August 2004 arXiv papers — page 8

Andrew M. Childs, Jeffrey Goldstone

Grover's quantum search algorithm provides a way to speed up combinatorial search, but is not directly applicable to searching a physical database. Nevertheless, Aaronson and Ambainis showed that a database of N items laid out in d spatial dimensions can be searched in time of order sqrt(N) for d>2, and in time of order sqrt(N) poly(log N) for d=2. We co

Renat Kh. Gainutdinov, Aigul A. Mutygullina

We discuss the problem of consistency of quantum mechanics as applied to low energy nucleon dynamics with the symmetries of QCD. It is shown that the dynamics consistent with these symmetries is not governed by the Schrodinger equation. We present a new way to formulate the effective theory of nuclear forces as an inevitable consequence of the basic principl

Franco Bagnoli, Carlo Guardiani

We study the evolution of recombination using a microscopic model developed within the frame of the theory of quantitative traits. Two components of fitness are considered: a static one that describes adaptation to environmental factors not related to the population itself, and a dynamic one that accounts for interactions between organisms e.g. competition.

T. Mizuguchi, K. Sugawara, H. Nishimori, T. Tao

Collective behavior of active elements inspired by mass of biological organisms is addressed. Especially, two topics are focused on among amazing behaviors performed by colony of ants. First, task allocation phenomena are treated from the viewpoint of proportion regulation of population between different states. Using a dynamical model consisting of elements

Franco Bagnoli, Carlo Guardiani

A microscopic model is developed, within the frame of the theory of quantitative traits, to study both numerically and analytically the combined effect of competition and assortativity on the sympatric speciation process, i.e. speciation in the absence of geographical barriers. Two components of fitness are considered: a static one that describes adaptation

H. E. Puthoff, M. A. Piestrup

Laboratory observation of high-density filamentation or clustering of electronic charge suggests that under certain conditions strong coulomb repulsion can be overcome by cohesive forces as yet imprecisely defined. Following an earlier suggestion by Casimir, we investigate here the possibility that Casimir forces can lead to charge clustering of the type obs

Hongwu Zhao, Kamran Mohseni

A dynamic procedure for the Lagrangian Averaged Navier-Stokes-$α$ (LANS-$α$) equations is developed where the variation in the parameter $α$ in the direction of anisotropy is determined in a self-consistent way from data contained in the simulation itself. The dynamic model is initially tested in forced and decaying isotropic turbulent flows where $α$ is con

Ruediger Vaas

Did the universe have a beginning or does it exist forever, i.e. is it eternal at least in relation to the past? This fundamental question was a main topic in ancient philosophy of nature and the Middle Ages. Philosophically it was more or less banished then by Immanuel Kant's Critique of Pure Reason. But it used to have and still has its revival in modern p

M. Hasegawa, K. Kaneko, T. Mizusaki

The $^{66}$Ge and $^{68}$Ge nuclei are studied by means of the shell model with the extended $P+QQ$ Hamiltonian, which succeeds in reproducing experimentally observed energy levels, moments of inertia and other properties. The investigation using the reliable wave-functions predicts T=0, J=9 one-proton-one-neutron ($1p1n$) alignment in the $g_{9/2}$ orbit, a

Olga Barannikova

Investigation of the final hadronic state properties of ultra-relativistics pp and Au+Au collisions supplies information on freeze-out conditions at RHIC and possible insights into early stages of these collisions. A variety of particle spectra measured by STAR are studied within the framework of chemical and local kinetic equlibrium models. Here we present

Olga Barannikova

Measurements of a variety of hadron species in Au+Au collisions at 200 GeV by the STAR experiment are used to investigate properties of such collisions. We present a study of particle yields and transverse momentum spectra within the framework of chemical and local kinetic equilibrium models. The extracted freeze-out properties are studied as function of col

H. Gottschalk

We prove that for a Wightman quantum field $ϕ(x)$ the assumptions (i) positivity of the metric on the state space ${\cal H}$ of the theory (ii) the asymptotic condition in the form of Yang-Feldman equations and (iii) Klein-Gordon equation for the outgoing field imply that the states generated by application of the asymptotic fields to the vacuum are stable.

