December 2001 arXiv papers — page 21

J. G. Gilson

This paper is an updated version of the paper of similar title published in September 1998 {21} modified to take into account recent experimental results and recommendations from CODATA {19} and also to incorporate a correction. The original abstract follows and is still valid. A 1960's suggestion by R. P. Feynman, concerning the possibility of carrying

Marek Sasura, Vladimir Buzek

In this tutorial we review physical implementation of quantum computing using a system of cold trapped ions. We discuss systematically all the aspects for making the implementation possible. Firstly, we go through the loading and confining of atomic ions in the linear Paul trap, then we describe the collective vibrational motion of trapped ions. Further, we

V. P. Karassiov, A. A. Gusev, S. I. Vinitsky

We compare exact and SU(2)-cluster approximate calculation schemes to determine dynamics of the second-harmonic generation model using its reformulation in terms of a polynomial Lie algebra $su_{pd}(2)$ and related spectral representations of the model evolution operator realized in algorithmic forms. It enabled us to implement computer experiments exhibitin

M. D. Reid

In a previous paper certain measurable criteria have been derived, that are sufficient to demonstrate the existence of Einstein-Podolsky-Rosen (EPR) correlations for measurements with continuous variable outcomes. Here it is shown how such EPR criteria, which do not demand perfect EPR correlations, can be used to prove the extent of security for continuous v

M. D. Reid

A generalization of the 1935 Einstein-Podolsky-Rosen (EPR) argument for measurements with continuous variable outcomes is presented to establish criteria for the demonstration of the EPR paradox, for situations where the correlation between spatially separated subsystems is not perfect. Two types of criteria for EPR correlations are determined. The first typ

XuBo Zou, K. Pahlke, W. Mathis

We present a feasible scheme to use trapped ions Cavity QED system to implement optimal $1\to N$ cloning machine of coherent state. In present scheme, as the ouput of the clone machine, the copies of the cavity mode emerge at the vibrational modes and cavity modes is acted as the ancilla mode in the implementation of the cloning. We further show that such sy

Jin-Yuan Hsieh, Che-Ming Li

A general quantum search algorithm with arbitrary unitary transformations and an arbitrary initial state is considered in this work. To serach a marked state with certainty, we have derived, using an SU(2) representation: (1) the matching condition relating the phase rotations in the algorithm, (2) a concise formula for evaluating the required number of iter

Li-Bin Fu, Jie Liu, Shi-Gang Chen

In this paper, we have investigated the correlated electron emission of the nonsequence double ionization (NSDI) in an intense linearly polarized field. The theoretical model we employed is the semiclassical rescattering model, the model atom we used is the helium. We find a significant correlation between magnitude and direction of the momentum of two emiss

S. Gojuki, S. Oryu, S. A. Sofianos

Effective interactions that fit the low energy p-$^3$He experimental data have been constructed. They are based on the Resonating Group Method and a modified Orthogonality Condition Model in which Pauli and partly Pauli forbidden states are removed from the spectrum. Partial waves up to L=3 have been considered. The LS force acting between the proton and $^3

R. Kobes, H. Letkeman

We consider two non-linear generalizations of fractal interpolating functions generated from iterated function systems. The first corresponds to fitting data using a Kth-order polynomial, while the second relates to the freedom of adding certain arbitrary functions. An escape-time algorithm that can be used for such systems to generate fractal images like th

Wen-Xiu Ma

A bi-Hamiltonian formulation is proposed for triangular systems resulted by perturbations around solutions, from which infinitely many symmetries and conserved functionals of triangular systems can be explicitly constructed, provided that one operator of the Hamiltonian pair is invertible. Through our formulation, four examples of triangular systems are exhi

Thomas Gorin

A recursion formula is derived which allows to evaluate invariant integrals over the orthogonal group O(N), where the integrand is an arbitrary finite monomial in the matrix elements of the group. The value of such an integral is expressible as a finite sum of partial fractions in $N$. The recursion formula largely extends presently available integration for

Salih Celik

We introduce the h-deformation of the algebra of functions on the grassmann supergroup Gr$(1|1)$ via a contraction of Gr$_q(1|1)$.

Salih Celik

In this article it is explicitly shown that the matrix elements of CP$_q(n)$ are the annihilation operator of Pusz-Woronowicz (P-W) oscillators provided they are rescaled.

