November 1999 arXiv papers — page 15

E. L. Martín, C. D. Koresko, S. R. Kulkarni, B. F. Lane

We report observations obtained with the Keck adaptive optics facility of the nearby (d=9.8 pc) binary Gl~569. The system was known to be composed of a cool primary (dM2) and a very cool secondary (dM8.5) with a separation of 5" (49 Astronomical Units). We have found that Gl~569~B is itself double with a separation of only 0".101$\pm$0".002 (1 As

V. H. Chavushyan, V. O. Verkhodanov, R. Mujica, L. Carrasco

The main goal of the FIRST-APM QSO Survey (FAQS) survey is to compile the most complete sample of Bright QSOs, located in the well optically investigated area of the sky covered by the Second Byurakan Survey (SBS). We do that through the combination of both radio and optical surveys, down to the magnitude limit B<18.5. We report here the first results of our

Daniel E. Reichart, Donald Q. Lamb, Francisco J. Castander

We better determine the spectral flux distribution of the supernova candidate associated with GRB 970228 by modeling the spectral flux distribution of the host galaxy of this burst, fitting this model to measurements of the host galaxy, and using the fitted model to better subtract out the contribution of the host galaxy to measurements of the afterglow of t

Daniel E. Reichart, Francisco J. Castander, Donald Q. Lamb

We better determine the spectral flux distribution of the supernova candidate associated with GRB 970228 by modeling the spectral flux distribution of the host galaxy of this burst, fitting this model to measurements of the host galaxy, and using the fitted model to better subtract out the contribution of the host galaxy to measurements of the afterglow of t

Witold Maciejewski, Linda S. Sparke

High-resolution observations of the inner regions of barred disk galaxies have revealed many asymmetrical, small-scale central features, some of which are best described as secondary bars. Because orbital time-scales in the galaxy center are short, secondary bars are likely to be dynamically decoupled from the main kiloparsec-scale bars. Here, we show that r

Kartik Sheth, Michael W. Regan, Stuart N. Vogel, Peter J. Teuben

We present multi-wavelength (interferometer and single-dish CO J=1-0, Halpha, broadband optical and near-infrared) observations of the classic barred spiral NGC 5383. We compare the observed central gas and dust morphology to the predictions of recent hydrodynamic simulations. In the nuclear region, our observations reveal three peaks lying along a S-shaped

Witold Maciejewski

Active Galactic Nuclei (AGN) require mass accretion onto the central engine. On large galactic scales, torques from a stellar bar can efficiently remove angular momentum from gas, and cause it to move inwards along two hydrodynamical shocks on the leading edges of the bar. Inflowing gas settles on near-circular orbits around the Inner Lindblad Resonance (ILR

Caleb Scharf, Megan Donahue, G. Mark Voit, Piero Rosati

Cosmological simulations predict that a large fraction of the baryonic mass of the Universe exists as 10^5-10^7 K diffuse, X-ray emitting gas, tracing low density filament and sheet-like structures exterior to massive clusters of galaxies. If present, this gas helps reconcile the current shortfall in observed baryon counts relative to the predictions of the

G. S. Bisnovatyi-Kogan

Estimations of magnetic fields of neutron stars, observed as radio and X-ray pulsars, are discussed. It is shown, that theoretical and observational values for different types of radiopulsars are in good correspondence. Magnetic fields of X-ray pulsars are estimated from the cyclotron line energy. In the case of Her X-1 this estimation exceeds considerably t

Patrick A. Woudt, Renee C. Kraan-Korteweg, Anthony P. Fairall

(abbreviated) In the third of a series of papers on large-scale structures behind the southern Milky Way, we report here on redshifts obtained at the South African Astronomical Observatory (SAAO) in the Great Attractor region (318deg < l < 340deg, |b| <= 10deg, Woudt 1998). This region encompasses the peak in the reconstructed mass density field, associated

Dawn M. Leeber, Thomas E. Harrison, Bernard J. McNamara

Soft X-ray Transients (SXTs) are binary systems that are believed to consist of a black hole and a normal late type dwarf star which fills its Roche Lobe. We have used GRIM II on the ARC 3.5 meter telescope at Apache Point Observatory to obtain infrared photometry of GS2000+25 (QZ Vul). By modeling the SXT ellipsoidal variations with WD98, we can determine t

