April 2003 arXiv papers — page 9

Markus Lazar

In this paper we study the twist disclination within the elastoplastic defect theory. Using the stress function method, we found exact analytical solutions for all characteristic fields of a straight twist disclination in an infinitely extended linear isotropic medium. The elastic stress, elastic strain and displacement have no singularities at the disclinat

A. C. Maggs

This article describes Monte-Carlo algorithms for charged systems using constrained updates for the electric field. The method is generalized to treat inhomogeneous dielectric media, electrolytes via the Poisson-Boltzmann equation and considers the problem of charge and current interpolation for off lattice models. We emphasize the differences between this a

E. Nakano, T. Maruyama, T. Tatsumi

A coexistent phase of spin polarization and color superconductivity in high-density QCD is investigated using a self-consistent mean-field method at zero temperature. The axial-vector current stemming from the Fock exchange term of the one-gluon-exchange interaction has a central role to cause spin polarization. The magnitude of spin polarization is determin

Yutaka Sakamura

We propose a useful method for deriving the effective theory for a system where BPS and anti-BPS domain walls coexist. Our method respects an approximately preserved SUSY near each wall. Due to the finite width of the walls, SUSY breaking terms arise at tree-level, which are exponentially suppressed. A practical approximation using the BPS wall solutions is

S. Dickmann

We study the spin relaxation (SR) of a two-dimensional electron gas (2DEG) in the quantized Hall regime and discuss the role of spatial inhomogeneity effects on the relaxation. The results are obtained for small filling factors ($ν\ll 1$) or when the filling factor is close to an integer. In either case SR times are essentially determined by a smooth random

E. Keihanen, H. Kurki-Suonio, T. Poutanen, D. Maino

The destriping technique is a viable tool for removing different kinds of systematic effects in CMB related experiments. It has already been proven to work for gain instabilities that produce the so-called 1/f noise and periodic fluctuations due to e.g. thermal instability. Both effects when coupled with the observing strategy result in stripes on the observ

P. Caban, J. Rembielinski, K. A. Smolinski, Z. Walczak

It is shown that the hypothesis of tachyonic neutrinos leads to the same oscillations effect as if they were usual massive particles. Therefore, the experimental evidence of neutrino oscillations does not distinguish between massive and tachyonic neutrinos.

Claudio A. Scrucca, Marco Serone, Luca Silvestrini

We study higher-dimensional non-supersymmetric orbifold models where the Higgs field is identified with some internal component of a gauge field. We address two important and related issues that constitute severe obstacles towards model building within this type of constructions: the possibilities of achieving satisfactory Yukawa couplings and Higgs potentia

Pietro Faccioli, Thomas A. DeGrand

We perform a study of the non-perturbative dynamics of the light-quark sector of QCD, based on some recent results of lattice simulations with chiral fermions. We analyze some correlators that are designed to probe the Dirac structure of the quark-quark interaction at different scales. We show that, in the non-perturbative regime, such an interaction contain

T. Nord, A. Isacsson

The effects of including the van der Waals interaction in the modelling of the single electron shuttle have been investigated numerically. It is demonstrated that the relative strength of the vdW-forces and the elastic restoring forces determine the characteristics of the shuttle instability. In the case of weak elastic forces and low voltages the grain is t

Ewa Gudowska-Nowak, Romuald A. Janik, Jerzy Jurkiewicz, Maciej A. Nowak

We use an extension of the diagrammatic rules in random matrix theory to evaluate spectral properties of finite and infinite products of large complex matrices and large hermitian matrices. The infinite product case allows us to define a natural matrix-valued multiplicative diffusion process. In both cases of hermitian and complex matrices, we observe an eme

Masashige Matsumoto, Cyril Belardinelli, Manfred Sigrist

The inhomogeneous 3 Kelvin phase is most likely a superconducting state nucleating at the interface between micrometer-sized Ru-metal inclusions and Sr2RuO4 above the bulk onset of superconductivity. This filamentary superconducting state yields a characteristic temperature dependence of the upper critical field which is sublinear, i.e., H_{c2} (T) \propto (

S. R. Choudhury, A. S. Cornell, G. C. Joshi

The nature of the modification to neutrino lensing from galaxies, as caused by possible modifications to Newtonian gravity at large distances, is studied.

