September 2001 arXiv papers — page 13

E. Oset, José A. Oller, Ulf-G. Meißner

We perform a study of the final state interactions of the K^+ \bar{K^0} and the \bar{K^0}d systems in the reactions pp \to d K^+ \bar{K^0} and pp \to d π^+ η. Since the two-meson system couples strongly to the a_0(980) resonance, these reactions are expected to be an additional source of information about the controversial scalar sector. We also show that th

J. E. Amaro, T. W. Donnelly

The cross section for electron-induced proton knockout reactions with polarized beam and target is computed in a DWIA model. The analysis is focused on the electron helicity-dependent (HD) piece of the cross section. For the case of in-plane emission a new symmetry is found in the HD cross section, which takes opposite values for specific opposing pairs of n

J. Kvasil, V. O. Nesterenko, P. -G. Reinhard

Self-consistent factorization of two-body residual interaction is proposed for arbitrary density- and current-dependent energy functionals. Following this procedure, a separable RPA (SRPA) method is constructed. SRPA dramatically simplifies the calculations and demonstrates quick convergence to exact results. The method is tested for SkM* forces.

A. Fabrocini

We discuss some single particle properties of $^{16}$O and $^{40}$Ca using correlated basis function theory and Fermi hypernetted chain equations with central and tensor correlations. In particular, we concentrate on one body density matrix, momentum distribution, natural orbits and quasi hole states. The correlations are variationally generated by a realist

T. Frick, S. Kaiser, H. Müther, A. Polls

The influence of $Δ$ isobar components on the ground state properties of nuclear systems is investigated for nuclear matter as well as finite nuclei. Many-body wave functions, including isobar configurations, and binding energies are evaluated employing the framework of the coupled-cluster theory. It is demonstrated that the effect of isobar configurations d

Konstantin Yu. Kazakov, Denis V. Shulga

Several observables in two-body deuteron photodisintegration are investigated in the framework of the Bethe-Salpeter formalism. Apart from keeping throughout Lorentz covariance, a special attention is paid to inclusion of both the positive energy and negative energy partial-wave components of the deuteron state. Using the Bethe-Salpeter equation for deuteron

Bao-An Li, Andrew T. Sustich, Matt Tilley, Bin Zhang

Within nuclear thermodynamics and an isospin-dependent transport model we investigate respective roles of the nuclear mean field and the 2-body stochastic scattering on the evolution of density and isospin fluctuations in either mechanically or chemically unstable regions of neutron-rich matter. It is found that the mean field dominates overwhelmingly the fa

M. K. Lauren

This paper endeavors to show how a fractal-based approach can offer an alternative to differential equations for describing rates of interaction in complex systems. The specific example given is for combat analysis. This concerns a scenario of some similarity to the situation in Mogadishu in 1993, for which military analysts struggled to provide useful analy

R. Quian Quiroga, A. Kraskov, T. Kreuz, P. Grassberger

We study the synchronization between left and right hemisphere rat EEG channels by using various synchronization measures, namely non-linear interdependences, phase-synchronizations, mutual information, cross-correlation and the coherence function. In passing we show a close relation between two recently proposed phase synchronization measures and we extend

A. Loskutov, I. Istomin, O. Kotlyarov

We study forecasting capabilities of the methods of Singular Spectrum Analysis (SSA) and Local Approximation (LA). A practical implementation of these methods to several time series is described. Details of the algorithms of these methods are discussed. Advantages and disadvantages of SSA and LA are given. On the basis of our results we generalize LA and SSA

F. T. Arecchi, R. Meucci, E. Allaria, A. Di Garbo

The chaotic spike train of a homoclinic dynamical system is self-synchronized by re-inserting a small fraction of the delayed output. Due to the sensitive nature of the homoclinic chaos to external perturbations, stabilization of very long periodic orbits is possible. On these orbits, the dynamics appears chaotic over a finite time, but then it repeats with

R. Meucci, A. Di Garbo, E. Allaria, F. T. Arecchi

A continuous train of irregularly spaced spikes, peculiar of homoclinic chaos, transforms into clusters of regularly spaced spikes, with quiescent periods in between (bursting regime), by feeding back a low frequency portion of the dynamical output. Such autonomous bursting results to be extremely robust against noise; we provide experimental evidence of it

