November 2005 arXiv papers — page 4

A. Raouf Chouikha

In this work we study the equation $(E) \ddot x + f(x) \dot x^2 + g(x) = 0$ with a center at 0 and investigate conditions of its isochronicity. When $f$ and $g$ are analytic (not necessary odd) a necessary and sufficient condition for the isochronicity of 0 is given. This approach allows us to present an algorithm for obtained conditions for a point of (E) t

Jun-Chen Su

To illustrate the unitarity of the massive gauge field theory described in the foregoing papers, we calculate the scattering amplitudes up to the fourth order of perturbation by the optical theorem and the Landau-Cutkosky rule. In the calculations, it is shown that for a given process, if all the diagrams are taken into account, the contributions arising fro

M. Bertola

We consider the two-matrix model with potentials whose derivative are arbitrary rational function of fixed pole structure and the support of the spectra of the matrices are union of intervals (hard-edges). We derive an explicit formula for the planar limit of the free energy and we derive a calculus which allows to compute derivatives of arbitrarily high ord

Jerome Martin, Marcello Musso

A method to estimate the reliability of a perturbative expansion of the stochastic inflationary Langevin equation is presented and discussed. The method is applied to various inflationary scenarios, as large field, small field and running mass models. It is demonstrated that the perturbative approach is more reliable than could be naively suspected and, in g

Hidenori Sonoda

An application of the exact renormalization group equations to the scalar field theory in three dimensional euclidean space is discussed. We show how to modify the original formulation by J. Polchinski in order to find the Wilson-Fisher fixed point using perturbation theory.

Bo Feng, Yang-Hui He, Kristian D. Kennaway, Cumrun Vafa

Dimer models are 2-dimensional combinatorial systems that have been shown to encode the gauge groups, matter content and tree-level superpotential of the world-volume quiver gauge theories obtained by placing D3-branes at the tip of a singular toric Calabi-Yau cone. In particular the dimer graph is dual to the quiver graph. However, the string theoretic expl

Federico Piazza

The holographic principle and the thermodynamics of de Sitter space suggest that the total number of fundamental degrees of freedom associated with any finite-volume region of space may be finite. The naive picture of a short distance cut-off, however, is hardly compatible with the dynamical properties of spacetime, let alone with Lorentz invariance. Conside

Jan Kotanski

The reggeized gluon states, which are also called Reggeons, appear in the scattering amplitude of hadrons in Regge limit. The wave-function of Reggeons satisfy the BKP equation, which in multi-colour limit of Quantum Chromodynamics is equivalent to the Schrodinger equation of the XXX Heisenberg SL(2,C) spin chain model. In this work we solve the BKP equation

Stephen Godfrey, Pat Kalyniak, Alexander Tomkins

Extra neutral gauge bosons arise in many extensions of the Standard Model. If one were to be discovered it would be necessary to measure its properties so that we could understand its origins. In this report we find that Z' couplings can be measured at the ILC precisely enough to distinguish between models up to a Z' mass of 2-3 TeV. An important ing

Adriana Cordero-Cid, G. Tavares-Velasco, J. J. Toscano

A long-lived very light pseudoscalar boson would favor lepton flavor violating transitions of charged leptons. Its implications on the l_i --> l_j γγ, and l_i --> l_j e^+ e^- transitions are investigated. Assuming 2 m_e < m_ϕ<m_μ, it is found that the inequality B(l_i --> l_j γγ)<B(l_i --> l_j e^+ e^-) is hold. The experimental constraints on the decays l_i

Stephen Godfrey, Shou-hua Zhu

In the event that the Higgs mass is large or that the electroweak interactions are strongly interacting at high energy, top quark couplings to longitudinal components of the weak gauge bosons could offer important clues to the underlying dynamics. It has been suggested that precision measurements of W_L W_L \to t\bar{t} and Z_L Z_L \to t\bar{t} might provide

G. K. Leontaris, A. Psallidas, N. D. Vlachos

Motivated by effective low energy models of string origin, we discuss the neutrino masses and mixing within the context of the Minimal Supersymmetric Standard Model supplemented by a U(1) anomalous family symmetry and additional Higgs singlet fields charged under this extra U(1). In particular, we interpret the solar and atmospheric neutrino data assuming th

T. Fujita, S. Kanemaki, S. Oshima

We discuss the gauge invariance of quark-quark potential in QCD in the perturbative treatment, and show that the gauge dependence of the quark-gluon interaction cannot be eliminated. Therefore, the quark-quark potential cannot properly be written in terms of physical variables in the perturbation theory. This is in contrast to the QED case in which the gauge

Robert Fleischer, Stefan Recksiegel

With the wealth of new data from the B-factories, b -> d penguin decays become available for study, in addition to their b -> s counterparts that have proven an indespensable tool for the exploration of new-physics effects in flavour physics. A prominent example of the b -> d penguin transitions is $\bar B^0_d \to K^0 \bar K^0$. We show that this decay can b

Alexander L. Bondarev

General equations for the calculation of amplitudes are presented. As an illustration of application of proposed formulae we calculate electron-electron scattering amplitudes.

