October 2006 arXiv papers — page 13

Yum-Tong Siu

On August 5, 2005 in the American Mathematical Society Summer Institute on Algebraic Geometry in Seattle and later in several conferences I gave lectures on my analytic proof of the finite generation of the canonical ring for the case of general type. After my lectures many people asked me for a copy of the slides which I used for my lectures. Since my slide

Peter Balazs

In this paper we will look at the connection of frames and finite dimensionality. A main focus is to present simple algorithms and make them available online. The main result is a way to 'switch' between different frames, giving an algorithm to calculate the coefficients of one frame given the analysis of another frame using their cross-Gram matrix.

Christian Krattenthaler

The $M$-triangle of a ranked locally finite poset $P$ is the generating function $\sum_{u,w\in P} ^{}μ(u,w) x^{\rk u}y^{\rk w}$, where $μ(.,.)$ is the Möbius function of $P$. We compute the $M$-triangle of Armstrong's poset of $m$-divisible non-crossing partitions for the root systems of type $E_7$ and $E_8$. For the other types except $D_n$ this had bee

Halvard Fausk, Daniel C. Isaksen

For every stable model category $\mathcal{M}$ with a certain extra structure, we produce an associated model structure on the pro-category pro-$\mathcal{M}$ and a spectral sequence, analogous to the Atiyah-Hirzebruch spectral sequence, with reasonably good convergence properties for computing in the homotopy category of pro-$\mathcal{M}$. Our motivating exam

Paul Bressler

We give a natural obstruction theoretic interpretation to the first Pontryagin class in terms of Courant algebroids. As an application we calculate the class of the stack of algebras of chiral differential operators. In particular, we establish the existence and uniqueness of the chiral de Rham complex.

Riccardo Benedetti, Francesco Bonsante

We develop a ``canonical Wick rotation-rescaling theory in 3-dimensional gravity''. This includes: (a) A simultaneous classification that shows how generic maximal globally hyperbolic spacetimes of constant curvature, which admit a complete Cauchy surface (in particular a compact one), as well as complex projective structures on arbitrary surfaces, a

Ralph M. Kaufmann

Using a cell model for the little discs operad in terms of spineless cacti we give a minimal common topological operadic formalism for three a priori disparate algebraic structures: (1) a solution to Deligne's conjecture on the Hochschild complex, (2) the Hopf algebra of Connes and Kreimer, and (3) the string topology of Chas and Sullivan.

Tirthabir Biswas, Robert Brandenberger, Anupam Mazumdar, Warren Siegel

In hep-th/0508194 it was shown how non-perturbative corrections to gravity can resolve the big bang singularity, leading to a bouncing universe. Depending on the scale of the non-perturbative corrections, the temperature at the bounce may be close to or higher than the Hagedorn temperature. If matter is made up of strings, then massive string states will be

Jen-Chi Lee

We identify spacetime symmetry charges of the bosonic sector of 10D superstring theory from an infinite number of zero-norm states (ZNS) in the old covariant first quantized string spectrum. We give evidences to support this identification. These include supersymmetric sigma-model calculation, 2D super-Liouville theory calculation and, most importantly, thre

Angel Paredes

The addition of fundamental degrees of freedom to a theory which is dual (at low energies) to N=2 SYM in 1+3 dimensions is studied. The gauge theory lives on a stack of Nc D5 branes wrapping an S^2 with the appropriate twist, while the fundamental hypermultiplets are introduced by adding a different set of Nf D5-branes. In a simple case, a system of first or

Andrea Cappelli, Ivan D. Rodriguez

The U(N) Maxwell-Chern-Simons matrix gauge theory is proposed as an extension of Susskind's noncommutative approach. The theory describes D0-branes, nonrelativistic particles with matrix coordinates and gauge symmetry, that realize a matrix generalization of the quantum Hall effect. Matrix ground states obtained by suitable projections of higher Landau l

Hua Bai, J. X. LU, Shibaji Roy

Unlike BPS $p$-brane, non-supersymmetric (non-susy) $p$-brane could be either charged or chargeless. As envisaged in [hep-th/0503007], we construct an intersecting non-susy $p$-brane with chargeless non-susy $q$-brane by taking T-dualities along the delocalized directions of the non-susy $q$-brane solution delocalized in $(p-q)$ transverse directions (where

R. A. Reid-Edwards

Complimentary geometric and non-geometric consistent reductions of IIB supergravity are studied. The geometric reductions on the identified group manifold X are found to have a gauge symmetry with Lie algebroid structure, generalising that found in similar reductions of the Bosonic string theory and eleven-dimensional supergravity. Examples of such compactif

Peter Orland

In axial gauge, the (2+1)-dimensional SU($N$) Yang-Mills theory is equivalent to a set of (1+1)-dimensional integrable models with a non-local coupling between charge densities. This fact makes it possible to determine the static potential between charges at weak coupling in an anisotropic version of the theory, and understand features of the spectrum.

