October 2006 arXiv papers — page 33

Mu-in Park

It has been widely believed that the Hawking temperature for a black hole is $uniquely$ determined by its metric and $positive$. But, I find that this does ``not'' seem to be true in the recently discovered black holes which include the exotic black holes and the black holes in the three-dimensional higher curvature gravities. I show that the Hawking

K. Maruyama, T. Iitaka, F. Nori

We study the effect of a phase shift on the amount of transferrable two-spin entanglement in a spin chain. We consider a ferromagnetic Heisenberg/XY spin chain, both numerically and analytically, and two mechanisms to generate a phase shift, the Aharonov-Casher effect and the Dzyaloshinskii-Moriya interaction. In both cases, the maximum attainable entangleme

K. B. Efetov, I. L. Aleiner

We discuss a recent bosonization method developed to study clean Fermi gases with a repulsion in any dimensions. The method enables one to consider both density and spin excitations. It is demonstrated that due to a non-abelian structure of the effective theory, the spin excitations interact with each other, which leads to new logarithmic in temperature corr

G. Catelani

The electron-electron interaction corrections to the transport coefficients are calculated for a two-dimensional disordered metal in a parallel magnetic field via the quantum kinetic equation approach. For the thermal transport, three regimes (diffusive, quasiballistic and truly ballistic) can be identified as the temperature increases. For the diffusive and

Yong Li, C. Bruder, C. P. Sun

Time-dependent Fröhlich transformations can be used to derive an effective Hamiltonian for a class of quantum systems with time-dependent perturbations. We use such a transformation for a system with time-dependent atom-photon coupling induced by the classical motion of two atoms in an inhomogeneous electromagnetic field. We calculate the entanglement betwee

F. Le Pimpec, R. Ganter, R. Betemps

In the framework of the Low Emittance Gun (LEG) project, high gradient acceleration of a low emittance electron beam will be necessary. In order to achieve this acceleration a -500 kV, 250 ns FWHM, pulse will be applied in between two electrodes. Those electrodes should sustain the pulsed field without arcing, must not outgass and must not emit electrons. Io

Tom Fisher

We continue our development of the invariant theory of genus one curves with the aim of computing certain twists of the universal family of elliptic curves parametrised by the modular curve X(n) for n = 2,3,4,5. Our construction makes use of a covariant we call the Hessian, generalising the classical Hessian that exists in degrees 2 and 3. In particular we g

Daniel O'Dea, Anthony Challinor, Bradley R. Johnson

We investigate the impact of instrumental systematic errors on the potential of cosmic microwave background polarization experiments targeting primordial B-modes. To do so, we introduce spin-weighted Muller matrix-valued fields describing the linear response of the imperfect optical system and receiver, and give a careful discussion of the behaviour of the i

Yan-Hua Zhai, Xi-Hao Chen, Ling-An Wu

The nature of two-photon interference is a subject that has aroused renewed interest in recent years and is still under debate. In this paper we report the first observation of two-photon interference with independent pseudo-thermal sources in which sub-wavelength interference is observed. The phenomenon may be described in terms of the classical statistical

Itai Benjamini, Raphael Rossignol

We study a model of random electric networks with Bernoulli resistances. In the case of the lattice Z^2, we show that the point-to-point effective resistance between 0 and a vertex v has a variance of order at most (log |v|)^(2/3) whereas its expected value is of order log |v|, when v goes to infinity. When the dimension of Z^d is different than 2, expectati

Bernhard Baumgartner, Beatrix Hiesmayr, Heide Narnhofer

Focus is on two parties with Hilbert spaces of dimension d, i.e. "qudits". In the state space of these two possibly entangled qudits an analogue to the well known tetrahedron with the four qubit Bell states at the vertices is presented. The simplex analogue to this magic tetrahedron includes mixed states. Each of these states appears to each of the t

Stephen D. Cohen, Sophie Huczynska

An element w of the extension E of degree n over the finite field F=GF(q) is called free over F if {w, w^q,...,w^{q^{n-1}}} is a (normal) basis of E/F. The Primitive Normal Basis Theorem, first established in full by Lenstra and Schoof (1987), asserts that for any such extension E/F, there exists an element w in E such that w is simultaneously primitive (i.e

