September 2005 arXiv papers — page 8

Eduardo S. Fraga

For almost twenty years the effects of a nonzero strange quark mass on the equation of state of cold and dense QCD were considered to be negligible, thereby yielding only minor corrections to the mass-radius diagram of compact stars. By computing the thermodynamic potential to first order in α_s, and including the effects of the renormalization group running

Gang Hao, Lin Li, Cong-Feng Qiao

By adopting two models of strange and antistrange quark distributions inside nucleon, the light-cone meson-baryon fluctuation model and the effective chiral quark model, we calculate the $D_s^+ - D_s^-$ asymmetry in photoproduction in the framework of heavy-quark recombination mechanism. We find that the effect of asymmetry of strange sea to the $D_s$ asymme

D. Gomez Dumm, A. Pich, J. Portoles

Tau decays into hadrons foresee the study of the hadronization of vector and axial-vector QCD currents, yielding relevant information on the dynamics of the resonances entering into the processes. We analyse tau -> (3 pion) nu_tau decays within the framework of the Resonance Chiral Theory, comparing this theoretical scheme with the experimental data, namely

Y. Mambrini

We analyse the effect of the compression of the dark matter due to the infall of baryons to the galactic center on the gamma-ray flux. In addition, we also consider the effect of non-universal supersymmetric soft terms. This analysis shows that neutralino dark matter annihilation can give rise to signals largely reachable by future experiments like GLAST. Th

Wolfgang Hollik, Dominik Stöckinger

The evaluation of Yukawa-enhanced two-loop contributions to the MSSM Higgs-boson mass is considered. We prove the common assumption that regularization by dimensional reduction preserves supersymmetry at the required level. Thus generating counterterms by multiplicative renormalization is correct. Technically, we identify a suitable Slavnov-Taylor identity,

M. Beneke

A brief summary of outstanding theoretical issues and recent results from the QCD factorization approach to exclusive hadronic B decays is provided.

Daniel Zwanziger

We describe the gluon plasma in zeroth order as a gas of free quasi-particles with a temperature-independent dispersion relation of Gribov type, $E(k) = \sqrt{k^2 + {M^4 \over k^2}}$, that results from the restriction of the physical state space to the Gribov region. The effective mass ${M^2 \over k}$ controls infrared divergences of finite-temperature pertu

J. Portoles

Using the 1/N_C expansion scheme and truncating the hadronic spectrum to the lowest-lying multiplets of resonances we develop a procedure to implement QCD information on the non-perturbative regime populated by resonances through the use of three-point Green Functions of QCD currents. The process implies to enforce on these functions the constraints provided

M. Göckeler, R. Horsley, A. C. Irving, D. Pleiter

Using the O(a) Symanzik improved action an estimate is given for the strange quark mass for unquenched (nf=2) QCD. The determination is via the axial Ward identity (AWI) and includes a non-perturbative evaluation of the renormalisation constant. Numerical results have been obtained at several lattice spacings, enabling the continuum limit to be taken. Result

F. Di Renzo, A. Mantovi, V. Miccio, C. Torrero

Quark currents renormalization constants can in principle be safely computed in lattice perturbation theory. In practice, traditional lattice perturbative computations are quite cumbersome, so that so far only the first loop results were available. By making use of Numerical Stochastic Perturbation Theory we reached three (and with less statistical precision

C. Torrero, F. Di Renzo, V. Miccio, M. Laine

The QCD free energy can be studied by dimensional reduction to a three-dimensional (3d) effective theory, whereby non-perturbative lattice simulations become less demanding. To connect to the original QCD a perturbative matching computation is required, which is conventionally carried out in dimensional regularization. Therefore the 3d lattice results need t

Kurt Langfeld, Norbert Lages, Hugo Reinhardt

SU(2) lattice gauge theory is investigated where the traces of the Wilson lines at any lattice point and along each direction is constrained to zero. Hence, each of the lattice configurations possesses a vanishing density of heavy (anti-) quarks. The results are compared with those of pure SU(2) gauge theory which can be interpreted as the grand canonical re

Roberto Frezzotti, Giancarlo Rossi

We discuss how the peculiar properties of maximally twisted Wilson fermions can be exploited to set up a consistent LQCD computational scheme in which the CP-conserving matrix elements of the $ΔS =1,2$ effective weak Hamiltonian can be evaluated without mixing with wrong-chirality and/or -parity operators. The proposed lattice framework guarantees automatic

