February 2003 arXiv papers — page 17

I. C. Cloet, D. B. Leinweber, A. W. Thomas

Theoretical predictions for the magnetic moments of the physical Delta baryons are extracted from lattice QCD calculations. We utilize finite-range regulated effective field theory that is constructed to have the correct Dirac moment mass dependence in the region where the up and down quark masses are heavy. Of particular interest is the chiral nonanalytic b

Andrei V. Frolov, Valeri P. Frolov

We discuss properties of a 4-dimensional Schwarzschild black hole in a spacetime where one of the spatial dimensions is compactified. As a result of the compactification the event horizon of the black hole is distorted. We use Weyl coordinates to obtain the solution describing such a distorted black hole. This solution is a special case of the Israel-Khan me

L. Anguelova, P. Langfelder

We extend the method of calculation of propagators in maximally symmetric spaces (Minkowski, dS, AdS and their Euclidean versions) in terms of intrinsic geometric objects to the case of massive spin 3/2 field. We obtain the propagator for arbitrary space-time dimension and mass in terms of Heun's function, which is a generalization of the hypergeometric

Shina Tan, K. Levin

We address those puzzling experiments in underdoped high $T_c$ superconductors which have been associated with normal state "vortices" and show these data can be understood as deriving from preformed pairs with onset temperature $T^* > T_c$. For uncorrelated bosons in small magnetic fields, and arbitrary $T^*/T_c$, we present the exact contribution t

Christopher A. Fuchs, Masahide Sasaki

This article is an introduction to quant-ph/0302092. We propose to quantify how "quantum" a set of quantum states is. The quantumness of a set is the worst-case difficulty of transmitting the states through a classical communication channel. Potential applications of this measure arise in quantum cryptography, where one might like to use an alphabet

Niels Emil Jannik Bjerrum-Bohr

An extensive number of numerical computations of energy 1/$N$ series using a recursive Taylor series method are presented in this paper. The series are computed to a high order of approximation and their behaviour on increasing the order of approximation is examined.

A. K. Popov, V. V. Kimberg, Thomas F. George

We have developed a theory of three-pulse coherent control of photochemical processes. It is based on adiabatic passage and quantum coherence and interference attributed to the lower-lying dissociation continuum and excited upper discrete states, which are otherwise not connected to the ground state by one-photon transitions. Novel opportunities offered by t

Kazuyuki Fujii

In this paper we propose a Hamiltonian of the n-level system by making use of generalized Pauli matrices.

H. De Raedt, V. V. Dobrovitski

Computer simulations of decoherence in quantum spin systems require the solution of the time-dependent Schrodinger equation for interacting quantum spin systems over extended periods of time. We use exact diagonalization, Chebyshev polynomial technique, four Suzuki-formula algorithms, and the short-iterative-Lanczos method to solve a simple model for decoher

Claus O. Wilke

In competition experiments between two RNA viruses of equal or almost equal fitness, often both strains gain in fitness before one eventually excludes the other. This observation has been linked to the Red Queen effect, which describes a situation in which organisms have to constantly adapt just to keep their status quo. I carried out experiments with digita

Palash B. Pal

We deduce the most general space-time transformation laws consistent with the principle of relativity. Thus, our result contains the results of both Galilean and Einsteinian relativity. The velocity addition law comes as a bi-product of this analysis. We also argue why Galilean and Einsteinian versions are the only possible embodiments of the principle of re

O. E. Aiello, M. A. A. da Silva

In this work, we revisit the basic reproduction rate $\mathcal{R}_{0}$ definition for analysis of epidemic-non-epidemic phases describing the dynamics of the discrete stochastic version of the epidemic $SIR$ model based on the Master Equation formalism. One shows that it is a very precise and efficient way to determine the epidemic threshold; using its most

E. M. Darwish, H. Arenhoevel, M. Schwamb

The contribution of incoherent single pion photoproduction to the spin response of the deuteron, i.e., the asymmetry of the total photoabsorption cross section with respect to parallel and antiparallel spins of photon and deuteron, is calculated over the region of the $Δ$-resonance with inclusion of final state $NN$- and $πN$-rescattering. Sizeable effects,

Prashant Shukla

We reexamine the Glauber model and calculate the total reaction cross section as a function of energy in the low and intermediate energy range, where many of the corrections in the model, are effective. The most significant effect in this energy range is by the modification of the trajectory due to the Coulomb field. The modification in the trajectory due to

