February 2002 arXiv papers — page 5

G. E. Volovik

The Kelvin-Helmholtz instability in superfluids is discussed, based on the first experimental observation of such instability at the interface between superfluid 3He-A and superfluid 3He-B (cond-mat/0111343). We discuss why (i) the Kelvin-Helmholtz criterion, (ii) the Landau critical velocity for nucleation of ripplons, and (iii) the free energy consideratio

Lars Andersson, Gregory J. Galloway

Motivated by recent proposals for a de Sitter version of the AdS/CFT correspondence, we give some topological restrictions on spacetimes of de Sitter type, i.e., spacetimes with $Λ>0$, which admit a regular past and/or future conformal boundary. For example we show that if $M^{n+1}$, $n \ge 2$, is a globally hyperbolic spacetime obeying suitable energy condi

S. Ando, K. Sato, T. Totani

We investigate the flux and the event rate of the supernova relic neutrino background (SRN) at the SuperKamiokande detector for various neutrino oscillation models with parameters inferred from recent experimental results. A realistic model of neutrino emission from supernova explosions and several models of the cosmic star formation history are adopted in t

Jan Louis, Andrei Micu

Compactifications of type II theories on Calabi-Yau threefolds including electric and magnetic background fluxes are discussed. We derive the bosonic part of the four-dimensional low energy effective action and show that it is a non-canonical N=2 supergravity which includes a massive two-form. The symplectic invariance of the theory is maintained as long as

Bogdan Damski, Krzysztof Sacha

We consider changes of the topological charge of vortices in quantum mechanics by investigating analytical examples where the creation or annihilation of vortices occurs. In classical hydrodynamics of non-viscous fluids the Helmholtz-Kelvin theorem ensures that the velocity field circulation is conserved. We discuss applicability of the theorem in the hydrod

Marc Timme, Fred Wolf, Theo Geisel

We present and analyze the first example of a dynamical system that naturally exhibits attracting periodic orbits that are \textit{unstable}. These unstable attractors occur in networks of pulse-coupled oscillators where they prevail for large networks and a wide range of parameters. They are enclosed by basins of attraction of other attractors but are remot

D. Zappala'

The renormalization group flow equation obtained by means of a proper time regulator is used to calculate the two loop beta function and anomalous dimension eta of the field for the O(N) symmetric scalar theory. The standard perturbative analysis of the flow equation does not yield the correct results for both beta and eta. We also show that it is still poss

R. G. Ghulghazaryan, N. S. Ananikian, P. M. A. Sloot

The Yang-Lee zeros of the Q-state Potts model on recursive lattices are studied for non-integer values of Q. Considering 1D lattice as a Bethe lattice with coordination number equal to two, the location of Yang-Lee zeros of 1D ferromagnetic and antiferromagnetic Potts models is completely analyzed in terms of neutral periodical points. Three different regime

Richard P. Sear

Mixtures of ideal polymers with hard spheres whose diameters are smaller than the radius of gyration of the polymer, exhibit extensive immiscibility. The interfacial tension between demixed phases of these mixtures is estimated, as is the barrier to nucleation. The barrier is found to scale linearly with the radius of the polymer, causing it to become large

J. Buenemann, F. Gebhard, R. Thul

We define Landau quasi-particles within the Gutzwiller variational theory, and derive their dispersion relation for general multi-band Hubbard models in the limit of large spatial dimensions D. Thereby we reproduce our previous calculations which were based on a phenomenological effective single-particle Hamiltonian. For the one-band Hubbard model we calcula

Pantelis A. Damianou, Rui L. Fernandes

We discuss the relationship between the multiple Hamiltonian structures of the generalized Toda lattices and that of the generalized Volterra lattices. We use a symmtery approach for Poisson structures that generalizes the Poisson involution theorem.

