November 1999 arXiv papers — page 24

Richard Jozsa, Juergen Schlienz

Consider an ensemble of pure quantum states |ψ_j>, j=1,...,n taken with prior probabilities p_j respectively. We show that it is possible to increase all of the pairwise overlaps |<ψ_i|ψ_j>| i.e. make each constituent pair of the states more parallel (while keeping the prior probabilities the same), in such a way that the von Neumann entropy S is increased,

A. Acin, R. Tarrach, G. Vidal

We present optimal measuring strategies for the estimation of the entanglement of unknown two-qubit pure states and of the degree of mixing of unknown single-qubit mixed states, of which N identical copies are available. The most general measuring strategies are considered in both situations, to conclude in the first case that a local, although collective, m

Iwo Bialynicki-Birula, Zofia Bialynicka-Birula, Cezary Sliwa

Exact analytic solutions of the time dependent Schrodinger equation are produced that exhibit a variety of vortex structures. The qualitative analysis of the motion of vortex lines is presented and various types of vortex behavior are identified. Vortex creation and annihilation and vortex interactions are illustrated in the special cases of the free motion,

I. V. Dobrovolska, R. S. Tutik

The explicit semiclassical treatment of logarithmic perturbation theory for the bound-state problem within the framework of the Dirac equation is developed. Avoiding disadvantages of the standard approach in the description of exited states, new handy recursion formulae with the same simple form both for ground and exited states have been obtained. As an exa

H. Moya-Cessa, P. Tombesi

We propose a scheme to generate number states (and specific superpositions of them) of the vibrational motion of a trapped ion. In particular, we show that robust to noise qubits can be generated with arbitrary amplitudes.

Gui Lu Long, Chang Cun Tu, Yan Song Li, Wei Lin Zhang

An SO(3) picture of the generalized Grover&#39;s quantum searching algorithm,with arbitrary unitary transformation and with arbitrary phase rotations, is constructed. In this picture, any quantum search operation is a rotation in a 3 dimensional space. Exact formulas for the rotation angle and rotational axis are given. The probability of finding the marked

Ali Mostafazadeh

For a T-periodic non-Hermitian Hamiltonian H(t), we construct a class of adiabatic cyclic states of period T which are not eigenstates of the initial Hamiltonian H(0). We show that the corresponding adiabatic geometric phase angles are real and discuss their relationship with the conventional complex adiabatic geometric phase angles. We present a detailed ca

Thomas Schaefer

We discuss recent results on color superconductivity in QCD at large chemical potential.

W. R. B. de Araujo, E. F. Suisso, T. Frederico, M. Beyer

We investigate the effect of different forms of relativistic spin coupling of constituent quarks in the nucleon electromagnetic form factors. The four-dimensional integrations in the two-loop Feynman diagram are reduced to the null-plane, such that the light-front wave function is introduced in the computation of the form factors. The neutron charge form fac

J. C. Dunlop, C. A. Ogilvie

The measured K$^+/π^+$ ratios from heavy-ion reactions are compared with the K$^+/π^+$ ratios from p+p reactions over the energy range 2-160 AGeV. The K/$π$ enhancement in heavy-ion reactions is largest at the lower energies, consistent with strangeness production in secondary scattering becoming relatively more important than initial collisions near the kao

C. M. Keil, F. Hofmann, H. Lenske

The Density Dependent Relativistic Hadron Field (DDRH) theory, previously introduced and applied to isospin nuclei, is extended to hypernuclei by including the octet hyperons. Infinite matter Dirac-Brueckner theory for octet baryons and the derivation of in-medium DDRH baryon-meson vertices is discussed. From the properties of Dirac-Brueckner interactions it

L. McLerran

In these lectures, I shall discuss small x physics and the consequences of the high gluon density which arises as x decreases. I argue that an understanding of this problem would lead to knowledge of the high energy asymptotics of hadronic processes. The high gluon density should allow a first principles computation of these asymptotics from QCD. This physic

L. V. Bravina, E. E. Zabrodin, Amand Faessler, C. Fuchs

The directed flow of protons is studied in the quark-gluon string model as a function of the impact parameter for S+S and Pb+Pb reactions at 160 AGeV/c. A significant reduction of the directed flow in midrapidity range, which can lead to the development of the antiflow, is found due to the absorption of early emitted particles by massive spectators (shadowin

