October 1999 arXiv papers — page 9

J. Houdayer, O. C. Martin

The problem of the survival of a spin glass phase in the presence of a field has been a challenging one for a long time. To date, all attempts using equilibrium Monte Carlo methods have been unconclusive. In their comment to our paper, Marinari, Parisi and Zuliani use out-of-equilibrium measurements to test for an Almeida-Thouless line. In our view such a dy

Albert-Laszlo Barabasi, Reka Albert

Systems as diverse as genetic networks or the world wide web are best described as networks with complex topology. A common property of many large networks is that the vertex connectivities follow a scale-free power-law distribution. This feature is found to be a consequence of the two generic mechanisms that networks expand continuously by the addition of n

Ya. M. Blanter, H. Schomerus, C. W. J. Beenakker

We calculate the cumulants of the charge transmitted through a chaotic cavity in the limit that the two openings have a large number of scattering channels. The shot noise, which is the second cumulant, is known to be insensitive to dephasing in this limit. Unexpectedly, the fourth and higher cumulants are found to depend on dephasing: A semiclassical theory

A. D. Bruce, A. N. Jackson, G. J. Ackland, N. B. Wilding

We present a Monte Carlo method for the direct evaluation of the difference between the free energies of two crystal structures. The method is built on a lattice-switch transformation that maps a configuration of one structure onto a candidate configuration of the other by `switching' one set of lattice vectors for the other, while keeping the displaceme

E. C. Marino

A fully quantized field theory is developped for the skyrmion topological excitations of the O(3) symmetric CP$^1$-Nonlinear Sigma Model in 2+1D. The method allows for the obtainment of arbitrary correlation functions of quantum skyrmion fields. The two-point function is evaluated in three different situations: a) the pure theory; b) the case when it is coup

G. Ganbold

The main quasi-particle characteristics of the one-dimensional polaron are estimated within and beyond the most general Gaussian approximation at arbitrary electron-phonon coupling. We have derived explicitly the ground-state energy and the effective mass in the weak- and strong-coupling regimes. For arbitrary coupling, the Gaussian leading-order term of the

Frederic Faure

We consider periodic quantum Hamiltonians on the torus phase space (Harper-like Hamiltonians). We calculate the topological Chern index which characterizes each spectral band in the generic case. This calculation is made by a semi-classical approach with use of quasi-modes. As a result, the Chern index is equal to the homotopy of the path of these quasi-mode

A. Puente, M. Casas, Ll. Serra

A semiclassical Thomas-Fermi method, including a Weizsäcker gradient term, is implemented to describe ground states of two dimensional nanostructures of arbitrary shape. Time dependent density oscillations are addressed in the same spirit using the corresponding semiclassical time-dependent equations. The validity of the approximations is tested, both for gr

C. Jurecka, W. Brenig

We present a theory of phonon-assisted optical two-magnon absorption in two-leg spin-ladders. Based on the strong intra-rung-coupling limit we show that collective excitations of total spin S=0, 1 and 2 exist outside of the two-magnon continuum. It is demonstrated that the singlet collective state has a clear signature in the optical spectrum.

Frank Epperlein, Thomas Vojta, Michael Schreiber

We numerically investigate the transport properties of interacting spinless electrons in disordered systems. We use an efficient method which is based on the diagonalization of the Hamiltonian in the subspace of the many-particle Hilbert space which is spanned by the low-energy Slater states. Low-energy properties can be calculated with an accuracy comparabl

J. E. Han, E. Koch, O. Gunnarsson

We study the influence of the lattice structure, the Jahn-Teller effect and the Hund's rule coupling on a metal-insulator transition in AnC60 (A= K, Rb). The difference in lattice structure favors A3C60 (fcc) being a metal and A4C60 (bct) being an insulator, and the coupling to Hg Jahn-Teller phonons favors A4C60 being nonmagnetic. The coupling to Hg (Ag

Yu. G. Pashkevich, A. E. Filippov

The processes of Coulomb gas ordering in 3D layered system are studied by means of Brownian dynamics approach. It is found that at different densities of the carriers the 3D lattice of charges as well as new specific structures are possible in the system. In particular, at some small density the particles inside the layers can associate into droplets that co

A. N. Lavrov, Yoichi Ando, Kouji Segawa

We present a study of the in-plane and out-of-plane magnetoresistance (MR) in heavily-underdoped, antiferromagnetic YBa_2Cu_3O_{6+x}, which reveals a variety of striking features. The in-plane MR demonstrates a "d-wave"-like anisotropy upon rotating the magnetic field H within the ab plane. With decreasing temperature below 20-25 K the system acquire

Baigeng Wang, Jian Wang, Hong Guo

We present a theoretical analysis of the nonlinear bias and temperature dependence of current-voltage characteristics of a spin-valve device which is formed by connecting a quantum dot to two ferromagnetic electrodes whose magnetic moments orient at an angle $θ$ with respect to each other. The theory is based on nonequilibrium Green's function approach a

