August 2005 arXiv papers — page 2

P. Carta, E. Gozzi, D. Mauro

In this paper we present the Koopman-von Neumann (KvN) formulation of classical non-Abelian gauge field theories. In particular we shall explore the functional (or classical path integral) counterpart of the KvN method. In the quantum path integral quantization of Yang-Mills theories concepts like gauge-fixing and Faddeev-Popov determinant appear in a quite

Pascal Grange

This thesis is devoted to derivative corrections to the effective action of D-branes, and to mirror symmetry with D-branes. Series of derivative corrections first predicted by non-commutative gauge theory are completed by couplings between the metric and the gauge field. The result is interpreted as a deformation of the non-commutative gauge theory, whose st

Pietro Menotti, Erik Tonni

We develop a perturbative expansion of quantum Liouville theory on the pseudosphere around the background generated by heavy charges. Explicit results are presented for the one and two point functions corresponding to the summation of infinite classes of standard perturbative graphs. The results are compared to the one point function and to a special case of

J. Kluson

This paper is devoted to the study of the tachyon kink on the worldvolume of a non-BPS Dp-brane that is embedded in general background, including NS-NS two form B and also general Ramond-Ramond field. We will explicitly show that the dynamics of the kink is described by the equations of motion that arrise from the DBI and WZ action for D(p-1)-brane.

Hui Liu, Defu Hou, Jiarong Li

The shear viscosity of QED plasma at finite temperature and density is calculated by solving Boltzmann equation with variational approach. The result shows the small chemical potential enhances the viscosity in leading-log order by adding a chemical potential quadratic term to the viscosity for the pure temperature environment.

Leonardo Castellani

Free differential algebras (FDA's) provide an algebraic setting for field theories with antisymmetric tensors. The "presentation" of FDA's generalizes the Cartan-Maurer equations of ordinary Lie algebras, by incorporating p-form potentials. An extended Lie derivative along antisymmetric tensor fields can be defined, and used to recover a Lie

H. Castillo, C. A. Dominguez, M. Loewe

We obtain the electromagnetic form factors of the nucleon, in the space-like region, using three-point function Finite Energy QCD Sum Rules. The QCD calculation is performed to leading order in perturbation theory in the chiral limit, and also to leading order in the non-perturbative power corrections. For the Dirac form factor, $F_1(q^2)$, we get a very goo

B. F. L. Ward, S. A. Yost

We present the elements of QEDXQCD exponentiation and its interplay with shower/ME matching in precision LHC physics scenarios. Applications to single heavy gauge boson production at hadron colliders are illustrated.

Jean-Paul Blaizot, Andreas Ipp, Anton Rebhan

At finite temperature and chemical potential, the leading-order (hard-thermal-loop) contributions to the gauge-boson propagator lead to momentum-dependent thermal masses for propagating quasiparticles as well as dynamical screening and Landau damping effects. We compare the hard-thermal-loop propagator with the complete large-N_f gluon propagator, for which

Ralf Lehnert

Cosmological models often contain scalar fields, which can acquire global nonzero expectation values that change with the comoving time. Among the possible consequences of these scalar-field backgrounds, an accelerated cosmological expansion, varying couplings, and spacetime-symmetry violations have recently received considerable attention. This talk studies

T. Gleisberg, S. Hoeche, F. Krauss, A. Schaelicke

In this contribution the new event generation framework Sherpa will be presented. It aims at the full simulation of events at current and future high-energy experiments, in particular the LHC. Some results related to the production of jets at the Tevatron will be discussed.

G. Moortgat-Pick, S. Hesselbach, F. Franke, H. Fraas

The interplay between the LHC and the $e^+ e^-$ International Linear Collider (ILC) with $\sqrt{s}=500$ GeV might be crucial for the discrimination between the minimal and next-to-minimal supersymmetric standard model. We present an NMSSM scenario, where the light neutralinos have a significant singlino component, that cannot be distinguished from the MSSM b

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

We analyze the dependence of heavy quark free energies on the baryon chemical potential (mu_b) in 2-flavour QCD using improved (p4) staggered fermions with a bare quark mass of m/T = 0.4. By performing a 6th order Taylor expansion in the chemical potential which circumvents the sign problem. The Taylor expansion coefficients of colour singlet and colour aver

Rajamani Narayanan, Herbert Neuberger

A brief overview of the authors' work on lattice chirality and its application to the numerical study of planar QCD is presented.

