April 2002 arXiv papers — page 12

Mannque Rho

This note is based on four lectures that I gave at the 10th Taiwan Nuclear Spring School held at Hualien, Taiwan in January 2002. It aims to correlate the old notion of Cheshire Cat Principle developed for elementary baryons to the modern notion of quark-baryon and gluon-meson "continuities" or "dualities" in dilute and dense many-body system

V. B. Taranenko, C. O. Weiss

We show experimentally and numerically the existence of stable spatial solitons in an optically pumped semiconductor microresonator. We demonstrate that the pump substantially reduces the light intensity necessary to sustain the solitons and thereby reduces destabilizing thermal effects. We demonstrate coherent switching on and off of bright solitons. We dis

Siegfried Fussy, Gerhard Groessing, Herbert Schwabl

Highly nonlinear behavior of a system of discrete sites on a lattice is observed when a specific feedback loop is introduced into models employing coupled map lattices, quantum cellular automata, or the real-valued analogues of the latter. It is shown that the combination of two operations, i.e. i) enhancement of a site's value when fulfilling a feedback

Takahisa Harayama, Rainer Klages, Pierre Gaspard

We propose a flower shape billiard in order to study the irregular parameter dependence of chaotic normal diffusion. Our model is an open system consisting of periodically distributed obstacles of flower shape, and it is strongly chaotic for almost all parameter values. We compute the parameter dependent diffusion coefficient of this model from computer simu

L. Ts. Adzhemyan, N. V. Antonov, J. Honkonen

The renormalization group and operator product expansion are applied to the model of a passive scalar quantity advected by the Gaussian self-similar velocity field with finite, and not small, correlation time. The inertial-range energy spectrum of the velocity is chosen in the form $E(k)\propto k^{1-2\eps}$, and the correlation time at the wavenumber $k$ sca

Taku Matsui, Yoshihito Shimada

We consider an infinite dimensional generalization of Metaplectic representations (Weil representations) for the (double covering of) symplectic group. Given quasifree states of an infinite dimensional CCR algebra, projective unitary representations of the infinite dimensional symplectic group are constructed via unitary implementors of Bogoliubov automorphi

Young-Hoon Kiem

We compute the stringy E function of the moduli space of rank 2 bundles over a Riemann surface of genus 3. In doing so, we answer a question of Batyrev about the stringy E functions of the GIT quotients of linear representations.

D. D. Long, A. W. Reid

We show that all closed flat n-manifolds are diffeomorphic to a cusp cross-section in a finite volume hyperbolic (n+1)-orbifold.

A. Zinger

We give a formula computing the number of one-nodal rational curves that pass through an appropriate collection of constraints in a complex projective space. We combine the methods and results from three different papers.

Ugo Boscain, Thomas Chambrion, Jean-Paul Gauthier

We apply techniques of subriemannian geometry on Lie groups to laser-induced population transfer in a three-level quantum system. The aim is to induce transitions by two laser pulses, of arbitrary shape and frequency, minimizing the pulse energy. We prove that the Hamiltonian system given by the Pontryagin Maximum Principle is completely integrable, since th

Daciana Bochis, Francisco Santos

We prove that Dirichlet stereohedra for non-cubic crystallographic groups in dimension 3 cannot have more than 80 facets. The bound depends on the particular crystallographic group considered and is above 50 only on 9 of the 97 affine conjugacy classes of them. We also construct Dirichlet stereohedra with 32 and 29 facets for a hexagonal and a tetragonal gro

Paolo Aluffi

We discuss an algorithm computing the push-forward to projective space of several classes associated to a (possibly singular, reducible, nonreduced) projective scheme. For example, the algorithm yields the topological Euler characteristic of the support of a projective scheme $S$, given the homogeneous ideal of $S$. The algorithm has been implemented in Maca

B. Enriquez, G. Halbout

We prove that if U_h(g) is a quasitriangular QUE algebra with universal R-matrix R, and O_h(G^*) is the quantized function algebra sitting inside U_h(g), then h log(R) belongs to the tensor square O_h(G^*) otimes O_h(G^*). This gives another proof of the results of Gavarini and Halbout, saying that R normalizes O_h(G^*) otimes O_h(G^*) and therefore induces

Julien Bichon

We show that there exists cosemisimple Hopf algebras of arbitrary finite even order. We also discuss the Schur indicator for such Hopf algebras.

