September 2005 arXiv papers — page 10

Christian Schwinn

In five dimensional models of Higgsless electroweak symmetry breaking, tree level unitarity in gauge boson scattering is restored by the exchange of gauge boson Kaluza-Klein modes instead of a Higgs boson. Unitarity of scattering amplitudes involving top quarks requires also the Kaluza-Klein modes of the third family quarks. It is shown that the relevant uni

Michael Strickland

I discuss recent advances in the understanding of non-equilibrium gauge field dynamics in plasmas which have particle distributions which are locally anisotropic in momentum space. In contrast to locally isotropic plasmas such anisotropic plasmas have a spectrum of soft unstable modes which are characterized by exponential growth of transverse (chromo)-magne

M. A. Stephanov, J. J. M. Verbaarschot, T. Wettig

We review elementary properties of random matrices and discuss widely used mathematical methods for both hermitian and nonhermitian random matrix ensembles. Applications to a wide range of physics problems are summarized. This paper originally appeared as an article in the Wiley Encyclopedia of Electrical and Electronics Engineering.

J. R. Pelaez

I review the large Nc behavior of light resonances generated from unitarized one-loop Chiral Perturbation Theory. In contrast with the rho or K*, the scalar behavior is at odds with a qqbar "dominant component". In fact, in the light scalar region, meson-meson amplitudes vanish as Nc increases. Also, the scalar widths, obtained from their associated

A. R. Malecki

We consider a multi-channel correction accounting for intermediate transitions inside an equivalence class of diffractive states. Our formalism of 'diffractive limit' provides an excellent description of elastic and inclusive inelastic scattering of high energy (53 - 546 GeV) protons and antiprotons.

Antonio Silva, Hyun-CHul Kim, Diana Urbano, Klaus Goeke

We investigate three different axial-vector form factors of the nucleon, $G_A^{0}$, $G_A^3$, $G_A^8$, within the framework of the SU(3) chiral quark-soliton model, emphasizing their strangeness content. We take into account the rotational $1/N_c$ and linear strange quark ($m_s$) contributions using the symmetry-conserving SU(3) quantization and assuming isos

Steen Hannestad, Georg Raffelt

Precision measurements of the acoustic peaks of the cosmic microwave background indicate that neutrinos must be freely streaming at the photon decoupling epoch when T ~ 0.3 eV. This requirement implies restrictive limits on ``secret neutrino interactions,'' notably on neutrino Yukawa couplings with hypothetical low-mass (pseudo)scalars ϕ. For diagona

V. A. Petrov, R. A. Ryutin, A. E. Sobol, J. -P. Guillaud

EDDE is a Monte Carlo event generator, under construction, for different Exclusive Double Diffractive Events. The program is based on the extended Regge-eikonal approach for "soft" processes. Standard Model and its extensions are used for "hard" fusion processes. An interface to PYTHIA, CMSJET and CMKIN is provided.

Bjorn Leder, Tomasz Korzec

We study the chiral Gross-Neveu model with Wilson fermions. In the framework of the Schroedinger functional we show that in general not only the bare mass has to be tuned to achieve chiral symmetry in the continuum, but also coupling constants multiplying chirally non-invariant four fermion terms. The strategy for fixing the parameters of the theory is expla

Slavo Kratochvila, Philippe de Forcrand

We present a canonical approach to study properties of QCD at finite baryon density rho, and apply it to the determination of the phase diagram of four-flavour QCD. For a pion mass of about 350 MeV, the first-order transition between the hadronic and the plasma phase gives rise to a co-existence region in the T-rho plane, which we study in detail. We obtain

CP-PACS, JLQCD Collaborations, :, T. Ishikawa

CP-PACS and JLQCD collaborations are carrying out a joint project of the 2+1 flavor full QCD simulation. Gauge configurations are generated for the non-perturbatively $O(a)$-improved Wilson quark action and the Iwasaki gauge action using PHMC algorithm at three lattice spacings, $a\sim 0.076$, 0.010 and 0.122 fm, with a fixed physical volume $(2.0 fm)^3$. We

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

We present technical details of fermionic observables computations in NSPT. In particular we discuss the construction of composite operators starting from the inverse Dirac operator building block, the subtraction of UV divergences and the treatment of irrelevant contributions in extracting the continuum limit.

