December 2001 arXiv papers — page 18

Matthias Clausen, Piotr Bartkiewicz, Alexei Dmitrovski, Albert Kagarmanov

In the past, the features of a user interface were limited by those available in the existing graphical widgets it used. Now, improvements in processor speed have fostered the emergence of interpreted languages, in which the appropriate method to render a given data object can be loaded at runtime. XML can be used to precisely describe the association of dat

Ralph C. Baer, Hartmut Eickhoff, Thomas Haberer

The HICAT project is a Heavy Ion accelerator for light ion Cancer Treatment to be built for the clinics in Heidelberg, Germany. It consists of a 7 MeV/u linac, a compact synchrotron and three treatment places, one of them equipped with a 360 degree gantry beam-line. The facility will implement the intensity controlled raster-scanning technique that was devel

R. I. Khrapko

F. V. Gubarev et al. (``On the significance of the vector potential squared'', Phys. Rev. Lett. 86, 2220) have argued that the vector potential itself may have physical meaning, in defiance of the gauge equivalence principle. Earlier R. I. Khrapko proposed a gauge noninvariant electrodynamics spin tensor (``Spin density of electromagnetic waves'&

R. Lombard, C. Volpe

The variation of the size of two-body objects is investigated, as the separation energy approaches zero, with both long range potentials and short range potentials having a repulsive core. It is shown that long range potentials can also give rise to very extended systems. The asymptotic laws derived for states with angular momentum l=1,2 differ from the ones

J. Dukelsky, C. Esebbag, S. Pittel

The traditional nuclear pairing problem is shown to be in one-to-one correspondence with a classical electrostatic problem in two dimensions. We make use of this analogy in a series of calculations in the Tin region, showing that the extremely rich phenomenology that appears in this classical problem can provide interesting new insights into nuclear supercon

Jason R. Cooke

Light front dynamics is a promising approach for calculating the deuteron wave function and form factors at high momentum transfers. However, in light-front dynamics rotational invariance is not manifest, which results in a splitting in the binding energies of states with different magnetic quantum numbers and a breaking of the angular condition for the matr

T. Hatsuda, T. Kunihiro

After a brief overview of the realization of chiral symmetry in hot and/or dense medium, the implications of the existence of a light scalar-isoscalar meson (which we call $σ$ throughout this report) are discussed in the vacuum and in the medium. Special emphasis is put on its relation to the fluctuation of the chiral order parameter $<\bar{q}q>$. In the vac

Emily S. C. Ching, Zhen-Su She, Weidong Su, Zhengping Zou

It is shown that the two remarkable properties of turbulence, the Extended Self-Similarity (ESS) [R. Benzi {\it et al.}, Phy. Rev. E {\bf 48}, R29, (1993)] and the She-Leveque Hierarchical Structure (SLHS) [Z.S. She and E. Leveque, Phy. Rev. Lett. {\bf 72}, 336, (1994)] are related to each other. In particular, we have shown that a generalized hierarchical s

Yunbo Zeng, Huihui Dai, Jinping Song

New infinite number of one- and two-point Bäcklund transformations (BTs) with explicit expressions are constructed for the high-order constrained flows of the AKNS hierarchy. It is shown that these BTs are canonical transformations including Bäcklund parameter $η$ and a spectrality property holds with respect to $η$ and the &#39;conjugated&#39; variable $μ$

Jaroslav Dittrich, Jan Kriz

We investigate the discrete spectrum of the Hamiltonian describing a quantum particle living in the two-dimensional straight strip. We impose the combined Dirichlet and Neumann boundary conditions on different parts of the boundary. Several statements on the existence or the absence of the discrete spectrum are proven for two models with combined boundary co

Bennet Vance

We present an algorithmic mapping from permutations of length dn to labeled n-node d-ary trees and back again. Given such a bijection, one can interpret each of the factorials in the formula for the Catalan numbers as a count of permutations.

