February 2003 arXiv papers — page 5

Hiroyuki Yoshiguchi, Shigehiro Nagataki, Katsuhiko Sato

We predict the arrival distribution of UHECRs above $4 \times 10^{19}$ eV with the event number expected by future experiments in the next few years. We perform event simulations with the source model which is adopted in our recent study and can explain the current AGASA observation. At first, we calculate the harmonic amplitude and the two point correlation

P. Exner, T. Ichinose

We prove a product formula which involves the unitary group generated by a semibounded self-adjoint operator and an orthogonal projection $P$ on a separable Hilbert space $\HH$, with the convergence in $L^2_\mathrm{loc}(\mathbb{R};\HH)$. It gives a partial answer to the question about existence of the limit which describes quantum Zeno dynamics in the subspa

Jian-gang Hao, Xin-zhou Li

In light of recent study on the dark energy models that manifest an equation of state $w<-1$, we investigate the cosmological evolution of phantom field in a specific potential, exponential potential in this paper. The phase plane analysis show that the there is a late time attractor solution in this model, which address the similar issues as that of fine tu

S. Zhu, U. Garg, B. K. Nayak, S. S. Ghugre

High-spin states in 135Nd were populated with the 110Pd(30Si,5n)135Nd reaction at a 30Si bombarding energy of 133 MeV. Two Delta(I)=1 bands with close excitation energies and the same parity were observed. These bands are directly linked by Delta(I)=1 and Delta(I)=2 transitions. The chiral nature of these two bands is confirmed by comparison with three-dimen

Lawrence J. Hall, Yasunori Nomura, Takemichi Okui, Steven J. Oliver

Explicit supersymmetry breaking is studied in higher dimensional theories by having boundaries respect only a subgroup of the bulk symmetry. If the boundary symmetry is the maximal subgroup allowed by the boundary conditions imposed on the fields, then the symmetry can be consistently gauged; otherwise gauging leads to an inconsistent theory. In a warped fif

Jonathan L. Feng, Arvind Rajaraman, Fumihiro Takayama

We investigate a new class of dark matter: superweakly-interacting massive particles (superWIMPs). As with conventional WIMPs, superWIMPs appear in well-motivated particle theories with naturally the correct relic density. In contrast to WIMPs, however, superWIMPs are impossible to detect in all conventional dark matter searches. We consider the concrete exa

Constantine Yannouleas, Uzi Landman

Exact diagonalization results are reported for the lowest rotational band of N=6 electrons in strong magnetic fields in the range of high angular momenta 70 <= L <= 140 (covering the corresponding range of fractional filling factors 1/5 >= nu >= 1/9). A detailed comparison of energetic, spectral, and transport properties (specifically, magic angular momenta,

J. A. Nieto, M. C. Marin

By combining the concepts of graviton and matroid, we outline a new gravitational theory which we call gravitoid theory. The idea of this theory emerged as an attempt to link the mathematical structure of matroid theory with M-theory. Our observations are essentially based on the formulation of matroid bundle due to MacPherson and Anderson-Davis. Also, by co

Bumseok Kyae, Qaisar Shafi

In a class of realistic four and five dimensional supersymmetric grand unified models, the scalar spectral index is found to be $n_s=0.98 (\pm 0.01)$, in excellent agreement with the values determined by several previous experiments and most recently by the Wilkinson Microwave Anisotropy Probe (WMAP). The models predict $dn_s/d{\rm ln}k\sim 10^{-3}$ and a ne

Vladimir V Chernov, Yuli B Rudyak

Let N_1, N_2, M be smooth manifolds with dim N_1 + dim N_2 +1 = dim M$ and let phi_i, for i=1,2, be smooth mappings of N_i to M with Im phi_1 and Im phi_2 disjoint. The classical linking number lk(phi_1,phi_2) is defined only when phi_1*[N_1] = phi_2*[N_2] = 0 in H_*(M). The affine linking invariant alk is a generalization of lk to the case where phi_1*[N_1]

R. de la Madrid

We discuss the role of boundary conditions in determining the physical content of the solutions of the Schrodinger equation. We study the standing-wave, the ``in,&#39;&#39; the ``out,&#39;&#39; and the purely outgoing boundary conditions. As well, we rephrase Feynman&#39;s $+i ε$ prescription as a time-asymmetric, causal boundary condition, and discuss the c

