February 2006 arXiv papers — page 13

A. C. D. van Enter, C. Kuelske

In this contribution we discuss the role disordered (or random) systems have played in the study of non-Gibbsian measures. This role has two main aspects, the distinction between which has not always been fully clear: 1) {\em From} disordered systems: Disordered systems can be used as a tool; analogies with, as well as results and methods from the study of r

Martin Kassabov, Nikolay Nikolov

We prove that if a Cartesian product of alternating groups is topologically finitely generated, then it is the profinite completion of a finitely generated residually finite group. The same holds for Cartesian producs of other simple groups under some natural restrictions.

Zoltan I. Szabo

The problem of infinities (divergent integrals) appearing in quantum field theory or elementary particle physics are treated by renormalization in the current theories. By this perturbative tool the desired finite quantities are produced by differences of infinities. This paper gives a new non-perturbative approach to this problem. Namely, the Hilbert space

Erlend Fornaess Wold

For certain bordered submanifolds $M\subset\CC^2$ we show that $M$ can be embedded properly and holomorphically into $\CC^2$. An application is that any subset of a torus with two boundary components can be embedded properly into $\CC^2$.

Vladimir Chilin, Semyon Litvinov

Utilizing the notion of uniform equicontinuity for sequences of functions with the values in the space of measurable operators, we present a non-commutative version of the Banach Principle for $L^\infty$.

J. A. Rodriguez

The conditional diameter of a connected graph $Γ=(V,E)$ is defined as follows: given a property ${\cal P}$ of a pair $(Γ_1, Γ_2)$ of subgraphs of $Γ$, the so-called \emph{conditional diameter} or ${\cal P}$-{\em diameter} measures the maximum distance among subgraphs satisfying ${\cal P}$. That is, \[ D_{\cal P}(Γ):=\max_{Γ_1, Γ_2\subset Γ} \{\partial(Γ_1, Γ

J. A. Rodriguez, J. M. Sigarreta

In this paper we obtain several tight bounds on different types of alliance numbers of a graph: (global) defensive alliance number, global offensive alliance number and global dual alliance number. In particular, we investigate the relationship between the alliance numbers of a graph and its algebraic connectivity, its spectral radius, and its Laplacian spec

A. V. Kiselev, V. I. Varlamov

A class of spiral minimal surfaces in E^3 is constructed using a symmetry reduction. The new surfaces are invariant with respect to the composition of rotation and dilatation. The solutions are obtained in closed form %through the Legendre transformation and their asymptotic behaviour is described.

J. M. Sigarreta, J. A. Rodriguez

Let $Γ$ be a simple graph of size $m$ and degree sequence $δ_1\ge δ_2\ge ... \ge δ_n$. Let ${\cal L}(Γ)$ denotes the line graph of $Γ$. The aim of this paper is to study mathematical properties of the alliance number, ${a}({\cal L}(Γ)$, and the global alliance number, $γ_{a}({\cal L}(Γ))$, of the line graph of a simple graph. We show that $\lceil\frac{δ_{n}+

Vasily E. Tarasov

We consider an invariant skew-symmetric phase-space metric for non-Hamiltonian systems. We say that the metric is an invariant if the metric tensor field is an integral of motion. We derive the time-dependent skew-symmetric phase-space metric that satisfies the Jacobi identity. The example of non-Hamiltonian systems with linear friction term is considered.

J. M. Sigarreta, J. A. Rodriguez

An offensive alliance in a graph $Γ=(V,E)$ is a set of vertices $S\subset V$ where for every vertex $v$ in its boundary it holds that the majority of vertices in $v$'s closed neighborhood are in $S$. In the case of strong offensive alliance, strict majority is required. An alliance $S$ is called global if it affects every vertex in $V\backslash S$, that

J. M. Perez Izquierdo

We prove that the only proper right ideal of the universal enveloping algebra of a finite-dimensional central simple Lie triple system over a field of characteristic zero is its augmentation ideal.

Valentin Konakov, Enno Mammen

We consider triangular arrays of Markov chains that converge weakly to a diffusion process. Edgeworth type expansions of third order for transition densities are proved. This is done for time horizons that converge to 0. For this purpose we represent the transition density as a functional of densities of sums of i.i.d. variables. This will be done by applica

Valentin Konakov

We consider triangular arrays of Markov chains that converge weakly to a diffusion process. Local limit theorems for transition densities are proved. The observation time [0,T] may be fixed or lim n T = 0, where nh = T and h is a mesh between two neighboring observation points.