Francis Fung

We describe the irreducible components of Springer fibers for hook and two-row nilpotent elements of gl_n(C) as iterated bundles of flag manifolds and Grassmannians. We then relate the topology (in particular, the intersection homology Poincare' polynomials) of the intersections of these components with the inner products of the Kazhdan-Lusztig basis ele

Satyajit S Karnik

We study the action of the group of automorphisms of the projective plane on the Maruyama scheme of sheaves $\mathcal{M}_{P^{2}}(r,c_{1,}c_{2})$ of rank $r$ and Chern classes $c_{1}=0$ and $c_{2}=n$ and obtain sufficient conditions for unstability in the sense of Mumford's geometric invariant theory. The conditions are in terms of the splitting behaviour

Francisco Santos, Raimund Seidel

We show that a point set of cardinality $n$ in the plane cannot be the vertex set of more than $59^n O(n^{-6})$ straight-edge triangulations of its convex hull. This improves the previous upper bound of $276.75^n$.

Maxim Braverman

We present a short analytic proof of the equality between the analytic and combinatorial torsion. We use the same approach as in the proof given by Burghelea, Friedlander and Kappeler, but avoid using the difficult Mayer-Vietoris type formula for the determinants of elliptic operators. Instead, we provide a direct way of analyzing the behaviour of the determ

D. G. C. McKeon

We examine noncommutative Chern Simons theory using operator regularization. Both the zeta-function and the eta-function are needed to determine one loop effects. The contributions to these functions coming from the two point function is evaluated. The U(N) noncommutative model smoothly reduces to the SU(N) commutative model as the noncommutative parameter t

S. Cacciatori, L. Martucci

In this paper we propose a generalization of N=4 three dimensional AdS supergravity to the noncommutative case. This is a supersymmetric version of the results presented in hep-th/0201103. We show that it continues to admit an N=4 supersymmetric solution which is the noncommutative couterpart of AdS_3 space. Some other solutions are also discussed.

Dmitri Antonov

The Berezinsky-Kosterlitz-Thouless (BKT) RG flow in the ensemble of monopoles existing in the finite-temperature (2+1)D Georgi-Glashow model is explored in the regime when the Higgs field is not infinitely heavy, but its mass is rather of the same order of magnitude as the mass of the W-boson. The corrections to the standard RG flow are derived to the leadin

T. Padmanabhan

It is an accepted practice in cosmology to invoke a scalar field with potential $V(ϕ)$ when observed evolution of the universe cannot be reconciled with theoretical prejudices. Since one function-degree-of-freedom in the expansion factor $a(t)$ can be traded off for the function $V(ϕ)$, it is {\it always} possible to find a scalar field potential which will

B. Kampfer, J. Cleymans, K. Gallmeister, S. M. Wheaton

The centrality dependence of thermal parameters describing hadron multiplicities and intermediate-mass dilepton spectra in heavy-ion collisions at SPS and RHIC is analyzed. From experimental hadron multiplicities we deduce evidence for strangeness saturation at high energy and maximum centrality. The observed dilepton spectra can be parameterized by a centra

Carlos A. Salgado, Urs Achim Wiedemann

Medium modifications of parton fragmentation provide a novel tomographic tool for the study of the hot and dense matter created in ultrarelativistic nucleus-nucleus collisions. Their quantitative analysis, however, is complicated by the strong dynamical expansion of the collision region. Here, we establish for the multiple scattering induced gluon radiation

Michele Frigerio

We reconstruct the neutrino mass matrix in the flavor basis, using experimental data on neutrino oscillations. Both normal and inverted hierarchy (ordering) of the mass spectrum are considered. The dependence of the matrix structure on CP violating Majorana phases $ρ$ and $σ$ is studied. The results are shown in $ρ-σ$ plots. We find the possible matrix struc

Nicola Fabiano, Giulia Pancheri

We discuss the measured partial width of the pseudoscalar charmonium state eta_c into two photons. Predictions from potential models are examined and compared with experimental values. Including radiative corrections, it is found that present measurements are compatible both with a QCD type potential and with a static Coulomb potential. The latter is then us

R. Baier, A. H. Mueller, D. Schiff, D. T. Son

We discuss the recent claim that hadron multiplicities measured at RHIC energies are directly described in terms of gluon degrees of freedom fixed from the initial conditions of central heavy ion collisions. The argument is based on the parton saturation scenario expected to be valid at high parton densities and on the assumption of conserved gluon number. A

Y. Yan, R. Tegen, T. Gutsche, V. E. Lyubovitskij

The high energy proton-neutron charge exchange scattering reaction is studied in an effective hadron model for the energy range of s from 45.9 to 414.61 GeV*GeV. The main features of the observed differential cross section, the forward peak and the scaling behavior over a large energy region, are well reproduced.

