June 2004 arXiv papers — page 7

R. Dennis Cook

We develop tests of the hypothesis of no effect for selected predictors in regression, without assuming a model for the conditional distribution of the response given the predictors. Predictor effects need not be limited to the mean function and smoothing is not required. The general approach is based on sufficient dimension reduction, the idea being to repl

Christopher Genovese, Larry Wasserman

This paper extends the theory of false discovery rates (FDR) pioneered by Benjamini and Hochberg [J. Roy. Statist. Soc. Ser. B 57 (1995) 289-300]. We develop a framework in which the False Discovery Proportion (FDP)--the number of false rejections divided by the number of rejections--is treated as a stochastic process. After obtaining the limiting distributi

Estate V. Khmaladze, Hira L. Koul

This paper discusses two goodness-of-fit testing problems. The first problem pertains to fitting an error distribution to an assumed nonlinear parametric regression model, while the second pertains to fitting a parametric regression model when the error distribution is unknown. For the first problem the paper contains tests based on a certain martingale type

Roumen Anguelov, Elemer E Rosinger

It was shown in 1994, in Oberguggenberger & Rosinger, that very large classes of nonlinear PDEs have solutions which can be assimilated with usual measurable functions on the Euclidean domains of definition of the respective equations. In this paper the regularity of these solutions is significantly improved by showing that they can in fact be assimilated wi

Dan Romik

We construct a piecewise onto 3-to-1 dynamical system on the positive quadrant of the unit circle, such that for rational points (which correspond to normalized Primitive Pythagorean Triples), the associated ternary expansion is finite, and is equal to the address of the PPT on Barning's ternary tree of PPTs, while irrational points have infinite expansi

Erica Walker, Raza M. Syed, Achille Corsetti

We will first solve the following problem analytically: given a piece of wire of specified length, we will find where the wire should be cut and bent to form two regular polygons not necessarily having the same number of sides, so that the combined area of the polygons thus formed is maximized, minimized, greater than, and less than a specified area. We will

Thierry Monteil

A planar polygonal billiard $¶$ is said to have the finite blocking property if for every pair $(O,A)$ of points in $¶$ there exists a finite number of ``blocking'' points $B_1, ..., B_n$ such that every billiard trajectory from $O$ to $A$ meets one of the $B_i$'s. Generalizing our construction of a counter-example to a theorem of Hiemer and Snur

Philip Foth, Yi Hu

We show that a weight variety, which is a quotient of a flag variety by the maximal torus, admits a flat degeneration to a toric variety. In particular, we show that the moduli spaces of spatial polygons degenerate to polarized toric varieties with the moment polytopes defined by the lengths of their diagonals. We extend these results to more general Flaschk

S. A. Belbas

We define two models of hysteresis that generalize the Preisach model. The first model is deterministic, the second model is stochastic and it utilizes disconinuous transition probabilities that satisfy impulsive differential equations. For the first model we prove, among other things, a local version of the "wiping out" property; for the stochastic

Domenico Fiorenza

The aim of these notes is to introduce the quantum master equation $\{S,S\}-2i\hbarΔS=0$, and to show its relations to the theory of Lie algebras representations and to perturbative expansions of Gaussian integrals. The relations of the classical master equation $\{S,S\}=0$ with the BRST formalisms are also described. Being an introduction, only finite-dimen

Kenichiro Kimura

We use the elements in $K$-cohomology groups which are constructed by Flach and Mildenhall to obtain a finiteness result for the torsion part of the Chow group of a self-product of a modular curve.

Pramathanath Sastry

We relate the variance theory for Cousin complexes -^# developed by Lipman, Nayak and the author to Grothendieck duality for Cousin complexes. Specifically for a Cousin complex F on (Y, Δ)--with Δa codimension function on a formal scheme Y (noetherian, universally catenary)--and a pseudo-finite type map f:(X,Δ') --> (Y,Δ) of such pairs of schemes with co

Harish Seshadri

We prove that any compact four-manifold admits a Riemannian metric with negative isotropic curvature in the sense of Micallef and Moore.

