August 2002 arXiv papers — page 2

San Vu Ngoc

This article gives a classification, up to symplectic equivalence, of singular Lagrangian foliations given by a completely integrable system of a 4-dimensional symplectic manifold, in a full neighbourhood of a singular leaf of focus-focus (=nodal) type.

Gert Almkvist

Polynomials related to rational solutions of Painleve' equations satisfy certain difference equations. Conditions are given to acertain that all solutions really are polynomials.

Riccardo Benedetti, Jean-Marc Gambaudo

A G-solenoid is a laminated space whose leaves are copies of a single Lie group G, and whose transversals are totally disconnected sets. It inherits a G-action and can be considered as dynamical system. Free Z^d-actions on the Cantor set as well as a large class of tiling spaces possess such a structure of G-solenoid. We show that a G-solenoid can be seen as

Nobuya Sato, Michihisa Wakui

In this paper, we establish a rigorous correspondence between the two tube algebras, that one comes from the Turaev-Viro-Ocneanu TQFT introduced by Ocneanu and another comes from the sector theory introduced by Izumi, and construct a canonical isomorphism between the centers of the two tube algebras, which is a conjugate linear isomorphism preserving the pro

Carmeliza Luna Navasca

We present methods for locally solving the Dynamic Programming Equations (DPE) and the Hamilton Jacobi Bellman (HJB) PDE that arise in the infinite horizon optimal control problem. The method for solving the DPE is the discrete time version of Al'brecht's procedure for locally approximating the solution of the HJB. We also prove the existence of the

Atsuo Kuniba, Masato Okado, Taichiro Takagi, Yasuhiko Yamada

We construct a geometric crystal for the affine Lie algebra D^{(1)}_n in the sense of Berenstein and Kazhdan. Based on a matrix realization including a spectral parameter, we prove uniqueness and explicit form of the tropical R, the birational map that intertwines products of the geometric crystals. The tropical R commutes with geometric Kashiwara operators

Yasuyuki Kawahigashi, Nobuya Sato, Michihisa Wakui

In this paper, we establish the general theory of (2+1)-dimensional topological quantum field theory (in short, TQFT) with a Verlinde basis. It is a consequence that we have a Dehn surgery formula for 3-manifold invariants for this kind of TQFT's. We will show that Turaev-Viro-Ocneanu unitary TQFT's obtained from subfactors satisfy the axioms of TQFT

A. Yu. Olshanskii, M. V. Sapir

We construct a finitely presented non-amenable group without free non-cyclic subgroups thus providing a finitely presented counterexample to von Neumann's problem. Our group is an extension of a group of finite exponent n >> 1 by a cyclic group, so it satisfies the identity [x,y]^n = 1.

Ernie Croot

We prove that if one has k non-intersecting arithmetic progressions of integers, with common differences 2 <= q_1,...,q_k <= x, then k < x exp((-1/6 + o(1)) sqrt(log x loglog x)). This improves a result of Szemeredi and Erdos.

J. Sawollek

It is an open question whether there are Vassiliev invariants that can distinguish an oriented knot from its inverse, i.e., the knot with the opposite orientation. In this article, an example is given for a first order Vassiliev invariant that takes different values on a virtual knot and its inverse. The Vassiliev invariant is derived from the Conway polynom

M. Bouhmadi-Lopez, P. F. Gonzalez-Diaz, A. Zhuk

By considering 5--dimensional cosmological models with a bulk filled with a pressureless scalar field; equivalently dust matter, and a negative cosmological constant, we have found a regular instantonic solution which is free from any singularity at the origin of the extra--coordinate. This instanton describes 5--dimensional asymptotically anti de Sitter wor

A. R. Mkrtchyan, A. A. Saharian, L. Sh. Grigoryan, B. V. Khachatryan

The influence of hypersonic waves excited in a single crystal is investigated on the process of electron-positron pair creation by high-energy photons. The coherent part of the corresponding differential cross-section is derived as a function of the amplitude and wave number of the hypersound. The values of the parameters are specified for which the latter a

K. Konishi

Three closely related issues will be discussed. Magnetic quarks having non-Abelian charges have been found recently to appear as the dominant infrared degrees of freedom in some vacua of softly broken N=2 supersymmetric QCD with SU(n_c) gauge group. Their condensation upon N=1 perturbation causes confinement and dynamical symmetry breaking. We argue that the