Eugene Balkovsky, Boris I. Shraiman

Locating the source of odor in a turbulent environment - a common behavior for living organisms - is non-trivial because of the random nature of mixing. Here we analyze the statistical physics aspects of the problem and propose an efficient strategy for olfactory search which can work in turbulent plumes. The algorithm combines the maximum likelihood inferen

Cristian Degli Esposti Boschi, Enrique Louis, Guillermo Ortega

It is shown that arbitrarily weak (frozen) heterogeneity can induce global synchronized oscillations in excitable media close to threshold. The work is carried out on networks of coupled van der Pol-FitzHugh-Nagumo oscillators. The result is shown to be robust against the presence of internal dynamical noise.

Guillermo Ortega, Cristian Degli Esposti Boschi, Enrique Louis

A method based upon the statistical evaluation of the differentiability of the measure along the trajectory is used to identify in high dimensional systems. The results show that the method is suitable for discriminating stochastic from deterministic systems even if the dimension of the latter is as high as 13. The method is shown to succeed in identifying d

Richard L. Hall, Nasser Saad, Attila B. von Keviczky

A complete variational treatment is provided for a family of spiked-harmonic oscillator Hamiltonians H = -d^2/dx^2 + B x^2 + lambda/x^alpha, B > 0, lambda > 0, for arbitrary alpha > 0. A compact topological proof is presented that the set S = {psi_n} of known exact solutions for alpha = 2 constitutes an orthonormal basis for the Hilbert space L_2(0, infinity

Feodor A. Smirnov

In this paper we construct separated variables for quantum integrable models related to the algebra $U_q(\hat{sl}_N)$. This generalizes the results by Sklyanin for $N=2,3$.

Bernardo Uribe

Chen and Ruan's orbifold cohomology of the symmetric product of a complex manifold is calculated. An isomorphism of rings (up to a change of signs) $H_{orb}^*(X^n/S_n;\complex) \cong H^*(X^{[n]};\complex)$ between the orbifold cohomology of the symmetric product of a smooth projective surface with trivial canonical class $X$ and the cohomology of its Hil

V. M. Buchstaber, E. G. Rees

If A is an algebra of functions on X, there are many cases when X can be regarded as included in Hom(A,C) as the set of ring homomorphisms. In this paper the corresponding results for the symmetric products of X are introduced. It is shown that the symmetric product Sym^n(X) is included in Hom(A,C) as the set of those functions that satisfy equations general

Anton Deitmar

It is shown that Mellin transforms of p-adic Whittaker functions exist for generic characters. For good choices of vectors they are rational functions. For class one vectors they can be calculated explicitly. It turns out that they are automorphic L-factors times normalization factors.

P. Baguis, M. Cahen

We propose a reduction procedure for symplectic connections with symmetry. This is applied to coadjoint orbits whose isotropy is reductive.

Amnon Neeman, Andrew Ranicki

The noncommutative (Cohn) localization S^{-1}R of a ring R is defined for any collection S of morphisms of f.g. projective left R-modules. We exhibit S^{-1}R as the endomorphism ring of R in an appropriate triangulated category. We use this expression to prove that if S^{-1}R is "stably flat over R" (meaning that Tor^R_i(S^{-1}R,S^{-1}R)=0 for i>0) t

Chaofeng Zhu

In this paper, we prove a Morse index theorem for the index form of regular Lagrangian system with selfadjoint boundary condition.

Martin Hairer

We consider parabolic stochastic partial differential equations driven by white noise in time. We prove exponential convergence of the transition probabilities towards a unique invariant measure under suitable conditions. These conditions amount essentially to the fact that the equation transmits the noise to all its determining modes. Several examples are i

J. Hilgert, A. Pasquale, E. B. Vinberg

We show how to calculate the dual horospherical Radon transform of a polynomial in terms of the Harish-Chandra c-function.

