August 2002 arXiv papers — page 3

H. Nikolic

We study the de Broglie-Bohm interpretation of bosonic relativistic quantum mechanics and argue that the negative densities and superluminal velocities that appear in this interpretation do not lead to inconsistencies. After that, we study particle trajectories in bosonic quantum field theory. A new continuously changing hidden variable - the effectivity of

Thierry Mora, Clifford M. Will

We make a comparison between results from numerically generated, quasi-equilibrium configurations of compact binary systems of black holes in close orbits, and results from the post-Newtonian approximation. The post-Newtonian results are accurate through third PN order (O(v/c)^6 beyond Newtonian gravity), and include rotational and spin-orbit effects, but ar

Cecilia Scannapieco, Patricia B. Tissera

We study the effects of mergers on the structural properties of disc-like systems by using Smooth Particle Hydrodynamical (SPH) numerical simulations in hierarchical clustering scenarios. In order to assess the effects of mergers on the mass distributions we performed a bulge-disc decomposition of the projected surface density of the systems at different sta

Joaquin Sanchez-Guillen

Skyrme theory on S^2 (Faddeev coset proposal), is analyzed with a generalization of 0-curvature integrability, based on gauge techniques. New expressions valid for models in the sphere are given. The relation of the minimum energy configurations to gauge vacua is clarified. Consequences of adding a potential term to break the SO(3) symmetry are discussed.

P. West

We argue that the higher space-time derivative terms that occur in closed bosonic string field theory are reminiscent of those found in the Landau theory of liquid-crystal transitions. We examine the lowest level approximation of the closed bosonic string and find evidence for the existence of a new vacuum that spontaneously breaks Lorentz and translation sy

Gabor Fath

Antiferromagnetic Heisenberg spin chains in a sufficiently strong magnetic field are Luttinger liquids, whose parameters depend on the actual magnetization of the chain. Here we present precise numerical estimates of the Luttinger liquid dressed charge $Z$, which determines the critical exponents, by calculating the magnetization and quadrupole operator prof

Marco Lombardi

Smoothing is omnipresent in astronomy, because almost always measurements performed at discrete positions in the sky need to be interpolated into a smooth map for subsequent analysis. Still, the statistical properties of different interpolation techniques are very poorly known. In this paper, we consider the general problem of interpolating discrete data who

Rouzbeh Allahverdi, Anupam Mazumdar

We present a model with minimal assumptions for non-thermal leptogenesis with almost degenerate superheavy right-handed neutrinos in a supersymmetric set up. In this scenario a gauge singlet inflaton is directly coupled to the right-handed (s)neutrinos with a mass heavier than the inflaton mass. This helps avoiding potential problems which can naturally aris

I. A. Dynnikov, S. P. Novikov

A non-traditional approach to the discretization of differential-geometrical connections was suggested by the authors in 1997. At the same time we started studying first order difference ``black and white triangle operators (equations)'' on triangulated surfaces with a black and white coloring or triangles. In this work, we develop the theory of thes

K. B. Blyuss, T. J. Bridges, G. Derks

The stability properties of line solitary wave solutions of the (2+1)-dimensional Boussinesq equation with respect to transverse perturbations and their consequences are considered. A geometric condition arising from a multi-symplectic formulation of this equation gives an explicit relation between the parameters for transverse instability when the transvers

Ralf Hofmann

Explaining cosmic inflation by the effective dynamics of an $SU(N_C)$ pure gauge theory of scale $\La\sim 10^{-6} M_p$ is lacking an explanation of the (Gaussian) spatial curvature perturbations needed to seed the formation of large-scale structure after inflation. In this work it is demonstrated how fundamentally charged fermions of mass $m_F\sim 10^{-12} \

P. P. Avelino, L. M. G. Beca, J. P. M. de Carvalho, C. J. A. P. Martins

We discuss the issue of toy model building for the dark energy component of the universe. Specifically, we consider two generic toy models recently proposed as alternatives to quintessence models, known as Cardassian expansion and the Chaplygin gas. We show that the former is enteriely equivalent to a class of quintessence models. We determine the observatio

