August 2003 arXiv papers — page 25

S. Pratik Khastgir

Elasticity property (i.e. no-particle creation) is used in the tree level scattering of scalar particles in 1+1 dimensions to construct the affine Toda field theory(ATFT) associated with root systems of groups $a_2^{(2)}$ and $c_2^{(1)}$. A general prescription is given for constructing ATFT (associated with rank two root systems) with two self conjugate sca

V. Batagelj, M. Zaversnik

Short cycles connectivity is a generalization of ordinary connectivity. Instead by a path (sequence of edges), two vertices have to be connected by a sequence of short cycles, in which two adjacent cycles have at least one common vertex. If all adjacent cycles in the sequence share at least one edge, we talk about edge short cycles connectivity. It is shown

R. R. Akhmetshin, E. V. Anashkin, A. B. Arbuzov, V. Sh. Banzarov

The updated results of the precise measurements of the processes e+e-->rho->pi+pi-, e+e-->omega->pi+pi-pi0 and e+e-->phi->KLKS performed by the CMD-2 collaboration are presented. The update appeared necessary due an overestimate of the integrated luminosity in previous analyses.

T. Wibig, I. Kurp

The creation of particles with large transverse momenta in high energy hadronic collisions is a long standing problem. The transition from small- (soft) to hard- parton scattering `high-pt' events is rather smooth. In this paper we apply the non-extensive statistical framework to calculate transverse momentum distributions of long lived hadrons created a

Pat Muldowney, Fionn Murtagh

Practical data analysis involves many implicit or explicit assumptions about the good behavior of the data, and excludes consideration of various potentially pathological or limit cases. In this work, we present a new general theory of data, and of data processing, to bypass some of these assumptions. The new framework presented is focused on integration, an

R. J. Elliott, E. M. Epshtein, Yu. V. Gulyaev, P. E. Zilberman

Magnetic junction is considered which consists of two ferromagnetic metal layers, a thin nonmagnetic spacer in between, and nonmagnetic lead. Theory is developed of a magnetization reversal due to spin injection in the junction. Spin-polarized current is perpendicular to the interfaces. One of the ferromagnetic layers has pinned spins and the other has free

E. Bartos, M. V. Galynskii, S. R. Gevorkyan, E. A. Kuraev

The compact expressions for cross sections of photoproduction of a pair of charged particles $\mathrm{e}^+,\mathrm{e}^-$; $μ^+,μ^-$; $π^+,π^-$ as well as the double Compton scattering process are given. The explicit analytic expressions for the case of polarized photon and the initial electron in the kinematics when all the particles can be considered as a m

E. Bartos, A. -Z. Dubnickova, M. V. Galynskii, E. A. Kuraev

Processes with creation of a pair charged particles with emission of hard photon and two pairs of charged particles are considered for colliding partially polarized photon photon beams. The effects of circular and linear polarization of the initial photons are discussed in more details.

Dongsu Bak

We propose a new version of holographic principle. This proposal extends the holographic principle based on the lightsheet to the one constraining the entropy passing through bulk hypersurface of timelike geodesics by the boundary area divided by 4G. We give a proof of the proposal in the classical regime based on a simple local entropy condition.

Yasuhisa Abe, Bertrand Bouriquet, Caiwan Shen, Grigori Kosenko

The two-step model for fusion reactions of massive systems is briefly reviewed.By the use of fusion probabilities obtained by the model and of survival probabilities obtained by the new statistical code, we predict residue cross sections for 48Ca+actinide systems leading to superheavy elements with Z=114, 116 and 118.

T. Myo, S. Aoyama, K. Kato, K. Ikeda

Coulomb breakup strengths of 11Li into a three-body 9Li+n+n system are studied in the complex scaling method. We decompose the transition strengths into the contributions from three-body resonances, two-body ``10Li+n'' and three-body ``9Li+n+n'' continuum states. In the calculated results, we cannot find the dipole resonances with a sharp dec

A. Soddu, N-K. Tran

We reconstruct the Standard Model (SM) quark masses and the Cabibbo-Kobayashi-Maskawa (CKM) matrix from a five-dimensional model, with the fifth dimension compactified on an S^1/Z_2 orbifold. Fermions are localized only at the orbifold fixed points and the induced quark mass matrices are almost democratic. Two specific versions of our model with 15 and 24 pa

