March 2004 arXiv papers — page 3

Randall Espinoza, Tom Imbo, Paul Lopata

In the companion to this paper, we described a generalization of the deterministic quantum cloning process, called enscription, which utilizes entanglement in order to achieve the "copying" of (certain) sets of distinct quantum states which are not orthogonal, called texts. Here we provide a further generalization, called translation, which allows us

Randall Espinoza, Tom Imbo, Paul Lopata

We investigate an entangled deformation of the deterministic quantum cloning process, called enscription, that can be applied to (certain) sets of distinct quantum states which are not necessarily orthogonal, called texts. Some basic theorems on enscribable texts are given, and a relationship to probabilistic quantum cloning is demonstrated.

N. G. de Almeida, R. M. Serra, C. J. Villas-Boas, M. H. Y. Moussa

While it has been possible to build fields in high-Q cavities with a high degree of squeezing for some years, the engineering of arbitrary squeezed states in these cavities has only recently been addressed [Phys. Rev. A 68, 061801(R) (2003)]. The present work examines the question of how to squeeze any given cavity-field state and, particularly, how to gener

Tabish Qureshi

A thought experiment, proposed by Karl Popper, which has been experimentally realized recently, is critically examined. A basic flaw in Popper's argument which has also been prevailing in subsequent debates, is pointed out. It is shown that Popper's experiment can be understood easily within the Copenhagen interpretation of quantum mechanics. An alte

Norio Konno, Takao Namiki, Takahiro Soshi

In this paper we study a one-dimensional quantum random walk with the Hadamard transformation which is often called the Hadamard walk. We construct the Hadamard walk using a transition matrix on probability amplitude and give some results on symmetry of probability distributions for the Hadamard walk.

Dwight Barkley, Laurette S. Tuckerman

Turbulent-laminar patterns near transition are simulated in plane Couette flow using an extension of the minimal flow unit methodology. Computational domains are of minimal size in two directions but large in the third. The long direction can be tilted at any prescribed angle to the streamwise direction. Three types of patterned states are found and studied:

J. Guéna, M. Lintz, M. A Bouchiat

Amplification by stimulated emission of radiation provides an intriguing means for increasing the sensitivity of Atomic Parity Violation (APV) measurements in a pump-probe configuration well adapted to the 6S-7S cesium transition. It takes advantage of the large number of atoms excited along the path of the pump beam. In the longitudinal E-field configuratio

Volker E. Oberacker, A. Sait Umar, Feodor F. Karpeshin

Following the formation of an excited muonic atom, inner shell transitions may proceed without photon emission by inverse internal conversion, i.e. the muonic excitation energy is transferred to the nucleus. In actinides, the 2p -> 1s and the 3d -> 1s muonic transitions result in excitation of the nuclear giant dipole and giant quadrupole resonances, respect

G. Colo`, N. Van Giai, J. Meyer, K. Bennaceur

The nuclear incompressibility $K_\infty$ is deduced from measurements of the Isoscalar Giant Monopole Resonance (ISGMR) in medium-heavy nuclei, and the resulting value turns out to be model dependent. Since the considered nuclei have neutron excess, it has been suggested that the model dependence is due to the different behaviour of the symmetry energy in di

Sean Kelly

The PHENIX experiment at RHIC has measured single electron spectra in proton-proton, deuteron-gold and gold-gold collisions at sqrt(s_NN)=200 GeV. The photonic contribution (photon conversions and Daltiz decays) is subtracted from the inclusive spectra resulting in non-photonic electron spectra. The principal source of non-photonic electrons is the semi-lept

V. S. Pronskikh, J. Adam, A. R. Balabekyan, V. S. Barashenkov

Two NaI (85% 129-I and 15% 127-I) targets were exposed to a beam of 660-MeV protons. Cross sections for formation of 76 residual nuclei were obtained by the induced activity method. The results are compared with other experimental data on 127-I and theoretical calculations by eleven models contained in the codes LAHET3 (using the Bertini+Dresner, ISABEL+Dres

V. D. Gershun

The closed string model in the background gravity field is considered as the bi-Hamiltonian system in assumption that string model is the integrable model for particular kind of the background fields. The dual nonlocal Poisson brackets, de pending of the background fields and of there derivatives, are obtained. The integrability condition is formulated as co

Oliver Maspfuhl

The motion of a classical particle in a gravitational and a Yang-Mills field was described by S. Sternberg and A. Weinstein by a particular Hamiltonian system on a Poisson manifold known under the name of Sternberg-Weinstein phase space. This system leads to the generalization of the Lorentz equation of motion first discovered by Wong. The aim of this work i

