February 2002 arXiv papers — page 15

Bedangadas Mohanty

Results from the photon multiplicity measurements using a fine granularity preshower photon multiplicity detector (PMD) at CERN SPS are discussed. These include study of pseudo-rapidity distributions of photons, scaling of photon multiplicity with number of participating nucleons, centrality dependence of mean transverse momentum of photons, event-by-event f

J. Mas, M. Perez-Victoria, C. Seijas

Using differential renormalization, we calculate the complete two-point function of the background gauge superfield in pure N=1 Supersymmetric Yang-Mills theory to two loops. Ultraviolet and (off-shell) infrared divergences are renormalized in position and momentum space respectively. This allows us to reobtain the beta function from the dependence on the ul

F. Finkel, D. Gomez-Ullate, A. Gonzalez-Lopez, M. A. Rodriguez

The B_N hyperbolic Sutherland spin model is expressed in terms of a suitable set of commuting Dunkl operators. This fact is exploited to derive a complete family of commuting integrals of motion of the model, thus establishing its integrability. The Dunkl operators are shown to possess a common flag of invariant finite-dimensional linear spaces of smooth sca

N. V. Priezjev, Robert A. Pelcovits

We study the coarsening dynamics of two and three dimensional biaxial nematic liquid crystals, using Langevin dynamics. Unlike previous work, we use a model with no a priori relationship among the three elastic constants associated with director deformations. We find a rich variety of coarsening behavior, including the simulataneous decay of nearly equal pop

Anders S. Sorensen, Klaus Molmer

We propose a method to produce entangled spin squeezed states of a large number of atoms inside an optical cavity. By illuminating the atoms with bichromatic light, the coupling to the cavity induces pairwise exchange of excitations which entangles the atoms. Unlike most proposals for entangling atoms by cavity QED, our proposal does not require the strong c

Lara Faoro, Jens Siewert, Rosario Fazio

Non-Abelian geometric phases can be generated and detected in certain superconducting nanocircuits. Here we consider an example where the holonomies are related to the adiabatic charge dynamics of the Josephson network. We demonstrate that such a device can be applied both for adiabatic charge pumping and as an implementation of a quantum computer.

A. D. Dolgov

Cosmological implications of neutrinos are reviewed. The following subjects are discussed at a different level of scrutiny: cosmological limits on neutrino mass, neutrinos and primordial nucleosynthesis, cosmological constraints on unstable neutrinos, lepton asymmetry of the universe, impact of neutrinos on cosmic microwave radiation, neutrinos and the large

Gianluca Stefanucci, Michele Cini

As a prototype model of antiferromagnetism, we propose a repulsive Hubbard Hamiltonian defined on a graph $Ł={\cal A}\cup{\cal B}$ with ${\cal A}\cap {\cal B}=\emptyset$ and bonds connecting any element of ${\cal A}$ with all the elements of ${\cal B}$. Since all the hopping matrix elements associated with each bond are equal, the model is invariant under an

Pierre Bieliavsky, Martin Bordemann, Simone Gutt, Stefan Waldmann

In this paper, we describe all traces for the BCH star-product on the dual of a Lie algebra. First we show by an elementary argument that the BCH as well as the Kontsevich star-product are strongly closed if and only if the Lie algebra is unimodular. In a next step we show that the traces of the BCH star-product are given by the $\ad$-invariant functionals.

J. Hove, S. Mo, A. Sudbo

We have computed the effective interaction between vortices in the Ginzburg-Landau model from large-scale Monte-Carlo simulations, taking thermal fluctuations of matter fields and gauge fields fully into account close to the critical temperature. We find a change, in the form of a crossover, from attractive to repulsive effective vortex interactions in an in

W. Behr, N. G. Deshpande, G. Duplancic, P. Schupp

On noncommutative spacetime, the Standard Model allows new, usually Standard Model forbidden, triple gauge boson interactions. In this letter we propose the Standard Model strictly forbidden Z -> gamma gamma and Z -> gg decay modes coming from the gauge sector of the Noncommutative Standard Model as a place where noncommutativity could be experimentally disc

Saurya Das, P. Ramadevi, U. A. Yajnik

It has been argued by several authors that the quantum mechanical spectrum of black hole horizon area must be discrete. This has been confirmed in different formalisms, using different approaches. Here we concentrate on two approaches, the one involving quantization on a reduced phase space of collective coordinates of a Black Hole and the algebraic approach

