October 2006 arXiv papers — page 3

S. Camalet, R. Chitra

We study the decoherence of a central spin 1/2 induced by a spin bath with intrabath interactions. Since we are interested in the cumulative effect of interaction and disorder, we study baths comprising Ising spins with random ferro- and antiferromagnetic interactions between the spins. Using the resolvent operator method which goes beyond the standard Born-

R. L. C. Vink, K. Binder, H. Loewen

We show that the critical behavior of a colloid-polymer mixture inside a random porous matrix of quenched hard spheres belongs to the universality class of the random-field Ising model. We also demonstrate that random-field effects in colloid-polymer mixtures are surprisingly strong. This makes these systems attractive candidates to study random-field behavi

Yan-Hong Zhou, Xiao-Hong Zheng, Ying Xu, Zhao Yang Zeng

Effects of relative orientation of the molecules on electron transport in molecular devices are studied by non-equilibrium Green's function method based on density functional theory. In particular, two molecular devices, with the planer Au$_{7}$ and Ag$_{3}$ clusters sandwiched between the Al(100) electrodes are studied. In each device, two typical confi

H. Pan, J. B. Yi, J. Y. Lin, Y. P. Feng

We report magnetism in carbon doped ZnO. Our first-principles calculations based on density functional theory predicted that carbon substitution for oxygen in ZnO results in a magnetic moment of 1.78 $μ_B$ per carbon. The theoretical prediction was confirmed experimentally. C-doped ZnO films deposited by pulsed laser deposition with various carbon concentrat

L. Capogna, B. Fauque, Y. Sidis, C. Ulrich

We present inelastic neutron scattering data on highly overdoped Bi_2 Sr_2 Ca Cu_2 O_{8+δ} single crystals with superconducting transition temperature T_C=70 K and, for comparison, a nearly optimally doped crystal with T_C=87 K. In both samples, magnetic resonant modes with odd and even symmetry under exchange of the two CuO_2 layers in the unit cell are obs

Filippo Radicchi, Daniele Vilone, Hildegard Meyer-Ortmanns

We consider triad dynamics as it was recently considered by Antal \emph{et al.} [T. Antal, P. L. Krapivsky, and S. Redner, Phys. Rev. E {\bf 72}, 036121 (2005)] as an approach to social balance. Here we generalize the topology from all-to-all to a regular one of a two-dimensional triangular lattice. The driving force in this dynamics is the reduction of frus

Alexandre Reily Rocha, Stefano Sanvito

We investigate theoretically the effects of surface states over the magnetoresistance of Ni-based organic spin-valves. In particular we perform {\it ab initio} electronic transport calculations for a benzene-thiolate molecule chemically attached to a Ni [001] surface and contacted either by Te to another Ni [001] surface, or terminated by a thiol group and p

Y. H. Kim, P. H. Hor

We propose a charge crystal model that captures all the essential physics of the high temperature superconductivity (HTS) in the long wavelength limit. Based on the recent transport and the far-infrared (far-IR) experiments, we argue that the three-dimensional (3D) ordering of the pinned two-dimensional (2D) square electronic lattice (EL) in each CuO2 plane

X. L. Dong, P. H. Hor, F. Zhou, Z. -X. Zhao

We have measured the superconducting critical temperature (Tc) and the diamagnetic susceptibility of La2-xSrxCuO4 single crystals in various magnetic fields. We observed a field-induced evolution from an apparent Tc phase to an intrinsic Tc1 = 15 K or Tc2 = 30 K phase characterized by "magic" hole concentration which is commensurate with that of a tw

Ryusuke Ikeda

Motivated by recent NMR data suggesting the presence of a Fulde-Ferrell-Larkin-Ovchinnikov (FFLO) vortex lattice in magnetic fields perpendicular to the superconducting plane in the heavy-fermion superconductor CeCoIn5, we examine here the stability of FFLO states in quasi two-dimensional (2D) superconductors under a perpendicular field. It is found that a 3

Hiroki Saito, Yuki Kawaguchi, Masahito Ueda

We study the dynamics of the quantum phase transition of a ferromagnetic spin-1 Bose-Einstein condensate from the polar phase to the broken-axisymmetry phase by changing magnetic field, and find the spontaneous formation of spinor domain walls followed by the creation of polar-core spin vortices. We also find that the spin textures depend very sensitively on

S. Miyahara, J. -B. Fouet, S. R. Manmana, R. M. Noack

We investigate the interplay of Dzyaloshinskii-Moriya interactions and an external field in spin 1/2 dimers. For isolated dimers and at low field, we derive simple expressions for the staggered and uniform magnetizations which show that the orientation of the uniform magnetization can deviate significantly from that of the external field. In fact, in the lim