M. Chaichian, M. M. Sheikh-Jabbari, A. Tureanu

Recently the PVLAS collaboration has reported the observation of rotation of polarization of light propagating in a background magnetic field. In this letter we explore the possibility that such a rotation is a result of noncommutativity in the background space-time. To explain the reported polarization rotation within noncommutative QED we need the noncommu

Laurent Schoeffel

Recent diffractive structure function measurements in deep inelastic scattering (DIS) by the H1 and ZEUS experiments at HERA are reviewed. In neutral current (NC) DIS, precise measurements have been made of diffraction, $ep \to eXY$, the signature of which is a large rapidity gap (LRG) between the hadronic system $X$ and the proton or one of its low-mass exc

Jie Hu, Thomas Mehen

We construct a chiral Lagrangian for doubly heavy baryons and heavy mesons that is invariant under heavy quark-diquark symmetry at leading order and includes the leading O(1/m_Q) symmetry violating operators. The theory is used to predict the electromagnetic decay width of the J=3/2 member of the ground state doubly heavy baryon doublet. Numerical estimates

Oleg Lebedev, Hans Peter Nilles, Michael Ratz

Recent progress in string theory moduli stabilization has motivated a mixed modulus-anomaly mediated supersymmetry breaking scenario, also dubbed `mirage mediation&#39;. This scenario has a number of phenomenologically attractive features, in particular with respect to the cosmological gravitino/moduli problem. In this note, we investigate the issues of fine

P. Colangelo, F. De Fazio, R. Ferrandes

We use recent experimental data on charmed mesons to constrain three coupling constants in the effective lagrangian describing the interactions of excited heavy-light mesons with light pseudoscalar mesons at order $m_Q^{-1}$. Predictions in the beauty sector are also derived.

Gudrun Hiller, A. Salim Safir

Using the operator product expansion (OPE) technique, we study the rare double radiative decay $B\to K γγ$ in the Standard Model (SM) and beyond. We estimate the short-distance (SD) contribution to the decay amplitude in a region of the phase space which is around the point where all decay products have energy $\sim m_b/3$ in the rest frame of the $B$-meson.

A. Donini, E. Fernandez, P. Migliozzi, S. Rigolin

In this paper, we discuss the possibilities offered to neutrino physics by the upgrades of the CERN accelerator complex. Emphasis is on the physics reach of a medium $γ$ (350-580) $β$-beam that fully exploits the improvements in the CERN accelerator complex for the luminosity/energy upgrade of the LHC. We show that, this design not only profits of the ongoin

Alexander L. Bondarev

This paper presents some relations for orthonormal bases in the Minkowski space and isotropic tetrads constructed from the vectors of these bases. As an example of an application of the obtained formulae, in particular recursion relations, a new method is proposed to calculate traces of Dirac $γ$-matrices in the Minkowski space. Compared to the classical alg

Apoorva D. Patel, Raghunath Ratabole

We had previously obtained an integral equation for mesons in transverse lattice QCD, in the limit of large number of colours and strong transverse lattice gauge coupling [1]. This equation is a generalisation of the &#39;t Hooft equation [2], by inclusion of the spin degrees of freedom. We analyse this equation to extract spectral properties and light-front

J. C. Anjos, A. F. Barbosa, R. Z. Funchal, E. Kemp

We present the status and plans of the Angra Project, a new nuclear reactor neutrino oscillation experiment, proposed to be built in Brazil at the Angra dos Reis nuclear reactor complex. This experiment is aimed to measure theta_13, the last unknown of the three neutrino mixing angles. Combining a high luminosity design, very low background from cosmic rays

M. G. Albrow, M. Atac, P. Booth, P. Crosby

We propose to add high precision track detectors 55m downstream on both (E&W) sides of CDF, to measure high Feynman-x protons and antiprotons in association with central states. A primary motivation is to search for the Higgs boson, and if it is seen to measure its mass precisely. The track detectors will be silicon strip telescopes backed up by high resolut

Alan D. Rendall

There are a number of mathematical theorems in the literature on the dynamics of cosmological models with accelerated expansion driven by a positive cosmological constant $Λ$ or a nonlinear scalar field with potential $V$ (quintessence) which do not assume homogeneity and isotropy from the beginning. The aim of this paper is to generalize these results to th

Sisir Bhanja, Subenoy Chakraborty, Ujjal Debnath

Here we study an anisotropic model of the universe with constant energy per particle. A decaying cosmological constant and particle production in an adiabatic process are considered as the sources for the entropy. The statefinder parameters $\{r,s\}$ are defined and their behaviour are analyzed graphically in some cases.

