January 2002 arXiv papers — page 14

L. Piro, D. A. Frail, J. Gorosabel, G. Garmire

The gamma-ray burst GRB000210 had the highest gamma-ray peak flux of any event localized by BeppoSAX as yet but it did not have a detected optical afterglow. It is therefore one of the events recently classified as dark GRBs or GHOST (GRB Hiding Optical Source Transient), whose origin is still unclear. Chandra observations allowed us to localize this GRB wit

Soonkeon Nam, Sang-Jin Sin

We consider condensation of localized closed string tachyons by examining the recent proposal of Harvey, Kutasov, Martinec, and Moore. We first observe that the $g_{\rm cl}$ defined by HKMM does not reflect the space-time supersymmetry when the model has the SUSY. Especially for ${\bf C}^2/{\bf Z}_N$ models, $g_{\rm cl}$ defined by them is highly peaked alon

C. D. Froggatt, H. B. Nielsen, Y. Takanishi

We present a modification of our previous family replicated gauge group model, which now generates the Large Mixing Angle MSW solution rather than the experimentally disfavoured Small Mixing Angle MSW solution to the solar neutrino oscillation problem. The model is based on each family of quarks and leptons having its own set of gauge fields, each containing

Bin Zhang, C. M. Ko, Bao-An Li, Zi-Wei Lin

Using A Multi-Phase Transport (AMPT) model, we study J/psi production from interactions between charm and anti-charm quarks in initial parton phase and between D and Dbar mesons in final hadron phase of relativistic heavy ion collisions at the Relativistic Heavy Ion Collider (RHIC). Including also the inverse reactions of J/psi absorption by gluons and light

Tadafumi Ohsaku

We solve numerically various types of the gap equations developed in the relativistic BCS and generalized BCS framework, presented in part I of this paper. We apply the method for, not only the usual solid metal but also other physical systems, by using homogeneous fermion gas approximation. We examine the relativistic effects on the thermal properties and t

Zhi-zhong Xing

We present the generic formulas to calculate the ratios of neutrino masses and the Majorana phases of CP violation from the neutrino mass matrix with two independent vanishing entries in the flavor basis where the charged lepton mass matrix is diagonal. An order-of-magnitude illustration is given for seven experimentally acceptable textures of the neutrino m

Naoki Sasakura

We obtain and study an analytical solution of a de-Sitter thick domain wall in five-dimensional Einstein gravity interacting with a scalar field. The scalar field potential is axion-like, V(phi)=a+b cos(phi) with constants a,b satisfying -3b<5a<3b, and the solution is expressed in terms of elliptic functions.

Grigori Litvinov, Viktor Maslov, Grigori Shpiz

In the framework of a model for quantum computer media, a nondigital implementation of the arithmetic of the real numbers is described. For this model, an elementary storage &#34;cell&#34; is an ensemble of qubits (quantum bits). It is found that to store an arbitrary real number it is sufficient to use four of these ensembles and the arithmetic operations c

Erika Andersson, Stephen M. Barnett, Claire R. Gilson, Kieran Hunter

We present the optimal measurement strategy for distinguishing between three quantum states exhibiting a mirror symmetry. The three states live in a two-dimensional Hilbert space, and are thus overcomplete. By mirror symmetry we understand that the transformation {|+> -> |+>, |-> -> -|->} leaves the set of states invariant. The obtained measurement strategy

Jonathan Barrett

We consider situations in which i) Alice wishes to send quantum information to Bob via a noisy quantum channel, ii) Alice has a classical description of the states she wishes to send and iii) Alice can make use of a finite amount of noiseless classical information. After setting up the problem in general, we focus attention on one specific scenario in which

K. M. Fonseca-Romero, M. C. Nemes, J. G. Peixoto de Faria, A. F. R. de Toledo Piza

We construct a class of systems for which quantum dynamics can be expanded around a mean field approximation with essentially classical content. The modulus of the quantum overlap of mean field states naturally introduces a classical distance between classical phase points. Using this fact we analytically show that the time rate of change (trc) of two neighb

Anna Felicetti, Stefano Mancini, Paolo Tombesi

We introduce a Werner-like mixture [R. F. Werner, Phys. Rev. A {\bf 40}, 4277 (1989)] by considering two correlated but different degrees of freedom, one with discrete variables and the other with continuous variables. We evaluate the mixedness of this state, and its degree of entanglement establishing its usefulness for quantum information processing like q