Dan Mangoubi

We consider the problem of extending a conformal metric of negative curvature, given outside a neighbourhood of 0 in the unit disk $\DD$, to a conformal metric of negative curvature in $\DD$. We give conditions under which such an extension is possible, and also give obstructions to such an extension. The methods we use are based on a maximum principle and t

Cong-Feng Qiao

The direct production of $J/ψ(ψ')$ at large transverse momentum, $p_T \gg M_{J/ψ}$, at the Fermilab Tevatron is revisited. It is found that the sea-quark initiated processes dominate in the high-$p_T$ region within the framework of color-singlet model, which is not widely realized. We think this finding is enlightening for further investigation on the ch

F. Ozon, J. -M. di Meglio, J. -F. Joanny

We have studied the adsorption of neutral polyampholytes on model charged surfaces that have been characterized by contact angle and streaming current measurements. The loop size distributions of adsorbed polymer chains have been obtained using atomic force microscopy (AFM) and compared to recent theoretical predictions. We find a qualitative agreement with

Lisa Dyson, James Lindesay, Leonard Susskind

In this paper a de Sitter Space version of Black Hole Complementarity is formulated which states that an observer in de Sitter Space describes the surrounding space as a sealed finite temperature cavity bounded by a horizon which allows no loss of information. We then discuss the implications of this for the existence of boundary correlators in the hypothesi

Chris Allton, Danielle Blythe, Jonathan Clowser

We present two unconventional methods of extracting information from hadronic 2-point functions produced by Monte Carlo simulations. The first is an extension of earlier work by Leinweber which combines a QCD Sum Rule approach with lattice data. The second uses the Maximum Entropy Method to invert the 2-point data to obtain estimates of the spectral function

B. I. Ivlev

The extremely small probability of tunneling through an almost classical potential barrier may become not small under the action of the specially adapted non-stationary signal which selects the certain particle energy E_R. For particle energies close to this value, the tunneling rate is not small during a finite interval of time and has a very sharp peak at

Robert R. Tucci

In previous papers, we expressed the Entanglement of Formation in terms of Conditional Mutual Information (CMI). In this brief paper, we express the Entanglement of Distillation in terms of CMI.

Terry Rudolph

This paper consists of musings that originate mainly from conversations with other physicists, as together we've tried to learn some cryptography, but also from conversations with a couple of classical cryptographers. The main thrust of the paper is an attempt to explore the ramifications for cryptographic security of incorporating physics into our think

Dominic Berry

In this thesis I consider the general problem of how to make the best possible phase measurements using feedback. Both the optimum input state and optimum feedback are considered for both single-mode dyne measurements and two-mode interferometric measurements. I derive the optimum input states under general dyne measurements when the mean photon number is fi

Zeng-Bing Chen, Huai-Xin Lu, Yong-De Zhang

We propose a feasible scheme for teleporting an arbitrary polarization state or entanglement of photons by requiring only single-photon (SP) sources, simple linear optical elements and SP quantum non-demolition measurements. An unknown SP polarization state can be faithfully teleported either to a duplicate polarization state or to an entangled state. Our pr

C. Greiner

Rapid chemical equilibration of antihyperons by means of the interplay between strong annihilation on baryons and the corresponding backreactions of multi-mesonic (fusion-type) processes in the later, hadronic stage of an ultrarelativistic heavy ion collision will be discussed. Explicit rate calculations for a dynamical setup are presented. At maximum SPS en

R. Rico-Martinez, K. Krischer, G. Flaetgen, J. S. Anderson

We present an example of the practical implementation of a protocol for experimental bifurcation detection based on on-line identification and feedback control ideas. The idea is to couple the experiment with an on-line computer-assisted identification/feedback protocol so that the closed-loop system will converge to the open-loop bifurcation points. We demo

J. Machta

The parallel computational complexity of the quadratic map is studied. A parallel algorithm is described that generates typical pseudotrajectories of length t in a time that scales as log t and increases slowly in the accuracy demanded of the pseudotrajectory. Long pseudotrajectories are created in parallel by putting together many short pseudotrajectories;

Zoltan Neufeld, Peter H. Haynes, Tamas Tel

We study the evolution of a localized perturbation in a chemical system with multiple homogeneous steady states, in the presence of stirring by a fluid flow. Two distinct regimes are found as the rate of stirring is varied relative to the rate of the chemical reaction. When the stirring is fast localized perturbations decay towards a spatially homogeneous st

Pierre Coullet, Lorenz Kramer

The intermittent route to spatio-temporal complexity is analyzed in a simple model which displays a subcritical bifurcation without hysteresis. A new type of spatio-temporal complexity is found, induced by fronts which "convectively clean" the perturbations around an unstable state. The mechanism which leads to the existence of these "retracting

Ashwin Vaidya, George Sparling

This paper discusses the solutions to the perturbed wave equation containing a singular potential term in the Lorentzian metric. We present the classical solution to the problem using the separation of variables method for any dimension, n. Special solutions are obtained for even n's and properties of these solutions are discussed. Finally, we also consi

