November 2005 arXiv papers — page 2

Juan B. Gil, Thomas Krainer, Gerardo A. Mendoza

We present an overview of some of our recent results on the existence of rays of minimal growth for elliptic cone operators and two new results concerning the necessity of certain conditions for the existence of such rays.

Eguchi Mitsuaki, Tomoyuki Takenawa

Some Weyl group acts on a family of rational varieties obtained by successive blow-ups at $m$ ($m\geq n+2$) points in the projective space $\mpp^n(\mc)$. In this paper we study the case where all the points of blow-ups lie on a certain elliptic curve in $\mpp^n$. Investigating the action of Weyl group on the Picard groups on the elliptic curve and on rationa

Tomasz Maszczyk

We present a recursive algorithm computing all the genus-zero Gromov-Witten invariants from a finite number of initial ones, for Fano varieties with generically tame semi-simple quantum (and small quantum) (p, p)- type cohomology, whose first Chern class is a strictly positive combination of effective integral basic divisors.

Tomasz Maszczyk

The structure of filtered algebras of Grothendieck's differential operators of truncated polynomials in one variable and graded Poisson algebras of their principal symbols is explicitly determined. A related infinitesimal-birational duality realized by a Springer type resolution of singularities and the Fourier transformation is presented. This algebro-g

Tomasz Maszczyk

We characterize, among all rational curves in the grassmannian G(d, 2d), those which are GL(2d)-equivalent to the canonical morphism induced by the Morita equivalence C-Mod -> M(d)-Mod.

Mark Elin, David Shoikhet, Lawrence Zalcman

In this paper, we study conditions which ensure the existence of backward flow invariant domains for semigroups of holomorphic self-mappings of a simply connected domain $D$. More precisely, the problem is the following. Given a one-parameter semigroup $\mathcal S$ on $D$, find a simply connected subset $Ω\subset D$ such that each element of $\mathcal S$ is

Steve Clark, Fritz Gesztesy

We provide a comparative treatment of some aspects of spectral theory for self-adjoint and non-self-adjoint (but J-self-adjoint) Dirac-type operators connected with the defocusing and focusing nonlinear Schrödinger equation, of relevance to nonlinear optics. In addition to a study of Dirac and Hamiltonian systems, we also introduce the concept of Weyl-Titchm

Jean Mairesse, Frédéric Mathéus

Let G be a free product of a finite family of finite groups, with the set of generators being formed by the union of the finite groups. We consider a transient nearest-neighbour random walk on G. We give a new proof of the fact that the harmonic measure is a special Markovian measure entirely determined by a finite set of polynomial equations. We show that i

Jean Mairesse, Frédéric Mathéus

This paper is an appendix to the paper "Random walks on free products of cyclic groups" by J.Mairesse and F.Mathéus. It contains the details of the computations and the proofs of the results concerning the examples treated there.

Ilya Kapovich, Igor Rivin, Paul Schupp, Vladimir Shpilrain

In this article we relate two different densities. Let $F_k$ be the free group of finite rank $k \ge 2$ and let $α$ be the abelianization map from $F_k$ onto $ \mathbb{Z}^k$. We prove that if $S \subseteq \mathbb{Z}^k$ is invariant under the natural action of $SL(k, \mathbb{Z})$ then the asymptotic density of $S$ in $\mathbb Z^k$ and the annular density of i

Donu Arapura, Su-Jeong Kang

It is shown that if the generalized Hodge conjecture, or some weaker form of it, holds for a Calabi-Yau variety then it holds for any Calabi-Yau variety birationally equivalent to it. The key idea is to construct suitable homomorphisms between the Grothendieck group of varieties and the Grothendieck group of the exact category of filtered Hodge structures. T

Vladimir Batchenko, Fritz Gesztesy

We characterize the spectrum of one-dimensional Jacobi operators H=aS^{+}+a^{-}S^{-}+b in l^{2}(\Z) with quasi-periodic complex-valued algebro-geometric coefficients (which satisfy one (and hence infinitely many) equation(s) of the stationary Toda hierarchy) associated with nonsingular hyperelliptic curves. The spectrum of H coincides with the conditional st

I. Krichever

We prove that an indecomposable principally polarized abelian variety $X$ is the Jacobain of a curve if and only if there exist vectors $U\neq 0,V$ such that the roots $x_i(y)$ of the theta-functional equation $θ(Ux+Vy+Z)=0$ satisfy the equations of motion of the {\it formal infinite-dimensional Calogero-Moser system}