S. Shcheredin, W. Bietenholz

We apply different types of overlap operators in quenched QCD simulations to compute the zero mode contribution to the pseudo-scalar correlator. In particular we use the conventional Neuberger Dirac operator and the overlap hypercube Dirac operator. Confronting our data with the analytical predictions by Chiral Perturbation Theory we evaluate the pion decay

Xiao-Lu Yu, Xiang-Qian Luo

We perform the first study of lattice QCD with overlap fermions at finite temperature $T$ and chemical potential $μ$. We start from the Taylor expanded overlap fermion action, and derive in the strong coupling limit the effective free energy by mean field approximation. On the ($μ,T$) plane and in the chiral limit, there is a tricritical point, separating th

The Belle Collaboration, K. Abe

We report results on studies of CP violation in the three-body charmless decay B+- => K+-pi+-pi-+. Evidence at the 3.9sigma level for large direct CP violation in B+- => rho(770)0K+-$ is found. This is the first evidence for CP violation in a charged meson decay. The analysis is performed using Dalitz analysis technique with a data sample that contains 386 m

The OPAL Collaboration, G. Abbiendi

The effects of the final state interaction phenomenon known as colour reconnection are investigated at centre-of-mass energies in the range sqrt(s) ~ 189-209 GeV using the OPAL detector at LEP. Colour reconnection is expected to affect observables based on charged particles in hadronic decays of W+W-. Measurements of inclusive charged particle multiplicities

F. Hubaut, E. Monnier, P. Pralavorio, V. Simak

Stringent tests on top quark production and decay mechanisms are provided by the measurement of the top quark and W boson polarization. This paper presents a detailed study of these two measurements with the ATLAS detector, in the semileptonic (ttbar -> W W b bbar -> l nu j1 j2 b bbar) and dileptonic (ttbar -> W W b bbar -> l nu l nu b bbar) ttbar channels.

The OPAL Collaboration, G. Abbiendi

The mass and width of the W boson are measured using e+e- -> W+W- events from the data sample collected by the OPAL experiment at LEP at centre-of-mass energies between 170 GeV and 209 GeV. The mass (mw) and width (gw) are determined using direct reconstruction of the kinematics of W+W- -> qqbarlv and W+W- -> qqbarqqbar events. When combined with previous OP

Alex Harvey, Engelbert L. Schucking, Eugene J. Surowitz

Courses in introductory special and general relativity have increasingly become part of the curriculum for upper-level undergraduate physics majors and master's degree candidates. One of the topics rarely discussed is symmetry, particularly in the theory of general relativity. The principal tool for its study is the Killing vector. We provide an elementa

Zsolt I. Lázár, Lehel István Kovács, Bazil Pârv

The COmputational MODule Integrator (COMODI) is an initiative aiming at a component based framework, component developer tool and component repository for scientific computing. We identify the main ingredients to a solution that would be sufficiently appealing to scientists and engineers to consider alternatives to their deeply rooted programming traditions.

Zsolt I. Lázár, Jouke R. Heringa, Bazil Pârv, Simon W. de Leeuw

Computational scientists are facing a new era where the old ways of developing and reusing code have to be left behind and a few daring steps are to be made towards new horizons. The present work analyzes the needs that drive this change, the factors that contribute to the inertia of the community and slow the transition, the status and perspective of presen

X. Wu, R. Srikant

In this paper, we complement Verdú's work on spectral efficiency in the wideband regime by investigating the fundamental tradeoff between rate and bandwidth when a constraint is imposed on the error exponent. Specifically, we consider both AWGN and Rayleigh-fading channels. For the AWGN channel model, the optimal values of $R_z(0)$ and $\dot{R_z}(0)$ are

Tran Cao Son, Enrico Pontelli

We present a declarative language, PP, for the high-level specification of preferences between possible solutions (or trajectories) of a planning problem. This novel language allows users to elegantly express non-trivial, multi-dimensional preferences and priorities over such preferences. The semantics of PP allows the identification of most preferred trajec

V. Gontis, B. Kaulakys, J. Ruseckas

We present a simple model reproducing the long-range autocorrelations and the power spectrum of the web traffic. The model assumes the traffic as Poisson flow of files with size distributed according to the power-law. In this model the long-range autocorrelations are independent of the network properties as well as of inter-packet time distribution.