Peter M. Alberti, Armin Uhlmann

On a W*-algebra M, for given two positive linear forms f,g and algebra elements a,b a variational expression for the Bures-distance d_B(f^a,g^b) between the inner derived positive linear forms f^a=f(a* . a) and g^b=g(b* . b) is obtained. Along with the proof of the formula also some earlier result of S.Gudder on non-commutative probability will be slightly e

Bernard Shiffman, Mikhail Zaidenberg

We describe a new method of constructing Kobayashi-hyperbolic surfaces in complex projective 3-space based on deforming surfaces with a "hyperbolic non-percolation" property. We use this method to show that general small deformations of certain singular abelian surfaces of degree 8 are hyperbolic. We also show that a union of 15 planes in general pos

Nik Weaver

Let H be a separable, infinite dimensional Hilbert space and let S be a countable subset of H. Then most positive operators on H have the property that every nonzero vector in the span of S is cyclic, in the sense that the set of operators in the positive part of the unit ball of B(H) with this property is comeager for the strong operator topology. Suppose κ

M. Matthias Schmitt

In this thesis we solve the coboundary equation $δc=d$ with bounds for cochains with values in a coherent subsheaf of some $\mathcal{O}^p_Ω$, where $Ω$ is a Stein manifold. In particular the existence of a finite set of global generators is not assumed. Our result applies therefore to the ideal sheaf $\mathcal{J}_V\subset \mathcal{O}_{\C^N}$ of germs of holo

David Chataur

On construit des foncteurs de formes differentielles generalisees. Ceux-ci, dans le cas d'espaces nilpotents de type fini, determinent le type d'homotopie faible des espaces. Ils sont munis, d'une maniere elementaire et naturelle, de l'action de cup-i produits. Pour les algebres commutatives a homotopit pres (algebres sur une resolution cofib

Christopher J. Leininger, Alan W. Reid

In this paper we construct explicit examples of both closed and non-compact finite volume hyperbolic manifolds which provide counterexamples to the conjecture that the co-rank of a 3-manifold group (also known as the cut number) is bounded below by one-third the first Betti number.

Zbigniew Fiedorowicz

We provide a simple explicit counterexample to a group completion conjecture for simplicial monoids attributed to JC Moore.

Michel Nguiffo Boyom

This work is devoted to an intrinsic cohomology theory of Koszul-Vinberg algebras and their modules. Our results may be regarded as improvements of the attempt by Albert Nijenhuis in [NA]. The relationships between the cohomology theory developed here and some classical problems are pointed out, e.g. extensions of algebras and modules, and deformation theory

Michel Nguiffo Boyom

The present work is devoted to compact completely solvable solvmanifolds which admit Kahlerian metrics whose Kahler forms are homogeneous. In particular, we show that such manifolds are diffeomorphic to flat tori. Our proof is based on Dynkin diagrams associated to left invariant closed 2-forms in completely solvable Lie groups. These diagrams are shown to b

Michel Nguiffo Boyom

A transitive smooth action of a connected Lie group G on a manifold M is called almost primitive (resp. primitive) if G doesn't contain any proper subgroup (resp. any proper normal subgroup) whose induced action on M is transitive as well. The aim of the present work is to investigate some combinatory properties of symplectic actions of completely solvab

Michael Levin, Wayne Lewis

We present some results related to theorems of Pasynkov and Torunczyk on the geometry of maps of finite dimensional compacta.

Kh. Saaidi, M. R. Setare

We study the phase structure of nonlocal two dimensional generalized Yang - Mills theories (nlgYM$_2$) and it is shown that all order of $ϕ^{2k}$ model of these theories has phase transition only on compact manifold with $g = 0$(on sphere), and the order of phase transition is 3. Also it is shown that the $ϕ^2 + \frac{2α}{3}ϕ^3$ model of nlgYM$_2$ has third

Donam Youm

We consider the brane universe in the bulk background of the topological AdS-Schwarzschild black holes, where the brane tension takes larger value than the fine-tunned value. The resulting universe is radiation dominated and has positive cosmological constant. We obtain the associated cosmological Cardy formula and the Cardy-Verlinde formula. We also derive

Yuri V. Kovchegov

We review recent progress in understanding QCD at high energies and the role played in it by the large Nc limit. We discuss unitarization of total hadronic cross sections and saturation of structure functions at high energies.

