September 2007 arXiv papers — page 25

Dennis I. Merino, Vladimir V. Sergeichuk

A strengthened form of Schur's triangularization theorem is given for quaternion matrices with real spectrum (for complex matrices it was given by Littlewood). Littlewood's algorithm for reducing a complex matrix to a canonical form under unitary similarity is extended to quaternion matrices whose eigenvalues have geometric multiplicity 1.

Maciej Niebrzydowski

It is known that the number of biquandle colorings of a long virtual knot diagram, with a fixed color of the initial arc, is a knot invariant. In this paper we describe a more subtle invariant: a family of biquandle endomorphisms obtained from the set of colorings and longitudinal information.

Genrich Belitskii, Ruvim Lipyanski, Vladimir V. Sergeichuk

We prove that the problems of classifying triples of symmetric or skew-symmetric matrices up to congruence, local commutative associative algebras with zero cube radical and square radical of dimension 3, and Lie algebras with central commutator subalgebra of dimension 3 are hopeless since each of them reduces to the problem of classifying pairs of n-by-n ma

V. Ryzhii, A. Satou, T. Otsuji, M. S. Shur

We analyze the operation of a resonant detector of terahertz (THz) radiation based on a two-dimensional electron gas (2DEG) channel with split gates. The side gates are used for the excitation of plasma oscillations by incoming THz radiation and control of the resonant plasma frequencies. The central gate provides the potential barrier separating the source

J. Adamek, M. Hebert, L. Souza

Injectivity of objects with respect to a set $\ch$ of morphisms is an important concept of algebra, model theory and homotopy theory. Here we study the logic of injectivity consequences of $\ch$, by which we understand morphisms $h$ such that injectivity with respect to $\ch$ implies injectivity with respect to $h$. We formulate three simple deduction rules

Genrich Belitskii, Vitalij M. Bondarenko, Ruvim Lipyanski, Vladimir V. Plachotnik

We prove that over an algebraically closed field of characteristic not two the problems of classifying pairs of sesquilinear forms in which the second is Hermitian, pairs of bilinear forms in which the second is symmetric (skew-symmetric), and local algebras with zero cube radical and square radical of dimension 2 are hopeless since each of them reduces to t

Vyacheslav Futorny, Vladimir V. Sergeichuk, Nadya Zharko

For each Hermitian matrix, we prove that instead of the leading principal minors some of their sums can be used in the leading principal minors criterion and in other inertia problems.

M. Hirai, S. Kumano, T. -H. Nagai, M. Oka

Fragmentation functions of pion, kaon, and nucleon are determined by global analyses of hadron-production data in $e^+e^-$ annihilation. It is particularly important that uncertainties of the fragmentation functions are estimated for the first time. We found that light-quark and gluon fragmentation functions have large uncertainties, so that one should be ca

Andrej V. Roiter, Vladimir V. Sergeichuk

By [R. Bautista, P. Gabriel, A.V Roiter., L. Salmeron, Representation-finite algebras and multiplicative basis. Invent. Math. 81 (1985) 217-285.], a finite-dimensional algebra having finitely many isoclasses of indecomposable representations admits a multiplicative basis. In Sections 4.10-4.12 of [P. Gabriel, A. V. Roiter, Representations of finite-dimension

Erasmo Recami, Flavio Fontana, Roberto Garavaglia

Some experiments, performed at Berkeley, Cologne, Florence, Vienna, Orsay, Rennes, etc., led to the claim that something seems to travel with a group velocity larger than the speed c of light in vacuum. Various other experimental results seem to point in the same direction: For instance, localized wavelet- type solutions to Maxwell equations have been found,

R. M. Dudley, Sergiy Sidenko, Zuoqin Wang, Fangyun Yang

For positive integers d, r, and M, we consider the class of rational functions on real d-dimensional space whose denominators are products of at most r functions of the form 1+Q(x) where each Q is a quadratic form with eigenvalues bounded above by M and below by 1/M. Each numerator is a monic monomial of the same degree as the corresponding denominator. Then

Sean Sather-Wagstaff

Let $R$ be a local ring and $M$ a finitely generated $R$-module. The complete intersection dimension of $M$--defined by Avramov, Gasharov and Peeva, and denoted $\cidim_R(M)$--is a homological invariant whose finiteness implies that $M$ is similar to a module over a complete intersection. It is related to the classical projective dimension and to Auslander a