Salih Celik

The two parameter quantum deformation of 2x2 Grassmann matrices, Gr(2), and supermatrices, Gr$(1| 1)$, are presented. Gr(2) whose matrix elements are all Grassmannian variables is called the superdual of the genel linear group GL(2), and Gr$(1| 1)$ whose diagonal matrix elements are Grassmannian variables is called the superdual of the supergroup GL$(1| 1)$

Emilia Mezzetti

We study smooth threefolds of the projective space of dimension 5 whose quadrisecant lines don't fill up the space. We give a complete classification of those threefolds X whose only quadrisecant lines are the lines contained in X. Then we prove that, if X admits "true" quadrisecant lines, but they don't fill up the space, then either X is co

Ezio Vasselli

We construct the crossed product of a C(X)-algebra by an endomorphism, in such a way that it becomes induced by a Hilbert C(X)-bimodule. Furthermore we introduce the notion of C(X)-category, and discuss relationships with crossed products and duality for compact groups.

Xiaotao Sun

We constructed a projective moduli space of semistable torsion free sheaves with `fixed determinant' on a reducible curve. When a family of smooth curves degenerates to the reducible curve, our moduli space is a degeneration of the moduli spaces of semistable vector bundles with a fixed determinant on the smooth curves. Moreover, the moduli space is redu

Yvan Martel, Frank Merle, Tai-Peng Tsai

We prove in this paper the stability and asymptotic stability in H^1 of a decoupled sum of N solitons for the subcritical generalized KdV equations $u_t+(u_{xx}+u^p)_x=0$ (1<p<5). The proof of the stability result is based on energy arguments and monotonicity of local L^2 norm. Note that the result is new even for p=2 (the KdV equation). The asymptotic stabi

Matthias Beck, Xueqin Wang, Thomas Zaslavsky

Sperner&#39;s bound on the size of an antichain in the lattice P(S) of subsets of a finite set S has been generalized in three different directions: by Erdos to subsets of P(S) in which chains contain at most r elements; by Meshalkin to certain classes of compositions of S; by Griggs, Stahl, and Trotter through replacing the antichains by certain sets of pai

Alexander A. Voronov

These are notes of a mini-course given at Dennisfest in June 2001. The goal of these notes is to give a self-contained survey of deformation quantization, operad theory, and graph homology. Some new results related to &#34;String Topology&#34; and cacti are announced in Section 2.7.

Scott Sheffield

We fix $n$ and say a square in the two-dimensional grid indexed by $(x,y)$ has color $c$ if $x+y \equiv c \pmod{n}$. A {\it ribbon tile} of order $n$ is a connected polyomino containing exactly one square of each color. We show that the set of order-$n$ ribbon tilings of a simply connected region $R$ is in one-to-one correspondence with a set of {\it height

Louis F. McAuley

The Hilbert-Smith Conjecture states that if G is a locally compact group which acts effectively on a connected manifold as a topological transformation group, then G is a Lie group. A rather straightforward proof of this conjecture is given. The motivation is work of Cernavskii (``Finite-to-one mappings of manifolds&#39;&#39;, Trans. of Math. Sk. 65 (107), 1

Louis F. McAuley

The Hilbert-Smith Conjecture states that if G is a locally compact group which acts effectively on a connected manifold as a topological transformation group, then G is a Lie group. A rather straightforward proof of this conjecture is given. The motivation is work of Cernavskii (``Finite-to-one mappings of manifolds&#39;&#39;, Trans. of Math. Sk. 65 (107), 1

V. I. Fernández, C. A. Iucci, C. M. Naón

We extend a non local and non covariant version of the Thirring model in order to describe a many-body system with backward and umklapp scattering processes. We express the vacuum to vacuum functional in terms of a non trivial fermionic determinant. Using path-integral methods we find a bosonic representation for this determinant which allows us to obtain an

H. Garcia-Compean, J. F. Plebanski, M. Przanowski, F. J. Turrubiates

Second quantization of a classical nonrelativistic one-particle system as a deformation quantization of the Schrodinger spinless field is considered. Under the assumption that the phase space of the Schrodinger field is $C^{\infty}$, both, the Weyl-Wigner-Moyal and Berezin deformation quantizations are discussed and compared. Then the geometric quantum mecha

V. Barger, D. Marfatia, K. Whisnant

We identify three independent two-fold parameter degeneracies (δ, θ_{13}), sgn(δm^2_{31}) and (θ_{23}, π/2-θ_{23}) inherent in the usual three-neutrino analysis of long-baseline neutrino experiments, which can lead to as much as an eight-fold degeneracy in the determination of the oscillation parameters. We discuss the implications these degeneracies have fo

