January 2005 arXiv papers — page 7

Vladimir Manuilov, Klaus Thomsen

Let $A$ and $B$ be separable $C^*$-algebras, $A$ unital and $B$ stable. It is shown that there is a natural six-terms exact sequence which relates the group which arises by considering all semi-split extensions of $A$ by $B$ to the group which arises by restricting the attention to \emph{unital} semi-split extensions of $A$ by $B$. The six-terms exact sequen

Hidetoshi Maeda, Andrew Sommese

Let $\Cal E$ be a very ample vector bundle of rank two on a smooth complex projective threefold $X$. An inequality about the third Segre class of $\Cal E$ is provided when $K_X+\det \Cal E$ is nef but not big, and when a suitable positive multiple of $K_X+\det \Cal E$ defines a morphism $X\to B$ with connected fibers onto a smooth projective curve $B$, where

Alex Clark, Robbert Fokkink

Lind and Schmidt have shown that the homoclinic group of a cyclic $\Z^k$ algebraic dynamical system is isomorphic to the dual of the phase group. We show that this duality result is part of an exact sequence if $k=1$. The exact sequence is a well known algebraic object, which has been applied by Schmidt in his work on rigidity. We show that it can be derived

Pierre Andreoletti

We give an alternative proof of the localization of Sinai's random walk in random environment under weaker hypothesis than the ones used by Sinai. Moreover we give estimates that are stronger than the one of Sinai on the localization neighborhood and on the probability for the random walk to stay inside this neighborhood.

Pierre Andreoletti

We consider Sinai's random walk in random environment. We prove that for an interval of time [1,n] Sinai's walk sojourns in a small neighborhood of the point of localization for the quasi totality of this amount of time. Moreover the local time at the point of localization normalized by $n$ converges in probability to a well defined random variable o

Freyja Hreinsdottir

Let $X=(x_{ij})$ and $Y=(y_{ij})$ be generic $n$ by $n$ matrices and $Z=XY-YX$. Let $S=k[x_{11},...,x_{nn},y_{11},...,y_{nn}]$, where $k$ is a field, let $I$ be the ideal generated by the entries of $Z$ and let $R=S/I$. We give a conjecture on the first syzygies of $I$, show how these can be used to give a conjecture on the canonical module of $R$. Using thi

James E. Keesling, Yuli B. Rudyak

We discuss which groups can be realized as the fundamental groups of compact Hausdorff spaces. In particular, we prove that the claim ``every group can be realized as the fundamental group of a compact Hausdorff space'' is consistent with the Zermelo - Fraenkel - Choice set theory.

Qihong Xie

We revisit the nef curve cone theorem and use it to reprove the pseudo-effectivity of the second Chern classes for terminal weak Q-Fano varieties.

J. -F. Fortin, P. Jacob, P. Mathieu

By jagged partitions we refer to an ordered collection of non-negative integers $(n_1,n_2,..., n_m)$ with $n_m\geq p$ for some positive integer $p$, further subject to some weakly decreasing conditions that prevent them for being genuine partitions. The case analyzed in greater detail here corresponds to $p=1$ and the following conditions $n_i\geq n_{i+1}-1$

Tetsushi Ito

The aim of this paper is to study certain properties of the weight spectral sequences of Rapoport-Zink by a specialization argument. By reducing to the case over finite fields previously treated by Deligne, we prove that the weight filtration and the monodromy filtration defined on the $l$-adic étale cohomology coincide, up to shift, for proper smooth variet

Artur Elezi

Let $Y$ be the zero loci of a regular section of a convex vector bundle $E$ over $X$. We provide a new proof of a conjecture of Cox, Katz and Lee for the virtual class of the genus zero moduli of stable maps to $Y$. This in turn yields the expected relationship between Gromov-Witten theories of $Y$ and $X$ which together with Mirror Theorems allows for the c

Artur Elezi

Let $X\subset Y$ be smooth, projective manifolds. Assume that $X$ is the zero locus of a generic section of a direct sum $V+$ of positive line bundles on $\PP^n$. Furthermore assume that the normal bundle $N_{X/Y}$ is a direct sum $V-$ of negative line bundles. We show that a $V:=V+\oplus V-$-twisted Gromov-Witten theory of $\PP^n$ restricts to the Gromov-Wi

J. C. Osborn, K. Splittorff, J. J. M. Verbaarschot

The relation between the spectral density of the QCD Dirac operator at nonzero baryon chemical potential and the chiral condensate is investigated. We use the analytical result for the eigenvalue density in the microscopic regime which shows oscillations with a period that scales as 1/V and an amplitude that diverges exponentially with the volume $V=L^4$. We