Nikos Georgiou, Brendan Guilfoyle

We study 2-dimensional submanifolds of the space ${\mathbb{L}}({\mathbb{H}}^3)$ of oriented geodesics of hyperbolic 3-space, endowed with the canonical neutral Kähler structure. Such a surface is Lagrangian iff there exists a surface in ${\mathbb{H}}^3$ orthogonal to the geodesics of $Σ$. We prove that the induced metric on a Lagrangian surface in ${\mathbb{

J. L. Prieto, K. Z. Stanek, C. S. Kochanek, D. R. Weisz

In a variability survey of M81 using the Large Binocular Telescope we have discovered a peculiar eclipsing binary (MV ~ -7.1) in the field of the dwarf galaxy Holmberg IX. It has a period of 272 days and the light curve is well-fit by an overcontact model in which both stars are overflowing their Roche lobes. It is composed by two yellow supergiants (V-I ~ 1

G. W. Gibbons, C. N. Pope

The classifications of holonomy groups in Lorentzian and in Euclidean signature are quite different. A group of interest in Lorentzian signature in n dimensions is the maximal proper subgroup of the Lorentz group, SIM(n-2). Ricci-flat metrics with SIM(2) holonomy were constructed by Kerr and Goldberg, and a single four-dimensional example with a non-zero cos

Gino Isidori

The effects due to soft-photon emission (and the related virtual corrections) in multi-body decays of B, D, and K mesons are analysed. We present analytic expressions for the universal O(alpha) correction factors which can be applied to all multi-body decay modes where a tight soft-photon energy cut in the decaying-particle rest-frame is applied. All-order r

H. Mohseni Sadjadi

In the context of modified theory of gravity (f(R) gravity) we try to study the conditions required for validity of the generalized second law.

Erasmo Caponio, Miguel Angel Javaloyes

This paper has been withdrawn by the authors because it has been merged with paper arXiv:0903.3501v1 [math.DG]

Mariko Ninomiya, Syoiti Ninomiya

In this paper, authors successfully construct a new algorithm for the new higher order scheme of weak approximation of SDEs. The algorithm presented here is based on [1][2]. Although this algorithm shares some features with the algorithm presented by [3], algorithms themselves are completely different and the diversity is not trivial. They apply this new alg

Hanno Sahlmann

In a remarkable numerical analysis of the spectrum of states for a spherically symmetric black hole in loop quantum gravity, Corichi, Diaz-Polo and Fernandez-Borja found that the entropy of the black hole horizon increases in what resembles discrete steps as a function of area. In the present article we reformulate the combinatorial problem of counting horiz

A. Retzker, J. I. Cirac, M. B. Plenio, B. Reznik

We propose and study methods for detecting the Unruh effect in a Bose-Einstein condensate. The Bogoliubov vacuum of a Bose-Einstein condensate is used here to simulate a scalar field-theory, and accelerated atom dots or optical lattices as means for detecting phonon radiation due to acceleration effects. We study Unruh's effect for linear acceleration an

G. Cauzzi, K. P. Reardon, H. Uitenbroek, F. Cavallini

(Abridged) Aims: In this paper, we seek to establish the suitability of imaging spectroscopy performed in the Ca II 854.2 nm line as a means to investigate the solar chromosphere at high resolution. Methods: We utilize monochromatic images obtained with the Interferometric BIdimensional Spectrometer (IBIS) at multiple wavelengths within the Ca II 854.2 nm li

Ying-Qiu Gu

In cosmology, the cosmic curvature $K$ and the cosmological constant $Λ$ are two important parameters, and the values have strong influence on the behavior of the universe. In the context of normal cosmology, under the ordinary assumptions of positive mass-energy and initial negative pressure, we find the initial singularity of the universe is certainly abse

Abdenacer Makhlouf, Sergei Silvestrov

The aim of this paper is to generalize the concept of Lie-admissible coalgebra introduced by Goze and Remm to Hom-coalgebras and to introduce Hom-Hopf algebras with some properties. These structures are based on the Hom-algebra structures introduced by the authors.