Cédric Deffayet, Diego Harari, Jean-Philippe Uzan, Matias Zaldarriaga

Recently Csaki, Kaloper and Terning (hep-ph/0111311) suggested that the observed dimming of distant type Ia supernovae may be a consequence of mixing of the photons with very light axions. We point out that the effect of the plasma, in which the photons are propagating, must be taken into account. This effect changes the oscillation probability and renders t

Ian Blokland, Andrzej Czarnecki, Kirill Melnikov

We derive an analytic result for the pion pole contribution to the light-by-light scattering correction to the anomalous magnetic moment of the muon, $a_μ= (g_μ-2)/2$. Using the vector meson dominance model (VMD) for the pion transition form factor, we obtain $a_μ^{{\rm LBL},π^0} = +56 \times 10^{-11}$.

Steven D. Bass

We give a brief overview of the physics of gluonic degrees of freedom associated with the strong (QCD) axial anomaly. The role of this anomalous glue in the spin structure of the proton and eta&#39;-hadron interactions is discussed.

Guray Erkol, Gursevil Turan

We investigate the exclusive $B\to γ\ell^+ \ell^- $ decay in the general two Higgs doublet model (model III) including the neutral Higgs boson effects with an emphasis on possible CP-violating effects. For this decay, we analyse the dependencies of the forward-backward asymmetry of the lepton pair, $A_{FB}$, CP-violating asymmetry, $A_{CP}$, and the CP-viola

John Ellis, Keith Olive, Yudi Santoso

We present detailed calculations of the neutralino-stop coannihilation channels that have the largest impact on the relic neutralino density in the constrained minimal supersymmetric extension of the Standard Model (CMSSM), in which scalar masses m_0, gaugino masses m_1/2 and the trilinear soft supersymmetry-breaking parameters A_0 are each assumed to be uni

A. Gutiérrez-Rodríguez, M. A. Hernández-Ruíz, C. López-González, M. Maya

We start from a Left-Right Symmetric Model and we analyze the beta decay of the free neutron $n\to p+e^{-}+\barν_{e}$. We applied this model to incorporate the right currents, whereby we propose an amplitude whose leptonic part contains the parameter $λ$ defined as left-right asymmetry parameter which measures the parity violation. The analysis consists of s

Yukinori Nagatani

A spherical domain wall around a small black hole is formed by the Hawking radiation from the black hole in the symmetry-broken-phase of the field theory, e.g., the Standard Model (SM) and the Grand Unified Theory (GUT) which have a property of the phase transition. We have obtained two types of the spherical domain wall; (a) thermalized wall which is formed

A. Ali, A. V. Borisov, N. B. Zamorin

We discuss same-sign dilepton production mediated by Majorana neutrinos in high-energy proton-proton collisions $pp\ra \ell^+ \ell^{\prime +}X$ for $\ell,~ \ell^\prime = e,~ μ,~ τ$ at the LHC energy $\sqrt{s}=14$ TeV. Assuming one heavy Majorana neutrino of mass $m_N$, we present discovery limits in the $(m_{N},|U_{\ell N}U_{\ell^\prime N}|)$ plane where $U_

LHPCollaboration, :, H. R. Fiebig

A system of two static quarks, at fixed distances r, and two light quarks is studied on an anisotropic lattice. Excitations by operators emphasizing quark or gluon degrees of freedom are examined. The maximum entropy method is applied in the spectral analysis. These simulations ultimately aim at learning about mechanisms of hadronic interaction.

J. Olsson

Odderon induced contributions to exclusive photoproduction of $π^{\circ}$, $f_2(1270)$ and $a_2(1320)$ have been searched for at HERA, using the multiphoton decays of these mesons. No indication for such contributions was found, in a kinematic region defined by the average photon-proton centre-of-mass energy $<W> = 200 - 215$ GeV, photon virtualities $Q^2 <

ALEPH Collaboration

A search for selectron, smuon and stau pair production is performed with the data collected by the ALEPH detector at LEP at centre-of-mass energies up to 209 GeV. The numbers of candidate events are consistent with the background predicted by the Standard Model. Final mass limits from ALEPH are reported.