Kiran S. Kedlaya

We exhibit a quantum algorithm for determining the zeta function of a genus g curve over a finite field F_q, which is polynomial in g and log(q). This amounts to giving an algorithm to produce provably random elements of the class group of a curve, plus a recipe for recovering a Weil polynomial from enough of its cyclic resultants. The latter effectivizes a

Vitor Araujo, Maria Jose' Pacifico

We study the dynamics of generic unfoldings of saddle-node circle local diffeomorphisms from the measure theoretical point of view, obtaining statistical stability results for deterministic and random perturbations in these kind of one-parameter families.

Ismar Volic

We describe Taylor towers for spaces of knots arising from Goodwillie-Weiss calculus of the embedding functor and extend the configuration space integrals of Bott and Taubes from spaces of knots to the stages of the towers. We show that certain combinations of integrals, indexed by trivalent diagrams, yield cohomology classes of the stages of the tower, just

Herbert W. Hamber, Ruth M. Williams

Quantum gravity is investigated in the limit of a large number of space-time dimensions, using as an ultraviolet regularization the simplicial lattice path integral formulation. In the weak field limit the appropriate expansion parameter is determined to be $1/d$. For the case of a simplicial lattice dual to a hypercube, the critical point is found at $k_c/λ

Axel Maas

In the Gribov-Zwanziger scenario the confinement of gluons is attributed to an enhancement of the spectrum of the Faddeev-Popov operator near eigenvalue zero. This has been observed in functional and also in lattice calculations. The linear rise of the quark-anti-quark potential and thus quark confinement on the other hand seems to be connected to topologica

Predrag Prester

We analyze near horizon behavior of small D-dimensional 2-charge black holes by modifying tree level effective action of heterotic string with all extended Gauss-Bonnet densities. We show that there is a nontrivial and unique choice of parameters, independent of D, for which the black hole entropy in any dimension is given by 4π\sqrt{nw}, which is exactly th

N. T. Yilmaz

We perform the non-linear realisation or the coset formulation of the pure N=4, D=5 supergravity. We derive the Lie superalgebra which parameterizes a coset map whose induced Cartan-Maurer form produces the bosonic field equations of the pure N=4, D=5 supergravity by canonically satisfying the Cartan-Maurer equation. We also obtain the first-order field equa

Kiyoshi Higashijima, Etsuko Itou

In this paper, we study three dimensional NL$σ$Ms within two kind of nonperturbative methods; WRG and large-N expansion. First, we investigate the renormalizability of some NL$σ$Ms using WRG equation. We find that some models have a nontrivial UV fixed point and are renormalizable within nonperturbative method. Second, we study the phase structure of $CP^{N-

D. Kharzeev

A new thermalization scenario for heavy ion collisions is discussed. It is based on the Hawking--Unruh effect: an observer moving with an acceleration $a$ experiences the influence of a thermal bath with an effective temperature $T = a / 2π$, similar to the one present in the vicinity of a black hole horizon. In the case of heavy ion collisions, the accelera

Borut Bajc, Alejandra Melfo, Goran Senjanovic, Francesco Vissani

Neutrino and charged fermion masses provide important constraints on grand unified theories. We illustrate this by focusing on a renormalizable, supersymmetric SO(10) theory proposed long ago, that recently attracted great interest in view of its minimality. We show how the nature of the light Higgs, which depends on the GUT scale fields, gets reflected on t

G. Zanderighi

We present a semi-numerical method to compute one-loop corrections to processes involving many particles. We treat in detail cases with up to five external legs and massless internal propagators, although the method is more general.

G. Zanderighi

We point out that a study of event shapes at hadron colliders allows to explore novel aspects of QCD. These studies are today made easier by the development of a program which automates the resummation.

Giuliano Panico, Marco Serone

The dynamics of five dimensional Wilson line phases at finite temperature is studied in the one-loop approximation. We show that at temperatures of order $T\sim 1/L$, where L is the length of the compact space, the gauge symmetry is always restored and the electroweak phase transition appears to be of first order. We focus on a specific model where the Wilso

G. Zanderighi

We illustrate the use of effective theory methods to describe resonant unstable particles. We outline the necessary ingredients to describe $W$-pair production close to threshold in $e^-e^+$ collisions.