A. T. Alan, A. Senol

We study the single top production mediated by flavor changing neutral current via both of the $t-q-γ$ and $t-q-Z$ vertices (here q represents c and u quarks) in ep collisions at two colliders HERA and THERA. Contribution of the second vertex becomes even more important as the couplings take more improved values provided by the higher luminosities of collide

Ch. Amann, M. Brack

We discuss the semiclassical approaches for describing systems with spin-orbit interactions by Littlejohn and Flynn (1991, 1992), Frisk and Guhr (1993), and by Bolte and Keppeler (1998, 1999). We use these methods to derive trace formulae for several two- and three-dimensional model systems, and exhibit their successes and limitations. We discuss, in particu

E. Solano, G. S. Agarwal, H. Walther

We propose a method of generating multipartite entanglement by considering the interaction of a system of N two-level atoms in a cavity of high quality factor with a strong classical driving field. It is shown that, with a judicious choice of the cavity detuning and the applied coherent field detuning, vacuum Rabi coupling produces a large number of importan

Fabio Cecconi, Matteo Marsili, Jayanth R. Banavar, Amos Maritan

We present a general, physically motivated non-linear and non-local advection equation in which the diffusion of interacting random walkers competes with a local drift arising from a kind of peer pressure. We show, using a mapping to an integrable dynamical system, that on varying a parameter, the steady state behaviour undergoes a transition from the standa

Belle Collaboration, K. Abe

This report describes an observation of mixing-induced CP violation and a measurement of the CP violation parameter, sin(2phi_1), with the Belle detector at the KEKB asymmetric e+e- collider. Using a data sample of 29.1 fb-1 recorded on the Upsilon(4S) resonance that contains 31.3 million BBbar pairs, we reconstruct decays of neutral B mesons to the followin

Koji Hashimoto, Satoshi Nagaoka

We examine Sen's descent relations among (non-)BPS D-branes by using low energy effective field theories of DpDpbar system. We find that the fluctuation around the kink solution reproduces the low energy matter content on a non-BPS D(p-1)-brane. The effective action for these fluctuation modes turns out to be a generalization of Minahan-Zwiebach model. I

Alessandro Volpi, John L. Bohn

Cold collisions of ground state oxygen molecules with Helium have been investigated in a wide range of cold collision energies (from 1 $μ$K up to 10 K) treating the oxygen molecule first as a rigid rotor and then introducing the vibrational degree of freedom. The comparison between the two models shows that at low energies the rigid rotor approximation is ve

E. W. Piotrowski, J. Sladkowski

We show that quantum game theory offers solution to the famous Newcomb's paradox (free will problem). Divine foreknowledge is not necessary for successful completion of the game because quantum theory offers a way to discern human intentions in such way that the human retain her/his free will but cannot profit from changing decision. Possible interpretat

E. Solano, R. L. de Matos Filho, N. Zagury

We consider a resonant bichromatic excitation of N trapped ions that generates displacement and squeezing in their collective motion conditioned to their ionic internal state, producing eventually Scrhodinger cat states and entangled squeezing. Furthermore, we study the case of tetrachromatic illumination or producing the so called entangled coherent states

K. Kowalski, J. Rembielinski

The uncertainty relations for the position and momentum of a quantum particle on a circle are identified minimized by the corresponding coherent states. The sqeezed states in the case of the circular motion are introduced and discussed in the context of the uncertainty relations.

Balazs Molnar, Peter Foldi, Mihaly G. Benedict, Ferenc Bartha

We present an algebraic method for treating molecular vibrations in the Morse potential perturbed by an external laser field. By the help of a complete and normalizable basis we transform the Schrödinger equation into a system of coupled ordinary differential equations. We apply our method to calculate the dissociation probability of the NO molecule excited

S. Rebić, A. S. Parkins, S. M. Tan

We explore the photon statistics of light emitted from a system comprising a single four--level atom strongly coupled to a high-finesse optical cavity mode which is driven by a coherent laser field. In the weak driving regime this system is found to exhibit a photon blockade effect. For intermediate driving strengths we find a sudden change in the photon sta

E. G. Bessonov

The dynamics of charged particle beams interacting with laser beams and material targets in storage rings is presented. Formulas for the radiative damping, quantum excitation and equilibrium parameters of ion and electron beams determined by the backward rayleigh and backward compton scattering are derived. General case is considered. It takes into account t

S. Mair, B. Gompf, M. Dressel

A novel THz near-field spectrometer is presented which allows to perform biological and medical studies with high spectral resolution combined with a spatial resolution down to l/100. In the setup an aperture much smaller than the used wavelength is placed in the beam very close to the sample. The sample is probed by the evanescent wave behind the aperture.