Ji-Feng Yang

Based on the effective field theory philosophy, a universal form of the scaling laws could be easily derived with the scaling anomalies naturally clarified as the decoupling effects of underlying physics. In the novel framework, the conventional renormalization group equations and Callan-Symanzik equations could be reproduced as special cases and a number of

Mar Bastero-Gil Arjun Berera

Warm inflation scenarios are studied with the dissipative coefficient computed in the equilibrium approximation. Use is made of the analytical expressions available in the low temperature regime with focus on the possibility of achieving strong dissipation within this approximation. Two different types of models are examined: monomial or equivalently chaotic

J. Braun, H. Gies, H. J. Pirner

We study SU(2) Yang-Mills theory at finite temperature in the framework of the functional renormalization group. We concentrate on the effective potential for the Polyakov loop which serves as an order parameter for confinement. In this first status report, we focus on the behaviour of the effective Polyakov-loop potential at high temperatures. In addition t

Wolfgang Hollik, Michael Rauch

Associated production of a Higgs boson with a heavy, i.e. top or bottom, quark-anti-quark pair provide observation channels for Higgs bosons at the LHC which can be used to measure the respective Yukawa couplings. For the light supersymmetric Higgs boson we present SUSY-QCD corrections at the one-loop level, which constitute a significant contribution to the

J. H. Kuhn, A. Scharf, P. Uwer

Top-quark physics plays an important role at hadron colliders such as the Tevatron collider at Fermilab or the upcoming Large Hadron Collider (LHC) at CERN. Given the planned experimental precision, detailed theoretical predictions are mandatory. In this article we present analytic results for the complete electroweak corrections to gluon induced top-quark p

R. N. Faustov, I. V. Gorbacheva, A. P. Martynenko

The contribution of the proton polarizability to the ground state hyperfine splitting in the hydrogen atom is evaluated on the basis of isobar model and evolution equations for the parton distributions. The contributions of the Born terms, vector meson exchanges and nucleon resonances are taken into account in the construction of the proton polarized structu

Jens Braun, Hans-Jürgen Pirner

Finite temperature modifies the running of the QCD coupling alpha_s(k,T) with resolution k. After calculating the thermal quark and gluon masses selfconsistently, we determine the quark-quark and quark-gluon cross sections in the plasma based on the running coupling. We find that the running coupling enhances these cross sections by factors of two to four de

S. Baek, J. H. Jeon, C. S. Kim, Chaehyun Yu

We consider the leptophobic $Z^\prime$ model which can appear naturally in the flipped SU(5) or string-inspired $E_6$ models. This model can be constrained by measurements of the $B\to M ν\barν$ decays and $Δm_s$. We find that although the latter give much stronger constraints on the coupling than the former, they are complementary to each other.

Taekoon Lee

The bilocal expansion of Borel transform provides an efficient way of Borel resummation with low order perturbations in QCD. Its applications to the heavy quark pole mass, static potential, and lattice calculation are reviewed.

Adam Falkowski, Manuel Perez-Victoria

We investigate the relation between holographic calculations in 5D and the Migdal approach to correlation functions in large N theories. The latter employs Pade approximation to extrapolate short distance correlation functions to large distances. We make the Migdal/5D relation more precise by quantifying the correspondence between Pade approximation and the

M. Gockeler, Ph. Hageler, R. Horsley, Y. Nakamura

The electromagnetic form factors provide important hints for the internal structure of the nucleon and continue to be of major interest for experimentalists. For an intermediate range of momentum transfers the form factors can be calculated on the lattice. However, reliability of the results is limited by systematic errors due to the required extrapolation t

Philippe de Forcrand, Urs Wenger

We investigate the Gross-Neveu model on the lattice at finite temperature and chemical potential in the limit of an infinite number of fermion flavours. We check the universality of the continuum limit of staggered and overlap fermions at finite temperature and chemical potential. We show that at finite density a recently discovered phase of cold baryonic ma

Elliott Cheu

The KTeV experiment has carried out a broad program of studies of rare kaon decays. In this paper we present results on KL -> pi0 gamma gamma, KL -> pi0 e+ e- gamma and KL -> pi0 pi0 gamma. These decays provide a window for testing chiral perturbation theory at O(p^6). We find BR(KL-> pi0 pi0 gamma) = (1.30 +/- 0.03 +/- 0.04)E-6, BR(KL-> pi0 e+ e- gamma) = (

