September 2005 arXiv papers — page 6

Giancarlo Rossi, Roberto Frezzotti, Guido Martinelli, Mauro Papinutto

The Symanzik analysis of correlators in lattice QCD with maximally twisted Wilson fermions reveals that there exist cutoff artifacts which tend to become large as the quark mass gets small. We show that these effects can be reduced to a negligible level by either introducing the clover term in the action or, as already suggested in the literature, by a suita

Roberto De Pietri, Alessandra Feo, Erhard Seiler, Ion-Olimpiu Stamatescu

We study the high density region of QCD within an effective model obtained in the frame of the hopping parameter expansion. The model still acknowledges the sign problem peculiar to non-zero chemical potential, but it permits the development of refined algorithms which ensure a good overlap of the Monte Carlo ensemble with the true one. We review the main fe

Dmitri Grigoriev

Substituting Skyrmion for nucleon, one can potentially see -- in real time -- how the monopole is catalysing the proton (or neutron) decay, and even obtain a plausible estimate for catalysis cross-section. Here we discuss the key aspects of a practical implementation of such approach and demonstrate how one can overcome the main technical problems: Gauss con

D. Becirevic, B. Blossier, Ph. Boucaud, J. P. Leroy

We study the $B^0_s-\bar{B^0_s}$ mixing amplitude in Standard Model by computing the relevant hadronic matrix element in the static limit of lattice HQET with the Neuberger light quark action. In the quenched approximation, and after matching to the $\bar{\rm MS}$ scheme in QCD, we obtain $B^{\bar{\rm MS}}_{B_s}(m_b)=0.940(16)(22)$.

Y. Koma, E. -M. Ilgenfritz, K. Koller, G. Schierholz

Overlap fermions, which preserve exact chiral symmetry on the lattice, provide a powerful tool for investigating the topological structure of the vacuum. Applying this formulation to zero-temperature quenched SU(3) configurations generated by means of the Luescher-Weisz action, we define the topological charge density with and without UV filtering and study

Yigal Shamir

Lattice QCD simulations with staggered fermions rely on the ``fourth-root trick.'' The validity of this trick has been proved for free staggered fermions using renormalization-group block transformations. I review the elements of the construction and discuss how it might be generalized to the interacting case.

Julieta Medina, Wolfgang Bietenholz, Frank Hofheinz, Denjoe O'Connor

We explore a new way to simulate quantum field theory, without introducing a spatial lattice. As a pilot study we apply this method to the 3d λϕ^4 model. The regularisation consists of a fuzzy sphere with radius R for the two spatial directions, plus a discrete Euclidean time. The fuzzy sphere approximates the algebra of functions of the sphere with a matrix

UKQCD Collaboration, A. M. Green, J. Ignatius, M. Jahma

This is a follow-up to our earlier work [Phys. Rev. D 65, 014512 (2002); Eur. Phys. J. C 28, 79 (2003); Phys. Rev. D 69, 094505 (2004)] for the energies and the charge (vector) and matter (scalar) distributions for S-wave states in a heavy-light meson, where the heavy quark is static and the light quark has a mass about that of the strange quark. We study th

Mitsuhiro Kato, Makoto Sakamoto, Hiroto So

We propose a new formulation of lattice theory. It is given by a matrix form and suitable for satisfying Leibniz rule on lattice. The theory may be interpreted as a multi-flavor system. By realizing the difference operator as a commutator, we may obtain exact supersymmetric theories on lattice explicitly. Some problems such as locality and single flavor redu

J. M. Link

Using data from the FOCUS (E831) experiment at Fermilab, we present a new measurement of the weak decay-asymmetry parameter alpha(Lambdac) in Lambdac --> Lambda pi decay. Comparing particle with antiparticle decays, we obtain the first measurement of the CP violation parameter : A = [alpha(Lambdac)+alpha(antiLambda_c)]/[alpha(Lambdac)-alpha(antiLambda_c)]. W

M. Osipenko, G. Ricco, S. Simula, M. Battaglieri

The inclusive, inelastic eD scattering cross section has been measured with the CLAS detector in Hall B of the Thomas Jefferson National Accelerator Facility (TJNAF). Combining these data and previously measured world data we have extracted Nachtmann moments of the deuteron structure function F2 in the region 0.4 < Q2 < 100 GeV2/c2. These results are publish

R. Casana, C. A. M. de Melo, B. M. Pimentel

Massless scalar and vector fields are coupled to Lyra geometry by means of Duffin-Kemmer-Petiau (DKP) theory. Using Schwinger Variational Principle, equations of motion, conservation laws and gauge symmetry are implemented. We find that the scalar field couples to the anholonomic part of the torsion tensor, and the gauge symmetry of the electromagnetic field

Firmin J. Oliveira

A linear second order wave equation is presented based on cosmological general relativity, which is a space-velocity theory of the expanding Universe. The wave equation is shown to be exactly solvable, based on the Gaussian hypergeometric function.