M. P. Lorikyan

This paper presents the development of a new technology of registration of ionizing radiation and a new type of detectors - single-cathode multiwire porous detector with neither a gaseous nor semiconductor, but a porous dielectric substance, e.g., CsI, being used as working medium. It is shown that the performance of the multiwire porous detector is stable,

C. O. Escobar, V. Pleitez

We present a critical analysis of what is called Relational Mechanics, as it has been presented in a book thus entitled, which has been recently reviewed in this journal.

J. Carbonell, M. Mangin-Brinet, V. A. Karmanov

We present the main features of the explicitly covariant Light-Front Dynamics formalism and a summary of our recent works on this topic. They concern the bound states of two scalar particles in the Wick-Cutkosky model and of two fermions interacting via the usual OBEP ladder kernels.

D. T. de Paula, T. Aumann, L. F. Canto, B. V. Carlson

The role of anharmonic effects on the excitation of the double giant dipole resonance is investigated in a simple macroscopic model.Perturbation theory is used to find energies and wave functions of the anharmonic ascillator.The cross sections for the electromagnetic excitation of the one- and two-phonon giant dipole resonances in energetic heavy-ion collisi

M. Ueda, A. J. Sargeant, M. P. Pato, M. S. Hussein

We derived analytic formulas of the effective S astrophysical S factor,S^eff for a non-resonant reaction of charged particles using a Taylor expension of the astrophysical S factor and a uniform approximation.The formulas will be able to generate generate more accurate approximation to S^eff than previous ones.

M. K. Bacrania, P. J. Doe, S. R. Elliott, C. E. Paul

Lead can be an ideal medium for the detection and study of neutrinos. Such a detector may be realized through the use of a lead perchlorate solution as a Cerenkov radiator. The basic physical properties of lead perchlorate solution are given and preparation of the solution for use in a Cerenkov detector is described. Results from investigations of light tran

Sadayoshi Toh, Takeshi Matsumoto

We obtained steady solutions to the two-dimensional Boussinesq approximation equations without mean temperature gradient. This system is referred to as free convection in this paper. Under an external flow described by the stream function $\mPsi = - Ayf(x)$, two types of steady solutions are found depending on the boundary conditions. One is kept steady by t

Gregory Berkolaiko, Holger Schanz, Robert S. Whitney

Using periodic-orbit theory beyond the diagonal approximation we investigate the form factor, $K(τ)$, of a generic quantum graph with mixing classical dynamics and time-reversal symmetry. We calculate the contribution from pairs of self-intersecting orbits that differ from each other only in the orientation of a single loop. In the limit of large graphs, the

Richard Kenyon

On a periodic planar graph whose edge weights satisfy a certain simple geometric condition, the discrete Laplacian and d-bar operators have the property that their determinants and inverses only depend on the local geometry of the graph. We obtain explicit expressions for the logarithms of the (normalized) determinants, as well as the inverses of these opera

Stephen C. Anco, Juha Pohjanpelto

A complete and explicit classification of all independent local conservation laws of Maxwell's equations in four dimensional Minkowski space is given. Besides the elementary linear conservation laws, and the well-known quadratic conservation laws associated to the conserved stress-energy and zilch tensors, there are also chiral quadratic conservation law

N. P. Landsman

Notwithstanding known obstructions to this idea, we formulate an attempt to turn quantization into a functorial procedure. We define a category PO of Poisson manifolds, whose objects are integrable Poisson manifolds and whose arrows are isomorphism classes of regular Weinstein dual pairs; it follows that identity arrows are symplectic groupoids, and that two

Franz Lemmermeyer

Let E_k denote the elliptic curve defined by y^2 = x(x^2 - k^2). We consider the curves with k = pl, p = l = 1 mod 8 primes, and show that the density of rank-0 curves among them is at least 1/2 by explicitly constructing nontrivial elements in the 2-part of the Tate-Shafarevich group of E_k.