H. Gottschalk

It is proved that a Poincare invariant Wightman function which fulfils the spectral property and can be defined at sharp times is local if and only if the integration over both the energy variables of a commutator in momentum space is a polynomial in the momentum conjugated to the spacial difference variable of the commutator with distributional coefficients

H. Gottschalk

It is proven that in indefinite metric quantum field theory there exists a dense set of analytic vectors for the generator of the one parameter group of x^0-x^1 velocity transformations. This makes it possible to define complex velocity transformations also for the indefinite metric case. In combination with the results of Bros -- Epstein -- Moschella, provi

H. Gottschalk, H. Thaler

We consider a relativistic Ansatz for the vacuum expectation values (VEVs) of a quantum field on a globally hyperbolic space-time which is motivated by certain Euclidean field theories. The Yang-Feldman asymptotic condition w.r.t. a "in"-field in a quasi-free representation of the canonic commutation relations (CCR) leads to a solution of this Ansatz for the

M. R. Dennis

Any eigenfunction of the laplacian on the sphere is given in terms of a unique set of directions: these are Maxwell's multipoles, their existence and uniqueness being known as Sylvester's theorem. Here, the theorem is proved by realising the multipoles are pairs of opposite vectors in Majorana's sphere representation of quantum spins. The proof i

J. Mark Heinzle, Alan D. Rendall, Claes Uggla

We investigate spherically symmetric equilibrium states of the Vlasov-Poisson system, relevant in galactic dynamics. We recast the equations into a regular three-dimensional system of autonomous first order ordinary differential equations on a region with compact closure.Based on a dynamical systems analysis we derive theorems that guarantee that the steady

Jan de Gier, Vladimir Rittenberg

Recently it has been conjectured that the ground-state of a Markovian Hamiltonian, with one boundary operator, acting in a link pattern space is related to vertically and horizontally symmetric alternating-sign matrices (equivalently fully-packed loop configurations (FPL) on a grid with special boundaries).We extend this conjecture by introducing an arbitrar

Alexander I. Aptekarev, Pavel M. Bleher, Arno B. J. Kuijlaars

We continue the study of the Hermitian random matrix ensemble with external source $\frac{1}{Z_n} e^{-n \Tr({1/2}M^2 -AM)} dM$ where $A$ has two distinct eigenvalues $\pm a$ of equal multiplicity. This model exhibits a phase transition for the value $a=1$, since the eigenvalues of $M$ accumulate on two intervals for $a > 1$, and on one interval for $0 < a <

Qi Chen

We construct certain tensor categories that are dominated by finitely many simple objects. Objects in these categories are modules over rings of algebra integers. We show how to obtain TQFTs defined over algebra integers from these categories.

Chris Connell, Roman Muchnik

We consider a group G of isometries acting on a (not necessarily geodesic) delta-hyperbolic space X and possessing a radial limit set of full measure within its limit set. For any continuous quasiconformal measure w supported on the limit set, we produce a stationary measure m on G. Moreover the limit set together with w forms a m-boundary and w is harmonic

Federico Ardila

A set S of 2n+1 points in the plane is said to be in general position if no three points of S are collinear and no four are concyclic. A circle is called halving with respect to S if it has three points of S on its circumference, n-1 points in its interior, and n-1 in its exterior. We prove the following surprising result: any set of 2n+1 points in general p

Khalil El Mehdi, Mokhless Hammami

In this paper we consider the following biharmonic equation with critical exponent $P_ε$ : $Δ^2 u= Ku^{(n+4)/(n-4)-ε}, u>0$ in $Ω$ and $u=Δu=0$ on $\partialΩ$, where $Ω$ is a domain in $R^n$, $n\geq 5$, $ε$ is a small positive parameter and $K$ is smooth positive function. We construct solutions of $P_ε$ which blow up and concentrate at strict local maximum

Ana L. Branco Correia, Santiago Zarzuela

Let R be a commutative ring and let G be a free R-module with positive rank e. For any R-submodule E of G we may consider the image of the symmetric algebra of E by the natural map to the symmetric algebra of G, and then the graded components E_n of the image, that we call the n-th Rees powers of E. In this work we prove some asymptotic properties of the mod

Robin de Jong

In this note we give a closed formula for Faltings&#39; delta-invariant of a hyperelliptic Riemann surface.