Mary Baker, Mehul Shah, David S. H. Rosenthal, Mema Roussopoulos

Many emerging Web services, such as email, photo sharing, and web site archives, need to preserve large amounts of quickly-accessible data indefinitely into the future. In this paper, we make the case that these applications' demands on large scale storage systems over long time horizons require us to re-evaluate traditional storage system designs. We ex

Ali Naji, Christian Seidel, Roland R. Netz

Neutral or charged polymers that are densely end-grafted to surfaces form brush-like structures and are highly stretched under good-solvent conditions. We discuss and compare relevant results from scaling models, self-consistent-field methods and MD simulation techniques and concentrate on the conceptual simple case of planar substrates. For neutral polymers

Christopher L. Henley

The (three-dimensional) pyrochlore lattice antiferromagnet with Heisenberg spins of large spin length $S$ is a highly frustrated model with an macroscopic degeneracy of classical ground states. The zero-point energy of (harmonic order) spin wave fluctuations distinguishes a subset of these states. I derive an approximate but illuminating {\it effective Hamil

M. R . Ghadimi, B. Beschoten, G. Güntherodt

We have studied the influence of non-magnetic defects throughout the antiferromagnet Co_{1-y}O on the exchange bias (EB) in epitaxially grown Co_{1-y}O/Co bilayers. These defects are either substitutional or structural (twin boundaries and surface morphology) which both lead to an increase of the EB-field. We find a dominance of twin boundaries over surface

Stefan Hollos, Richard Hollos

We derive formulas for the matrix elements of the lattice Green function for the discrete Poisson equation on an infinite square lattice. The partial difference equation for the matrix elements is solved by reducing it to a series of first order difference equations, which can then be solved sequentially. These formulas are useful in solving two dimensional

Sebastian Eggert, Ian Affleck

We consider the effect of doping on the magnetic order in quasi one-dimensional (1D) antiferromagnets. First the detailed magnetic response of finite spin-1/2 chains in the presence of a staggered field is determined, which by itself shows an interesting crossover as function of length and field strength. We can then understand the ordering by including an e

R. Y. Gu, V. P. Antropov

Using quantum Heisenberg model calculations with Green's function technique generalized for arbitrary spins, we found that for a system of small spins the quantum spin effects significantly contribute to the magnetic short-range order and strongly affect physical properties of magnets. The spin dynamics investigation confirms that these quantum spin effe

Christoph Sohrmann, Rudolf A. Roemer

Electron-electron interactions seem to play a surprisingly small role in the description of the integer quantum Hall effect, considering that for just slightly different filling factors the interactions are of utmost importance causing the interaction-mediated fractional quantum Hall effect. However, recent imaging experiments by Cobden et al. and Ilani et a

E. Goering, S. Gold, M. Lafkioti, G. Schuetz

We show detailed magnetic absorption spectroscopy results of an in situ cleaved high quality single crystal of magnetite. In addition the experimental setup was carefully optimized to reduce drift, self absorption, and offset phenomena as far as possible. In strong contradiction to recently published data, our observed orbital moments are nearly vanishing an

Y. Bason, L. Klein, J. -B. Yau, X. Hong

We suggest a new type of magnetic random access memory (MRAM) that is based on the phenomenon of the planar Hall effect (PHE) in magnetic films, and we demonstrate this idea with manganite films. The PHE-MRAM is structurally simpler than currently developed MRAM that is based on magnetoresistance tunnel junctions (MTJ), with the tunnel junction structure bei

Ali Naji, Roland R. Netz

We address the critical and universal aspects of counterion-condensation transition at a single charged cylinder in both two and three spatial dimensions using numerical and analytical methods. By introducing a novel Monte-Carlo sampling method in logarithmic radial scale, we are able to numerically simulate the critical limit of infinite system size (corres

J. Reinisch, A. Heuer

Though the existence of two-level systems (TLS) is widely accepted to explain low temperature anomalies in many physical observables, knowledge about their properties is very rare. For silica which is one of the prototype glass-forming systems we elucidate the properties of the TLS via computer simulations by applying a systematic search algorithm. We get sp

Ali Naji, Swetlana Jungblut, Andre G. Moreira, Roland R. Netz

Charged soft-matter systems--such as colloidal dispersions and charged polymers--are dominated by attractive forces between constituent like-charged particles when neutralizing counterions of high charge valency are introduced. Such counter-intuitive effects indicate strong electrostatic coupling between like-charged particles, which essentially results from

D. M. Zumbuhl, C. M. Marcus, M. P. Hanson, A. C. Gossard

The symmetry properties of transport beyond the linear regime in chaotic quantum dots are investigated experimentally. A component of differential conductance that is antisymmetric in both applied source-drain bias V and magnetic field B, absent in linear transport, is found to exhibit mesoscopic fluctuations around a zero average. Typical values of this com

