March 1999 arXiv papers — page 6

P. Valageas, R. Schaeffer, J. Silk

We present a model for the Lyman-alpha absorbers that treats all objects (from the low-density forest clouds to the dense damped systems) in a unified description. This approach is consistent with an earlier model of galaxies (luminosity function, metallicity) but also with the known description of the density field in the small-scale non-linear regime. We c

F. Bernardeau, R. Schaeffer

The question we address in this paper is the determination of the correlation properties of the dark matter halos appearing in cosmic density fields once they underwent a strongly nonlinear evolution induced by gravitational dynamics. Assuming that the high-order correlation functions of the matter field behave as products of two-body correlation functions,

K. Hurley, P. Li, M. Boer, T. Cline

We have used the ROSAT High Resolution Imager to search for quiescent X-ray counterparts to four gamma-ray bursts which were localized to small (< 10 sq. arcmin.) error boxes with the Interplanetary Network. The observations took place years after the bursts, and the effective exposure times for each target varied from ~16 - 23 ks. We have not found any X-ra

Leo Blitz, Jonathan P. Williams

We review the progress made in understanding molecular cloud formation and evolution toward star formation since the first Crete conference in 1990. It now seems clear that molecular clouds in the Galaxy at least form from compressed HI entering a spiral arm. The internal clumpy structure within clouds probably results from the magnification of inhomogeneiti

H. -G. Ludwig, B. Freytag, M. Steffen

Based on detailed 2D numerical radiation hydrodynamics (RHD) calculations of time-dependent compressible convection, we have studied the dynamics and thermal structure of the convective surface layers of solar-type stars. The RHD models provide information about the convective efficiency in the superadiabatic region at the top of convective envelopes and pre

R. Vilela Mendes

In addition to the emergent complexity of patterns that appears when many agents come in interaction, it is also useful to characterize the dynamical processes that lead to their self-organization. A set of ergodic invariants is identified for this purpose, which is computed in several examples, namely a Bernoulli network with either global or nearest-neighb

Paul H. Frampton, Andrija Rasin

In minimal theories with extra spatial dimensions at scales mu_0 much lower than the conventional GUT scale, unification can give too-large predictions for alpha_3(M_Z) given alpha_1(M_Z) and alpha_2(M_Z) as empirical input. We systematically study the effects of adding extra states above the compactification scale on running of the gauge couplings and find

Yanhui Liu, Parameswaran Gopikrishnan, Pierre Cizeau, Martin Meyer

We study the statistical properties of volatility---a measure of how much the market is likely to fluctuate. We estimate the volatility by the local average of the absolute price changes. We analyze (a) the S&P 500 stock index for the 13-year period Jan 1984 to Dec 1996 and (b) the market capitalizations of the largest 500 companies registered in the Trades

Theodore J. Allen, M. G. Olsson, Jeffrey R. Schmidt

The computation of mode sums of the types encountered in basic quantum field theoretic applications is addressed with an emphasis on their expansions into functions of distance that can be interpreted as potentials. We show how to regularize and calculate the Casimir energy for the continuum Nambu-Goto string with massive ends as well as for the discrete Isg

Dietrich Bodeker

The dynamics of soft ($|\vec{p}|\sim g^2 T$) non-Abelian gauge fields at finite temperature is non-perturbative. The effective theory for the soft scale is determined by diagrams with external momenta $p_0\lsim g^2 T$, $|\vec{p}|\sim g^2 T$ and loop momenta larger than $g^2 T$. We consider the polarization tensor beyond the hard thermal loop approximation, w

C. P. Bachas, P. Bain, M. B. Green

We derive the complete $(curvature)^2$ terms of effective D-brane actions, for arbitrary ambient geometries and world-volume embeddings, at lowest order (disk-level) in the string-loop expansion. These terms reproduce the $o(\alpha'^2)$ corrections to string scattering amplitudes, and are consistent with duality conjectures. In the particular case of the D3-

Masaaki Sakano, Kensuke Imanishi, Masahiro Tsujimoto, Katsuji Koyama

We report the ASCA results of the Great Annihilator 1E 1740.7-2942 obtained with five pointing observations in a time span of 3.5 years. The X-ray spectrum for each period is well fitted with a single power-law absorbed by a high column of gas. The X-ray flux changes by a factor of 2 from period to period, but the other spectral parameters show no significan