Sangchul Oh

We study numerically the dynamics of two-qubit gates with superconducting charge qubits. The exact ratio of $E_J$ to $E_L$ and the corresponding operation time are calculated in order to implement two-qubit gates. We investigate the effect of finite rise/fall times of pulses in realization of two-qubit gates. It is found that the error in implementing two-qu

Masato Koashi, Nobuyuki Imoto

Consider a situation in which a quantum system is secretly prepared in a state chosen from the known set of states. We present a principle that gives a definite distinction between the operations that preserve the states of the system and those that disturb the states. The principle is derived by alternately applying a fundamental property of classical signa

M. S. Hussein, C. P. Malta, M. P. Pato, A. P. B. Tufaile

We derive an exact general formalism that expresses the eigenvector and the eigenvalue dynamics as a set of coupled equations of motion in terms of the matrix elements dynamics. Combined with an appropriate model Hamiltonian, these equations are used to investigate the effect of the presence of a discrete symmetry in the level curvature distribution. An expl

M. Y. Su, S. Carter, M. S. Sherwin, A. Huntington

An undoped double quantum well (DQW) was driven with a terahertz (THz) electric field of frequency ω_{THz} polarized in the growth direction, while simultaneously illuminated with a near-infrared (NIR) laser at frequency ω_{NIR}. The intensity of NIR upconverted sidebands ω_{sideband}=ω_{NIR} + ω_{THz} was maximized when a dc voltage applied in the growth di

Alexander A. Vlasov

A simple example of especially constructed potential barrier enables to show analytically (not numerically) the existence of tunneling effect for a Sommerfeld particle.

R. Schiavilla, V. R. Pandharipande

What range of momentum components in the deuteron wave function are available e d elastic scattering data sensitive to ? This question is addressed within the context of a model calculation of the deuteron form factors, based on realistic interactions and currents. It is shown that the data on the $A(q)$, $B(q)$, and $T_{20}(q)$ observables at $q \leq 6$ fm$

V. F. Dmitriev, I. B. Khriplovich

We discuss the present state of the theory of nuclear anapole moments.

Sourav Sarkar, Jan-e Alam, T. Hatsuda

The medium modification of vector meson properties in hot/dense hadronic matter and its role in explaining the CERES/NA45 dilepton data at different centralities are discussed.

K. Hagino

We present results of coupled-channels calculations which are performed to understand the role of vibrational excitations of the daughter nucleus in proton emission decay of spherical nuclei. It is shown that the experimental decay rates from the 2$d_{3/2}$, 3$s_{1/2}$ and 1$h_{11/2}$ states in proton emitting nuclei $^{160,161}$Re are reproduced simultaneou

G. Van Buren

The STAR Experiment at RHIC is capable of a wide variety of measurements of the production of strange hadrons in nuclear collisions. Measurements of the relative production of strange baryons, antibaryons, and kaons can shed light on the baryon densities achieved in these collisions and on the validity of models for production yields. We will present here pr

C. Jayaprakash, F. Hayot

We derive for the Navier-Stokes equation an exact equation satisfied by the dissipation rate correlation function. In the equal time limit, in the inertial range, for the homogeneous, isotropic state of fully-developed turbulence, we show that the correlation is characterized by two exponents, one of which depends on the sixth-order static structure function

E. M. Shahverdiev, S. Sivaprakasam, K. A. Shore

We report an analysis of synchronization between two unidirectionally coupled chaotic external cavity master/slave semiconductor lasers with two characteristic delay times, where the delay time in the coupling is different from the delay time in the coupled systems themselves. We demonstrate for the first time that parameter mismatches in photon decay rates

Zai-Qiao Bai, Wei-Mou Zheng

Symbolic dynamics for homoclinic orbits in the two-dimensional symmetric map, $x_{n+1}+cx_{n}+x_{n-1}=3x_{n}^3$, is discussed. Above a critical $c^{\ast}$, the system exhibits a fully-developed horse-shoe so that its global behavior is described by a complete ternary symbolic dynamics. The relative location of homoclinic orbits is determined by their sequenc

Sonke Hansen, Gunther Uhlmann

We show that knowing the Dirichlet-to-Neumann map (DN) associated to the equations of elastodynamics with residual stress we can determine the lens relations of presssure and shear waves. We derive several consequences of this for the inverse problem of determining the residual stress and the Lamé parameters from the DN map.