Gesualdo Scutari, Sergio Barbarossa, Loreto Pescosolido

In this paper we propose and analyze a distributed algorithm for achieving globally optimal decisions, either estimation or detection, through a self-synchronization mechanism among linearly coupled integrators initialized with local measurements. We model the interaction among the nodes as a directed graph with weights (possibly) dependent on the radio chan

Roger A. Horn, Vladimir V. Sergeichuk

Canonical matrices are given for (a) bilinear forms over an algebraically closed or real closed field; (b) sesquilinear forms over an algebraically closed field and over real quaternions with any nonidentity involution; and (c) sesquilinear forms over a field F of characteristic different from 2 with involution (possibly, the identity) up to classification o

De Tao Mao, Yisheng Zhong

To describe and analyze the dynamics of Self-Organized Criticality (SOC) systems, a four-state continuous-time Markov model is proposed in this paper. Different to computer simulation or numeric experimental approaches commonly employed for explaining the power law in SOC, in this paper, based on this Markov model, using E.T.Jayness' Maximum Entropy meth

Ivo Souza, David Vanderbilt

We consider the magnetic circular dichroism spectrum of a crystal with broken time-reversal symmetry in the electric-dipole approximation. Using the Kubo-Greenwood formula for the absorptive part of the antisymmetric optical conductivity, its frequency integral is recast as a ground-state property. We show that in insulators this quantity is proportional to

Bao-quan Ai, Liang-gang Liu

Based on recent work [L. Machura, M. Kostur, P. Talkner, J. Luczka, and P. Hanggi, Phys. Rev. Lett. 98, 040601 (2007)], we extend the study of inertial Brownian motors to the case of an asymmetric potential. It is found that some transport phenomena appear in the presence of an asymmetric potential. Within tailored parameter regimes, there exists two optimal

Kazuya Koyama

The self-accelerating universe realizes the accelerated expansion of the universe at late times by large-distance modification of general relativity without a cosmological constant. The Dvali-Gabadadze-Porrati (DGP) braneworld model provides an explicit example of the self-accelerating universe. Recently, the DGP model becomes very popular to study the obser

Irena Tzekina, Karan Danthi, Daniel N. Rockmore

In this note we study the bilateral merchandise trade flows between 186 countries over the 1948-2005 period using data from the International Monetary Fund. We use Pajek to identify network structure and behavior across thresholds and over time. In particular, we focus on the evolution of trade "islands" in the a world trade network in which countrie

M. Sharif, Umber Sheikh

We investigate the wave properties of the Kerr black hole with isothermal plasma using 3+1 ADM formalism. The corresponding Fourier analyzed perturbed GRMHD equations are used to obtain the dispersion relations. These relations lead to the real values of the components of wave vector $\textbf{k}$ which are used to evaluate the quantities like phase and group

Fabian Heitsch, Lee Hartmann, Adrianne D. Slyz, Julien E. G. Devriendt

We study numerically the formation of molecular clouds in large-scale colliding flows including self-gravity. The models emphasize the competition between the effects of gravity on global and local scales in an isolated cloud. Global gravity builds up large-scale filaments, while local gravity -- triggered by a combination of strong thermal and dynamical ins

B. Commercon, P. Hennebelle, E. Audit, G. Chabrier

The development of parallel supercomputers allows today the detailed study of the collapse and the fragmentation of prestellar cores with increasingly accurate numerical simulations. Thanks to the advances in sub-millimeter observations, a wide range of observed initial conditions enable us to study the different modes of low-mass star formation. The challen

Quentin G. Bailey

In this talk, results from the gravitational sector of the Standard-Model Extension (SME) are discussed. The weak-field phenomenology of the resulting modified gravitational field equations is explored. The application of the results to a variety of modern gravity experiments, including lunar laser ranging, Gravity Probe B, binary pulsars, and Earth-laborato

Fangwen Fu, Mihaela van der Schaar

In this paper, we model the various wireless users in a cognitive radio network as a collection of selfish, autonomous agents that strategically interact in order to acquire the dynamically available spectrum opportunities. Our main focus is on developing solutions for wireless users to successfully compete with each other for the limited and time-varying sp

Yi Su, Mihaela van der Schaar

In this paper, we consider the problem of resource allocation among two competing users sharing a binary symmetric broadcast channel. We model the interaction between autonomous selfish users in the resource allocation and analyze their strategic behavior in manipulating the allocation outcome. We analytically show that users will improve their performance (