T. Chiarappa, R. Frezzotti, C. Urbach

We present a detailed design of a (P)HMC simulation algorithm for N_f = 2 + 1 + 1 maximally twisted Wilson quark flavours. The algorithm retains even/odd and mass-shift preconditionings combined with multiple Molecular Dynamics time scales for both the light mass degenerate, u and d, quarks and the heavy mass non-degenerate, s and c, quarks. Various non-stan

Victor Laliena

I present a method which can be used to locate the expected critical endpoint of the phase diagram of QCD with two light quark flavors. I illustrate the ideas on a suitable Random Matrix Model and show preliminary results in QCD

Martin Lüscher

Wilson's formulation of lattice QCD is attractive for many reasons, but perhaps mainly because of its simplicity and conceptual clarity. Numerical simulations of the Wilson theory (and of its improved versions) tend to be extremely demanding, however, to the extent that they rapidly become impractical at small quark masses. Recent advances in simulation

Rajiv Gavai, Sourendu Gupta

We investigate the critical end point (CEP) of QCD with two flavours of light dynamical quarks at finite lattice cutoff a=1/4T using a Taylor expansion of the baryon number susceptibility. We find a strong volume dependence of the position of the critical end point. In the large volume limit we obtain\ T^E/T_c approximately 0.95 and mu_B^E/T^E approximately

M. Doring, S. Ejiri, O. Kaczmarek, F. Karsch

We study the free energies of heavy quarks calculated from Polyakov loop correlation functions in full 2-flavour QCD using the p4-improved staggered fermion action. A small but finite Baryon number density is included via Taylor expansion of the fermion determinant in the Baryo-chemical potential mu. For temperatures above Tc we extract Debye screening masse

Toru T. Takahashi, Takashi Umeda, Tetsuya Onogi, Teiji Kunihiro

We study spin $\frac12$ hadronic states in quenched lattice QCD to search for a possible $S=+1$ pentaquark resonance. Our work is the first systematic lattice QCD study which properly carries out the following analyses: {\it (1) the careful extraction of the first two low energy states with very high statistics and the variational method} and {\it (2) the st

Lorenz von Smekal, Torsten Tok, Philippe de Forcrand

We explore the old idea that, in a theory containing several gauge groups, the topological defects of one gauge group coincide with those of another gauge group. This simple 'unification' constraint has deep consequences, the best known of which is a natural explanation of the fractional electric charge of quarks. Here we explore the consequences of

J. Volkholz, W. Bietenholz, J. Nishimura, Y. Susaki

We present results of numerical simulations for pure U(1) gauge theory in a non-commutative space. The theory is mapped onto a dimensionally reduced matrix model, which renders its numerical treatment feasible. New data on large lattices reveal the scaling of Wilson loops and their correlation functions in the simultaneous limit to the continuum and to infin

Takumi Doi, Noriyoshi Ishii, Yukio Nemoto, Makoto Oka

We perform the comprehensive analysis of the pentaquark (5Q) in J^P=3/2^{\pm} channel using anisotropic quenched lattice QCD. We employ the standard Wilson gauge action at β=5.75 and the O(a) improved Wilson (clover) quark action on a 12^3*96 lattice with the renormalized anisotropy as a_s/a_t = 4. A large number of gauge configurations as Nconf=1000 is anal

Jun Cao

The Daya Bay Neutrino Experiment is proposed to measure sin^2(2θ_{13}) to better than 0.01 at 90% C.L. in a three-year run. The experimental site, detector design, and background estimation are presented.

John T Whelan

The response of a cross-correlation measurement to an isotropic stochastic gravitational-wave background depends on the observing geometry via the overlap reduction function. If one of the detectors being correlated is a resonant bar whose orientation can be changed, the response to stochastic gravitational waves can be modulated. I derive the general form o

Mihalis Dafermos, Alan D. Rendall

A new criterion for inextendibility of expanding cosmological models with symmetry is presented. It is applied to derive a number of new results and to simplify the proofs of existing ones. In particular it shows that the solutions of the Einstein-Vlasov system with $T^2$ symmetry, including the vacuum solutions, are inextendible in the future. The technique

Yurij Baryshev

Gravity theory is the basis of modern cosmological models. Thirring-Feynman's tensor field approach to gravitation is an alternative to General Relativity (GR). Though Field Gravity (FG) approach is still developing subject, it opens new understanding of gravitational interaction, stimulates novel experiments on the nature of gravity and gives possibilit

Alejandro Cabo, Alejandro Garcia-Chung, Alejandro Rosabal

The existence of a simple spherically symmetric and static solution of the Einstein equations in the presence of a cosmological constant vanishing outside a definite value of the radial distance is investigated. A particular succession of field configurations, which are solutions of the Einstein equations in the presence of the considered cosmological term a

