July 2006 arXiv papers — page 7

Ronald G. Douglas

Many Hilbert modules over the polynomial ring in m variables are essentially reductive, that is, have commutators which are compact. Arveson has raised the question of whether the closure of homogeneous ideals inherit this property and provided motivation to seek an affirmative answer. Positive results have been obtained by Arveson, Guo, Wang and the author.

Dapeng Zhan

An annulus SLE$_κ$ trace tends to a single point on the target circle, and the density function of the end point satisfies some differential equation. Some martingales or local martingales are found for annulus SLE$_4$, SLE$_8$ and SLE$_{8/3}$. From the local martingale for annulus SLE$_4$ we find a candidate of discrete lattice model that may have annulus S

William Y. C. Chen, Susan Y. J. Wu, Catherine Yan

The notion of noncrossing linked partition arose from the study of certain transforms in free probability theory. It is known that the number of noncrossing linked partitions of [n+1] is equal to the n-th large Schroder number $r_n$, which counts the number of Schroder paths. In this paper we give a bijective proof of this result. Then we introduce the struc

Stefan Bauer

An odd Seiberg-Witten invariant imposes bounds on the signature of a closed, almost complex 4-manifold with vanishing first Chern class. This applies in particular to symplectic 4-manifolds of Kodaira dimension zero.

Eric Mourre

In this article an interpretation and a proof of some classical \\theorems in analysis on the integration of analytic vectors fields are derived from the algebraic method of realization of bialgebras which are constructed with the data of a linear application from a coalgebra into the algebra of right (or left) invariant operators on an approximated coalgebr

Mikko Salo, Jenn-Nan Wang

We consider the inverse conductivity problem of identifying embedded objects in unbounded domains. The main tool is a set of special solutions to the Schroedinger equation, the complex spherical waves, which are constructed by a Carleman estimate. Using these solutions we can treat the inverse problem in the unbounded domain like in the bounded case, and it

V. V. Peller, V. I. Vasyunin

For a rational matrix function $Φ$ with poles outside the unit circle, we estimate the degree of the unique superoptimal approximation $\AΦ$ by matrix functions analytic in the unit disk. We obtain sharp estimates in the case of $2\times2$ matrix functions. It turns out that ``generically'' $°\AΦ\le\degΦ-2$. We prove that for an arbitrary $2\times2$

Florin F. Nichita, Deepak Parashar

For any algebra two families of coloured Yang-Baxter operators are constructed, thus producing solutions to the two-parameter quantum Yang-Baxter equation. An open problem about a system of functional equations is stated. The matrix forms of these operators for two and three dimensional algebras are computed. A FRT bialgebra for one of these families is pres

Donatella Donatelli, Corrado Lattanzio

This paper deals with the rigorous study of the diffusive stress relaxation in the multidimensional system arising in the mathematical modeling of viscoelastic materials. The control of an appropriate high order energy shall lead to the proof of that limit in Sobolev space. It is shown also as the same result can be obtained in terms of relative modulate ene

Min Chen, Olivier Goubet

In this paper, we study various dissipative mechanics associated with the Boussinesq systems which model two-dimensional small amplitude long wavelength water waves. We will show that the decay rate for the damped one-directional model equations, such as the KdV and BBM equations, holds for some of the damped Boussinesq systems which model two-directional wa

Claudia Garetto, Guenther Hoermann, Michael Oberguggenberger

In this article, a theory of generalized oscillatory integrals (OIs) is developed whose phase functions as well as amplitudes may be generalized functions of Colombeau type. Based on this, generalized Fourier integral operators (FIOs) acting on Colombeau algebras are defined. This is motivated by the need of a general framework for partial differential opera

Eric Olivier, Alain Thomas

We study the selfsimilarity and the Gibbs properties of several measures defined on the product space $Ω\_r:=\{0,1,...,\break r-1\}^{\mathbb N}$. This space can be identified with the interval $[0,1]$ by means of the numeration in base $r$. The last section is devoted to the Bernoulli convolution in base $β={1+\sqrt5\over2}$, called the Erd\H os measure, and

Eric Olivier, Alain Thomas

We consider the infinite sequences $(A\_n)\_{n\in\NN}$ of $2\times2$ matrices with nonnegative entries, where the $A\_n$ are taken in a finite set of matrices. Given a vector $V=\pmatrix{v\_1\cr v\_2}$ with $v\_1,v\_2>0$, we give a necessary and sufficient condition for $\displaystyle{A\_1... A\_nV\over|| A\_1... A\_nV||}$ to converge uniformly. In applicati