Jan Rosseel, Thomas Van Riet, Dennis B. Westra

We construct exact cosmological scaling solutions in N=8 gauged supergravity. We restrict to solutions for which the scalar fields trace out geodesic curves on the scalar manifold. Under these restrictions it is shown that the axionic scalars are necessarily constant. The potential is then a sum of exponentials and has a very specific form that allows for sc

Xi-Guo Lee, Zi-Yu Liu, Yong-Qing Li, Peng-Ming Zhang

We construct an M-solitons solutions in Jackiw-Pi model depends on 5M parameters(two positions, one scale, one phase per solition and one charge of each solution). By using ϕ-mapping method, we discuss the topological structure of the self-duality solution in Jackiw-Pi model in terms of gauge potential decomposition. We set up relationship between Chern-Simo

F. van Beijnum, E. G. van Putten, K. L. van der Molen, A. P. Mosk

Buchanan et al. [Nature 436, p. 475 (2005)] have shown that it is possible to recognize paper samples via their speckle pattern by using a line-shaped laser focus, four photo detectors and a scanning mechanism. In this report recognition of five out of ten paper samples is presented. The sample was illuminated by a 2.62 +- 0.02 mm circular spot and the refle

R. Meijerink, M. Spaans, F. P. Israel

\abridged The nuclei of active galaxies harbor massive young stars, an accreting central black hole, or both. In order to determine the physical conditions that pertain to molecular gas close to the sources of radiation, numerical models are constructed. These models determine the thermal and chemical balance of molecular gas that is exposed to X-rays and fa

Xiao-Fan Mo, Tao Zhang, Fang-Xing Xu, Zheng-Fu Han

Most traditional applications of quantum cryptography are point-to-point communications, in which only two users can exchange keys. In this letter, we present a network scheme that enable quantum key distribution between multi-user with wavelength addressing. Considering the current state of wavelength division multiplexing technique, dozens or hundreds of u

T. Shirakawa, S. Horiuchi, Y. Ohta, H. Fukuyama

We consider superconductivity in boron (B) doped diamond using a simplified model for the valence band of diamond. We treat the effects of substitutional disorder of B ions by the coherent potential approximation (CPA) and those of the attractive force between holes by the ladder approximation under the assumption of instantaneous interaction with the Debye

Benjamin Enriquez, Sergey Khoroshkin, Stanislav Pakuliak

A universal weight function for a quantum affine algebra is a family of functions with values in a quotient of its Borel subalgebra, satisfying certain coalgebraic properties. In representations of the quantum affine algebra it gives off-shell Bethe vectors and is used in the construction of solutions of the qKZ equations. We construct a universal weight fun

Paul A Crowther

The striking broad emission line spectroscopic appearance of Wolf-Rayet (WR) stars has long defied analysis, due to the extreme physical conditions within their line and continuum forming regions. Recently, model atmosphere studies have advanced sufficiently to enable the determination of stellar temperatures, luminosities, abundances, ionizing fluxes and wi

Takehiko Yasuda

In his previous paper, the author has defined a higher version of the Nash blowup and considered it a possible candidate for the one-step resolution. In this paper, we will introduce another higher version of the Nash blowup and prove that it is compatible with products and smooth morphisms. We will also prove that the product of curves can be desingularized

TAMA Collaboration, T. Akutsu

We analyze the data of TAMA300 detector to search for gravitational waves from inspiraling compact star binaries with masses of the component stars in the range 1-3Msolar. In this analysis, 2705 hours of data, taken during the years 2000-2004, are used for the event search. We combine the results of different observation runs, and obtained a single upper lim

Leila Feiz, Muhammad Irshad, Rafael F Pont-Lezica, Hervé Canut

The ultimate goal of proteomic analysis of a cell compartment should be the exhaustive identification of resident proteins; excluding proteins from other cell compartments. Plant cell walls possess specific difficulties. Several reported procedures to isolate cell walls for proteomic analyses led to the isolation of a high proportion (more than 50%) of predi

Koji Fujiwara, Kevin Whyte

Let $X$ be a geodesic metric space with $H_1(X)$ uniformly generated. If $X$ has asymptotic dimension one then $X$ is quasi-isometric to an unbounded tree. As a corollary, we show that the asymptotic dimension of the curve graph of a compact, oriented surface with genus $g \ge 2$ and one boundary component is at least two.