Filipe Paccetti Correia, Michael G. Schmidt, Zurab Tavartkiladze

We shortly review our new superfield formalism in the framework of Fujita, Kugo, Ohashi 5D conformal supergravity, in particular with an $S^1/Z_2$ orbifold. The radion of the fifth dimension is embedded in two related superfields, a chiral and a general multiplet and is linked to the radion superfield of rigid SUSY. The superspace action of the gauge sector

Joke Adam, Jos Gheerardyn, Bert Janssen, Yolanda Lozano

We present an elegant method to prove the invariance of the Chern-Simons part of the non-Abelian action for N coinciding D-branes under the R-R and NS-NS gauge transformations, by carefully defining what is meant by a background gauge transformation in the non-Abelian world volume action. We study as well the invariance under massive gauge transformations of

Seiji Sakoda

Basing on the canonical quantization of a BRS invariant Lagrangian, we construct holomorphic representation of path integrals for Faddeev-Popov(FP) ghosts as well as for unphysical degrees of the gauge field from covariant operator formalism. A thorough investigation of a simple soluble gauge model with finite degrees will explain the metric structure of the

Vyacheslav S. Rychkov

We revisit Voloshin's model of multiple black hole production in trans-Planckian elementary particle collisions in D=4. Our revised computation shows that the cross section to produce N additional black holes is suppressed by 1/s, rather than being enhanced as was originally found. We also review the semiclassical gravity picture of black hole production

H. Minakata, H. Nunokawa, W. J. C. Teves, R. Zukanovich Funchal

We demonstrate enormous power of dedicated reactor experiment for θ_{12} with a detector placed at around the first oscillation maximum, which we call "SADO". It allows determination of sin^2θ_{12} to the accuracy of \simeq 2% at 1 σCL, which surpasses all the method so far proposed. Unlike reactor θ_{13} experiments, the requirement for the systemat

W. Hollik

Work on electroweak precision calculations and event generators for electroweak physics studies at current and future colliders is summarized.

Goran Senjanovic

I review the profound connection between the see-saw mechanism for neutrino masses and grand unification. This connection points naturally towards SO(10) grand unified theory. The emphasis here is on the supersymmetric theory, but I also discuss salient features of its split supersymmetry version and ordinary non-supersymmetric SO(10). Particular attention i

M. V. Tokarev, Yu. A. Panebratsev, G. P. Skoro, I. Zborovsky

The properties of particle production in pp collisions are basis for analysis of pA and AA interactions and verification of theory. We analyzed inclusive particle production using z-scaling established in proton-proton and proton-antiproton collisions at the U70, ISR, Tevatron and RHIC. This scaling reflects symmetry of hadron structure, interaction and part

Shinta Kasuya, Fuminobu Takahashi

The smallness of the baryon asymmetry in our universe is one of the greatest mysteries and may originate from some profound physics beyond the standard model. We investigate the Affleck-Dine baryogenesis in split supersymmetry, and find that the smallness of the baryon asymmetry is directly related to the hierarchy between the supersymmetry breaking squark/s

Bohdan Grzadkowski, Jose Wudka

Within five-dimensional compactified theories we discuss generalized periodicity and orbifold boundary conditions that allow for mixing between particles and anti-particles after a shift by the size of extra dimensions or after the orbifold reflection. A systematic strategy for constructing 4-dimensional models is presented, in particular we find a general f

S. Rai Choudhury, Naveen Gaur, G. C. Joshi, B. H. J. McKellar

Little Higgs models provides us a new solution of the {\it hierarchy problem} of the SM. The problem is associated with the large difference in scales of SM and plank scale. One of the main features of these models is the existence of a vector like top quark. The CP violating $K_L \to π^0 ν\barν$ process n the SM model is dominated by top quark penguin & box

Justin Albert

We report on the initial measurements of the angle gamma and the sum of angles 2 beta + gamma of the Unitarity Triangle. When compared with indirect information on the value of gamma from other measurements of CKM parameters, the measurement of these angles will provide a precise test of Standard Model predictions, as statistics increase. There are several m

James Isenberg, David Maxwell, Daniel Pollack

We extend the conformal gluing construction of Isenberg-Mazzeo-Pollack [18] by establishing an analogous gluing result for field theories obtained by minimally coupling Einstein's gravitational theory with matter fields. We treat classical fields such as perfect fluids and the Yang-Mills equations as well as the Einstein-Vlasov system, which is an import

