June 2006 arXiv papers — page 36

Eva M. Fernandez, Jose M. Soler, L. C. Balbas

We study why gold forms planar and cage-like clusters while copper and silver do not. We use density functional theory and norm-conserving pseudo-potentials with and without a scalar relativistic component. For the exchange-correlation functional we use both the generalized gradient (GGA) and the local density (LDA) approximations. We find that planar Au_n s

B. J. Powell

We present a group theoretical analysis of the superconducting state of the Bechgaard salts, e.g., (TMTSF)_2PF_6 or (TMTSF)_2ClO_6. We show that there are eight symmetry distinct superconducting states. Of these only the (fully gapped, even frequency, p-wave, triplet) 'polar state' is consistent with the full range of the experiments on the Bechgaard

A. Mourachkine

This is the first book on the subject of room-temperature superconductivity. The main purpose of the book is twofold. First, to show that, under suitable conditions, superconductivity can occur above room temperature. Secondly, to present general guidelines on how to synthesize a room temperature superconductor. The book begins with an introduction into the

Luis E. Gonzalez, David J. Gonzalez

It is established that liquid metals exhibit surface layering at the liquid-vapor interface, while dielectric simple systems, like those interacting through Lennard-Jones potentials, show a monotonic decay from the liquid density to that of the vapor. First principles molecular dynamics simulations of the liquid-vapor interface of several liquid metals (Li,

Belén Valenzuela

We calculate the non-resonant Raman response, the single particle spectra and the charge-spin configuration for the electron doped $t-t'$ Hubbard model using unrestricted Hartree-Fock calculations. We discuss the similarities and differences in the response of homogeneous versus inhomogeneous structures. Metallic antiferromagnetism dominates in a large r

G. Herranz, M. Basletic, M. Bibes, C. Carretero

LaAlO3/SrTiO3 structures showing high mobility conduction have recently aroused large expectations as they might represent a major step towards the conception of all-oxide electronics devices. For the development of these technological applications a full understanding of the dimensionality and origin of the conducting electronic system is crucial. To shed l

Tota Nakamura

Dynamic scaling analyses are performed in the spin-glass phase of the $\pm J$ Ising, the {\it XY}, and the Heisenberg models in three dimensions. We found a crossover from the critical dynamics to the ground-state dynamics in the Ising model and the Heisenberg model. The ground-state dynamics of the Ising model is characterized by an activation law with a fi

Balázs Dóra, Kazumi Maki, Attila Virosztek, András Ványolos

We study the effect of quantum magnetic impurities on d-wave spin density waves (d-SDW). The impurity spins are aligned coherently according to the spin space anisotropy of the condensate. Both the order parameter and transition temperature increases due to the coherent interplay between magnetic scatterers and d-SDW. This can explain the recent experimental

R. Khasanov, A. Shengelaya, A. Maisuradze, F. La Mattina

The in-plane magnetic field penetration depth (λ_{ab}) in single-crystal La_{1.83}Sr_{0.17}CuO_4 was investigated by means of the muon-spin rotation (\muSR) technique. The temperature dependence of λ^{-2}_{ab} has an inflection point around 10-15K, suggesting the presence of two superconducting gaps: a large gap (Δ_1^d) with d-wave and a small gap (Δ_2^s) wi

W. Knafo, C. Meingast, K. Grube, S. Drobnik

The quasi two-dimensional magnetic BaNi$_{2}$V$_{2}$O$_{8}$ is studied by using high-resolution thermal expansion in magnetic fields up to 10 T applied along the c-axis. A slight increase of about 1 % of the three-dimensional antiferromagnetic ordering temperature $T_N$ is observed at 10 T. Positive and negative pressure dependencies of $T_N$, respectively,

David J. Gonzalez Luis E. Gonzalez, Malcolm J. Stott

Molecular dynamics simulations of the liquid-vapour interfaces in simple sp-bonded liquid metals have been performed using first principles methods. Results are presented for liquid Li, Na, K, Rb, Cs, Mg, Ba, Al, Tl, and Si at thermodynamic conditions near their respective triple points, for samples of 2000 particles in a slab geometry. The longitudinal ioni

J. L. West, K. Zhang, A. Glushchenko, D. Andrienko

When captured by a flat nematic-isotropic interface, colloidal particles can be dragged by it. As a result spatially periodic structures may appear, with the period depending on a particle mass, size, and interface velocity~\cite{west.jl:2002}. If liquid crystal is sandwiched between two substrates, the interface takes a wedge-like shape, accommodating the i

