October 1999 arXiv papers — page 13

Alain Riazuelo, Nathalie Deruelle, Patrick Peter

We consider a network of topological defects which can partly decay into neutrinos, photons, baryons, or Cold Dark Matter. We find that the degree-scale amplitude of the cosmic microwave background (CMB) anisotropies as well as the shape of the matter power spectrum can be considerably modified when such a decay is taken into account. We conclude that presen

Sh. Farhangfar, A. J. Manninen, J. P. Pekola

We present results of a set of experiments to investigate the effect of dissipative external electromagnetic environment on tunneling in linear arrays of junctions in the weak tunneling regime. The influence of this resistance decreases as the number of junctions in the chain increases and ultimately becomes negligible. Further, there is a value of external

O. Bertolami, P. J. Martins

Recent studies of Type Ia Supernovae with redshifts up to about $z~\laq~1$ reveal evidence for a cosmic acceleration in the expansion of the Universe. The most straightforward explanation to account for this acceleration is a cosmological constant dominating the recent history of our Universe; however, a more interesting suggestion is to consider an evolving

N. A. Obers, B. Pioline

We discuss the relevance of Eisenstein series for representing certain G(Z)-invariant string theory amplitudes which receive corrections from BPS states only. The Eisenstein series are constructed using G(Z)-invariant mass formulae and are manifestly invariant modular functions on the symmetric space K\G(R) of non-compact type, with K the maximal compact sub

Gerald Paul, Sergey V. Buldyrev, Nikolay V. Dokholyan, Shlomo Havlin

On two-dimensional percolation clusters at the percolation threshold, we study $<\sigma(M_B,r)>$, the average conductance of the backbone, defined by two points separated by Euclidean distance $r$, of mass $M_B$. We find that with increasing $M_B$ and for fixed r, $<\sigma(M_B,r)>$ asymptotically {\it decreases} to a constant, in contrast with the behavior o

S. Ciuchi, A. Crisanti

We study the role of different terms in the $N$-body potential of glass forming systems on the critical dynamics near the glass transition. Using a simplified spin model with quenched disorder, where the different terms of the real $N$-body potential are mapped into multi-spin interactions, we identified three possible scenarios. For each scenario we introdu

Emil Lundh, P. Ao

We study a vortex in a two-dimensional, harmonically trapped Bose-Einstein condensate at zero temperature. Through a variational calculation using a trial condensate wave function and a nonlinear Schroedinger Lagrangian, we obtain the effective potential experienced by a vortex at an arbitrary position in the condensate, and find that an off-center vortex wi

M. Czakon

The oblique part of the radiative corrections to the Left-Right model is described. The leading non-logarithmic terms are explicitly written. It is argued, on the basis of a comparison with the Standard Model, that one cannot use the loop contributions of the latter to refine phenomenological analyses of the Left-Right model, and by the same of any general e

E. Marinari, G. Parisi, F. Ricci-Tersenghi, J. J. Ruiz-Lorenzo

We present a high statistic systematic study of the overlap correlation function well below the critical temperature in the three dimensional Gaussian spin glass. The off-equilibrium correlation function has been studied confirming the power law behavior for the dynamical correlation length. In particular we have computed the dynamical critical exponent $z$

A. Amici, P. Thalmeier, P. Fulde

We present a theory of superconductivity in presence of a general magnetic structure in a form suitable for the description of complex magnetic phases encountered in borocarbides. The theory, complemented with some details of the band structure and with the magnetic phase diagram, may explain the nearly reentrant behaviour and the anisotropy of the upper cri

O. V. Utyuzh, G. Wilk, Z. Wlodarczyk

Using simple space-time implementation of the random cascade model we investigate numerically influence of the possible fractal structure of the emitting source on Bose-Einstein correlations between identical particles. The results are then discussed in terms of the non-extensive Tsallis statistics.