Serge Bouc

In this note I describe the structure of the biset functor $B^\times$ sending a $p$-group $P$ to the group of units of its Burnside ring $B(P)$. In particular, I show that $B^\times$ is a rational biset functor. It follows that if $P$ is a $p$-group, the structure of $B^\times(P)$ can be read from a genetic basis of $P$: the group $B^\times(P)$ is an element

Donatella Donatelli, Pierangelo Marcati

In this paper we study how to approximate the Leray weak solutions of the incompressible Navier Stokes equation. In particular we describe an hyperbolic version of the so called artificial compressibility method investigated by J.L.Lions and Temam. By exploiting the wave equation structure of the pressure of the approximating system we achieve the convergenc

Subhash J Bhatt

Given an $m$-tempered strongly continuous action $α$ of $\R$ by continuous $^{*}$-automorphisms of a Frechet $^{*}$-algebra $A$, it is shown that the enveloping \hbox{$σ$-$C^{*}$-algebra} $E(S(\R,A^{\infty},α))$ of the smooth Schwartz crossed product $S(\R,A^{\infty},α)$ of the Frechet algebra $A^{\infty}$ of $C^{\infty}$-elements of $A$ is isomorphic to the

A. E. Mironov

We associate a periodic two-dimensional Schrodinger operator to every Lagrangian torus in CP^2 and define the spectral curve of a torus as the Floquet spectrum of this operator on the zero energy level. In this event minimal Lagrangian tori correspond to potential operators. We show that Novikov-Veselov hierarchy of equations induces integrable deformations

Fernando Chamizo

We consider the analog of visibility problems in hyperbolic plane (represented by Poincaré half-plane model H), replacing the standard lattice $Z\times Z$ by the orbit $z=i$ under the full modular group $z$. We prove a visibility criterion and study orchard problem and the cardinality of visible points in large circles

Johan Andersson, Jan Snellman

We study the number of $k \times r$ plane partitions, weighted on the sum of the first row. Using Erhart reciprocity, we prove an identity for the generating function. For the special case $k=1$ this result follows from the classical theory of partitions, and for $k=2$ it was proved in Andersson-Bhowmik with another method. We give an explicit formula in ter

A. D. Ioffe

If $F$ is a set-valued mapping from $\R^n$ into $\R^m$ with closed graph, then $y\in \R^m$ is a critical value of $F$ if for some $x$ with $y\in F(x)$, $F$ is not metrically regular at $(x,y)$. We prove that the set of critical values of a set-valued mapping whose graph is a definable (tame) set in an $o$-minimal structure containing additions and multiplica

Pravir Dutt, Satyendra Tomar

In this paper we show that the h-p spectral element method developed in \cite{pdstrk1,tomar-01,tomar-dutt-kumar-02} applies to elliptic problems in curvilinear polygons with mixed Neumann and Dirichlet boundary conditions provided that the Babuska--Brezzi inf--sup conditions are satisfied.

Biswaranjan Behera, Shobha Madan

We study the action of translation operators on wavelet subspaces. This action gives rise to an equivalence relation on the set of all wavelets. We show by explicit construction that each of the associated equivalence classes is non-empty.

Omran Kouba

In this note we consider inequalities involving the error function $ϕ$. Our methodes give new proofs of some known inequalities of Komatsu, and of Szarek and Werner, and also produce two families of inequalities that give upper and lower bounds for $ϕ$. Moreover the continued fractions expansion of $ϕ$ is obtained.

Siddhartha Gadgil, Dishant Pancholi

We show that, for a closed non-orientable surface $F$, an automorphism of $H_1(F,\Z)$ is induced by a homeomorphism of $F$ if and only if it preserves the (mod 2) intersection pairing. We shall also prove the corresponding result for punctured surfaces.

Michael Joswig, Nikolaus Witte

Regular triangulations of products of lattice polytopes are constructed with the additional property that the dual graphs of the triangulations are bipartite. The (weighted) size difference of this bipartition is a lower bound for the number of real roots of certain sparse polynomial systems by recent results of Soprunova and Sottile [Adv. Math. 204(1):116-1

Philippe Ellia, Davide Franco, Laurent Gruson

We work over an algebraically closed field of arbitrary characteristic. Ellingsrud-Peskine proved that smooth surfaces in P^4 are subject to strong limitations. Their whole argument is derived from the fact that the sectional genus of surfaces of degree d lying on a hypersurface of degree s varies in an interval of length \frac{d(s-1)^2}{2s}. The aim of the