B. I. Ermolaev, M. Greco, S. I. Troyan

Total resummation of double- and single- logarithms of x contributing to the spin-dependent structure function g_1 ensures its steep rise at small $x$. In the asymptotic limit x ->0, the resummation leads to the Regge behavior of g_1 and allows to calculate the non-singlet and singlet intercepts of g_1. DGLAP lacks such a resummation but suggests special phe

Efrain J. Ferrer, Vivian de la Incera, Cristina Manuel

We explore the effects of an applied strong external magnetic field in a three flavour massless colour superconductor. The long-range component of the B field that penetrates the superconductor enhances some quark condensates, leading to a different condensation pattern. The external field also reduces the flavour symmetries in the system, and thus it change

Joao Pulido, B. C. Chauhan, R. S. Raghavan

The time dependence that appears to be hinted by the data from the first 13 years of the solar neutrino Gallium experiments is viewed as resulting from a partial conversion of active neutrinos to light sterile ones through the resonant interaction between the magnetic moment of the neutrino and a varying solar field. A summary of the model and its prediction

Alexander Mitov

We present a new method for the calculation of differential distributions directly in Mellin space without recourse to the usual momentum-fraction (or z-) space. The method is completely general and can be applied to any process. It is based on solving the Integration-by-Parts identities when one of the powers of the propagators is an abstract number. The me

M. M. Muhlleitner, P. M. Zerwas

After a brief description of the basic principle of a photon collider, we summarize the physics potential of such a facility at high energies. Unique opportunities are provided in supersymmetric theories for the discovery of heavy scalar and pseudoscalar Higgs bosons as well as selectrons and e-sneutrinos.

M. Tanimoto, T. Yanagida

We present successful lepton mass matrices with an inverted mass hierarchy for neutrinos, which follow from a geometrical structure of a (1+5) dimensional space-time where two extra dimensions are compactified on the T^2/Z_3 orbifold. A 5^* and a right-handed neutrino N in each family are localized on each of the equivalent three fixed points of the orbifold

J. -M. Richard, Fl. Stancu

The dynamics of two heavy quarks inside the same hadron is probed against the double charm baryon results of SELEX. This can be seen as a part of the mechanism to bind tetraquarks with two heavy quarks and two light antiquarks. In the framework of potential models, it is possible to test the role of different effects: relativistic corrections, confinement, h

Anatoli S. Kuznetsov

Quantum-mechanical calculations of transitions dynamics between the left- and right-handed helicity states of the atmospheric muon Dirac neutrino,which has a gravitoelectrical dipole moment (GEDM) interacting with the gravitational field of the Earth have been carried out. It is shown that the asymmetry of the zenith-angle distribution of an atmospheric muon

Wolfram Schroers

This review focuses on the current status of lattice calculations of three observables which are both phenomenologically and experimentally relevant and have been scrutinized recently. These three observables are the nucleon electromagnetic form factors, the momentum fraction, <x>, and the nucleon axial coupling, gA.

Kamal K. Seth

At CLEO, charmonium spectroscopy is pursued both thorugh e+e- annihilation data taken in the Upsilon region and more recently at psi(2S). A nmber of first observations (eta_c&#39;, h_c, pi and K form factors) have been made, and numerous high precision measurements have been made in radiative and hadronic decays of charmonium resonances. A brief report of th

Kamal K. Seth

There has been a renaissance in hadron spectroscopy during the last couple of years. Long lost states have been tracked down. Unexpected states are showing up all over, and numerous measurements with unprecedented precision are being reported. A review is presented.

Etera R. Livine, Daniele Oriti

We study the issue of coupling among 4-simplices in the context of spin foam models obtained from a group field theory formalism. We construct a generalisation of the Barrett-Crane model in which an additional coupling between the normals to tetrahedra, as defined in different 4-simplices that share them, is present. This is realised through an extension of

Peter Diener, Ernst Nils Dorband, Erik Schnetter, Manuel Tiglio

We construct new, efficient, and accurate high-order finite differencing operators which satisfy summation by parts. Since these operators are not uniquely defined, we consider several optimization criteria: minimizing the bandwidth, the truncation error on the boundary points, the spectral radius, or a combination of these. We examine in detail a set of ope

V. Dryuma

Some properties of the Gödel space-time metric and its Riemann extension are studied

Burkhard Zink, Enrique Pazos, Peter Diener, Manuel Tiglio

During the last few years progress has been made on several fronts making it possible to revisit Cauchy-perturbative matching (CPM) in numerical relativity in a more robust and accurate way. This paper is the first in a series where we plan to analyze CPM in the light of these new results. Here we start by testing high-order summation-by-parts operators, pen

M. Blagojevic, B. Cvetkovic

We discuss some new developments in three-dimensional gravity with torsion, based on Riemann-Cartan geometry. Using the canonical approach, we study the structure of asymptotic symmetry, clarify its fundamental role in defining the gravitational conserved charges, and explore the influence of the asymptotic structure on the black hole entropy.