M. M. Verma

An argument is made to show that the singularity in the General Theory of Relativity (GTR) is the expression of a non-Machian feature. It can be avoided with a scale-invariant dynamical theory, a property lacking in GTR. It is further argued that the global non-conservation of energy in GTR also results from the lack of scale-invariance and the field formula

Alicia M Sintes

An overview of the searches for continuous gravitational wave signals in LIGO and GEO 600 performed on different recent science runs and results are presented. This includes both searching for gravitational waves from known pulsars as well as blind searches over a wide parameter space.

Norichika Sago, Takahiro Tanaka, Wataru Hikida, Katsuhiko Ganz

We investigate the adiabatic orbital evolution of a point particle in the Kerr spacetime due to the emission of gravitational waves. In the case that the timescale of the orbital evolution is enough smaller than the typical timescale of orbits, the evolution of orbits is characterized by the change rates of three constants of motion, the energy $E$, the azim

Roman Steigl, Franz Hinterleitner

The Wheeler-DeWitt equation of Friedmann models with a massless quantum field is formulated with arbitrary factor ordering of the Hamiltonian constraint operator. A scalar product of wave functions is constructed, giving rise to a probability interpretation and making comparison with the classical solution possible. In general the bahaviour of the wave funct

Jeremie Leguay, Timur Friedman, Vania Conan

Because a delay tolerant network (DTN) can often be partitioned, the problem of routing is very challenging. However, routing benefits considerably if one can take advantage of knowledge concerning node mobility. This paper addresses this problem with a generic algorithm based on the use of a high-dimensional Euclidean space, that we call MobySpace, construc

Vishwambhar Rathi, Rudiger Urbanke

We derive the density evolution equations for non-binary low-density parity-check (LDPC) ensembles when transmission takes place over the binary erasure channel. We introduce ensembles defined with respect to the general linear group over the binary field. For these ensembles the density evolution equations can be written compactly. The density evolution for

Na Li, Wen-feng Qi

To resist algebraic attack, a Boolean function should possess good algebraic immunity (AI). Several papers constructed symmetric functions with the maximum algebraic immunity $\lceil \frac{n}{2}\rceil $. In this correspondence we prove that for each odd $n$, there is exactly one trivial balanced $n$-variable symmetric Boolean function achieving the algebraic

Kenton K. Yee

This article summarizes recent research in financial economics about why information, such as earnings announcements, moves stock prices. The article does not presume any prior exposure to finance beyond what you might read in newspapers.

M. G. das Virgens, S. García, L. Ghivelder

The lower critical field of the grains, $H_{c1}$, and the intragrain critical current density, $J_{c}$, were determined for the superconducting ruthenate-cuprate RuSr$_{2}$Gd$_{1.5}$Ce$_{0.5}$Cu$_{2}$O$_{10-δ}$ [Ru-1222(Gd)] through a systematic study of the hysteresis in magnetoresistance loops. A reliable method, based on the effects of the magnetization o

B. G. Ueland, G. C. Lau, R. J. Cava, J. R. OBrien

We report measurements of the ac susceptibility of the cooperative paramagnet Tb2Ti2O7 in a strong magnetic field. Our data show the expected saturation maximum in chi(T) and also an unexpected low frequency dependence (< 1 Hz) of this peak, suggesting very slow spin relaxations are occurring. Measurements on samples diluted with nonmagnetic Y3+ or Lu3+ and

Fathollah Varnik, Oliver Henrich

Large scale molecular dynamics simulations are performed to study the steady state yielding dynamics of a well established simple glass. In contrast to the supercooled state, where the shear stress, $σ$, tends to zero at vanishing shear rate, $\gammadot$, a stress plateau forms in the glass which extends over about two decades in shear rate. This strongly su

Gary S. Grest, David R. Heine, Edmund B. Webb

Controlling the spatial distribution of liquid droplets on surfaces via surface energy patterning can be used to control material delivery to specified regions via selective liquid/solid wetting. While studies of the equilibrium shape of liquid droplets on heterogenous substrates exist, much less is known about the corresponding wetting kinetics. We make sig

