May 2003 arXiv papers — page 7

Zhi-Wei Sun

Zero-sum problems for abelian groups and covers of the integers by residue classes, are two different active topics initiated by P. Erdos more than 40 years ago and investigated by many researchers separately since then. In an earlier announcement [Electron. Res. Announc. Amer. Math. Soc. 9(2003), 51-60], the author claimed some surprising connections among

James L. Crooks, James O. Dunn, Paul H. Frampton, Heather R. Norton

We discuss a degeneracy between the geometry of the universe and the dark energy equation of state $w_{\rm X}$ which exists in the power spectrum of the cosmic microwave background. In particular, for the case with $w_{\rm X} < -1$, this degeneracy has interesting implications to a lower bound on $w_{\rm X}$ from observations. It is also discussed how this d

Arun Paramekanti, Mohit Randeria, Nandini Trivedi

We use a variational approach to gain insight into the strongly correlated d-wave superconducting state of the high Tc cuprates at T=0. We show that strong correlations lead to qualitatively different trends in pairing and phase coherence: the pairing scale decreases monotonically with hole doping while the SC order parameter shows a non-monotonic dome. We o

M. G. Santos, A. Cooray, Z. Haiman, L. Knox

We study contributions from inhomogeneous (patchy) reionization to arcminute scale ($1000 < \ell < 10,000$) cosmic microwave background (CMB) anisotropies. We show that inhomogeneities in the ionization fraction, rather than in the mean density, dominate both the temperature and the polarization power spectra. Depending on the ionization history and the clus

Jacek Pawelczyk, Harold Steinacker

We analyze the dynamics of D2-branes on SU(2) within a recently proposed matrix model, which works for finite radius of SU(2). The spectrum of single-brane excitations turns out to be free of tachyonic modes. It is similar to the spectrum found using DBI and CFT calculations, however the triplet of rotational zero modes is missing. This is attributed to a na

Mark A. Walton, Jian-Ge Zhou

In the semi-light cone gauge $g_{ab}=e^{2ϕ}δ_{ab}$, $\barγ^+θ=0$, we evaluate the $ϕ$-dependent effective action for the pp-wave Green-Schwarz (GS) superstring in both harmonic and group coordinates. When we compute the fermionic $ϕ$-dependent effective action in harmonic coordinates, we find a new triangular one-loop Feynman diagram. We show that the bosoni

Thomas Gregoire, David R. Smith, Jay G. Wacker

We study precision electroweak constraints on the close cousin of the Littlest Higgs, the SU(6)/Sp(6) model. We identify a near-oblique limit in which the heavy W&#39; and B&#39; decouple from the light fermions, and then calculate oblique corrections, including one-loop contributions from the extended top sector and the two Higgs doublets. We find regions o

Marco Matone, Luca Mazzucato

In the framework of the matrix model/gauge theory correspondence, we consider supersymmetric U(N) gauge theory with $U(1)^N$ symmetry breaking pattern. Due to the presence of the Veneziano--Yankielowicz effective superpotential, in order to satisfy the $F$--term condition $\sum_iS_i=0$, we are forced to introduce additional terms in the free energy of the co

Musongela Lubo

We rederive the thermodynamical properties of a non interacting gas in the presence of a minimal uncertainty in length. Apart from the phase space measure which is modified due to a change of the Heisenberg uncertainty relations, the presence of an ultraviolet cut-off plays a tremendous role. The theory admits an intrinsic temperature above which the fermion

F. Matera

An effective interaction between fermions in a Bose-Fermi mixture is derived. It is induced by density fluctuations of the bosonic background. The contributions from states containing both one and two virtual phonons are taken into account self-consistently. The time dependence of the effective interaction has been removed by assuming that the velocity of th

S. Moukouri

The Kato-Bloch perturbation formalism is used to present a density-matrix renormalization-group (DMRG) method for strongly anisotropic two-dimensional systems. This method is used to study Heisenberg chains weakly coupled by the transverse couplings $J_{\perp}$ and $J_{d}$ (along the diagonals). An extensive comparison of the renormalization group and quantu

Askin Ankay, Oktay H. Guseinov, Sevinc O. Tagieva

In different directions of the Galaxy the Galactic background radio radiation and radiation of complex star formation regions which include large number of OB associations have different influences on radio pulsar (PSR) and supernova remnant (SNR) searches. In this work we analyse the effects of these background radiations on the observations of PSRs at 1400

