September 1998 arXiv papers — page 7

P. Garbaczewski

We analyze an isothermal Brownian motion of particle ensembles in the Smoluchowski approximation. Contrary to standard procedures, the environmental recoil effects associated with locally induced heat flows are not completely disregarded. The main technical tool in the study of such weakly-out-of equilibrium systems is a consequent exploitation of the Hamilt

Iwo Bialynicki-Birula

This article contains a review of an alternative theory of squeezing, based entirely on the wave function description of the squeezed states. Quantum field theoretic approach is used to describe the squeezing of the electromagnetic field in its most complete form that takes into account temporal and spatial characteristics of the squeezed state. An analog of

B. G. Sidharth

We examine conservation laws, typically the conservation of linear momentum, in the light of a recent successful formulation of fermions as Kerr-Newman type Black Holes, which are created fluctuationally from a background Zero Point Field. We conclude that these conservation laws are to be taken in the spirit of thermodynamic laws.

Yuri Ozhigov

Quantum algorithm is constructed which verifies the formulas of predicate calculus in time $O(\sqrt N)$ with bounded error probability, where $N$ is the time required for classical algorithms. This algorithm uses the polynomial number of simultaneous oracle queries. This is a modification of the result of Buhrman, Cleve and Wigderson quant-ph/9802040.

Nina Byers

Emmy Noether proved two deep theorems, and their converses, on the connection between symmetries and conservation laws. Because these theorems are not in the mainstream of her scholarly work, which was the development of modern abstract algebra, it is of some historical interest to examine how she came to make these discoveries. The present paper is an histo

A. V. Afanasjev, I. Ragnarsson, P. Ring

Super- and highly-deformed rotational bands in the A ~ 60 mass region are studied within cranked relativistic mean field theory and the configuration-dependent shell-correction approach based on the cranked Nilsson potential. Both approaches describe the experimental data well. Low values of the dynamic moments of inertia J^(2) compared with the kinematic mo

V. M. Kolomietz, S. Shlomo

The instability of a Fermi-liquid drop with respect to bulk density distortions is considered. It is shown that the presence of the surface strongly reduces the growth rate of the bulk instability of the finite Fermi-liquid drop because of the anomalous dispersion term in the dispersion relation. The instability growth rate is reduced due to the Fermi surfac

M. Del Estal, M. Centelles, X. Viñas

Nuclear matter and surface properties are carefully studied for a model based on an effective hadronic lagrangian with vector-vector and scalar-vector self-interactions. The results of the model are compared with those of the successful standard non-linear $σ-ω$ model.

L. Trache, A. Azhari, H. L. Clark, C. A. Gagliardi

The $^{13}C(^{14}N,^{13}C)^{14}N$ proton exchange reaction has been measured at an incident energy of 162 MeV. Angular distributions were obtained for proton transfer to the ground and low lying excited states in $^{14}N$. Elastic scattering of $^{14}N$ on $^{13}C$ also was measured out to the rainbow angle region in order to find reliable optical model pote

H. -D. Doebner, R. Z. Zhdanov

The family F of all potentials V(x) for which the Hamiltonian H in one space dimension possesses a high order Lie symmetry is determined. A sub-family F', which contains a class of potentials allowing a realization of so(2,1) as spectrum generating algebra of H through differential operators of finite order, is identified. Furthermore and surprisingly, t

Nadia Benakli, Oliver T. Dasbach, Yair Glasner, Brian Mangum

Recently, Rips produced an example of a double of two free groups which has unsolvable generalized word problem. In this paper, we show that Rips's example fits into a large class of doubles of groups, each member of which contains F_2 x F_2 and therefore has unsolvable generalized word problem and is incoherent.

Doron Zeilberger

Rabbi Abraham Ben Meir Ibn Ezra's(1089-1164) computation of the seventh row of the so-called Pascal-Chu triangle is described.

Doron Zeilberger

We prove that the `connective constant' for ternary square-free words is at least $2^{1/17} = 1.0416 ... $, improving on Brinkhuis and Brandenburg's lower bounds of $2^{1/24}=1.0293 ...$ and $2^{1/22}=1.032 ...$ respectively. This is the first improvement since 1983.