Thomas G. Rizzo

Arkani-Hamed, Dimopoulos and Dvali have recently suggested that gravity may become strong at energies near 1 TeV which would remove the hierarchy problem. Such a scenario can be tested at present and future colliders since the exchange of towers of Kaluza-Klein gravitons leads to a set of new dimension-8 operators that can play important phenomenological rol

Robert de Mello Koch, Alastair Paulin-Campbell, Joao P. Rodrigues

The BPS states of N=2 super Yang-Mills theory with gauge group SU(2) are constructed as non-trivial finite-energy solutions of the worldvolume theory of a threebrane probe in F theory. The solutions preserve 1/2 of N=2 supersymmetry and provide a worldvolume realization of strings stretching from the probe to a sevenbrane. The positions of the sevenbranes co

Dan Radu Grigore

We complete our study of non-Abelian gauge theories in the framework of Epstein-Glaser approach to renormalization theory including in the model an arbitrary number of Dirac Fermions. We consider the consistency of the model up to the third order of the perturbation theory. In the second order we obtain pure group theoretical relations expressing a represent

Yu Zeng-Hui, Herbert. Pietschmann, Ma Wen-Gan, Han Liang

We studied the process $γγ\to t\bar{c}+c\bar{t}$ in a $R_{p}$ violating supersymmetric Model with the effects from both B- and L-violating interactions. The calculation shows that it is possible to detect a $R_{p}$ violating signal at the Next Linear Collider. Information about the B-violating interaction in this model could be obtained under very clean back

Asish K. Dhara, Tapan Mukhopadhyay

The coherent stochastic resonance is observed and studied with multi-step periodic signal in continuous medium having two absorbing boundaries. The general features of this process are exihibited. The universal features at the resonance point are demonstrated. The kinetic behaviors around the resonance point are also presented.

A. D. Lahiff, I. R. Afnan

A relativistic description of pion-nucleon scattering based on the four-dimensional Bethe-Salpeter equation is presented. The kernel of the equation consists of s- and u-channel nucleon and delta pole diagrams, as well as rho and sigma exchange in the t-channel. The Bethe-Salpeter equation is solved by means of a Wick rotation, and good fits are obtained to

S. Y. Choi, Eung Jin Chun, Sin Kyu Kang, Jae Sik Lee

R-parity and L violation in the MSSM would be the origin of the neutrino oscillation observed in Super-Kamiokande. A distinctive feature of this framework is that it can be tested in colliders by observing decay products of the destabilized LSP. We examine all the possible decay processes of the neutralino LSP assuming the bilinear contribution to neutrino m

Koji Takahashi, Simon F. Portegies Zwart

We investigate the evolution of globular clusters using N-body calculations and anisotropic Fokker-Planck (FP) calculations. The models include a mass spectrum, mass loss due to stellar evolution, and the tidal field of the parent galaxy. Recent N-body calculations have revealed a serious discrepancy between the results of N-body calculations and isotropic F

Alan H. Guth, Lisa Randall, Mario Serna

It has been stated in the literature that the case of maximal mixing angle for ν_e leads to no day-night effect for solar neutrinos and an energy independent flux suppression of 1/2. While the case of maximal mixing angle and Δm^2 in the MSW range does lead to suppression of the electron neutrinos reaching the earth from the sun by P_S=1/2, the situation is

K. Kajiwara, T. Masuda

A determinant expression for the rational solutions of the Painlevé III (P$_{\rm III}$) equation whose entries are the Laguerre polynomials is given. Degeneration of this determinant expression to that for the rational solutions of P$_{\rm II}$ is discussed by applying the coalescence procedure.

K. Kajiwara, T. Masuda

A generalization of determinant formulas for the classical solutions of Painlevé XXXIV and Painlevé II equations are constructed using the technique of Darboux transformation and Hirota&#39;s bilinear formalism. It is shown that the solutions admit determinant formulas even for the transcendental case.

Robert Carroll

Some observations are made about energy-time uncertainty and spin in the context of trajectories as in Faraggi-Matone or Floyd.