Harald Weber, Matthias Kuenzer

Let n >= 1 and let p be a prime. Let t = 1 - zeta_{p^n}. Expand an integer j in [0,p^n-1], coprime to p, p-adically as j = sum_{s >= 0} a_s p^s. Denote the tensor product over Z_(p) by o . Then the #([0,j] - (p))th Z_(p)[t]-linear elementary divisor of the cyclotomic Dedekind embedding Z_(p)[t] o Z_(p)[t] --> prod_{i in (Z/p^n)^*} Z_(p)[t] has valuation -1 +

Yoji Michishita

We study gauge invariant quantities in the open superstring field theory proposed by Berkovits, extending the precedent discussion in bosonic string field theory. Our gauge invariants are ``on-shell''. As its applications, we define quantities which are expected to be related to the U(1) field strength -- a RR coupling and a ``component'' of

James Gray

We present an explicit example of a gauge symmetry breaking phase transition in heterotic models, the dynamics of which are not thermal and can be described in a well controlled manner throughout. The phase transition is driven by the evolution of bundle moduli - moduli associated with gauge field vacuum expectation values in the hidden dimensions. We presen

Danilo E. Diaz, Harald Dorn

Green functions for the scalar, spinor and vector fields in a plane wave geometry arising as a Penrose limit of $AdS\times S$ are obtained. The Schwinger-DeWitt technique directly gives the results in the plane wave background, which turns out to be WKB-exact. Therefore the structural similarity with flat space results is unveiled. In addition, based on the

Paul Mansfield

Motivated by a heuristic model of the Yang-Mills vacuum that accurately describes the string-tension in three dimensions we develop a systematic method for solving the functional Schroedinger equation in a derivative expansion. This is applied to the Landau-Ginzburg theory that describes surface critical scaling in the Ising model. A Renormalisation Group an

B. Geyer, P. M. Lavrov

Basic properties of even (odd) supermanifolds endowed with a connection respecting a given symplectic structure are studied. Such supermanifolds can be considered as generalization of Fedosov manifolds to the supersymmetric case.

Yu-ichi Takamizu, Kei-ichi Maeda

We study a particle production at the collision of two domain walls in 5-dimensional Minkowski spacetime. This may provide the reheating mechanism of an ekpyrotic (or cyclic) brane universe, in which two BPS branes collide and evolve into a hot big bang universe. We evaluate a production rate of particles confined to the domain wall. The energy density of cr

M. Asorey, D. Garcia-Alvarez, J. L. Lopez

Quantum fluctuations generate in three-dimensional gauge theories not only radiative corrections to the Chern-Simons coupling but also non-analytic terms in the effective action. We review the role of those terms in gauge theories with massless fermions and Chern-Simons theories. The explicit form of non-analytic terms turns out to be dependent on the regula

Hiroshige Kajiura

Homological mirror symmetry is a conjecture that a category constructed in the A-model and a category constructed in the B-model are equivalent in some sense. We construct a cyclic differential graded (DG) category of holomorphic vector bundles on noncommutative two-tori as a category in the B-model side. We define the corresponding Fukaya's category in

D. V. Bugg

The threshold pbar-p peak in BES data for J/Ψto gamma-pbar-p may be fitted as a cusp. It arises from the well known threshold peak in pbar-p elastic scattering due to annihilation. Several similar examples are discussed. The PS185 data for pbar-p to Lambdabar-Lambda require an almost identical cusp at the Lambdabar-Lambda threshold. There is also a cusp at t

D. V. Bugg

A partial wave analysis of PS185 data for pbar-p to Lambda-bar Lambda is presented. A 3S1 cusp is identified in the inverse process Lambda-bar Lambda to pbar-p at threshold using detailed balance. Partial wave amplitudes for pbar-p 3P0, 3F3, 3D3 and 3G3 exhibit a behaviour very similar to resonances observed in Crystal Barrel data. With this identification,

Francois Arleo

We discuss the energy loss effects on single prompt photon production in heavy-ion collisions at RHIC and LHC energy. The production of correlated photon pairs at the LHC is also considered.

M. Schlegel, A. Metz

Lorentz invariance relations connecting twist-3 parton distributions with transverse momentum dependent twist-2 distributions have been proposed previously. These relations can be extracted from a covariant decomposition of the quark-quark correlator. It is argued, however, that the derivation of the Lorentz invariance relations fails if the path-ordered exp

T. Hahn

FormCalc is a Mathematica package for the automatic computation of tree-level and one-loop Feynman amplitudes. It accepts diagrams generated by FeynArts, simplifies them, and generates a complete Fortran code for their numerical evaluation. Version 4 includes new features which enhance performance, convenience of use, and modularity/code reusability.