ALEPH Collaboration

The production rates of the orbitally excited Ds** mesons, Ds1 and Ds2*, are measured with the 4.1 million hadronic Z decays recorded by the ALEPH detector during 1991--1995. The Ds** mesons are reconstructed in the decay modes Ds1+ -> D*+ K0, Ds1+ -> D*0 K+ and Ds2*+ -> D0 K+. The production rate of the Ds1 is measured to be n(Z->Ds1+-)=(0.52+-0.09+-0.06)%,

David Mattingly, Ted Jacobson

While general relativity possesses local Lorentz invariance, both canonical quantum gravity and string theory suggest that Lorentz invariance may be broken at high energies. Broken Lorentz invariance has also been postulated as an explanation for astrophysical anomalies such as the missing GZK cutoff. Therefore, we seek an effective field theory description

Marcelo S. Berman, Luis A. Trevisan

We make use of Dirac LNH and results for a time varying fine structure constant in order to derive possible laws of variation for speed of light, the number of nucleons in the Universe, energy density and gravitational constant. By comparing with experimental bounds on G variation, we find that the deceleration paramenter of the present Universe is negative.

L. Herrera

It is shown that the effective inertial mass density of a dissipative fluid just after leaving the equilibrium, on a time scale of the order of relaxation time, reduces by a factor which depends on dissipative variables. Prospective applications of this result to cosmological and astrophysical scenarios are discussed.

Jose M. Martin-Garcia, Carsten Gundlach

We construct the general spherically symmetric and self-similar solution of the Einstein-Vlasov system (collisionless matter coupled to general relativity) with massless particles, under certain regularity conditions. Such solutions have a curvature singularity by construction, and their initial data on a Cauchy surface to the past of the singularity can be

Christiane Lechner, Jonathan Thornburg, Sascha Husa, Peter C. Aichelburg

We analyze a bifurcation phenomenon associated with critical gravitational collapse in a family of self-gravitating SU(2) $σ$-models. As the dimensionless coupling constant decreases, the critical solution changes from discretely self-similar (DSS) to continuously self-similar (CSS). Numerical results provide evidence for a bifurcation which is analogous to

Beverly K. Berger

Session A5 on numerical methods contained talks on colliding black holes, critical phenomena, investigation of singularities, and computer algebra.

Victor M. Villalba, Walter Greiner

In this article we compute the density of scalar and Dirac particles created by a cosmological anisotropic Bianchi type I universe in the presence of a time varying electric field. We show that the particle distribution becomes thermal when one neglects the electric interaction.

José Luis Hernández-Pastora, Jesús Martín, Eduardo Ruiz

The vorticity of a congruence is often considered to be the rate of rotation for the precession of a gyroscope moving along a world-line belonging to that congruence. Our aim here was to determine the evolution equation for the angular momentum of a gyrosocope with respect to an arbitrary time-like congruence: i.e, a reference congruence not containing the c

Mark Burgin

Many mathematical models utilize limit processes. Continuous functions and the calculus, differential equations and topology, all are based on limits and continuity. However, when we perform measurements and computations, we can achieve only approximate results. In some cases, this discrepancy between theoretical schemes and practical actions changes drastic

Yongqiang Xue, Supriyo Datta, Mark A. Ratner

Transport in molecular electronic devices is different from that in semiconductor mesoscopic devices in two important aspects: (1) the effect of the electronic structure and (2) the effect of the interface to the external contact. A rigorous treatment of molecular electronic devices will require the inclusion of these effects in the context of an open system

D. Mozyrsky, Sh. Kogan, G. P. Berman

Decoherence of a shallow donor electron spin in silicon caused by electron-lattice interaction is studied. We find that there are two time scales associated with the evolution of the electron spin density matrix: the fast but incomplete decay due to the interaction with non-resonant phonons followed by slow relaxation resulting from spin flips accompanied by

George C. M. A. Ehrhardt, Alan J. Bray, Satya N. Majumdar

We consider the problem of `discrete-time persistence&#39;, which deals with the zero-crossings of a continuous stochastic process, X(T), measured at discrete times, T = n(ΔT). For a Gaussian Stationary Process the persistence (no crossing) probability decays as exp(-θ_D T) = [ρ(a)]^n for large n, where a = \exp[-(ΔT)/2], and the discrete persistence exponen

F. Leyvraz, S. Ruffo

Ensemble inequivalence has been observed in several systems. In particular it has been recently shown that negative specific heat can arise in the microcanonical ensemble in the thermodynamic limit for systems with long-range interactions. We display a connection between such behaviour and a mean-field like structure of the partition function. Since short-ra