M. J. Coe

This paper will review the status of our observations and understanding of Be stars in X-ray binary systems. In virtually all cases the binary partner to the Be star is a neutron star. The circumstellar disk provides the accretion fuel and hence stimulates the X-ray emission, whilst the neutron star provides a valuable probe of the environment around the Be

W. Bednarek

We consider different scenarios of collisions of compact objects (clouds, massive stars, supernova shock waves, or young pulsars) with jets in active galactic nuclei. The purpose is to find out if such collisions can become plausible explanations for the gamma-ray production in blazars. We conclude that the relativistic proton beam - cloud collision scenario

A. Weiss, S. Cassisi, H. Schlattl, M. Salaris

We investigate the evolution of low-mass metal-free Population III stars. Emphasis is laid upon the question of internal and external sources for CNO-elements, which - if present in sufficient amounts in the hydrogen-burning regions - lead to a strong modification of the stars&#39; evolutionary behavior. For the production of carbon due to nuclear processes

L. Kuiper, W. Hermsen, F. Verbunt, A. Lyne

We report on the likely detection of pulsed high-energy gamma-rays from the binary millisecond pulsar PSR J0218+4232 in 100-1000 MeV data from CGRO EGRET. Imaging analysis demonstrates that the highly significant gamma-ray source 2EG J0220+4228 (~10 sigma) is for energies > 100 MeV positionally consistent with both PSR J0218+4232 and the BL Lac 3C66A. Howeve

Denis Puy

Primordial chemistry began in the recombination epoch when the adiabatic expansion caused the temperature of the radiation to fall below 4000 K. The chemistry of the early Universe involves the elements hydrogen, its isotope deuterium, helium with its isotopic forms and lithium. In this communication I will present results on the evolution of the primordial

W. Bednarek

The content of extremely high energy (EHE) photons in the highest energy cosmic rays can be investigated by analyzing showers arriving from directions where the perpendicular component of the Earth&#39;s magnetic field is high or showers arriving from the region surrounding the Sun. We perform Monte Carlo simulations of cascades initiated by photons with par

M. Almudena Prieto, Sueli M. Viegas

The ISO coronal line spectrum of the brightest Seyfert galaxies from the CfA sample is presented and modeled. ISO observations of [O IV] 25.9 $μ$, [Ne V] 14.3 $μ$, [Mg VIII] 3.02 $μ$ and [Si IX] 2.58 $μ$ lines are presented; their relationship with the soft part of the ionizing spectrum from 50 to 300 eV is investigated. Pure photoionization models reproduce

Alice K Harding, Mark S. Strickman, Carl Gwinn, P. McCulloch

We report on our analysis of a 300 ks observation of the Vela pulsar with the Rossi X-Ray Timing Explorer (RXTE). The double-peaked, pulsed emission at 2 - 30 keV, which we had previously detected during a 93 ks observation, is confirmed with much improved statistics. There is now clear evidence, both in the spectrum and the light curve, that the emission in

P. Nedialkov, T. Veltchev

An average value of the total-to-selective-extinction ratio R_V=3.8 +/- 0.4 in M31 is obtained by means of two independent methods and by use of the analytical formula of Cardelli, Clayton & Mathis (1989). This result differs from previous determinations as well from the `standard&#39; value 3.1 for the Milky Way. The derived individual extinctions for blue

S. A. Levshakov, I. I. Agafonova, W. H. Kegel

A very low primordial deuterium abundance of D/H = 1.5 10^{-5} has recently been proposed by Molaro et al. in the Lyman limit system with log(N_HI) = 18.1 cm^{-2} at z_a = 3.514 towards the quasar APM08279+5255. The D/H value was estimated through the standard Voigt fitting procedure utilizing a simple one-component model of the absorbing region. The authors

Y. Ramachers

The emphasis in this review about non-baryonic dark matter will be on experimental approaches to this fast evolving field of astroparticle physics, especially the direct detection method. The current status of experimental techniques will be reviewed and recent highlights as well as future plans will be introduced.