V. Dragovic, B. Gajic

A four-dimensional integrable rigid-body system is considered and it is shown that it represents two twisted three-dimensional Lagrange tops. A polynomial Lax representation, which doesn&#39;t fit neither in Dubrovin&#39;s nor in Adler - van Moerbeke&#39;s picture is presented. The algebro-geometric integration procedure is based on deep facts from the geome

Daniel R. Replogle

Let $K$ be an algebraic number field with ring of integers $\Cal{O}_{K}$, $p>2$ be a rational prime and $G$ be the cyclic group of order $p $. Let $Λ$ denote the order $\Cal{O}_{K}[G].$ Let $Cl(Λ)$ denote the locally free class group of $Λ$ and $D(Λ)$ the kernel group, the subgroup of $Cl(Λ)$ consisting of classes that become trivial upon extension of scalar

Marc Conrad, Daniel R. Replogle

We say a tame Galois field extension $L/K$ with Galois group $G$ has trivial Galois module structure if the rings of integers have the property that $\Cal{O}_{L}$ is a free $\Cal{O}_{K}[G]$-module. The work of Greither, Replogle, Rubin, and Srivastav shows that for each algebraic number field other than the rational numbers there will exist infinitely many p

Jesse Ratzkin

Complete constant positive scalar curvature metrics on S^n - {p_1, ..., p_k} admit a definite asymptotic structure; i.e. the metric is asymptotic to a specific S^{n-1}-invariant metric near the puncture points. This allows one to glue together two such metrics near their puncture points, provided the asymptotic structures match, and create a metric whose sca

Benson Farb, Peter Shalen

We prove that any real-analytic, volume-preserving action of a lattice $Γ$ in a simple Lie group with $\Qrank(Γ)\geq 7$ on a closed 4-manifold of nonzero Euler characteristic factors through a finite group action.

Steven R. Bell

We show that the classical kernel and domain functions associated to an n-connected domain in the plane are all given by rational combinations of three or fewer holomorphic functions of one complex variable. We characterize those domains for which the classical functions are given by rational combinations of only two or fewer functions of one complex variabl

Christian Bohr

In this paper, we exploit a subtle indeterminacy in the definition of the spherical Kervaire-Milnor invariant which was discovered by R. Stong to construct non-spin 4-manifolds with even intersection form and prescribed signature.

Monika Dörfler, Hans G. Feichtinger, Karlheinz Gröchenig

The classical criterion for compactness in Banach spaces of functions can be reformulated into a simple tightness condition in the time-frequency domain. This description preserves more explicitly the symmetry between time and frequency than the classical conditions. The result is first stated and proved for L^2(R^d), and then generalized to coorbit spaces.

P. M. G. Manchon

We find families of prime knot diagrams with arbitrary extreme coefficients in their Jones polynomials. Some graph theory is presented in connection with this problem, generalizing ideas by Yongju Bae and Morton and giving a positive answer to a question in their paper.

Gueo Grantcharov, George Papadopoulos, Yat Sun Poon

KT-geometry is the geometry of a Hermitian connection whose torsion is a 3-form. HKT-geometry is the geometry of a hyper-Hermitian connection whose torsion is a 3-form. We identify non-trivial conditions for a reduction theory for these types of geometry.

Jean-Yves Welschinger

In this paper, we give a complete description of the deformation classes of real structures on minimal ruled surfaces. In particular, we show that these classes are determined by the topology of the real structure, which means that real minimal ruled surfaces are quasi-simple. As an intermediate result, we obtain the classification, up to conjugation, of rea

Selman Akbulut

We discuss some consequences Fintushel-Stern `knot surgery&#39; operation on 4-manifolds coming from its handlebody description. We give some generalizations of this operation and give a counterexample to their conjecture.