Shao-shiung Lin, Shi-shyr Roan

Using the Baxter&#39;s T-Q relation derived from the transfer matrix technique, we consider the diagonalization problem of discrete quantum pendulum and discrete quantum sine-Gordon Hamiltonian from the algebraic geometry aspect. For a finite chain system of the size L, when the spectral curve degenerates into rational curves, we have reduced Baxter&#39;s T-

M. R. Ahmady, F. A. Chishtie, V. Elias, A. H. Fariborz

QCD contributions to the $b \to u \ell^- \barν_\ell$ decay rate, which are known to two-loop order in the $\bar{MS}$ scheme, exhibit sufficient dependence on the renormalization mass $μ$ to compromise phenomenological predictions for inclusive semileptonic $B \to X_u$ processes. Such scale dependence is ameliorated by the renormalization-group (RG) extractio

Alfred H. Mueller

The relationship between RHIC and HERA data is explored using the idea of saturation (color glass condensate) as a unifying framework for interpretation. A description of the early stages of a heavy ion collision is given with the RHIC results. The relevant QCD dynamics at the various stages of a heavy ion collision, from production of gluons to equilibratio

M. Guidal, M. Vanderhaeghen

We study the double deeply virtual Compton scattering (DDVCS) process off the nucleon, through the scattering of a spacelike virtual photon with large virtuality resulting in the production of a timelike virtual photon, decaying into an e^+ e^- pair. This process is expressed in the Bjorken regime in terms of generalized parton distributions (GPDs) and it is

V. I. Demchik, V. V. Skalozub

The spontaneous generation of magnetic and chromomagnetic fields at high temperature in the minimal supersymmetric standard model (MSSM) is investigated. The consistent effective potential including the one-loop and the daisy diagrams of all bosons and fermions is calculated and the magnetization of the vacuum is observed. The mixing of the generated fields

A. Bottino, F. Donato, N. Fornengo, S. Scopel

After a short introduction on some general implications of recent cosmological observations, we discuss the properties of relic neutralinos in connection with present experimental strategies for detecting WIMPs.

B. Laforge

The introduction of extra space dimensions in the theory could be an elegant way tovsolve the hierarchy problem. There could even be one energy scale at which all interactions could unify. The limits coming from our knowledge of the gravitation at low distance allow this energy scale to be as low as few TeV. This situation is extremely interesting experiment

E. T. Tomboulis

We consider correlation inequalities that follow from the well-known loop equations of LGT, and their analogues in spin systems. They provide a way of bounding long range by short or intermediate range correlations. In several cases the method easily reproduces results that otherwise require considerable effort to obtain. In particular, in the case of the 2-

B. Lucini, M. Teper, U. Wenger

We report on our ongoing investigation of the deconfining phase transition in SU(4) and SU(6) gauge theories. We calculate the critical couplings while taking care to avoid the influence of a nearby bulk phase transition. We determine the latent heat of the phase transition and investigate the order and the strength of the transition at large N. We also repo

Z. Sroczynski

We present results for the performance of QCD code on ALiCE, the Alpha-Linux Cluster Engine at Wuppertal. We describe the techniques employed to optimise the code, including the metaprogramming of assembler kernels, the effects of data layout and an investigation into the overheads incurred by the communication.

Z. Fodor, S. D. Katz, K. K. Szabo

In this letter we give the equation of state of QCD at finite temperatures and densities. The recently proposed overlap improving multi-parameter reweighting technique is used to determine observables at nonvanishing chemical potentials. Our results are obtained by studying n_f=2+1 dynamical staggered quarks with semi-realistic masses on N_t=4 lattices.

John B. Kogut

I review present challenges that QCD in extreme environments presents to lattice gauge theory. Recent data and impressions from RHIC are emphasized. Physical pictures of heavy ion wavefunctions, collisions and the generation of the Quark Gluon Plasma are discussed, with an eye toward engaging the lattice and its numerical methods in more interaction with the

John B. Kogut

SU(2) lattice gauge theory with four flavors of quarks is simulated at nonzero chemical potential mu and temperature T and the results are compared to the predictions of Effective Lagrangians. Simulations on 16^4 lattices indicate that at zero T the theory experiences a second order phase transition to a diquark condensate state which is well described by me

T. Bhattacharya, G. T. Fleming, G. Kilcup, R. Gupta

We report on progress and future plans for calculating kaon weak matrix elements for epsilon&#39;/epsilon using staggered fermions.

