January 2004 arXiv papers — page 14

Jeong Han Kim, Oleg Pikhurko, Joel Spencer, Oleg Verbitsky

It is not hard to write a first order formula which is true for a given graph G but is false for any graph not isomorphic to G. The smallest number $(G) of nested quantifiers in a such formula can serve as a measure for the ``first order complexity'' of G. Here, this parameter is studied for random graphs. We determine it asymptotically when the edge

Christophe Champetier, Vincent Guirardel

We give a topological framework for the study of Sela's limit groups: limit groups are limits of free groups in a compact space of marked groups. Many results get a natural interpretation in this setting. The class of limit groups is known to coincide with the class of finitely generated fully residually free groups. The topological approach gives some n

Carlos D'Andrea

We show that, for generic bihomogeneous polynomials, the determinant of the matrix of moving planes is irreducible.

Hanfeng Li

We show that matrices in the same orbit of the SO(n, n|Z) action on the space of n\times n skew-symmetric matrices give strong Morita equivalent noncommutative tori, both at the C*-algebra level and at the smooth algebra level. This proves a conjecture of Rieffel and Schwarz.

George J. McNinch

Let X be an F-rational nilpotent element in the Lie algebra of a connected and reductive group G defined over the ground field F. Suppose that the Lie algebra has a non-degenerate invariant bilinear form. We show that the unipotent radical of the centralizer of X is F-split. This property has several consequences. When F is complete with respect to a discret

Robert Coquereaux, Roberto Trinchero

The double triangle algebra(DTA) associated to an ADE graph is considered. A description of its bialgebra structure based on a reconstruction approach is given. This approach takes as initial data the representation theory of the DTA as given by Ocneanu's cell calculus. It is also proved that the resulting DTA has the structure of a weak *-Hopf algebra.

Veronika E. Hubeny

We present a short review of hep-th/0306170. In the context of AdS/CFT correspondence, we explore what information from behind the horizon of the bulk black hole geometry can be found in boundary CFT correlators. In particular, we argue that the CFT correlators contain distinct, albeit subtle, signals of the black hole singularity.

Ilka Brunner, Kentaro Hori, Kazuo Hosomichi, Johannes Walcher

We systematically construct and study Type II Orientifolds based on Gepner models which have N=1 supersymmetry in 3+1 dimensions. We classify the parity symmetries and construct the crosscap states. We write down the conditions that a configuration of rational branes must satisfy for consistency (tadpole cancellation and rank constraints) and spacetime super

Luisa Doplicher

I describe some phenomenological contexts in which it is possible to investigate effects induced by (string-motivated) canonical noncommutative spacetime. Due to the peculiar structure of the theory the usual criteria adopted for the choice of experimental contexts in which to test a theory may not be applicable here; care is required in taking into account

Luca Lusanna

The four (electro-magnetic, weak, strong and gravitational) interactions are described by singular Lagrangians and by Dirac-Bergmann theory of Hamiltonian constraints. As a consequence a subset of the original configuration variables are {\it gauge variables}, not determined by the equations of motion. Only at the Hamiltonian level it is possible to separate

T. Dereli, R. W. Tucker

By embedding Einstein's original formulation of GR into a broader context we show that a dynamic covariant description of gravitational stress-energy emerges naturally from a variational principle. A tensor $T^G$ is constructed from a contraction of the Bel tensor with a symmetric covariant second degree tensor field $Φ$ and has a form analogous to the s

Richard S. Garavuso

This talk adapts the available formalism to study a class of heterotic M-theory vacua with SO(10) grand unification group. Compactification to four dimensions with N = 1 supersymmetry is achieved on a torus fibered Calabi-Yau 3-fold Z = X / tau_{X} with first homotopy group pi_{1}(Z) = Z_{2}. Here X is an elliptically fibered Calabi-Yau 3-fold which admits t

Nikolaos Kidonakis

I review recent advances in the calculation of higher-order soft-gluon corrections for a variety of QCD, Higgs, and SUSY processes in hadron colliders. A unified approach and master formulas for next-to-next-to-leading order soft and virtual corrections are discussed. I present some applications of the formalism to top quark pair production at the Tevatron a

Raimund Ströhmer

We review the precision measurement of the mass and couplings of the W Boson at LEP. The total and differential W+W- cross section is used to extract the WWZ and WWgamma couplings. We discuss the techniques used by the four LEP experiments to determine the W mass in different decay channels, and present the details of methods used to evaluate the sources of