J. Olsson

Exclusive $ρ^{\circ}$ photoproduction has been measured with high statistics by the H1 Collaboration. The kinematical range is $20 < W < 90$ GeV, $|t|<3$ GeV$^2$ and $Q^2<4$ GeV$^2$. Cross sections are measured differentially in $W$ and $t$ and allow the extraction of the Pomeron trajectory, for the first time using $ρ^{\circ}$ photoproduction data of one si

H1 Collaboration

Measurements are presented of diffractive open charm production at HERA. The event topology is given by ep -> eX Y where the system X contains at least one charmed hadron and is well separated by a large rapidity gap from a leading low-mass proton remnant system Y. Two analysis techniques are used for the cross section measurements. In the first, the charm q

P. Azzurri

Hadronic events at the Z pole have been investigated in search for Colour Reconnection effects and QCD coherence. Colour Reconnection effects are searched for in three-jet events and the data results are compared to the predictions of different Monte Carlo models. QCD colour coherence effects are tested through the multiplicity distributions of hadrons with

Thomas W. Baumgarte, Niall Ó Murchadha, Harald P. Pfeiffer

We study the appearance of multiple solutions to certain decompositions of Einstein&#39;s constraint equations. Pfeiffer and York recently reported the existence of two branches of solutions for identical background data in the extended conformal thin-sandwich decomposition. We show that the Hamiltonian constraint alone, when expressed in a certain way, admi

William Hanan, Eugen Radu

We investigate the geodesic motion in $D-$dimensional Majumdar-Papapetrou multi-black hole spacetimes and find that the qualitative features of the D=4 case are shared by the higher dimensional configurations. The motion of timelike and null particles is chaotic, the phase space being divided into basins of attraction which are separated by a fractal boundar

S. K. Srivastava

Here, an accelerated phantom model for the late universe is explored, which is free from future singularity. It is interseting to see that this model exhibits strong curvature for all time in future, unlike models with `big-rip singularity&#39; showing high curvature near singularity time only. So, quantum gravity effects grow dominant as time increases in t

Cheng Chang, Stark Draper, Anant Sahai

Distributed source coding is traditionally viewed in the block coding context -- all the source symbols are known in advance at the encoders. This paper instead considers a streaming setting in which iid source symbol pairs are revealed to the separate encoders in real time and need to be reconstructed at the decoder with some tolerable end-to-end delay usin

Jeremy D. Schmit, Alex J. Levine

Conjugated polymers are observed to aggregate in solution. To account for this observation we propose a inter-chain binding mechanism based on the intermolecular tunneling of the delocalized $π$-electrons occurring at points where the polymers cross. This tunneling mechanism predicts specific bound structures of chain that depend on whether they are semicond

Lu Li, Yayu Wang, J. G. Checkelsky, M. J. Naughton

The depairing (upper critical) field $H_{c2}$ in hole-doped cuprates has been inferred from magnetization curves $M$-$H$ measured by torque magnetometry in fields $H$ up to 45 T. We discuss the implications of the results for the pair binding energy, the Nernst onset temperature, fluctuations and the nature of the Meissner transition at $T_c$.

Y. Onose, N. P. Ong, C. Petrovic

In CeCoIn$_5$, the thermal conductivity $κ_{xx}$ and Hall conductivity $κ_{xy}$ below $T_c$ display large anomalies below $T_c$. The strong suppression of the anomalies in weak fields implies the existence of long-lived quasiparticles. We also discuss briefly the Wiedemann-Franz ratio and the existence of a strongly field-dependent spin-fluctuation heat curr

L. Velazquez, F. Guzman

Microcanonical description is characterized by the presence of an internal symmetry closely related with the dynamical origin of this ensemble: the reparametrization invariance. Such symmetry possibilities the development of a non Riemannian geometric formulation within the microcanonical description of an isolated system, which leads to an unexpected genera

N. Logoboy, W. Joss

The model of diamagnetic phase transition in beryllium which takes into account the quasi 2-dimensional shape of the Fermi surface of beryllium is proposed. It explains correctly the recent experimental data on observation of non-homogeneous phase in beryllium at the conditions of strong dHvA effect when the strong correlation of electron gas results in inst

D. J. Scalapino

Numerical studies of the two-dimensional Hubbard model have shown that it exhibits the basic phenomena seen in the cuprate materials. At half-filling one finds an antiferromagnetic Mott-Hubbard groundstate. When it is doped, a pseudogap appears and at low temperature d-wave pairing and striped states are seen. In addition, there is a delicate balance between