Alexandre Fedotov, Frederic Klopp

This paper is devoted to the description of our recent results on the spectral behavior of one-dimensional adiabatic quasi-periodic Schrodinger operators. The specific operator we study is a slow periodic perturbation of an incommensurate periodic Schrodinger operator, and we are interested in energies where the perturbation creates a strong interaction betw

R. Parthasarathy, R. Sridhar

A q-generalization of the product densities in stochastic point processes is developed. The properties of these functions are studied and a q-generalization of the usual $C^r_s$ coefficients is obtained. This for fixed q-number of particles coincides with the q-Stirling numbers of the second kind. The q-product densities are investigated using q-Poisson dist

Rodrigo Bamón, Jan Kiwi, Juan Rivera-Letelier, Richard Urzúa

We study the dynamics of skew product endomorphisms acting on the cylinder $\cyl$, of the form $$ \tht \mapsto (\ell θ, \la θ+ τ(θ)), $$ where $ \ell \geq 2$ is an integer, $\la \in (0,1)$ and $τ: \T \to \R$ is a continuous function. We are interested on {\it topological} properties of the global attractor $\Omegalt$ of this map. Given $\ell$ and a Lipschitz

Pietro Corvaja, Umberto Zannier

About fifty years ago Mahler proved that if $α>1$ is rational but not an integer and if $0<l<1$ then the fractional part of $α^n$ is $>l^n$ apart from a finite set of integers $n$ depending on $α$ and $l$. Answering completely a question of Mahler we show that the same conclusion holds for all algebraic numbers which are not $d$-th roots of Pisot numbers. By

Sergei Fedotov, Stephanos Panayides

The purpose of this work is to explore the role that arbitrage opportunities play in pricing financial derivatives. We use a non-equilibrium model to set up a stochastic portfolio, and for the random arbitrage return, we choose a stationary ergodic random process rapidly varying in time. We exploit the fact that option price and random arbitrage returns chan

Jean Ludwig, Detlef Müller, Sofiane Souaifi

We study the problem of determining all connected Lie groups $G$ which have the following property (hlp): every sub-Laplacian $L$ on $G$ is of holomorphic $L^p$-type for $1\leq p<\infty, p\ne 2.$ First we show that semi-simple non-compact Lie groups with finite center have this property. We then apply an $L^p$-transference principle, essentially due to Anker

Kieran G. O&#39;Grady

A $K3$ surface with an ample divisor of self-intersection 2 is a double cover of the plane branched over a sextic curve. We conjecture that a similar statement holds for the generic couple $(X,H)$ with $X$ a deformation of $(K3)^{[n]}$ and $H$ an ample divisor of square 2 for Beauville&#39;s quadratic form. If $n=2$ then according to the conjecture $X$ is a

Stefano Marmi, Pierre Moussa, Jean-Christophe Yoccoz

We exhibit an explicit full measure class of minimal interval exchange maps T for which the cohomological equation $Ψ-Ψ\circ T=Φ$ has a bounded solution $Ψ$ provided that the datum $Φ$ belongs to a finite codimension subspace of the space of functions having on each interval a derivative of bounded variation. The class of interval exchange maps is characteri

Folkmar Bornemann, Christian Rasch

We propose a linear finite-element discretization of Dirichlet problems for static Hamilton-Jacobi equations on unstructured triangulations. The discretization is based on simplified localized Dirichlet problems that are solved by a local variational principle. It generalizes several approaches known in the literature and allows for a simple and transparent

Luis Dieulefait

In a previous article (a joint work with J. Manoharmayum) the modularity of a large class of rigid Calabi-Yau threefolds was established. To make that result more explicit, we recall (and re-prove) a result of Serre giving a bound for the conductor of an &#34;integral&#34; 2-dimensional compatible family of Galois representations and apply this result to giv

Frederic Bosio

Nous refutons, sous une certaine hypothese combinatoire, la &#34;nonrevisiting path conjecture&#34;. Abstract: In this article, we give, under some hypothesis, a couterexample to the nonrevisiting path conjecture.