Chandrashekhar Khare, Dipendra Prasad

In this paper we pose and answer the following question in a few different contexts: Given a homomorphism f:L_1 --> L_2 of a ``lattices'' that ``reduces mod p'' for almost all primes p, is f ``algebraic''? For instance the lattices may be the Mordell-Weil lattices of rational points of abelian varieties over Q, or arithmetic groups et

A. Kheifets, P. Yuditskii

We give a simple example of non-uniqueness in the inverse scattering for Jacobi matrices: roughly speaking $S$-matrix is analytic. Then, multiplying a reflection coefficient by an inner function, we repair this matrix in such a way that it does uniquely determine a Jacobi matrix of Szegö class; on the other hand the transmission coefficient remains the same.

Itai Benjamini, Laszlo Lovasz

Given a graph embedded in an orientable surface, a process consisting of random excitations and random node and face balancing is constructed and analyzed. It is shown that given a priori bounds g' on the genus and n' on the number of nodes, one can determine the genus of the surface from local observations of the process restricted to any connected

Emmanuel Hallouin, Emmanuel Riboulet-Deyris

We study and compute an infinite family of Hurwitz spaces parameterizing covers of P_C branched at four points and deduce explicit regular S_n and A_n-extensions over Q(T) with totally real fibers.

Jean-Camille Birget

We give some connections between various functions defined on finitely presented groups (isoperimetric, isodiametric, Todd-Coxeter radius, filling length functions, etc.), and we study the relation between those functions and the computational complexity of the word problem (deterministic time, nondeterministic time, symmetric space). We show that the isoper

Mihai Tibar

We use slicing by nongeneric pencils of hypersurfaces and prove a new theorem of Lefschetz type for singular non compact spaces, at the homotopy level. As applications, we derive results on the topology of the fibres of polynomial functions or the topology of complements of hypersurfaces in $\mathbb C^n$.

Norio Iwase, Mamoru Mimura

We determine the L-S category of Sp(3) by showing that the 5-fold reduced diagonal $\widebarΔ_5$ is given by $ν^2$, using a Toda bracket and a generalised cohomology theory $h^*$ given by $h^*(X,A) = \{X/A,{\mathbb S}[0,2]\}$, where ${\mathbb S}[0,2]$ is the 3-stage Postnikov piece of the sphere spectrum ${\mathbb S}$. This method also yields a general resul

J. R. Hubbuck, Norio Iwase

A finite connected CW complex which is a co-H-space is shown to have the homotopy type of a wedge of a bunch of circles and a simply-connected finite complex after almost $p$-completion at a prime $p$.

Norio Iwase

A criterion to determine the L-S category of a total space of a sphere-bundle over a sphere is given in terms of homotopy invariants of its characteristic map, and thus providing a complete answer to Ganea's Problem 4. As a result, we obtain a necessary and sufficient condition for such a total space $N$ to have the same L-S category as its `once punctur

Norio Iwase

To clarify the method behind the paper "Ganea's conjecture on Lusternik-Schnirelman category" by the author, a generalisation of Berstein-Hilton Hopf invariants is defined as `higher Hopf invariants'. They detect the higher homotopy associativity of Hopf spaces and are studied as obstructions not to increase the LS category by one by attachin

Hiroshi Sato

We construct one-parameter complex analytic families whose special fibers are complete toric varieties. Under some assumptions, the general fibers of these families also become toric varieties and we can explicitly describe the corresponding fans from the data of the fans corresponding to the special fibers. Using these families, we give a deformation family

Marat Gizatullin

A birational transformation of three-dimensional quadric is constructed. The inequalities of fano are not fulfilled for this transformation.

Vesko Valov

Characterizations of paracompact finite $C$-spaces via continuous selections are given. We apply these results to obtain some properties of finite $C$-spaces. Factorization theorems and a completion theorem for finite $C$- spaces are also established.