A. Diaz-Torres, G. G. Adamian, N. V. Antonenko, W. Scheid

The time-dependent transition between a diabatic interaction potential in the entrance channel and an adiabatic potential during the fusion process is investigated within the two-center shell model. A large hindrance is obtained for the motion to smaller elongations of near symmetric dinuclear systems. The comparison of the calculated energy thresholds for t

J. I. Johansson, H. S. Sherif

We study the effect of wave function orthogonality in the relativistic treatment of the nucleon removal reactions (gamma, p) and (e, e&#39; p). The continuum wave function describing the outgoing nucleon is made orthogonal to the relevant bound states using the Gram-Schmidt procedure. This procedure has the advantage of preserving the asymptotic character of

Zorka Papadopolos, Oleg Ogievetsky

We give the inflation rules for the decorated Mosseri-Sadoc tiles in the projection class of tilings ${\cal T}^{(MS)}$. Dehn invariants related to the stone inflation of the Mosseri-Sadoc tiles provide eigenvectors of the inflation matrix with eigenvalues equal to $τ= \frac{1+\sqrt{5}}{2}$ and $-τ^{-1}$.

C. Quesne

We comment on a recent paper by Chen, Liu, and Ge (J. Phys. A: Math. Gen. 31 (1998) 6473), wherein a nonlinear deformation of su(1,1) involving two deforming functions is realized in the exactly solvable quantum-mechanical problem with P\&#34; oschl-Teller potential, and is used to derive the well-known su(1,1) spectrum-generating algebra of this problem. We

Kur. Myrzakul, R. Myrzakulov

Some aspects of the multidimensional soliton geometry are considered. The relation between soliton equations in 2+1 dimensions and the Self-Dual Yang-Mills and Bogomolny equations are discussed.

Hiroshi Sato

The purpose of this paper is to give basic tools for the classification of nonsingular toric Fano varieties by means of the notions of primitive collections and primitive relations due to Batyrev. By using them we can easily deal with equivariant blow-ups and blow-downs, and get an easy criterion to determine whether a given nonsingular toric variety is a Fa

Olav Nygaard, Dirk Werner

We show that every nonvoid relatively weakly open subset, in particular every slice, of the unit ball of an infinite-dimensional uniform algebra has diameter~2.

Yu. A. Neretin

Consider the space B of complex $p\times q$ matrces with norm <1. There exists a standard one-parameter family $S_a$ of unitary representations of the pseudounitary group U(p,q) in the space of holomorphic functions on B (i.e. scalar highest weight representations). Consider the restriction $T_a$ of $S_a$ to the pseudoorthogonal group O(p,q). The representat

S. A. Argyros, I. Gasparis

The following dichotomy is established for a normalized weakly null sequence in a Banach space: Either every subsequence admits a convex block subsequence equivalent to the unit vector basis of c, the Banach space of null sequences under the supremum norm, or there exists a subsequence which is boundedly convexly complete. This result generalizes J. Elton&#3

Mark Gross

This paper focuses on a topological version on the Strominger-Yau-Zaslow mirror symmetry conjecture. Roughly put, the SYZ conjecture suggests that mirror pairs of Calabi-Yau manifolds are related by the existence of dual special Lagrangian torus fibrations. We explore this conjecture without reference to the special Lagrangian condition. In this setting, nat

A. Nersessian

We analyze the possibility of description of D-dimensional massless particles by the Lagrangians linear on world-line curvatures k_i, {\cal S}=\sum_{i=1}^Nc_i\int k_i d{\tilde s}. We show, that the nontrivial classical solutions of this model are given by space-like curves with zero 2N-th curvature for N\leq[(D-2)/2]. Massless spinning particles correspond t

R. R. Metsaev

Light cone form of field dynamics in anti-de Sitter spacetime is described. We also present light cone reformulation of the boundary conformal field theory representations. AdS/CFT correspondence between the bulk fields and the boundary operators is discussed.