Alberto Montesi, Alejandro A. Pena, Matteo Pasquali

Attractive emulsions near the colloidal glass transition are investigated by rheometry and optical microscopy under shear. We find that (a) the apparent viscosity ηdrops with increasing shear rate, then remains approximately constant in a range of shear rates, then continues to decay; (b) the first normal stress difference N1 transitions sharply from nearly

Marianna Larosa, Gianfranco Pradisi

We study deformations of $Z_2 \times Z_2$ (shift-)orientifolds in four dimensions in the presence of both uniform Abelian internal magnetic fields and quantized NS-NS $B_{ab}$ backgrounds, that are shown to be equivalent to asymmetric shift-orbifold projections. These models are related by $T$-duality to orientifolds with $D$-branes intersecting at angles. A

Stefan Antusch, Joern Kersten, Manfred Lindner, Michael Ratz

We derive simple analytical formulae for the renormalization group running of neutrino masses, leptonic mixing angles and CP phases, which allow an easy understanding of the running. Particularly for a small angle theta_13 the expressions become very compact, even when non-vanishing CP phases are present. Using these equations we investigate: (i) the influen

Michael Mitrovski

We report preliminary results on Omega and AntiOmega production in central Pb+Pb collisions at 30, 40 and 158 AGeV and p + p interactions at 158 GeV. The midrapidity AntiOmega/Omega ratio is estimated to be 0.45 +- 0.05 and 0.41 +- 0.18 for central Pb+Pb collisions at 158 and 40 AGeV, respectively. The corresponding value for 158 GeV p+p interactions is 0.67

I. Santamaria-Holek, A. Perez-Madrid, J. M. Rubi

We present a dynamical description of slow relaxation processes based on the extension of Onsager&#39;s fluctuation theory to systems in local quasi-equilibrium. A non-Markovian Fokker-Planck equation for the conditional probability density is derived and from it we obtain the relaxation equation for the moments. We show that the fluctuation-dissipation theo

Charles Livingston

As a corollary of work of Ozsvath and Szabo [math.GT/0301149], it is shown that the classical concordance group of algebraically slice knots has an infinite cyclic summand and in particular is not a divisible group.

S. S. Murzin, A. G. M. Jansen, I. Claus

Oscillatory variations of the diagonal ($G_{xx}$) and Hall ($G_{xy}$) magnetoconductances are discussed in view of topological scaling effects giving rise to the quantum Hall effect. They occur in a field range without oscillations of the density of states due to Landau quantization, and are, therefore, totally different from the Shubnikov-de Haas oscillatio

Yu. A. Simonov

New spectral representations for f_πand chiral condensate are derived in QCD and used for calculations in the large N_c limit. Both quantities are expressed in this limit through string tension σand gluon correlation length T_g without fitting parameters. As a result one obtains <\bar q q> = - N_cσ^2 T_g a_1, f_π=\sqrt{N_c} σT_g a_2, with a_1=0.0823, a_2=0.3

Pablo Fosalba, Enrique Gaztanaga

Models with late time cosmic acceleration, such as the Lambda-dominated CDM model, predict a freeze out for the growth of linear gravitational potential at moderate redshift z<1, what can be observed as temperature anisotropies in the CMB: the so called integrated Sachs-Wolfe (ISW) effect. We present a direct measurement of the ISW effect based on the angula

A. N. Gorban, I. V. Karlin

In this paper, explicit method of constructing approximations (the Triangle Entropy Method) is developed for nonequilibrium problems. This method enables one to treat any complicated nonlinear functionals that fit best the physics of a problem (such as, for example, rates of processes) as new independent variables. The work of the method was demonstrated on

Yong Zhang

In this paper, three methods for describing the conformal transformations of the S-matrix in quantum field theory are proposed. They are illustrated by applying the algebraic renormalization procedure to the quantum scalar field theory, defined by the LSZ reduction mechanism in the BPHZ renormalization scheme. Central results are shown to be independent of s

John Ellis, Yitzhak Frishman, Marek Karliner

Extending earlier work on strong-coupling meson-baryon scattering in QCD_2, we derive the effective meson-baryon action for any value of the coupling constant, in the large-N_c limit. Colour degrees of freedom play an important role, and we show that meson-baryon scattering can be formulated as a relativistic potential problem. We distinguish two cases that