C. Keil, H. Lenske

We study the interactions of the octet baryons in a relativistic meson exchange approach connecting free-space and in-medium interactions with those in finite (hyper)nuclei. A short sketch of the model including the relativistic T- and G-matrix and the mapping of the G-matrix onto density dependent vertex functionals in the density dependent relativistic had

V. O. Nesterenko, V. P. Likhachev, P. -G. Reinhard, J. Mesa

Momentum distributions (MD) of deep hole proton states in $^{238}$U are studied paying particular attention to the influence of deformation. Two essentially different mean-field models, Woods-Saxon (WS) and Skyrme-Hartree-Fock with the SkM$^*$ force, are used. Noticeable deviations between the WS and SkM$^*$ results are found. They are mainly due to the diff

B. B. Back, PHOBOS Collaboration

We present transverse momentum distributions of charged hadrons produced in Au+Au collisions at sqrt(s_NN) = 200 GeV. The spectra were measured for transverse momenta p_T from 0.25 to 4.5 GeV/c in a rapidity range of 0.2 < y_pi < 1.4. The evolution of the spectra is studied as a function of collision centrality, from 65 to 344 participating nucleons. The res

P. Kowina, M. Wolke, H. -H. Adam, A. Budzanowski

The associated strangeness dissociation at threshold has been studied at the COSY-11 facility measuring the hyperon - and the K+K- meson pair production. Measurements of the near threshold Lambda and Sigma0 production via the pp -> pK+ Lambda / Sigma0 reaction at COSY-11 have shown that the Lambda / Sigma0 cross section ratio exceeds the value at high excess

S. Tomsovic, D. Ullmo, T. Nagano

Within random matrix theory, the statistics of the eigensolutions depend fundamentally on the presence (or absence) of time reversal symmetry. Accepting the Bohigas-Giannoni-Schmit conjecture, this statement extends to quantum systems with chaotic classical analogs. For practical reasons, much of the supporting numerical studies of symmetry breaking have bee

Philipp Hövel, Joshua E. S. Socolar

We generalize a known analytical method for determining the stability of periodic orbits controlled by time-delay feedback methods when latencies associated with the generation and injection of the feedback signal cannot be ignored. We discuss the case of extended time-delay autosynchronization (ETDAS) and show that nontrivial qualitative features of the dom

M. A. I. Khan, A. Pumir, J. C. Vassilicos

As three particles are advected by a turbulent flow, they separate from each other and develop non trivial geometries, which effectively reflect the structure of the turbulence. We investigate here the geometry, in a statistical sense, of three Lagrangian particles advected, in 2-dimensions, by Kinematic Simulation (KS). KS is a Lagrangian model of turbulent

Stephan I. Tzenov, Ronald C. Davidson

The renormalization group method is applied to the study of discrete dynamical systems. As a particular example, the Henon map is considered as applied to describe the transverse betatron oscillations in a cyclic accelerator or storage ring possessing a FODO-cell structure with a single thin sextupole. A powerful renormalization group method is developed tha

G. M. Pritula, V. E. Vekslerchik

Taking the standard zero curvature approach we derive an infinite set of integrable equations, which taken together form the negative Volterra hierarchy. The resulting equations turn out to be nonlocal, which is usual for the negative flows. However, in some cases the nonlocality can be eliminated. Studying the combined action of both positive (classical) an

Joel Smoller, Blake Temple

We construct exact, entropy satisfying shock wave solutions of the Einstein equations for a perfect fluid which extend the Oppeheimer-Snyder (OS) model to the case of non-zero pressure, {\it inside the Black Hole}. These solutions put forth a new Cosmological Model in which the expanding Friedmann-Robertson-Walker (FRW) universe emerges from the Big Bang wit

F. Bernasconi, G. M. Graf, D. Hasler

We derive the first six coefficients of the heat kernel expansion for the electromagnetic field in a cavity by relating it to the expansion for the Laplace operator acting on forms. As an application we verify that the electromagnetic Casimir energy is finite.