Yuriy V. Pershin, Carlo Piermarocchi

Photocurrent generation is studied in a system composed of a quantum wire with side-coupled quantum rings. The current generation results from the interplay of the particular geometry of the system and the use of circularly polarized radiation. We study the energy-momentum conservation for optical transitions involving electrons moving forwards and backwards

Pedro A. Orellana, Gustavo A. Lara, Enrique V. Anda

Electron tunneling through quantum-dots side coupled to a quantum wire, in equilibrium and nonequilibrium Kondo regime, is studied. The mean-field finite-$U$ slave-boson formalism is used to obtain the solution of the problem. We have found that the transmission spectrum shows a structure with two anti-resonances localized at the renormalized energies of the

X. C. Zhang, G. Scott, H. W. Jiang

Resistively detected nuclear magnetic resonance (NMR) is observed inside the ring-like structure, with a quantized Hall conductance of 6e^2/h, in the phase diagram of a two subband electron system. The NMR signal persists up to 400 mK and is absent in other states with the same quantized Hall conductance. The nuclear spin-lattice relaxation time, T1, is foun

S. Komineas, N. R. Cooper

We study the ground states of rotating atomic Bose-Einstein condensates with dipolar interactions. We present the results of numerical studies on a periodic geometry which show vortex lattice ground states of various symmetries: triangular and square vortex lattices, &#34;stripe crystal&#34; and &#34;bubble crystal&#34;. We present the phase diagram (for sys

I. Vilfan, D. Mihailovic

The properties of Mo_6S_3I_6 nanowires were investigated with ab initio calculations based on the density-functional theory. The molecules build weakly coupled one-dimensional chains with three sulfur atoms in the bridging planes between the Mo octahedra, each dressed with six iodines. Upon uniaxial strain along the wires, each bridging plane shows two energ

Claire Levelut, Rozenn Le Parc, Annelise Faivre, Bernard Champagnon

We studied a set of float glass samples prepared with different fictive temperature by previous annealing around the glass transition temperature. We compared the results to previous measurements on a series of amorphous silica samples, also prepared with different fictive temperature. We showed that the modifications on the structure at a local scale are ve

Marhoun Ferhat, Kanji Yoh

Single Crystalline Fe3-deltaO4 (0<=delta<=0.33) films have been epitaxially grown on InAs (001) substrates by molecular beam epitaxy using O2 as source of active oxygen. Under optimum growth conditions in-situ real time reflection high-energy electron diffraction patterns along with ex-situ atomic force microscopy indicated the (001) Fe3-deltaO4 to be grown

A. D. Giddings, T. Jungwirth, B. L. Gallagher

Exhibiting antiferromagnetic interlayer coupling in dilute magnetic semiconductor multilayers is essential for the realisation of magnetoresistances analogous to giant magnetoresistance in metallic multilayer structures. In this work we use a mean-field theory of carrier induced ferromagnetism to explore possible (Ga,Mn)As based multilayer structures that mi

A. D. Chepelianskii, D. L. Shepelyansky

On a basis of extensive analytical and numerical studies we show that a linear-polarized microwave field creates a stationary magnetization in mesoscopic ballistic quantum dots with two-dimensional electron gas being at a thermal equilibrium. The magnetization is proportional to a number of electrons in a dot and to a microwave power. Microwave fields of mod

Yuan Li, You-Quan Li

The density matrix formalism is applied to calculate the spin-relaxation time for two-dimensional systems with a hierarchy of spin-orbit couplings, such as Rashba-type, Dresselhaus-type and so on. It is found that the spin-relaxation time can be infinite if those coupling strengths $α$, $β$, $γ_1$ and $γ_2$ satisfy either condition (i) $α=β, γ_1=0$ or (ii) $

Jacques Pelous, Claire Levelut

Comparison of the internal friction at hypersonic frequencies between a few K and the glass transition temperature Tg for various glasses brings out general features. At low temperature, internal friction is only weakly dependent on the material. At high temperature but still below Tg the internal friction for strong glasses shows a T-independent plateau in

A. W. Rushforth, A. D. Giddings, K. W. Edmonds, R. P. Campion

We have measured the Anisotropic Magnetoresistance (AMR) of ultra thin (5nm) Ga(0.95)Mn(0.05)As films. We find that the sign of the AMR can be positive or negative, which may depend on the direction of the current with respect to the crystal. At low temperatures, transport measurements and SQUID magnetometry suggest that the magnetisation has a component poi