Nobuhito Maru, Norisuke Sakai

The localization of vector multiplets is examined using the {\cal N}=1 supersymmetric U(1) gauge theory with the Fayet-Iliopoulos term coupled to charged chiral multiplets in four dimensions. The vector field becomes localized on a BPS wall connecting two different vacua that break the gauge symmetry. The vacuum expectation values of charged fields vanish (a

Yoshio Koide, Joe Sato

Within the framework of an SU(5) SUSY GUT model, a mechanism which effectively induces R-parity-violating terms below the unification energy scale M_X is proposed. The model has matter fields \bar{5}_{L(+)}+10_{L(-)} and Higgs fields H_{(-)} and \bar{H}_{(+)} in addition to the ordinary Higgs fields H_{(+)} and \bar{H}_{(-)} which contribute to the Yukawa in

A. Baran, W. Broniowski, W. Florkowski

The single-freeze-out model of hadron production is used to describe the particle ratios and the transverse-momentum spectra from RHIC. The emphasis is put on the new measurements done at the highest beam energy of 200 GeV. An overall very good agreement is found between the data and the model predictions. The data for different centrality windows are analyz

Robert Koenig, Ueli Maurer, Renato Renner

We address the question whether quantum memory is more powerful than classical memory. In particular, we consider a setting where information about a random n-bit string X is stored in r classical or quantum bits, for r<n, i.e., the stored information is bound to be only partial. Later, a randomly chosen binary question F about X is asked, which has to be an

Marcella Grasso, Michael Urban

We investigate a gas of superfluid fermionic atoms trapped in two hyperfine states by a spherical harmonic potential. We propose a new regularization method to remove the ultraviolet divergence in the Hartree-Fock-Bogoliubov equations caused by the use of a zero-range atom-atom interaction. Compared with a method used in the literature, our method is simpler

Yuri Aisaka, Yoichi Kazama

An explicit operator mapping in the form of a similarity transformation is constructed between the RNS formalism and an extension of the pure spinor formalism (to be called EPS formalism) recently proposed by the present authors. Due to the enlarged field space of the EPS formalism, where the pure spinor constraints are removed, the mapping is completely wel

F. Kazemi Tabatabaei, J. E. Amaro, J. A. Caballero

A study of the effects of meson-exchange currents and isobar configurations in $A(\vec{e},e&#39;\vec{p})B$ reactions is presented. We use a distorted wave impulse approximation (DWIA) model where final-state interactions are treated through a phenomenological optical potential. The model includes relativistic corrections in the kinematics and in the electrom

Hui Deng, Bo-Yu Hou, Kang-Jie Shi, Zhan-Ying Yang

In this paper, we explicitly construct a series of projectors on integral noncommutative orbifold $T^2/Z_4$ by extended $GHS$ constrution. They include integration of two arbitary functions with $Z_4$ symmetry. Our expressions possess manifest $Z_{4}$ symmetry. It is proved that the expression include all projectors with minimal trace and in their standard e

D. V. Shopova, T. P. Todorov

The Halperin-Lubensky-Ma (HLM) effect of a fluctuation-induced change of the order of phase transition in thin films of type I superconductors with relatively small Ginzburg-Landau number $κ$ is considered. Numerical data for the free energy, the order parameter jump, the latent heat, and the specific heat of W, Al and In are presented to reveal the influenc

Yi Ling

Recently Gambini and Pullin proposed a new consistent discrete approach to quantum gravity and applied it to cosmological models. One remarkable result of this approach is that the cosmological singularity can be avoided in a general fashion. However, whether the continuum limit of such discretized theories exists is model dependent. In the case of massless

K. -I. Izawa

Natural supergravity models of new inflation are reconsidered as minimal inflationary models within slow-roll approximation. Their running spectral index is derived in a revised form with recent observational results and future refinements in mind. This will possibly determine essential model parameters with respect to Planck-suppressed operators.

F. E. Close, S. Godfrey

Recent data on charmonium production in B-meson decays suggest that charmonium hybrid mesons with mass ~4 GeV may be produced in B-decay via c\bar{c} colour octet operators. Some of these states are likely to be narrow with clean signatures to J/ψpi^+ pi^- final states. Experimental signatures and search strategies for existing B-factories are described.