Pavel Krotkov, Andrey V. Chubukov

We study the normal state and pairing instability in electron-doped cuprates near optimal doping. We show that the fermionic self-energy has a non-Fermi liquid form leading to peculiar frequency dependencies of the conductivity and the Raman response. We solve the pairing problem and demonstrate that T_c is determined by the curvature of the Fermi surface, a

Oswaldo Diéguez, David Vanderbilt

We develop an exact formalism for performing first-principles calculations for insulators at fixed electric polarization. As shown by Sai, Rabe, and Vanderbilt (SRV) [N. Sai, K. M. Rabe, and D. Vanderbilt, Phys. Rev. B {\bf 66}, 104108 (2002)], who designed an approximate method to tackle the same problem, such an approach allows one to map out the energy la

A. V. Chubukov, A. M. Tsvelik

We re-consider the self-energy of a nodal (Dirac) fermion in a 2D d-wave superconductor. A conventional belief is that Im Σ(ω, T) \sim max (ω^3, T^3). We show that Σ(ω, k, T) for k along the nodal direction is actually a complex function of ω, T, and the deviation from the mass shell. In particular, the second-order self-energy diverges at a finite T when ei

Nils Hasselmann, Florian Schuetz, Ivan Spremo, Peter Kopietz

We derive the effective long-wavelength Euclidean action for the antiferromagnetic spin-waves of ordered quantum antiferromagnets subject to a uniform magnetic field. We point out that the magnetic field dependence of the spin-wave dispersion predicted by the usual O(3)-quantum nonlinear sigma model disagrees with spin-wave theory. We argue that the nonlinea

S. Sarangi, S. P. Chockalingam, S. V. Bhat

The kinetic inductance properties of a thin superconducting sample of BSCCO-2223 compound is studied. A strong dependence of kinetic inductance with the variation of applied magnetic field is found at low temperature in the superconducting state. The kinetic inductance of a thin superconductor increases linearly with increasing magnetic field. This behavior

O. Hudak, W. Schranz

We describe the static dielectric response of ferroelastic-dielectric microcomposites. Its dependence on temperature, pressure and concentration is considered for smaller concentrations and for temperatures above the critical temperature. We have found a qualitative agreement with existing experimental data for $Al_{2}(WO_{4})_{3}$.

S. Sarangi, S. P. Chockalingam, S. V. Bhat

AC losses of granular superconducting MgB2 were measured using non-resonant rf power absorption techniques. The presence of two band-gaps makes the temperature dependent ac loss pattern of MgB2 different from other high Tc superconductors like YBa2Cu3O and BSCCO-2223. Josephson junction decoupling plays a major role in MgB2 polycrystalline samples, both in t

S. Sarangi, S. V. Bhat

Non-resonant radio frequency absorption (NRRA) of superconducting MgB2 pellet is investigated as a function of frequency, temperature, pressure, rf power, magnetic field, sample size and grain size. The NRRA signals of granular MgB2 samples show three separate and distinguish temperature dependent phase reversals, one of them is similar to the phase reversal

Ana Maria Rey, Indubala I Satija, Charles W Clark

Noise correlations, such as those observable in the time of flight images of a released cloud, are calculated for hard-core bosonic (HCB) atoms. We find that the standard mapping of HCB systems onto spin-1/2 XY models fails in application to computation of noise correlations due to the contribution of multiply occupied virtual states in HCB systems. Such sta

Martin R. Galpin, David E. Logan

Single-particle dynamics of the Anderson impurity model are studied using both the numerical renormalization group (NRG) method and the local moment approach (LMA). It is shown that a &#39;two-self-energy&#39; description of dynamics inherent to the LMA, as well as a conventional &#39;single-self-energy&#39; description, arise within NRG; each yielding corre

M. Becker, S. Crampin, R. Berndt

We present a quantitative many-body analysis using the GW approximation of the decay rate $Γ$ due to electron-electron scattering of excitations in the Shockley surface state band of Ag(111), as measured using the scanning tunnelling microscope (STM). The calculations include the perturbing influence of the STM, which causes a Stark-shift of the surface stat

Guoqing Miao, Kai Huang, Yi Yun, Peng Zhang

We report the experimental findings of formation and motion of heap in granular materials in an inclined and vertically vibrated container. We show experimentally how the transport velocity of heap up container is related to the driving acceleration as well as the driving frequency of exciter. An analogous experiment was performed with a heap-shaped Plexigla