Zhujun Zheng, Keping Lu, Luo Xuebo

Based on the concepts of a generalized critical point and the corresponding generalized P.S. condition introduced by Duong Minh Duc[1], we have proved a new $Z_2$ index theorem and get a result on multiplicity of generalized critical points. Using the result and a quite standard variational method, it is found that the equation $$ -Δ_{H^n} u=|u|^{p-1} u ~ x\

A. Giacomini

We study the lower semicontinuity for functionals defined on compact sets in R^2 with a finite number of connected components and finite length which depend on their normal vector. We apply the result to the study of quasi-static growth of brittle fractures in linearly elastic inhomogeneous and anisotropic bodies.

Michael Mueger

We consider certain categorical structures that are implicit in subfactor theory. Making the connection between subfactor theory (at finite index) and category theory explicit sheds light on both subjects. Furthermore, it allows various generalizations of these structures, e.g. to arbitrary ground fields, and the proof of new results about topological invari

Leonid G. Fel

A conformal partition function ${\cal P}_n^m(s)$, which arose in the theory of Diophantine equations supplemented with additional restrictions, is concerned with {\it self-dual symmetric polynomials} -- reciprocal ${\sf R}^{\{m\}}_ {S_n}$ and skew-reciprocal ${\sf S}^{\{m\}}_{S_n}$ algebraic polynomials based on the polynomial invariants of the symmetric gro

Sandro Manfredini, Roberto Pignatelli

This paper is devoted to a very classical problem that can be summarized as follows: let S be a non singular compact complex surface, f:S --> P^2 a finite morphism having simple branching, B the branch curve: to what extent does B determine f? The problem was first studied by Chisini who proved that B determines S and f, assuming B to have only nodes and cus

G. Barnich, F. Brandt, M. Grigoriev

The formulation of Seiberg-Witten maps from the point of view of consistent deformations of gauge theories in the context of the Batalin-Vilkovisky antifield formalism is reviewed. Some additional remarks on noncommutative Yang-Mills theory are made.

J. M. Camino, A. V. Ramallo

We study some configurations of brane probes which are partially wrapped on spheres transverse to a stack of non-threshold bound states. The latter are represented by the corresponding supergravity background. Two cases are studied: D(10-p)-branes in the background of (D(p-2), Dp) bound states and D(8-p)-branes in the (NS5, Dp) geometry. By using suitable fl

Poul Olesen

It has been proposed some time ago that the large $N-$limit can be understood as a ``classical limit&#39;&#39;, where commutators in some sense approach the corresponding Poisson brackets. We discuss this in the light of some recent numerical results for an SU(N) gauge model, which do not agree with this ``classicality&#39;&#39; of the large N-limit. The wor

N. Kitanine, J. M. Maillet, N. A. Slavnov, V. Terras

Using a multiple integral representation for the correlation functions, we compute the emptiness formation probability of the XXZ spin-1/2 Heisenberg chain at anisotropy Delta=1/2. We prove it is expressed in term of the number of alternating sign matrices.

C. Barbachoux, A. Fabbri

We numerically integrate the semiclassical equations of motion for spherically symmetric Einstein-Maxwell theory with a dilaton coupled scalar field and look for zero temperature configurations. The solution we find is studied in detail close to the horizon and comparison is made with the corresponding one in the minimally coupled case.

Ning Wu, Zhan Xu, Da-Hua Zhang

Differential geometric formulation of quantum gauge theory of gravity is studied in this paper. The quantum gauge theory of gravity which is proposed in the references hep-th/0109145 and hep-th/0112062 is formulated completely in the framework of traditional quantum field theory. In order to study the relationship between quantum gauge theory of gravity and

D. Talalaev

The elliptic Gaudin model was obtained as the Hitchin system on an elliptic curve with two fixed points. In the present paper the algebraic-geometrical structure of the system with two fixed points is clarified. We identify this system with poles dynamics of the finite gap solutions of Davey-Stewartson equation. The solutions of this system in terms of theta

Stanley J. Brodsky

Spin effects in exclusive and inclusive reactions provide an essential new dimension for testing QCD and unraveling hadron structure. Remarkable new experiments from SLAC, HERMES (DESY), and the Jefferson Laboratory present many challenges to theory, including measurements at HERMES and SMC of the single spin asymmetries in pion electroproduction, where the