The KLOE Collaboration

We have measured the ratio R=Gamma(Ks -> pi+pi-gamma)/Gamma(Ks -> pi0pi0) with the KLOE detector at the DAFNE e+e- collider. This measurement is fully inclusive with respect to the pi+pi-gamma final state. The sample of over 10^6 two-pion decays of tagged Ks mesons allows a statistical error as low as 0.1% to be obtained. The accuracy is limited by systemati

Alexander Vilenkin

This contribution consists of two parts. In the first part, I review the tunneling approach to quantum cosmology and comment on the alternative approaches. In the second part, I discuss the relation between quantum cosmology and eternal inflation. In particular, I discuss whether or not we need quantum cosmology in the light of eternal inflation, and whether

Hirotaka Yoshino, Yasusada Nambu

We investigate the apparent horizon formation for high-energy head-on collisions of particles in multi-dimensional spacetime. The apparent horizons formed before the instance of particle collision are obtained analytically. Using these solutions, we discuss the feature of the apparent horizon formation in the multi-dimensional spacetime from the viewpoint of

Naureen Goheer, Peter Dunsby

In this work we consider Randall-Sundrum braneworld type scenarios, in which the spacetime is described by a five-dimensional manifold with matter fields confined in a domain wall or three-brane. We present the results of a systematic analysis, using dynamical systems techniques, of the qualitative behaviour of Friedmann-Lemaitre-Robertson-Walker type models

Walter Eaves

This thesis addresses the problem of providing trusted individuals with confidential information about other individuals, in particular, granting access to databases of personal records using the World-Wide Web. It proposes an access rights management system for distributed databases which aims to create and implement organisation structures based on the wis

C. Reichhardt, C. J. Olson Reichhardt

We examine the motion of one-dimensional (1D) vortex matter embedded in a 2D vortex system with weak pinning using numerical simulations. We confirm the conjecture of Matsuda et al. [Science 294, 2136 (2001)] that the onset of the temperature induced motion of the chain is due to an incommensuration effect of the chain with the periodic potential created by

Marcus B. Pinto, Rudnei O. Ramos, Frederico F. de Souza Cruz

We analyze the possible transition patterns exhibited by an effective non-relativistic field model describing interacting binary homogeneous dilute Bose gases whose overall potential is repulsive. We evaluate the temperature dependence of all couplings and show that at intermediate temperatures the crossed interaction, which is allowed to be attractive, domi

X. F. Wang, P. Vasilopoulos, F. M. Peeters

Ballistic spin transport through waveguides, with symmetric or asymmetric double stubs attached to them periodically, is studied systematically in the presence of a weak spin-orbit coupling that makes the electrons precess. By an appropriate choice of the waveguide length and of the stub parameters injected spin-polarized electrons can be blocked completely

S. Dukan, T. P. Powell, Z. Tesanovic

We present a calculation of the quasiparticle contribution to the longitudinal thermal conductivities as well as transverse (Hall) thermal conductivity of an extreme type-II superconductor in a high magnetic field and at low temperatures. In the limit of frequency and temperature approaching zero, both longitudinal and transverse conductivities upon entering

Raul O. Vallejos, Celia Anteneodo

The largest Lyapunov exponent of an ergodic Hamiltonian system is the rate of exponential growth of the norm of a typical vector in the tangent space. For an N-particle Hamiltonian system, with a smooth Hamiltonian of the type p^2 + v(q), the evolution of tangent vectors is governed by the Hessian matrix V of the potential. Ergodicity implies that the Lyapun

Vasilii Gusakov

In cuprates superconductors (as polycrystal and single crystal samples) unusual hysteretic temperature behavior of elastic properties is frequently observed. In this work from the uniform point of view detailed analysis this abnormal temperature behavior of elastic properties is given. It is shown that the hysteretic temperature dependencies of elastic prope

German J. de Valcarcel

The parametrically driven, damped Gross-Pitaevskii equation, which models Bose-Einstein condensates in which the interatomic s-wave scattering length is modulated in time, is shown to support spatially modulated states in the form of rolls. A Landau equation with broken phase symmetry is derived, which governs the dynamics of the roll amplitude.