Claus Gerhardt

We consider spacetimes with compact Cauchy hypersurfaces and with Ricci tensor bounded from below on the set of timelike unit vectors, and prove that the results known for spacetimes satisfying the timelike convergence condition, namely, foliation by CMC hypersurfaces, are also valid in the present situation, if corresponding further assumptions are satisfie

John M. Lee

The main purpose of this monograph is to give an elementary and self-contained account of the existence of asymptotically hyperbolic Einstein metrics with prescribed conformal infinities sufficiently close to that of a given asymptotically hyperbolic Einstein metric with nonpositive curvature. The proof is based on an elementary derivation of sharp Fredholm

Massimo Giovannini

A class of five-dimensional warped solutions is presented. The geometry is everywhere regular and tends to five-dimensional anti-de Sitter space for large absolute values of the bulk coordinate. The physical features of the solutions change depending on the value of an integer parameter. In particular, a set of solutions describes generalized gravitating kin

Herbert W. Hamber, Ruth M. Williams

Corrections are computed to the classical static isotropic solution of general relativity, arising from non-perturbative quantum gravity effects. A slow rise of the effective gravitational coupling with distance is shown to involve a genuinely non-perturbative scale, closely connected with the gravitational vacuum condensate, and thereby, it is argued, relat

Minoru Eto, Youichi Isozumi, Muneto Nitta, Keisuke Ohashi

We review our recent works on solitons in U(Nc) gauge theories with Nf (>Nc) Higgs fields in the fundamental representation, which possess eight supercharges. The moduli matrix is proposed as a crucial tool to exhaust all BPS solutions, and to characterize all possible moduli parameters. Since vacua are in the Higgs phase, we find domain walls (kinks) and vo

Massimo Bianchi, Alessio V. Santini

We derive compact expressions for one-loop scattering amplitudes of four open-string vector bosons around supersymmetric configurations with intersecting or magnetized D-branes on toroidal orbifolds. We check the validity of our formulae against the structure of their singularities and their behaviour under modular transformations to the transverse channel,

S. Mert Aybat, Lance J. Dixon, George Sterman

We extend the resummation of dimensionally-regulated amplitudes to next-to-next-to-leading poles. This requires the calculation of two-loop anomalous dimension matrices for color mixing through soft gluon exchange. Remarkably, we find that they are proportional to the corresponding one-loop matrices. Using the color generator notation, we reproduce the two-l

Bernd A. Kniehl, Gustav Kramer

In Phys. Rev. D 58, 014014 (1998) and 71, 094013 (2005), we determined non-perturbative D^0, D^+, D^{*+}, D_s^+, and Lambda_c^+ fragmentation functions, both at leading and next-to-leading order in the MS-bar factorization scheme, by fitting e^+e^- data taken by the OPAL Collaboration at CERN LEP1. The starting points for the evolution in the factorization s

Zurab Berezhiani, Fabrizio Nesti, Luigi Pilo

We show that in supersymmetric grand unified theories new effective D=4 and D=5 operators for proton decay are induced by soft SUSY-breaking terms, when heavy GUT gauge bosons are integrated out, in addition to the standard D=6 ones. As a result, the proton lifetime in gauge mediated channels can be enhanced or even suppressed depending on the size of the he

I. Bierenbaum, J. Blümlein, S. Klein

We calculate massive 5-propagator 2-loop integrals for operator matrix elements in the light-cone expansion, using Mellin-Barnes techniques and representations through generalized hypergeometric functions.

A. Peshier

It was argued recently that loop corrections to tree-level amplitudes are essential in the discussion of the collisional energy loss of energetic partons in the hot quark gluon plasma: Instead of $dE_{\rm coll}^B/dx \sim α^2 T^2 \ln(ET/m_D^2)$, as first derived by Bjorken (assuming a constant $α$), the mean energy loss actually behaves as $dE_{\rm coll}/dx \

Christian W. Bauer, Matthew D. Schwartz

A procedure is developed for using Soft Collinear Effective Theory (SCET) to generate fully exclusive events, which can then be compared to data from collider experiments. We show that SCET smoothly interpolates between QCD for hard emissions, and the parton shower for soft emissions, while resumming all large logarithms. In SCET, logarithms are resummed usi

F. M. L. de Almeida, Y. A. Coutinho, J. A. Martins Simões, A. J. Ramalho

There is a recent proposal of identifying the Higgs particle of the Standard Model as a pseudo Nambu-Goldstone boson. This new broken symmetry introduces new particles and new interactions. Among these new interactions a central role to get a new physics is played by the new neutral gauge boson. We have studied the new neutral currents in the Littlest Higgs