Leroux Philippe

We continue our reformulation of free dendriform algebras, dealing this time with the free dendriform trialgebra generated be Y over planar rooted trees. We propose a &#39;deformation&#39; of a vectorial coding used in Part I, giving a LL-lattice on rooted planar trees according to the terminology of A. Blass and B. E. Sagan. The three main operations on tre

Leroux Philippe

We propose a reformulation of some results known on the free dendriform dialgebra on one generator from a parenthesis point of view. This turns out to be more tractable and point out a connection to free probability by identifying noncrossing partitions with binary trees and by introducing the concept of NCP-operad.

Koji Fujiwara, Koichi Nagano, Takashi Shioya

We study the fixed point set in the ideal boundary of a parabolic isometry of a proper CAT(0)-space. We show that the radius of the fixed point set is at most pi/2, and study its centers. As a consequence, we prove that the set of fixed points is contractible with respect to the Tits topology.

Benjamin Lundell, Jason McCullough

We prove a new bound for the minimum distance of geometric Goppa codes that generalizes two previous improved bounds. We include examples of the bound to one and two point codes over both the Suzuki and Hermitian curves.

Andreas Kriegl, Mark Losik, Peter W. Michor, Armin Rainer

Any sufficiently often differentiable curve in the orbit space of a compact Lie group representation can be lifted to a once differentiable curve into the representation space.

Martin Rocek, Neal Wadhwa

We prove that a Kahler supermetric on a supermanifold with one complex fermionic dimension admits a super Ricci-flat supermetric if and only if the bosonic metric has vanishing scalar curvature. As a corollary, it follows that Yau&#39;s theorem does not hold for supermanifolds.

Nobuhito Maru, Nobuchika Okada

A simple model of extra-dimensional radius stabilization in a supersymmetric Randall-Sundrum model is presented. In our model, we introduce only a bulk hypermultiplet and source terms on each boundary branes. With an appropriate choice of model parameters, we find that the radius can be stabilized by supersymmetric vacuum conditions. Since the radion mass ca

Miroslav Pardy

It is considered the Dirac equation with two different four-potentials of the plane electromagnetic waves. We derive the equation for the wave function which is generalized form of the Volkov equation. We find the solutions of the Dirac equation for two orthogonal waves. We determine the modified Compton formula for the scattering of two photons on an electr

S. Kretzer

Interest in the strange nucleon sea has been renewed when it was realized that the strangeness asymmetry $s^-=s-\bar{s}$ plays a prominent role in the interpretation of the NuTeV weak mixing angle anomaly. I review the NLO QCD calculation of the neutrino-production of opposite-sign dimuons as the experimental signature of the strange quark parton density. Re

B. Jager, S. Kretzer, M. Stratmann, W. Vogelsang

The longitudinally polarized gluon density is probed sensitively in hard collisions of polarized protons under the condition that the dominant dynamics are perturbative and of leading twist origin. First data have recently been presented by Phenix on the double-spin asymmetry A_{LL}^{pi} for pi^0 production at moderate transverse momentum p_\perp \simeq 1 -

Ralf Lehnert, Robertus Potting

The emission of electromagnetic radiation by charges moving uniformly in a Lorentz-violating vacuum is studied. The analysis is performed within the classical Maxwell-Chern-Simons limit of the Standard-Model Extension (SME) and confirms the possibility of a Cherenkov-type effect. In this context, various properties of Cherenkov radiation including the rate,

M. Klasen, B. A. Kniehl, L. N. Mihaila, M. Steinhauser

We calculate the cross section of J/psi plus prompt-photon inclusive production in gamma gamma collisions at next-to-leading order within the factorization formalism of nonrelativistic quantum chromodynamics (NRQCD) focusing on direct photoproduction. Apart from direct J/psi production, we also include the feed-down from directly-produced chi_{cJ} and psi&#3

Alexander Mück, Apostolos Pilaftsis, Reinhold Rückl

We analyze non-universal 5D standard model extension, where some or all of the gauge and Higgs fields propagate in a flat extra dimension, while all other degrees of freedom are localized on a S^1/Z_2 orbifold brane. From LEP data, model-dependent bounds on the compactification scale M between 4 and 6 TeV are derived. We analyze the correlations between M an

Stefan Weinzierl

The process e+ e- -> 3 jets offers the opportunity to measure the strong coupling constant. For an accurate determination, precise theoretical calculations are necessary. I will give an overview on the status of the next-to-next-to-leading order calculations.