Constantia Alexandrou, Antonios Tsapalis

Before studying the pentaquark system we examine the spectral weights of the two lowest scattering states in the two-pion system in the isospin I=2 channel on lattices of size $16^3\times 32$, $24^3 \times 32$ and $32^3 \times 64$ at $β=6.0$ in the quenched theory. We find that the spectral weights scale with the volume for large time separations. Therefore

K. Petrov, A. Jakovac, P. Petreczky, A. Velytsky

We present preliminary studies of bottomonia spectral functions at zero and finite temperature using quenched anisotropic lattices. The heavy quark is treated within Fermilab approach. We find no modification of the $η_b$ and $Υ$ states up to temperatures $2.3T_c$ while our study suggest dissolution of $χ_b$ state at $1.15T_c$.

MILC Collaboration, C. Bernard, C. DeTar, Steven Gottlieb

We present an update of the MILC studies of the physics of light pseudoscalars using improved staggered fermions. New runs at lighter quark mass, as well as increased statistics for older sets, are enabling us to improve the results for decay constants in full QCD. In addition, we have analyzed quenched runs at two different lattice spacings. This makes poss

T. Yamazaki

We present preliminary results for the $ΔI = 3/2$ kaon decay matrix elements using domain wall fermions and the DBW2 gauge action at one coarse lattice spacing corresponding to $a^{-1} = 1.3$ GeV. We employ an extention of the Lellouch and Lüscher formula for non-zero total momentum to extract the infinite volume, center-of-mass system decay amplitudes. We c

Torsten Tok, Kurt Langfeld, Hugo Reinhardt, Lorenz von Smekal

We investigate the infrared behaviour of the gluon propagator in Landau gauge on a lattice with twisted boundary conditions. Analytic calculations using Dyson-Schwinger equations, exact renormalization group and stochastic quantization show that the gluon propagator in Landau gauge approaches zero for small momentum. On the other hand lattice calculations an

D. Brömmel, M. Diehl, M. Göckeler, Ph. Hägler

Moments of generalised parton distributions can be related to off-forward matrix elements of local operators. We calculate a few of the leading twist matrix elements for the pion on the lattice. The simulations are performed using two flavours of dynamical fermions and a range of pion masses from 550 to 1090 MeV. Our lattice spacings and spatial volumes lie

Tomasz Korzec, Francesco Knechtli, Ulli Wolff, Bjorn Leder

We investigate the two flavor chiral Gross-Neveu model in the Schroedinger functional on the lattice. The procedure necessary to recover chiral symmetry in the continuum limit of this model with Wilson fermions is discussed. We introduce several useful observables and present a first demonstration of the feasibility of Monte-Carlo simulations in this model.

F. Farchioni, P. Hofmann, K. Jansen, I. Montvay

We summarize four contributions about dynamical twisted mass fermions. The resulting report covers results for N_f=2 obtained from three different gauge actions, namely the standard Wilson plaquette gauge action, the DBW2 and the tree-level Symanzik improved gauge action. In addition, first results for N_f=2+1+1 flavours of twisted mass fermions are discusse

R. Ammendola, R. Petronzio, D. Rossetti, A. Salamon

We present the current status of APENet, our custom 3-dimensional interconnect architecture for PC clusters environment. We report some micro-benchmarks on our recent large installation as well as new developments on the software and hardware side. The low level device driver has been reworked by following a custom hardware RDMA architecture, and MPICH-VMI,

Hideaki Iida, Takumi Doi, Noriyoshi Ishii, Hideo Suganuma

J/Ψand η_c above the QCD critical temperature T_c are studied in anisotropic quenched lattice QCD, considering whether the c\bar c systems above T_c are compact quasi-bound states or scattering states. We adopt the standard Wilson gauge action and O(a)-improved Wilson quark action with renormalized anisotropy a_s/a_t =4 at β=6.10 on 16^3\times (14-26) lattic

Matthew Nobes, Howard Trottier

Using automated perturbation theory techniques, we have computed the one-loop mass of Fermilab fermions, with an improved gluon action. We will present the results of these calculations, and the resulting predictions for the charm and bottom quark masses in the MSbar scheme. We report mc(mc) = 1:22(9) GeV and mb(mb) = 4:7(4) GeV. In addition we present resul

Rajiv V. Gavai, Sourendu Gupta, Swagato Mukherjee

We propose a new variant of the operator method for the computation of the equation of state of QCD, which yields positive pressure for all temperatures and all values of temporal lattice spacings. Using this new method, we calculate the continuum limit of pressure, energy density, entropy density, specific heat, and the speed of sound, in quenched QCD, for

Matteo Beccaria, Gian Fabrizio De Angelis, Massimo Campostrini, Alessandra Feo

We study dynamical supersymmetry breaking and the transition point by non-perturbative lattice techniques in a class of two-dimensional N=1 Wess-Zumino model. The method is based on the calculation of rigorous lower bounds on the ground state energy density in the infinite-lattice limit. Such bounds are useful in the discussion of supersymmetry phase transit