K. W. Murch, K. L. Moore, S. Gupta, D. M. Stamper-Kurn

Specific velocities of particles circulating in a storage ring can lead to betatron resonances at which static perturbations of the particles' orbit yield large transverse (betatron) oscillations. We have observed betatron resonances in an ultracold-atom storage ring by direct observation of betatron motion. These resonances caused a near-elimination of

Ulrike Lueders, Agnes Barthelemy, Manuel Bibes, Karim Bouzehouane

Over the past few years, intensive studies of ultrathin epitaxial films of perovskite oxides have often revealed exciting properties like giant magnetoresistive tunnelling and electric field effects. Spinel oxides appear as even more versatile due to their more complex structure and the resulting many degrees of freedom. Here we show that the epitaxial growt

Chris I. Addison, Pierre-Arnaud Artola, Jean-Pierre Hansen, Ard A. Louis

The phase separation of a simple binary mixture of incompatible linear polymers in solution is investigated using an extension of the sedimentation equilibrium method, whereby the osmotic pressure of the mixture is extracted from the density profiles of the inhomogeneous mixture in a gravitational field. In Monte-Carlo simulations the field can be tuned to i

J. Barre', A. R. Bishop, T. Lookman, A. Saxena

We consider a dynamical generalization of the Eshelby problem: the strain profile due to an inclusion or "defect" in an isotropic elastic medium. We show that the higher the oscillation frequency of the defect, the more localized is the strain field around the defect. We then demonstrate that the qualitative nature of the interaction between two defe

J. Masek, F. Maca

We apply the density-functional technique to determine the lattice constant of GaAs supercells containing Mn_Ga, Mn_int, and As_Ga impurities, and use a linear interpolation to describe the dependence of the lattice constant a of Ga_{1-x}Mn_xAs on the concentrations of these impurities. The results of the supercell calculations confirm that Mn_Ga does not co

M. Sigrist, T. Ihn, K. Ensslin, D. Loss

Two quantum dots with tunable mutual tunnel coupling have been embedded in a two-terminal Aharonov-Bohm geometry. Aharonov-Bohm oscillations are investigated in the cotunneling regime. Visibilities of more than 0.8 are measured indicating that phase-coherent processes are involved in the elastic and inelastic cotunneling. An oscillation-phase change of pi is

P. N. Timonin

Thermodynamics of layered Ising magnet with the infinite-range ferromagnetic intralayer interaction and random exchange between nearest layers is considered. The case of zero average interlayer exchange is studied in detail. The inequilibrium thermodynamic potential is obtained near transition point and existence of numerous metastable states is shown. The t

G. Koren, P. Aronov, E. Polturak

Transport measurements along the node and anti-node directions in the a-b plane of optimally doped and epitaxial thin films of YBCO are reported. Low bias magnetoresistance measurements near and below T_c show that the flux flow resistivity along the node and anti-node directions versus magnetic field are indistinguishable. This result suggests that within t

P. Aronov, G. Koren

Magnetic properties of SFS and SF ramp-type junctions with $YBa_2Cu_3O_{7-δ}$ (YBCO) electrodes (S), and the itinerant ferromagnet $SrRuO_3$ (SRO - F), were investigated. We looked for a crossed Andreev reflection effect (CARE) in which an electron from one magnetic domain in F is Andreev reflected as a hole into an adjacent, oppositely polarized, domain whi

Dganit Meidan, Yuval Oreg

Recent experiments performed on weakly pinched quantum point contacts, have shown a resistance that tend to decrease at low source drain voltage. We show that enhanced Coulomb interactions, prompt by the presence of the point contact, may lead to anomalously large multiple-particle scattering at finite bias voltage. These processes tend to decrease at low vo

Y. Nohara, A. Yamasaki, S. Kobayashi, T. Fujiwara

The electronic structure of the A-type antiferromagnetic insulator LaMnO3 is investigated by the GW approximation. The band gap and spectrum are in a good agreement with experimental observation. The on-site/off-site dynamical screened Coulomb interaction on Mn sites is also calculated. Comparison with the results by the Hartree-Fock and the static COHSEX ap

S. Banerjee, N. K. Sinha, N. Gayathri, D. Ponraju

We report here that atomic force microscope (AFM) in frictional force mode can be used to detect onset of chain scission and crosslinking in polymeric and macromolecular samples upon irradiation. A systematic investigation to detect chain scission and crosslinking of two elastomers: (1) Ethylene-propylene-diene monomer rubber (EPDM) and (2) Fluorocarbon rubb