N. Cosme

We discuss leptogenesis in its natural context, i.e. gauge unification, by including in the analysis the effects of the gauge sector associated to the Majorana neutrinos. It results in stricter bounds on the minimal Majorana mass, depending on the gauge bosons mass, but also prevents to deduce any lower limit on the Yukawa couplings since thermal and re-heat

A. Bartl, H. Fraas, O. Kittel, W. Majerotto

We study CP sensitive observables in neutralino production e+e- -> neutralino_i neutralino_j and the subsequent two-body decays of the neutralino neutralino_i -> neutralino_n Z and of the Z boson Z -> l \bar l (q \bar q). We identify the CP odd elements of the Z boson density matrix and propose CP sensitive triple-product asymmetries. We calculate these obse

John M. LoSecco

We note that detector depth can influence the decay path length available for the primary and secondary particles that are the source of atmospheric neutrinos. As a consequence there is a location dependent modulation to the neutrino flux, which could be as large as 5-10% in some directions.

D. A. Shaddock, B. Ware, R. E. Spero, M. Vallisneri

High-precision interpolation of LISA phase measurements allows signal reconstruction and formulation of Time-Delay Interferometry (TDI) combinations to be conducted in post-processing. The reconstruction is based on phase measurements made at approximately 10 Hz, at regular intervals independent of the TDI delay times. Interpolation introduces an error less

Norman Cruz, Marco Olivares, Jose Villanueva

In this work we study static perfect fluid stars in 2+1 dimensions with an exterior BTZ spacetime. We found the general expression for the metric coefficients as a function of the density and pressure of the fluid. We found the conditions to have regularity at the origin throughout the analysis of a set of linearly independent invariants. We also obtain an e

J. Brian Pitts, W. C. Schieve

Recently the neglected issue of the causal structure in the flat spacetime approach to Einstein's theory of gravity has been substantially resolved. Consistency requires that the flat metric's null cone be respected by the null cone of the effective curved metric. While consistency is not automatic, thoughtful use of the naive gauge freedom resolves

J. Brian Pitts, W. C. Schieve

If Einstein's equations are to describe a field theory of gravity in Minkowski spacetime, then causality requires that the effective curved metric must respect the flat background metric's null cone. The kinematical problem is solved using a generalized eigenvector formalism based on the Segré classification of symmetric rank 2 tensors with respect t

J. -K. Kao, H. T. Cho

In the Schwarzchild black hole spacetime, we show that chaotic motion can be triggered by the spin of a particle. Taking the spin of the particle as a perturbation and using the Melnikov method, we find that the perturbed stable and unstable orbits are entangled with each other and that illustrates the onset of chaotic behavior in the motion of the particle.

Marcus H. Mendenhall

This paper presents an algorithm for computing Sine-Cosine pairs to modest accuracy, but in a manner which contains no conditional tests or branching, making it highly amenable to vectorization. An exemplary implementation for PowerPC AltiVec processors is included, but the algorithm should be easily portable to other achitectures, such as Intel SSE.

H. L. Janwa A. K. Lal

We give a new lower bound on the expansion coefficient of an edge-vertex graph of a $d$-regular graph. As a consequence, we obtain an improvement on the lower bound on relative minimum distance of the expander codes constructed by Sipser and Spielman. We also derive some improved results on the vertex expansion of graphs that help us in improving the paramet

Michael Nüsken, Martin Ziegler

We generalize univariate multipoint evaluation of polynomials of degree n at sublinear amortized cost per point. More precisely, it is shown how to evaluate a bivariate polynomial p of maximum degree less than n, specified by its n^2 coefficients, simultaneously at n^2 given points using a total of O(n^{2.667}) arithmetic operations. In terms of the input si

S. Das Sarma, M. P. Lilly, E. H. Hwang, L. N. Pfeiffer

By carefully analyzing the low temperature density dependence of 2D conductivity in undoped high mobility n-GaAs heterostructures, we conclude that the 2D metal-insulator transition in this system is a density inhomogeneity driven percolation transition due to the breakdown of screening in the random charged impurity disorder background. In particular, our m

M. Z. Hasan, Y. Li, D. Qian, Y. -D. Chuang

Electron behavior in doped Mott systems continues to be a major unsolved problem in quantum many-electron physics. A central issue in understanding the universal Mott behavior in a variety of complex systems is to understand the nature of their electron-hole pair excitation modes. Using high resolution resonant inelastic x-ray scattering (RIXS) we resolve th

