) for a protein folding model on a cubic lattice of size $4\times3\times3$. We used two types of amino acids -- hydrophobic (H) and polar (P) -- to make up the sequences, so there were $2^{36} \approx 6.87 \times 10^{10}$ differen

I. V. Gornyi, A. D. Mirlin

We study the statistics of wave functions in a ballistic chaotic system. The statistical ensemble is generated by adding weak smooth random potential, which allows us to apply the ballistic $σ$-model approach. We analyze conditions of applicability of the $σ$-model, emphasizing the role played by the single-particle mean free path and the Lyapunov exponent d

A Kambili, A B Walker, F Qiu, A C Fisher

Dye sensitised nanocrystalline solar cells (Grätzel cells) have achieved solar-to-electrical energy conversion efficiencies of 12% in diffuse daylight. The cell is based on a thin film of dye-sensitised nanocrystalline TiO$_2$ interpenetrated by a redox electrolyte. The high surface area of the TiO$_2$ and the spectral characteristics of the dye allow the de

Carsten Honerkamp, Manfred Sigrist

We investigate the quasiparticle spectrum near surfaces in a two-dimensional system with d-density-wave order within a mean-field theory. For Fermi surfaces with perfect nesting for the ordering wave vector of the d-density-wave, a zero energy bound state occurs at [110] surfaces, in close analogy with the known effect in d-wave superconducting states or gra

Julian Manzano

In this work we present a new family of options (mirror options) specially crafted to satisfy the necessities of aggressive speculators. The main ideas behind mirror options are: 1) A product that can be adjusted by the holder to agree with his/her market view at any time during its life. 2) The holder&#39;s right to make an arbitrary number of those adjustm

I. S. Elfimov, N. A. Skorikov, V. I. Anisimov, G. A. Sawatzky

We study the resonance behaviour of the forbidden 600 and 222 x-ray Bragg peaks in Ge using LDA band structure methods. These Bragg peaks remain forbidden in the resonant dipole scattering approximation even taking into account the non local nature of the band states. However they become allowed at resonance if the eigenstates of the unoccupied conduction ba

R. Pfandzelter, M. Potthoff

The temperature-dependence of the magnetization near the surface of a band-ferromagnet is measured with monolayer resolution. The simultaneous application of novel highly surface-sensitive techniques enables one to deduce the layer-dependent magnetization curves at a Fe(100) surface. Analysis of data is based on a simple mean-field approach. Implications for

A. Masoero, P. Mazzetti, I. Puica, A. Stepanescu

Analysis of the resistive transition of a polycristalline YBCO specimen produced by an a.c. magnetic field, reveals the presence of a large conductance noise signal which is repetitive over subsequent magnetization cycles. It is shown that the noise arises from avalanche effects produced by the simultaneous resistive transition of large groups of weak links.

Efim A. Brener, David A. Kessler

Comment on PRL v. 86, p. 5084 (2001) [cond-mat/0101016]. We point out that the authors&#39; simulations are consistent with the known theory of steady-state solutions in this system.

Th. Boeker, R. Severin, A. Mueller, C. Janowitz

In this work the complete valence-band structure of the molybdenum dichalcogenides MoS_2, MoSe_2, and alpha-MoTe_2 is presented and discussed in comparison. The valence bands have been studied using both angle-resolved photoelectron spectroscopy (ARPES) with synchrotron radiation, as well as, ab-initio band-structure calculations. The ARPES measurements have

Y. Xuan, H. J. Tao, Z. Z. Li, C. T. Lin

Temperature and doping dependent tunneling spectroscopy on $Bi_2Sr_2CaCu_2O_{8+δ}$ single crystals has been investigated by using break-junction technique. The results provide direct evidence that the pseudogap persists into heavily overdoped regime, possibly in whole doping range of the superconducting phase. The gap value determined from the peak-to-peak o

Irzaman, H. Darmasetiawan, M. Nur Indro S. G. Sukaryo, M Hikam

Thin Ba0.5Sr0.5TiO3 (BST) films on p-type Si (100) using The Chemical Solution Deposition (CSD) method. X-ray diffraction (XRD), Scanning electron microscopy (SEM), C-V meter analysis measurement were employed to characterise the films. The growth condition to obtain enough quality epitaxial of Ba0.5Sr0.5TiO3 carried out by spin coating at 3000 rpm for 30 se

Y. Itoh, S. Adachi, T. Machi, N. Koshizuka

We report a zero-field Cu nuclear quadrupole resonance (NQR) study on the effects of nonmagnetic Sr substitution for high-Tc superconductors, Y(Ba1-xSrx)2Cu4O8 (Tc=82-80 K for x=0-0.4), using a spin-echo technique. The site-disordering and chemical pressure effects associated with doping Sr were observed in the broadened, shifted Cu NQR spectra. Nevertheless

O. Cepas, Ross H. McKenzie, J. Merino

The synthetic organic compound lambda-(BETS)2FeCl4 undergoes successive transitions from an antiferromagnetic insulator to a metal and then to a superconductor as a magnetic field is increased. We use a Hubbard-Kondo model to clarify the role of the Fe(3+) magnetic ions in these phase transitions. In the high-field regime, the magnetic field acting on the el

H. Fehske, G. Wellein, A. Weiße, F. Göhmann

In an attempt to clarify the nature of the crossover from a Peierls band insulator to a Mott Hubbard insulator, we analyze ground-state and spectral properties of the one-dimensional half-filled Holstein Hubbard model using exact diagonalization techniques.