S. Khlebnikov

The final stage of Bose-Einstein condensation in a large volume occurs through coarsening--growth of individual correlated patches. We present analytical arguments and numerical evidence that in the momentum space this growth corresponds to strong turbulence of the particle number, with a turbulent cascade towards the infrared and the power law $n(k) \propto

C. P. Burgess, V. Di Clemente, J. R. Espinosa

For a light enough Higgs boson, the effective potential of the Standard Model develops a dangerous instability at some high energy scale, Lambda, signalling the need for new physics below that scale. On the other hand, a typical low-energy remnant of new physics at some heavy scale, M, is the presence of effective non-renormalizable operators (NROs), suppres

Diego F. Torres

We study the emissivity properties of a geometrically thin, optically thick, steady accretion disc about a static boson star. Starting from a numerical computation of the metric potentials and the rotational velocities of the particles in the vicinity of the compact object, we obtain the power per unit area, the temperature of the disc, and the spectrum of t

Clive Field, Gholam Mazaheri, Johnny S. T. Ng

The focusing strength of plasma lenses used with high energy electron or positron beams can give rise to synchrotron radiation with critical energies in the MeV range. A method is described for measuring the characteristic energy of this radiation as a way of monitoring the strength of the focus. The principle has been implemented in a plasma lens experiment

K. Piotrzkowski

Two-photon events at the LHC are characterized by the protons scattered at very small angles and the particles centrally produced via the photon-photon fusion. To select these events from the huge samples of generic pp interactions a detection of the scattered protons, or tagging two-photon interactions is necessary. It requires installation of the high-reso

Laurence Littenberg

Recent results on rare kaon decays are reviewed and prospects for future experiments are discussed.

Irina Dymnikova

We outline the class of globally regular spherically symmetric solutions to the minimally coupled GR equations asymptotically de Sitter in the origin and asymptotically Schwarzschild at infinity. A source term connects smoothly de Sitter vacuum at the regular center with Minkowski vacuum at infinity and corresponds to anisotropic spherically symmetric vacuum

M. H. van Emden

To analyse the significance of the digits used for interval bounds, we clarify the philosophical presuppositions of various interval notations. We use information theory to determine the information content of the last digit of the numeral used to denote the interval&#39;s bounds. This leads to the notion of efficiency of a decimal digit: the actual value as

Bruno Caprile, Cesare Furlanello, Stefano Merler

The dynamical evolution of weights in the Adaboost algorithm contains useful information about the role that the associated data points play in the built of the Adaboost model. In particular, the dynamics induces a bipartition of the data set into two (easy/hard) classes. Easy points are ininfluential in the making of the model, while the varying relevance o

T. Senthil, O. Motrunich

We construct explicit examples of microscopic models that stabilize a variety of fractionalized phases of strongly correlated systems in spatial dimension bigger than one, and in zero external magnetic field. These include models of charge fractionalization in boson-only systems, and various kinds of spin-charge separation in electronic systems. We determine

Leonid G. Fel

The Keller theorem in the problem of effective conductivity in anisotropic two-dimensional (2D) many-component composites makes it possible to establish a simple inequality $σ_{\sf is}^e(σ^{-1}_i)\cdot σ_{\sf is}^e(σ_k)> 1$ for the isotropic part $σ_{\sf is}^e(σ_k)$ of the 2-nd rank symmetric tensor ${\widehat σ}_{i,j}^e$ of effective conductivity.

A. Carpio, L. L. Bonilla, A. Luzon

Pinning and depinning of wave fronts are ubiquitous features of spatially discrete systems describing a host of phenomena in physics, biology, etc. A large class of discrete systems is described by overdamped chains of nonlinear oscillators with nearest-neighbor coupling and subject to random external forces. The presence of weak randomness shrinks the pinni

A. Carpio, L. L. Bonilla

Pinning and depinning of wavefronts are ubiquitous features of spatially discrete systems describing a host of phenomena in physics, biology, etc. A large class of discrete systems is described by overdamped chains of nonlinear oscillators with nearest-neighbor coupling and controlled by constant external forces. A theory of the depinning transition for thes

A. Carpio, L. L. Bonilla, G. Dell&#39;Acqua

An analysis of wavefront motion in weakly coupled doped semiconductor superlattices is presented. If a dimensionless doping is sufficiently large, the superlattice behaves as a discrete system presenting front propagation failure and the wavefronts can be described near the threshold currents $J_i$ ($i=1,2$) at which they depin and move. The wavefront veloci