Juergen Mueller, James G. Williams, Slava G. Turyshev

Lunar laser ranging (LLR) is used to conduct high-precision measurements of ranges between an observatory on Earth and a laser retro-reflector on the lunar surface. Over the years, LLR has benefited from a number of improvements both in observing technology and data modeling, which led to the current accuracy of post-fit residuals of ~2 cm. Today LLR is a pr

S. Chatterjee, A. Banerjee, Y. Z. Zhang

We present a simple higher dimensional FRW type of model where the acceleration is apparently caused by the presence of the extra dimensions. Assuming an ansatz in the form of the deceleration parameter we get a class of solutions some of which shows the desirable feature of dimensional reduction as well as reasonably good physical properties of matter. Inte

M. Heydari-Fard, M. Mohseni, H. R. Sepangi

The geodesic deviation equation is generalized to worldline deviation equations describing the relative accelerations of charged spinning particles in the framework of Dixon-Souriau equations of motion.

Zahid Anwar, William Yurcik, Vivek Pandey, Asim Shankar

Application-level peer-to-peer (P2P) network overlays are an emerging paradigm that facilitates decentralization and flexibility in the scalable deployment of applications such as group communication, content delivery, and data sharing. However the construction of the overlay graph topology optimized for low latency, low link and node stress and lookup perfo

Aris L. Moustakas, Steven H. Simon

The use of multi-antenna arrays in both transmission and reception has been shown to dramatically increase the throughput of wireless communication systems. As a result there has been considerable interest in characterizing the ergodic average of the mutual information for realistic correlated channels. Here, an approach is presented that provides analytic e

Thierry Poibeau

This paper presents a versatile system intended to acquire paraphrastic phrases from a representative corpus. In order to decrease the time spent on the elaboration of resources for NLP system (for example Information Extraction, IE hereafter), we suggest to use a machine learning system that helps defining new templates and associated resources. This knowle

G. Gutin, A. Rafiey, A. Yeo

For digraphs $D$ and $H$, a mapping $f: V(D)\dom V(H)$ is a {\em homomorphism of $D$ to $H$} if $uv\in A(D)$ implies $f(u)f(v)\in A(H).$ For a fixed directed or undirected graph $H$ and an input graph $D$, the problem of verifying whether there exists a homomorphism of $D$ to $H$ has been studied in a large number of papers. We study an optimization version

Jeroen Bekaert, Herbert Van de Sompel

In recent years, a variety of digital repository and archival systems have been developed and adopted. All of these systems aim at hosting a variety of compound digital assets and at providing tools for storing, managing and accessing those assets. This paper will focus on the definition of common and standardized access interfaces that could be deployed acr

Valdis Vitolins, Audris Kalnins

The paper proposes a more formalized definition of UML 2.0 Activity Diagram semantics. A subset of activity diagram constructs relevant for business process modeling is considered. The semantics definition is based on the original token flow methodology, but a more constructive approach is used. The Activity Diagram Virtual machine is defined by means of a m

Babajide Afolabi, Odile Thiery

This article presents earlier results of our research works in the area of modeling Business Intelligence Systems. The basic idea of this research area is presented first. We then show the necessity of including certain users&#39; parameters in Information systems that are used in Business Intelligence systems in order to integrate a better response from suc

Peter Jung, Gerhard Wunder

Phase noise and frequency offsets are due to their time-variant behavior one of the most limiting disturbances in practical OFDM designs and therefore intensively studied by many authors. In this paper we present a generalized framework for the prediction of uncoded system performance in the presence of time-variant distortions including the transmitter and

Tadaaki Hosaka, Yoshiyuki Kabashima

The encoder and decoder for lossy data compression of binary memoryless sources are developed on the basis of a specific-type nonmonotonic perceptron. Statistical mechanical analysis indicates that the potential ability of the perceptron-based code saturates the theoretically achievable limit in most cases although exactly performing the compression is compu

N. Wiese, T. Dimopoulos, M. Ruhrig, J. Wecker

This work reports on the thermal stability of two amorphous CoFeB layers coupled antiferromagnetically via a thin Ru interlayer. The saturation field of the artificial ferrimagnet which is determined by the coupling, J, is almost independent on the annealing temperature up to more than 300 degree C. An annealing at more than 325 degree C significantly increa