Ran Budnik, Assa Auerbach

The spin half Heisenberg antiferromagnet on the Kagome lattice, is mapped by Contractor Renormalization to a Spin-Pseudospin Hamiltonian on the triangular superlattice. Variationally, we find a ground state with columnar dimer order. Dimer orientation fluctuations are described by an effective O(2) model at energies above an exponentially suppressed clock ma

A. Crisanti, L. Leuzzi, T. Rizzo

The Complexity of the Thouless-Anderson-Palmer (TAP) solutions of the Ising $p$-spin is investigated in the temperature regime where the equilibrium phase is one step Replica Symmetry Breaking. Two solutions of the resulting saddle point equations are found. One is supersymmetric (SUSY) and includes the equilibrium value of the free energy while the other is

Cecilia Pennetta

A short review is presented of a recently developed computational approach which allows the study of the resistance noise over the full range of bias values, from the linear regime up to electrical breakdown. Resistance noise is described in terms of two competing processes in a random resistor network. The two processes are thermally activated and driven by

Marcelo J. Rozenberg, Isao H. Inoue, Maria Jose Sanchez

We investigate hysteresis effects in a model for non-volatile memory devices. Two mechanisms are found to produce hysteresis effects qualitatively similar to those often experimentally observed in heterostructures of transition metal oxides. One of them is a novel switching effect based on a metal-insulator transition due to strong electron correlations at t

D. P. Young, M. Moldovan, X. S. Wu, J. Y. Chan

We report ac susceptibility measurements of polycrystalline CePt_3Si down to 60 mK and in applied fields up to 9 T. In zero field, a full Meissner state emerges at temperatures T/Tc < 0.3, where Tc=0.65 K is the onset transition temperature. Though transport measurements show a relatively high upper critical field Bc2 ~ 4-5 T, the low temperature susceptibil

R. V. R. Pandya

We discuss a newly proposed model by Barrat et al. (Phys. Rev. Lett. 92, 228701, 2004) for weighted evolving networks and suggest yet another model which can be viewed in the framework of worldwide airport network as &#34;busy airports get busier&#34;.

R. Taranko, T. Kwapinski, E. Taranko

We consider the time-dependent electron transport through a quantum dot connected to multiple leads in the presence of the additional over-dot (bridge) tunnelling channels by using the evolution operator technique. Each terminal and quantum dot are disturbed by an external oscillating field resulting in a time-dependence of the corresponding energy levels. T

San-Huang Ke, Harold U. Baranger, Weitao Yang

We analyze the effect of a gate on the conductance of molecules by separately evaluating the gate-induced polarization and the potential shift of the molecule relative to the leads. The calculations use ab initio density functional theory combined with a Green function method for electron transport. For a general view, we study several systems: (1) atomic ch

Erio Tosatti, Michele Fabrizio, Jaroslav Tobik, Giuseppe E. Santoro

We propose that electron doped nontransition metal-phthalocyanines (MPc) like ZnPc and MgPc, similar to those very recently reported, should constitute novel strongly correlated metals. Due to orbital degeneracy, Jahn-Teller coupling and Hund&#39;s rule exchange, and with a large on-site Coulomb repulsion, these molecular conductors should display, particula

M. R. Graeber, T. Nussbaumer, W. Belzig, T. Kontos

We report on electrical transport measurements through a carbon nanotube quantum dot coupled to a normal and a superconducting lead. The ratio of Kondo temperature and superconducting gap $T_{K}/Δ$ is identified to govern the transport properties of the system. In the case of $T_{K}<Δ$ the conductance resonance splits into two resonances at $\pm Δ$. For the

Cyrille Barreteau, Faical Raouafi, Marie-Catherine Desjonqueres, Daniel Spanjaard

The energetics of transition and noble metal (Rh, Pd, Cu) vicinal surfaces, i.e., surface energy, step energy, kink energy and electronic interactions between steps, is studied at 0K from electronic structure calculations in the tight-binding approximation using a {\it s, p} and {\it d} valence orbital basis set. Then, the surface phonon spectra of copper ar

M. Daghofer, W. Koller, W. von der Linden, H. G. Evertz

We investigate the 2D ferromagnetic Kondo lattice model for manganites with classical corespins at Hund&#39;s rule coupling J_H=6, with antiferromagnetic superexchange 0.03 < J&#39; < 0.05. We employ canonical and grand canonical unbiased Monte Carlo simulations and find paramagnetism, weak ferromagnetism and the Flux phase, depending on doping and on J&#39;