Olvido Delgado, Javier Soria

We study the optimal domain for the Hardy operator considered with values in a rearrangement invariant space. In particular, this domain can be represented as the space of integrable functions with respect to a vector measure defined on a $δ$-ring. A precise description is given for the case of the minimal Lorentz spaces.

Ana Rita Martins

Let $X$ be a complex manifold. In "Microlocal study of Ind-sheaves I: microsupport and regularity", M. Kashiwara e P. Schapira made the conjecture that a holonomic D-module $\shm$ is regular holonomic if and only if $R\mathcal{I}{hom}_{β_X\shd_X}(β_X\shm,\sho_X^t)$ is regular (in the sense of "Microlocal study of Ind-sheaves I: microsupport and r

Tilman Bauer, Natalia Castellana

For a compact Lie group $G$ with maximal torus $T$, Pittie and Smith showed that the flag variety $G/T$ is always a stably framed boundary. We generalize this to the category of $p$-compact groups, where the geometric argument is replaced by a homotopy theoretic argument showing that the class in the stable homotopy groups of spheres represented by $G/T$ is

Satoshi Naito, Daisuke Sagaki

We give interpretations of energy functions and (classically restricted) one-dimensional sums associated to tensor products of level-zero fundamental representations of quantum affine algebras in terms of Lakshmibai-Seshadri paths of level-zero weight shape.

David Marker, Theodore A. Slaman

We consider the fragment F of first order arithmetic in which quantification is restricted to ''for all but finitely many.'' We show that the integers form an F-elementary substructure of the real numbers. Consequently, the F-theory of arithmetic is decidable.

Kalvis M. Jansons, Paul D. Metcalfe

We discuss the optimal Markovian coupling before an exponential time of the Kolmogorov diffusion, and a class of related stochastic control problems in which the aim is to hit the origin before an exponential time. We provide a scaling argument for the optimal control in the near field and use rational WKB approximation to obtain the optimal control in the f

Ravi Vakil

The goal of this article is to motivate and describe how Gromov-Witten theory can and has provided tools to understand the moduli space of curves. For example, ideas and methods from Gromov-Witten theory have led to both conjectures and theorems showing that the tautological part of the cohomology ring has a remarkable and profound structure. As an illustrat

Akira Sano

We recall the projective variety parametrizing a family of special lattices over Witt vectors. It is normal and Gorenstein. In this article, we prove that there exists a particular set of subvarieties in it that are also normal and Gorenstein. The set contains the subregular variety.

Teodor Stefan Bildea

In this paper, we exhibit strongly singular maximal abelian subalgebras living inside certain k-folded tensors of von Neumann group factors. The two classes of groups under consideration are the free groups of rank greater than 2 and the free product of m>2 groups, all finite and having the same order p>2 (m>p-1). We prove actually more, namely that the uniq

Marco Hien

We define a period pairing for flat, irregular singular, rank one connections, satisfying a technical condition regarding its stationary set, on complex surfaces between de Rham cohomology of the connection and a modified singular homology, the rapid decay homology. We prove that this gives a perfect duality. A 2-dimensional version of confluent hypergeometr

Mikhail Khovanov

We explain how rank two Frobenius extensions of commutative rings lead to link homology theories and discuss relations between these theories, Bar-Natan theories, equivariant cohomology and the Rasmussen invariant.

Alan L. Carey, Bai-Ling Wang

The goal of this paper is to apply the universal gerbe of \cite{CMi1} and \cite{CMi2} to give an alternative, simple and more unified view of the relationship between index theory and gerbes. We discuss determinant bundle gerbes \cite{CMMi1} and the index gerbe of \cite{L} for the case of families of Dirac operators on odd dimensional closed manifolds. The m

A. V. Smilga

5D superconformal theories involve vacuum valleys characterized in the simplest case by the vacuum expectation value of a real scalar field. If it is nonzero, conformal invariance is spontaneously broken and the theory is not renormalizable. In the conformally invariant sector with zero scalar v.e.v., the theory is intrinsically nonperturbative. We study cla

