March 2002 arXiv papers — page 13

Fabio Riccioni

This dissertation reviews some properties of the low-energy effective actions for six dimensional open-string models. The first chapter is a pedagogical introduction about supergravity theories. In the second chapter closed strings are analyzed, with particular emphasis on type IIB, whose orientifold projection, in order to build type-I models, is the subjec

Belal E. Baaquie, Yim Kok Kean

We study the Lagrangian for a sigma model based on the non-compact Heisenberg group. A unique feature of this model -- unlike the case for compact Lie groups -- is that the definition of the Lagrangian has to be regulated since the trace over the Heisenberg group is otherwise divergent. The resulting theory is a real Lagrangian with a quartic interaction ter

Stefano Profumo, Ettore Vicari

We study the twisted Eguchi-Kawai (TEK) reduction procedure for large-N unitary matrix lattice models. In particular, we consider the case of two-dimensional principal chiral models, and use numerical Monte Carlo (MC) simulations to check the conjectured equivalence of TEK reduced model and standard lattice model in the large-N limit. The MC results are comp

A. M. Ghezelbash, R. B. Mann

We study the problem of vortex solutions in the background of rotating black holes in both asymptotically flat and asymptoticlly anti de Sitter spacetimes. We demonstrate the Abelian Higgs field equations in the background of four dimensional Kerr, Kerr-AdS and Reissner-Nordstrom-AdS black holes have vortex line solutions. These solutions, which have axial s

J. E. Cieza Montalvo, P. P. de Queiroz Filho

We study the production and signatures of heavy exotic quarks pairs at LHC in the framework of the vector singlet model (VSM), vector doublet model (VDM) and fermion-mirror-fermion (FMF) model. The pair production cross sections for the electroweak and strong sector are computed.

C. Adamuscin, A. Z. Dubnickova, S. Dubnicka, R. Pekarik

A system of linear homogeneous algebraic equations for coupling constant ratios of vector-mesons to hadrons is derived by imposing an asymptotic behaviuor upon the VMD pole parametrization of an hadron electromagnetic form factor. A similar system of equations with a simpler structure of coefficients, taken as even powers of vector-meson masses, is derived b

S. Arunagiri

We consider the interference of resonant amplitudes leading to the final state $K_S π^+ π^-$ in $D^0/\bar {D^0}$ decays. Each of these amplitudes consists of both Cabibbo allowed and doubly Cabibbo suppressed transitions. The role of strong phase arising out of Breit-Wigner resonant propagators is emphasised. Invoking the $ΔS = ΔQ$ rule, $K_S$ in the final s

J. Kwiecinski

We utilise the fact that the CCFM equation in the single loop approximation can be diagonalised by the Fourier-Bessel transform. The analytic solution of the CCFM equation for the moments $f_ω(b,Q)$ of the scale dependent gluon distribution is obtained, where $b$ is the transverse coordinate conjugate to the transverse momentum of the gluon. The unintegrated

Stephan Narison

In this talk, I present new results [1] obtained from QCD spectral sum rules (QSSR), on the bag constant parameters entering in the analysis of the B^0_{(s)}-\bar B^0_{(s)} mass-differences. Taking the average of the results from the Laplace and moment sum rules, one obtains to order α_s: f_B\sqrt{\hat B_B}= (228 +- 61) MeV, f_{B_s}\sqrt{B_{B_s}}/{f_{B}\sqrt

B. A. Kniehl, A. A. Penin, V. A. Smirnov, M. Steinhauser

The next-to-next-to-next-to-leading order (N^3LO) Hamiltonian of potential nonrelativistic QCD is derived. The complete matching of the Hamiltonian and the contribution from the ultrasoft dynamical gluons relevant for perturbative bound-state calculations is performed including one-, two-, and three-loop contributions. The threshold expansion is used to dise

A. D. Dolgov

The role of neutrinos in big bang nucleosynthesis is discussed. The bounds on the number of neutrino families, neutrino degeneracy, parameters of neutrino oscillations are presented. A model of chemically inhomogeneous, while energetically smooth, universe created by inhomogeneous cosmological neutrino asymmetry is described. Nucleosynthesis limits on produc

V. A. Petrov, A. V. Prokudin

A model of a three Pomeron contribution to high energy elastic $pp$ and $\bar p p$ scattering is proposed. The data are well described for all momenta ($0.01\le |t|\le 14. GeV^2$) and energies ($8.\le\sqrt{s}\le 1800. GeV$) ($χ^2/{\rm d.o.f.}=2.60$). The model predicts the appearance of two dips in the differential cross-section which will be measured at LHC