Javier Hernandez-Rojas, David J. Wales

A kinetic Monte Carlo (KMC) method is used to study the structural properties and dynamics of a supercooled binary Lennard-Jones liquid around the glass transition temperature. This technique permits us to explore the potential energy surface and barrier distributions without suffering the exponential slowing down at low temperature that affects molecular dy

S. -H. Chong, W. Gotze

The mode-coupling theory for ideal glass transitions in simple systems is generalized to a theory for the glassy dynamics of molecular liquids using the density fluctuations of the sites of the molecule&#39;s constituent atoms as the basic structure variables. The theory is applied to calculate the liquid-glass phase diagram and the form factors for the arre

Martin Howard, Andrew D. Rutenberg, Simon de Vet

Positioning of the midcell division plane within the bacterium E. coli is controlled by the min system of proteins: MinC, MinD and MinE. These proteins coherently oscillate from end to end of the bacterium. We present a reaction--diffusion model describing the diffusion of min proteins along the bacterium and their transfer between the cytoplasmic membrane a

F. Leyvraz, S. Ruffo

Ensemble inequivalence has been observed in several systems. In particular it has been recently shown that negative specific heat can arise in the microcanonical ensemble in the thermodynamic limit for systems with long-range interactions. We display a connection between such behaviour and a mean-field like structure of the partition function. Since short-ra

Ilya Grinberg, Yashar Yourdshahyan, Andrew M. Rappe

CO adsorption on the Pt(111) surface is studied using first-principles methods. As found in a recent study [Feibelman, et al., J. Phys. Chem. B 105, 4018 (2001)], we find the preferred adsorption site within density functional theory to be the hollow site, whereas experimentally it is found that the top site is preferred. The influence of pseudopotential and

M. Eisterer, M. Zehetmayer, S. Toenies, H. W. Weber

Sintered samples of MgB2 were irradiated in a fission reactor. Defects in the bulk microstructure are produced during this process mainly by the 10B(n,a)7Li reaction while collisions of fast neutrons with the lattice atoms induce much less damage. Self-shielding effects turn out to be very important and lead to a highly inhomogeneous defect distribution in t

Vl. S. Dotsenko, J. L. Jacobsen, X. S. Nguyen, R. Santachiara

We study systems of M Potts models coupled by their local energy density. Each model is taken to have a distinct number of states, and the permutational symmetry S_M present in the case of identical coupled models is thus broken initially. The duality transformations within the space of 2^M-1 multi-energy couplings are shown to have a particularly simple for

Carsten Burstedde, Ansgar Kirchner, Kai Klauck, Andreas Schadschneider

We present applications of a cellular automaton approach to pedestrian dynamics introduced in [1,2]. It is shown that the model is able to reproduce collective effects and self-organization phenomena encountered in pedestrian traffic, e.g. lane formation in counterflow through a large corridor and oscillations at doors. Furthermore we present simple examples

Sylvie Hebert, Antoine Maignan, Raymond Fresard, Maryvonne Hervieu

The doping of the manganese site by iridium (up to 15%) in the small A cation manganites Pr_{1-x}Ca_xMnO_3 (0.4 < x < 0.8), has been investigated as a new method to suppress charge-ordering and induce CMR effects. Ir doping leads to ferromagnetism and to insulator to metal transitions, with high transition temperatures reaching 180K and CMR ratio in 7T as la

Andreas Schadschneider

We present a 2-dimensional cellular automaton model for the simulation of pedestrian dynamics. The model is extremely efficient and allows simulations of large crowds faster than real time since it includes only nearest-neighbour interactions. Nevertheless it is able to reproduce collective effects and self-organization encountered in pedestrian dynamics. Th

Kai Nagel, Christopher Kayatz, Peter Wagner

Most car-following models show a transition from laminar to ``congested&#39;&#39; flow and vice versa. Deterministic models often have a density range where a disturbance needs a sufficiently large critical amplitude to move the flow from the laminar into the congested phase. In stochastic models, it may be assumed that the size of this amplitude gets transl

Arlei Prestes Tonel, Angela Foerster, Xi-Wen Guan, Jon Links

Two integrable spin ladder systems with different types of impurities are proposed. The impurities are introduced in such a way that the integrability of the models is not violated. The models are solved exactly and the Bethe ansatz equations as well as the energy eigenvalues are obtained. We show for both models that a phase transition between gapped and ga