U. Jamil, J. K. Sarma

In this paper, we find the t and x-evolution of deuteron structure function from DGLAP evolution equation of singlet structure function in leading order at small-x assuming the Regge behaviour of the singlet structure function at this limit and we compare our result of deuteron structure function with New Muon Collaboration data to find the range of the inte

Shinya Kanemura, Koichi Matsuda, Toshihiko Ota, Tetsuo Shindou

We study possibility of observing the process $h^{0} \to τ^{\pm} μ^{\mp}$ at a linear collider. The branching ratio is constrained to be of the order of $10^{-4}$ by the $τ^{-} \to μ^{-} η$ result. Supersymmetric standard models can reproduce such amount of the branching ratio by taking a specific parameter set. The Higgsstrahlung process $e^{+}e^{-} \to Zh^

Paul Romatschke, Michael Strickland

We compute the leading-order collisional energy loss of a heavy quark propagating through a quark-gluon plasma in which the quark and gluon distributions are anisotropic in momentum space. Following the calculation outlined for QED in an earlier work we indicate the differences encountered in QCD and their effect on the collisional energy loss results. For a

J. Vijande, H. Garcilazo, A. Valcarce, F. Fernandez

We study the mass spectrum of baryons with two and three charmed quarks. For double charm baryons the spin splitting is found to be smaller than standard quark-model potential predictions. This splitting is not influenced either by the particular form of the confining potential or by the regularization taken for the contact term of the spin-spin potential. W

D. V. Shirkov

A comprehensive review is presented of the progress made in further developing the ghost-free Analytic Approach to low-energy QCD since &#34;QCD-97&#34; meeting. It is now formulated as a logically closed ``Analytic Perturbation Theory&#34; algorithm. Its most essential feature is nonpower functional expansions for QCD observables.

Gi-Chol Cho, Aya Omote

A generic feature of little Higgs models is presence of extra neutral gauge bosons. In the littlest Higgs model, the neutral extra gauge boson A_H is lightest among the extra particles and could be as light as a few hundred GeV, which may be produced directly at an e^+ e^- linear collider. We study production and decay of A_H at the linear collider and compa

S. Heinemeyer

Current and future colliders will provide high precision experimental data. In order to use the high experimental precision it has to be matched with theoretical predictions at the same level of accuracy or better. This involves the calculation of loop corrections at increasingly higher order. We briefly review the status of the field, especially in view of

P. R. Crompton, W. Janke, Z. X. Xu, H. P. Ying

We investigate critical slowing down in the local updating continuous-time Quantum Monte Carlo method by relating the finite size scaling of Fisher Zeroes to the dynamically generated gap, through the scaling of their respective critical exponents. As we comment, the nonlinear sigma model representation derived through the hamiltonian of our lattice spin mod

Bugra Borasoy, Randy Lewis, Daniel Mazur

Lattice regularization is used to perform chiral perturbation theory calculations in finite volume. The lattice spacing is chosen small enough to be irrelevant, and numerical results are obtained from simple summations.

Stephan Dürr, Christian Hoelbling

We investigate the validity of the square rooting procedure of the staggered determinant in the context of the Schwinger model. We find some evidence that at fixed physical quark mass the square root of the staggered determinant becomes proportional to the overlap determinant in the continuum limit. We also find that at fixed lattice spacing moderate smearin

Falk Bruckmann, E. M. Ilgenfritz, B. V. Martemyanov, M. Muller-Preussker

We discuss recent solutions for SU(2) calorons with non-trivial holonomy at higher charge, both through analytic means and using cooling, as well as extensive lattice studies for SU(3).