Ion I. Cotăescu, Mihai Visinescu

The Schrödinger equation is investigated in the Euclidean Taub-NUT geometry. The bound states are degenerate and an extra degeneracy is due to the conserved Runge-Lenz vector. The existence of the extra conserved quantities, quadratic in four-velocities implies the possibility of separating variables in two different coordinate systems. The eigenvalues and t

Konstantin G. Zloshchastiev

The effective p-brane action approach is generalized for arbitrary scalar field and applied for the Liouville theory near a particle-like solution. It was established that this theory has the remarkable features discriminating it from the theories studied earlier. Removing zero modes we obtain the effective action describing the solution as a point particle

Konstantin G. Zloshchastiev

The cubic scalar field theory admits the bell-shaped solitary wave solutions which can be interpreted as massive Bose particles. We rule out the nonminimal p-brane action for such a solution as the point particle with curvature. When quantizing it as the theory with higher derivatives, it is shown that the corresponding quantum equation has SU(2) dynamical s

Sung-Won Kim, Won Tae Kim, John J. Oh

We study massless and massive Hawking radiations on a two-dimensional AdS spacetime. For the massless case, the quantum stress-energy tensor of a massless scalar field on the AdS background is calculated, and the expected null radiation is obtained. However, for the massive case, the scattering analysis is performed in order to calculate the absorption and r

M. Calixto, V. Aldaya

The unitary implementation of a symmetry group $G$ of a classical system in the corresponding quantum theory entails unavoidable deformations $\TG$ of $G$, namely, central extensions by the typical phase invariance group U(1). The appearance of central charges in the corresponding Lie-algebra quantum commutators, as a consequence of non-trivial responses of

Victor T. Kim, Lev N. Lipatov, Grigorii B. Pivovarov

The next-to-leading order (NLO) corrections to the BFKL equation in the BLM optimal scale setting are briefly discussed. A striking feature of the BLM approach is rather weak Q^2-dependence of the Pomeron intercept, which might indicate an approximate conformal symmetry of the equation. An application of the NLO BFKL resummation for the virtual gamma-gamma t

L. Perivolaropoulos, T. N. Tomaras

We present a detailed analytical and numerical study of a novel type of static, superconducting, classically stable string texture in a renormalizable topologically trivial massive U(1) gauge model with one charged and one neutral scalar. An upper bound on the mass of the charged scalar as well as on the current that the string can carry are established. A p

Carlo Ewerz

A new representation for the two-to-four gluon vertex arising in the context of unitarity corrections is derived which involves only BFKL kernels. We discuss possible implications of this representation, including the possibility of finding the NLO corrections to the vertex.

J. W. F. Valle

Recent solar & atmospheric nu-data strongly indicate need for physics beyond the Standard Model. I review the ways of reconciling them in terms of 3-nu oscillations. Though not implied by data, bi-maximal nu-mixing models emerge as a possibility. SUSY with broken R-parity provides an attractive way to incorporate it, opening the possibility of testing nu-ano

R. Casalbuoni, R. Gatto

The constants of the effective action describing the massless modes in the color-flavor-locking phase of QCD have been recently evaluated at high density. Values of the pseudoscalar masses for nonvanishing quark masses have also been given. The calculated values show however a puzzling feature: when $m_u=m_d=0$ and $m_s\not=0$ all the goldstones remain massl

B. Pötter

We present an update of the JetViP 1.1 program for performing fixed NLO calculations in jet production including direct and resolved components in a continuous range of photon virtuality Q^2. The new version allows to access the full event record on the parton level. The program is set up such that hbook can be used to fill histograms. The phase space genera

Chris Michael

The status of lattice determinations of quarkonia and hybrid meson spectra is presented and compared with experiment. Both quenched and unquenched results are discussed. Hybrid meson decays are considered.

Daniel Wicke

To measure the strong coupling alpha_s from event shape observables two ingredients are necessary. A perturbative prediction containing the dependence of observables on alpha_s and a description of the hadronisation process to match the perturbative prediction with the hadronic data. As perturbative prediction O(alpha_s^2), NLLA and combined calculations are

Paul Singer

The search for new physics beyond the standard model is proceeding nowadays intensively along experimental and theoretical lines. We review here the sector of charm radiative decays in this context. The calculation of $D\to Vγ$, $D\to \ell^+\ell^-γ$ transitions reveals their unequivocal dominance by long-distance contributions. On the other hand, the beauty-

P. Di Bari

We show how the generation of a lepton number in the Early Universe induced by active-sterile neutrino oscillations, in presence of small baryon number inhomogeneities, gives rise to the formation of lepton domains, regions with different values of active neutrino chemical potential. The structure of these domains reflects the spectral features of the baryon