Changhao Jin

We calculate the total and differential decay rates for the semi-inclusive nonleptonic decays $B\to D_s^{(*)} X_q$ ($q=c$ or $u$) under the factorization hypothesis. The initial bound state effect is treated using the light-cone expansion and the heavy quark effective theory. We investigate the contribution of the penguin amplitude for the decay mode $B\to D

Yuji Igarashi, Hiroto So, Naoya Ukita

We derive Ginsparg-Wilson relation for a lattice chiral symmetry in theories with self-interacting fermions. Auxiliary scalar and pseudo-scalar fields are introduced on a coarse lattice to give an effective description of the fermionic interactions. We obtain particular solutions to the Ginsparg-Wilson relation and other Ward-Takahashi identities in a closed

The OPAL collaboration, G. Abbiendi

A novel method of determining the mass of the W boson in the W+W- -> lnu lnu channel is presented and applied to 667pb^-1 of data recorded at the center-of- mass energies in the range 183-207 GeV with the OPAL detector at LEP. The Measured energies of charged leptons and the results of a new procedure based on an approximate kinematic reconstruction of the e

Carlos O. Lousto, Bernard F. Whiting

Perturbation theory of rotating black holes is usually described in terms of Weyl scalars $ψ_4$ and $ψ_0$, which each satisfy Teukolsky's complex master wave equation and respectively represent outgoing and ingoing radiation. On the other hand metric perturbations of a Kerr hole can be described in terms of (Hertz-like) potentials $Ψ$ in outgoing or ingo

Jacob M. Howe, Andy King

In order to improve precision and efficiency sharing analysis should track both freeness and linearity. The abstract unification algorithms for these combined domains are suboptimal, hence there is scope for improving precision. This paper proposes three optimisations for tracing sharing in combination with freeness and linearity. A novel connection between

Semion Saykin, Dima Mozyrsky, Vladimir Privman

We study the low-temperature dynamics of a shallow donor, e.g., $^{31}$P, impurity electron spin in silicon, interacting with the bath of nuclear spins of the $^{29}$Si isotope. For small applied magnetic fields, the electron spin relaxation is controlled by the steady state distribution of the nuclear spins. We calculate the relaxation times $T_1$ and $T_2$

X. Chen, M. Na, M. Cheon, S. Wang

Digital alloys of GaSb/Mn have been fabricated by molecular beam epitaxy. Transmission electron micrographs showed good crystal quality with individual Mn-containing layers well resolved; no evidence of 3D MnSb precipitates was seen in as-grown samples. All samples studied exhibited ferromagnetism with temperature dependent hysteresis loops in the magnetizat

S. Mercone, A. Wahl, Ch. Simon, C. Martin

Up to now, electric field induced non-linear conduction in the Pr(1-x)CaxMnO3 system has been ascribed to a current-induced destabilization of the charge ordered phase. However, for x<0.25, a ferromagnetic insulator state is observed and charge-ordering is absent whatever the temperature. A systematic investigation of the non-linear transport in the ferromag

Paul Goddard, Stanley W. Tozer, John Singleton, Arzhang Ardavan

The conducting properties of the pressure-induced, layered organic superconductor (BEDT-TTF)_3Cl_2.2H_20 have been studied at 13.5 and 14.0 kbar using low temperatures, high magnetic fields and two-axis rotation. An upper critical field that is significantly larger than that expected from the Pauli paramagnetic limit is observed when the field is applied par

K. E. Chan, P. L. Krapivsky, S. Redner

We study the long-time dynamics of a forest-fire model with deterministic tree growth and instantaneous burning of entire forests by stochastic lightning strikes. Asymptotically the system organizes into a coarsening self-similar mosaic of synchronized patches within which trees regrow and burn simultaneously. We show that the average patch length <L> grows

F. Giazotto, F. Taddei, R. Fazio, F. Beltram

A promising scheme for electron microrefrigeration based on ferromagnet-superconductor contacts is presented. In this setup, cooling power densities up to 600 nW/$μ$m$^2$ can be achieved leading to electronic temperature reductions largely exceeding those obtained with existing superconductor-normal metal tunnel contacts. Half-metallic CrO$_2$/Al bilayers ar