G. Parmentier, E. Jehin, P. Magain, C. Neuforge

We present a model of globular cluster self-enrichment. In the protogalaxy, cold and dense clouds embedded in the hot protogalactic medium are assumed to be the progenitors of galactic halo globular clusters. The massive stars of a first generation of metal-free stars, born in the central areas of the proto-globular cluster clouds, explode as Type II superno

Thierry Fouchet, Emmanuel Lellouch, Bruno Bezard, Therese Encrenaz

We present the results of the Infrared Space Observatory Short Wavelength Spectrometer (ISO-SWS) observations of Jupiter related to ammonia. We focus on two spectral regions; the first one (the 10-micron region), probes atmospheric levels between 1 and 0.2 bar, while the second one (the 5-micron window), sounds the atmosphere between 8 and 2 bars. The two sp

Thierry Fouchet, Emmanuel Lellouch

The impact of the vapor pressure difference between deuterated and nondeuterated condensing molecules in planetary atmospheres is quantitatively assessed. This difference results in a loss of deuterium in the vapor phase above the condensation level. In Titan, Uranus and Neptune, the effect on CH3D is too subtle to alter current D/H ratio determinations. In

R. X. Xu, J. F. Liu, J. L. Han, G. J. Qiao

Qiao and his collaborators recently proposed an inverse Compton Scattering (ICS) model to explain radio emission of pulsars. In this paper, we investigate the polarization properties of pulsar emission in the model. First of all, using the lower frequency approximation, we derived the analytical amplitude of inverse Compton scattered wave of a single electro

Winfried Zimdahl

We discuss two different realizations of a ``deflationary&#39;&#39; scenario of the early universe which imply a smooth transition from an initial de Sitter stage to a subsequent radiation-dominated FLRW period. Thermodynamically, this transition is a non-equilibrium process which may also be interpreted as the decay of an initial cosmic vacuum into relativi

Cheongho Han, Seong-Hong Park, Yong-Sam Lee

Detection of caustic crossings of binary-lens gravitational microlensing events is important because by detecting them one can obtain useful information both about the lens and source star. In this paper, we compute the distribution of the intervals between two successive caustic crossings, $f(t_{\rm cc})$, for Galactic bulge binary-lens events to investigat

S. Alan Stern, Daniel D. Durda

We explore the effects of collisional evolution on putative Vulcanoid ensembles in the region between 0.06 and 0.21 AU from the Sun, in order to constrain the probable population density and population structure of this region today. Dynamical studies have shown that the Vulcanoid Zone (VZ) could be populated. However, we find that the frequency and energeti

A. Ioannisian, J. W. F. Valle

We propose a four-neutrino model which can reconcile the existing data coming from underground experiments in terms of neutrino oscillations, together with the hint from the LSND experiment and a possible neutrino contribution to the hot dark matter of the Universe. It applies the idea that extra compact dimensions, probed only by gravity and possibly gauge-

Bert Schroer

It is natural to analyse the AdS$_{d+1}$-CQFT$_{d}$ correspondence in the context of the conformal- compactification and covering formalism. In this way one obtains additional inside about Rehren&#39;s rigorous algebraic holography in connection with the degree of freedom issue which in turn allows to illustrates the subtle but important differences beween t

Herbert Spohn

We study the Dirac equation with slowly varying external potentials. Using matrix-valued Wigner functions we prove that the electron follows with high precision the classical orbit and that the spin precesses according to the BMT equation with gyromagnetic ratio g=2.

C. Y. Chen

After revealing difficulties of the standard time-dependent perturbation theory in quantum mechanics mainly from the viewpoint of practical calculation, we propose a new quasi-canonical perturbation theory. In the new theory, the dynamics of physical observables, instead of that of coefficients of wave-function expansion, is formulated so that the gauge-inva

Zheng-Wei Zhou, Guang-Can Guo

Started from local universal isotropic disentanglement, a threshold inequality on reduction factors is proposed, which is necessary and sufficient for this type of disentanglement processes. Furthermore, we give the conditions realizing ideal disentanglement processes provided that some information on quantum states is known. In addition, based on fully enta

I. V. Volovich

The current proposals for the realization of quantum computer such as NMR, quantum dots and trapped ions are based on the using of an atom or an ion as one qubit. In these proposals a quantum computer consists from several atoms and the coupling between them provides the coupling between qubits necessary for a quantum gate. We discuss whether a {\it single}

A. Gersten

New Lagrangians, depending on the field strengths and the electric and magnetic sources are found, which lead to the Maxwell equations. One new feature is that the equations of motion are obtained by varying the Lagrangian with respect to both the field strengths and the sources. In this way, conserved currents can be found for the field strengths and the el

Herbert Spohn

We investigate the solutions to the Lorentz-Dirac equation and show that its solution flow has a structure identical to the one of renormalization group flows in critical phenomena. The physical solutions of the Lorentz-Dirac equation lie on the critical surface. The critical surface is repelling, i.e. any slight deviation from it is amplified and as a resul