Tuval Foguel, Michael K. Kinyon, J. D. Phillips

In the spirit of Glauberman's fundamental work in B-loops and Moufang loops, we prove Cauchy and strong Lagrange theorems for Bol loops of odd order. We also establish necessary conditions for the existence of a simple Bol loop of odd order, conditions which should be useful in the development of a Feit-Thompson theorem for Bol loops. Bol loops are close

Volkhard F. Müller

In this article a self-contained exposition of proving perturbative renormalizability of a quantum field theory based on an adaption of Wilson's differential renormalization group equation to perturbation theory is given. The topics treated include the spontaneously broken SU(2) Yang-Mills theory. Although mainly a coherent but selective review, the arti

D. N. Voskresensky, M. Yasuhira, T. Tatsumi

Possibility of structured mixed phases at first order phase transitions in neutron stars is re-examined by taking into account charge screening and surface effects. Transition from the hadron $npe$ phase to the quark phase is studied. Two possibilities, the mixed phase and two separate phases given by the double-tangent (Maxwell) construction are considered.

Antoine Letessier-Selvon

Detection of Ultra High Energy Neutrinos (UHEN), with energy above 0.l EeV (10**18 eV) is one of the most exciting challenges of high energy astrophysics and particle physics. In this article we show that the Auger Observatories, built to study ultra high energy cosmic rays, are one of the most sensitive neutrino telescopes that will be available in the next

Katherine Freese

The Cardassian universe is a proposed modification to the Friedmann Robertson Walker (FRW) equation in which the universe is flat, matter dominated, and accelerating. Here we generalize the original Cardassian proposal to include additional variants on the FRW equation. Specific examples are presented. In the ordinary FRW equation, the right hand side is a l

Sergey Fomin, Andrei Zelevinsky

This paper continues the study of cluster algebras initiated in math.RT/0104151. Its main result is the complete classification of the cluster algebras of finite type, i.e., those with finitely many clusters. This classification turns out to be identical to the Cartan-Killing classification of semisimple Lie algebras and finite root systems, which is intrigu

J. J. Longdell, M. J. Sellars

We report on the implementation of quantum state tomography for an ensemble of Eu$^{3+}$ dopant ions in a \YSO crystal. The tomography was applied to a qubit based on one of the ion's optical transitions. The qubit was manipulated using optical pulses and measurements were made by observing the optical free induction in a phase sensitive manner. Fideliti

M. Sakakibara

We define a super Nambu-Poisson algebra over a super manifold. A super Nambu bracket does not satisfy the usual skew-symmetric property, and we propose another skew-symmetric property. We show that the divergence of super Nambu-Hamiltonian vector fields leads to a generalization of the Batalin-Vilkovisky algebra.

K. Ueda, M. Naito

We demonstrate that good superconductor/insulator/normal-metal tunnel junctions can be fabricated on as-grown superconducting MgB2 thin films. The as-grown films were prepared by coevaporation at low growth temperatures of around 280deg. The insulating barrier was formed by an Mg overlayer, which is subsequently oxidized in air. The tunneling spectra for Au/

Alex Bulatov, Vadim Smelyanskiy

We apply a quantum adiabatic evolution algorithm to a combinatorial optimization problem where the cost function depends entirely on the of the number of unit bits in a n-bit string (Hamming weight). The solution of the optimization problem is encoded as a ground state of the problem Hamiltonian H_p for the z-projection of a total spin-n/2. We show that tunn

Markus Hennrich, Thomas Legero, Axel Kuhn, Gerhard Rempe

Vacuum-stimulated Raman scattering in strongly coupled atom-cavity systems allows one to generate free-running single photon pulses on demand. Most properties of the emitted photons are well defined, provided spontaneous emission processes do not contribute. Therefore, electronic excitation of the atom must not occur, which is assured for a system adiabatica

R. D. Gill, G. Weihs, A. Zeilinger, M. Zukowski

Hess and Philipp have recently claimed that proofs of Bell's theorem have overlooked the possibility of time dependence in local hidden variables, hence the theorem has not been proven true. Moreover they present what is claimed to be a local realistic model of the EPR correlations. If this is true then Bell's theorem is not just unproven, but false.