Constantia Alexandrou, Petros Dimopoulos, Giannis Koutsou, Hartmut Neff

We present a study of gauge invariant density-density correlators. Density-density correlators probe hadron wave functions and thus can be used to study hadron deformation. Their zero momentum projection requires the computation of all-to-all propagators, which are evaluated with the standard stochastic technique, the dilution method and the stochastic seque

N. Yamada, T. Blum, M. Hayakawa, T. Izubuchi

We present the determination of the light quark masses using electromagnetic splittings of pions and kaons. The meson masses are calculated on $SU(3)\times U(1)$ gauge configurations, where SU(3) gauge fields include sea quark effects of two degenerate flavors and the U(1) gauge fields are incorporated in non-compact form. Possible sources of systematic unce

Eigo Shintani, S. Aoki, N. Ishizuka, K. Kanaya

We carry out a feasibility study toward a lattice QCD calculation of the neutron electric dipole moment (NEDM) in the presence of the $θ$ term using two different approaches. In the first method, we calculate the CP-odd electromagnetic form factor $F_3$, which becomes the NEDM in the zero momentum transfer limit. At the first order in $θ$, we derive a formul

V. G. Bornyakov, M. N. Chernodub, Y. Mori, S. M. Morozov

We present results obtained in QCD with two flavors of non-perturbatively improved Wilson fermions at finite temperature on $16^3 \times 8$ and $24^3 \times 10$ lattices. We determine the transition temperature in the range of quark masses $0.6<m_π/m_ρ<0.8$ at lattice spacing a$\approx$0.1 fm and extrapolate the transition temperature to the continuum and to

Gagan B. Mohanty

We review hadron spectroscopy at BABAR with emphasis on recent results from the studies of the X(3872) state, inclusive charmonia on recoil, double charmonium production, and the broad structure observed at around 4.26 GeV/c^2. These results are preliminary, unless otherwise specified.

A. Monfardini, C. Arnaboldi, C. Brofferio, S. Capelli

Neutrino oscillation experiments have proved that neutrinos are massive particles, but can&#39;t determine their absolute mass scale. Therefore the neutrino mass is still an open question in elementary particle physics. An international collaboration is growing around the project of Microcalorimeter Arrays for a Rhenium Experiment (MARE) for directly measuri

Giorgio Chiarelli

In this paper I present the most recent results of the ongoing searches, mainly from Tevatron Collider experiments, for new physics beyond the Standard Model. While no signal has been seen so far, many analyses are reaching the point in which either a discovery will take place or strong limit on currently popular theories will be set.

C. Filgueiras, Fernando Moraes

In this article we observe that the self-adjoint extension of the Hamiltonian of a particle moving around a shielded cosmic string gives rise to a gravitational analogue of the bound state Aharonov-Bohm effect.

Christian Cherubini, Simonetta Filippi

We discuss the possibility to solve Modern Numerical Relativity problems using finite element methods (FEM). Adopting a &#34;user friendly&#34; software for handling totally general systems of nonlinear partial differential equations, FEMLAB, we model and numerically solve in a short time a Gowdy vacuum spacetime, representing an inhomogeneous cosmology. Res

S. Antoci, D. -E. Liebscher

Kruskal&#39;s extension solves the problem of the arrow of time of the ``Schwarzschild solution&#39;&#39; through combining two Hilbert manifolds by a singular coordinate transformation. We discuss the implications for the singularity problem and the definition of the mass point. The analogy set by Rindler between the Kruskal metric and the Minkowski spaceti

Syed A. Jafar, Sudhir Srinivasa

We investigate the capacity of opportunistic communication in the presence of dynamic and distributed spectral activity, i.e. when the time varying spectral holes sensed by the cognitive transmitter are correlated but not identical to those sensed by the cognitive receiver. Using the information theoretic framework of communication with causal and non-causal

Anil Bazaz, James D. Arthur

This report presents a taxonomy of vulnerabilities created as a part of an effort to develop a framework for deriving verification and validation strategies to assess software security. This taxonomy is grounded in a theoretical model of computing, which establishes the relationship between vulnerabilities, software applications and the computer system resou

Assaf Naor, Gideon Schechtman

We show that any $L_1$ embedding of the transportation cost (a.k.a. Earthmover) metric on probability measures supported on the grid $\{0,1,...,n\}^2\subseteq \R^2$ incurs distortion $Ω(\sqrt{\log n})$. We also use Fourier analytic techniques to construct a simple $L_1$ embedding of this space which has distortion $O(\log n)$.

