June 2006 arXiv papers — page 44

Laura Luzzi, Stefano Marmi

We consider a one-parameter family of expanding interval maps $\{T_α\}_{α\in [0,1]}$ (japanese continued fractions) which include the Gauss map ($α=1$) and the nearest integer and by-excess continued fraction maps ($α={1/2},α=0$). We prove that the Kolmogorov-Sinai entropy $h(α)$ of these maps depends continuously on the parameter and that $h(α) \to 0$ as $α

Henriette Elvang, Daniel Z. Freedman, Boris Kors

We review and clarify the cancellation conditions for gauge anomalies which occur when N=1, D=4 supergravity is coupled to a Kahler non-linear sigma-model with gauged isometries and Fayet-Iliopoulos couplings. For a flat sigma-model target space and vanishing Fayet-Iliopoulos couplings, consistency requires just the conventional anomaly cancellation conditio

Jose F. Carinena, Hector Figueroa

In the context of the Feynman's derivation of electrodynamics, we show that noncommutativity allows other particle dynamics than the standard formalism of electrodynamics.

Simon Creek, Ruth Gregory, Panagiota Kanti, Bina Mistry

We look for spherically symmetric star or black hole solutions on a Randall-Sundrum brane from the perspective of the bulk. We take a known bulk solution, and analyse possible braneworld trajectories within it that correspond, from the braneworld point of view, to solutions of the brane Tolman-Oppenheimer-Volkoff equations. Our solutions are therefore embedd

Jutta Kunz, Dieter Maison, Francisco Navarro-Lerida, Jan Viebahn

We construct exact charged rotating black holes in Einstein-Maxwell-dilaton theory in $D$ spacetime dimensions, $D \ge 5$, by embedding the $D$ dimensional Myers-Perry solutions in $D+1$ dimensions, and performing a boost with a subsequent Kaluza-Klein reduction. Like the Myers-Perry solutions, these black holes generically possess $N=[(D-1)/2]$ independent

Ernest Ma

I review some of the recent progress (up to September 2005) in applying non-Abelian discrete symmetries to the family structure of leptons, with particular emphasis on the tribimaximal mixing ansatz of Harrison, Perkins, and Scott.

Vincenzo Cirigliano

In this talk I review recent developments in the calculation of radiative corrections to $K, D, B$ meson decays and discuss their impact on precision phenomenology.

E. H. Simmons, R. S. Chivukula, H. -J. He, M. Kurachi

This talk reviews recent progress in Higgsless models of electroweak symmetry breaking, and summarizes relevant points of model-building and phenomenology.

Christian W. Bauer

In this talk I will discuss non-leptonic B decays, in particular how soft-collinear effective field theory (SCET) can be used to constrain the non-perturbative hadronic parameters required to describe the various observables.

Mojtaba Mohammadi Najafabadi

In this paper we study the noncommutative effects to the lepton spectrum from the decay of a polarized top quark. It is shown that the lowest contribution comes from the quadratic terms of the noncommutative parameter. The deviations from the standard model are significant for small values of the noncommutative characteristic scale. However, the charged lept

Noriaki Kitazawa, Hiroaki Sugiyama, Osamu Yasuda

The effect of non-standard neutrino interactions with matter at long baseline neutrino experiments is examined in a model independent way, taking into account the constraints from all the experiments. It is found that such a non-standard interaction can enhance the flavor transition probability so significantly that the ongoing experiment MINOS may see the s

David Emmanuel-Costa, Ricardo Gonzalez Felipe

Using the current precision electroweak data, we look for the minimal particle content which is necessary to add to the standard model in order to have a complete unification of gauge couplings and gravity at the weakly coupled heterotic string scale. We find that the addition of a vector-like fermion at an intermediate scale and a non-standard hypercharge n

Alexander Grigoriev, Andrey Lobanov, Alexander Studenikin, Alexei Ternov

The claim of preprint hep-ph/0605114 that there is "no neutrino spin light because of photon dispersion in medium" is wrong.