Oleg Zaitsev

Representing an ensemble of random lasers with an ensemble of random matrices, we compute average number of lasing modes and its fluctuations. The regimes of weak and strong coupling of the passive resonator to environment are considered. In the latter case, contrary to an earlier claim in the literature, we do not find a power-law dependence of the average

S. Glocke, A. Klümper, J. Sirker

The density-matrix renormalization group (DMRG) applied to transfer matrices allows it to calculate static as well as dynamical properties of one-dimensional quantum systems at finite temperature in the thermodynamic limit. To this end the quantum system is mapped onto a two-dimensional classical system by a Trotter-Suzuki decomposition. Here we discuss two

Young-Je Yun, In-Cheol Baek, Mu-Yong Choi

Measurements of the $IV$ characteristics of site-diluted Josephson-junction arrays have revealed intriguing effects of percolative disorder on the phase transition and the vortex dynamics in a two-dimensional XY system. Different from other types of phase transitions, the Kosterlitz-Thouless (KT) transition was eliminated with the introduction of percolative

M. J. Bhaseen, A. G. Green, S. L. Sondhi

We investigate the finite temperature magnetothermoelectric response in the vicinity of a superfluid--Mott insulator quantum phase transition. We focus on the particle-hole symmetric transitions of the Bose--Hubbard model, and combine Lorentz invariance arguments with quantum Boltzmann calculations. By means of an epsilon expansion, we find that a non-vanish

Alexander Blumen, Veronika Bierbaum, Oliver Muelken

We study the coherent transport modeled by continuous-time quantum walks, focussing on hierarchical structures. For these we use Husimi cacti, lattices dual to the dendrimers. We find that the transport depends strongly on the initial site of the excitation. For systems of sizes $N\le21$, we find that processes which start at central sites are nearly recurre

Paolo Politi, Chaouqi Misbah

We study the effect of a higher-order nonlinearity in the standard Kuramoto-Sivashinsky equation: \partial_x \tilde G(H_x). We find that the stability of steady states depends on dv/dq, the derivative of the interface velocity on the wavevector q of the steady state. If the standard nonlinearity vanishes, coarsening is possible, in principle, only if \tilde

Anirban Bandyopadhyay, Y. Wakayama

Negative differential resistance (NDR) is tuned at junctions of electronically different dimer and trimer of Rose Bengal on an atomic flat gold (111) surface. Isolated molecule did not show any NDR. But it was induced to show double NDR with large peak to valley ratio (1.8~3.1) in room temperature via charging its neighbor reproducibly by an electrical pulse

J. -H. Lee, P. Murugavel, D. Lee, T. W. Noh

We fabricated epitaxial thin films of hexagonal DyMnO3, which otherwise form in a bulk perovskite structure, via deposition on Pt(111)//Al2O3 (0001) and YSZ(111) substrates: each of which has in-plane hexagonal symmetry. The polarization hysteresis loop demonstrated the existence of ferroelectricity in our hexagonal DyMnO3 films at least below 70 K. The obse

K. MacLean, S. Amasha, Iuliana P. Radu, D. M. Zumbuhl

We present measurements of the rates for an electron to tunnel on and off a quantum dot, obtained using a quantum point contact charge sensor. The tunnel rates show exponential dependence on drain-source bias and plunger gate voltages. The tunneling process is shown to be elastic, and a model describing tunneling in terms of the dot energy relative to the he

J. Richard Gott, Wesley N. Colley, Chan-Gyung Park, Changbom Park

We have independently measured the genus topology of the temperature fluctuations in the cosmic microwave background seen in the Wilkinson Microwave Anisotropy Probe (WMAP) 3-year data. A genus analysis of the WMAP data indicates consistency with Gaussian random-phase initial conditions, as predicted by standard inflation. We set 95% confidence limits on non

Peter R. Allen, David W. Koerner, Michael W. McElwain, Kelle L. Cruz

We present the results of a deep-imaging search for wide companions to low-mass stars and brown dwarfs using NSFCam on IRTF. We searched a sample of 132 M7-L8 dwarfs to magnitude limits of $J \sim 20.5$ and $K \sim 18.5$, corresponding to secondary-primary mass ratios of $\sim 0.5$. No companions were found with separations between $2{\arcsec}$ to $31{\arcse

J. Richard Gott, D. Clay Hambrick, Michael S. Vogeley, Juhan Kim

We measure the three-dimensional topology of large-scale structure in the Sloan Digital Sky Survey (SDSS). This allows the genus statistic to be measured with unprecedented statistical accuracy. The sample size is now sufficiently large to allow the topology to be an important tool for testing galaxy formation models. For comparison, we make mock SDSS sample