Christina Sormani

In 1968, Milnor conjectured that a complete noncompact manifold with nonnegative Ricci curvature has a finitely generated fundamental group. The author applies the Excess Theorem of Abresch and Gromoll (1990), to prove two theorems. The first states that if such a manifold has small linear diameter growth then its fundamental group is finitely generated. The

Klaus Altmann, Jan Stevens

We show that the number of generators of the n-th cotangent cohomology group (n >=2) is the same for all rational surface singularities Y. For a large class of rational surface singularities, including quotient singularities, this number is also the dimension. For them we obtain an explicit formula for the corresponding Poincare series.

Do Ngoc Diep

In this paper we consider the category $C (\tilde k, \tilde H)$ of the $(\tilde k, \tilde H)$-modules, including all the Verma modules, where $k$ is some compact Lie algebra and H some Cartan subgroup, $\tilde k$ and $\tilde H$ are the corresponding affine Lie algebra and the affine Cartan group, respectively. To this category we apply the Zuckerman functor

Theodore Voronov

We consider the following construction of quantization. For a Riemannian manifold $M$ the space of forms on $T^*M$ is made into a space of (full) symbols of operators acting on forms on $M$. This gives rise to the composition of symbols, which is a deformation of the (``super'')commutative multiplication of forms. The symbol calculus is exact for dif

M. Yu. Kalmykov, K. A. Kazakov, P. I. Pronin, K. V. Stepanyantz

In this paper, the dependence of the Einstein gravity with the cosmological constant as well as of this theory in the first-order formalism on the gauge and parametrization is been analyzed. The one-loop counterterms off the mass shell have been plainly calculated in arbitrary gauge and parametrization. The tensor package of analytic calculations, written in

M A Grigoriev, A M Semikhatov

We study the geometry of the triplectic quantization of gauge theories. We show that underlying the triplectic geometry is a Kaehler manifold N endowed with a pair of transversal polarizations. The antibrackets can be brought to the canonical form if and only if N admits a flat symmetric connection that is compatible with the complex structure and the polari

D. G. Robertson, E. S. Swanson, A. P. Szczepaniak, C. -R. Ji

Continuing our previous QCD Hamiltonian studies in the gluonic and quark sectors, we describe a new renormalization procedure which generates an effective Hamiltonian. The formulation, which is in the Coulomb gauge, provides an improved framework for investigating hadron structure.

K. A. Milton, I. L. Solovtsov, O. P. Solovtsova

We apply analytic perturbation theory to the Gross--Llewellyn Smith sum rule. We study the $Q^2$ evolution and the renormalization scheme dependence of the analytic three-loop QCD correction to this sum rule, and demonstrate that the results are practically renormalization scheme independent and lead to rather different $Q^2$ evolution than the standard pert

Zhang Yang

By using Monte Carlo simulation of pomeron exchange model, the dependence of the fractal behavior of the pomeron induced system in deep inelastic lepton-nucleon scattering upon the diffractive kinematic variables is found rather robust and not sensitive to the distinct parameterization of the pomeron flux factor and structure function. Based on this characte

Gerhard Buchalla

The rare decay $B\to X_sl^+l^-$ provides excellent prospects for precision tests of Standard Model flavour dynamics. The process can be computed in perturbation theory with small uncertainty. However, in order to ensure a reliable theoretical prediction, also potentially important effects from non-perturbative QCD have to be controlled with sufficient accura

K. A. Milton, I. L. Solovtsov, O. P. Solovtsova

Results of applying analytic perturbation theory (APT) to the Bjorken sum rule are presented. We study the third-order QCD correction within the analytic approach and investigate its renormalization scheme dependence. We demonstrate that, in the framework of the method, theoretical predictions of the Bjorken sum rule are, practically, scheme independent for

Frank Wilczek

The value of the neutrino mass reported by the SuperK collaboration fits beautifully into the framework of gauge theory unification. Here I justify this claim, and review the other main reasons to believe in that framework. Supersymmetry and SO(10) symmetry are important ingredients; nucleon instability is a dramatic consequence.