Laszlo Erdos, Manfred Salmhofer, Horng-Tzer Yau

We give a nonrigorous derivation of the nonlinear Boltzmann equation from the Schrodinger evolution of interacting fermions. The argument is based mainly on the assumption that a quasifree initial state satisfies a property called restricted quasifreeness in the weak coupling limit at any later time. By definition, a state is called restricted quasifree if t

Dorin Ervin Dutkay

We define the local trace function for subspaces of $\ltworn$ which are invariant under integer translation. Our trace function contains the dimension function and the spectral function defined by Bownik and Rzeszotnik and completely characterizes the given translation invariant subspace. It has properties such as positivity, additivity, monotony and some fo

Dorin Ervin Dutkay

In connection to wavelet theory, we describe the peripheral spectrum of the transfer operator. The solution involves the analysis of certain representations of the algebra generated by two unitaries $U$ and $T$ that satisfy the commutation relation $UTU^{-1}=T^N$.

Carlo Mantegazza, Matteo Novaga, Vincenzo Maria Tortorelli

We consider the motion by curvature of a network of smooth curves with multiple junctions in the plane, that is, the geometric gradient flow associated to the length functional. Such a flow represents the evolution of a two--dimensional multiphase system where the energy is simply the sum of the lengths of the interfaces, in particular it is a possible model

Marco Fontana, K. Alan Loper

In 1994, Matsuda and Okabe introduced the notion of semistar operation. This concept extends the classical concept of star operation (cf. for instance, Gilmer&#39;s book \cite{G}) and, hence, the related classical theory of ideal systems based on the works by W. Krull, E. Noether, H. Prüfer and P. Lorenzen from 1930&#39;s. In \cite{FL1} and \cite{FL2} the cu

D. V. Chistyakov

Fractal measures of images of continuous maps from the set of p-adic numbers Qp into complex plane C are analyzed. Examples of &#34;anomalous&#34; fractals, i.e. the sets where the D-dimensional Hausdorff measures (HM) are trivial, i.e. either zero, or sigma-infinite (D is the Hausdorff dimension (HD) of this set) are presented. Using the Caratheodory constr

Frank Pacard, Manuel Ritoré

We construct solutions of the Cahn-Hilliard equation whose nodal set converges to a given constant mean curvature hypersurface in a Riemannian manifold.

Simona Dabuleanu, Vicentiu Radulescu

We prove an existence result for a class of Dirichlet boundary value problems with discontinuous nonlinearity and involving a Leray-Lions operator. The proof combines monotonicity methods for elliptic problems, variational inequality techniques and basic tools related to monotone operators.

Chandan Singh Dalawat

A telegraphic survey of some of the standard results and conjectures about the set $C({\bf Q})$ of rational points on a smooth projective absolutely connected curve $C$ over ${\bf Q}$.

Chandan Singh Dalawat

Colliot-Th{é}l{è}ne has determined the Chow group of zero-cycles on a Ch{â}telet surface X defined over a finite extension K of the field of p-adic numbers (p an odd prime) when X is split by an unramified extension of K. Using similar techniques, we extend this calculation to the ramified case, simplifying his result in the process. We also determine how th

I. M. Duursma

We give an explicit description of all 168 quartic curves over the field of two elements that are isomorphic to the Klein curve over an algebraic extension. Some of the curves have been known for their small class number, others for attaining the maximal number of rational points.

L J P Kilford

Let $τ$ be the primitive Dirichlet character of conductor 4, let $χ$ be the primitive even Dirichlet character of conductor 8 and let $k$ be an integer. Then the $U_2$ operator acting on cuspidal overconvergent modular forms of weight $2k+1$ and character $τ$ has slopes in the arithmetic progression ${2,4,...,2n,...}$, and the $U_2$ operator acting on cuspid

Victor V. Batyrev, Evgeny N. Materov

Using Cayley trick, we define the notions of mixed toric residues and mixed Hessians associated with $r$ Laurent polynomials $f_1,...,f_r$.We conjecture that the values of mixed toric residues on the mixed Hessians are determined by mixed volumes of the Newton polytopes of $f_1,...,f_r$. Using mixed toric residues, we generalize our Toric Residue Mirror Conj

J. Colliander, C. Kenig, G. Staffilani

In this paper we obtain local in time existence and (suitable) uniqueness and continuous dependence for the KP-I equation for small data in the intersection of the energy space and a natural weighted $L^{2}$ space.