F. Iwamuro, K. Motohara, T. Maihara, M. Kimura

Near-infrared spectra of 15 high-redshift radio galaxies (HzRGs) located at $2<z<2.6$ were obtained by the OH Airglow Suppressor spectrograph mounted on the Subaru telescope. The UV-optical line ratio diagnostic diagrams indicate that half of the observed HzRGs have extended emission-line regions with low metal abundance, photoionized by a flat-continuum act

J. Jones, I. Mocioiu, M. H. Reno, I. Sarcevic

Astrophysical sources of ultrahigh energy neutrinos yield tau neutrino fluxes due to neutrino oscillations. We study in detail the contribution of tau neutrinos with energies above PeV relative to the contribution of the other flavors. We consider several different initial neutrino fluxes and include tau neutrino regeneration in transit through the Earth and

P. Wang, C. Z. Yuan, X. H. Mo

In S- and D-wave mixing scheme, the branching ratio of psi(3770) --> rho pi is estimated. Together with the continuum cross section of rho pi estimated by form factor, the observed cross section of rho pi production at psi(3770) in e+e- experiment is calculated taking into account the interference effect between the resonance and continuum amplitudes and the

Ali Mostafazadeh

With a view to eliminate an important misconception in some recent publications, we give a brief review of the notion of a pseudo-Hermitian operator, outline pseudo-Hermitian quantum mechanics, and discuss its basic difference with the indefinite-metric quantum mechanics. In particular, we show that the answer to the question posed in the title is a definite

E. W. Piotrowski, J. Sladkowski

Recent development in quantum computation and quantum information theory allows to extend the scope of game theory for the quantum world. The paper presents the history, basic ideas and recent development in quantum game theory. On grounds of the discussed material, we reason about possible future development of quantum game theory and its impact on informat

D. E. Browne, M. B. Plenio, S. F. Huelga

We present a protocol that allows the generation of a maximally entangled state between individual atoms held in spatially separate cavities. Assuming perfect detectors and neglecting spontaneous emission from the atoms, the resulting idealized scheme is deterministic. Under more realistic conditions, when the the atom-cavity interaction departs from the str

J. Sapirstein, K. T. Cheng

Complete vacuum polarization calculations incorporating finite nuclear size are presented for hydrogenic ions with principal quantum numbers n=1-5. Lithiumlike, sodiumlike, and copperlike ions are also treated starting with Kohn-Sham potentials, and including first-order screening corrections. In both cases dominant Uehling terms are calculated with high acc

Jean Marie Deken

Paper provides a brief introduction to SLAC, discusses the origins of the SLAC Archives and History Office, its present-day operations, and the present and future challenges it faces in attempting to preserve an accurate historical record of SLAC&#39;s activities.

Igor I. Smolyaninov

Nonlinear mode coupling in a coaxial waveguide filled with Faraday material has been considered. The picture of mode interaction is shown to resemble Coulomb interaction of charges: higher modes with nonzero angular momentum interact like effective charges via exchange of zero angular momentum quanta of the fundamental mode. Thus, at large distances this int

Axel G. Rossberg

It is argued that the two problems of choosing characterizations and models of complex systems should not be considered independently. A particular criterion for these choices, oriented on the potential usefulness of the results, is considered, and a generic formalization applicable to realistic experiments is developed. It is applied to Kuramoto-Sivashinsky

Martin Erik Horn

As an expansion of complex numbers, the quaternions show close relations to numerous physically fundamental concepts. In spite of that, the didactic potential provided by quaternion interrelationships in formulating physical laws are hardly regarded in the current physics curriculum. In particular, many approaches emerge that are useful in conveying the unit

Peter F. Kolb

A brief overview of the current status of hydrodynamic concepts applied to ultra relativistic heavy-ion collisions is presented. Special emphasis is placed on future prospects for extracting the thermodynamic properties and the bulk features of the created medium from experimental observations.