J. Huston, I. Puljak, T. Sjöstrand, E. Thomé

The transverse momentum spectra of the Z and Higgs bosons are studied, as probes of the consequences of multiple parton emissions in hadronic events. Emphasis is put on constraints, present in showers, that go beyond conventional leading log. It is shown that, if such constraints are relaxed, better agreement can be obtained with experimental data and with r

Yuan-Ben Dai, Chao-Shang Huang, Chun Liu, Shi-Lin Zhu

Within the framework of the heavy quark effective theory, QCD sum rules are used to calculate the masses of p-wave (c-bar s) states. The results for 0^+ and 1^+ states with the angular momentum of the light component j_l=1/2 are consistent with the experimental values for D_s(2317) and D_s(2457), respectively.

Piyush Kumar, Joseph D. Lykken

We revisit the possibility of "visible sector" SUSY models: models which are straightforward renormalizable extensions of the Minimal Supersymmetric Standard Model (MSSM), where SUSY is broken at tree level. Models of this type were abandoned twenty years ago due to phenomenological problems, which we review. We then demonstrate that it is possible t

Eduard Masso

I review the physics of axions, paying attention to the role as dark matter. This paper is based on talks given at the workshops ``Thinking, Observing and Mining the Universe'' held in Sorrento (Italy), September 22-27, 2003, and at ``International Workshop on Astroparticle and High Energy Physics'' held in Valencia (Spain) October 14-18, 200

Biagio Lucini, Michael Teper, Urs Wenger

We calculate the topological charge density of SU(N) lattice gauge fields for values of N up to N=8. Our T=0 topological susceptibility appears to approach a finite non-zero limit at N=infinity that is consistent with earlier extrapolations from smaller values of N. Near the deconfining temperature Tc we are able to investigate separately the confined and de

V. G. Bornyakov, M. N. Chernodub, H. Ichie, Y. Koma

We study the Abelian flux tube profile of mesonic and the baryonic configurations of static quarks below and above the finite-temperature transition in $N_f=2$ full QCD. To reduce effects of ultra-violet fluctuations we measure Abelian distributions of the action density, the color-electric field and the monopole current after fixing to the maximally Abelian

Robert Oeckl

We give an introductory account to the renormalization of models without metric background. We sketch the application to certain discrete models of quantum gravity such as spin foam models.

Giovanni Imponente, Giovanni Montani

We analyze the Bianchi IX dynamics (Mixmaster) in view of its stochastic properties; in the present paper we address either the original approach due to Belinski, Khalatnikov and Lifshitz (BKL) as well as a Hamiltonian one relying on the Arnowitt--Deser--Misner (ADM) reduction. We compare these two frameworks and show how the BKL map is related to the geodes

Luca Lusanna

The status of canonical reduction for metric and tetrad gravity in space-times of the Christodoulou-Klainermann type, where the ADM energy rules the time evolution, is reviewed. Since in these space-times there is an asymptotic Minkowski metric at spatial infinity, it is possible to define a Hamiltonian linearization in a completely fixed (non harmonic) 3-or

Leopoldo Bertossi, Loreto Bravo

The problem of answering queries posed to a peer who is a member of a peer-to-peer data exchange system is studied. The answers have to be consistent wrt to both the local semantic constraints and the data exchange constraints with other peers; and must also respect certain trust relationships between peers. A semantics for peer consistent answers under exch

B. F. Samsonov, Yu. V. Pershin

In nuclear-spin-polarization-induced quantum dots the electrons are confined through local nuclear spin polarization. The model electron confinement potential is time-dependent due to the nuclear spin diffusion and relaxation processes. It can be well-approximated by a Gaussian curve which is not an exactly solvable potential. We demonstrate that it can also

R. S. Perry, K. Kitagawa, S. A. Grigera, R. A. Borzi

We present measurements on ultra clean single crystals of the bilayered ruthenate metal Sr3Ru2O7, which has a magnetic-field-tuned quantum critical point. Quantum oscillations of differing frequencies can be seen in the resistivity both below and above its metamagnetic transition. This frequency shift corresponds to a small change in the Fermi surface volume

Michael J. Mehl, Aaron Aguayo, Larry L. Boyer, Romeo de Coss

A tetragonal (Bain path) distortion of a metal with an fcc (bcc) ground state will initially cause an increase in energy, but at some point along the Bain path the energy will again decrease until a local minimum is reached. Using a combination of parametrized tight-binding and first-principles LAPW calculations we show that this local minimum is unstable wi

M. I. Dyakonov

This is a brief review of spin physics in semiconductors, as well as of the historic roots of the recent very active research of spin-related phenomena. The perspectives of "spintronics" are also discussed.