Fernando Etayo, Rafael Santamaría, Ujué R. Trías

This is a survey on bi-Lagrangian manifolds, which are symplectic manifolds endowed with two transversal Lagrangian foliations. We also study the non-integrable case (i.e., a symplectic manifold endowed with two transversal Lagrangian distributions). We show that many different geometric structures can be attached to these manifolds and we carefully analyse

Raimundas Vidunas

This paper presents expressions for gamma values at rational points with the denominator dividing 24 or 60. These gamma values are expressed in terms of 10 distinct gamma values and rational powers of $π$ and a few real algebraic numbers. Our elementary list of formulas can be conveniently used to evaluate, for example, algebraic Gauss hypergeometric functio

Elchanan Mossel

We study distorted metrics on binary trees in the context of phylogenetic reconstruction. Given a binary tree $T$ on $n$ leaves with a path metric $d$, consider the pairwise distances $\{d(u,v)\}$ between leaves. It is well known that these determine the tree and the $d$ length of all edges. Here we consider distortions $\d$ of $d$ such that for all leaves $

Gregory Eskin, James Ralston

We describe a simple way of constructing exponentially growing solutions of the second order systems with the Laplacian as the principal term.

Claus Gerhardt

We consider spacetimes $N$ satisfying some structural conditions, which are still fairly general, and prove convergence results for the leaves of an inverse mean curvature flow. Moreover, we define a new spacetime $\hat N$ by switching the light cone and using reflection to define a new time function, such that the two spacetimes $N$ and $\hat N$ can be past

Henrique Bursztyn, Alan Weinstein

These notes discuss various aspect of the ``representation theory&#39;&#39; of Poisson manifolds, with focus on Morita equivalence and Picard groups. We give a brief introduction to Poisson geometry (including Dirac and twisted Poisson structures) and algebraic Morita theory before presenting the geometric Morita theory of Poisson manifolds. We also point ou

Houman Owhadi

This paper is concerned with the approximation of the effective conductivity $σ(A,μ)$ associated to an elliptic operator $\nabla_x A(x,η) \nabla_x$ where for $x\in \R^d$, $d\geq 1$, $A(x,η)$ is a bounded elliptic random symmetric $d\times d$ matrix and $η$ takes value in an ergodic probability space $(X,μ)$. Writing $A^N(x,η)$ the periodization of $A(x,η)$ o

Houman Owhadi

This paper is concerned with the asymptotic behavior of solutions of stochastic differential equations $dy_t=dω_t -\nabla V(y_t) dt$, $y_0=0$. When $d=1$ and $V$ is not periodic but obtained as a superposition of an infinite number of periodic potentials with geometrically increasing periods ($V(x) = \sum_{k=0}^\infty U_k(x/R_k)$, where $U_k$ are smooth func

Frieder Lenz

In these lecture notes, an introduction to topological concepts and methods in studies of gauge field theories is presented. The three paradigms of topological objects, the Nielsen-Olesen vortex of the abelian Higgs model, the &#39;t Hooft-Polyakov monopole of the non-abelian Higgs model and the instanton of Yang-Mills theory, are discussed. The common forma

S. de Buyl, C. Schomblond

We identify the hyperbolic Kac Moody algebras for which there exists a Lagrangian of gravity, dilatons and $p$-forms which produces a billiard that can be identified with their fundamental Weyl chamber. Because of the invariance of the billiard upon toroidal dimensional reduction, the list of admissible algebras is determined by the existence of a Lagrangian

A. Parodi

Solutions of the Vacuum String Field Theory (VSFT) equation of motion involving matter part are given by projectors, and they represent nonperturbative solutions (e.g. the sliver) interpreted as D25-branes (or lower dimensional branes), but they are not mathematically well defined as they have zero norm. In this work we will use a regularization procedure ba

V. N. Rodionov

Given the anomalous magnetic moments of electrons and positrons in the one-loop approximation, we calculate the exact Lagrangian of an intense constant magnetic field that replaces the Heisenberg-Euler Lagrangian in traditional quantum electrodynamics (QED). We have established that the derived generalization of the Lagrangian is real for arbitrary magnetic

Terrance Figy, Dieter Zeppenfeld

Higgs boson production via weak boson fusion is sensitive to the tensor structure of the HVV (V=W,Z) couplings, which distinguishes loop induced vertices from SM expectations. At the CERN Large Hadron Collider this information shows up most clearly in the azimuthal angle correlations of the two forward and backward quark jets which are typical for weak boson

P. Bicudo

I study the charmed $uudd\bar c$ resonance D*p (3100) very recently discovered by the H1 collaboration at Hera. An anticharmed resonance was already predicted, in a recent publication mostly dedicated to the S=1 resonance Theta+(1540). To confirm these recent predictions, I apply the same standard quark model with a quark-antiquark annihilation constrained b