Kai Huang, Guoqing Miao, Peng Zhang, Yi Yun

Shock wave formation and propagation in two-dimensional granular materials under vertical vibration are studied by digital high speed photography. The steepen density and temperature wave fronts form near the plate as granular layer collides with vibrating plate and propagate upward through the layer. The temperature front is always in the transition region

Zhi Ren, Jingqin Shen, Shuai Jiang, Xiaoyang Chen

We report the measurements of thermopower, electrical resistivity and thermal conductivity in a complex cobalt oxide Li$_{0.48}$Na$_{0.35}$CoO$_{2}$, whose crystal structure can be viewed as an intergrowth of the O3 phase of Li$_{x}$CoO$_{2}$ and the P2 phase of Na$_{y}$CoO$_{2}$ along the c axis. The compound shows large room-temperature thermopower of $\si

Asaph Widmer-Cooper, Peter Harrowell

We examine the relation between the free volume per particle and the variance of the particle position, equivalent to a local Debye-Waller (DW) factor for a 2D glass-forming alloy using molecular dynamics simulations. We find that the latter quantity exhibits significant spatial heterogeneity despite involving trajectories two orders of magnitude shorter tha

Kai Huang, Peng Zhang, Guoqing Miao, Rongjue Wei

We present experimental study of vibrofluidized granular materials by high speed photography. Statistical results present the averaged dynamic behaviors of granular materials in one cycle, including the variations of height, velocity and mechanical energy of the center of mass. Furthermore, time-space distribution of granular temperature which corresponds to

Kai Huang, Guoqing Miao, Peng Zhang, Yifei Zhu

Molecular dynamical (MD) simulations are performed to simulate two dimensional vibrofluidized granular materials in this work. Statistics on simulation results indicate that there exist shocks propagating upward in each vibrating cycle. Under certain driving parameters surface waves similar to Faraday instability in normal fluid coexist with internal waves.

Kazuhiko Seki, Mariusz Wojcik, M. Tachiya

The photoluminescence in amorphous semiconductors decays according to power law $t^{-delta}$ at long times. The photoluminescence is controlled by dispersive transport of electrons. The latter is usually characterized by the power $alpha$ of the transient current observed in the time-of-flight experiments. Geminate recombination occurs by radiative tunneling

Shu-Chiuan Chang, Robert Shrock

We study the zeros of the $q$-state Potts model partition function $Z(Λ,q,v)$ for large $q$, where $v$ is the temperature variable and $Λ$ is a section of a regular $d$-dimensional lattice with coordination number $κ_Λ$ and various boundary conditions. We consider the simultaneous thermodynamic limit and $q \to \infty$ limit and show that when these limits a

Lixin Feng, Xiaoming Tang, Yueyue Yan, Xuezhi Chen

Based upon a widely-accepted internal-barrier-layer-capacitance (IBLC) model, the dielectric loss in the giant-dielectric-constant CaCu$_{3}$Ti$_{4}$O$_{12}$ (CCTO) material is expected to decrease as the conductivity of the CCTO grains/subgrains increases. In this letter, we report that this idea was successfully realized through the La-for-Ca substitution

J. Mizubayashi, J. Haruyama, I. Takesue, T. Okazaki

We report encapsulated C60 molecules on electron transport in carbon-nanotube peapod quantum dots. We find atomic-like behaviors with doubly degenerate electronic levels, which exist only around ground states, by single electron spectroscopy measured at low back-gate voltages (Vbg&#39;s). Correlation with presence of nearly free electrons (NFEs) unique to th

Thomas Vojta, Joerg Schmalian

We show that the interplay of geometric criticality and quantum fluctuations leads to a novel universality class for the percolation quantum phase transition in diluted magnets. All critical exponents involving dynamical correlations are different from the classical percolation values, but in two dimensions they can nonetheless be determined exactly. We deve

Masaki Oshikawa, T. Senthil

We argue, based on general principles, that topological order is essential to realize fractionalization in gapped insulating phases in dimensions $d \geq 2$. In $d=2$ with genus $g$, we derive the existence of the minimum topological degeneracy $q^g$ if the charge is fractionalized in unit of $1/q$, irrespective of microscopic model or of effective theory. F

R. Capozza, D. Giuliano, P. Lucignano, A. Tagliacozzo

We calculate the oscillations of the DC conductance across a mesoscopic ring, simultaneously tuned by applied magnetic and electric fields orthogonal to the ring. The oscillations depend on the Aharonov-Bohm flux and of the spin-orbit coupling. They result from mixing of the dynamical phase, including the Zeeman spin splitting, and of geometric phases. By ch