F. Chen, G. L. Klimchitskaya, V. M. Mostepanenko, U. Mohideen

We report the first experiment on the optical modulation of dispersion forces through a change of the carrier density in a Si membrane. For this purpose a high-vacuum based atomic force microscope and excitation light pulses from an Ar laser are used. The experimental results are compared with two theoretical models. The modulation of the dispersion force wi

G. N. Throumoulopoulos, H. Weitzner, H. Tasso

It is proved that irrespective of compressibility tokamak steady states with purely poloidal mass flow can not exist in the framework of either magnetohydrodynamics (MHD) or Hall MHD models. Non-existence persists within single fluid plasma models with pressure anisotropy and incompressible flows.

Jérôme Mathé, Jean-Marc Di Meglio, Bernard Tinland

We report an alternative method for electrophoretic separation of large DNAs using steric confinement between solid walls, without gel or obstacles. The change of electrophoretic mobility vs confinement thickness is investigated using fluorescence video microscopy. We observe separation at small confinement thicknesses followed by a transition to the bulk be

Christopher J. Hillar, Jiawang Nie

We give a short and elementary proof of a theorem of Procesi, Schacher and (independently) Gondard, Ribenboim that generalizes a famous result of Artin. Let $A$ be an $n \times n$ symmetric matrix with entries in the polynomial ring $\mathbb R[x_1,...,x_m]$. The result is that if $A$ is postive semidefinite for all substitutions $(x_1,...,x_m) \in \mathbb R^

Congjun Wu, Kai Sun, Eduardo Fradkin, Shou-Cheng Zhang

We study the Fermi surface instabilities of the Pomeranchuk type in the spin triplet channel with high orbital partial waves ($F_{l}^a ~(l>0)$). The ordered phases are classified into two classes, dubbed the $α$ and $β$-phases by analogy to the superfluid $^3$He-A and B-phases. The Fermi surfaces in the $α$-phases exhibit spontaneous anisotropic distortions,

J. L. Lucio M.

We point out limitations to the analogy between the continuous variable and spin 1/2 systems and show that the maximal violation of Bell inequality is related to an infinite degeneracy. We quantify non-maximal violation of the Bell-CHSH inequality and comment potential experimental implications of our work.

G. Vidal

We introduce the multi-scale entanglement renormalization ansatz (MERA), an efficient representation of certain quantum many-body states on a D-dimensional lattice. Equivalent to a quantum circuit with logarithmic depth and distinctive causal structure, the MERA allows for an exact evaluation of local expectation values. It is also the structure underlying e

Noah Linden, Sandu Popescu, Anthony J. Short, Andreas Winter

We investigate the problem of "nonlocal" computation, in which separated parties must compute a function with nonlocally encoded inputs and output, such that each party individually learns nothing, yet together they compute the correct function output. We show that the best that can be done classically is a trivial linear approximation. Surprisingly,

Stefan Scheel, E. A. Hinds, P. L. Knight

We comment on a recent paper [Phys. Rev. Lett. 97, 070401 (2006): quant-ph/0603229] concerning rubidium atoms trapped near a superconducting niobium surface at ~4K. This seeks to calculate the rate of atomic spin flips induced by thermal magnetic noise. We point out that the calculation is in error by a large factor because it is based on the two-fluid model

T. C. Ralph

We discuss a model for non-linear quantum evolution based on the idea of time displaced entanglement, produced by taking one member of an entangled pair on a round trip at relativistic speeds, thus inducing a time-shift between the pair. We show that decoherence of the entangled pair is predicted. For non-maximal entanglement this then implies the ability to

Fergal P. Casey, Dan Baird, Qiyu Feng, Ryan N. Gutenkunst

We apply the methods of optimal experimental design to a differential equation model for epidermal growth factor receptor (EGFR) signaling, trafficking, and down-regulation. The model incorporates the role of a recently discovered protein complex made up of the E3 ubiquitin ligase, Cbl, the guanine exchange factor (GEF), Cool-1 (Beta-Pix), and the Rho family

Willy A. Valdivia-Granda, Maricel G. Kann, Jose Malaga

Smallpox is a deadly disease that can be intentionally reintroduced into the human population as a bioweapon. While host gene expression microarray profiling can be used to detect infection, the analysis of this information using unsupervised and supervised classification techniques can produce contradictory results. Here, we present a novel computational ap