S. A. Blundell, M. D. Nunez-Regueiro

The recently elucidated structure of the delafossite YCuO$_{2.5}$ reveals a Cu-O network with nearly independent $Δ$ chains having different interactions between the $s=1/2$ spins. Motivated by this result, we study the $Δ$ chain for various ratios $J_{\rm bb}/J_{\rm bv}$ of the base-base and base-vertex interactions. By exact diagonalization and extrapolati

F. Bruno, L. Floreano, A. Verdini, D. Cvetko

The angular distribution of the intensity in photoemission experiments is affected by electron diffraction patterns and by a smoothly varying ISO contribution originated by both intrumental details and physical properties of the samples. The origin of the various contributions to the ISO component has been identified since many years. Nonetheless in this wor

P. Dimopoulos, D. Espriu, E. Jané, A. Prats

We study dynamical aspects of three--dimensional gonihedric spins by using Monte--Carlo methods. The interest of this family of models (parametrized by one self-avoidance parameter $κ$) lies in their capability to show remarkably slow dynamics and seemingly glassy behaviour below a certain temperature $T_g$ without the need of introducing disorder of any kin

Luca Salasnich

We investigate the critical temperature of an interacting Bose gas confined in a trap described by a generic isotropic power-law potential. We compare the results with respect to the non-interacting case. In particular, we derive an analytical formula for the shift of the critical temperature holding to first order in the scattering length. We show that this

F. Hohls, U. Zeitler, R. J. Haug

We analyze the conductance fluctuations observed in the quantum Hall regime for a bulk two-dimensional electron system in a Corbino geometry. We find that characteristics like the power spectral density and the temperature dependence agree well with simple expectations for universal conductance fluctuations in metals, while the observed amplitude is reduced.

P. Tegzes, T. Vicsek, P. Schiffer

We have studied the dynamics of avalanching wet granular media in a rotating drum apparatus. Quantitative measurements of the flow velocity and the granular flux during avalanches allow us to characterize novel avalanche types unique to wet media. We also explore the details of viscoplastic flow (observed at the highest liquid contents) in which there are la

Chitoshi Yasuda, Synge Todo, Munehisa Matsumoto, Hajime Takayama

Dilution effects on spin-1/2 quantum Heisenberg antiferromagnets with a non-magnetic spin-gapped ground state are studied by means of the qunatum Monte Carlo simulation. In the site-diluted system, an antiferromagnetic long-range order (AF-LRO) is induced at an infinitesimal concentration of dilution due to an effective coupling $\tilde{J}_{mn}$ between indu

Martin H. Müser

It has long been recognized that the key to understand kinetic friction force $F_k$ is the analysis of microscopic instabilities that lead to sudden irreversible "pops" of certain degrees of freedom. In this Letter, the nature of such instabilities is characterized with an emphasis on boundary lubricants. It is shown that there are certain critical v

Berit Hinnemann, Haye Hinrichsen, Dietrich E. Wolf

It has been observed experimentally that under certain conditions pulsed laser deposition (PLD) produces smoother surfaces than ordinary molecular beam epitaxy (MBE). So far the mechanism leading to the improved quality of surfaces in PLD is not yet fully understood. In the present work we investigate the physical properties of a simple model for PLD in whic

V. D. Krevchik, A. B. Grunin, A. K. Aringazin, M. B. Semenov

Magneto-optical properties of the quantum dot - impurity center (QD-IC) systems synthesized in a transparent dielectric matrix are considered. For the QD one-electron state description the parabolic model of the confinement potential is used. Within the framework of zero-range potential model and the effective mass approach, the light impurity absorption coe

C. J. Bolech, N. Andrei

We solve the two-channel Anderson impurity model using the Bethe-Ansatz. We determine the ground state and derive the thermodynamics, obtaining the impurity entropy and specific heat over the full range of temperature. We show that the low temperature physics is given by a line of fixed points decribing a two-channel non Fermi liquid behavior in the integral

X. F. Wang, P. Vasilopoulos, F. M. Peeters

Ballistic spin transport is studied through electronic tuners with double stubs attached to them. The spins precess due to the spin-orbit interaction. Injected polarized spins can exit the structure polarized in the opposite direction. A nearly square-wave spin transmission, with values 1 and 0, can be obtained using a periodic system of symmetric stubs and