Michael Aizenman, Jeffrey H. Schenker, Roland M. Friedrich, Dirk Hundertmark

A technically convenient signature of localization, exhibited by discrete operators with random potentials, is exponential decay of the fractional moments of the Green function within the appropriate energy ranges. Known implications include: spectral localization, absence of level repulsion, strong form of dynamical localization, and a related condition whi

Dag Østvang

According to the socalled &#34;quasi-metric&#34; framework developed elsewhere, the cosmic expansion applies directly to gravitationally bound systems. This prediction has a number of observable consequences, none of which are in conflict with observation. In this paper we compare test particle motion in the nonstatic gravitational field outside a sphericall

Masahide Yamaguchi, Jun'ichi Yokoyama, M. Kawasaki

We evolve the network of global strings in the matter-dominated universe by means of numerical simulations. The existence of the scaling solution is confirmed as in the radiation-dominated universe but the scaling parameter $\xi$ takes a slightly smaller value, $\xi \simeq 0.6 \pm 0.1$, which is defined as $\xi = \rho_{s} t^{2} / \mu$ with $\rho_{s}$ the ene

Rebecca Menes, Niels Gronbech Jensen, Phil A. Pincus

Using both theoretical modeling and computer simulations we study a model system for DNA interactions in the vicinity of charged membranes. We focus on the polarization of the mobile charges in the membranes due to the nearby charged rods (DNA) and the resulting screening of their fields and inter-rod interactions. We find, both within a Debye-Huckel model a

D. Grecu, Anca Visinescu, A. S. Carstea

Multi scales method is used to analyze a nonlinear differential-difference equation. In order $ε^3$ the NLS equation is found to determine the space-time evolution of the leading amplitude. In the next order this has to satisfy a complex mKdV equation (the next in the NLS hierarchy) in order to eliminate secular terms. The zero dispersion point case is also

Howard N. Barnum

I consider the use of entanglement between two parties to enable one to authenticate her identity to another over a quantum communication channel. Exploiting the phenomenon of entanglement-catalyzed transformations between pure states gives a potentially reusable entangled identification token. In analyzing this, I consider the independently interesting prob

A. Sinha, R. Roychoudhury

A formalism is developed to obtain the energy eigenvalues of spatially confined quantum mechanical systems in the framework of The usual WKB and MAF methods. The technique is applied to three different cases,viz one dimensional Harmonic Oscillators,Quartic Oscillators and a boxed-in charged particle in electric field.

N. Cufaro Petroni, S. De Martino, S. De Siena, F. Illuminati

We study the nonstationary solutions of Fokker-Planck equations associated to either stationary or nonstationary quantum states. In particular we discuss the stationary states of quantum systems with singular velocity fields. We introduce a technique that allows to realize arbitrary evolutions ruled by these equations, to account for controlled quantum trans

Kazuyuki Fujii

We give a possible generalization to the example in the paper of Zanardi and Rasetti (quant-ph/9904011). For this generalized one explicit forms of adiabatic connection, curvature and etc. are given.

M. Costa, I. R. Pimentel, T. Santiago, M. J. Rebocho

A parasystole from a heart-transplant patient is analysed using a beat-to-beat RR interval time series obtained from an electrocardiogram (ECG). The dysrhythmia, resulting from the co-existence of two pacemakers, the sinus node and an ectopic focus, presents distinctive regular patterns, with transitions from one pattern to another occurring abruptly. It is

A. T. Kruppa, M. Bender, W. Nazarewicz, P. -G. Reinhard

Shell corrections to the nuclear binding energy as a measure of shell effects in superheavy nuclei are studied within the self-consistent Skyrme-Hartree-Fock and Relativistic Mean-Field theories. Due to the presence of low-lying proton continuum resulting in a free particle gas, special attention is paid to the treatment of single-particle level density. To

I. Fachruddin, W. Gloeckle

At intermediate energies it appears advantageous to work without partial wave decomposition and use directly the momentum vectors. We derived a finite set of coupled Lippmann-Schwinger equations using helicities. They can be used for any type of realistic NN forces, which are given in operator form. As an example we have chosen the Bonn OBEPR NN potential.

N. Kaiser

We calculate in (two-loop) chiral perturbation theory the local NN-potentials generated by certain classes of three-pion exchange diagrams. We stress that the chiral $3πNN$-contact vertex depends on the particular choice of the interpolating pion-field and therefore one has to consider representation invariant classes of diagrams by supplementing graphs invo

K. Kabir, T. K. Dutta, Muslema Pervin, L. M. Nath

In this paper we have studied the two-pion exchange three-nucleon potential $(2πE-3NP)$ using an approximate $SU(2) \times SU(2)$ chiral symmetry of the strong interaction. The off-shell pion-nucleon scattering amplitudes obtained from the Weinberg Lagangian are supplemented with contributions from the well-known $σ$-term and the $Δ(1232)$ exchange. It is th

R. Michael Howe, Tuong Ton-That

The structure of r-fold tensor products of irreducible tame representations of the inductive limit U(\infty) of unitary groups U(n) are are described, versions of contragredient representations and invariants are realized on Bargmann-Segal-Fock spaces.