Vladimir V. Sergeichuk

A unitary (Euclidean) representation of a quiver is given by assigning to each vertex a unitary (Euclidean) vector space and to each arrow a linear mapping of the corresponding vector spaces. We recall an algorithm for reducing the matrices of a unitary representation to canonical form, give a certain description of the representations in canonical form, and

Gheorghe Ivan, Mihai Ivan, Dumitru Opris

The theory of derivative of noninteger order goes back to Leibniz, Liouville and Riemann. Derivatives of fractional order have found many applications in recent studies in mechanics, physics, economics. In this paper we define the fractional tangent bundle on a manifold, using a method of Radu Miron. The fractional Leibniz algebroids are investigated. The as

Gino Isidori

A concise overview of the interesting recent developments in kaon phyiscs discussed at KAON 2007 is presented.

Denis I. Saveliev

We discuss how singular can cardinals be in absence of the axiom of choice. We show that, contrasting with known negative consistency results (of Gitik and others), certain positive results are provable. Then we pose some problems.

Shay Fuchs

It is well known that spinors on oriented Riemannian manifolds cannot be defined as sections of a vector bundle associated with the frame bundle. For this reason spin and spin^c structures are often introduced. In this paper we prove that spin^c structures have a universal property among all other structures that enable the construction of spinor bundles. We

Pasquale Temi, Fabrizio Brighenti, William G. Mathews

We describe photometry at mid-infrared passbands (1.2 - 24 microns) for a sample of 18 elliptical galaxies. All surface brightness distributions resemble de Vaucouleurs profiles, indicating that most of the emission arises from the photospheres or circumstellar regions of red giant stars. The spectral energy distribution peaks near 1.6 microns, but the half-

Antonio Sciarretta

In this paper, I propose a realistic interpretation (RI) of quantum mechanics, that is, an interpretation according to which a particle follows a definite path in spacetime. The path is not deterministic but it is rather a random walk. However, the probability of each step of the walk is found to depend from some average properties of the particle that can b

K. Schiessl, K. L. Ishikawa, E. Persson, J. Burgdörfer

We investigate the dependence of the intensity of radiation due to high-harmonic generation (HHG) as a function of the wavelength of the fundamental driver field. Superimposed on a smooth power-law dependence observed previously we find surprisingly strong and rapid fluctuations on a fine wavelength scale. We identify the origin of these fluctuations in term

Filippo Petroni, Giulia Rotundo

Statistical analysis of financial data most focused on testing the validity of Brownian motion (Bm). Analysis performed on several time series have shown deviation from the Bm hypothesis, that is at the base of the evaluation of many financial derivatives. We inquiry in the behavior of measures of performance based on maximum drawdown movements (MDD), testin

Maria Sotiropoulou, Frederic Bossard, Eric Balnois, Julian Oberdisse

The formation of soluble hydrogen-bonding interpolymer complexes between poly(acrylic acid) (PAA) and poly(acrylic acid-co-2-acrylamido-2-methyl-1-propane sulfonic acid)-graft-poly(N, N dimethylacrylamide) (P(AA-co-AMPSA)-g-PDMAM) at pH = 2.0 was studied. A viscometric study showed that in semidilute solution a physical gel is formed, due to the interconnect

W. Gieren, G. Pietrzynski, I. Soszynski, F. Bresolin

We have obtained deep images in the near-infrared J and K filters of four fields in the Sculptor Group spiral galaxy NGC 55 with the ESO VLT and ISAAC camera. For 40 long-period Cepheid variables in these fields which were recently discovered by Pietrzy{ń}ski et al., we have determined mean J and K magnitudes from observations at two epochs, and derived dist

S. Cebrat, D. Stauffer

In simulations of sexual reproduction with diploid individuals, we introduce that female haploid gametes recognize one specific allele of the genomes as a marker of the male haploid gametes. They fuse to zygotes preferrably with male gametes having a different marker than their own. This gamete recognition enhances the advantage of complementary bit-strings

Pavel V. Avramov, Alexander A. Kuzubov, Alexander S. Fedorov, Pavel B. Sorokin

The atomic and electronic structure of a set of proposed thin (1.6 nm in diameter) silicon/silica quantum nanodots and nanowires with narrow interface, as well as parent metastable silicon structures (1.2 nm in diameter), was studied in cluster and PBC approaches using B3LYP/6-31G* and PW PP LDA approximations. The total density of states (TDOS) of the small