H. Matsui, T. Sato, T. Takahashi, S. -C. Wang

We performed high-resolution angle-resolved photoemission spectroscopy on triple-layered high-Tc cuprate Bi2Sr2Ca2Cu3O10+delta. We have observed the full energy dispersion (electron and hole branches) of Bogoliubov quasiparticles and determined the coherence factors above and below EF as a function of momentum from the spectral intensity as well as from the

K. Higashijima, E. Itou

The three dimensional nonlinear sigma model is unrenormalizable in perturbative method. By using the $β$ function in the nonperturbative Wilsonian renormalization group method, we argue that ${\cal N}=2$ supersymmetric nonlinear $σ$ models are renormalizable in three dimensions. When the target space is an Einstein-Kähler manifold with positive scalar curvat

Junji Hisano, Kiyotomo Kawagoe, Mihoko M. Nojiri

In supersymmetric models a gluino can decay into tb\tildeχ^{\pm}_1 through a stop or a sbottom. The decay chain produces an edge structure in the m_{tb} distribution. Monte Carlo simulation studies show that the end point and the edge height would be measured at the CERN LHC by using a sideband subtraction technique. The stop and sbottom masses as well as th

Matthew Whiting, Petra Majewski, Rachel Webster

We present photometric observations of six radio-loud quasars that were detected by the COMPTEL gamma-ray telescope. The data encompasses seven wavebands in the optical and near-infrared. After correction for Galactic extinction, we find a wide range in optical slopes. Two sources are as blue as optically-selected quasars, and are likely to be dominated by t

Gábor Megyesi, Frank Sottile

We study the set of lines that meet a fixed line and are tangent to two spheres and classify the configurations consisting of a single line and three spheres for which there are infinitely many lines tangent to the three spheres that also meet the given line. All such configurations are degenerate. The path to this result involves the interplay of some beaut

E917 Collaboration, B. B. Back, R. R. Betts, J. Chang

We report on a measurement of phi-meson production in Au+Au collisions at a beam momentum of 11.7 A GeV/c by Experiment E917 at the AGS. The measurement covers the midrapidity region 1.2 < y < 1.6. Transverse-mass spectra and the rapidity distribution are presented as functions of centrality characterized by the number of participant projectile nucleons. The

Paolo Giorda, Paolo Zanardi

We analyze the quantum entanglement properties of bosonic particles hopping over graph structures.Mode-entanglement of a graph vertex with respect the rest of the graph is generated, starting from a product state, by turning on for a finite time a tunneling along the graph edges. The maximum achieved during the dynamical evolution by this bi-partite entangle

C. Stephen Hellberg

Quantum computation in solid state quantum dots faces two significant challenges: Decoherence from interactions with the environment and the difficulty of generating local magnetic fields for the single qubit rotations. This paper presents a design of composite qubits to overcome both challenges. Each qubit is encoded in the degenerate ground-state of four (

Thomas Durt, Bob Nagler

The study of quantum cryptography and quantum entanglement has traditionally been based on two-level quantum systems (qubits) and more recently on three-level systems (qutrits). We investigate several classes of state-dependent quantum cloners for four-level systems (quartits). These results apply to symmetric as well as asymmetric cloners, so that the balan

Mikio Fujii

We give a description of balanced homodyne detection (BHD) using a conventional laser as a local oscillator (LO), where the laser field outside the cavity is a mixed state whose phase is completely unknown. Our description is based on the standard interpretation of the quantum theory for measurement, and accords with the experimental result in the squeezed s

Almas F. Sadreev, Ingrid Rotter

In the tight-binding approximation we consider multi-channel transmission through a billiard coupled to leads. Following Dittes we derive the coupling matrix, the scattering matrix and the effective Hamiltonian, but take into account the energy restriction of the conductance band. The complex eigenvalues of the effective Hamiltonian define the poles of the s

Mark A Bashuk

It is well known, and appreciated, that quantum computers have the potential to be the most powerful computational devices ever created. This newfound power comes from a quantum parallelism effect that allows the computer to be in multiple states at the same time. This property of quantum parallelism, while suited to handle common problems such as factoring