S. Bellucci, S. Krivonos

These Lectures have been given at Laboratori Nazionali di Frascati in the month of March, 2005. The main idea was to provide our young collegues, who joined us in our attempts to understand the structure of $N$-extended supersymmetric one-dimensional systems, with short descriptions of the methods and techniques we use. This was reflected in the choice of ma

Hongwei Yu, Jun Chen, Puxun Wu

We discuss the random motion of charged test particles driven by quantum electromagnetic fluctuations at finite temperature in both the unbounded flat space and flat spacetime with a reflecting boundary and calculate the mean squared fluctuations in the velocity and position of the test particle. We show that typically the random motion driven by the quantum

Akira Kokado, Gaku Konisi, Takesi Saito

When open strings end with a charge q on a D2-brane, which involves constant background magnetic field B perpendicular to the brane, we calculate the Hall conductivity for these charged strings. We also construct the corresponding spectrum-generating algebra, which assures that our system is ghost-free under some conditions.

Merced Montesinos, Ernesto Flores

The symmetric and gauge-invariant energy-momentum tensors for source-free Maxwell and Yang-Mills theories are obtained by means of translations in spacetime via a systematic implementation of Noether's theorem. For the source-free neutral Proca field, the same procedure yields also the symmetric energy-momentum tensor. In all cases, the key point to get

R. K. Ellis, W. T. Giele, Giulia Zanderighi

We present results for the six-gluon scattering amplitude at one-loop. Since our method is semi-numerical, it yields the result for arbitrary momenta and helicities of the external gluons. We evaluate the colour-ordered sub-amplitudes with gluons, fermions and scalars running in the internal loop. This is more than sufficient to give a complete description o

R. S. Pasechnik, V. A. Beylin, V. I. Kuksa, G. M. Vereshkov

Rare astrophysical events - cosmological gamma-ray bursts with energies over GeV - are considered as an origin of information about some SUSY parameters. The model of generation of the powerful gamma-ray bursts is proposed. According to this model the gamma-ray burst represents as a result of the collapse and the total annihilation of the neutralino clump. A

J. Casalderrey-Solana, E. V. Shuryak, D. Teaney

We study the interaction of a fast moving particle in the Quark Gluon Plasma with linearized hydrodynamics. We derive the linearized hydrodynamic equations on top of an expanding fireball, and detail the solutions for a static medium. There are two modes far from the jet -- a sound mode and a diffusion mode. The diffusion mode is localized in a narrow wake b

M. Ciminale, G. Nardulli, M. Ruggieri, R. Gatto

We compute in the Ginzburg-Landau approximation the gluon Meissner masses for the Larkin-Ovchinnikov-Fulde-Ferrell (LOFF) phase of QCD with three flavors in the kinematical range where it is energetically favored. We find real Meissner masses and therefore chromomagnetic stability.

B. A. Kniehl, D. V. Vasin, V. A. Saleev

We study charmonium production at high-energy colliders (Tevatron, HERA, and LEP2) in the framework of the k_T-factorization approach and the factorization formalism of non-relativistic quantum chromodynamics at leading order in the strong-coupling constant alpha_s and the relative velocity v. The transverse-momentum distributions of direct and prompt J/psi-

Ruth Britto, Bo Feng, Pierpaolo Mastrolia

Unitarity cuts are widely used in analytic computation of loop amplitudes in gauge theories such as QCD. We expand upon the technique introduced in hep-ph/0503132 to carry out any finite unitarity cut integral. This technique naturally separates the contributions of bubble, triangle and box integrals in one-loop amplitudes and is not constrained to any parti

Yong-Liang Ma, Qing Wang, Yue-Liang Wu

The anomalous action of the chiral effective theory to $\mathcal{O}(p^4)$ is investigated by generalizing the consideration in \cite{ma02} with including the wave function part in the general quark propagator. It is found that the QCD dynamics dependence of the Wess-Zumino term is explicit and this dependence means that the QCD chiral symmetry must be broken

Alessandro Cafarella, Claudio Coriano', Marco Guzzi

Aspects of the QCD parton densities are briefly reviewed, drawing some parallels to the density matrix formulation of quantum mechanics, exemplified by Wigner functions. We elaborate on the solution of their evolution equations using logarithmic expansions and overview their kinetic interpretation. We illustrate how a Fokker-Planck equation can be derived us