Leon Heller

We calculate the rate of decrease of the expectation value of the transverse component of spin for spin-1/2 particles in a magnetic field with a spatial gradient, to determine the conditions under which a previous classical description is valid. A density matrix treatment is required for two reasons. The first arises because the particles initially are not i

Katalin Friedl, Frederic Magniez, Miklos Santha, Pranab Sen

We construct efficient or query efficient quantum property testers for two existential group properties which have exponential query complexity both for their decision problem in the quantum and for their testing problem in the classical model of computing. These are periodicity in groups and the common coset range property of two functions having identical

Gregor Leander

Given n=p*q with p and q prim and y in Z_{p*q}^*. Shor's Algorithm computes the order r of y, i.e. y^r=1 (mod n). If r=2k is even and y^k \ne -1 (mod n) we can easily compute a non trivial factor of n: gcd(y^k-1,n). In the original paper it is shown that a randomly chosen y is usable for factoring with probabily {1/2}. In this paper we will show an effic

G. Soyler, A. Erzan

We investigate a statistical model for multidimensional epistasis. The genotype is devided into subsequences, and within each subsequence mutations which occur in a prescribed order are beneficial. The bit-string model used to represent the genotype, may be cast in the form of a ferromagnetic Ising model with a staggered field. We obtain the actual correlati

O. I. Permyakova, E. Ilisca, P. L. Chapovsky

Theoretical model of the coherent control of nuclear spin isomers by microwave radiation has been developed. Model accounts the M-degeneracy of molecular states and molecular center-of-mass motion. The model has been applied to the 13CH3F molecules. Microwave radiation excites the para state (J=11,K=1) which is mixed by the nuclear spin-spin interaction with

V. N. Soshnikov

Using previously developed method of two-dimensional Laplace transform we obtain the characteristic equations k(ω) for electromagnetic waves in low-collision fully ionized plasma of a plane geometry. We apply here a new, different from the one used in our previous paper, iteration procedure of taking into account the Coulomb collisions. The waves are collisi

P. Maris, A. Raya, C. D. Roberts, S. M. Schmidt

The gap equation is a cornerstone in understanding dynamical chiral symmetry breaking and may also provide clues to confinement. A symmetry-preserving truncation of its kernel enables proofs of important results and the development of an efficacious phenomenology. We describe a model of the kernel that yields: a momentum-dependent dressed-quark propagator in

Thomas Schaefer

We explain how an effective theory of the CFL phase can be used to study the effect of the strange quark mass on the ground state and the excitation spectrum. We also apply the effective theory to the problem of neutrino emission from a CFL quark core inside a neutron star.

S. Typel, G. Baur

The Trojan-Horse method is an indirect approach to determine the energy dependence of S-factors of astrophysically relevant two-body reactions. This is accomplished by studying closely related three-body reactions under quasi-free scattering conditions. The basic theory of the Trojan-Horse method is developed starting from a post-form distorted wave Born app

T. Hirano, K. Tsuda

We investigate the effect of early chemical freeze-out on hydrodynamic flow and HBT radii at the RHIC energy with a genuinely three dimensional hydrodynamic model. It is found that the property of early chemical freeze out reduces radial flow, elliptic flow, R_out and R_long.

Boris Krippa, Michael C. Birse, Judith A. McGovern, Niels R. Walet

Effective field theory requires all observables to be independent of the representation used for the quantum field operators. It means that off-shell properties of the interactions should not lead to any observable effects. We analyse this issue in the context of many-body approaches to nuclear matter, where it should be possible to shift the contributions o

Boris Tomasik, Urs Achim Wiedemann

We formulate a freeze-out criterion for ultra-relativistic heavy ion collisions in terms of the pion escape probability from the collision region. We find that the increase in pion phase-space density from SPS to RHIC reported at this conference has a small influence on particle freeze-out because of the small pi-pi cross-section. Our treatment takes into ac

Jian-Ye Liu, Wen-Jun Guo, Yong-Zhong Xing, Wei Zuo

The effects of the symmetry potential and the isospin dependent in-medium nucleon-nucleon (NN) cross section on the number of proton(neutron) emissions N$_p(N_n$) are studied respectively within an isospin-dependent quantum molecular dynamics (IQMD) model. The isospin dependent in-medium NN cross section is found to have a strong influence on N$_p(N_n$) but

Oleg Zaitsev

We apply the semiclassical spin coherent state method for the density of states by Pletyukhov et al. (2002) in the weak spin-orbit coupling limit and recover the modulation factor in the semiclassical trace formula found by Bolte and Keppeler (1998, 1999).