L. H. Ford

The operational meaning of spacetime fluctuations is discussed. Classical spacetime geometry can be viewed as encoding the relations between the motions of test particles in the geometry. By analogy, quantum fluctuations of spacetime geometry can be interpreted in terms of the fluctuations of these motions. Thus one can give meaning to spacetime fluctuations

R. Aloisio, A. Galante, A. F. Grillo, E. Luzio

In this note we discuss the possibility to define a space-time with a DSR based approach. We show that the strategy of defining a non linear realization of the Lorentz symmetry with a consistent vector composition law cannot be reconciled with the extra request of an invariant length (time) scale. The latter request forces to abandon the group structure of t

Xin-Bing Huang

The covariant Dirac equation in Robertson-Walker space-time is studied under the comoving coordinates. The exact forms of the spatial factor of wave function are respectively acquired in closed, spatially flat, and open universes.

Liang Zhou, Miruna Ticrea, Eduard Hovy

In this paper we describe a biography summarization system using sentence classification and ideas from information retrieval. Although the individual techniques are not new, assembling and applying them to generate multi-document biographies is new. Our system was evaluated in DUC2004. It is among the top performers in task 5-short summaries focused by pers

Ketan D. Mulmuley, Milind Sohoni

We point out that the remarkable Knutson and Tao Saturation Theorem and polynomial time algorithms for LP have together an important and immediate consequence in Geometric Complexity Theory. The problem of deciding positivity of Littlewood-Richardson coefficients for GLn(C) belongs to P. Furthermore, the algorithm is strongly polynomial. The main goal of thi

M. Poggio, D. D. Awschalom

A method for high-field optically detected nuclear magnetic resonance (ODNMR) is developed sensitive to 10**8 nuclei. Nuclear spin transitions are induced using a radio frequency coil and detected through Faraday rotation spectroscopy. Unlike conventional ODNMR, which is limited to low fields and relies on the measurement of time-averaged luminescence polari

Giovanni Russo, Peter Smereka

A numerical method for computation of heteroepitaxial growth in the presence of strain is presented. The model used is based on a solid-on-solid model with a cubic lattice. Elastic effects are incorporated using a ball and spring type model. The growing film is evolved using Kinetic Monte Carlo (KMC) and it is assumed that the film is in mechanical equilibri

Daniel Huber, Lev Tsimring

A network of noisy bistable elements with global time-delayed couplings is considered. A dichotomous mean field model has recently been developed describing the collective dynamics in such systems with uniform time delays near the bifurcation points. Here the theory is extended and applied to systems with nonuniform time delays. For strong enough couplings t

E. S. Choi, J. S. Brooks, H. Kang, Y. J. Jo

We examine an unusual phenomenon where, in tilted magnetic fields near magic angles parallel to crystallographic planes, a "giant" resonant Nernst signal has been observed by Wu et al.[Phys. Rev. Lett. 91 56601(2003)] in the metallic state of an organic conducting Bechgaard salt. We show that this effect appears to be a general feature of these mater

S. Galam, A. Mauger

We report on a possible crossover of a non universal quantity at the upper critical dimensionality in the field of percolation. Plotting recent estimates for site percolation thresholds of hypercubes in dimension 6< d< 13 against corresponding predictions from the GM formula p_c=p_0 [ (d-1)(q-1) ]^{-a} d^b for percolation thresholds, a significant departure

B. Watkins, H. Chashka, Y. Direktovich, A. Knizhnik

Using charge transport observations on sintered ceramic samples of CLBLCO, we failed to observe the Quantum Critical Point (QCP) where it is expected. Experimental data relating Cooper pair density, electrical conductivity, and superconductivity critical temperature suggest that Homes&#39; relation might need a more specific definition of &#39;sigma&#39;. Tr

Tapash Chakraborty, Pekka Pietiläinen

We demonstrate here that the dipole-allowed optical absorption spectrum of a parabolic quantum dot subjected to an external magnetic field reflects the inter-electron interaction effects when the spin-orbit interaction is also taken into account. We have investigated the energy spectra and the dipole-allowed transition energies for up to four interacting ele

Kirone Mallick, Philippe Marcq

The asymptotic behavior of a nonlinear oscillator subject to a multiplicative Ornstein-Uhlenbeck noise is investigated. When the dynamics is expressed in terms of energy-angle coordinates, it is observed that the angle is a fast variable as compared to the energy. Thus, an effective stochastic dynamics for the energy can be derived if the angular variable is