Mikito Koshino, Tsuneya Ando

We extensively study the localization and the quantum Hall effect in the Hofstadter butterfly, which emerges in a two-dimensional electron system with a weak two-dimensional periodic potential. We numerically calculate the Hall conductivity and the localization length for finite systems with the disorder in general magnetic fields, and estimate the energies

Jens Harting, Martin Hecht, Hans J. Herrmann, Sean McNamara

Particle suspensions are ubiquitous in our daily life, but are not well understood due to their complexity. During the last twenty years, various simulation methods have been developed in order to model these systems. Due to varying properties of the solved particles and the solvents, one has to choose the simulation method properly in order to use the avail

Mikito Koshino, Tsuneya Ando

The transport properties of a bilayer graphene are studied theoretically within a self-consistent Born approximation. The electronic spectrum is composed of $k$-linear dispersion in the low-energy region and $k$-square dispersion as in an ordinary two-dimensional metal at high energy, leading to a crossover between different behaviors in the conductivity on

Armen N. Kocharian, Gayanath W. Fernando, Kalum Palandage, James W. Davenport

An exact study of charge-spin separation, pairing fluctuations and pseudogaps is carried out by combining the analytical eigenvalues of the four-site Hubbard clusters with the grand canonical and canonical ensemble approaches in a multidimensional parameter space of temperature (T), magnetic field (h), on-site interaction (U) and chemical potential. Our resu

A. Alan Middleton, Pierre Le Doussal, Kay Joerg Wiese

Exact numerical minimization of interface energies is used to test the functional renormalization group (FRG) analysis for interfaces pinned by quenched disorder. The fixed-point function R(u) (the correlator of the coarse-grained disorder) is computed. In dimensions D=d+1, a linear cusp in R''(u) is confirmed for random bond (d=1,2,3), random field

Temo Vekua, Andreas Honecker

The phase diagram of a frustrated S=1/2 antiferromagnetic spin ladder with additional next-nearest neighbor exchanges, both diagonal and inchain, is studied by a weak-coupling effective field theory approach combined with exact diagonalization for finite systems. In addition to two known phases with rung-singlet and Haldane-type ground states, we observe two

A. M. Bratkovsky, A. P. Levanyuk

We discuss ferroelectric phase transitions into single- and multidomain states in very thin films using continuous theory. It is shown that in nearly cubic ferroelectrics the domain state may survive down to atomic film thicknesses, unlike the single domain state, which is almost always unstable or metastable. This conclusion is valid almost irrespective of

A. I. Sheinis, L. Nigra, M. Q. Kuhlen

We describe a new concept for a MEMS-based active spatial filter for astronomical spectroscopy. The goal of this device is to allow the use of a diffraction-limited spectrometer on a seeing limited observation at improved throughput over a comparable seeing-limited spectrometer, thus reducing the size and cost of the spectrometer by a factor proportional to

C. E. Grant, M. W. Bautz, S. E. Kissel, B. LaMarr

Soon after launch, the Advanced CCD Imaging Spectrometer (ACIS), one of the focal plane instruments on the Chandra X-ray Observatory, suffered radiation damage from exposure to soft protons during passages through the Earth's radiation belts. The primary effect of the damage was to increase the charge transfer inefficiency (CTI) of the eight front illumi

A. I. Sheinis

We report on the design, development and commissioning of an Integral Field Unit (IFU) that has been built for the Echellette Spectrograph and Imager (ESI) at the W.M. Keck Observatory. This image slicer--based IFU, which was commissioned in the spring of 2004 covers a contiguous field of 5.65 x 4.0 arcseconds in 5 slices that are 1.13 arcseconds wide. The I

Jonathan P. Gardner, John C. Mather, Mark Clampin, Rene Doyon

The James Webb Space Telescope (JWST) is a large (6.6m), cold (50K), infrared-optimized space observatory that will be launched early in the next decade. The observatory will have four instruments: a near-infrared camera, a near-infrared multi-object spectrograph, and a tunable filter imager will cover the wavelength range, 0.6 to 5.0 microns, while the mid-

Nathan Smith, Stanley P. Owocki

We suggest that the mass lost during the evolution of very massive stars may be dominated by optically thick, continuum-driven outbursts or explosions, instead of by steady line-driven winds. In order for a massive star to become a WR star, it must shed its H envelope, but new estimates of the effects of clumping in winds indicate that line driving is vastly

John J. Feldmeier

I review the progress in research on intracluster planetary nebulae over the last five years. Hundreds more intracluster planetary nebulae have been detected in the nearby Virgo and Fornax galaxy clusters, searches of several galaxy groups have been made, and intracluster planetary candidates have been detected in the distant Coma cluster. The first theoreti