Prateek Sharma, Gregory W. Hammett, Eliot Quataert

Recent calculations by Quataert et al. (2002) found that the growth rates of the magnetorotational instability (MRI) in a collisionless plasma can differ significantly from those calculated using MHD. This can be important in hot accretion flows around compact objects. In this paper we study the transition from the collisionless kinetic regime to the collisi

L. -A. Wu, M. S. Byrd, D. A. Lidar

We reply to Dukelsky, et al. regarding the article: L. A. Wu, M. S. Byrd and D. A. Lidar, Phys. Rev. Lett. 89, 057904 (2002).

H. H. Erbil

We found a simple procedure for the solution of the time - independent Schrodinger equation in one dimension without making any approximation. The wave functions are always periodic. Two difficulties may be encountered: one is to solve the equation E=U(x), where E and U(x) are the total and potential energies, respectively, and the other is to calculate the

Daniel Comparat

NDE (Near-dissociation expansion) including LeRoy-Bernstein formulas are improved by taking into account the multipole expansion coefficients and the non asymptotic part of the potential curve. Applying these new simple analytical formulas to photoassociation spectra of cold alkali atoms, we improve the determination of the asymptotic coefficient, reaching a

Petre Dita

In this paper we obtain a description of the Hermitian operators acting on the Hilbert space $\C^n$, description which gives a complete solution to the over parameterization problem. More precisely we provide an explicit parameterization of arbitrary $n$-dimensional operators, operators that may be considered either as Hamiltonians, or density matrices for f

Kazuyuki Fujii

In this paper we propose a Hamiltonian generalizing the interaction of the two--level atom and both the single radiation mode and external field $...$ a kind of cavity QED. We solve the Schrodinger equation in the strong coupling regime by making use of rotating wave approximation under new resonance conditions containing the Bessel functions and etc, and ob

Manfred Lein, Jan M. Rost

We present a theoretical analysis of high-order harmonic generation from ion-atom collisions in the presence of linearly polarized intense laser pulses. Photons with frequencies significantly higher than in standard atomic high-harmonic generation are emitted. These harmonics are due to two different mechanisms: (i) collisional electron capture and subsequen

Jacques Moret-Bailly

The usual computation of the spontaneous emission uses a mixture of classical and quantum postulates. A purely classical computation shows that a source of electromagnetic field absorbs light in the eigenmode it is able to emit. Thus in an excitation by an other mode, the component of this mode on the eigenmode is absorbed, while the remainder is scattered.

Jian-Qi Shen

Neutron spin can be coupled to the Earth&#39;s rotating frequency. Once if the Earth&#39;s rotating frequency is time-dependent, then the neutron will acquire a Berry&#39;s topological phase (cyclic adiabatic geometric phase). So, a potential method to investigate the Earth&#39;s time-varying rotating frequency by measuring the phase difference between geome

Rolf Mueller

A computational theory for classification of natural biosonar targets is developed based on the properties of an example stimulus ensemble. An extensive set of echoes (84 800) from four different foliages was transcribed into a spike code using a parsimonious model (linear filtering, half-wave rectification, thresholding). The spike code is assumed to consis

Jean-Marc Richard

A review is first presented of the Hall--Post inequalities relating $N$-body to $(N-1)$-body energies of quantum bound states. These inequalities are then applied to delimit, in the space of coupling constants, the domain of Borromean binding where a composite system is bound while smaller subsystems are unbound.

A. K. Chaudhuri

Using the QGP motivated threshold model, where all the $J/ψ$&#39;s are suppressed above a threshold density, we have analyzed the latest version of the NA50 data on the centrality dependence of the $J/ψ$ over Drell-Yan ratio. The data are not well explain in the model, unless the threshold density is largely smeared. Large smeared threshold density effective

A. Foerster, J. Links, H. -Q. Zhou

We review the theory for exactly solving quantum Hamiltonian systems through the algebraic Bethe ansatz. We also demonstrate how this theory applies to current studies in Bose-Einstein condensation and metallic grains which are of nanoscale size.

J. Links, H. -Q. Zhou, R. H. McKenzie, M. D. Gould

In this review we demonstrate how the algebraic Bethe ansatz is used for the calculation of the energy spectra and form factors (operator matrix elements in the basis of Hamiltonian eigenstates) in exactly solvable quantum systems. As examples we apply the theory to several models of current interest in the study of Bose-Einstein condensates, which have been

P. A. Horvathy

The ``Kaluza-Klein-type&#39;&#39; geometric structure appropriate to study the central extension of the Galilei group and non-relativistic physics is reviewed.