I. Schmelzer

We present a new staggered discretization of the Dirac operator. In comparison with standard staggered fermions, real and imaginary parts are located in different nodes. Doubling gives only a doublet of Dirac fermions which we propose to interpret as a physical (lepton or quark) doublet. Contrary to usual staggered fermions, we have no exact chiral symmetry

K. Abe

A D0 meson can decay to K+ pi- through doubly Cabibbo-suppressed decay or via D0-D0bar mixing. With 46.2 fb^{-1} of integrated luminosity collected by Belle, we have measured the time integrated rate of the wrong-sign process D0 -> K+ pi- relative to that of the Cabibbo-favored process D0 -> K- pi+ to be R_WS = (0.372 +- 0.025 +0.009/-0.014) % (preliminary).

Gregory J. Galloway

The null splitting theorem (proved in math.DG/9909158) is discussed. As an application, a uniqueness theorem for Minkowski space and for de Sitter space associated with the occurrence of null lines (inextendible globally achronal null geodesics) is presented.

S. Picozzi, R. Asahi, C. B. Geller, A. J. Freeman

The technologically important problem of predicting Auger recombination lifetimes in semiconductors is addressed by means of a fully first--principles formalism. The calculations employ highly precise energy bands and wave functions provided by the full--potential linearized augmented plane wave (FLAPW) code based on the screened exchange local density appro

Shuichi Murakami, Naoto Nagaosa

The colossal magnetoresistance in manganites AMnO_3 is studied from the viewpoint of multicritical phenomena. To understand the complicated interplay of various phases, we study the Ginzburg-Landau theory in terms of both the mean-field approximation and the renormalization-group analysis to compare with the observed phase diagram. Several novel features, su

Z. L. Xiao, Catherine Y. Han, U. Welp, H. H. Wang

Large area nickel antidot arrays with density up to 10^10 /cm^2 have been fabricated by depositing nickel onto anodic aluminum oxide membranes that contain lattices of nanopores. Electron microscopy images show a high degree of order of the antidot arrays. Various sizes and shapes of the antidots were observed with increasing thickness of the deposited nicke

Xin Wan, Kun Yang, Chenggang Zhou, R. N. Bhatt

We study quantum spin-1/2 Heisenberg ferromagnetic chains with dilute, random antiferromagnetic impurity bonds with modified spin-wave theory. By describing thermal excitations in the language of spin waves, we successfully observe a low-temperature Curie susceptibility due to formation of large spin clusters first predicted by the real-space renormalization

Arup Banerjee, Manoranjan P. Singh

We study the effect of going beyond the Gross-Pitaevskii theory on the frequencies of collective oscillations of a trapped Bose gas in the large gas parameter regime. We go beyond the Gross-Pitaevskii regime by including a higher-order term in the interatomic correlation energy. To calculate the frequencies we employ the sum-rule approach of many-body respon

F. Pignatelli, A. V. Ustinov

We present experimental observation of broken-symmetry states in a superconducting loop with three Josephson junctions. These states are generic for discrete breathers in Josephson ladders. The existence region of the breather-like states is found to be in good accordance with the theoretical expectations. We observed three different resonant states in the c

C. D. Batista, J. Bonča, J. E. Gubernatis

We introduce a novel mechanism for itinerant ferromagnetism, based on a simple two-band model. The model includes an uncorrelated and dispersive band hybridized with a second band which is narrow and correlated. The simplest Hamiltonian containing these ingredients is the Periodic Anderson Model (PAM). Using quantum Monte Carlo and analytical methods, we sho

C. L. Kane, Matthew P. A. Fisher

We analyze theoretically a three-terminal geometry in a fractional quantum Hall system - studied in a recent experiment - which allows a dilute beam of Laughlin quasiparticles to be prepared and subsequently scattered by a point contact. Employing a chiral Luttinger liquid description of the nu^{-1} = m integer edge states, we compute the current and noise o