The BABAR Collaboration, B. Aubert

Using 232 fb-1 of data collected by the BABAR detector, the Xic'+ and Xic'0 baryons are reconstructed through the decays: Xic'+ -> Xic+ gamma and Xic'0 -> Xic0 gamma, where Xic+ -> Xi- pi+ pi+ and Xic0 -> Xi- pi+. By measuring the efficiency-corrected yields in different intervals of the center-of-mass momentum, the production rates from B de

The BABAR Collaboration, B. Aubert

Based on the measured four-dimensional rate for $D_{s}^+ to ϕe^+ ν_e$ decays, we have determined the ratios of the three hadronic form factors, r_V=V(0)/A_1(0)= 1.636 \pm 0.067 \pm 0.038 and r_2=A_2(0)/A_1(0)= 0.705 \pm 0.056 \pm 0.029, using a simple pole ansatz for the $q^2$ dependence, with fixed values of the pole masses for both the vector and axial for

The BABAR Collaboration, B. Aubert

The decay width and the mass of the D_s1(2536) have been measured via the decay channel D_s1 -> D*+K_S using 232 fb^-1 of data collected with the BABAR detector at the PEP-II asymmetric-energy e+e- storage ring. The result for the decay width is (1.03 +- 0.05 +- 0.12) MeV/c^2, with the first error denoting the statistical uncertainty and the second one the s

The BABAR Collaboration, B. Aubert

A study of exclusive production of the $D \bar D$ system through initial-state r adiation is performed in a search for charmonium states, where $D=D^0$ or $D^+$. The $D^0$ mesons are reconstructed in the $D^0 \to K^- π^+$, $D^0 \to K^- π^+ π^0$, and $D^0 \to K^- π^+ π^+ π^-$ decay modes. The $D^+$ is reconstructed through the $D^+ \to K^- π^+ π^+$ decay mode

The BABAR Collaboration, B. Aubert

We perform the first three-dimensional measurement of the amplitudes of $B\toψ{(2S)}K^*$ and $B\toχ_{c1}K^*$ decays and update our previous measurement for $B\to{J\mskip -3mu/\mskip -2muψ\mskip 2mu}K^*$. We use a data sample collected with the {\slshape BABAR} detector at the PEP-II storage ring, representing 232 million produced $B{\kern 0.18em\bar{\kern -0

G. Huang, CLEO Collaboration

Knowledge of the Bs decay fraction of the Y(5S) resonance, fs, is important for Bs meson studies at the Y(5S) energy. Using data collected by the CLEO III detector at CESR consisting of 0.423 1/fb on the Y(5S) resonance, 6.34 1/fb on the Y(4S) and 2.32 1/fb in the continuum below the Y(4S), we measure B(Y(5S)-> phi X)=(13.2+/- 0.7 ^{+2.2}_{-1.4})% and B(Y (4

N. Adam, CLEO Collaboration

We report preliminary measurements of absolute hadronic branching fractions of Ds mesons determined using a double tag technique. These measurements are from 195 pb^{-1} of e+e- collisions recorded at center of mass energies near 4.17 GeV with the CLEO-c detector at CESR. We obtain absolute branching fractions for Ds+ decays to KS0 K+, K- K+ pi+, K- K+ pi+ p

The BABAR Collaboration, B. Aubert

We present a preliminary measurement of the q2 dependence of the D0 --> K- e+ nu_e decay rate. This rate is proportional to the hadronic form factor squared, specified by a single parameter. This is either the mass in the simple pole ansatz m_pole = (1.854 +- 0.016 +- 0.020) GeV/c2 or the scale in the modified pole ansatz alpha_pole = 0.43 +- 0.03 +- 0.04. T

The BABAR Collaboration, B. Aubert

We present a combined measurement of the Cabibbo-Kobayashi-Maskawa matrix element $|V_{cb}|$ and of the parameters $ρ^2$, $R_1$, and $R_2$, which fully characterize the form factors of the $B^0 \to D^{*-}\ell^{+}ν_\ell$ decay in the framework of HQET, based on a sample of about 52,800 $B^0 \to D^{*-}\ell^{+}ν_\ell$ decays recorded by the BABAR detector. The