Matthias Steinhauser

The decay of the Standard Model Higgs boson in the intermediate-mass range into gluons is considered where special emphasis is put on the influence of the leading electroweak corrections proportional to G_F m_t^2. An effective Lagrangian approach is used where the top quark is integrated out. The evaluation of the coefficient function is performed using two

Gudrun Hiller

We calculate the leading power corrections to the decay rates, distributions and hadronic spectral moments in rare inclusive \bxsll decays in the standard model, using heavy quark expansion (HQE) in $(1/m_b)$ and a phenomenological model implementing the Fermi motion effects of the b-quark bound in the B-hadron. We include next-to-leading order perturbative

James D. Wells

Recent measurements of cosmological parameters from the microwave background radiation, type Ia supernovae, and the age of globular clusters help determine the relic matter density in the universe. It is first shown with mild cosmological assumptions that the relic matter density satisfies $Ω_M h^2 < 0.6$ independent of the cosmological constant and independ

G. L. Gogiberidze, L. K. Gelovani, E. K. Sarkisyan

Multiparticle spike-production process is investigated in central C-Cu collisions at 4.5 $A$ Gev/c per nucleon. The study is based on two different hypotheses - stochastic vs. coherent - of the formation of spikes. To observe manifestations of the stochastic dynamics, the non-regularities in the multiplicity distributions are analyzed using intermittency app

A. L. Kataev, G. Parente, A. V. Sidorov

The improved next-to-next-to-leading order (NNLO) QCD analysis of the experimental data of the CCFR collaboration for the $xF_3$ structure function is made. Theoretical ambiguities of the NNLO fits are estimated by means of the Padé resummation technique, which was applied both in the expanded and non-expanded forms. The NNLO and the new N$^3$LO $α_s(Q^2)$ $

J. M. LoSecco

The atmospheric neutrino anomaly is the apparent reduction of the $ν_μ/ν_{e}$ ratio observed in underground detectors. It represents either a reduction in the muon neutrino interaction rate or an excess of the electron neutrino interaction rate, or both. Unable to answer the question of ``What else could it be?&#39;&#39; this paper explores a number of alter

D. I. Kazakov

It is shown that softly broken theory is equivalent to a rigid theory in external spurion superfield. The singular part of effective action in a broken theory follows from a rigid one by a simple redefinition of the couplings. This gives an explicit relation between the soft and rigid couplings renormalizations. As an illustration the renormalization group f

Tadeusz Wibig, Dorota Sobczynska

Cross sections for proton inelastic collision with different nuclei are described within the Glauber and multiple scattering approximations. A significant difference between approximate `Glauber&#39; formula and exact calculations with a geometrical scaling assumption for very high-energy cross section is shown. Experimental values of proton-proton cross sec

C. J. Horowitz, Gang Li

The neutrino-nucleon cross section is slightly larger than that for $\barν-N$. Therefore, $\barν$ will escape more quickly from core collapse supernovae leaving the star $ν$ rich. A diffusion formalism is used to calculate the time evolution of the mu and tau lepton number densities. These quickly reach steady state equilibria. We estimate that a protoneutro

Daniel J. H. Chung

We calculate analytically and numerically the production of superheavy dark matter (X) when it is coupled to the inflaton field ϕwithin the context of a slow-roll m_ϕ^2 ϕ^2/2 inflationary model with coupling g^2 X^2 ϕ^2/2. We find that X particles with a mass as large as 1000 H_i, where H_i is the value of the Hubble expansion rate at the end of inflation, c

C. Boros, J. T. Londergan, A. W. Thomas

Comparison of structure functions measured in neutrino and charged lepton deep inelastic scattering can be used to test basic properties of parton distribution functions such as the validity of charge symmetry. Recent experiments indicate a substantial discrepancy between $F_2^ν$ and $F_2^μ$ in the region of small Bjorken-x. We discuss nuclear corrections an

Michael C. Ogilvie

Analytic methods for Abelian projection are developed, and a number of results related to string tension measurements are obtained. It is proven that even without gauge fixing, Abelian projection yields string tensions of the underlying non-Abelian theory. Strong arguments are given for similar results in the case where gauge fixing is employed. The subgroup

M. Alford

I review the growing theoretical indications that at high densities color SU(3) gauge symmetry is spontaneously broken by the formation of a quark pair condensate. This leads to a rich phase structure for QCD as a function of temperature and chemical potential. I also discuss the prospects for lattice QCD calculations at finite density, including the Glasgow

M. Göckeler, A. Hoferichter, R. Horsley, D. Pleiter

Quenched lattice QCD calculations with Wilson-type fermions at small quark masses are impeded by exceptional configurations. We show how this problem can be resolved in a practicable way without changing the physics in the chiral limit.