R. Laura

The formalism of quantum systems with diagonal singularities is applied to describe scattering processes. Well defined states are obtained for infinite time, which are related to a &#39;&#39;weak form&#39;&#39; of intrinsic irreversibility. Real and complex generalized spectral decompositions of the Liouville-Von Neumann superoperator are computed. The physi

Gil Cohen

The dynamics of soliton pulses in the Nonlinear Schrodinger Equation (NLSE) driven by an external Traveling wave is studied analytically and numerically. The Hamiltonian structure of the system is used to show that, in the adiabatic approximation for a single soliton, the problem is integrable despite the large number of degrees of freedom. Fixed points of t

J. C. A. Barata

We study the Schroedinger equation of a class of two-level systems under the action of a periodic time-dependent external field in the situation where the energy difference 2epsilon between the free energy levels is sufficiently small with respect to the strength of the external interaction. Under suitable conditions we show that this equation has a solution

G. Sardanashvily

In the case of simple graded manifolds utilized in supermechanics, supervector fields and exterior superforms are represented by global sections of smooth vector bundles.

Dino J. Lorenzini

Let $K$ be a complete discrete valuation field with ring of integers $\co_K$. Let $X/K$ be a proper smooth curve and let $A/K$ denote its jacobian. Let $P$ and $Q$ belong to $X(K)$. The divisor $P - Q$ defines a $K$-rational point of $A/K$. In this article, we study the reduction of $P - Q$ in the Néron model ${\cal A}_K/{\cal O}_K$ of $A/K$ in terms of the

J. Brian Conrey, David W. Farmer, K. Soundararajan

We evaluate the character sum sigma_m sigma_n (m/n) where the two sums are of approximately the same length. The answer is surprising.

E. Getzler

Let H be a symplectic vector space, let V be a vector space, and consider the nilpotent Lie algebra L_H(V) = H \otimes V + S^2(V) with bracket [(h_1 \otimes v_1;a_1),(h_2 \otimes v_2;a_2)] = (0,<h_1,h_2> v_1 v_2) . In this paper, we calculate the Lie algebra homology of L_H(V) as a polynomial functor of V. This has applications to the analysis of the Leray-S

Bert van Geemen

This paper gives an introduction to Kuga-Satake varieties and discusses some aspects of the Hodge conjecture related to them. Kuga-Satake varieties are abelian varieties associated to certain weight two Hodge structures, for example the second cohomology group of a K3 surface. We give a detailed account of the construction of Kuga-Satake varieties and of the

Mark S. Joshi, Antonio Sa Barreto

The problem of recovering the asymptotics of a short range perturbation of the Euclidean Laplacian on n dimensional Eudlidean space from fixed energy scattering data is studied. It is shown that for greater than or equal to three that a magnetic potential is determined, modulo Gauge invariance, by its scattering matrix at a fixed non-zero energy. This result

K. R. Goodearl, T. H. Lenagan

The ideal I generated by the 2x2 quantum minors in the algebra A = O_q(M_{m,n}(k)) (the quantized coordinate algebra of mxn matrices) is investigated. Analogues of the First and Second Fundamental Theorems of Invariant Theory are proved. In particular, it is shown that I is a completely prime ideal, that is, A/I is an integral domain, and that A/I is the rin

Y. A. Abramovich, A. K. Kitover

The characterization mentioned in the title is found.

S. Alama, L. Bronsard, T. Giorgi

We study the structure of symmetric vortices in a Ginzburg-Landau model based on S. C. Zhang&#39;s SO(5) theory of high temperature superconductivity and antiferromagnetism. We consider both a full Ginzburg-Landau theory (with Ginzburg-Landau scaling parameter kappa) and a high-kappa limiting model. In all cases we find that the usual superconducting vortice

Dmitriy S. Kalyuzhniy

We propose the new generalization of linear stationary dynamical systems with discrete time $t\in\mathbb{Z}$ to the case $t\in\nspace{Z}{N}$. The dynamics of such a system can be reproduced by means of its associated multiparametric Lax-Phillips semigroup. We define multiparametric passive, and conservative scattering systems and interpret them in terms of o

L. Chekhov

The AdS/CFT correspondence is established for the AdS_3 space compactified on a solid torus with the CFT field on the boundary. Correlation functions that correspond to the bulk theory at finite temperature are obtained in the regularization a&#39;la Gubser, Klebanov, and Polyakov. The BTZ black hole solutions in AdS_3 are T-dual to the solution in the AdS_3