Roger Bieli

A late time asymptotic perturbative analysis of curvature coupled complex scalar field models with accelerated cosmological expansion is carried out on the level of formal power series expansions. For this, algebraic analogues of the Einstein scalar field equations in Gaussian coordinates for space-time dimensions greater than two are postulated and formal s

Sanquan Song, Dennis L. Goeckel, Don Towsley

Xue and Kumar have established that the number of neighbors required for connectivity of wireless networks with N uniformly distributed nodes must grow as log(N), and they also established that the actual number required lies between 0.074log(N) and 5.1774log(N). In this short paper, by recognizing that connectivity results for networks where the nodes are d

Jeroen Bekaert, Xiaoming Liu, Herbert Van de Sompel

Various efforts aimed at representing digital assets have emerged from several communities over the last years, including the Metadata Encoding and Transmission Standard (METS), the IMS Content Packaging (IMS-CP) XML Binding and the XML Formatted Data Units (XFDU). The MPEG-21 Digital Item Declaration (MPEG-21 DID) is another approach that can be used for th

Yossi Zana, Roberto M. Cesar-Jr, Rogerio S. Feris, Matthew Turk

We present a novel local-based face verification system whose components are analogous to those of biological systems. In the proposed system, after global registration and normalization, three eye regions are converted from the spatial to polar frequency domain by a Fourier-Bessel Transform. The resulting representations are embedded in a dissimilarity spac

Yossi Zana, Roberto M. Cesar-JR

A novel biologically motivated face recognition algorithm based on polar frequency is presented. Polar frequency descriptors are extracted from face images by Fourier-Bessel transform (FBT). Next, the Euclidean distance between all images is computed and each image is now represented by its dissimilarity to the other images. A Pseudo-Fisher Linear Discrimina

Yossi Zana, Roberto M. Cesar-Jr, Regis de A. Barbosa

We present an automatic face verification system inspired by known properties of biological systems. In the proposed algorithm the whole image is converted from the spatial to polar frequency domain by a Fourier-Bessel Transform (FBT). Using the whole image is compared to the case where only face image regions (local analysis) are considered. The resulting r

Steven H. Simon, Aris L. Moustakas, Luca Marinelli

We apply a promising new method from the field of representations of Lie groups to calculate integrals over unitary groups, which are important for multi-antenna communications. To demonstrate the power and simplicity of this technique, we first re-derive a number of results that have been used recently in the community of wireless information theory, using

David Manset, Richard McClatchey, Flavio Oquendo, Herve Verjus

As a consequence to the hype of Grid computing, such systems have seldom been designed using formal techniques. The complexity and rapidly growing demand around Grid technologies has favour the use of classical development techniques, resulting in no guidelines or rules and unstructured engineering processes. This paper advocates a formal approach to Grid ap

Manuel Torres, Alejandro Kunold

In this work we present a model for the photoconductivity of two-dimensional electron system in a perpendicular homogeneous magnetic field, a weak lateral superlattice, and exposed to millimeter irradiation. The model includes the microwave and Landau contributions in a non-perturbative exact way, the periodic potential is treated perturbatively. The Landau-

J. D. Jorgensen, M. Avdeev, D. G. Hinks, P. W. Barnes

We have performed thermal expansion and compressibility measurements on the recently discovered superconducting material NaxCoO2*4xD2O (x=1/3) using neutron powder diffraction over the temperature range 10-295 K and the pressure range 0-0.6 GPa. Pressure measurements were done in a helium-gas pressure cell. Both the thermal expansion and compressibility are

B. Davoudi, A. -M. S. Tremblay

We generalize the two-particle self-consistent approach (TPSC) to study the extended Hubbard model, where nearest-neighbor interaction is present in addition to the usual local screened interaction. Similarities and differences between the TPSC approach and the Singwi Tosi Land Sjölander (STLS) approximation for the electron gas are discussed. The accuracy o

W. Escoffier, C. Chapelier, F. Lefloch

Using a Scanning Tunneling Microscope (STM), we investigate the Local Density of States (LDOS) of artificially fabricated normal metal nano-structures in contact with a superconductor. Very low temperature local spectroscopic measurements (100 mK) reveal the presence of well defined subgap peaks at energy |E|<Delta in the LDOS at various positions of the STM