Gabjin Oh, Seunghwan Kim, Cheoljun Eom, Taehyuk Kim

We propose a novel method to quantify the clustering behavior in a complex time series and apply it to a high-frequency data of the financial markets. We find that regardless of used data sets, all data exhibits the volatility clustering properties, whereas those which filtered the volatility clustering effect by using the GARCH model reduce volatility clust

V. M. Red'kov, N. G. Tokarevskaya, E. M. Bychkouskaya, George J. Spix

The known possibility to consider the (vacuum) Maxwell equations in a curved space-time as Maxwell equations in flat space-time(Mandel'stam L.I., Tamm I.E.) taken in an effective media the properties of which are determined by metrical structure of the curved model is studied. Metrical structure of the curved space-time generates effective constitutive e

N. Schartel, P. M. Rodriguez-Pascual, M. Santos-Lleo, L. Ballo

We analyse a 75ks XMM-Newton observation of PG 2112+059 performed in November 2005 and compare it with a 15ks XMM-Newton observation taken in May 2003. PG 2112+059 was found in a deep minimum state as its 0.2-12 keV flux decreased by a factor of 10 in comparison to the May 2003 observation. During the deep minimum state the spectra show strong emission in ex

Mihail V. Chizhov

Direct constraints on the masses of new heavy bosons by the Tevatron data are discussed. Some excesses in the experimental data are interpreted as a resonance production of new charged and `leptophobic' neutral chiral bosons with masses around 500 GeV and 700 GeV, respectively. The interpretation was provided on the basis of the theoretical model, propos

Kazuhiro Hikami

We study topological properties of quasi-particle states in the non-Abelian quantum Hall states. We apply a skein-theoretic method to the Read--Rezayi state whose effective theory is the SU(2)_K Chern--Simons theory. As a generalization of the Pfaffian (K=2) and the Fibonacci (K=3) anyon states, we compute the braiding matrices of quasi-particle states with

M. Chauvet, G. Fu, G. Salamo

A method to probe the guiding characteristics of waveguides formed in real-time is proposed and evaluated. It is based on the analysis of the time dependent light distribution observed at the exit face of the waveguide while progressively altering its index profile and probed by a large diameter optical beam. A beam propagation method is used to model the ob

Joel Gomez, Andrew Niles, J. Maurice Rojas

Consider real bivariate polynomials f and g, respectively having 3 and m monomial terms. We prove that for all m>=3, there are systems of the form (f,g) having exactly 2m-1 roots in the positive quadrant. Even examples with m=4 having 7 positive roots were unknown before this paper, so we detail an explicit example of this form. We also present an O(n^{11})

Bao-quan Ai, Liang-gang Liu

Transport of a Brownian particle moving along the axis of a three-dimensional asymmetric periodic tube is investigated in the presence of asymmetric unbiased forces. The reduction of the coordinates may involve not only the appearance of entropic barrier but also the effective diffusion coefficient. It is found that in the presence of entropic barrier, the a

Timothy Baldwin

We propose a range of deep lexical acquisition methods which make use of morphological, syntactic and ontological language resources to model word similarity and bootstrap from a seed lexicon. The different methods are deployed in learning lexical items for a precision grammar, and shown to each have strengths and weaknesses over different word classes. A pa

Jean-Philippe Lenain

M87 is the first extragalactic source detected at the TeV that is not a blazar. To account for the recent observations of M87 made by the High Energy Stereoscopic System (H.E.S.S.) telescope array, we developed a new multi-blob synchrotron self-Compton model. In the framework of this model, we present here the predictions for the very high energy emission of

Jean-Philippe Lenain

M87 is the first extragalactic source detected in the TeV range that is not a blazar. The large scale jet of M87 is not aligned with the line of sight. Modification of standard emission models of TeV blazars appears necessary to account for the gamma-ray observations made by H.E.S.S. despite this misalignment. We present a new multi-blob synchrotron self-Com

Tao Ma

We use the iterative unitary matrix multiply method to calculate the long time behavior of the resonant quantum kicked rotator with a large denominator. The delocalization time is exponentially large. The quantum wave delocalizes through degenerate states. At last we construct a nonresonant quantum kicked rotator with delocalization.