Marek Jarnicki, Peter Pflug

Let $D_j\subset\Bbb C^{n_j}$ be a pseudoconvex domain and let $A_j\subset D_j$ be a locally pluriregular set, $j=1,...,N$. Put $$ X:=\bigcup_{j=1}^N A_1\times...\times A_{j-1}\times D_j\times A_{j+1}\times ...\times A_N\subset\Bbb C^{n_1}\times...\times\Bbb C^{n_N}=\Bbb C^n. $$ Let $U\subset\Bbb C^n$ be an open neighborhood of $X$ and let $M\subset U$ be a r

Michael Baake

A Dirac comb of point measures in Euclidean space with bounded complex weights that is supported on a lattice inherits certain general properties from the lattice structure. In particular, its autocorrelation admits a factorization into a continuous function and the uniform lattice Dirac comb, and its diffraction measure is periodic, with the dual lattice as

Florin Radulescu

In this paper we analyze the structure of some sets of non-commutative moments of elements in a finite von Neumann algebra M. If the fundamental group of M is R_+\{0}, then the moment sets are convex, and if M is isomorphic to M tensor M, then the sets are closed under pointwise multiplication. We introduce a class of discrete groups that we call hyperlinear

Stéphane Salmons, Pierre GrangÉ, Ernst Werner

The dynamics of the phase transition of the continuum $Φ^{4}_{1+1}$-theory in Light Cone Quantization is reexamined taking into account fluctuations of the order parameter $< Φ>$ in the form of dynamical zero mode operators (DZMO) which appear in a natural way via the Haag expansion of the field $Φ(x)$ of the interacting theory. The inclusion of the DZM-sect

M. A. Santos

In this paper we apply the Symplectic Projectors Method to gauge theories with second class constraints in various space-time dimensions. The conclusion is that this method is equivalent to the standard quantization methods. Although it suffers from some limitations since its applicability is restricted to some simpler situation when one is not interested in

Tibra Ali

We give a path-integral proof of level-rank duality in Kazama-Suzuki models for world-sheets of spherical topology.

Jorma Louko, David L. Wiltshire

We construct a family of (p+3)-dimensional brane worlds in which the brane has one compact extra dimension, the bulk has two extra dimensions, and the bulk closes regularly at codimension two submanifolds known as bolts. The (p+1)-dimensional low energy spacetime M_{low} may be any Einstein space with an arbitrary cosmological constant, the value of the bulk

G. Kulzinger

We consider scattering in nonperturbative Quantum Chromodynamics (QCD) for large invariant centre of mass energy $\surd s$. Our analysis is based upon the Stochastic Vacuum Model~(SVM) of Dosch and Simonov and on the nonperturbative $s \to \infty$-asymptotic formula of Nachtmann for the scattering of two Wegner Wilson loops. We argue, that its validity can b

T. M. Aliev, A. Ozpineci, M. Savci

Using the most general, model independent form of the effective Hamiltonian, the exclusive, rare baryonic (Lambda_b -> Lambda l^+ l^- ~l=μ,τ) decay is analyzed. We study sensitivity of the branching ratio and lepton forward-backward asymmetry to the new Wilson coefficients. Is is shown that these physical quantities are quite sensitive to the new Wilson coef

V. K. Magas, L. P. Csernai, D. D. Strottman

An Effective String Rope Model (ESRM) for heavy ion collisions at RHIC energies is presented. Our model takes into account baryon recoil for both target and projectile, arising from the acceleration of partons in an effective field, produced in the collision. The typical field strength (string tension) for RHIC energies is about $5-12 GeV/fm$, what allows us

Zoltan Ligeti, Yosef Nir

Further experimental and theoretical studies of the physics of flavor and CP violation are well motivated. Within the supersymmetric framework, higher precision measurements will allow to explore classes of models with stronger degree of universality: first, models with no universality, such as alignment or heavy first two squark generations; second, models

Jose J. Blanco-Pillado, Ken D. Olum, Alexander Vilenkin

We investigate the decay of current on a superconducting cosmic string through quantum tunneling. We construct the instanton describing tunneling in a simple bosonic string model, and estimate the decay rate. The tunneling rate vanishes in the limit of a chiral current. This conclusion, which is supported by a symmetry argument, is expected to apply in gener

R. Bellwied, D. Cinabro, V. L. Rykov

The track timing capabilities of a silicon drift detector based tracker for a future linear electron-positron collider are evaluated. We show such a detector can time tracks at the nanosecond, and for high-$P_{T}$, sub-nanosecond level. This implies that, even for collider designs with the bunch spacing at 1.4 ns, every track can be assigned to a particular

Roy A. Briere

We report recent measurements from CLEO of the first two moments of the photon energy spectrum for b -> s gamma decays and the hadronic recoil mass in B -> X_c l nu. These physical quantities allow one to fix non-perturbative parameters occurring in calculations based on HQET and QCD. Predictions for semileptonic decay rates within this same framework depend