Partha Ghose

t is shown that although the de Broglie-Bohm quantum theory of motion is equivalent to standard quantum mechanics when averages of dynamical variables are taken over a Gibbs ensemble of Bohmian trajectories, the equivalence breaks down for ensembles built over clearly separated short intervals of time in special multi-particle systems. This feature is exploi

Andrei G. Bashkirov

Effective potential of a charged dusty particle moving in homogeneous plasma has a negative part that provides attraction between similarly charged dusty particles. A depth of this potential well is great enough to ensure both stability of crystal structure of dusty plasma and sizable value of surface tension of a boundary surface of dusty region. The latter

Koichi Saito

The rate constants for recombination and exchange reactions are calculated using the flux correlation approach with a general form of the Boltzmannized flux operator, which can simultaneously describe the Kubo and traditional half-split forms. First, we consider an exactly solvable model, i.e., the free particle case, in terms of a new scaling function. Next

Harihar Behera

The invariance of the speed of light in all inertial frames is shown to be an inevitable consequence of the relativity principle of special relativity contrary to the view held by Hsu and Hsu in taiji relativity where the speed of light is no longer a universal constant. The present approach is not only new but also much simpler than the existing approaches.

A G Moreira, S A Baeurle, G H Fredrickson

We present a computational strategy for reducing the sign problem in the evaluation of high dimensional integrals with non-positive definite weights. The method involves stochastic sampling with a positive semidefinite weight that is adaptively and optimally determined during the course of a simulation. The optimal criterion, which follows from a variational

S. V. Adamenko, A. S. Adamenko

We present the results of the experimental study on synthesis of a wide range of isotopes in a superdense plasma. The initial conditions necessary for plasma bunch formation were provided by specially organized coherent impact on a solid target with a total energy up to 1 kJ. More than 4000 shots were performed with various targets made of light, medium, and

J. D. Urbina, K. Richter

We show how two-point correlation functions derived within non-isotropic random wave models are in fact quantum results that are obtained in the appropriate limit in terms of the exact Green function of the quantum system. Since no statistical model is required for this derivation, this shows that taking the wave functions as Gaussian processes is the only a

A. Yu. Orlov

We generalize Harish-Chandra-Itzykson-Zuber and certain other integrals (Gross-Witten integral and integrals over complex matrices) using the notion of tau function of matrix argument. In this case one can reduce the matrix integral to the integral over eigenvalues, which in turn is certain tau function. We also consider a generalization of the Kontsevich in

G. Giachetta, L. Mangiarotti, G. Sardanashvily

Given a finite order Lagrangian L on a fibre bundle, its global generalized symmetries depending on higher order derivatives of dynamic variables are considered. The first variational formula is obtained. It leads both to the corresponding Lagarngian conservation laws and the characteristic equation for generalized symmetries of L.

Pramod N. Achar, Anne-Marie Aubert

Soit G un groupe algebrique reductif sur la cloture algebrique d&#39;un corps fini F_q et defini sur ce dernier. L&#39;existence du support unipotent d&#39;un caractere irreductible du groupe fini G(F_q), ou d&#39;un faisceau caractere de G, a ete etablie dans differents cas par Lusztig, Geck et Malle, et le second auteur. Dans cet article, nous demontrons q

Markus Banagl, Andrew Ranicki

The difference between the quadratic L-groups L_*(A) and the symmetric L-groups L^*(A) of a ring with involution A is detected by generalized Arf invariants. The special case A=Z[x] gives a complete set of invariants for the Cappell UNil-groups UNil_*(Z;Z,Z) for the infinite dihedral group D_{\infty}=Z_2*Z_2, extending the results of Connolly and Ranicki (ma

Gestur Olafsson, Angela Pasquale

The $Θ$-spherical functions generalize the spherical functions on Riemannian symmetric spaces and the spherical functions on non-compactly causal symmetric spaces. In this article we consider the case of even multiplicity functions. We construct a differential shift operator $D_m$ with smooth coefficients which generates the $Θ$-spherical functions from fini

Gestur Olafsson

Wavelet and frames have become a widely used tool in mathematics, physics, and applied science during the last decade. In this article we discuss the construction of frames for $L^2(\R^n)$ using the action of closed subgroups $H\subset \mathrm{GL}(n,\mathbb{R})$ such that $H$ has an open orbit $\cO$ in $\R^n$ under the action $(h,ω)\mapsto (h^{-1})^T(ω)$. If