J. Ranft

DPMJET is a Monte Carlo model for sampling of hadron-hadron, hadron-nucleus, nucleus-nucleus and neutrino-nucleus interactions at accelerator and Cosmic Ray energies according to the two-component Dual Parton Model. Here we describe new features in version DPMJET-II.5: Implementation of new DPM diagrams for an improved description of baryon stopping in nucle

ALEPH Collaboration

The ee -> ZZ cross section at sqrt(s)=182.7 and 188.6 GeV has been measured using the ALEPH detector. The analysis covers all of the visible ZZ final states and yields cross section measurements of sigma_ZZ(182.7 GeV) = 0.11 +- (0.16,0.11) (stat.) +- 0.04 (syst.) pb and sigma_ZZ(188.6 GeV) = 0.67 +- 0.13 (stat.) +- 0.04 (syst.) pb consistent with the Standar

Ulrich F. Katz

Recent results on searches for new particles at the electron-proton collider HERA are reported. Based on roughly 40pb-1 of e^+p data taken in the years 1994-1997, the H1 and ZEUS collaborations have derived new exclusion limits for the direct production of excited fermion states and of leptoquarks in different decay channels, including lepton-flavor violatin

Lawrence E. Kidder, Lee Samuel Finn

Numerical relativity has traditionally been pursued via finite differencing. Here we explore pseudospectral collocation (PSC) as an alternative to finite differencing, focusing particularly on the solution of the Hamiltonian constraint (an elliptic partial differential equation) for a black hole spacetime with angular momentum and for a black hole spacetime

M. F. A. da Silva, Anzhong Wang, Filipe M. Paiva, N. O. Santos

The main properties of the Levi-Civita solutions with the cosmological constant are studied. In particular, it is found that some of the solutions need to be extended beyond certain hypersurfaces in order to have geodesically complete spacetimes. Some extensions are considered and found to give rise to black hole structure but with plane symmetry. All the sp

Mustapha Ishak, Peter Musgrave, John Mourra, Jonathan Stern

GRLite and GRTensorJ are first and second generation graphical user interfaces to the computer algebra system GRTensorII. Current development centers on GRTensorJ, which provides fully customizable symbolic procedures that reduce many complex calculations to &#34;elementary functions&#34;. Although still in development, GRTensorJ, which is now available (fre

Cayetano Di Bartolo, Rodolfo Gambini, Jorge Griego, Jorge Pullin

In a companion paper we introduced a kinematical arena for the discussion of the constraints of canonical quantum gravity in the spin network representation based on Vassiliev invariants. In this paper we introduce the Hamiltonian constraint, extend the space of states to non-diffeomorphism invariant ``habitats&#39;&#39; and check that the off-shell quantum

Cayetano Di Bartolo, Rodolfo Gambini, Jorge Griego, Jorge Pullin

We generalize the idea of Vassiliev invariants to the spin network context, with the aim of using these invariants as a kinematical arena for a canonical quantization of gravity. This paper presents a detailed construction of these invariants (both ambient and regular isotopic) requiring a significant elaboration based on the use of Chern-Simons perturbation

I. Z. Fisher

(Foreword by translator.) The aim of present translation is to clarify the historically important question who was the pioneer in obtaining of exact static solutions of Einstein equations minimally coupled with scalar field. Usually, people cite the works by Janis, Newman, Winicour (Phys. Rev. Lett. 20 (1968) 878) and others authors whereas it is clear that

Konstantin G. Zloshchastiev

The spherically symmetric layer of matter is considered within the frameworks of general relativity. We perform generalization of the already known theory for the case of nonconstant surface entropy and finite temperature. We also propose the minisuperspace model to determine the behaviour of temperature field and perform the Wheeler-DeWitt quantization.