I. N. Towers, B. A. Malomed

We introduce the simplest model to describe parametric interactions in a quadratically nonlinear optical medium with the fundamental harmonic containing two components with (slightly) different carrier frequencies [which is a direct analog of wavelength-division multiplexed (WDM) models, well known in media with cubic nonlinearity]. The model takes a closed

Richard L. Hall, Wolfgang Lucha, Franz F. Schoeberl

The semirelativistic Hamiltonian H = β\sqrt{m^2 + p^2} + V(r), where V(r) is a central potential in R^3, is concave in p^2 and convex in p. This fact enables us to obtain complementary energy bounds for the discrete spectrum of H. By extending the notion of 'kinetic potential' we are able to find general energy bounds on the ground-state energy E cor

Paul Beneker, Jan Wiegerinck

We investigate which boundary points in the closed unit ball of the Bergman space of integrable holomorphic functions on the unit disc are strongly exposed. This requires study of the Bergman projection and its kernel, the annihilator of Bergman space. We show that all polynomials in the boundary of the unit ball are strongly exposed.

Victoria Gould

A subsemigroup S of a semigroup Q is a left order in Q and Q is a semigroup of left quotients of S if every element of Q can be expressed as a# b where a and b are elements of S and if, in addition, every element of S that is square cancellable lies in a subgroup of Q. Here a# denotes the inverse of a in a subgroup of Q. We say that a left order S is straigh

Jingyi Chen, Jiayu Li

We prove that for a mean curvature flow of a compact symplectic surface in a compact Kaehler-Einstein surface, the tangent cone at the first blow-up time consists of a finite union of more than two 2-planes in $R^4$ which are complex in a complex structure on $R^4$.

Anurag K. Singh

We examine some recent work of Phillip Griffith on étale covers and fibered products from the point of view of tight closure theory. While it is known that cyclic covers of Gorenstein rings with rational singularities are Cohen-Macaulay, we show this is not true in general in the absence of the Gorenstein hypothesis. Specifically, we show that the canonical

Robert O. Bauer

Using concepts of noncommutative probability we show that the Loewner's evolution equation can be viewed as providing a map from paths of measures to paths of probability measures. We show that the fixed point of the Loewner map is the convolution semigroup of the semicircle law in the chordal case, and its multiplicative analogue in the radial case. We

Siddhartha Gadgil

We show that an oriented elliptic 3-manifold admits a universally tight positive contact structure iff the corresponding group of deck transformations on $S^3$ preserves a standard contact structure pointwise. We also relate univerally tight contact structures on 3-manifolds covered by $S^3$ to the exceptional isomorphism $SO(4)=(SU(2)\times SU(2))/{\pm 1}$.

James Propp

The problem of counting tilings of a plane region using specified tiles can often be recast as the problem of counting (perfect) matchings of some subgraph of an Aztec diamond graph A_n, or more generally calculating the sum of the weights of all the matchings, where the weight of a matching is equal to the product of the (pre-assigned) weights of the consti

J. Sawollek

A graph G is called "minimalizable" if a diagram with minimal crossing number can be obtained from an arbitrary diagram of G by crossing changes. If, furthermore, the minimal diagram is unique up to crossing changes then G is called "strongly minimalizable". In this article, it is explained how minimalizability of a graph is related to its au

Nuno D. Antunes, Edmund J. Copeland, Mark Hindmarsh, Andre Lukas

We present a toy model for five-dimensional heterotic M-theory where bulk three-branes, originating in 11 dimensions from M five-branes, are modelled as kink solutions of a bulk scalar field theory. It is shown that the vacua of this defect model correspond to a class of topologically distinct M-theory compactifications. Topology change can then be analysed

Piotr Kosinski, Katarzyna Bolonek

The explicit constrtuction of states saturating uncertainty relations following from basic commutation rules of NCQM is given both in Fock space and coordinate representation

Z. Haba

We discuss a D-dimensional Euclidean scalar field interacting with a scale invariant quantized metric. We assume that the metric depends on d-dimensional coordinates where d<D. We show that the interacting quantum fields have more regular short distance behaviour than the free fields. A model of a Gaussian metric is discussed in detail. In particular, in the

Alexander I Nesterov, F. Aceves de la Cruz

Theory of pointlike magnetic monopole with an arbitrary magnetic charge is considered. It is shown that a proper description requires making use of nonunitary representations of the rotation group and the nonassociative generalization of the gauge group and fibre bundle theory.