Lenhard L. Ng

We examine the Legendrian analogue of the topological satellite construction for knots, and deduce some results for specific Legendrian knots and links in standard contact three-space and the solid torus. In particular, we show that the Chekanov-Eliashberg contact homology invariants of Legendrian Whitehead doubles of stabilized knots contain no nonclassical

B. Feigin, M. Jimbo, S. Loktev, T. Miwa

In our earlier paper we made a combinatorial study of (k,l)-admissible partitions. This object appeared already in the work of M. Primc as a label of a basis of level k-integrable modules over $\hat{sl}_l$. We clarify the relation between these two works. As a byproduct we obtain an explicit parameterization of the affine Weyl group of $\hat{sl}_l$ by a simp

Mikhail Menshikov, Dimitri Petritis

We study random walks in a random environment on a regular, rooted, coloured tree. The asymptotic behaviour of the walks is classified for ergodicity/transience in terms of the geometric properties of the matrix describing the random environment. A related problem, with only one type of vertices and quite stringent conditions on the transition probabilities

Spencer Bloch, Hélène Esnault

The cosimplicial scheme $$Delta^bullet = Δ^0 smallmatrix \to smallmatrix Δ^1 smallmatrix to smallmatrix ...;\quad Δ^n :=\Spec\Big(k[t_0,...c,t_n]/(\sum t_i -t)\Big)$$ was used in B to define higher Chow groups. In this note, we let t tend to 0 and replace Δ^\bullet by a degenerate version $$Q^\bullet = Q^0 smallmatrix to smallmatrix Q^1 smallmatrix to smallm

Pieter Moree

Let P(x,d,a) denote the number of primes p<=x with p=a(mod d). Chebyshev&#39;s bias is the phenomenon that `more often&#39; P(x;d,n)>P(x;d,r) than the other way around, where n is a quadratic non-residue mod d and r is a quadratic residue mod d. If P(x;d,n)>=P(x;d,r) for every x up to some large number, then one expects that N(x;d,n)>=N(x;d,r) for every x. H

Robert Erdahl, Konstantin Rybnikov

George Voronoi (1908-09) introduced two important reduction methods for positive quadratic forms: the reduction with perfect forms, and the reduction with L-type domains. A form is perfect if can be reconstructed from all representations of its arithmetic minimum. Two forms have the same L-type if Delaunay tilings of their lattices are affinely equivalent. D

Robert Erdahl, Konstantin Rybnikov

George Voronoi (1908, 1909) introduced two important reduction methods for positive quadratic forms: the reduction with perfect forms, and the reduction with L-type domains, often called domains of Delaunay type. The first method is important in studies of dense lattice packings of spheres. The second method provides the key tools for finding the least dense

Tomas L. Gomez, Ignacio Sols

Let X be a smooth projective complex variety, and let G be an algebraic reductive complex group. We define the notion of principal G-sheaf, that generalises the notion of principal G-bundle. Then we define a notion of semistability, and construct the projective moduli space of semistable principal G-sheaves on X. This is a natural compactification of the mod

C. Strametz

We study the Lie algebra structure of the first Hochschild cohomology group of a finite dimensional monomial algebra A, in terms of the combinatorics of its quiver, in any characteristic. This allows us also to examine the identity component of the algebraic group of outer automorphisms of A in characteristic zero. Criteria for the (semi-)simplicity, the sol

Jean Bellissard, Riccardo Benedetti, Jean-Marc Gambaudo

For a large class of tilings, including the Penrose tiling in two dimension as well as the icosahedral ones in 3 dimension, the continuous hull of such a tiling inherits a minimal lamination structure with flat leaves and a transversal which is a Cantor set. In this case, we show that the continuous hull can be seen as the projective limit of a suitable sequ

B. Feigin, R. Kedem, S. Loktev, T. Miwa

We give the fermionic character formulas for the spaces of coinvariants obtained from level $k$ integrable representations of $\hat{\mathfrak sl}_2$. We establish the functional realization of the spaces dual to the coinvariant spaces. We parameterize functions in the dual spaces by rigged partitions, and prove the recursion relations for the sets of rigged

Rui Loja Fernandes

We extend the notion of connection in order to be able to study singular geometric structures, namely, we consider a notion of connection on a Lie algebroid which is a natural extension of the usual concept of connection. Using connections, we are able to define holonomy of the orbit foliation of a Lie algebroid and prove a stability theorem. We also introdu

O. A. Castro-Alvaredo, A. Fring

We compare two different methods of computing form factors. One is the well established procedure of solving the form factor consistency equations and the other is to represent the field content as well as the particle creation operators in terms of fermionic Fock operators. We compute the corresponding matrix elements for the complex free fermion and the Fe

I. Krichever

The Hamiltonian theory of isomonodromy equations for meromorphic connections with irregular singularities on algebraic curves is constructed. An explicit formula for the symplectic structure on the space of monodromy and Stokes matrices is obtained. The Whitham equations for the isomonodromy equations are derived. It is shown that they provide a flat connect

Hubert Saleur, Birgit Wehefritz-Kaufmann

We conjecture the factorized scattering description for OSP(m/2n)/OSP(m-1/2n) supersphere sigma models and OSP(m/2n) Gross Neveu models. The non-unitarity of these field theories translates into a lack of `physical unitarity&#39; of the S matrices, which are instead unitary with respect to the non-positive scalar product inherited from the orthosymplectic st

F. O&#39;Dea

We look at the supersymmetric generalization of harmonic maps into Lie groups, known to physicists as the chiral model. Explicit solutions to the equations are found and examined using Backlund transformations.