L. Tessieri, F. M. Izrailev

We study localization properties of electronic states in one-dimensional lattices with nearest-neighbour interaction. Both the site energies and the hopping amplitudes are supposed to be of arbitrary form. A few cases are considered in details. We discuss first the case in which both the diagonal potential and the fluctuating part of the hopping amplitudes a

C. Reichhardt, G. T. Zimanyi

We study numerically the effects of temperature on moving vortex lattices interacting with periodic pinning arrays. For low temperatures the vortex lattice flows in channels, forming a hexatic structure with long range transverse and longitudinal ordering. At higher temperatures, a transition to a smectic state occurs where vortices wander between channels a

M. T. Batchelor, J. de Gier, J. Links, M. Maslen

We extend the results of spin ladder models associated with the Lie algebras $su(2^n)$ to the case of the orthogonal and symplectic algebras $o(2^n),\ sp(2^n)$ where n is the number of legs for the system. Two classes of models are found whose symmetry, either orthogonal or symplectic, has an explicit n dependence. Integrability of these models is shown for

Yuval Oreg, Krzysztof Byczuk, Bertrand I. Halperin

We study, theoretically, the ground state spin of a carbon nanotube in the presence of an external potential. We find that when the external potential is applied to a part of the nanotube, its variation changes the single electron spectrum significantly. This, in combination with Coulomb repulsion and the symmetry properties of a finite length armchair nanot

Catalin Mandache, Daniel ben-Avraham

We study the kinetics of diffusion-limited coalescence, A+A->A, and annihilation, A+A->0, in random media consisting of disconnected domains of reaction. Examples include excitons fusion and annihilation in porous matrices and along polymer chains. We begin with an exact analysis of A+A->A in a finite segment. This result is applied to coalescence in a rando

Roberto A. Monetti, Alejandro Rozenfeld, Ezequiel V. Albano

First-order irreversible phase transitions (IPT&#39;s) between an active regime and an absorbing state are studied in two models by means of both simulations and mean-field stability analysis. Hysteresis around coexistence is the result of the interplay of the length of the interface, its curvature, and a memory effect related to the phase which is being rem

J. Lorenzana, J. Eroles, S. Sorella

We compute the absorption spectrum for multimagnon excitations assisted by phonons in insulating layered cuprates using exact diagonalization in clusters of up to 32 sites. The resulting line shape is very sensitive to the underlying magnetic Hamiltonian describing the spin dynamics. For the usual Heisenberg description of undoped Cu-O planes we find, in acc

V. L. Golo, E. I. Kats, Yu. M. Yevdokimov

We calculate the spectrum of torsional vibrations of a double-stranded structure that models the double helix of the DNA. We come to the conclusion that within the framework of the model elementary excitations may display an asymmetry as regards their winding and direction of the propagation, depending on initial polarization. The asymmetry could have a bear

R. K. P. Zia, L. B. Shaw, B. Schmittmann

We report recent simulation results which might indicate the existence of a new low-temperature &#34;phase&#34; in an Ising lattice gas, driven into a non-equilibrium steady state by an external field. It appears that this &#34;phase&#34;, characterized by multiple-strip configurations, is selected when square systems are used to approach the thermodynamic l

M. J. Van Bael, K. Temst, V. V. Moshchalkov, Y. Bruynseraede

We report on the magnetic properties of elongated submicron magnetic islands and their influence on a superconducting film. The magnetic properties were studied by magnetization hysteresis loop measurements and scanning-force microscopy. In the as-grown state, the islands have a magnetic structure consisting of two antiparallel domains. This stable domain co

M. J. Van Bael, L. Van Look, K. Temst, M. Lange

The pinning of flux lines by two different types of regular arrays of submicron magnetic dots is studied in superconducting Pb films; rectangular Co dots with in-plane magnetization are used as pinning centers to investigate the influence of the magnetic stray field of the dots on the pinning phenomena, whereas multilayered Co/Pt dots with out-of-plane magne

Eugene B. Kolomeisky, Joseph P. Straley

Directed manifolds (domain walls, interfaces, vortex lines) in a deformable medium can exist in a correlated state in which the manifold is self-localized by its own strain field. Depending on the temperature, manifold/medium dimensionalities, and the strength of the coupling with the medium, the degree of localization of the ground state can vary both conti

Francisco Tamarit, Celia Anteneodo

We analyze the equilibrium properties of a chain of ferromagnetically coupled rotators which interact through a force that decays as $r^{-α}$ where r is the interparticle distance and $α\ge 0$. Our model contains as particular cases the mean field limit ($α=0$) and the first-neighbor model ($α\to \infty$). By integrating the equations of motion we obtain the