Daniel B. Nestor, David A. Turnshek, Sandhya M. Rao, Anna M. Quider

We present r&#39;- or i&#39;-band WIYN images of the fields of 15 Sloan Digital Sky Survey quasars that have spectra exhibiting intervening MgII absorption-line systems with rest equivalent widths 2.7A \le REW \le 6.0A and redshifts 0.42 < z_{abs} < 0.84. Such systems are rare and exhibit projected absorption velocity spreads in excess of \approx 300-650 km/

C. Catala, J. -F. Donati, E. Shkolnik, D. Bohlender

We have obtained high resolution spectropolarimetric data for the planet-hosting star $τ$ Bootis, using the ESPaDOnS spectropolarimeter at CFHT. A weak but clear Stokes $V$ signature is detected on three of the four nights of June 2006 during which we have recorded data. This polarimetric signature indicates with no ambiguity the presence of a magnetic field

John E. Everett, Norm Murray

We build and test Parker-wind models to apply to observations of large-scale (of order 100 pc) outflows from Active Galactic Nuclei (AGNs). These models include detailed photoionization simulations, the observed radially varying mass profile, adiabatic cooling, and approximations for clouds dragged along in the wind and the interaction of the wind with the c

D. A. Schwartz, D. E. Harris, H. Landt, A. Siemiginowska

We investigate the variations of the magnetic field, Doppler factor, and relativistic particle density along the jet of a quasar at z=0.72. We chose 4C 19.44 for this study because of its length and straight morphology. The 18 arcsec length of the jet provides many independent resolution elements in the Chandra X-ray image. The straightness suggests that geo

T. Bensby, M. S. Oey, S. Feltzing, B. Gustafsson

Using the MIKE spectrograph, mounted on the 6.5 m Magellan/Clay telescope at the Las Campanas observatory in Chile, we have obtained high-resolution spectra for 60 F and G dwarf stars, all likely members of a density enhancement in the local velocity distribution, referred to as the Hercules stream. Comparing with an existing sample of 102 thin and thick dis

A. V. Getling, R. D. Simitev, F. H. Busse

A convection-driven MHD dynamo in a rotating spherical shell, with clearly defined structural elements in the flow and magnetic field, is simulated numerically. Such dynamos can be called deterministic, in contrast to those explicitly dependent on the assumed properties of turbulence. The cases most interesting from the standpoint of studying the nature of s

Simon P. Driver, Jochen Liske, Alister W. Graham

Galaxy bimodality is caused by the bulge-disc nature of galaxies as opposed to two distinct galaxy classes. This is evident in the colour-structure plane which clearly shows that elliptical galaxies (bulge-only) lie in the red compact peak and late-type spiral galaxies (disc-dominated) lie in the blue diffuse peak. Early-type spirals (bulge plus disc systems

Karin I. Oberg, Helen J. Fraser, A. C. Adwin Boogert, Suzanne E. Bisschop

H2O is the most abundant component of astrophysical ices. In most lines of sight it is not possible to fit both the H2O 3 um stretching, the 6 um bending and the 13 um libration band intensities with a single pure H2O spectrum. Recent Spitzer observations have revealed CO2 ice in high abundances and it has been suggested that CO2 mixed into H2O ice can affec

J. -P. Beaulieu, J. Robert Buchler, J. -B. Marquette, J. D. Hartman

Our analysis of the Deep CFHT M33 variability survey database has uncovered 5 Beat Cepheids (BCs) that are pulsating in the fundamental and first overtone modes. With {\it only} the help of stellar pulsation theory and of mass--luminosity (M-L) relations, derived from evolutionary tracks, we can accurately determine the metallicities Z of these stars. The [O

U. Hopp, R. E. -Schulte-Ladbeck, J. Kerp

We address the hypothesis that High Velocity Clouds correspond to the &#34;missing&#34; dwarf galaxies of the Local Group predicted by cosmological simulations. To this end, we present optical and near-infrared photometry of five additional High Velocity Clouds, one of which produces Lyman series absorption on the sight line towards the Quasar Ton S210, with

Edward Malec, Krzysztof Roszkowski

We investigate the accretion onto luminous bodies with hard surfaces within the framework of newtonian theory. The accreting gases are assumed to be polytropes and their selfgravitation is included. A remarkable feature of the model is that under proper boundary conditions some parameters of the sonic point are the same as in the Bondi model and the relation