Sergey V. Barabash, David Stroud

We discuss the low-frequency absorption arising from quenched inhomogeneity in the superfluid density rho_s of a model superconductor. Such inhomogeneities may arise in a high-T_c superconductor from a wide variety of sources, including quenched random disorder and static charge density waves such as stripes. Using standard classical methods for treating ran

A. Barhdadi, M. Chafik El Idrissi

The present work is essentially focused on the study of optical and structural properties of hydrogenated amorphous silicon thin films (a-Si:H) prepared by radio-frequency cathodic sputtering. We examine separately the influence of hydrogen partial pressure during film deposition, and the effect of post-deposition thermal annealings on the main optical chara

Suzanne M. Fielding, Peter D. Olmsted

Motivated by experiments on wormlike micelles, we study the early stages of the shear banding instability using a two-fluid Johnson-Segalman model. We perform a linear stability analysis for coupled fluctuations in shear rate, micellar strain and concentration about an initially homogeneous state. First we calculate the ``spinodal&#39;&#39; onset of instabil

G. Bouzerar, J. Kudrnovsky, P. Bruno

Carrier induced ferromagnetism in diluted III-V semi-conductor is analyzed within a two step approach. First, within a single site CPA formalism, we calculate the element resolved averaged Green&#39;s function of the itinerant carrier. Then using a generalized RKKY formula we evaluate the Mn-Mn long-range exchange integrals and the Curie temperature as a fun

P. Prelovsek, A. Ramsak

The theoretical investigation of spectral functions and pseudogap in systems with strongly correlated electrons is discussed, with the emphasis on the single-band t-J model as relevant for superconducting cuprates. The evidence for the pseudogap features from numerical studies of the model is presented. One of the promising methods to study spectral function

T. Scopigno, A. Filipponi, M. Krisch, G. Monaco

The microscopic dynamics in liquid gallium (l-Ga) at melting (T=315 K) has been studied by inelastic x-ray scattering. We demonstrate the existence of collective acoustic-like modes up to wave-vectors above one half of the first maximum of the static structure factor, at variance with earlier results from inelastic neutron scattering data [F.J. Bermejo et al

Yunbo Zhang, Wei-Dong Li, Lu Li, H. J. W. Müller-Kirsten

The tunneling rate of a skyrmion in ferromagnetic spin-1/2 Bose condensates through an off-centered potential barrier is calculated exactly with the periodic instanton method. The prefactor is shown to depend on the chemical potential of the core atoms, at which level the atom tunnels. Our results can be readily extended to estimate the lifetime of other top

A. Yakubovskii, A. Trokiner, S. Verkhovskii, A. Gerashenko

The charge and orbital ordering in Pr_{0.5} Ca_{0.5} MnO_3 is studied for the first time by ^{17}O NMR. This local probe is sensitive to spin, charge and orbital correlations. Two transitions exist in this system: the charge and orbital ordering at T_{CO} = 225 K and the antiferromagnetic (AF) transition at T_N = 170 K. Both are clearly seen in the NMR spect

K. Yamaura, Q. Huang, D. P. Young, M. Arai

The novel 4d perovskite compound SrRhO3 was investigated by isovalent doping studies. The solubility limits of Ca and Ba onto Sr-site were below 80% and 20%, respectively. Although SrRhO3 was chemically compressed, approximately 5.7% by the Ca doping, no significant influence was observed on the magnetic and electrical properties.

Weiping Zhang, Chris P. Search, Han Pu, Pierre Meystre

We study the propagation of an atom laser beam through a spatial region with a magnetic field tuned to a Feshbach resonance. Tuning the magnetic field below the resonance produces an effective focusing Kerr medium that causes a modulational instability of the atomic beam. Under appropriate circumstances, this results in beam breakup and filamentation seeded

K. Goral, L. Santos

We analyze the ground-state properties and the excitation spectrum of Bose-Einstein condensates of trapped dipolar particles. First, we consider the case of a single-component polarized dipolar gas. For this case we discuss the influence of the trapping geometry on the stability of the condensate as well as the effects of the dipole-dipole interaction on the