A. R. Junghans, E. C. Mohrmann, K. A. Snover, T. D. Steiger

We present new measurements of the ^7Be(p,gamma)^8B cross section from \bar{E}_{cm} = 116 to 2460 keV, that incorporate several improvements over our previously published experiment, also discussed here. Our new measurements lead to S_{17}(0) = 22.1 +- 0.6(expt) +- 0.6(theor) eV b based on data from \bar{E}_{cm} = 116 to 362 keV, where the central value is b

N. I. Ashwood, M. Freer

Measurements of the helium-cluster breakup and neutron removal cross sections for neutron-rich Be isotopes A=10-12,14 are presented. These have been studied in the 30 to 42 MeV/u energy range where reaction measurements are proposed to be sensitive to the cluster content of the ground-state wave-function. These measurements provide a comprehensive survey of

Yueheng Lan, Predrag Cvitanovic

A variational principle for determining unstable periodic orbits of flows as well as unstable spatio-temporally periodic solutions of extended systems is proposed and implemented. An initial loop approximating a periodic solution is evolved in the space of loops toward a true periodic solution by a minimization of local errors along the loop. The ``\descent&

G. Berkolaiko, J. P. Keating, B. Winn

We investigate statistical properties of the eigenfunctions of the Schrodinger operator on families of star graphs with incommensurate bond lengths. We show that these eigenfunctions are not quantum ergodic in the limit as the number of bonds tends to infinity by finding an observable for which the quantum matrix elements do not converge to the classical ave

Noam D. Elkies

We give a new construction of nonlinear error-correcting codes over suitable finite fields k from the geometry of modular curves with many rational points over k, combining two recent improvements on Goppa&#39;s construction. The resulting codes are asymptotically the best currently known.

A. Farrugia, R. Bruce Richter, G. Semanisin

A graph property (i.e., a set of graphs) is induced-hereditary or additive if it is closed under taking induced-subgraphs or disjoint unions. If $\cP$ and $\cQ$ are properties, the product $\cP \circ \cQ$ consists of all graphs $G$ for which there is a partition of the vertex set of $G$ into (possibly empty) subsets $A$ and $B$ with $G[A] \in \cP$ and $G[B]

Rafe Mazzeo, Frank Pacard

Let $Γ$ be a nondegenerate geodesic in a compact Riemannian manifold $M$. We prove the existence of a partial foliation of a neighbourhood of $Γ$ by CMC surfaces which are small perturbations of the geodesic tubes about $Γ$. There are gaps in this foliation, which correspond to a bifurcation phenomenon. Conversely, we also prove, under certain restrictions,

Fabrizio Andreatta, Eyal Z. Goren

We study Hilbert modular forms in characteristic $p$ and over $p$-adic rings. In the characteristic $p$-theory we describe the kernel and image of the $q$-expansion map and prove the existence of filtration for Hilbert modular forms; we define operators $U$, $V$ and $Θ_χ$ and study the variation of the filtration under these operators. In particular, we prov

G. Boros, J. Little, V. Moll, E. Mosteig

We describe dynamical properties of a map $\mathfrak{F}$ defined on the space of rational functions. The fixed points of $\mathfrak{F}$ are classified and the long time behavior of a subclass is described in terms of Eulerian polynomials.

Dr. W. B. Vasantha Kandasamy

Generally the study of algebraic deals with the concepts like groups, semigroups, groupoids, loops, rings, near-rings, semirings and vector spaces. The study of bialgebraic structures deals with the study of bistructures like bigroups, biloops, bigroupoids, bisemigroups, birings, binear-rings, bisemirings and bivector spaces. A complete study of these bialge

Peter Jorgensen

Let X be a smooth projective scheme of dimension d >= 1 over the field k, and let C be an indecomposable coherent sheaf on X. Then there is an Auslander-Reiten sequence in the category of quasi-coherent sheaves on X, with C as right hand end term. The left hand end term of the sequence can be computed. It is the (d-1)&#39;st syzygy in a minimal injective res

Nitin Nitsure

Let $X$ be a projective scheme over a noetherian base scheme $S$, and let $F$ be a coherent sheaf on $X$. For any coherent sheaf $E$ on $X$, consider the set-valued contravariant functor $Hom_{E,F}$ on $S$-schemes, defined by $Hom_{E,F}(T) = Hom(E_T,F_T)$ where $E_T$ and $F_T$ are the pull-backs of $E$ and $F$ to $X_T = X\times_S T$. A basic result of Grothe

Kiyonori Gomi

By means of cohomology groups, we study relationships between equivariant gerbes with connection over a manifold with a Lie group action and gerbes with connection over the quotient space.

A. Bartels, H. Reich

We prove the Farrell-Jones Isomorphism Conjecture about the algebraic K-theory of a group ring RG in the case where the group G is the fundamental group of a closed Riemannian manifold with strictly negative sectional curvature. The coefficient ring R is an arbitrary associative ring with unit and the result applies to all dimensions.