Silvano Garnerone, Annalisa Marzuoli, Mario Rasetti

The spin network simulator model represents a bridge between (generalized) circuit schemes for standard quantum computation and approaches based on notions from Topological Quantum Field Theories (TQFT). More precisely, when working with purely discrete unitary gates, the simulator is naturally modelled as families of quantum automata which in turn represent

M. Consoli, E. Costanzo

We present a fully model-independent analysis of the extensive observations reported by a recent ether-drift experiment in Berlin. No a priori assumption is made on the nature of a hypothetical preferred frame. We find a remarkable consistency with an Earth&#39;s cosmic motion exhibiting an average declination angle |γ|\sim 43^o and with values of the RMS an

Jeremy Carroll, Frank Ruskey, Mark Weston

We establish a new lower bound for the number of sides required for the component curves of simple Venn diagrams made from polygons. Specifically, for any n-Venn diagram of convex k-gons, we prove that k >= (2^n - 2 - n) / (n (n-2)). In the process we prove that Venn diagrams of seven curves, simple or not, cannot be formed from triangles. We then give an ex

A. Benabdallah, G. Radons

We propose a new method for the estimation of parameters of hidden diffusion processes. Based on parametrization of the transition matrix, the Baum-Welch algorithm is improved. The algorithm is compared to the particle filter in application to the noisy periodic systems. It is shown that the modified Baum-Welch algorithm is capable of estimating the system p

J. G. Esteve, F. Falceto

We report an analytic and numerical study of a phase transition in a P problem (the assignment problem) that separates two phases whose representatives are the simple matching problem (an easy P problem) and the traveling salesman problem (a NP-complete problem). Like other phase transitions found in combinatoric problems (K-satisfiability, number partitioni

Sergiu Theodor Chelcea, Alzennyr Da Silva, Yves Lechevallier, Doru Tanasa

This paper presents our preprocessing and clustering analysis on the clickstream dataset proposed for the ECMLPKDD 2005 Discovery Challenge. The main contributions of this article are double. First, after presenting the clickstream dataset, we show how we build a rich data warehouse based an advanced preprocesing. We take into account the intersite aspects i

Erik M. Boczko, Todd R. Young

From a geometric perspective most nonlinear binary classification algorithms, including state of the art versions of Support Vector Machine (SVM) and Radial Basis Function Network (RBFN) classifiers, and are based on the idea of reconstructing indicator functions. We propose instead to use reconstruction of the signed distance function (SDF) as a basis for b

Hossein Kakavand

An upper bound to the information capacity of a wavelength-division multi- plexed optical fiber communication system is derived in a model incorporating the nonlinear propagation effects of cross-phase modulation (XPM). This work is based on the paper by Mitra et al., finding lower bounds to the channel capacity, in which physical models for propagation are

Aaron B. Wagner, Venkat Anantharam

We prove a new outer bound on the rate-distortion region for the multiterminal source-coding problem. This bound subsumes the best outer bound in the literature and improves upon it strictly in some cases. The improved bound enables us to obtain a new, conclusive result for the binary erasure version of the &#34;CEO problem.&#34; The bound recovers many of t

Jianyang Zeng, Wen-Jing Hsu, Jiangdian Wang

In order to investigate the routing aspects of small-world networks, Kleinberg proposes a network model based on a $d$-dimensional lattice with long-range links chosen at random according to the $d$-harmonic distribution. Kleinberg shows that the greedy routing algorithm by using only local information performs in $O(\log^2 n)$ expected number of hops, where

Giorgio Parisi

In this paper I will describe some results that have been recently obtained in the study of random Euclidean matrices, i.e. matrices that are functions of random points in Euclidean space. In the case of {\sl translation invariant} matrices one generically finds a phase transition between a {\sl phonon} phase and a {\sl saddle} phase. If we apply these consi