K. Abe

We report measurements of $B$ to pseudoscalar-pseudoscalar decays with at least one eta meson in the final state using 140 fb^{-1} of data collected by the Belle detector at KEKB e^+ e^- collider. We observe the decays of B^+-> eta pi^+ and B^+-> eta K^+; the measured branching fractions are Br(B^+-> eta pi^+) = (4.8^{+0.8}_{-0.7}(stat) +- 0.3 (sys)) * 10^-6

The OPAL collaboration, G. Abbiendi

We present a determination of the LEP beam energy using &#34;radiative return&#34; fermion-pair events recorded at centre-of-mass energies from 183 GeV to 209 GeV. We find no evidence of a disagreement between the OPAL data and the LEP Energy Workings Group&#39;s standard calibration. Including the energy- averaged 11 MeV uncertainty in the standard determin

K. Abe

We report a study of the suppressed decay $B^{-} \to [K^{+}π^{-}]_{D}K^{-}$(and its charge-conjugate mode) at Belle, where $[K^{+}π^{-}]_{D}$ indicates that the $K^{+}π^{-}$ pair originates from a neutral $D$ meson. A data sample containing 274 million $B\bar{B}$ pairs recorded at the $Υ(4S)$ resonance with the Belle detector at the KEKB asymmetric $e^{+}e^{

N. M. Agababyan, V. V. Ammosov, M. Atayan, N. Grigoryan

For the first time, the characteristics of the charged current neutrinonuclear interactions are investigated at $E_ν$ = 1 - 3 GeV using the data obtained with SKAT propane-freon bubble chamber irradiated in the neutrino beam at Serpukhov accelerator. The $E_ν$ - dependence of the mean multiplicities of different types of secondary particles and their multipl

B. Aubert, BABAR Collaboration

We present results on time-dependent CP asymmetries in neutral B decays to several CP eigenstates. The measurements use a data sample of about 227 million Upsilon(4S) -> BBbar decays collected by the BABAR detector at the PEP-II asymmetric-energy B Factory at SLAC. The amplitude of the CP asymmetry, sin2Beta in the Standard Model, is derived from decay-time

J. E. Nelson

The ADM Formalism is discussed in the context of 2+1--dimensional gravity, uniting two areas of relativity theory in which Stanley Deser has been particularly active. For spacetimes with topology R x T^2 the partially reduced and fully reduced ADM formalism are related and quantized, and the role of &#34;large diffeomorphisms&#34; (the modular group) in the

J. E. Nelson, R. F. Picken

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

Tapas K. Das

We show that spherical accretion onto astrophysical black holes can be considered as a natural example of analogue system. We provide, for the first time, an exact analytical scheme for calculating the analogue Hawking temperature and surface gravity for general relativistic accretion onto astrophysical black holes. Our calculation may bridge the gap between

Bernd Reimann

Slice-stretching effects are discussed as they arise at the event horizon when geodesically slicing the extended Schwarzschild black-hole spacetime while using singularity excision. In particular, for Novikov and isotropic spatial coordinates the outward movement of the event horizon (``slice sucking&#39;&#39;) and the unbounded growth there of the radial me

Patrik O. Hoyer

Non-negative matrix factorization (NMF) is a recently developed technique for finding parts-based, linear representations of non-negative data. Although it has successfully been applied in several applications, it does not always result in parts-based representations. In this paper, we show how explicitly incorporating the notion of `sparseness&#39; improves

Afzal Ballim, Vincenzo Pallotta

In this paper we summarized a framework for designing grammar-based procedure for the automatic extraction of the semantic content from spoken queries. Starting with a case study and following an approach which combines the notions of fuzziness and robustness in sentence parsing, we showed we built practical domain-dependent rules which can be applied whenev

A. Donev, S. Torquato, F. H. Stillinger

We study the approach to jamming in hard-sphere packings, and, in particular, the pair correlation function $g_{2}(r)$ around contact, both theoretically and computationally. Our computational data unambiguously separates the narrowing delta-function contribution to $g_{2}$ due to emerging interparticle contacts from the background contribution due to near c

T. Zhao, J. D. Weeks, D. Kandel

Coarse-grained modeling of dynamics on vicinal surfaces concentrates on the diffusion of adatoms on terraces with boundary conditions at sharp steps, as first studied by Burton, Cabrera and Frank (BCF). Recent electromigration experiments on vicinal Si surfaces suggest the need for more general boundary conditions in a BCF approach. We study a discrete 1D ho

T. Zhao, J. D. Weeks

We study current-induced step bunching and wandering instabilities with subsequent pattern formations on vicinal surfaces. A novel two-region diffusion model is developed, where we assume that there are different diffusion rates on terraces and in a small region around a step, generally arising from local differences in surface reconstruction. We determine t

