June 2006 arXiv papers — page 3

R. S. Thorne

I discuss the current status of parton distributions. I outline the wide variety of different parton distributions available, and highlight which are either necessary or suitable for use at present.

Mehdi Hassani

In this note, first we refine Mandl's inequality. Then, we consider the product $p_1p_2... p_n$ and we refine some known lower bounds for it, and we find some upper bounds for it by using Mandl's inequality and its refinement and the AGM-Inequality.

Sean Gavin, Mohamed Abdel-Aziz

Elliptic flow measurements at RHIC suggest that quark gluon plasma flows with very little viscosity compared to weak coupling expectations, challenging theorists to explain why this fluid is so nearly ``perfect''. It is therefore vital to find quantitative experimental information on the viscosity of the plasma. We propose that measurements of transv

Sebastian de Haro, Anastasios C. Petkou

We study a subsector of the AdS_4/CFT_3 correspondence where a class of solutions in the bulk and on the boundary can be explicitly compared. The bulk gravitational theory contains a conformally coupled scalar field with a Phi^4 potential, and is holographically related to a massless scalar with a Phi^6 interaction in three dimensions. We consider the scalar

Kaustubh Agashe, Gilad Perez, Amarjit Soni

We study top quark flavor violation in the framework of a warped extra dimension with the Standard Model (SM) fields propagating in the bulk. Such a scenario provides solutions to both the Planck-weak hierarchy problem and the flavor puzzle of the SM without inducing a flavor problem. We find that, generically, tcZ couplings receive a huge enhancement, in pa

M. Dasgupta

We consider the impact of the kt algorithm on energy flow into gaps between jets in any QCD hard process. While we confirm the observation that the kt clustering procedure considerably reduces the impact of non-global logarithms, we unearth yet new sources of logarithmic enhancement, that stem from using the $k_t$ algorithm to define the final state. We comm

Christian Wolf, Philipp Podsiadlowski

We investigate the difference between the host galaxy properties of core-collapse supernovae and long-duration gamma-ray bursts (LGRBs), and quantify a possible metallicity dependence of the efficiency of producing LGRBs. We use a sample of 16 CC SNe and 16 LGRBs from Fruchter et al. (2006) which have similar redshift distributions to eliminate galaxy evolut

Zhengyu Mao, Fernando Rodriguez-Villegas, Gonzalo Tornaría

Let f be a newform of weight two, prime level p. If D is a fundamental discriminant, define the twisted L-function L(f,D,s) to be the L-function associated to the twist of f by the quadratic character of conductor D. In this paper we consider the question of computing the family of twisted central values {L(f,D,1) : |D| <= x} for some x, by using an explicit

José Antônio Gonçalves Miranda

We study the topological entropy of the magnetic flow on a closed riemannian surface. We prove that if the magnetic flow has a non-hyperbolic closed orbit in some energy set T^cM= E^{-1}(c), then there exists an exact $ C^\infty$-perturbation of the 2-form $ Ω$ such that the new magnetic flow has positive topological entropy in T^cM. We also prove that if th

Maciej Lewenstein, Anna Sanpera, Veronica Ahufinger, Bogdan Damski

We review recent developments in the physics of ultracold atomic and molecular gases in optical lattices. Such systems are nearly perfect realisations of various kinds of Hubbard models, and as such may very well serve to mimic condensed matter phenomena. We show how these systems may be employed as quantum simulators to answer some challenging open question

Alexander Fel&#39;shtyn, Evgenij Troitsky

We study the notion of twisted conjugacy separability (essentially introduced in our previous paper for a proof of twisted version of Burnside-Frobenius theorem) and some related properties. We give examples of groups with and without this property and study its behavior under some extensions. An affirmative answer to the twisted Dehn conjugacy problem for p

Quentin Duret, Bruno Machet

Defining, in the framework of quantum field theory, their mass eigenstates through their matricial propagator, we show why the mixing matrices of non-degenerate coupled systems should not be parametrized as unitary. This is how, for leptonic binary systems, two-angles solutions with discrete values pi/4 [pi/2] and pi/2 [pi] (in addition to the trivial case 0

G. Stasinska, R. Cid Fernandes, A. Mateus, L. Sodre

We consider the techniques to distinguish normal star forming (NSF) galaxies and active galactic nuclei (AGN) hosts using optical spectra. The observational data base is a set of 20000 galaxies extracted from the Sloan Digital Sky Survey, for which we have determined the emission line intensities after subtracting the stellar continuum obtained from spectral

A. G. Ramm

Scattering problem by several bodies, small in comparison with the wavelength, is reduced to linear algebraic systems of equations, in contrast to the usual reduction to some integral equations.