Albeverio Sergio, Torbin Grygoriy

We examine measure preserving mappings $f$ acting from a probability space $(Ω, F,μ) $ into a probability space $% (Ω^{*},F^{*},μ^{*}) ,$ where $μ^{*}=μ(f^{-1})$. Conditions on $f$, under which $f$ preserves the relations &#39;&#39;to be singular&#39;&#39; and &#39;&#39;to be absolutely continuous&#39;&#39; between measures defined on $(Ω, F) $ and correspon

Bert Koehler, Marco Kuehnel

We discuss a technique to construct Ricci-flat hermitian metrics on complements of (some) anticanonical divisors of almost homogeneous manifolds and discuss when this metric is complete and Kähler. This construction has a strong interplay with invariance groups of the same dimension as the manifold acting with an open orbit. Lie groups of this type we call d

Tamas Hausel, Eugenie Hunsicker, Rafe Mazzeo

We study the space of L^2 harmonic forms on complete manifolds with metrics of fibred boundary or fibred cusp type. These metrics generalize the geometric structures at infinity of several different well-known classes of metrics, including asymptotically locally Euclidean manifolds, the (known types of) gravitational instantons, and also Poincaré metrics on

Michael Entov

Each element of the commutator subgroup of a group can be represented as a product of commutators. The minimal number of factors in such a product is called the commutator length of the element. The commutator length of a group is defined as the supremum of commutator lengths of elements of its commutator subgroup. We show that for certain closed symplectic

Mark Tomforde

In this paper we analyze the structure of C*-algebras associated to ultragraphs, which are generalizations of directed graphs. We characterize the simple ultragraph algebras as well as deduce necessary and sufficient conditions for an ultragraph algebra to be purely infinite and to be AF. Using these techniques we also produce an example of an ultragraph alg

Noam D. Elkies

The sum in the title is a rational multiple of pi^n for all integers n=2,3,4,... for which the sum converges absolutely. This is equivalent to a celebrated theorem of Euler. Of the many proofs that have appeared since Euler, a simple one was discovered only recently by Calabi: the sum is written as a definite integral over the unit n-cube, then transformed i

Peter Svrcek

We find the complete chiral ring relations of the supersymmetric U(N) gauge theories with matter in adjoint representation. We demonstrate exact correspondence between the solutions of the chiral ring and the supersymmetric vacua of the gauge theory. The chiral ring determines the expectation values of chiral operators and the low energy gauge group. All the

M. S. Berger

Superfield realizations of Lorentz-violating extensions of the Wess-Zumino model are presented. These models retain supersymmetry but include terms that explicitly break the Lorentz symmetry. The models can be understood as arising from superspace transformations that are modifications of the familiar one in the Lorentz-symmetric case.

Kimball A. Milton

It is shown that a version of PT-symmetric electrodynamics based on an axial-vector current coupling massless fermions to the photon possesses anomalies and so is rendered nonrenormalizable. An alternative theory is proposed based on the conventional vector current constructed from massive Dirac fields, but in which the PT transformation properties of electr

Kimball A. Milton

In the context of the PT-symmetric version of quantum electrodynamics, it is argued that the C operator introduced in order to define a unitary inner product has nothing to do with charge conjugation.

Sunggeun Lee, Sang-Jin Sin

The GSO projection in the twisted sector of orbifold background is sometimes subtle and incompatible descriptions are found in literatures. Here, from the equivalence of partition functions in NSR and GS formalisms, we give a simple rule of GSO projection for the chiral rings of string theory in $\C^r/\Z_n$, $r=1,2,3$. Necessary constructions of chiral rings

Sang-Jin Sin

We study the localized tachyon condensation in their mirror Landau-Ginzburg picture. We completely determine the decay mode of an unstable orbifold $C^r/Z_n$, $r=1,2,3$ under the condensation of a tachyon with definite R-charge and mass by extending the Vafa&#39;s work hep-th/0111105. Here, we give a simple method that works uniformly for all $C^r/Z_n$. For

Vivien de Beauce, Samik Sen

We propose a discretisation scheme based on the Dirac-Kahler formalism (DK) in which the algebraic relations between continuum operators ${\wedge, d, \star}$ are captured by their discrete analogues, allowing the construction of the relevant projection operators necessary to prevent species doubling. We thus avoid the traditional form of species doubling as

Leonard S. Kisslinger

We use the method of QCD sum rules to investigate a possible hybrid baryon with the quantum numbers of the $Λ$. Using a current composed of uds quarks in a color octet and a gluon, a strange hybrid, the $Λ_H$ is found about 500 MeV above the $Λ$, and we identify it as the $Λ(1600)$. Using our sigma/glueball model we predict a large branching fraction for the