G. Górski, J. Mizia

We analyze the influence of different on-site and inter-site interactions on the Curie temperature of transition metal magnetic elements. The numerical calculations show the well known result that the on-site Coulomb repulsion helps ferromagnetism mainly at half-filling of the band, where the 3d elements are antiferromagnetic (Cr, Mn). The inter-site interac

Hui Pan, Tsung-Han Lin, Dapeng Yu

The influence of the impurity on the resonant Andreev reflection through a normal-metal/carbon-nanotube/superconductor system is studied theoretically. It is found that the resonant Andreev reflection depends on the strength of the impurity and the length of the armchair nanotube. The impurity which breaks the electron-hole symmetry of the nanotubes greatly

A. D. Drozdov

An explicit expression is derived for the distribution function of end-to-end vectors and for the mean square end-to-end distance of a flexible chain with excluded-volume interactions. The Hamiltonian for a flexible chain with weak intra-chain interactions is determined by two small parameters: the ratio $ε$ of the energy of interaction between segments (wit

Lukasz Zawitkowski, Miroslaw Brewczyk, Mariusz Gajda, Kazimierz Rzazewski

Classical fields approximation to cold weakly interacting bosons allows for a unified treatment of condensed and uncondensed parts of the system. Until now, however, the quantitative predictions were limited by a dependence of the results on a grid chosen for numerical implementation of the method. In this paper we propose replacing this unphysical ambiguity

Thomas Gasenzer

A dynamical many body theory of single color photoassociation in a Bose-Einstein condensate is presented. The theory describes the time evolution of a condensed atomic ensemble under the influence of an arbitrarily varying near resonant laser pulse, which strongly modifies the binary scattering properties. In particular, when considering situations with rapi

B. Babic, J. Furer, M. Iqbal, C. Schonenberger

Using carbon nanotubes (CNTs) produced by chemical vapor deposition, we have explored different strategies for the preparation of carbon nanotube devices suited for electrical and mechanical measurements. Though the target device is a single small diameter CNT, there is compelling evidence for bundling, both for CNTs grown over structured slits and on rigid

F. Celestini

We perform molecular dynamic simulations of liquid nanoparticles deposited on a disordered substrate. The motion of the nanoparticle is characterised by a &#39;stick and roll&#39; diffusive process. Long simulation times ($\simeq μs$), analysis of mean square displacements and stacking time distribution functions demonstrate that the nanoparticle undergoes a

L. X. You, P. H. Wu, J. Chen, W. W. Xu

We have observed back-bending structures at high bias current in the current-voltage curves of intrinsic Josephson junctions. These structures may be caused by nonequilibrium quasiparticle injection and/or Joule heating. The energy gap suppression varies considerably with temperature. Different levels of the suppression are observed when the same level of cu

Li-Xing You, Pei-Heng Wu, Wei-Wei Xu, Zheng-Ming Ji

In fabricating $\mathrm{Bi_2Sr_2CaCu_2O_{8+δ}}$ intrinsic Josephson junctions in 4-terminal mesa structures, we modify the conventional fabrication process by markedly reducing the etching rates of argon ion milling. As a result, the junction number in a stack can be controlled quite satisfactorily as long as we carefully adjust those factors such as the etc

H. Nakano, H. Tanaka, S. Saito, K. Semba

The readout process of a superconducting flux-qubit is theoretically analyzed in terms of the quantum dynamics of a qubit-SQUID coupled system during measurement. The quantity directly observed by the measurement is the switching current (Isw) of the dc-SQUID placed around the qubit ring. In order to clarify the relation between the Isw and the qubit state,

Arun Paramekanti, Ashvin Vishwanath

Luttinger&#39;s theorem for Fermi liquids equates the volume enclosed by the Fermi surface in momentum space to the electron filling, independent of the strength and nature of interactions. Motivated by recent momentum balance arguments that establish this result in a non-perturbative fashion [M. Oshikawa, Phys. Rev. Lett. {\bf 84}, 3370 (2000)], we present

V. V. Ponomarenko, D. V. Averin

We have developed a theory of quasiparticle backscattering in a system of point contacts formed between single-mode edges of several Fractional Quantum Hall Liquids (FQHLs) with in general different filling factors $ν_j$ and one common single-mode edge $ν_0$ of another FQHL. In the strong-tunneling limit, the model of quasiparticle backscattering is obtained