Yuriy I. Kuzmin

The effect of fractal clusters on magnetic and transport properties of percolative superconductors is considered. The superconductor contains percolative superconducting cluster, carrying a transport current, as well as clusters of a normal phase, which act as pinning centers. A prototype of such a structure is a high-temperature superconducting wire. It is

R. Oppermann, D. Sherrington

Using numerical self-consistent solutions of a sequence of finite replica symmetry breakings (RSB) and Wilson&#39;s renormalization group but with the number of RSB-steps playing a role of decimation scales, we report evidence for a non-trivial T->0-limit of the Parisi order function q(x) for the SK spin glass. Supported by scaling in RSB-space, the fixed po

Rajamani Raghunathan, S. Ramasesha, Corine Mathonière, Valérie Marvaud

A theoretical model for understanding photomagnetism in the heptanuclear complex $[Mo(IV)(CN)_2(CN-CuL)_6]^{8+}$ perchlorate is developed. It is a many-body model involving the active orbitals on the transition metal ions. The model is exactly solved using a valence bond approach. The ground state solution of the model is highly degenerate and is spanned by

Masatsugu Suzuki, Itsuko S. Suzuki, Motohiro Matsuura

Stage-2 CoCl$_{2}$ graphite intercalation compound undergoes two magnetic phase transitions at $T_{cl}$ (= 7.0 K) and $T_{cu}$ (= 8.9 K). The aging dynamics of this compound is studied near $T_{cl}$ and $T_{cu}$. The intermediate state between $T_{cl}$ and $T_{cu}$ is characterized by a spin glass phase extending over ferromagnetic islands. A genuine thermor

D. Keller, D. R. Yakovlev, G. V. Astakhov, W. Ossau

The optical properties of two-dimensional electron gases in ZnSe/(Zn,Be)Se and ZnSe/(Zn,Be,Mg)Se modulation-doped quantum wells with electron densities up to 1.4x10^{12} cm^{-2} were studied by photoluminescence, photoluminescence excitation and reflectivity in a temperature range between 1.6 and 70 K and in external magnetic fields up to 48 T. In these stru

Christian Wald, Paul M. Goldbart, Annette Zippelius

We consider a microscopic model of a polymer blend that is prone to phase separation. Permanent crosslinks are introduced between randomly chosen pairs of monomers, drawn from the Deam-Edwards distribution. Thereby, not only density but also concentration fluctuations of the melt are quenched-in in the gel state, which emerges upon sufficient crosslinking. W

Baruch Meerson, Leonard M. Sander, Peter Smereka

We investigate the role of discrete-particle noise in interface-controlled Ostwald ripening. We introduce the noise within the framework of the Becker-Doering equations, and employ both Monte Carlo simulations and direct numerical solution of these equations. We find that the noise drives the system towards a unique scaling regime describable by a limiting s

C. Vignat, A. Plastino

In this paper, we present some geometric properties of the maximum entropy (MaxEnt) Tsallis- distributions under energy constraint. In the case q > 1, these distributions are proved to be marginals of uniform distributions on the sphere; in the case q < 1, they can be constructed as conditional distribu- tions of a Cauchy law built from the same uniform dist

E. Klotins

Nonadiabatic behavior of metastable systems modeled by anharmonic Hamiltonians is reproduced by the Fokker-Planck and imaginary time Schrodinger equation scheme with subsequent symplectic integration. Example solutions capture ergodicity breaking, reassure the H-theorem of global stability [M. Shiino, Phys. Rev. A, Vol 36, pp. 2393-2411 (1987)], and reproduc

S. V. Ghaisas

Growth of interfaces during vapor deposition is analyzed on a discrete lattice. It leads to finding distribution of local heights, measurable for any lattice model. Invariance in the change of this distribution in time is used to determine the finite size effects in various models The analysis is applied to the discrete linear growth equation and Kardar-Pari

M. G. Vergniory, J. M. Pitarke, S. Crampin

A theoretical many-body analysis is presented of the electron-electron inelastic lifetimes of Shockley electrons and holes at the (111) surface of Cu. For a description of the decay of Shockley states both below and above the Fermi level, single-particle wave functions have been obtained by solving the Schrödinger equation with the use of an approximate one-

Martin Hasenbusch, Andrea Pelissetto, Ettore Vicari

We study the phase diagram and critical behavior of the two-dimensional square-lattice fully frustrated XY model (FFXY) and of two related models, a lattice discretization of the Landau-Ginzburg-Wilson Hamiltonian for the critical modes of the FFXY model, and a coupled Ising-XY model. We present a finite-size-scaling analysis of the results of high-precision