Jurij Smakov, Erik Sorensen

The scaling of the conductivity at the superfluid-insulator quantum phase transition in two dimensions is studied by numerical simulations of the Bose-Hubbard model. In contrast to previous studies, we focus on properties of this model in the experimentally relevant thermodynamic limit at finite temperature T. We find clear evidence for deviations from w_k-s

Sara Ianeselli, Chiara Menotti, Augusto Smerzi

According to the Landau criterion for superfluidity, a Bose-Einstein condensate flowing with a group velocity smaller than the sound velocity is energetically stable to the presence of perturbing potentials. We found that this is strictly correct only for vanishingly small perturbations. The superfluid critical velocity strongly depends on the strength and s

A. Kolakowska, M. A. Novotny, P. S. Verma

We study two-component growth that mixes random deposition (RD) with a correlated growth process that occurs with probability p. We find that these composite systems are in the universality class of the correlated growth process. For RD blends with either Edwards-Wilkinson of Kardar-Parisi-Zhang processes, we identify a nonuniversal parameter in the universa

C. Stambaugh, H. B. Chan

We measure the spectral densities of fluctuations of an underdamped nonlinear micromechanical oscillator. By applying a sufficiently large periodic excitation, two stable dynamical states are obtained within a particular range of driving frequency. White noise is injected into the excitation, allowing the system to overcome the activation barrier and switch

Sakuntala Chatterjee, Mustansir Barma

We study the dynamics of a system of hard-core particles sliding downwards on a one dimensional fluctuating interface, which in a special case can be mapped to the problem of a passive scalar advected by a Burgers fluid. Driven by the surface fluctuations, the particles show a tendency to cluster, but the hard-core interaction prevents collapse. We use numer

H. Benthien, F. H. L. Essler, A. Grage

We consider the one-dimensional extended Hubbard model in the presence of an explicit dimerization $δ$. For a sufficiently strong nearest neighbour repulsion we establish the existence of a quantum phase transition between a mixed bond-order wave and charge-density wave phase from a pure bond-order wave phase. This phase transition is in the universality cla

Francisco J. Solis, Galen T. Pickett

Mixtures of near-symmetric oppositely charged components with strong attractive short range interactions exhibit ordered lamellar phases at low temperatures. In the strong segregation limit the state of these systems can be described by the location of the interfaces between the components. It has previously been shown that these systems are stable against s

W. Yu, B. Liang, R. L. Greene

We remeasured the magnetic field dependence of the low-temperature specific heat of the electron-doped superconductor Pr1.85Ce0.15CuO4 (T_C=22\pm 2K) under a different measurement procedure. Under field-cooling, the electronic specific heat follows C_{el}(H, T)=γ(H)T from 4.5K down to 1.8K. In the field range H_{C1}<H<0.5 H_{C2}, the Sommerfeld coefficient γ

V. Barsegov, D. Thirumalai

We investigate the folding and forced-unbinding transitions of adsorbed semiflexible polymer chains using theory and simulations. These processes describe biologically relevant phenomena that include adhesive interactions between proteins and tethering of receptors to cell walls. The binding interface is modeled as a solid surface and the worm-like chain is

A. Zorkovska, M. Orendac, J. Sebek, E. Santava

Specific heat of the layered NaxCoO2 (x=0.65, 0.70 and 0.75) oxides has been measured in the temperature range of 3-360 K and magnetic field of 0 and 9 T. The analysis of data, assuming the combined effect of inter-layer superexchange and the phase separation into mesoscopic magnetic domains with localized spins embedded in a matrix with itinerant electronic

S. Bellucci, P. Onorato

We describe the simultaneous effects of the spin-orbit (SO) perturbation and a magnetic field $B$ on a disk shaped quantum dot (QD). {As it is known the} combination of electrostatic forces among the $N$ electrons confined in the QD and the Pauli principle can induce a spin polarization when $B$ (applied in the direction orthogonal to the QD) is above a thre

M. Dumm, B. Gorshunov, M. Dressel, T. Matsumura

The infrared optical conductivity of intermediate valence compound TmSe reveals clear signatures for hybridization of light $d$- and heavy f-electronic states with m* ~ 1.6 m_0 and m* ~ 16 m_0, respectively. At moderate and high temperatures, the metal-like character of the heavy carriers dominate the low-frequency response while at low temperatures (T_N < T

G. Fedorov, S. I. Maslovski, A. V. Dorofeenko, A. P. Vinogradov

An experimental evidence of subwavelength imaging with a &#34;lens&#34;, which is a uniaxial negative permittivity wire medium slab, is reported. The slab is formed by gratings of long thin parallel conducting cylinders. Taking into account the anisotropy and spatial dispersion in the wire medium we theoretically show that there are no usual plasmons that co