I. S. Beloborodov, K. B. Efetov, A. V. Lopatin, V. M. Vinokur

We investigate transport in a granular metallic system at large tunneling conductance between the grains. We show that at low temperatures, $T\leq g_Tδ$, where $δ$ is the single mean energy level spacing in a grain, the coherent electron motion at large distances dominates the physics, contrary to the high temperature ($T > g_T δ$) behavior where conductivit

Susanne Moelbert, B. Normand, Paolo De Los Rios

Kosmotropic cosolvents added to an aqueous solution promote the aggregation of hydrophobic solute particles, while chaotropic cosolvents act to destabilise such aggregates. We discuss the mechanism for these phenomena within an adapted version of the two-state Muller-Lee-Graziano model for water, which provides a complete description of the ternary water/cos

Jungyeon Cho, A. Lazarian

We present numerical studies of 3-dimensional electron magnetohydrodynamic (EMHD) turbulence. We investigate cascade timescale and anisotropy of freely decaying strong EMHD turbulence with zero electron skin depth. Cascade time scales with $k^{-4/3}$. Our numerical results clearly show scale-dependent anisotropy. We discuss that the observed anisotropy is co

Mallory S. E. Roberts, Maxim Lyutikov, Bryan M. Gaensler, Crystal Brogan

The traditional view of radio pulsar wind nebulae (PWN), encouraged by the Crab nebula&#39;s X-ray and radio morphologies, is that they are a result of the integrated history of their pulsars&#39; wind. The radio emission should therefore be largely unaffected by recent pulsar activity, and hence minimally correlated with structures in the X-ray nebulae. Obs

E. Vanzella, S. Cristiani, M. Dickinson, H. Kuntschner

We present the first results of the ESO/GOODS program of spectroscopy of faint galaxies in the Chandra Deep Field South (CDF-S). 399 spectra of 303 unique targets have been obtained in service mode with the FORS2 spectrograph at the ESO/VLT, providing 234 redshift determinations (the median of the redshift distribution is at 1.04). The typical redshift uncer

Fan Fang, David L. Shupe, Gillian Wilson, Mark Lacy

We present the first results of the angular auto-correlation function of the galaxies detected by the Infrared Array Camera (IRAC) instrument in the First Look Survey (FLS) of the Spitzer Space Telescope. We detect significant signals of galaxy clustering within the survey area. The angular auto-correlation function of the galaxies detected in each of the fo

K. S. Noll, D. C. Stephens, W. M. Grundy, I. Griffin

We have observed 1999 RZ253 with the Hubble Space Telescope at seven separate epochs and have fit an orbit to the observed relative positions of this binary. Two orbital solutions have been identified that differ primarily in the inclination of the orbit plane. The best fit corresponds to an orbital period, P=46.263 +0.006/-0.074 days, semimajor axis a=4,660

W. M. Liu, P. M. Hinz, W. F. Hoffmann, G. Brusa

We present the results of mid-infrared nulling interferometric observations of the main-sequence star alpha Lyr (Vega) using the 6.5 m MMT with its adaptive secondary mirror. From the observations at 10.6 microns, we find that there is no resolved emission from the circumstellar environment (at separations greater than 0.8 AU) above 2.1% (3 sigma limit) of t

M. Bursa, M. A. Abramowicz, V. Karas, W. Kluzniak

We show that a luminous torus in the Schwarzschild metric oscillating along its own axis gives rise to a periodically varying flux of radiation, even though the source of radiation is steady and perfectly axisymmetric. This implies that the simplest oscillation mode in an accretion flow, axisymmetric up-and-down motion at the meridional epicyclic frequency,

A. Ecuvillon, G. Israelian, N. C. Santos, M. Mayor

We present a detailed and uniform study of C, S, Zn and Cu abundances in a large set of planet host stars, as well as in a homogeneous comparison sample of solar-type dwarfs with no known planetary-mass companions. Carbon abundances were derived by {EW} measurement of two C I optical lines, while spectral syntheses were performed for S, Zn and Cu. We investi

Xiaolei Zhang

The secular evolution process, which slowly transforms the morphology of a galaxy over its lifetime, could naturally account for observed properties of the great majority of physical galaxies if both stellar and gaseous accretion processes are taken into account. As an emerging paradigm for galaxy evolution, its dynamical foundation had been established in t

E. Moraux, P. Kroupa, J. Bouvier

Two stellar-dynamical models of binary-rich embedded proto-Orion-Nebula-type clusters that evolve to Pleiades-like clusters are studied with an emphasis on comparing the stellar mass function with observational constraints. By the age of the Pleiades (about 100 Myr) both models show a similar degree of mass segregation which also agrees with observational co