S. D. Huegelmeyer, S. Dreizler, K. Werner, J. Krzesinski

The Sloan Digital Sky Survey has provided spectra of a large number of new PG 1159 stars and DO white dwarfs. This increase in known hot H-deficient compact objects significantly improves the statistics and helps to investigate late stages of stellar evolution. We have finished our analyses of nine PG 1159 stars and 23 DO white dwarfs by means of detailed NL

F. P. Pijpers

A central step in time-distance local helioseismology techniques is to obtain travel times of packets of wave signals between points or sets of points on the visible surface. Standard ways of determining group or phase travel times involve cross-correlating the signal between locations at the solar photosphere and determining the shift of the envelope of thi

S. D. Huegelmeyer, S. Dreizler, T. Rauch, J. Krzesinski

We present a spectral analysis of 16 DAO white dwarfs from the Sloan Digital Sky Survey Data Release 4. With our NLTE H+He model grid, we derived photospheric parameters for these objects. We compare our new results to literature values and divide the DAOs into two distinct groups: post-AGB and EHB progenitors.

A. Hernan-Caballero, I. Perez-Fournon, M. Rowan-Robinson, D. Rigopoulou

We report results from a Spitzer GO-1 program of IRS spectroscopy of a large sample of Luminous Infrared Galaxies and quasars selected from the European Large Area ISO Survey (ELAIS) which have a wide multiwavelength coverage, including ISOCAM, ISOPHOT, IRAC and MIPS (from SWIRE), and optical photometry. We present the sample selection and results from the I

D. Heinzeller, W. J. Duschl

Although the Eddington limit has originally been derived for stars, recently its relevance for the evolution of accretion discs has been realized. We discuss the question whether the classical Eddington limit - which has been applied globally for almost all calculations on accretion discs - is a good approximation if applied locally in the disc. For this pur

R. Hirschi, A. Maeder, G. Meynet, C. Chiappini

Although the theoretical study of very low metallicity (Z) and metal-free stars is not new, their importance has recently greatly increased since two related fields have been developing rapidly. The first is cosmological simulations of the formation of the first stars and of the reionisation period. The second is the observations of extremely metal poor star

R. A. Burenin, A. Vikhlinin, A. Hornstrup, H. Ebeling

We present a catalog of galaxy clusters detected in a new ROSAT PSPC survey. The survey is optimized to sample, at high redshifts, the mass range corresponding to T> keV clusters at z=0. Technically, our survey is the extension of the 160 square degrees survey (Vikhlinin etal 98a, Mullis etal 2003). We use the same detection algorithm, thus preserving high q

P. Popesso, A. Biviano

Some previous investigations have found that the fraction (f_AGN) of active galactic nuclei (AGNs) is lower in clusters than in the field. This can result from the suppression of galaxy-galaxy mergers in high-velocity dispersion (sigma_v) clusters, if the formation and/or fueling of AGNs is directly related to the merging process. We investigate the existenc

Mark A. Walker

Several radio-wave scintillation phenomena exhibit properties which are difficult to accommodate within the standard propagation model based on distributed Kolmogorov turbulence in the ionised ISM; here we discuss one such phenomenon, namely Extreme Scattering Events. By analysis of the data we demonstrate that these events are caused by ionised gas associat

Shinya Komugi, Kotaro Kohno, Tomoka Tosaki, Hiroyuki Nakanishi

Star formation rates (SFRs) obtained via extinction corrected H alpha are compared to dense gas as traced by CO(J=3-2) emission at the centers of nearby galaxies, observed with the ASTE telescope. It is found that, although many of the observed positions are dusty and therefore heavily absorbed at H alpha, the SFR shows a striking correlation with dense gas

Ing-Guey Jiang, Li-Chin Yeh

Following Papadakis (2005)&#39;s numerical exploration of the Chermnykh&#39;s problem, we here study a Chermnykh-like problem motivated by the astrophysical applications. We find that both the equilibrium points and solution curves become quite different from the ones of the classical planar restricted three-body problem. In addition to the usual Lagrangian

Raul Jimenez, Mariangela Bernardi, Zoltan Haiman, Ben Panter

We use the spectra of ~ 22,000 early-type galaxies, selected from the Sloan Digital Sky Survey, to infer the ages, metallicities and star formation histories of these galaxies. We find clear evidence of &#34;downsizing&#34;, i.e. galaxies with larger velocity dispersion have older stellar populations. In particular, most early-type galaxies with velocity dis

Alain Coc, Nelson J. Nunes, Keith A. Olive, Jean-Philippe Uzan

The effect of variations of the fundamental nuclear parameters on big-bang nucleosynthesis are modeled and discussed in detail taking into account the interrelations between the fundamental parameters arising in unified theories. Considering only \he4, strong constraints on the variation of the neutron lifetime, neutron-proton mass difference are set. These