Lyonell S. Boulton

Let $H$ be the discrete Schrödinger operator $Hu(n):=u(n-1)+u(n+1)+v(n)u(n)$, $u(0)=0$ acting on $l^2({\bf Z}^+)$ where the potential $v$ is real-valued and $v(n)\to 0$ as $n\to \infty$. Let $P$ be the orthogonal projection onto a closed linear subspace $L \subset l^2({\bf Z}^+)$. In a recent paper E.B. Davies defines the second order spectrum ${\rm Spec}_2(

Sultan Catto

An approximate hadronic symmetry based on spin and flavor independence and broken by spin and mass dependent terms is shown to follow from QCD. This symmetry justifies the SU(6) classification scheme, but is more general in allowing its supersymmetric extension based on a diquark-antiquark symmetry. It will be shown that the same supersymmetry is also implie

David E. Crooks, Nick Evans

We describe a ten dimensional supergravity geometry which is dual to a gauge theory that is non-supersymmetric Yang Mills in the infra-red but reverts to $N$=4 super Yang Mills in the ultra-violet. A brane probe of the geometry shows that the scalar potential of the gauge theory is stable. We discuss the infra-red behaviour of the solution. The geometry desc

Cesar Gomez, Juan Jose Manjarin

We study the dyon electric charge of D6-branes as eleven dimensional KK-monopoles. We observe that the dyon charge is intimately related with the existence of gauge connections and antisymmetric fields on the brane world volume.

Vladislav Popkov, Gunter Schuetz

A set of Markov processes corresponding to systems of hard-core particles interacting along the line are shown to be solvable via a dynamic matrix product ansatz (DMPA). We show that quantum spin Hamiltonians can be treated by the DMPA as well, and demonstrate how the DMPA, originally formulated for systems with open ends, works for periodic systems.

Paul A. Pearce, Leung Chim, Changrim Ahn

We consider the massless tricritical Ising model M(4,5) perturbed by the thermal operator in a cylindrical geometry and apply integrable boundary conditions, labelled by the Kac labels (r,s), that are natural off-critical perturbations of known conformal boundary conditions. We derive massless thermodynamic Bethe ansatz (TBA) equations for all excitations by

Marek Rogatko

We prove the uniqueness theorem for static higher dimensional charged black holes spacetime containing an asymptotically flat spacelike hypersurface with compact interior and with both degenerate and non-degenerate components of the event horizon.

Sultan Catto

We show that with every classical system possessing first class constraints that form a natural Lie algebra, we can associate a superalgebra that admits the constraint Lie algebra as a subalgebra. An odd generator of this superalgebra that commutes with the constraints is shown to be the BRST operator whose form follows from a non linear coset representation

Antoine Van Proeyen

We give an elementary introduction to the structure of supergravity theories. This leads to a table with an overview of supergravity and supersymmetry theories in dimensions 4 to 11. The basic steps in constructing supergravity theories are considered: determination of the underlying algebra, the multiplets, the actions, and solutions. Finally, an overview i

R. Vogt, T. D. Gutierrez

Strange baryons have long been known to exhibit a leading particle effect. A recent comparison of $Ξ^-$ production in $π^-$, $n$, and $Σ^-$ interactions with nuclei show this effect clearly. These data are supplemented by earlier measurements of $Ξ^-$ and $Ω$ production by a $Ξ^-$ beam. We calculate the $Ξ^-$ and $Ω$ $x_F$ distributions and nuclear dependenc

Ana M. Curiel, Maria J. Herrero, David Temes

We consider a plausible scenario in the Minimal Supersymmetric Standard Model (MSSM) where all the genuine supersymmetric (SUSY) particles are heavier than the electroweak scale. In this situation, indirect searches via their radiative corrections to low energy observables are complementary to direct searches, and they can be crucial if the SUSY masses are a

Bing He, Hu Li, C. M. Shakin, Qing Sun

The Euclidean-time hadronic current correlation functions, $G_P(τ, T)$ and $G_V(τ, T)$, of pseudoscalar and vector currents have recently been calculated in lattice simulations of QCD and have been used to obtain the corresponding spectral functions. We have used the Nambu-Jona-Lasinio (NJL) model to calculate such spectral functions, as well as the Euclidea

G. Bozzi, S. Catani, D. de Florian, M. Grazzini

We consider the transverse-momentum (q_T) distribution of Higgs bosons produced at hadron colliders. We use a formalism that uniformly treats both the small-q_T and large-q_T regions in QCD perturbation theory. At small q_T (q_T << M_H, M_H being the mass of the Higgs boson), we implement an all-order resummation of logarithmically-enhanced contributions up

Johan Hansson

This is the reply to a comment by Andreas Aste [hep-th/0302103] on a previous article of mine in Can.J.Phys. The counter-arguments used by Aste utilize a mathematical limit without physical meaning. We still contend that in QCD, the particles ``gluons&#39;&#39; and ``quarks&#39;&#39; are merely artifacts of an approximation method (the perturbative expansion

G. P. Vacca

The next-to-leading corrections to the jet vertex which is relevant for the Mueller-Navelet jets production in hadronic collisions and for the forward jet cross section in lepton-hadron collisions are presented in the context of a k_t factorizazion formula which resums the leading and next-to-leading logarithms of the energy.