S. Dytman, CLEO Collaboration

We present a measurement of the branching fraction for the doubly-Cabibbo-suppressed decay D+ to K+ pi0, using 281 pb-1 of data accumulated with the CLEO-c detector on the psi(3770) resonance. We find B(D+ to K+ pi0) = (2.25 +- 0.36 +- 0.15 +- 0.07) times 10^{-4}, where the first uncertainty is statistical, the second is systematic, and the last error is due

Q. He, CLEO Collaboration

We present preliminary measurements of D to K^0_L pi and D to K^0_S pi branching fractions using 281 pb^{-1} of psi(3770) data at the CLEO-c experiment. We find that BF(D^0 to KS pi^0) is larger than BF(D^0 to KL pi^0), with an asymmetry of R(D^0) = 0.122 +- 0.024 +- 0.030. For BF(D^+ to KS pi^+) and BF(D^+ to KL pi^+), we observe no measureable difference;

Wontae Kim, Edwin J. Son, Myung Seok Yoon

Motivated by previous works, we study semi-classical cosmological solutions and the wave function of the Wheeler-DeWitt equation in the Bose-Parker-Peleg model. We obtain the wave function of the universe satisfying the suitable boundary condition of the redefined fields, which has not been considered in previous works. For some limiting cases, the Wheeler-D

F. Rahaman, M. Kalam, R. Mondal, B. Raychaudhuri

In this article, we discuss the space-time of a global monopole field as a candidate for galactic dark matter in the context of scalar tensor theory.

S. R. Berbena, A. V. Berrocal, J. Socorro, Luis O. Pimentel

The dynamical evolution of the scale factor of FRW cosmological model is presented, when the equation of state of the material content assume the form $\rm p=γρ$, $\rm γ=constant$, including the cosmological term. We use the WKB approximation and the relation with the Einstein-Hamilton-Jacobi equation to obtain the exact solutions.

Vladimir Vovk

We start from a simple asymptotic result for the problem of on-line regression with the quadratic loss function: the class of continuous limited-memory prediction strategies admits a "leading prediction strategy", which not only asymptotically performs at least as well as any continuous limited-memory strategy but also satisfies the property that the

R. Ahlswede, H. Aydinian, L. H. Khachatrian, L. M. G. M. Tolhuizen

We consider codes over the alphabet Q={0,1,..,q-1}intended for the control of unidirectional errors of level l. That is, the transmission channel is such that the received word cannot contain both a component larger than the transmitted one and a component smaller than the transmitted one. Moreover, the absolute value of the difference between a transmitted

Sergey V. Zykov

Human resources management software is having a wide audience at present. However, no truly integrate solution has been proposed yet to improve the systems concerned. Approaches to extra data collection for appraisal decision-making are considered on the concept modeling theoretical basis. Current technologies in state-of-the-art HR management software are c

Sergey V. Zykov

Enterprise resource planning (ERP) systems enjoy an increasingly wide coverage. However, no truly integrate solution has been proposed as yet. ERP classification is given. Recent trends in commercial systems are analyzed on the basis of human resources (HR) management software. An innovative "straight through" design and implementation process of an

Sergey V. Zykov

Integrated approach to enterprise resource planning (ERP) software design and implementation can significantly improve the entire corporate information infrastructure and it helps to benefit from power of Internet services. The approach proposed provides for corporate Web portal integrity, consistency, urgency and front-end data processing. Human resources (

Sergey V. Zykov

Web-portal based approach can significantly improve the entire corporate information infrastructure. The approach proposed provides for rapid and accurate front-end integration of heterogeneous corporate applications including enterprise resource planning (ERP) systems. Human resources ERP component and multimedia data warehouse implementations are discussed

Sergey V. Zykov

Enterprise content management is an urgent issue of current scientific and practical activities in software design and implementation. However, papers known as yet give insufficient coverage of theoretical background of the software in question. The paper gives an attempt of building a state-based model of content management. In accordance with the theoretic

Sergey V. Zykov

Portal technology can significantly improve the entire corporate information infrastructure. The approach proposed is based on rigorous and consistent (meta)data model and provides for efficient and accurate front-end integration of heterogeneous corporate applications including enterprise resource planning (ERP) systems, multimedia data warehouses and propr

Sergey V. Zykov

The paper describes problem-oriented approach to software development. The approach is a part of the original integrated methodology of enterprise Internet-based software design and implementation. All aspects of software development, from theory to implementation, are covered.

Sergey V. Zykov

The paper deals with problem-oriented visual information system (IS) engineering for enterprise Internet-based applications, which is a vital part of the whole development process. The suggested approach is based on semantic network theory and a novel ConceptModeller CASE tool.