M. El Falaki, E. H. Tahri

We show that the 1+1-dimensional quantum superplane introduced by Manin is a quantum supergroup according to the Faddeev-Reshetikhin-Takhtajan approach. We give its supermatrix element, its corresponding R-matrix and its Hopf structure. This new point of view allows us, first, to realize its dual Hopf superalgebra starting from postulated initial pairings. S

Christian Baer

Let D be a self-adjoint differential operator of Dirac type acting on sections in a vector bundle over a closed Riemannian manifold M. Let H be a closed D-invariant subspace of the Hilbert space of square integrable sections. Suppose D restricted to H is semibounded. We show that every element u in H has the weak unique continuation property, i.e. if u vanis

Roberto Scipioni

The mathematical relations between certain classical Non-Riemannian gravity models and Einstein-Proca theories are discussed in details. We also show some relations with theories with scalar fields.

Vadim Kostrykin, Robert Schrader

In this article we formulate and discuss one particle quantum scattering theory on an arbitrary finite graph with $n$ open ends and where we define the Hamiltonian to be (minus) the Laplace operator with general boundary conditions at the vertices. This results in a scattering theory with $n$ channels. The corresponding on-shell S-matrix formed by the reflec

Lajos Soukup

We give a simplified proof of a theorem of M. Rabus and S. Shelah claiming that for each cardinal mu there is a c.c.c Boolean algebra with topological density mu.

Manuel de Leon, Belen Lopez, Juan C. Marrero, Edith Padron

Lichnerowicz-Jacobi cohomology and homology of Jacobi manifolds are reviewed. We present both in a unified approach using the representation of the Lie algebra of functions on itself by means of the hamiltonian vector fields. The use of the associated Lie algebroid allows to prove that the Lichnerowicz-Jacobi cohomology and homology are invariant under confo

Dmitry Roytenberg

In this dissertation we study Courant algebroids, objects that first appeared in the work of T. Courant on Dirac structures; they were later studied by Liu, Weinstein and Xu who used Courant algebroids to generalize the notion of the Drinfeld double to Lie bialgebroids. As a first step towards understanding the complicated properties of Courant algebroids, w

David Damanik, Daniel Lenz

We consider discrete one-dimensional Schrödinger operators with strictly ergodic, aperiodic potentials taking finitely many values. The well-known tendency of these operators to have purely singular continuous spectrum of zero Lebesgue measure is further elucidated. We provide a unified approach to both the study of the spectral type as well as the measure o

Philip C. Argyres, Alex Buchel

New S-dualities in a scale invariant N=2 gauge theory with SU(2) x SU(2) gauge group are derived from embeddings of the theory in two different larger asymptotically free theories. The true coupling space of the scale invariant theory is a 20-fold identification of the coupling space found in the M- and string-theory derivations of the low energy effective a

Ramzi R. Khuri

In a recent essay, we discussed the possibility of using polymer sizing to model the collapse of a single, long excited string to a black hole. In this letter, we apply this idea to bring further support to string/black hole correspondence. In particular, we reproduce Horowitz and Polchinki&#39;s results for self-gravitating fundamental strings and speculate

Beatriz Gato-Rivera

Subsingular vectors of the N=2 superconformal algebras were discovered, and examples given, in 1996. Shortly afterwards Semikhatov and Tipunin claimed to have obtained a complete classification of the N=2 subsingular vectors in the paper `The Structure of Verma Modules over the N=2 Superconformal algebra&#39;, hep-th/9704111, published in CMP 195 (1998) 129.

G. Sh. Japaridze, K. Sh. Turashvili

A renormalization scheme is suggested where QCD input parameters - quark mass and coupling constant - are expressed in terms of gauge invariant and infrared stable quantities. For the renormalization of coupling constant the quark anomalous electromagnetic moment is used; the latter is calculated in a two loop approximation. Examination of the renormalized S

Teparksorn Pengpan

We extend equal rank embedding of reductive Lie algebras to that of basic Lie superalgebras. The Kac character formulas for equal rank embedding are derived in terms of subalgebras and Kostant&#39;s cubic Dirac operator for equal rank embedding of Lie superalgebras is constructed from both even and odd generators and their related structure constants.