F. Halzen

With an effective telescope area of order $10^4$ m$^2$ for TeV neutrinos, a threshold near $\sim$50 GeV and a pointing accuracy of 2.5 degrees per muon track, the AMANDA detector represents the first of a new generation of high energy neutrino telescopes, reaching a scale envisaged over 25 years ago. We describe early results on the calibration of natural de

Michael P. Reisenberger

Barrett and Crane have proposed a model of simplicial Euclidean quantum gravity in which a central role is played by a class of Spin(4) spin networks called &#34;relativistic spin networks&#34; which satisfy a series of physically motivated constraints. Here a proof is presented that demonstrates that the intertwiner of a vertex of such a spin network is uni

J. Podolsky, K. Vesely

We investigate geodesics in non-homogeneous vacuum pp-wave solutions and demonstrate their chaotic behavior by rigorous analytic and numerical methods. For the particular class of solutions considered, distinct &#34;outcomes&#34; (channels to infinity) are identified, and it is shown that the boundary between different outcomes has a fractal structure. This

K. Ghosh

We consider the thermodynamics of minimally coupled massive scalar field in 3+1 dimensional constant curvature black hole background. The brick wall model of &#39;t Hooft is used. When Scharzschild like coordinates are used it is found that apart from the usual radial brick wall cut-off parammeter an angular cut-off parameter is required to regularize the so

Sonia Fahmy, Raj Jain, Rohit Goyal, Bobby Vandalore

ABR traffic management for point-to-multipoint connections controls the source rate to the minimum rate supported by all the branches of the multicast tree. A number of algorithms have been developed for extending ABR congestion avoidance algorithms to perform feedback consolidation at the branch points. This paper discusses various design options and implem

Madhav V. Marathe, Harry B. Hunt, Richard E. Stearns, Venkatesh Radhakrishnan

We study the efficient approximability of basic graph and logic problems in the literature when instances are specified hierarchically as in \cite{Le89} or are specified by 1-dimensional finite narrow periodic specifications as in \cite{Wa93}. We show that, for most of the problems $Π$ considered when specified using {\bf k-level-restricted} hierarchical spe

Bobby Vandalore, Shivkumar Kalyanaraman, Raj Jain, Rohit Goyal

We model World Wide Web (WWW) servers and clients running over an ATM network using the ABR (available bit rate) service. The WWW servers are modeled using a variant of the SPECweb96 benchmark, while the WWW clients are based on a model by Mah. The traffic generated by this application is typically bursty, i.e., it has active and idle periods in transmission

Sastri Kota, Rohit Goyal, Raj Jain

In this paper, we have provided a summary of the design options in Satellite-ATM technology. A satellite ATM network consists of a space segment of satellites connected by inter-satellite crosslinks, and a ground segment of the various ATM networks. A satellite-ATM interface module connects the satellite network to the ATM networks and performs various call

Tao Jiang, Ming Li, Paul Vitanyi

The incompressibility method is an elementary yet powerful proof technique. It has been used successfully in many areas. To further demonstrate its power and elegance we exhibit new simple proofs using the incompressibility method.

Harry Buhrman, Tao Jiang, Ming Li, Paul Vitanyi

The incompressibility method is an elementary yet powerful proof technique. It has been used successfully in many areas. To further demonstrate its power and elegance we exhibit new simple proofs using the incompressibility method.

Shivkumar Kalyanaraman, Raj Jain, Sonia Fahmy, Rohit Goyal

We propose an explicit rate indication scheme for congestion avoidance in ATM networks. In this scheme, the network switches monitor their load on each link, determining a load factor, the available capacity, and the number of currently active virtual channels. This information is used to advise the sources about the rates at which they should transmit. The

Raj Jain, Shiv Kalyanaraman, Ram Viswanathan

The OSU scheme is a rate-based congestion avoidance scheme for ATM networks using explicit rate indication. This work was one of the first attempts to define explicit rate switch mechanisms and the Resource Management (RM) cell format in Asynchronous Transfer Mode (ATM) networks. The key features of the scheme include explicit rate feedback, congestion avoid

Sonia Fahmy, Raj Jain, Shivkumar Kalyanaraman, Rohit Goyal

The ABR service is designed to fairly allocate the bandwidth unused by higher priority services. The network indicates to the ABR sources the rates at which they should transmit to minimize their cell loss. Switches must constantly measure the demand and available capacity, and divide the capacity fairly among the contending connections. In order to compute