V. Orlyanchik, V. I. Kozub, Z. Ovadyahu

We present results of conductance-noise experiments on disordered films of crystalline indium oxide with lateral dimensions 2microns to 1mm. The power-spectrum of the noise has the usual 1/f form, and its magnitude increases with inverse sample-volume down to sample size of 2microns, a behavior consistent with un-correlated fluctuators. A colored second spec

Z. Ovadyahu

We describe several experimental methods to quantify dynamics in electron glasses and illustrate their use in the glassy phase of crystalline indium-oxide films. These methods are applied to study the dependence of dynamics on temperature and on non-ohmic electric fields at liquid helium temperatures. It is shown that over a certain range of temperature the

Z. Ovadyahu

Anderson-insulating indium-oxide films excited far from equilibrium exhibit a variety of memory effects including aging. Full aging has been recently demonstrated in this system using two different experimental protocols. The first, (gate-protocol) employed a MOSFET structure and involved switching between two gate voltages. In a different procedure, the sys

Vadim Oganesyan, David A. Huse

We suggest that if a localized phase at nonzero temperature $T>0$ exists for strongly disordered and weakly interacting electrons, as recently argued, it will also occur when both disorder and interactions are strong and $T$ is very high. We show that in this high-$T$ regime the localization transition may be studied numerically through exact diagonalization

Kazutoshi Miwa, Nobuko Ohba, Yuko Nakamori, Shin-ichi Towata

The thermodynamical stability of ${\rm Al(BH_4)_3}$ has been investigated using first-principles calculations based on density functional theory. The heats of formation are obtained to be -132 and $-131 {\rm kJ/mol}$ without the zero-point energy corrections for $α$- and $β$-${\rm Al(BH_4)_3}$, respectively, which are made up of discrete molecular ${\rm Al(B

Ji Jianghui, H. Kinoshita, Liu Lin, Li Guangyu

We perform numerical simulations to study the secular orbital evolution and dynamical structure in the HD 69830 system with the best-fit orbital solutions by Lovis and coworkers (2006). In the simulations, we show that the triplet Neptunian system can be stable at least for 2 Gyr and the stability would not be greatly influenced even if we vary the planetary

Michael S. Kelley, William T. Reach, Charles E. Woodward

The Deep Impact encounter with the nucleus of 9P/Tempel ejected small grains (a <~ 10 micron) into the comet&#39;s coma, evidenced by thermal emission from small dust grains at mid-infrared wavelengths (~10 micron) and dynamical simulations of optical images. Meteor-sized particles (a >~ 100 micron) ejected by the impact will likely have the lowest ejection

L. Zhang, R. V. E. Lovelace

This work derives the linearized equations of motion, the Lagrangian density, the Hamiltonian density, and the canonical angular momentum density for general perturbations [$\propto \exp(imϕ)$ with $m=0,\pm 1,..$] of a geometrically thin self-gravitating, homentropic fluid disk including the pressure. The theory is applied to ``eccentric,&#39;&#39; $m=\pm 1$

David J. Jeffery, Paolo A. Mazzali

Giant steps is a technique to accelerate Monte Carlo radiative transfer in optically-thick cells of astrophysical atmospheres by greatly reducing the number of Monte Carlo steps needed to propagate photon packets through such cells. Giant steps replaces the exact diffusion treatment of ordinary Monte Carlo radiative transfer in the cells by an approximate di

Jennifer E. Carson

The Gamma-ray Large Area Space Telescope (GLAST) is a space-based observatory scheduled to launch in October 2007 with two instruments: (1) the GLAST Burst Monitor (GBM), sensitive to photon energies between 8 keV and 25 MeV and optimized to detect gamma-ray bursts, and (2) the Large Area Telescope (LAT), sensitive to gamma rays between ~20 MeV and 300 GeV a

D. Berge, S. Funk, J. Hinton

Ground based Cherenkov telescope systems measure astrophysical gamma-ray emission against a background of cosmic-ray induced air showers. The subtraction of this background is a major challenge for the extraction of spectra and morphology of gamma-ray sources. The unprecedented sensitivity of the new generation of ground based very-high-energy gamma-ray expe

Enn Saar, Vicent J. Martinez, Jean-Luc Starck, David L. Donoho

Many statistical methods have been proposed in the last years for analyzing the spatial distribution of galaxies. Very few of them, however, can handle properly the border effects of complex observational sample volumes. In this paper, we first show how to calculate the Minkowski Functionals (MF) taking into account these border effects. Then we present a mu