Jaume Masoliver, Josep Perello

We study the exponential Ornstein-Uhlenbeck stochastic volatility model and observe that the model shows a multiscale behavior in the volatility autocorrelation. It also exhibits a leverage correlation and a probability profile for the stationary volatility which are consistent with market observations. All these features make the model quite appealing since

Matthew T Glossop, Gareth E Jones, David E Logan

The pseudogap Anderson impurity model is a paradigm for locally critical quantum phase transitions. Within the framework of the local moment approach we study its finite-T dynamics, as embodied in the single-particle spectrum, in the vicinity of the symmetric quantum critical point (QCP) separating generalized Fermi-liquid (Kondo screened) and local moment p

Marko T. Cvitas, Pavel Soldan, Jeremy M. Hutson, Pascal Honvault

We have carried out the first quantum dynamics calculations on ultracold atom-diatom collisions in isotopic mixtures. The systems studied are spin-polarized 7Li + 6Li7Li, 7Li + 6Li2, 6Li + 6Li7Li and 6Li + 7Li2. Reactive scattering can occur for the first two systems even when the molecules are in their ground rovibrational states, but is slower than vibrati

M. M. Glazov, E. L. Ivchenko, R. v. Baltz, E. G. Tsitsishvili

We report on a theoretical study of the fine structure of excited excitonic levels in semiconductor quantum disks. A particular attention is paid to the effect of electron-hole long-range exchange interaction. We demonstrate that, even in the axisymmetric quantum disks, the exciton P-shell is split into three sublevels. The analytical results are obtained in

T. Kwapinski, R. Taranko, E. Taranko

We have studied the electron transport through a quantum dot coupled to three leads in the presence of external microwave fields supplied to different parts of the considered mesoscopic system. Additionally, we introduced a possible nonresonant tunneling channels between leads. The quantum dot charge and currents were determined in terms of the appropriate e

Yuriy E. Kuzovlev

The generating functional is derived for the fluctuation-dissipation relations which result from the unitarity and reversibility of microscopic dynamics and connect various statistical characteristics of many consecutive (continuous) observations in a quantum system subjected to external perturbations. Consequences of these relations in respect to the earlie

Tu Yu-Song, A. O. Sousa, Kong Ling-Jiang, Liu Mu-Ren

We analyze the evolution of Sznajd Model with synchronous updating in several complex networks. Similar to the model on square lattice, we have found a transition between the state with no-consensus and the state with complete consensus in several complex networks. Furthermore, by adjusting the network parameters, we find that a large clustering coefficient

Keitaro Sakurazawa, Hiroshi Kontani, Tetsuro Saso

We propose the mechanism for the magnetic-field-induced antiferromagnetic (AFM) state in a two-dimensional Hubbard model in the vicinity of the AFM quantum critical point (QCP), using the fluctuation-exchange (FLEX) approximation by taking the Zeeman energy due to the magnetic field $B$ into account. In the vicinity of the QCP, we find that the AFM correlati

S. V. Belim

A field-theoretical description of the behavior of compressible Ising systems with long-range interactions is presented. The description is performed in the two-loop approximation in three dimensions with the use of the Pade-Borel resummation technique. The renormalization group equations are analyzed, and the fixed points that determine the critical behavio

J. Schnack

The synthesis of molecular magnets has undergone rapid progress in recent years. Each of the identical molecular units can contain as few as two and up to several dozens of paramagnetic ions (spins). Although these materials appear as macroscopic samples, i.e. crystals or powders, the intermolecular magnetic interactions are utterly negligible as compared to

Catrin Ellenberger, Florian Gebhard, Wolfgang Bestgen

In type-I superconducting cylinders bulk superconductivity is destroyed above the first critical current. Below the second critical current the `type-I mixed state&#39; displays fluctuation superconductivity which contributes to the total current. A magnetic flux on the axis of the cylinder can change the second critical current by as much as 50 percent so t

L. J. Swenson, D. R. Schmidt, J. S. Aldridge, D. K. Wood

By configuring a radio-frequency single-electron transistor as a mixer, we demonstrate a unique implementation of this device, that achieves good charge sensitivity with large bandwidth about a tunable center frequency. In our implementation we achieve a measurement bandwidth of 16 MHz, with a tunable center frequency from 0 to 1.2 GHz, demonstrated with the