G. M. Jones, B. H. Hu, C. H. Yang, M. J. Yang

We propose and demonstrate experimentally a novel design of single-electron quantum dots. The structure consists of a narrow band gap quantum well that can undergo a transition from the hole accumulation regime to the electron inversion regime in a single-top-gate transistor configuration. We have observed large size quantization and Coulomb charging energie

A. V. Klopper, U. K. Roessler, R. L. Stamps

Extensive Monte Carlo simulations are used to investigate the stability of the ferromagnetic ground state in three-dimensional systems of Ising dipoles with added quenched disorder. These systems model the collective ferromagnetic order observed in various systems with dipolar long-range interactions. The uniaxial dipolar spins are arranged on a face-centred

N. Wiese, T. Dimopoulos, M. Ruhrig, J. Wecker

This work reports on the magnetic interlayer coupling between two amorphous CoFeB layers, separated by a thin Ru spacer. We observe an antiferromagnetic coupling which oscillates as a function of the Ru thickness x, with the second antiferromagnetic maximum found for x=1.0 to 1.1 nm. We have studied the switching of a CoFeB/Ru/CoFeB trilayer for a Ru thickne

D. Wahyu Utami, Hsi-Sheng Goan, C. A. Holmes, G. J. Milburn

We consider a type of Quantum Electro-Mechanical System, known as the shuttle system, first proposed by Gorelik et al., [Phys. Rev. Lett., 80, 4526, (1998)]. We use a quantum master equation treatment and compare the semi-classical solution to a full quantum simulation to reveal the dynamics, followed by a discussion of the current noise of the system. The t

Ling Wang, K. S. D. Beach, Anders W. Sandvik

We use quantum Monte Carlo (stochastic series expansion) and finite-size scaling to study the quantum critical points of two S=1/2 Heisenberg antiferromagnets in two dimensions: a bilayer and a Kondo-lattice-like system (incomplete bilayer), each with intra- and inter-plane couplings J and J_perp. We discuss the ground-state finite-size scaling properties of

M. B. Stone, W. Tian, G. E. Granroth, M. D. Lumsdena

Dimethylammonium copper (II) chloride (also known as DMACuCl3 or MCCL) is a low dimensional S=1/2 quantum spin system proposed to be an alternating ferro-antiferromagnetic chain with similar magnitude ferromagnetic (FM) and antiferromagnetic (AFM) exchange interactions. Subsequently, it was shown that the existing bulk measurements could be adequately modele

Bhavtosh Bansal, V Venkataraman

The effect of Landau level formation on the population of intrinsic electrons in InSb is probed near room temperature in magnetic fields upto 16 Tesla. Although the measured magnetic field dependence of the Hall coefficient is qualitatively similar to published results, it is shown that the data may also be explained by simply including ambipolar conduction.

M. B. Stone, W. Tian, T. P. Murphy, S. E. Nagler

Although (CH3)2NH2CuCl3 (MCCL) was first examined in the 1930&#39;s [1], there are open questions regarding the magnetic dimensionality and nature of the magnetic properties. MCCL is proposed to be a S=1/2 alternating ferromagnetic antiferromagnetic spin chain alternating along the crystalline a-axis [2,3]. Proposed ferromagnetic (JFM =1.3 meV) and antiferro

A. Delisle, D. J. Gonzalez, M. J. Stott

Several static and dynamic properties of liquid silicon near melting have been determined from an orbital free {\em ab-initio} molecular dynamics simulation. The calculated static structure is in good agreement with the available X-ray and neutron diffraction data. The dynamical structure shows collective density excitations with an associated dispersion rel

Aleksandar Bogojevic, Antun Balaz, Aleksandar Belic

We introduce and analyze a new quantity, the path integral ideal, governing the flow of generic discrete theories to the continuum limit and greatly increasing their convergence. The said flow is classified according to the degree of divergence of the potential at spatial infinity. Studying the asymptotic behavior of path integral ideals we isolate the domin

J. Jaroszynski, Dragana Popovic

The relaxations of conductivity have been studied in a strongly disordered two-dimensional (2D) electron system in Si after excitation far from equilibrium by a rapid change of carrier density n_s at low temperatures T. The dramatic and precise dependence of the relaxations on n_s and T strongly suggests (a) the transition to a glassy phase as T->0, and (b)

Maciej Bobrowski, Jacek Dziedzic, Jaroslaw Rybicki

Ultra-precision machining of metals, the breaking of nanowires under tensile stress and fracture of nanoscale materials are examples of technologically important processes which are both extremely difficult and costly to investigate experimentally. We describe a multiscale method for the simulation of such systems in which the energetically active region is