Jui-yu Chiu, Frank Golf, Randall Kelley, Aneesh V. Manohar

Electroweak Sudakov corrections of the form alpha^n log^m s/M_{W,Z}^2 are summed using renormalization group evolution in soft-collinear effective theory (SCET). Results are given for the scalar, vector and tensor form-factors for fermion and scalar particles. The formalism for including massive gauge bosons in SCET is developed.

Ayman A. El-Okaby

In this paper, we study the correlation between the exceptional lie groups and El-Naschie's transfinite E-infinity spacetime theory. Subsequently this is used to calculate the number of elementary particles in the standard model, mass of the Higgs boson and some coupling constants.

H. J. Krenner, C. Pryor, J. He, J. P. Zhang

We demonstrate a method to grow height controlled, dislocation-free InGaAs quantum posts (QPs) on GaAs by molecular beam epitaxy (MBE) which is confirmed by structural investigations. The optical properties are compared to realistic 8-band k.p calculations of the electronic structure which fully account for strain and the structural properties of the QP. Usi

Ron Peled

Intuitively, two metric spaces are rough isometric (or quasi-isometric) if their large-scale metric structure is the same, ignoring fine details. This concept has proven fundamental in the geometric study of groups. Abért, and later Szegedy and Benjamini, have posed several probabilistic questions concerning this concept. In this article, we consider one of

Danny Birmingham, Susan Mokhtari

We explore the classical stability of topological black holes in d-dimensional anti-de Sitter spacetime, where the horizon is an Einstein manifold of negative curvature. According to the gauge invariant formalism of Ishibashi and Kodama, gravitational perturbations are classified as being of scalar, vector, or tensor type, depending on their transformation p

A. Mering, M. Fleischhauer

We study the phase diagram of the zero-temperature, one-dimensional Bose-Fermi-Hubbard model for fixed fermion density in the limit of small fermionic hopping. This model can be regarded as an instance of a disordered Bose-Hubbard model with dichotomic values of the stochastic variables. Phase boundaries between compressible, incompressible (Mott-insulating)

S. Das, X. Zong, A. Niazi, A. Ellern

Magnetically pure spinel compound ${\rm LiV_2O_4}$ is a rare $d$-electron heavy fermion. Measurements on single crystals are needed to clarify the mechanism for the heavy fermion behavior in the pure material. In addition, it is known that small concentrations ($< 1$ mol%) of magnetic defects in the structure strongly affect the properties, and measurements

J. Holder, A. Falcone, D. Morris

The TeV emitting high-mass X-ray binary system LSI+61303 was observed with the Swift satellite from early September 2006 to early January 2007. Many of these observations were contemporaneous with TeV observations. The data consist of observations on 24 separate days with durations ranging between 700s and 4700s, and partially cover 4.5 orbital periods of th

Christian Beck, Clovis Jacinto de Matos

We revisit the cosmological constant problem using the viewpoint that the observed value of dark energy density in the universe actually represents a rather natural value arising as the geometric mean of two vacuum energy densities, one being extremely large and the other one being extremely small. The corresponding mean energy scale is the Planck-Einstein s

X. Zong, B. J. Suh, A. Niazi, J. Q. Yan

$^{51}$V NMR studies on CaV2O4 single crystals and $^{17}$O NMR studies on $^{17}$O-enriched powder samples are reported. The temperature dependences of the $^{17}$O NMR line width and nuclear spin-lattice relaxation rate give strong evidence for a long-range antiferromagnetic transition at Tn = 78 K in the powder. Magnetic susceptibility measurements show t

Bogdan A. Dobrescu, Kyoungchul Kong, Rakhi Mahbubani

We analyze collider signatures of massive color-octet bosons whose couplings to quarks are suppressed. Gauge invariance forces the octets to couple at tree level only in pairs to gluons, with a strength set by the QCD gauge coupling. For a spin-1 octet, the cross section for pair production at hadron colliders is larger than that for a quark of equal mass. T

D. M. Gangardt, M. Pustilnik

We consider a longitudinal expansion of a one-dimensional gas of hard-core bosons suddenly released from a trap. We show that the broken translational invariance in the initial state of the system is encoded in correlations between the bosonic occupation numbers in the momentum space. The correlations are protected by the integrability and exhibit no relaxat