G. M. Buendia, P. A. Rikvold, M. Kolesik

We present analytical results and kinetic Monte Carlo simulations for the mobility and microscopic structure of solid-on-solid (SOS) interfaces driven far from equilibrium by an external force, such as an applied field or (electro)chemical potential difference. The interfaces evolve under a specific stochastic dynamic with a local energy barrier (an Arrheniu

Joel Chavas, Cyril Furtlehner, Marc Mezard, Riccardo Zecchina

We discuss the implementation of two distributed solvers of the random K-SAT problem, based on some development of the recently introduced survey-propagation (SP) algorithm. The first solver, called the &#34;SP diffusion algorithm&#34;, diffuses as dynamical information the maximum bias over the system, so that variable nodes can decide to freeze in a self-o

Fabrizio Anfuso, Sebastian Eggert

We are considering the interplay between several non-magnetic impurities in the spin-1/2 Heisenberg antiferromagnet in chains, ladders and planes by introducing static vacancies in numerical quantum Monte Carlo simulations. The effective potential between two and more impurities is accurately determined, which gives a direct measure of the quantum correlatio

Roberto B. Diener, Tin-Lun Ho

We show that the newly discovered $^{52}$Cr Bose condensate in zero magnetic field can be a spin nematic of the following kind: A &#34;maximum&#34; polar state, a &#34;co-linear&#34; polar state, or a biaxial nematic ferromagnetic state. We also present the phase diagram with a magnetic field in the interaction subspace containing the Chromium condensate. It

A. Reynoso, Gonzalo Usaj, C. A. Balseiro

We study the spin polarization induced by a current flow in clean two dimensional electron gases with Rashba spin-orbit coupling. This geometric effect originates from special properties of the electron&#39;s scattering at the edges of the sample. In wide samples, the spin polarization has it largest value at low energies (close to the bottom of the band) an

Christian Klinke, Jean-Marc Bonard, Klaus Kern

The evolution of a continuous Fe(NO3)3 catalyst film was observed by in-situ annealing in a Transmission Electron Microscope (TEM). Such catalysts are routinely used in the catalytic growth of carbon nanotubes. The experiments reveal that crystalline particles form from the gel-like film already around 300C. At usual carbon nanotube growth temperatures of 70

Eric D. Chisolm, Giulia De Lorenzi-Venneri, Duane C. Wallace

Within the framework of V-T theory of monatomic liquid dynamics, an exact equation is derived for a general equilibrium time correlation function. The purely vibrational contribution to such a function expresses the system&#39;s motion in one extended harmonic random valley. This contribution is analytically tractable and has no adjustable parameters. While

A. del Campo, J. G. Muga

We study the expansion dynamics of a Tonks-Girardeau gas released from a hard wall trap. Using the Fermi-Bose map, the density profile is found analytically and shown to differ from that one of a classical gas in the microcanonical ensemble even at macroscopic level, for any observation time larger than a critical time. The relevant time scale arises as a co

P. Stansell, K. Stratford, J. -C. Desplat, R. Adhikari

We simulate by lattice Boltzmann the steady shearing of a binary fluid mixture undergoing phase separation with full hydrodynamics in two dimensions. Contrary to some theoretical scenarios, a dynamical steady state is attained with finite domain lengths $L_{x,y}$ in the directions ($x,y)$ of velocity and velocity gradient. Apparent scaling exponents are esti

M. H. Sage, G. R. Blake, G. J. Nieuwenhuys, T. T. M. Palstra

We report evidence for phase coexistence of orbital orderings of different symmetry in SmVO$_3$ by high resolution X-Ray powder diffraction. The phase coexistence is triggered by an antiferromagnetic ordering of the vanadium spins near 130K, below an initial orbital ordering near 200K. The phase coexistence is the result of the intermediate ionic size of sam

Brian M. Andersen, I. V. Bobkova, P. J. Hirschfeld, Yu. S. Barash

We show that the dc Josephson current through superconductor-antiferromagnet-superconductor (S/AF/S) junctions manifests a remarkable atomic scale dependence on the interlayer thickness. At low temperatures the junction is either a 0- or pi-junction depending on whether the AF interlayer consists of an even or odd number of atomic layers. This is associated