N. Bianchi, A. Fantoni, S. Liuti

We study the phenomenon of parton-hadron duality in both polarised and unpolarised electron proton scattering using the HERMES and the Jefferson Lab data, respectively. In both cases we extend a systematic perturbative QCD based analysis to the integrals of the structure functions in the resonance region. After subtracting target mass corrections and large x

G. L. Fogli, E. Lisi, A. Marrone, D. Montanino

In a previous paper [1], we presented a three-flavour oscillation analysis of the solar neutrino measurements and of the first data from the KamLAND experiment, in terms of the relevant mass-mixing parameters (delta m^2, theta_12, theta_13). The analysis, performed by including the terrestrial neutrino constraints coming from the CHOOZ (reactor), KEK-to-Kami

S. Dev, Sanjeev Kumar

Even after the confirmation of the large mixing angle (LMA) solution of the solar neutrino problem, the scope for resonant spin- flavor precession (RSFP) transitions as a subdominant effect still exists. In this work,we have considered suitably suppressed RSFP transitions in addition to the dominant LMA flavor transitions and translated the bounds on the ant

Marcela Carena, Andre de Gouvea, Ayres Freitas, Michael Schmitt

The measurement of the invisible Z-boson decay width at e+e- colliders can be done &#34;indirectly&#34;, by subtracting the Z-boson visible partial widths from the Z-boson total width, or &#34;directly&#34;, from the process e+e- -> γν\barν. Both procedures are sensitive to different types of new physics and provide information about the couplings of the neu

Stuart Raby

In this talk I discuss the problems and virtues of SUSY GUTs in four dimensions. I then show how to solve some of these problems, without foregoing the virtues, by considering an SO(10) SUSY GUT in five dimensions. I discuss gauge coupling unification and neutrino masses. In particular, it is shown that the 5D compactification scale and cutoff scale are dete

R. N. Mohapatra, S. Nussinov, A. Perez-Lorenzana

We suggest the possibility that in ADD type brane-world scenarios, the higher KK excitations of the graviton may decay to lower ones owing to a breakdown of the conservation of extra dimensional ``momenta&#39;&#39; and study its implications for astrophysics and cosmology. We give an explicit realization of this idea with a bulk scalar field $Φ$, whose nonze

J. L. Albacete, N. Armesto, A. Capella, A. B. Kaidalov

A model for shadowing in nuclear structure functions at small $x$ and small or moderate $Q^2$ is presented using the relation with diffraction that arises from Gribov&#39;s reggeon calculus. A reasonable description of the experimental data is obtained with no fitted parameters. A comparison with predictions from other models is performed.

Markus Lazar

In the framework of nonlocal light-cone expansion of two current operators we construct bilocal as well as trilocal QCD light-cone operators with definite geometric twist. We are able to decompose uniquely the appearing QCD light-cone operators into all their twist parts on the light-cone. The quark distribution functions and the vector meson distribution am

Pierre Binetruy, Andreas Birkedal-Hansen, Yann Mambrini, Brent D. Nelson

We provide a detailed study of the phenomenology of orbifold compactifications of the heterotic string within the context of supergravity effective theories. Our investigation focuses on those models where the soft Lagrangian is dominated by loop contributions to the various soft supersymmetry breaking parameters. Such models typically predict non-universal

M. Beneke

I estimate the SU(3) flavour symmetry breaking in the ratio of penguin-to-tree ratios of the decays B_s\to K^+ K^- and B_d\toπ^+π^-, given an assumption on the flavour symmetry breaking of the hadronic input parameters. The decay amplitudes are calculated in QCD factorization. Implications for the determination of gamma are discussed.