F. P. Mancini, P. Sodano, A. Trombettoni

We study the effects of external offset charges on the phase diagram of Josephson junction arrays. Using the path integral approach, we provide a pedagogical derivation of the equation for the phase boundary line between the insulating and the superconducting phase within the mean-field theory approximation. For a uniform offset charge q=e the superconductin

Joydeep Bhattacharjee, Umesh V Waghmare

We present a formal expression for Wannier functions of composite bands of 1-D Bloch electrons in terms of parallel-transported Bloch functions and their non-Abelian geometric phases. Spatial decay properties of these Wannier functions are studied in the case of simple bands of 1-D model insulator and metal. Within first-principles density functional theory,

Christophe Josserand, Pierre-Yves Lagree, Daniel Lhuillier

We propose a simple continuum model to interpret the shearing motion of dense, dry and cohesion-less granular media. Compressibility, dilatancy and Coulomb-like friction are the three basic ingredients. The granular stress is split into a rate-dependent part representing the rebound-less impacts between grains and a rate-independent part associated with long

H. Lammert, A. Heuer

The existence of conduction channels in lithium silicate (Li_2O)(SiO_2) is investigated. Regions of the system where many different ions pass by form channels and are thus spatially correlated. For a closer analysis the properties of the individual ionic sites are elucidated. The mobility of ions in single sites is found to depend strongly on the number of b

Karl Isak Skau, Edgar M. Blokhuis, Jan van Male

In a previous article [E.M. Blokhuis, K.I. Skau, and J.B. Avalos, J. Chem. Phys. 119, 3483 (2003)], a self-consistent field formalism was derived for weakly adsorbing polymers, valid for any chain length. It was shown that the presence of a solid wall induces an ordering of the polymers on the scale of the radius of gyration far away from the surface (the di

M. I. Krivoruchenko

The autocorrelation function of volatility in financial time series is fitted well by a superposition of several exponents. Such a case admits an explicit analytical solution of the problem of constructing the best linear forecast of a stationary stochastic process. We describe and apply the proposed analytical method for forecasting volatility. The leverage

Cesare Tozzo, Franco Dalfovo

Phonon-like excitations can be imprinted into a trapped Bose-Einstein condensate of cold atoms using light scattering. If the condensate is suddenly let to freely expand, the initial phonons lose their collective character by transferring their energy and momentum to the motion of individual atoms. The basic mechanisms of this evaporation process are investi

Andrea Donarini, Tomas Novotny, Antti-Pekka Jauho

We study the shuttling instability in an array of three quantum dots the central one of which is movable. We extend the results by Armour and MacKinnon on this problem to a broader parameter regime. The results obtained by an efficient numerical method are interpreted directly using the Wigner distributions. We emphasize that the instability should be viewed

Peter Babinec

Heuristic arguments are presented to show that the basic quantity of density functional theory - exact universal exchange-correlation potential should have fractal structure.

Andrea Donarini, Antti-Pekka Jauho

We present a semiclassical analysis of the instability of an electron shuttle composed of three quantum dots: two are fixed and coupled via leads to electron resevoirs at different chemical potentials, while the central dot is mounted on a classical harmonic oscillator. The semiclassical analysis, which is valid if the central dot oscillation amplitude is la

Frank Krüger, Stefan Scheidl

The spin dynamics of bilayer cuprate compounds are studied in a basic model. The magnetic spectral properties are calculated in linear spin-wave theory for several stripe configurations which differ by the relative location of the stripes in the layers. We focus on the bilayer splitting of the magnon bands near the incommensurate low energy peaks as well as

C. Pennetta, E. Alfinito, L. Reggiani, S. Ruffo

The distribution of resistance fluctuations of conducting thin films with granular structure near electrical breakdown is studied by numerical simulations. The film is modeled as a resistor network in a steady state determined by the competition between two biased processes, breaking and recovery. Systems of different sizes and with different levels of inter