Robert A. Nyman, Gael Varoquaux, Brice Villier, Delphine Sacchet

We present a system of room-temperature extended-cavity grating-diode lasers (ECDL) for production of light in the range 760-790nm. The extension of the tuning range towards the blue is permitted by the weak feedback in the cavity: the diodes are anti-reflection coated, and the grating has just 10% reflectance. The light is then amplified using semiconductor

Massmimo Coraddu, Marcello Lissia, Roberto Tonelli

Ensemble of initial conditions for nonlinear maps can be described in terms of entropy. This ensemble entropy shows an asymptotic linear growth with rate K. The rate K matches the logarithm of the corresponding asymptotic sensitivity to initial conditions λ. The statistical formalism and the equality K=λcan be extended to weakly chaotic systems by suitable a

P. Visco, A. Puglisi, A. Barrat, F. van Wijland

We investigate the behavior of energy fluctuations in several models of granular gases maintained in a non-equilibrium steady state. In the case of a gas heated from a boundary, the inhomogeneities of the system play a predominant role. Interpreting the total kinetic energy as a sum of independent but not identically distributed random variables, it is possi

Andras Csordas, Eva Szoke, Peter Szepfalusy

The paper concerns the ground state structure of the partly filled l-shell of a fermionic gas of atoms of spin s in a spherically symmetric spin independent trap potential. At particle numbers N=n(2s+1), n=1,2,...,2l+1 the basic building blocks are clusters consisting of (2s+1) atoms, whose wave functions are completely symmetric and antisymmetric in space a

Huan-Qiang Zhou, Thomas Barthel, John Ove Fjaerestad, Ulrich Schollwoeck

We investigate boundary critical phenomena from a quantum information perspective. Bipartite entanglement in the ground state of one-dimensional quantum systems is quantified using the Renyi entropy S_alpha, which includes the von Neumann entropy (alpha=1) and the single-copy entanglement (alpha=infinity) as special cases. We identify the contribution from t

O. Waldmann, C. Dobe, S. T. Ochsenbein, H. U. Güdel

The magnetic torque of the antiferromagnetic molecular wheel CsFe8 was studied down to 50 mK and in fields up to 28 T. Below ca. 0.5 K phase transitions were observed at the field-induced level-crossings (LCs). Intermolecular magnetic interactions are very weak excluding an explanation in terms of field-induced magnetic ordering. A magneto-elastic coupling w

Michael Potthoff

The systematics of different approximations within the self-energy-functional theory (SFT) is discussed for fermionic lattice models with local interactions. In the context of the SFT, an approximation is essentially given by specifying a reference system with the same interaction but a modified non-interacting part of the Hamiltonian which leads to a partia

A. Pelizzola

I study the properties of the equilibrium probability distribution of a protein folding model originally introduced by Wako and Saito, and later reconsidered by Munoz and Eaton. The model is a one-dimensional model with binary variables and many-body, long-range interactions, which has been solved exactly through a mapping to a two-dimensional model of binar

Mathias Michel, Jochen Gemmer, Guenter Mahler

We analyze closed one-dimensional chains of weakly coupled many level systems, by means of the so-called Hilbert space average method (HAM). Subject to some concrete conditions on the Hamiltonian of the system, our theory predicts energy diffusion with respect to a coarse-grained description for almost all initial states. Close to the respective equilibrium

M. T. Batchelor, X. W. Guan, N. Oelkers

We investigate thermal and magnetic properties of the double spin chain compound KCuCl_3 via an exactly solved ladder model with strong rung interaction. Results from the analysis of the thermodynamic Bethe Ansatz equations suggests the critical field values H_{c1}=22.74T and H_{c2}=51.34T, in good agreement with the experimental observations. The temperatur

Jian Li, Xi Dai, Shun-Qing Shen, Fu-Chun Zhang

We examine electric response of a linearly polarized light normally shed on a cross-shaped quasi 2-dimensional InGaAs/InAlAs system with structure inversion asymmetry. The photo-excited conduction electrons carry a pure spin current with in-plane spin polarization due to the Rashba spin-orbit interaction. We use Landauer-Büttiker formalism to show that this

Siyuranga O. Koswatta, Sayed Hasan, Mark S. Lundstrom, M. P. Anantram

We investigate the role of electron-phonon scattering and gate bias in degrading the drive current of nanotube MOSFETs. Our central results are: (i) Optical phonon scattering significantly decreases the drive current only when gate voltage is higher than a well-defined threshold. It means that elastic scattering mechanisms are most detrimental to nanotube MO