G. Dillon, G. Morpurgo

This paper deals with how to extract the s-s(bar) contribution to the proton magnetic moment from the experiments

Muon, Collaboration, :, G. W. Bennett

We present the final report from a series of precision measurements of the muon anomalous magnetic moment, a_mu = (g-2)/2. The details of the experimental method, apparatus, data taking, and analysis are summarized. Data obtained at Brookhaven National Laboratory, using nearly equal samples of positive and negative muons, were used to deduce a_mu(Expt) = 11

Jelle Hartong, André Ploegh, Thomas Van Riet, Dennis B. Westra

We study the dynamics of multiple scalar fields and a barotropic fluid in an FLRW-universe. The scalar potential is a sum of exponentials. All critical points are constructed and these include scaling and de Sitter solutions. A stability analysis of the critical points is performed for generalized assisted inflation, which is an extension of assisted inflati

Nosratollah Jafari, Ahmad Shariati

Double Special Relativity theories are the relativistic theories in which the transformations between inertial observers are characterized by two observer-independent scales of the light speed and the Planck length. We study two main examples of these theories and want to show that these theories are not the new theories of relativity, but only are re-descri

Eirik Rosnes, Øyvind Ytrehus

This paper is devoted to the finite-length analysis of turbo decoding over the binary erasure channel (BEC). The performance of iterative belief-propagation (BP) decoding of low-density parity-check (LDPC) codes over the BEC can be characterized in terms of stopping sets. We describe turbo decoding on the BEC which is simpler than turbo decoding on other cha

Alexandros G. Dimakis, Anand D. Sarwate, Martin J. Wainwright

Gossip algorithms for aggregation have recently received significant attention for sensor network applications because of their simplicity and robustness in noisy and uncertain environments. However, gossip algorithms can waste significant energy by essentially passing around redundant information multiple times. For realistic sensor network model topologies

Nathan Boeger

The technical challenges of scaling websites with large and growing member bases, like social networking sites, are numerous. One of these challenges is how to evenly distribute the growing member base across all available resources. This paper will explore various methods that address this issue. The techniques used in this paper can be generalized and appl

Degang Zhang

We study a two-dimensional electron system in the presence of both Rashba and Dresselhaus spin-orbit interactions in a perpendicular magnetic field. Defining two suitable boson operators and using the unitary transformations we are able to obtain the exact Landau levels in the range of all the parameters. When the strengths of the Rashba and Dresselhaus spin

A. Widom, L. Larsen

Low energy nuclear transmutations have been reported in experimental chemical electrolytic cells employing metallic hydride electrodes. Assuming that the nuclear transmutations are induced by ultra-low momentum neutron absorption, the expected chemical cell nuclear abundances are discussed on the basis of a neutron optical potential model. The theoretical re

Vadim V. Cheianov, H. Smith, M. B. Zvonarev

We develop a method for the calculation of vacuum expectation values of local operators in the Lieb-Liniger model. This method is based on a set of new identities obtained using integrability and effective theory (``bosonization'') description. We use this method to get an explicit expression for the three-body local correlation function, measured in

Anatoly Kuklov, Nikolay Prokof'ev, Boris Svistunov, Matthias Troyer

We perform a comparative Monte Carlo study of the easy-plane deconfined critical point (DCP) action and its short-range counterpart to reveal close similarities between the two models for intermediate and strong coupling regimes. For weak coupling, the structure of the phase diagram depends on the interaction range: while the short-range model features a tri

David C. Morse

A straightforward expansion of Edwards' functional integral representation of the grand partition function for a polymer liquid as an infinite set of Feynman diagrams is shown to yield a cluster expansion that is closely related to the corresponding Mayer cluster expansion developed for flexible molecules by Chandler and coworkers. The procedure initiall

Fabio Chiarello

A double SQUID manipulated by fast magnetic flux pulses can be used as a tunable flux qubit. In this paper we study the requirements for the qubit operation, and evaluate dissipation and decoherence due to the manipulation for a typical system. Furthermore, we discuss the possibility to use an integrated Rapid Single Flux Quantum logic for the qubit control.