Lajos Diosi

Time-arrow $s=+/-$, intrinsic to a concrete physical system, is associated with the direction of information loss $ΔI$ displayed by the random evolution of the given system. When the information loss tends to zero the intrinsic time-arrow becomes uncertain. We propose the heuristic relationship $1/[1+exp(-sΔI)]$ for the probability of the intrinsic time-arro

Paul M. Alsing, G. J. Milburn

In this work, we give a description of the process of teleportation between Alice in an inertial frame, and Rob who is in uniform acceleration with respect to Alice. The fidelity of the teleportation is reduced due to Unruh radiation in Rob&#39;s frame. In so far as teleportation is a measure of entanglement, our results suggest that quantum entanglement is

Todd A. Brun, Hsi-Sheng Goan

A requirement for many quantum computation schemes is the ability to measure single spins. This paper examines one proposed scheme: magnetic resonance force microscopy, including the effects of thermal noise and back-action from monitoring. We derive a simplified equation using the adiabatic approximation, and produce a stochastic pure state unraveling which

Milena D&#39;Angelo, Yanhua Shih

Quantum imaging has been demonstrated since 1995 by using entangled photon pairs. The physics community named these experiments &#34;ghost image&#34;, &#34;quantum crypto-FAX&#34;, &#34;ghost interference&#34;, etc. Recently, Bennink et al. simulated the &#34;ghost&#34; imaging experiment by two co-rotating k-vector correlated lasers. Did the classical simul

Alexei Kaltchenko, En-Hui Yang

We prove that the stationarity and the ergodicity of a quantum source are preserved by any trace-preserving completely positive linear map of the tensor product form ${\cal E}^{\otimes m}$, where a copy of ${\cal E}$ acts locally on each spin lattice site. We also establish ergodicity criteria for so called classically-correlated quantum sources.

Enrique Ordaz Romay

All physical process are subject to some laws which determine with math accurately its time-space evolution. These laws are described, in the last analysis for the principle of causality. The physical space can be homogeneous or heterogeneous in function of the distribution of the physical magnitudes. Applying the principle of causality to the homogeneous sp

A. P. Saiko

Some aspects of lasing at vibronic transitions in impurity crystals are theoretically studied. The threshold conditions for a vibronic laser are shown to be dependent on the strength of interaction of optical centers with a local vibration, which forms the vibronic spectrum, and the crystal lattice temperature. The theory can be easily generalized to the spe

Slobodan Prvanovic

The portrait of Mona Lisa is scrutinized with reference to quantum mechanics. The elements of different expressions are firstly recognized on her face. The contradictory details are then classified in two pictures that, undoubtedly representing distinct moods, confirm dichotomous character of the original. Consecutive discussion has lead to conclusion that t

E. J. Stephenson, R. C. Johnson, F. Sammarruca

This paper presents the first calculations of proton inelastic scattering in which the medium effect of Pauli blocking is included through an exact, rather than angle averaged, operator. This improvement is important in the isoscalar channel at proton energies near 100 MeV and fades as the energy rises. However, processes that emphasize finite-range exchange

E. Bauer

We have performed a many-body calculation of the longitudinal nuclear $(e,e&#39;)$ reaction employing a Second RPA (SRPA) formalism which contains the $Δ$(1232). More explicitly, our scheme contains RPA correlations as well as Hartree-Fock and second order self-energies, where an accurate evaluation of exchange terms is achieved. Using this formalism we have

Yee Tat-leung, R. Conte, M. Musette

Even if it is nonintegrable, a differential equation may nevertheless admit particular solutions which are globally analytic. On the example of the dynamical system of Kuramoto and Sivashinsky, which is generically chaotic and presents a high physical interest, we review various methods, all based on the structure of singularities, allowing us to characteriz

A. N. Skripka

The approach allowing is considered to represent the solutions such as stationary lonely waves of various nonlinear wave the equations as system of the ordinary differential equations in variable action - angle.

G. Lusztig

The theory of character sheaves on a reductive group is extended to a class of varieties which includes the strata of the De Concini-Procesi completion of an adjoint group.

C. Dong, C. H. Lam, K. Tanabe, H. Yamada

The W_3 algebra of central charge 6/5 is realized as a subalgebra of the vertex operator algebra V_{\sqrt{2}A_2} associated with a lattice of type \sqrt{2}A_2 by using both coset construction and orbifold theory. It is proved that W_3 is rational. Its irreducible modules are classified and constructed explicitly. The characters of those irreducible modules a

Christophe Hohlweg

Let W be a finite Coxeter group. In this paper, we show that the properties of the Solomon algebra homomorphism Phi (from the Solomom descent algebra to the algebra of class functions) are strongly related to enumerative results: certain joint statistics on W may be enumerated by the scalar products of appropriate characters.