Belle Collaboration

We report the first observation of chi_c2 production in B-meson decays. We find an inclusive B -> chi_c2 X branching fraction of (1.80^{+0.23}_{-0.28}+/- 0.26) 10^-3. The data set, collected with the Belle detector at the KEKB e^+e^- collider, consists of 31.9 million B\bar B events. We also present branching fractions and momentum spectra for both chi_c1 an

H. P. de Oliveira, I. Damião Soares

We study the general dynamics of the spherically symmetric gravitational collapse of a massless scalar field. We apply the Galerkin projection method to transform a system of partial differential equations into a set of ordinary differential equations for modal coefficients, after a convenient truncation procedure, largely applied to problems of turbulence.

H. P. de Oliveira

Starting from a gauge invariant treatment of perturbations an analytical expression for the spectrum of long wavelength density perturbations in warm inflation is derived. The adiabatic and entropy modes are exhibited explicitly. As an application of the analytical results, we determined the observational constraint for the dissipation term compatible with C

Jorge Pullin

Community News: - Center for Gravitational Wave Physics, by Sam Finn - Perimeter Institute for Theoretical Physics, by Lee Smolin Research Briefs: - Detector and Data Developments within GEO 600, by Alicia Sintes - The Virtual Data Grid and LIGO, by Pat Brady and Manuela Campanelli - 1000 hours of data and first lock of the recycled TAMA300, by Seiji Kawamur

Simon Davis, Hugh Luckock

The wave function for the quadratic gravity theory derived from the heterotic string effective action is deduced to first order in ${e^{-Φ}\over {g_4^2}}$ by solving a perturbed second-order Wheeler-DeWitt equation, assuming that the potential is slowly varying with respect to $Φ$. Predictions for inflation based on the solution to the second-order Wheeler-D

A. V. Nikulov

Results of the investigation of fluctuation phenomena in bulk type-II superconductors obtained in 1980 - 1984 years are compared with the analogous results obtained at the investigation of high-Tc superconductors (HTSC). It is shown the latter repeat in the main the results obtained before the HTSC discovery. It was discovered in 1981 year that a sharp chang

D. P. Young, J. F. DiTusa, R. G. Goodrich, D. Hall

Hall, resistivity, magnetization, and thermoelectric power measurements were performed on single crystals of the highly anisotropic layered metal LaSb2. A 100-fold linear magnetoresistance (MR) was observed in fields up to 45 T, with no indication of saturation. We show that the MR is associated with a magnetic-field-dependent holelike carrier density, n(H)

M. Calandra, J. Merino, Ross H. McKenzie

We study with exact diagonalization the zero temperature properties of the quarter-filled extended Hubbard model on a square lattice. We find that increasing the ratio of the intersite Coulomb repulsion, $V$, to the band width drives the system from a metal to a charge ordered insulator. The evolution of the optical conductivity spectrum with increasing $V$

Yong-Hoon Kim, Martin Staedele, Andreas Goerling

We calculate the imaginary part of the frequency-dependent dielectric function of bulk silicon by applying time-dependent density-functional theory based on the exact-exchange (EXX) Kohn-Sham (KS) band structure and the adiabatic local-density approximation (ALDA) kernel. The position of the E2 absorption peak calculated with the EXX band structure at the in

A. V. Chechkin, R. Gorenflo, I. M. Sokolov

We propose diffusion-like equations with time and space fractional derivatives of the distributed order for the kinetic description of anomalous diffusion and relaxation phenomena, whose diffusion exponent varies with time and which, correspondingly, can not be viewed as self-affine random processes possessing a unique Hurst exponent. We prove the positivity

E. G. Moshopoulou, J. L. Sarrao, P. G. Pagliuso, N. O. Moreno

The crystal structure of the recently discovered heavy-fermion (HF) superconductor CeCoIn5 (Tc = 2.3 K) has been determined by high-resolution neutron powder diffraction. It is tetragonal (space group P4/mmm), with lattice parameters a = 4.61292(9) A and c = 7.5513(2) A at ambient conditions. Whereas CeCoIn5 is isostructural with the HF aniferromagnet CeRhIn

E. Lyman, B. Schmittmann

We present Monte Carlo simulations of a three-state lattice gas, half-filled with two types of particles which attract one another, irrespective of their identities. A bias drives the two particle species in opposite directions, establishing and maintaining a non-equilibrium steady state. We map out the phase diagram at fixed bias, as a function of temperatu

Dean Lee, Nathan Salwen

We derive general lower energy bounds for the ground state energy of any translationally invariant quantum lattice Hamiltonian. The bounds are given by the ground state energy of renormalized Hamiltonians on finite clusters.