T. S. Biro, G. Kaniadakis

We connect two different generalizations of Boltzmann&#39;s kinetic theory by requiring the same stationary solution. Non-extensive statistics can be produced by either using corresponding collision rates nonlinear in the one-particle densities or equivalently by using nontrivial energy composition rules in the energy conservation constraint. Direct transfor

N. Shah, A. Rosch

Motivated by recent experiments, we consider a single-electron transistor in the Kondo regime which is coupled to three leads in the presence of large bias voltages. Such a steady-state non-equilibrium system is to a large extent governed by a decoherence rate induced by the current through the dot. As the two-terminal conductance turns out to be rather inse

P. Padhan, W. Prellier

We have observed the pinned/biased moments in the superlattices consisting of ferromagnetic (FM) SrRuO3 (SRO) and antiferromagnetic (AFM) SrMnO3 (SMO)bilayer. The alternate stacking of SRO and SMO leading to a low field positive magnetoresistance with enhanced hysteretic field dependent magnetoresistance under the application of the out-of-plane magnetic fie

Masaki Oshikawa, Claudio Chamon, Ian Affleck

We study a junction of three quantum wires enclosing a magnetic flux. The wires are modeled as single-channel spinless Tomonaga-Luttinger liquids. This is the simplest problem of a quantum junction between Tomonaga-Luttinger liquids in which Fermi statistics enter in a non-trivial way. We study the problem using a mapping onto the dissipative Hofstadter mode

R. Lal, V. P. S. Awana, K. P. Singh, H. Kishan

Measurements have been performed of the resistivity of the samples of MgB2, AlB2 and AgB2. The samples show presence of impurities. Analyzing the data in terms of the impurity scattering, electron-phonon scattering, and weak localization it has been found that the AlB2 (AgB2) sample involves maximum (minimum) effect of the impurity, electron-phonon interacti

A. A. Taskin, Yoichi Ando

In RBaCo_{2}O_{5+x} compounds (R is rare earth) variability of the oxygen content allows precise doping of CoO_2 planes with both types of charge carriers. We study transport properties of doped GdBaCo_{2}O_{5+x} single crystals and find a remarkable asymmetry in the behavior of holes and electrons doped into a parent insulator GdBaCo_{2}O_{5.5}. Doping depe

Pawel Bryk

We use a microscopic density functional theory based on Wertheim&#39;s first order thermodynamic perturbation theory to study wetting behavior of athermal mixtures of colloids and excluded-volume polymers. In opposition to the wetting behavior of the Asakura-Oosawa-Vrij model we find the polymer-rich phase to wet a hard wall. The wetting transition is of the

P. Tricarico, N. C. Hearn, G. Lake, G. Worthey

Asteroids can be eclipsed by other bodies in the Solar System, but no direct observation of an asteroid eclipse has been reported to date. We describe a statistical method to predict an eclipse for an asteroid based on the analysis of the orbital elements covariance matrix. By propagating a set of Virtual Asteroids to an epoch correspondent to a close approa

L. H. Li, S. Sofia, G. Belvedere

A magnetic flux tube may be considered both as a separate body and as a confined field. As a field, it is affected both by differential rotation ($Ω$-effect) and cyclonic convection ($α$-effect). As a body, the tube experiences not only a buoyant force, but also a dynamic pressure due to downflows above the tube. These two competing dynamic effects are incor

G. T. van Belle, D. R. Ciardi, T. ten Brummelaar, H. A. McAlister

We present observations of the A7IV-V star Alderamin ($α$ Cep, HR 8162, HD 203280) from the Georgia State University CHARA Array. These infrared interferometric angular size measurements indicate a non-circular projected disk brightness distribution for this known rapid rotator. The interferometric observations are modeled as arising from an elongated rigid

Yongzhong Xu, Philipp P. Kronberg, Salman Habib, Quentin W. Dufton

Faraday rotation of radio source polarization provides a measure of the integrated magnetic field along the observational lines of sight. We compare a new, large sample of Faraday rotation measures (RMs) of polarized extragalactic sources with galaxy counts in Hercules and Perseus-Pisces, two nearby superclusters. We find that the average of RMs in these two

M. Krips, A. Eckart, R. Neri, R. Schoedel

We present new interferometric observations of the continuum emission at mm wavelengths in the Seyfert galaxies NGC1068 and NGC3147. Three mm continuum peaks are detected in NGC1068, one centered on the core, one associated with the jet and the third one with the counter-jet. This is the first significant detection of the radio jet and counter-jet at mm wave