O. Lauscher, M. Reuter

We summarize recent evidence supporting the conjecture that four-dimensional Quantum Einstein Gravity (QEG) is nonperturbatively renormalizable along the lines of Weinberg&#39;s asymptotic safety scenario. This would mean that QEG is mathematically consistent and predictive even at arbitrarily small length scales below the Planck length. For a truncated vers

Oleg Andreev

We investigate the possibility that stringy nonperturbative instabilities are described by worldsheet methods. We focus on the case of open bosonic string theory, where the D-instanton plays a role of the bounce, i.e. it describes barrier penetration. In the process, we compute the exponential factor in a decay probability.

Allen C. Hirshfeld, Thomas Schwarzweller

We perform the calculation of the partition function of the Poisson-sigma model on the world sheet with the topology of a two-dimensional disc. Considering the special case of a linear Poisson structure we recover the partition function of the Yang-Mills theory. Using a glueing procedure we are able to calculate the partition function for arbitrary base mani

Sei-Hoon Moon

We study global defects coupled to higher-dimensional gravity with a negative cosmological constant. This paper is mainly devoted to studying global black brane solutions which are extended global defects surrounded by horizons. We find series solutions in a few separated regions and confirm numerically that they can be mutually connected. When the world vol

Jarah Evslin, Uday Varadarajan

Recently Maldacena, Moore, and Seiberg (MMS) have proposed a physical interpretation of the Atiyah-Hirzebruch spectral sequence, which roughly computes the K-homology groups that classify D-branes. We note that in IIB string theory, this approach can be generalized to include NS charged objects and conjecture an S-duality covariant, nonlinear extension of th

Hitoshi Murayama, Elena Perazzi

Kutasov--type duals of supersymmetric gauge theories had been studied only in the dual regime and the s-confining case. Here we extend the discussion to the case of less flavor, analogous to the case of quantum-modified moduli space in Seiberg duality. Unlike the Seiberg duality, however, we find that parts of the moduli space become superconformal, generali

Kimmo Kainulainen, Antti Sorri

We study the dynamics of active-sterile neutrino oscillations in the early universe using full momentum-dependent quantum-kinetic equations. These equations are too complicated to allow for an analytical treatment, and numerical solution is greatly complicated due to very pronounced and narrow structures in the momentum variable introduced by resonances. Her

R. Arnowitt, B. Dutta

Direct detection of Milky Way wimps are discussed within the framework of R-parity conserving SUGRA models with grand unification at M_G. Two questions are discussed: what SUGRA models can account for the DAMA data if this data is confirmed, and is the full SUGRA parameter space accessible to future planned detectors. Experimental constraints of the Higgs ma

Bastian Kubis, Ulf-G. Meißner

We evaluate the isospin breaking corrections to the scattering amplitude π^- K^+ -> π^- K^+ at threshold in the framework of chiral perturbation theory. This channel is of particular interest for the strong 2S-2P energy level shift in pion-kaon bound states. While a prediction of this level shift is hampered by a large uncertainty in the isoscalar scattering

Jes Madsen

Strange quark matter in a color-flavor locked state is significantly more bound than ``ordinary&#39;&#39; strange quark matter. This increases the likelihood of strangelet metastability or even absolute stability. Properties of color-flavor locked strangelets are discussed and compared to ordinary strangelets. Apart from differences in binding energy, the ma

Masaaki Fujii, T. Watari

Semi-simple unification is one of a model which naturally solves two difficulties in the supersymmetric grand unification theory: doublet-triplet splitting problem and suppression of dimension 5 proton decay. We analyzed the dimension 6 proton decay of this model using perturbative analysis at the next-to-leading order. The life time of proton is 3 \times 10