Devin C. V. Greene

We define the notion of a free resolution of a d-tuple $(T_1, T_2, . . . T_d)$ of mutually commuting operators acting on a Hilbert space H, and that this invariant gives rise to a class of vector space complexes parametrized by points in the unit ball $B_d = {z \in C^d: |z| <1}$. We show that for $λ\in B_d$ the homology of the corresponding complex is equiva

Stephen Semmes

This is a kind of introduction to some basic topics in analysis, some of which would be covered in standard graduate courses, and some not. However, an important difference is that not much in the way of prerequisites are needed, beyond linear algebra and beginning analysis. In particular, this should be accessible to undergraduates or readers whose main foc

Sherman K. Stein

Let m and n be integers, $2 \leq m \leq n$. An m by n array consists of mn cells, arranged in m rows and n columns, and each cell contains exactly one symbol. A transversal of an array consists of m cells, one from each row and no two from the same column. A latin transversal is a transversal in which no symbol appears more than once. We will establish a suf

Marco Grandis

This is a sequel to a previous paper, developing an intrinsic, combinatorial homotopy theory for simplicial complexes; the latter form the cartesian closed subcategory of &#39;simple presheaves&#39; in !Smp, the topos of symmetric simplicial sets, or presheaves on the category of finite, positive cardinals. We show here how this homotopy theory can be extend

Wen-Jun Chen, Kang Li, Carlos Naón

Using two new well defined 4-dimensional potential vectors, we formulate the classical Maxwell&#39;s field theory in a form which has manifest Lorentz covariance and SO(2) duality symmetry in the presence of magnetic sources. We set up a consistent Lagrangian for the theory. Then from the action principle we get both Maxwell&#39;s equation and the equation o

G. De Risi, M. Gasperini

We discuss the possibility of a smooth transition from the pre- to the post-big bang regime, in the context of the lowest-order string effective action (without higher-derivative corrections), taking into account with a phenomenological model of source the repulsive gravitational effects due to the back-reaction of the quantum fluctuations outside the horizo

Sayan Kar, Parthasarathi Majumdar, Soumitra SenGupta, Saurabh Sur

The effects of introducing a harmonic spatial inhomogeneity into the Kalb-Ramond field, interacting with the Maxwell field according to a `string-inspired&#39; proposal made in earlier work are investigated. We examine in particular the effects on the polarization of synchrotron radiation from cosmologically distant (i.e. of redshift greater than 2) galaxies

S. James Gates, W. D. Linch, J. Phillips, L. Rana

In the following, we will review the fundamental problem that prevents a complete understanding of a theory of supersymmetrical field representations and describe its possible relation to a similar problem facing superstring/M-theory.

A. B. Balantekin

Recent work on neutrino propagation in stochastic media and its implications for the Sun and core-collapse supernovae are reviewed. It is shown that recent results from Sudbury Neutrino Observatory and SuperKamiokande combined with a best global fit value of $δm^2= 5\times 10^{-5}$ eV$^2$ and $\tan^2 θ= 0.3$ rule out solar electron density fluctuations of a

J. A. Casas, A. Ibarra

If neutrino masses and mixings are suitable to explain the atmospheric and solar neutrino fluxes, this amounts to contributions to FCNC processes, in particular $μ\to e, γ$. If the theory is supersymmetric and the origin of the masses is a see-saw mechanism, we show that the prediction for BR($μ\to e, γ$) is in general larger than the experimental upper boun

C. Bourrely, J. Soffer, F. Buccella

A global next-to-leading order QCD analysis of unpolarized and polarized deep-inelastic scattering data is performed with parton distributions constructed in a statistical physical picture of the nucleon. The chiral properties of QCD lead to strong relations between quarks and antiquarks distributions and the importance of the Pauli exclusion principle is al

Yoshio Koide

Recent trends in the Zee model are reviewed. Especially, the importance of a serious constraint in the Zee model, sin^2 2θ_{solar} =1.0, is pointed out.

Masaaki Fujii, K. Hamaguchi, T. Yanagida

We study the supersymmetric leptogenesis via $LH_{u}$ flat direction with a gauged $U(1)_{B-L}$ symmetry. We find that the resultant baryon asymmetry is enhanced compared with the case without a gauged $U(1)_{B-L}$ symmetry. The baryon asymmetry is proportional to the reheating temperature of inflation, but it is independent of the gravitino mass. If high re

H. Hayakawa, K. Hosokawa, T. Kurimoto

The recently observed CP violation in B decay and $B$-$\ovar{B}$ mixing data put constraints on the mass of $W_R$ and the parameters of the right-handed current quark mixing matrix $V^R$ in $SU(2)_L \times SU(2)_R\times U(1)$ gauge model. It is shown that the allowed region of parameters are severely restricted for light $W_R$ with mass on the order of 1 TeV

S. Kumano

Nuclear parton distribution functions are obtained by a chi^2 analysis of lepton deep inelastic experimental data. It is possible to determine valence-quark distributions at medium x and antiquark distributions at small x; however, the distributions in other x regions and gluon distributions cannot be fixed. We need a variety of experimental data and also fu

The FOCUS Collaboration

We describe the various techniques developed in the Fermilab Wideband Experiments, E687 and FOCUS, to reconstruct long-lived states. The techniques all involve modifications to standard tracking techniques and are useful to report for future experiments.