Y. Chen, Wei Bao, J. E. Lorenzo, A. Stunault

The Landau-Ginzburg-Wilson paradigm for critical phenomena is spectacularly successful whenever the critical temperature is finite and all fluctuation modes, with characteristic energies much smaller than the thermal energy, obey classical statistics. In zero-temperature quantum critical phenomena, classical thermal fluctuations are replaced by zero-point qu

Ricardo Kagimura, Ricardo W. Nunes, Helio Chacham

We report an ab-initio investigation of several possible Si and Ge pristine nanowires with diameters between 0.5 and 1.2 nm. We considered nanowires based on the diamond structure, high-density bulk structures, and fullerene-like structures. We find that the diamond structure nanowires are unstable for diameters smaller than 1 nm, and undergo considerable st

K. P. Hewaparakrama, S. Mackowski, H. E. Jackson, L. M. Smith

We demonstrate sub-wavelength imaging of excitons confined to single CdTe quantum dots. By combining slit-confocal microscopy with a hemispherical solid immersion lens we simultaneously map the emission of thousands of single quantum dots with a spatial resolution of 400 nm. By analyzing the linear polarization of the quantum dot emissions at B=0T, we find t

Leonid P. Pryadko, Jing-Xian Lin

We analyze one-dimensional motion of an overdamped classical particle in the presence of external disorder potential and an arbitrary driving force F. In thermodynamical limit the effective force-dependent mobility mu(F) is self-averaging, although the required system size may be exponentially large for strong disorder. We calculate the mobility mu(F) exactl

S. N. Coppersmith, Seungwon Lee, Paul von Allmen

In bulk silicon, intervalley electronic interference has been shown to lead to strong oscillations in the exchange coupling between impurity electronic wavefunctions, posing a serious manufacturability problem for proposed quantum computers. Here we show that this problem does not arise in proposed architectures using Si/SiGe quantum dots because of the larg

Elijah Flenner, Grzegorz Szamel

A four-time correlation function was calculated using a computer simulation of a binary Lennard-Jones mixture. The information content of the four-time correlation function is similar to that of four-time correlation functions measured in NMR experiments. The correlation function selects a sub-ensemble and analyzes its dynamics after some waiting time. The l

G. J. Ackland, H. Fox

We present calculation of the high pressure crystal structures in selenium, including rational approximants to the recently reported incommensurate phases. We show how the incommensurate phases can be intuitively explained in terms of imaginary phonon frequencies arising from Kohn anomalies in the putative undistorted phase. We also find inconsistencies betw

A. E. Allahverdyan, Th. M. Nieuwenhuizen

The minimal work principle states that work done on a thermally isolated equilibrium system is minimal for adiabatically slow (reversible) realization of a given process. This principle, one of the formulations of the second law, is studied here for finite (possibly large) quantum systems interacting with macroscopic sources of work. It is shown to be valid

A. Boulbitch

A model system has been recently developed to study adhesion. It consists of a giant lipid bilayer vesicle with reconstituted lipo-polymers (repellers) as well as with lipo-ligands recognized by receptors covering the substrate. Adhesion in this system is studied theoretically. The state of the weak adhesion is shown to be dominated by the competition of the

S. McNamara, R. Rojo-Garcia, H. J. Herrmann

We apply two theoretical and two numerical methods to the problem of a disk placed in a groove and subjected to gravity and a torque. Methods assuming rigid particles are indeterminate -- certain combinations of forces cannot be calculated, but only constrained by inequalities. In methods assuming deformable particles, these combinations of forces are determ

Andre Eckardt, Christoph Weiss, Martin Holthaus

When calculating the ground-state energy of a weakly interacting Bose gas with the help of the customary contact pseudopotential, one meets an artifical ultraviolet divergence which is caused by the incorrect treatment of the true interparticle interactions at small distances. We argue that this problem can be avoided by retaining the actual, momentum-depend

C. Rüster, C. Gould, T. Jungwirth, J. Sinova

We report the discovery of a super-giant tunneling anisotropic magnetoresistance in an epitaxially grown (Ga,Mn)As/GaAs/(Ga,Mn)As structure. The effect arises from a strong dependence of the electronic structure of ferromagnetic semiconductors on the magnetization orientation rather than from a parallel or antiparallel alignment of the contacts. The key nove