Elisabeth Jamet, Hervé Canut, Georges Boudart, Rafael F Pont-Lezica

Cell wall proteins are essential constituents of plant cell walls; they are involved in modifications of cell wall components, wall structure, signaling and interactions with plasma membrane proteins at the cell surface. The application of proteomic approaches to the cell wall compartment raises important questions: are there technical problems specific to c

Abhishek Parakh

This paper presents the principle of relativity of motion as described in Aryabhata's text Aryabhatiya. This principle is likely to have been instrumental in the faming of Aryabhata's theory that the earth rotated on its axis and, therefore, it has played a very important role in the history of astronomy.

Jacek Mulak, Maciej Mulak

A new measure of the crystal-field strength, complementary to the conventional one, is defined. It is based on the rotational invariants |B_{k0}|_{av} or |\sum_{k}B_{k0}|_{av}, k=2,4,6, of the crystal-(ligand)-field (CF) Hamiltonian H_{CF} parametrizations, i.e. on the axial CF parameters modules averaged over all reference frame orientations. They turn out

Joop M. Houtkooper, Dirk Schulze-Makuch

The adaptability of extremophiles on Earth raises the question of what strategies putative life might have used to adapt to the present conditions on Mars. Here, we hypothesize that organisms might utilize a water-hydrogen peroxide (H2O-H2O2) mixture rather than water as an intracellular liquid. This adaptation would have the particular advantages in the mar

Randall D. Peters

The period of an undamped compound pendulum has been selected to maximize the instrument's response to microseisms, when functioning as a type of horizontal seismometer. When functioning as a tiltmeter, the instrument is also capable of monitoring eigenmode oscillations of the Earth. Other instruments designed by the author, some of which were monitored

C. Zinoni, B. Alloing, L. H. Li, F. Marsili

Single photonic applications - such as quantum key distribution - rely on the transmission of single photons, and require the ultimate sensitivity that an optical detector can achieve. Single-photon detectors must convert the energy of an optical pulse containing a single photon into a measurable electrical signal. We report on fiber-coupled superconducting

Gregor Knoener, Simon Parkin, Timo A. Nieminen, Norman R. Heckenberg

The refractive index of single microparticles is derived from precise measurement and rigorous modeling of the stiffness of a laser trap. We demonstrate the method for particles of four different materials with diameters from 1.6 to 5.2 microns and achieve an accuracy of better than 1%. The method greatly contributes as a new characterization technique becau

A. A. Castrejon-Pita, G. Huelsz

In this work, a new concept for the conversion of heat into electricity is presented. The conversion is based on the combined effects of a thermoacoustic prime mover coupled with a magnetohydrodynamic generator, using different working fluids in each process. The results of preliminary experiments are also presented.

Magdalena Djordjevic

We give a theoretical overview of the heavy quark tomography puzzle posed by recent non-photonic single electron data from central Au+Au collisions at $\sqrt{s} = 200$ AGeV. We show that radiative energy loss mechanisms alone are not able to explain large single electron suppression data, as long as realistic parameter values are assumed. We argue that combi

Renato Higa, Manoel R. Robilotta, Carlos A. da Rocha

We outline the progress made in the past five years by the São Paulo group in the development of a two-pion exchange nucleon-nucleon potential within a Lorentz-invariant framework of (baryon) chiral perturbation theory.

J. Kapusta

Photons and dileptons are being used to probe the properties of nuclear and quark-gluon matter at high energy densities. This is an area where theory and experiment are driving each other to obtain solid results. However, it is important to clearly separate the assumptions and conclusions concerning the correlation and response functions of a system in therm

D. V. Shetty, S. J. Yennello, G. A. Souliotis

The density dependence of the symmetry energy in the equation of state of asymmetric nuclear matter (N/Z $>$ 1) is important for understanding the structure of systems as diverse as the atomic nuclei and neutron stars. Due to a proper lack of understanding of the basic nucleon-nucleon interaction for matters that are highly asymmetric and at non-normal nucle

A. T. Grecu, D. Grecu, Anca Visinescu

The modulational instability in the class of NLS equations is discussed using a statistical approach. A kinetic equation for the two-point correlation function is studied in a linear approximation, and an integral stability equation is found. The modulational instability is associated with a positive imaginary part of the frequency. The integral equation is