K. Garrow

The quasielastic (e,e$^\prime$p) reaction was studied on targets of deuterium, carbon, and iron up to a value of momentum transfer $Q^2$ of 8.1 (GeV/c)$^2$. A nuclear transparency was determined by comparing the data to calculations in the Plane-Wave Impulse Approximation. The dependence of the nuclear transparency on $Q^2$ and the mass number $A$ was invest

T. Christodoulakis

The problems encountered in trying to quantize the various cosmological models, are brought forward by means of a concrete example. The Automorphism groups are revealed as the key element through which G.C.T.&#39;s can be used for a general treatment of these problems. At the classical level, the time dependent automorphisms lead to significant simplificatio

T. Christodoulakis, G. O. Papadopoulos

The canonical quantization of the most general minisuperspace actions --i.e. with all six scale factor as well as the lapse function and the shift vector present-- describing the vacuum type II, VI and VII geometries, is considered. The reduction to the corresponding physical degrees of freedom is achieved through the usage of the linear constraints as well

Francois Fages

Nomadic applications create replicas of shared objects that evolve independently while they are disconnected. When reconnecting, the system has to reconcile the divergent replicas. In the log-based approach to reconciliation, such as in the IceCube system, the input is a common initial state and logs of actions that were performed on each replica. The output

James Katz, Ronald E. Rice, Philip Aspden

Our research, which began fielding surveys in 1995, and which have been repeated with variation in 1996, 1997 and 2000, was apparently the first to use national random telephone survey methods to track social and community aspects of Internet use, and to compare users and non-users. It also seems to be among the first that used these methods to compare users

Eneko Agirre, David Martinez

Two kinds of systems have been defined during the long history of WSD: principled systems that define which knowledge types are useful for WSD, and robust systems that use the information sources at hand, such as, dictionaries, light-weight ontologies or hand-tagged corpora. This paper tries to systematize the relation between desired knowledge types and act

E. Agirre, D. Martinez

Selectional preference learning methods have usually focused on word-to-class relations, e.g., a verb selects as its subject a given nominal class. This papers extends previous statistical models to class-to-class preferences, and presents a model that learns selectional preferences for classes of verbs. The motivation is twofold: different senses of a verb

T. Michalareas, L. Sacks

In this paper we present a combinatorial optimisation view on the routing problem for connectionless packet networks by using the metaphor of a landscape. We examine the main properties of the routing landscapes as we define them and how they can help us on the evaluation of the problem difficulty and the generation of effective algorithms. We also present t

Alessandro Mei, Romeo Rizzi

It is shown that a POPS network with g groups and d processors per group can efficiently route any permutation among the n=dg processors. The number of slots used is optimal in the worst case, and is at most the double of the optimum for all permutations p such that p(i)<>i for all i.

Seamus Simpson, Rorden Wilkinson

Drawing on perspectives from telecommunications policy and neo-Gramscian understandings of international political economy, this paper offers an explanation and analysis of the shifting patterns of regulation which have been evident in the telecommunications sector in recent years. It aims to illustrate explain and explore the implications of the movement of

Roman Bartak

Global constraints proved themselves to be an efficient tool for modelling and solving large-scale real-life combinatorial problems. They encapsulate a set of binary constraints and using global reasoning about this set they filter the domains of involved variables better than arc consistency among the set of binary constraints. Moreover, global constraints

Ernesto Villar-Cociña, Eduardo Valencia-Morales, Romulo González- Rodríguez, Jesús Hernández-Ruíz.