Sebastian Wolf, Hubert Klahr

We investigate the possibility of mapping large-scale anti-cyclonic vortices, resulting from a global baroclinic instability, as pre-cursors of planet formation in proto-planetary disks with the planned Atacama Large Millimeter Array (ALMA). On the basis of three-dimensional radiative transfer simulations, images of a hydrodynamically calculated disk are der

Yong-Seon Song, Asantha Cooray, Lloyd Knox, Matias Zaldarriaga

The intervening large--scale structure distorts cosmic microwave background (CMB) anisotropies via gravitational lensing. The same large--scale structure, traced by dusty star--forming galaxies, also induces anisotropies in the far--infrared background (FIRB). We investigate the resulting inter--dependence of the FIRB and CMB with a halo model for the FIRB.

Demosthenes Kazanas, Markos Georganopoulos, Apostolos Mastichiadis

We propose that the internal energy of the GRB blast waves, thought to be stored in the form of relativistic protons co-moving with the blast wave, is converted explosively (i.e. on light crossing time scales) into relativistic electrons of the same Lorentz factor, which are responsible for the production of observed prompt gamma-ray emission of the burst. T

Nader Haghighipour

The results of an extensive numerical study of the orbital dynamics of small bodies ranging from micron-sized dust grains to 1 km objects subject to gas drag and also the gravitational attraction of a non-uniform gaseous nebula are presented. The results indicate that it is possible for small bodies to migrate rapidly toward the locations of the maxima of th

M. Guainazzi, C. Stanghellini, P. Grandi

We report in this paper the ASCA discovery of the first radio-loud Active Galactic Nucleus (AGN) covered by a Compton-thick X-ray absorber, in the GigaHertz Peaked Spectrum (GPS) radio source OQ+208. It represents one of the few available direct measurements of dense matter in the nuclear environment of this class of sources, which may provide the confining

Eugenio J. Rivera, Nader Haghighipour

In this paper, we present preliminary results on the stability of massless particles in two and three-planet systems. The results of our study may be used to address questions concerning the stability of terrestrial planets in these systems and also the trapping of particles in resonances with the planets. The possibility of the existence of islands of stabi

D. J. Fixsen, P. G. A. Mirel, A. Kogut, M. Seiffert

The thermometer and thermal control system, for the Absolute Radiometer for Cosmology, Astrophysics, and Diffuse Emission (ARCADE) experiment, is described, including the design, testing, and results from the first flight of ARCADE. The noise is equivalent to about 1 Omega or 0.15 mK in a second for the RuO_2 resistive thermometers at 2.7 K. The average powe

H. -G. Ludwig, F. Allard, P. H. Hauschildt

Based on detailed 2D and 3D numerical radiation-hydrodynamics (RHD) simulations of time-dependent compressible convection, we have studied the dynamics and thermal structure of the convective surface layers of a prototypical late-type M-dwarf (Teff~2800K log(g)=5.0, solar chemical composition). The RHD models predict stellar granulation qualitatively similar

H. -G. Ludwig

We constructed hydrodynamical model atmospheres for mid M-type main-, as well as pre-main-sequence objects. Despite the complex chemistry encountered in such cool atmospheres a reasonably accurate representation of the radiative transfer is possible. The detailed treatment of the interplay between radiation and convection in the hydrodynamical models allows

H. Beuther, J. Kerp, T. Preibisch, T. Stanke

We report the detection of hard X-ray emission (>2 keV) from a number of point sources associated with the very young massive star-forming region IRAS 19410+2336. The X-ray emission is detected from several sources located around the central and most deeply embedded mm continuum source, which remains undetected in the X-ray regime. All X-ray sources have K-b

L. Monaco, F. R. Ferraro, M. Bellazzini, E. Pancino

We present V, I photometry of the Sagittarius Dwarf Spheroidal galaxy (Sgr) for a region of ~ 1^{circ} times 1^{circ}, centered on the globular cluster M 54. This catalog is the largest database of stars (~500,000) ever obtained for this galaxy. The wide area covered allows us to measure for the first time the position of the RGB-bump, a feature that has bee