A. Lascialfari, A. Rigamonti, L. Romano&#39;, P. Tedesco

SQUID magnetization measurements in oriented powders of Y$_{1-x}$Ca$_{x}$Ba$% _{2}$Cu$_{3}$O$_{y}$, with $x$ ranging from 0 to 0.2, for $y\approx 6.1$ and $y\approx 6.97$, have been performed in order to study the doping dependence of the fluctuating diamagnetism above the superconducting transition temperature $T_{c}$. While for optimally doped compounds th

S. A. Gramsch, R. E. Cohen, S. Y. Savrasov

The accuracy of LDA + U total energies is tested by predicting the high pressure behavior of rocksalt-structured FeO, including metal-insulator and magnetic transitions, equation of state, and lattice strain, as functions of the Coulomb repulsion U. For U = 4.6 eV, 6.0 eV and 8.0 eV, two self-consistent solutions, one with rhombohedral and one with monoclini

R. D. Blandford

Two related topics are discussed. 1. Accretion onto black holes at low and high (though not very high) rates is believed to proceed adiabatically ({\em ie} non-radiatively). It is argued that the liberated energy is carried off by an outflow, probably involving almost all of the gas that is supplied. Two dimensional, fluid, accretion disks, in which mass, an

R. D. Blandford

A summary is presented of a symposium held to review recent progress in X-ray astronomy and to discuss prospects for the next generation of X-ray missions. The summary is organized around ten general, astrophysical questions that may provide scientific drivers for the design of new facilities.

Cindy Tam, Mallory S. E. Roberts, Victoria M. Kaspi

We present a high-resolution radio study of the supernova remnant (SNR) G11.2-0.3 using archival VLA data. Spectral tomography is performed to determine the properties of this composite-type SNR&#39;s individual components, which have only recently been distinguished through X-ray observations. Our results indicate that the spectral index of the pulsar wind

B. D. G. Chandran, D. C. Backer

We study the propagation of radio waves through a medium possessing density fluctuations that are elongated along the ambient magnetic field and described by an anisotropic Goldreich-Sridhar power spectrum. We derive general formulas for the wave phase structure function, visibility, angular broadening, diffraction-pattern length scales, and scintillation ti

Pinaki Chatterjee, Lars Hernquist, Abraham Loeb

We derive a model that describes the motion of a Brownian particle in a system which is dominated by gravitational forces. An example of such a system is a massive black hole immersed in a cluster of stars. We compute the dispersion in the position and velocity of such a black hole, and examine whether it achieves a state of equipartition of kinetic energy w

Dragan Huterer, Glenn D. Starkman, Mark Trodden

We consider the fate of the observable universe in the light of the discovery of a dark energy component to the cosmic energy budget. We extend results for a cosmological constant to a general dark energy component and examine the constraints on phenomena that may prevent the eternal acceleration of our patch of the universe. We find that the period of accel

W. M. Lane, N. E. Kassim, T. A. Ensslin, D. E. Harris

We present a new wide-field map of the radio galaxy 3C 129 and its companion galaxy 3C 129.1 at lambda=90 cm. We see a distinct steep-spectrum feature near the head of 3C 129, extending in a direction perpendicular to the radio tails. We propose that this Crosspiece might consist of fossil radio plasma, which has been re-energized by the compression of the b

C. D. Dermer

This paper presents the theoretical basis of the fireball/blast wave model, and some implications of recent results on GRB source models and cosmic-ray production from GRBs. BATSE observations of the prompt gamma-ray luminous phase, and Beppo-SAX and long wavelength afterglow observations of GRBs are briefly summarized. Derivation of spectral and temporal in

A. C. Quillen

Hipparcos parallaxes and proper motions have made it possible to construct Hertzsprung-Russell (HR) diagrams of nearby clusters with unprecedented accuracy. The standard deviation of high fidelity non-binary non-variable stars about a model stellar evolution isochrone in the Hyades cluster is about 0.04 magnitudes. We use this deviation to estimate an upper