Barry R. Holstein

Recently, the development of chiral perturbation theory has allowed the generation of rigorous low energy theorems for various hadronic processes based only on the chiral invariance of the underlying QCD Lagrangian. Such techniques are highly developed and well tested in the domain of pionic and kaonic reactions. In this note we point out that with the addit

A. C. Kalloniatis, S. N. Nedelko

Singular gauge fields in the partition function for QCD can lead to a domain-like picture for the QCD vacuum by virtue of constraints on quantum fluctuations at the singularities. With a simple model of hyperspherical domains with interiors of constant field strength we show that the main features of gluon condensation and an area law for static quarks can b

Hiroyuki Kawamura, Jiro Kodaira, Cong-Feng Qiao, Kazuhiro Tanaka

We present a systematic study of the B meson light-cone distribution amplitudes which are relevant for the QCD factorization approach for the exclusive B meson decays. We construct representations for the quark-antiquark distribution amplitudes in terms of independent dynamical degrees of freedom, which exactly satisfy the QCD equations of motion and constra

Chung-Hsien Chou, Hsien-Hung Shih, Shih-Chang Lee, Hsiang-nan Li

We calculate the amplitudes involved in the heavy baryon nonleptonic decay $Λ_b \rar ΛJ/ψ$ using perturbative QCD factorization theorem, which are expressed as convolutions of hard $b$ quark decay amplitudes with the $Λ_b$ baryon, $Λ$ baryon and $J/ψ$ meson distribution amplitudes. It is found that nonfactorizable contributions dominate over factorizable one

A. Bardi, A. Belloni, R. Carosi, A. Cerri

The Online Silicon Vertex Tracker is the new CDF-II level 2 trigger processor designed to reconstruct 2-D tracks within the Silicon Vertex Detector with high speed and accuracy. By performing a precise measurement of impact parameters the SVT allows tagging online B events which typically show displaced secondary vertices. Physics simulations show that this

Zoltan Ligeti

Recent progress in flavor physics is discussed. In particular, I review theoretical and experimental developments relevant for semileptonic B decays and the determination of |Vcb| and |Vub|, for exclusive rare decays, for nonleptonic b->c decays and tests of factorization, and for D meson mixing.

Thomas G. Rizzo

We examine the rates for the production of black holes(BH) at the LHC in light of the exponential suppression of the geometric cross section estimate proposed by Voloshin. We show that these rates will still be quite large over a reasonable range of model parameters. While BH production may not be the dominant process, its unique signature will ensure observ

V. A. Kuzmin, V. I. Nazaruk

In the framework of field approach with finite time interval the particle oscillations in a medium are considered. The absorption in a final states do not lead to dramatic suppression of ab-transitions. Also we touch on the problem of infrared singularities. The approach under study is infrared-free. It is shown that &#34;correction&#34; published recently [

Thomas D. Cohen

Due to a pion-pole contribution, the nucleon axial current matrix elements can be visualized in position space as becoming delocalized as the chiral limit is approached, with one-third of the current at distance of order the inverse pion mass. However, this delocalization effect will not cause calculations of the axial coupling in a finite system with standa

T. K. Komatsubara

Recent results and future prospects in the rare kaon-decay experiments at KEK, BNL, CERN and FNAL are reviewed. Emphasis is placed on the quark flavor dynamics in the flavor-changing neutral current processes. Experimental and data-analysis techniques developed in the rare decay experiments are discussed.

Gerard Clement, Alessandro Fabbri

We present a family of time-dependent solutions to 2+1 gravity with negative cosmological constant and a massless scalar field as source. These solutions are continuously self-similar near the central singularity. We analyze linear perturbations of these solutions, and discuss the subtle question of boundary conditions. We find two growing modes, one of whic

V. Berezin

We describe some specific quantum black hole model. It is pointed out that the origin of a black hole entropy is the very process of quantum gravitational collapse. The quantum black hole mass spectrum is extracted from the mass spectrum of the gravitating source. The classical analog of quantum black hole is constructed.