J. M. Mignot, A. Gukasov, C. P. Yang, P. Link

The physical properties of the antiferroquadrupolar state occurring in TmTe below TQ=1.8 K have been studied using neutron diffraction in applied magnetic fields. A field-induced antiferromagnetic component k = (1/2,1/2,1/2) is observed and, from its magnitude and direction for different orientations of H, an O(2,2) quadrupole order parameter is inferred. Me

Mustansir Barma, Kavita Jain

We consider the dynamics of the disordered, one-dimensional, symmetric zero range process in which a particle from an occupied site $k$ hops to its nearest neighbour with a quenched rate $w(k)$. These rates are chosen randomly from the probability distribution $f(w) \sim (w-c)^{n}$, where $c$ is the lower cutoff. For $n > 0$, this model is known to exhibit a

A. Cornia, R. Sessoli, L. Sorace, D. Gatteschi

The problem of the role of transverse fields in Mn12-acetate, a molecular nanomagnet, is still open. We present structural evidences that the disorder of the acetic acid of crystallization indices sizeable distortion of the Mn(III) sites, giving rise to six different isomers, four of them with symmetry lower than tetragonal. Using a ligand field approach the

Miki Ueda, Satoru Maegawa, Susumu Kitagawa

The spin-lattice relaxation rate $T_{1}^{-1}$ and NMR spectra of $^1$H in single crystal molecular magnets of Fe8 have been measured down to 15 mK. The relaxation rate $T_1^{-1}$ shows a strong temperature dependence down to 400 mK. The relaxation is well explained in terms of the thermal transition of the iron state between the discreet energy levels of the

Michelle Girvan, M. E. J. Newman

A number of recent studies have focused on the statistical properties of networked systems such as social networks and the World-Wide Web. Researchers have concentrated particularly on a few properties which seem to be common to many networks: the small-world property, power-law degree distributions, and network transitivity. In this paper, we highlight anot

S. J. Wang, M. C. Nemes, A. N. Salgueiro, H. A. Weidenmüller

We compare the equilibrium solution for the condensate obtained in the mean--field approximation to the master equation for sympathetic cooling with the one obtained by Scully for a system in contact with a heat bath with the help of an analogy with the laser. While the mean--field approach yields analytical formulas for the approach towards equilibrium and

A. Yu. Grosberg, T. T. Nguyen, B. I. Shklovskii

We review recent advances in the physics of strongly interacting charged systems functioning in water at room temperature. We concentrate on the phenomena which go beyond the framework of mean field theories, whether linear Debye-Huckel or non-linear Poisson-Boltzmann. We place major emphasis on charge inversion - a counterintuitive phenomenon in which a str

U. Heiter, W. W. Weiss, E. Paunzen

Most of the current theories suggest the lambda Bootis phenomenon to originate from an interaction between the stellar surface and its local environment. In this paper, we compare the abundance pattern of the lambda Bootis stars to that of the interstellar medium and find larger deficiencies for Mg, Si, Mn and Zn than in the interstellar medium. A comparison

Mikhail V. Medvedev, Kristen Menou

We present dynamically consistent solutions for hot accretion onto unmagnetized, rotating white dwarfs (WDs) in five quiescent dwarf novae. The measured WD rotation rates (and other system parameters) in RX And, SS Cyg, U Gem, VW Hyi and WZ Sge imply spindown of the WD by an extended hot flow emitting most of its X-rays in the vicinity of the stellar surface

U. Heiter

Within a project to investigate the properties of lambda Bootis stars, we report on their abundance pattern. High resolution spectra have been obtained for a total of twelve candidate lambda Bootis stars, four of them being contained in spectroscopic binary systems, and detailed abundance analyses have been performed. All program stars show a characteristic

C. Koen, L. Eyer

Two selection statistics are used to extract new candidate periodic variables from the epoch photometry of the Hipparcos catalogue. The primary selection criterion is a signal to noise ratio. The dependence of this statistic on the number of observations is calibrated using about 30 000 randomly permuted Hipparcos datasets. A significance level of 0.1% is us

R. A. Bernstein, W. L. Freedman, B. F. Madore

We present a measurement of the absolute surface brightness of the zodiacal light (3900-5100A) toward a fixed extragalactic target at high ecliptic latitude based on moderate resolution (~1.3A per pixel) spectrophotometry obtained with the du Pont 2.5m telescope at Las Campanas Observatory in Chile. This measurement and contemporaneous Hubble Space Telescope