L. Marleau

We find exact solutions for Skyrmions for the Skyrme-like models. Constructing first the recursion formulae at small and large distance behavior, we proceed by implementing these constraints to a chosen parametrization of the solutions. The procedure is applied to the spherically symmetric hedgehog solution and to topological number N > 1 solutions based on

D. Kazanas, R. N. Mohapatra, S. Nasri, V. L. Teplitz

We show that spontaneous breaking of global $B-L$ symmetry responsible for small neutrino masses via the seesaw mechanism provides a unified picture of hybrid inflation and dark matter if the scale of $B-L$ breaking is close to the GUT scale. The majoron which acquires a small mass in the milli-eV range due to Planck scale breaking of $B-L$ is the dark matte

K. Zalewski

The core/halo model describes the Bose-Einstein correlations in multihadron production taking into account the effects of long-lived resonances. The model contains the combinatorial coefficients alpha_j which were originally calculated from a recurrence relation. We show that alpha_j is the integer nearest to j!/e.

Silas R. Beane

A critical appraisal is given of a recent analysis of the quark-mass and finite-size dependence of unquenched lattice QCD data for the nucleon mass. We use this forum to estimate the boundary of the chiral regime for nucleon properties.

Manu Mathur

We write the SU(2) lattice gauge theory Hamiltonian in (d+1) dimensions in terms of prepotentials which are the SU(2) fundamental doublets of harmonic oscillators. The Hamiltonian in terms of prepotentials has $SU(2) \otimes U(1)$ local gauge invariance. In the strong coupling limit, the color confinement in this formulation is due to the U(1) gauge group. W

A. H. Mahmood, CLEO Collaboration

We report a new measurement of the B-meson semileptonic decay momentum spectrum that has been made with a sample of 9.4/fb of electron-positron annihilation data collected with the CLEO II detector at the Y(4S) resonance. Electrons from primary semileptonic decays and secondary charm decays were separated by using charge and angular correlations in Y(4S) eve

S. E. Csorna, CLEO Collaboration

We present a measurement of the composition of B meson inclusive semileptonic decays using 9.4 fb^-1 of e^+e^- data taken with the CLEO detector at the Upsilon(4S) resonance. In addition to measuring the charged lepton kinematics, the neutrino four-vector is inferred using the hermiticity of the detector. We perform a maximum likelihood fit over the full thr

Gabriella Pasztor

Latest results from the LEP Collaboration on searches for neutral Higgs bosons predicted by the Standard Model and its minimal supersymmetric extension, the MSSM, are summarized.

N. K. Spyrou, C. G. Tsagas

We use covariant techniques to examine the implications of the dynamical equivalence between geodesic motions and adiabatic hydrodynamic flows. Assuming that the metrics of a geodesically and a non-geodesically moving fluid are conformally related, we calculate and compare their mass densities. The density difference is then expressed in terms of the fundame

Nelson Christensen, Peter Shawhan, Gabriela González

Presented is a summary of studies by the LIGO Scientific Collaboration&#39;s Inspiral Analysis Group on the development of possible vetoes to be used in evaluation of data from the first two LIGO science data runs. Numerous environmental monitor signals and interferometer control channels have been analyzed in order to characterize the interferometers&#39; p

L. Fernandez-Jambrina

Zipoy used spheroidal coordinates to construct a family of static axisymmetric gravitational fields included in Weyl&#39;s class. We calculate the mass moment source for the dipole solution using techniques previously developed for magnetic and angular momentum densities and compare it with the Newtonian analog studied by Bonnor and Sackfield.

Achim Kempf

It is shown that space-time may possess the differentiability properties of manifolds as well as the ultraviolet finiteness properties of lattices. Namely, if a field&#39;s amplitudes are given on any sufficiently dense set of discrete points this could already determine the field&#39;s amplitudes at all other points of the manifold. The criterion for when s

A. P. Ramirez, G. Lawes, D. Li, M. A. Subramanian

We present transport and thermal data for the quadruple-perovskites MCu3(Ti1-xRux)4O12 where 0 < x < 1. A metal-insulator transition (MIT) occurs for Ru concentrations x~0.75. At the same time, the Cu2+ antiferromagnetic state is destroyed and it&#39;s magnetic entropy suppressed by Ru on a 1:1 basis. This implies that each Ru transfers an electron to a Cu i