Katsuya Ishiguro, M. N. Chernodub, Katsuya Kobayashi, Tsuneo Suzuki

The length distribution and the monopole action of the infrared monopole clusters are studied numerically in quenched SU(2) QCD. We determine the effective entropy of the monopole currents which turns out to be a descending function of the blocking scale, indicating that the effective degrees of freedom of the extended monopoles are getting smaller as the bl

The BABAR Collaboration, B. Aubert

We present an observation of the decay $B^{0} \to π^{0} π^{0}$ based on a sample of 124 million $B\bar{B}$ pairs recorded by the BABAR detector at the PEP-II asymmetric-energy $B$ Factory at SLAC. We observe $46 \pm 13 \pm 3$ events, where the first error is statistical and the second is systematic, corresponding to a significance of 4.2 standard deviations

K. Scholberg

This pedagogical overview will cover the current status of neutrino physics from an experimentalist&#39;s point of view, focusing primarily on oscillation studies. The evidence for neutrino oscillations will be presented, along with the prospects for further refinement of observations in each of the indicated regions of two-flavor oscillation parameter space

Curtis A. Meyer

In this paper, I review the experimental situation for both glueballs and hybrid mesons. Theoretical expectations are discussed, and a survey of what is known about hybrid mesons and glueballs is undertaken. Good experimental evidence exists for both states with exotic quantum numbers and a glueball which is mixed with the nearby mesons, but a full understan

Alessando De Angelis

The hadronic events collected by LEP between 1989 and 2000 have changed dramatically our understanding of QCD, which has now been established as a part of the Standard Model. Still in many sectors (nonperturbative in particular) science analysis needs to be completed, and some new studies are just starting.

Russell Impagliazzo, Nathan Segerlind

We show that constant-depth Frege systems with counting axioms modulo $m$ polynomially simulate Nullstellensatz refutations modulo $m$. Central to this is a new definition of reducibility from formulas to systems of polynomials with the property that, for most previously studied translations of formulas to systems of polynomials, a formula reduces to its tra

Giorgio Parisi

In this note I will review some of the recent results that have been obtained in the probabilistic approach to the random satisfiability problem. At the present moment the results are only heuristic. In the case of the random 3-satisfiability problem a phase transition from the satisfiable to the unsatisfiable phase is found at $α=4.267$. There are other val

Baden Hughes, Steven Bird

We describe the design and early implementation of an extensible, component-based software architecture for natural language engineering applications which interfaces with high performance distributed computing services. The architecture leverages existing linguistic resource description and discovery mechanisms based on metadata descriptions, combining thes

C. Reichhardt, C. J. Olson Reichhardt, M. B. Hastings

We show that ratchet effects can occur in a glassy media of interacting particles where there is no quenched substrate. We consider simulations of a disordered binary assembly of colloids in which only one species responds to a drive. We apply an asymmetric ac drive that would produce no net dc drift of an isolated overdamped particle. When interacting parti

Duncan H J O&#39;Dell, Stefano Giovanazzi, Claudia Eberlein

We derive the exact density profile of a harmonically trapped Bose-Einstein condensate (BEC) which has dipole-dipole interactions as well as the usual s-wave contact interaction, in the Thomas-Fermi limit. Remarkably, despite the non-local anisotropic nature of the dipolar interaction, the density turns out to be an inverted parabola, just as in the pure s-w

S. Jochim, M. Bartenstein, A. Altmeyer, G. Hendl

We report on the production of a pure sample of up to 3x10^5 optically trapped molecules from a Fermi gas of 6Li atoms. The dimers are formed by three-body recombination near a Feshbach resonance. For purification a Stern-Gerlach selection technique is used that efficiently removes all trapped atoms from the atom-molecule mixture. The behavior of the purifie

D. G. Georgiev, P. Boolchand, K. A. Jackson

Raman scattering on bulk AsxS1-x glasses showes that vibrational modes of As4S4 monomer first appear near x=0.38, and their concentration increases precipitously with increasing x, suggesting that the stoichiometric glass (x=0.40) is intrinsically phase seperated into small As-rich(As4S4) and large S-righ clusters. Support for the Raman-active vibrational mo

R. Kuechler, N. Oeschler, P. Gegenwart, T. Cichorek

We present low-temperature volume thermal expansion, $β$, and specific heat, $C$, measurements on high-quality single crystals of CeNi2Ge2 and YbRh2(Si$_{0.95}$Ge$_{0.05}$)$_2$ which are located very near to quantum critical points. For both systems, $β$ shows a more singular temperature dependence than $C$, and thus the Grueneisen ratio ${Γ\propto β/C}$ div

Oleg Tchernyshyov

This paper explores the large-S route to quantum disorder in the Heisenberg antiferromagnet on the pyrochlore lattice and its homologues in lower dimensions. It is shown that zero-point fluctuations of spins shape up a valence-bond solid at low temperatures for one two-dimensional lattice and a liquid with very short-range valence-bond correlations for anoth