J. E. Greene, A. J. Barth, L. C. Ho

We describe our efforts to study dwarf galaxies with active nuclei, whose black holes, with masses < 10^6 M_sun, provide the best current observational constraints on the mass distribution of primordial seed black holes. Although these low-mass galaxies do not necessarily contain classical bulges, Barth, Greene, & Ho (2005) show that their stellar velocity d

M. Mouhcine, I. Lewis, B. Jones, F. Lamareille

We investigate the systematic variation of the [OII]3727/Halpha flux line ratio as a function of various galaxy properties, i.e., luminosity, metallicity, reddening, and excitation state, for a sample of 1124 emission-line galaxies, with a mean redshift z ~ 0.06, drawn from the Two Degree Field Galaxy Redshift Survey. The mean observed and extinction-correct

K. L. Luhman, Lucia Adame, Paola D&#39;Alessio, Nuria Calvet

Using the Hubble Space Telescope, the 4 m Blanco telescope at the Cerro Tololo Inter-American Observatory, and the Spitzer Space Telescope, we have performed deep imaging from 0.8 to 8 um of the southern subcluster in the Chamaeleon I star-forming region. In these data, we have discovered an object, Cha 110913-773444, whose colors and magnitudes are indicati

Patrick A. Young, Chris L. Fryer, Aimee Hungerford, David Arnett

We compare a suite of 3D explosion calculations and stellar models incorporating advanced physics with observational constraints on the progenitor of Cassiopeia A. We consider binary and single stars from 16 to 40 solar masses with a range of explosion energies and geometries. The parameter space allowed by observations of nitrogen rich high velocity ejecta,

Laura Baudis

More than 90% of matter in the Universe could be composed of heavy particles, which were non-relativistic, or &#39;cold&#39;, when they froze-out from the primordial soup. I will review current searches for these hypothetical particles, both via interactions with nuclei in deep underground detectors, and via the observation of their annihilation products in

B. G. Castanheira, S. O. Kepler, F. Mullally, D. E. Winget

We report the discovery of eleven new ZZ Cetis using telescopes at OPD (Observatório do Pico dos Dias/LNA) in Brazil, the 4.1 m SOAR (Southern Astrophysical Research) telescope at Cerro Pachon, Chile, and the 2.1 m Otto Struve telescope at McDonald observatory. The candidates were selected from the SDSS (Sloan Digital Sky Survey) and SPY (ESO SN Ia progenito

G. Chabrier, D. Saumon, A. Potekhin

We briefly examine the properties of dense plasmas characteristic of the interior of giant planets and the atmospheres of neutron stars. Special attention is devoted to the equation of state of hydrogen and helium at high density and to the effect of magnetic fields on the properties of dense matter.

Patrick Dineen, Peter Coles

The extraction of cosmological parameters from microwave background observations relies on specific assumptions about the statistical properties of the data, in particular that the p-point distributions of temperature fluctuations are jointly-normal. Using a battery of statistical tests, we assess the multivariate Gaussian nature of the Wilkinson Microwave A

Michaela Kraus, Henny J. G. L. M. Lamers

We investigate the ionization structure in the non-spherical winds and disks of B[e] stars. Especially the luminous B[e] supergiants seem to have outflowing disks which are neutral in hydrogen already close to the stellar surface. The existence of neutral material so close to the central star is surprising and needs to be investigated in detail. We perform o

A A Watson

The status of measurements of the arrival directions, mass composition and energy spectrum of cosmic rays above 3 x 10^18 eV (3 EeV) is reviewed using reports presented at the 29th International Cosmic Ray Conference held in Pune, India, in August 2005. The paper is based on a plenary talk given at the TAUP2005 meeting in Zaragoza, 10 - 14 September 2005.

Dimitri A. Gadotti, Ronaldo E. de Souza

Along with a brief analysis we present data obtained from BVRI and Ks images of a sample of 19 galaxies (18 barred and 1 unbarred) which will be further explored in a future paper. We measured the lengths and colors of the bars, created color maps and estimated global color gradients. Applying a method developed in a companion paper, we could distinguish for

F. D&#39;Antona, P. Ventura, L. Burderi, T. Di Salvo

The monotonic increase of the radius of low mass stars during their ascent on the red giant branch halts when they suffer a temporary contraction. This occurs when the hydrogen burning shell reaches the discontinuity in hydrogen content left from the maximum increase in the convective extension, at the time of the first dredge up, and produces a well known &