S. Y. Yoon, Byoung-sun Ahn, Yup Kim

We study the dynamics of visitation flux in a multi-random-walker model by comparison to surface growth dynamics in which one random walker drops a particle to a node at each time the walker visits the node. In each independent experiment (trial or day) for the multi-random-walker model, the number of walkers are randomly chosen from the uniform distribution

Mathieu Bouville, Shenyang Hu, Long-Qing Chen, Dongzhi Chi

Polycrystalline thin films can be unstable with respect to island formation (agglomeration) through grooving where grain boundaries intersect the free surface and/or thin film-substrate interface. We develop a phase-field model to study the evolution of the phases, composition, microstructure and morphology of such thin films. The phase-field model is quite

H. Youk, G. -W. Chern, K. Merit, B. Oppenheimer

We discuss the structure of the so-called "vortex" domain walls in soft magnetic nanoparticles. A wall of this kind is a composite object consisting of three elementary topological defects: two edge defects with winding numbers -1/2 and a vortex with a winding number +1 between them. We provide a qualitative model accounting for the energetics of suc

G. -W. Chern, H. Youk, O. Tchernyshyov

We discuss elementary topological defects in soft magnetic nanoparticles in the thin-film geometry. In the limit dominated by magnetostatic forces the low-energy defects are vortices (winding number n = +1), cross ties (n = -1), and edge defects with n = -1/2. We obtain topological constraints on the possible composition of domain walls. The simplest domain

A. V. Rozhkov

We find a unitary operator which asymptotically diagonalizes the Tomonaga-Luttinger hamiltonian of one-dimensional spinless electrons. The operator performs a Bogoliubov rotation in the space of electron-hole pairs. If bare interaction of the physical electrons is sufficiently small this transformation maps the original Tomonaga-Luttinger system on a system

Rosa A. Gonzalez-Lopezlira, Marna Y. Albarran, Mustapha Mouhcine, Michael C. Liu

This work continues our efforts to calibrate model surface brightness luminosities for the study of unresolved stellar populations, through the comparison with data of Magellanic Cloud star clusters. We present here the relation between absolute K_s-band fluctuation magnitude and (V - I) integrated colour, using data from the 2MASS and DENIS surveys, and fro

D. Wittman

Weak lensing observations have the potential to be even more powerful than cosmic microwave background (CMB) observations in constraining cosmological parameters. However, the practical limits to weak lensing observations are not known. Most theoretical studies of weak lensing constraints on cosmology assume that the only limits are shot noise on small scale

David V. Bowen, Edward B. Jenkins, Max Pettini, Todd M. Tripp

We have used the Space Telescope Imaging Spectrograph (STIS) aboard HST to measure a sulfur abundance of [S/H] = -0.41 +/-0.06 in the interstellar medium (ISM) of the nearby damped Lyman-alpha (DLA) absorbing galaxy SBS 1543+593. A direct comparison between this QSO absorption line abundance on the one hand, and abundances measured from HII region emission l

Banibrata Mukhopadhyay

Origin of hydrodynamic turbulence in rotating shear flow, e.g. plane Couette flow including the Coriolis force, is a big puzzle. While the flow often exhibits turbulence in laboratory experiments, according to the linear perturbation theory it should always be stable. We demonstrate that the secondary disturbance to the primarily perturbed flow triggers the

Roberto D. D. Costa, Andre V. Escudero, Walter J. Maciel

Electron temperatures, densities, ionic and elemental abundances of helium, nitrogen, oxygen, argon, sulfur and neon were derived for a sample of bulge planetary nebulae, representative of its intermediate mass population. Using these results as constraints, a model for the chemical evolution of the galactic bulge was developed. The results indicate that the

Miguel A. Perez-Torres, Carlos De Breuck, Wil van Breugel, George Miley

We report on first results of an ongoing effort to image a small sample of high-redshift radio galaxies (HzRGs) with milliarcsecond (mas) resolution, using very-long-baseline interferometry (VLBI) techniques. Here, we present 1.7 and 5.0 GHz VLBA observations of B3 J2330+3927, a radio galaxy at z=3.087. Those observations, combined with 8.4 GHz VLA-A observa

H. Socas-Navarro, J. Beckers, P. Brandt, J. Briggs

The site survey for the Advanced Technology Solar Telescope concluded recently after more than two years of data gathering and analysis. Six locations, including lake, island and continental sites, were thoroughly probed for image quality and sky brightness. The present paper describes the analysis methodology employed to determine the height stratification