En-Wei Liang, Bin-Bin Zhang, Mike Stamatikos, Bing Zhang

The spectral and temporal properties of the non-thermal emission ofthe nearby XRF 060218 in 0.3-150 keV band are studied. We show that both the spectral energy distribution and the light curve properties suggest the same origin of the non-thermal emission detected by {\em Swift} BAT and XRT. This event has the longest pulse duration and spectral lag observed

Andreas Reisenegger, Rodrigo Fernandez, Paula Jofre

The equilibrium composition of neutron star matter is achieved through weak interactions (direct and inverse beta decays), which proceed on relatively long time scales. If the density of a matter element is perturbed, it will relax to the new chemical equilibrium through non-equilibrium reactions, which produce entropy that is partly released through neutrin

Kevin France, Stephan R. McCandliss, Roxana E. Lupu

We present new infrared observations of the emission/reflection nebula IC 405 obtained with the Spitzer Space Telescope. Infrared images in the four IRAC bands (3.6, 4.5, 5.8, and 8.0 um) and two MIPS bands (24 and 70 um) are complemented by IRS spectroscopy (5-30 um) of two nebular filaments. The IRAC (8.0 um) and MIPS imaging shows evidence of a bow shock

D. A. Boboltz, A. L. Fey, W. K. Puatua, N. Zacharias

We have used the Very Large Array (VLA), linked with the Pie Town Very Long Baseline Array antenna, to determine astrometric positions of 46 radio stars in the International Celestial Reference Frame (ICRF). Positions were obtained in the ICRF directly through phase referencing of the stars to nearby ICRF quasars whose positions are accurate at the 0.25 mas

Pasquale Blasi

We briefly discuss three aspects related to the origin of ultra-high energy cosmic rays (UHECRs) namely: 1) particle acceleration in astrophysical sources; 2) transition to an extragalactic origin; 3) spectrum and anisotropies at the highest energies.

Yves Revaz, Francoise Combes, Philippe Salome

New CO observations at the center of cooling flow in Perseus cluster \cite{salome06} show a clear correlation of the molecular gas with the previously detected H-$α$ filaments \cite{conselice01}. In this poster, we present high resolution multi-phase simulations of the Perseus Cluster, taking into account the AGN feedback in form of hot buoyant bubbles. Thes

F. Heitsch, A. D. Slyz, J. E. G. Devriendt, L. Hartmann

We revisit the analysis of the Non-linear Thin Shell Instability (NTSI) numerically, including magnetic fields. The magnetic tension force is expected to work against the main driver of the NTSI -- namely transverse momentum transport. However, depending on the field strength and orientation, the instability may grow. For fields aligned with the inflow, we f

Julio Chaname

Wide binaries, particularly in large numbers and as free from selection biases as possible, constitute a largely overlooked tool for studying the Galaxy. The goal of this review is to highlight the potential inherent to large samples of field wide binaries for research on problems as varied as star formation in the early Galaxy, the nature of halo dark matte

E. Alecian, M. -J. Goupil, Y. Lebreton, M. -A. Dupret

Context: The calibration of binary systems with accurately known masses and/or radii provides powerful tools to test stellar structure and evolution theory and to determine the age and helium content of stars. We study the eclipsing double-lined spectroscopic binary system RS Cha, for which we have accurate observations of the parameters of both stars (masse

John P. Subasavage, Todd J. Henry, Pierre Bergeron, Patrick Dufour

How confident are we that all of the nearest white dwarfs (WDs) have been identified? In an effort to answer this question, we have begun an initiative to identify and characterize new nearby WDs, particularly in the southern hemisphere. We estimate physical parameters for new WDs using medium resolution (R ~1000) optical spectroscopy, and distances using op

Nuria Sidro

During its first cycle, the MAGIC (Major Atmospheric Gamma-ray Imaging Cherenkov) telescope was performing an observational campaign covering a total of about 250 hours on galactic sources. Here we review the results for the very high energy gamma-ray emission from some of those sources.

G. V. Kulikov, M. Yu. Zotov

New results of an analysis of arrival directions of extensive air showers registered with the EAS--1000 Prototype array from August 1997 till February 1999 are presented. The method of Alexandreas et al., which has been used for analysis of data registered with CYGNUS, Milagrito, HEGRA AIROBICC, KASCADE and a number of other experiments, is employed. The exi

A. Kashlinsky

We review the recent measurements on the cosmic infrared background (CIB) and their implications for the physics of the first stars era, including Population III. The recently obtained CIB results range from the direct measurements of CIB fluctuations from distant sources using deep Spitzer data to strong upper limits on the near-IR CIB from blazar spectra.