Pei-Hong Gu, He Zhang, Shun Zhou

We propose a minimal type II seesaw model by introducing only one right-handed neutrino besides the $SU(2)_{L}$ triplet Higgs to the standard model. In the usual type II seesaw models with several right-handed neutrinos, the contributions of the right-handed neutrinos and the triplet Higgs to the CP asymmetry, which stems from the decay of the lightest right

Kurt Johansson, Eric Nordenstam

Consider an infinite random matrix $H=(h_{ij})_{0<i,j}$ picked from the Gaussian Unitary Ensemble (GUE). Denote its main minors by $H_i=(h_{rs})_{1\leq r,s\leq i}$ and let the $j$:th largest eigenvalue of $H_i$ be $μ^i_j$. We show that the configuration of all these eigenvalues $(i,μ_j^i)$ form a determinantal point process on $\mathbb{N}\times\mathbb{R}$. F

Adriano Tomassini, Luigi Vezzoni

An \emph{$ω$-admissible almost complex structure} on a $2n$-dimensional symplectic manifold $(M,ω)$ is a $ω$-calibrated almost complex structure $J$ admitting a nowhere vanishing $\bar{\partial}_J$-closed $(n,0)$-form $ψ$. After giving some examples we consider the moduli space of admissible almost complex structures and we study infinitesimal deformations.

Derek A. Stewart

In recent years, palladium has proven to be a crucial component for devices ranging from nanotube field effect transistors to advanced hydrogen storage devices. In this work, I examine the phonon dispersion of fcc Pd using first principle calculations based on density functional perturbation theory. While several groups in the past have studied the acoustic

Mariano Cadoni

In absence of matter Einstein gravity with a cosmological constant $\La$ can be formulated as a scale-free theory depending only on the dimensionless coupling constant G Λwhere G is Newton constant. We derive the conformal field theory (CFT) and its improved stress-energy tensor that describe the dynamics of conformally flat perturbations of the metric. The

Manuel A. Ballester, Stephanie Wehner

We prove tight entropic uncertainty relations for a large number of mutually unbiased measurements. In particular, we show that a bound derived from the result by Maassen and Uffink for 2 such measurements can in fact be tight for up to sqrt{d} measurements in mutually unbiased bases. We then show that using more mutually unbiased bases does not always lead

Lara Sidoli, Alberto Pellizzoni, Stefano Vercellone, Michele Moroni

We report the results of XMM-Newton and BeppoSAX observations of the radio and X-ray emitting star LS I +61 303, likely associated with the gamma-ray source 2CG 135+01 and recently detected also at TeV energies. The data include a long XMM-Newton pointing carried out in January 2005, which provides the deepest look ever obtained for this object in the 0.3-12

P. Bialas, L. Daniel, A. Morel, B. Petersson

In this article we will discuss numerical results on screening masses and thermodynamic quantities in 2 + 1 dimensional SU(3) gauge theory. We will also compare them to perturbation theory and the dimensionally reduced model.

Semyon Alesker

The goal of this article is to present a survey of the recent theory of plurisubharmonic functions of quaternionic variables, and its applications to theory of valuations on convex sets and HKT-geometry (HyperKähler with Torsion). The exposition follows the articles math.CV/0104209, math.CV/0208005, math.MG/0401219 by the author and math.CV/0510140 by M. Ver

Giampiero Esposito, Roberto Pettorino, Paolo Scudellaro

The problem of deriving a shock-wave geometry with cosmological constant by boosting a Schwarzschild-de Sitter (or anti-de Sitter) black hole is re-examined. Unlike previous work in the literature, we deal with the exact Schwarzschild-de Sitter (or anti-de Sitter) metric. By virtue of peculiar cancellations in this exact calculation, where the metric does no