G. Babic, B. Vandalore, R. Jain

In performance analysis and design of communication netword modeling data traffic is important. With introduction of new applications, the characteristics of the data traffic changes. We present a brief review the different models of data traffic and how they have evolved. We present results of data traffic analysis and simulated traffic, which demonstrates

Rohit Goyal, Raj Jain, Sonia Fahmy, Bobby Vandalore

The ATM Guaranteed Frame Rate (GFR) service is intended for best effort traffic that can benefit from minimum throughput guarantees. Edge devices connecting LANs to an ATM network can use GFR to transport multiple TCP/IP connections over a single GFR VC.These devices would typically multiplex VCs into a single FIFO queue. It has been shown that in general, F

Rohit Goyal, Raj Jain, Sonia Fahmy, Bobby Vandalore

Recent enhancements have been proposed to the ATM Unspecified Bit Rate (UBR) service that guarantee a minimum rate at the frame level to the UBR VCs. These enhancements have been called Guaranteed Frame Rate (GFR). In this paper, we discuss the motivation, design and implementation issues for GFR. We present the design of buffer management and policing mecha

ohit Goyal, Raj Jain, Shiv Kalyanaraman, Sonia Fahmy

In this paper we study the design issues in improving TCP performance over the ATM UBR service. ATM-UBR switches respond to congestion by dropping cells when their buffers become full. TCP connections running over UBR can experience low throughput and high unfairness. Intelligent switch drop policies and end-system policies can improve the performance of TCP

Rohit Goyal, Sastri Kota, Raj Jain, Sonia Fahmy

In this paper we present a model to study the end-to-end delay performance of a satellite-ATM netowrk. We describe a satellite-ATM network architecture. The architecture presents a trade-off between the on-board switching/processing features and the complexity of the satellite communication systems. The end-to-end delay of a connection passing through a sate

Niels Ole Bernsen, Laila Dybkjaer, eds.

The DISC project aims to (a) build an in-depth understanding of the state-of-the-art in spoken language dialogue systems (SLDSs) and components development and evaluation with the purpose of (b) developing a first best practice methodology in the field. The methodology will be accompanied by (c) a series of development and evaluation support tools. To the li

Wolfgang Lezius, Reinhard Rapp, Manfred Wettler

In this paper we present Morphy, an integrated tool for German morphology, part-of-speech tagging and context-sensitive lemmatization. Its large lexicon of more than 320,000 word forms plus its ability to process German compound nouns guarantee a wide morphological coverage. Syntactic ambiguities can be resolved with a standard statistical part-of-speech tag

Peter J Bentley

This paper examines the four main types of Evolutionary Design by computers: Evolutionary Design Optimisation, Evolutionary Art, Evolutionary Artificial Life Forms and Creative Evolutionary Design. Definitions for all four areas are provided. A review of current work in each of these areas is given, with examples of the types of applications that have been t

Rohit Goyal, Steve Lai, Raj Jain, Arian Durresi

In this paper we describe a hands-on laboratory oriented instructional package that we have developed for data communications and networking. The package consists of a software tool, together with instructional material for a laboratory based networking curriculum. The software is based on a simulation environment that enables the student to experiment with

Rohit Goyal, Raj Jain, Sonia Fahmy, Shobana Narayanaswamy

Asynchronous transfer mode (ATM) is the new generation of computer and communication networks that are being deployed throughout the telecommunication industry as well as in campus backbones. ATM technology distinguishes itself from the previous networking protocols in that it has the latest traffic management technology and thus allows guaranteeing delay, t

Sonia Fahmy, Raj Jain, Rohit Goyal, Bobby Vandalore

In multipoint-to-point connections, the traffic at the root (destination) is the combination of all traffic originating at the leaves. A crucial concern in the case of multiple senders is how to define fairness within a multicast group and among groups and point-to-point connections. Fairness definition can be complicated since the multipoint connection can

Shivkumar Kalyanaraman, Bobby Vandalore, Raj Jain, Rohit Goyal

Compressed video is well known to be self-similar in nature. We model VBR carrying Long-Range Dependent (LRD), multiplexed MPEG-2 video sources. The actual traffic for the model is generated using fast-fourier transform of generate the fractional gaussian noise (FGN) sequence. Our model of compressed video sources bears similarity to an MPEG-2 Transport Stre