Bing Dong, Ivana Djuric, H. L. Cui, X. L. Lei

We derive the quantum rate equations for an Aharonov-Bohm interferometer with two vertically coupled quantum dots embedded in each of two arms by means of the nonequilibrium Green&#39;s function in the sequential tunneling regime. Basing on these equations, we investigate time-dependent resonant tunneling under a small amplitude irradiation and find that the

Jing Wang, Eric Polizzi, Mark Lundstrom

The silicon nanowire transistor (SNWT) is a promising device structure for future integrated circuits, and simulations will be important for understanding its device physics and assessing its ultimate performance limits. In this work, we present a three-dimensional quantum mechanical simulation approach to treat various SNWTs within the effective-mass approx

A. K. Rajagopal, C. S. Pande, Sumiyoshi Abe

Granular and nanoscale materials containing a relatively small number of constituents have been studied to discover how their properties differ from their macroscopic counterparts. These studies are designed to test how far the known macroscopic approaches such as thermodynamics may be applicable in these cases. A brief review of the recent literature on the

Wonkee Kim, F. Marsiglio, J. P. Carbotte

The cusp-like behavior of the microwave conductivity observed in clean ortho-II YB$_{2}$Cu$_{3}$O$_{6.50}$ at low temperature and low frequency is shown to be related directly to a linear in frequency dependence of the impurity scattering rate with a negligibly small value at zero frequency. In the weak scattering limit, the conductivity decreases linearly w

Krzysztof Byczuk, Jozef Spalek, Geoffrey Joyce, Sarben Sarkar

We overwiev the properties of a quantum gas of particles with the intermediate statistics defined by Haldane. Although this statistics has no direct connection to the symmetry of the multiparticle wave function, the statistical distribution function interpolates continuously between the Fermi-Dirac and the Bose-Einstein limits. We present an explicit solutio

Henryk A. Pinnow, Kay J. Wiese

The field theory of self-avoiding tethered membranes still poses major challenges. In this article, we report progress on the toy-model of a manifold repelled by a single point. Our approach allows to sum the perturbation expansion in the strength g_0 of the interaction exactly in the limit of internal dimension D -> 2, yielding an analytic solution for the

R. M. Fye, G. B. Martins, E. Dagotto

We analytically calculate the ground state pairing symmetry and excitation spectra of two holes doped into the half-filled t-t&#39;-t&#34;-Jz model in the strong-coupling limit (Jz>>|t|,|t&#39;|,|t&#34;|). In leading order, this reduces to the t&#39;-t&#34;-Jz model, where there are regions of d-wave, s-wave, and (degenerate) p-wave symmetry. We find that th

A. M. Savin, J. P. Pekola, J. T. Flyktman, A. Anthore

A superconductor-normal metal-superconductor mesoscopic Josephson junction has been realized in which the critical current is tuned through normal current injection using a symmetric electron cooler directly connected to the weak link. Both enhancement of the critical current by more than a factor of two, and supercurrent suppression have been achieved by va

L. Bogani, A. Caneschi, M. Fedi, D. Gatteschi

The problem of finite size effects in s=1/2 Ising systems showing slow dynamics of the magnetization is investigated introducing diamagnetic impurities in a Co$^{2+}$-radical chain. The static magnetic properties have been measured and analyzed considering the peculiarities induced by the ferrimagnetic character of the compound. The dynamic susceptibility sh

Sungchul Kwon, Hyunggyu Park

We study the absorbing phase transitions in coupled directed percolation (DP) processes with $N$-species particles in one dimension. The interspecies coupling is linear, bidirectional, and excitatory. We find that the presence of a spontaneous annihilation process $A\to 0$ is essential in stabilizing the absorbing phase (vacuum). In the coupled contact proce

Sang Koo You, Chul Koo Kim

We present a Rayleigh-Schroedinger-Goldstone perturbation formalism for many fermion systems. Based on this formalism, variational perturbation scheme which goes beyond the Gaussian approximation is developed. In order to go beyond the Gaussian approximation, we identify a parent Hamiltonian which has an effective Gaussian vacuum as a variational solution an

Enrique Canessa

A statistical thermodynamic approach of moving particles forming an elastic body is presented which leads to reveal molecular-mechanical properties of classical and nonextensive dynamical systems. We derive the Boltzmann-Gibbs (BG) entropy form and relate it to Newton&#39;s law of motion in relation to a distinct tensile force acting on the systems at consta