Alakabha Datta, Harry J. Lipkin, Patrick J. O'Donnell

We consider the weak decays of a B meson to final states that contain a S-wave radially excited vector meson. We consider vector-pseudoscalar final states and calculate ratios of the type $B \to ρ^{\prime} π/B \to ρπ$, $B \to ω^{\prime} π/B \to ωπ$ and $B \to ϕ^{\prime} π/B \to ϕπ$ where $ρ^{\prime}$, $ω^{\prime}$ and $ϕ^{\prime}$ are higher $ρ$, $ω$ and $ϕ$

B. C. Allanach, M. Battaglia, G. A. Blair, M. Carena

The ``Snowmass Points and Slopes'' (SPS) are a set of benchmark points and parameter lines in the MSSM parameter space corresponding to different scenarios in the search for Supersymmetry at present and future experiments. This set of benchmarks was agreed upon at the 2001 ``Snowmass Workshop on the Future of Particle Physics'' as a consensus

T. Tabarelli de Fatis

The pattern of oscillation parameters emerging from current experimental data can be further elucidated by the observation of matter effects. In contrast to planned experiments with conventional neutrino beams, atmospheric neutrinos offer the possibility to search for Earth-induced matter effects with very long baselines. Resonant matter effects are asymmetr

P. Poulose

We study the process e^+e^- --> W^+W^- to probe low-scale gravity at high energy linear colliders. A characteristic signature of extra-dimensions models is the forward-backward asymmetry due to the interference of spin-2 graviton and spin-1 SM gauge boson exchange terms, even when right-polarised electron beam is used. Our analysis shows that larger than 5%

A. D. Smirnov

The contributions into radiative correction parameters S, T, U from scalar leptoquark and scalar gluon doublets are investigated in the minimal four color symmetry model. It is shown that the current experimental data on S, T, U allow the scalar leptoquarks and the scalar gluons to be relatively light (with masses of order of 1 TeV or less), the lightest par

Andrea Messina

We analyse the contributions to the charge asymmetry in $K^\pm\toπ^\pm\ell^+\ell^-$ decays induced by gluino-exchange diagrams in the context of supersymmetric models with generic flavour couplings. We show that sizeable deviations with respect to the Standard Model are possible only under special circumstances. Within this scenario we set an upper limit of

Michal Praszalowicz, Andrzej Rostworowski

We formulate the nonlocal NJL model with a momentum dependent constituent quark mass and calculate pion light cone wave functions of twist 2 and 3. The leading twist wave function is not asymptotic and agrees well with the new CLEO data. Normalization conditions for the twist 3 wave functions are used to calculate the quark condensate. A prescription to calc

Wojciech Krolikowski

An effective texture is presented for six Majorana neutrinos, three active and three (conventional) sterile, based on a 6x6 mass matrix, whose 3x3 active--sterile component (i.e., Dirac component) is conjectured to get a fermion universal form similar to the constructed previously 3x3 mass matrix for charged leptons and 3x3 mass matrices for up and down quar

Zhenjun Xiao, Chong Sheng Li, Kuang-Ta Chao

we calculate the new physics contributions to seven measured decays $B \to π^+ π^-, K π$ and $ K \etap$ in the general two-Higgs-doublet model (Model III). Within the considered parameter space, we find that: (a) the CLEO/BaBar measurement of $B\to π^+ π^-$ decay prefers a small $F_0^{Bπ}(0)$: $F_0^{Bπ}(0)=0.25 \pm 0.03$; (b) the new physics enhancements to

J. van den Eshof, A. Frommer, Th. Lippert, K. Schilling

The numerical and computational aspects of the overlap formalism in lattice quantum chromodynamics are extremely demanding due to a matrix-vector product that involves the sign function of the hermitian Wilson matrix. In this paper we investigate several methods to compute the product of the matrix sign-function with a vector, in particular Lanczos based met

Fabrizio Cei

I discuss the state of the art in the search for neutrinos from galactic stellar collapses and the future perspectives of this field. The implications for the neutrino physics of a high statistics supernova neutrino burst detection by the network of detectors operating around the world are also reviewed.