Frank Krüger, Stefan Scheidl

We study the interplay of topological excitations in stripe phases: charge dislocations, charge loops, and spin vortices. In two dimensions these defects interact logarithmically on large distances. Using a renormalization-group analysis in the Coulomb gas representation of these defects, we calculate the phase diagram and the critical properties of the tran

T. Fliessbach

Guided by the analogy to the Bose-Einstein condensation of the ideal Bose gas (IBG) we propose a new model for the lambda transition of liquid helium. Deviating from the IBG our model uses phase ordered and localized single-particle functions. This means that finite groups of particles are assumed to be phase-locked. These phase correlations can be related t

J. -S. Kang, J. H. Kim, A. Sekiyama, S. Kasai

Electronic structures of Sr_2FeMoO_6 (SFMO) and Ba_2FeMoO_6 (BFMO) double perovskites have been investigated using the Fe 2p->3d resonant photoemission spectroscopy (PES) and the Cooper minimum in the Mo 4d photoionization cross section. The states close to the Fermi level are found to have strongly mixed Mo-Fe t_{2g} character, suggesting that the Fe valenc

Hongwei Xiong, Shujuan Liu, Guoxiang Huang

The analytical probability distribution of the quasi-2D (and purely 2D) ideal and interacting Bose gas are investigated by using a canonical ensemble approach. Using the analytical probability distribution of the condensate, the statistical properties such as the mean occupation number and particle number fluctuations of the condensate are calculated. Resear

Carl Gold, Peter Sollich

We address the problem of model selection for Support Vector Machine (SVM) classification. For fixed functional form of the kernel, model selection amounts to tuning kernel parameters and the slack penalty coefficient $C$. We begin by reviewing a recently developed probabilistic framework for SVM classification. An extension to the case of SVMs with quadrati

K. Ueda, M. Naito

This is the first review on superconducting MgB2 thin films as far as we know.

R. Mansilla, E. Bush

In this paper we develop a method to analyze the increase of complexity from classical Greek poetry to classical Latin poetry by mapping large samples of those poetry onto a symbolic time series. This mapping setup intends characterize regular succession of rhythms, that is, the patterns of stressed and unstressed syllables in a verse. Using techniques from

P. Kinsler

Quantum stochastic operator equations are derived for inter-branch exciton and polariton processes caused by acoustic phonon scattering. The use of a fully quantum model combined with these recently developed techniques predicts the presence of ``stimulated scattering&#39;&#39; terms, and provides a sound basis for understanding the basis of the approximatio

Haijun Zhou

The stability of a $β$-sheeted conformation and its transition into a random coil are studied with a 2D lattice biopolymer model. At low temperature and low external force, the polymer folds back and forth on itself and forms a $β$-sheet. Our analytical calculation and Monte Carlo simulation reveal that a co-operative $β$-sheet--random coil transition takes

Julian H. Krolik, John F. Hawley

What is meant by the &#34;inner edge&#34; of an accretion disk around a black hole depends on the property that defines the edge. We discuss four such definitions using data from recent high-resolution numerical simulations. These are: the &#34;turbulence edge&#34;, where flux-freezing becomes more important than turbulence in determining the magnetic field

C. Quiroga, J. Mikolajewska, E. Brandi, O. Ferrer

We analyze optical and near infrared spectra of intermediate and high resolution of the eclipsing symbiotic system AR Pavonis. We have obtained the radial velocity curves for the red and the hot component from the M-giant absorption lines and from the wings of Halpha, H and He II4686 emission profiles, respectively. From the orbital elements we have derived

Stephen A. W. Moore, John R. Lucey, Harald Kuntschner, Matthew Colless

We present a homogeneous and high signal-to-noise data set (mean S/N of ~60 per Å) of Lick/IDS stellar population line indices and central velocity dispersions for a sample of 132 bright (b_j < 18.0) galaxies within the central 1 deg (= 1.26 h^-1 Mpc) of the nearby rich Coma cluster (A1656). Our observations include 73 per cent (100 out of 137) of the total

G. Risaliti, M. Elvis, F. Nicastro

We present a study of X-ray column density variability in Seyfert 2 galaxies. We show that variations in N_H are observed in almost all the objects with multiple hard X-ray observations. Variation timescales (as short as a few months in several cases) are not in agreement with the standard scenario of a parsec-scale toroidal absorber. We propose that the X-r