Aldo H. Romero, J. M. Sancho, Katja Lindenberg

We examine the mean first passage time for a particle driven by highly correlated Gaussian fluctuations to reach one or more predetermined boundaries. We discuss a numerical algorithm to generate power-law correlated fluctuations and apply these to three physical examples. One is the arrival of a free particle at either end of an interval. The second is the

Kazutomu Shiokawa, Raymond Kapral

The conditions under which an open quantum mechanical system may be described by mixed quantum-classical dynamics are investigated. Decoherence is studied using influence functional methods in a model composite quantum system comprising two coupled systems, A and C, interacting with a harmonic bath with Ohmic and super-Ohmic spectral densities. Subsystem A i

Takuma Ohashi, Sei-ichiro Suga

We investigate the Kondo effect in two-dimensional disordered electron systems using a finite-temperature quantum Monte Carlo method. Depending on the position of a magnetic impurity, the local moment is screened or unscreened by the spin of the conduction electron. The results suggest that the Kondo temperature takes different values depending on the positi

E. Novais, E. Miranda, A. H. Castro Neto, G. G. Cabrera

We establish the phase diagram of the one-dimensional anisotropic Kondo lattice model at T=0 using a generalized two-dimensional classical Coulomb gas description. We analyze the problem by means of a renormalization group (RG) treatment. We find that the phase diagram contains regions of paramagnetism, partial and full ferromagnetic order.

Manolis Plionis

Evidence is presented for a recent evolution of the relaxation processes in clusters of galaxies, using large optical and X-ray cluster samples. The criteria of the cluster relaxation used are the cluster ellipticity, the ICM temperature and X-ray cluster luminosity. We find evidence of varying strength and significance of all three indicators evolving with

S. Cote, A. R. Taylor, P. E. Dewdney

The Canadian Large Adaptive Reflector (CLAR) is a proposed prototype of a new concept for large, filled-aperture radio telescopes. The prototype would have a 300-metre aperture, working up to frequencies of at least 1.4 GHz, and would be equipped with a multi-beam phased array providing a field-of-view of 0.8deg at that frequency. The largest fully-steerable

T. P. Sasseen, I. Eisenman, K. Mason, The XMM Optical Monitor Team

We use galaxies detected in a deep ultraviolet XMM-Newton Optical Monitor image and a model that predicts UV galaxy counts based on local counts and evolution parameters to constrain galaxy evolution to Z=1.2. The 17' square 2000 angstrom (UVW2 filter) image was taken as part of the XMM-OM team's guaranteed time program. We detect sources in this ima

Yuichi Terashima, Andrew S. Wilson

We present the results of Chandra observations of off-nuclear X-ray sources in the spiral galaxy M51 (NGC 5194). 113 X-ray sources have been detected in the field of view and 84 among them project within the disk of NGC 5194. Six and twenty eight sources have luminosities exceeding 1x10^39 ergs s^-1 and 1x10^38 ergs s^-1 in the 0.5-8 keV band, respectively.

F. Ferrari, M. G. Pastoriza, F. D. Macchetto, C. Bonatto

We present mid-IR photometric properties for a sample of 28 early-type galaxies observed at 6.75, 9.63 and 15 um with the ISOCAM instrument on board the ISO satellite. We find total mid-IR luminosities in the range 3-48x10^8 L_sun. The spectral energy distribution (SED) of the galaxies were derived using the mid-IR data together with previously published UV,

Janet P. Simpson, Sean W. J. Colgan, Edwin F. Erickson, Dean C. Hines

We have observed the polarized light at 2 micron in the center of NGC 1068 with HST NICMOS Camera 2. The nucleus is dominated by a bright, unresolved source, polarized at a level of 6.0 pm 1.2% with a position angle of 122degr pm 1.5degr. There are two polarized lobes extending up to 8'' northeast and southwest of the nucleus. The polarized flux in b

H. Hirashita, Y. Y. Tajiri, H. Kamaya

This paper investigates the origin of the observed large variety in dust-to-gas ratio among blue compact dwarf galaxies (BCDs). By applying our chemical evolution model, we find that the dust destruction can largely suppress the dust-to-gas ratio when the metallicity of a BCD reaches $12+\log{\rm (O/H)}\sim 8$, i.e., a typical metallicity level of BCDs. We a