Tetsuo Nishikawa, Osamu Morimatsu, Yoshimasa Hidaka

We study the so-called `` sunset diagram&#39;&#39;, which is one of two-loop self-energy diagrams, for scalar field theories at finite temperature. For this purpose, we first find the complete expression of the bubble diagram, the one-loop subdiagram of the sunset diagram, for arbitrary momentum. We calculate the temperature independent part and dependent pa

Jian-wei Mei, Zhi-zhong Xing

In view of the quark mass hierarchy and in the assumption of the up-down parallelism, we derive two phenomenologically-favored patterns of Hermitian quark mass matrices from the quark flavor mixing matrix. We compare one of them with two existing {\it Ans$\it\ddot{a}$tze} proposed by Rosner and Worah and by Roberts {\it et al}, and find that only the latter

A. V. Berezhnoy, V. V. Kiselev, A. K. Likhoded

In the framework of the constituent quark model the exclusive pair production of the charmed mesons in the photon-photon interaction is calculated. The comparison of these predictions with the ones of the heavy quark effective theory is performed. It is shown, that the light valence quark of D-meson plays the essential role not only in the hadronization proc

Gouranga C. Nayak, Ming X. Liu, Fred Cooper

We compute \frac{dσ}{dp_T} of the J/ψproduction in pp collisions at RHIC at \sqrt s = 500 and 200 GeV by using both the color octet and singlet models in the framework of non-relativistic QCD. The J/ψwe compute here includes the direct J/ψfrom the partonic fusion processes and the J/ψcoming from the radiative decays of χ_J&#39;s both in the color octet and s

M. Paulini

After a five year upgrade period, the CDF detector located at the Fermilab Tevatron Collider is back in operation taking high quality data with all subsystems functional. We report on the status of the CDF experiment in Run II and discuss the start-up of the Tevatron accelerator. First physics results from CDF are presented. We also discuss the prospects for

The BABAR Collaboration, B. Aubert

We present a study of the decays B0->D_s(*)+D*-, using 20.8 fb-1 of e+e- annihilation data recorded with the BABAR detector. The analysis is conducted with a partial reconstruction technique, in which only the D_s(*)+ and the soft pion from the D*- decay are reconstructed. We measure the branching fractions BR(B0->D_s+D*-) = (1.03 +/- 0.14 +/- 0.13 +/- 0.26)

Bartolome Coll

The object of this contribution is twofold. On one hand, it rises some general questions concerning the definition of the electromagnetic field and its intrinsic properties, and it proposes concepts and ways to answer them. On the other hand, and as an illustration of this analysis, a set of quadratic equations for the electromagnetic field is presented, ric

Joachim Moortgat, Jan Kuijpers

One of the possible sources of gamma-ray bursts are merging, compact neutronstar binaries. More than 90% of the binding energy of such a binary is released in the form of gravitational waves (GWs) in the last few seconds of the spiral-in phase before the formation of a black hole. In this article we investigate whether a fraction of this GW-energy is transfe

G. Lambiase

Loop quantum gravity theory incorporates a new scale length ${\cal L}$ which induces a Lorentz invariance breakdown. This scale can be either an universal constant or can be fixed by the momentum of particles (${\cal L}\sim p^{-1}$). Effects of the scale parameter ${\cal L}$ and helicity terms occurring in the dispersion relation of fermions are reviewed in

M. Novello, S. E. Perez Bergliaffa

We introduce the concept of effective geometry by studying several systems in which it arises naturally. As an example of the power and conciseness of the method, it is shown that a flowing dielectric medium with a linear response to an external electric field can be used to generate an analog geometry that has many of the formal properties of a \Sch black h

Nathan D. George, Adrian P. Gentle, Arkady Kheyfets, Warner A. Miller

Standard techniques of canonical gravity quantization on the superspace of 3--metrics are known to cause insurmountable difficulties in the description of time evolution. We forward a new quantization procedure on the superspace of true dynamic variables -- geometrodynamic quantization. This procedure takes into account the states that are ``off-shell&#39;&#