Filippo Frontera

The discovery by the BeppoSAX satellite of X-ray afterglow emission from the gamma-ray burst which occurred on 28 February 1997 produced a revolution in our knowledge of the gamma-ray burst phenomenon. Along with the discovery of X-ray afterglows, the optical afterglows of gamma-ray bursts were discovered and the distance issue was settled, at least for long

Daniel Pfenniger, Yves Revaz

Bars and spiral arms have played an important role as constraints on the dynamics and on the distribution of dark matter in the optical parts of disk galaxies. Dynamics linked to the dissipative nature of gas, and its transformation into stars provide clues that spiral galaxies are driven by dissipation close to a state of \textit{marginal stability} with re

Wing-Fai Thi, Gerd-Jan van Zadelhoff, Ewine F. van Dishoeck

The results of single-dish observations of low- and high-J transitions of selected molecules from protoplanetary disks around two TTauri stars (LkCa15 and TWHya) and two HerbigAe stars (HD163296 and MWC480) are reported. Simple molecules such as CO, 13CO, HCO+, CN and HCN are detected. Several lines of H2CO are found toward the TTauri star LkCa15 but not in

L. van Zyl, Z. Ioannou, P. A. Charles, T. Naylor

The luminous low-mass X-ray binary X2127+119 in the core of the globular cluster M15 (NGC 7078), which has an orbital period of 17 hours, has long been assumed to contain a donor star evolving off the main sequence, with a mass of 0.8 solar masses (the main-sequence turn-off mass for M15). We present orbital-phase-resolved spectroscopy of X2127+119 in the H-

F. Frontera, L. Amati, D. Lazzati, E. Montanari

We report observation results of the prompt X-- and $γ$--ray emission from GRB 000528. This event was detected with the Gamma-Ray Burst Monitor and one of the two Wide Field Cameras aboard the BeppoSAX satellite. The GRB was promptly followed on with the BeppoSAX Narrow Field Instruments and with ground optical and radio telescopes. The X-ray afterglow sourc

Hideyuki Kamaya

This paper presents a possible way to understand dissolution of OB associations (or groups). Assuming rapid escape of parental cloud gas from associations, we show that the shadow of the formation environment for associations can be partially imprinted on the velocity dispersion at their dissolution. This conclusion is not surprising as long as associations

D. Pourbaix, A. A. Tokovinin, A. H. Batten, F. C. Fekel

The Ninth Catalogue of Spectroscopic Binary Orbits (http://sb9.astro.ulb.ac.be) continues the series of compilations of spectroscopic orbits carried out over the past 35 years by Batten and collaborators. As of 2004 May 1st, the new Catalogue holds orbits for 2,386 systems. Some essential differences between this catalogue and its predecessors are outlined a

Yasufumi Kojima, Taishi Okita

We study the propagation and transmission of Alfven waves in the context of cylindrical geometry. This approximates the polar cap region of aligned pulsar with strong magnetic fields. Non-propagating region appears in the presence of rotation. The displacement current further prevents the low frequency modes from propagating near the stellar surface. The tra

Xinwu Cao

We use a sample of radio-loud active galactic nuclei (AGNs) with estimated central black hole masses to explore their jet formation mechanisms. The jet power of AGNs is estimated from their extended radio luminosity. It is found that the jets in several AGNs of this sample are too powerful to be extracted from the standard thin accretion disks or rapidly spi

Sara C. Beck, S. T. Garrington, Jean L. Turner, Schuyler D. Van Dyk

We have observed the starburst dwarf galaxy VII Zw 19 at subarcsecond resolution with the MERLIN and MERLIN+EVN networks at 18 cm, with MERLIN at 6 cm, and with the VLA in A array at 6 and 2 cm. The galaxy is detected at all VLA wavelengths and is resolved. It is also resolved at 18 cm by MERLIN, but is not detected by the EVN nor by MERLIN at 6 cm. VII Zw 1

Arbab I. Arbab

We have shown that the phenomenological models with a cosmological constant of the type $Λ=β(\frac{\ddot R}{R})$ and $Λ=3αH^2$, where $R$ is the scale factor of the universe and $H$ is the Hubble constant, are equivalent to a quintessence model with a scalar ($ϕ$) potential of the form $V\propto ϕ^{-n}, n$ = constant. The equation of state of the cosmic flui

Judd D. Bowman, Jacqueline N. Hewitt, James R. Kiger

Observational measurements of the relationship between supermassive black holes (SMBHs) and the properties of their host galaxies are an important method for probing theoretical hierarchical growth models. Gravitational lensing is a unique mechanism for acquiring this information in systems at cosmologically significant redshifts. We review the calculations

Adrian Vasiu

We prove several basic extension theorems for reductive group schemes. We also prove that each Lie algebra with a perfect Killing form over a commutative $\dbZ$-algebra, is the Lie algebra of an adjoint group scheme.