R. P. Kraft, J. Azcona, W. R. Forman, M. J. Hardcastle

We present results from a 35 ks {\em Chandra}/ACIS-I observation of the hot ICM around the FR II radio galaxy 3C 388. 3C 388 resides in a cluster environment with an ICM temperature of $\sim$3.5 keV. We detect cavities in the ICM coincident with the radio lobes. The enthalpy of these cavities is $\sim1.2\times10^{60}$ ergs. The work done on the gas by the in

Maxim Yu. Khlopov

Hypothesis of heavy stable quark of 4th family can provide a nontrivial solution for cosmological dark matter if baryon asymmetry in 4th family has negative sign and the excess of anti-U quarks with charge (-2/3) is generated in early Universe. Excessive anti-U antiquarks form (\bar U \bar U \bar U) antibaryons with electric charge -2, which are all captured

Fabrizio Massi, Leonardo Testi, Leonardo Vanzi

We present the results of a Near-Infrared deep photometric survey of a sample of six embedded star clusters in the Vela-D molecular cloud, all associated with luminous (~10^3 Lsun) IRAS sources. The clusters are unlikely to be older than a few 10^6 yrs, since all are still associated with molecular gas. We employed the fact that all clusters lie at the same

A. S. Hales, T. M. Gledhill, M. J. Barlow, K. T. E. Lowe

We have carried out JHK polarimetric observations of eleven dusty young stars, by using the polarimeter module IRPOL2 with the near-IR camera UIST on the 3.8-m United Kingdom Infrared Telescope (UKIRT). Our sample targeted systems for which UKIRT-resolvable discs had been predicted by model fits to their spectral energy distributions. Our observations have c

C. J. A. P. Martins, E. P. S. Shellard

We present results from a detailed numerical study of the small-scale and loop production properties of cosmic string networks, based on the largest and highest resolution string simulations to date. We investigate the non-trivial fractal properties of cosmic strings, in particular, the fractal dimension and renormalised string mass per unit length, and we a

J. Horner, N. Wyn Evans

Large scale simulations of Centaurs have yielded vast amounts of data, the analysis of which allows interesting but uncommon scenarios to be studied. One such rare phenomenon is the temporary capture of Centaurs as Trojans of the giant planets. Such captures are generally short (10 kyr to 100 kyr), but occur with sufficient frequency (about 40 objects larger

Eduardo Bica, Charles Bonatto, Beatriz Barbuy, Sergio Ortolani

Updated data of the 153 Galactic globular clusters are used to readdress fundamental parameters of the Milky Way. We build a reduced sample, decontaminated of the clusters younger than 10Gyr, those with retrograde orbits and/or evidence of relation to dwarf galaxies. The 33 metal-rich globular clusters of the reduced sample extend basically to the Solar circ

Paolo Cea

P-stars are compact stars made of up and down quarks in $β$-equilibrium with electrons in a chromomagnetic condensate. We discuss p-stars endowed with super strong dipolar magnetic field which, following consolidated tradition in literature, are referred to as magnetars. We show that soft gamma-ray repeaters and anomalous $X$-ray pulsars can be understood wi

F. Lahuis, E. F. van Dishoeck, A. C. A. Boogert, K. M. Pontoppidan

Spitzer Space Telescope spectra of the low mass young stellar object (YSO) IRS 46 (L_bol ~ 0.6 L_sun) in Ophiuchus reveal strong vibration-rotation absorption bands of gaseous C2H2, HCN, and CO2. This is the only source out of a sample of ~100 YSO&#39;s that shows these features and the first time they are seen in the spectrum of a solar-mass YSO. Analysis o

Julia K. Becker, Michael Stamatikos, Francis Halzen, Wolfgang Rhode

In the hadronic fireball phenomenology of Gamma Ray Bursts (GRBs), it is expected that the observed photons are accompanied by UHE neutrinos, which have not been observed yet. It is one of the challenges of experimental UHE neutrino astrophysics to look for a signal from GRBs. In this paper, the differences between a search for a diffuse signal and an examin

Paola Grandi, Giuseppe Malaguti, Mariateresa Fiocchi, --

A systematic analysis of a large sample of radio-loud Active Galactic Nuclei available in the BeppoSAX public archive has been performed. The sample includes 3 Narrow Line Radio Galaxies (NLRG), 10 Broad Line Radio Galaxies (BLRG), 6 Steep Spectrum Radio Quasars (SSRQ), and 16 Flat Spectrum Radio Quasars (FSRQ). According to the unified models, these classes