J. Christensen-Dalsgaard

Helioseismology has provided very detailed inferences about rotation of the solar interior. Within the convection zone the rotation rate roughly shares the latitudinal variation seen in the surface differential rotation. The transition to the nearly uniformly rotating radiative interior takes place in a narrow tachocline, which is likely important to the ope

T. Elperin, I. Golubev, N. Kleeorin, I. Rogachevskii

Formation of large-scale coherent structures in a turbulent convection via excitation of large-scale instability is studied. The redistribution of the turbulent heat flux due to non-uniform large-scale motions plays a crucial role in the formation of the coherent large-scale structures in the turbulent convection. The modification of the turbulent heat flux

I. Balestra, P. Tozzi, S. Ettori, P. Rosati

We present a Chandra analysis of the X-ray spectra of 56 clusters of galaxies at z>0.3, which cover a temperature range of 3>kT>15 keV. Our analysis is aimed at measuring the iron abundance in the ICM out to the highest redshift probed to date. We find that the emission-weighted iron abundance measured within (0.15-0.3)R_vir in clusters below 5 keV is, on av

Roberto Gilli, Andrea Comastri, Guenther Hasinger

We present a detailed and self-consistent modeling of the cosmic X-ray background (XRB) based on the most up-to-date X-ray luminosity functions (XLF) and evolution of Active Galactic Nuclei (AGN). The large body of observational results collected by soft (0.5-2 keV) and hard (2-10 keV) X-ray surveys are used to constrain at best the properties of the Compton

Francesco Sylos Labini, Nickolay L. Vasilyev, Yurij V. Baryshev

We discuss the estimation of galaxy correlation properties in several volume limited samples, in different sky regions, obtained from the Fourth Data Release of the Sloan Digital Sky Survey. The small scale properties are characterized through the determination of the nearest neighbor probability distribution. By using a very conservative statistical analysi

O. Petruk

The observed spectrum of a supernova remnant (SNR) is a superposition of many ``local&#39;&#39; spectra emitted by regions of SNRs that are under different physical conditions. The question remains as to whether the broadening of the high-energy end of the observed nonthermal spectrum of SNRs, like in G347.3-0.5 and SN 1006, can be an artifact of observation

F. Millour, R. G. Petrov, O. Chesneau, D. Bonneau

In this work, we present the first AMBER observations, of the Wolf-Rayet and O (WR+O) star binary system y2 Velorum. The AMBER instrument was used with the telescopes UT2, UT3, and UT4 on baselines ranging from 46m to 85m. It delivered spectrally dispersed visibilities, as well as differential and closure phases, with a resolution R = 1500 in the spectral ba

Matteo Guainazzi

I review the constraints that X-ray observations impose on the physical properties and the geometrical distribution of cold absorbing gas in nearby obscured Active Galactic Nuclei (AGN), as well as their implications for AGN structure models.

Zhongli Zhang, Haiguang Xu, Yu Wang, Tao An

We present a study of the mass distributions in the bright E0 galaxy NGC 1407 and its associated group by analyzing the high quality Chandra and ROSAT X-ray spectroscopic data. In order to probe the stellar mass distribution we calculated the B-band mass-to-light ratio profile by comparing the observed line-strength indices and multi-color photometric data w

M. Metz, P. Kroupa, H. Jerjen

There are two fundamentally different physical origins of faint satellite galaxies: cosmological sub-structures that contain shining baryons and the fragmentation of gas-rich tidal arms thrown out from interacting galaxies during hierarchical structure formation. The latter tidal-dwarf galaxies (TDG) may form populations with correlated orbital angular momen

Rim Dib, Victoria M. Kaspi, Fotis P. Gavriil

We report on 10 yr of monitoring of the 8.7-s Anomalous X-ray Pulsar 4U 0142+61 using the Rossi X-Ray Timing Explorer (RXTE). This pulsar exhibited stable rotation from 2000 until February 2006: the RMS phase residual for a spin-down model which includes nu, nudot, and nuddot is 2.3%. We report a possible phase-coherent timing solution valid over a 10-yr spa

S. I. Ipatov, M. F. A&#39;Hearn, K. P. Klaasen

The results of recognition of cosmic ray (CR) signatures on a single image were analyzed for several codes written by several authors. For most visual images made during low solar activity at exposure time t>4 s, the number of clusters of bright pixels on an image per second per sq. cm of CCD was about 2-4, both for dark and normal sky images. At high solar