Peter Buergisser

We determine the expected curvature polynomial of random real projective varieties given as the zero set of independent random polynomials with Gaussian distribution, whose distribution is invariant under the action of the orthogonal group. In particular, the expected Euler characteristic of such random real projective varieties is found. This considerably e

David M. J. Calderbank

I present a construction of real or complex selfdual conformal 4-manifolds (of signature (2,2) in the real case) from a natural gauge field equation on a real or complex projective surface, the gauge group being the group of diffeomorphisms of a real or complex 2-manifold. The 4-manifolds obtained are characterized by the existence of a foliation by selfdual

Péter Süle

Anomalous inter-layer atomic transport of deposited impurity atoms on Al(111) has been found by constant temperature molecular dynamics simulations. The low-energy deposition of Pt on Al(111) leads to oscillatory adsorbate-substrate interaction and to a low-temperature ballistic injection of the deposited particles to below the topmost layer. The ultrafast i

John Erik Fornaess, Nessim Sibony

Let F be a holomorphic foliation of P^2 by Riemann surfaces. Assume all the singular points of F are hyperbolic. If F has no algebraic leaf, then there is a unique positive harmonic $(1,1)$ current $T$ of mass one, directed by F. This implies strong ergodic properties for the foliation. We also study the harmonic flow associated to the current $T.$

Ciprian Tudor, Yimin Xiao

Let $B^{H, K}= \big\{B^{H, K}(t), t \in \R_+ \big\}$ be a bifractional Brownian motion in $\R^d$. We prove that $B^{H, K}$ is strongly locally nondeterministic. Applying this property and a stochastic integral representation of $B^{H, K}$, we establish Chung&#39;s law of the iterated logarithm for $B^{H, K}$, as well as sharp Hölder conditions and tail proba

Robert Alicki

We compare two physical systems: polarization degrees of freedom of a macroscopic light beam and the Josephson junction (JJ) in the &#34;charge qubit regime&#34;. The first system obviously cannot carry genuine quantum information and we show that the maximal entanglement which could be encoded into polarization of two light beams scales like 1/(photon numbe

Stephan J. Huber, Thomas Konstandin, Tomislav Prokopec, Michael G. Schmidt

We analyze the nMSSM with CP violation in the singlet sector. We study the static and dynamical properties of the electroweak phase transition. We conclude that electroweak baryogenesis in this model is generic in the sense that if the present limits on the mass spectrum are applied, no severe additional tuning is required to obtain a strong first-order phas

Lin Hu, Xueliang Li

This paper has been withdrawn by the author(s), due an error in the proof.

Heidrun Weber, Matthias Vojta

Motivated by impurity-induced magnetic ordering phenomena in spin-gap materials like TlCuCl3, we develop a mean-field theory for strongly disordered antiferromagnets, designed to capture the broad distribution of coupling constants in the effective model for the impurity degrees of freedom. Based on our results, we argue that in the presence of random magnet

Jun Goryo, Mahito Kohmoto

We study quantum processes with two or more adiabatic parameters. When the parameters are compactified, a derivative of the Hamiltonian gives a first Chern number, hence an integer. This topological formulation is applied to the AC Josephson effect and the spin Hall effect in semiconductors.

M. Zaccanti, C. D&#39;Errico, F. Ferlaino, G. Roati

We control the interspecies interaction in a two-species atomic quantum mixture by tuning the magnetic field at a Feshbach resonance. The mixture is composed by fermionic 40K and bosonic 87Rb. We observe effects of the large attractive and repulsive interaction energy across the resonance, such as collapse or a reduced spatial overlap of the mixture, and we

C. Benesch, M. Thoss, W. Domcke, M. Cizek

The influence of vibrational motion on electron conduction through single molecules bound to metal electrodes is investigated employing first-principles electronic-structure calculations and projection-operator Green&#39;s function methods. Considering molecular junctions where a central phenyl ring is coupled via (alkane)thiol-bridges to gold electrodes, it

Paula Jofre, Andreas Reisenegger, Rodrigo Fernandez

A hypothetical time-variation of the gravitational constant $G$ would cause neutron star matter to depart from beta equilibrium, due to the changing hydrostatic equilibrium. This forces non-equilibrium beta processes to occur, which release energy that is invested partly in neutrino emission and partly in heating the stellar interior. Eventually, the star ar