Nataliya A. Zimbovskaya, Joseph L. Birman

We introduce a new generic model of a deformed Composite Fermion-Fermi Surface (CF-FS) for the Fractional Quantum Hall Effect near $/nu=1/2$ in the presence of a periodic density modulation. Our model permits us to explain recent Surface Acoustic Wave observations of anisotropic anomalies [1,2] in sound velocity and attenuation- appearance of peaks and aniso

A. L. Shelankov

The controversial question of the transverse force exerted by the Aharonov-Bohm (AB) magnetic flux line is reconsidered with the help of a new paraxial solution to the AB-scattering problem. It is shown that despite the left-right symmetry in the AB scattering cross-section, a beam of a finite width is deflected by the AB-line as if by the ``Lorentz&#39;&#39

F. Kassubek, C. A. Stafford, Hermann Grabert

The conducting and mechanical properties of a metallic nanowire formed at the junction between two macroscopic metallic electrodes are investigated. Both two- and three-dimensional wires with a W(ide)-N(arrow)-W(ide) geometry are modelled in the free-electron approximation with hard-wall boundary conditions. Tunneling and quantum-size effects are treated exa

A. K. Kienappel, M. A. Moore

We report on simulations of layered superconductors using the Lawrence-Doniach model in the framework of the lowest Landau level approximation. We find a first order phase transition with a $B(T)$ dependence which agrees very well with the experimental ``melting&#39;&#39; line in YBaCuO. The transition is not associated with vortex lattice melting, but separ

C. H. Booth, D. E. MacLaughlin, R. H. Heffner, R. Chau

X-ray-absorption fine-structure measurements of the local structure in UCu_4Pd are described which indicate a probable lattice-disorder origin for non-Fermi-liquid behavior in this material. Short Pd-Cu distances are observed, consistent with 24 +/- 3% of the Pd atoms occupying nominally Cu sites. A &#34;Kondo disorder&#34; model, based on the effect on the

D. S. McLachlan, W. D. Heiss, C. Chiteme, Junjie Wu

Scaling functions, $F_+(ω/ω_c^+)$ and $F_-(ω/ω_c^-)$ for $ϕ>ϕ_c$ and $ϕ<ϕ_c$, respectively, are derived from an equation for the complex conductivity of binary conductor-insulator composites. It is shown that the real and imaginary parts of $F_{\pm}$ display most properties required for the percolation scaling functions. One difference is that, for $ω/ω_c<1$

Luca Peliti, Mohammed Saber

We study the phase transitions of the spin-1/2 Ising film in a transverse field within the framework of the effective field theory. We evaluate the critical temperature of the film as a function of the exchange interactions, the transverse field and the film thickness. We find that, if the ratio of the surface exchange interactions to the bulk ones R=Js/J is

Emilio N. M. Cirillo, Giuseppe Gonnella, Sebastiano Stramaglia

We measure the persistence exponent in a phase separating two-dimensional spin system with non-conserved dynamics quenched in a region with four coexisting stripe phases. The system is an Ising model with nearest neighbor, next-to-the-nearest neighbor and plaquette interactions. Due the particular nature of the ground states, the order parameter is defined i

J. J. Betouras, S. Fujimoto

The transport properties of the ferromagnetic Kondo lattice model in one dimension are studied via bosonization methods. The antiferromagnetic fluctuations, which normally appear because of the RKKY interactions, are explicitly taken into account as a direct exchange between the ``core&#39;&#39; spins. It is shown that in the paramagnetic regime with the loc

M. Montagna, G. Ruocco, G. Viliani, R. Di Leonardo

We propose an explanation for the quadratic dependence on the momentum $Q$, of the broadening of the acoustic excitation peak recently found in the study of the dynamic structure factor of many real and simulated glasses. We ascribe the observed $Q^2$ law to the spatial fluctuations of the local wavelength of the collective vibrational modes, in turn produce

S. A. Antonenko, A. I. Sokolov

The critical behavior of a model with N-vector complex order parameter and three quartic coupling constants that describes phase transitions in unconventional superconductors, helical magnets, stacked triangular antiferromagnets, superfluid helium-3, and zero-temperature transitions in fully frustrated Josephson-junction arrays is studied within the field- t

I. M. Khalatnikov, M. Kroyter

We analyze stability of a system which contains an harmonic oscillator non-linearly coupled to its second harmonic, in the presence of a driving force. It is found that there always exists a critical amplitude of the driving force above which a loss of stability appears. The dependence of the critical input power on the physical parameters is analyzed. For a