Frank Milde, Rudolf A. Römer, Michael Schreiber, Ville Uski

We study the three-dimensional Anderson model of localization with anisotropic hopping, i.e., weakly coupled chains and weakly coupled planes. In our extensive numerical study we identify and characterize the metal-insulator transition by means of the transfer-matrix method. The values of the critical disorder $W_c$ obtained are consistent with results of pr

M. Jahan-Miri

We report on a study of the evolution of magnetic fields of neutron stars, driven by the expulsion of magnetic flux out of the proton superconducting core of the star. The rate of expulsion, or equivalently the velocity of outward motion of flux-carrying proton-vortices is determined from a solution of their equation of motion. A determination of the effecti

A. Latz

A formally exact set of equations is derived for the description of nonequilibrium phenomena in classical liquids and glasses. With the help of a non equilibrium projection operator formalism, the correlation functions and fluctuation propagators are expressed in terms of memory functions and time dependent collective frequencies. This formally exact set of

John Cardy

It is argued that logarithmic factors multiplying power law behavior are to be expected at or near non-mean field critical points of systems with short-range interactions described theoretically by any kind of n -> 0 limit, in which the effective free energy vanishes. Explicit examples are given for quenched random ferromagnets, polymer statistics and percol

Walter Kob

In these lectures, which were presented at &#34;Soft and Fragile Matter, Nonequilibrium Dynamics, Metastability and Flow&#34; University of St. Andrews, 8 July - 22 July, 1999, I give an introduction to the physics of supercooled liquids and glasses and discuss some computer simulations done to investigate these systems.

M. B. Hastings

We consider the dielectric breakdown model in the limit $η\to 0^+$. A differential equation describing the surface growth is derived; this equation is KPZ plus a term causing linear instability, and includes a short-distance regularization similar to a viscosity. The equation exhibits an interesting dynamics in terms of poles, permitting us to derive a large

M. V. Entin, G. M. Entin

The electrostatics of 2D system with complicated inner boundary is studied. The object which we call &#34;monster&#34; is built by an iterative process of multiple conformal mapping of the circle exterior. The procedure leads to the figures built from circle with branching curved cuts (i), to the multiple tangential near-round circles (ii) and the Mandelbrot

K. Kikoin, Y. Avishai

Anderson impurity model for semiconductor quantum dot is extended to take into account both particle and hole branches of charge excitations. It is shown that in dots with even number of electrons where the Kondo effect is absent in the ground state, novel midgap excitonic states emerge in the energy spectrum due to Kondo-type shake-up processes. The relevan

Mordecai-Mark Mac Low, Ralf Klessen, Fabian Heitsch

We review how supersonic turbulence can both prevent and promote the collapse of molecular clouds into stars. First we show that decaying turbulence cannot significantly delay collapse under conditions typical of molecular clouds, regardless of magnetic field strength so long as the fields are not supporting the cloud magnetohydrostatically. Then we review p

R. J. Reynolds, L. M. Haffner, S. L. Tufte

Spatial variations of the [S II]/H-Alpha and [N II]/H-Alpha line intensity ratios observed in the gaseous halo of the Milky Way and other galaxies are inconsistent with pure photoionization models. They appear to require a supplemental heating mechanism that increases the electron temperature at low densities n_e. This would imply that in addition to photoio

E. Branchini, I. Zehavi, M. Plionis, A. Dekel

The density and velocity fields as extracted from the Abell/ACO clusters are compared to the corresponding fields recovered by the POTENT method from the Mark~III peculiar velocities of galaxies. In order to minimize non-linear effects and to deal with ill-sampled regions we smooth both fields using a Gaussian window with radii ranging between $12 - 20\hmpc$

B. T. Soifer, G. Neugebauer, K. Matthews, E. Egami

Observations of ultraluminous infrared galaxies (ULIRGs) with an achieved resolution approaching the diffraction limit in the mid-infrared from 8 - 25 $μ$m using the Keck Telescopes are reported. We find extremely compact structures, with spatial scales of $< 0.3&#39;&#39;$ (diameter) in six of the seven ULIRGs observed. These compact sources emit between 30

D. Barret, J. F. Olive, L. Boirin, C. Done

We report on Rossi X-ray Timing Explorer observations of four type I X-ray bursters; namely 1E1724-3045, GS1826-238, SLX1735-269 and KS1731-260. The first three were in a low state (LS) whereas KS1731-260 was in a high state. The LS sources have very similar power spectra, displaying high frequency noise up to \~200 Hz. For KS1731-260, its power spectrum is