In this paper the kinetics of the pozzolanic reaction between lime (calcium hydroxide) and sugar cane straw ash with 20 and 30% of clay burned at 800 and 1000 C is studied. A simple experimental technique where the conductivity is the experimental variable was used. A calibration curve was established for correlating the conductivity with the concentration o

U. Tirnakli, C. Tsallis, M. L. Lyra

We numerically investigate the sensitivity to initial conditions of asymmetric unimodal maps $x_{t+1} = 1-a|x_t|^{z_i}$ ($i=1,2$ correspond to $x_t>0$ and $x_t<0$ respectively, $z_i >1$, $0<a\leq 2$, $t=0,1,2,...$) at the edge of chaos. We employ three distinct algorithms to characterize the power-law sensitivity to initial conditions at the edge of chaos, n

O. Entin-Wohlman, A. Aharony, Y. Imry, Y. Levinson

After briefly reviewing the Fano effect, we explain why it may be relevant to various types of Aharonov-Bohm interferometers. We discuss both closed (electron conserving) and open interferometers, in which one path contains either a simple quantum dot or a decorated quantum dot (with more than one internal state or a parallel path). The possible relevance to

Sergio Albeverio, Shao-Ming Fei

A general way to construct ladder models with certain Lie algebraic or quantum Lie algebraic symmetries is presented. These symmetric models give rise to series of integrable systems. It is shown that corresponding to these SU(2) symmetric integrable ladder models there are exactly solvable stationary discrete-time (resp. continuous-time) Markov processes wi

S. Rapsch, J. T. Chalker, D. K. K. Lee

We study quantum Hall ferromagnets in the presence of a random electrostatic impurity potential. Describing these systems with a classical non-linear sigma model and using analytical estimates supported by results from numerical simulations, we examine the nature of the ground state as a function of disorder strength, $Δ$, and deviation, $δν$, of the average

Italo Guarneri, Marcello Terraneo

We theoretically and numerically demonstrate that completely integrable scattering processes may exhibit fractal transmission fluctuations, due to typical spectral properties of integrable systems. Similar properties also occur with scattering processes in the presence of strong dynamical localization, thus explaining recent numerical observations of fractal

Chih-Yuan Tseng, Ariel Caticha

The ``Gibbs Paradox&#39;&#39; refers to several related questions concerning entropy in thermodynamics and statistical mechanics: whether it is an extensive quantity or not, how it changes when identical particles are mixed, and the proper way to count states in systems of identical particles. Several authors have recognized that the paradox is resolved once

S. Caprara, C. Di Castro, M. Grilli

We analyze the single-particle spectra of a bi-layered electron system near a stripe instability and compare the results with ARPES experiments on the Bi2212 cuprate superconductor near optimum doping, addressing also the issue of the puzzling absence of bonding-antibonding splitting.

H. Ott, J. Fortagh, G. Schlotterbeck, A. Grossmann

Bose-Einstein condensation has been achieved in a magnetic surface micro trap with 4x10^5 87Rb atoms. The strongly anisotropic trapping potential is generated by a microstructure which consists of microfabricated linear copper conductors at a width ranging from 3 to 30 micrometer. After loading a high number of atoms from a pulsed thermal source directly int

A. Wacker, S. -C. Lee

We report gain calculations for a quantum cascade laser using a fully self-consistent quantum mechanical approach based on the theory of nonequilibrium Green functions. Both the absolute value of the gain as well as the spectral position at threshold are in excellent agreement with experimental findings for T=77 K. The gain strongly decreases with temperatur

J. Schiøtz

In recent years it has become possible to study the properties of nanocrystalline metals through atomic-scale simulations of systems with realistic grain sizes. A brief overview of the main results is given, such as the observation of a reverse Hall-Petch effect - a softening of the metal when the grain size is reduced. The limitations of computer simulation

C. Di Castro, M. Grilli, S. Caprara

Within the Hubbard-Holstein model with long-range Coulomb forces, we revisit the charge-ordering scenario for the superconducting cuprates and account for the presence or the absence of a formed stripe phase in different classes of cuprates. We also evaluate the mean-field and the fluctuation-corrected critical lines for charge ordering and we relate them wi

Burkhard Doliwa, Andreas Heuer

We present simulations of a hard disc system and analyze the time evolution of the dynamic heterogeneities. We characterize the time evolution of slow regions and slow particles individually. The motion of slow clusters turns out to be very restricted, i.e. a cluster is generated and annihilated in a spatial region four times the size of its maximum extent.