A. Shearer, A. Golden

Observations of the five confirmed optical pulsars indicate that the peak emission scales according to the magnetic field strength at the light cylinder. To the accuracy that such low number allows we show that this gives further confirmation that a straightforward synchrotron model such as Pacini & Salvati (1987) still has validity. The derived relationship

J. M. Deharveng, A. Boselli, J. Donas

We have assembled a UV-flux selected sample of 82 early-type galaxies and collected additional information at other wavelengths. These data confirm a large spread of the UV-V color in the range 2 to 5. The spread in UV-V is accompanied by a spread in B-V that is mainly attributed to the range of morphological types and luminosities. A large fraction of the o

R. Samadi, A. Nordlund, R. F. Stein, M. J. Goupil

A 3D simulation of the upper part of the solar convective zone is used to derive constraints about the averaged and dynamic properties of solar turbulent convection. Theses constraints are then used to compute the acoustic energy supply rate P(nu) injected into the solar radial oscillations according to the theoretical expression in Samadi & Goupil (2001). T

H. J. de Vega

The physics during the inflationary stage of the universe is of quantum nature involving extremely high energy densities. Moreover, it is out of equilibrium on a fastly expanding dynamical geometry. We complement here the 1999 Chalonge Lectures on out of equilibrium fields in self-consistent inflationary dynamics [astro-ph/0006446] investigating inflation dr

O. Reimer, K. T. S. Brazier, A. Carrami, G. Kanbach

The EGRET telescope aboard NASAs Compton GRO has repeatedly detected 3EG J1835+5918, a bright and steady source of high-energy gamma-ray emission with no identification suggested until recently. The long absence of any likely counterpart for a bright gamma-ray source located 25 degrees off the Galactic plane initiated several attempts of deep observations at

R. Schopper, H. Ruhl, T. A. Kunzl, H. Lesch

We present the numerical simulations of coherent inverse Compton scattering (CICS) in a highly magnetized plasma process by means of a full three dimensional particle in cell code (PIC), which is mass and energy conservative. We used the parameters of a pulsar magnetosphere where CICS is one of the most promising models for the generation of the observed hig

R. Samadi, M. J. Goupil, G. Houdek

Model computations of Delta Scuti stars, located in the vicinity of the red edge of the classical instability strip, suggest amplitudes of solar-like oscillations larger than in cooler models located outside the instability strip. Solar-like amplitudes in our Delta Scuti models are found to be large enough to be detectable with ground-based instruments provi

A. N. Lommen

We calculate a new gravitational wave background limit using timing residuals from PSRs J1713+0747, B1855+09, and B1937+21. The new limit is based on 17 years of continuous data pieced together from 3 different observing projects: 2 at the Arecibo Observatory and 1 at the 140ft Green Bank Telescope. This project represents the earliest results from the `Puls

W. Sieber

Problems solved? Pulsar research must be considered - 35 years after the detection of pulsars - a mature science, where the basic questions have been raised and discussed. One would hope that many if not all generic and important problems have found some kind of answer and that scientific work can concentrate now on specific details requiring more in depth i

W. Kundt

We are still far from understanding how pulsars pulse, how neutron stars are born, what neutron stars can emit, and in which way they do this. In this short communication, I list 18 alternatives -- several of them old, a few of them new -- which are handled differently by different authors but all of which are crucial for a model of neutron stars to be viabl

E. V. Gotthelf, C. M. Olbert

We present preliminary results from a systematic spectral study of pulsars and their wind nebulae using the Chandra X-Ray Observatory. The superb spatial resolution of Chandra allows us to differentiate the compact object&#39;s spectrum from that of its surrounding nebulae. Specifically, for six Crab-like pulsars, we compare spectral fits of the averaged pul

Th. Kunzl, H. Lesch, A. Jessner

We present the outline of a new model for the coherent radio emission of pulsars that succeeds in reproducing the energetics and brightness temperatures of the observed radio emission from the observationally deduced distances of 50-100 pulsar radii above the neutron star in a narrow region. The restrictions imposed by energy conservation, plasma dynamics of

Steen Hannestad

We review the current status of neutrino cosmology, focusing mainly on the question of the absolute values of neutrino masses and the possibility of a cosmological neutrino lepton asymmetry.

Y. E. Lyubarsky

Generation of the pulsar radio emission from plasma waves excited by the two-stream instability is considered. Special attention is given to propagation effects.