Jens Siewert, Tobias Brandes, Giuseppe Falci

The rapid experimental progress in the field of superconducting nanocircuits gives rise to an increasing quest for advanced quantum-control techniques for these macroscopically coherent systems. Here we demonstrate theoretically that stimulated Raman adiabatic passage (STIRAP) should be possible with the quantronium setup of a Cooper-pair box. The scheme app

E. Rauwel, W. Prellier, B. Mercey, S. de Brion

Thin films of Sm0.5Ca0.5MnO3 manganites with charge ordering (CO) properties and colossal magnetoresistance were synthesized by pulsed laser deposition technique on (100)-SrTiO3 and (100)-LaAlO3 substrates. We first compare the structural modifications as function of the substrate and film thickness. Secondly, measuring transport properties in magnetic field

Pierre-Olivier Amblard, Christophe Vignat

The aim of the paper is to study the link between non additivity of some entropies and their boundedness. We propose an axiomatic construction of the entropy relying on the fact that entropy belongs to a group isomorphic to the usual additive group. This allows to show that the entropies that are additive with respect to the addition of the group for indepen

Shahar Even-Dar Mandel, Ron Lifshitz

We study the electronic energy spectra and wave functions on the square Fibonacci tiling, using an off-diagonal tight-binding model, in order to determine the exact nature of the transitions between different spectral behaviors, as well as the scaling of the total bandwidth as it becomes finite. The macroscopic degeneracy of certain energy values in the spec

J. M. Villas-Boas, Sergio E. Ulloa, A. O. Govorov

In this paper we show that it is possible to switch the spin polarization of the photocurrent signal obtained from a single self-assembled quantum dot photodiode under the effect of elliptically polarized light by just increasing the light intensity. In the nonlinear mechanism treated here, intense elliptically polarized light creates an effective exchange i

F. Messina, M. Cannas

The conversion processes of Ge-related point defects triggered in amorphous SiO2 by 4.7eV laser exposure were investigated. Our study has focused on the interplay between the (=Ge&#8226;-H) H(II) center and the twofold coordinated Ge defect (=Ge&#8226;&#8226;). The former is generated in the post-irradiation stage, while the latter decays both during and aft

V. M. Somsikov

The process of equilibration of a colliding hard-disks system is studied in the framework of classical mechanic. The method consists of dividing the nonequilibrium system into the interacting subsystems; the evolution one of these subsystems is analyzed employing generalized Lagrange and Liouville equations. The subsystem-subsystem interaction force is consi

H. Ott, C. Schuessler-Langeheine, E. Schierle, A. Yu. Grigoriev

Quantitative analyses of x-ray scattering from thin films of Ho and Dy metal at the M_5 resonances result in values of the optical constants and the magnetic scattering lengths f_m, with f_m as large as 200 r_0. The observation of first- and second-order magnetic satellites allows to separate f_m into circular and linear dichroic contributions. This high mag

Raoul Dillenschneider, Jean Richert

We study the effect of site occupation on the description of quantum spin systems at finite temperature and mean-field level. We impose each lattice site to be occupied by a single electron. This is realized by means of a specific prescription. The outcome of the prescription is compared to the result obtained by means of a projection procedure which fixes t

H. Ott, S. J. Heise, R. Sutarto, Z. Hu

We report on the growth and characterization of ferromagnetic Gd-doped EuO thin films. We prepared samples with Gd concentrations up to 11% by means of molecular beam epitaxy under distillation conditions, which allows a very precise control of the doping concentration and oxygen stoichiometry. Using soft x-ray magnetic circular dichroism at the Eu and Gd M4

L. Craco, L. De Cesare, I. Rabuffo, I. P. Takov

The critical behaviour of thin films containing quenched random impurities and inhomogeneities is investigated by the renormalization-group method. The finite-size crossover in impure films has been considered on the basis of the fundamental relationship between the effective spatial dimensionality and the characteristic lengths of the system. The difference

L. E. Gonzalez, D. J. Gonzalez, M. J. Stott

First principles molecular dynamics simulations have been performed for the liquid-vapor interfaces of liquid Li, Mg, Al and Si. We analize the oscillatory ionic and valence electronic density profiles obtained, their wavelengths and the mechanisms behind their relative phase-shift.