R. Fabec, G. Olafsson, A. Sengupta

Suppose $A$ is a positive real linear transformation on a finite dimensional complex inner product space $V$. The reproducing kernel for the Fock space of square integrable holomorphic functions on $V$ relative to the Gaussian measure $dμ_A(z)=\frac {\sqrt {\det A}} {π^n}e^{-{\rm Re}< Az,z>} dz$ is described in terms of the holomorphic--antiholomorphic decom

Mark Davidson, Gestur Olafsson

In our previous papers \cite{doz1,doz2} we studied Laguerre functions and polynomials on symmetric cones $Ω=H/L$. The Laguerre functions $\ell^ν_{\mathbf{n}}$, $\mathbf{n}\in\mathbfΛ$, form an orthogonal basis in $L^{2}(Ω,dμ_ν)^{L}$ and are related via the Laplace transform to an orthogonal set in the representation space of a highest weight representations

Alan L. T. Paterson

We develop a theory of graph C*-algebras using path groupoids and inverse semigroups. Row finiteness is not assumed so that the theory applies to graphs for which there are vertices emitting a countably infinite set of edges. We show that the path groupoid is amenable, and give a groupoid proof of a recent theorem of Szymanski characterizing when a graph C*-

Dan Abramovich, Jiun C. Chen

We consider two cases of birational transformations of Q-Gorenstein threefolds: the case of a terminal flop and the case of a Francia flip. In the first case we show that, if one replaces the threefolds by their canonical covering stacks, the the flop coincides with the moduli stack of perverse point sheaves. This adds to a result of Kawamata showing the der

Ricardo Weder

In this paper we prove that the initial-boundary value problem for the forced non-linear Schroedinger equation with a potential on the half-line is locally and (under stronger conditions) globally well posed, i.e. that there is a unique solution that depends continuously on the force at the boundary and on the initial data. We allow for a large class of unbo

M. Campanino, D. Ioffe, Y. Velenik

We rigorously derive the Ornstein-Zernike asymptotics of the pair-correlation functions for finite-range Ising ferromagnets in any dimensions and at any temperature above critical.

M. Campanino, D. Ioffe, Y. Velenik

We recently introduced a robust approach to the derivation of sharp asymptotic formula for correlation functions of statistical mechanics models in the high-temperature regime. We describe its application to the nonperturbative proof of Ornstein-Zernike asymptotics of 2-point functions for self-avoiding walks, Bernoulli percolation and ferromagnetic Ising mo

Maciej Mroczkowski

In the classical knot theory there is a well-known notion of descending diagram. From an arbitrary diagram one can easily obtain, by some crossing changes, a descending diagram which is a diagram of the unknot or unlink. In this paper the notion of descending diagram for knots and links in the real space is extended to the case of nonoriented knots and links

Ph. Brax, J. Mourad, D. A. Steer

We consider solitonic solutions of the DBI tachyon effective action for a non-BPS brane. When wrapped on a circle, these solutions are regular and have a finite energy. We show that in the decompactified limit, these solitons give Sen&#39;s infinitely thin finite energy kink -- interpreted as a BPS brane -- provided that some conditions on the potential hold

Octavio Obregon, Leonardo Patino, Hernando Quevedo

For models with several time-dependent components generalized entropies can be defined. This is shown for the Bianchi type IX model. We first derive the Cardy-Verlinde formula under the assumption that the first law of thermodynamics is valid. This leads to an explicit expression of the total entropy associated with this type of universes. Assuming the valid

Ning Wu

Based on local gauge invariance, four different kinds of fundamental interactions in Nature are unified in a theory which has $SU(3)_c \otimes SU(2)_L \otimes U(1) \otimes_s Gravitational Gauge Group$ gauge symmetry. In this approach, gravitational field, like electromagnetic field, intermediate gauge field and gluon field, is represented by gauge potential.