Nicola M. Pugno

In this letter a mathematical model to design nano-bio-inspired hierarchical materials is proposed. An optimization procedure is also presented. Simple formulas describing the dependence of strength, fracture toughness and stiffness on the considered size-scale are derived, taking into account the toughening biomechanisms. Furthermore, regarding nano-grained

Michael C. Mackey, Marta Tyran-Kaminska

We study the temporal approach to equilibrium of the Gibbs&#39; and conditional entropies for both invertible deterministic dynamics as well as non-invertible stochastic systems in the presence of white noise. The conditional entropy will either remain constant or monotonically increase to its maximum of zero. However, the Gibbs&#39; entropy may have a varie

D. H. E. Gross

A short reply to Jarzynski&#39;s comment cond-mat/0509344 on my paper ``Flaw of Jarzynski&#39;s equality when applied to systems with several degrees of freedom&#39;&#39; (cond--mat/0508721) is presented.

Péter Lajkó, Enrico Carlon, Heiko Rieger, Ferenc Iglói

We use extensive density matrix renormalization group (DMRG) calculations to explore the phase diagram of the random S=1 antiferromagnetic Heisenberg chain with a power-law distribution of the exchange couplings. We use open chains and monitor the lowest gaps, the end-to-end correlation function, and the string order parameter. For this distribution at weak

S. S. Murzin, A. G. M. Jansen

Reply to A. M. M. Pruisken and I. S. Burmistrov: cond-mat/0504763

M. Malki, M. micoulaut, F. Chaimbault, Y. vaills

Non-Arrhenius behaviour and fast increase of the ionic conductivity is observed for a number of potassium silicate glasses $(1-x)SiO_2-xK_2O$ with potassium oxide concentration larger than a certain value $x=x_c=0.14$. Recovering of Arrhenius behaviour is provided by the annealing that enhances densification. Conductivity furthermore obeys a percolation law

Kalobaran Maiti, U. Manju, Sugata Ray, Priya Mahadevan

We investigate the electronic structure of Ca1-xSrxVO3 using careful state-of-the-art experiments and calculations. Photoemission spectra using synchrotron radiation reveal a hitherto unnoticed polarization dependence of the photoemission matrix elements for the surface component leading to a substantial suppression of its intensity. Bulk spectra extracted w

Rolf-Juergen Merath, Udo Seifert

The thermal fluctuation spectrum of a fluid membrane coupled harmonically to a solid support by an array of tethers is calculated. For strong tethers, this spectrum exhibits non-monotonic, anisotropic behavior with a relative maximum at a wavelength about twice the tether distance. The root mean square displacement is evaluated to estimate typical membrane d

Adi Salomon, Olga Girshevitz, David Cahen, Till Bocking

Electron transport through Si-C bound alkyl chains, sandwiched between n-Si and Hg, is characterized by two distinct types of barriers, each dominating in a different voltage range. At low voltage, current depends strongly on temperature but not on molecular length, suggesting transport by thermionic emission over a barrier in the Si. At higher voltage, the

Mladen Georgiev

The existence of bound excited states of two-electron centers loosely trapped in an anion vacancy, the F&#39; centers, is a long-standing problem of color center physics. Optical absorption bands attributed to F&#39; centers in NaI and NaBr as observed by Baldacchini et al. seem to confirm the existence of F&#39; bound snglet states. Nevertheless, a paper by

Akira Endo, Yasuhiro Iye

We report quantitative analysis of positive magnetoresistance (PMR) for unidirectional-lateral-superlattice samples with relatively small periods (a=92-184 nm) and modulation amplitudes (V_0=0.015-0.25 meV). By comparing observed PMR&#39;s with ones calculated using experimentally obtained mobilities, quantum mobilities, and V_0&#39;s, it is shown that contr

Shutaro Chiba, Yoshiyuki Ono

The effect of the electron-electron (e-e) interaction on the Peierls lattice distortions due to the electron-lattice (e-l) interaction is studied in the two-dimensional Peierls-Hubbard model, treating the fluctuation of e-e interaction around the Hartree-Fock solution within the 2nd order perturbation theory. In our previous work, using the Hartree-Fock appr

S. Kalavathi, J. Janaki, T. N. Sairam, Awadhesh Mani

Some new members of a Ruthenocuprate (2212) series have been synthesized by Mn substitution for Ru in Gd1.4Ce0.6Sr2RuCu2O10 . Characterisation by XRD phase analysis followed by Rietveld refinement has been carried out. IR spectroscopy studies and Rietveld refinements are consistent with substitution of Mn at Ru site. XRD studies indicate changes in structura