Carlos Hernandez-Monteagudo, Hy Trac, Raul Jimenez, Licia Verde

Using cosmological hydrodynamical simulations, we investigate the prospects of the thermal Sunyaev-Zel'dovich (tSZ) effect to detect the missing baryons in the local universe. We find that at least 80% of the tSZ luminosity is generated in collapsed structures, and that $\sim$ 70% of the remaining diffuse tSZ luminosity (i.e., $\sim 15$% of the total) co

Michael R. Blanton, Sam Roweis

Template fits to observed galaxy fluxes allow calculation of K-corrections and conversions among observations of galaxies at various wavelengths. We present a method for creating model-based template sets given a set of heterogeneous photometric and spectroscopic galaxy data. Our technique, non-negative matrix factorization, is akin to principle component an

Oleg Y. Gnedin, Jose L. Prieto

We test the hypothesis that globular clusters form in supergiant molecular clouds within high-redshift galaxies. Numerical simulations demonstrate that such large, dense, and cold gas clouds assemble naturally in current hierarchical models of galaxy formation. These clouds are enriched with heavy elements from earlier stars and could produce star clusters i

C. Armendariz-Picon

We describe a novel mechanism to seed a nearly scale invariant spectrum of adiabatic perturbations during a non-inflationary stage. It relies on a modified dispersion relation that contains higher powers of the spatial momentum of matter perturbations. We implement this idea in the context of a massless scalar field in an otherwise perfectly homogeneous univ

A. -M. Lagrange, H. Beust, S. Udry, G. Chauvin

We present the results of multi epochs imaging observations of the companion to the planetary host Gliese 86. Associated to radial velocity measurements, this study aimed at characterizing dynamically the orbital properties and the mass of this companion (here after Gliese 86 B), but also at investigating the possible history of this particular system. We us

G. Chauvin, A. -M. Lagrange, S. Udry, T. Fusco

We present the results of a deep imaging survey of stars surrounded by planets detected with the radial velocity technique. The purpose is to search for and to characterize long-period stellar and substellar companions. The sample contains a total of 26 stars, among which 6 exhibit additional radial velocity drifts. We used NACO, at the ESO Very Large Telesc

Eleazar R. Carrasco, Claudia M. de Oliveira, Leopoldo Infante

We used V and I CCD photometry to search for low-surface brightness dwarf galaxies (LSBD) in the central (<0.5 h^-1 Mpc) region of the groups NGC 6868, NGC 5846, HCG 42 and the poor cluster IC 4765. Using the parameters given by the exponential profile fit, we identified 80 LSBD candidates with magnitudes 17 < V < 22 mag and with colors V-I < 1.5 mag at the

W. Herbst, S. Dhital, A. Francis, L. Lin

Five years of photometric monitoring of the T Tauri star HBC 338 in NGC 1333 has revealed that it is a periodic variable, but the period has changed significantly with time. From 2000-2003, a period near 5.6 days was observed, while in the last two seasons, the dominant period is near 4.6 days. No other T Tauri star has been seen to change its period by such

Maryvonne Gerin, Dariuscz C. Lis, Sabine Philipp, Rolf Güsten

Finding tracers of the innermost regions of prestellar cores is important for understanding their chemical and dynamical evolution before the onset of gravitational collapse. While classical molecular tracers, such as CO and CS, have been shown to be strongly depleted in cold, dense gas by condensation on grain mantles, it has been a subject of discussion to

Barbara Ercolano, Nate Bastian

Emission line spectra from HII regions are often used to study properties of the gas in star-forming regions, as well as temperatures and luminosities of the ionising sources. Empirical diagnostics for the interpretation of observational data must often be calibrated with the aid of photoionisation models. Most studies so far have been carried out by assumin

Giuseppe Lodato, Priya Natarajan

In this paper we discuss the evolution of gravitationally unstable pre-galactic discs that result from the collapse of haloes at high redshift $z \approx 10$ or so, which have not yet been enriched by metals. In cases where molecular hydrogen formation is suppressed the discs are maintained at a temperature of a few thousand degrees Kelvin. However, when mol

M. Schweitzer, D. Lutz, E. Sturm, A. Contursi

This paper addresses the origin of the far-infrared (FIR) continuum of QSOs, based on the Quasar and ULIRG Evolution Study (QUEST) of nearby QSOs and ULIRGs using observations with the Spitzer Space Telescope. For 27 Palomar-Green QSOs at z <~ 0.3, we derive luminosities of diagnostic lines ([NeII]12.8um, [NeV]14.3um, [OIV]25.9um) and emission features (PAH7