D. A. Rabson, B. N. Narozhny, A. J. Millis

We study numerically the evolution of energy-level statistics as an integrability-breaking term is added to the XXZ Hamiltonian. For finite-length chains, physical properties exhibit a cross-over from behavior resulting from the Poisson level statistics characteristic of integrable models to behavior corresponding to the Wigner-Dyson statistics characteristi

K. Yu. Arutyunov, T. T. Hongisto

Hybrid normal metal - insulator - superconductor microstructures suitable for studying an interference of electrons were fabricated. The structures consist of a superconducting loop connected to a normal metal electrode through a tunnel barrier . An optical interferometer with a beam splitter can be considered as a classical analogue for this system. All mea

Göran Johansson, Peter Samuelsson, Åke Ingerman

We derive the full counting statistics of charge transfer through a voltage biased superconducting junction. We find that for measurement times much longer than the inverse Josephson frequency, the counting statistics describes a correlated transfer of quanta of multiple electron charges, each quantum associated with the transfer of a single quasiparticle. A

Sadhan K. Adhikari

We study the expansion of a Bose-Einstein condensate trapped in a combined optical-lattice and axially-symmetric harmonic potentials using the numerical solution of the mean-field Gross-Pitaevskii equation. First, we consider the expansion of such a condensate under the action of the optical-lattice potential alone. In this case the result of numerical simul

Chandan Dasgupta, Oriol T. Valls

We consider the melting of the vortex solid in highly anisotropic layered superconductors with a small concentration of random columnar pinning centers. Using large-scale numerical minimization of a free-energy functional, we find that melting of the low-temperature, nearly crystalline vortex solid (Bragg glass) into a vortex liquid occurs in two steps as th

V. I. Yukalov, E. P. Yukalova, V. S. Bagnato

Coherent resonance is the effect of resonant excitation of nonlinear coherent modes in trapped Bose condensates. This novel effect is shown to be feasible for Bose-condensed trapped gases. Conditions for realizing this effect are derived. A method of stabilizing Bose condensates with attractive interactions is advanced. The origin of dynamic critical phenome

H. D. Yang, H. L. Liu, J. -Y. Lin, M. X. Kuo

X-ray absorption spectroscopy and optical reflectance measurements have been carried out to elucidate the evolution of the electronic structure in (Mg$_{1-x}$Al$_{x}$)B$_{2}$ for $\emph{x}$ = 0.0,0.1, 0.2, 0.3, and 0.4. The important role of B 2$\emph{p}$ $σ$ hole states to superconductivity has been identified, and the decrease in the hole carrier number is

V. M. Krasnov

Layered structure of Bi-2212 high $T_c$ superconductor (HTSC), provides a unique opportunity to probe quasiparticle density of states inside a bulk single crystal by means of intrinsic (interlayer) tunneling spectroscopy. Here I present a systematic study of intrinsic tunneling characteristics of Bi-2212 as a function of doping, temperature, magnetic field a

S. Kettemann

The 2-- to 1--dimensional crossover of the localisation length of electrons confined to a disordered quantum wire of finite width $L_y$ is studied in a model of electrons moving in the potential of uncorrelated impurities. An analytical formula for the localisation length is derived, describing the dimensional crossover as function of width $L_y$, conductanc

I. Felner, E. Galstyan, I. Asulin, A. Sharoni

The properties of the MoSr2RCu2O8 (R=rare earth) system are found to systematically change with the contraction of the R ions. For the light R ions (La-Nd) the samples are paramagnetic down to 5 K, whereas in the intermediate range (Sm-Tb), the Mo sublattice orders antiferromagnetically at TN, ranging from 11 to 24 K. For the heavy R ions, Ho-Tm and Y, super

D. Donadio, M. Bernasconi, F. Tassone

Based on density-functional perturbation theory we have computed from first principles the photoelastic tensor of few crystalline phases of silica at normal conditions and high pressure (quartz, $α$-cristobalite, $β$-cristobalite) and of models of amorphous silica (containig up to 162 atoms), obtained by quenching from the melt in combined classical and Car-

I. Felner, E. Galstyan

The properties of the MoSr2YCu2O8 materials are found to systematically change with the oxygen concentration determined by the sintering and annealing conditions. The as-prepared (asp) sample is anti-ferromagnetically (AFM) ordered at 16 K. The magnetic features are related to the Mo5+ sublattice. Annealing under an oxygen atmosphere induces superconductivit