Shi-Hao Chen

We suppose that there are both particles with negative energies described by L_{W} and particles with positive energies described by L_{F}, L_{W} and L_{F} are independent of each other before quantization, dependent on each other after quantization and symmetric, and L=L_{W} + L_{F}. From this we present a new quantization method for QED. That the energy of

H. G. Dosch, S. Narison

We summarize the different features which show that QCD spectral sum rule analyses of the scalar two- and three-point functions do not favour the $\bar uu+\bar dd$ interpretation of the broad and low mass $σ(0.6)$ and emphasize that a measurement of the $D_s$ semileptonic decays into $ππ$ can reveal in a model-independent way its eventual gluon component $σ_

S. F. King

I discuss a class of hierarchical neutrino mass models based on the see-saw mechanism with single right-handed neutrino dominance. I apply this mechanism to a string inspired SUSY Pati-Salam model and indicate how it may emerge from intersecting D-branes.

C. Parkes

The silicon systems of the Large Hadron Collider (LHC) detectors are briefly described. The complexity and diversity of the projects are illustrated by highlighting for discussion different components of the silicon systems in each experiment.

S. F. King

I review promising approaches to neutrino mass models, focussing on three neutrino patterns of neutrino masses and mixing angles, and the corresponding Majorana mass matrices. I discuss the see-saw mechanism, and show how it may be applied in a very natural way to give a neutrino mass hierarchy with large atmospheric and solar angles by assuming single right

Alexander Kovner, Urs Achim Wiedemann

We show that the inclusion of parton density effects in the perturbative small-x evolution reduces the strength of the powerlike growth of total hadronic cross sections.

Peter N. Meisinger, Travis R. Miller, Michael C. Ogilvie

A phenomenological expression for the thermodynamic potential of gluons and quarks is constructed which incorporates the features of deconfinement and chiral symmetry restoration known from lattice simulations. The thermodynamic potential is a function of the Polyakov loop and chiral condensate expectation values. The gluonic sector uses a successful model f

Michael C. Ogilvie

At finite temperature, there is an apparent conflict between Abelian projection and critical universality. For example, should the deconfinement transition of an SU(2) gauge theory projected to U(1) lie in the Z(2) universality class of the parent SU(2) theory or in the U(1) universality class? I prove that the projected theory lies in the universality class

Shailesh Chandrasekharan

The partition function of two dimensional massless staggered fermions interacting with U(N) gauge fields is rewritten in terms of loop variables in the strong coupling limit. We use this representation of the theory to devise a non-local Metropolis algorithm to calculate the chiral susceptibility. For small lattices our algorithm reproduces exact results qui

F. X. Lee, S. J. Dong, T. Draper, I. Horvath

Using the constrained-fitting method based on Bayesian priors, we extract the masses of the two lowest states of octet and decuplet baryons with both parities. The calculation is done on quenched 16^3x28 lattices of a=0.2 fm using an improved gauge action and overlap fermions, with the pion mass as low as 180 MeV. The Roper state N(1440)1/2+ is clearly obser

A. Bravar, W. Guryn, S. R. Klein, D. Milstead

The relativistic heavy ion collider (RHIC) offers many opportunities to study diffraction in pp, pA and AA collisions. Because both proton beams can be polarized, RHIC offers the unique possibility of studying polarization effects in diffraction. We will introduce diffraction at RHIC and present three compelling physics topics: hard diffraction with polarize

Brian T. Meadows

An analysis of the Dalitz plots for the decays $D^+\to K^-π^+π^+$ and $D^+\toπ^-π^+π^+$ indicates that structure with significant phase variation is required in the s-wave $K^-π^+$ and $π^-π^+$ systems in the region below 1 GeV/c$^2$ effective mass. A constant, non resonant &#34;contact&#34; term, together with a simple s-wave Breit Wigner amplitude with $M_

Hartmut Abele

Neutrons study a number of hot topics from the field of particle physics and cosmology: Recent measurements of various mixed American-British-French-German-Hungarian-Japan-Russian groups of researchers determine the strength of the weak interaction of the neutron, which gives us unique information on quark-mixing and the question of unitarity. Much to our su