M. Taguchi, A. Chainani, K. Horiba, Y. Takata

Hard X-ray Photoemission spectroscopy (PES) of copper core electronic states, with a probing depth of $\sim$60 Å, is used to show that the Zhang-Rice singlet feature is present in La$_2$CuO$_4$ but is absent in Nd$_2$CuO$_4$. Hole- and electron doping in La$_{2-x}$Sr$_x$CuO$_4$ (LSCO) and Nd$_{2-x}$Ce$_x$CuO$_4$ (NCCO) result in new well-screened features wh

H. Rho, S. L. Cooper, S. Nakatsuji, H. Fukazawa

We present a Raman scattering study of Ca$_2$RuO$_4$, in which we investigate the temperature-dependence of the lattice dynamics and the electron-phonon interaction below the metal-insulator transition temperature ({\it T}$_{\rm MI}$). Raman spectra obtained in a backscattering geometry with light polarized in the ab-plane reveal 9 B$_{1g}$ phonon modes (140

Amit P. Mehta, Karin A. Dahmen, M. W. Weissman, Tim Wotherspoon

We present a novel analytic calculation of the Haar power spectra, and various higher order spectra, of mean field avalanche models. We also compute these spectra from a simulation of the zero-temperature mean field RFIM and infinite range RFIM model for $d = 3$. We compare the results and obtain novel exponents.

L. E. Silbert

Granular simulations are used to probe the particle scale dynamics at short, intermediate, and long time scales for gravity driven, dense granular flows down an inclined plane. On approach to the angle of repose, where motion ceases, the dynamics become intermittent over intermediate times, with strong temporal correlations between particle motions -- tempor

L. E. Silbert, A. J. Liu, S. R. Nagel

We numerically study the vibrations of jammed packings of particles interacting with finite-range, repulsive potentials at zero temperature. As the packing fraction $ϕ$ is lowered towards the onset of unjamming at $ϕ_{c}$, the density of vibrational states approaches a non-zero value in the limit of zero frequency. For $ϕ>ϕ_{c}$, there is a crossover frequen

Christian Flindt, Tomas Novotny, Antti-Pekka Jauho

We develop a theory for the full counting statistics (FCS) for a class of nanoelectromechanical systems (NEMS), describable by a Markovian generalized master equation. The theory is applied to two specific examples of current interest: vibrating C60 molecules and quantum shuttles. We report a numerical evaluation of the first three cumulants for the C60-setu

Hugo Touchette, Christian Beck

Superstatistics are superpositions of different statistics relevant for driven nonequilibrium systems with spatiotemporal inhomogeneities of an intensive variable (e.g., the inverse temperature). They contain Tsallis statistics as a special case. We develop here a technique that allows us to analyze the large energy asymptotics of the stationary distribution

J. A. Santiago, A. Zamora

Using a covariant geometric approach we obtain the effective bending couplings for a 2-dimensional rigid membrane embedded into a $(2+D)$-dimensional Euclidean space. The Hamiltonian for the membrane has three terms: The first one is quadratic in its mean extrinsic curvature. The second one is proportional to its Gaussian curvature, and the last one is propo

Robert S. Whitney, Yuriy Makhlin, Alexander Shnirman, Yuval Gefen

We investigate the geometric phase or Berry phase (BP) acquired by a spin-half which is both subject to a slowly varying magnetic field and weakly-coupled to a dissipative environment (either quantum or classical). We study how this phase is modified by the environment and find that the modification is of a geometric nature. While the original BP (for an iso

J. C. Loudon, S. Cox, A. J. Williams, J. P. Attfield

Modulations in manganites attributed to stripes of charge/orbital/spin order are thought to result from strong electron-lattice interactions that lock the superlattice and parent lattice periodicities. Surprisingly in La1-xCaxMnO3(x>0.5, 90 K), convergent beam (3.6 nm spot) electron diffraction patterns rule out charge stacking faults and indicate a superlat

F. Halzen

Kilometer-scale neutrino detectors such as IceCube are discovery instruments covering nuclear and particle physics, cosmology and astronomy. Examples of their multidisciplinary missions include the search for the particle nature of dark matter and for additional small dimensions of space. In the end, their conceptual design is very much anchored to the obser

A. P. Boss, R. H. Durisen

Chondrules are mm-sized spherules found throughout primitive, chondritic meteorites. Flash heating by a shock front is the leading explanation of their formation. However, identifying a mechanism for creating shock fronts inside the solar nebula has been difficult. In a gaseous disk capable of forming Jupiter, the disk must have been marginally gravitational