Julian Oberdisse, Giovanni Ianniruberto, Francesco Greco, Guiseppe Marrucci

The mechanical properties of a polymeric network containing both crosslinks and sliplinks (entanglements) are studied using a multi-chain Brownian dynamics simulation. We coarse-grain at the level of chain segments connecting consecutive nodes (cross- or sliplinks), with particular attention to the Gaussian statistics of the network. Affine displacement of n

A. V. Zaitsev

Josephson current in SFcFS junctions with arbitrary transparency of the constriction (c) is investigated. The emphasis is done on the analysis of the supercurrent dependencies on the misorientation angle $θ$ between the in-plane magnetizations of diffusive ferromagnetic layers (F). It is found that the current-phase relation $I(ϕ)$ may be radically modified

Thomas Gilbert

We present numerical evidence supporting the validity of the Gallavotti-Cohen Fluctuation Theorem applied to the driven Lorentz gas with Nosé-Hoover thermostating. It is moreover argued that the asymptotic form of the fluctuation formula is independent of the amplitude of the driving force, in the limit where it is small.

Zsolt Gulacsi, Miklos Gulacsi

Exact static nondegenerate stripe and checkerboard ground states are obtained in a two-dimensional generalized periodic Anderson model, for a broad concentration range below quarter filling. The random droplet states, also present in the degenerate ground state, are eliminated by extending the Hamiltonian with terms of different physical origin such as dimer

N. Sunel, E. Rizaoglu, K. Harigaya, O. Ozsoy

Electronic properties, band width, band gap and van Hove singularities, of (3,0), (4,0) and (9,0) zigzag nanotubes are comparatively investigated in the Harigaya's model and a toy model including the contributions of bonds of different types to the SSH Hamiltonian differently. Optical transition frequencies are calculated. In this way an experimental cor

Yuerui Lu, Sarunya Bangsaruntip, Xinran Wang, Li Zhang

For single-walled carbon nanotube (SWNT) field effect transistors, vertical scaling of high k dielectrics by atomic layer deposition (ALD) currently stands at ~8nm with subthreshold swing S~70-90 mV/decade at room temperature. ALD on as-grown pristine SWNTs is incapable of producing a uniform and conformal dielectric layer due to the lack of functional group

Y. Kopelevich, S. Moehlecke, R. R. da Silva

We review our recent work on magnetic properties of graphite and related carbon materials. The results demonstrate that a structural disorder, topological defects, as well as adsorbed foreign atoms can be responsible for the occurrence of both ferromagnetic and superconducting patches in graphitic structures.

C. Berthod, T. Giamarchi, S. Biermann, A. Georges

We investigate the Mott transition in weakly-coupled one-dimensional (1d) fermionic chains. Using a generalization of Dynamic Mean Field Theory, we show that the Mott gap is suppressed at some critical hopping $t_{\perp}^{c2}$. The transition from the 1d insulator to a 2d metal proceeds through an intermediate phase where the Fermi surface is broken into ele

M. Keceli, M. O. Oktel

We consider a rapidly rotating two-component Bose-Einstein condensate (BEC) containing a vortex lattice. We calculate the dispersion relation for small oscillations of vortex positions (Tkachenko modes) in the mean-field quantum Hall regime, taking into account the coupling of these modes with density excitations. Using an analytic form for the density of th

David Ford

The inverse relationship between energy and time is as familiar as Planck's constant. From the point of view of a system with many states, perhaps a better representation of the system is a vector of characteristic times (one per state) for example, a canonically distributed system. In the vector case the inverse relationship persists, this time as a rel

B. Pedrini, J. L. Gavilano, S. Weyeneth, E. Felder

Na0.5CoO2 exhibits a metal-insulator transition at 53 K upon cooling. The nature of another transition at 88 K has not been fully clarified yet. We report the results of measurements of the electrical conductivity, the magnetic susceptibility and 23Na NMR on a powder sample of Na0.5CoO2, including the mapping of NMR spectra, as well as probing the spin-latti

Alexander Yu. Cherny, Joachim Brand

Correlation functions related to the dynamic density response of the one-dimensional Bose gas in the model of Lieb and Liniger are calculated. An exact Bose-Fermi mapping is used to work in a fermionic representation with a pseudopotential Hamiltonian. The Hartree-Fock and generalized random phase approximations are derived and the dynamic polarizability is

J. Hove, A. Sudbo

A short Reply to the Comment of Prokof'ev and Svistunov, cond-mat/0504008, is given.