Renat M. Yulmetyev, Anatolii V. Mokshin, Peter Hänggi

We report the results of calculation of diffusion coefficients for Lennard-Jones liquids, based on the idea of time-scale invariance of relaxation processes in liquids. The results were compared with the molecular dynamics data for Lennard-Jones system and a good agreement of our theory with these data over a wide range of densities and temperatures was obta

A. A. Clerk, A. D. Stone

We study the noise properties and efficiency of a mesoscopic resonant-level conductor which is used as a quantum detector, in the regime where transport through the level is only partially phase coherent. We contrast models in which detector incoherence arises from escape to a voltage probe, versus those in which it arises from a random time-dependent potent

Yousuke Kobayashi, Kazuyuki Takai, Ken-ichi Fukui, Toshiaki Enoki

Superperiodic patterns were observed by STM on two kinds of finite-sized graphene sheets. One is nanographene sheets inclined from a highly oriented pyrolitic graphite (HOPG) substrate and the other is several-layer-thick graphene sheets with dislocation-network structures against a HOPG substrate. As for the former, the in-plane periodicity increased gradua

Stephan Dürr, Thomas Volz, Andreas Marte, Gerhard Rempe

Molecules are created from a Bose-Einstein condensate of atomic 87Rb using a Feshbach resonance. A Stern-Gerlach field is applied, in order to spatially separate the molecules from the remaining atoms. For detection, the molecules are converted back into atoms, again using the Feshbach resonance. The measured position of the molecules yields their magnetic m

K. L. Luhman

Ultra-cool dwarfs have been defined as dwarfs with spectral types of M7 or later (Kirkpatrick, Henry, & Irwin 1997) and thus include the new L and T spectral classes. The previous IAU report on ultra-cool dwarfs in 1999 described the optical and IR spectral features that characterize these spectral types. In this report, I review the latest progress on the s

Andrei Gruzinov

Curvature perturbations generated after the end of inflation are estimated for a generic multi-field inflationary potential. The curvature perturbations are generated by conversion of inflationary isocurvature perturbations, similar to curvaton and inhomogeneous reheating scenarios. During inflation, the trajectory along which the fields are rolling down wil

E. D. Feigelson, G. J. Babu

Despite centuries of close association, statistics and astronomy are surprisingly distant today. Most observational astronomical research relies on an inadequate toolbox of methodological tools. Yet the needs are substantial: astronomy encounters sophisticated problems involving sampling theory, survival analysis, multivariate classification and analysis, ti

Michele D. Thornley

In this review, I highlight a number of recent surveys of molecular gas in nearby spiral galaxies. Through such surveys, more complete observations of the distribution and kinematics of molecular gas have become available for galaxies with a wider range of properties (e.g., brightness, Hubble type, strength of spiral or bar structure). These studies show the

Denis Richard, Sanford S. Davis

In this note we address the issue of hydrodynamical instabilities in Astrophysical rotating shear flows in the light of recent publications focused on the possibility for differential rotation to trigger and sustain turbulence in the absence of a magnetic field. We wish to present in a synthetic form the major arguments in favor of this thesis along with a s

A. Ecuvillon, G. Israelian, N. C. Santos, M. Mayor

We present a detailed spectroscopic analysis of nitrogen abundances in 91 solar-type stars, 66 with and 25 without known planetary mass companions. All comparison sample stars and 28 planet hosts were analysed by spectral synthesis of the near-UV NH band at 3360 Åobserved at high resolution with the VLT/UVES,while the near-IR NI 7468 Åwas measured in 31 obje

Glen Petitpas, Christine Wilson

Most models of double-barred galaxies suggest that a molecular gas component is crucial for maintaining long-lived nuclear bars. We have undertaken a CO survey in an attempt to determine the gas content of these systems and to locate double barred galaxies with strong CO emission that could be candidates for high resolution mapping. We observed 10 galaxies i

Leslie K. Hunt, Kristy K. Dyer, Trinh X. Thuan, James S. Ulvestad

We present new Very Large Array observations at five frequencies, from 1.4 to 22GHz, of the extremely low-metallicity blue compact dwarf SBS0335-052. The radio spectrum shows considerable absorption at 1.49GHz, and a composite thermal+non-thermal slope. After fitting the data with a variety of models, we find the best-fitting geometry to be one with free-fre