Yunkyu Bang, I. Martin, A. V. Balatsky

We propose the multiband extension of the spin-fermion model to address the superconducting d-wave pairing due to magnetic interaction near critical point. We solve the unrestricted gap equation with a general d-wave symmetry gap and find that divergent magnetic correlation length $ξ$ leads to the very unharmonic shape of the gap function with shallow gap re

L. L. Bonilla, R. Escobedo, F. J. Higuera

The Kroemer model for the Gunn effect in a circular geometry (Corbino disks) has been numerically solved. The results have been interpreted by means of asymptotic calculations. Above a certain onset dc voltage bias, axisymmetric pulses of the electric field are periodically shed by an inner circular cathode. These pulses decay as they move towards the outer

P. Grassberger

We describe a general strategy for sampling configurations from a given distribution, NOT based on the standard Metropolis (Markov chain) strategy. It uses the fact that nontrivial problems in statistical physics are high dimensional and often close to Markovian. Therefore, configurations are built up in many, usually biased, steps. Due to the bias, each con

Krisztian Kohary

1. Introduction 2. Molecular dynamics simulation of amorphous carbon structures 3. Atomistic simulation of the bombardment process during the BEN phase of diamond CVD 4. Growth of amorphous silicon 5. One-dimensional hopping in disordered organic solids

Trinh Xuan Hoang, Marek Cieplak, Jayanth R. Banavar, Amos Maritan

We use LINUS, a procedure developed by Srinivasan and Rose, to provide a physical interpretation of and to predict the secondary structures of proteins. The secondary structure type at a given site is identified by the largest conformational bias during short time simulations. We examine the rate of successful prediction as a function of temperature and the

Massimo Campostrini, Martin Hasenbusch, Andrea Pelissetto, Paolo Rossi

We discuss some recent determinations of the equation of state for the XY and the Heisenberg universality class.

Gunnar Pruessner, Henrik Jeldtoft Jensen

We investigate the scaling behavior of the cluster size distribution in the Drossel-Schwabl Forest Fire model (DS-FFM) by means of large scale numerical simulations, partly on (massively) parallel machines. It turns out that simple scaling is clearly violated, as already pointed out by Grassberger [P. Grassberger, J. Phys. A: Math. Gen. 26, 2081 (1993)], but

T. Fukui, H. Emura, H. Yamada

A Dirac fermion model with random axial-vector potential is proposed. At a special strength of randomness, the symmetry of the action is enhanced, which is due to the gauge symmetry à la Nishimori. Some exact scaling exponents of single-particle Green functions are computed. The relationship with the XY gauge glass model is discussed.

M. Mazars, J-M. Caillol, J. -J. Weis, D. Levesque

Using the specific model of a system of like charged ions confined between two planar like charged surfaces, we compare the predictions for the energy and density profile of four simulation methods available to treat the long range Coulomb interactions in systems periodic in two directions but bound in the third one. Monte Carlo simulations demonstrate unamb

Alexander Khaetskii, Daniel Loss, Leonid Glazman

We study the decoherence of a single electron spin in an isolated quantum dot induced by hyperfine interaction with nuclei for times smaller than the nuclear spin relaxation time. The decay is caused by the spatial variation of the electron envelope wave function within the dot, leading to a non-uniform hyperfine coupling. We evaluate the spin correlation fu

M. Lange, M. J. Van Bael, L. Van Look, S. Raedts

The pinning properties of type-II superconductors can be efficiently controlled by using laterally nanostructured ferromagnet / superconductor bilayers. This will be illustrated by studying the flux pinning in thin superconducting Pb films which are deposited on top of two types of magnetic nanostructures with out-of-plane magnetisation: (i) an array of dots

Igor Vilfan, Thierry Deutsch, Frederic Lancon, Gilles Renaud

Grazing-incidence X-ray diffraction data are combined with energy-minimization calculations to analyse the atomic structure of the Al-rich (3sqrt{3} x 3sqrt{3})R 30 deg reconstructed surface of sapphire alpha-Al_2O_3(0001). The experiments on the BM32 beamline of the ESRF provide the non-integer-order diffraction intensities and, after Fourier transform, an

T. Asano, H. Nojiri, Y. Inagaki, Y. Ajiro

Considering experimental results obtained on three prototype compounds, TMMC, CsCoCl3 (or CsCoBr3) and Cu Benzoate, we discuss the importance of non-linear excitations in the physics of quantum (and classical) antiferromagnetic spin chains.