N. M. Atakishiyev, A. U. Klimyk

We study some classes of symmetric operators for the discrete series representations of the quantum algebra U_q(su_{1,1}), which may serve as Hamiltonians of various physical systems. The problem of diagonalization of these operators (eigenfunctions, spectra, overlap coefficients, etc.) is solved by expressing their overlap coefficients in terms of the known

Titu Andreescu, Walter Stromquist, Zoran Sunik

We show that the bandwidth of a square two-dimensional grid of arbitrary size can be reduced if two (but not less than two) edges are deleted. The two deleted edges may not be chosen arbitrarily, but they may be chosen to share a common endpoint or to be non-adjacent. We also show that the bandwidth of the rectangular n by m (m greater or equal to n) grid ca

Andreas Gathmann

We state and prove a topological recursion relation that expresses any genus-g Gromov-Witten invariant of a projective manifold with at least a (3g-1)-st power of a cotangent line class in terms of invariants with fewer cotangent line classes. For projective spaces, we prove that these relations together with the Virasoro conditions are sufficient to calcula

Christopher Voll

We introduce a new method to calculate local normal zeta functions of finitely generated, torsion-free nilpotent groups. It is based on an enumeration of vertices in the Bruhat-Tits building for Sl_n(Q_p). It enables us to give explicit computations for groups of class 2 with small centres and to derive local functional equations. Examples include formulae f

L. Molnar, M. Barczy

In this paper we determine all the bijective linear maps on the space of bounded observables which preserve a fixed moment or the variance. Nonlinear versions of the corresponding results are also presented.

Do Duc Hanh

In this article we describe the coadjoint orbits of SL(2,$\mathbb R$). After choosing polarizations for each orbits, we pointed out the corresponding quantum coadjoint orbits and therefore unitary representations of SL(2,$\mathbb R$) via deformation quantization.

Paul Terwilliger, Raimundas Vidunas

Let K denote a field and let $V$ denote a vector space over K with finite positive dimension. We consider an ordered pair of linear transformations $A:V\to V$ and $A^*:V\to V$ which satisfy the following two properties: (i) There exists a basis for $V$ with respect to which the matrix representing $A$ is irreducible tridiagonal and the matrix representing $A

Antonios Zagaris, Hans G. Kaper, Tasso J. Kaper

This article is concerned with the asymptotic accuracy of the Computational Singular Perturbation (CSP) method developed by Lam and Goussis to reduce the dimensionality of a system of chemical kinetics equations. The method exploits the presence of disparate time scales to model the dynamics by an evolution equation on a lower-dimensional slow manifold. In t

Matthew Neal, Bernard Russo

An atomic decomposition is proved for Banach spaces which satisfy some affine geometric axioms compatible with notions from the quantum mechanical measuring process. This is then applied to yield, under appropriate assumptions, geometric characterizations, up to isometry, of the unit ball of the dual space of a JB*-triple, and up to complete isometry, of one

M. Volkov

Let V be a p-adic representation of the absolute Galois group G of Q_p that becomes crystalline over a finite tame extension, and assume p odd. We provide necessary and sufficient conditions for V to be isomorphic to the Tate module V_p(A) of an abelian variety A defined over Q_p. These conditions are stated on the filtered (ϕ,G)-module attached to V.

S. Pruss-Hunzinger, S. Rupp, M. Sorg

The relativistic two-particle quantum mixtures are studied from the topological point of view. The mixture field variables can be transformed in such a way that a kinematical decoupling of both particle degrees of freedom takes place with a residual coupling of purely algebraic nature (&#34;exchange coupling&#34;). Both separated sets of particle variables i

Luis F. Alday, Michele Cirafici, Justin R. David, Edi Gava

We study effective gravitational F-terms, obtained by integrating an $U(N)$ adjoint chiral superfield $Φ$ coupled to the ${\cal N}=1$ gauge chiral superfield $W_α$ and supergravity, to arbitrary orders in the gravitational background. The latter includes in addition to the ${\cal N}=1$ Weyl superfield $G_{αβγ}$, the self-dual graviphoton field strength $F_{α

C. Carimalo, A. Schiller, V. G. Serbo

We consider inelastic QED processes, the cross sections of which do not drop with increasing energy. Such reactions have the form of two-jet processes with the exchange of a virtual photon in the t-channel. We consider them in the region of small scattering angles m/E <= theta << 1, which yield the dominant contribution to their cross sections. A new effecti