Congjun Wu, W. Vincent Liu, Joel Moore, Sankar Das Sarma

We predict the robust existence of a novel quantum orbital stripe order in the $p$-band Bose-Hubbard model of two-dimensional triangular optical lattices with cold bosonic atoms. An orbital angular momentum moment is formed on each site exhibiting a stripe order both in the superfluid and Mott-insulating phases. The stripe order spontaneously breaks time-rev

C. Reichhardt, C. J. Olson Reichhardt

Using numerical simulations we show that, in the presence of random quenched disorder, sliding superconducting vortices and Wigner crystals pass through a variety of dynamical phases when an additional transverse driving force is applied. If the disorder is weak, the driven particles form a moving lattice and the transverse response shows a devil&#39;s stair

S. Casanova, B. L. Dingus, Bing Zhang

TeV gamma rays emitted by GRBs are converted into electron-positron pairs via interactions with the extragalactic infrared radiation fields. In turn the pairs produced, whose trajectories are randomized by magnetic fields, will inverse Compton scatter off the cosmic microwave background photons. The beamed TeV gamma ray flux from GRBs is thus transformed int

Yuji Koike, Junji Nagashima, Werner Vogelsang

We study the transverse-momentum distribution of hadrons produced in semi-inclusive deep-inelastic scattering. We consider cross sections for various combinations of the polarizations of the initial lepton and nucleon or the produced hadron, for which we perform the resummation of large double-logarithmic perturbative corrections arising at small transverse

Denis Lacroix

In this article, we consider a set of trial wave-functions denoted by $| Q \right>$ and an associated set of operators $A_α$ which generate transformations connecting those trial states. Using variational principles, we show that we can always obtain a quantum Monte-Carlo method where the quantum evolution of a system is replaced by jumps between density mat

S. A. Moiseev, B. S. Ham

Dynamic control of a weak quantum probe light pulse for the generation and quantum manipulations of a stationary multi-color (MC-) light field in a resonant coherent atomic medium using electromagnetically induced transparency is proposed. The manipulations have been analyzed based on the analytical solution of the adiabatic limit in the evolution of MC-ligh

M. A. Jafarizadeh, S. Salimi, R. Sufiani

In papers\cite{js,jsa}, the amplitudes of continuous-time quantum walk on graphs possessing quantum decomposition (QD graphs) have been calculated by a new method based on spectral distribution associated to their adjacency matrix. Here in this paper, it is shown that the continuous-time quantum walk on any arbitrary graph can be investigated by spectral dis

F. Franchini, A. R. Its, B. -Q. Jin, V. E. Korepin

Entanglement in the ground state of the XY model on the infinite chain can be measured by the von Neumann entropy of a block of neighboring spins. We study a double scaling limit: the size of the block is much larger then 1 but much smaller then the length of the whole chain. In this limit, the entropy of the block approaches a constant. The limiting entropy

E. Hernandez, A. Jauregui, A. Mondragon

We solved numerically the implicit, trascendental equation that defines the eigenenergy surface of a degenerating isolated doublet of unbound states in the simple but illustrative case of the scattering of a beam of particles by a double barrier potential. Unfolding the degeneracy point with the help of a contact equivalent approximant, crossings and anticro

Harry Buhrman, Matthias Christandl, Falk Unger, Stephanie Wehner

Non-local boxes are hypothetical ``machines&#39;&#39; that give rise to superstrong non-local correlations, leading to a stronger violation of Bell/CHSH inequalities than is possible within the framework of quantum mechanics. We show how non-local boxes can be used to perform any two-party secure computation. We first construct a protocol for bit commitment

Mohamed Doulazmi, Francesca Capone, Florence Frederic, JoËlle Bakouche

The staggerer (sg/sg) mutation is a spontaneous deletion in the Rora gene that prevents the translation of the ligand-binding domain (LBD), leading to the loss of RORαactivity. The homozygous Rorasg/sg mutant mouse, whose most obvious phenotype is ataxia associated with cerebellar degeneration, also displays a variety of other phenotypes. The heterozygous Ro