D. Cinabro, CLEO Collaboration

We have studied two-photon transitions from Upsilon(3S) decays recorded by the CLEO-III detector in exclusive events with two photons and either two electrons or two muons. We obtain precision measurements of the chi_b(2P_J) masses for J=2 and J=1. The transition rates for all three spin states of the 2P triplet are measured with improved precision which lea

Claudia Moreno, Olivier Sarbach

We analyze the dynamical stability of black hole solutions in self-gravitating nonlinear electrodynamics with respect to arbitrary linear fluctuations of the metric and the electromagnetic field. In particular, we derive simple conditions on the electromagnetic Lagrangian which imply linear stability in the domain of outer communication. We show that these c

Stephen A. Fenner

We show that for a wide range of probability measures, constructive gales are interchangable with constructive supergales for defining constructive Hausdorff dimension, thus generalizing a previous independent result of Hitchcock (cs.CC/0208043) and partially answering an open question of Lutz (cs.CC/0203017).

John M. Hitchcock

Supergales, generalizations of supermartingales, have been used by Lutz (2002) to define the constructive dimensions of individual binary sequences. Here it is shown that gales, the corresponding generalizations of martingales, can be equivalently used to define constructive dimension.

S. -H. Lee, C. Broholm, W. Ratcliff, G. Gasparovic

Frustrated systems are ubiquitous and interesting because their behavior is difficult to predict. Magnetism offers extreme examples in the form of spin lattices where all interactions between spins cannot be simultaneously satisfied. Such geometrical frustration leads to macroscopic degeneracies, and offers the possibility of qualitatively new states of matt

M. Varela, D Arias, Z. Sefrioui, C. Leon

We report the effects of epitaxial strain and deoxygenation on high quality [YBa2Cu3O7-x (YBCO)_N / PrBa2Cu3O7 (PBCO)_5] (1000 A thick) superlattices, with 1 <= N <= 12 unit cells. High spatial resolution electron energy loss spectroscopy (EELS) shows that strained, fully oxygenated YBCO layers are underdoped. Irrespective of whether underdoping is induced b

Ichiro Amimori, Nikolai V. Priezjev, Robert A. Pelcovits, Gregory P. Crawford

A scattering polarizer is created by subjecting a polymer dispersed liquid crystal (PDLC) film to tensile strain. The optomechanical properties of the film are investigated by simultaneously measuring the stress-strain and polarization dependent optical transmission characteristics. The correlation between transmittances of two orthogonal polarizations and t

Peixun Luo, K. Y. Michael Wong

The dynamical and stationary properties of on-line learning from finite training sets are analysed using the cavity method. For large input dimensions, we derive equations for the macroscopic parameters, namely, the student-teacher correlation, the student-student autocorrelation and the learning force uctuation. This enables us to provide analytical solutio

Antti-Pekka Jauho

A generalized Landauer formula, derived with the methods due to Keldysh, and Baym and Kadanoff, is gaining widespread use in the modeling of transport in a large number of different mesoscopic systems. We review some of the recent developments, including transport in semiconductor superlattices, calculation of noise, and nanoelectromechanical systems.

R. G. Nazmitdinov, H. -S. Sim, H. Schomerus, I. Rotter

We present a dynamical analysis of the transport through small quantum cavities with large openings. The systematic suppression of shot noise is used to distinguish direct, deterministic from indirect, indeterministic transport processes. The analysis is based on quantum mechanical calculations of $S$ matrices and their poles for quantum billiards with conve

Andrea Marini, Rodolfo Del Sole, Angel Rubio, Giovanni Onida

We investigate the lifetime of {\it d} holes in copper within a {\it first--principle} $GW$ approximation. At the $G_0W_0$ level the lifetime of the topmost {\it d} bands are in agreement with the experimental results and are four times smaller than those obtained in the ``on--shell&#39;&#39; calculations commonly used in literature. The theoretical lifetime

T. Mart

Using the tools developed for statistical physics, we simultaneously analyze statistical properties of the Jakarta and Kuala Lumpur Stock Exchange indices. In spite of the small number of data used in the analysis, the result shows the universal behavior of complex systems previously found in the leading stock indices. We also analyze their features before a