H. Socas-Navarro

This paper presents an analysis of three-dimensional vector currents and temperatures observed in a sunspot from the photosphere to the chromosphere, spanning a range of heights of approximately 1500 km. With this unique dataset, based on novel spectro-polarimetric observations of the 850 nm spectral region, it is possible to conduct for the first time an em

H. Socas-Navarro

Here we report on observations of the three-dimensional structure of a sunspot magnetic field from the photosphere to the chromosphere, obtained with the new visible/infrared spectro-polarimeter SPINOR. The observations, interpreted with a non-LTE modeling technique, reveal a surprisingly complex topology with areas of opposite-sign torsion, suggesting that

Magda Arnaboldi

Cosmological simulations of structure formation predict that galaxies are dramatically modified by galaxy harassment during the assembly of galaxy clusters, losing a substantial fraction of their stellar mass which today must be in the form of intracluster stars. Simulations predict non-uniform spatial and radial velocity distributions for these stars. Intra

D. Gouliermis, W. Brandner, Th. Henning

We present V- and I-equivalent HST/WFPC2 stellar photometry of an area in the Large Magellanic Cloud (LMC), located on the western edge of the bar of the galaxy, which accounts for the general background field of its inner disk. The WFPC2 observations reach magnitudes as faint as V=25 mag, and the large sample of more than 80,000 stars allows us to determine

H. Socas-Navarro, D. Elmore, A. Pietarila, A. Darnell

SPINOR is a new spectro-polarimeter that will serve as a facility instrument for the Dunn Solar Telescope at the National Solar Observatory. This instrument is capable of achromatic polarimetry over a very broad range of wavelengths, from 430 up to 1600 nm, allowing for the simultaneous observation of several visible and infrared spectral regions with full S

Barbara Ercolano

The study of photoionised gas in planetary nebulae (PNe) has played a major role in the achievement, over the years, of a better understanding of a number of physical processes, pertinent to a broader range of fields than that of PNe studies, spanning from atomic physics to stellar evolution theories. Whilst empirical techniques are routinely employed for th

Jean-Luc Sauvageot, Elena Belsole, Gabriel W. Pratt

We present a mosaic of five XMM-Newton observations of the nearby ($z=0.0594$) merging galaxy cluster Abell 3266. We use the spectro-imaging capabilities of \xmm to build precise (projected) temperature, entropy, pressure and Fe abundance maps. The temperature map exhibits a curved, large-scale hot region, associated with elevated entropy levels, very simila

Kevin Krisciunas, Peter M. Garnavich, Peter Challis, Jose Luis Prieto

We present broad-band light curves of nine supernovae ranging in redshift from 0.5 to 0.8. The supernovae were discovered as part of the ESSENCE project, and the light curves are a combination of Cerro Tololo 4-m and Hubble Space Telescope (HST) photometry. On the basis of spectra and/or light-curve fitting, eight of these objects are definitely Type Ia supe

Patricia B. Tissera, Maria E. De Rossi, C. Scannapieco

We study the mass-metallicity relation of galactic systems with stellar masses larger than 10^9 Mo in Lambda-CDM scenarios by using chemical hydrodynamical simulations. We find that this relation arises naturally as a consequence of the formation of the structure in a hierarchical scenario. The hierarchical building up of the structure determines a character

E. Rosolowsky

We reanalyze the catalogs of molecular clouds in the Local Group to determine the parameters of their mass distributions in a uniform manner. The analysis uses the error-in-variables method of parameter estimation which accounts not only for the variance of the sample when drawn from a parent distribution but also for errors in the mass measurements. Testing

M. Livio, J. E. Pringle, K. Wood

We predict the existence of dusty disks and possibly CO planets around massive white dwarfs. We show that the thermal emission from these disks should be detectable in the infrared. The planets may also be detectable either by direct IR imaging, spectroscopy, or using the pulsations of the white dwarfs.