O. Kortner, M. P. Locher, V. E. Markushin, P. Weber

We study pi0pi0 correlations in the exclusive reaction ppbar -> 4pi0 at rest with complete reconstruction of the kinematics for each event. The inclusive distribution shows a dip at small invariant mass of the pion pair while a small enhancement in the double differential distribution is observed for small invariant masses of both pion pairs. Dynamical model

S. V. Naydenov, V. D. Ryzhikov

The development prospects have been considered of a scintillator-photodiode type detector with improved energy resolution attaining several per cent ($R=1-2%$). The main contributions to the scintielectron detector energy resolution have been analyzed theoretically and their theoretical and physical limits determined. Experimental data have been presented on

V. D. Ivashchuk, V. N. Melnikov

Multidimensional model describing the "cosmological" and/or spherically symmetric configuration with n+1 Einstein spaces in the theory with several scalar fields and forms is considered. When electro-magnetic composite p-brane ansatz is adopted, n "internal" spaces are Ricci-flat, one space M_0 has a non-zero curvature, and all p-branes do no

Philippe Mounaix, David Langlois

Generalized Friedmann equations governing the cosmological evolution inside a thick brane embedded in a five-dimensional Anti-de Sitter spacetime are derived. These equations are written in terms of four-dimensional effective brane quantities obtained by integrating, along the fifth dimension, over the brane thickness. In the case of a Randall-Sundrum type c

E. Boehler, E. Hemaspaandra, Steffen Reith, Heribert Vollmer

A Boolean constraint satisfaction instance is a conjunction of constraint applications, where the allowed constraints are drawn from a fixed set B of Boolean functions. We consider the problem of determining whether two given constraint satisfaction instances are equivalent and prove a Dichotomy Theorem by showing that for all sets C of allowed constraints,

Xinyuan Zhao, David Vanderbilt

Crystalline structures, zone-center phonon modes, and the related dielectric response of the three low-pressure phases of HfO2 have been investigated in density-functional theory using ultrasoft pseudopotentials and a plane-wave basis. The structures of low-pressure HfO2 polymorphs are carefully studied with both the local-density approximation (LDA) and the

H. J. Im, Y. S. Kwon, M. H. Jung

We have measured the electric resistivity, magnetoresistance, magnetic susceptibility and magnetization of the new Kondo-lattice compound Ce3Pd4Ge4. The electrical resistivity exhibits a rapid drop at temperatures below 6 K, while the magnetic susceptibility does not show any corresponding anomaly at that temperature. This phenomenon is similar to that of Ce

Anjan K. Gupta, K. -W. Ng

The tunneling spectra obtained within the ab-plane of Bi$_2$Sr$_2$CaCu$_2$O$_y$ (Bi2212) for temperatures below and above the critical temperature (T$_c$) are analyzed. We find that the tunneling conductance spectra for the underdoped compound in the superconducting state do not follow the conservation of states rule. There is a consistent loss of states for

M. H. Jung, I. H. Inoue, H. Nakotte, A. H. Lacerda

The magnetic properties of perovskite CaVO3 single crystals have been studied by means of magnetoresistance r(T, H) and magnetization M(H) measurements in fields to 18T. At 2 K, the magnetoresistance is positive and a maximum value of Dr(18T)/r(0) = 16.5% is found for H//a. The magnetization exhibits a smooth increase at 2 K, reaching values of M(18T) = 0.03

A. Ossipov, Tsampikos Kottos, T. Geisel

We investigate the statistics of eigenfunction intensities ${\cal P}(|ψ|^2)$ in dynamical systems with classical chaotic diffusion. Our results contradict some recent theoretical considerations which challenge the applicability of field theoretical predictions, derived in a different framework for diffusive disordered samples. For two-dimensional systems, th

Kh. Saaidi, M. R. Setare

we study the statistical properties of inhomogenous Poisson networks. we perform a detailed analysis of the statistical properties of Poisson networks and show that the topological properties of random cellular structures, can be derived from these models of random networks. we study both two and three dimensional networks with non uniform density and show t

R. Roth, R. van Roij, D. Andrienko, K. R. Mecke

Quantitative predictions are presented of a depletion-induced torque and force acting on a single colloidal hard rod immersed in a solvent of hard spheres close to a planar hard wall. This torque and force, which are entirely of entropic origin, may play an important role for the key-lock principle, where a biological macromolecule (the key) is only function