Chris Lintott, Serena Viti

Recent observations reveal galaxies in the early Universe (2<z<6.4) with large reservoirs of molecular gas and extreme star formation rates. For a very large range of sources, a tight relationship exists between star formation rate and the luminosity of the HCN J=1-0 spectral line, but sources at redshifts of z~2 and beyond do not follow this trend. The defi

JF Donati, ID Howarth, MM Jardine, P Petit

We report the discovery of a medium-strength (~0.5kG) magnetic field on the young, massive star tauSco (B0.2V), which becomes the third-hottest magnetic star known. Circularly polarized Zeeman signatures are clearly detected in observations collected mostly with the ESPaDOnS spectropolarimeter, recently installed on the 3.6-m Canada-France-Hawaii Telescope;

F. Schuller, S. Leurini, C. Hieret, K. M. Menten

Context: The M16 nebula is a relatively nearby Hii region, powered by O stars from the open cluster NGC 6611, which borders to a Giant Molecular Cloud. Radiation from these hot stars has sculpted columns of dense obscuring material on a few arcmin scales. The interface between these pillars and the hot ionised medium provides a textbook example of a Photodis

Katrin Heitmann, David Higdon, Charles Nakhleh, Salman Habib

The complexity and accuracy of current and future precision cosmology observational campaigns has made it essential to develop an efficient technique for directly combining simulation and observational datasets to determine cosmological and model parameters; a procedure we term calibration. Once a satisfactory calibration of the underlying cosmological model

Thomas R. Ayres, Claude Plymate, Christoph U. Keller

A solar photospheric &#34;thermal profiling&#34; analysis is presented, exploiting the infrared rovibrational bands of carbon monoxide (CO) as observed with the McMath-Pierce Fourier transform spectrometer (FTS) at Kitt Peak, and from above the Earth&#39;s atmosphere by the Shuttle-borne ATMOS experiment. Visible continuum intensities and center-limb behavio

C. P. Haines, P. Merluzzi, A. Mercurio, A. Gargiulo

We present an analysis of the effects of environment on the photometric properties of galaxies in the core of the Shapley Supercluster at z=0.05, one of the most massive structures in the local universe. The Shapley Optical Survey (SOS) comprises archive WFI optical imaging of a 2.0 deg^2 region containing the rich clusters A3556, A3558 and A3562 which demon

P. V. Kaygorodov, D. V. Bisikalo, O. A. Kuznetsov, A. A. Boyarchuk

We consider a mechanism for the formation of superhumps in the TV Col system, based on the possible existence of a precessional spiral wave in the accretion disk of the system. This mechanism can act in binaries with arbitrary component-mass ratios, and our precessional spiral wave model can be applied to explain observed superhumps of all types.

M. Gustafsson, J. L. Lemaire, D. Field

Context. In order to understand the evolution of molecular clouds it is important to identify the departures from self-similarity associated with the scales of self-gravity and the driving of turbulence. Aims. A method is described based on structure functions for determining whether a region of gas, such as a molecular cloud, is fractal or contains structur

R. S. Levenhagen, N. V. Leister

Spectroscopic monitoring of 141 southern &#64257;eld B type stars, 114 of them known to exhibit the Be phenomenon, allowed the estimation of their projected rotational velocities, effective temperatures and super&#64257;cial gravities from both line and equivalent width &#64257;tting procedures. Stellar ages, masses and bolometric luminosities were derived f

Bo Li, Xing Li

The classic Weber-Davis model of the solar wind is reconsidered by incorporating alpha particles and by allowing the solar wind to flow out of the equatorial plane in an axisymmetrical configuration. In the ion momentum equations of the solar wind, the ion gyro-frequency is many orders of magnitude higher than any other frequency. This requires that the diff

T. Oosterbroek, J. H. J. de Bruijne, D. Martin, P. Verhoeve

We have observed the Crab Pulsar in the optical with S-Cam, an instrument based on Superconducting Tunneling Junctions (STJs) with $μ$s time resolution. Our aim was to study the delay between the radio and optical pulse. The Crab Pulsar was observed three times over a time span of almost 7 years, on two different locations, using three different versions of

Juergen Schmoll, David J. Robertson, David A. Ryder

We describe our work towards the manufacture of micro-optical arrays using freeform diamond machining techniques. Simulations have been done to show the feasibility of manufacturing micro-lens arrays using the slow-tool servo method. Using this technique, master shapes can be produced for replication of micro-lens arrays of either epoxy-on-glass or monolthic