William Pasillas-Lepine, Witold Respondek

A Goursat structure on a manifold of dimension n is a rank two distribution D such that dim D(i)=i+2, for i=0,...,n-2, where D(i) denotes the derived flag of D, which is defined by D(0)=D and D(i+1)=D(i)+[D(i),D(i)]. Goursat structures appeared first in the work of E. von Weber and E. Cartan, who have shown that on an open and dense subset they can be conver

M. V. Movshev

We define a symplectic structure on the space of non parametrized loops in $G_2$ manifold. We also develop some basics of intersection theory of Lagrangian submanifolds.

Anna Dioubina

We construct examples of groups showing that virtual solvability and the property of being virtually torsion-free are not preserved by bi-Lipschitz maps and hence by quasi-isometries.

A. N. Parshin

We study the notion of non-commumative higher dimensional local fields. A simplest example is the ring P of formal pseudo- differential operators. As an application we extend the KP hierarchy to the space $P^n$.

A. N. Parshin

In 70&#39;s there was discovered a construction how to attach to some algebraic-geometric data an infinite-dimensional subspace in the space k((z)) of the Laurent power series. The construction was successfully used in the theory of integrable systems, particularly, for the KP and KdV equations. There were also found some applications to the moduli of algebr

Siegmund Kosarew, Paul Lupascu

In this note we identify two complex structures (one is given by algebraic geometry, the other by gauge theory) on the set of isomorphism classes of holomorphic bundles with section on a given compact complex manifold. In the case of line bundles, these complex spaces are shown to be isomorphic to a space of effective divisors on the manifold.

Corrado Marastoni, Toshiyuki Tanisaki

In this paper we deal with Radon transforms for generalized flag manifolds in the framework of quasi-equivariant D-modules. We shall follow the method employed by Baston-Eastwood and analyze the Radon transform using the Bernstein-Gelfand-Gelfand resolution and the Borel-Weil-Bott theorem. We shall determine the transform completely on the level of the Groth

Teresa Krick, Luis Miguel Pardo, Martin Sombra

We present sharp estimates for the degree and the height of the polynomials in the Nullstellensatz over $\Z$. The result improves previous work of Philippon, Berenstein-Yger and Krick-Pardo. We also present degree and height estimates of intrinsic type, which depend mainly on the degree and the height of the input polynomial system. As an application, we der

J. Gasser, A. Rusetsky, J. Schacher

These are the proceedings of the workshop &#34;HadAtom99&#34;, held at the Institut fuer Theoretische Physik, Universitaet Bern, October 14-15, 1999. The main topics discussed at the workshop were the physics of hadronic atoms and in this context recent results from Chiral Perturbation Theory. Included here are the program, the list of participants and a sho

Zoltan Ligeti

Theoretical predictions for B decay rates are rewritten in terms of the Upsilon meson mass instead of the b quark mass, using a modified perturbation expansion. The theoretical consistency is shown both at low and high orders. This method improves the behavior of the perturbation series for inclusive and exclusive decay rates, and the largest theoretical err

R. A. Alanakyan

We consider lepton-neutron (and lepton-antineutron) bound states and resonances which appear due to spin-spin, spin-orbital interactions,neutron polarization by muon. Our analis is also true for any system which include one charge and one neutral particle with finite size e.g. $π^0μ^{\pm}$-bound states.We consider also cylindrically symmetric bound states an

Yakov Itin

We propose a sufficient condition for a general spherical symmetric static metric to be compatible with classical tests of gravity. A 1-parametric class of such metrics are constructed. The Schwarzschild metric as well as the Yilmaz-Rosen metric are in this class. By computing the scalar curvature we show that the non-Schwarzschild metrics can be interpreted

Nikolai V. Brilliantov, Thorsten Poeschel

The velocity distribution in a homogeneously cooling granular gas has been studied in the viscoelastic regime when the restitution coefficient of colliding particles depends on the impact velocity. We show that for viscoelastic particles the simple scaling hypothesis is violated, i.e., that the time dependence of the velocity distribution does not scale with