Tai-Fu Feng, Tao Huang, Xue-Qian Li, Xin-Min Zhang

We investigate the muon anomalous magnetic dipole moment (MDM), the muon electric dipole moment (EDM) and the lepton-flavour-violating decays of the $τ-$lepton, $τ\to μγ$ and $τ\to 3μ$, in the CP-violating Minimal Supersymmetric Standard Model (MSSM) with nonuniversal soft-supersymmetry breaking. We evaluate numerically the muon EDM and the branching ratios

R. Fiore, L. L. Jenkovszky, F. Paccanoni, A. Prokudin

An earlier developed model for vector meson photoproduction, based on a dipole Pomeron exchange, is extended to electroproduction. Universality of the non linear Pomeron trajectory is tested by fitting the model to ZEUS and H1 data as well as to CDF data on $\bar pp$ elastic scattering

Margarete Mühlleitner, Michael Spira

We analyze the next-to-leading order QCD corrections to the production of doubly-charged Higgs particles at hadron colliders in extensions of the SM with Higgs isospin triplets. At both the Tevatron and the LHC, these corrections are found to be moderate in size increasing the cross sections by about 20--30%. The residual theoretical uncertainties are of the

B. Blok

We study in the quasiclassical approximation the radiation reaction and its influence on the space-time evolution for the small relativistic dipole moving in a constant external electromagnetic field in QED.

Morimitsu Tanimoto

We have discussed the impact of $U_{e3}$ on the model of the neutrino mass matrix. In order to get the small $U_{e3}$, some flavor symmetry is required. Typical two models are investigated. The first one is the model in which the bi-maximal mixing is realized at the symmetric limit. The second one is the texture zeros of the neutrino mass matrix.

N. Adam, S. Lee, H. Schwarthoff, T. Wilksen

After the successful conclusion of the CLEO III phase, the CLEO experiment at the Cornell Electron Positron Storage Ring CESR is preparing for its transition to CLEO-c. This new program contains a wide array of Physics studies at e+ e- collisions at center of mass energies between 3 GeV and 5 GeV that will provide new insights into QCD. Because the existing

Andreas Warburton

I report on studies of inclusive and exclusive semileptonic b -> c l nu and b -> u l nu decays in 9.7 million BBbar events accumulated with the CLEO detector in symmetric e^+e^- collisions produced in the Cornell Electron Storage Ring (CESR). Various experimental techniques, including the study of spectral moments and the inference of neutrino candidates by

R. Esposito, P. Mastroserio, G. Tortone, F. M. Taurino

Web portals are nowadays very popular. This type of web sites let users to share information, request advice or help in a particular field, and furthermore allow them to create and extend sites content. Combined with instant messaging systems, used to send messages or files instantaneously to a user or a group of users, and with various kinds of chat program

R. Esposito, P. Mastroserio, G. Tortone, F. M. Taurino

Accurately estimate performance of currently available processors is becoming a key activity, particularly in HENP environment, where high computing power is crucial. This document describes the methods and programs, opensource or freeware, used to benchmark processors, memory and disk subsystems and network connection architectures. These tools are also use

R. Esposito, P. Mastroserio, G. Tortone, F. M. Taurino

The OpenMosix approach is a good solution to build powerful and scalable computing farms. Furthermore an easy management infrastructure is implemented using diskless nodes and network boot procedures. In HENP environment, the choice of OpenMosix has been proven to be an optimal solution to give a general performance boost on implemented systems thanks to its

L. Berti, V. Brigljevic, G. Bruno, E. Cano

XDAQ is a generic data acquisition software environment that emerged from a rich set of of use-cases encountered in the CMS experiment. They cover not the deployment for multiple sub-detectors and the operation of different processing and networking equipment as well as a distributed collaboration of users with different needs. The use of the software in var

The OPAL collaboration, G. Abbiendi

For the first time at LEP the production of prompt photons is studied in the collisions of quasi-real photons using the OPAL data taken at e+e- centre-of-mass energies between 183 GeV and 209 GeV. The total inclusive production cross-section for isolated prompt photons in the kinematic range of photon transverse momentum larger than 3.0 GeV and absolute phot