Timothy J. Hollowood, Valentin V. Khoze, Michael P. Mattis

Following work on theories with SU(N) gauge groups, we perform a large-N saddle-point approximation of the measure for ADHM multi-instantons in N=4 supersymmetric gauge theories with symplectic or orthogonal gauge groups. For Sp(N) we find that a saddle-point only exists in the even instanton charge sector. For either Sp(N) or SO(N) the saddle-point solution

Steven S. Gubser

Asymptotically anti-de Sitter spacetimes with Poincare invariance along the boundary can describe, via the AdS/CFT correspondence, either relevant deformations of a conformal field theory or non-conformal vacuum states. I consider examples of both types constructed in the framework of five-dimensional gauged supergravity. I explain the proof and motivation o

Mikhail S. Volkov

The N=4 gauged SU(2)$\times$SU(1,1) supergravity in four-dimensional Euclidean space is obtained via a consistent dimensional reduction of the N=1, D=10 supergravity on $S^3\times AdS_3$. The dilaton potential in the theory is proportional to the difference of the two gauge coupling constants, which is due to the opposite signs of the curvatures of $S^3$ and

Shin&#39;ichi Nojiri, Sergei D. Odintsov

We calculate the conformal anomaly from 5d Weyl gravity (with broken conformal symmetry) which is conjectured to be supergravity dual to ${\cal N}=2$ superconformal field theory via AdS/CFT correspondence. Its comparison with ${\cal N}=2$ SCFT conformal anomaly (UV calculation) suggests that such duality may exist subject to presence of sub-leading 1/N corre

J. Balog, L. Feher, L. Palla

It is well-known that the chiral WZNW Bloch waves satisfy a quadratic classical exchange algebra which implies the affine Kac-Moody algebra for the corresponding currents. We here obtain a direct derivation of the exchange algebra by inverting the symplectic form on the space of Bloch waves, and give a completely algorithmic construction of its generalized f

Alfredo T. Suzuki, Alexandre G. M. Schmidt

Negative dimensional integration method (NDIM) seems to be a very promising technique for evaluating massless and/or massive Feynman diagrams. It is unique in the sense that the method simultaneously gives solutions in different regions of external momenta. Moreover, it is a technique whereby the difficulties associated with performing parametric integrals -

G. Jikia, S. Soldner-Rembold

We have studied the production of a light Higgs boson with a mass of 120 GeV in photon-photon collisions at a Compton collider. The event generator for the backgrounds to a Higgs signal due to bbbar and ccbar heavy quark pair production in polarized gamma-gamma collisions is based on a complete next-to-leading order (NLO) perturbative QCD calculation. For J_

A. Gall

Nonrelativstic effective field theories have shown to be a useful framework to describe systems of weakly bound particles. This work focuses on the matching procedure to the underlying relativistic theory. The concept of a physical mass in the absence of explicit Lorentz symmetry and the matching conditions for S-matrix elements and Green&#39;s functions are

Marek Gazdzicki

The experimental results on the pion, strangeness and J/psi production in high energy nuclear collisions are discussed. The anomalous energy dependence of pion and strangeness production is consistent with the hypothesis that a transition to a deconfined phase takes place between the top AGS (15 AGeV) and the SPS (200 AGeV) energies. The J/psi production sys

Nick Evans

The modern precision accelerator data has essentially ruled out the most obvious model of dynamical electroweak symmetry breaking, technicolour. The idea is though well motivated and it is important to construct models compatible with the precision data of this ilk to motivate experimental searches. We describe the top-see-saw and flavour universal symmetry

B. Kerbikov

Pronounced effects due to final state hyperon-nucleon interaction are predicted in strangeness photoproduction reaction on the deuteron. Use is made of the covariant reaction formalism and the P- matrix approach to the hyperon-nucleon interaction.

T. Carli

Recent \alphas determinations from jet production at HERA are presented. Three different observables lead to consistent alpha values. The result is consistent with the world average and has an error of about 0.006. This is quite a remarkable result, since it is only slightly less precise than the world average.