P. A. Rikvold, Th. Wandlowski, I. Abou Hamad, S. J. Mitchell

We reply to remarks by Lang and Horanyi on the meaning of the notion of &#34;electrosorption valency&#34; used in I. Abou Hamad et al., Electrochim. Acta 50 (2005) 5518. It is concluded that, contrary to the assertion of Lang and Horanyi, the magnitude of the current in the external circuit upon adsorption of an ion of charge ze with partial charge transfer

Vasily E. Tarasov

In this paper we consider the electric multipole moments of fractal distribution of charges. To describe fractal distribution, we use the fractional integrals. The fractional integrals are considered as approximations of integrals on fractals. In the paper we compute the electric multipole moments for homogeneous fractal distribution of charges.

A. S. Botvina, N. Buyukcizmeci, M. Erdogan, J. Lukasik

Within the statistical multifragmentation model we study modifications of the surface and symmetry energy of primary fragments in the freeze-out volume. The ALADIN experimental data on multifragmentation obtained in reactions induced by high-energy projectiles with different neutron richness are analyzed. We have extracted the isospin dependence of the surfa

Fabien Vignes-Tourneret

We prove that the non-commutative Gross-Neveu model on the two-dimensional Moyal plane is renormalizable to all orders. Despite a remaining UV/IR mixing, renormalizability can be achieved. However, in the massive case, this forces us to introduce an additional counterterm of the form &#34;psibar i gamma^{0} gamma^{1} psi&#34;. The massless case is renormaliz

U. A. Rozikov

In the paper a one-dimensional model with nearest - neighbor interactions $I_n, n\in \Z$ and spin values $\pm 1$ is considered. We describe a condition on parametres $I_n$ under which the phase transition occurs. In particular, we show that the phase transition occurs if $I_n\geq |n|, n\in \Z.$

Domenico Giulini

Mapping-class groups of 3-manifolds feature as symmetry groups in canonical quantum gravity. They are an obvious source through which topological information could be transmitted into the quantum theory. If treated as gauge symmetries, their inequivalent unitary irreducible representations should give rise to a complex superselection structure. This highligh

Omar Mustafa, S. Habib Mazharimousavi

The d-dimensional generalization of the point canonical transformation for a quantum particle endowed with a position-dependent mass in Schrodinger equation is described. Illustrative examples including; the harmonic oscillator, Coulomb, spiked harmonic, Kratzer, Morse oscillator, Poschl-Teller and Hulthen potentials are used as reference potentials to obtai

Driss Bennis, Najib Mahdou

In this paper, we study a particular case of Gorenstein projective, injective, and flat modules, which we call, respectively, strongly Gorenstein projective, injective, and flat modules. These last three modules give us a new characterization of the first modules, and confirm that there is an analogy between the notion of Gorenstein projective, injective, an

Carlos Duran, Thomas Puettmann

We recognize the Gromoll-Meyer sphere Sigma^7 as the geodesic join of a simple closed geodesic and a minimal subsphere Sigma^5, which can be equivariantly identified with the Brieskorn sphere W^5_3. As applications we in particular determine the full isometry group of Sigma^7, classify all closed subgroups that act freely, determine the homotopy type of the

Arnaud Basson, David Gerard-Varet

The general concern of this paper is the effect of rough boundaries on fluids. We consider a stationary flow, governed by incompressible Navier-Stokes equations, in an infinite domain bounded by two horizontal rough plates. The roughness is modeled by a spatially homogeneous random field, with characteristic size $\eps$. A mathematical analysis of the flow f

Primoz Sparl

A graph is said to be {\em half-arc-transitive} if its automorphism group acts transitively on the set of its vertices and edges but not on the set of its arcs. With each half-arc-transitive graph of valency 4 a collection of the so called {\em alternating cycles} is associated, all of which have the same even length. Half of this length is called the {\em r

Carsten Schultz

By Lovasz&#39; proof of the Kneser conjecture, the chromatic number of a graph G is bounded from below by the index of the Z_2-space Hom(K_2,G) plus two. We show that the cohomological index of Hom(K_2,G) is also greater than the cohomological index of the Z_2-space Hom(C_{2r+1}, G) for r>0. This gives a new and simple proof of the strong form of the graph c