Thomas Ihle, Erkan Tuzel, Daniel M. Kroll

A thermodynamically consistent particle-based model for fluid dynamics with continuous velocities and a non-ideal equation of state is presented. Excluded volume interactions are modeled by means of biased stochastic multiparticle collisions which depend on the local velocities and densities. Momentum and energy are exactly conserved locally. The equation of

A. Gozar, G. Blumberg

We study low temperature Raman data on phononic and magnetic excitations in SrCu_2(BO_3)_2. Regarding the former, in the 0 to 350 cm-1 range we find several pairs of quasi-degenerate modes which have different symmetries. Group theoretical analysis suggests that the existence of these modes is related to quite different atomic vibrational pattern, i.e. in-pl

O. V. Zhirov, D. L. Shepelyansky

Using the methods of quantum trajectories we study numerically the phenomenon of quantum synchronization in a quantum dissipative system with periodic driving. Our results show that at small values of Planck constant $\hbar$ the classical devil&#39;s staircase remains robust with respect to quantum fluctuations while at large $\hbar$ values synchronization p

V. M. Silkin, I. A. Nechaev, E. V. Chulkov, P. M. Echenique

Induced charge-density (ICD) oscillations at the Cu(111) surface caused by an external impurity are studied within linear response theory. The calculation takes into account such properties of the Cu(111) surface electronic structure as an energy gap for three-dimensional (3D) bulk electrons and a $s-p_z$ surface state that forms two-dimensional (2D) electro

Veronica Cerletti, Oliver Gywat, Daniel Loss

We show that electron recombination using positively charged excitons in single quantum dots provides an efficient method to transfer entanglement from electron spins onto photon polarizations. We propose a scheme for the production of entangled four-photon states of GHZ type. From the GHZ state, two fully entangled photons can be obtained by a measurement o

Snezana Stanimirovic, Alberto D. Bolatto, Karin Sandstrom, Adam K. Leroy

We present infrared observations of the young, oxygen-rich supernova remnant 1E 0102.2-7219 (E0102) in the Small Magellanic Cloud, obtained with the Spitzer Space Telescope. The remnant is detected at 24 um but not at 8 or 70 um and has a filled morphology with two prominent filaments. We find evidence for the existence of up to 8x10^-4 Msolar of hot dust (T

Ping Zhao, Jonathan E. Grindlay, JaeSub Hong, Silas Laycock

The ChaMPlane survey to identify and analyze the serendipitous X-ray sources in deep Galactic plane fields incorporates the ChaMPlane Optical Survey, which is one of NOAO&#39;s Long-term Survey Programs. We started this optical imaging survey in March 2000 and completed it in June 2005. Using the NOAO 4-m telescopes with the Mosaic cameras at CTIO and KPNO,

S. Laycock, J. Grindlay, M. van den Berg, P. Zhao

We searched for infrared counterparts to the cluster of X-ray point sources discovered by Chandra in the Galactic Center Region (GCR). While the sources could be white dwarfs, neutron stars, or black holes accreting from stellar companions, their X-ray properties are consistent with magnetic Cataclysmic Variables, or High Mass X-ray Binaries (HMXB) at low ac

JaeSub Hong, Maureen van den Berg, Eric M. Schlegel, Jonathan E. Grindlay

We describe the X-ray analysis procedure of the on-going Chandra Multiwavelength Plane (ChaMPlane) survey and report the initial results from the analysis of 15 selected anti-Galactic center observations (90 deg < l < 270 deg). We describe the X-ray analysis procedures for ChaMPlane using custom-developed analysis tools appropriate for Galactic sources but a

J. E. Grindlay, J. Hong, P. Zhao, S. Laycock

We introduce the Chandra Multiwavelength Plane (ChaMPlane) Survey, designed to measure or constrain the populations of low-luminosity (Lx > ~10^31 erg/s) accreting white dwarfs, neutron stars and stellar mass black holes in the Galactic Plane and Bulge. ChaMPlane incorporates two surveys, X-ray (Chandra) and optical (NOAO 4m-Mosaic imaging), and a followup s

Andrei Mesinger

We develop and assess the potential of several powerful techniques, designed to investigate the details of reionization. First, we present a procedure to probe the neutral fraction, x_HI, using the Lyman alpha transmission statistics of high-redshift (z > 6) sources. We find that only tens of bright quasar spectra could distinguish between x_HI ~ 1 and x_HI

David R. Law, Charles C. Steidel, Dawn K. Erb

We investigate the ability of infrared integral-field spectrographs to map the velocity fields of high redshift galaxies, presenting a formalism which may be applied to any telescope and imaging spectrograph system. We discuss the 5-sigma limiting line fluxes which current integral-field spectrographs will reach, and extend this discussion to consider future