D. Pini, J. S. Hoye, G. Stell

An Ornstein-Zernike approximation for the two-body correlation function embodying thermodynamic consistency is applied to a system of classical Heisenberg spins on a three-dimensional lattice. The consistency condition determined in a previous work is supplemented by introducing a simplified expression for the mean-square fluctuations of the spin on each lat

Th. Theenhaus, M. Letz, A. Latz, R. Schilling

We investigate hard ellipsoids of revolution in a parameter regime where no long range nematic order is present but already finite size domains are formed which show orientational order. Domain formation leads to a substantial slowing down of a collective rotational mode which separates well from the usual microscopic frequency regime. A dynamic coupling of

Satya N. Majumdar, P. L. Krapivsky

We study the statistics of height and balanced height in the binary search tree problem in computer science. The search tree problem is first mapped to a fragmentation problem which is then further mapped to a modified directed polymer problem on a Cayley tree. We employ the techniques of traveling fronts to solve the polymer problem and translate back to de

K. L. Janssens, B. Partoens, F. M. Peeters

We studied the exciton energy in a type II quantum disk as a function of the magnetic field, disk radius R and height d. We found angular momentum transitions for dots with d >> 2R. Application of an electric field perpendicular to the disk showed a non-linear Stark shift. In the case of three vertically coupled dots angular momentum transistions were found

P. Chaddah

We discuss first-order phase transitions that are broadened by disorder, but still remain first order on the local mesoscopic level. Using vortex-matter as our paradigm, we argue that phase transitions in general can be broadened by two different causes viz. due to a distribution of the phase transition point (field or temperature) from one region of the sam

Klaus Fabricius, Barry M. McCoy

We propose an expression for the current form of the lowering operator of the $ {sl}_2$ loop algebra symmetry of the six vertex model (XXZ spin chain) at roots of unity. This operator has poles which correspond to the evaluation parameters of representation theory which are given as the roots of the Drinfeld polynomial. We explicitly compute these polynomial

Xiaolei Zhang

It is found that a previously thought-to-be well established result of density wave theory, that there is no interaction between a quasi-stationary spiral density wave and the basic state (i.e. the axisymmetric part) of the galactic disk, is in fact false. When solved as a nonlinear and globally self-consistent problem, the presence of non-axisymmetric patte

Priscilla C. Frisch

Observations of interstellar gas and dust towards nearby stars and within the solar system show that the Sun is embedded in a warm diffuse partially-ionized cloud. This cloud is the leading edge of a flow of interstellar matter (ISM) through our Galactic neighborhood. Interstellar matter sets the boundary conditions of the heliosphere and astrospheres of ext

E. Gaztanaga, E. Garcia-Berro, J. Isern, E. Bravo

Recent high-redshift Type Ia supernovae results can be used to set new bounds on a possible variation of the gravitational constant $G$. If the local value of $G$ at the space-time location of distant supernovae is different, it would change both the kinetic energy release and the amount of $^{56}$Ni synthesized in the supernova outburst. Both effects are re

S. Michael Fall, Qing Zhang

In the first part of this article, we review observations of the mass and luminosity functions of young and old star cluster systems. We also review some of the physical processes that may determine the characteristic mass of globular clusters and the form of their mass function. In the second part of this article, we summarize our models for the disruption

Hartmut Bluhm, Klaas S. de Boer

FUSE and IUE observations of Sk -69 246, a WN 6 star to the north of 30 Dor, reveal the existence of LMC interstellar gas in at least 3 velocity components.In one of these components FUSE spectra show strong absorption by molecular hydrogen with a column density of log N(H_2)=19.6. We investigate the physical conditions in this cloud, which is probably locat

Estrella Florido, Eduardo Battaner, Ana Guijarro, Francisco Garzon

We present a first study of truncation of the stellar disks of spiral galaxies in the near infrared. Observations of NGC4013, NGC4217, NGC6504 and NGC5981 were made with the CAIN NIR camera on the CST in Tenerife. This wavelength range provides the best description of the phenomenon, not only because extinction effects are minimized, but also because the dis