Kijung Lee, Carl Mueller, Jei Xiong

For a superprocess under a stochastic flow, we prove that it has a density with respect to the Lebesgue measure for d=1 and is singular for d>1. For d=1, a stochastic partial differential equation is derived for the density. The regularity of the solution is then proved by using Krylov&#39;s L_p-theory for linear SPDE. A snake representation for this superpr

G. Burde, W. Schwarz, J. Wolfart, A. D. Coste

This is a free summary of a much longer article published in german in &#34;Forschung Frankfurt&#34;. This article presents facts concerning the works of Max Dehn and the history of Frankfurt University. E. Hellinger, R. Moufang, C. L. Siegel, A. Weil, P. Epstein, W. Hartner are named among others. Of course these texts are centered around the critical perio

Andrea Causin, Gian Pietro Pirola

We give some upper bounds on the dimension of the kernel of the cup product map $H^{1}(X,\mathbb{C})\otimes H^{1}(X,\mathbb{C}) \to H^{2}(X,\mathbb{C})$, where $X$ is a compact Kähler variety without Albanese fibrations.

C. Houdré, P. Reynaud-Bouret

For various classes of Lipschitz functions we provide dimension free concentration inequalities for infinitely divisible random vectors with independent components and finite exponential moments.

Andrea Collevecchio

We introduce a simple technique for proving the transience of certain processes defined on the random tree $\mathcal{G}$ generated by a supercritical branching process. We prove the transience for once-reinforced random walks on $\mathcal{G}$, that is, a generalization of a result of Durrett, Kesten and Limic [Probab. Theory Related Fields 122 (2002) 567--59

Ádám Timár

We show that for a transitive unimodular graph, the number of ends is the same for every tree of the free minimal spanning forest. This answers a question of Lyons, Peres and Schramm.

Julian Pfeifle

We give an explicit construction, based on Hadamard matrices, for an infinite series of floor{sqrt{d}/2}-neighborly centrally symmetric d-dimensional polytopes with 4d vertices. This appears to be the best explicit version yet of a recent probabilistic result due to Linial and Novik, who proved the existence of such polytopes with a neighborliness of d/400.

Lyudmyla Yu. Polyakova

A free resolution of free partially commutative monoids is constructed and with its help the homological dimension of these monoids is calculated.

Alexandre Eremenko

A version of Markov&#39;s estimate for the derivative of a polynomial is proved with the interval [-1,1] replaced by an arbitrary continuum in the complex plane.

Mourad E H Ismail

We give one parameter generalizations of the Fibonacci and Lucas numbers denoted by $\{F_n(þ)\}$ and $\{L_n(þ)\}$, respectively. We evaluate the Hankel determinants with entries $\{1/F_{j+k+1}(þ): 0\le i,j \le n\}$ and $\{1/L_{j+k+1}(þ): 0\le i,j\le n\}$. We also find the entries in the inverse of $\{1/F_{j+k+1}(þ): 0\le i,j \le n\}$ and show that all its en

Masaki Tsukamoto

We study entire holomorphic curves in the algebraic torus, and show that they can be characterized by the ``growth rate&#39;&#39; of their derivatives.

Bahram Rangipour

In this note we prove that the constant and equivariant cyclic cohomology of algebras coincide. This shows that constant cyclic cohomology is rich and computable.

Claudio Landim, Glauco Valle

We study a class of one-dimensional interacting particle systems with random boundaries as a microscopic model for Stefan&#39;s melting and freezing problem. We prove that under diffusive rescaling these particle systems exhibit a hydrodynamic behavior described by the solution of a Cauchy--Stefan problem.