S. Aigrain, M. Irwin

(Abridged) Space missions to search for exo-planets via the transit method, such as COROT, Eddington and Kepler, will need to address problems associated with the automated and efficient detection of planetary transits in light curves affected by a variety of noise sources, including stellar variabilility. Starting from a general purpose maximum likelihood a

L. Monaco, E. Pancino, F. R. Ferraro, M. Bellazzini

We present wide field photometry of the Galactic Globular Cluster M~22 in the B, V and I passbands for more than 186,000 stars. The study is complemented by the photometry in two narrowband filters centered on H$_α$ and the adjacent continuum, and by infrared J, H and K magnitudes derived from the 2 MASS survey for $\sim$2000 stars. Profiting from this huge

I. Jimenez-Serra, J. Martin-Pintado, A. Rodriguez-Franco, N. Marcelino

We present the detection of the SiO v=0 J=2-1 and J=3-2 lines, and of the HCO 101-000 J=3/2-1/2 F=2-1 line at ambient velocities towards the molecular outflows in L1448-mm and L1448-IRS3. This is the first detection of HCO in a dark cloud. We have also measured lines of H13CO+, H13CN, HN13C, CH3OH, and N2H+. While the HCO and the SiO lines have the narrowest

S. Van Loo, M. C. Runacres, R. Blomme

We present a theoretical model for the non-thermal radio emission from single hot stars, in terms of synchrotron radiation from electrons accelerated in wind-embedded shocks. The model is described by five independent parameters each with a straightforward physical interpretation. Applying the model to a high-quality observation of Cyg OB2 No. 9 (O5 If), we

G. Baume, A. Moitinho, E. Giorgi, G. Carraro

We present CCD broad band photometric observations in the fields of the Third Galactic Quadrant open clusters NGC 2580 and NGC 2588 ($V(I)_C$ and $UBV(RI)_C$ respectively). From the analysis of our data we found that NGC 2580 is located at a distance of about 4 kpc and its age is close to 160 Myr. As for NGC 2588, it is placed at about 5 kpc from the Sun and

Michael K. Barker, Ata Sarajedini, Jason Harris

We examine the reliability of the tip of the red giant branch (TRGB) as a distance indicator for stellar populations with different star formation histories (SFHs) when photometric errors and completeness corrections at the TRGB are small. In general, the TRGB-distance method is insensitive to the shape of the SFH except when it produces a stellar population

Juhan Kim, Changbom Park

We have developed a new halo finding method, Physically Self-Bound (PSB) group finding algorithm, which can efficiently identify halos located even at crowded regions. This method combines two physical criteria such as the tidal radius of a halo and the total energy of each particle to find member particles. Two hierarchical meshes are used to increase the s

Pawel Pietrukowicz, Janusz Kaluzny

Time-series data taken with the Hubble Space Telescope of three fields covering the central part of the globular cluster M22 have been analyzed in search of variable objects. We report identification of 11 periodic variables of which 8 are new discoveries. The sample includes 5 certain contact binaries as well as 1 SX Phe star. Two objects with periods longe

F. De Paolis, A. Geralico, G. Ingrosso, A. A. Nucita

Gravitational lensing is a well known phenomenon predicted by the General Theory of Relativity. It is now a well-developed observational technique in astronomy and is considered to be a fundamental tool for acquiring information about the nature and distribution of dark matter. In particular, gravitational lensing experiments may be used to search for black

J. Krticka, R. K. Barrett, J. C. Brown, S. P. Owocki

The Discrete Absorption Components (DACs) commonly observed in the ultraviolet lines of hot stars have previously been modelled by dynamical simulations of Corotating Interaction Regions (CIRs) in their line-driven stellar winds. Here we apply the kinematic DAC inversion method of Brown et al. to the hydrodynamical CIR models and test the reliability of the

F. V. Prigara

The standard theory of thermal radio emission encounters some difficulties. The most crucial one is nonpossibility to explain the radio spectrum of Venus in the decimeter range (Ksanfomality 1985). The radio spectra of planetary nebulae at high frequencies also are not comfortably consistent with the standard theory (Siodmiak & Tylenda 2001). Here we show th