Adam T. Kruger, Thomas J. Loredo, Ira Wasserman

We analyze the Time-Tagged Event (TTE) data from observations of gamma ray bursts (GRBs) and soft gamma repeaters (SGRs) by the Burst and Transient Source Experiment (BATSE). These data provide the best available time resolution for GRBs and SGRs. We have performed an extensive search for weak periodic signals in the frequency range 400 Hz to 2500 Hz using t

M. T. Dova, L. N. Epele, J. D. Swain

Despite many efforts to find a reasonable explanation, the origin of the &#34;knee&#34; in the cosmic ray spectrum at energy around 10**15.5 eV remains mysterious. In this letter we suggest that the &#34;knee&#34; may be due to a GZK-like effect of cosmic rays interacting with massive neutrinos in the galactic halo. Simple kinematics connects the location of

K. G. Stassun, M. van den Berg, R. D. Mathieu, F. Verbunt

We use differential CCD photometry to search for variability in BVI among 990 stars projected in and around the old open cluster M 67. In a previous paper we reported results for 22 cluster members that are optical counterparts to X-ray sources; this study focuses on the other stars in our observations. A variety of sampling rates were employed, allowing var

P. S. Custódio, J. E. Horvath

We constrain the mass abundance of unclustered primordial black holes (PBHs), formed with a simple mass distribution and subject to the Hawking evaporation and particle absorption from the environment. Since the radiative flux is proportional to the numerical density, an upper bound is obtained by comparing the calculated and observed diffuse background valu

F. P. Israel, F. Baas

We present measurements of the emission from the centers of fifteen spiral galaxies in the 3P1-3P0 [CI] fine-structure transition at 492 GHz. Observed galaxy centers range from quiescent to starburst to active. The intensities of neutral carbon, the J=2-1 transition of 13CO and the J=4-3 transition of 12CO are compared in matched beams. Most galaxy centers e

Maureen van den Berg, Keivan Stassun, Frank Verbunt, Robert D. Mathieu

We study photometric variability among the optical counterparts of X-ray sources in the old open cluster M67. The two puzzling binaries below the giant branch are both variables: for S1113 the photometric period is compatible with the orbital period, S1063 either varies on a period longer than the orbital period, or does not vary periodically. For the spectr

E. K. Verolme, P. T. de Zeeuw

We describe a practical method for constructing axisymmetric two-integral galaxy models (with distribution functions of the form f(E,L_z), in which E is the orbital energy, and L_z is the vertical component of the angular momentum), based on Schwarzschild&#39;s orbit superposition method. Other f(E,L_z)-methods are mostly based on solving the Jeans equations

R. Giacconi, A. Zirm, J. Wang, P. Rosati

In this Paper we present the source catalog obtained from a 942 ks exposure of the Chandra Deep Field South (CDFS), using ACIS-I on the Chandra X-ray Observatory. Catalog generation proceeded simultaneously using two different methods; a method of our own design using a modified version of the SExtractor algorithm, and a wavelet transform technique developed

Neville S. Shane, Phil A. James

We are conducting a large survey of star formation within ~400 nearby spiral and irregular galaxies through imaging of the Halpha emission. We present here some of our first results from 104 of the galaxies in our sample, investigating the variation of SFR and Halpha EWs along the Hubble sequence for these galaxies. We find a strong dependence of SFR on Hubb

G. Hebrard, M. Lemoine, A. Vidal-Madjar, J. -M. Desert

We present a deuterium abundance analysis of the line of sight toward the white dwarf WD2211-495 observed with the Far Ultraviolet Spectroscopic Explorer (FUSE). Numerous interstellar lines are detected on the continuum of the stellar spectrum. A thorough analysis was performed through the simultaneous fit of interstellar absorption lines detected in the fou

M. Lemoine, A. Vidal-Madjar, G. Hebrard, J. -M. Desert

High-resolution spectra of the hot white dwarf G191-B2B, covering the wavelength region 905-1187A, were obtained with the Far Ultraviolet Spectroscopic Explorer (FUSE). This data was used in conjunction with existing high-resolution Hubble Space Telescope STIS observations to evaluate the total HI, DI, OI and NI column densities along the line of sight. Prev

D. R. Ballantyne, A. C. Fabian, R. R. Ross

Iron Kαemission from photoionized and optically thick material is observed in a variety of astrophysical environments including X-ray binaries, active galactic nuclei, and possibly gamma-ray bursts. This paper presents calculations showing how the equivalent width (EW) of the Fe K line depends on the iron abundance of the illuminated gas and its ionization s