G. Gemme, A. Chincarini, R. Parodi, Ph. Bernard

Since 1978 superconducting coupled cavities have been proposed as a sensitive detector of gravitational waves. The interaction of the gravitational wave with the cavity walls, and the esulting motion, induces the transition of some energy from an initially excited cavity mode to an empty one. The energy transfer is maximum when the frequency of the wave is e

J. A. Belinchon, T. Harko, M. K. Mak

We study the evolution of a flat Friedmann-Robertson- Walker Universe, filled with a bulk viscous cosmological fluid, in the presence of variable gravitational and cosmological constants. The dimensional analysis of the model suggest a proportionality between the bulk viscous pressure of the dissipative fluid and the energy density. With the use of this assu

J. P. Krisch, E. N. Glass

We present a solution generating technique for anisotropic fluids which preserves specific Killing symmetries. Anisotropic matter distributions that can be used with the one parameter Ehlers-Geroch transform are discussed. Example spacetimes that support the appropriate anisotropic stress-energy are found and the transformation applied. The 3+1 black string

Tom Brijs, Bart Goethals, Gilbert Swinnen, Koen Vanhoof

In recent years, data mining researchers have developed efficient association rule algorithms for retail market basket analysis. Still, retailers often complain about how to adopt association rules to optimize concrete retail marketing-mix decisions. It is in this context that, in a previous paper, the authors have introduced a product selection model called

Marek Cieplak, Trinh Xuan Hoang, Mark O. Robbins

Mechanical stretching of the I27 domain of titin and of its double and triple repeats are studied through molecular dynamics simulations of a Go-like model with Lennard-Jones contact interactions. We provide a thorough characterization of the system and correlate the sequencing of the folding and unraveling events with each other and with the contact order.

Marek Cieplak, Trinh Xuan Hoang, Mark O. Robbins

Mechanical stretching of secondary structures is studied through molecular dynamics simulations of a Go-like model. Force vs. displacement curves are studied as a function of the stiffness and velocity of the pulling device. The succession of stretching events, as measured by the order in which contacts are ruptured, is compared to the sequencing of events d

J. C. Phillips

Generic intermediate phases with anomalous properties exist over narrow composition ranges adjacent to connectivity transitions. Analysis of both simple classical and complex quantum percolation shows how topological concepts can be used to understand many mysterious properties of high temperature superconductors, including the remarkably similar phase diagr

A. Zheludev, E. Ressouche, I. Tsukada, T. MasudaK. Uchinokura

The unusual 2-stage spin flop transition in BaCu2Si2O7 is studied by single-crystal neutron diffraction. The magnetic structures of the various spin-flop phases are determined. The results appear to be inconsistent with the previously proposed theoretical explanation of the 2-stage transition.

Gady Frenkel, Moshe Schwartz

Consider a deformable body immersed in an incompressible fluid that is randomly stirred. Sticking to physical situations in which the body departs only slightly from its spherical shape, we investigate the deformations of the body. The shape is decomposed into spherical harmonic modes. We study the correlations of these modes for a general class of random fl

Mathis Plapp, Alain Karma

Eutectic two-phase cells, also known as eutectic colonies, are commonly observed during the solidification of ternary alloys when the composition is close to a binary eutectic valley. In analogy with the solidification cells formed in dilute binary alloys, colony formation is triggered by a morphological instability of a macroscopically planar eutectic solid

Ilya M. Dubrovskii

On this article there are presented the main results of the theory of electron phenomena in an unordered condensed matter that can be described as an inhomogeneously deformed crystalline lattice with dislocations. The one-electron effective Hamiltonian is derived by introducing a new basis for the expansion of the sought functions. It allows to overcome the

Francesca Colaiori, Andrea Gabrielli, Stefano Zapperi

We analyze the demagnetization properties of the random-field Ising model on the Bethe lattice focusing on the beahvior near the disorder induced phase transition. We derive an exact recursion relation for the magnetization and integrate it numerically. Our analysis shows that demagnetization is possible only in the continous high disorder phase, where at lo

M. Kenzelmann, R. A. Cowley, W. J. L. Buyers, R. Coldea

We have mapped from the quantum to the classical limit the spin excitation spectrum of the antiferromagnetic spin-1 Heisenberg chain system CsNiCl3 in its paramagnetic phase from T=5 to 200K. Neutron scattering shows that the excitations are resonant and dispersive up to at least T=70K, but broaden considerably with increasing temperature. The dispersion fla

Colin Benjamin, A. M. Jayannavar

A multiply connected system in both its open and closed form variations but in equilibrium is studied using quantum waveguide theory. The system exhibits remarkable features, in its open form variation we see current enhancement, hitherto seen only in non-equilibrium systems in absence of magnetic flux. In its closed form analog parity effects are broken. Fu

R. Gunnarsson, A. Kadigrobov, Z. Ivanov

We have studied the temperature dependence of low-field magnetoresistance and current-voltage characteristics of a low-angle bi-crystal grain boundary junction in perovskite manganite La_{2/3}Sr_{1/3}MnO_3 thin film. By gradually trimming the junction we have been able to reveal the non-linear behavior of the latter. With the use of the relation M_{GB} \prop