G. A. Shanmugha Sundaram, K. R. Subramanian

Continuum observations of a solar noise storm in the frequency range of 50 - 80 MHz observed with the Gauribidanur radio spectrograph during 2000 September, 26 & 27, are presented here. The radio spectral index of the noise storm continuum in the band 50 - 80 MHz is found to be ~3.65 during the above period. The Noise Storm continuum radiation is explained a

W. D. Vacca, M. C. Cushing, J. T. Rayner

We derive general equations for non-linearity corrections and statistical uncertainty (variance) estimates for data acquired with near-infrared detectors employing correlated double sampling, multiple correlated double sampling (Fowler sampling) and uniformly-spaced continuous readout techniques. We compare our equation for the variance on each pixel associa

F. V. Prigara

An effect of stimulated radiation processes on thermal radiation from an accretion disk is considered. The radial density waves triggering flare emission and producing quasi-periodic oscillations in radiation from an accretion disk are discussed. It is argued that the observational data suggest the existence of the weak laser sources in a two-temperature pla

Alexander G. Abanov, Maxim Braverman

We study the zeta-regularized determinant of a non self-adjoint elliptic operator on a closed odd-dimensional manifold. We show that, if the spectrum of the operator is symmetric with respect to the imaginary axis, then the determinant is real and its sign is determined by the parity of the number of the eigenvalues of the operator, which lie on the positive

Jason Tumlinson, Aparna Venkatesan, J. Michael Shull

We critique the hypothesis that the first stars were very massive stars (VMS; M > 140 Msun). We review the two major lines of evidence for the existence of VMS: (1) that the relative metal abundances of extremely metal-poor Galactic halo stars show evidence of VMS enrichment, and (2) that the high electron-scattering optical depth (tau_e) to the CMB found by

James B. Hartle

We investigate the quantum theory of closed systems based on the linear positivity decoherence condition of Goldstein and Page. A quantum theory of closed systems requires two elements; 1) a condition specifying which sets of histories may be assigned probabilities that are consistent with the rules of probability theory, and 2) a rule for those probabilitie

Jin H. An, N. W. Evans, P. Hewett, P. Baillon

The POINT-AGAPE collaboration has been monitoring M31 for three seasons with the Wide Field Camera on the Isaac Newton Telescope. In each season, data are taken for one hour per night for roughly sixty nights during the six months that M31 is visible. The two fields of view straddle the central bulge, northwards and southwards. We have calculated the locatio

Tommaso Treu, Leon V. E. Koopmans

(Shortened) The combination of lensing and stellar dynamics breaks the mass-anisotropy degeneracy and provides stringent constraints on the mass distribution in early-type (E/S0) galaxies out to z~1. We present the combined results from the five field E/S0 lens galaxies at z=0.5-1.0 analyzed as part of the LSD Survey. We find: (i) Constant M/L models are rul

Jiannis K. Pachos, Martin B. Plenio

We demonstrate that in a triangular configuration of an optical lattice of two atomic species a variety of novel spin-1/2 Hamiltonians can be generated. They include effective three-spin interactions resulting from the possibility of atoms tunneling along two different paths. This motivates the study of ground state properties of various three-spin Hamiltoni

G. Duffy, S. Parkins, T. Muller, M. Sadgrove

We report the experimental observation of resonances in the early-time momentum diffusion rates for the atom-optical delta-kicked rotor. In this work a Bose-Einstein condensate provides a source of ultra-cold atoms with an ultra-narow initial momentum distribution, which is then subjected to periodic pulses (or "kicks") using an intense far-detuned o

A. Rebhan, P. van Nieuwenhuizen, R. Wimmer

We calculate the one-loop corrections to the mass and central charge of the BPS monopole in N=2 super-Yang-Mills theory in 3+1 dimensions using a supersymmetry-preserving version of dimensional regularization adapted to solitons. In the renormalization scheme where previous studies have indicated vanishing quantum corrections, we find nontrivial corrections

John Ellis, Marek Karliner, Michal Praszalowicz

We re-analyze the predictions of chiral-soliton models for the masses and decay widths of baryons in the exotic antidecuplet of flavour SU(3). The calculated ranges of the chiral-soliton moment of inertia and the π-nucleon scattering Σterm are used together with the observed baryon octet and decuplet mass splittings to estimate 1430 MeV < m_{Θ^+} < 1660 MeV}