Amina Helmi, Simon D. M. White, P. Tim de Zeeuw, and HongSheng Zhao

It is now generally believed that galaxies were built up through gravitational amplification of primordial fluctuations and the subsequent merging of smaller precursor structures. The stars of the structures that assembled to form the Milky Way should now make up much or all of its bulge and halo, in which case one hopes to find &#34;fossil&#34; evidence for

R. Durrer, P. G. Ferreira, T. Kahniashvili

We derive an expression for the angular power spectrum of cosmic microwave background anisotropies due to gravity waves generated by a stochastic magnetic field and compare the result with current observations; we take into account the non-linear nature of the stress energy tensor of the magnetic field. For almost scale invariant spectra, the amplitude of th

Sabrina De Grandi, Silvano Molendi

We present results from a BeppoSAX observation of the cooling flow cluster PKS 0745-191 (z=0.1028). By performing spatially resolved spectroscopy, we find that the projected temperature profile is consistent with being constant. We can rule out, at more than the 99% confidence level, a temperature decrement of a factor 2 when going from the cluster core out

S. A. Trushkin

The extended radio source G16.2-2.7 is detected as a new previously uncataloged Galactic supernova remnant. Its non-thermal radio spectrum has spectral index alpha=-0.51, with S_nu(1 GHz) = 2.08 Jy, as being measured with the RATAN-600 radio telescope. The NRAO VLA Sky Survey (NVSS) map at 1.4 GHz shows a shell-like bilateral structure. The similar smoothed

R. Kaufmann, N. Straumann

We study with semi-analytical methods the statistics of pronounced arcs caused by lensing of galaxies by foreground galaxy clusters. For the number density and redshift distribution of rich clusters we use Press-Schechter theory, normalized on the basis of empirical data. For the background sources we make use of observational results in the Hubble Deep Fiel

T. Ott, W. Hackenberg, S. Rabien, A. Eckart

The ALFA laser subsystem uses a 4 watt continuous wave laser beam to produce an artificial guide star in the mesospheric sodium layer as a reference for wavefront sensing. In this article we describe the system design, focusing on the layout of the beam relay system. It consists of seven mirrors, four of which are motor-controlled in closed loop operation ac

J. M. Ibanez, M. A. Aloy, J. A. Font, J. M. Marti

Our contribution concerns with the numerical solution of the 3D general relativistic hydrodynamical system of equations within the framework of the 3+1 formalism. We summarize the theoretical ingredients which are necessary in order to build up a numerical scheme based on the solution of local Riemann problems. Hence, the full spectral decomposition of the J

P. Ventura, F. D&#39;Antona, I. Mazzitelli

We present the first quantitative results explaining the presence in the Large Magellanic Cloud of some asymptotic giant branch stars that share the properties of lithium rich carbon stars. A self-consistent description of time-dependent mixing, overshooting, and nuclear burning was required. We identify a narrow range of masses and luminosities for this pec

R. P. Fender

I compare the properties of radio emission from neutron star and black hole X-ray binaries. In both transient and persistent systems the ratio of X-ray : radio fluxes is comparable for (low field) neutron stars and black holes. It appears that, broadly speaking, the disc : jet coupling is independent of the nature of the accretor, (except for X-ray pulsars w

S. Rabien, T. Ott, W. Hackenberg, A. Eckart

The optimal performance of adaptive optics systems can only be maintained if the wavefront reference is bright and compact. Experience has shown that both of these important criteria are remarkably difficult to achieve with laser guide stars, and this contribution gives an account of the methods by which ALFA attempts to reach them. First, the production of

R. Davies, A. Eckart, W. Hackenberg, T. Ott

The importance of laser guide stars to the practical usefulness of adaptive optics cannot be understated, and yet there are very few working systems. This contribution discusses the current status of the ALFA laser guide star, with regard to the particular difficulties encountered while observing as well as both the expected performance and that so far achie

R. T. Gangadhara, Y. Gupta, D. R. Lorimer

To study the structure of emission beam, we have analysed the single pulse data of PSR B0329+-54 at 325 and 606 MHz. In order to unambiguously detect the weak emission components, we have developed a new data analysis technique, which we term ``window-thresholding&#39;&#39;. By applying this technique to the data, we have detected three new emission componen