Eugenia Diaz, Hernan Muriel

We analyse a subsample of the galaxy groups obtained by Merchán & Zandivarez (2005) from the SDSS DR3 to study the fundamental plane and the mass to light ratio of galaxy groups. We find a fundamental plane given by $L_R \propto R^{1.3} σ^{0.7}$. We do not find differences when different dynamical sates or redshift ranges are analysed. We find that the mass

F. Camilo, S. M. Ransom, B. M. Gaensler, P. O. Slane

We have discovered the pulsar associated with the supernova remnant G21.5-0.9. PSR J1833-1034, with spin period P = 61.8 ms and dispersion measure 169 pc/cc, is very faint, with pulse-averaged flux density of approximately 70 microJy at a frequency of 1.4 GHz, and was first detected in a deep search with the Parkes telescope. Subsequent observations with Par

John T. Stocke, Steven V. Penton, Charles W Danforth, J. Michael Shull

We combine a FUSE sample of OVI absorbers (z < 0.15) with a database of 1.07 million galaxy redshifts to explore the relationship between absorbers and galaxy environments. All 37 absorbers with N(OVI) > 10^{13.2} cm^-2 lie within 800 h_70^-1 kpc of the nearest galaxy, with no compelling evidence for OVI absorbers in voids. The OVI absorbers often appear to

Antoinette Songaila

Using the extremely high S/N quasar absorption-line sample described in the first paper of the series, we investigate which intergalactic CIV absorption line systems could be directly associated with galactic outflows at z = 2 - 3.5 from an analysis of the velocity widths of the CIV absorption line systems. Only about half the systems with a peak tau(CIV) ab

M. T. Geske, S. J. Gettel, T. A. McKay

Contact binary stars are common variable stars which are all believed to emit relatively large fluxes of x-rays. In this work we combine a large new sample of contact binary stars derived from the ROTSE-I telescope with x-ray data from the ROSAT All-Sky Survey (RASS) to estimate the x-ray volume emissivity of contact binary stars in the galaxy. We obtained x

S. J. Gettel, M. T. Geske, T. A. McKay

In this work we describe a large new sample of contact binary stars extracted in a uniform manner from sky patrol data taken by the ROTSE-I telescope. Extensive ROTSE-I light curve data is combined with J, H, and K band near-infrared data taken from the Two Micron All-Sky Survey (2MASS) to add color information. Contact binaries candidates are selected using

J. Swift, Wm. J. Welch, J. Di Francesco, I. Stojimirovic

Both analytic and numerical radiative transfer models applied to high spectral resolution CS and N2H+ data give insight into the evolutionary state of L1551 MC. This recently discovered pre-protostellar core in L1551 appears to be in the early stages of dynamical evolution. Line-of-sight infall velocities of >0.1km/s are needed in the outer regions of L1551

Sabatino Sofia, Sarbani Basu, Pierre Demarque, Linghuai Li

We show in this paper that the changes of the solar diameter in response to variations of large scale magnetic fields and turbulence are not homologous. For the best current model, the variation at the photospheric level is over 1000 times larger than the variation at a depth of 5 Mm, which is about the level at which f-mode solar oscillations determine diam

R. A. Osten, T. S. Bastian

We report high-time-resolution, broadband spectroscopic observations of two radio bursts on the classical flare star AD Leonis. The observations were acquired by the 305 m telescope at Arecibo Observatory on 2003 June 13-14. Using the Wideband Arecibo Pulsar Processor, these observations sampled a total bandwidth of 400 MHz, distributed over a 500 MHz freque

C. Allende Prieto, T. C. Beers, R. Wilhelm, H. J. Newberg

(Abridged) We perform an analysis of spectra and photometry for 22,770 stars included in the third data release (DR3) of the SDSS. We measure radial velocities and, based on a model-atmosphere analysis, derive estimates ofthe atmospheric parameters (effective temperature, surface gravity, and [Fe/H]) for each star. Stellar evolution models are then used to e

Kimberly A. Herrmann, Robin Ciardullo

When astronomers study the dark matter halos of spiral galaxies, they normally assume that the disk mass-to-light ratio is *constant*. We describe a method of analyzing the kinematics of planetary nebulae (PNe) in nearby face-on spiral galaxies to test this assumption. Since the restoring force for stellar motions perpendicular to the galactic disk is propor

I. A. Bonnell, C. L. Dobbs, T. R. Robitaille, J. E. Pringle

We present numerical simulations of the passage of clumpy gas through a galactic spiral shock and the subsequent formation of giant molecular clouds (GMCs). The spiral shock forms dense clouds while dissipating kinetic energy, producing regions that are locally gravitationally bound and collapse to form stars. The effect of the clumpiness of gas as it passes