E. Hoskinson, Y. Sato, I. Hahn, R. E. Packard

The rich dynamics of flow between two weakly coupled macroscopic quantum reservoirs has led to a range of important technologies. Practical development has so far been limited to superconducting systems, for which the basic building block is the so-called superconducting Josephson weak link. With the recent observation of quantum oscillations in superfluid 4

R. Lopez-Sandoval, Martin E. Garcia

The pairwise quantum entanglement of sites in disordered electronic one-dimensional systems (rings) is studied. We focus on the effect of diagonal and off diagonal disorder on the concurrence $C_{ij}$ between electrons on neighbor and non neighbor sites $i,j$ as a function of band filling. In the case of diagonal disorder, increasing the degree of disorder l

Gregory A. Fiete, Karyn Le Hur, Leon Balents

In a one dimensional electron gas at low enough density, the magnetic (spin) exchange energy $J$ between neighboring electrons is exponentially suppressed relative to the characteristic charge energy, the Fermi energy $E_F$. At non-zero temperature $T$, the energy hierarchy $J \ll T \ll E_F$ can be reached, and we refer to this as the spin incoherent Lutinge

A. S. Tychkov, T. Jeltes, J. M. McNamara, P. J. J. Tol

We have produced a Bose-Einstein condensate of metastable helium (4He*) containing over 1.5x10^7 atoms, which is a factor of 25 higher than previously achieved. The improved starting conditions for evaporative cooling are obtained by applying one-dimensional Doppler cooling inside a magnetic trap. The same technique is successfully used to cool the spin-pola

D. Schmeltzer

A theory based on the Aharonov -Bohm effect in the momentum space for the Spin-Hall conductivity without a magnetic field is presented. The two dimensional Rashba Hamiltonian is diagonalized in the momentum spinor basis. This spinor is singular at K=0. The representation of the cartesian coordinates in the spinor momentum basis obey non-commutative rules. Th

Nigel Goldenfeld, Roger Haydock

The Anderson model for independent electrons in a disordered potential is transformed analytically and exactly to a basis of random extended states leading to a variant of augmented space. In addition to the widely-accepted phase diagrams in all physical dimensions, a plethora of additional, weaker Anderson transitions are found, characterized by the long-di

Magnus Paulsson, Thomas Frederiksen, Mads Brandbyge

Computationally inexpensive approximations describing electron-phonon scattering in molecular-scale conductors are derived from the non-equilibrium Green&#39;s function method. The accuracy is demonstrated with a first principles calculation on an atomic gold wire. Quantitative agreement between the full non-equilibrium Green&#39;s function calculation and t

Gonzalo Usaj, Harold U. Baranger

We calculate the mesoscopic fluctuations of the magnetic anisotropy of ferromagnetic nanoparticles. A microscopic spin-orbit Hamiltonian considered as a perturbation of the much stronger exchange interaction first yields an explicit expression for the anisotropy tensor. Then, assuming a simple random matrix model for the spin-orbit coupling allows us to desc

Gonzalo Usaj, C. A. Balseiro

We show that in a two dimensional electron gas (2DEG) the interplay between the Rashba spin-orbit coupling and a potential barrier (eg., the sample edge) generates interesting spin effects. In the presence of an external charge current, a spin accumulation is built up near the barrier while in equilibrium there is an inhomogeneous spin current which is local

Ezequiel Treister, C. Megan Urry, Paulina Lira

The Great Observatories Origins Deep Survey (GOODS) combines deep HST and Spitzer imaging with the deepest Chandra/XMM observations to probe obscured AGN at higher redshifts than previous multiwavelength surveys. We present a self-consistent implementation of the AGN unification paradigm, which postulates obscured AGN wherever there are unobscured AGN, to su

Ioannis Contopoulos, Anatoly Spitkovsky

We address the issue of electromagnetic pulsar spindown by combining our experience from the two limiting idealized cases which have been studied in great extent in the past: that of an aligned rotator where ideal MHD conditions apply, and that of a misaligned rotator in vacuum. We construct a spindown formula that takes into account the misalignment of the

Thomas M. Brown, Ed Smith, Puragra Guhathakurta, R. Michael Rich

We present a color-magnitude diagram (CMD) for a field in the giant tidal stream of the Andromeda galaxy (M31). These observations, taken with the Advanced Camera for Surveys on the Hubble Space Telescope, are 50% complete at V~30 mag, reaching 1 mag below the oldest main-sequence turnoff. Striking similarities between the stream and a previous spheroid CMD