Marcelo Mora, Soeren S. Larsen, Markus Kissler-Patig

We determined ages for 52 star clusters with masses < 10^6 solar masses in the low surface brightness spiral galaxy NGC 45. Four of these candidates are old globular clusters located in the bulge. The remaining ones span a large age range. The cluster ages suggest a continuous star/cluster formation history without evidence for bursts, consistent with the ga

Claude Mercier, Prasad Subramanian, Alain Kerdraon, Monique Pick

We report first results from an ongoing program of combining visibilities from the Giant Meterwave Radio Telescope (GMRT) and the Nancay Radio Heliograph (NRH) to produce composite snapshot images of the sun at meter wavelengths. We describe the data processing, including a specific multi-scale CLEAN algorithm. We present results of a) simulations for two mo

V. Aynutdinov

We present the results of a search for high energy extraterrestrial neutrinos with the Baikal underwater Cherenkov detector NT200, based on data taken in 1998 - 2002. Upper limits on the diffuse fluxes of $ν_e+ν_μ+ν_τ$, predicted by several models of AGN-like neutrino sources, are derived. For an $E^{-2}$ behavior of the neutrino spectrum, our limit is $E^2

P. Ferrando, A. Goldwurm, P. Laurent, O. Limousin

SIMBOL-X is a hard X-ray mission, operating in the ~ 0.5-70 keV range, which is proposed by a consortium of European laboratories in response to the 2004 call for ideas of CNES for a scientific mission to be flown on a formation flying demonstrator. Relying on two spacecrafts in a formation flying configuration, SIMBOL-X uses for the first time a ~ 30 m foca

Z. Bagoly, I. Horvath, A. Meszaros, L. G. Balazs

The gamma-ray burst&#39;s lightcurves have been analyzed using a special wavelet transformation. The applied wavelet base is based on a typical Fast Rise-Exponential Decay (FRED) pulse. The shape of the wavelet coefficients&#39; total distribution is determined on the observational frequency grid. Our analysis indicates that the pulses in the long bursts&#39

Chanda J. Jog

We study the vertical density distribution of stars and gas (HI and H_2) in a galactic disk which is embedded in a dark matter halo. The new feature of this work is the inclusion of gas, and the gravitational coupling between stars and gas, which has led to a more realistic treatment of a multi-component galactic disk. The gas gravity is shown to be cruciall

Sebastien Fromang, Caroline Terquem, Richard P. Nelson

Using 2D MHD numerical simulations performed with two different finite difference Eulerian codes, we analyze the effect that a toroidal magnetic field has on low mass planet migration in nonturbulent protoplanetary discs. The presence of the magnetic field modifies the waves that can propagate in the disc. In agreement with a recent linear analysis (Terquem

Áron Süli, Rudolf Dvorak, Florian Freistetter

Although the long-term numerical integrations of planetary orbits indicate that our planetary system is dynamically stable at least +/- Gyr, the dynamics of our Solar System includes both chaotic and stable motions: the large planets exhibit remarkable stability on gigayear timescales, while the subsystem of the terrestrial planets is weekly chaotic with a m

F. X. Hu, G. X. Wu, G. X. Song, Q. R. Yuan

The progress of the studies on the orientation of galaxies in the Local Supercluster (LSC) is reviewed and a summary of recent results is given. Following a brief introduction of the LSC, we describe the results of early studies based on two-dimensional analysis, which were mostly not conclusive. We describe next the three-dimensional analysis, which is used

H. Socas-Navarro, V. Martinez Pillet, D. Elmore, A. Pietarila

Ellerman bombs are bright emission features observed in the wings of H$α$, usually in the vicinity of magnetic concentrations. Here we show that they can also be detected in the Ca II infrared triplet lines, which are easier to interpret and therefore allow for more detailed diagnostics. We present full Stokes observations of the 849.8 and 854.2 nm lines acq

Peter M. Frinchaboy, Steven R. Majewski

The dark matter distribution of the Milky Way remains among the major unsolved problems about our home galaxy. The masses of other spiral galaxies can be determined from their rotation curves through long-slit spectroscopy. But for the Milky Way obtaining the complete rotation curve is a more complex problem. By measuring the 3-dimensional motions of tracer

Charles W. Danforth, J. Michael Shull, Jessica L. Rosenberg, John T. Stocke

We present the results of a large survey of HI, OVI, and CIII absorption lines in the low-redshift (z<0.3) intergalactic medium (IGM). We begin with 171 strong Lyalpha absorption lines (W>80 mA) in 31 AGN sight lines studied with the Hubble Space Telescope and measure corresponding absorption from higher-order Lyman lines with FUSE. Higher-order Lyman lines

C. Y. Hui, W. Becker

Based on observations with the X-ray observatories Chandra and XMM-Newton we present results from a detailed spectro-imaging and timing analysis of the central compact X-ray source RX J0822-4300 in the supernova remnant Puppis-A. The superior angular resolution of Chandra allows for the first time to pinpoint the point source nature of this object down to $0