Stephen Semmes

These informal notes, initially prepared a few years ago, look at various questions related to infinite processes in several parts of mathematics, with emphasis on examples.

W. J. van Hoeve

This work presents a hybrid approach to solve the maximum stable set problem, using constraint and semidefinite programming. The approach consists of two steps: subproblem generation and subproblem solution. First we rank the variable domain values, based on the solution of a semidefinite relaxation. Using this ranking, we generate the most promising subprob

Mikhail G. Katz

P. Buser and P. Sarnak showed in 1994 that the maximum, over the moduli space of Riemann surfaces of genus s, of the least conformal length of a nonseparating loop, is logarithmic in s. We present an application of (polynomially) dense Euclidean packings, to estimates for an analogous 2-dimensional conformal systolic invariant of a 4-manifold X with indefini

Gunther Uhlmann, Andras Vasy

We survey finite energy inverse results in N-body scattering, and we also sketch the proof of the extension of our recent two-cluster to two-cluster three-body result to the many-body case: this requires only minor modifications. We also indicate how to extend a free-to-free inverse result in three-body scattering to the many-body case.

Amitai Regev, Yuval Roichman

Let $A_n\subseteq S_n$ denote the alternating and the symmetric groups on $1,...,n$. MacMahaon&#39;s theorem, about the equi-distribution of the length and the major indices in $S_n$, has received far reaching refinements and generalizations, by Foata, Carlitz, Foata-Schutzenberger, Garsia-Gessel and followers. Our main goal is to find analogous statistics a

C. Kapoudjian, V. Sergiescu

We study some aspects of the geometric representation theory of the Thompson and Neretin groups, suggested by their analogies with the diffeomorphism groups of the circle. We prove that the Burau representation of the Artin braid groups extends to a mapping class group $A_T$ related to Thompson&#39;s group $T$ by a short exact sequence $B_{\infty}\hookrighta

Hongling Su, Mengzhao Qin

The multi-symplectic form for Hamiltonian PDEs leads to a general framework for geometric numerical schemes that preserve a discrete version of the conservation of symplecticity. The cases for systems or PDEs with dissipation terms has never been extended. In this paper, we suggest a new extension for generalizing the multi-symplectic form for Hamiltonian sy

Alina Vdovina

We construct compact polyhedra with $m$-gonal faces whose links are generalized 3-gons. It gives examples of cocompact hyperbolic bildings of type $P(m,3)$. For $m=3$ we get compact spaces covered by Euclidean buildings of type $A_2$.

Michael Hitrik, Johannes Sjoestrand

This is the first in a series of works devoted to small non-selfadjoint perturbations of selfadjoint $h$-pseudodifferential operators in dimension 2. In the present work we treat the case when the classical flow of the unperturbed part is periodic and the strength $ε$ of the perturbation is $\gg h$ (or sometimes only $\gg h^2$) and bounded from above by $h^δ

Jason Fulman

We study deformations of the Plancherel measure of the symmetric group by lifting them to the symmetric group and using combinatorics of card shuffling. The existing methods for analyzing deformations of Plancherel measure are not obviously applicable to the examples in this paper. The main idea of this paper is to find and analyze a formula for the total va

JeongHyeong Park

Let (M,g,J) be a compact Hermitian manifold with a smooth boundary. Let $Δ_p$ and $D_p$ be the realizations of the real and complex Laplacians on p forms with either Dirichlet or Neumann boundary conditions. We generalize previous results in the closed setting to show that (M,g,J) is Kaehler if and only if $Spec(Δ_p)=Spec(2D_p)$ for p=0,1. We also give a cha

Hans-Joachim Baues, Davide L. Ferrario

A stratified bundle is a fibered space in which strata are classical bundles and in which attachment of strata is controlled by a structure category of fibers. Well known results on fibre bundles are shown to be true for stratified bundles; namely the pull back theorem, the bundle theorem and the principal bundle theorem.