M. R. Trunin, Yu. A. Nefyodov, H. J. Fink

Measurements of the microwave surface impedance $Z_s(T)=R_s(T)+iX_s(T)$ and of the complex conductivity $σ_s(T)$ of high-quality, high-$T_c$ single crystals of YBCO, BSCCO, TBCCO, and TBCO are analyzed. Experimental data of $Z_s(T)$ and $σ_s(T)$ are compared with calculations based on a modified two-fluid model which includes temperature-dependent quasiparti

J. Tempere, F. Brosens, L. F. Lemmens, J. T. Devreese

For a gas of N bosons interacting through a two-body Morse potential a variational bound of the free energy of a confined system is obtained. The calculation method is based on the Feynman-Kac functional projected on the symmetric representation. Within the harmonic approximation a variational estimate of the effect of the interaction range on the existence

Tulika Maitra, A. Taraphder

The gap anisotropy in Bi$_2$Sr$_2$CaCu$_2$O$_{8+δ}$ is revisited in the framework of a d-wave scenario in view of the recent angle-resolved photoemission experiment. Based on a tight-binding fit to the normal state dispersion, a detail analysis on the effects of the inclusion of the next harmonic in the d-wave has been presented. Significant effect has been

Murat Özer

We have reanalyzed the age of the universe problem under the assumption that the lower limit on the age of the globular clusters is 11Gyr, as predicted by the recent Hipparcos data. We find that the globular cluster and the expansion ages in a λ=0 universe are consistent only if the present value H_0 of the Hubble constant is \le 60kms^{-1}Mpc^{-1}. If H_0\g

Murat Özer

It is shown that in the cosmological models based on a vacuum energy decaying as a^{-2}, where a is the scale factor of the universe, the fate of the universe in regard to whether it will collapse in future or expand forever is determined not by the curvature constant k but by an effective curvature constant k_{eff}. It is argued that a closed universe with

T. Hearty, R. Neuhauser, B. Stelzer, M. Fernandez

We present the ROSAT PSPC pointed and ROSAT All-Sky Survey (RASS) observations and the results of our low and high spectral resolution optical follow-up observations of the T Tauri stars (TTS) and X-ray selected T Tauri star candidates in the region of the high galactic latitude dark cloud MBM12 (L1453-L1454, L1457, L1458). Previous observations have reveale

Soonkeon Nam

We study junctions of supersymmetric domain walls in N=1 supergravity theories in four dimensions, coupled to a chiral superfield with quartic superpotential having $Z_3$ symmetry. After deriving a BPS equation of the domain wall junction, we consider a stable hexagonal configuration of network of brane junctions, which are only approximately locally BPS. We

Y. Jack Ng, H. van Dam

Recent astrophysical observations seem to indicate that the cosmological constant is small but nonzero and positive. The old cosmological constant problem asks why it is so small; we must now ask, in addition, why it is nonzero (and is in the range found by recent observations), and why it is positive. In this essay, we try to kill these three metaphorical b

HERMES Collaboration, A. Airapetian

Spin transfer in deep-inelastic Lambda electroproduction has been studied with the HERMES detector using the 27.6 GeV polarized positron beam in the HERA storage ring. For an average fractional energy transfer <z> = 0.45, the longitudinal spin transfer from the virtual photon to the Lambda has been extracted. The spin transfer along the Lambda momentum direc

Matthew C. Kuntz, James P. Sethna

For a long time, it has been known that the power spectrum of Barkhausen noise had a power-law decay at high frequencies. Up to now, the theoretical predictions for this decay have been incorrect, or have only applied to a small set of models. In this paper, we describe a careful derivation of the power spectrum exponent in avalanche models, and in particula

Steven L. Liebling, Eric W. Hirschmann, James Isenberg

We consider solutions to the nonlinear sigma model (wave maps) with target space S^3 and base space 3+1 Minkowski space, and we find critical behavior separating singular solutions from nonsingular solutions. For families of solutions with localized spatial support a self-similar solution is found at the boundary. For other families, we find that a static so

G. I. Gomero, M. J. Reboucas, A. F. F. Teixeira

Two procedures for obtaining (extracting and constructing) the topological signature of any multiply connected Robertson-Walker (RW) universe are presented. It is shown through computer-aided simulations that both approaches give rise to the same topological signature for a multiply connected flat RW universe. The strength of these approaches is illustrated

M. Y. Choi, H. J. Kim, D. Kim, H. Hong

We study the synchronization phenomena in a system of globally coupled oscillators with time delay in the coupling. The self-consistency equations for the order parameter are derived, which depend explicitly on the amount of delay. Analysis of these equations reveals that the system in general exhibits discontinuous transitions in addition to the usual conti