Thierry Monteil

A translation surface S is said to have the finite blocking property if for every pair (O,A) of points in S there exists a finite number of "blocking" points B_1,...,B_n such that every geodesic from O to A meets one of the B_i's. S is said to be purely periodic if the directional flow is periodic in each direction whose directional flow contains a periodic

Eli Dwek, Frank Krennrich

Very high energy (~ TeV) $γ$-rays from blazars are attenuated by photons from the extragalactic background light (EBL). Observations of blazars can therefore provide an ideal opportunity for determining the EBL intensity if their intrinsic spectrum is known. Conversely, knowledge of the EBL intensity can be used to determine the intrinsic blazar spectrum. Un

Anirban Basu, Michael B. Green, Savdeep Sethi

The operator, O_τ, that generates infinitesimal changes of the coupling constant in N=4 Yang-Mills sits in the same supermultiplet as the superconformal currents. We show how superconformal current Ward identities determine a class of terms in the operator product expansion of O_τwith any other operator. In certain cases, this leads to constraints on the cou

O. G. Miranda, M. A. Tortola, J. W. F. Valle

The robustness of the large mixing angle (LMA) oscillation (OSC) interpretation of the solar neutrino data is considered in a more general framework where non-standard neutrino interactions (NSI) are present. Such interactions may be regarded as a generic feature of models of neutrino mass. The 766.3 ton-yr data sample of the KamLAND collaboration are includ

Zhe Xu, Carsten Greiner

We develop a new 3+1 dimensional Monte Carlo cascade solving the kinetic on-shell Boltzmann equations for partons including the inelastic gg <-> ggg pQCD processes. The back reaction channel is treated -- for the first time -- fully consistently within this scheme. An extended stochastic method is used to solve the collision integral. The frame dependence an

Richard Kenyon, Lorenzo Sadun, Boris Solomyak

We investigate topological mixing for Z and R actions associated with primitive substitutions on two letters. The characterization is complete if the second eigenvalue $θ_2$ of the substitution matrix satisfies $|θ_2|\ne 1$. If $|θ_2|<1$, then (as is well-known) the substitution system is not topologically weak mixing, so it is not topologically mixing. We p

A. G. Akeroyd, W. Bartel, A. Bondar, T. E. Browder

This report presents the results of studies that investigate the physics reach at a Super B factory, an asymmetric-energy e^+e^- collider with a design luminosity of 5 x 10^35 cm^-2s^-1, which is around 40 times as large as the peak luminosity achieved by the KEKB collider. The studies focus on flavor physics and CP violation measurements that could be carri

B. C. Allanach, D. Grellscheid, F. Quevedo

We introduce genetic algorithms as a means to estimate the accuracy required to discriminate among different models using experimental observables. We exemplify the technique in the context of the minimal supersymmetric standard model. If supersymmetric particles are discovered, models of supersymmetry breaking will be fit to the observed spectrum and it is

Kunihito Ioka, Shiho Kobayashi, Peter Meszaros

We investigate the high-energy photon emission around Gamma-Ray Burst (GRB) remnants caused by ultrahigh-energy cosmic rays (UHECRs) from the GRBs. We apply the results to the recent report that the supernova remnant W49B is a GRB remnant in our Galaxy. If this is correct, and if GRBs are sources of UHECRs, a natural consequence of this identification would

D. E. Feldman, Robert A. Pelcovits

The nature of glass phases of liquid crystals in random porous media depends on the effective disorder strength. We study how the disorder strength depends on the density of the porous media and demonstrate that it can increase as the density decreases. We also show that the interaction of the liquid crystal with random porous media can destroy long--range o

Paolo Sibani, Henrik Jeldoft Jensen

The memory and rejuvenation aspects of intermittent heat transport are explored theoretically and by numerical simulation for Ising spin glasses with short-ranged interactions. The theoretical part develops a picture of non-equilibrium glassy dynamics recently introduced by the authors. Invoking the concept of marginal stability, this theory links irreversib