Sudip Bhattacharyya

We calculate the accretion disc temperature profiles, disc luminosities and boundary layer luminosities for rapidly rotating neutron stars considering the full effect of general relativity. We compare the theoretical values of these quantities with their values inferred from EXOSAT data for four low mass X-ray binary sources: XB 1820-30, GX 17+2, GX 9+1 and

A. M. Atoyan, P. M. Chadwick, M. K. Daniel, K. Lyons

A timing analysis of VHE gamma-ray observations of Cen X-3 taken with the University of Durham Mark 6 telescope was performed, using both Rayleigh and Bayesian statistics. Data from only 1 observation produced evidence for periodicity, in a &#39;soft&#39; cut data set, with an overall chance probability <0.01 and blueshifted by 6.6ms from the nominal second

S. J. Smartt

The masses and the evolutionary states of the progenitors of core-collapse supernovae are not well constrained by direct observations. Stellar evolution theory generally predicts that massive stars with initial masses less than about 30M_sol should undergo core-collapse when they are cool M-type supergiants. However the only two detections of a SN progenitor

Sudip Bhattacharyya

We predict from a survey of equations of state and observations of X-ray pulsations from SAX J1808.4-3658, that the upper limit of the mass of the compact star is 2.27 solar mass. The corresponding upper limit of the radius comes out to be 9.73 km. We also do a study to estimate the lower limit of the mass of the compact star. Such a limit is very useful to

M. G. Burton, D. Londish, P. W. J. L. Brand

We have imaged the emission from the near-infrared v=1-0 S(1), 1-0 S(7), 2-1 S(1) and 6-4 O(3) lines of molecular hydrogen in the N- and SW-Bars of M17, together with the hydrogen Br-gamma and Br-10 lines. This includes the first emission line image ever to be obtained of a line from the highly excited v=6 level of H2. In both Bars, the H2 emission is genera

F. Villa, M. Bersanelli, C. Burigana, R. C. Butler

In this paper we present an overview of the Telescope designed for ESA&#39;s mission dedicated to map the Cosmic Microwave Background Anisotropies and Polarization. Two instruments, LFI and HFI, operate in an overall frequency range between 25 and 900 GHz and share the focal region of the 1.5 meter optimized telescope. The optimization techniques adopted for

The ANTARES Collaboration

The ANTARES collaboration is building a deep sea neutrino telescope in the Mediterranean Sea. This detector will cover a sensitive area of typically 0.1 km-squared and will be equipped with about 1000 optical modules. Each of these optical modules consists of a large area photomultiplier and its associated electronics housed in a pressure resistant glass sph

Benedetta Ciardi

In this talk I will present a model for primordial galaxy formation. In particular, I will review the feedback effects that regulate the process: (i) radiative (i.e. ionizing and H_2-photodissociating photons) and (ii) stellar (i.e. SN explosions) feedback produced by massive stars. I will show the results of a model for galaxy formation and IGM reionization

R. A. Bernstein, W. L. Freedman, B. F. Madore

(Abridged) We have used HST WFPC2 and ground-based spectroscopy to measure the integrated extragalactic background light (EBL) at optical wavelengths. We have also computed the integrated light from individual galaxy counts in the images used to measure the EBL and in the Hubble Deep Field. We find that the flux in galaxies as measured by standard galaxy pho

Peter M. Frinchaboy, Jaehyon Rhee, James C. Ostheimer, Steven R. Majewski

We explore the metallicity distribution function (MDF) of red giant stars in Omega Centauri from a catalogue of Washington M, T_2 and DDO51 photometry covering over 1.1 deg^2 outside the cluster core. Using updated calibrations of giant branch isometallicity loci in this filter system, photometric metallicities, guided by previously published spectroscopic a

Dion Lewis, Richard Dodson, David McConnell, Avinash Deshpande

Observations using the Australia Telescope Compact Array at a wavelength of 6 cm have uncovered the radio counterpart to the compact X-ray nebula surrounding the Vela pulsar. Two lobes were found oriented about the spin axis of the pulsar, starting at the edge of X-ray emission, they extend to three times the size. The northern lobe has a bright, defined edg

R. Sadat, A. Blanchard, M. Douspis

One of the most direct way to constrain the matter density of the universe $Ω_M$ is to measure the baryon content in X-Rays clusters of galaxies. Typical value of the mean gas mass fraction is $\fg \sim 0.15h^{-3/2}$ which leads to $\omM <0.4$. In this talk I will discuss the issue of the gas fraction radial distribution inside a cluster and foccus on the ap