Martin Castelnovo, J. F. Joanny

We discuss in this paper the phase diagram of a diblock polyampholyte solution in the limit of high ionic strength as a function of concentration and charge asymmetry. This system is shown to be very similar to solutions of so-called charged-neutral diblock copolymers: at zero charge asymmetry the solution phase separates into a polyelectrolyte complex and a

A. Sarsa, J. Boronat, J. Casulleras

The implementation and reliability of a quadratic diffusion Monte Carlo method for the study of ground-state properties of atoms are discussed. We show in the simple yet non-trivial calculation of the binding energy of the Li atom that the method presented is effectively second-order in the time step. The fulfilment of the expected quadratic behavior relies

Y. Kafri, D. Mukamel, L. Peliti

It is shown that the scaling analysis presented in Phys. Rev. Lett. 85, 4988 (2000) (cond-mat/0007141) is valid for finite chains of lengths relevant to experiments, in contrast to a recent claim made by A. Hanke and R. Metzler in cond-mat/0108323.

K. Sasaki

Charge screening effect in metallic carbon nanotubes is investigated in a model including the one-dimensional long-range Coulomb interaction. It is pointed out that an external charge which is being fixed spatially is screened by internal electrons so that the resulting object becomes electrically neutral. We found that the screening length is given by about

R. Khomeriki, M. Abolfath, K. Mullen

A new manifestation of interlayer coherence in strongly polarized double layer quantum Hall systems with total filling factor $ν=1$ in the presence of a small or zero tunneling is theoretically predicted. It is shown that moving (for small tunneling) and spatially localized (for zero tunneling) stable pseudospin solitons develop which could be interpreted as

Tristram J. Alexander, Yuri S. Kivshar, Elena A. Ostrovskaya, Paul S. Julienne

The structure and stability of vortices in hybrid atomic-molecular Bose-Einstein condensates is analyzed in the framework of a two-component Gross-Pitaevskii-type model that describes the stimulated Raman-induced photoassociation process. New types of topological vortex states are predicted to exist in the coherently coupled two-component condensates even wi

Morten Hogsbro Larsen, A. Mathias Lunde, Karsten Flensberg

We study theoretically the conductance of heterostructures with ferromagnetic conductors (F) and a two dimensional electron gas with Rashba spin-orbit interaction (R) using the Landauer-Büttiker formalism. Assuming a one-dimensional model, we first find the $S$-matrix for the FR interface. This result is then applied to different devices such as a FRF struct

Bacham E. Reddy, David L. Lambert, Bruce J. Hrivnak, Eric J. Bakker

We report on photometry and high-resolution spectroscopy for IRAS 19285+0517. The spectral energy distribution based on visible and near-IR photometry and far-IR fluxes shows that the star is surrounded by dust at a temperature of $T_{\rm {d}}$ $\sim$ 250 K. Spectral line analysis shows that the star is a K giant with a projected rotational velocity $v sin i

S. R. Majewski, M. H. Siegel

The reduced proper motion diagram (RPMD) for a complete sample of faint stars with high accuracy proper motions in the North Galactic Pole field SA57 is investigated. Eight stars with very large reduced proper motions are identified as faint white dwarf candidates. We discriminate these white dwarf candidates from the several times more numerous QSOs based o

R. G. Cruddace, M. P. Kowalski, D. J. Yentis, C. M. Brown

We report a high-resolution (R=3000-4000) spectroscopic observation of the DA white dwarf G191-B2B in the extreme ultraviolet band 220-245 A. A low- density ionised He component is clearly present along the line-of-sight, which if completely interstellar implies a He ionisation fraction considerably higher than is typical of the local interstellar medium. Ho

L. Guzzo, H. Boehringer, C. A. Collins, P. Schuecker

We summarize some of the major results obtained so far from the REFLEX survey of X-ray clusters of galaxies, concentrating on the latest measurements of the cluster X-ray luminosity function and two-point correlation function. The REFLEX luminosity function provides the most homogeneous census of the distribution function of masses in the local Universe, rep

Aaron J. Grocholski, Ata Sarajedini

In an effort to improve the utility of the helium burning red clump luminosity as a distance indicator, we explore the sensitivity of the K-band red clump absolute magnitude Mk(RC) to metallicity and age. We rely upon JK photometry for 14 open clusters and two globulars from the 2nd Incremental Data Release of the 2MASS Point Source Catalog. The distances, m