Yoichi Asada, Keith Slevin, Tomi Ohtsuki

Electron transport phenomena in disordered electron systems with spin-orbit coupling in two dimensions and below are studied numerically. The scaling hypothesis is checked by analyzing the scaling of the quasi-1D localization length. A logarithmic increase of the mean conductance is also confirmed. These support the theoretical prediction that the two dimens

Hiroaki Nakamura, Naomichi Hatano, Ryoen Shirasaki

We report our recent predictions on the quantum Nernst effect, a novel thermomagnetic effect in the quantum Hall regime. We assume that, when the chemical potential is located between a pair of neighboring Landau levels, edge currents convect around the system. This yields theoretical predictions that the Nernst coefficient is strongly suppressed and the the

Dong-Meng Chen, Liang-Jian Zou

Magnetic and orbital structures in KCuF$_{3}$ are revisited by the cluster self-consistent field approach developed recently. We clearly showed that due to the inherent frustration, the ground state of the system with the superexchange and Jahn-Teller phonon-mediated orbital couplings is highly degenerate without broken symmetry; the orthorhombic crystalline

Iwan Jensen

We have derived long series expansions for the perimeter generating functions of the radius of gyration of various polygons with a convexity constraint. Using the series we numerically find simple (algebraic) exact solutions for the generating functions. In all cases the size exponent $ν=1$.

Iwan Jensen

We introduce a model for temporally disordered directed percolation in which the probability of spreading from a vertex $(t,x)$, where $t$ is the time and $x$ is the spatial coordinate, is independent of $x$ but depends on $t$. Using a very efficient algorithm we calculate low-density series for bond percolation on the directed square lattice. Analysis of th

I. Bulyzhenkov, A. -M. Lamarche, G. Lamarche

Ginzburg-Landau bulk magnetization of itinerant electrons can provide a negative effective field in the Weiss model by coupling to localized magnetic moments. The coupling enforces remnant magnetization, which can be negative or positive depending on the sample magnetic history. Stable magnetic susceptibility of coupled nonequilibrium subsystems with magneti

Golan Bel, Baruch Rosenstein

Dynamics of homogeneous moving vortex matter is considered beyond the linear response. The framework is the time dependent Ginzburg - Landau equation within the lowest Landau level approximation. Both disorder and thermal fluctuations are included using the Martin-Siggia-Rose formalism. We determine the critical current as function of magnetic field and temp

M. A. Avila, T. Takabatake, Y. Takahashi, S. L. Bud&#39;ko

We have grown single crystals of YbFe6Ge6 and LuFe6Ge6 and characterized their anisotropic behaviour through low field magnetic susceptibility, field-dependent magnetization, resistivity and heat capacity measurements. The Yb+3 valency is confirmed by LIII XANES measurements. YbFe6Ge6 crystals exhibit a field-dependent, sudden reorientation of the Fe spins a

Koichi Kusakabe

Uniqueness of effective interaction defined in an extension of the Kohn-Sham theory is proved, if the model with a non-degenerate ground state exists and to reproduce a correlation function as well as the single-particle density of an electron system. The two-body interaction term is regarded as a Hubbard-type short range interaction term. The interaction st

Linghua Wen, Min Liu, Hongwei Xiong, Mingsheng Zhan

We present a theoretical model to investigate the interference of an array of Bose-Einstein condensates loaded in a one-dimensional spin-dependent optical lattice, which is based on an assumption that for the atoms in the entangled single-atom state between the internal and the external degrees of freedom each atom interferes only with itself. Our theoretica

O. Manuel, Sumeet A. Kamat, Michael Mozina

The Iron Sun formed on the collapsed core of a supernova and now acts as a magnetic plasma diffuser, as did the precursor star, separating ions by mass. This process covers the solar surface with lightweight elements and with lighter isotopes of each element. Running difference images expose rigid, iron-rich structures below the fluid photosphere made of lig

Masatoshi Imanishi, C. C. Dudley, Philip R. Maloney

We present infrared L-band (3-4 micron) nuclear spectra of a large sample of nearby ultraluminous infrared galaxies (ULIRGs).ULIRGs classified optically as non-Seyferts (LINERs, HII-regions, and unclassified) are our main targets. Using the 3.3 micron polycyclic aromatic hydrocarbon (PAH) emission and absorption features at 3.1 micron due to ice-covered dust

C. B. Markwardt, J. Tueller, G. K. Skinner, N. Gehrels

We present preliminary results from the first 3 months of the Swift BAT high galactic latitude survey in the 14--195 keV band. The survey reaches a flux of \~10^{-11} erg/cm^2/s and has ~2.7&#39; (90% confidence) positional uncertainties for the faintest sources. This represents the most sensitive survey to date in this energy band. These data confirm the co