S. Pramanik, C-G. Stefanita, S. Bandyopadhyay, K. Garre

We report spin valve behavior in an organic nanowire consisting of three layers - cobalt, Alq3 and nickel - all nominally 50 nm in diameter. Based on the data, we conclude that the dominant spin relaxation mechanism in Alq3 is the Elliott-Yafet mode. Despite the very short momentum relaxation time, the spin relaxation time is found to be very long - at least

Luca Mazzucato

We study the effective superpotential of N=1 supersymmetric gauge theories with a mass gap, whose analytic properties are encoded in an algebraic curve. We propose that the degree of the curve equals the number of semiclassical branches of the gauge theory. This is true for supersymmetric QCD with one adjoint and polynomial superpotential, where the two shee

Juna A. Kollmeier, Christopher A. Onken, Christopher S. Kochanek, Andrew Gould

We study the distribution of Eddington luminosity ratios, L_bol/L_edd, of active galactic nuclei (AGNs) discovered in the AGN and Galaxy Evolution Survey (AGES). We combine H-beta, MgII, and CIV line widths with continuum luminosities to estimate black hole (BH) masses in 407 AGNs, covering the redshift range z~0.3-4 and the bolometric luminosity range L_bol

M. L. Ladrón de Guevara, P. A. Orellana

The electronic transport through a triple quantum dot molecule attached in parallel to leads in presence of a magnetic flux is studied. Analytical expressions of the linear conductance and density of states for the molecule in equilibrium at zero temperature are obtained. As a consequence of quantum interference, the conductance exhibits in general a Breit--

Nelia Mann, Joe Polchinski

We study an integrable conformal OSp(2m + 2|2m) supercoset model as an analog to the AdS_5 X S^5 superstring world-sheet theory. Using the known S-matrix for this system, we obtain integral equations for states of large particle density in an SU(2) sector, which are exact in the sigma model coupling constant. As a check, we derive as a limit the general clas

Joshua J. Friess, Steven S. Gubser, Indrajit Mitra

We demonstrate explicit counter-examples to the Correlated Stability Conjecture (CSC), which claims that the horizon of a black brane is unstable precisely if that horizon has a thermodynamic instability, meaning that its matrix of susceptibilities has a negative eigenvalue. These examples involve phase transitions near the horizon. Ways to restrict or revis

Shahrokh Parvizi, Alireza Tavanfar

In the interesting conjecture, Z_{BH} = |Z_{top}|^2, proposed by Ooguri, Strominger and Vafa (OSV), the black hole ensemble is a mixed ensemble and the resulting degeneracy of states, as obtained from the ensemble inverse-Laplace integration, suffers from prefactors which do not respect the electric-magnetic duality. One idea to overcome this deficiency, as

G. E. Volovik

In the geometry of the circular hydraulic jump, the velocity of the liquid in the interior region exceeds the speed of capillary-gravity waves (ripplons), whose spectrum is `relativistic&#39; in the shallow water limit. The velocity flow is radial and outward, and thus the relativistic ripplons cannot propagating into the interior region. In terms of the eff

L. Campanelli, M. Giannotti

The coupling between a primordial magnetic field and the cosmic axion field generates a helical component of the magnetic field around the time in which the axion starts to oscillate. If the energy density of the seed magnetic field is comparable to the energy density of the universe at that time, then the resulting magnetic helicity is about |H_B| \simeq (1

Attilio Cucchieri, Tereza Mendes, Antonio Mihara

We perform a numerical study of ghost condensation -- in the so-called Overhauser channel -- for SU(2) lattice gauge theory in minimal Landau gauge. The off-diagonal components of the momentum-space ghost propagator G^{cd}(p) are evaluated for lattice volumes V = 8^4, 12^4, 16^4, 20^4, 24^4 and for three values of the lattice coupling: β= 2.2, 2.3, 2.4. Our

Carlo Rovelli

We study the graviton propagator in euclidean loop quantum gravity, using the spinfoam formalism. We use boundary-amplitude and group-field-theory techniques, and compute one component of the propagator to first order, under a number of approximations, obtaining the correct spacetime dependence. In the large distance limit, the only term of the vertex amplit

Diego Chialva, Gary Shiu, Bret Underwood

We investigate in some quantitative details the viability of reheating in multi-throat brane inflationary scenarios by estimating and comparing the time scales for the various processes involved. We also calculate within perturbative string theory the decay rate of excited closed strings into KK modes and compare with that of their decay into gravitons; we f