Antti Salmela

A generalisation of existing SU(2) results is obtained. In particular, the source-free Gauss law for SU(3)-valued gauge fields is solved using a non-Abelian analogue of the Poincare lemma. When sources are present, the colour-electric field is divided into two parts in a way similar to the Hodge decomposition. Singularities due to coinciding eigenvalues of t

Christian S. Fischer

We present approximate non-perturbative solutions for the propagators as well as the running coupling of QCD from a coupled system of renormalised, truncated Dyson--Schwinger equations. We employ ansaetze for the dressed vertices such that the running coupling and the quark mass function are independent of the renormalisation point. Our solutions are in good

Alan Barr, Christopher Lester, Phil Stephens

We present the kinematic variable, m_T2, which is in some ways similar to the more familiar `transverse-mass&#39;, but which can be used in events where two or more particles have escaped detection. We define this variable and describe the event topologies to which it applies, then present some of its mathematical properties. We then briefly discuss two case

Johan Hansson

The &#34;proton spin crisis&#34; was introduced in the late 1980s, when the EMC-experiment revealed that little or nothing of a proton&#39;s spin seemed to be carried by its quarks. The main objective of this paper is to point out that it is wrong to assume that the proton spin, measured by completely different experimental setups, should be the same in all

Dieter Gromes

Starting with two coupled Bethe-Salpeter equations for the quark-antiquark, and for the quark-glue-antiquark component of the quarkonium, we solve the bound state equations perturbatively. The resulting admixture of glue can be partially understood in a semiclassical way, one has, however, to take care of the different use of time ordered versus retarded Gre

Johan Bijnens, Elvira Gamiz, Edisher Lipartia, Joaquim Prades

This paper discusses a general class of ladder resummation inspired hadronic approximations. It is found that this approach naturally reproduces many successes of single meson per channel saturation models (e.g. VMD) and NJL based models. In particular the existence of a constituent quark mass and a gap equation follows naturally. We construct an approximati

L. Frankfurt, V. Guzey, M. Strikman, M. Zhalov

We study photon-induced coherent production of Upsilon in ultraperipheral heavy ion collisions at LHC and demonstrate that the counting rates will be sufficient to measure nuclear shadowing of generalized gluon distributions. This will establish the transition from the regime of color transparency to the regime of perturbative color opacity in an unambiguous

Hsiang-nan Li

I compare collinear and $k_T$ factorization theorems in perturbative QCD, and discuss their application to exclusive $B$ meson decays. Especially, I concentrate on the recently measured time-dependent CP asymmetry of the $B^0_d\toπ^+π^-$ modes, from which the unitarity angle can be extracted.

X. -G. He, G. Valencia

We explore models with additional right-handed gauge bosons that couple predominantly to the third generation in the context of $b\bar{b}$ production at LEP. In particular we investigate potential new contributions to $δg_{Rb}$ that are needed if the measured $A^b_{FB}$ at the $Z$ peak is interpreted as a signal of new physics. We identify two sources of lar

J. Arrington

The strongly repulsive core of the short-range nucleon-nucleon interaction leads to the existence of high-momentum nucleons in nuclei. Inclusive electron scattering can be used to probe these high-momentum nucleons and study the nature of the corresponding short-range correlations in nuclei. With recent data from Jefferson Lab we have begun to map out the st

A. Straessner

Measurements of hadronic final state interactions in W-pair events at LEP are presented. In particular, different scenarios of colour reconnection are studied. The data agree with moderate colour reconnection effects. Extreme scenarios are ruled out, limiting the systematic uncertainty on the LEP W mass determination due to this effect. An updated measuremen

B. Aubert

We present a search for the B- ->tau- nu-bar decay in a data sample of 82 fb^(-1) collected at the Y(4S) resonance with the BaBar detector at the SLAC PEP-II asymmetric B Factory. Continuum and combinatorial backgrounds are suppressed by selecting a sample of events with one completely reconstructed B. The decay products of the other B in the event are analy

Solveig Albrand, Johann Collot, Jerome Fulachier

Many database tools have the same or similar requirements. The Atlas Metadata Interface (AMI) project aims to provide a set of generic tools for managing database applications. AMI has a three-tier architecture with a core that supports a connection to any RDBMS using JDBC and SQL. The middle layer assumes that the databases have an AMI compliant self-descri

Edgard C. de Rey Neto, Odylio D. Aguiar, José C. N. de Araujo

We find a gravitational wave solution to the linearized version of quadratic gravity by adding successive perturbations to the Einstein&#39;s linearized field equations. We show that only the Ricci squared quadratic invariant contributes to give a different solution of those found in Einstein&#39;s general relativity. The perturbative solution is written as