A. Rodriguez-Ardila, S. M. Viegas, M. G. Pastoriza, L. Prato

UV, visible, and near-infrared spectroscopy is used to study the transitions of neutral oxygen leading to the emission of broad OI $λ$8446, $λ$11287 and $λ$1304 in Active Galactic Nuclei. From the strength of the former two lines, contrary to the general belief, we found that in six out of seven galaxies, L-beta fluorescence is not the only mechanism respons

Gordon T. Richards, Xiaohui Fan, Heidi Jo Newberg, Michael A. Strauss

We describe the algorithm for selecting quasar candidates for optical spectroscopy in the Sloan Digital Sky Survey. Quasar candidates are selected via their non-stellar colors in &#34;ugriz&#34; broad-band photometry, and by matching unresolved sources to the FIRST radio catalogs. The automated algorithm is sensitive to quasars at all redshifts lower than z=

Jorge Penarrubia, Pavel Kroupa, Christian M. Boily

We carry out a set of self-consistent N-body calculations to compare the decay rates of satellite dwarf galaxies orbiting a disc galaxy embedded in a dark matter halo (DMH). We consider both spherical and oblate axisymmetric DMHs of aspect ratio q_h=0.6. The satellites are given different initial orbital inclinations, orbital periods and mass. The live flatt

A. Skopal, M. Vanko, T. Pribulla, M. Wolf

We present new photometric observations of EG And, Z And, BF Cyg, CH Cyg, V1329 Cyg, AG Dra, RW Hya, AX Per and IV Vir made in standard Johnson UBVR system. The current issue summarizes observations of these onjects to 2001 December.

L. Foschini, G. Di Cocco, M. Dadina, L. Bassani

We present preliminary results from a study with XMM-Newton of the galactic serendipitous sources in a sample of 28 nearby Seyfert galaxies (with D < 22 Mpc). We concentrate here on a subset of four galaxies, namely: NGC3185, NGC3486, NGC3941, and NGC4565. In these galaxies we found six ultraluminous X-ray source (ULX). The large collecting area of XMM-Newto

G. Rüdiger, R. Arlt, D. Shalybkov

The hydrodynamic stability of accretion disks is considered. The particular question is whether the combined action of a (stable) vertical density stratification and a (stable) radial differential rotation gives rise to a new instability for nonaxisymmetric modes of disturbances. The existence of such an instability is not suggested by the well-known Solberg

M. Cappi, G. Di Cocco, F. Panessa, L. Foschini

We report here preliminary results from a survey of nearby Seyfert galaxies using the EPIC CCDs on board XMM-Newton. The total sample consists of 28 Seyfert galaxies, and constitute a well-defined, complete (B<12.5 mag), and volume-limited (D<22 Mpc) sample of Seyfert galaxies in the northern (Delta > 0 deg.) hemisphere. The survey has been initiated in June

Chris Flynn, Janne Holopainen, Johan Holmberg

We discuss the recent discovery by Oppenheimer et al (2001) of old, cool white dwarf stars, which may be the first direct detection of Galactic halo dark matter. We argue here that the contribution of more mundane white dwarfs of the stellar halo and thick disk would contribute sufficiently to explain the new high velocity white dwarfs without invoking putat

T. A. Gardiner, A. Frank, L. Hartmann

We present two-dimensional, cylindrically symmetric simulations of hydrodynamic and magnetohydrodynamic (MHD) wide-angle winds interacting with a collapsing environment. These simulations have direct relevance to young stellar objects (YSOs). The results may also be of use in the study of collimated outflows from proto-planetary and planetary nebulae. We stu

A. V. Moiseev, J. R. Valdes, V. H. Chavushyan

The first results of the observational program of the study of 2D-kinematics in double-barred galaxies are presented. We show that, for the main part of the sample, the inner bars do not affect the circumnuclear stellar kinematics. Therefore, they are not dynamically decoupled structures. Various types of non-circular gas motion were found in many galaxies.

Sergey M. Klishevich, Mikhail S. Plyushchay

We investigate the nonlinear holomorphic supersymmetry for quantum-mechanical systems on Riemann surfaces subjected to an external magnetic field. The realization is shown to be possible only for Riemann surfaces with constant curvature metrics. The cases of the sphere and Lobachevski plane are elaborated in detail. The partial algebraization of the spectrum