Andrei P. Lobanov, J. Anton Zensus

Over the last five decades, AGN studies have produced a number of spectacular examples of synergies and multifaceted approaches in astrophysics. The field of AGN research now spans the entire spectral range and covers more than twelve orders of magnitude in the spatial and temporal domains. The next generation of astrophysical facilities will open up new pos

Andrei P. Lobanov

The Square Kilometer Array will be operating at the same time with several new large optical, X-ray and Gamma-ray facilities currently under construction or planned. Fostering synergies in astrophysical research made across different spectral bands presents a compelling argument for designing the SKA such that it would offer imaging capabilities similar to t

S. Bhattacharyya, N. Bhatt, R. Misra

In the inner regions of an accretion disk around a black hole, relativistic protons can interact with ambient matter to produce electrons, positrons and $γ$-rays. The resultant steady state electron and positron particle distributions are self-consistently computed taking into account Coulomb and Compton cooling, $e^-e^+$ pair production (due to $γ-γ$ annihi

A. Georgakakis, K . Nandra, E. S. Laird, S. Gwyn

We discuss the optical and X-ray spectral properties of the sources detected in a single 200ks Chandra pointing in the Groth-Westphal Strip region. Optical identifications and spectroscopic redshifts are primarily from the DEEP2 survey. This is complemented with deeper (r~26mag) multi-waveband data (ugriz) from the Canada France Hawaii Legacy Survey to estim

Laura P. Dunn, Helmut Jerjen

A sophisticated SBF analysis package has been developed, designed to measure distances of early-type galaxies by means of surface brightness fluctuations of unresolved stars. This suite of programs called SAPAC is made readily available to the astronomical community for extensive testing with the long-term goal to provide the necessary tools for systematic d

R. Sharp, W. Saunder, G. Smith, V. Churilov

AAOmega is the new spectrograph for the 2dF fibre-positioning system on the Anglo-Australian Telescope. It is a bench-mounted, double-beamed design, using volume phase holographic (VPH) gratings and articulating cameras. It is fed by 392 fibres from either of the two 2dF field plates, or by the 512 fibre SPIRAL integral field unit (IFU) at Cassegrain focus.

Anand Sivaramakrishnan, Ben R. Oppenheimer

We propose a solution to the problem of astrometric and photometric calibration of coronagraphic images with a simple optical device which, in theory, is easy to use. Our design uses the Fraunhofer approximation of Fourier optics. Placing a periodic grid of wires (we use a square grid) with known width and spacing in a pupil plane in front of the occulting c

A. Gianninas, P. Bergeron, G. Fontaine

As part of an ongoing program to map better the empirical instability strip of pulsating ZZ Ceti white dwarfs, we present a brief progress report based on our last observing season. We discuss here high-speed photometric measurements for 6 new pulsators. These stars were selected on the basis of preliminary measurements of their effective temperature and sur

Peter Petreczky

I discuss recent progress in calculating quarkonia correlators and spectral functions on the lattice in relation with the problem of quarkonia dissolution at high temperatures and heavy quark transport in Quark Gluon Plasma.

Johan Richard, Roser Pello, Daniel Schaerer, Jean-Francois Le Borgne

(abridged) We present the first results of our deep survey of lensing clusters aimed at constraining the abundance of star-forming galaxies at z~6-10. Deep near-IR photometry of two lensing clusters (A1835 and AC114) was obtained with ISAAC/VLT. These images, combined with existing data in the optical bands, including HST images, were used to select very hig

David Gamarnik, Dmitriy Katz

We propose a deterministic algorithm for approximately counting the number of list colorings of a graph. Under the assumption that the graph is triangle free, the size of every list is at least $αΔ$, where $α$ is an arbitrary constant bigger than $α^{**}=2.8432...$, and $Δ$ is the maximum degree of the graph, we obtain the following results. For the case whe

R. R. Caldwell, Daniel Grin

We consider a linearized, effective quantum theory of gravitation in which gravity weakens at energies higher than ~10^-3 eV in order to accommodate the apparent smallness of the cosmological constant. Such a theory predicts departures from the static Newtonian inverse-square force law on distances below ~0.05 mm. However, we show that such a modification al

Ben E. K. Sugerman, Barbara Ercolano, M. J. Barlow, A. G. G. M. Tielens

We present late-time optical and mid-infrared observations of the Type-II supernova 2003gd in NGC 628. Mid-infrared excesses consistent with cooling dust in the ejecta are observed 499-678 days after outburst, and are accompanied by increasing optical extinction and growing asymmetries in the emission-line profiles. Radiative-transfer models show that up to