H. W. W. Spoon, A. G. G. M. Tielens, L. Armus, G. C. Sloan

Silicates are an important component of interstellar dust and the structure of these grains -- amorphous versus crystalline -- is sensitive to the local physical conditions. We have studied the infrared spectra of a sample of ultra-luminous infrared galaxies. Here, we report the discovery of weak, narrow absorption features at 11, 16, 19, 23, and 28 microns,

Sergei Shandarin, Hume A. Feldman, Katrin Heitmann, Salman Habib

We study the global distribution and morphology of dark matter voids in a LCDM universe using density fields generated by N-body simulations. Voids are defined as isolated regions of the low-density excursion set specified via density thresholds, the density thresholds being quantified by the corresponding filling factors, i.e., the fraction of the total vol

M. R. Schmidt, L. Zacs, J. Mikolajewska, K. H. Hinkle

The photospheric abundances for the cool component of the symbiotic star CH Cyg were calculated for the first time using high-resolution near-infrared spectra and the method of of standard LTE analysis and atmospheric models. The iron abundance for CH Cyg was found to be solar, [Fe/H] = 0.0+/-0.19. The atmospheric parameters and metallicity for CH Cyg are fo

Z. Abraham, D. Falceta-Goncalves, T. P. Dominici, A. Caproni

In this paper we use the 7 mm and 1.3 mm light curves obtained during the 2003.5 low excitation phase of the eta Carinae system to constrain the possible parameters of the binary orbit. To do that we assumed that the mm wave emission is produced in a dense disk surrounding the binary system; during the low excitation phase, which occurs close to periastron,

L. C. Garcia de Andrade

The role played by torsion of magnetic vortex line curves or filaments, in the equilibrium state of magnetars is investigated. When the magnetars equilibrium equations are written in terms Frenet-Serret frame it is shown that in regions of the magnetic star where the Frenet torsion is constant it induces an oscillation in the vortex filaments. By solving the

G. Gogoberidze, L. Samushia, G. D. Chagelishvili, J. G. Lominadze

Special features of surface gravity waves in deep fluid flow with constant vertical shear of velocity is studied. It is found that the mean flow velocity shear leads to non-trivial modification of surface gravity wave modes dispersive characteristics. Moreover, the shear induces generation of surface gravity waves by internal vortex mode perturbations. The p

S. Kimeswenger

In 1994 V4332 Sgr underwent a mysterious eruption. Somehow its fast evolution towards a red giant star was, lacking alternative classifications, connected to the red variable M31 RV, which had its eruption in 1988. The red eruptive variable V838~Mon draw in February 2002 the attention back to its &#39;older twin&#39; V4332~Sgr. The new precise photometry of

I. Musella, V. Ripepi, E. Brocato, V. Castellani

We present the result of BVI photometry, obtained by using FORS@VLT, of the Cepheids present in the field of the Large Magellanic Cloud cluster NGC 1866. We found the 22 known variables plus an additional new Cepheid located about 10&#39; from the cluster center. The accuracy of the photometry allowed us to derive B, V and I mean magnitudes with an uncertain

N. Masetti, E. Mason, L. Bassani, R. Landi

As a follow-up of the X-ray serendipitous detection of the source 2MASX J14585116-1652223, medium-resolution optical spectroscopic observations collected at the 1.5-metre &#34;Cassini&#34; telescope of the Astronomical Observatory of Bologna were performed. This allowed us to determine the extragalactic nature of this X-ray source, which is a Type 2 Seyfert

A. J. Lim, S. A. E. G. Falle, T. W. Hartquist

We consider the dynamical evolution of an interstellar cloud that is initially in thermal equilibrium in the warm phase and is then subjected to a sudden increase in the pressure of its surroundings. We find that if the initial plasma beta of the cloud is of order unity, then there is a considerable period during which the material in the cloud both has a sm

Ralf Bender, John Kormendy, Gary Bower, Richard Green

We present HST spectroscopy of the nucleus of M31 obtained with STIS. Spectra taken around the CaT lines at 8500 see only the red giants in the double bright- ness peaks P1 and P2. In contrast, spectra taken at 3600-5100 A are sensitive to the tiny blue nucleus embedded in P2, the lower surface brightness red nucleus. P2 has a K-type spectrum, but the embedd

Mohsen Shadmehri, Fazeleh Khajenabi

The steady-state structure of self-gravitating, magnetized accretion disks is studied using a set of self-similar solutions which are appropriate in the outer regions. The disk is assumed to be isothermal and the magnetic field outside of the disk is treated in a phenomenological way. However, the internal field is determined self-consistently. The behaviour