P. A. Treharne, A. S. Fokas

For the two versions of the KdV equation on the positive half-line an initial-boundary value problem is well posed if one prescribes an initial condition plus either one boundary condition if $q_{t}$ and $q_{xxx}$ have the same sign (KdVI) or two boundary conditions if $q_{t}$ and $q_{xxx}$ have opposite sign (KdVII). Constructing the generalized Dirichlet t

Chengshi Liu

Under the travelling wave transformation, Calogero-Degasperis-Focas equation was reduced to an ordinary differential equation. Using a symmetry group of one-parameter, this ODE was reduced to a second order linear inhomogeneous ODE. Furthermore, we applied the change of the variable and complete discrimination system for polynomial to solve the corresponding

A. G. Ramm, S. Gutman

Scattering properties of a material are changed when the material is injected with small acoustically soft particles. It is shown that its new scattering behavior can be understood as a solution of a potential scattering problem with the potential $q$ explicitly related to the density of the small particles. In this paper we examine the inverse problem of de

Rolf Dyre Svegstrup

In algebraic quantum field theory we consider nets of von Neumann algebras indexed over regions of the space-time. Wiesbrock has shown that strongly additive nets of von Neumann algebras on the circle are in correspondence with standard half-sided modular inclusions. We show that a finite index endomorphism on a half-sided modular inclusion extends to a fini

Daniel Farley

If G is a finite graph and n is a natural number, then the n-strand braid group of G is the fundamental group of the configuration space of n points on G. This article gives a complete computation of the integral cohomology rings of the n-strand braid groups in case G is a tree. Some of the argument builds on earlier joint work with Lucas Sabalka.

Anvar Mavlyutov

We explicitly describe cohomology of the sheaf of differential forms with poles along a semiample divisor on a complete simplicial toric variety. As an application, we obtain a new vanishing theorem which is an analogue of the Bott-Steenbrink-Danilov vanishing theorem.

Petr Hajek, Richard Haydon

We prove two theorems about differentiable functions on the Banach space C(K), where K is compact. (i) If C(K) admits a non-trivial function of class C^m and of bounded support, then all continuous real-valued functions on C(K) may be uniformly approximated by functions of class C^m. (ii) If C(K) admits an equivalent norm with locally uniformly convex dual n

K. Muchewicz, S. Rybicki

In this article we study the existence, continuation and bifurcation from infinity of nonconstant solutions for a nonlinear Neumann problem. We apply the Leray-Schauder degree and the degree for SO(2)-equivariant gradient operators defined by the second author.

Gautami Bhowmik, Jan-Christoph Schlage-Puchta

We determine Davenport's constant for all groups of the form $\Z\_3\oplus \Z\_3\oplus\Z\_{3d}$.

A. Andrada, M. L. Barberis, G. Ovando

In this work we study a particular class of Lie bialgebras arising from Hermitian structures on Lie algebras such that the metric is ad-invariant. We will refer to them as Lie bialgebras of complex type. These give rise to Poisson Lie groups G whose corresponding duals G* are complex Lie groups. We also prove that a Hermitian structure on the Lie algebra $\m

Mark Wildon

By exploiting relationships between the values taken by ordinary characters of symmetric groups we prove two theorems in the modular representation theory of the symmetric group. 1. The decomposition matrices of symmetric groups in odd characteristic have distinct rows. In characteristic 2 the rows of a decomposition matrix labelled by the different partitio

Clive G. Wells

We prove the existence of a solution to an equation governing the number density within a compact domain of a discrete particle system for a prescribed class of particle interactions taking into account the effects of the diffusion and drift of the set of particles. Each particle carries a number of internal coordinates which may evolve continuously in time,

Michael Baake, Uwe Grimm

Two Delone sets are called homometric when they share the same autocorrelation or Patterson measure. A model set LAMBDA within a given cut and project scheme is a Delone set that is defined through a window W in internal space. The autocorrelation measure of LAMBDA is a pure point measure whose coefficients can be calculated via the so-called covariogram of

Michael Baake, Dirk Frettlöh, Uwe Grimm

Diffraction images with continuous rotation symmetry arise from amorphous systems, but also from regular crystals when investigated by powder diffraction. On the theoretical side, pinwheel patterns and their higher dimensional generalisations display such symmetries as well, in spite of being perfectly ordered. We present first steps and results towards a ge

G. Lusztig

We introduce a class of perverse sheaves on a partial flag manifold of a connected reductive group G defined over a finite field which are equivariant under the action of the group of rational points of G. The definition of this class is similar to the definition of parabolic character sheaves.