F. Heitsch, A. D. Slyz, J. E. G. Devriendt, A. Burkert

Cold clouds embedded in warm media are very common objects in astrophysics. Their disruption timescale depends strongly on the dynamical configuration. We discuss the evolution of an initially homogeneous cold cloud embedded in warm turbulent gas. Within a couple of dynamical timescales, the filling factor of the cold gas within the original cloud radius dro

N. D. R. Bhat, Y. Gupta, M. Kramer, A. Karastergiou

We revisit the phenomenon of pulse nulling using high-quality single-pulse data of PSR B1133+16 from simultaneous multifrequency observations. Observations were made at 325, 610, 1400 and 4850 MHz as part of a joint program between the European Pulsar Network and the Giant Metrewave Radio Telescope. The pulse energy time series are analysed to derive improve

A. V. Turbiner, N. L. Guevara

A detailed study of the ground state of the Coulomb system $(\al \al e e)$ which corresponds to the $He_2^{2+}$ molecular ion in a magnetic field $B=0-4.414 \times 10^{13} $ G in parallel configuration (infinitely massive $\al-$particles are situated along a magnetic field line) is presented. The variational method is employed using a trial function which in

Ing-Guey Jiang, Li-Chin Yeh

The restricted three body problem is well-known and very important for dynamics of binary, multiple stars and also planetary systems. We extend the classical version of this problem to the situation that there are some external forces from the belt. We find that both the equilibrium points and solution curves become quite different from the classical case. W

L. J. Mix, J. C. Armstrong, A. M. Mandell, A. C. Mosier

Astrobiology, the study of life as a planetary phenomenon, aims to understand the fundamental nature of life on earth and the possibility of life elsewhere. To achieve this goal, astrobiologists have initiated unprecedented communication between the disciplines of astronomy, biology, chemistry, and geology. The Astrobiology Primer has been created as a refer

Nuria Sidro

Here we report the discovery of very high energy gamma-ray emission from the radio emitting X-ray binary LS I +61 303 with the Major Atmospheric Gamma Imaging Cherenkov (MAGIC) telescope. This high energy emission has been found to be variable, detected 4 days after the periastron passage and lasting for several days. The data have been taken along different

A. Z. Bonanos

In the last decade, over 7000 eclipsing binaries have been discovered in the Local Group through various variability surveys. Measuring fundamental parameters of these eclipsing binaries has become feasible with 8 meter class telescopes, making it possible to use eclipsing binaries as distance indicators. Distances with eclipsing binaries provide an independ

John F. Beacom

How large can the dark matter self-annihilation rate in the late universe be? This rate depends on (rho_DM/m_chi)^2 <sigma_A v>, where rho_DM/m_chi is the number density of dark matter, and the annihilation cross section is averaged over the velocity distribution. Since the clustering of dark matter is known, this amounts to asking how large the annihilation

V. Smolcic, E. Schinnerer, A. Finoguenov, I. Sakelliou

We have identified a complex galaxy cluster system in the COSMOS field via a wide angle tail (WAT) radio galaxy consistent with the idea that WAT galaxies can be used as tracers of clusters. The WAT galaxy, CWAT-01, is coincident with an elliptical galaxy resolved in the HST-ACS image. Using the COSMOS multiwavelength data set, we derive the radio properties

Xavier Siemens, Vuk Mandic, Jolien Creighton

We consider the stochastic background of gravitational waves produced by a network of cosmic strings and assess their accessibility to current and planned gravitational wave detectors, as well as to big bang nucleosynthesis (BBN), cosmic microwave background (CMB), and pulsar timing constraints. We find that current data from interferometric gravitational wa

M. Bajdich, L. Mitas, L. K. Wagner, K. E. Schmidt

We investigate pfaffian trial wave functions with singlet and triplet pair orbitals by quantum Monte Carlo methods. We present mathematical identities and the key algebraic properties necessary for efficient evaluation of pfaffians. Following upon our previous study \cite{pfaffianprl}, we explore the possibilities of expanding the wave function in linear com

K. Hasegawa, Alexey Pak

We calculate the two-loop QCD corrections to paracharmonium decays $eta_{c} rightarrow gamma gamma$ and $eta_{c} rightarrow g g$ involving light-by-light scattering diagrams with light quark loops. Artificial large mass expansion and convergence improvement techniques are used to evaluate these corrections. The obtained corrections to the decays $eta_{c} rig