Sriram Ramaswamy, R. Aditi Simha, John Toner

We construct the equations of motion for the coupled dynamics of order parameter and concentration for the nematic phase of driven particles on a solid surface, and show that they imply (i) giant number fluctuations, with a standard deviation proportional to the mean and (ii) long-time tails $\sim t^{-d/2}$ in the autocorrelation of the particle velocities i

J. P. Park, P. Eames, D. M. Engebretson, J. Berezovsky

Time-resolved Kerr microscopy is used to study the excitations of individual micron- scale ferromagnetic thin film elements in their remnant state. Thin (18 nm) square elements with edge dimensions between 1 and 10 $μ$m form closure domain structures with 90 degree Neel walls between domains. We identify two classes of excitations in these systems. The first

Taku Takeuchi, D. N. C. Lin

We study the radial migration of dust particles in accreting protostellar disks analogous to the primordial solar nebula. This study takes account of the two dimensional (radial and normal) structure of the disk gas, including the effects of the variation in the gas velocity as a function of distance from the midplane. It is shown that the dust component of

K. J. Inskip, P. N. Best, M. S. Longair

The ionization and kinematic properties of the emission line regions of three subsamples of 6C and 3CR radio galaxies have been compared. The degeneracy between redshift and radio power is broken, and the relative importance of radio power (P), radio size (D) and redshift (z) for the emission line region properties is determined.

K. J. Inskip, P. N. Best, H. J. A. Rottgering, S. Rawlings

The results of a spectroscopic analysis of 3CR and 6C radio galaxies at redshift z~1 are contrasted with the properties of lower redshift radio galaxies, chosen to be matched in radio luminosity to the 6C sources studied at z~1, thus enabling the P-z degeneracy to be broken. Partial rank correlations and principal component analysis have been used to determi

K. J. Inskip, P. N. Best, S. Rawlings, M. S. Longair

(abridged) The results of deep long-slit optical spectroscopy for a sample of 8 6C radio galaxies at z~1 are presented. Emission line ratios are derived for emission lines with rest-frame wavelengths of 1500 - 4500Ang, and the kinematic propertiess of the emission line gas are derived from an analysis of the 2-d structure of thee [OII]3727 Ang emission line

Marcelo A. Alvarez, Paul R. Shapiro, Hugo Martel

Adaptive SPH and N-body simulations were carried out to study the collapse and evolution of dark matter halos that result from the gravitational instability and fragmentation of cosmological pancakes. Such halos resemble those formed by hierarchical clustering in a CDM universe and serve as a convenient test-bed model for studying halo dynamics. Our halos ar

Vinay Kashyap, Jeremy Drake, Manuel Guedel, Marc Audard

We investigate the contribution of very weak flares to the coronal luminosity of low-mass active stars. We analyze EUVE/DS events data from FK Aqr, V1054 Oph, and AD Leo and conclude that in all these cases the coronal emission is dominated by flares to such an extent that in some cases the entire emission may be ascribed to flare heating. We have developed

R. Schwarz, J. Greiner, G. H. Tovmassian, S. V. Zharikov

We report the discovery of a new, bright (V = 17 mag) AM Her system as the optical counterpart of the soft ROSAT All-Sky-Survey source RX J1846.9+5538 (= 1RXS J184659.4+553834). Optical photometric and spectroscopic follow-up observations reveal a single period of 128.7 min, consistent with a high degree of spin-orbit synchronization, and a low polar field s

Massimo Stiavelli

This paper reviews our current understanding of the process of re-ionization of the Universe, focusing especially on those models where re-ionization is caused by UV radiation from massive stars. After reviewing the expected properties of stars at zero metallicity, I discuss the properties of primordial HII regions and their observability.

A. S. Evans, J. M. Mazzarella, J. A. Surace, D. B. Sanders

High-resolution CO(1-0) observations of five ultraluminous infrared galaxies (ULIGs: L_IR [8-1000um] >~ 10^12 L_sun) with double nuclei are analyzed. These sources constitute a complete subset of local ULIGs expected to be in an intermediate stage of merging and selected with projected nuclear separations of 2.0-5.4 (3-5 kpc) so they could be resolved with t

A. R. Crusius-Waetzel, H. Lesch

We present a model for the gamma-ray emission of pulsars in terms of curvature radiation by highly relativistic particles. It is shown that the injection of power-law primary particles from an outer gap and subsequent cooling by curvature radiation losses reproduces the high energy spectrum and the luminosity of pulsars. As a result a spectral break is to be

Michael Feast

Relations are given for the correction of bias when mean absolute magnitudes are derived by the method of reduced parallaxes. The bias in the case of the derivation of the absolute magnitudes of individual objects is also considered.