Patrice Philippon, Martin Sombra

We study the obstruction degrees of translates of sub-tori of multiplicative tori and we show how they are connected to lower bounds for the essential minimum of these varieties. In particular, we combine our computations with results of A. Schinzel and of F. Amoroso - R. Dvornicich, that we thus extend to translates of sub-tori defined over CM fields. This

Marina Avitabile, Sandro Mattarei

Thin Lie algebras are Lie algebras over a field, graded over the positive integers and satisfying a certain narrowness condition. In particular, all homogeneous components have dimension one or two, and are called diamonds in the latter case. The first diamond is the component of degree one, and the second diamond can only occur in degrees 3, 5, q or 2q-1, w

Moussa Balde, Ugo Boscain

Consider the planar linear switched system $\dot x(t)=u(t)Ax(t)+(1-u(t))Bx(t),$ where $A$ and $B$ are two $2\times2$ real matrices, $x \in \R^2$, and $u(.):[0,\infty[\to\{0,1\}$ is a measurable function. In this paper we consider the problem of finding a (coordinate-invariant) necessary and sufficient condition on $A$ and $B$ under which the system is asympt

Benjamin Braun, Mike Develin

Stanley's non-negativity theorem is at the heart of many of the results in Ehrhart theory. In this paper, we analyze the root behavior of general polynomials satisfying the conditions of Stanley's theorem and compare this to the known root behavior of Ehrhart polynomials. We provide a possible counterexample to a conjecture of the second author, M. B

Gruia Arsu

We prove an extended version of Cordes' lemma concerning trace-class properties of some special pseudo-differential operators. This version of Cordes' lemma is used to improve the results in \cite{Arsu} concerning the Schatten-class properties of pseudo-differential operators in the $(X,τ) $-quantization. Here $X$ is an $n$ dimensional vector space a

Ping Wei, Qiang Guan, Wensheng Yu, Long Wang

This paper analyzes the eigenvalue distribution of neutral differential systems and the corresponding difference systems, and establishes the relationship between the eigenvalue distribution and delay-independent stability of neutral differential systems. By using the ``Complete Discrimination System for Polynomials", easily testable necessary and suffic

Clement Dombry, Nadine Guillotin-Plantard

We study a Curie-Weiss model with a random external field generated by a dynamical system. Probabilistic limit theorems (weak law of large numbers, central limit theorems) are proven for the corresponding magnetization.

Nicolas Bouleau

We use the language of errors to handle local Dirichlet forms with square field operator (cf [2]). Let us consider, under the hypotheses of Donsker theorem, a random walk converging weakly to a Brownian motion. If in addition the random walk is supposed to be erroneous, the convergence occurs in the sense of Dirichlet forms and induces the Ornstein-Uhlenbeck

Nicolas Bouleau

A comparison of the "theory of random sequences" developed during the twentieth century and the axiomatic approach of probability theory proposed by Kolmogorov shows the importance of sigma-additivity as extension tool. Similarly, the Cauchy criterion appears to be an extension tool for mathematical analysis. The Dirichlet forms theory possesses also

Nicolas Bouleau

We consider a random variable $Y$ and approximations $Y\_n$, defined on the same probability space with values in the same measurable space as $Y$. We are interested in situations where the approximations $Y\_n$ allow to define a Dirichlet form in the space $L^2(P\_Y)$ where $P\_Y$ is the law of $Y$. Our approach consists in studying both biases and variance

Frank Connolly, Benjamin Fehrman, Michael Hartglass

In this paper we construct a model for the classifying space, BVCG, of a crystallographic group G of rank n relative to the family VC of virtually-cyclic subgroups of G. The model is used to show that there exists no other model for the virtually-cyclic classifying space of G with dimension less than vcd(G)+1, where vcd(G) denotes the virtual cohomological d