Robbie C. Dohm-Palmer Evan D. Skillman

We have examined the ratio of blue to red (B/R) supergiants in the dwarf irregular galaxy Sextans A. The supergiants were identified in previously published stellar photometry measured from Hubble Space Telescope imaging. The high resolution imaging and low dust environment provided high photometric accuracy such that the main sequence and blue He-burning su

M. R. Zapatero Osorio, V. J. S. Bejar, E. L. Martin, D. Barrado y Navascues

We report very intense and variable Halpha emission (pseudo-equivalent widths of ~180, 410 A) of S Ori 55, a probable free-floating, M9-type substellar member of the young sigma Orionis open star cluster. After comparison with state-of-the-art evolutionary models, we infer that S Ori 55 is near or below the cluster deuterium-burning mass borderline, which se

Francesco Paparella, Edward A. Spiegel, Suzanne Talon

To investigate the mechanism of mixing in oscillatory doubly diffusive (ODD) convection, we truncate the horizontal modal expansion of the Boussinesq equations to obtain a simplified model of the process. In the astrophysically interesting case with low Prandtl number, large-scale shears are generated as in ordinary thermal convection. The interplay between

Neal A. Miller, Michael J. Ledlow, Frazer N. Owen, John M. Hill

Multifiber optical spectroscopy has been performed on galaxies in the vicinity of strong, nearby radio galaxies. These radio galaxies were selected from the 3CR and B2 catalogs based on their exclusion from the Abell catalog, which is puzzling given the hypothesis that an external medium is required to confine the radio plasma of such galaxies. Velocities de

Yu. S. Grishkan, V. B. Petkov, E. G. Vertogradova

The estimation of light velocity dispertion caused by quantum fluctuations influence on electromagnetic wave propogation in four-dimensional space-time is presented. Analytical cosmological solutions for the flat and open Universe for the case of cosmic vacuum model are obtained. The time delay of cosmic gamma-ray burst radiation is calculated. The delay is

D. H. Lumb

We briefly describe the in orbit measurements of the mirror vignetting, using observations of SNR G21.5-09. The instrument features which complicate these measurements are briefly described, and we show the spatial and energy dependences, outlining assumptions made in deriving the eventual agreement between theory and measurement.

D. H. Lumb

We briefly describe the methods used in compiling a set of high galactic latitude background data. The characteristics and limitations of the data which affect their use as a template for analysing extended objects are described. We briefly describe a spectral fitting analysis of the data which reveals a normalisation for the extragalactic background of 11.4

D. H. Lumb

This paper introduces the articles that describe detailed aspects of the XMM-Newton calibration. The unique calibration issues of XMM-Newton are highlighted. The original calibration requirements and aspects of the ground calibration are summarized. The life cycle of the in-orbit calibration observations, analysis and ingestion into calibration files is disc

Luigi Piro

Observational evidence of iron absorption and emission lines in X-ray spectra of Gamma-Ray Bursts is quite compelling. I will briefly review the results, summarize different models and describe the connection with massive progenitors in star-forming regions implied by these results. This link is also supported by measurements of the X-ray absorbing gas in se

Yan Guo, Gerhard Rein

We construct stable axially symmetric models of elliptical galaxies. The particle density on phase space for these models depends monotonically on the particle energy and on the third component of the angular momentum. They are obtained as minimizers of suitably defined energy-Casimir functionals, and this implies their nonlinear stability. Since our analysi

C. Isola, G. Sigl

We present numerical simulations for the two-point correlation function and the angular power spectrum of nucleons above 10^{19} injected by a discrete distribution of sources following a simple approximation to the profile of the Local Supercluster. We develop a method to constrain the number of sources necessary to reproduce the observed sky distribution o

G. G. Pavlov, V. E. Zavlin, D. Sanwal, J. Trumper

Second Chandra observation of 1E 1207.4-5209, the central source of the supernova remnant PKS 1209-51/52, allowed us to confirm the previously detected period of 424 ms and, assuming a uniform spin-down, estimate the period derivative, Pdot (0.7-3)e-14 s/s. The corresponding characteristic age of the pulsar, P/2Pdot~200-900 kyr, is much larger than the estim

S. L. Skinner, S. A. Zhekov, M. Guedel, W. Schmutz

We have used the excellent sensitivity of XMM-Newton to obtain the first high-quality X-ray spectrum of a Wolf-Rayet (WR) star which is not known to be a member of a binary system. Our target, the nitrogen-type star WR 110 (= HD 165688) was also observed and detected with the VLA at four different frequencies. The radio data are in excellent agreement with t