A. Jessner, H. Lesch, T. Kunzl

Rough estimates and upper limits on current and particle densities form the basis of most of the canonical pulsar models. Whereas the surface of the rotating neutron star is capable of supplying sufficient charges to provide a current that, given the polar cap potential, could easily fuel the observed energy loss processes, observational and theoretical cons

P. P. Papadopoulos, W. -F. Thi, S. Viti

There is now strong evidence suggesting that the 12CO J = 1-0 transition, widely used to trace H2 gas, significantly underestimates its mass in metal-poor regions. In spiral disks such regions are found in large galactocentric distances where we show that any unaccounted H2 gas phase is likely to be diffuse (~5-20 cm^-3) and warmer (T(kin) ~ 50-100 K) than t

J. Stuart B. Wyithe, Joshua N. Winn, David Rusin

We present a generalization of the concept of magnification bias for gravitationally-lensed quasars, in which the quasars are selected by flux in more than one wavelength band. To illustrate the principle, we consider the case of two-band selection, in which the fluxes in the two bands are uncorrelated, perfectly correlated, or correlated with scatter. For u

Andreas Heithausen

Using the IRAM 30m telescope two molecular structures have been detected which cover very small areas, FWHM<1&#39;. The clouds have velocities of v_lsr~5kms and linewidth of dv~0.8km/s; thus they belong most likely to the Milky Way. Applying standard conversion factors one finds that even at the upper distance limit of 2200pc the structures are low mass obje

T. Yaqoob, B. McKernan, S. B. Kraemer, M. Crenshaw

We observed the Seyfert 1 galaxy Mrk 509 simultaneously with Chandra/HETG, HST/STIS and RXTE. We measure strong absorption lines from He-like Ne and Mg, and from H-like N, O, and Ne. The lines are unresolved except for Ne Lya and Ne IX(r). The absorption-line profiles are blueshifted by ~200 km/s with respect to the systemic velocity of Mrk 509, and there is

S. Aigrain, G. Gilmore, F. Favata, S. Carpano

Stellar micro-variability poses a serious threat to the capacities of space-based planet-finding missions such as Kepler or Eddington. The solar lightcurves obtained by the VIRGO PMO6 and SPM instruments on board SoHO from 1996 to 2001 have been studied in order to follow variability changes through the activity cycle. In all datasets, active regions-induced

Michael Truss, Graham Wynn, James Murray, Andrew King

We present a model of an outburst of the soft X-ray transient A0620-003. A two-dimensional time-dependent smoothed particle hydrodynamics scheme is used to simulate the evolution of the accretion disc through a complete outburst. The scheme includes the full tidal potential of the binary and a simple treatment of the thermal-viscous disc instability. In the

Larisa A. Yakovina, Yakiv V. Pavlenko, Carlos Abia

Lithium abundances in the atmospheres of the super Li-rich C-giants WZ Cas and WX Cyg are derived by the spectral synthesis technique {\bf using} the Li I resonance line at λ670.8 nm and {\bf three subordinate} lines at λλ812.6, 610.4 and 497.2 nm. The differences between the Li abundances derived from the λ670.8 nm line and the λλ497.2, 812.6 nm lines do no

Frank C. van den Bosch

The standard picture for the formation of disk galaxies has come to face a number of problems related to angular momentum. Numerical simulations produce disks that are too small, and analytical models predict too much low angular momentum compared to observations. In addition, angular momentum distributions of proto-galaxies in numerical simulations reveal l

S. B. F. Dorch, B. Freytag

Recent numerical simulations by Freytag et al. of the outer convection envelope of the cool super-giant Betelgeuse, have shown that the fluctuations in the star&#39;s apparent luminosity may be caused by giant cell convection. These simulations bring forth the possibility of addressing another question; namely whether stars such as Betelgeuse may harbor magn