Gary Steigman

The relic abundances of the light elements synthesized during the first few minutes of the evolution of the Universe provide unique probes of cosmology and the building blocks for stellar and galactic chemical evolution, while also enabling constraints on the baryon (nucleon) density and on models of particle physics beyond the standard model. Recent WMAP an

L. Perivolaropoulos

The cosmic string theory for cosmological fluctuations is a good example of healthy scientific progress in cosmology. It is a well defined physically motivated model that has been tested by cosmological observations and has been ruled out as a primary source of primordial fluctuations. Until about fifteen years ago, the cosmic string theory of cosmological p

Daisuke Iono, Min S. Yun, Paul T. P. Ho

We present HI and CO(1-0) interferometric observations of 10 comparable-mass interacting systems obtained at the Very Large Array (VLA) and the Owens Valley Radio Observatory (OVRO) millimeter array. The primary intent of this study is to investigate the response of cold gas during the early stages of collision of massive disk galaxies. The sample sources ar

E. Jimenez-Bailon, E. Piconcelli, M. Guainazzi, N. Schartel

The properties of the fluorescence Fe K-alpha emission lines of a sample of 38 quasars (QSOs) observed with XMM-Newton are studied. These objects are included in the optically selected sample from the Palomar-Green (PG) Bright Quasar Survey with an X-ray luminosity 1.3E43<L(2-10 keV)<5.1E45 ergs/s and z<1.72. For each object in the sample, we investigated th

D. Breitschwerdt, M. A. de Avillez, M. J. Freyberg

The observational and theoretical state of Galactic and extragalactic bubbles are reviewed. Observations of superbubbles are discussed, with some emphasis on nearby bubbles such as the Local Bubble (LB) and the Loop I superbubble (LI). Analytical bubble theory is revisited, and similarity solutions, including the time-dependent energy input by supernova expl

Ch. R. Cowley, S. Hubrig

Chemically peculiar stars in the magnetic sequence can show the same isotopic anomaly in calcium previously discovered for mercury-manganese stars in the non-magnetic sequence. In extreme cases, the dominant isotope is the exotic 48^Ca. Measurements of Ca II lines arising from 3d-4p transitions reveal the anomaly by showing shifts up to 0.2 AA for the extrem

Immo Appenzeller, Claude Bertout, Otmar Stahl

Using the UVES echelle spectrograph at the ESO VLT we obtained two-dimensional high-resolution (R = 50 000) spectra of the edge-on disk objects HH30*, HK Tau B, and HV Tau C. For comparison purposes we also observed with the same equipment both the classical T Tauri star HL Tau and the active late-type star LDN 1551-9. The spectra of all three observed edge-

V. Karas, M. Dovciak, G. Matt

We discuss the effects of strong gravity on the polarization properties of a black hole accretion disc. The intrinsic polarization is computed taking into account light scattered on the disc surface and using different approximations. The gravitational field of a black hole influences the Stokes parameters of reflected radiation propagating to a distant obse

Christopher J. Deloye, Lars Bildsten, Gijs Nelemans

We apply the Deloye & Bildsten (2003) isentropic models for donors in ultracompact low-mass X-ray binaries to the AM CVn population of ultracompact, interacting binaries. The mass-radius relations of these systems&#39; donors in the mass range of interest ($M_2<0.1 \msun$) are not single-valued, but parameterized by the donor&#39;s specific entropy. This pro

Josep M. Paredes

Microquasars are X-ray binary stars with the capability to generate relativisticjets. It is expected that microquasars are gamma-ray sources, because of the analogy with quasars and because the theoretical models predict emission at such energy range. In addition, from observational arguments, there are two microquasars that appear as the possible counterpar

A. M. Bykov

The nonthermal phenomena in clusters of galaxies are considered in the context of the hierarchical model of cosmic structure formation by accretion and merging of the dark matter (DM) substructures.Accretion and merging processes produce large-scale gas shocks. The plasma shocks are expected to be collisionless. In the course of cluster&#39;s aggregation, th

Grazyna Stasinska

Using ab-initio photoionization models of giant HII regions, we test methods for abundance determinations based on a direct measurement of the electron temperature, now possible even for moderate to high-metallicity objects. We find that, for metallicities larger than solar, the computed abundances deviate systematically from the real ones, generally by larg