John Singleton, Charles Mielke

We present a review of quasi-two-dimensional organic superconductors. These systems exhibit many interesting phenomena, including reduced dimensionality, strong electron-electron and electron-phonon interactions and the proximity of antiferromagnetism, insulator states and superconductivity. Moreover, it has been possible to measure the electronic bands of m

N. S. Averkiev, L. E. Golub, M. Willander

Spin relaxation is investigated theoretically in two-dimensional systems. Various semiconductor structures of both n- and p-types are studied in detail. The most important spin relaxation mechanisms are considered. The spin relaxation times are calculated taking into account the contributions to the spin--orbit interaction due to both the bulk inversion asym

F. Eurich, P. Maass, J. Baschnagel

Polymer systems in slab geometries are studied on the basis of the recently presented Gaussian Ellipsoid Model [J. Chem. Phys. 114, 7655 (2001)].The potential of the confining walls has an exponential shape. For homogeneous systems in thermodynamic equilibrium we discuss density, orientation and deformation profiles of the polymers close to the walls. For st

C. Voeltz, M. Nitschke, L. Heymann, I. Rehberg

An experimental study of the viscosity of a macroscopic suspension, i.e. a suspension for which Brownian motion can be neglected, under steady shear is presented. The suspension is prepared with a high packing fraction and is density-matched in a Newtonian carrier fluid. The viscosity of the suspension depends on the shear rate and the time of shearing. It i

A. Rosch, N. Andrei

Umklapp scattering determines the conductivity of clean metals. In typical quasi one-dimensional Fermi liquids with an open Fermi surface, certain pseudo-momenta do not decay by 2-particle collisions even in situations where Umklapp scattering relaxes the momentum of the quasi particles efficiently. Due to this approximate conservation of pseudo-momentum, a

Joachim Hermisson, Oliver Redner, Holger Wagner, Ellen Baake

We show how concepts from statistical physics, such as order parameter, thermodynamic limit, and quantum phase transition, translate into biological concepts in mutation-selection models for sequence evolution and can be used there. The article takes a biological point of view within a population genetics framework, but contains an appendix for physicists, w

Masaki Kawamura, Masato Okada

An exact solution of the transient dynamics for a sequential associative memory model is discussed through both the path-integral method and the statistical neurodynamics. Although the path-integral method has the ability to give an exact solution of the transient dynamics, only stationary properties have been discussed for the sequential associative memory.

Masaru Onoda, Naoto Nagaosa

Transport properties are studied for the flux state with the gauge flux $ϕ$ per plaquett, which may model the underdoped cuprates, with the emphasis on the particle-hole and parity/chiral symmetries.This model is reduced to the Dirac fermions in (2+1)D with a mass gap introduced by the antiferromagnetic (AF) long range order and/or the stripe formation. With

A. W. C. Lau, D. B. Lukatsky, P. Pincus, S. A. Safran

We predict a condensation phenomenon in an overall neutral system, consisting of a single charged plate and its oppositely charged counterions. Based on the ``two-fluid'' model, in which the counterions are divided into a ``free'' and a ``condensed'' fraction, we argue that for high surface charge, fluctuations can lead to a phase tra

X. S. Wu, L. Lu, D. L. Zhang, Y. Xuan

The occurrence and development of phase inhomogeneity in {\rm Bi$_2$Sr$_2$CaCu$_2$O$_{8+x}$} single crystals have been investigated by measuring their superconducting transition patterns using a high-sensitivity ac magnetometer. We find that the overdoped {\rm Bi$_2$Sr$_2$CaCu$_2$O$_{8+x}$} single crystals, even if they were single-phased immediately after a

J. Perez-Conde, A. K. Bhattacharjee

We study the electronic properties of spherical quantum dot quantum well nanocrystals within a symmetry-based tight-binding model. In particular, the influence of a concentric monolayer of HgS embedded in a spherical CdS nanocrystal of diameter 52.7 A is analyzed as a function of its distance from the center. The electron and hole states around the energy ga

A. V. Syromyatnikov, S. V. Maleyev

We give a physical picture of the low-energy sector of the spin 1/2 Heisenberg Kagome antiferromagnet (KAF). It is shown that Kagome lattice can be presented as a set of stars which are arranged in a triangular lattice and contain 12 spins. Each of these stars has two degenerate singlet ground states which can be considered in terms of pseudospin. As a resul