S. Turcotte, O. Richard

Diffusion in cool B stars of the main sequence has been shown to strongly affect opacities and convection in cool B stars of the main sequence. We show here that diffusion in B stars maintains or enhances the excitation of pulsations in these stars. This result conflicts with observations as cool B stars that show evidence of diffusion, the HgMn stars, are s

Sebastian Heinz

We model the observed size and brightness of the VLBA radio core of the jet in Cygnus X-1 to derive an expression for the jet power as a function of basic jet parameters. We apply this expression to recent constraints on the jet power from observations of a large scale shocked shell around the source by Gallo et al. 2005, which leads us to a set of alternati

Yee Yee Oo, K. N. Nagendra, Sharath Ananthamurthy, G. Ramachandran

The polarization of radiation by scattering on an atom embedded in combined external quadrupole electric and uniform magnetic fields is studied theoretically. Analytic formulae are derived for the scattering phase matrix. Limiting cases of scattering under Zeeman effect, and Hanle effect in weak magnetic fields are discussed.

Vincent Boucher

The effect of spatial variations of the Newton constant on the cosmic microwave background is studied. Constraints on the strong equivalence principle violation at the recombination time are then obtained with the help of WMAP data and of the standard theory of big-bang nucleosynthesis.

Emma L. Allard, Reynier F. Peletier, Johan H. Knapen

The SAURON integral field spectrograph was used to observe the central area of the barred spiral galaxy M100 (NGC 4321). M100 contains a nuclear ring of star formation, fueled by gas channeled inward by the galaxy&#39;s bar. We present maps of emission line strengths, absorption line strength indices, and the gas velocity dispersion across the field. The H b

L. M. Buson, E. Bertone, A. Buzzoni, G. Carraro

Relying on U,B imagery at the Italian Telescopio Nazionale Galileo (TNG), we report here the discovery of a sample of 13 new UV-bright post-HB candidate stars in the field of the galactic open cluster NGC 6791. Owing to its super-solar metal content ([Fe/H]>0.2 dex) and estimated age (t> 8 Gyr), this cluster represents the nearest and ideal stellar aggregate

H. Beuther, Q. Zhang, M. J. Reid, T. R. Hunter

Submillimeter Array observations of Orion-KL at 1&#39;&#39; resolution in the 440mu/690GHz band reveal new insights about the continuum and line emission of the region. The 440mu continuum flux density measurement from source I allows us to differentiate among the various proposed physical models: Source I can be well modeled by a ``normal&#39;&#39; protoste

Sylvie F. Beaulieu, Kenneth C. Freeman, Claude Carignan, Felix J. Lockman

An \hi survey of 10 dE/dS0 galaxies in the nearby Sculptor and Centaurus A groups was made using the Australia Telescope Compact Array (ATCA). The observed galaxies have accurate distances derived by Jerjen et al (1998; 2000b) using the surface brightness fluctuation technique. Their absolute magnitudes are in the range $-9.5 > M_B > -15.3$. Only two of the

C. W. Mauche, P. Gorenstein

We have searched the region surrounding the Crab Nebula for the existence of a shock wave with the imaging instruments of the Einstein Observatory. The search is complicated by the scattering of nebula and pulsar X-rays from the imperfectly polished surfaces of the telescope mirror, as well as from interstellar grains along the line of sight. Both of these e

B. Mobasher, M. Dickinson, H. C. Ferguson, M. Giavalisco

We present results from a search for high-redshift J--band ``dropout&#39;&#39; galaxies in the portion of the GOODS southern field that is covered by extremely deep imaging from the Hubble Ultradeep Field (HUDF).Using observations at optical, near-infrared and mid-infrared wavelengths from the Hubble and Spitzer Space Telescopes and the ESO-VLT, we search fo

Simon Portegies Zwart, Steve McMillan

We consider the formation of the recently discovered ``hot Jupiter&#39;&#39; planet orbiting the primary component of the triple star system HD188753. Although the current outer orbit of the triple is too tight for a Jupiter-like planet to have formed and migrated to its current location, the binary may have been much wider in the past. We assume here that t

Naofumi Ohnishi, Kei Kotake, Shoichi Yamada

We have numerically studied the instability of the spherically symmetric standing accretion shock wave against non-spherical perturbations. We have in mind the application to the collapse-driven supernovae in the post bounce phase, where the prompt shock wave generated by core bounce is commonly stalled. We take an experimental stand point in this paper. Usi