A. J. Chorin, R. Kupferman, D. Levy

Optimal prediction methods compensate for a lack of resolution in the numerical solution of time-dependent differential equations through the use of prior statistical information. We present a new derivation of the basic methodology, show that field-theoretical perturbation theory provides a useful device for dealing with quasi-linear problems, and provide a

D. Levy, G. Puppo, G. Russo

We present a new third-order central scheme for approximating solutions of systems of conservation laws in one and two space dimensions. In the spirit of Godunov-type schemes,our method is based on reconstructing a piecewise-polynomial interpolant from cell-averages which is then advanced exactly in time. In the reconstruction step, we introduce a new third-

Pavel Exner, Vladimir A. Geyler

We study a two-dimensional charged particle interacting with a magnetic field, in general non-homogeneous, perpendicular to the plane, a confining potential, and a point interaction. If the latter moves adiabatically along a loop the state corresponding to an isolated eigenvalue acquires a Berry phase. We derive an expression for it and evaluate it in severa

T. Shigehara, H. Mizoguchi, T. Mishima, Taksu Cheon

We first give the solution for the local approximation of a four parameter family of generalized one-dimensional point interactions within the framework of non-relativistic model with three neighboring $δ$ functions. We also discuss the problem within relativistic (Dirac) framework and give the solution for a three parameter family. It gives a physical inter

Mayeul Arminjon

Newton&#39;s second law: &#34;force = time-derivative of momentum&#34;, may also be defined for theories of gravitation endowing space-time with a curved metric. Thus, Einstein&#39;s assumption of a geodesic motion may be rewritten in that form, and it corresponds to a velocity-dependent gravity acceleration vector g. In contrast, the investigated theory sta

D. Levy, Y. Brenier

The KdV equation can be considered as a special case of the general equation u_{t} + f(u)_{x} - δg(u_{xx})_x = 0, \qquad δ> 0, where f is non-linear and g is linear, namely $f(u)=u^2/2$ and g(v)=v. As the parameter $δ$ tends to 0, the dispersive behavior of the KdV equation has been throughly investigated . We show through numerical evidence that a completel

J. H. Lu, M. Yan, Y. C. Zhu

A basis B of a finite dimensional Hopf algebra H is said to be positive if all the structure constants of H relative to B are non-negative. A quasi-triangular structure $R\in H\otimes H$ is said to be positive with respect to B if it has non-negative coefficients in the basis $B \otimes B$ of $H\otimes H$. In our earlier work, we have classified all finite d

J. H. Lu, M. Yan, Y. C. Zhu

We show that if a finite dimensional Hopf algebra over ${\bf C}$ has a basis such that all the structure constants are non-negative, then the Hopf algebra must be given by a finite group $G$ and a factorization $G=G_+G_-$ into two subgroups. We also show that Hopf algebras in the category of finite sets with correspondences as morphisms are classified in the

J. T. Lunardi, L. A. Manzoni, B. M. Pimentel

We consider the (2+1)-dimensional gauged Thirring model in the Heisenberg picture. In this context we evaluate the vacuum polarization tensor as well as the corrected gauge boson propagator and address the issues of generation of mass and dynamics for the gauge boson (in the limits of QED$_3$ and Thirring model as a gauge theory, respectively) due to the rad

A. Losev, N. Nekrasov, S. Shatashvili

Field theory with instantons can be partially regularized by adding degrees of freedom at some scale. These extra degrees of freedom lead to the appearence of the new topological defects. These defects which we call freckles have some characteristic size depending on the scale at which the extra degrees of freedom revive. The examples of two dimensional sigm

C. Greub

I review the NLO QCD calculations of the branching ratio for B--> X_s gamma in the SM. Including the leading electromagnetic corrections, one obtaines BR(B-> X_s gamma)=(3.32 +- 0.30)*10^{-4}. Confronting theory with the newest data, an updated value for |V_{ts}| is obtained: |V_{ts}|=0.037 +- 0.007. Theoretical progress on the photon energy spectrum is also

I. Akushevich, P. Kuzhir

QED radiative effects are considered in the case of measurement of spin-density matrix elements of diffractive $ρ$-meson electroproduction. Large radiative correction for $r^5_{00}$ is found in the kinematics of collider experiments at HERA.