Somnath Bharadwaj, Shiv K. Sethi

We investigate the possibility of probing the large scale structure in the universe at large redshifts by studying fluctuations in the redshifted 1420 MHz emission from the neutral hydrogen (HI) at early epochs. The neutral hydrogen content of the universe is known from absorption studies for z<4.5. The HI distribution is expected to be inhomogeneous in the

E. Pointecouteau, M. Hattori, D. M. Neumann, E. Komatsu

We have performed a combined analysis of X-ray and Sunyaev-Zel&#39;dovich data in the direction of the distant galaxy cluster, RX J2228+2037. Fitting a $β$-model to the high-resolution HRI data gives $r_c = 103 \pm 12 h_{70}^{-1}$ kpc and $β=0.54 \pm 0.03$. The dependency of the Sunyaev-Zel&#39;dovich effect with respect to the gas temperature allows us, thr

C. Ciofi degli Atti, L. P. Kaptari

The two-proton emission process $^3He(e,e&#39;pp)n$ is theoretically investigated using realistic three-nucleon wave functions and taking the final state interaction into account by an approach which can be used when the value of the three-nucleon invariant mass is either below or above the pion emission threshold. Various kinematical conditions which enhanc

Han-Dong Chen, Jiang-Ping Hu, Sylvain Capponi, Enrico Arrigoni

We propose a microscopic state for the vortex phase of BSCO superconductors. Around the vortex core or above H_{c2}, the d wave hole pairs form a checkerboard localized in the commensurate antiferromagnetic background. We discuss this theory in connection with recent STM experiments.

T. Fritzsche, W. Hollik

The mass spectrum of the chargino--neutralino sector in the minimal supersymmetric standard model (MSSM) is calculated at the one-loop level, based on the complete set of one-loop diagrams. On-shell renormalization conditions are applied to determine the counterterms for the gaugino-mass-parameters $M_1, M_2$ and the Higgsino-mass parameter $μ$. The input is

S. Shankaranarayanan

We study the effects of the trans-Planckian dispersion relation on the spectrum of the primordial density perturbations during inflation. In contrast to the earlier analyses, we do not assume any specific form of the dispersion relation and allow the initial state of the field to be arbitrary. We obtain the spectrum of vacuum fluctuations of the quantum fiel

Daniel Smania

We describe a new and robust method to prove rigidity results in complex dynamics. The new ingredient is the geometry of the critical puzzle pieces: under control of geometry and ``complex bounds&#39;&#39;, two generalized polynomial-like maps which admits a topological conjugacy, quasiconformal outside the filled-in Julia set are, indeed, quasiconformally c

Ayse Karasu, Atalay Karasu, S. Yu. Sakovich

A recursion operator is constructed for a new integrable system of coupled Korteweg - de Vries equations by the method of gauge-invariant description of zero-curvature representations. This second-order recursion operator is characterized by unusual structure of its nonlocal part.

D. J. Wilner, M. J. Holman, M. J. Kuchner, P. T. P. Ho

We present images of the Vega system obtained with the IRAM Plateau de Bure interferometer at 1.3 millimeters wavelength with sub-mJy sensitivity and $\sim2\farcs5$ resolution (about 20 AU). These observations clearly detect the stellar photosphere and two dust emission peaks offset from the star by $9\farcs5$ and $8\farcs0$ to the northeast and southwest, r

I. I. Bigi

With the time dependant CP asymmetry in $B_d(t) \to ψK_S$ well measured, the most powerful method to search for {\em direct} CP violation in $B_d$ decays is to analyze whether the CP asymmetry of other transitions like $B_d(t) \to π^+ π^-, η^{\prime}K_S$ etc. can be described by a $sin$ term taken from $B_d(t) \to ψK_S$ and without a cos term. The failure of

J. Blümlein, H. Böttcher

A QCD analysis of the world data on polarized deep inelastic scattering is presented in leading and next-to-leading order. New parameterizations are derived for the quark and gluon distributions for the kinematic range $x ε[10^{-9},1], Q^2 ε[1,10^6] \GeV^2$. The extrapolation far outside the domain of the current measurements is given both to allow for appli