C. O. Heinke, P. D. Edmonds, J. E. Grindlay

We have detected three new x-ray point sources, in addition to the known low-mass x-ray binary (LMXB) X1832-330, in the globular cluster NGC 6652 with a Chandra 1.6 ksec HRC-I exposure. Star 49 (M_{V}~4.7), suggested by Deutsch et al.(1998) as the optical candidate for the LMXB, is identified (<0.3&#34;) not with the LMXB, but with another, newly detected so

Roger W. Romani, Simon Johnston

We have carried out a survey for `giant pulses&#39; in 5 millisecond pulsars. We detect individual pulses from the high Edot pulsar PSR B1821-24 with energies exceeding 50x the mean pulse energy. These giant pulses are concentrated in a narrow phase window coincident with the power-law non-thermal pulse seen in hard X-rays. This is the third example of the g

G. Risaliti, M. Elvis, F. Nicastro

We present a study of the variations in the absorbing column density of 25 X-ray defined Seyfert 2 galaxies, as inferred from hard X-ray observations, on timescales from months to several years. We show that a significant variation of N$_H$ (from 20% to 80%) is observed in almost all (22/25) the sources with multiple X-ray observations, although X-ray absorp

A. Natta, L. Testi

We discuss the spectral energy distribution of three very low mass objects in Chamaeleon I for which ground-based spectroscopy and photometry as well as ISO measurements in the mid-infrared are available (Comeron et al. 2000; Persi et al. 2000). One of these stars (Cha Halpha1) is a bona-fide brown dwarf, with mass 0.04-0.05 Msun. We show that the observed e

G. D. Schmidt, S. Vennes, D. T. Wickramasinghe, L. Ferrario

Optical spectrophotometry and circular spectropolarimetry are presented for several candidate magnetic white dwarfs that were identified during the Hamburg/ESO survey for bright QSOs. HE 1211-1707 and HE 1043-0502 are rare examples of white dwarfs that show neutral helium lines in a high magnetic field, in these cases ~50 MG and ~800 MG, respectively. The fo

Rachel S. Somerville

Cold Dark Matter theory predicts that the Local Group should contain many more dwarf-sized objects than the observed number of dwarf galaxies --- the so-called sub-structure problem. We investigate whether the suppression of star formation in these small objects due to the presence of a photoionizing background can resolve the problem. We make use of results

E. Vanzella, S. Cristiani, P. Saracco, S. Arnouts

We present a deep multicolor (UBVIJsHKs) catalog of galaxies in the HDF-S, based on observations obtained with the HST WFPC2 in 1998 and VLT-ISAAC in 1999. The photometric procedures were tuned to derive a catalog optimized for the estimation of photometric redshifts. In particular we adopted a ``conservative&#39;&#39; detection threshold which resulted in a

Patrick A. Woudt, Brian Warner

The first results of a photometric survey of faint Cataclysmic Variables are presented. V359 Cen is an SU UMa star with a period of 112 min. Even though observed at quiescence, the mass transfer rate in this old nova may be sufficiently high that in such a short period system (with its implied small mass ratio) the disc may be excited into an elliptical shap

S. Schindler, A. Castillo-Morales, E. De Filippis, A. Schwope

We present CHANDRA observations of the X-ray luminous, distant galaxy cluster RBS797 at z=0.35. In the central region the X-ray emission shows two pronounced X-ray minima, which are located opposite to each other with respect to the cluster centre. These depressions suggest an interaction between the central radio galaxy and the intra-cluster medium, which w

Alex H. Blin

At the level of the Planck scale, the spacetime metric has to be considered a quantum variable. Conformal quantum fluctuations of the metric tensor are studied here. They lead to an extra term in the Einstein equations which can be identified with a cosmological constant. Quantum fluctuations may therefore contribute to an accelerated expansion of the univer

N. Bartolo, S. Matarrese, A. Riotto

We study adiabatic and isocurvature perturbations produced during a period of cosmological inflation. We compute the power spectra and cross spectra of the curvature and isocurvature modes, as well as the tensor perturbation spectrum in terms of the slow-roll parameters. We provide two consistency relations for the amplitudes and spectral indices of the corr

R. Morganti, T. A. Oosterloo, C. N. Tadhunter, K. A. Wills

We present a summary of recent studies of HI absorption in radio galaxies. The results show how the absorption can be due to a variety of phenomena and how they can help us in understanding more of what is happening in and around AGNs.