M. Berggren, R. Keranen, H. Nowak, A. Sopczak

The scalar top discovery potential has been studied with a full-statistics background simulation for sqrt(s) = 500 GeV and L = 500 fb-1. The simulation is based on a fast and realistic simulation of a TESLA detector. The large simulated data sample allowed the application of an Iterative Discriminant Analysis (IDA) which led to a significantly higher sensiti

M. Berggren, R. Keranen, A. Sopczak

The experimental sensitivity of the reaction e+e- -> bb -> bbA has been studied with a full-statistics background simulation for sqrt(s) = 500 GeV and L = 500 fb-1. The simulation is based on a fast and realistic simulation of a TESLA detector. For the first time this reaction has been analysed for a future linear collider and we show that a signal could be

N. Paver

We discuss the sensitivity to four-fermion contact interactions of the process of fermion-pair production at the e^+ - e^- Linear Collider (LC), with E_{CM}=0.5 TeV and longitudinally polarized electron beam. The analysis is based on polarized integrated cross sections with optimal cuts. Beam polarization and optimization are shown to have a crucial role in

T. Binoth, J. Ph. Guillet, G. Heinrich

We consider one-loop scalar and tensor integrals with an arbitrary number of external legs relevant for multi-parton processes in massless theories. We present a procedure to reduce N-point scalar functions with generic 4-dimensional external momenta to box integrals in (4-2ε) dimensions. We derive a formula valid for arbitrary N and give an explicit express

L. C. Garcia de Andrade

Obukhov spin-driven inflation in General Relativity is extended to include inflaton fields.A de Sitter phase solution is obtained and new slow-rolling conditions for the spin potential are obtained.The spin potential reduces to Obukhov result at the present epoch of the Universe where the spin density is low with comparison to the Early Universe spin densiti

V. Celebonovic

This is a short review of the physical ideas,algorithm for the calculation of the phase transition pressure and some results of a semi-classical theory of the behaviour of materials under high pressure proposed by P.Savic and R.Kasanin.It is base on the Coulomb interaction,supplemented by a microscopic selection rule and a set of experimentally founded postu

S. Koval, R. Burriel, M. G. Stachiotti, M. Castro

An ab-initio Linear Augmented Plane-Wave (LAPW) calculation of the zone-centered phonon frequencies of SnO has been performed. E$_g$ symmetry has been ascribed to the mode observed at 113 cm$^{-1}$ in Raman measurements, discarding a previous B$_{1g}$ assignement. The other phonon modes measured by Raman spectroscopy are also well reproduced. A new shell-mod

P. G. Silvestrov, Y. Imry

Coulomb blockade (CB) in a quantum dot (QD) with one anomalously broad level is considered. In this case many consecutive pronounced CB peaks correspond to occupation of one and the same broad level. Between the peaks the electron jumps from this level to one of the narrow levels and the transmission through the dot at the next resonance essentially repeats

A. J. Moreno, V. Bekeris

We measured the first and third harmonic of the complex AC susceptibility in YBCO single crystals with different oxygen content. The amplitude of the AC field was varied in presence of an external DC field both applied parallel to the c axis of the crystals. We show evidence that deoxygenation leads to a reduction of bulk pinning strength and consequently to

Tomoyuki Kimoto, Masato Okada

In the present paper, we analyze symmetric mixed states corresponding to the so-called concept formation on a sparsely encoded associative memory model with 0-1 neurons. Three types of mixed states, OR, AND and a majority decision mixed state are described as typical examples. Each element of the OR mixed state is composed of corresponding memory pattern ele

Seiji Miyashita, Keiji Saito, Hiroto Kobayashi

A mechanism of the parity effect in the thermally assisted resonant tunneling is proposed in the view point of nonadiabatic transitions of thermally excited states. In this mechanism, alternating enhancement of the relaxation is naturally understood as a general property of quantum relaxation of uniaxial magnets at finite temperatures where appreciable popul

Bidhan Chandra Bag, Bikash Chandra Gupta, Debshankar Ray

We consider the tunneling of a wave packet through a potential barrier which is coupled to a nonintegrable classical system and study the interplay of classical chaos and dissipation in the tunneling dynamics. We show that chaos-assisted tunneling is further enhanced by dissipation, while tunneling is suppressed by dissipation when the classical subsystem is

S. Prunet, S. K. Sethi, F. R. Bouchet

We estimate the accuracy with which various cosmological parameters can be determined from the CMB temperature and polarization data when various galactic unpolarized and polarized foregrounds are included and marginalized using the multi-frequency Wiener filtering technique. We use the specifications of the future CMB missions MAP and PLANCK for our study.