Sergey V. Zykov

The paper considers enterprise content management (ECM) issues in global heterogeneous distributed computational environment. Present-day enterprises have accumulated a huge data burden. Manipulating with such a bulk becomes an essential problem, particularly due to its global distribution, heterogeneous and weak-structured character. The conceptual approach

Sergey V. Zykov, Gleb G. Pogodayev

Document management software systems are having a wide audience at present. However, groupware as a term has a wide variety of possible definitions. Groupware classification attempt is made in this paper. Possible approaches to groupware are considered including document management, document control and mailing systems. Lattice theory and concept modelling a

Peter D. Turney

We present an unsupervised learning algorithm that mines large text corpora for patterns that express implicit semantic relations. For a given input word pair X:Y with some unspecified semantic relations, the corresponding output list of patterns <P1,...,Pm> is ranked according to how well each pattern Pi expresses the relations between X and Y. For example,

Sergey V. Zykov

The paper considers software development issues for large-scale enterprise information systems (IS) with databases (DB) in global heterogeneous distributed computational environment. Due to high IT development rates, the present-day society has accumulated and rapidly increases an extremely huge data burden. Manipulating with such huge data arrays becomes an

R. Vasic, H. Zhou, E. Jobiliong, C. R. Wiebe

The magnetic field dependent phase diagram of the ferroelectric material ${\rm Ho}_{1-x}Y_{x}MnO_{3}$ has been investigated for x = 0, 0.6, and 0.8 for fields directed along both the ab in-plane and c-axis basal plane directions. Dielectric measurements are used to map out the re-entrant temperature-magnetic field phase transitions which involve in-plane Mn

Jing-qiao Zhang, Sergey Vitkalov, A. A. Bykov, A. K. Kalagin

The effect of a DC electric field on the longitudinal resistance of highly mobile two dimensional electrons in heavily doped GaAs quantum wells is studied at different magnetic fields and temperatures. Strong suppression of the resistance by the electric field is observed in magnetic fields at which the Landau quantization of electron motion occurs. The phen

Z. Q. Yuan, C. L. Yang, R. R. Du, L. N. Pfeiffer

The microwave (MW) photoresistance has been measured on a high-mobility two-dimensional electron gas patterned with a shallow triangular antidot lattice, where both the MW-induced resistance oscillations (MIRO) and magnetoplasmon (MP) resonance are observed superposing on sharp commensurate geometrical resonance (GR). Analysis shows that the MIRO, MP, and GR

R. C. Ashoori

This thesis describes capacitance and tunneling experiments performed on two-dimensional electron gas (2DEG) and quantum dot systems. It develops a system of equations that allow determination, by means of capacitance measurements, of the electronic density of states, the electron density, and the chemical potential in a 2DEG. The thesis describes the use of

Hans Huebl, Andre R. Stegner, Martin Stutzmann, Martin S. Brandt

The hyperfine interaction of phosphorus donors in fully strained Si thin films grown on virtual Si$_{1-x}$Ge$_x$ substrates with $x\leq 0.3$ is determined via electrically detected magnetic resonance. For highly strained epilayers, hyperfine interactions as low as 0.8 mT are observed, significantly below the limit predicted by valley repopulation. Within a G

M. Centelles, P. Leboeuf, A. G. Monastra, J. Roccia

Semiclassical theories like the Thomas-Fermi and Wigner-Kirkwood methods give a good description of the smooth average part of the total energy of a Fermi gas in some external potential when the chemical potential is varied. However, in systems with a fixed number of particles N, these methods overbind the actual average of the quantum energy as N is varied.

Alexander J. Wagner, Sylvio May

We present theoretical work in which the degree of electrostatic coupling across a charged lipid bilayer in aqueous solution is analyzed on the basis of nonlinear Poisson-Boltzmann theory. In particular, we consider the electrostatic interaction of a single, large macroion with the two apposed leaflets of an oppositely charged lipid bilayer where the macroio

G. Cao, S. Parkin, P. Schlottmann

A structural and thermodynamic study of the newly synthesized single crystal Sr5Rh4O12 is reported. Sr5Rh4O12 consists of a triangular lattice of spin chains running along the c-axis. It is antiferromagnetically ordered below 23 K with the intrachain and interchain coupling being ferromagnetic (FM) and antiferromagnetic (AFM), respectively. There is strong e

O. S. Barisic, S. Barisic

The translationally invariant diagrammatic quantum perturbation theory (TPT) is applied to the polaron problem on the 1D lattice, modeled through the Holstein Hamiltonian with the phonon frequency omega0, the electron hopping t and the electron-phonon coupling constant g. The self-energy diagrams of the fourth-order in g are calculated exactly for an intermi