V. Bindi, N. Carota, D. Casadei, G. Castellini

The AMS-02 detector is a superconducting magnetic spectrometer that will operate on the International Space Station. The time of flight (TOF) system of AMS-02 is composed by four scintillator planes with 8, 8, 10, 8 counters each, read at both ends by a total of 144 phototubes. This paper describes the new design, the expected performances, and shows prelimi

Naoki Seto, Jun&#39;Ichi Yokoyama

We propose a method to probe the equation of state of the early universe and its evolution, using the stochastic gravitational wave background from inflation. A small deviation from purely radiation dominated universe ($w= 1/3$) would be clearly imprinted on the gravitational wave spectrum $Ω_{GW}(f)$ due to the nearly scale invariant nature of inflationary

Wei Wang

Factorization of statistical language models is the task that we resolve the most discriminative model into factored models and determine a new model by combining them so as to provide better estimate. Most of previous works mainly focus on factorizing models of sequential events, each of which allows only one factorization manner. To enable parallel factori

M. E. J. Newman, Juyong Park

We argue that social networks differ from most other types of networks, including technological and biological networks, in two important ways. First, they have non-trivial clustering or network transitivity, and second, they show positive correlations, also called assortative mixing, between the degrees of adjacent vertices. Social networks are often divide

Satoshi Nishimoto, Yukinori Ohta

The density-matrix renormalization-group method is used to study the electronic states of a two-chain Hubbard model for CuO double chains of PrBa$_2$Cu$_4$O$_8$. We show that the model at quarter filling has the charge ordered phases with stripe-type and in-line--type patterns in the parameter space, and in-between, there appears a wide region of vanishing c

Constantino Tsallis, Edgardo Brigatti

Boltzmann-Gibbs statistical mechanics is based on the entropy $S_{BG}=-k \sum_{i=1}^W p_i \ln p_i$. It enables a successful thermal approach of ubiquitous systems, such as those involving short-range interactions, markovian processes, and, generally speaking, those systems whose dynamical occupancy of phase space tends to be ergodic. For systems whose micros

D. V. Shopova, T. P. Todorov

A new approach to the treatment of magnetic fluctuations in thin films of type I superconductors is introduced. Results for the dependence of free energy, specific heat and order parameter profile on the film thickness near the equilibrium phase transition point are obtained and discussed.

D. V. Shopova, D. I. Uzunov

The coexistence of a homogeneous (Meissner-like) phase of spin-triplet superconductivity and ferromagnetism is investigated within the framework of a phenomenological model of spin-triplet ferromagnetic superconductors. The results are discussed in view of application to metallic ferromagnets as UGe$_2$, ZrZn$_2$, URhGe, and Fe.

M. Payami

Using the stabilized jellium model in two schemes of `relaxed&#39; and `rigid&#39;, we have calculated the dissociation energies and the fission barrier heights for the binary fragmentations of singly-ionized and doubly-ionized Ag clusters. In the calculations, we have assumed spherical geometries for the clusters. Comparison of the fragmentation energies in

Sunil Nair, A. Banerjee, A. V. Narlikar, D. Prabhakaran

We report measurements and analysis of the magnetic critical phenomena in a single crystal of La${_{0.875}}$Sr${_{0.125}}$MnO${_3}$. The critical exponents associated with the ferromagnetic transition have been determined from ac susceptibility and dc magnetisation data. Techniques like the Kouvel$-$Fischer plots, modified Arrots Plots and the critical isoth

J. Demsar, R. D. Averitt, K. H. Ahn, M. J. Graf

We present the first femtosecond studies of electron-phonon (e-ph) thermalization in heavy fermion compounds. The e-ph thermalization time tau_{ep} increases below the Kondo temperature by more than two orders of magnitude as T = 0 K is approached. Analysis using the two-temperature model and numerical simulations based on Boltzmann&#39;s equations suggest t

Daniel Dantchev, Michael Krech, S. Dietrich

Recently a nonuniversal character of the leading spatial behavior of the thermodynamic Casimir force has been reported [X. S. Chen and V. Dohm, Phys. Rev. E {\bf 66}, 016102 (2002)]. We reconsider the arguments leading to this observation and show that there is no such leading nonuniversal term in systems with short-ranged interactions if one treats properly

C. M. Aegerter, H. Keller, S. L. Lee, C. Ager

We investigate the superconducting behaviour of Bi doped Pb. Pure lead shows type-I behaviour entering an intermediate state in a magnetic field. High dopings of Bi ($>$3%) lead to type-II behaviour showing a mixed state, where the magnetic field penetrates the superconductor in the form of a flux lattice. At intermediate doping, the sample shows both type-I