L. C. Prochaska, James A. Rose, Ricardo P. Schiavon

We have investigated the abundance of calcium in early-type galaxies by measuring the strength of the Ca I 4227 absorption line in their integrated spectra. The database used is the large sample of early-type galaxy integrated spectra in Caldwell, Rose, & Concannon (2003). We have measured Ca abundances from the Ca I 4227 feature both by using the Lick Ca422

S. E. Meidt, R. J. Rand

Spiral galaxies displaying molecule-dominated ISMs are potential candidates for pattern speed determination by the Tremaine-Weinberg (TW) method (1984); the molecular gas of such galaxies, as traced by CO emission, is argued to approximately obey the continuity equation on orbital timescales--a key requirement of the method. We continue our work on this appl

Rachel A. Osten, Suzanne L. Hawley, Timothy S. Bastian, I. Neill Reid

We explore the radio emission from the M9 dwarf, TVLM513-46546, at multiple radio frequencies, determining the flux spectrum of persistent radio emission, as well as constraining the levels of circular polarization. Detections at both 3.6 and 6 cm provide spectral index measurement $α$ (where S$_ν \propto ν^α$) of $-0.4\pm0.1$. A detection at 20 cm suggests

W. Wang, C. S. J. Pun, K. S. Cheng

we study the possibility of pulsar winds in the Galactic center (GC) to produce the 511 keV line. We propose that there may exist three possible scenarios of pulsar winds as the positron sources: normal pulsars; rapidly spinning strongly magnetized neutron stars in GRB progenitors; a population of millisecond pulsars in the Galactic center region. These $e^\

Felipe Menanteau, Holland C. Ford, Veronica Motta, Narciso Benitez

We present a morphological analysis of distant field galaxies using the deep ACS images from the public parallel NICMOS observations of the Hubble Ultra Deep Field obtained in the F435W (B), F606W (V), F775W (i) and F850LP (z) filters. We morphologically segregate galaxies using a combination of visual classification and objective machine based selection. We

S. V. Vadawale, J. Hong, J. E. Grindlay, G. Skinner

EXIST is being studied as the Black Hole Finder Probe, one of the 3 Einstein Probe missions under NASA&#39;s Beyond Einstein program. The major science goals for EXIST include highly sensitive full-sky hard X-ray survey in a very wide energy band of 5-600 keV. The scientific requirements of wide energy band (10-600 keV for the High Energy Telescope considere

J. Hong, A. Copete, J. E. Grindlay, S. V. Vadawale

We outline our plan to develop ProtoEXIST, a balloon-borne prototype experiment for the Energetic X-ray Imaging Survey Telescope (EXIST) for the Black Hole Finder Probe. EXIST will consist of multiple wide-field hard X-ray coded-aperture telescopes. The current design of the EXIST mission employs two types of telescope systems: high energy telescopes (HETs)

G. Lodato, E. Delgado-Donate, C. J. Clarke

In this paper we discuss the nature and the possible formation scenarios of the companion of the brown dwarf 2MASS 1207334-393254. We initially discuss the basic physical properties of this object and conclude that, although from its absolute mass ($5M_{\rm Jup}$), it is a planetary object, in terms of its mass ratio $q$ and of its separation $a$ with respec

Kate Land, Joao Magueijo

We investigate two possible explanations for the large-angle anomalies in the Cosmic Microwave Background (CMB): an intrinsically anisotropic model and an inhomogeneous model. We take as an example of the former a Bianchi model (which leaves a spiral pattern in the sky) and of the latter a background model that already contains a non-linear long-wavelength p

Zdenek Mikulasek, Jiri Krticka, Juraj Zverko, Jozef Ziznovsky

We present a principle component analysis of multicolour light variations of the He-strong magnetic chemically peculiar star HD 37776 and its (O-C) diagram. The period increase rate found, (dP/dt) / P = 5.5 x 10^{-6}/year, is consistent with the conception of angular momentum loss through magnetically confined stellar wind.

Hideyuki Umeda, Nozomu Tominaga, Keiichi Maeda, Ken&#39;ichi Nomoto

We investigate a &#34;hypernova&#34; model for gamma-ray bursts (GRBs), i.e., massive C+O star model with relativistic jets. In this model, non-thermal precursors can be produced by the &#34;first&#34; relativistic shell ejected from the star. Main GRBs are produced behind the &#34;first&#34;-shell by the collisions of several relativistic shells. They becom

M. Sachkov, T. Ryabchikova, S. Bagnulo, I. Ilyin

We present results of the radial velocity (RV) analysis of spectroscopic time-series observations of the roAp star HD24712 (HR1217) which were carried out simultaneously with the Canadian MOST mini-satellite photometry. Only lines of the rare-earth elements (REE) show substantial amplitudes of RV pulsations. Based on new Zeeman measurements we found differen