Yoshio Koide

On the basis of the universal seesaw mass matrix model, which is a promising model of the unified description of the quark and lepton mass matrices, the behaviors of the gauge coupling constants and intermediate energy scales in the SO(10)_L \times SO(10)_R model are investigated related to the neutrino mass generation scenarios. The non-SUSY model cannot gi

W. L. van Neerven

We have calculated first and second order corrections to several sum rules measured in deep inelastic lepton-hadron scattering. These corrections, which are due to heavy flavors only, are compared with the existing perturbation series which is computed for massless quarks up to third order in the strong coupling constant α_s. A study of the perturbation seri

F. Csikor

Recent results of four-dimensional (4d) lattice simulations on the finite temperature electroweak phase transition (EWPT) are discussed. The phase transition is of first order in the SU(2)-Higgs model below the end point Higgs mass 66.5$\pm$1.4 GeV. For larger masses a rapid cross-over appears. This result completely agrees with the results of the dimensiona

R. Baier, M. Dirks, K. Redlich

Within the Closed Time Path Formalism of Thermal Field Theory we calculate the hard photon emission rate as well as the collisional energy-loss rate for a quark-gluon plasma away from chemical equilibrium. Mass singularities are shown to be dynamically screened within HTL-resummed perturbation theory also away from equilibrium. Additional (pinch) singulariti

Deirdre Black, Amir H. Fariborz, Joseph Schechter

We study pi eta scattering in a model which starts from the tree diagrams of a non-linear chiral Lagrangian including appropriate resonances. Previously, models of this type were applied to pi pi and pi K scattering and were seen to require the existence of light scalar sigma(560) and kappa(900) mesons and to be consistent with the f0(980). The present calcu

Joseph D. Lykken, Konstantin T. Matchev

We present a more detailed account of our study (hep-ph/9903238) for the supersymmetry reach of the Tevatron in channels with isolated leptons and identified tau jets. We review the theoretical motivations for expecting such signatures, and describe the relevant parameter space in the minimal supergravity and the minimal gauge-mediated models. With explicit

Haibo LI

Based on 7.8 million J/ψevents collected at BEPC, the events for J/ψ\to p\bar{p}π^0 and p\bar{p}ηhave been selected and reconstructed. Clear peaks are observed around 1480 MeV in pπ^0 (\bar{p}π^0) invariant mass spectrum and near the threshold for $η$ production in pη(\bar{p}η) invariant mass spectrum. A partial wave analysis of J/ψ\to p\bar{p}ηdata has been

F. Cerutti

The first results on searches performed by ALEPH on the 1999 data sample are presented here. They are based on an integrated luminosity of about 54 pb$^-1$ collected at the two centre-of-mass energies of 192 and 196 GeV. Preliminary results on searches for supersymmetric particles and for the neutral Higgs bosons are shown.

The KTeV Collaboration

We present results of a search for a neutral, six-quark, dibaryon state called the \h, a state predicted to exist in several theoretical models. Observation of such a state would signal the discovery of a new form of hadronic matter. Analyzing data collected by experiment E799-II, using the KTeV detector at Fermilab, we searched for the decay $H^0 \to Λp \pi

Clifford M. Will

The completion of a network of advanced laser-interferometric gravitational-wave observatories around 2001 will make possible the study of the inspiral and coalescence of binary systems of compact objects (neutron stars and black holes), using gravitational radiation. To extract useful information from the waves, such as the masses and spins of the bodies, t

Wlodzimierz Piechocki

General relativity is unable to determine the topology of the Universe. We propose to apply quantum approach. Quantization of dynamics of a test particle is sensitive to the spacetime topology. Presented results for a particle in de Sitter spacetimes favor a finite universe.