Stephan J. Huber

Electroweak baryogenesis fails in the SM because of too small CP violation and the lack of a strong first-order phase transition. It has been shown that supersymmetric models allow for successful baryogenesis, where the Higgsinos play an important role in the transport processes that generate the asymmetry. I will demonstrate that also non-supersymmetric mod

Oystein Elgaroy, Ofer Lahav

Upper limits on neutrino masses from cosmology have been reported recently to reach the impressive sub-eV level, which is competitive with future terrestrial neutrino experiments. In this brief review of the latest limits from cosmology we point out some of the caveats that should be borne in mind when interpreting the significance of these limits.

Carlos A. Salgado

We review recent theoretical ideas and experimental data in high-energy heavy ion collisions with special emphasis in the hard probes.

H1 Collaboration

A detailed analysis is presented of the diffractive deep-inelastic scattering process $ep\to eXY$, where $Y$ is a proton or a low mass proton excitation carrying a fraction $1 - \xpom > 0.95$ of the incident proton longitudinal momentum and the squared four-momentum transfer at the proton vertex satisfies $|t|<1 {\rm GeV^2}$. Using data taken by the H1 exper

H1 Collaboration

The cross section for the diffractive deep-inelastic scattering process $ep \to e X p$ is measured, with the leading final state proton detected in the H1 Forward Proton Spectrometer. The data analysed cover the range \xpom <0.1 in fractional proton longitudinal momentum loss, 0.08 < |t| < 0.5 GeV^{-2} in squared four-momentum transfer at the proton vertex,

James G. Smith

We present a new result from Belle and many new results from BABAR for rare hadronic B decays. These include measurements of decays involving baryons, a Dalitz plot analysis of the three-charged-kaon system, many new results for B decays to eta&#39;X and omegaX, and a limit for the decay B-> a_1 rho. Measurements of the vector-vector decays B->rhoKstar and B

Christian Fronsdal

The Friedman universe is re-examined in a context that is non-standard only in that the properties of matter are postulated in the form of an action principle. Applications to equilibrium configurations of ideal stars have already been reported. In this paper we apply the same theory to a fresh examination of the Friedman universe. The results agree with sta

W. Rudnicki, R. J. Budzynski, W. Kondracki

This paper is a further development of the approach to weak cosmic censorship proposed by the authors in Ref. 5. We state and prove a modified version of that work&#39;s main result under significantly relaxed assumptions on the asymptotic structure of space--time. The result, which imposes strong constraints on the occurrence of naked singularities of the s

S. Deser

In this pedagogical note, we discuss obstacles to the usual Palatini formulations of gauge and gravity theories in presence of odd-derivative order, Chern-Simons, terms.

Rodolfo Gambini, Jorge Pullin

We apply the ``consistent discretization&#39;&#39; technique to the Regge action for (Euclidean and Lorentzian) general relativity in arbitrary number of dimensions. The result is a well defined canonical theory that is free of constraints and where the dynamics is implemented as a canonical transformation. This provides a framework for the discussion of top

Andrew Pavlo, Christopher Homan, Jonathan Schull

We have developed (1) a graph visualization system that allows users to explore graphs by viewing them as a succession of spanning trees selected interactively, (2) a radial graph layout algorithm, and (3) an animation algorithm that generates meaningful visualizations and smooth transitions between graphs while minimizing edge crossings during transitions a

Peter Wittenburg, Daan Broeder, Wolfgang Klein, Stephen Levinson

A number of serious reasons will convince an increasing amount of researchers to store their relevant material in centers which we will call &#34;language resource archives&#34;. They combine the duty of taking care of long-term preservation as well as the task to give access to their material to different user groups. Access here is meant in the sense that

Samuel Galice, Véronique Legrand, Marine Minier, John Mullins

In the context of ambient networks where each small device must trust its neighborhood rather than a fixed network, we propose in this paper a \textit{trust management framework} inspired by known social patterns and based on the following statements: each mobile constructs itself a local level of trust what means that it does not accept recommendation by ot