A. B. Giles, K. M. Hill, T. E. Strohmayer, N. Cummings

We present a study of the distribution of asymptotic burst oscillation periods for a sample of 26 bursts from 4U 1636-53 observed with the Rossi X-ray Timing Explorer (RXTE). The burst sample includes both archival and proprietary data and spans more than 4.5 years. We also present new optical light curves of V801 Arae, the optical counterpart of 4U 1636-53,

N. Delmotte, D. Egret, C. Loup, M. -R. Cioni

The recent publications of the DENIS Catalogue towards the Magellanic Clouds (MCs) with more than 1.3 million sources identified in at least two of the three DENIS filters (I J K_s) and of the incremental releases of the 2MASS point source catalogues (J H K_s) covering the same region of the sky, provide an unprecedented wealth of data related to stellar pop

Yousaf M. Butt, Diego F. Torres, Jorge A. Combi, Thomas Dame

The non-thermal supernova remnant RX J1713.7-3946 (G347.3-0.5) has recently been shown to be a site of cosmic ray (CR) electron acceleration to TeV energies (Muraishi et al. 2000). Here we present evidence that this remnant is also accelerating CR nuclei. Such nuclei can interact with ambient interstellar gas to produce high energy gamma-rays via the decay o

D. Mehlert, S. Seitz, R. P. Saglia, I. Appenzeller

We present images and long-slit spectra obtained with FORS1 at UT1 of the VLT centered on the gravitational arc of the galaxy cluster 1E0657-56 (z = 0.296). The cluster is one of the hottest, most massive clusters known so far and acts as a powerful gravitational telescope, amplifying the flux of background sources by up to a factor of 17. We present photome

F. Hammer, F. Sayède, E. Gendron, T. Fusco

A large fraction of the present-day stellar mass was formed between z=0.5 and z~3 and our understanding of the formation mechanisms at work at these epochs requires both high spatial and high spectral resolution: one shall simultaneously} obtain images of objects with typical sizes as small as 1-2kpc(~0&#39;&#39;.1), while achieving 20-50 km/s (R >= 5000) sp

D. Lazzati, S. Covino, G. Ghisellini, D. Fugazza

We present photometric and spectroscopic observations of the late afterglow of GRB 000911, starting ~1 day after the burst event and lasting ~8 weeks. We detect a moderately significant re-brightening in the R, I and J lightcurves, associated with a sizable reddening of the spectrum. This can be explained through the presence of an underlying supernova, outs

F. Piron

To date, only two extragalactic objects have been firmly established as very high-energy gamma-ray sources in the Northern sky: these are the two blazars Markarian 501 and Markarian 421. This paper reviews the most striking results obtained from these sources by the CAT atmospheric Cherenkov imaging telescope, with a particular emphasis on the 1999-2000 and

F. Eisenhauer, P. van der Werf, N. Thatte, T. de Zeeuw

SPIFFI is the near-infrared integral-field spectrometer for the VLT. Assisted by the SINFONI adaptive optics module, the instrument will be offered to the astronomical community in 2004. We outline the scientific rationale for infrared integral-field spectroscopy at the VLT, and specifically for the enhancement of SPIFFI with a larger detector and higher spe

Ann Merchant Boesgaard, Jeremy R. King

Beryllium is not destroyed as easily as Li, so the abundances of Li and Be together can tell us more about the internal physical processes in stars than either element can alone. We have obtained high-resolution (45,000) and high signal-to-noise (typically 90 per pixel) spectra of the Be II resonance lines in 34 Hyades F and G dwarfs with the Keck I telescop

Xue-Bing Wu, J. L. Han

A tight correlation of black hole mass and central velocity dispersion has been found recently for both active and quiescent galaxies. By applying this correlation, we develop a simple method to derive the inclination angles for a sample of 11 Seyfert 1 galaxies that have both measured central velocity dispersions and black hole masses estimated by reverbera

A. Y. Poludnenko, A. Frank, E. G. Blackman

Many astrophysical flows occur in inhomogeneous (clumpy) media. We present results of a numerical study of steady, planar shocks interacting with a system of embedded cylindrical clouds. Our study uses a two-dimensional geometry. Our numerical code uses an adaptive mesh refinement allowing us to achieve sufficiently high resolution both at the largest and th

M. Guedel, M. Audard, A. Sres, R. Wehrli

We present an X-ray spectral analysis of four solar analogs with different ages and magnetic activity levels. We find largely different coronal compositions. The most active stars tend to show an ``Inverse First Ionization Potential&#39;&#39; (IFIP) effect, i.e., elements with low FIP are underabundant. Less active stars tend to the opposite effect, with rel