M. C. Diamantini, H. Kleinert, C. A. Trugenberger

A recently proposed model of confining strings has a non-local world-sheet action induced by a space-time Kalb-Ramond tensor field. Here we show that, in the large-D approximation, an infinite set of ghost- and tachyon-free truncations of the derivative expansion of this action all lead to c=1 models. Their infrared limit describes smooth strings with world-

Volker Schomerus

In this note we explain how world-volume geometries of D-branes can be reconstructed within the microscopic framework where D-branes are described through boundary conformal field theory. We extract the (non-commutative) world-volume algebras from the operator product expansions of open string vertex operators. For branes in a flat background with constant n

Osvaldo Chandia, Ricardo Troncoso, Jorge Zanelli

The dynamical content of local AdS supergravity in five dimensions is discussed. The bosonic sector of the theory contains the vielbein ($e^{a}$), the spin connection ($ω^{ab}$) and internal SU(N) and U(1) gauge fields. The fermionic fields are complex Dirac spinors ($ψ^{i}$) in a vector representation of SU(N). All fields together form a connection 1-form i

M. Suzuki, L. Wolfenstein

From an estimate of the meson-meson inelastic scatterin at 5 GeV it is concluded that a typical strong phase in B decays to two mesons is of order of 20 degrees. For a particular final state an estimate of the phase depends on whether that state is more or less probable as a final state compared to those states to which it is connected by the strong interact

Jens Erler, Paul Langacker

Indirect precision data are used to constrain the masses of possible extra Z^prime bosons and their mixings with the ordinary Z. We study a variety of Z^prime bosons as they appear in E_6 and left-right unification models, the sequential Z boson, and the example of an additional U(1) in a concrete model from heterotic string theory. In all cases the mixings

L. Navarro, W. Porod, J. W. F. Valle

We study unconventional decays of the top-quark in the framework of SUSY models with spontaneously broken R-parity. In particular we discuss an effective theory which consists of the MSSM plus bilinearly broken R-parity. We demonstrate that the decay modes t -> stau + b and t -> tau + sbottom can have large branching ratios even in scenarios where the tau-ne

P. C. de Holanda, C. Peña-Garay, M. C. Gonzalez-Garcia, J. W. F. Valle

MSW solutions of the solar neutrino problem predict a seasonal dependence of the zenith angle distribution of the event rates, due to the non-zero latitude at the Super-Kamiokande site. We calculate this seasonal dependence and compare it with the expectations in the no-oscillation case as well as just-so scenario, in the light of the latest Super-Kamiokande

G. Raffelt

Low-mass particles such as neutrinos, axions, other Nambu-Goldstone bosons and gravitons are produced in the hot and dense interior of stars. Therefore, astrophysical arguments constrain the properties of these particles in ways which are often complementary to cosmological arguments and to laboratory experiments. This review provides an update on the most i

B. Pötter

We present a next-to-leading order calculation of jet production in gamma^*gamma collisions from e+e- scattering in a region where the virtuality Q^2 of the probing virtual photon is small compared to the transverse jet energy. The calculation is based on the phase-space slicing method. The initial state singularity of the virtual photon is factorized into t

Walter Dittrich, Holger Gies

We examine the propagation of light in the presence of various modifications of the QED vacuum in the limit of low frequency. A polarization summed and direction averaged-light cone condition is derived from the equation of motion which arises from the effective QED action. Several applications are given concerning vacuum modifications caused by, e.g., stron

Michal Brhlik, Leszek Roszkowski

We examine the effect of some uncertainties in the input astrophysical parameters on direct detection searches for WIMPs in the Galactic halo. We concentrate on the possible WIMP annual modulation signal recently reported by the DAMA Collaboration. We find that allowing for a reasonable uncertainty in a WIMP Maxwellian velocity distribution leads to signific

Leszek Roszkowski

I review axions, neutralinos, axinos, gravitinos and super-massive Wimpzillas as dark matter candidates.