V. V. Kryssanov, V. A. Abramov, H. Hibino, Y. Fukuda

In this paper, an attempt is made to systematically discuss the development of simulation systems for manufacturing system design. General requirements on manufacturing simulators are formulated and a framework to address the requirements is suggested. Problems of information representation as an activity underlying simulation are considered. This is to form

Sergei Kojarski, David H. Lorenz

A plethora of diverse aspect mechanisms exist today, all of which integrate concerns into artifacts that exhibit crosscutting structure. What we lack and need is a characterization of the design space that these aspect mechanisms inhabit and a model description of their weaving processes. A good design space representation provides a common framework for und

David Steurer

Many load balancing problems that arise in scientific computing applications ask to partition a graph with weights on the vertices and costs on the edges into a given number of almost equally-weighted parts such that the maximum boundary cost over all parts is small. Here, this partitioning problem is considered for bounded-degree graphs G=(V,E) with edge co

Vicky Choi

In this paper, we present a fast algorithm for constructing a concept (Galois) lattice of a binary relation, including computing all concepts and their lattice order. We also present two efficient variants of the algorithm, one for computing all concepts only, and one for constructing a frequent closed itemset lattice. The running time of our algorithms depe

Marcela Hernandez, Harry Westfahl Junior

We model a melt of monodisperse side-chain liquid crystalline polymers as a melt of comb copolymers in which the side groups are rod-coil diblock copolymers. We consider both excluded volume and Maier-Saupe interactions. The first acts among any pair of segments while the latter acts only between rods. Using a free energy functional calculated from this micr

William P. Krekelberg, Venkat Ganesan, Thomas M. Truskett

We introduce and test via molecular simulation a simple model for predicting the manner in which interparticle interactions and thermodynamic conditions impact the single-particle free-volume distributions of equilibrium fluids. The model suggests a scaling relationship for the density-dependent behavior of the hard-sphere system. It also predicts how the se

S. E. Sebastian, N. Harrison, C. D. Batista, L. Balicas

Competition between electronic ground states near a quantum critical point (QCP) - the location of a zero-temperature phase transition driven solely by quantum-mechanical fluctuations - is expected to lead to unconventional behaviour in low-dimensional systems. New electronic phases of matter have been predicted to occur in the vicinity of a QCP by two-dimen

Marcus Benghi Pinto, Rudnei O. Ramos, Frederico F. de Souza Cruz

We study the thermodynamics of a two-species homogeneous and dilute Bose gas that is self-interacting and quadratically coupled to each other. We make use of field theoretical functional integral techniques and evaluate the one-loop finite temperature effective potential for this system considering the resummation of the leading order temperature dependent a

Yongsheng Zhang, Jutta Rogal, Karsten Reuter

We present a density-functional theory study addressing the on-surface adsorption of oxygen at the Pd(11N) (N =3,5,7) vicinal surfaces, which exhibit (111) steps and (100) terraces of increasing width. We find the binding to be predominantly governed by the local coordination at the adsorption site. This leads to very similar bonding properties at the threef

P. Zakharov, A. C. Voelker, A. Buck, B. Weber

We have analyzed the image formation and dynamic properties in laser speckle imaging (LSI) both experimentally and with Monte-Carlo simulation. We show for the case of a liquid inclusion that the spatial resolution and the signal itself are both significantly affected by scattering from the turbid environment. Multiple scattering leads to blurring of the dyn

Rafael Ramirez, Carlos P. Herrero, Eduardo R. Hernandez

Diamond is studied by path integral molecular dynamics simulations of the atomic nuclei in combination with a tight-binding Hamiltonian to describe its electronic structure and total energy. This approach allows us to quantify the influence of quantum zero-point vibrations and finite temperatures on both the electronic and vibrational properties of diamond.