Adam Van Tuyl

The Hilbert functions of sets of distinct points in P^n have been characterized. We show that if we restrict to sets of distinct of points in P^{n_1} x ... x P^{n_k} that are also arithmetically Cohen-Macaulay (ACM for short), then there is a natural generalization of this result. We begin by determining the possible values for the invariants K-dim R/Ix and

Christian Fronsdal

Varchenko&#39;s approach to quantum groups, from the theory of arrangements of hyperplanes, can be usefully applied to q-algebras in general, of which quantum groups and quantum (super) Kac-Moody algebras are special cases. New results are obtained on the classification of q-algebras, and of the Serre ideals of generalized quantum (super) Kac-Moody algebras.

J"urgen Fuchs, Ingo Runkel, Christoph Schweigert

The interpretation of D-branes in terms of open strings has lead to much interest in boundary conditions of two-dimensional conformal field theories (CFTs). These studies have deepened our understanding of CFT and allowed us to develop new computational tools. The construction of CFT correlators based on combining tools from topological field theory and non-

G. W. Gibbons

Motivated by some recent speculative attempts to model the dark energy, scalar fields with negative kinetic energy coupled to gravity without a cosmological constant are considered. It is shown that in the presence of an ordinary fluid, any solution of the vacuum Einstein equations with cosmological constant is a solution provided $ρ-P={Λ\over 4 πG}$. The so

Yutaka Sakamura

We propose a modified mode-expansion of the bulk fields in a BPS domain wall background to obtain the effective theory on the wall. The broken SUSY is nonlinearly realized on each mode defined by our mode-expansion. Our work clarifies a relation between two different approaches to derive the effective theory on a BPS wall, {\it i.e.} the nonlinear realizatio

H. V. Klapdor-Kleingrothaus

Double beta decay is indispensable to solve the question of the neutrino mass matrix together with $ν$ oscillation experiments. Recent analysis of the most sensitive experiment since nine years - the HEIDELBERG-MOSCOW experiment in Gran-Sasso - yields a first indication for the neutrinoless decay mode. This result is the first evidence for lepton number viol

Lance Dixon, M. Stewart Siu

A low mass Standard Model Higgs boson should be visible at the Large Hadron Collider through its production via gluon-gluon fusion and its decay to two photons. We compute the interference of this resonant process, gg -> H -> gamma gamma, with the continuum QCD background, gg -> gamma gamma induced by quark loops. Helicity selection rules suppress the effect

Daniel Boer, Rainer Jakob, Marco Radici

We study the process of electron-positron annihilation into back-to-back jets, where in each jet a pair of hadrons is detected. The orientation of these two pairs with respect to each other can be used to extract the interference fragmentation functions in a clean way, for instance from BELLE or BABAR experiment data. This is of relevance for studies of the

Edward Shuryak, Ismail Zahed

A semiclassical theory of high energy scattering based on interrupted tunneling (instantons) or QCD sphaleron production has been recently developed to describe the growing hadronic cross section and properties of the soft Pomeron. In this work we address double-pomeron processes in this framework for the first time. We specifically derive the cross section

Khin Maung Maung, Charles A. Hill, Michael T. Hill, George DeRise

We consider the correspondence between solutions of non-gravitational field theories formulated in Euclidean space-time and Minkowski space-time. Infinitely many &#34;Euclidean&#34; spaces can be obtained from M4 via a group of transformations in which the Wick rotation is a special case. We then discuss how the solutions of gauge field theories formulated i

C. S. Lam

In the braneworld scenario, gravity and neutrino oscillation can both be used to detect the presence of an extra dimension. We argue that neutrino oscillation is particularly suitable if the size of the extra dimension is small, in which case the signature for the extra dimension is the disappearance of active neutrino fluxes into the bulk, caused by the des

Roberto Emparan

In this talk I briefly discuss some features of a striking signature of TeV quantum gravity/strings and large extra dimensions: the production of exotic objects such as black holes, and their stringy precursors, the string resonances at large masses which can be dubbed `string balls&#39;. The focus is on aspects less frequently discussed in other reviews of

Henrik Johansson

Particles are either bosons or fermions, which obey Bose-Einstein (BE) or Fermi-Dirac statistics, respectively. In the hadronization process the effects of the former kind are the most important ones, since mesons are the most common products in high-energy collisions. In the phenomenological Lund Model the BE effect is approximated by a semiclassical moment

Alessandro De Angelis

Among the many topics related to soft QCD in which Bo Andersson gave an important contribution to experiments, this report selects a few for which the final word has not yet been pronounced.