Deepak Chandra, Ashok Goyal

We study the dynamics of first-order phase transition in the early Universe when it was $10-50 μs$ old with quarks and gluons condensing into hadrons. We look at how the Universe evolved through the phase transition in small as well as large super cooling scenario, specifically exploring the formation of quark nuggets and their possible survival. The nucleat

D. Rainwater

The production of a neutral, CP even Higgs via weak boson fusion and decay H -> tau tau at the LHC is studied for the Standard Model and MSSM, utilizing a parton level Monte Carlo analysis. This channel allows a 5 sigma observation of a Standard Model Higgs with an integrated luminosity of about 30 fb^-1, and provides a direct measurement of the H-tau-tau co

Daniel F. Litim

We review the use of Wilsonian renormalization group methods for quantum field theories at finite temperature. The implementations within both real and imaginary time formalism is carefully discussed. In particular, the question of gauge invariance is addressed in detail. A recently proposed real time thermal renormalization group is then used to derive the

XinChou Lou

A preliminary measurement of branching fractions of the D0 and D+ mesons into the phi meson is reported. The result is based on a data sample of 22.3 pb-1 collected at the CM energy of 4.03 GeV with the BES detector operated at the BEPC e+e- storage ring. From tagged D\bar{D} pair events the average branching fraction for a mixture of D0 and D+ is determined

Gerald C. Blazey, Brenna L. Flaugher

High energy jet distributions measured since 1992 at the Fermilab Tevatron proton--antiproton collider are presented and compared to theoretical predictions. The statistical uncertainties on these measurements are significantly reduced relative to previous results. The systematic uncertainties are comparable in size to the uncertainty in the theoretical pred

Jozef Sima, Miroslav Sukenik

The paper summarizes the background of Expensive Nondecelerative Universe model and its main consequences for gravitation. Applying the Vaidya metrics, the model allows for the localization and determination of the density and quantity of gravitational energy created by a body with the mass m in the distance r. The consequences are manifested both in a macro

Petr Hajicek

This paper is an extended version of the talk given at 19th Texas Symposium of Relativistic Astrophysics and Cosmology, Paris, 1998. It reviews of some recent work; mathematical details are skipped. It is well-known that a choice of gauge in generally covariant models has a twofold pupose: not only to render the dynamics unique, but also to define the spacet

Peter Huebner

This is the second paper in a series describing a numerical implementation of the conformal Einstein equation. This paper deals with the technical details of the numerical code used to perform numerical time evolutions from a &#34;minimal&#34; set of data. We outline the numerical construction of a complete set of data for our equations from a minimal set of

N Friedman, J. Y. Halpern

The study of belief change has been an active area in philosophy and AI. In recent years two special cases of belief change, belief revision and belief update, have been studied in detail. In a companion paper (Friedman & Halpern, 1997), we introduce a new framework to model belief change. This framework combines temporal and epistemic modalities with a noti

Wojciech Florek

Properties of the magnetic translation operators for a charged particle moving in a crystalline potential and a uniform magnetic field show that it is necessary to consider all inequivalent irreducible projective representations of the the crystal lattice translation group. These considerations lead to the concept of magnetic cells and indicate the periodici

E. A. Kotomin, R. I. Eglitis, A. V. Postnikov, G. Borstel

The ab initio linear muffin-tin-orbital (LMTO) formalism and the semi-empirical method of the Intermediate Neglect of the Differential Overlap (INDO) based on the Hartree-Fock formalism are combined for the study of the hole polarons (a hole trapped nearby the cation vacancy) in a cubic phase of KNbO3 perovskite crystals. The 40-atom and 320-atom supercells

P. Sens, S. Safran

The effect of rigid inclusions on the phase behavior of a film containing a mixture of lipid molecules is investigated. In the proposed model, the inclusion-induced deformation of the film, and the resulting energy cost are strongly dependent upon the spontaneous curvature of the mixed film. The spontaneous curvature is in turn strongly influenced by the com

Boris Fain, Joseph Rudnick

We examine the conformations of a model for a short segment of closed DNA. The molecule is represented as a cylindrically symmetric elastic rod with a constraint corresponding to a specification of the linking number. We obtain analytic expressions leading to the spatial configuration of a family of solutions representing distortions that interpolate between

Maxim Yu. Kagan, Stephan Haas, T. M. Rice

A phase diagram of the t-J three-leg ladder as a function of hole dopping is derived in the limit where the coupling parameters along the rungs, $t_{\perp}$ and $J_{\perp}$, are taken to be much larger than those along the legs, $t_{||}$ and $J_{||}$ At large exchange coupling along the rungs, $J_{\perp}/t_{\perp}> 3 / \sqrt{2}$, there is a transition from a