Stuart C. Whitehouse, Matthew R. Bate, Joe J. Monaghan

We describe a new, faster implicit algorithm for solving the radiation hydrodynamics equations in the flux-limited diffusion approximation for smoothed particle hydrodynamics. This improves on the method elucidated in Whitehouse & Bate by using a Gauss-Seidel iterative method rather than iterating over the exchange of energy between pairs of particles. The n

R. Liseau, K. Justtanont, A. G. G. M. Tielens

Far infrared fine structure line data from the ISO archive have been extracted for several hundred YSOs and their outflows, including molecular (CO) outflows, optical jets and Herbig-Haro (HH) objects. Given the importance of these lines to astrophysics, their excitation and transfer ought to be investigated in detail and, at this stage, the reliability of t

Tsutomu T. Takeuchi

The interplay between dust and molecules is of fundamental importance in early galaxy evolution. First we present the prediction for the dust emission from forming galaxies. Then we discuss the observational strategy for molecules in early galaxies by infrared absorption lines of a bright continuum source behind the clouds. By combining these two approaches,

Brian Punsly, Luis Rodriguez, Steven Tingay, Sergio Cellone

In this Letter, we discuss new deep radio observations of PKS 1622-253 and their implications for the energetics of the central engine that powers this strong high energy gamma-ray source. Combining archival infrared and optical measurements with new millimeter observations, we show that even though the accretion flow in PKS 1622-253 is under-luminous by qua

A. M. Teodorescu, R. H. Mendez, R. P. Saglia, A. Riffeser

We present photometric and kinematic information obtained by measuring 197 planetary nebulae (PNs) discovered in the flattened Fornax elliptical galaxy NGC 1344 (also known as NGC 1340) with an on-band, off-band, grism + on-band filter technique. We build the PN luminosity function (PNLF) and use it to derive a distance modulus m-M=31.4, slightly smaller tha

Alvise Mattei

In General Relativity, there is a new field of activity concerning the study of charged stars. In a recent paper, Ray et al. have shown the possibility that the collapse of a charged star could form a charged black hole before all the charge leaves the system. In this field of view we propose a new model for UHECR and we will show that it is possible to acce

Leticia Carigi, Pedro Colin, Manuel Peimbert

Based on the photometric properties of NGC 6822 we derive a robust star formation history. Adopting this history we compute 15 models of galactic chemical evolution. All of them match present-day photometric properties. The dark halo mass in all models evolves according to the mass assembly history predicted by a $Λ$CDM cosmology. We model the evolution of t

Tanmoy Bhattacharya, Rajan Gupta, Weonjong Lee, Stephen R. Sharpe

Non-perturbative results for improvement and renormalization constants needed for on-shell and off-shell O(a) improvement of bilinear operators composed of Wilson fermions are presented. The calculations have been done in the quenched approximation at beta=6.0, 6.2 and 6.4. To quantify residual discretization errors we compare our data with results from othe

Akihiro Ishibashi, Robert M. Wald

No. It is simply not plausible that cosmic acceleration could arise within the context of general relativity from a back-reaction effect of inhomogeneities in our universe, without the presence of a cosmological constant or ``dark energy.&#39;&#39; We point out that our universe appears to be described very accurately on all scales by a Newtonianly perturbed

V. A. Zykunov

The weak radiative corrections to the Drell-Yan process above the Z-peak have been studied. The compact asymptotic expression for the two heavy boson exchange - one of the significant contributions to the investigated process - has been obtained, the results expand in the powers of the Sudakov electroweak logarithms. At the quark level we compare the weak ra

Tobias H. Colding, William P. Minicozzi

This paper is the fifth and final in a series on embedded minimal surfaces. Following our earlier papers on disks, we prove here two main structure theorems for non-simply connected embedded minimal surfaces of any given fixed genus. The first of these asserts that any such surface without small necks can be obtained by gluing together two oppositely--orient

A. H. Castro Neto, F. Guinea, N. M. R. Peres

We study the integer and fractional quantum Hall effect on a honeycomb lattice at half-filling (graphene) in the presence of disorder and electron-electron interactions. We show that the interactions between the delocalized chiral edge states (generated by the magnetic field) and Anderson-localized surface states (created by the presence of zig-zag edges) le

Daniel Robbins, Savdeep Sethi

The null-brane background is a simple smooth 1/2 BPS solution of string theory. By tuning a parameter, this background develops a big crunch/big bang type singularity. We construct the DLCQ description of this space-time in terms of a Yang-Mills theory on a time-dependent space-time. Our dual Matrix description provides a non-perturbative framework in which