Julien Siebert

The self-gravitating systems are formed by particles interacting through gravity. They describe structure formation in the universe. As a consequence of the long range interaction of gravity, they are inhomogeneous even at thermal equilibrium. We study the self-gravitating systems with several kinds of particles and the self-gravitating systems in the presen

E. E. Kholupenko, A. V. Ivanchik, D. A. Varshalovich

CMBR distortion concerned with recombination of the primordial plasma is calculated in frequency band from 1 GHz to 100 GHz in the frame of the standard cosmological model for different values of cosmological density parameters: nonrelativistic matter density $Ω_m$ and baryonic matter density $Ω_b$. Comparison of these results with observational data which w

C. Bonatto, J. F. C. Santos Jr. E. Bica

We use 2MASS photometry to study colour-magnitude and colour-colour diagrams, structure and mass distribution in the ionizing open cluster NGC\,6611. Reddening variation throughout the cluster region is taken into account followed by field-star decontamination of the CMDs. The field-star decontamination showed that the lower limit of the main sequence (MS) o

C. Bonatto, L. O. Kerber, E. Bica, B. X. Santiago

We use the open clusters (OCs) with known parameters available in the WEBDA database and in recently published papers to derive properties related to the disk structure. The sample totals 654 OCs, consisting basically of Trumpler types I to III clusters. Because of the completeness effects, the observed radial distribution of OCs with respect to Galactocentr

R. Napiwotzki, G. Tovmassian, M. G. Richer, G. Stasinska

PN G135.9+55.9 is the most metal-poor PN known in our Galaxy. The central star resides in a short-period binary system with a compact component, probably a white dwarf. We describe new observations, which allowed us to determine the orbital period. The lower limit for the combined mass of both stars is close to the Chandrasekhar limit for white dwarfs, makin

Yurij Baryshev

The physics of the expansion of the universe is still a poorly studied subject of the standard cosmological model. This because the concept of expanding space can not be tested in the laboratory and because ``expansion&#39;&#39; means continuous creation of space, something that leads to several paradoxes. We re-consider and expand here the discussion of con

Steen H. Hansen, Ben Moore, Joachim Stadel

One can solve the Jeans equation analytically for equilibrated dark matter structures, once given two pieces of input from numerical simulations. These inputs are 1) a connection between phase-space density and radius, and 2) a connection between velocity anisotropy and density slope, the α-βrelation. The first (phase-space density v.s. radius) has been anal

G. Chabrier, I. Baraffe, F. Allard, P. H. Hauschildt

In this review, we examine the successes and weaknesses of modern low-mass star and brown dwarf theory.(1) We first focus on the mechanical (equation of state) and thermal (atmosphere) properties and on the evolution. We then examine the current shortcomings of the theory and we discuss recent observational analysis which have suggested discrepancies between

P. Pietrukowicz, J. Kaluzny, I. B. Thompson, M. Jaroszynski

We report the identification of a new cataclysmic variable (denoted as CV2) and a probable microlensing event in the field of the globular cluster M22. Two outbursts were observed for CV2. During one of them superhumps with P_sh=0.08875 d were present in the light curve. CV2 has an X-ray counterpart detected by XMM-Newton. A very likely microlensing event at

P. Mucciarelli, P. Casella, T. Belloni, L. Zampieri

We report results from a spectral and timing analysis of M82 X-1, one of the brightest known ultraluminous X-ray sources. Data from a new 105 ks {\it XMM-Newton} observation of M82 X-1, performed in April 2004, and of archival {\it RossiXTE} observations are presented. A very soft thermal component is present in the {\it XMM} spectrum. Although it is not pos

H. Bouy, E. Moraux, J. Bouvier, W. Brandner

We present the results of a high-resolution imaging survey for brown dwarf binaries in the Pleiades open cluster. The observations were carried out with the Advance Camera for Surveys onboard the Hubble Space Telescope. Our sample consists of 15 bona-fide brown dwarfs. We confirm 2 binaries and detect their orbital motion, but we did not resolve any new bina

Alexei Y. Kniazev, Eva K. Grebel, Daniel B. Zucker, Eric F. Bell

We present the latest results from our project to search for new planetary nebulae in nearby galaxies using Sloan Digital Sky Survey (SDSS) imaging data. Our method is based on photometric criteria and can be applied to galaxies where PNe appear as point sources. We applied these criteria to the whole area of M31 as scanned by SDSS, detecting 130 new PN cand