L. Lavoura

At one-loop level the decay f1 --> f2 gamma, where f1 and f2 are two spin-1/2 particles with the same electric charge, is mediated by a boson B and a spin-1/2 fermion F. The boson B may have either spin 0 - interacting with the fermions through Dirac matrices 1 and gamma5 - or spin 1 - with V+A and V-A couplings to the fermions. I give general formulae for t

N. N. Achasov, G. N. Shestakov

The results of the recent experiments on the reaction $π^-p\toπ^0π^0n$ performed at KEK, BNL, IHEP, and CERN are analyzed in detail. For the I=0 $ππ$ S wave phase shift $δ^0_0$ and inelasticity $η^0_0$ a new set of data is obtained. Difficulties emerging when using the physical solutions for the $π^0π^0$ S and D wave amplitudes extracted with the partial wav

Deepak Chandra, Ashok Goyal

We study the dynamics of first-order cofinement-deconfinement phase transition through nucleation of hadronic bubbles in an expanding quark gluon plasma in the context of heavy ion collisions for interacting quark and hadron gas and by incorporating the effects of curvature energy. We find that the interactions reduce the delay in the phase transition wherea

Bruno Autin, Deborah A. Harris, Steve F. King, Kevin S. McFarland

Issues on the physics of, beamlines for, and detectors of neutrino oscillation discussed in Working Group 2 at Nufact&#39;02 are summarized.

Andrew G. Cohen, David B. Kaplan, Emanuel Katz, Mithat Unsal

We formulate a Euclidean spacetime lattice whose continuum limit is (2,2) supersymmetric Yang-Mills theory in two dimensions, a theory which possesses four supercharges and an anomalous global chiral symmetry. The lattice action respects one exact supersymmetry, which allows the target theory to emerge in the continuum limit without fine-tuning. Our method e

J. B. Kogut, D. K. Sinclair

We study the finite temperature phase transition of lattice QCD with an irrelevant chiral 4-fermion interaction and two massless quark flavours, on $8^3 \times 4$ and $12^2 \times 24 \times 4$ lattices. The strength of the 4-fermion interaction was reduced to half the minimum value used in previous simulations, to study how the nature of this phase transitio

Kai-Peer O. Diener, Christian Schwanenberger, Michael Spira

A procedure of implementing QCD corrections in Monte Carlo programs by a reweighting method is described for the photoproduction of W bosons at HERA. Tables for W boson production in LO and NLO are given in bins of the transverse momentum of the W boson and its rapidity.

M. Kaya

The production of $D_s^-$ relative to $D_s^+$ as a function of $x_F $ with 600 GeV/c $Σ^-$ beam is measured in the interval $0.15 < x_F < 0.7$ by the SELEX (E781) experiment at Fermilab. The integrated charge asymmetries with 600 GeV/c $Σ^-$ beam ($0.53\pm0.06$) and $π^-$ beam ($0.06\pm0.11$) are also compared. The results show the $Σ^-$ beam fragments play

Supriya Jain, Naba K. Mondal, Dhiman Chakraborty

We present a preliminary result on a search for narrow-width resonances that decay into ttbar pairs using 130 pb^{-1} of lepton plus jets data in ppbar collisions at center of mass energy = 1.8 TeV. No significant deviation from Standard Model prediction is observed. 95% C.L. upper limits on the production cross section of the narrow-width resonance times it

Lino Miramonti, Franco Reseghetti

Solar neutrino physics is an exciting and difficult field of research for physicists, where astrophysics, elementary particle and nuclear physics meet. \ The Sun produces the energy that life has been using on Earth for many years, about $10^9$ y, emits a lot of particles: protons, electrons, ions, electromagnetic quanta... among them neutrinos play an impor

Michael D. Hartl

We investigate the dynamics of the Papapetrou equations in Kerr spacetime. These equations provide a model for the motion of a relativistic spinning test particle orbiting a rotating (Kerr) black hole. We perform a thorough parameter space search for signs of chaotic dynamics by calculating the Lyapunov exponents for a large variety of initial conditions. We

Ted Jacobson, Renaud Parentani

Although the laws of thermodynamics are well established for black hole horizons, much less has been said in the literature to support the extension of these laws to more general settings such as an asymptotic de Sitter horizon or a Rindler horizon (the event horizon of an asymptotic uniformly accelerated observer). In the present paper we review the results