F. Cavalli, A. Gamba, G. Naldi, M. Semplice

Blood vessel networks form by spontaneous aggregation of individual cells migrating toward vascularization sites (vasculogenesis). A successful theoretical model of two dimensional experimental vasculogenesis has been recently proposed, showing the relevance of percolation concepts and of cell cross-talk (chemotactic autocrine loop) to the understanding of t

Fausto Cavalli, Giovanni Naldi, Gabriella Puppo, Matteo Semplice

Several relaxation approximations to partial differential equations have been recently proposed. Examples include conservation laws, Hamilton-Jacobi equations, convection-diffusion problems, gas dynamics problems. The present paper focuses onto diffusive relaxation schemes for the numerical approximation of nonlinear parabolic equations. These schemes are ba

Adilson Berlatto, Said Sidki

A virtual endomorphism of a group G is a homomorphism f from H into G where H is a subgroup of G of finite index m. The triple (G,H,f) produces a state-closed (or, self-similar) representation t of G on the 1-rooted m-ary tree. This paper is a study of properties of the image G^t when G is nilpotent. In particular, it is shown that if G is finitely generated

Mauricio Garay

We study the vanishing cycles on the Milnor fibre of a holomorphic map germ with special kind of non-isolated singularities which appear in symplectic geometry. We show, under assumptions given in the text, that the Lefschetz vanishing cycles freely generate the corresponding homology group of the Milnor fibre. We study two examples of applications: involuti

Gruia Arsu

We investigate the Schatten-class properties of pseudo-differential operators with the (revisted) method of Cordes and Kato. As symbol classes we use classes similar to those of Cordes in which the $L^{\infty}$% -conditions are replaced by $L^{p}$-conditions, $1\leq p<\infty $.

Everett C. Dade, Manoj K. Yadav

We classify all finite groups G such that the product of any two non-inverse conjugacy classes of G is always a conjugacy class of G. We also classify all finite groups G for which the product of any two G-conjugacy classes which are not inverse modulo the center of G is again a conjugacy class of G.

Ronald G. Douglas, Gadadhar Misra

For any open, connected and bounded set $Ω\subseteq \mathbb C^m$, let $\mathcal A$ be a natural function algebra consisting of functions holomorphic on $Ω$. Let $\mathcal M$ be a Hilbert module over the algebra $\mathcal A$ and $\mathcal M_0\subseteq \mathcal M$ be the submodule of functions vanishing to order $k$ on a hypersurface $\mathcal Z \subseteq Ω$.

Anton A. Klyachko

The known facts about solvability of equations over groups are considered from a more general point of view. A generalized version of the theorem about solvability of unimodular equations over torsion-free groups is proved. In a special case, this generalized version become a multivariable variant of this theorem. For unimodular equations over torsion free g

Mikiya Masuda, Taras Panov

A torus manifold is an even-dimensional manifold acted on by a half-dimensional torus with non-empty fixed point set and some additional orientation data. It may be considered as a far-reaching generalisation of toric manifolds from algebraic geometry. The orbit space of a torus manifold has a rich combinatorial structure, e.g., it is a manifold with corners

Paola Arias, Ashok Das, Jorge Gamboa, Justo Lopez-Sarrion

Analogies between the noncommutative harmonic oscillator and noncommutative fields are analyzed. Following this analogy we construct examples of quantum fields theories with explicit CPT and Lorentz symmetry breaking. Some applications to baryogenesis and neutrino oscillation are also discussed

Marcos Rosenbaum, J. David Vergara, L. Román Juárez

Using arbitrary symplectic structures and parametrization invariant actions, we develop a formalism, based on Dirac&#39;s quantization procedure, that allows us to consider theories with both space-space as well as space-time noncommutativity. Because the formalism has as a starting point an action, the procedure admits quantizing the theory either by obtain

E. Frenkel, A. Losev, N. Nekrasov

Many quantum field theories in one, two and four dimensions possess remarkable limits in which the instantons are present, the anti-instantons are absent, and the perturbative corrections are reduced to one-loop. We analyze the corresponding models as full quantum field theories, beyond their topological sector. We show that the correlation functions of all,

Paolo Benincasa, Alex Buchel, Roman Naryshkin

We consider strongly coupled gauge theory plasma with conserved global charges that allow for a dual gravitational description. We study the shear viscosity of the gauge theory plasma in the presence of chemical potentials for these charges. Using gauge theory/string theory correspondence we prove that at large &#39;t Hooft coupling the ratio of the shear vi