M. Saffman, T. G. Walker

We discuss the application of dipole blockade techniques for the preparation of single atom and single photon sources. A deterministic protocol is given for loading a single atom in an optical trap as well as ejecting a controlled number of atoms in a desired direction. A single photon source with an optically controlled beam-like emission pattern is describ

James Lindesay, H. Pierre Noyes

Starting from a unitary, Lorentz invariant two-particle scattering amplitude , we show how to use an identification and replacement process to construct a unique, unitary particle-antiparticle amplitude. This process differs from conventional on-shell Mandelstam s,t,u crossing in that the input and constructed amplitudes can be off-diagonal and off-energy sh

E. M. Shahverdiev, K. A. Shore

In this paper a proposal is made of an adaptive coupling function for achieving synchronization between two lasers subject to optical feedback.Such a control scheme requires knowledge of the systems&#39; parameters. We demonstate that when these parameters are not available on-line parameter estimation can be applied.

Alejandro Rivero

We exhibit some series of discrete spectral triples converging to the canonical spectral triple of a finite dimensional manifold. Thus the non-go theorem of Goekeler and Schuecker is reasonably bypassed.

Vladimir Shpilrain

Based on a normal form for braid group elements suggested by Dehornoy, we prove several representations of braid groups by automorphisms of a free group to be faithful. This includes a simple proof of the standard Artin&#39;s representation being faithful.

B. P. Damyanov

Results on products of the distributions $x_{\pm}^{a}$ and $\de^{(p)}(x)$ with coinciding singularities are derived when the products are balanced so that they exist in the distribution space. These results follow the idea of a known result on distributional products published by Jan Mikusiński in 1966. They are obtained in Colombeau algebra $\EuScript{G}(\m

Gabriel Cardona, Jordi Quer

In this paper we classify curves of genus 2 with group of automorphisms isomorphic to D_8 or D_12 over an arbitrary field k (of characteristic different from 2 in the D_8 case and from 2 and 3 in the D_{12} case) up to k-isomorphism. As an application of the classification of curves of genus 2 obtained, we get precise arithmetic information on their elliptic

Alexey Boyarsky, Jeffrey A. Harvey, Oleg Ruchayskiy

We study a five-dimensional field theory which contains a monopole (string) solution with chiral fermion zero modes. This monostring solution is a close analog of the fivebrane solution of M-theory. The cancellation of normal bundle anomalies parallels that for the M-theory fivebrane, in particular, the presence of a Chern-Simons term in the low-energy effec

R. Gueven

A generalization of the limiting procedure of Penrose, which allows non-zero cosmological constants and takes into account metrics that contain homogeneous functions of degree zero, is presented. It is shown that any spacetime which admits a spacelike conformal Killing vector has a limit which is conformal to plane waves. If the spacetime is an Einstein spac

H. B. Nielsen, Y. Takanishi

We review our recent development of family replicated gauge group model, which generates the Large Mixing Angle MSW solution. The model is based on each family of quarks and leptons having its own set of gauge fields, each containing a replica of the Standard Model gauge fields plus a (B-L)-coupled gauge field. A fit of all the seventeen quark-lepton mass an

O. Philipsen

By dressing Polyakov lines with appropriate functionals of the gauge fields, we construct observables describing a fundamental representation static quark-antiquark pair in the singlet, adjoint and average channels of SU(N) pure gauge theory. Each of the potentials represents a gauge invariant eigenvalue of the Hamiltonian. Numerical simulations are performe

Takeshi Chiba

The current observational and experimental bounds on time variation of the constants of Nature are briefly reviewed.

Claudia V. Goldman, Dan Gang, Jeffrey S. Rosenschein, Daniel Lehmann

The system presented here shows the feasibility of modeling the knowledge involved in a complex musical activity by integrating sub-symbolic and symbolic processes. This research focuses on the question of whether there is any advantage in integrating a neural network together with a distributed artificial intelligence approach within the music domain. The p

Chenyu Wei, Deepak Srivastava, Kyeongjae Cho

Classical molecular dynamics (MD) simulations employing Brenner potential for intra-nanotube interactions and Van der Waals forces for polymer-nanotube interfaces are used to invetigate the thermal expansion and diffusion characteristics of carbon nanotube-polyethylene composites. Additions of carbon nanotubes to polymer matrix are found to increase the glas