C. Lobo, A. Recati, S. Giorgini, S. Stringari

We study the Fermi gas at unitarity and at T=0 by assuming that, at high polarizations, it is a normal Fermi liquid composed of weakly interacting quasiparticles associated with the minority spin atoms. With a quantum Monte Carlo approach we calculate their effective mass and binding energy, as well as the full equation of state of the normal phase as a func

Sergio De Nicola, Boris A. Malomed, Renato Fedele

We demonstrate that a tight transverse trap with the local frequency, $% ω_{\perp}$, gradually varying in the longitudinal direction ($x$) induces an effective potential for one-dimensional solitons in a self-attractive Bose-Einstein condensate. An analytical approximation for this potential is derived by means of a variational method. In the lowest approxim

M. Letz, L. Parthier

Charge centers in ionic crystals provide a channel for elementary interaction between electromagnetic radiation and the lattice. We calculate the electronic ground state energies which are needed to create a charge center -- namely a $F$- and a $H$-center. In well agreement with common understanding the $F$-center results in being accompanied by a small latt

Afif Siddiki, Stefan Kraus, Rolf R. Gerhardts

We report on theoretical and experimental investigations of a novel hysteresis effect that has been observed on the magnetoresistance of quantum-Hall bilayer systems. Extending to these system a recent approach, based on the Thomas-Fermi-Poisson nonlinear screening theory and a local conductivity model, we are able to explain the hysteresis as being due to s

Xavier Vidal, Pablo Balenzuela, Javier M. Buldú, Jordi Martorell

Two trains of light pulses at periods that are equally shifted from the harmonics of a missing fundamental, are combined in a nonlinear crystal. As a result of a noncollinear phase matched second order nonlinear generation, a new train of pulses is obtained. When the temporal width of the input pulses is large, the frequency of the resulting pulse train foll

Laura Urba, Emil Lundh, Anders Rosengren

The extended Bose-Hubbard model in a quadratic trap potential is studied using a finite-size density-matrix renormalization group method (DMRG). We compute the boson density profiles, the local compressibility and the hopping correlation functions. We observed the phase separation induced by the trap in all the quantities studied and conclude that the local

S. Pilati, K. Sakkos, J. Boronat, J. Casulleras

By using exact Path Integral Monte Carlo methods we calculate the equation of state of an interacting Bose gas as a function of temperature both below and above the superfluid transition. The universal character of the equation of state for dilute systems and low temperatures is investigated by modeling the interatomic interactions using different repulsive

K. Karkkainen, M. Borgh, M. Manninen, S. M. Reimann

Artificially confined, small quantum systems show a high potential for employing quantum physics in technology. Ultra-cold atom gases have opened an exciting laboratory in which to explore many-particle systems that are not accessible in conventional atomic or solid state physics. It appears promising that optical trapping of cold bosonic or fermionic atoms

Chisa Hotta, Nobuo Furukawa, Akihiko Nakagawa, Kenn Kubo

The strong coupling phase diagram of the spinless fermions on the anisotropic triangular lattice at half-filling is presented. The geometry of inter-site Coulomb interactions rules the phase diagram. Unconventional charge ordered phases are detected which are the recently reported pinball liquid and the striped chains. Both are induced by the quantum dynamic

Panayotis Spathis, Marcin Konczykowski, Cornelis J. van der Beek, Piotr Gierlowski

By measuring the Josephson Plasma Resonance, we have probed the influence of an in-plane magnetic field on the pancake vortex correlations along the c-axis in heavily underdoped Bi2Sr2CaCu2O8+d (Tc = 72.4 +/- 0.6 K) single crystals both in the vortex liquid and in the vortex solid phase. Whereas the in-plane field enhances the interlayer phase coherence in t

Denis Andrienko, Valentina Marcon, Kurt Kremer

Using atomistic molecular dynamics simulations we study solid and liquid crystalline columnar discotic phases formed by alkyl-substituted hexabenzocoronene mesogens. Correlations between the molecular structure, packing, and dynamical properties of these materials are established.