B. R. Brandl

30 Doradus is the closest massive star forming region and the best studied template of a starburst. In this conference paper we first summarize the properties of 30 Doradus and its stellar core, R136. We discuss the effects of insufficient spatial resolution and cluster density profiles on dynamical mass estimates of super star clusters, and show that their

Antonio Masiero, Francesca Rosati

Although a direct interaction between WIMP CDM candidates and scalar Quintessence fields (sources of Dark Energy) poses severe phenomenological threats, yet it is possible that the presence of Quintessence produces profound deviations in the expansion rate of the early Universe at the moment of WIMP decoupling, hence causing significant enhancements of the r

C. P. Dullemond, I. M. van Bemmel

We discuss the question whether the matter in dusty tori around active galactic nuclei has a smooth or a clumpy structure. Nenkova, Ivezic & Elitzur (2002) have argued that the lack of emission feature in the SEDs of type 1 AGN galaxies combined with a clear absorption feature in type 2 AGN can be explained if the circumnuclear dust is distributed in discret

J. Meaburn, P. Boumis, P. E. Christopoulou, C. D. Goudis

Spatially resolved profiles of the HeII 6560 A, Halpha and [N II] 6548 & 6584 A nebular emission lines have been obtained in two orthogonal long cuts over the Dumbbell planetary nebula. The central HeII 6560 A emitting volume of the bright dumbbell structure is shown to be particularly inert with an expansion velocity of <= 7 km/s. This is enveloped by an in

B. R. Brandl, S. Portegies Zwart, A. J. F. Moffat, D. F. Chernoff

We discuss the signature of a peculiar constellation of very massive stars at a projected distance of 2-3 pc around R136a. We discuss various scenarios for its possible origin, such as independent clusters, triggered star formation, supernovae, and ejections via dynamical interactions. If the latter scenario were the correct one this would have significant i

V. F. Cardone, M. Sereno

We use the adiabatic compression theory to build a physically well - motivated Milky Way mass model in agreement with the observational data. The visible mass of the Galaxy is distributed in a spheroidal bulge and a multi - components disc parametrized by three galactic parameters, the Sun distance to the galactic centre, R_0, the total bulge mass, M_{bulge}

Matthias Stute, Max Camenzind

We compare two scenarios to launch jets -- formation by MHD processes or formation by thermal pressure in the boundary layer (BL) -- with respect to their compatibility with observational data of jets in symbiotic stars, especially in the well studied jet source MWC 560. Finally, we discuss points of further research to be done.

A. S. Cohen, T. E. Clarke, L. Feretti, N. E. Kassim

It has long been know that an extremely steep spectrum radio source lies at the center of ZwCl 0735.7+7421, a galaxy cluster with high X-ray luminosity and a cooling core. In this Letter, we present VLA observations of this radio source at both 1425 and 325 MHz. With a resolution below 21&#39;&#39; (75 kpc) for both 1425 and 325 MHz, we show the morphology o

B. M. Gaensler, N. M. McClure-Griffiths, M. S. Oey, M. Haverkorn

We present 21-cm HI observations from the Southern Galactic Plane Survey of the field around the anomalous X-ray pulsar 1E 1048.1-5937, a source whose X-ray properties imply that it is a highly magnetized neutron star (a &#34;magnetar&#34;). These data reveal an expanding hydrogen shell, GSH 288.3-0.5-28, centered on 1E 1048.1-5937, with a diameter of 35x23

M. Spite, R. Cayrel, B. Plez, V. Hill

We have investigated the poorly-understood origin of nitrogen in the early Galaxy by determining N abundances in 35 extremely metal-poor halo giants (22 stars have [Fe/H]<-3.0) using the C and O abundances determined in Paper V. Because any dredge-up of CNO processed material to the surface may complicate the interpretation of CNO abundances in giants, we ha

L. Li, Y. Meurice

We discuss the weak coupling expansion of a one plaquette SU(2) lattice gauge theory. We show that the conventional perturbative series for the partition function has a zero radius of convergence and is asymptotic. The average plaquette is discontinuous at g^2=0. However, the fact that SU(2) is compact provides a perturbative sum that converges toward the co

Benjamin Grinstein, Dan Pirjol

We describe a chiral formalism for processes involving both energetic hadrons and soft Goldstone bosons, which extends the application of soft-collinear effective theory to multibody B decays. The nonfactorizable helicity amplitudes for heavy meson decays into multibody final states satisfy symmetry relations analogous to the large energy form factor relatio