Michel Zamboni-Rached, Erasmo Recami

In this work it is shown how to obtain, in a simple way, localized (non- diffractive) subluminal pulses as exact analytic solutions to the wave equations. These new ideal subluminal solutions, which propagate without distortion in any homogeneous linear media, are herein obtained for arbitrarily chosen frequencies and bandwidths, avoiding in particular any r

Alexey Boyarsky, Dmytro Iakubovskyi, Oleg Ruchayskiy, Vladimir Savchenko

We derive constraints on parameters of the radiatively decaying Dark Matter (DM) particles, using XMM-Newton EPIC spectra of the Andromeda galaxy (M31). Using the observations of the outer (5&#39;-13&#39;) parts of M31 we improve the existing constraints. For the case of sterile neutrino DM, combining our constraints with the latest computation of abundances

Helge Glockner

This note is devoted to the theory of projective limits of finite-dimensional Lie groups, as developed in the recent monograph ``The Lie Theory of Connected Pro-Lie Groups&#39;&#39; by K.H. Hofmann and S.A. Morris. We replace the original, highly non-trivial proof of the One-Parameter Subgroup Lifting Lemma given in the monograph by a shorter and more elemen

J. M. Drummond, J. Henn, G. P. Korchemsky, E. Sokatchev

There is growing evidence that on-shell gluon scattering amplitudes in planar N=4 SYM theory are equivalent to Wilson loops evaluated over contours consisting of straight, light-like segments defined by the momenta of the external gluons. This equivalence was first suggested at strong coupling using the AdS/CFT correspondence and has since been verified at w

Alexandre Eremenko

Fabry&#39;s theorem on the singularities of power series is improved: the maximum density in the assumptions of this theorem is replaced by an interior density of Beurling--Malliavin type.

W. Kluzniak, S. Rappaport

We compute the properties of a geometrically thin, steady accretion disk surrounding a central rotating, magnetized star. The magnetosphere is assumed to entrain the disk over a wide range of radii. The model is simplified in that we adopt two (alternate) ad hoc, but plausible, expressions for the azimuthal component of the magnetic field as a function of ra

Ana Alboteanu, Thorsten Ohl, Reinhold Rückl

We study phenomenological consequences of a noncommutative extension of the standard model in the theta-expanded approach at the ILC. We estimate the sensitivity of the ILC for the noncommutative scale Lambda_NC. Comparing with earlier estimates for the LHC, we demonstrate the complementarity of the experiments at the two colliders.

Giuseppe D&#39;Appollonio, Thomas Quella

In this paper we study the abelian cosets of the H(4) WZW model. They coincide or are related to several interesting three-dimensional backgrounds such as the Melvin model, the conical point-particle space-times and the null orbifold. We perform a detailed CFT analysis of all the models and compute the coset characters as well as some typical three-point cou

Jonathan T. Barron, Christopher Stumm, David W. Hogg, Dustin Lang

The USNO-B Catalog contains spurious entries that are caused by diffraction spikes and circular reflection halos around bright stars in the original imaging data. These spurious entries appear in the Catalog as if they were real stars; they are confusing for some scientific tasks. The spurious entries can be identified by simple computer vision techniques be

Stephen Semmes

Although Clifford analysis is like complex analysis in many ways, there are obvious differences related to noncommutativity, and a few aspects of this are considered here.

R. Mark Crockett, Justyn R. Maund, Stephen J. Smartt, Seppo Mattila

We report our attempts to locate the progenitor of the peculiar type Ic SN 2007gr in HST pre-explosion images of the host galaxy, NGC 1058. Aligning adaptive optics Altair/NIRI imaging of SN 2007gr from the Gemini (North) Telescope with the pre-explosion HST WFPC2 images, we identify the SN position on the HST frames with an accuracy of 20 mas. Although noth

Gerald W. Schwarz

Let $G\subset\GL(V)$ be a complex reductive group where $\dim V<\infty$, and let $π\colon V\to\quot VG$ be the categorical quotient. Let $\NN:=π\invπ(0)$ be the null cone of $V$, let $H_0$ be the subgroup of $\GL(V)$ which preserves the ideal $\I$ of $\NN$ and let $H$ be a Levi subgroup of $H_0$ containing $G$. We determine the identity component of $H$. In

Jesse Gilbert

We show the Graceful Tree Conjecture holds.