L. B. Ioffe, A. J. Millis

The effect of proximity to a Mott insulating phase on the superflow properties of a d-wave superconductor is studied using the slave boson-U(1) gauge theory model. The model has two limits corresponding to superconductivity emerging either out of a &#39;renormalized fermi liquid&#39; or out of a non-fermi-liquid regime. Three crucial physical parameters are

Wolfgang Knospe, Ludger Santen, Andreas Schadschneider, Michael Schreckenberg

We present a detailed analysis of single-vehicle data which sheds some light on the microscopic interaction of the vehicles. Besides the analysis of free flow and synchronized traffic the data sets especially provide information about wide jams which persist for a long time. The data have been collected at a location far away from ramps and in the absence of

W. Knospe, L. Santen, A. Schadschneider, M. Schreckenberg

A two-lane extension of a recently proposed cellular automaton model for traffic flow is discussed. The analysis focuses on the reproduction of the lane usage inversion and the density dependence of the number of lane changes. It is shown that the single-lane dynamics can be extended to the two-lane case without changing the basic properties of the model whi

Feng Yuan, Shiping Feng

The effect of the additional second neighbor hopping t&#39; on the charge dynamics of the t-J model in the underdoped regime is studied within the fermion-spin theory. The conductivity spectrum of the t-t&#39;-J model shows the low-energy peak and unusual midinfrared band, while the resistivity exhibits a nearly temperature linear dependence with deviation a

Zhen Ye, Sheng Li, Xin Sub

Motivated by previous investigations on the radiative effects of the electric dipoles embedded in structured cavities, localization of electromagnetic waves in two dimensions is studied {\it ab initio} for a system consisting of many randomly distributed two dimensional dipoles. A set of self-consistent equations, incorporating all orders of multiple scatter

E. Pfahl, S. Rappaport, Ph. Podsiadlowski

We explore the possibility that neutron stars accreting from the winds of main-sequence stellar companions account for a significant fraction of low-luminosity, hard X-ray sources (L_X <~ 10^35 ergs/s; 1-10 keV) in the Galaxy. This work was motivated by recent Chandra observations of the Galactic center by Wang et al. (2002). Our calculations indicate that m

B. V. Vasiliev

Temperature dependence of an electron-nuclear plasma equilibrium density is considered basing on known approaches, which are given in (1)(2). It is shown that at a very high temperature, which is characteristic for a star interior, the equilibrium plasma density is almost constant and equals approximately to $10^{25}$ particles per $cm^3$. At a relatively lo

S. Kaspi, W. N. Brandt, I. M. George, H. Netzer

We present results from a 900 ks exposure of NGC 3783 with the High-Energy Transmission Grating Spectrometer on board the Chandra X-ray Observatory. The resulting X-ray spectrum has the best combination of signal-to-noise and resolution ever obtained for an AGN. This spectrum reveals absorption lines from H-like and He-like ions of N, O, Ne, Mg, Al, Si, and

Amir Levinson, Eran Ofek, Eli Waxman, Avishay Gal-Yam

The number of orphan radio afterglows associated with gamma-ray bursts (GRBs) that should be detected by a flux limited radio survey, is calculated. It is shown that for jetted GRBs this number is smaller for smaller jet opening angle (theta), contrary to naive expectation. For a beaming factor f_b^{-1}=(theta^2/2)^{-1} = 500, roughly the value inferred by F

W. Bietenholz, F. Hofheinz, J. Nishimura

We perform a non-perturbative study of pure gauge theory in a two dimensional non-commutative (NC) space. On the lattice, it is equivalent to the twisted Eguchi-Kawai model, which we simulated at N ranging from 25 to 515. We observe a clear large-N scaling for the 1- and 2-point function of Wilson loops, as well as the 2-point function of Polyakov lines. The

Freydoon Mansouri

It is pointed out that a collider experiment involves a local contribution to the energy-momentum tensor, a circumstance which not a common feature of the current state of the Universe at large characterized by the cosmological constant $Λ_0$. This contribution may be viewed as a change in the structure of space-time from its large scale form governed by $Λ_

Kaige Wang, Shiyao Zhu

We present a complete theoretical description of atomic storage states in the multimode framework by including spatial coherence in atomic collective operators and atomic storage states. We show that atomic storage states are Dicke states with the maximum cooperation number. In some limits, a set of multimode atomic storage states has been established in cor

D. Lenz, N. Peyerimhoff, I. Veselić

We study spectral properties of random operators in the general setting of groupoids and von Neumann algebras. In particular, we establish an explicit formula for the canonical trace of the von Neumann algebra of random operators and define an abstract density of states. The general setting applies to many examples studied before while we lay special emphasi