F. Cordero, F. Craciun, A. Franco, C. Galassi

It has been recently shown that the memory of multiple aging stages, a phenomenon considered possible only below the glass transition of some glassy systems, appears also above that temperature range in the relaxor ferroelectric (Pb/La)(Zr/Ti)O_3 (PLZT). Doubts exist whether memory at such high temperature is intrinsic of the glassy relaxor state or is rathe

Giorgos Fagas, Paul Delaney, James C. Greer

Currents across thin insulators are commonly taken as single electrons moving across classically forbidden regions; this independent particle picture is well-known to describe most tunneling phenomena. Examining quantum transport from a different perspective, i.e., by explicit treatment of electron-electron interactions, we evaluate different single particle

Armel Le Bail

There is a huge and confusing literature about inorganic crystal structure prediction. The word &#34;prediction&#34; is used sometimes as meaning &#34;structure determination&#34; since the process described needs the knowledge of the chemical composition and of the cell parameters. Some clarifications are presented here together with a new software (GRINSP)

A. K. Arzhnikov, L. V. Dobysheva

The iron carbide $Fe_3C$ is studied by the first-principle density functional theory. It is shown that the crystal structure with the carbon disposition in a prismatic environment has the lowest total energy and the highest energy of magnetic anisotropy as compared to the structure with carbon in an octahedron environment. This fact explains the behavior of

Michael Murat, Yacov Kantor

We derive expressions for determination of the stress and the elastic constants in systems composed of particles interacting via non-central two-body potentials as thermal averages of products of first and second partial derivatives of the interparticle potentials and components of the interparticle separation vectors. These results are adapted to hard poten

Jae-Hyuk Choi, Min-Seok Kim, Yon-Kyu Park, Mahn-Soo Choi

We propose mechanical force realization based on flux quantization in the pico-Newton range. By controlling the number of flux quantum in a superconducting annulus, a force can be created as integer multiples of a constant step. For a 50 nm-thick Nb annulus with the inner and outer radii of 5 $μ$m and 10 $μ$m, respectively, and the field gradient of 10 T/m t

M. X. Huo, Ying Li, Z. Song, C. P. Sun

We systematically study the transfer of quantum state of electron spin as the flying qubit along a half-filled Peierls distorted tight-binding chain described by the Su-Schrieffer-Heeger (SSH) model, which behaves as a quantum data bus. This enables a novel physical mechanism for quantum communication with always-on interaction: the effective hopping of the

Yossi Farjoun, John C. Neu

We present a new model of homogeneous aggregation that contains the essential physical ideas of the classical predecessors, the Becker-Doring and Lifshitz-Slyovoz models. These classical models, which give different predictions, are asymptotic limits of the new model at small (BD) and large (LS) cluster sizes. Since the new theory is valid for large and smal

Sabina Ruiz-Chavarria, Gustavo Tavizon, Pablo de la Mora

In this work the effect of Carbon and Aluminium doping on the multiband MgB2 superconductor is analyzed. Using the rigid band and virtual crystal approximations (RBA and VCA), it was found that the main effect of doping on the band structure is band filling and a relative band-shift. If this band-shift is eliminated with an appropriate change of scale, then

Mahrous R. Ahmed, G. A. Gehring

The Jahn-Teller distortive transition of \lmo is described by a modified 3-state Potts model. The interactions between the three possible orbits depends both on the orbits and their relative orientation on the lattice. Values of the two exchange parameters which are chosen to give the correct low temperature phase and the correct value for the transition tem

Pedro M. Reis, Tim Sykes, Tom Mullin

We present results from an extensive experimental investigation into granular segregation of a shallow binary mixture in which particles are driven by frictional interactions with the surface of a vibrating horizontal tray. Three distinct phases of the mixture are established viz; binary gas (unsegregated), segregation liquid and segregation crystal. Their r

Ying Zhang, S. Das Sarma

By theoretically calculating the interacting spin susceptibility of a two-dimensional electron system in the presence of finite spin polarization, we show that the extensively employed technique of measuring the 2D spin susceptibility by linear extrapolation to a zero field from the finite-field experimental data is theoretically unjustified due to the stron

Andreas Ruttor, Wolfgang Kinzel, Rivka Naeh, Ido Kanter

Different scaling properties for the complexity of bidirectional synchronization and unidirectional learning are essential for the security of neural cryptography. Incrementing the synaptic depth of the networks increases the synchronization time only polynomially, but the success of the geometric attack is reduced exponentially and it clearly fails in the l