Tomek Plewa, Michal Rozyczka

A hydrodynamic interaction between an old supernova remnant and a massive black hole is studied with the help of a high-resolution adaptive mesh refinement code. A series of multidimensional numerical models is obtained for a fixed distance between supernova explosion site and the black hole but different densities of the ambient medium. The interaction betw

J. Baker, M. Campanelli, C. O. Lousto, R. Takahashi

With the goal of bringing theory, particularly numerical relativity, to bear on an astrophysical problem of critical interest to gravitational wave observers we introduce a model for coalescence radiation from binary black hole systems. We build our model using the "Lazarus approach", a technique that bridges far and close limit approaches with full

M. Juric, Z. Ivezic, H. R. Lupton, T. Quinn

We positionally correlate asteroids from existing catalogs with a sample of $\about$18,000 asteroids detected by the Sloan Digital Sky Survey (SDSS, Ivezić {\em et al.} 2001). We find 2641 unique matches, which represent the largest sample of asteroids with both accurate multi-color photometry and known orbital parameters. The matched objects are predominant

Dana S. Balser, Joseph P. McMullin, T. L. Wilson

Standard stellar evolution theory is inconsistent with the observed isotopic carbon ratio, 12C/13C, in evolved stars. This theory is also inconsistent with the 3He/H abundance ratios observed in Galactic HII regions, when combined with chemical evolution theory. These discrepancies have been attributed to an extra, non-standard mixing which further processes

M. Steinmetz, Julio F. Navarro

We report first results from a series of N-body/gasdynamical simulations designed to study the origin of galaxy morphologies in a cold dark matter-dominated universe. The simulations include star formation and feedback and have numerical resolution sufficiently high to allow for a direct investigation of the morphology of simulated galaxies. We find, in agre

Asantha Cooray

We discuss the second order contributions to lensing statistics resulting from the clustering of background sources from which galaxy shape measurements are made in weak lensing experiments. In addition to a previously discussed contribution to the lensing skewness, background source clustering also contributes to the two-point correlation function, such as

A. C. Quillen

Using star counts in both color and magnitude from the Two Micron All Sky Survey (2MASS) Second Incremental Release Point Source Catalog we search for evidence of non-uniform extinction and stellar population density changes in the Galactic Plane. Extinction causes the entire main sequence to shift toward redder colors on a color magnitude diagram. A local i

Alberto Franceschini, Carol Lonsdale, the SWIRE Co-Investigator Team

The SIRTF Wide-area Infrared Extragalactic (SWIRE) survey is a "Legacy Program" using 851 hours of SIRTF observing time to conduct a set of large-area (67 sq. deg. split into 7 fields) high Galactic latitude imaging surveys, achieving 5-sigma sensitivities of 0.45/2.75/17.5 mJy at 24/70/160 micron with MIPS and of 7.3/9.7/27.5/32.5 microJy at 3.6/4.5

Peter Goldreich, Re'em Sari

We investigate the hypothesis that interactions between a giant planet and the disk from which it forms promote eccentricity growth. These interactions are concentrated at discrete Lindblad and corotation resonances. Interactions at principal Lindblad resonances cause the planet's orbit to migrate and open a gap in the disk if the planet is sufficiently

I. Neill Reid, D. Kilkenny, Kelle L. Cruz

We present BVRI photometry of 180 bright, southern nearby-star candidates. The stars were selected from the New Luyten Two-Tenths proper motion catalogue based on optical/infrared colours, constructed by combining Luytens's m(r) estimates with near-infrared photometry from the 2-Micron All Sky Survey. Photometric parallaxes derived from (V-K), (V-I) and

I. Neill Reid, Kelle L. Cruz

We are currently undertaking a program aimed at identifying previously-unrecognised late-type dwarfs within 20 parsecs of the Sun. As a first step, we have cross-referenced Luyten's NLTT proper motion catalogue against the second incremental release of the 2MASS Point Source Catalogue, and use optical/infrared colours, derived by combining Luytens's

N. C. Santos, R. J. Garcia Lopez, G. Israelian, M. Mayor

We have derived beryllium abundances in a wide sample of stars hosting planets, with spectral types in the range F7V-K0V, aimed at studying in detail the effects of the presence of planets on the structure and evolution of the associated stars. Predictions from current models are compared with the derived abundances and suggestions are provided to explain th

Remo J. Ruffini

The developments of the elctromgnetic black holes physics and vacuum polarization process are presented in the interpretation of Gamma-Ray Bursts.