B. Kaulakys

Area preserving maps provide the simplest and most accurate means to visualize and quantify the behavior of nonlinear systems. Convenience of the mapping equations of motion for investigation of transition to chaotic behavior in dynamics of classical atom in microwave field, transition to nonchaotic behavior in randomly driven systems and induced quantum dyn

Mitchell C. Begelman

I propose that the moving `wisps&#39; near the center of the Crab Nebula result from nonlinear Kelvin-Helmholtz instabilities in the equatorial plane of the shocked pulsar wind. Recent observations suggest that the wisps trace out circular wavefronts in this plane, expanding radially at speeds approximately less than c/3. Instabilities could develop if there

Inma Domínguez, Peter Höflich, Oscar Straniero Craig Wheeler, Friedrich-Karl Thielemann

The influence of the initial composition and structure of the exploding white dwarf on the nucleosynthesis and structure of Type Ia Supernovae has been studied. The progenitor structures are based on detailed stellar evolutionary tracks for stars in the mass range between 1 to 9 $M_\odot$ using the state of the art code FRANEC. The calculations of the thermo

Avishai Dekel

I describe a general formalism for galaxy biasing (Dekel & Lahav 1998) and its application to measurements of beta (=Omega^0.6/b), e.g. via direct comparisons of light and mass and via redshift distortions. The linear and deterministic relation g=b*d between the density fluctuation fields of galaxies g and mass d is replaced by the conditional distribution P

Dan Maoz

Imaging studies have shown that about 25% of LINER galaxies display a compact nuclear UV source. I compare the HST ultraviolet spectra now available for seven such ``UV-bright&#39;&#39; LINERs. The spectra of NGC 404, NGC 4569, and NGC 5055 show clear absorption-line signatures of massive stars, indicating a stellar origin for the UV continuum. Similar featu

P. P. Gladwin, S. Kitsionas, H. M. J. Boffin, A. P. Whitworth

We analyse and compare the clustering of young stars in Chamaeleon I and Taurus. We compute the mean surface-density of companion stars \bar{N} as a function of angular displacement θfrom each star. We then fit \bar{N}(θ) with two simultaneous power laws. For Chamaeleon I, the exponents of the power laws are 1.97 and 0.28, with the elbow at ~0.011 degrees. F

Paolo Salucci, Ewa Szuszkiewicz, Pierluigi Monaco, Luigi Danese

In our recent paper (Salucci et al. 1998) we have investigated the mass distribution function of massive dark objects in galaxies, exploiting the available optical and radio observations. Under the assumption that massive black holes power active galactic nuclei, we have compared the mass functions of massive dark objects and black holes responsible for the

F. Frontera, M. Orlandini, L. Amati, D. Dal Fiume

We report on two X-ray observations of the transient source XTE J0421+560 performed by BeppoSAX, and on a series of observations performed by the 0.7m Teramo-Normale Telescope. Outburst peak occurrence time and duration depend on photon energy: the outburst peak is achieved first in the X-ray band, then in the optical and finally in the radio. An exponential

E. Meyer-Hofmeister, F. Meyer, B. F. Liu

We model the evolution of the accretion disk of WZ Sagittae during the long quiescence. We find that the large amount of mass in the disk derived from the outburst luminosity is a severe constraint and demands values of $α_c$ $\approx$ 0.001 in contradiction to some recent suggestions. We include in our computations the formation of an inner disk hole and th

R. Sadat

We show how Type Ia/II supernova rates at various redshifts can be used to follow the cosmic star formation rate (CSFR) history. Using the recent e stimate of the Cosmic Star Formation (CSFR), we compute the predicted cosmic Type Ia/II supernovae rates. We show that while SNII rates provide a direct measurement of the instantaneous CSFR, the SNIa rate depend

P. N. Best, H. J. A. R&#34;ottgering, M. N. Bremer, A. Cimatti

The results of a deep submillimetre observation using SCUBA of the powerful radio galaxy 3C324, at redshift z=1.206, are presented. At 850 microns, emission from the location of the host radio galaxy is marginally detected at the 4.2 sigma level, 3.01 +/- 0.72 mJy, but there is no detection of emission at 450 microns to a 3 sigma limit of 21 mJy. A new 32 GH

Carlos Abia, Ute Lisenfeld, Jordi Isern

It is well known that no time-independent galactic cosmic ray (GCR) flux model can account for the observed linear relationship of Be and B abundances with metallicity. In this contribution we solve the time-dependent CR propagation equation using simple analytic time dependences for the CR spectrum at the source, the galactic CR escape-length and gas densit