Amit Keren, Ophir M. Auslaender

We derive a general formalism with which it is possible to obtain the time dependence of the echo size for a spin in a stochastic field environment. Our model is based on ``strong collisions&#39;&#39;. We examine in detail three cases where: (I) the local field is Ising-like, (II) the field distribution is continuous and has a finite second moment, and (III)

V. I. Anisimov, A. E. Bedin, M. A. Korotin, G. Santoro

We present ab-initio electronic structure calculations for the Si-terminated SiC(0001)$\sqrt{3}\times\sqrt{3}$ surface. While local density approximation (LDA) calculations predict a metallic ground state with a half-filled narrow band, Coulomb effects, included by the spin-polarized LDA+U method, result in a magnetic (Mott-Hubbard) insulator with a gap of 1

R. Besseling, R. Niggebrugge, P. H. Kes

Incommensurate easy flow channels in an otherwise perfect vortex lattice are investigated. The associated (point) defects in the lattice inside the channel cause an almost vanishing critical current, as shown by molecular dynamics simulations and a comparison with the Frenkel-Kontorova model. In addition to the normal flux flow behavior we find a low mobilit

J. J. Rodríguez-Núñez, A. A. Schmidt

We examine the paper basic equations of T. Domański and K.I. Wysokiński [Phys. Rev. B {\bf 59}, 173 (1999)], who calculated the critical superconducting temperature, T_c, in function of Coulomb correlations (U) for s- and d-wave order parameter symmetries. We give physical arguments, based on general theory of perturbation, that in their gap equation the Cou

M. E. J. Newman, D. J. Watts

We study the small-world network model, which mimics the transition between regular-lattice and random-lattice behavior in social networks of increasing size. We contend that the model displays a normal continuous phase transition with a divergent correlation length as the degree of randomness tends to zero. We propose a real-space renormalization group tran

Justin Goodwin, Reggie Brown, Lutz Junge

Changes in parameters of a physical device can eventually lead to catastrophic failure. This paper discusses a parameter estimation method based on synchronization between a model and time series data. In particular, we examine the robustness of the method to additive noise in the data.

Piero Rosati, S. A. Stanford, Peter R. Eisenhardt, Richard Elston

We report the discovery of an X-ray luminous galaxy cluster at z=1.26. RXJ0848.9+4452 was selected as an X-ray cluster candidate in the ROSAT Deep Cluster Survey, on the basis of its spatial extent. Deep optical and near-IR imaging have revealed a galaxy overdensity around the peak of the X-ray emission, with a significant excess of red objects with J-K colo

Martin E. Sulkanen

Imaging of the Sunyaev-Zel&#39;dovich (SZ) effect in galaxy clusters combined with cluster plasma x-ray diagnostics can measure the cosmic distance scale to high redshift. Projecting the inverse-Compton scattering and x-ray emission along the cluster line-of-sight introduces systematic errors in the Hubble constant, H0, because the true shape of the cluster

J. S. Ulvestad, J. M. Wrobel, A. L. Roy, A. S. Wilson

The Very Long Baseline Array has been used at 15 GHz to image the milliarcsecond structure of the Seyfert galaxies Mrk 231 and Mrk 348 at two epochs separated by about 1.7 yr. Both galaxies contain parsec-scale double radio sources whose components have brightness temperatures of 10^9-10^{11} K, implying that they are generated by synchrotron emission. The n

Eric Woods, Abraham Loeb

We calculate the prompt x-ray emission as a function of viewing angle for beamed Gamma-Ray Burst (GRB) sources. Prompt x-rays are inevitable due to the less highly blueshifted photons emitted at angles greater than 1/gamma relative to the beam symmetry axis, where gamma is the expansion Lorentz factor. The observed flux depends on the combinations (gamma Del

M. Sakano, J. Yokogawa, H. Murakami, K. Koyama

We report the ASCA results of the supernova remnants (SNRs) and their candidates in the Galactic Center region. We found apparent X-ray emission from G359.1-0.5 and G0.9+0.1, and made marginal detection for G359.1+0.9, but found no significant X-ray from the other cataloged SNRs: G359.0-0.9, Sgr A East (G0.0+0.0), G0.3+0.0, Sgr D SNR (G1.0-0.1) (Green 1998).