R. Donangelo, A. Hansen, K. Sneppen, S. R. Souza

We study an economic model where agents trade a variety of products by using one of three competing rules: &#34;need&#34;, &#34;greed&#34; and &#34;noise&#34;. We find that the optimal strategy for any agent depends on both product composition in the overall market and composition of strategies in the market. In particular, a strategy that does best on pairw

R. Nath, A. V. Mahajan, N. Buttgen, C. Kegler

The magnetic behavior of the low-dimensional phosphates (Sr,Ba)_2 Cu(PO_4)_2 and BaCuP_2O_7 was investigated by means of magnetic susceptibility and ^{31}P nuclear magnetic resonance (NMR) measurements. We present here the NMR shift K(T), the spin-lattice 1/T_1 and spin-spin 1/T_2 relaxation-rate data over a wide temperature range 0.02 K < T < 300 K. The T-d

P. Capuzzi, P. Vignolo, F. Toschi, S. Succi

We present a theoretical study of the dynamical behavior of a gas made of ultracold fermionic atoms, which during their motions can collide with a much smaller number of thermal bosonic impurities. The atoms are confined inside harmonic traps and the interactions between the two species are treated as due to s-wave scattering with a negative scattering lengt

J. S. Lim, M. Y. Choi, J. Choi, B. J. Kim

We consider a two-dimensional fully frustrated Josephson-junction array driven by combined direct and alternating currents. Interplay between the mode locking phenomenon, manifested by giant Shapiro steps in the current-voltage characteristics, and the dynamic phase transition is investigated at finite temperatures. Melting of Shapiro steps due to thermal fl

Patrik Recher, D. S. Saraga, Daniel Loss

We present electron spin entanglers--devices creating mobile spin-entangled electrons that are spatially separated--where the spin-entanglement in a superconductor present in form of Cooper pairs and in a single quantum dot with a spin singlet groundstate is transported to two spatially separated leads by means of a correlated two-particle tunneling event. T

H. Kimura, Y. Noda, H. Goka, M. Fujita

The nature of charge stripe order and its relationship with structural phase transitions were studied using synchrotron X-ray diffraction in La$_{1.875}$Ba$_{0.125-x}$Sr$_{x}$CuO$_{4}$ ($0.05\leq x\leq 0.10$). For $x=0.05$, as temperature increased, incommensurate superlattice peaks associated with the charge order disappeared just at the structural phase tr

Igor Khavkine, Chung-Hou Chung, Vadim Oganesyan, Hae-Young Kee

We study the formation of an electronic nematic phase characterized by a broken point-group symmetry in interacting fermion systems within the weak coupling theory. As a function of interaction strength and chemical potential, the phase transition between the isotropic Fermi liquid and nematic phase is first order at zero temperature and becomes second order

Scott A. Hughes, Marc Favata, Daniel E. Holz

Gravitational waves from the coalescence of binary black holes carry linear momentum, causing center of mass recoil. This ``radiation rocket&#39;&#39; has important implications for systems with escape speeds of order the recoil velocity. We describe new recoil calculations using high precision black hole perturbation theory to estimate the magnitude of the

Alan Dressler, Augustus Oemler,, Bianca M. Poggianti, Ian Smail

We have formed ``composite spectra&#39;&#39; by combining the integrated-light spectra of individual galaxies in 8 intermediate-redshift and 12 low-redshift clusters of galaxies. Because these composite spectra have much higher signal-to-noise ratios than individual galaxy spectra, they are particularly useful in quantifying general trends in star formation

Uri Keshet, Eli Waxman

We analytically study diffusive particle acceleration in relativistic, collisionless shocks. We find a simple relation between the spectral index s and the anisotropy of the momentum distribution along the shock front. Based on this relation, we obtain s = (3beta_u - 2beta_u*beta_d^2 + beta_d^3) / (beta_u - beta_d) for isotropic diffusion, where beta_u (beta

E. -I. Esch, T. J. Bowles, A. Hime, A. Pichlmaier

In this work a measurement of the muon intensity at the Waste Isolation Pilot Plant (WIPP) near Carlsbad, NM, USA is presented. WIPP is a salt mine with a depth of 655 m. The vertical muon flux was measured with a two panels scintillator coincidence setup to Phi_{vert}=3.10(+0.05/-0.07)*10^(-7)s^(-1)cm^(-2)sr^(-1).