John P. Ralston, Pankaj Jain

Polarizations of electromagnetic waves from distant galaxies are known to be correlated with the source orientations. These quantities have been used to search for signals of cosmological birefringence. We review and classify transformation properties of the polarization and source orientation observables. The classifications give a firm foundation to certai

I. K. Baldry, M. Viskum, T. R. Bedding, H. Kjeldsen

We present bisector measurements of the H-alpha line of the rapidly oscillating Ap (roAp) star, Alpha-Cir, obtained from dual-site observations with medium-dispersion spectrographs. The velocity amplitude and phase of the principal pulsation mode vary significantly, depending on the height in the H-alpha line, including a phase reversal between the core and

M. Ruffert, H. -Th. Janka

By means of three-dimensional hydrodynamic simulations with a Eulerian PPM code we investigate the formation and the properties of the accretion torus around the stellar mass black hole which originates from the merging of two neutron stars. The simulations are performed with four nested cartesian grids which allow for both a good resolution near the central

Savdeep Sethi

We show that three-dimensional N=8 $Sp(N)$ and $SO(2N+1)$ gauge theories flow to the same strong coupling fixed point. As a consequence, the corresponding orientifold two-planes in type IIA string theory are described at strong coupling and low-energies by the same M theory background. In the large $N$ limit, these assertions are confirmed by studying discre

Robert M. Geller, Robert J. Sault, Robert Antonucci, Neil E. B. Killeen

Standard big bang nucleosynthesis predicts the average baryon density of the Universe to be a few percent of the critical density. Only about one tenth of the predicted baryons have been seen. A plausible respository for the missing baryons is in a diffuse ionized intergalactic medium (IGM). In an attempt to measure the IGM we searched for Thomson-scattered

Brian D. Fields, Keith A. Olive

Because of the roughly linear correlation between Be/H and Fe/H in low metallicity halo stars, it has been argued that a ``primary&#39;&#39; component in the nucleosynthesis of Be must be present in addition to the ``secondary&#39;&#39; component from standard Galactic cosmic ray nucleosynthesis. In this paper we critically re-evaluate the evidence for the p

Tim D. Cochran, Paul Melvin

This paper provides a topological interpretation for number theoretic properties of quantum invariants of 3-manifolds. In particular, it is shown that the p-adic valuation of the quantum SO(3)-invariant of a 3-manifold M, for odd primes p, is bounded below by a linear function of the mod p first betti number of M. Sharper bounds using more delicate topologic

F. Jegerlehner, O. V. Tarasov

A two-loop calculation of the renormalization group $β$--function in a momentum subtraction scheme with massive quarks is presented using the background field formalism. The results have been obtained by using a set of new generalized recurrence relations proposed recently by one of the authors (O.V.T.). The behavior of the mass dependent effective coupling

I. Vekhter, P. J. Hirschfeld, J. P. Carbotte, E. J. Nicol

We show that the density of states and the thermodynamic properties of a 2D d-wave superconductor in the vortex state with applied magnetic field $\bf H$ in the plane depend on the angle between $\bf H$ and the order parameter nodes. Within a semiclassical treatment of the extended quasiparticle states, we obtain fourfold oscillations of the specific heat, m

N. Lütkenhaus, J. Calsamiglia, K-A. Suominen

In this paper we investigate the possibility to make complete Bell measurements on a product Hilbert space of two two-level bosonic systems. We restrict our tools to linear elements, like beam splitters and phase shifters, delay lines and electronically switched linear elements, photo-detectors, and auxiliary bosons. As a result we show that with these tools

M. V. Polyakov

We study the hard exclusive production of two pions in the virtual photon fragmentation region with various invariant masses including the resonance region. The amplitude is expressed in terms of two-pion light cone distribution amplitudes ($2π$DA&#39;s). We derive dispersion relations for these amplitudes, which enables us to fix them completely in terms of

A. Yu. Smirnov

We discuss various aspects of the solar neutrino spectrum distortion and time variations of fluxes. (i) Oscillations of neutrinos which cross the mantle and the core of the Earth can be parametrically enhanced. The parametric effect gives correct physical interpretation of the calculated day-night asymmetry. (ii) Solution of the $ν_{\odot}$-problem in scheme