Takeji Kubo, Takao Goto, Takeshi Koshiba, Keiji Takeda

The 55Mn NMR in oriented powder Mn12Ac has been investigated at 1.4-2.0 K in zero field and with external fields along the c-axis. Three kinds of 55Mn NMR composed of five-fold quadrupole-split lines for I=5/2 nuclei have been interpreted to arise from Mn4+ ion, and two crystallographically-inequivalent Mn3+ ions, respectively. It is found that the isotropic

G. Lamura, J. C. Villegier, A. Gauzzi, J. Le Cochec

Using a single coil mutual inductance technique, we measure the low temperature dependence of the magnetic penetration depth in superconducting NbN films prepared with similar critical temperatures around 16 K but with different microstructures. Only (100) epitaxial and weakly granular (100) textured films display the characteristic exponential dependence of

Ryusuke Ikeda

This is a Comment on an experimental paper by Zhukov et al. on the issue of a lower critical point, seen only in YBCO clean samples, of the first order transition line implying a vortex liquid-freezing. An explanation with a firm theoretical basis of the strange doping dependence of the lower critical point is presented.

C. C. Ling, W. K. Mui, C. H. Lam, C. D. Beling

Positron lifetime, Photoluminescence and Hall measurements were performed to study undoped p-type gallium antimonide materials. A 314ps lifetime component, attributed to $V_{Ga}$ related defect, was identified in the positron lifetime measurement. In the PL measurement, a $778meV$ and a $797meV$ peaks were observed. Isochronal annealing studies were performe

E. Arrigoni, M. G. Zacher, T. Eckl, W. Hanke

We propose a phenomenological model, comprising a microscopic \sof model plus the on-site Hubbard interaction $U$ (``projected \sof model&#39;&#39;) to understand the interrelation between the d-wave-gap modulation observed by recent angle-resolved photoemission experiments in the insulating antiferromagnet Ca$_2$CuO$_2$Cl$_2$ and the d-wave gap of high-Tc s

Slawomir Piatek, Carlton Pryor, Taft E. Armandroff, Edward W. Olszewski

This article studies the structure of the Draco dwarf spheroidal galaxy with an emphasis on the question of whether the spatial distribution of its stars has been affected by the tidal interaction with the Milky Way, using R- and V-band CCD photometry for eleven fields. The article reports coordinates for the center, a position angle of the major axis, and t

Roger A. Chevalier

The Crab Nebula is likely to be expanding into freely expanding supernova ejecta, although the energy in the ejecta may be less than is typical for a Type II supernova. Pulsar nebulae much younger than the Crab have not been found and could have different properties. The search for such nebulae through ultraviolet/optical line emission in core collapse super

R. Launhardt, R. Zylka, P. G. Mezger

We analyse IRAS and COBE DIRBE data at wavelengths between 2.2 and 240 mu of the central 500pc of the Galaxy and derive the large-scale distribution of stars and interstellar matter in the Nuclear Bulge. Models of the Galactic Disk and Bulge are developed in order to correctly decompose the total surface brightness maps and to apply proper extinction correct

Rodger I. Thompson, Bradford A. Smith, J. Jeff Hester

M16=NGC 6611, the Eagle Nebula, is a well studied region of star formation and the source of a widely recognized Hubble Space Telescope (HST) image. High spatial resolution infrared observations with the Near Infrared Camera and Multi-Object Spectrometer (NICMOS) on HST reveal the detailed morphology of two embedded star formation regions that are heavily ob

M. Landgraf, J. -C. Liou, H. A. Zook, E. Grün

The measurements of cosmic interplanetary dust by the instruments on board the Pioneer 10 and 11 spacecraft contain the dynamical signature of dust generated by Edgeworth-Kuiper Belt objects, as well as short period Oort Cloud comets and short period Jupiter family comets. While the dust concentration detected between Jupiter and Saturn is mainly due to the