K. Mori, J. J. Hester, D. N. Burrows, G. G. Pavlov

We present a series of monitoring observations of the Crab Nebula with the Chandra X-ray Observatory, focusing on the temporal evolution of the structure. This series of 8 observations, spanning a period of approximately six months, shows the dynamic nature of the inner X-ray structures. We detected outward moving ``wisps&#39;&#39; from the recently discover

P. -A. Duc, B. Poggianti, D. Fadda. D. Elbaz, H. Flores

At a redshift of 0.18, Abell 1689 is so far the most distant cluster of galaxies for which substantial mid-infrared (MIR) data have been published. We present here the follow-up optical photometric and spectroscopic observations which were used to study the individual properties of the galaxies members of A1689. Sources with a low [15 micron] / [6.75 micron]

Wenbin Li, Neal J. Evans, Daniel T. Jaffe, Ewine F. van Dishoeck

We have carried out an in-depth study of the peripheral region of the molecular cloud L1204/S140, where the far ultraviolet radiation and the density are relatively low. Our observations test theories of photon-dominated regions (PDRs) in a regime that has been little explored. CII 158 micron and OI 63 micron lines are detected by ISO at all 16 positions alo

P. Naselsky, I. Novikov

We discuss possible distortions of the ionization history of the Universe in the model with small scale baryonic clouds. The corresponding scales of the clouds are much smaller than the typical galactic mass scales. These clouds are considered in a framework of the cosmological model with the isocurvature and adiabatic perturbations. In this model the baryon

A. Z. Gazizov, S. I. Yanush

Rapid growth of neutrino-nucleon cross-sections at high energies due to hypothetical hard pomeron enhancement of $νN$-structure functions is discussed. Differential and integral hadron moments, which, together with cross-sections, define rates of hadron-electromagnetic cascades in a neutrino detector are calculated for different power-law decreasing neutrino

V. A. Belokurov, N. W. Evans

GAIA is the ``super-Hipparcos&#39;&#39; survey satellite selected as a Cornerstone 6 mission by the European Space Agency. GAIA can measure microlensing by the small excursions of the light centroid that occur during events. The all-sky source-averaged astrometric microlensing optical depth is about 10^{-5}. Some 25000 sources will have a significant variati

N. La Palombara, S. Mereghetti

The Crab-like SNR G21.5-0.9 was observed in the X-ray band (0.5-10 keV) by the XMM-Newton satellite for over 100 ks. The large effective area of the EPIC instrument has allowed us to to perform a deep search for pulsations from the central core of G21.5-0.9. No pulsations were found with upper limits on the pulsed fraction between 7.5 % and 40 % (depending o

Patrick B. Hall

2MASSI J1315309-264951 is an L3 dwarf with strong H-alpha emission discovered in the course of a color-selected survey for active galactic nuclei using the Two-Micron All-Sky Survey (2MASS). The strength of its H-alpha emission decreased by about a factor of two between two epochs separated by 137 days. This is the first time that variable H-alpha emission h

Taichi Kato

We observed the 1991 October outburst of EF Peg. Prominent superhumps with a period of 0.08705(1) d were observed, qualifying EF Peg as a being long-period SU UMa-type dwarf nova. The superhump period showed a monotonous decrease during the superoutburst, which makes a contrast to the virtually zero period change observed during the 1997 superoutburst of the

M. Feroci, S. Mereghetti, E. Costa, J. J. M. in &#39;t Zand

After a couple of years of quiescence, the soft gamma repeater SGR 1900+14 suddenly reactivated on 18 April 2001, with the emission of a very intense, long and modulated flare, only second in intensity and duration to the 27 August 1998 giant flare. BeppoSAX caught the large flare with its Gamma Ray Burst Monitor and with one of the Wide Field Cameras. The W

Taichi Kato, Kesao Takamizawa

We discovered that GSC 6554.559 is a previously unknown variable star, and named as TmzV429. We noticed that TmzV429 is identified with the IRAS-selected proto-planetary nebula (PPN), IRAS 08005-2356, which is undergoing a vigorous mass-loss episode. The analysis of photometric data suggests that TmzV429 a short-period pulsator, resembling a high-latitude ye