Sidney van den Bergh

Observations in the Hubble Deep Fields have been used to study the evolution of galaxy morphology over time. The majority of galaxies with z < 1 are seen to be disk like, whereas most objects with z > 2 appear to be either chaotic or centrally concentrated ``blobs&#39;&#39;. Such blobs might be the ancestral objects of ellipticals or of galaxy bulges. About

J. J. Zach

Well into the deleptonization phase of a core collapse supernova, a first-order phase transition to matter with macroscopic strangeness content is assumed to occur and lead to a structured lattice defined by negatively charged strange droplets. The lattice is shown to crystallize for expected droplet charges and separations at temperatures typically obtained

F. Fontani, R. Cesaroni, P. Caselli, L. Olmi

We have used the IRAM 30-m and FCRAO 14-m telescopes to observe the molecular clumps associated with 12 ultracompact (UC) HII regions in the J=6-5, 8-7 and 13-12 rotational transitions of methyl-acetylene (CH3C2H). Under the assumption of LTE and optically thin emission, we have derived temperature estimates ranging from 30 to 56 K. We estimate that the clum

Anisa T. Bajkova

The generalized maximum entropy method (GMEM) is a special modification of the standard maximum entropy method (MEM) which seeks solutions in the space of complex functions. In this work a reduced version of the GMEM intended for reconstructing real images with positive and negative values is used. As compared with the standard MEM, intended for the reconstr

Swadesh M. Mahajan, Komunela I. Nikol&#39;skaya, Nana L. Shatashvili, Zensho Yoshida

It is shown that a generalized magneto-Bernoulli mechanism can effectively generate high velocity flows in the Solar chromosphere by transforming the plasma pressure energy into kinetic energy. It is found that at reasonable heights and for realistic plasma parameters, there is a precipitous pressure fall accompanied by a sharp amplification of the flow spee

Kee-Tae Kim, Bon-Chul Koo

We have observed extended emission physically associated with 15 out of 16 UC HII regions with large ratios of single-dish to VLA fluxes. We discuss their implications for the age problem of UC HII regions and the evolution of HII regions.

Kee-Tae Kim, Bon-Chul Koo

We have carried out 21 cm radio continuum, H76_αradio recombination line, and various (CO, ^13CO, CS, & C^34S) molecular line observations of the W31 complex. Our radio continuum data show that W31 is composed of two extended HII regions, G10.2-0.3 and G10.3-0.1, each of which comprises an ultracompact HII region, two or more compact components, and diffuse

A. Bonanno, D. Elstner, G. Ruediger, G. Belvedere

We have developed a high-precision code which solves the kinematic dynamo problem both for given rotation law and meridional flow in the case of a low eddy diffusivity of the order of $10^{11}$ cm$^2$/s known from the sunspot decay. All our models work with an \alf-effect which is positive (negative) in the northern (southern) hemisphere. It is concentrated

Miguel Alcubierre, F. Siddhartha Guzman, Tonatiuh Matos, Dario Nunez

We present a general description of the scalar field dark matter (SFDM) hypothesis in the cosmological context. The scenario of structure formation under such a hypothesis is based on Jeans instabilities of fluctuations of the scalar field. It is shown that it is possible to form stable long lived objects consisting of a wide range of typical galactic masses

M. Arnaud, S. Majerowicz, D. Lumb, D. M. Neumann

We report on a 20 ksec XMM observation of the distant cluster RXJ1120.1+4318, discovered at z=0.6 in the SHARC survey. The cluster has a regular spherical morphology, suggesting it is in a relaxed state. The combined fit of the EPIC/MOS&pn camera gives a cluster mean temperature of kT=5.3\pm0.5 keV with an iron abundance of 0.47\pm0.19. The temperature profi

C. H. Ishwara-Chandra, J. S. Yadav, A. Pramesh Rao

We present GMRT observations of the Galactic microquasar GRS 1915+105 at 1.28 GHz for 8 days from 2001 June 18 to July 1. We have seen several isolated radio flares of varying magnitudes (20 - 50 mJy) and durations (6 - 35 min) and we model them as due to adiabatically expanding synchrotron emitting clouds (synchrotron bubbles) ejected from the accretion dis

Q. Yuan, R. F. Green, M. Brotherton, T. M. Tripp

As one of the most luminous radio-loud quasars showing intrinsic ultraviolet (UV) and X-ray absorption, 3C 351 provides a laboratory for studying the kinematics and physical conditions of such ionized absorbers. We present an analysis of the intrinsic absorption lines in the high-resolution ($\sim$ 7 km/s) far-UV spectrum which was obtained from observations