Misao Sasaki

We consider general, non-linear curvature perturbations on scales greater than the Hubble horizon scale by invoking an expansion in spatial gradients, the so-called gradient expansion. After reviewing the basic properties of the gradient expansion, we derive the conservation law for non-linear curvature perturbations for an isentropic fluid. We also define t

B. L. Ziegler, A. Böhm, A. Fritz

Faber-Jackson and Tully-Fisher scaling relations for elliptical and spiral galaxy samples up to z=1 provide evidence for a differential behaviour of galaxy evolution with mass. In compliance with the downsizing scenario, the stellar populations of less massive galaxies display a stronger evolution than the more massive ones. For spirals, this may be attribut

Christopher W. Mauche

EUVE observed the SU UMa-type dwarf nova VW Hydri in superoutburst for an interval of nearly 2 days in 1994 June and produced EUV light curves and the first EUV spectrum of this important CV.

Zong-Kuan Guo, Yuan-Zhong Zhang

We investigate observational constraints on the variable Chaplygin gas model from the gold sample of type Ia supernova data and the recent measurements of the X-ray gas mass fractions in galaxy clusters. Combining these databases, we obtain a tight constraint on the two model parameters. Our results indicate that the original Chaplygin gas model is ruled out

S. Wanajo, K. Nomoto, N. Iwamoto, Y. Ishimaru

Recent spectroscopic studies have revealed the presence of numerous carbon-enhanced, metal-poor stars with [Fe/H] < -2.0 that exhibit strong enhancements of s-process elements. These stars are believed to be the result of a binary mass-transfer episode from a former asymptotic giant-branch (AGB) companion that underwent s-process nucleosynthesis. However, se

Takashi Hiramatsu, Kei Kotake, Hideaki Kudoh, Atsushi Taruya

We discuss the gravitational wave background (GWB) from a cosmological population of gamma-ray bursts (GRBs). Among various emission mechanisms for the gravitational waves (GWs), we pay a particular attention to the vast anisotropic neutrino emissions from the accretion disk around the black hole formed after the so-called failed supernova explosions. The pr

Steen H. Hansen, Ben Moore

We identify a universal relation between the radial density slope α(r) and the velocity anisotropy β(r) for equilibrated structures. This relation holds for a variety of systems, including disk galaxy mergers, spherical collapses, cold dark matter (CDM) halos both with and without cooling. We argue that the shape of the relation is reasonable from fundamenta

F. M. Jiménez-Esteban, L. Agudo-Mérida, D. Engels, P. García-Lario

In this paper we present optical and near-infrared finding charts, accurate astrometry (~1&#34;) and single-epoch near-infrared photometry for 371 IRAS sources, 96% of those included in the so-called Arecibo sample of OH/IR stars (Eder et al. 1988; Lewis et al. 1990a; Chengalur et al. 1993). The main photometric properties of the stars in the sample are pres

Ahmad Idilbi, Xiangdong Ji, Jian-Ping Ma, Feng Yuan

We present an effective field theory to resum the large double logarithms originated from soft-gluon radiations at small final-state hadron invariant masses in Higgs and vector boson (γ^*, $W$ and $Z$) production at hadron colliders. The approach is conceptually simple, indepaendent of details of an effective field theory formulation, and valid to all orders

Colin Benjamin

The coexistence of superconductivity and ferromagnetism has brought about the phenomena of ferromagnetic superconductors. The theory needed to understand the compatibility of such antagonistic phenomena cannot be built until the pairing symmetry of such superconductors is correctly identified. The proper and unambiguous identification of the pairing symmetry

Daniel Babich, Abraham Loeb

We consider the effects of inhomogeneous reionization on the distribution of galaxies at high redshifts. Modulation of the formation process of the ionizing sources by large scale density modes makes reionization inhomogeneous and introduces a spread to the reionization times of different regions with the same size. After sources photo-ionize and heat these

M. Hutzenthaler, A. Wakolbinger

For a class of processes modeling the evolution of a spatially structured population with migration and a logistic local regulation of the reproduction dynamics, we show convergence to an upper invariant measure from a suitable class of initial distributions. It follows from recent work of Alison Etheridge that this upper invariant measure is nontrivial for

Tolga Etgü, Burak Ozbagci

We describe explicit open books on arbitrary plumbings of oriented circle bundles over closed oriented surfaces. We show that, for a non-positive plumbing, the open book we construct is horizontal and the corresponding compatible contact structure is also horizontal and Stein fillable. In particular, we describe horizontal open books on some Seifert fibered