Denis Richard, Jean-Paul Zahn

The turbulent transport of angular momentum plays an important role in many astrophysical objects, but its modelization is still far from satisfactory. We discuss here what can be learned from laboratory experiments. We analyze the results obtained by Wendt (1933) and Taylor (1936) on the classical Couette-Taylor flow, in the case where angular momentum incr

R. G. Carlberg

The gravitational clustering hierarchy and dissipative gas processes are both involved in the formation of bulges. Here we present a simple empirical model in which bulge material is assembled via gravitational accretion of the visible companion galaxies. Assuming that merging leads to a starburst, we show that the resulting winds can be strong enough that t

A. Ptak, R. Griffiths

We report on the detection of hard (2-10 keV) X-ray variability in the starburst galaxy M82 over the course of 9 ASCA observations. Long-term variability occurred on a time scale of days, with a change in flux by a factor of up to 4, corresponding to a point-source luminosity of L(2-10 keV) ~ 6e40 ergs/s. Short-term variability with an amplitude of ~ 1.4 on

Michele Bellazzini, Francesco R. Ferraro, Roberto Buonanno

A detailed study of the Star Formation History of the Sgr dSph galaxy is performed through the analysis of the data from the Sagittarius Dwarf Galaxy Survey (SDGS; Bellazzini, Ferraro & Buonanno 1999). Accurate statistical decontamination of the SDGS Color - Magnitude diagrams allow us to obtain many useful constraints on the age and metal content of the Sgr

A. W. Strong, I. V. Moskalenko

We have developed a model which aims to reproduce observational data of many kinds related to cosmic-ray origin and propagation: direct measurements of nuclei, antiprotons, electrons and positrons, gamma-rays, and synchrotron radiation. Our main results include evaluation of diffusion/convection and reacceleration models, estimates of the halo size, calculat

Etienne Parizot, Luke Drury

We calculate the light element production induced by the explosion of an isolated supernova in the ISM. We use a time-dependent model and consider energetic particles accelerated at the forward (process~1) and reverse (process~2) shocks. Both processes are primary, but are shown to underproduce Be and B. The reasons for this failure are analyzed and used to

A. Navarro, A. Serna, J. -M. Alimi

We present a method which enables exact solutions to be found for at homogeneous and isotropic scalar-tensor cosmologies with an arbitrary $ω(Φ)$ function and satisfying the general perfect fluid state equation $P=(γ-1)ρc^2$. This method has been used to analyze a wide range of asymptotic analytical solutions at early and late times for different epochs in t

Brian D. Fields, Keith A. Olive

The galactic chemical evolution of Be and B provides unique information about the origin and history of cosmic rays. The available Pop II data demonstrate that Be and B have a Galactic source, probably in one or more kinds of spallation processes. However, the data are not unequivocal about the nature of Be and B origin, as encoded in the primary or secondar

V. N. Rudenko, A. V. Gusev, V. K. Kravchuk, M. P. Vinogradov

A new approach in the gravitational wave experiment is considered. In addition to the old method of searching for coincident reactions of two separated gravitational antennae it was proposed to seek perturbations of the gravitational detector noise background correlated with astrophysical events such as neutrino and gamma ray bursts which can be relaibly reg

Mareki Honma

We investigate the possibility of lens mass determination for a caustic crossing microlensing event based on a space telescope observation. We demonstrate that the parallax due to the orbital motion of a space telescope causes a periodic fluctuation of the light curve, from which the lens distance can be derived. Since the proper motion of the lens relative

Yaw-Hwang Chen, Hai-Yang Cheng, B. Tseng, Kwei-Chou Yang

Two-body charmless nonleptonic decays of B_u and B_d mesons are studied within the framework of generalized factorization in which the effective Wilson coefficients $c^{eff}_i$ are renormalization-scale and -scheme independent while factorization is applied to the tree-level hadronic matrix elements. Contrary to previous studies, our $c_i^{eff}$ do not suffe

J. Toke, D. K. Agnihotri, W. Skulski, W. U. Schroeder

Experimental joint multiplicity distributions of neutrons and charged particles emitted in complex nuclear reactions provide an important test of theoretical models. The method is applied to test three different theoretical models of nuclear multi-fragmentation, two of which fail the test. The measurement of neutrons is decisive in distinguishing between the