R. L. Oldershaw

Multi-periodic pulsation phenomena of ZZ Ceti variable stars are analyzed within the context of a fractal cosmological paradigm that emphasizes discrete self-similarity in nature. A quantitative test comparing relevant stellar and atomic periods provides preliminary support for the analysis. This paper completes a 3-part series that explores the possibility

A. L. Kraus, R. J. White, L. A. Hillenbrand

We present the results of a high-resolution imaging survey of 22 brown dwarfs and very low mass stars in the nearby (~145 pc) young (~1-2 Myr) low-density star-forming region Taurus-Auriga. We obtained images with the Advanced Camera for Surveys/High Resolution Channel on HST through the F555W (V), F775W (i'), and F850LP (z') filters. This survey con

C. J. Fluke, P. D. Bourke, D. O'Donovan

Despite the large budgets spent annually on astronomical research equipment such as telescopes, instruments and supercomputers, the general trend is to analyse and view the resulting datasets using small, two-dimensional displays. We report here on alternative advanced image displays, with an emphasis on displays that we have constructed, including stereosco

D. J. Christian, M. Mathioudakis, D. S. Bloomfield, J. Dupuis

We present FUV and UV spectroscopic observations of AD Leonis, with the aim of investigating opacity effects in the transition regions of late-type stars. The C III lines in FUSE spectra show significant opacity during both the quiescent and flaring states of AD Leonis, with up to 30% of the expected flux being lost during the latter. Other FUSE emission lin

Cesar Briceno, Thomas Preibisch, William Sherry, Eric Mamajek

Low-mass stars 0.1 ~< M ~< 1 Msun) in OB associations are key to addressing some of the most fundamental problems in star formation. The low-mass stellar populations of OB associations provide a snapshot of the fossil star-formation record of giant molecular cloud complexes. Large scale surveys have identified hundreds of members of nearby OB associations, a

Drake Deming, Joseph Harrington, Sara Seager, L. Jeremy Richardson

We report detection of strong infrared thermal emission from the nearby (d=19 pc) transiting extrasolar planet HD189733b, by measuring the flux decrement during its prominent secondary eclipse. A 6-hour photometric sequence using Spitzer&#39;s infrared spectrograph in peak-up imaging mode at 16-microns shows the secondary eclipse depth to be 0.551 +/-0.030%,

Ohad Shemmer, W. N. Brandt, Donald P. Schneider, Xiaohui Fan

We present new Chandra observations of 21 z>4 quasars, including 11 sources at z>5. These observations double the number of X-ray detected quasars at z>5, allowing investigation of the X-ray spectral properties of a substantial sample of quasars at the dawn of the modern Universe. By jointly fitting the spectra of 15 z>5 radio-quiet quasars (RQQs), including

Irit Maor

I discuss the work of Maor and Lahav [1], in which the inclusion of dark energy into the spherical collapse formalism is reviewed. Adopting a phenomenological approach, I consider the consequences of - a) allowing the dark energy to cluster, and, b) including the dark energy in the virialization process. Both of these issues affect the final state of the sys

Irit Maor

The possibility that the Galactic dark matter is composed of neutralinos that are just above half the $Z^o$ mass is examined, in the context of the Galactic positron excess. In particular, we check if the anomalous bump in the cosmic ray positron to electron ratio at $10~GeV$ can be explained with the ``decay&#39;&#39; of virtual $Z^o$ bosons produced when t

Swati Gupta, Markus Boettcher, Charles D. Dermer

Jet models for the high-energy emission of Galactic X-ray binary sources have regained significant interest with detailed spectral and timing studies of the X-ray emission from microquasars, the recent detection by the HESS collaboration of very-high-energy gamma-rays from the microquasar LS~5039, and the earlier suggestion of jet models for ultraluminous X-

M. Sereno, Ph. Jetzer

Some tests of gravity theories - periastron shift, geodetic precession, change in mean motion and gravitational redshift - are applied in solar and stellar systems to constrain the cosmological constant. We thus consider a length scale range from 10^8 to 10^{15} km. Best bounds from the solar system come from perihelion advance and change in mean motion of E

Miguel A. Aloy, Luciano Rezzolla

Velocities close to the speed of light are a robust observational property of the jets observed in microquasars and AGNs, and are expected to be behind much of the phenomenology of GRBs. Yet, the mechanism boosting relativistic jets to such large Lorentz factors is still essentially unknown. Building on recent general-relativistic, multidimensional simulatio