Alexei V. Tkachenko, Thomas A. Witten

We present a minimalistic approach to simulations of force transmission through granular systems. We start from a configuration containing cohesive (tensile) contact forces and use an adaptive procedure to find the stable configuration with no tensile contact forces. The procedure works by sequentially removing and adding individual contacts between adjacent

A. Bansil, S. Kaprzyk, P. E. Mijnarends, J. Toboła

We present first principles charge- and spin-selfconsistent electronic structure computations on the Heusler-type disordered alloys Fe$_{3-x}$V$_{x}$X for three different metalloids X=(Si, Ga and Al). In these calculations we use the methodology based on the Korringa-Kohn- Rostoker formalism and the coherent-potential approximation (KKR-CPA), generalized to

D. Thirumalai, D. K. Klimov

The number of protein structures is far less than the number of sequences. By imposing simple generic features of proteins (low energy and compaction) on all possible sequences we show that the structure space is sparse compared to the sequence space. Even though the sequence space grows exponentially with N (the number of amino acids) we conjecture that the

C. -M. Nedelcu, A. K. Kolezhuk, H. -J. Mikeska

A model of two-leg spin-S ladder with two additional frustrating diagonal exchange couplings J_{D}, J_{D}&#39; is studied within the framework of the nonlinear sigma model approach. The phase diagram has a rich structure and contains 2S gapless phase boundaries which split off the boundary to the fully saturated ferromagnetic phase when J_{D} and J_{D}&#39;

G. Oshanin, J. De Coninck, M. Moreau, S. F. Burlatsky

We study dynamics of a phase boundary in a one-dimensional lattice gas, which is initially put into a non-equilibrium configuration and then is let to evolve in time by particles performing nearest-neighbor random walks constrained by hard-core interactions. Initial non-equilibrium configuration is characterized by an $S$-shape density profile, such that par

T. E. Huber, M. J. Graf

The resistance R of a high density network of 6 nm diameter Bi wires in porous Vycor glass is studied in order to observe its expected semiconductor behavior. R increases from 300 K down to 0.3 K. Below 4 K, where R varies approximately as ln(1/T), the order-of-magnitude of the resistance rise, as well as the behavior of the magnetoresistance are consistent

Brandon Carter, Reinhard Prix, David Langlois

We carry out a systematic analytic investigation of stationary and cylindrically symmetric vortex configurations for simple models representing an incompressible non-relativistic superconductor in a rigidly rotating background. It is shown that although the magnetic and kinetic contributions to the energy per unit length of such a vortex are separately modif

J. Talbot, G. Tarjus, P. Viot

We investigate both analytically and by numerical simulation the kinetics of a microscopic model of hard rods adsorbing on a linear substrate, a model which is relevant for compaction of granular materials. The computer simulations use an event-driven algorithm which is particularly efficient at very long times. For a small, but finite desorption rate, the s

Georg Goeppert, Hermann Grabert

We study the linear conductance of single electron devices showing Coulomb blockade phenomena. Our approach is based on a formally exact path integral representation describing electron tunneling nonperturbatively. The electromagnetic environment of the device is treated in terms of the Caldeira-Leggett model. We obtain the linear conductance from the Kubo f

C. J. van der Beek, M. Konczykowski, R. J. Drost, P. H. Kes

Using dynamic and thermodynamic magnetization measurements, we analyze the phase diagram of Bi_2Sr_2CaCu_2O_8delta single crystals containing amorphous columnar defects created by heavy-ion irradiation. Reversible magnetization experiments yield the respective magnitudes of the pinning energy and entropy contributions to the free energy of the vortex lattice

V. Senz, T. Heinzel, T. Ihn, K. Ensslin

Magnetoresistivity measurements on p-type Si/SiGe quantum wells reveal the coexistence of a metallic behavior and weak localization. Deep in the metallic regime, pronounced weak localization reduces the metallic behavior around zero magnetic field without destroying it. In the insulating phase, a positive magnetoresistivity emerges close to B=0, possibly rel

D. N. Aristov, S. V. Maleyev

The indirect RKKY interaction in a layered metal with nearly nested (almost squared) Fermi surface is evaluated analytically. The final expressions are obtained in closed form as a combination of Bessel functions. We show that the expected ``2k_F&#39;&#39; oscillations occur as the far asymptote of our expressions, where a value of the effective Fermi moment

C. Huscroft, M. Jarrell, Th. Maier, S. Moukouri

We study the pseudogaps in the spectra of the half-filled 2D Hubbard model using both finite-size and dynamical cluster approximation (DCA) quantum Monte Carlo calculations. A charge pseudogap, accompanied by non-Fermi liquid behavior in the self energy, is shown to persist in the thermodynamic limit. The DCA (finite-size) method systematically underestimate