William D. Walker

A near-field analysis based on Maxwells equations is presented which indicates that the fields generated by both an electric and a magnetic dipole or quadrapole, and also the gravitational waves generated by a quadrapole mass source propagate superluminally in the nearfield of the source and reduce to the speed of light as the waves propagate into the farfie

Roy Maartens

The standard cosmological model, based on general relativity with an inflationary era, is very effective in accounting for a broad range of observed features of the universe. However, the ongoing puzzles about the nature of dark matter and dark energy, together with the problem of a fundamental theoretical framework for inflation, indicate that cosmology may

V. M. Khatsymovsky

Quantum area tensor Regge calculus is considered, some properties are discussed. The path integral quantisation is defined for the usual length-based Regge calculus considered as a particular case (a kind of a state) of the area tensor Regge calculus. Under natural physical assumptions the quantisation of interest is practically unique up to an additional on

Hans Stephani

From the original papers an interesting and surprising connection is established between LaPlace and his early discovery that black holes may occur in nature, and a poem by Schiller.

G. Neugebauer, R. Meinel

The increasing interest in compact astrophysical objects (neutron stars, binaries, galactic black holes) has stimulated the search for rigorous methods, which allow a systematic general relativistic description of such objects. This paper is meant to demonstrate the use of the inverse scattering method, which allows, in particular cases, the treatment of rot

Sudharshan Vazhkudai, Jennifer M. Schopf

The recent proliferation of Data Grids and the increasingly common practice of using resources as distributed data stores provide a convenient environment for communities of researchers to share, replicate, and manage access to copies of large datasets. This has led to the question of which replica can be accessed most efficiently. In such environments, fetc

Manuela Kunze, Chun Xiao

In this paper we describe an approach for the analysis of documents in German and English with a shared pool of resources. For the analysis of German documents we use a document suite, which supports the user in tasks like information retrieval and information extraction. The core of the document suite is based on our tool XDOC. Now we want to exploit these

Dietmar Roesner, Manuela Kunze

It is very costly to build up lexical resources and domain ontologies. Especially when confronted with a new application domain lexical gaps and a poor coverage of domain concepts are a problem for the successful exploitation of natural language document analysis systems that need and exploit such knowledge sources. In this paper we report about ongoing expe

H. P. Büchler, G. Blatter

We show that a two-dimensional atomic mixture of Bosons and Fermions cooled into their quantum degenerate states and subject to an optical lattice develops a supersolid phase characterized by the simultaneous presence of a non-trivial crystalline order and phase order. This transition is in competition with a phase separated ground state. We determine the ph

Dirk K. Morr, Nikolaos A. Stavropoulos

We study the electronic structure of magnetic and non-magnetic quantum corrals embedded in s-wave superconductors. We demonstrate that a quantum mirage of an impurity bound state peak can be projected from the occupied into the empty focus of a non-magnetic quantum corral via the excitation of the corral&#39;s eigenmodes. We observe an enhanced coupling betw

D. J. Singh

Density functional calculations are used to investigate the doping dependence of the electronic structure and magnetic properties in hexagonal Na$_x$CoO$_2$. The electronic structure is found to be highly two dimensional, even without accounting for the structural changes associated with hydration. At the local spin density approximation level, a weak itiner

Oleg Berman, Shaul Mukamel

Equations of motion are derived for the normal and the anomalous single-electron density matrices of a Fermi liquid using a time dependent finite temperature generalized coherent state (GCS) variational ansatz for the many-body density matrix. Self-consistent equations for the order parameter $Δ$ allow to investigate the interplay of Coulomb repulsion and pa

Stefan Blawid, Gertrud Zwicknagl

We extend a recently introduced semiclassical approach to calculating the influence of local lattice fluctuations on electronic properties of metals and metallic molecular crystals. The effective action of electrons in degenerate orbital states coupling to Jahn-Teller distortions is derived, employing dynamical mean-field theory and adiabatic expansions. We