Aaron Harwood

Use of Peer-to-Peer (P2P) service networks introduces a new communication paradigm because peers are both clients and servers and so each peer may provide/request services to/from other peers. Empirical studies of P2P networks have been undertaken and reveal useful characteristics. However there is to date little analytical work to describe P2P networks with

R. Buyya, S. Date, Y. Mizuno-Matsumoto, S. Venugopal

The lack of computational power within an organization for analyzing scientific data, and the distribution of knowledge (by scientists) and technologies (advanced scientific devices) are two major problems commonly observed in scientific disciplines. One such scientific discipline is brain science. The analysis of brain activity data gathered from the MEG (M

Ding Choon Hoong, Rajkumar Buyya

With the advent of the Internet, search engines have begun sprouting like mushrooms after a rainfall. Only in recent years, have developers become more innovative, and came up with guided searching facilities online. The goals of these applications are to help ease and guide the searching efforts of a novice web user toward their desired objectives. A number

Michael N. Leuenberger, Daniel Loss, Michael E. Flatte, D. D. Awschalom

In this paper we show that the discrete Fourier transform can be performed by scattering a coherent particle or laser beam off a two-dimensional potential that has the shape of rings or peaks. After encoding the initial vector into the two-dimensional potential, the Fourier-transformed vector can be read out by detectors surrounding the potential. The wavele

E. H. Rezayi, T. Jungwirth, A. H. MacDonald, F. D. M. Haldane

Opposite spin Landau levels in a quantum well can be brought into coincidence by tilting the magnetic field away from normal orientation. We demonstrate that the magnetotransport anomaly at integer filling factors that was recently discovered by Pan {\it et al} is due to such a coincidence. By performing exact diagonalization calculations using microscopical

Alain Comtet, Jean Desbois

We consider a planar Brownian motion starting from $O$ at time $t=0$ and stopped at $t=1$ and a set $F= \{OI_i ; i=1,2,..., n\}$ of $n$ semi-infinite straight lines emanating from $O$. Denoting by $g$ the last time when $F$ is reached by the Brownian motion, we compute the probability law of $g$. In particular, we show that, for a symmetric $F$ and even $n$

L. Sudheendra, C. N. R. Rao

All the three series of manganates showsaturation magnetization characteristic of ferromagnetism, with the ferromagnetic Tc decreasing with increasing in x up to a critical value of x, xc (xc = 0.6, 0.3, 0.2 respectively for Nd, Gd, Y). For x > xc, the magnetic moments are considerably smaller showing a small increase around TM, the value of TM decreasing sl

T. Brandes, N. Lambert

We investigate the transport and coherence properties of a double quantum dot coupled to a single damped boson mode. Our numerically results reveal how the properties of the boson distribution can be steered by altering parameters of the electronic system such as the energy difference between the dots. Quadrature amplitude variances and the Wigner function a

O. Carrillo, M. Ibanes, J. Garcia-Ojalvo, J. Casademunt

We discuss intrinsic noise effects in stochastic multiplicative-noise partial differential equations, which are qualitatively independent of the noise interpretation (Ito vs. Stratonovich), in particular in the context of noise-induced ordering phase transitions. We study a model which, contrary to all cases known so far, exhibits such ordering transitions w

R. G. Goodrich, David P. Young, Donavan Hall, Z. Fisk

We have measured the magnetic field dependence of the paramagnetic to the field-induced high temperature antiferroquadrupolar magnetically ordered phase transition is CeB6 from 0 to 60 T using a variety of techniques. It is found that the field-dependent phase separation line becomes re-entrant above 35 T and below 10 K. Measurements of resonant ultra-sound,

A. Rufenacht, P. Chappatte, S. Gariglio, Ch. Leemann

We have developed an approach to grow high quality ultrathin films of La$_{2-x}$Sr$_x$CuO$_{4}$ with molecular beam epitaxy, by adding a homoepitaxial buffer layer in order to minimize the degradation of the film structure at the interface. The advantage of this method is to enable a further reduction of the minimal thickness of a superconducting La$_{1.9}$S

R. N. Onody, P. A. de Castro

We propose a kind of Bak-Sneppen dynamics as a general optimization technique to treat magnetic systems. The resulting dynamics shows self-organized criticality with power law scaling of the spatial and temporal correlations. An alternative method of the extremal optimization is also analyzed here. We provided a numerical confirmation that, for any possible