O. Lipan

I propose a method for studying the product of bandwidths for the Harper-Hofstader model. This method requires knowledge of the moments of the midband energies. I conjectured a general formula for these moments. I computed the asymptotic representation for the product of bandwidths in the limit of a weak magnetic flux using Szego&#39;s theorem for Hankel mat

J. Greiner, D. H. Hartmann, W. Voges, Th. Boller

We describe a search for X-ray afterglows from gamma-ray bursts using the ROSAT all-sky survey (RASS) data. If the emission in the soft X-ray band is significantly less beamed than in the gamma-ray band, we expect to detect many afterglows in the RASS. We found 23 afterglow candidates, where about 4 detections are predicted. However, follow-up spectroscopy o

G. Chartas

The large magnification factors of gravitationally lensed (GL) systems allow us to investigate the properties of quasars with X-ray luminosities that are substantially lower than those of unlensed ones and also provide an independent means of estimating the contribution of faint quasars to the hard X-ray component of the cosmic X-ray background. Our spectral

A. Biviano, M. Sauvage, P. Gallais, O. Boulade

We describe the calibration, measurements and data reduction, of the dark current of the ISOCAM/LW detector. We point-out the existence of two significant drifts of the LW dark-current, one throughout the ISO mission, on a timescale of days, another within each single revolution, on a timescale of hours. We also show the existence of a dependence of the dark

F. Combes

The bulk of the molecular gas in spiral galaxies is under the form of cold H2, that does not radiate and is only suspected through tracer molecules, such as CO. All tracers are biased, and in particular H2 could be highly underestimated in low metallicity regions. Our knowledge is reviewed of the H2 content of galaxies, according to their types, environment,

H. E. Jorgensen, E. V. Kotok, I. P. Naselsky, P. D. Naselsky

We discuss some aspects of the Cosmological Gene Project started at the Special Astrophysical Observatory (Russia) in 1999. The goal of the project is to measure the anisotropy and polarization of the Cosmic Microwave Background (CMB) and investigation of atmospheric fluctuations and foreground on arcmin-scales using the radio-telescope RATAN-600. We develop

Aparna Chitre, U. C. Joshi, S. Ganesh

We report the detection of massive star formation along a bar in the peculiar starburst galaxy Mkn 439. We present optical B, R and H_alpha + [NII] emission line images as well as H band images to show that the signature of the bar becomes progressively weak at longer wavelengths. Moreover, this bar is misaligned with the main body of the galaxy. The peak H_

Reinhard Prix

We study stationary axisymmetric configurations of a star model consisting of two barotropic fluids, which are uniformly rotating at two different rotation rates. Analytic approximate solutions in the limit of slow rotation are obtained with the classical method of Chandrasekhar, which consists of an expansion of the solution in terms of the rotation rate, a

Gaspar Galaz

I present near-IR photometry of a selected sample of E+A galaxies observed in the southern hemisphere. The sample includes 50 galaxies from nearby clusters (z ~ 0.05) and distant clusters (z ~ 0.31) as well as E+A galaxies from the field (z ~ 0.15). I have also observed 13 normal early-type galaxies from the field and from clusters, to be compared with the E

Lauro Moscardini, Sabino Matarrese, Francesco Lucchin, Sabrina De Grandi

We present a theoretical model which aims at predicting the clustering properties of X-ray clusters in flux-limited surveys for different cosmological scenarios. The model uses the theoretical and empirical relations between mass, temperature and X-ray luminosity, and fully accounts for the redshift evolution of the underlying dark matter clustering and clus

A. Palacios, F. Leroy, C. Charbonnel, M. Forestini

Nucleosynthesis in evolved (RGB and AGB) low-mass stars is reviewed under the light of the reaction rates recommended in the NACRE compilation (Angulo et al. 1999). We use a parametric model of stellar nucleosynthesis to investigate the uncertainties that still exist nowadays on the nuclear data and to give a critical point of view on the resulting evolution

P. C. van der Kruit, R. de Grijs

The spatial distribution of stars in a disk of a galaxy can be described by a radial scale length and a vertical scale height. The ratio of these two scale parameters contains information on the axis ratio of the velocity ellipsoid, i.e. the ratio of the vertical to radial stellar velocity dispersions of the stars, at least at some fiducial distance from the

S. B. Popov

In this poster I briefly review several articles on astrophysics of old isolated neutron stars, which were published in 1994-99 by my co-authors and myself.