Geoffery Ericksson, Susan M. Scott

Much of the published work regarding the Isotropic Singularity is performed under the assumption that the matter source for the cosmological model is a barotropic perfect fluid, or even a perfect fluid with a $γ$-law equation of state. There are, however, some general properties of cosmological models which admit an Isotropic Singularity, irrespective of the

J. Jaroszynski, Dragana Popovic, T. M. Klapwijk

Studies of low-frequency resistance noise show that the glassy freezing of the two-dimensional electron system (2DES) in Si in the vicinity of the metal-insulator transition (MIT) persists in parallel magnetic fields B of up to 9 T. At low B, both the glass transition density $n_g$ and $n_c$, the critical density for the MIT, increase with B such that the wi

M. El Massalami, R. E. Rapp, F. A. B. Chaves, H. Takeya

Zero-field specific heat of the single crystals RNi2B2C (R= Er, Ho, Dy, Tb, Gd) was measured within the temperature range 0.1 K<T<25 K. Linearized spin wave analysis was successfully applied to account for and to rationalize the thermal evolution of the low--temperature magnetic specific heats of all the studied compounds (as well as the one reported for TmN

P. L. Krapivsky, E. Ben-Naim

We investigate the kinetics of nonlinear collision-induced fragmentation. We obtain the fragment mass distribution analytically by utilizing its travelling wave behavior. The system undergoes a shattering transition in which a finite fraction of the mass is lost to infinitesimal fragments (dust). The nature of the shattering transition depends on the fragmen

Yuriy V. Pershin, Vladimir Privman

We study the evolution and distribution of non-equilibrium electron spin polarization in n-type semiconductors within the two-component drift-diffusion model in an applied electric field. Propagation of spin-polarized electrons through a boundary between two semiconductor regions with different doping levels is considered. We assume that inhomogeneous spin p

Burkhard Militzer, Francois Gygi, Giulia Galli

Using first principles simulations we have investigated the structural and bonding properties of dense fluid oxygen up to 180 GPa. We have found that band gap closure occurs in the molecular liquid, with a &#34;slow&#34; transition from a semi-conducting to a poor metallic state occurring over a wide pressure range. At approximately 80 GPa, molecular dissoci

M. El Massalami, H. Takeya, K. Hirata, M. Amara

Extensive magnetization and magnetostriction measurements were carried out on a single crystal of GdNi2B2C along the main tetragonal axes. Within the paramagnetic phase, the magnetic and strain susceptibilities revealed a weak anisotropy in the exchange couplings and two-ion tetragonal-preserving alpha-strain modes. Within the ordered phase, magnetization an

I. P. Raevski, S. A. Prosandeev, S. M. Emelyanov, F. I. Savenko

(1-x)PbMg1/3Nb2/3O3-(x)PbSc1/2Nb1/2O3 (PMN-PSN) solid solution crystals have been grown by the flux method in the whole concentration range. X-ray supercell reflections due to B-cation ordering were observed for as-grown crystals from the 0.1 < x < 0.65 compositional range. Though the ordered domains are rather large (~50 nm) the relaxor-like dielectric beha

R. Delgado-Buscalioni, P. V. Coveney

The aim of hybrid methods in simulations is to communicate regions with disparate time and length scales. Here, a fluid described at the atomistic level within an inner region P is coupled to an outer region C described by continuum fluid dynamics. The matching of both descriptions of matter is made across an overlapping region and, in general, consists of a

David S. Hall

This Resource Letter provides a guide to the literature on Bose-Einstein condensation in trapped dilute gases. Journal articles and books are cited for the following topics: history, technological advances, condensates as quantum fluids, effects of interatomic interactions, condensates as matter waves, condensate optics, multiple condensates, lower dimension

S. De Franceschi, J. A. van Dam, E. P. A. M. Bakkers, L. F. Feiner

We report on the fabrication and electrical characterization of field-effect devices based on wire-shaped InP crystals grown from Au catalyst particles by a vapor-liquid-solid process. Our InP wires are n-type doped with diameters in the 40-55 nm range and lengths of several microns. After being deposited on an oxidized Si substrate, wires are contacted indi

Victor M. Eguiluz, Emilio Hernandez-Garcia, Oreste Piro, Konstantin Klemm

We introduce appropriate definitions of dimensions in order to characterize the fractal properties of complex networks. We compute these dimensions in a hierarchically structured network of particular interest. In spite of the nontrivial character of this network that displays scale-free connectivity among other features, it turns out to be approximately one