Romain Bel, Kamran Behnia, Helmut Berger

The first study of Nernst effect in NbSe$_2$ reveals a large quasi-particle contribution with a magnitude comparable and a sign opposite to the vortex signal. Comparing the effect of the Charge Density Wave(CDW) transition on Hall and Nernst coefficients, we argue that this large Nernst signal originates from the thermally-induced counterflow of electrons an

A. Moura, V. I. Yukalov

Acoustic emission before the failure of heterogeneous materials is studied as a function of applied hydrostatic pressure. A formula for the energy release is suggested, which is valid in the whole diapason of pressures, from zero to the critical pressure of rupture. This formula is obtained by employing the extrapolation technique of the self-similar approxi

K. B. Efetov, A. Tschersich

We consider effects of Coulomb interaction in a granular normal metal at not very low temperatures suppressing weak localization effects. In this limit calculations with the initial electron Hamiltonian are reduced to integrations over a phase variable with an effective action, which can be considered as a bosonization for the granular metal. Conditions of t

E. Schachinger, J. P. Carbotte

In a d-wave superconductor with elastic impurity scattering, not all the available optical spectral weight goes into the condensate at zero temperature, and this leads to residual absorption. We find that for a range of impurity parameters in the intermediate coupling regime between Born (weak) and unitary (strong) limit, significant oscillator strength rema

L. S. Isaev, A. P. Protogenov

The structures of order parameters which determine the bounds of the phase states in the framework of the $CP^{1}$ Ginzburg-Landau model were considered. Using the formulation of this model in terms of the gauged order parameters (the unit vector ${\bf n}$, density $ρ^{2}$ and momentum of particles ${\bf c}$) we found that some universal properties of phases

L. S. Isaev, A. P. Protogenov

We consider the form of the charge density nano-scale configurations in underdoped states of planar antiferromagnetic insulators in the framework of a soft variant of Faddeev-Niemi model. It is shown that there is such a level of doping and the temperature range, where charge density distributions in the form of closed quasi-one-dimensional structures are mo

L. Van Look, S. Raedts, R. Jonckheere, V. V. Moshchalkov

We investigate anisotropy in the vortex pinning in thin superconducting films with a square array of rectangular submicron holes (&#34;antidots&#34;). The size of the antidots is chosen in such a way that it corresponds to a saturation number n_s=1, i.e. each antidot can trap at most one flux quantum. Therefore, interstitial vortices, appearing when the magn

O. Bourgeois, A. Frydman, R. C. Dynes

We report on transport and tunneling measurements performed on ultra-thin Pb/Ag (strong coupled superconductor/normal metal) multilayers evaporated by quench condensation. The critical temperature and energy gap of the heterostructures oscillate with addition of each layer, demonstrating the validity of the Cooper limit model in the case of multilayers. We o

A. Sundaresan, Y. Tanaka, A. Iyo, M. Kusunoki

A simple method, fishing high-Tc superconductor thin films out of liquid nitrogen bath by a permanent magnet (field > Hc1) due to the effect of high flux pinning, has been suggested to identify films having high critical current density (Jc > 106 A/cm2 at 77 K) and thus a low microwave surface resistance (Rs). We have demonstrated that a Nd-Fe-B magnet, havi

Alexey V Pan, Sihai Zhou, Huakun Liu, Shixue Dou

We have fabricated a series of iron-sheathed superconducting wires prepared by the powder-in-tube technique from (MgB_2)_{1-x}:(Mg+2B)_x initial powder mixtures taken with different proportions, so that x varies from 0 to 1. It turned out that &#34;ex-situ&#34; prepared wire (x = 0) has considerable disadvantages compared to all the other wires in which &#34

A. P. J. Breu, C. A. Kruelle, I. Rehberg

A novel pattern forming instability in a mixture of a granular material and water in a horizontal rotating drum is experimentally investigated. The particles accumulate in radial symmetric rings separated by pure water. The transition between the homogeneous state and the structured state is hysteretic. The transition point is extrapolated from the growth ra

Philip J. Armitage, Christopher S. Reynolds

We use global magnetohydrodynamic simulations, in a pseudo-Newtonian potential, to investigate the temporal variability of accretion discs around Schwarzschild black holes. We use the vertically-averaged magnetic stress in the simulated disc as a proxy for the rest-frame dissipation, and compute the observed emission by folding this through the transfer func