Levon Pogosian, Tanmay Vachaspati

We investigate the effect of wiggly cosmic strings on the cosmic microwave background radiation anisotropy and matter power spectrum by modifying the string network model used by Albrecht et al.. We employ the wiggly equation of state for strings and the one-scale model for the cosmological evolution of certain network characteristics. For the same choice of

Konstadinos Sfetsos

We construct the most general solution in type-II string theory that represents N coincident non-extremal rotating NS5-branes and determine the relevant thermodynamic quantities. We show that in the field theory limit, it has an exact description. In particular, it can be obtained by an O(3,3) duality transformation on the exact string background for the cos

W. Vincent Liu

The coexistence of superconducting and charge-density-wave order in the half-filled attractive Hubbard model is interpreted as a consequence of the pseudospin SU(2) symmetry spontaneously broken to a `hidden&#39; subgroup U(1). By topological arguments we show that there must exist new skyrmion textures associated with this symmetry breakdown. This fact is i

J. J. Garcia-Ripoll, V. M. Perez-Garcia

We study the stability of vortex-lines in trapped dilute gases subject to rotation. We solve numerically both the Gross-Pitaevskii and the Bogoliubov equations for a 3d condensate in spherically and cilyndrically symmetric stationary traps, from small to very large nonlinearities. In the stationary case it is found that the vortex states with unit and $m=2$

William H. Kinney, Antonio Riotto

A large lepton asymmetry in the Universe is still a viable possibility and leads to many interesting phenomena such as gauge symmetry nonrestoration at high temperature. We show that a large lepton asymmetry changes the predicted cosmic microwave background (CMB) anisotropy and that any degeneracy in the relic neutrino sea will be measured to a precision of

J. Beckers, N. Debergh, F. H. Szafraniec

A recent proposal of new sets of squeezed states is seen as a particular case of a general context admitting realistic physical Hamiltonians. Such improvements reveal themselves helpful in the study of associated squeezing effects. Coherence is also considered.

J. Jersak, T. Neuhaus, H. Pfeiffer

We observe the power law scaling behavior of the monopole mass and condensate in the pure compact U(1) gauge theory with the Villain action. In the Coulomb phase the monopole mass scales with the exponent ν_m=0.49(4). In the confinement phase the behavior of the monopole condensate is described with remarkable accuracy by the exponent β_{exp}=0.197(3). Possi

ZEUS Collaboration

Charged particle production in neutral current deep inelastic scattering (DIS) has been studied using the ZEUS detector.The evolution of the mean multiplicities, scaled momenta and transverse momenta in $Q^2$ and $x$ for $ 10 < Q^2 < 5120 GeV^2$ and $x > 6\times 10^{-4}$ has been investigated in the current and target fragmentation regions of the Breit frame

Koji Harada

A self-consistent random phase approximation (RPA) is proposed as an effective Hamiltonian method in Light-Front Field Theory (LFFT). We apply the general idea to the light-front massive Schwinger model to obtain a new bound state equation and solve it numerically.

Kurt Johansson

We study a certain random groeth model in two dimensions closely related to the one-dimensional totally asymmetric exclusion process. The results show that the shape fluctuations, appropriately scaled, converges in distribution to the Tracy-Widom largest eigenvalue distribution for the Gaussian Unitary Ensemble.

A. J. Benson, S. Cole, C. S. Frenk, C. M. Baugh

We have used a combination of high resolution cosmological N-body simulations and semi-analytic modelling of galaxy formation to investigate the processes that determine the spatial distribution of galaxies in cold dark matter (CDM) models. The galaxy distribution depends sensitively on the efficiency with which galaxies form in halos of different mass. In s

Martin Castelnovo, Pierre Sens, Jean-Francois Joanny

We investigate the equilibrium charge distribution along a single annealed polyelectrolyte chain under different conditions. The coupling between the conformation of the chain and the local charge distribution is described for various solvent qualities and salt concentration. In salt free solution, we find a slight charge depletion in the central part of the

B Sriram Shastry

This work present a new class of variational wave functions for fermi systems in any dimension. These wave functions introduce correlations between Cooper pairs in different momentum states and the relevant correlations can be computed analytically. At half filling we have a ground state with critical superconducting correlations, that is argued to be exact