Stephen D. H. Hsu

We give a path integral expression for the quantum amplitude to produce a black hole from particle collisions. When expanded about an appropriate classical solution it yields the leading order contribution to the production amplitude in a curvature expansion. Classical solutions describing black hole production resulting from two particle scattering at non-z

Hwang Lee, Yuri Rostovtsev, Chris J. Bednar, Ali Javan

Laser induced line narrowing effect, discovered more than thirty years ago, can also be applied to recent studies in high resolution spectroscopy based on electromagnetically induced transparency. In this paper we first present a general form of the transmission width of electromagnetically induced transparency in a homogeneously broadened medium. We then an

F. Rathmann, M. Düren, P. Jansen, F. Klehr

The study of near--threshold meson production in pp and pd collisions involving polarized beams and polarized targets offers the rare opportunity to gain insight into short--range features of the nucleon--nucleon interaction. The Cooler Synchrotron COSY at FZ--Jülich is a unique environment to perform such studies. Measurements of polarization observables re

P. Chau Huu-Tai, N. A. Smirnova, P. Van Isacker

We present new analytical results concerning the spectral distributions for 2x2 random real symmetric matrices which generalise the Wigner surmise.

Tadeusz Ziebakowski

Traditional approaches to combination tones based on Helmholtz theory encounter essential interpreting difficulties, which the most known example is the anomalous behaviour of the combination tone 2f1-f2. Without doubt the phenomenon of combination tones is connected with nonlinear phenomena in the human ear. Therefore, it is generally assumed that the expla

Masato Okado, Anne Schilling, Mark Shimozono

Kerov, Kirillov, and Reshetikhin defined a bijection between highest weight vectors in the crystal graph of a tensor power of the vector representation, and combinatorial objects called rigged configurations, for type $A^{(1)}_n$. We define an analogous bijection for all nonexceptional affine types, thereby proving (in this special case) the fermionic formul

Jerzy Lukierski, Francesco Toppan

We describe the set of generalized Poincare and conformal superalgebras in D=4,5 and 7 dimensions as two sequences of superalgebraic structures, taking values in the division algebras R, C and H. The generalized conformal superalgebras are described for D=4 by OSp(1;8| R), for D=5 by SU(4,4;1) and for D=7 by U_αU(8;1|H). The relation with other schemes, in p

F. Loran

We study gauge fixing in the generalized Gupta-Bleuler quantization. In this method physical states are defined to be simultaneous null eigenstates of a set of quantum invariants. We apply the method to a solvable model proposed by Friedberg, Lee, Pang and Ren and show that no Gribov-type copies appears by construction.

Marek Czachor

Non-canonical quantization is based on certain reducible representations of canonical commutation relations. Relativistic formalism for electromagnetic non-canonical quantum fields is introduced. Unitary representations of the Poincaré group at the level of fields and states are explicitly given. Multi-photon and coherent states are introduced. Statistics of

V. Del Duca, W. B. Kilgore, C. Oleari, C. R. Schmidt

We consider Higgs + 2 jet production via gluon fusion in the limit where either one of the Higgs-jet or the dijet invariant masses become much larger than the typical momentum transfers in the scattering. These limits also occur naturally in Higgs production via weak-boson fusion. We show that the scattering amplitudes factorize in the high energy limit, and

Maritza de Coss, Rodrigo Huerta

Starting from a weak basis in which the up (or down) quark matrix is diagonal, we obtain an exact set of equations for the quark mass matrix elements in terms of known observables. We make a numerical analysis of the down (up) quark mass matrix. Using the data available for the quark masses and mixing angles at different energy scales, we found a numerical e

Nikolai V. Brilliantov, Thorsten Poeschel

We show that two basic mechanical processes, the collision of particles and rolling motion of a sphere on a plane, are intimately related. According to our recent findings, the restitution coefficient for colliding spherical particles ε, which characterizes the energy loss upon collision, is directly related to the rolling friction coefficient μ_{roll} for a

W. A. Al-Saidi, D. Stroud

We have studied quantum-mechanically a system of several small identical Josephson junctions in a lossless single-mode cavity for different initial states, under conditions such that the system is at resonance. This system is analogous to a collection of identical atoms in a cavity, which is described under appropriate conditions by the Dicke model. We find