Martin Elvis

The R~300-1000 grating spectra from XMM-Newton and Chandra are a radical advance, allowing spectroscopic physics techniques to be applied to X-ray astronomy, revolutionizing a wide range of research. Ten years on these spectra will be routine, and higher resolution will be needed. I propose ``Thermal Limit Spectroscopy&#39;&#39; as the next natural goal for

Alain Smette, Sara R. Heap, Gerard M. Williger, Todd M. Tripp

We present an HST STIS spectrum of the HeII Gunn-Peterson effect towards HE2347-4342. Compared to the previous HST GHRS data obtained by Reimers et al. (1997), the STIS spectrum has a much improved resolution. The 2-D detector also allows us to better characterize the sky and dark background. We confirm the presence of two spectral ranges of much reduced opa

Itzhak Bars

``Extremely&#39;&#39; localized wavefunctions in noncommutative geometry have disturbances that are localized to distances smaller than $\sqrtθ$, where $θ$ is the ``area&#39;&#39; parameter that measures noncommutativity. In particular, distributions such as the sign function or the Dirac delta function are limiting cases of extremely localized wavefunctions

Joop Schaye

An intriguing fact about cosmic gas clouds is that they all appear to have neutral (atomic) hydrogen column densities smaller than 10^{22} cm^{-2}. Observations of damped Ly-alpha (DLA) absorption systems further indicate that the maximum N(HI) decreases with increasing metallicity. It is generally assumed that this trend is due to a dust-induced selection b

Hwang Lee, Pieter Kok, Nicolas J. Cerf, Jonathan P. Dowling

We propose a method for preparing maximal path entanglement with a definite photon number N, larger than two, using projective measurements. In contrast with the previously known schemes, our method uses only linear optics. Specifically, we exhibit a way of generating four-photon, path-entangled states of the form |4,0> + |0,4>, using only four beam splitter

Darwin Chang, We-Fu Chang, Wai-Yee Keung, Nita Sinha

We investigate the possibility that the CP violation due to the soft supersymmetry breaking terms in squark mixing can give significant contributions to the various $γ$ related parameters in B decays, different from those of the Standard Model. We derive the new limits on $(δ^u_{12})_{LL,LR,RR}$ and on $(δ^d_{23})_{LL,LR,RR}$ from the recent data on $D^0$--$

L. Knox, N. Christensen, C. Skordis

If Omega_tot = 1 and structure formed from adiabatic initial conditions then the age of the Universe, as constrained by measurements of the cosmic microwave background (CMB), is t_0=14.0 +/- 0.5 Gyr. The uncertainty is surprisingly small given that CMB data alone constrain neither h nor Omega_Lambda significantly. It is due to the tight (and accidental) corr

Kento Ichikawa

We propose the relationships between the noncommutative solitons and the (fractional) D-branes on the C^2/Z_n orbifold and extend the solution generating technique for the orbifold. As applications, we determine how tachyon condensations occur in various D-Dbar systems on the orbifolds. The calculations give results consistent with BSFT. The extended solutio

M. B. Hastings

Iterated conformal mappings are used to obtain exact multifractal spectra of the harmonic measure for arbitrary Laplacian random walks in two dimensions. Separate spectra are found to describe scaling of the growth measure in time, of the measure near the growth tip, and of the measure away from the growth tip. The spectra away from the tip coincide with tho

J. Baacke, S. Michalski

We consider the out-of-equilibrium evolution of a classical condensate field and its quantum fluctuations for a scalar O(N) model with spontaneously broken symmetry. In contrast to previous studies we do not consider the large N limit, but the case of finite N, including N=1, i.e., plain $λϕ^ 4$ theory. The instabilities encountered in the one-loop approxima

W. Cassing, L. Jarczyk, B. Kamys, P. Kulessa

The lifetime of the Lambda hyperon in heavy hypernuclei as measured by the COSY-13 Collaboration in proton - Au, Bi and U collisions has been analysed to yield tau(Lambda) = (145 +- 11) ps. This value for tau(Lambda) is compatible with the lifetime extracted from antiproton annihilation on Bi and U targets, however, much more accurate. We find that the depen