James G. Bartlett, Jean-Baptiste Melin

We examine the effect of point source confusion on cluster detection in Sunyaev-Zel&#39;dovich (SZ) surveys. A filter matched to the spatial and spectral characteristics of the SZ signal optimally extracts clusters from the astrophysical backgrounds. We calculate the expected confusion (point source and primary cosmic microwave background [CMB]) noise throug

S. Rayaprol, R. Poettgen

La2Au2Cd and Ce2Au2Cd were prepared from the elements by reactions in sealed tantalum tubes in a water-cooled sample chamber of an induction furnace. These intermetallics crystallize with the tetragonal Mo2FeB2 type, space group P4/mbm. While La2Au2Cd is Pauli paramagnetic, Ce2Au2Cd shows Curie-Weiss behaviour above 100 K with an experimental magnetic moment

Xianglei Zhu, Marcus Bleicher, Horst Stoecker

The cumulant method is applied to study elliptic flow ($v_2$) in Au+Au collisions at $\sqrt{s}=200$AGeV, with the UrQMD model. In this approach, the true event plane is known and both the non-flow effects and event-by-event spatial ($ε$) and $v_2$ fluctuations exist. Qualitatively, the hierarchy of $v_2$&#39;s from two, four and six-particle cumulants is con

Gregory J. Galloway, Richard Schoen

Hawking&#39;s theorem on the topology of black holes asserts that cross sections of the event horizon in 4-dimensional asymptotically flat stationary black hole spacetimes obeying the dominant energy condition are topologically 2-spheres. This conclusion extends to outer apparent horizons in spacetimes that are not necessarily stationary. In this paper we ob

Henrique Bursztyn, Gil R. Cavalcanti, Marco Gualtieri

We present a theory of reduction for Courant algebroids as well as Dirac structures, generalized complex, and generalized Kähler structures which interpolates between holomorphic reduction of complex manifolds and symplectic reduction. The enhanced symmetry group of a Courant algebroid leads us to define \emph{extended} actions and a generalized notion of mo

Zurab Berezhiani, Piotr H. Chankowski, Adam Falkowski, Stefan Pokorski

A mechanism of double protection of the Higgs potential, by supersymmetry and by a global symmetry, is investigated in a class of supersymmetric models with the SU(3)xSU(3)xU(1) gauge symmetry. In such models the electroweak symmetry can be broken with no fine-tuning at all.

Manuela Campanelli, Miranda Dettwyler, Mark Hannam, Carlos O. Lousto

Three-body interactions are expected to be common in globular clusters and in galactic cores hosting supermassive black holes. Here we consider an equal-mass binary-black-hole system in the presence of a third black hole. Using numerically generated binary-black-hole initial-data sets, and first- and second-order post-Newtonian (1PN and 2PN) techniques, we f

V. Derzhko, J. Jedrzejewski

Recently, we demonstrated rigorously the stability of charge-stripe phases in quantum-particle systems that are described by extended Falicov-Kimball Hamiltonians, with the quantum hopping particles being either spinless fermions or hardcore bosons. In this paper, by means of the same methods, we show that any anisotropy of nearest-neighbor hopping eliminate

A. Plastino, A. R. Plastino, B. H. Soffer

It was recently shown, starting from first principles, that thermodynamics&#39; first law (TFL) can be microscopically obtained without need of invoking the adiabatic theorem (AT) [Physica A, {\bf 356}, 167 (2005)]. We show here that a TFL can also be found for Fisher&#39;s information measure, following a similar procedure. Further, it is proved that enforc

John Lott

We show that three-dimensional homogeneous Ricci flow solutions that admit finite-volume quotients have long-time limits given by expanding solitons. We show that the same is true for a large class of four-dimensional homogeneous solutions. We give an extension of Hamilton&#39;s compactness theorem that does not assume a lower injectivity radius bound, in te

M. Dotti, M. Colpi, F. Haardt

We study the inspiral of double black holes, with masses in the LISA window of detectability, orbiting inside a massive circum-nuclear disc. Using high-resolution SPH simulations, we follow the black hole dynamics in the early phase when gas-dynamical friction acts on the black holes individually, and continue our simulation until they form a close binary. W

C. -H. Zhang, H. A. Fertig

We develop a time-dependent Hartree-Fock approximation that is appropriate for Bose-condensed systems. Defining a {\it depletion Green&#39;s function} allows the construction of condensate and depletion particle densities from eigenstates of a single time-dependent Hamiltonian, guaranteeing that our approach is a conserving approximation. The poles of this G