O. Martineau

We present here the principles of detection of Weakly Interacting Massive Particles, which could represent a large contribution to Dark Matter. A status of the experimental situation is given both for indirect and direct detection. In particular, the DAMA claim for a WIMP signal is confronted to the recent results of the CDMS and EDELWEISS experiments. We co

S. Leon, J. Lim, F. Combes, D. Van-Trung

We report the detection of CO(1-0) and CO(2-1) emission from the central region of nearby 3CR radio galaxies (z$<$ 0.03). Out of 21 galaxies, 8 have been detected in, at least, one of the two CO transitions. The total molecular gas content is below 10$^9$ \msun. Their individual CO emission exhibit, for 5 cases, a double-horned line profile that is character

F. De Paolis, G. Ingrosso, A. A. Nucita, D. Orlando

The nature of the massive object at the Galactic Center (Sgr A$^{*}$) is still unclear even if various observational campaigns led many authors to believe that our Galaxy hosts a super-massive black hole with mass $M\simeq 2.6\times 10^6$ M$_{\odot}$. However, the black hole hypothesis, which theoretically implies a luminosity $\simeq 10^{41}$ erg s$^{-1}$,

Jessica L. Rosenberg, Stephen E. Schneider

We present a study of HI-rich galaxies in the local universe selected from blind emission-line surveys. These galaxies represent the emission-line counterparts of local damped Lyman-alpha systems. We find that the HI cross-section of galaxies is drawn from a large range of galaxy masses below M_star, 66% of the area comes from galaxies in the range 8.5 < Log

J. Brand, J. G. A. Wouterloot, A. L. Rudolph, E. J. de Geus

We report the results of high-resolution (~0.2 pc) CO(1-0) and CS(2-1) observations of the central regions of three star-forming molecular clouds in the far-outer Galaxy (~16 kpc from the Galactic Center): WB89 85 (Sh 2-127), WB89 380, and WB89 437. We used the BIMA array in combination with IRAM 30-m and NRAO 12-m observations. The GMC&#39;s in which the re

David B. Kaplan, Sanjay Reddy

We analyze the phases of dense quark matter at nonzero quark masses. We map out the phase diagrams for charged quark matter as well as charge neutral matter containing leptons. We find that in Color Flavor Locked (CFL) quark matter, the symmetric phase with equal numbers of $u$, $d$ and $s$ quarks is unlikely to occur in nature. Various less symmetric phases

Jimmy A. Irwin, Craig L. Sarazin, Joel N. Bregman

We present a Chandra ACIS-S observation of the nearby bulge-dominated Sa galaxy NGC1291. The X-ray emission from the bulge resembles the X-ray emission from a sub-class of elliptical and S0 galaxies with low L_X/L_B luminosity ratios. The X-ray emission is composed of a central point-like nucleus, ~50 point sources that are most likely low mass X-ray binarie

Michael Gronau, Yuval Grossman, Dan Pirjol, Anders Ryd

We propose a way of measuring the photon polarization in radiative B decays into K resonance states decaying to Kππ, which can test the Standard Model and probe new physics. The photon polarization is shown to be measured by the up-down asymmetry of the photon direction relative to the Kππdecay plane in the K resonance rest frame. The integrated asymmetry in

Nahum Arav, Martijn de Kool, Kirk T. Korista

We re-analyze the HST high resolution spectroscopic data of the intrinsic absorber in NGC 5548 and find that the C IV absorption column density is at least four times larger than previously determined. This increase arises from accounting for the kinematical nature of the absorber and from our conclusion that the outflow does not cover the narrow emission li

Ari Mizel

We present a microscopic approach to the quantum tunneling of vortices. The formalism characterizes the rate at which a many-body superconducting state with a vortex in one location makes a transition to a second many-body superconducting state with a vortex in a second location. The theory is utilized to study the effect of a d-wave order parameter upon the

E. Kh. Akhmedov

We propose a dynamical mechanism of localization of gauge fields on a brane in which gauge bosons are excitations of the brane itself or composites made out of matter fields localized on the brane. The mechanism is operative for both Abelian and non-Abelian gauge fields. Several scalar and scalar-fermion composite models of gauge fields are considered. The m

R. N. Mohapatra

It is shown that if small neutrino masses owe their origin to the conventional seesaw mechanism and the MNS mixing matrix is in the exact bimaximal form, then there exist symmetries in the theory that allow one of the righthanded neutrinos to become naturally massless, making it a candidate for the sterile neutrino discussed in the literature. Departures fro

A. S. Gliozzi, A. Parola

Microscopic models of quantum antiferromagnets are investigated on the basis of a mapping onto effective low energy hamiltonians. Lattice effects are carefully taken into account and their role is discussed. We show that the presence of an external staggered magnetic field modifies in a non trivial way the usual mapping onto the non linear sigma model, leadi

D. Kazhdan, B. Pioline, A. Waldron

Theta series for exceptional groups have been suggested as a possible description of the eleven-dimensional quantum supermembrane. We present explicit formulae for these automorphic forms whenever the underlying Lie group $G$ is split (or complex) and simply laced. Specifically, we review and construct explicitly the minimal representation of $G$, generalizi

Vishal Mehra, Peter Grassberger

We study biased random walkers on lattices with randomly dispersed static traps in one, two and three dimensions. As the external bias is increased from zero the system undergoes a phase transition, most clearly manifested in the asymptotic drift velocity of survivors which is zero below a critical bias. This transition is second-order in one dimension but o