A. Moretti, D. Lazzati, S. Campana, G. Tagliaferri

Chandra deep fields represent the deepest look at the X-ray sky. We analyzed the Chandra Deep Field South (CDFS) with the aid of a dedicated wavelet-based algorithm. Here we present a detailed description of the procedures used to analyze this field, tested and verified by means of extensive simulations. We show that we can safely reconstruct the LogN-Log S

A. Misiriotis, S. Bianchi

We have used a Monte Carlo radiative transfer code to produce edge-on images of dusty galactic disks, allowing a fraction of the dust to be distributed in clumps. Synthetic images of edge-on galaxies have been constructed for different amounts of dust, distributions of clumps and fractions of dust in clumps, following the formalism of Bianchi et al. (1999).

P. R. McCullough, R. R. Chen

The microwave spectral energy distribution of the dusty, diffuse H II region LPH 201.663+1.643 has been interpreted by others as tentative evidence for microwave emission from spinning dust grains. We present an alternative interpretation for that particular object; specifically, that an ultracompact H II region embedded within the dust cloud would explain t

Davide Lazzati, Rosalba Perna, Gabriele Ghisellini

Despite great observational and theoretical effort, the burst progenitor is still a mysterious object. It is generally accepted that one of the best ways to unveil its nature is the study of the properties of the close environment in which the explosion takes place. We discuss the potentiality and feasibility of time resolved X-ray spectroscopy, focusing on

Lionel Siess, Mario Livio, John Lattanzio

(abridge version) The evolution of population III stars (Z=0) is followed from the pre-main sequence phase up to the AGB phase for intermediate-mass stars and up to C ignition in more massive stars...We find that, thanks to the development of mixing episodes (carbon injections) at the beginning of the AGB phase, the carbon abundance of the 1, 1.5, 2, 3, 4 an

T. Rauch

We present a new grid (solar and halo abundance ratios) of state-of-the-art fully line-blanketed NLTE model atmospheres which covers the parameter range of central stars of planetary nebulae. The grid is available at the WWW.

V. Buat, A. Boselli, G. Gavazzi, C. Bonfanti

We study the star formation rate and dust extinction properties of a sample of nearby star forming galaxies as derived from Halpha and UV (2000 A) observations and we compare them to those of a sample of starburst galaxies. The dust extinction in Halpha is estimated from the Balmer decrement and the extinction in UV using the FIR to UV flux ratio or the atte

K. Werner, S. Dreizler, L. Koesterke, J. W. Kruk

FUSE high resolution spectra of two PG1159 type central stars (K1-16 and NGC 7094) have revealed an unexpected iron deficiency of at least 1 or 2 dex (Miksa et al. 2002). Here we present early results of FUSE spectroscopy of the CSPN Abell 78. It is shown that iron is strongly deficient in this star, too.

Mario Hamuy, Philip A. Pinto

We present evidence for a correlation between expansion velocities of the ejecta of Type II plateau supernovae and their bolometric luminosities during the plateau phase. This correlation permits one to standardize the candles and decrease the scatter in the Hubble diagram from ~1 mag to a level of 0.4 and 0.3 mag in the V and I bands, respectively. When we

V. Charmandaris, G. J. Stacey, G. Gull

We present new 37.7 micron far-infrared imaging of the infrared luminous (L_IR ~ 5.16x10^{11} L_sun) interacting galaxy Arp299 (= IC694 + NGC3690). We show that the 38 micron flux, like the 60 and 100 micron emission, traces the luminosity of star forming galaxies, but at considerably higher spatial resolution. Our data establish that the major star formatio

Tomonori Totani, Tsutomu T. Takeuchi

We give an explanation for the origin of various properties observed in local infrared galaxies, and make predictions for galaxy counts and cosmic background radiation (CBR), by a new model extended from that for optical/near-infrared galaxies. Important new characteristics of this study are that (1) mass scale dependence of dust extinction is introduced bas

P. Zuccon, B. Bertucci, B. Alpat, R. Battiston

Substantial fluxes of protons and leptons with energies below the geomagnetic cutoff have been measured by the AMS experiment at altitudes of 370-390 Km, in the latitude interval +/- 51.7 degrees. The production mechanisms of the observed trapped fluxes are investigated in detail by means of the FLUKA Monte Carlo simulation code. All known processes involved