P. O. Fedichev, M. J. Bijlsma, P. Zoller

We develop a theory describing neutral atoms scattering at low energies in an optical lattice. We show that for a repulsive interaction, as the microscopic scattering length increases, the effective scattering amplitude approaches a limiting value which depends only on the lattice parameters. In the case of attractive interaction a geometric resonance occurs

H. A. Radovan, N. A. Fortune, T. P. Murphy, S. T. Hannahs

A sufficiently high magnetic field applied to a superconductor will act on both the charge and the spin of the individual electrons breaking up the Cooper pairs. If the spin effect dominates, the superconducting state can develop a texture before eventually entering the normal state with increasing magnetic field. This spatially varying superconducting state

P. I. Arseev, N. K. Fedorov, S. O. Loiko

The current-voltage $IV$ characteristics of $SIS$ junctions are calculated in the framework of a multiband model with an anisotropic effective order parameter of HTSC. The results of calculations show that the shape of $IV$ characteristic and the density of electron states changes significantly depending on the parameters of the model. A theoretical explanat

Baruch Horovitz, Ehoud Pazy

Nonlinear photocurrent carriers in conjugated polymers, such as polarons, bipolarons and solitons, are considered at low photon energies where a tunnelling process is necessary. We show that polarons usually dominate the photocurrent I due to a novel electric field assisted tunnelling for which ln(I) ~ -E^{-2/3}. For near degenerate polymers an electric fiel

N. S. Skantzos, J. van Mourik, D. Saad, Y. Kabashima

We present a theoretical method for a direct evaluation of the average and reliability error exponents in low-density parity-check error-correcting codes using methods of statistical physics. Results for the binary symmetric channel (BSC) are presented for codes of both finite and infinite connectivity.

S. Rayaprol, Kausik Sengupta, E. V. Sampathkumaran

The temperature dependent ac and dc magnetization and heat capacity data of Ca$_3$CoIrO$_6$, a spin-chain compound crystallizing in a K$_4$CdCl$_6$-derived rhombohedral structure, show the features due to magnetic ordering of a frustrated-type below about 30 K, however without exhibiting the signatures of the so-called &#34;partially disordered antiferromagn

M. Potters, J-P Bouchaud

In a recent article [Nature 421, 130 (2003)], Plerou, Gopikrishnan and Stanley report some evidence for an intriguing two-phase behavior of financial markets when studying the distribution of volume imbalance conditional to the local intensity of its fluctuations. We show here that this apparent phase transition is a generic consequence of the conditioning a

Joachim Sjostrand, Anders Karlhede

We discuss a charge qubit consisting of a circular array of Josephson junctions. The two-level system we consider couples the two charge states through a higher order tunneling process thus making it possible to achieve a long relaxation time. Using the spin-boson Hamiltonian, we estimate decoherence due to ohmic as well as 1/f noise. We simulate the quantum

Dietrich Stauffer, Gerard Weisbuch

This article summarizes some physics aspects of the market model of Weisbuch and Stauffer, Physica A (2003): How do demand and quality expectation adjust to each other in a buyer dominated market like cinema visits? And how can business cycles be modelled?

E. Tsitsishvili, R. v. Baltz, H. Kalt

We study the relaxation of the exciton spin (longitudinal relaxation time $T_{1}$) in single asymmetrical quantum dots due to an interplay of the short--range exchange interaction and acoustic phonon deformation. The calculated relaxation rates are found to depend strongly on the dot size, magnetic field and temperature. For typical quantum dots and temperat

Cheng-Hung Chang, Anatoly G. Mal&#39;shukov, Koung-An Chao

Quantum oscillations of the spin conductance through regular and chaotic 2D quantum dots under the varying Rashba spin orbit interaction and at zero magnetic field have been numerically calculated by summing up the spin evolution matrices for classical transmitting trajectories. Fourier analysis of these oscillations showed power spectra strongly dependent o

Paolo Allegrini, Gerardo Aquino, Paolo Grigolini, Luigi Palatella

We discuss the problem of the equivalence between Continuous Time Random Walk (CTRW) and Generalized Master Equation (GME). The walker, making instantaneous jumps from one site of the lattice to another, resides in each site for extended times. The sojourn times have a distribution psi(t) that is assumed to be an inverse power law. We assume that the Onsager