J. S. Bloom, Dan L. Starr, Cullen H. Blake, M. F. Skrutskie

The Peters Automated Infrared Imaging Telescope (PAIRITEL) is the first meter-class telescope operating as a fully robotic IR imaging system. Dedicated in October 2004, PAIRITEL began regular observations in mid-December 2004 as part of a 1.5 year commissioning period. The system was designed to respond without human intervention to new gamma-ray burst trans

D. J. Lennon, C. J. Evans, C. Trundle

In this paper we review the observational data for OB stars in the SMC concentrating on those aspects of their spectra which provide information on processes which may strongly influence their evolution, namely mass-loss, rotational mixing and mass-transfer. We illustrate the very weak winds now thought to pertain to late O-dwarfs in the SMC, using HST/STIS

D. C. Homan, M. L. Lister

We report first-epoch circular polarization results for 133 active galactic nuclei in the MOJAVE program to monitor the structure and polarization of a flux limited sample of extra-galactic radio jets with the VLBA at 15 GHz. We found strong circular polarization ($\geq 0.3$%) in approximately 15% of our sample. The circular polarization was usually associat

P. North, F. Betrix, C. Besson

Preliminary abundances of lithium and a few other elements have been obtained for 31 field Am stars with good Hipparcos parallaxes, as well as for 36 normal A and F stars. Radial and projected rotational velocities were determined as well. We examine the Li abundance as a function of the stellar parameters: for normal stars, it is clearly bimodal for Teff <

P. North

35 Eclipsing binaries presenting unambiguous total eclipses were selected from a subsample of the list of Wyrzykowski et al. (2003). The photometric elements are given for the I curve in DiA photometry, as well as approximate Teff and masses of the components. The interest of these systems is stressed in view of future spectroscopic observations.

R. Lahmann, G. Anton, K. Graf, J. Hoessl

The ANTARES group at the University of Erlangen is working towards the integration of a set of acoustic sensors into the ANTARES Neutrino Telescope. With this setup, tests of acoustic particle detection methods and background studies shall be performed. The ANTARES Neutrino Telescope, which is currently being constructed in the Mediterranean Sea, will be equ

Eugenio Carretta, Angela Bragaglia, Raffaele Gratton, Francesco Leone

We derived atmospheric parameters and elemental abundances of Fe, O and Na for about 120 red giant stars in the Galactic globular cluster NGC 2808. Our results are based on the analysis of medium-high resolution (R=22000-24000) GIRAFFE spectra acquired with the FLAMES spectrograph at VLT-UT2 as a part of a project aimed at studying the Na-O anticorrelation a

A. Bragaglia, M. Tosi, E. Carretta, R. G. Gratton

We present CCD UBVI photometry and high-resolution spectroscopy of the intermediate age open cluster NGC 3960. The colour - magnitude diagrams (CMDs) derived from the photometric data and interpreted with the synthetic CMD method allow us to estimate the cluster parameters. We derive: age = 0.9 or 0.6 Gyr (depending on whether or not overshooting from convec

O. Nakamura, A. Aragon-Salamanca, B. Milvang-Jensen, N. Arimoto

We have carried out spectroscopic observations in 4 cluster fields using Subaru&#39;s FOCAS multi-slit spectrograph and obtained spectra for 103 bright disk field and cluster galaxies at $0.06 \le z \le 1.20$. Seventy-seven of these show emission lines, and 33 provide reasonably-secure determinations of the galaxies&#39; rotation velocity. The rotation veloc

Sergei Nayakshin, Walter Dehnen, Jorge Cuadra, Reinhard Genzel

It is believed that young massive stars orbiting Sgr A* in two stellar discs on scales of 0.1-0.2 parsecs were formed either farther out in the Galaxy and then quickly migrated inward, or in situ in a massive self-gravitating disc. Comparing N-body evolution of stellar orbits with observational constraints, we set upper limits on the masses of the two stella

L. Fuhrmann, A. Cucchiara, N. Marchili, G. Tosti

The flat-spectrum radio quasar 3C 454.3 is well known to be a highly active and variable source with outbursts occurring across the whole electromagnetic spectrum over the last decades. In spring 2005, 3C 454.3 has been reported to exhibit a strong optical outburst which subsequently triggered multi-frequency observations of the source covering the radio up