Ruth Lawrence, Dennis Sullivan

The formula is $\partial{e}=({\rm ad}_e)b+\sum_{i=0}^\infty{\frac{B_i}{i!}}({\rm ad}_e)^i(b-a)\>,$ with $\partial{a}+{1\over2}[a,a] =0$ and $\partial{b}+{1\over2}[b,b] =0$, where $a$, $b$ and $e$ in degrees $-1$, $-1$ and 0 are the free generators of a completed free graded Lie algebra $L[a,b,e]$. The coefficients are defined by ${x\over{e^x-1}}=\sum_{n=0}^\

Karín Menéndez-Delmestre, Andrew W. Blain, Dave M. Alexander, Ian Smail

We present mid-infrared spectra of 5 submillimeter galaxies at z=0.65-2.38 taken with the Spitzer Space Telescope. Four of these sources, at z<1.5, have strong PAH features and their composite spectrum is well fitted by an M82-like spectrum with an additional power-law component consistent with that expected from AGN activity. Based on a comparison of the 7.

Dan Guralnik

Let X be a proper CAT(0) space. A halfspace system (or cubulation) of X is a set H of open halfspaces closed under closure-complementation and such that every point in X has a neighbourhood intersecting only finitely many walls of H. Given a cubulation H, one uses the Sageev-Roller construction to form a cubing C(H). One setting in which cubulations were stu

Jose Javier Garcia Moreta

In this paper we discuss a method to apply Quantization rules for arbitrary Hamiltonians that are not necessarily Polynomials in variable p, so we have H of the form H(x,p)=F(x,p)+g(x) the method uses the results of &#34;Fractional Calculus&#34; for derivatives and integrals.

J. D. T. Smith, B. T. Draine, D. A. Dale, J. Moustakas

We present a sample of low-resolution 5-38um Spitzer IRS spectra of the inner few square kiloparsecs of 59 nearby galaxies spanning a large range of star formation properties. A robust method for decomposing mid-infrared galaxy spectra is described, and used to explore the behavior of PAH emission and the prevalence of silicate dust extinction. Evidence for

Niels L. Ellegaard, Tage Christensen, Peder Voetmann Christiansen, Niels Boye Olsen

Thermo-viscoelastic linear-response functions are calculated from the master equation describing viscous liquid inherent dynamics. From the imaginary parts of the frequency-dependent isobaric specific heat, isothermal compressibility, and isobaric thermal expansion coefficient, we define a &#34;linear dynamic Prigogine-Defay ratio&#34; with the property that

Jose A. Gonzalez, Ulrich Sperhake, Bernd Bruegmann, Mark Hannam

When unequal-mass black holes merge, the final black hole receives a ``kick&#39;&#39; due to the asymmetric loss of linear momentum in the gravitational radiation emitted during the merger. The magnitude of this kick has important astrophysical consequences. Recent breakthroughs in numerical relativity allow us to perform the largest parameter study undertak

Malcolm Fairbairn, Timur Rashba, Sergey Troitsky

It is shown that the Sun can become partially transparent to high energy photons in the presence of a pseudo-scalar. In particular, if the axion interpretation of the PVLAS result were true then up to 2% of GeV energy gamma rays might pass through the Sun, while an even stronger effect is expected for some axion parameters. We discuss the possibilities of ob

F R Cohen, J Pakianathan, V V Vershinin, Jie Wu

Let F_n = <x_1,...,x_n> denote the free group with generators {x_1,...,x_n}. Nielsen and Magnus described generators for the kernel of the canonical epimorphism from the automorphism group of F_n to the general linear group over the integers. In particular among them are the automorphisms chi_{k,i} which conjugate the generator x_k by the generator x_i leavi

Alessio Celi

We study null 1/4 BPS deformations of flat domain wall solutions (NDDW) in N=2, d=5 gauged supergravity with hypermultiplets and vector multiplets coupled. These are uncharged time-dependent configurations and contain as special case, 1/2 supersymmetric flat domain walls (DW), as well as 1/2 BPS null solutions of the ungauged supergravity. Combining our anal

Anais Rassat, Kate Land, Ofer Lahav, Filipe B. Abdalla

We perform a cross-correlation of the Cosmic Microwave Background (CMB) using the third year Wilkinson Microwave Anisotropy Probe (WMAP) data with the 2 Micron All Sky Survey (2MASS) galaxy map (about 828 000 galaxies with median redshift z ~ 0.07). One motivation is to detect the Integrated Sachs-Wolfe (ISW) effect, expected if the cosmic gravitational pote

Kenji Toma, Kunihito Ioka, Takanori Sakamoto, Takashi Nakamura

The gamma-ray burst (GRB) 060218 has ~ 10^5 times lower luminosity than typical long GRBs, and is associated with a supernova (SN). The radio afterglow displays no jet break, so that this burst might arise from a mildly-relativistic spherical outflow produced by the SN shock sweeping the stellar surface. Since this model is energetically difficult, we propos