H. Reinhardt

Assuming that center vortices are the confining gauge field configurations, we argue that in gauges that are sensitive to the confining center vortex degrees of freedom, and where the latter lie on the Gribov horizon, the corresponding ghost form factor is infrared divergent. Furthermore, this infrared divergence disappears when center vortices are removed f

Tamar T. Khachidze, Anzor A. Khelashvili

We propose a symmetry of the Dirac equation under the interchange of signs of eigenvalues of the Dirac&#39;s $K$ operator. We show that the only potential which obeys this requirement is the Coulomb one for both vector and scalar cases.

H. Nikolic

I present a short overview of my recent achievements on the Bohmian interpretation of relativistic quantum mechanics, quantum field theory and string theory. This includes the relativistic-covariant Bohmian equations for particle trajectories, the problem of particle creation and destruction, the Bohmian interpretation of fermionic fields and the intrinsical

Walter D. van Suijlekom

We study the Connes-Kreimer Hopf algebra of renormalization in the case of gauge theories. We show that the Ward identities and the Slavnov-Taylor identities (in the abelian and non-abelian case respectively) are compatible with the Hopf algebra structure, in that they generate a Hopf ideal. Consequently, the quotient Hopf algebra is well-defined and has tho

Howard Baer, Azar Mustafayev, Stefano Profumo, Xerxes Tata

In supersymmetric models where the magnitude of the GUT scale gaugino mass parameter M_3 is suppressed relative to M_1 and M_2, the lightest neutralino can be a mixed higgsino-bino state with a thermal relic abundance in agreement with the WMAP central value for Ω_{\rm CDM} h^2 and consistent with all other phenomenological constraints. In these models, the

Silvano Simula

We summarize the results of a recent global analysis of proton and deuteron F2 structure function world data performed over a large range of kinematics, including recent measurements done at JLab with the CLAS detector. From these data the lowest moments (n <= 10) of the unpolarized structure functions are determined with good statistics and systematics. The

Juan Garcia-Bellido

The Minimal Supersymmetry Standard Model contains several hundreds of D- and F-flat directions that are lifted by soft susy breaking terms as well as by non-renormalizable terms. In a recent paper we find that only two of these directions, {\bf LLe} and {\bf udd} can accommodate inflation. The model predicts more than $10^3$ e-foldings with an inflationary s

E. G. Ferreiro

We present our results on transverse momentum fluctuations and multiplicity fluctuations in the framework of the clustering of color sources. In this approach, elementary color sources -strings- overlap forming clusters, so the number of effective sources is modified. These clusters decay into particles with mean transverse momentum that depends on the numbe

Arlene C. Aguilar, Joannis Papavassiliou

We study the necessary conditions for obtaining infrared finite solutions from the Schwinger-Dyson equation governing the dynamics of the gluon propagator. The equation in question is set up in the Feynman gauge of the background field method, thus capturing a number of desirable features. Most notably, and in contradistinction to the standard formulation, t

Ahmed Ali, Alexander Parkhomenko

We review and update the branching ratios for the $B \to (ρ,ω) γ$ decays, calculated in the QCD factorization approach in the next-to-leading order (NLO) in the strong coupling $α_s$ and to leading power in $Λ_{\rm QCD}/m_b$. The corrections take into account the vertex, hard-spectator and annihilation contributions and are found to be large. Theoretical exp

Quentin Duret, Bruno Machet

Investigating, in direct continuation of our previous paper hep-ph/0606303 the implications of the non-unitarity of mixing matrices for non-degenerate coupled systems that we demonstrated there, we examine more accurately the vicinity of Cabibbo-like mixing in quantum field theory. We show that it is possible to preserve one of its main features, namely that

D. J. Antonio, P. A. Boyle, C. Dawson, T. Izubuchi

We present the latest results from the UKQCD/RBC collaborations for the K_{l3} form factor with 2+1 flavours of dynamical domain wall quarks. Simulations are performed on 16^3x32x16 and 24^3x64x16 lattices with three values of the light quark mass, allowing for an extrapolation to the chiral limit. After interpolating to zero momentum transfer, we obtain the