Claus Leitherer

Wolf-Rayet stars are the evolved descendents of massive stars. Their extraordinary properties make them useful tracers of the stellar initial mass function (IMF) in a young stellar population. I discuss how the interpretation of spectral diagnostics are complicated by the interplay of stellar, nebular, and dust properties. There is mounting observational evi

Joseph J Mohr

Galaxy cluster surveys are power tools for studying the dark energy. In principle, the equation of state parameter w of the dark energy and its time evolution can be extracted from large solid angle, high yield surveys that deliver tens of thousands of clusters. Robust constraints require accurate knowledge of the survey selection, and crude cluster redshift

R. Cid Fernandes, Q. Gu, J. Melnick, E. Terlevich

We present a study of the stellar populations in the central ~ 200 pc of a large and homogeneous sample comprising 79 nearby galaxies, most of which are type 2 Seyferts. The star-formation history of these nuclei is reconstructed by means of state-of-the art population synthesis modeling of their spectra in the 3500--5200 A interval. A QSO-like featureless c

B. Stecklum, R. Launhardt, O. Fischer, A. Henden

We report on results of near-infrared and optical observations of the mm disk embedded in the Bok globule CB 26 (Launhardt & Sargent 2001). The near-infrared images show a bipolar reflection nebula with a central extinction lane which coincides with the mm disk. Imaging polarimetry of this object yielded a polarization pattern which is typical for a young st

N. C. Sterling, H. L. Dinerstein

We present results from an ongoing survey of infrared emission lines from the neutron-capture elements Se and Kr in Galactic planetary nebulae (PNe). Se and Kr may be produced in the initial steps of the s-process during the asymptotic giant branch (AGB) phase of PN progenitor stars, and brought to the surface by convective dredge-up before PN ejection. Ther

U. Fritze-v. Alvensleben

I will show that photometry -- if extending over a reasonable choice of passbands -- can give fairly precise information about young star clusters and their evolutionary state. Optical colors alone are known to leave severe ambiguities due to degeneracies between age, metallicity and extinction. High quality photometry including $U, B, V$ or $I$, and a NIR b

Zoltan Haiman

Which came first, the stars and gas that make up a galaxy, or the giant black hole at its centre? Observations of a distant galaxy, caught as it forms, could help solve this chicken-and-egg problem.

Michael Weidinger, Palle Moller, Johan P. U. Fynbo

Quasars are the visible signatures of super-massive black holes in the centres of distant galaxies. It has been suggested that quasars are formed during ``major merger events&#39;&#39; when two massive galaxies collide and merge, leading to the prediction that quasars should be found in the centres of the regions of largest overdensity in the early Universe.

O. H. Guseinov, A. Ankay, S. O. Tagieva

In this work we have analysed various data on radio pulsars and we have shown that magnetic field decay of a factor about 10-20 is necessary to explain their evolution, in particular to remove the discrepancy between the characteristic and the real ages. The character of the field decay is exponential with a characteristic time of about 3$\times10^6$ yr. Obs

H. Lamy, D. Hutsemekers

We report the results of statistical tests performed on a sample of 139 broad absorption line (BAL) QSOs with good quality optical spectra and/or optical polarization data. Correlations between optical indices and the polarization degree p_0 are systematically searched for. In order to identify the most important correlations, we perform a principal componen

Alan J. Penny

SKA would have distinct capabilities for studies associated with extra-solar planets, their formation and properties.

Alan J. Penny

SETI with SKA would be by far the most powerful SETI search ever undertaken, covering enough stars with enough sensitivity to probe significantly further towards those other Earth civilisations than previous ones. This paper discusses the rationale behind radio SETI searches, and explains why SKA will be such as big step forward and will make few demands on

B. Czerny, R. Goosmann

We discuss the local physical changes at the surface of an AGN accretion disk after the onset of a magnetic flare. The X-ray irradiation by a flare creates a hot spot at the disk surface where the plasma both heats up and expands in the vertical direction in order to regain the hydrostatic equilibrium. Assuming that the magnetic loop causing the flare is anc