Frank Westerhoff

This note explores the consequences of nonlinear price impact functions on price dynamics within the chartist-fundamentalist framework. Price impact functions may be nonlinear with respect to trading volume. As indicated by recent empirical studies, a given transaction may cause a large (small) price change if market depth is low (high). Simulations reveal t

M. D. Girardeau, Hieu Nguyen, M. Olshanii

Derivation of effective zero-range one-dimensional (1D) interactions between atoms in tight waveguides is reviewed, as is the Fermi-Bose mapping method for determination of exact and strongly-correlated states of ultracold bosonic and fermionic atomic vapors in such waveguides, including spin degrees of freedom. Odd-wave 1D interactions derived from 3D p-wav

Dong-Hee Kim, Jae Dong Noh, Hawoong Jeong

We investigate the properties of the spanning trees of various real-world and model networks. The spanning tree representing the communication kernel of the original network is determined by maximizing total weight of edges, whose weights are given by the edge betweenness centralities. We find that a scale-free tree and shortcuts organize a complex network.

W. Zheng, J. Oitmaa, C. J. Hamer, R. R. P. Singh

Motivated by the recent discovery of superconductivity in Na$_x$CoO$_2\cdot y$H$_2$O, we use series expansion methods and cluster mean-field theory to study spontaneous charge order, Neel order, ferromagnetic order, dimer order and phase-separation in the triangular-lattice t-J-V model at 2/3 electron density. We find that for t<0, the charge ordered state,

Hiroyuki Yoshimoto, Susumu Kurihara

Effects of collective modes on thermoelectric properties of a charge density system is studied. We derive the temperature dependence of thermoelectric power and thermal conductivity by applying the linear response theory to Fröhlich Hamiltonian. Energy dissipation has been attributed to non-linear interaction between phase mode and amplitude mode, ignoring d

Björn Naundorf, Roland Ketzmerick

We study the energy spectrum and wave packet dynamics of electrons in a two-dimensional periodic potential subject to a perpendicular spatially modulated magnetic field. We observe avoided band crossings, metal-insulator transitions, and changes in the spreading direction of wave packets in two new situations: (i) for a purely magnetic modulation and (ii) in

D. Stauffer, A. O. Sousa, C. Schulze

The consensus model of Deffuant et al is simplified by allowing for many discrete instead of infinitely many continuous opinions, on a directed Barabasi-Albert network. A simple scaling law is observed. We then introduce noise and also use a more realistic network and compare the results. Finally, we look at a multi-layer model representing various age level

Raghuveer Parthasarathy, Xiao-Min Lin, Klara Elteto, T. F. Rosenbaum

We investigate how temperature affects transport through large networks of nonlinear conductances with distributed thresholds. In monolayers of weakly-coupled gold nanocrystals, quenched charge disorder produces a range of local thresholds for the onset of electron tunneling. Our measurements delineate two regimes separated by a cross-over temperature $T^*$.

Nickolay Y. Gnedin

I show that advanced simulations of cosmological reionization are able to fit the observed data on the mean transmitted flux in the hydrogen Lyman-alpha line at z~6. At the same time, posteriori models can be constructed that also produce a large value (20%) for the Thompson scattering optical depth, consistent with the WMAP measurements. Thus, it appears th

Amr El-Zant, Woong-Tae Kim, Marc Kamionkowski

We revisit the notion that galaxy motions can efficiently heat intergalactic gas in the central regions of clusters through dynamical friction. For plausible values of the galaxy mass-to-light ratio, the heating rate is comparable to the cooling rate due to X-ray emission. Heating occurs only for supersonic galaxy motions, so the mechanism is self-regulating

Andrea Comastri

The spectrum of the hard X-ray background records the history of accretion processes integrated over the cosmic time. Several pieces of observational and theoretical evidence indicate that a significant fraction of the energy density is obscured by large columns of gas and dust. The absorbing matter is often very thick, with column densities exceeding N_H >

D. Sowards-Emmerd, R. W. Romani, P. F. Michelson, J. S. Ulvestad

Supplementing existing survey data with VLA observations, we have extended $γ-$ray counterpart identifications down to decl. = -40$^\circ$ using our Figure of Merit approach. We find blazar counterparts for $\sim$ 70% of EGRET sources above decl. = -40$^\circ$ away from the Galaxy. Spectroscopic confirmation is in progress, and spectra for $\sim$ two dozen s