Kamiokande Collaboration, M. E. C. Swanson

Many astrophysical models predict a diffuse flux of high-energy neutrinos from active galactic nuclei and other extra-galactic sources. At muon energies above 1 TeV, the upward-going muon flux induced by neutrinos from active galactic nuclei is expected to exceed the flux due to atmospheric neutrinos. We have performed a search for this astrophysical neutrin

Trevor C. Weekes

The Atmospheric Cherenkov Imaging Technique has opened up the gamma-ray spectrum from 100 GeV to 50 TeV to astrophysical exploration. The development of the technique (with emphasis on the early days) is described as are the basic principles underlying its application to gamma-ray astronomy. The current generation of arrays of telescopes, in particular, VERI

Xiong-Jun Liu, Xin Liu, Zheng-Xin Liu, L. C. Kwek

We show the pulse matching phenomenon can be obtained in the general multi-level system with electromagnetically induced transparency (EIT). For this we find a novel way to create tightly localized stationary pulses by using counter-propagating pump fields. The present process is a spatial compression of excitation so that it allows us to shape and further i

Lucas Cieza, Nairn Baliber

We present 75 new stellar rotation periods in the young cluster IC348. Stars estimated to be less massive than 0.25 Mo show a unimodal distribution with a peak at P ~1-2 d) and a tail of slower rotators, while stars estimated to be more massive than 0.2 Mo show a bimodal distribution with peaks at ~2 and ~8 d. We combine all published rotation periods in IC3

Josep Àlvarez Montaner, Anton Leykin

For a polynomial ring $R=k[x_1,...,x_n]$, we present a method to compute the characteristic cycle of the localization $R_f$ for any nonzero polynomial $f\in R$ that avoids a direct computation of $R_f$ as a $D$-module. Based on this approach, we develop an algorithm for computing the characteristic cycle of the local cohomology modules $H^r_I(R)$ for any ide

R. Poling

Selected recent results and future prospects for the CLEO-c experiment at CESR are reviewed. The topics covered include measurements of leptonic and semileptonic charm decays made with data collected at the $ψ(3770)$ resonance and results from a scan of the center-of-mass energy range from 3970 to 4260 MeV addressing the details of open-charm production and

Ling Wang, Anders W. Sandvik

We investigate the quantum dynamics of site diluted S=1/2 Heisenberg antiferromagnetic clusters at the percolation threshold. We use Lanczos diagonalization to calculate the lowest excitation gap Delta and, to reach larger sizes, study an upper bound for Delta obtained from sum rules involving the staggered structure factor and susceptibility, which we evalu

Jiri Lebl

A local uniqueness property of holomorphic functions on real-analytic nowhere minimal CR submanifolds of higher codimension is investigated. A sufficient condition called almost minimality is given and studied. A weaker necessary condition, being contained a possibly singular real-analytic Levi-flat hypersurface is studied and characterized. This question is

Oleg Antipin, G. Valencia

We study the (tree-level) weak radiative decays of $B$ mesons. We present a numerical estimate for the inclusive $b \to X_c γ(γ)$ modes based on the free-quark decay. We then review what is known for the $B \to D^\star γ$ modes in the framework of heavy quark effective theory and chiral perturbation theory. Finally, we extend these ideas to the double radiat

Kazumi Okuyama

We study the relation between two kinds of topological amplitudes of non-compact D-branes on conifold. In the A-model, D-branes are represented by fermion operators in the melting crystal picture and the amplitudes are given by the quantum dilogarithm. In the mirror B-model, D-branes correspond to the determinant operator det(x-M) in the Chern-Simons matrix

Itzhak Bars

In this paper it will be shown that the Standard Model in 3+1 dimensions is a gauge fixed version of a 2T-physics field theory in 4+2 dimensions, thus establishing that 2T-physics provides a correct description of Nature from the point of view of 4+2 dimensions. The 2T formulation leads to phenomenological consequences of considerable significance. In partic

Steven D. Bass

Two key issues in the application of perturbative QCD and Regge predictions to high energy processes are whether the hard and soft pomerons should be considered as two separate distinct exchanges and whether the Regge intercepts are Q^2 independent or not. Models involving a distinct hard pomeron exchange predict much larger values for the LHC total cross-se

J. W. Moffat

An exact inhomogeneous solution of Einstein&#39;s field equations is shown to be able to inflate in a non-uniform way in the early universe and explain anomalies in the WMAP power spectrum data. It is also possible for the model to explain the accelerated expansion of the universe by late-time inhomogeneous structure.