A. Lemiere, R. Terrier, A. Djannati-Ataï

From May to July 2004, the central radian of the Galactic Plane was scanned by the H.E.S.S. (High Energy Stereoscopic System) telescopes at energies above 200 GeV. This survey was performed from -$3^o$ to +$3^o$ in latitude, for a total of 230 hours, revealing eight new VHE sources at a significance level greater than 6$σ$(standard deviations). We present a

S. Pita, W. Benbow, L. Costamante, A. Djannati-Ataï

The understanding of acceleration mechanisms in active galactic nuclei (AGN) jets and the measurement of the extragalactic-background-light (EBL) density are closely linked and require the detection of a large sample of very-high-energy (VHE) emitting extragalactic objects at varying redshifts. We report here on the discovery with the H.E.S.S. (High Energy S

E. Rasia, S. Ettori, L. Moscardini, P. Mazzotta

We examine the systematics affecting the X-ray mass estimators applied to a set of five simulated galaxy clusters. They have been processed through the X-ray Map Simulator, X-MAS, to provide Chandra-like long exposures that are analyzed to reconstruct the gas temperature, density, and mass profiles used as input. We find that at R_2500 the mass profile obtai

Jatush V. Sheth

Observations reveal that on large scales the universe is spanned by a percolating network of superclusters interspersed with large and almost empty regions -- voids. This thesis reports the construction of a sophisticated computational algorithm called SURFGEN which is used to determine the morphological and topological properties of the cosmic web. SURFGEN

Hiroaki Isobe, Durgesh Tripathi

We report observation of a large-amplitude filament oscillation followed by an eruption. This is used to probe the pre-eruption condition and the trigger mechanism of solar eruptions. We used the EUV images from the Extreme-Ultraviolet Imaging Telescope on board SOHO satellite and the H-alpha images from the Flare Monitoring Telescope at Hida Observatory. Th

Lorenzo Zaninetti

The size distributions of 2D and 3D Voronoi cells and of cells of $V_p(2,3)$,--2D cut of 3D Voronoi diagram--are explored, with the single-parameter (re-scaled) gamma distribution playing a central role in the analytical fitting. Observational evidence for a cellular universe is briefly reviewed. A simulated $V_p(2,3)$ map with galaxies lying on the cell bou

Uros Seljak, Alexey Makarov, Patrick McDonald, Hy Trac

We use the Ly-alpha forest power spectrum measured by the SDSS and high-resolution spectroscopy observations in combination with cosmic microwave background and galaxy clustering constraints to place limits on a sterile neutrino as a dark matter candidate in the warm dark matter (WDM) scenario. Such a neutrino would be created in the early universe through m

P. H. Chavanis

We complete previous investigations on the dynamical stability of barotropic stars and collisionless stellar systems. A barotropic star that minimizes the energy functional at fixed mass is a nonlinearly dynamically stable stationary solution of the Euler-Poisson system. Formally, this minimization problem is similar to a condition of ``canonical stability&#

Chris Blake, Alexandra Pope, Douglas Scott, Bahram Mobasher

Bright sub-mm galaxies are expected to arise in massive highly-biased haloes, and hence exhibit strong clustering. We argue that a valuable tool for measuring these clustering properties is the cross-correlation of sub-mm galaxies with faint optically-selected sources. We analyze populations of SCUBA-detected and optical galaxies in the GOODS-N survey area.

László Á. Gergely, Barbara Darázs

We derive the deflection angle of light rays caused by a brane black hole with mass m and tidal charge q in the weak lensing approach, up to the second order in perturbation theory. We point out when the newly derived second order contributions become important.

Padelis P. Papadopoulos

Preliminary results from a sensitive survey of the CO J=1--0, 2--1, 3--2, 4--3, 6--5, HCN J=1--0, 3--2, 4--3, and CI J=1--0 lines of a sample of 30 Ultraluminous Infrared Galaxies (ULIRGs) are presented. These reveal a tandalizing picture of the physical conditions of the molecular gas in these extraordinary galaxies ($\rm L_{FIR}>10^{12} L_{\odot}$), with a

D. Lohiya, P. Kumar

The prejudice against baryon isocurvature models is primarily because of their inconsistency with early universe light element nucleosynthesis results. We propose that incipient low metallicity (Pop II) star forming regions can be expected to have environments conducive to Deuterium production by spallation, up to levels observed in the universe.