Edward A. Baltz, James E. Taylor, Lawrence L. Wai

The nature of the cosmic dark matter is unknown. The most compelling hypothesis is that dark matter consists of weakly interacting massive particles (WIMPs) in the 100 GeV mass range. Such particles would annihilate in the galactic halo, producing high-energy gamma rays which might be detectable in gamma ray telescopes such as the GLAST satellite. We investi

A. Baran, A. Staszczak, J. Dobaczewski, W. Nazarewicz

Spontaneous fission barriers, quadrupole inertia, and zero-point quadrupole-energy corrections are calculated for 252,256,258Fm in the framework of the self-consistent Skyrme-Hartree-Fock+BCS theory. Two ways of computing dynamical inertia are employed: the Gaussian Overlap Approximation to the Generator Coordinate Method and cranking ansatz. The Skyrme resu

Aidan C. Crook, John P. Huchra, Nathalie Martimbeau, Karen L. Masters

We present the results of applying a percolation algorithm to the initial release of the Two Micron All-Sky Survey Extended Source Catalog, using subsequently measured redshifts for almost all of the galaxies with K < 11.25 mag. This group catalog is based on the first near-IR all-sky flux-limited survey that is complete to |b| = 5 deg. We explore the depend

B. Alver

This paper presents measurements of the elliptic flow of charged particles as a function of pseudorapidity and centrality from Cu-Cu collisions at 62.4 and 200 GeV using the PHOBOS detector at the Relativistic Heavy Ion Collider (RHIC). The elliptic flow in Cu-Cu collisions is found to be significant even for the most central events. For comparison with the

Davide Lazzati, Rosalba Perna

The detection of bright X-ray flares superimposed on the regular afterglow decay in Swift gamma-ray bursts has triggered theoretical speculations on their origin. We study the temporal properties of flares due to internal dissipation and external shock mechanisms. We first show that at least a sizable fraction of the flares cannot be related to external shoc

Xiaolei Zhang, Ronald J. Buta

We have developed a new method for determining the corotation radii of density waves in disk galaxies, which makes use of the radial distribution of an azimuthal phase shift between the potential and density wave patterns. The approach originated from improved theoretical understandings of the relation between the morphology and kinematics of galaxies, and o

Kenji Fukushima, Yoshimasa Hidaka

We argue the sign problem of the fermion determinant at finite density. It is unavoidable not only in Monte-Carlo simulations on the lattice but in the mean-field approximation as well. A simple model deriving from Quantum Chromodynamics (QCD) in the double limit of large quark mass and large quark chemical potential exemplifies how the sign problem arises i

Sean A. Barton

A light-weight &#34;inflatable&#34; tensioned-membrane-structure vacuum container is proposed and its stability is analyzed. The proposed structure consists of a pressurized lobed cylindrical &#34;wall&#34; surrounding a central evacuated space. Stability is analyzed by discretizing the system and diagonalizing the second derivative of the potential energy.

John M O&#39;Meara, Jason X. Prochaska, Scott Burles, Gabriel Prochter

We present the results of a survey for super Lyman limit systems (SLLS; defined to be absorbers with 19.0 <= log(NHI) <= 20.3 cm^-2) from a large sample of high resolution spectra acquired using the Keck and Magellan telescopes. Specifically, we present 47 new SLLS from 113 QSO sightlines. We focus on the neutral hydrogen frequency distribution f(N,X) of the

S. Caprara, M. Grilli, C. Di Castro, T. Enss

We study the optical conductivity sigma(Omega) of an electron system near a quantum-critical point with finite-wavelength ordering. sigma(Omega) vanishes in clean Galilean-invariant systems, unless electrons are coupled to dynamical collective modes, which dissipate the current. This coupling introduces a nonuniversal energy scale. Depending on the parameter

Christian Schmidt

I discuss different approaches to finite density lattice QCD. In particular, I focus on the structure of the phase diagram and discuss attempts to determine the location of the critical end-point. Recent results on the transiton line as function of the chemical potential ($T_c(μ_q)$) are reviewed. Along the transition line, hadronic fluctuations have been ca

L. O. Kerber, B. X. Santiago, E. Brocato

We analyzed HST/WFPC2 colour-magnitude diagrams (CMDs) of 15 populous Large Magellanic Cloud (LMC) stellar clusters with ages between ~ 0.3 Gyr and ~ 3 Gyr. These (V, B-V) CMDs are photometrically homogeneous and typically reach V \~ 22. Accurate and self-consistent physical parameters (age, metallicity, distance modulus and reddening) were extracted for eac