D. E. Harris, J. A. Biretta, W. Junor, E. S. Perlman

We present Chandra X-ray monitoring of the M87 jet in 2002, which shows that the intensity of HST-1, an optical knot 0.8&#34; from the core, increased by a factor of two in 116 days and a factor of four in 2 yrs. There was also a significant flux decrease over two months, with suggestive evidence for a softening of the spectrum. From this variability behavio

Subhashis Roy

We have studied HI absorption towards three non-thermal filaments (NTFs) Sgr-C, G359.54+0.18 and G359.79+0.17 using the Giant Metrewave Radio Telescope (GMRT). Our study, for the first time, constrains the distance of the Sgr C NTF and the HII region seen associated with the NTF in the sky plane, to within a few hundred parsecs from the Galactic Centre (GC).

R. Mushotzky, E. Figueroa-Feliciano, M. Loewenstein, S. L. Snowden

Using XMM-Newton spatially resolved X-ray imaging spectroscopy we obtain the temperature, density, entropy, gas mass, and total mass profiles for two groups of galaxies out to ~0.3 Rvir (Rvir, the virial radius). Our density profiles agree well with those derived previously, and the temperature data are broadly consistent with previous results but are consid

C. M. Bridge, Pasi Hakala, Mark Cropper, Gavin Ramsay

We apply a new method of eclipse mapping to the light curves of eclipsing polars. The technique aims to locate the bright emission associated with the accretion stream, using a technique that makes the fewest prior assumptions about the location of the accretion stream material. We have obtained data of EP Dra and HU Aqr with the S-Cam 2 superconducting tunn

J. K. Gambill, R. M. Sambruna, G. Chartas, C. C. Cheung

We present the X-ray properties of a sample of 17 radio sources observed with the Chandra X-ray Observatory as part of a project aimed at studying the X-ray emission from their radio jets. In this paper, we concentrate on the X-ray properties of the unresolved cores. The sample includes 16 quasars (11 core-dominated and 5 lobe-dominated) in the redshift rang

Jun&#39;ichi Yokoyama

Using the values of the cosmological parameters obtained from Wilkinson Microwave Anisotropy Probe (WMAP) and the cosmological chemical clock observed by high-redshift quasars, it is shown that star formation should have started by the redshift $z_F > 9.5$, and that $z_F$ is sensitive only to $\omegamz h^2$ in flat $Λ$CDM cosmology.

Michele Cappellari, Yannick Copin

We present new techniques to perform adaptive spatial binning of Integral-Field Spectroscopic (IFS) data to reach a chosen constant signal-to-noise ratio per bin. These methods are required for the proper analysis of IFS observations, but can also be used for standard photometric imagery or any other two-dimensional data. Various schemes are tested and compa

Martin Harwit, Marco Spaans

A prediction of standard inflationary cosmology is that the elemental composition of the medium out of which the earliest stars and galaxies condensed consisted primarily of hydrogen and helium 4He with small admixtures of deuterium, lithium 7Li, and 3He. The most red-shifted quasars, galaxies, and Ly-alpha absorbers currently observed, however, all exhibit

G. D. Chagelishvili, J. -P. Zahn, A. G. Tevzadze, J. G. Lominadze

This paper deals with the problem of hydrodynamic shear turbulence in non-magnetized Keplerian disks. We wish to draw attention to a route to hydrodynamic turbulence which seems to be little known by the astrophysical community, but which has been intensively discussed among fluid dynamicists during the past decade. In this so-called `bypass&#39; concept for

Dean E. McLaughlin, Georges Meylan

Scarpa et al. (2003) have used their new measurements of the line-of-sight velocity dispersion at radii R ~ 30-45 pc in omega Centauri to argue for modifications to Newtonian dynamics (MOND) at low accelerations in the outer reaches of this globular cluster. Alternatively, any such evidence could be taken as an indication of the presence of an extended dark-

Seiji Kameno, Makoto Inoue, Kiyoaki Wajima, Satoko Sawada-Satoh

We report Very-Long-Baseline Array (VLBA) observations at 2.3, 8.4, and 15.4 GHz towards nine GHz-Peaked Spectrum (GPS) sources. One Seyfert 1 galaxy, one Seyfert 2 galaxy, three radio galaxies, and four quasars were included in our survey. We obtained spatial distributions of the Free-Free Absorption (FFA) opacity with milliarcsec resolutions for all source