Andres Meza

The stability of rotating isotropic spherical stellar systems is investigated by using N-body simulations. Four spherical models with realistic density profiles are studied: one of them fits the luminosity profile of globular clusters, while the remaining three models provide good approximations to the surface brightness of elliptical galaxies. The phase-spa

S. Shibata, J. Miyazaki, F. Takahara

We study self-consistency for the pulsar polar cap model. In general, there will remain an unscreened electric field at the pair production front (PPF). We have derived the condition of electric field screening by pairs in the presence of returning particles. A previous belief that pairs with a density higher than the Goldreich-Julian density immediately scr

F. Pacini

Concluding Remarks of the 270.WE-Heraeus Seminar on Neutron Stars, Pulsars and Supernova Remnants.

Michael Malquarti, Andrew R. Liddle

We carry out a comprehensive study of the dynamics of large-scale perturbations in quintessence scenarios. We model the contents of the Universe by a perfect fluid with equation of state w_f and a scalar field Q with potential V(Q). We are able to reduce the perturbation equations to a system of four first-order equations. During each of the five main regime

J. Kijak

This paper presents a method of estimation of emission altitudes using observational data - precise measurements of pulse profile widths at low intensity level. The analysis of emission altitudes obtained using this method for a large number of pulsars gives constraints that should be useful for theory of coherent pulsar emission. It seems that radio emissio

Vladislav V. Izmodenov

This paper reviews the theoretical approaches and existing models of the solar wind interaction with the Local Interstellar Cloud (LIC). Models discussed take into account the multi-component nature of the solar wind and local interstellar medium. Basic results of the modeling and their possible applications to interpretation of space experiments are summari

A. Possenti

The millisecond pulsars discovered in globular clusters are diagnostic tools for studying the dynamics of the clusters, the intracluster ionized gas and the evolution of the binaries embedded in the cluster. In the first two years of a search at 1.4 GHz in progress at the Parkes radio telescope 12 new millisecond pulsars have been discovered in 6 globular cl

Pradip Gangopadhyay, Vlad Izmodenov, Mike Gruntman, Darrell Judge

The Very Local Interstellar Medium (VLISM) neutral hydrogen and proton densities are still not precisely known even after three decades of deep space research and the existence of the EUV and other diagnostic data obtained by Pioneer 10/11, Voyager 1/2 and other spacecraft. The EUV data interpretation, in particular, has suffered because of inadequate neutra

Richard Wielebinski

Pulsars have now been studied for 34 years. We know of the existence of some 1500 objects at radio frequencies. Many of the characteristics of pulsars such as pulsar period, period derivative, spectrum, polarization, etc., have been catalogued for many objects. Still we do not know the details of the pulsar emission mechanism. The present review will give an

Francesco Palla, Steven W. Stahler

To understand the formation of stellar groups, one must first document carefully the birth pattern within real clusters and associations. In this study of Taurus-Auriga, we combine pre-main-sequence ages from our own evolutionary tracks with stellar positions from observational surveys. Aided by the extensive, millimeter data on the molecular clouds, we deve

Joss Bland-Hawthorn, Martin Cohen

During a 9-month campaign (1996--1997), the Midcourse Space Experiment (MSX) satellite mapped the Galactic Plane at mid-infrared wavelengths (4.3--21.3um). Here we report evidence for a spectacular limb- brightened, bipolar structure at the Galactic Center extending more than a degree (170 pc at 8.0 kpc) on either side of the plane. The 8.3um emission shows

D. Boyanovsky, H. J de Vega, M. Simionato

We study the generation of magnetic fields during the stage of particle production resulting from spinodal instabilities during phase transitions out of equilibrium. The main premise is that long-wavelength instabilities that drive the phase transition lead to strong non-equilibrium charge and current fluctuations which generate electromagnetic fields. We pr

Harry L. Morrison, Achilles D. Speliotopoulos

Using results from sheaf theory combined with the phenomenological theory of the two-dimensional superfluid, the precipitation of quantum vortices is shown to be the genesis of a macroscopic order parameter for a phase transition in two dimensions.