Z. Idziaszek, L. Santos, M. Lewenstein

We study the sympathetic cooling of a trapped Fermi gas interacting with an ideal Bose gas below the critical temperature of the Bose-Einstein condensation. We derive the quantum master equation, which describes the dynamics of the fermionic component, and postulating the thermal distribution for both gases we calculate analytically the rate at which fermion

Donald F. Figer, Francisco Najarro, T. R. Geballe, R. D. Blum

We report the discovery of additional hot and massive stars in the cluster surrounding the soft gamma repeater SGR 1806-20, based upon UKIRT and Keck near-infrared spectroscopy. Of the newly identified stars, three are Wolf-Rayet stars of types WC8, WN6, and WN7, and a fourth star is an OB supergiant. These three stars, along with four previously discovered,

David L. Band, Robert D. Preece

Building on Nakar & Piran&#39;s analysis of the Amati relation relating gamma-ray burst peak energies E_p and isotropic energies E_iso, we test the consistency of a large sample of BATSE bursts with the Amati and Ghirlanda (which relates peak energies and actual gamma-ray energies E_gamma) relations. Each of these relations can be expressed as a ratio of the

Dmitri Kharzeev, Kirill Tuchin

We propose a new thermalization scenario for heavy ion collisions which at sufficiently high energies implies the phase transition to the quark--gluon plasma. The key ingredient of our approach is the Hawking--Unruh effect: an observer moving with an acceleration $a$ experiences the influence of a thermal bath with an effective temperature $T = a / 2π$, simi

I. Y. Park, A. Tirziu, A. A. Tseytlin

We consider a circular string with spin $S$ in $AdS_5$ wrapped around big circle of $S^5$ and carrying also momentum $J$. The corresponding N=4 SYM operator belongs to the SL(2) sector, i.e. has tr$(D^S Z^J)+...$ structure. The leading large $J$ term in its 1-loop anomalous dimension can be computed using Bethe ansatz for the SL(2) spin chain and was previou

A. Huebsch, R. G. Endres, D. L. Cox, R. R. P. Singh

Motivated by recent experiments we have studied the optical conductivity of DNA in its natural environment containing water molecules and counter ions. Our density functional theory calculations (using SIESTA) for four base pair B-DNA with order 250 surrounding water molecules suggest a thermally activated doping of the DNA by water states which generically

I. L. Buchbinder, S. James Gates,, S. M. Kuzenko, J. Phillips

Lagrangians for several new off-shell 4D, N = 1 supersymmetric descriptions of massive superspin-1 and superspin-3/2 multiplets are described. Taken together with the models previously constructed, there are now four off-shell formulations for the massive gravitino multiplet (superspin-1) and six off-shell formulations for the massive graviton multiplet (sup

Gianfranco Bertone, David Merritt

The prospects of indirect detection of dark matter at the galactic center depend sensitively on the mass profile within the inner parsec. We calculate the distribution of dark matter on sub-parsec scales by integrating the time-dependent Fokker-Planck equation, including the effects of self-annihilations, scattering of dark matter particles by stars, and cap

K. Eng, R. N. McFarland, B. E. Kane

We have fabricated and characterized a field-effect transistor in which an electric field is applied through an encapsulated vacuum cavity and induces a two-dimensional electron system on a hydrogen-passivated Si(111) surface. This vacuum cavity preserves the ambient sensitive surface and is created via room temperature contact bonding of two Si substrates.

G. Gerardi, D. Molteni, V. Teresi

We present the simulation of 3D time dependent flow of rotating ideal gas falling into a Schwarzschild black hole. It is shown that also in the 3D case steady shocks are formed in a wide range of parameters (initial angular momentum and thermal energy). We therefore highlight the stability of the phenomenon of shock formation in sub keplerian flows onto blac

M. R. Ahmed, G. A. Gehring

A study is made of an anisotropic Potts model in three dimensions where the coupling depends on both the Potts state on each site but also the direction of the bond between them using both analytical and numerical methods. The phase diagram is mapped out for all values of the exchange interactions. Six distinct phases are identified. Monte Carlo simulations

Hidekazu Hanayama, Keitaro Takahashi, Kei Kotake, Masamune Oguri

We study generation of magnetic fields by the Biermann mechanism in the pair-instability supernovae explosions of first stars. The Biermann mechanism produces magnetic fields in the shocked region between the bubble and interstellar medium (ISM), even if magnetic fields are absent initially. We perform a series of two-dimensional magnetohydrodynamic simulati

H. -J. Mikeska, A. K. Kolezhuk

This paper has been withdrawn.