Christopher W. Mauche

We have fitted the Chandra Low Energy Transmission Grating spectrum of SS Cygni in outburst with a single temperature blackbody suffering the photoelectric opacity of a neutral column density and the scattering opacity of an outflowing wind. We find that this simple model is capable of reproducing the essential features of the observed spectrum with the blac

Richard Ignace Edward B Churchwell

In an effort to understand unusual power-law spectral slopes observed in some hypercompact HII regions, we consider the radio continuum energy distribution from an ensemble of spherical clumps. An analytic expression for the free-free emission from a single spherical clump is derived. The radio continuum slope (with F_ν ν^α) is governed by the population of

W. H. T. Vlemmings, J. M. Cordes, S. Chatterjee

High precision astrometric data have enabled us to determine the trajectories through the Galactic potential for a growing number of pulsars. This has resulted in the discovery of a pulsar pair (B2020+28 and B2021+51) that has a common origin in the Cygnus Superbubble or in one of its related OB associations at an epoch which is comparable with the spin-down

Gerard A. Kriss

More than half of all low-redshift AGN exhibit UV and X-ray absorption by highly ionized gas. The observed UV and X-ray absorption lines are almost always blue-shifted at velocities of hundreds of km/s, indicating that the absorbing gas is outflowing from the active nucleus. In some cases the inferred mass flux rivals the Eddington limit of the central black

K. L. Luhman, D. Steeghs

We present an analysis of candidate members of the Eta Cha and MBM 12A young associations. For an area of 0.7 deg^2 toward Eta Cha, we have performed a search for members of the association by combining JHK_s photometry from 2MASS and i photometry from DENIS with followup optical spectroscopy at Magellan Observatory. We report the discovery of three new memb

Gerard A. Kriss, the FUSE AGN Working Group

Using the Far Ultraviolet Spectroscopic Explorer (FUSE) we have obtained 87 spectra of 57 low-redshift (z<0.15) active galactic nuclei (AGN). This sample comprises 53 Type 1 AGN and 4 Type 2. All the Type 1 objects show broad O VI 1034 emission; two of the Type 2s show narrow O VI emission. In addition to O VI, we also identify emission lines due to C III 97

M. Haverkorn, F. Heitsch

Multi-frequency radio polarimetric observations of the diffuse Galactic synchrotron background enable us to study the structure of the diffuse ionized gas via rotation measure maps. However, depolarization will introduce artifacts in the resulting rotation measure, most notably in the form of narrow, elongated ``depolarization canals&#39;&#39;. We use numeri

Liliya L. R. Williams, Jeeseon Song

The current sample of high-redshift Supernova Type Ia, which combines results from two teams, High-z Supernova Search Team and Supernova Cosmology Project, is analyzed for the effects of weak lensing. After correcting SNe magnitudes for cosmological distances, assuming recently published, homogeneous distance and error estimates, we find that brighter SNe ar

R. Dowsett, O. Johnson, P. N. Best, O. Almaini

We are undertaking the first systematic study of the prevalence of AGN activity in a large sample of high redshift galaxy clusters. Local clusters contain mainly red elliptical galaxies, and have little or no luminous AGN activity. However, recent studies of some moderate to high redshift clusters have revealed significant numbers of luminous AGN within the

G. Di Cocco, A. J. Castro-Tirado, S. Chaty, A. J. Dean

The primary objective of the study of unidentified EGRET sources with INTEGRAL is to locate with a few arcminute accuracy the hard X-ray / soft gamma-ray counterparts within the EGRET error circle or to determine upper limits on their emission in the INTEGRAL energy range. The INTEGRAL Galactic Plane Scan (GPS) and Galactic Centre Deep Exposure (GCDE) data h

Tod E. Strohmayer

V407 Vul is a candidate double-degenerate binary with a putative 1.756 mHz (9.5 min) orbital frequency. In a previous timing study using archival ROSAT and ASCA data we reported evidence for an increase of this frequency at a rate consistent with expectations for gravitational radiation from a detached ultracompact binary system. Here we report the results o

Irini Sakelliou, Trevor J. Ponman

Abell 399 and Abell 401 are both rich clusters of galaxies, at temperatures 7.2keV and 8.5keV respectively. They lie at a projected separation of ~3Mpc, forming a close pair. We have observed the system with the XMM-Newton satellite. The data of each cluster show significant departures from our idealised picture of relaxed rich clusters. There is also eviden