Bing Zhang, Alice K. Harding

We modify polar cap cascade picture to include the ICS of the higher generation pairs. In such a ``full-cascade&#39;&#39; scenario, not only the perpendicular portion of the energy of the pairs goes to high energy radiation via SR, but the parallel portion of the energy of the pairs can also contribute to high energy emission via ICS with the soft thermal ph

K. Xilouris, D. R. Lorimer

We have extensively searched for periodic signals in the area of the soft gamma-ray repeater SGR 1900+14, at 430 and 1410 MHz with the Arecibo telescope. Our observations did not reveal the 5.16-s periodicity reported for the magnetar down to a 430-MHz flux density limit of 150 uJy. During the search we discovered a 226-ms radio pulsar, PSR J1907+0918. The p

Bing Zhang, Alice K. Harding

We modify the conventional curvature radiation (inverse Compton scattering) + synchrotron radiation polar cap cascade model by including the inverse Compton scattering of the higher generation pairs. Within the framework of the space-charge-limited-flow acceleration model with frame-dragging proposed by Harding & Muslimov (1998), such a full polar cap cascad

Ivo Souza, Tim Wilkens, Richard M. Martin

We develop the theory and practical expressions for the full quantum-mechanical distribution of the intrinsic macroscopic polarization of an insulator in terms of the ground state wavefunction. The central quantity is a cumulant generating function which yields, upon successive differentiation, all the cumulants and moments of the probability distribution of

N. Tregoures, W. Roberts

The application of the tensor formalism of the heavy quark effective theory (HQET) at leading order to strong decays of heavy hadrons is presented. Comparisons between experimental and theoretical predictions of ratios of decay rates for B mesons, D mesons and kaons are given. The application of HQET to strange mesons presents some encouraging results. The s

L. Leuzzi, G. Parisi

A particular, two-dimensional, tiling model, composed by the so called Wang tiles has been studied at finite temperature by Monte Carlo numerical simulations. In absence of any thermal bath the Wang tiles give the opportunity of building a very large number of non-periodic tilings. We can construct a local Hamiltonian such that only perfectly matched tilings

Eric R. Tittley, H. M. P. Couchman, F. R. Pearce

We present a study of hydrodynamic drag forces in smoothed particle simulations. In particular, the deceleration of a resolution-limited cold clump of gas moving through a hot medium is examined. It is found that the drag for subsonic velocities exceeds that predicted by simple physical approximations. This is shown to be a result of the hydrodynamical metho

G. Schmidt, L. W. Molenkamp, A. T. Filip, B. J. van Wees

We have calculated the spin-polarization effects of a current in a two dimensional electron gas which is contacted by two ferromagnetic metals. In the purely diffusive regime, the current may indeed be spin-polarized. However, for a typical device geometry the degree of spin-polarization of the current is limited to less than 0.1%, only. The change in device

J. E. Nelson, R. F. Picken

We describe an approach to the quantisation of (2+1)-dimensional gravity with topology R x T^2 and negative cosmological constant, which uses two quantum holonomy matrices satisfying a q-commutation relation. Solutions of diagonal and upper-triangular form are constructed, which in the latter case exhibit additional, non-trivial internal relations for each h

G. G. Adamian, N. V. Antonenko, E. A. Cherepanov, A. K. Nasirov

The synthesis of superheavy elements is analysed within the dinuclear system concept of compound nucleus formation. The perspectives for using radioactive beams in complete fusion reactions are discussed.

Yu. V. Palchikov, G. G. Adamian, N. V. Antonenko, W. Scheid

For Lindblad's master equation of open quantum systems with a general quadratic form of the Hamiltonian, the propagator of the density matrix is analytically calculated by using path integral techniques. The time-dependent density matrix is applied to nuclear barrier penetration in heavy ion collisions with inverted oscillator and double-well potentials. The

M. Boglione, E. Leader

It is shown that the Collins mechanism explanation of the transverse single-spin asymmetries in p^{\uparrow} p -> πX leads to a transversely polarized d quark density Delta_T d(x) which violates the Soffer bound when one uses several standard forms for the longitudinally polarized d quark density Delta d(x) obtained from polarized deep inelastic scattering.