Ll. Masanes, R. Renner, M. Christandl, A. Winter

We analyze a cryptographic protocol for generating a distributed secret key from correlations that violate a Bell inequality by a sufficient amount, and prove its security against eavesdroppers, constrained only by the assumption that any information accessible to them must be compatible with the non-signaling principle. The claim holds with respect to the s

Thomas Vojta, Rastko Sknepnek

We study the phase diagram and the quantum phase transitions of a site-diluted two-dimensional O(3) quantum rotor model by means of large-scale Monte-Carlo simulations. This system has two quantum phase transitions, a generic one for small dilutions, and a percolation transition across the lattice percolation threshold. We determine the critical behavior for

Anne Louchet, Jamil S. Habib, Vincent Crozatier, Ivan Lorgeré

A three-level Lambda system in Tm3+ doped YAG crystal is experimentally investigated in the prospect of quantum information processing. Zeeman effect is used to lift the nuclear spin degeneracy of this ion. In a previous paper [de Seze et al. Phys. Rev. B, 73, 85112 (2006) we measured the gyromagnetic tensor components and concluded that adequate magnetic fi

Thomas H. Otway

A fundamental result that characterizes elliptic-hyperbolic equations of Tricomi type, the uniqueness of classical solutions to the open Dirichlet problem, is extended to a large class of elliptic-hyperbolic equations of Keldysh type. The result implies the non-existence of classical solutions to the closed Dirichlet problem for this class of equations. A un

K. Rodriguez, S. R. Manmana, M. Rigol, R. M. Noack

We study the formation of (quasi-)coherent matter waves emerging from a Mott insulator for strongly interacting bosons on a one-dimensional lattice. It has been shown previously that a quasi-condensate emerges at momentum k=π/2a, where a is the lattice constant, in the limit of infinitely strong repulsion (hard-core bosons). Here we show that this phenomenon

Evgeny Plekhanov, Adolfo Avella, Ferdinando Mancini

The issue of ergodicity is often underestimated. The presence of zero-frequency excitations in bosonic Green's functions determine the appearance of zero-frequency momentum-dependent quantities in correlation functions. The implicit dependence of matrix elements make such quantities also relevant in the computation of susceptibilities. Consequently, the corr

Gentaro Watanabe, S. Andrew Gifford, Gordon Baym, C. J. Pethick

We calculate the structure of individual vortices in rotating Bose-Einstein condensates in a transverse harmonic trap. Making a Wigner-Seitz approximation for the unit cell of the vortex lattice, we derive the Gross-Pitaevskii equation for the condensate wave function in each cell of the lattice, including effects of varying coarse grained density. We calcul

J. Haidenbauer, H. -W. Hammer, Ulf-G. Meißner, A. Sibirtsev

We study the energy dependence of the e^+e^- to ppbar cross section close to the two-nucleon threshold, recently reported by the BaBar collaboration. Our analysis also includes the pbarp to e^+e^- data collected by PS170 collaboration and the e^+e^- to NNbar data from the FENICE collaboration. We show that the near-threshold enhancement in the e^+e^- to ppba

Liviu Ornea, Misha Verbitsky

A contact manifold $M$ can be defined as a quotient of a symplectic manifold $X$ by a proper, free action of $\R^{>0}$, with the symplectic form homogeneous of degree 2. If $X$ is, in addition, Kaehler, and its metric is also homogeneous of degree 2, $M$ is called Sasakian. A Sasakian manifold is realized naturally as a level set of a Kaehler potential on a

D. Makogon, V. Juricic, C. Morais Smith

We study the transport properties of a Luttinger liquid in the presence of several time-dependent weak point-like impurities. Our starting point is the bosonized form of the Luttinger liquid Hamiltonian with a potential introduced by the impurities. We find the correction to the total current due to the backscattering of the electrons by the impurities in fi

Weixing Shu, Zhongzhou Ren, Hailu Luo, Fei Li

By the extinction theorem we explore the Brewster effect in the external and internal reflections of electromagnetic wave associated with an anisotropic material that is both dielectric and magnetic, including metamaterials. We obtain Fresnel&#39;s coefficients and the condition of Brewster&#39;s angle, and give microscopic explanations from the view point o

Alessandro Mirone

We develop a simple tensorial contraction method to obtain analytical formula for X-ray resonant magnetic scattering. We apply the method considering first electric dipole-dipole and electric quadrupole-quadrupole scattering in the isolated atom approximation and compare the results with previous works. Then we apply the method to derive phenomenological ori