Yan Yin, Stephen Cronin, Andrew Walsh, Alexander Stolyarov

Intrinsic optical transition energies for isolated and individual single wall carbon nanotubes grown over trenches are measured using tunable resonant Raman scattering. Previously measured E22_S optical transitions from nanotubes in surfactants are blue shifted 70-90 meV with respect to our measurements of nanotubes in air. This large shift in the exciton en

Hua Feng, Philip Kaaret, Hans Andersson

A double-layer silicon detector consisting of two 500micron-thick silicon PIN photodiodes with independent readouts was mounted in a vacuum chamber and tested with X-ray sources. The detector is sensitive from 1-30 keV with an effective area of 6 mm^2. The detector performs best at -35 C with an energy resolution of 220 eV (FWHM, full width at half maximum)

Francois Schweizer

Mergers of gas-rich galaxies lead to gravitationally driven increases in gas pressure that can trigger intense bursts of star and cluster formation. Although star formation itself is clustered, most newborn stellar aggregates are unbound associations and disperse. Gravitationally bound star clusters that survive for at least 10-20 internal crossing times (~2

C. Moni Bidin, S. Moehler, G. Piotto, Y. Momany

We present preliminary results of a our search for close (period P < 10 days) binary systems among hot (Teff > 20000 K) horizontal branch stars in globular clusters M80 and NGC5986. We measured radial velocity variations of 11 targets in M80 and 5 in NGC5986, spectroscopically observed at medium resolution (R=4100) during four nights at VLT-FORS2. We found o

Alexander Vikman

It is well known that in manifestly Lorentz invariant theories with nontrivial kinetic terms, perturbations around some classical backgrounds can travel faster than light. These exotic &#34;supersonic&#34; models may have interesting consequences for cosmology and astrophysics. In particular, one can show that in such theories the contribution of the gravita

R. L. Porter, G. J. Ferland, S. B. Kraemer, B. K. Armentrout

We discuss new functionality of the spectral simulation code CLOUDY which allows the user to calculate grids with one or more initial parameters varied and formats the predicted spectra in the standard FITS format. These files can then be imported into the x-ray spectral analysis software XSPEC and used as theoretical models for observations. We present and

J. P. Marques, M. J. P. F. G. Monteiro, J. Fernandes

We discuss the effects of convective overshooting in the PMS evolution of intermediate mass stars, by analysing in detail the early evolution towards the main sequence of a 2 M_sun stellar model. These effects can be extremely important in the end of the PMS, when the abundances in CNO elements approach the equilibrium in the centre. We provide a possible ph

Martin Durant, Marten H. van Kerkwijk

We identify `red clump stars&#39; - core helium-burning giants - among 2MASS stars and use them to measure the run of reddening with distance in the direction of each of the Galactic Anomalous X-ray Pulsars (AXP). We combine this with extinction estimates from X-ray spectroscopy to infer distances and find that the locations of all AXP are consistent with be

M. Castellani, V. Castellani, P. G. Prada Moroni

We revisit the evolutionary scenario for Hot Flasher low-mass structures, where mass loss delays the He flash till the initial phases of their White Dwarf cooling sequence. Our aim has been to test the theoretical results vis-a-vis different assumptions about the efficiency of mass loss. To this purpose, we present evolutionary models covering a fine grid of

M. V. Popov, A. D. Kuzmin, O. M. Ul&#39;yanov, A. A. Deshpande

The results of simultaneous multifrequency observations of giant radio pulses from the Crab pulsar, PSR B0531+21, at 23, 111, and 600 MHz are presented and analyzed. Giant pulses were detected at a frequency as low as 23 MHz for the first time. Of the 45 giant pulses detected at 23 MHz, 12 were identified with counterparts observed simultaneously at 600 MHz.