M. A. Prieto, J. Reunanen, J. K. Kotilainen

We present deep L- and M- band imaging with ISAAC on the ESO VLT with unprecedented spatial resolution of the nearby Seyfert 2 galaxies NGC 7496 and NGC 7582 and the Seyfert 1 galaxy NGC 7213. The unresolved nuclear component dominates the emission within the central 90 pc region, while the host galaxy accounts for up to 50 % of the integrated emission at bo

J. G. Kirk, O. Skjaeraasen, Y. A. Gallant

The radiation of a pulsar wind is computed assuming that at roughly 10 to 100 light cylinder radii from the star, magnetic energy is dissipated into particle energy. The synchrotron emission of heated particles appears periodic, with, in general, both a pulse and an interpulse. The predicted spacing agrees well with the Crab and Vela pulse profiles.Using par

Yuka Y. Tajiri, Hideyuki Kamaya

We investigate the star-formation history of gas-rich dwarf galaxies, taking account of the dynamical evolution of their neutral hydrogen (H{\sc i}) envelope. Gas-rich dwarfs are classified into blue compact dwarfs (BCDs) and dwarf irregulars (dIrrs). In this paper, their H{\sc i} envelope is clearly shown not to be blown away by their stellar feedback. This

Kazuki Takahashi, Hajime Inoue, Tadayasu Dotani

We have studied the origin of the broad and skewed feature at 4.5-7.5 keV in the energy spectra of NGC4151 using the ASCA and RXTE data. The feature consists of a narrow peak at 6.4 keV and a broad wing extended between 4.5-7.5 keV. An analysis of the long-term variations revealed that the feature became variable only on a time scale longer than 1.5x10^6 s.

K. Noguchi, V. I. Pariev, S. A. Colgate, J. Nordhaus

Despite the importance of the magnetorotational instability (MRI) as a fundamental mechanism for angular momentum transport in magnetized accretion disks, it has yet to be demonstrated in the laboratory. A liquid sodium alpha-omega dynamo experiment at the New Mexico Institute of Mining and Technology provides an ideal environment to study the MRI in a rotat

A. O. Jaunsen, M. I. Andersen, J. Hjorth, J. P. U. Fynbo

As part of the HST/STIS GRB host survey program we present the detection of three faint gamma-ray burst (GRB) host galaxies based on an accurate localisation using ground-based data of the optical afterglows (OAs). A common property of these three hosts is their extreme faintness. The location at which GRBs occur with respect to their host galaxies and surro

Henk Hoekstra, Howard Yee, Mike Gladders

We have analysed 53 square degrees of imaging data from the Red-Sequence Cluster Survey (RCS), and measured the excess correlations in the shapes of galaxies on scales out to ~1.5 degrees. We separate the signal into an ``E&#39;&#39;- (lensing) and ``B&#39;&#39;-mode (systematics), which allows us to study residual systematics. On scales larger than 10 arcmi

B. C. Jacobs, T. B. Pittman, J. D. Franson

Probabilistic quantum non-demolition (QND) measurements can be performed using linear optics and post-selection. Here we show how QND devices of this kind can be used in a straightforward way to implement a quantum relay, which is capable of extending the range of a quantum cryptography system by suppressing the effects of detector noise. Unlike a quantum re

Alexander Belyaev, Tao Han, Rogerio Rosenfeld

We study the neutral Higgs boson production via the gluon fusion process with the $\tautau$ final state at the upgraded Fermilab Tevatron, including a complete simulation of signal channels and leading background processes. For the SM Higgs boson, this $h\to \tautau$ channel may provide important addition for the Higgs boson discovery in the mass range 120-1

Marcus Spradlin, Anastasia Volovich

We construct light-cone gauge superstring field theory in a pp-wave background with Ramond-Ramond flux. The leading term in the interaction Hamiltonian is determined up to an overall function of $p^+$ by requiring closure of the pp-wave superalgebra. The bosonic and fermionic Neumann matrices for this cubic vertex are derived, as is the interaction point ope

Silas R. Beane, Martin J. Savage

We show that processes involving pions that remain very near their mass-shell can be reliably computed in the pionless effective field theory, with the pion integrated in as a heavy field. As an application, we compute the pion-deuteron scattering amplitude near threshold to next-to-leading order in the momentum expansion. This amplitude is formally dominate