C. Richard, I. Jensen, A. J. Guttmann

Exactly solvable models of planar polygons, weighted by perimeter and area, have deepened our understanding of the critical behaviour of polygon models in recent years. Based on these results, we derive a conjecture for the exact form of the critical scaling function for planar self-avoiding polygons. The validity of this conjecture was recently tested numer

Nils Eissfeldt, Peter Wagner

Anticipation in traffic means that drivers estimate their leaders&#39; velocities for future timesteps. In the article a specific stochastic car--following model with non--unique flow--density relation is investigated with respect to anticipatory driving. It is realized by next--nearest--neighbour interaction which leads to large flows and short temporal hea

Yu. A. Nefyodov, M. R. Trunin

The linear microwave response of ultra high-quality YBa$_2$Cu$_3$O$_x$ single crystals grown in BaZrO$_3$ crucibles is measured at 9.4 GHz in rf magnetic fields parallel and perpendicular to the $ab$-plane in the temperature range 5$\leq T\leq 200$ K. Having found the analytic solution for the magnetic field distribution on the sample surface we determine bo

Yu. A. Nefyodov, M. R. Trunin, A. A. Zhohov, I. G. Naumenko

An electrodynamic technique is developed for determining the components of surface impedance and complex conductivity tensors of HTSC single crystals on the basis of measured quantities of a quality factor and a resonator frequency shift. A simple formula is obtained for a geometrical factor of a crystal in the form of a plate with dimensions $b\gg a>c$ in a

Michael Patra

The lasing threshold of a random laser is computed numerically from a generic model. It is shown that spatial correlations of the disorder in the medium (i.e., dielectric constant) lead to an increase of the decay rates of the eigenmodes and of the lasing threshold. This is in conflict with predictions that such correlations should lower the threshold. While

David A. Kessler, Yitzhak Rabin

We develop a novel biased Monte-Carlo simulation technique to measure the force-extension curves and the distribution function of the extension of fluctuating filaments stretched by external force. The method is applicable for arbitrary ratio of the persistence length to the contour length and for arbitrary forces. The simulation results agree with analytic

Chetan Nayak, Xiao Yang

In a dirty metal, electron-electron interactions in the spin-triplet channel lead to singular corrections to a variety of physical quantities. We show that these singularities herald the emergence of ferromagnetism. We calculate the effective action for the magnetic moment of weakly-interacting electrons in a dirty metal and show that a state with finite fer

Indrani Bose, Rajesh Karmakar, Siddhartha Roy

In this paper, we consider two stochastic models of gene expression in prokaryotic cells. In the first model, sixteen biochemical reactions involved in transcription, translation and transcriptional regulation in the presence of inducer molecules are considered. The time evolution of the number of biomolecules of a particular type is determined using the sto

Joshua G. Nollenberg, Liliya L. R. Williams, Steve J. Maddox

Existing observations are consistent with rich clusters of galaxies having no dust on $\simgt$ Mpc scales, while galaxy groups most probably do have dust distributed over $\lesssim$ Mpc scales. Dust in groups accounts for the observed redshift asymmetries of their galaxy distributions, and about $E(B-V)\sim 0.1-0.2$ mag of reddening. Motivated by these resul

Michael Kesden, Asantha Cooray, Marc Kamionkowski

Weak gravitational lensing by intervening large-scale structure induces a distinct signature in the cosmic microwave background (CMB) that can be used to reconstruct the weak-lensing displacement map. Estimators for individual Fourier modes of this map can be combined to produce an estimator for the lensing-potenial power spectrum. The naive estimator for th

T. M. Tripp, B. P. Wakker, E. B. Jenkins, C. W. Bowers

(Abridged) We present a new high-resolution (7 km/s FWHM) echelle spectrum of 3C 351 obtained with STIS. 3C 351 lies behind the low-latitude edge of high-velocity cloud Complex C, and the new spectrum provides accurate measurements of O I, Si II, Al II, Fe II, and Si III absorption lines at the velocity of the HVC. We use collisional and photoionization mode

L. J. Greenhill, R. S. Booth, S. P. Ellingsen, J. R. Herrnstein

We present the first VLBI maps of H2O maser emission (lambda 1.3cm) in the nucleus of the Circinus Galaxy, constructed from data obtained with the Australia Telescope Long Baseline Array. The maser emission traces a warped, edge-on accretion disk between radii of 0.11+/-0.02 and ~0.40 pc, as well as a wide-angle outflow that extends up to ~1 pc from the esti