N. Bulut

In order to investigate the effects of nonmagnetic impurities in strongly correlated systems, Quantum Monte Carlo (QMC) simulations have been carried out for the doped two-dimensional Hubbard model with one nonmagnetic impurity. Using a bare impurity potential which is onsite and attractive, magnetic and single-particle properties have been calculated. The Q

Michele Catanzaro, Guido Caldarelli, Luciano Pietronero

In this paper we present a new version of a network growth model, generalized in order to describe the behavior of social networks. The case of study considered is the preprint archive at cul.arxiv.org. Each node corresponds to a scientist, and a link is present whenever two authors wrote a paper together. This graph is a nice example of degree-assortative n

V. Orlyanchik, Z. Ovadyahu

A new protocol for an aging experiment is studied in the electron-glass phase of indium-oxide films. In this protocol, the sample is exposed to a non-ohmic electric field F for a waiting time t_{w} during which the system attempts to reach a steady state (rather than relax towards equilibrium). The relaxation of the excess conductance dG after ohmic conditio

M. Eleftheriou, G. P. Tsironis

We study the thermodynamics of discrete breathers by transforming a lattice of weakly coupled nonlinear oscillators into an effective Ising pseudospin model. We introduce a replica ensemble and investigate the effective system susceptibilities through the replica overlap distribution. We find that a transition occurs at a given temperature to a new phase cha

T. Vancura, S. Kicin, T. Ihn, K. Ensslin

A scanning force microscope with a base temperature below 300 mK is used for measuring the local electron density of a two-dimensional electron gas embedded in an Ga[Al]As heterostructure. At different separations between AFM tip and sample, a dc-voltage is applied between the tip and the electron gas while simultaneously recording the frequency shift of the

Kensuke Fukuda, H. Eugene Stanley, Luis A. Nunes Amaral

Many phenomena, both natural and human-influenced, give rise to signals whose statistical properties change under time translation, i.e., are nonstationary. For some practical purposes, a nonstationary time series can be seen as a concatenation of stationary segments. Using a segmentation algorithm, it has been reported that for heart beat data and Internet

S. M. Badalyan

We have studied magnetodrag between spatially separated two dimensional electron systems due to the virtual phonon exchange with and without taking into account the screening effects. The drag rate as a function of magnetic field, temperature, and interlayer spacing is calculated.

J. Sugiyama, J. H. Brewer, E. J. Ansaldo, H. Itahara

A positive muon spin rotation and relaxation ($μ^+$SR) experiment on [Ca$_2$CoO$_3$]$_{0.62}$[CoO$_2$], ({\sl i.e.}, Ca$_3$Co$_4$O$_9$, a layered thermoelectric cobaltite) indicates the existence of two magnetic transitions at $\sim$ 100 K and 400 - 600 K; the former is a transition from a paramagnetic state to an incommensurate ({\sf IC}) spin density wave

Marcel Ausloos, Kristinka Ivanova

The shape and tails of partial distribution functions (PDF) for a financial signal, i.e. the S&P500 and the turbulent nature of the markets are linked through a model encompassing Tsallis nonextensive statistics and leading to evolution equations of the Langevin and Fokker-Planck type. A model originally proposed to describe the intermittent behavior of turb

Hideo Hasegawa

Spike propagation for spatially correlated inputs in layered neural networks has been investigated with the use of a semi-analytical dynamical mean-field approximation (DMA) theory recently proposed by the author [H. Hasegawa, Phys. Rev. E {\bf 67}, 041903 (2003)]. Each layer of the network is assumed to consist of FitzHugh-Nagumo neurons which are coupled b

Rosalba Perna, Jonathan McDowell, Kristen Menou, John Raymond

We report Chandra observations of the dwarf nova WX Hyi in quiescence. The X-ray spectrum displays strong and narrow emission lines of N, O, Mg, Ne, Si, S and Fe. The various ionization states implied by the lines suggest that the emission is produced within a flow spanning a wide temperature range, from T ~ 10^6 K to T >~ 10^8 K. Line diagnostics indicate t

Philip Massey, P. A. Henning, R. C. Kraan-Korteweg

We have obtained VLA and optical follow-up observations of the low-velocity H I source HIZSS 3 discovered by Henning et al. (2000) and Rivers (2000) in a survey for nearby galaxies hidden by the disk of the Milky Way. Its radio characteristics are consistent with this being a nearby (~1.8 Mpc) low-mass dwarf irregular galaxy (dIm). Our optical imaging failed