Stephane Lenfant, Christophe Krzeminski, Christophe Delerue, Guy Allan

We demonstrate a molecular rectifying junction made from a sequential self-assembly on silicon. The device structure consists of only one conjugated (p) group and an alkyl spacer chain. We obtain rectification ratios up to 37 and threshold voltages for rectification between -0.3V and -0.9V. We show that rectification occurs from resonance through the highest

C. M. Aegerter, H. Keller, S. H. Lloyd, P. G. Kealey

We present a study of the vortex lattice in untwinned YBa$_2$Cu$_3$O$_{7-x}$ crystals, using a combination of muon spin rotation and neutron small angle scattering measurements. Both methods show a very sharp melting temperature consistent with a first order transition. The dependence of the melting temperature on the angle of the field with respect to the c

C. M. Aegerter, R. Günther, R. J. Wijngaarden

We present a two-dimensional system which exhibits features of self-organized criticality. The avalanches which occur on the surface of a pile of rice are found to exhibit finite size scaling in their probability distribution. The critical exponents are $τ$ = 1.21(2) for the avalanche size distribution and $D$ = 1.99(2) for the cut-off size. Furthermore the

C. M. Aegerter, M. S. Welling, R. J. Wijngaarden

The penetration of magnetic flux into a thin film of YBa$_2$Cu$_3$O$_{7-x}$ is studied when the external field is ramped slowly. In this case the flux penetrates in bursts or avalanches. The size of these avalanches is distributed according to a power law with an exponent of $τ$ = 1.29(2). The additional observation of finite-size scaling of the avalanche di

M. Barranco, M. Guilleumas, E. S. Hernandez, R. Mayol

We investigate the behavior of mixed 3He-4He droplets on alkali surfaces at zero temperature, within the frame of Finite Range Density Functional theory. The properties of one single 3He atom on 4He_N4 droplets on different alkali surfaces are addressed, and the energetics and structure of 4He_N4+3He_N3 systems on Cs surfaces, for nanoscopic 4He drops, are a

L. M. Fisher, T. H. Johansen, A. L. Rakhmanov, A. A. Levchenko

A theory of the macroturbulent instability in the system containing vortices of opposite directions (vortices and antivortices) in hard superconductors is proposed. The origin of the instability is connected with the anisotropy of the current capability in the sample plane. The anisotropy results in the appearance of tangential discontinuity of the hydrodyna

D. Bolle, R. Erichsen,, W. K. Theumann

The time evolution of an exactly solvable layered feedforward neural network with three-state neurons and optimizing the mutual information is studied for arbitrary synaptic noise (temperature). Detailed stationary temperature-capacity and capacity-activity phase diagrams are obtained. The model exhibits pattern retrieval, pattern-fluctuation retrieval and s

D. V. Shopova, D. I. Uzunov

We investigate thermodynamic phases, including the phase of coexistence of superconductivity and ferromagnetism, the possible phase transitions of first and second order, and the shape of the phase diagram in mean-field approximation for a phenomenological model of spin-triplet ferromagnetic superconductors. The results are discussed in view of application t

B. Guillet, L. Mechin, D. Robbes

Dedicated read-out electronics was developed for low impedance resistive thermometers. Using this high performance temperature controller, the temperature dependence of the excess noise of a YBa2Cu307-d (YBCO) sample in the superconducting transition was monitored as a function of the current bias. The noise could reach 3.10-8 K Hz-1/2 at 1 Hz, 5 mA bias and

Wellington da Cruz

We consider recent experimental results [W. Pan {\it et al}, Phys. Rev. Lett. {\bf 90}, 016801 (2003)] for occurrence of the fractional quantum Hall effect-FQHE under the perspective of our formulation in terms of {\it fractons}. These objects carry rational or irrational values of spin and satisfy a {\it fractal distribution function} associated with a {\it

Marjorie Gonzalez, Samar Safi-Harb

We report the Chandra Advanced CCD Imaging Spectrometer detection of the X-ray counterpart of the high magnetic field, ~1600 year-old, 407 ms radio pulsar J1119-6127 associated with the supernova remnant G292.2-0.5. The powerful imaging capability of Chandra also unveiled, for the first time, a faint 3&#34;x6&#34; pulsar wind nebula (PWN) at energies above ~