K. Jedamzik

Standard Big Bang nucleosynthesis predicts an essentially zero primordial metallicity. I speculate on possible metal (i.e. nucleon number A\geq 12) production in scenarios of inhomogeneous Big Bang nucleosynthesis. It is conceivable, though not necessarily probable, that some primordial metallicity is synthesized if a small fraction of all cosmic baryons res

R. Battiston

The modeled performance of the Alpha Magnetic Spectrometer (AMS) as a high-energy (0.3 to 100 GeV) gamma-ray detector is described, and its gamma-ray astrophysics objectives are discussed.

G. J. Qiao, R. X. Xu, J. F. Liu, B. Zhang J. L. Han

Many theoretical efforts were made to understand the core and conal emission identified from observations by Rankin (1983) and Lyne and Manchester (1988). One of them, named as inverse Compton scattering (ICS) model (Qiao & Lin 1998), has been proposed. It is found in the model that: there are central or `core&#39; emission beam, and one or two hollow conica

Sushan Konar, Dipankar Bhattacharya

The evolution of the magnetic field is investigated for isolated as well as binary neutron stars. The overall nature of the field evolution is seen to be similar for an initial crustal field and an expelled flux. The major uncertainties of the present models of field evolution and the directions in which further investigation are required are also discussed

R. E. Rothschild, D. Marsden, R. E. Lingenfelter

We measured the period and spin-down rate for SGR 1900+14 during the quiescient period two years before the recent interval of renewed burst activity. We have shown that the spin-down age of SGR 1900+14 is consistent with a braking index of ~1 which is appropriate for wind torques and not magnetic dipole radiation. We have shown that a combination of dipole

Eric L. Sandquist

For each of the three indicators used, we have conducted a thorough error analysis, and identified systematic errors in the computational procedures. For the population ratio R = N_HB / N_RGB, we find that there is no evidence of a trend with metallicity, although there appears to be real scatter in the values derived. Although this indicator is the one best

P. S. Ray, K. S. Wood, G. Fritz, P. Hertz

The USA Experiment is a new X-ray timing experiment with large collecting area and microsecond time resolution capable of conducting a broad program of studies of galactic X-ray binaries. USA is one of nine experiments aboard the Advanced Research and Global Observation Satellite which was launched February 23, 1999. USA is a collimated proportional counter

R. K. Barrett, C. A. Clarkson

We challenge the widely held belief that the cosmological principle is an obvious consequence of the observed isotropy of the cosmic microwave background radiation, combined with the Copernican principle. We perform a detailed analysis of a class of inhomogeneous perfect fluid cosmologies admitting an isotropic radiation field, with a view to assessing their

Jean Letessier, Ahmed Tounsi, Johann Rafelski

We show that in sudden hadronization of QGP a non-equilibrium value of the pion phase space occupancy parameter gamma_q>1 is expected in order to accommodate the entropy excess in QGP and the process of gluon fragmentation. When gamma_q is near to its maximum allowed value, pion overabundance is shown to arise at low $m_\bot$, where the charged pion asymmetr

Paul B. Slater

In previous studies, we have explored the ansatz that the volume elements of the Bures metrics over quantum systems might serve as prior distributions, in analogy to the (classical) Bayesian role of the volume elements ("Jeffreys' priors") of Fisher information metrics. Continuing this work, we obtain exact Bures probabilities that the members of certain low

T. Binoth, J. Ph. Guillet, E. Pilon, M. Werlen

We discuss the production of photon pairs in hadronic collisions, from fixed target to LHC energies. The study which follows is based on a QCD calculation at full next-to-leading order accuracy, including single and double fragmentation contributions, and implemented in the form of a general purpose computer program of &#34;partonic event generator&#34; type

Joanne E. McCarthy, Jonathan A. Duffy, Carsten Detlefs, Malcolm J. Cooper

The spin contribution to the magnetic moment in SmMn2Ge2 has been measured by magnetic Compton scattering in both the low and high temperature ferromagnetic phases. At low temperature, the Sm site is shown to possess a large 4f spin moment of 3.4 +/- 0.1 Bohr magnetons, aligned antiparallel to the total magnetic moment. At high temperature, the data show con