Petr Hadrava

The use of a method of spectra disentangling for telluric lines is explained in detail, with a particular emphasis on high-precision radial-velocity measurements for the search for extrasolar planets. New improvements to the method are introduced.

R. Caimmi

Using two alternative [O/H]-[Fe/H] dependences, the empirical oxygen abundance distribution (EGD) is deduced from two different samples of old objects, available in the literature. Under the assumption that each distribution (with the addition of a third one previously known) is typical for the corresponding subsystem, the EGD of the Galactic spheroid is det

Yuichi Matsuda, Toru Yamada, Tomoki Hayashino, Ryosuke Yamauchi

We present the results of an intermediate resolution (~2 angstrom) spectroscopy of a sample of 37 candidate Lyman alpha blobs and emitters at redshift z=3.1 using the DEIMOS spectrograph on the 10 m Keck telescope. The emission lines are detected for all the 37 objects and have variety in their line profiles. The Lyman alpha velocity widths (FWHM) of the 28

P. C. W. Davies

Popular multiverse models such as the one based on the string theory landscape require an underlying set of unexplained laws containing many specific features and highly restrictive prerequisites. I explore the consequences of relaxing some of these prerequisites with a view to discovering whether any of them might be justified anthropically. Examples consid

B. Keilhauer, J. Bluemer, R. Engel, H. O. Klages

Several experiments measure the fluorescence light produced by extensive air showers in the atmosphere. This light is converted into a longitudinal shower profile from which information on the primary energy and composition is derived. The fluorescence yield, as the conversion factor between light profile measured by EAS experiments and physical interpretati

A. E. Lobanov

The possibility of radiative effects that are due to interaction of fermions with a dense matter is investigated. Neutrino-antineutrino photo-production is studied. The rate of this process is calculated in the Furry picture. It is demonstrated that this effect does not disappear even if the medium refractive index is assumed to be equal to unity. The rate o

Oktay Aydogdu

This paper has been removed by arXiv administrators because it plagiarizes gr-qc/9910015, gr-qc/0008034, and hep-th/0308070. This paper also has excessive overlap with the following papers also written by the authors or their collaborators: gr-qc/0601070 and gr-qc/0509047.

Pedro Bicudo, Stephen R. Cotanch, Felipe J. Llanes-Estrada, David G. Robertson

We analyze the f_0(1810) state recently observed by the BES collaboration via radiative J/ψdecay to a resonant ϕωspectrum and confront it with DM2 data and glueball theory. The DM2 group only measured ωωdecays and reported a pseudoscalar but no scalar resonance in this mass region. A rescattering mechanism from the open flavored KKbar decay channel is consid

G. N. Kakazei, Yu. G. Pogorelov, M. D. Costa, T. Mewes

We discuss the four-fold anisotropy of in-plane ferromagnetic resonance (FMR) field $H_r$, found in a square lattice of circular Permalloy dots when the interdot distance $a$ gets comparable to the dot diameter $d$. The minimum $H_r$, along the lattice $<11>$ axes, and the maximum, along the $<10>$ axes, differ by $\sim$ 50 Oe at $a/d$ = 1.1. This anisotropy

Frederik Witt

We investigate a new 8-dimensional Riemannian geometry defined by a generic closed and coclosed 3-form with stabiliser PSU(3), and which arises as a critical point of Hitchin&#39;s variational principle. We give a Riemannian characterisation of this structure in terms of invariant spinor-valued 1-forms, which are harmonic with respect to the twisted Dirac op

Mehdi Hassani

In this short note, we introduce an analogue of Wilson&#39;s theorem for all nonzero elements $a_1,a_2,...,a_{q-1}$ of a finite filed $\mathbb{F}$ with $|\mathbb{F}|=q\geq 3$, as follows: $$ \sum_{1\leq i_1< i_2<...< i_k\leq q-1}a_{i_1}a_{i_2}... a_{i_k}=\left\lfloor\frac{k}{q-1}\right\rfloor(-1)^q\hspace{10mm}(k=1,2,..., q-1), $$ which the left hand side of