Erin K. S. Hicks, Matthew A. Malkan, Harry I. Teplitz, Patrick J. McCarthy

Optical spectra of 14 emission-line galaxies representative of the 1999 NICMOS parallel grism Ha survey of McCarthy et al. are presented. Of the 14, 9 have emission lines confirming the redshifts found in the grism survey. The higher resolution of our optical spectra improves the redshift accuracy by a factor of 5. The [O II]/Ha values of our sample are foun

M. Landriau, E. P. S. Shellard

We present methods to compute maps of CMB fluctuations from high resolution cosmic string networks using a full Boltzmann code, on both large and small angular scales. The accuracy and efficency of these methods are discussed.

A. Reyes, F. J. Rodriguez, L. Quiroga

We present results on both the intensity and phase-dynamics of the transient non-linear optical response of a single quantum dot (SQD). The time evolution of the Four Wave Mixing (FWM) signal on a subpicosecond time scale is dominated by biexciton effects. In particular, for the cross-polarized excitation case a biexciton bound state is found. In this latter

Adrienne M. Juett, Duncan K. Galloway, Deepto Chakrabarty

We present the high-resolution spectrum of the accretion-powered millisecond pulsar XTE J0929-314 during its 2002 outburst, measured using the Low Energy Transmission Grating Spectrometer onboard the Chandra X-ray Observatory. The 1.5-25.3 A (0.5-8.3 keV) Chandra spectrum is well fit by a power-law + blackbody model with photon index Gamma=1.55+/-0.03, black

L. Burakovsky, C. W. Greeff, D. L. Preston

An analytic model of the shear modulus applicable at temperatures up to melt and at all densities is presented. It is based in part on a relation between the melting temperature and the shear modulus at melt. Experimental data on argon are shown to agree with this relation to within 1%. The model of the shear modulus involves seven parameters, all of which c

G. Jackeli

We present a microscopic theory of carrier-induced ferrimagnetism in metallic double perovskite compounds such as ${\rm Sr}_{2}{\rm FeMoO}_{6}$ and ${\rm Sr}_{2}{\rm FeReO}_{6}$ which have recently attracted intense interest for their possible applications to magnetotransport devices. The theory is based on an effective &#34;Kondo-like&#34; Hamiltonian treat

Bhuvnesh Jain

The magnification effects of clustered matter produce variations in the image sizes and number density of galaxies across the sky. This paper advocates the use of these effects in wide field surveys to map large-scale structure and the profiles of galaxy and cluster sized halos. The magnitude of the size variation as a function of angular scale is computed a

F. Lenz, D. Steinbacher

The Casimir effect is investigated in light-cone quantization. It is shown that for spacelike separation of the walls enclosing the system the standard result for the pressure exerted on the walls is obtained. For walls separated in light-cone space direction no regularization of the quantum fluctuations exists which would yield a finite pressure. The origin

B. Field

In this letter we examine the production channels for the scalar or pseudoscalar Higgs plus two jets at the CERN Large Hadron Collider (LHC). We identify possible signals for distinguishing between a scalar and a pseudoscalar Higgs boson.

Kirill N. Alekseev, Feodor V. Kusmartsev

We describe a limiting case when nonlinear dynamics of an ac-driven semiconductor superlattice in the miniband transport regime is governed by a periodically forced and damped pendulum. We find analytically the conditions for a transition to chaos and consider an influence of temperature on the effect. We also discuss fractional dc voltage states in a superl

George B. Rybicki

A kinetic equation for Compton scattering is given that differs from the Kompaneets equation in several significant ways. By using an inverse differential operator this equation allows treatment of problems for which the radiation field varies rapidly on the scale of the width of the Compton kernel. This inverse operator method describes, among other effects

Daniel F. Litim, Jan M. Pawlowski

We study exact renormalisation group flows for background field dependent regularisations. It is shown that proper-time flows are approximations to exact background field flows for a specific class of regulators. We clarify the role of the implicit scale dependence introduced by the background field. Its impact on the flow is evaluated numerically for scalar

N. D. Lambert, I. Sachs

Recently effective actions have been extensively used to describe tachyon condensation in string theory. While the various effective actions which have appeared in the literature have very similar properties for static configurations, they differ for time-dependent tachyons. In this paper we discuss general properties of non-linear effective Lagrangians whic