Zsolt Sandor

The probability of the detection of Earth-like exoplanets may increase in the near future after the launch of the space missions using the transit photometry as observation method. By using this technique only the semi-major axis of the detected planet can be determined, and there will be no information on the upper limit of its orbital eccentricity. However

Chikako Yasui, Naoto Kobayashi, Alan T. Tokunaga, Hiroshi Terada

While conducting a near-infrared (NIR) survey of ``Digel Clouds&#39;&#39;, which are thought to be located in the extreme outer Galaxy (EOG), Kobayashi & Tokunaga found star formation activity in ``Cloud 2&#39;&#39;, a giant molecular cloud at the Galactic radius of ~ 20 kpc. Additional infrared imaging showed two embedded young clusters at the densest regio

P. S. Negi

We present explicit examples to show that the `compatibility criterion&#39; is capable of providing a {\em necessary} and {\em sufficient} condition for any regular configuration to be compatible with the state of hydrostatic equilibrium. This conclusion is drawn on the basis of the finding that the $M-R$ relation gives the necessary and sufficient condition

M. Fenovcik, J. S. Kaastra, E. Costantini, K. C. Steenbrugge

We study the absorption and emission properties of the photoionised gas near one of the brightest and most variable AGN, the Seyfert galaxy NGC 4051, in order to constrain the geometry, dynamics and ionisation structure of the outflow. We analyse two observations taken with the Low Energy Transmission Grating Spectrometer (LETGS) of Chandra. We study the spe

A. Bressan, R. Falomo, J. R. Valdes, R. Rampazzo

We present VLT long slit optical spectroscopy of the luminous BL Lacertae object PKS 2005-489. The high signal-to-noise ratio and the good spatial resolution of the data allow us to detect the signatures of ongoing star formation in an extended rotating ring, at ~4 kpc from the nucleus. We find that the ring is almost perpendicular to the radio axis and its

Tom Abel, John H. Wise, Greg L. Bryan

The concordance model of cosmology and structure formation predicts the formation of isolated very massive stars at high redshifts in dark matter dominated halos of 10^5 to 10^6 Msun. These stars photo-ionize their host primordial molecular clouds, expelling all the baryons from their halos. When the stars die, a relic HII region is formed within which large

L. L. Kiss

Using the Harvard College Observatory Photographic Plate Collection and recent CCD observations by the ASAS project we have reconstructed the light variations of the southern pulsating red giant star VZ Velorum between 1890 and early 2006. Contrary to an early report on its low-amplitude semiregular nature, we found a relatively stable Mira-like light curve

Kouichi Hirotani

A synthesis of the present knowledge on gamma-ray emission from the magnetosphere of a rapidly rotating neutron star is presented, focusing on the electrodynamics of particle accelerators. The combined curvature, synchrotron, and inverse-Compton emission from ultra-relativistic positrons and electrons, which are created by two-photon and/or one-photon pair c

Jonathan R. Trump, Chris D. Impey, Patrick J. McCarthy, Martin Elvis

We present spectroscopic redshifts for the first 466 X-ray and radio-selected AGN targets in the 2 deg^2 COSMOS field. Spectra were obtained with the IMACS instrument on the Magellan (Baade) telescope, using the nod-and-shuffle technique. We identify a variety of Type 1 and Type 2 AGN, as well as red galaxies with no emission lines. Our redshift yield is 72%

Qinghuan Luo

Coherent synchrotron emission by particles moving along semi-infinite tracks is discussed, with a specific application to radio emission from air showers induced by high-energy cosmic rays. It is shown that in general, radiation from a particle moving along a semi-infinite orbit consists of usual synchrotron emission and modified impulsive bremsstrahlung. Th

Ehud Nakar, Jonathan Granot

Some GRB afterglow light curves show significant variability, which often includes episodes of rebrightening. This was attributed in several cases to large fluctuations in the external density. Here we examine the effect of a sharp increase in the external density on the light curve by considering, for the first time, a full treatment of both the hydrodynami

Dario Izzo, Andreas Rathke

The Doppler-tracking data of the Pioneer 10 and 11 spacecraft show an unmodelled constant acceleration in the direction of the inner Solar System. Serious efforts have been undertaken to find a conventional explanation for this effect, all without success at the time of writing. Hence the effect, commonly dubbed the Pioneer anomaly, is attracting considerabl