Keigo Nitadori, Junichiro Makino, George Abe

In this paper, we describe the performance of an $N$-body simulation of star cluster with 64k stars on a Cray XD1 system with 400 dual-core Opteron processors. A number of astrophysical $N$-body simulations were reported in SCxy conferences. All previous entries for Gordon-Bell prizes used at least 700k particles. The reason for this preference of large numb

Esteban Guevara Hidalgo

We propose the study of quantum games from the point of view of quantum information theory and statistical mechanics. Every game can be described by a density operator, the von Neumann entropy and the quantum replicator dynamics. There exists a strong relationship between game theories, information theories and statistical physics. The density operator and e

Clément Sire

We present an approximate calculation for the distribution of the maximum of a smooth stationary temporal signal X(t). As an application, we compute the persistence exponent associated to the probability that the process remains below a non-zero level M. When X(t) is a Gaussian process, our results are expressed explicitly in terms of the two-time correlatio

Harmen J. Warringa

We calculate the phase diagram of color and electrically neutral quark matter in weak equilibrium using the NJL model at high baryon densities. We extend previous analyses by taking into account the possibility of formation of pseudoscalar meson condensates in the color-flavor locked (CFL) phase. We find that the kaon condensed phase (CFL-K0) is preferred ov

M. Hirsch, W. Porod

We point out that, if R-parity is broken spontaneously, the neutralino can decay to the final state majoron plus neutrino, which from the experimental point of view is indistinguishable from the standard missing momentum signal of supersymmetry. We identify the regions of parameter space where this decay mode is dominant and show that they are independent of

Ilja Dorsner, Pavel Fileviez Perez

We investigate unification constraints in the simplest renormalizable non-supersymmetric SU(5) framework. We show that in the scenario where the Higgs sector is composed of the 5, 24, and 45 dimensional representations the proton could be practically stable. We accordingly demonstrate that of all the SU(5) scenarios only the non-renormalizable one with the 5

S. V. Kukhlevsky

The energy conservation is a general law of nature. In the classical physics, the energy W_{AB} of a conservative system {AB} that contains the objects A and B is equal to a sum of the positive energies W_A and W_B of the isolated objects A and B, W_{AB} = W_A+W_B. We show that the energy conservation does not exhibit the &#34;classic law&#34; if the physica

Sergio Mendes, Roger Plymen

Let F be a nonarchimedean local field and let G = GL(n) = GL(n,F). Let E/F be a finite Galois extension. We investigate base change E/F at two levels: at the level of algebraic varieties, and at the level of K-theory. We put special emphasis on the representations with Iwahori fixed vectors, and the tempered spectrum of GL(1) and GL(2). In this context, the

R. J. McLure, M. Cirasuolo, J. S. Dunlop, K. Sekiguchi

We have exploited the large area coverage of the combined UKIDSS Ultra Deep Survey (UDS) and Subaru/XMM-Newton Deep Survey (SXDS) to search for bright Lyman-break galaxies (LBGs) at z >= 5. Using the available optical+near-infrared photometry to efficiently exclude low-redshift contaminants, we identify nine z >= 5 LBG candidates brighter than z&#39;=25(AB)

Santanu K. Maiti

Mathematica is a powerful application package for doing mathematics and is used almost in all branches of science. It has widespread applications ranging from quantum computation, statistical analysis, number theory, zoology, astronomy, and many more. Mathematica gives a rich set of programming extensions to its end-user language, and it permits us to write

Matthieu Renaud, Guillaume Bélanger, Jacques Paul, François Lebrun

Aims. We report the INTEGRAL/IBIS observations of the Coma Cluster in the hard X-ray/soft-ray domain. Methods. Since the Coma Cluster appears as an extended source, its global intensity and significance cannot be directly extracted with standard coded mask analysis. We used the method of imaging the extended sources with a coded mask telescope developed by R

Arnab Chatterjee, Parongama Sen

A one dimensional network on which there are long range bonds at lattice distances $l>1$ with the probability $P(l) \propto l^{-δ}$ has been taken under consideration. We investigate the critical behavior of the Ising model on such a network where spins interact with these extra neighbours apart from their nearest neighbours for $0 \leq δ< 2$. It is observed

Renaud Matthieu, Alexandra Gros, François Lebrun, Régis Terrier

Context. In coded mask techniques, reconstructed sky images are pseudo-images: they are maps of the correlation between the image recorded on a detector and an array derived from the coded mask pattern. Aims. The INTEGRAL/IBIS telescope provides images where the flux of each detected source is given by the height of the local peak in the correlation map. As