R. A. Vicencio, M. I. Molina, Y. S. Kivshar

We demonstrate a simple method for controlling nonlinear switching of discrete solitons in arrays of weakly coupled optical waveguides, for both cubic and uadratic nonlinearities. Based on the effective discrete nonlinear equations describing the waveguide arrays in the tight-binding approximation, we develop the concept of the array engineering by means of

S. De Leo, P. Rotelli

It is well known that Yukawa potentials permit bound states in the Schrodinger equation only if the ratio of the exchanged mass to bound mass is below a critical multiple of the coupling constant. However, arguments suggested by the Darwin term imply a more complex situation. By numerically studying the Dirac equation with a Yukawa potential we investigate t

Matthias R. Gaberdiel, Peter Kaste

A generalisation of discrete torsion is introduced in which different discrete torsion phases are considered for the different fixed points or twist fields of a twisted sector. The constraints that arise from modular invariance are analysed carefully. As an application we show how all the different resolutions of the T^7/Z_2^3 orbifold of Joyce have an inter

A. Masiero, S. Profumo, S. K. Vempati, C. E. Yaguna

We revisit the phenomenology of the Constrained MSSM with right-handed neutrinos (CMSSMRN). A supersymmetric seesaw mechanism, generating neutrino masses and sizable lepton flavour violating (LFV) entries is assumed to be operative. In this scheme, we study the complementarity between the `observable ranges&#39; of various paths leading to the possible disco

Sumiyoshi Abe, A. K. Rajagopal

The forms of Euler and Gibbs-Duhem relations discussed in thermodynamics of extensive systems are shown to hold also for nonextensive systems with long-range interactions with a novel interpretation of entities appearing therein. In this way, the principles underlying Tsallis&#39; scaling relations in equilibrium nonextensive thermostatistics are clarified.

C. Chamon, P. Charbonneau, L. F. Cugliandolo, D. R. Reichman

In this paper we extend the earlier treatment of out-of-equilibrium mesoscopic fluctuations in glassy systems in several significant ways. First, via extensive simulations, we demonstrate that models of glassy behavior without quenched disorder display scalings of the probability of local two-time correlators that are qualitatively similar to that of models

Sergei V. Sharov, Andrei D. Zaikin

We argue that at sufficiently low temperatures T superconducting parity effect may strongly influence equilibrium persistent currents (PC) in isolated superconducting nanorings containing a weak link with few conducting modes. For a single channel quantum point contact at T=0 we predict a novel effect of parity-induced blocking of PC. In nanorings with SNS j

Hong Jiang, Weitao Yang

Orbital-free density functional theory as an extension of traditional Thomas-Fermi theory has attracted a lot of interest in the past decade because of developments in both more accurate kinetic energy functionals and highly efficient numerical numerical methodology. In this paper, we developed a new conjugate-gradient method for the numerical solution of sp

Richard Shurtleff

It is well known that an essentially unique free massive particle field of given spin can be constructed as a linear combination of the annihilation and creation operators for free single particle states. And the given spin determines the transformation of the field components for rotations and boosts. But the usual construction restricts translations; the c

Claude Godreche, Florent Krzakala, Federico Ricci-Tersenghi

We investigate the temporal evolution of a ferromagnetic system of Ising spins evolving under Kawasaki dynamics from a random initial condition, in spatial dimensions one and two. We examine in detail the asymptotic behaviour of the two-time correlation and response functions. The linear response is measured without applying a field, using a recently propose

A. Hildebrandt, R. Blossey, S. Rjasanow, O. Kohlbacher

The accurate modeling of the dielectric properties of water is crucial for many applications in physics, computational chemistry and molecular biology. This becomes possible in the framework of nonlocal electrostatics, for which we propose a novel formulation allowing for numerical solutions for the nontrivial molecular geometries arising in the applications

Gaston Andres Garcia

We discuss some general results on finite-dimensional Hopf algebras over an algebraically closed field k of characteristic zero and then apply them to Hopf algebras H of dimension p^{3} over k. There are 10 cases according to the group-like elements of H and H^{*}. We show that in 8 of the 10 cases, it is possible to determine the structure of the Hopf algeb

V. G. Bornyakov, H. Ichie, Y. Mori, D. Pleiter

We study the distribution of color electric flux of the three-quark system in quenched and full QCD (with N_f = 2 flavors of dynamical quarks) at zero and finite temperature. To reduce ultra-violet fluctuations, the calculations are done in the abelian projected theory fixed to the maximally abelian gauge. In the confined phase we find clear evidence for a Y