Hao Fu, Alberto G. Rojo

We study an ultra-cold atomic Fermi Gas with the atom-atom interaction modulated periodically in space. A novel ground state with cooper pairs occupying non-zero center of mass momenta is found. Such a state is closely related to the state proposed by Fulde, Ferrell, Larkin, and Ovchinnikov(FFLO). The resultant single particle excitations with momenta along

Jay R. Yablon

It is well-known that following summing Feynman graphs, the fermion-boson coupling vertex is modified according to gamma^u-->Gamma^u=gamma^u+Delta^u, with Delta^u representing non-divergent perturbative corrections. Here, we calculate the anticommutators specified by Gamma^uv=.5{Gamma^u,Gamma^v}, and then explore some consequences of employing these as a met

André LeClair

We describe a new kind of quantum critical point in the context of quantum anti-ferromagnetism in 2d that can be understood as a quantum critical spin liquid. Based on the comparison of exponents with previous numerical work, we argue it describes a transition from an anti-ferromagnetic Néel ordered state to a VBS-like state. We argue further that the symple

Weiliang Shi, Grace Wahba, Stephen Wright, Kristine Lee

The LASSO-Patternsearch algorithm is proposed to efficiently identify patterns of multiple dichotomous risk factors for outcomes of interest in demographic and genomic studies. The patterns considered are those that arise naturally from the log linear expansion of the multivariate Bernoulli density. The method is designed for the case where there is a possib

David Lehavi

This paper has been withdrawn by the author due to a crucial error

André LeClair

We study a model of N component symplectic fermions in D spacetime dimensions. It has an infra-red stable fixed point in 2<D<4 dimensions referred to as Sp{2N}{D}. Based on the comparison of exponents, we conjecture that the critical exponents for the 3D Wilson-Fisher fixed point for an O(N) invariant N-component bosonic field can be computed in the Sp{-2N}{

Richard J. Mathar

The theory of summation of electromagnetic line transitions is used to tabulate the Taylor expansion of the refractive index of humid air over the basic independent parameters (temperature, pressure, humidity, wavelength) in five separate infrared regions from the H to the Q band at a fixed percentage of Carbon Dioxide. These are least-squares fits to raw, h

P. Zh. Aslanyan

Experimental data from the 2m propane bubble chamber have been analyzed for exotic baryon states search. A number of peculiarities were found in the effective mass spectra of: $Λπ^+$($Σ^{*+}$(1382),PDG), $Λp$ and $Λp p$ subsystems. A few events detected on the photographs of the propane bubble chamber exposed to a 10 GeV/c proton beam, were interpreted as S=

Peter A. Horvathy, Mikhail S. Plyushchay, Mauricio Valenzuela

A covariant set of linear differential field equations, describing an N=1 supersymmetric anyon system in (2+1)D, is proposed in terms of Wigner&#39;s deformation of the bosonic Heisenberg algebra. The non-relativistic ``Jackiw-Nair&#39;&#39; limit extracts the ordinary bosonic and fermionic degrees of freedom from the Heisenberg-Wigner algebra. It yields fir

Tania Robens

We present a Monte-Carlo event generator for simulating chargino pair production at the ILC at next-to-leading order in the electroweak couplings. We consider two approaches of including photon radiation. A strict fixed-order approach allows for comparison and consistency checks with published semianalytic results in the literature. A version with soft- and

A. Belavin, Al. Zamolodchikov

Similarly to the ordinary bosonic Liouville field theory, in its N=1 supersymmetric version an infinite set of operator valued relations, the ``higher equations of motions&#39;&#39;, holds. Equations are in one to one correspondence with the singular representations of the super Virasoro algebra and enumerated by a couple of natural numbers $(m,n)$. We demon

M. E. Machacek, R. P. Kraft, C. Jones, W. R. Forman

We present results from a 49.3 ks Chandra X-ray observation of the strongly interacting dumbbell galaxies NGC4782(3C278) and NGC4783 that constrain the kinematics of the interaction and models for bending the radio jets associated with NGC4782. The galaxies are embedded in an approximately spherical distribution of group gas, centered on NGC4782,that is near

Mark Bowick, Homin Shin, Alex Travesset

Point defects are ubiquitous in two dimensional crystals and play a fundamental role in determining their mechanical and thermodynamical properties. When crystals are formed on a curved background, finite length grain boundaries (scars) are generally needed to stabilize the crystal. We provide a continuum elasticity analysis of defect dynamics in curved crys