Steven N. Evans, Anita Winter

We use Dirichlet form methods to construct and analyze a reversible Markov process, the stationary distribution of which is the Brownian continuum random tree. This process is inspired by the subtree prune and regraft (SPR) Markov chains that appear in phylogenetic analysis. A key technical ingredient in this work is the use of a novel Gromov--Hausdorff type

Olivier Daviaud

We consider the lattice version of the free field in two dimensions and study the fractal structure of the sets where the field is unusually high (or low). We then extend some of our computations to the case of the free field conditioned on being everywhere nonnegative. For example, we compute the width of the largest downward spike of a given length. Throug

Scott Sheffield

An essential spanning forest of an infinite graph $G$ is a spanning forest of $G$ in which all trees have infinitely many vertices. Let $G_n$ be an increasing sequence of finite connected subgraphs of $G$ for which $\bigcup G_n=G$. Pemantle&#39;s arguments imply that the uniform measures on spanning trees of $G_n$ converge weakly to an $\operatorname {Aut}(G

Philippe Chassaing, Bergfinnur Durhuus

Exploiting a bijective correspondence between planar quadrangulations and well-labeled trees, we define an ensemble of infinite surfaces as a limit of uniformly distributed ensembles of quadrangulations of fixed finite volume. The limit random surface can be described in terms of a birth and death process and a sequence of multitype Galton--Watson trees. As

Tom Banks, Matt Johnson, Assaf Shomer

We analyze the bound on gauge couplings $e\geq m/m_p$, suggested by Arkani-Hamed et.al. We show this bound can be derived from simple semi-classical considerations and holds in spacetime dimensions greater than or equal to four. Non abelian gauge symmetries seem to satisfy the bound in a trivial manner. We comment on the case of discrete symmetries and close

J. L. Cornou, E. Pajer, R. Sturani

Fundamental superstrings (F-strings) and D-strings may be produced at high temperature in the early Universe. Assuming that, we investigate if any of the instabilities present in systems of strings and branes can give rise to a phenomenologically interesting production of gravitons. We focus on D-strings and find that D-string recombination is a far too weak

Marta Gomez-Reino, Claudio A. Scrucca

We further develop on the study of the conditions for the existence of locally stable non-supersymmetric vacua with vanishing cosmological constant in supergravity models involving only chiral superfields. Starting from the two necessary conditions for flatness and stability derived in a previous paper (which involve the Kahler metric and its Riemann tensor

T. Banks

The meta-stable SUSY breaking mechanism of Intriligator Seiberg and Shih can be used to simplify the Pentagon model of TeV scale physics. The simplified model has only a single scalar field and no troublesome low energy axion. One significant signature is $l^+ l^- X$ plus missing energy, where $X$ might be the two photons of gauge mediated models, but is lik

V. Barger, Patrick Huber, Danny Marfatia

We deduce the cosmogenic neutrino flux by jointly analysing ultra high energy cosmic ray data from HiRes-I and II, AGASA and the Pierre Auger Observatory. We make two determinations of the neutrino flux by using a model-dependent method and a model-independent method. The former is well-known, and involves the use of a power-law injection spectrum. The latte

Mauro Napsuciale, Mariana Kirchbach, Simon Rodriguez

We employ the two independent Casimir operators of the Poincare group, the squared four--momentum, P^2, and the squared Pauli-Lubanski vector, W^2, in the construction of a covariant mass-m, and spin-3/2 projector in the four-vector-spinor, ψ_μ. This projector provides the basis for the construction of an interacting Lagrangian that describes a causally prop

I. Antoniadis, A. Boyarsky, Oleg Ruchayskiy

If recent results of the PVLAS collaboration proved to be correct, some alternative to the traditional axion models are needed. We present one of the simplest possible modifications of axion paradigm, which explains the results of PVLAS experiment, while avoiding all the astrophysical and cosmological restrictions. We also mention other possible models that

T. Pietrycki, A. Szczurek

The invariant cross sections for direct photon production in hadron-hadron collisions are calculated for several initial energies (SPS, ISR, S$p \bar p$S, RHIC, Tevatron, LHC) including initial parton transverse momenta within the formalism of unintegrated parton distributions (UPDF). Different approaches from the literature are compared and discussed. A spe

Stefan Weinzierl

I review the state-of-the-art for fully differential numerical NNLO programs. Topics which are covered include the calculation of two-loop amplitudes, multiple polylogarithms, cancellation of infra-red divergences at NNLO and the efficient generation of the phase space. Numerical results for e+ e- --> 2 jets are also discussed.

Tomas Brauner

This is the introduction to the PhD thesis, defended in June 2006. In the original form it was appended with the reprints of the author&#39;s published papers, and is to be regarded as their summary. Full details may be found in the quoted papers.