John McDonald

We study the cosmological constraints on unparticle interactions and the temperature of the Universe for the case where unparticle states can be modelled as continuous mass particles with lifetime > 1s. By considering thermal background quark decay to continuous mass scalars via a scalar operator of dimension d_{U}, we show that the condition that the Univer

Pablo de la Mora, O. Navarro

The superconductor UCoGe is analyzed with electronic structure calculations using Linearized Augmented Plane Wave method based on Density Functional Theory. Ferromagnetic and antiferromagnetic calculations with and without correlations (via LDA+U) were done. In this compound the Fermi level is situated in a region where the main contribution to DOS comes fro

Vladislav Kravchenko, Dominic Rochon, Sebastien Tremblay

Elliptic pseudoanalytic function theory was considered independently by Bers and Vekua decades ago. In this paper we develop a hyperbolic analogue of pseudoanalytic function theory using the algebra of hyperbolic numbers. We consider the Klein-Gordon equation with a potential. With the aid of one particular solution we factorize the Klein-Gordon operator in

James Bedford, Constantinos Papageorgakis, Konstantinos Zoubos

Twistor string theory is known to describe a wide variety of field theories at tree-level and has proved extremely useful in making substantial progress in perturbative gauge theory. We explore the twistor dual description of a class of N=2 UV-finite super-Yang-Mills theories with fundamental flavour by adding &#39;flavour&#39; branes to the topological B-mo

Pilar Albert, Elvira Mayordomo, Philippe Moser, Sylvain Perifel

The pressing need for eficient compression schemes for XML documents has recently been focused on stack computation [6, 9], and in particular calls for a formulation of information-lossless stack or pushdown compressors that allows a formal analysis of their performance and a more ambitious use of the stack in XML compression, where so far it is mainly conne

C. P. Hughes, Matthew P. Young

We compute the asymptotics of the fourth moment of the Riemann zeta function times an arbitrary Dirichlet polynomial of length $T^{{1/11} - ε}$

Moumita Das, Alex J. Levine, F. C. MacKintosh

Motivated by recent experiments showing the buckling of microtubules in cells, we study theoretically the mechanical response of, and force propagation along elastic filaments embedded in a non-linear elastic medium. We find that, although embedded microtubules still buckle when their compressive load exceeds the critical value $f_c$ found earlier, the resul

Krishnan Shankar, Christina Sormani

In this paper we extend the concept of a conjugate point in a Riemannian manifold to complete length spaces (also known as geodesic spaces). In particular, we introduce symmetric conjugate points and ultimate conjugate points. We then generalize the long homotopy lemma of Klingenberg to this setting as well as the injectivity radius estimate also due to Klin

D. Gamermann, L. R. Dai, E. Oset

We present the formalism for the decay of dynamically generated scalar mesons with open- or hidden-charm and give results for the decay of D^*_{s0} (2317) to γD_s^* plus that of a hidden charm scalar meson state predicted by the theory around 3700 MeV decaying into γJ/ψ.

D. L. Shepelyansky

The properties of the resonant Gamow states are studied numerically in the semiclassical limit for the quantum Chirikov standard map with absorption. It is shown that the number of such states is described by the fractal Weyl law and their Husimi distributions closely follow the strange repeller set formed by classical orbits nonescaping in future times. For

Andrea Gabrielli, Fabio Cecconi

From the exact single step evolution equation of the two-point correlation function of a particle distribution subjected to a stochastic displacement field $\bu(\bx)$, we derive different dynamical regimes when $\bu(\bx)$ is iterated to build a velocity field. First we show that spatially uncorrelated fields $\bu(\bx)$ lead to both standard and anomalous dif

Tongjiang Wang, Linhui Sui, Jiong Qiu

Spectroscopic observations of a solar limb flare recorded by SUMER on SOHO reveal, for the first time, hot fast magnetic reconnection outflows in the corona. As the reconnection site rises across the SUMER spectrometer slit, significant blue- and red-shift signatures are observed in sequence in the Fe XIX line, reflecting upflows and downflows of hot plasma

Alexander S. Mishchenko, Nicolae Teleman

The Fredholm representation theory is well adapted to construction of homotopy invariants of non simply connected manifolds on the base of generalized Hirzebruch formula. Earlier a natural family of the Fredholm representations was constructed that lead to a symmetric vector bundle on completion of the fundamental group with a modification of the Higson-Roe