Pran Nath

A brief review is given of dark matter in SUGRA, strings and branes. For SUGRA models the implications of Yukawa coupling unification on dark matter are discussed in the light of $g-2$ and $b\to sγ$ constraints. A brief discussion is given of the dark matter in orbifold string compactifications under constraints of modular invariance and radiative breaking o

Azita Parsaeian, Horacio E. Castillo

We present a detailed numerical study of dynamical heterogeneities in the aging regime of a simple binary Lennard-Jones glass former. For most waiting times t_w and final times t, both the dynamical susceptibility \chi_4(t,t_w) and the dynamical correlation length \xi_4(t,t_w) can be approximated as products of two factors: i) a waiting time dependent scale

F. Rodriguez-Hertz, M. Rodriguez-Hertz, R. Ures

We prove that stable ergodicity is C r open and dense among conservative partially hyperbolic diffeomorphisms with one-dimensional center bundle, for all r in [2,infty]. The proof follows Pugh-Shub program: among conservative partially hyperbolic diffeomorphisms with one-dimensional center bundle, accessibility is C r open and dense, and essential accessibil

Yungui Gong, Bin Wang, Anzhong Wang

We have investigated the thermodynamical properties of the Universe with dark energy. Adopting the usual assumption in deriving the constant co-moving entropy density that the physical volume and the temperature are independent, we observed some strange thermodynamical behaviors. However, these strange behaviors disappeared if we consider the realistic situa

Paolo Amore, Mayra Cervantes, Arturo De Pace, Francisco M. Fernandez

We develop a non--perturbative method that yields analytical expressions for the deflection angle of light in a general static and spherically symmetric metric. It is an improvement on a method previously devised by the authors, and provides a correct description of the photon sphere already to first order. We also propose an alternative approach that provid

Greg Kuperberg

We establish a version of the bottleneck conjecture, which in turn implies a partial solution to the Mahler conjecture on the product $v(K) = (\Vol K)(\Vol K^\circ)$ of the volume of a symmetric convex body $K \in \R^n$ and its polar body $K^\circ$. The Mahler conjecture asserts that the Mahler volume $v(K)$ is minimized (non-uniquely) when $K$ is an $n$-cub

Satoshi Uchiyama

The functional composition principle is generalized by taking into account of history of context change. Analysis of Peres' example shows hysteresis of value assignments. It is shown that value assignments which depend on the history of context change are possible in the case that the Hilbert space of state vectors is finite dimensional.

Sangwook Kim

We prove that if a simplicial complex is shellable, then the intersection lattice for the corresponding diagonal arrangement is homotopy equivalent to a wedge of spheres. Furthermore, we describe precisely the spheres in the wedge, based on the data of shelling. Also, we give some examples of diagonal arrangements where the complement is K(π,1), coming from

R. L. C. Starling, R. A. M. J. Wijers, K. Wiersema, E. Rol

We use a new approach to obtain limits on the absorbing columns towards an initial sample of 10 long Gamma-Ray Bursts observed with BeppoSAX and selected on the basis of their good optical and nIR coverage, from simultaneous fits to nIR, optical and X-ray afterglow data, in count space and including the effects of metallicity. In no cases is a MW-like extinc

Bernd Braunecker, D. E. Feldman

Spin and charge currents can be generated by an ac voltage through a one-channel quantum wire with strong electron interactions in a static uniform magnetic field. In a certain range of low voltages, the spin current can grow as a negative power of the voltage bias as the voltage decreases. The spin current expressed in units of hbar/2 per second can become

Eben Kenah, James M. Robins

In an important paper, M.E.J. Newman claimed that a general network-based stochastic Susceptible-Infectious-Removed (SIR) epidemic model is isomorphic to a bond percolation model, where the bonds are the edges of the contact network and the bond occupation probability is equal to the marginal probability of transmission from an infected node to a susceptible

C. Pepin

We show within the slave boson technique, that the Anderson lattice model exhibits a Kondo breakdown quantum critical point (KB-QCP) where the hybridization goes to zero at zero temper- ature. At this fixed point, the f-electrons experience as well a selective Mott transition separating a local-moment phase from a Kondo-screened phase. The presence of a mult

David Coupier

A $d$-dimensional ferromagnetic Ising model on a lattice torus is considered. As the size of the lattice tends to infinity, two conditions ensuring a Poisson approximation for the distribution of the number of occurrences in the lattice of any given local configuration are suggested. The proof builds on the Stein--Chen method. The rate of the Poisson approxi

Igor V. Dolgachev

This is a survey on appearances of reflection groups, real and complex, in algebraic geometry. We also include a brief introduction into the theory of reflection groups.