A. Bianconi, B. Pasquini, M. Radici

We have performed numerical simulations of the unpolarized e+e- --> p pbar process in kinematic conditions under discussion for a possible upgrade of the existing DAFNE facility. By fitting the cross section angular distribution with a typical Born expression, we can extract information on the ratio |G_E/G_M| of the proton electromagnetic form factors in the

De-Min Li, Zhen Li

The masses of the $K_1(^3P_1)$ and $K_1(^1P_1)$ are considered in a nonrelativistic constituent quark model, and the absolute value of the $K_1(^3P_1)-K_1(^1P_1)$ mixing angle is determined to be about $59.29^\circ$. Comparison of the theoretical predictions on the strong decay widths of the $K_1(1270)$ and $K_1(1400)$ in the $^3P_0$ decay model as well as t

Christian Schmidt

Ongoing calculations on the QCDOC supercomputer at Brookhaven National Laboratory and the APEnext installation at the University of Bielefeld aim to determine the critical temperature of the QCD phase transition as well as the equation of state with almost realistic quark masses. We will discuss preliminary results of the quark mass and cut-off dependence of

George Sparling

Following the approach of Julien Lesgourgues [astro-ph/0409426], we analyze the mathematical structure of the time co-ordinate of present day cosmological models, where these models include a cosmological constant term to account for the observed acceleration of the universe: we find that in all cases, except for a set of measure zero in the parameter space,

Mark E. Rupright

The problem of resolving spherical harmonic components from numerical data defined on a rectangular grid has many applications, particularly for the problem of gravitational radiation extraction. A novel method due to Misner improves on traditional techniques by avoiding the need to cover the sphere with a coordinate system appropriate to the grid geometry.

Michal Demetrian

The second order Coleman - de Luccia instanton and its action in the Randall - Sundrum type II model are investigated and the comparison with the results in Einstein&#39;s general relativity is done in the present paper.

Clemens Heuson

We consider deformed special relativity (DSR) theories on commutative space-time, perhaps as an first approximation to a noncommutative space-time formulation. The corresponding field theories in general possess derivatives of all orders. From a quantisation procedure and the deformed Dirac equation in momentum space we obtain for a specific DSR model enhanc

A. Garcia, W. Guzman, M. Sabido, J. Socorro

Using the factorization approach of quantum mechanics, we obtain a family of isospectral scalar potentials for power law inflationary cosmology. The construction is based on a scattering Wheeler-DeWitt solution. These iso-spectrals have new features, they give a mechanism to end inflation, as well as the possibility to have new inflationary epochs. The proce

Eldan Goldenberg, Jacob R. Garcowski, Randall D. Beer

In this paper we present a deeper analysis than has previously been carried out of a selective attention problem, and the evolution of continuous-time recurrent neural networks to solve it. We show that the task has a rich structure, and agents must solve a variety of subproblems to perform well. We consider the relationship between the complexity of an agen

Marius Marin

We present a consistent system for referring crosscutting functionality, relating crosscutting concerns to specific implementation idioms, and formalizing their underlying relations through queries. The system is based on generic crosscutting concerns that we organize and describe in a catalog. We have designed and implemented a tool support for querying sou

Atos Ramos Alves

To demonstrate the result of researches in laboratory with the focus in exhibiting the real impact of the use of the technology MPLS in LAN. Through these researches we will verify that the investment in this technology is shown, of the point of view cost/benefit, very interesting, being necessary, however, the adoption of another measured, in order to settl

Wolfgang Mueller, P. Oscar Boykin, Nima Sarshar, Vwani P. Roychowdhury

Given some of the recent advances in Distributed Hash Table (DHT) based Peer-To-Peer (P2P) systems we ask the following questions: Are there applications where unstructured queries are still necessary (i.e., the underlying queries do not efficiently map onto any structured framework), and are there unstructured P2P systems that can deliver the high bandwidth

Enrico Formenti, Benoît Masson, Theophilos Pisokas

A symmetric version of the well-known SPM model for sandpiles is introduced. We prove that the new model has fixed point dynamics. Although there might be several fixed points, a precise description of the fixed points is given. Moreover, we provide a simple closed formula for counting the number of fixed points originated by initial conditions made of a sin