U. Ertan, E. Gogus, M. A. Alpar

The long term (~1.5 years) X-ray enhancement and the accompanying infrared enhancement light curves of the anomalous X-ray pulsar 1E 2259+58 following the major bursting epoch can be accounted for by the relaxation of a fall back disk that has been pushed back by a gamma-ray flare. The required burst energy estimated from the results of our model fits is low

J. C. Pandey, K. P. Singh, S. A. Drake, R. Sagar

BVR photometric and quasi-simultaneous optical spectroscopic observations of the star HD 81032 have been carried out during the years 2000 - 2004. A photometric period of $18.802 \pm 0.07$ d has been detected for this star. A large group of spots with a migration period of $7.43 \pm 0.07$ years is inferred from the first three years of the data. H$α$ and Ca

Rafael D. Sorkin

This paper derives an objective Bayesian &#34;prior&#34; based on considerations of entropy/information. By this means, it produces a quantitative measure of goodness of fit (the &#34;H-statistic&#34;) that balances higher likelihood against the number of fitting parameters employed. The method is intended for phenomenological applications where the underlyi

Franck Delahaye, Marc Pinsonneault

The latest solar atmosphere models include non-LTE corrections and 3D hydrodynamic convection simulations. These models predict a significant reduction in the solar metal abundance, which leads to a serious conflict between helioseismic data and the predictions of solar interiors models. We demonstrate that the helioseismic constraints on the surface convect

Sang Chul Kim, Hong Soo Park, Sangmo Tony Sohn, Myung Gyoon Lee

We present BV CCD photometry for the open clusters Czernik 24 and Czernik 27. These clusters have never been studied before, and we provide, for the first time, the cluster parameters; reddening, distance, metallicity and age. Czernik 24 is an old open cluster with age 1.8 +/- 0.2 Gyr, metallicity [Fe/H]=-0.41 +/- 0.15 dex, distance modulus (m-M)_0 = 13.1 +/

Jorge I. Zuluaga

We study the sensitivity to neutrino masses of a Galactic supernova neutrino signal as could be measured with the detectors presently in operation and with future large volume water Čerencov and scintillator detectors. The analysis uses the full statistics of neutrino events. The method proposed uses the principles of Bayesian inference reasoning and has sho

Mark R. Krumholz

The physical mechanism that allows massive stars to form is a major unsolved problem in astrophysics. Stars with masses $\gtsim 20$ $\msun$ reach the main sequence while still embedded in their natal clouds, and the immense radiation output they generate once fusion begins can exert a force stronger than gravity on the dust and gas around them. They also pro

D. Meiser, P. Meystre

We consider the motion of the end mirror of a cavity in whose standing wave mode pattern atoms are trapped. The atoms and the light field strongly couple to each other because the atoms form a distributed Bragg mirror with a reflectivity that can be fairly high. We analyze how the dipole potential in which the atoms move is modified due to this backaction of

Riccardo Ricci

We apply mirror symmetry to the super Calabi-Yau manifold CP^{(n|n+1)} and show that the mirror can be recast in a form which depends only on the superdimension and which is reminiscent of a generalized conifold. We discuss its geometrical properties in comparison to the familiar conifold geometry. In the second part of the paper examples of special-Lagrangi

Amitava Bhattacharya, Uri N. Peled, Murali K. Srinivasan

Consider a graph whose edges have been colored red and blue. Assign a nonnegative real weight to every edge so that at every vertex, the sum of the weights of the incident red edges equals the sum of the weights of the incident blue edges. The set of all such assignments forms a convex polyhedral cone in the edge space, called the \emph{alternating cone}. Th

D. C. Cabra, N. E. Grandi

Experiments on tunneling into fractional quantum Hall droplets systematically found tunneling exponents smaller than those predicted by the ordinary chiral Luttinger liquid theory. In this note, by considering the effects of a smooth boundary, we propose a modification of the theory that predicts a reduced exponent, in qualitative agreement with experiments.

Jeronimo Peralta Ramos, Ana Maria Llois

We calculate the tunneling magnetoresistance (TMR) of Fe|ZnSe|Fe|ZnSe|Fe (001) double magnetic tunnel junctions as a function of the in-between Fe layer&#39;s thickness, and compare these results with those of Fe|ZnSe|Fe simple junctions. The electronic band structures are modeled by a parametrized tight-binding Hamiltonian fitted to ab initio calculations,

Ramón García-Rojo, Stefan Luding, J. Javier Brey

A study of the transport coefficients of a system of elastic hard disks, based on the use of Helfand-Einstein expressions is reported. The self-diffusion, the viscosity, and the heat conductivity are examined with averaging techniques especially appropriate for the use in event-driven molecular dynamics algorithms with periodic boundary conditions. The densi