K. G. Fissum

The physics program in Hall A at Jefferson Lab commenced in the summer of 1997 with a detailed investigation of the 16O(e,e&#39;p) reaction in quasielastic, constant (q,w) kinematics at Q^2 ~ 0.8 (GeV/c)^2, q ~ 1 GeV/c, and w ~ 445 MeV. Use of a self-calibrating, self-normalizing, thin-film waterfall target enabled a systematically rigorous measurement. Diff

A. I. Mares, A. F. Otte, L. G. Soukiassian, R. H. M. Smit

The formation of gold nanowires in vacuum at room temperature reveals a periodic spectrum of exceptionally stable diameters. This is identified as shell structure similar to that which was recently discovered for alkali metals at low temperatures. The gold nanowires present two competing `magic&#39; series of stable diameters, one governed by electronic stru

Heath Emerson, Ralf Meyer

We formulate and study a new coarse (co-)assembly map. It involves a modification of the Higson corona construction and produces a map dual in an appropriate sense to the standard coarse assembly map. The new assembly map is shown to be an isomorphism in many cases. For the underlying metric space of a group, the coarse co-assembly map is closely related to

Chris Dams, Ronald Kleiss

We derive the Feynman rules of the standard model in the axial gauge. After this we prove that the fields $ϕ_W$ and $ϕ_Z$ do not correspond to physical particles. As a consequence, these fields cannot appear as incoming or outgoing lines in Feynman graphs. We then calculate the contribution of these fields in the case of a particular decay mode of the top qu

Y. Sidis, S. Pailhès, B. Keimer, P. Bourges

The observation of an unusual spin resonant excitation in the superconducting state of various High-Tc ~copper oxides by inelastic neutron scattering measurements is reviewed. This magnetic mode % (that does not exist in conventional superconductors) is discussed in light of a few theoretical models and likely corresponds to a spin-1 collective mode.

Alfredo Iorio

Kaluza-Klein reduction of the 3-dimensional gravitational Chern-Simons term leads to a 2-dimensional theory that supports a symmetry breaking solution and an associated kink interpolating between AdS and dS geometries.

A. -Z. Dubnickova, S. Dubnicka, A. Liptaj, R. Pekarik

The present situation on a comparison of theoretical evaluation of the muon anomalous magnetic moment with experimental one is roughly reviewed. Then by means of a recently elaborated unitary and analytic model of the meson transition form factors the contributions of $e^+e^-\to P(S) γ$ processes to muon $g-2$ is estimated.

J. -L. Kneur, A. Neveu, M. B. Pinto

Improving perturbation theory via a variational optimization has generally produced in higher orders an embarrassingly large set of solutions, most of them unphysical (complex). We introduce an extension of the optimized perturbation method which leads to a drastic reduction of the number of acceptable solutions. The properties of this new method are studied

Takuya Ohno, Gaku Arakawa, Ikuo Ichinose, Tetsuo Matsui

We study the phase structure of the random-plaquette Z_2 lattice gauge model in three dimensions. In this model, the &#34;gauge coupling&#34; for each plaquette is a quenched random variable that takes the value βwith the probability 1-p and -βwith the probability p. This model is relevant for the recently proposed quantum memory of toric code. The parameter

Jean-Pierre Eckmann, Lai-Sang Young

We study heat transport in the context of Hamiltonian and related stochastic models with nearest-neighbor coupling, and derive a universal law for the temperature profiles of a large class of such models. This law contains a parameter $α$, and is linear only when $α=1$. The value of $α$ depends on energy-exchange mechanisms, including the range of motion of

Daisuke Kadoh, Yoshio Kikukawa

We consider a numerical method to solve the local cohomology problem related to the gauge anomaly cancellation in U(1) chiral gauge theories. In the cohomological analysis of the chiral anomaly, it is required to carry out the differentiation and the integration of the anomaly with respect to the continuous parameter for the interpolation of the admissible g

R. de la Fuente Marcos, C. de la Fuente Marcos

We have derived the star formation history of the Milky Way disk over the last 2 Gyr from the age distribution diagram of a large sample of open clusters comprising more than 580 objects. By interpreting the age distribution diagram using numerical results from an extensive library of N-body calculations carried out during the last ten years, we reconstruct