Kevork N. Abazajian, George M. Fuller

We point out that the relic densities of singlet (sterile) neutrinos of interest in viable warm and cold dark matter scenarios, depend on the characteristics of the QCD transition in the early universe. In the most promising of these dark matter scenarios the production of the singlets occurs at or near the QCD transition. Since production of the singlets, t

Marc Freitag, Willy Benz

We have recently written a new code to simulate the long term evolution of spherical clusters of stars. It is based on the pioneering Monte Carlo scheme proposed by Henon in the 70&#39;s. Our code has been devised in the specific goal to treat dense galactic nuclei. After having described how we treat relaxation in a first paper, we go on and include further

Luc Fournier, Bela Joos

We have constructed a model for the kinetics of rupture of membranes under tension, applying physical principles relevant to lipid bilayers held together by hydrophobic interactions. The membrane is characterized by the bulk compressibility (for expansion), the thickness of the hydrophobic part of the bilayer, the hydrophobicity and a parameter characterizin

B. O. Kerbikov

It is shown that the onset of the color superconducting phase occurs in the BCS-BE crossover region.

Ashoke Sen

We propose a field theory for describing the tachyon on a brane-antibrane system near the minimum of the potential. This field theory realizes two known properties of the tachyon effective action: 1) absence of plane-wave solutions around the minimum, and 2) exponential fall off of the pressure at late time as the tachyon field evolves from any spatially hom

L. Andrianopoli, R. D&#39;Auria, S. Ferrara, M. A. Lledo

It is shown that the super Higgs mechanism that occurs in a wide class of models with vanishing cosmological constant (at the classical level) is obtained by the gauging of a flat group which must be an electric subgroup of the duality group. If the residual massive gravitinos which occur in the partial supersymmetry breaking are BPS saturated, then the flat

Santo Fortunato

The properties of the pure-site clusters of spin models, i.e. the clusters which are obtained by joining nearest-neighbour spins of the same sign, are here investigated. In the Ising model in two dimensions it is known that such clusters undergo a percolation transition exactly at the critical point. We show that this result is valid for a wide class of bidi

Maciej Dunajski, Paul Tod

We present two constructions of new solutions to the dispersionless KP (dKP) equation arising from the first two Painlevé transcendents. The first construction is a hodograph transformation based on Einstein--Weyl geometry, the generalised Nahm&#39;s equation and the isomonodromy problem. The second construction, motivated by the first, is a direct character

M. Matlak, J. Aksamit, B. Grabiec, W. Nolting

We formulate the Hubbard model for the simple cubic lattice in the representation of interacting dimers applying the exact solution of the dimer problem. By eliminating from the considerations unoccupied dimer energy levels in the large U limit (it is the only assumption) we analytically derive the Hubbard Hamiltonian for the dimer (analogous to the well-kno

Martin Kruczenski, Robert C. Myers, Amanda W. Peet

We construct supergravity solutions corresponding to space-like branes in string theory. Our approach is to apply the usual solution generating techniques to an appropriate time-dependent solution of the eleven dimensional vacuum Einstein equations. In this way all SDp-brane solutions are obtained, as well as the NS and M-theory space branes. Bound states of

Frank E. Close, Nils A. Tornqvist

We show that two nonets and a glueball provide a consistent description of data on scalar mesons below 1.7 GeV. Above 1 GeV the states form a conventional (q bar q) nonet mixed with the glueball of lattice QCD. Below 1 GeV the states also form a nonet, as implied by the attractive forces of QCD, but of more complicated nature. Near the center they are 4 quar

Boris Ischi

We consider the description of two independent quantum systems by a complete atomistic ortho-lattice (cao-lattice) L. It is known that since the two systems are independent, no Hilbert space description is possible, i.e. $L\ne P(H)$, the lattice of closed subspaces of a Hilbert space (theorem 1). We impose five conditions on L. Four of them are shown to be p

F. Spineanu, M. Vlad

The space-uniform amplitude envelope of the Ion Temperature Gradient driven turbulence is unstable to small perturbations and evolves to nonuniform, soliton-like modulated profiles. The induced poloidal asymmetry of the transport fluxes can generate spontaneous poloidal spin-up of the tokamak plasma.

E. Elizalde, A. C. Tort

We discuss some controverted aspects of the evaluation of the thermal energy of a scalar field in a one-dimensional compact space. The calculations are carried out using a generalised zeta function approach.