Takashi Uchida, Yoshiro Kakehashi

The relative stability among the multiple spin density wave (MSDW) states in fcc transition metals has been investigated on the basis of a Ginzburg-Landau type of free energy with terms up to the fourth order in magnetic moments. Obtained magnetic phase diagrams in the space of expansion coefficients indicate the possibility of various 3Q MSDW states in fcc

D. A. Head

Motivated by the buckling of glassy crusts formed on evaporating droplets of polymer and colloid solutions, we numerically model the deformation and buckling of spherical elastic caps controlled by varying the volume between the shell and the substrate. This volume constraint mimics the incompressibility of the unevaporated solvent. Discontinuous buckling is

H. Hori, Y. Yamamoto, S. Sonoda

The high TC ferromagnetism in (Ga,Mn)N were observed and almost all results are approximately similar to the experimental results in (Ga,Mn)As except the value of TC. Though all standard experiments on magnetism clearly support the results, the value is unexpectedly high. This work present and discuss the possibility of high TC ferromagnetism, after brief re

N. Paris, K. Bouadim, F. Hebert, G. G. Batrouni

We study the transitions from band insulator to metal to Mott insulator in the ionic Hubbard model on a two dimensional square lattice using determinant Quantum Monte Carlo. Evaluation of the temperature dependence of the conductivity demonstrates that the metallic region extends for a finite range of interaction values. The Mott phase at strong coupling is

Steven V. W. Beckwith, Massimo Stiavelli, Anton M. Koekemoer, John A. R. Caldwell

This paper presents the Hubble Ultra Deep Field (HUDF), a one million second exposure of an 11 square minute-of-arc region in the southern sky with the Hubble Space Telescope. The exposure time was divided among four filters, F435W (B435), F606W (V606), F775W (i775), and F850LP (z850), to give approximately uniform limiting magnitudes mAB~29 for point source

R. Cannon, M. Drinkwater, A. Edge, D. Eisenstein

We present a spectroscopic survey of almost 15,000 candidate intermediate-redshift Luminous Red Galaxies (LRGs) brighter than i=19.8, observed with 2dF on the Anglo-Australian Telescope. The targets were selected photometrically from the Sloan Digital Sky Survey (SDSS) and lie along two narrow equatorial strips covering 180 sq deg. Reliable redshifts were ob

D. A. Wake, R. C. Nichol, D. J. Eisenstein, J. Loveday

We present new measurements of the luminosity function (LF) of Luminous Red Galaxies (LRGs) from the Sloan Digital Sky Survey (SDSS) and the 2dF-SDSS LRG and Quasar (2SLAQ) survey. We have carefully quantified, and corrected for, uncertainties in the K and evolutionary corrections, differences in the colour selection methods, and the effects of photometric e

H. Schatz

The importance of mass measurements for astrophysical capture processes in general, and for the rp-process in X-ray bursts in particular is discussed. A review of the current uncertainties in the effective lifetimes of the major waiting points 64Ge, 68Se, and 72Kr demonstrates that despite of recent measurements uncertainties are still significant. It is fou

Rupal Mittal, Richard Porcas, Olaf Wucknitz

We address the issue of anomalous image flux ratios seen in the double-image gravitational lens JVAS B0218+357. From the multi-frequency observations presented in a recent study (Mittal et al. 2006) and several previous observations made by other authors, the anomaly is well-established in that the image flux-density ratio (A/B) decreases from 3.9 to 2.0 ove

Glenn E. Ciolek, Shantanu Basu

We formulate the problem of the formation and collapse of nonaxisymmetric protostellar cores in weakly ionized, self-gravitating, magnetic molecular clouds. In our formulation, molecular clouds are approximated as isothermal, thin (but with finite thickness) sheets. We present the governing dynamical equations for the multifluid system of neutral gas and ion

Jodi Cooley

In the last year many collaborations searching for the dark matter constituent have published results from their experiments. Here I give a review of direct detection searches reported by the DAMA, KIMS, CDMS-II, EDELWEISS-I, CRESST-II and ZEPLIN-I collaborations. I also outline the future plans of each collaboration as well as the XENON10 collaboration.

S. Immler, P. J. Brown, P. Milne, L. -S. The

We present a study of the early (days to weeks) X-ray and UV properties of eight Type Ia supernovae (SNe Ia) which have been extensively observed with the X-Ray Telescope (XRT) and UV/Optical Telescope (UVOT) onboard Swift, ranging from 5-132 days after the outburst. SN 2005ke is tentatively detected (at a 3-3.6 sigma level of significance) in X-rays based o

L. Derome

A precise evaluation of the secondary particle production and propagation in the atmosphere is very important for the atmospheric neutrino oscillation studies. The issue is addressed with the extension of a previously developed full 3-Dimensional Monte-Carlo simulation of particle generation and transport in the atmosphere, to compute the flux of secondary p