Smita Mathur, Rik J. Williams

We report on a discovery of a candidate cluster of galaxies at redshift z=1.47 based on Chandra observations in the field of quasars UM425 A & B. We detect with high significance diffuse emission due the intracluster hot gas around the quasar pair. This is the second highest redshift cluster candidate after 3C294 at z=1.786. The diffuse emission is elliptica

K. M. Perrett, D. A. Stiff, D. A. Hanes, T. J. Bridges

In the most prominent current scenario of galaxy formation, galaxies form hierarchically through the merger of smaller systems. Such mergers could leave behind dynamical signatures which may linger long after the event. In particular, the globular cluster system (GCS) of a merging satellite galaxy may remain as a distinct sub-population within the GCS of a m

B. J. McNamara, T. E. Harrison, R. T. Zavala, Eduardo Galvan

In 1970, Hiltner & Mook reported the results of the first multiyear study of the optical emission from Sco X-1. They found that the Sco X-1 B-magnitude histograms changed from year to year. Subsequent multi-wavelength campaigns confirmed the variable nature of these optical histograms and also found that the X-ray and optical emissions were only correlated w

C. L. Carilli, R. Ivison, D. Frail

We present 1.4 GHz VLA observations of the variability of radio sources in the Lockman Hole region at the level of > 100 uJy on timescales of 17 months and 19 days. These data indicate that the areal density of highly variable sources at this level is < 0.005 arcmin^{-2}. We set an upper limit of 2% to the fraction of 50 to 100uJy sources that are highly var

Ralf S. Klessen, Doug N. C. Lin

We investigate diffusion in supersonic, turbulent, compressible flows. Supersonic turbulence can be characterized as network of interacting shocks. We consider flows with different rms Mach numbers and where energy necessary to maintain dynamical equilibrium is inserted at different spatial scales. We find that turbulent transport exhibits super-diffusive be

J. E. Gizis, I. N. Reid, G. R. Knapp, J. Liebert

We present analysis of Hubble Space Telescope images of 82 nearby field late-M and L dwarfs. We resolve 13 of these systems into double M/L dwarf systems and identify an additional possible binary. Combined with previous observations of 20 L dwarfs, we derive an observed binary fraction for ultracool dwarfs of 17+4-3%, where the statistics included systems w

Alessandro Marconi, Roberto Maiolino, Romain G. Petrov

Interferometry in the optical and near infrared has so far played a marginal role in Extragalactic Astronomy. Active Galactic Nuclei are the brightest and most compact extragalactic sources, nonetheless only a very limited number could be studied with speckle interferometry and none with long baseline interferometry. The VLTI will allow the study of moderate

Lennart Lindegren, Dainis Dravins

Accuracy levels of metres per second require the fundamental concept of &#39;radial velocity&#39; for stars and other distant objects to be examined, both as a physical velocity, and as measured by spectroscopic and astrometric techniques. Aiming at definitions that are unambiguous at accuracy levels of 1 m/s, we analyse different concepts of radial velocity

E. Athanassoula

Angular momentum exchange is a driving process for the evolution of barred galaxies. Material at resonance in the bar region loses angular momentum which is taken by material at resonance in the outer disc and/or the halo. By losing angular momentum, the bar grows stronger and slows down. This evolution scenario is backed by both analytical calculations and

J. A. Stevens, D. C. Hannikainen, Kinwah Wu, R. W. Hunstead

At radio frequencies, the current evidence for the microquasar-quasar connection is based on imaging observations showing that relativistic outflows/jets are found in both classes of objects. Some microquasars also display superluminal motion, further strengthening the view that microquasars are in fact Galactic miniatures of quasars. Here we demonstrate tha

E. Athanassoula

Isolated barred galaxies evolve by redistributing their angular momentum, which, emitted by material in the inner disc at resonance with the bar, can be absorbed by resonant material in the outer disc, or in the halo. The amount of angular momentum that can be emitted/absorbed at a given resonance depends on the distribution function of the emitting/absorbin

C. M. Raiteri, M. Villata, G. Tosti, R. Nesci

Eight optical and four radio observatories have been intensively monitoring the BL Lac object 0716+714 in the last years: 4854 data points have been collected in the UBVRI bands since 1994, while radio light curves extend back to 1978. Many of these data are presented here for the first time. The long-term trend shown by the optical light curves seems to var