Maarten Baes, Herwig Dejonghe

Observations show that early-type galaxies contain a considerable amount of interstellar dust, most of which is believed to exist as a diffusely distributed component. We construct a four-parameter elliptical galaxy model in order to investigate the effects of such a smooth absorbing component on the projection of kinematic quantities, such as the line profi

Tohru Nagao, Takashi Murayama, Yoshiaki Taniguchi, Michitoshi Yoshida

We present an optical spectroscopic analysis of the well-known Seyfert galaxy NGC 4051. The high-ionization nuclear emission-line region (HINER) traced by [Fe X]6374 is found to be spatially extended to a radius of 3a rcseconds (150 pc) west and southwest from the nucleus; NGC 4051 is the third example which has an extended HINER. The nuclear spectrum shows

Silvano Molendi, Sabrina De Grandi

We present results from a BeppoSAX observation of the cooling flow cluster Abell 2029. The broad band spectrum (2-35 keV) of the cluster, when fitted with a model including a cooling flow component and a one temperature thermal component, yields a temperature of 8.3+/-0.2 keV and a metal abundance of 0.46+/-0.03 in solar units, for the latter. No evidence of

S. K. Saha, V. Chinnappan

The night time variation of the Fried&#39;s parameter, r$_{o}$ is measured on 28-29 March 1991, at the Cassegrain focus of 2.34 m Vainu Bappu Telescope (VBT), at Vainu Bappu Observatory (VBO), Kavalur, India, using speckle interferometer; the results are discussed.

S. K. Saha, G. Sudheendra, A. Umesh Chandra, V. Chinnappan

A new optical speckle interferometer for use at the 2.34 meter Vainu Bappu Telescope (VBT), at Vainu Bappu Observatory (VBO), Kavalur, India, has been designed and developed. Provisions have been made for observation both at the prime focus (f/3.25), as well as at the Cassegrain focus (f/13) of the said telescope. The technical details of this sensitive inst

Matthew A. Bershady, David R. Andersen

We report on aspects of an observational study to probe the mass assembly of large galaxy disks. In this contribution we focus on a new survey of integral-field H-alpha velocity-maps of nearby, face on disks. Preliminary results yield disk asymmetry amplitudes consistent with estimates based on the scatter in the local Tully-Fisher relation. We also show how

Raul Jimenez, Paolo Padoan, James Dunlop, David Bowen

We have computed the evolving ultraviolet-millimeter spectral energy distribution (SED) produced by proto-galactic starbursts at high redshift, incorporating the chemical evolution of the interstellar medium in a consistent manner. Dust extinction is calculated in a novel way, that is not based on empirical calibrations of extinction curves, but rather on th

H. Heiselberg

After a brief history of neutron stars and supernovae recent developments are discussed. Based on modern nucleon-nucleon potentials more reliable equations of state for dense nuclear matter have been constructed. Furthermore, phase transitions such as pion, kaon and hyperon condensation, superfluidity and quark matter can occur in cores of neutron stars. Spe

Adolf N. Witt

The properties of interstellar grains can now be defined by a rapidly growing wealth of observational data. We rely upon models to combine these data with unobserved properties such as the size distribution of grains, their structure and shape, and their detailed chemical composition, in a self-consistent manner. I will review the observational constraints w

Cosma Rohilla Shalizi, William A. Tozier

In the spirit of the many recent simple models of evolution inspired by statistical physics, we put forward a simple model of the evolution of such models. Like its objects of study, it is (one supposes) in principle testable and capable of making predictions, and gives qualitative insights into a hitherto mysterious process.

Ilki Kim, Guenter Mahler

We investigate a 2-spin quantum Turing architecture, in which discrete local rotations α_m of the Turing head spin alternate with quantum controlled NOT-operations. We demonstrate that a single chaotic parameter input α_m leads to a chaotic dynamics in the entire Hilbert-space.

Daniel F. Litim, Cristina Manuel

We consider a transport equation of the Boltzmann-Langevin type for non-Abelian plasmas close to equilibrium to derive the spectral functions of the underlying microscopic fluctuations from the entropy. The correlator of the stochastic source is obtained from the dissipative processes in the plasma. This approach, based on classical transport theory, exploit