Yurii V. Dumin

Processing the data of lunar laser ranging (LLR) points to the effect of anomalous increase in the lunar semimajor axis (with an excessive rate about 1.3 cm/yr), which cannot be attributed to the well-known tidal exchange of angular momentum between the Earth and Moon. The nature of this phenomenon is not quite clear yet, but one of the possible explanations

Jennifer Scott, Jill Bechtold, Miwa Morita, Adam Dobrzycki

In Paper III of our series &#34;A Uniform Analysis of the Ly-alpha forest at z=0 - 5&#34;, we presented a set of 270 quasar spectra from the archives of the Faint Object Spectrograph on the Hubble Space Telescope. A total of 151 of these spectra, yielding 906 lines, are suitable for using the proximity effect signature to measure J(ν_0), the mean intensity o

Mark S. Byrd, Daniel A. Lidar

Proposals for scalable quantum computing devices suffer not only from decoherence due to the interaction with their environment, but also from severe engineering constraints. Here we introduce a practical solution to these major concerns, addressing solid state proposals in particular. Decoherence is first reduced by encoding a logical qubit into two qubits,

P. Berglund, T. Hubsch, D. Minic

We continue our study of codimension two solutions of warped space-time varying compactifications of string theory. In this letter we discuss a non-supersymmetric solution of the classical type IIB string theory with de Sitter gravity on a codimension two uncompactified part of spacetime. A non-zero positive value of the cosmological constant is induced by t

Takahiro Kubota, Jorgen Rasmussen, Mark A. Walton, Jian-Ge Zhou

Gluing conditions are proposed to characterize the D-branes in gauged WZW models. From them the boundary conditions for the group-valued and the subgroup-valued fields are determined. We construct a gauged WZW action for open strings that coincides classically with those written previously, when the gluing conditions are imposed.

Ioulia Kvasnikova, Charles Gale, Dinesh Kumar Srivastava

The production of intermediate mass dileptons in ultrarelativistic nuclear collisions at SPS energies is studied. The acceptance and detector resolution inherent to measurements by the NA50 experimental collaboration are accurately modeled. The measured centrality dependence of the intermediate mass lepton pair excess is also addressed.

S. Hill, S. Maccagnano, K. Park, R. M. Achey

It is shown that our multi-high-frequency (40-200 GHz) resonant cavity technique yields distortion-free high field EPR spectra for single crystal samples of the uniaxial and biaxial spin S = 10 single molecule magnets (SMMs) [Mn12O12(CH3COO)16(H2O)4].2CH3COOH.4H2O and [Fe8O2(OH)12(tacn)6]Br8.9H2O. The observed lineshapes exhibit a pronounced dependence on te

M. Angst, R. Puzniak, A. Wisniewski, J. Jun

The anisotropy gamma of the superconducting state of high quality single-crystals of MgB2 was determined, using torque magnetometry with two different methods. The anisotropy of the upper critical field was found to be temperature dependent, decreasing from gamma = 6 at 15 K to 2.8 at 35 K. Reversible torque data near Tc reveal a field dependent anisotropy,

Jens Kujat, Angela M. Linn, Robert J. Scherrer, David H. Weinberg

The dark energy that appears to produce the accelerating expansion of the universe can be characterized by an equation of state p=wρwith w<-1/3. A number of observational tests have been proposed to study the value or redshift dependence of w, including SN Ia distances, the Sunyaev-Zel&#39;dovich effect, cluster abundances, strong and weak gravitational lens

Ruben Portugues, Paul K. Townsend

The spectrum of supersymmetric domain wall solitons of the Wess-Zumino model is known to be discontinuous across a curve (of marginal stability) in the moduli space of quartic superpotentials. Here we show how this phenomenon can be understood from the behavior of the long-range inter-soliton force, which we compute by a method due to Manton.

Bjorn Jacobsson, Tommy Ohlsson, Hakan Snellman, Walter Winter

In this paper, we investigate the effects of random fluctuations of the Earth matter density for long baselines on the neutrino oscillation transition probabilities. We especially identify relevant parameters characterizing the matter density noise and calculate their effects by averaging over statistical ensembles of a large number of matter density profile

Nick Evans, Clifford V. Johnson, Michela Petrini

We study the addition of an irrelevant operator to the N=4 supersymmetric large n SU(n) gauge theory, in the presence of finite temperature, T. In the supergravity dual, the effect of the operator is known to correspond to a deformation of the AdS_5 x S^5 ``throat&#39;&#39; which restores the asymptotic ten dimensional Minkowski region of spacetime, completi