A. Morales, R. A. Méndez-Sánchez, J. Flores

It has been recently shown theoretically that a topological defect in a 1D periodic potential may give rise to two localized states within the energy gaps. In this work we present an experimental realization of this effect for the case of torsional waves in elastic rods. We also show numerically that three, or even more, localized states can be present if th

Hiroya Sakurai, Kazunori Takada, Shunsuke Yoshii, Takayoshi Sasaki

Magnetic properties of the novel layered superconductor, Na$_{0.35}$CoO$_{2}$$\cdot$1.3H$_{2}$O have been investigated. From the temperature dependence and field dependence of the magnetization, the superconducting transition temperature, as well as upper- and lower-critical fields have been estimated to be $T_{C}=4.6$ K, $H_{C2}(0)=61.0$ T and $H_{C1}(0)=28

R. Weihrich, V. Eyert, S. F. Matar

The dinitrides CN2, SiN2, and GeN2 in assumed pyrite-type structures are studied by means of density functional theory using both ultrasoft pseudopotentials and the augmented spherical wave (ASW) method. The former two materials constitute the large-x limit of the broader class of CNx and SiNx compounds, which are well known for their interesting mechanical

S. Brazovskii, P. Monceau, F. Nad

We present key issues of related phenomenons of the Ferroelectricity and the Charge Disproportionation in organic metals. In (TMTTF_2X the dielectric susceptibility demonstrates clear cases of the ferroelectric and anti-ferroelectric phase transitions. Both the susceptibility and the conductivity prove independence and occasional coexistence of &#34;structur

Joseph B. Jensen, John L. Tonry, John P. Blakeslee

Significant progress has been made during the last 10 years toward resolving the debate over the expansion rate of the Universe. The current value of the Hubble parameter, Ho, is now arguably known with an accuracy of 10%, largely due to the tremendous increase in the number of galaxies in which Cepheid variable stars have been discovered. Increasingly accur

Stephen D. Murray, Shawfeng Dong, Douglas N. C. Lin

We use both analytical analyses and numerical simulations to examine the evolution of residual gas within tidally-limited dwarf galaxies and globular clusters. If the gas sound speed exceeds about 10% of the central velocity dispersion, as is the case for ionized gas within small stellar systems, the gas shall have significant density at the tidal radius, an

S. Turcotte

Ap/Bp stars are magnetic chemically peculiar early A and late B type stars of the main sequence. They exhibit peculiar surface abundance anomalies that are thought to be the result of gravitational settling and radiative levitation. The physics of diffusion in these stars are reviewed briefly and some model predictions are discussed. While models reproduce s

I. K. Baldry, K. Glazebrook

We obtain constraints on the slope of a universal stellar initial mass function (IMF) over a range of cosmic star-formation histories (SFH) using z=0.1 luminosity densities in the range from 0.2 to 2.2 microns. The age-IMF degeneracy of integrated spectra of stellar populations can be broken for the Universe as a whole by using direct measurements of (relati

E. Poretti, R. Garrido, P. J. Amado, K. Uytterhoeven

By pursuing the goal to find new variables in the COROT field-of-view we characterised a sample of stars located in the lower part of the instability strip. Our sample is composed of stars belonging to the disk population in the solar neighbourhood. We found that 23% of the stars display multiperiodic light variability up to few mmag of amplitude. uvbyBeta p

Ronald F. Webbink

Despite being the most abundant (by space density) of interacting binary stars, W Ursae Majoris (W UMa) stars are not understood structurally. Their stellar components are in physical contact, and share a common convective envelope. Observations demand large-scale energy exchange between components, as do considerations of hydrostatic and thermal equilibrium

Daniel Baumann, Asantha Cooray

Scattering of the temperature anisotropy quadrupole by free electrons in galaxy clusters leads to a secondary polarization signal in the cosmic microwave background (CMB) fluctuations. At low redshifts, the temperature quadrupole contains a significant contribution from the integrated Sachs-Wolfe (ISW) effect associated with the growth of density fluctuation

Piercarlo Bonifacio, Marco Limongi, Alessandro Chieffi

The chemical composition of stars with extremely low metal contents (taking ``metals&#39;&#39; to mean all elements other than hydrogen and helium) provides us with information on the masses of the stars that produced the first metals. Such a direct connection is not possible, however, if the surface of the star has been polluted by enriched material, either