Remo Ruffini

The Relative Space-Time Transformation (RSTT) Paradigm and the Interpretation of the Burst Structure (IBS) Paradigm are applied to the analysis of the structure of the burst and afterglow of Gamma-Ray Bursts within the theory based on the vacuum polarization process occurring in an Electro-Magnetic Black Hole, the EMBH theory. This framework is applied to th

F. -K. Thielemann, D. Argast, F. Brachwitz, G. Martinez-Pinedo

With the exception of the Big Bang, responsible for 1,2H, 3,4He, and 7Li, stars act as sources for the composition of the interstellar medium. Cosmic rays are related to the latter and very probably due to acceleration of the mixed interstellar medium by shock waves from supernova remnants. Thus, the understanding of the abundance evolution in the interstell

A. N. Parmar, T. Oosterbroek, L. Boirin, D. Lumb

We report the discovery of narrow X-ray absorption features from the dipping low-mass X-ray binary X 1624-490 during an XMM-Newton observation in 2001 February. The features are identified with the K alpha absorption lines of Fe xxv and Fe xxvi and have energies of 6.72 +/- 0.03 keV and 7.00 +/- 0.02 keV and equivalent widths (EWs) of -7.5 +1.7 -6.3 eV and -

D. Barret, G. Skinner, E. Kendziorra, R. Staubert

The Rossi X-ray Timing Explorer has demonstrated that fast X-ray timing can be used to probe strong gravity fields around collapsed objects and constrain the equation of state of dense matter in neutron stars. These studies require extremely good photon statistics. In view of the huge collecting area of its mirrors, XEUS could make a unique contribution to t

A. C. Fabian, C. S. Crawford, K. Iwasawa

We report a Chandra observation of the z=3.395 radio galaxy B2 0902+343. The unresolved X-ray source is centred on the active nucleus. The spectrum is well fit by a flat power law of photon index of Gamma~1.1 with intrinsic absorption of 8x10^{22} cm^{-2}, and an intrinsic 2-10keV luminosity of 3.3x10^{45} erg/s. More complex models which allow for a steeper

S. S. Komissarov

This paper formulates time-dependent, force-free, degenerate electrodynamics as a hyperbolic system of conservation laws. It is shown that this system has four characteristic modes, a pair of fast waves propagating with the speed of light and a pair of Alfven waves. All these modes are linearly degenerate. The results of this analytic study can be used in de

Toru Okuda

We examine highly super-Eddington black-hole models for SS 433, based on two-dimensional hydrodynamical calculations coupled with radiation transport. The super-Eddington accretion flow with a small viscosity parameter, $α= 10^{-3}$, results in a geometrically and optically thick disk with a large opening angle of $\sim 60^{\circ}$ to the equatorial plane an

S. E. Juralevich, V. V. Tikhomirov

It is shown that primordial black holes (PBHs) of masses M > 5x10^14 g are able to absorb white dwarfs (WD) completely for the time of their existence, giving rise to formation of black holes of WD mases. The WD absorption is accompanied by up to 10^{52}erg neutrino bursts which could both considerably contribute to the cosmic neutrino flux and open up a new

Sidney van den Bergh, Roberto G. Abraham, Laura F. Whyte, Michael R. Merrifield

We investigate the visibility of galactic bars and spiral structure in the distant Universe by artificially redshifting 101 B-band CCD images of local spiral galaxies from the Ohio State University Bright Spiral Galaxy Survey. Our artificially redshifted images correspond to Hubble Space Telescope I-band observations of the local galaxy sample seen at z=0.7,

Donato Bini, Robert T. Jantzen

The historical origins of Fermi-Walker transport and Fermi coordinates and the construction of Fermi-Walker transported frames in black hole spacetimes are reviewed. For geodesics this transport reduces to parallel transport and these frames can be explicitly constructed using a Killing-Yano tensor as shown by Marck. For accelerated or geodesic circular orbi

Vikram Soni, Moninder Singh Modgil, Desdeep Sahdev

While it is commonly believed that there is a {\it direct} transition from the hadronic to a quark gluon phase at high temperature, it would be prejudicial to rule out a sequence of dynamically generated intermediate scales. Using as guide, an effective lagrangian with unconfined gluons and constituent quarks, interacting with a chiral multiplet, we examine