Janet Drew, Jorick Vink, Tim Harries, Ryuichi Kurosawa

The aim of this article is to demonstrate the useful role that can be played by spectropolarimetric observations of young and evolved emission line stars that analyse the linearly polarized component in their spectra. At the time of writing, this demonstration has to be made on the basis of optical data since there is no common-user infrared facility, in ope

Yun-Song Piao, Yuan-Zhong Zhang

In this paper, focusing on the case of single scalar field, we discuss various expanding and contracting phases generating primordial perturbations, and study the relation between the primordial perturbation spectrum from these phases and the parameter w of state equation in details. Furthermore, we offer an interesting classification for the primordial pert

Lesley K. Summers, Ian R. Stevens, David K. Strickland, Timothy M. Heckman

We present Chandra and XMM-Newton X-ray data of NGC5253, a local starbursting dwarf elliptical galaxy, in the early stages of a starburst episode. Contributions to the X-ray emission come from discrete point sources and extended diffuse emission, in the form of what appear to be multiple superbubbles, and smaller bubbles probably associated with individual s

Bilal Khan, Kiran R. Bhutani, Delaram Kahrobaei

In this paper, we extend the classical arithmetic defined over the set of natural numbers N, to the set of all finite directed connected multigraphs having a pair of distinct distinguished vertices. Specifically, we introduce a model F on the set of such graphs, and provide an interpretation of the language of arithmetic L={0,1,<=,+,x} inside F. The resultin

David Poulin

We study macroscopic observables defined as the total value of a physical quantity over a collection of quantum systems. We show that previous results obtained for infinite ensemble of identically prepared systems lead to incorrect conclusions for finite ensembles. In particular, exact measurement of a macroscopic observable significantly disturbs the state

Paul Benioff

The problem of how mathematics and physics are related at a foundational level is of much interest. One approach is to work towards a coherent theory of physics and mathematics together. Here steps are taken in this direction by first examining the theory experiment connection. The role of an implied theory hierarchy and use of computers in comparing theory

F. R. Klinkhamer

As was shown previously, oscillations of massless neutrinos may be due to the splitting of multiply degenerate Fermi points. In this Letter, we give the details and propose a three-flavor model of Fermi point splittings and neutrino mixings with only two free parameters. The model may explain recent experimental results from the K2K and KamLAND collaboration

Michael Gronau, Jonathan L. Rosner, Jure Zupan

Flavor SU(3) is used to constrain the coefficients of $\sinΔmt$ and $\cosΔmt$ in the time-dependent CP asymmetry of $B^0 \to η&#39; K_S$. Correlated bounds in the $(S_{η&#39; K}, C_{η&#39; K})$ plane are derived, by using recent rate measurements of $B^0$ decays into $K^+ K^-, π^0π^0, π^0η, π^0η&#39;, ηη, ηη&#39;, η&#39;η&#39;$. Stringent bounds are obtained

Pavel Fileviez Perez

It is well known, although sometimes ignored, that not only the d=5 but also d=6 proton decay depends on fermion mixings. In general we study carefully the dependence of d=6 decay on fermion mixings using the effective operator approach. We find that without specifying a theory it is impossible to make clear predictions. Even in a given model, it is often no

J. M. Conrad, J. M. Link, M. H. Shaevitz

This paper presents a strategy for measuring sin^2 theta_W to ~1% at a reactor-based experiment, using antineutrinos electron elastic scattering. This error is comparable to the NuTeV, SLAC E158, and APV results on sin^2 theta_W, but with substantially different contributions to the systematics. An improved method for identifying antineutrino proton events,

Charis Anastopoulos

The probability `measure&#39; for measurements at two consecutive moments of time is non-additive. These probabilities, on the other hand, may be determined by the limit of relative frequency of measured events, which are by nature additive. We demonstrate that there are only two ways to resolve this problem. The first solution places emphasis on the precise

Katerina J. Argyraki, David R. Cheriton

A distributed denial-of-service (DDoS) attack can flood a victim site with malicious traffic, causing service disruption or even complete failure. Public-access sites like amazon or ebay are particularly vulnerable to such attacks, because they have no way of a priori blocking unauthorized traffic. We present Active Internet Traffic Filtering (AITF), a mecha

Ruth A. Daly, S. G. Djorgovski

Understanding of the nature of dark energy, which appears to drive the expansion of the universe, is one of the central problems of physical cosmology today. In an earlier paper [Daly & Djorgovski (2003)] we proposed a novel method to determine the expansion rate and the deceleration parameter in a largely model-independent way, directly from the data on coo