C. Reichhardt, A. van Otterlo, G. T. Zimanyi

We overview several recent experimental and numerical observations, which are at odds with the Vortex Glass theory of the freezing of disordered vortex matter. To reinvestigate the issue, we performed numerical simulations of the overdamped London - Langevin model, and use finite size scaling to analyze the data. Upon approaching the transition the initial V

Yosef Ashkenazy, Luca Bonci, Jacob Levitan, Roberto Roncaglia

We investigate the decay process from a time dependent potential well in the semiclassical regime. The classical dynamics is chaotic and the decay rate shows an irregular behavior as a function of the system parameters. By studying the weak-chaos regime we are able to connect the decay irregularities to the presence of nonlinear resonances in the classical p

S. H. Lubow, M. Seibert, P. Artymowicz

We analyze the nonlinear, two-dimensional response of a gaseous, viscous protoplanetary disk to the presence of a planet of one Jupiter mass (1 M_J) and greater that orbits a 1 solar mass star by using the ZEUS hydrodynamics code with high resolution near the planet's Roche lobe. The planet is assumed to be in a circular orbit about the central star and is n

Anthony N. Aguirre

Recently Van Putten has suggested that superradiance of magnetosonic waves in a toroidal magnetosphere around a Kerr black hole may play a role in the central engine of gamma-ray bursts. In this context, he computed (in the WKB approximation) the superradiant amplification of scalar waves confined to a thin equatorial wedge around a Kerr hole and found that

I. D. Karachentsev, M. E. Sharina, E. K. Grebel, A. E. Dolphin

We present ground-based and HST WFPC2 imaging of the nearby low surface brightness dwarf spheroidal galaxy DDO 44. For the first time DDO 44 was resolved into stars. The resulting color-magnitude diagram for about 1290 stars shows the red giant branch with a tip at I=(23.55+-0.15) mag, which yields a distance of (3.2+-0.2) Mpc consistent with membership of D

L. Subr, V. Karas

We further investigate the long-term evolution of a trajectory of a stellar-mass orbiter which is gravitationally bound to a massive central body. The orbiter undergoes repetitionary collisions with an accretion disc. We consider eccentric orbits intersecting the disc once or twice per each revolution, and we solve the equations for osculating elements. We f

R. E. Mennickent, C. Sterken, W. Gieren, E. Unda

We present results of differential photometry of the dwarf nova RZ Leonis spanning a 11-year baseline. The most striking feature of the light curve is a non-coherent periodic hump of variable amplitude. A seasonal time series analysis yields a photometric period of 0.0756(12) d. In addition, low amplitude fluctuations of the mean magnitude in time scale of m

L. M. Young

Previous searches for atomic gas in our Galaxy's dwarf spheroidal companions have not been complete enough to settle the question of whether or not these galaxies have HI, especially in their outer parts. We present new observations of the dwarf spheroidals Sextans, Leo I, Ursa Minor, and Draco, using the NRAO 140-foot telescope to search much farther in

Asantha R. Cooray, Wayne Hu

We study contributions to the cosmic microwave background (CMB) bispectrum from non-Gaussianity induced by secondary anisotropies during reionization. Large-scale structure in the reionized epoch both gravitational lenses CMB photons and produces Doppler shifts in their temperature from scattering off electrons in infall. The resulting correlation is potenti

P. Colin, A. Klypin

We make available to the public 4 dark matter simulations that cover 4 CDM cosmological models and were run with the AP^3M code (Couchamn 1991). These simulations are described in Colin et al. (ApJ, 523, 32, 1999). There are about 20 epochs available per model. They were run in a 30 Mpc/h box and have 128^3 particles in a 128^3 mesh. To download the binary d

A. A. Coley

The qualitative properties of spatially homogeneous stiff perfect fluid and minimally coupled massless scalar field models within general relativity are discussed. Consequently, by exploiting the formal equivalence under conformal transformations and field redefinitions of certain classes of theories of gravity, the asymptotic properties of spatially homogen

Trevor C. Weekes

A report on the observational status of VHE astronomy is given.

D. Lin, I. A. Smith, M. Bottcher, E. P. Liang

Using the data from the Rossi X-ray Timing Explorer (RXTE), we report the different energy dependence of the variability of the four persistent hard X-ray sources in the low-hard state: Cygnus X-1, GX 339-4, GRS 1758-258 and 1E 1740.7-2942. Cygnus X-1 is found to have a flatter power density spectrum (PDS) shape at higher energies. The other three sources ha

K. R. Müller, G. Wegner, W. Freudling

Radial velocities and central velocity dispersions are derived for 238 E/S0 galaxies from medium-resolution spectroscopy. New spectroscopic data have been obtained as part of a study of the Fundamental Plane distances and peculiar motions of early-type galaxies in three selected directions of the South Equatorial Strip, undertaken in order to investigate the

D. A. Noever, J. A. Phillips, J. M. Horack, G. Jerman

On 17 November 1998, a helium-filled weather balloon was launched into the stratosphere, equipped with a xerogel microparticle collector. The three-hour flight was designed to sample the dust environment in the stratosphere during the Leonid meteor shower, and possibly to capture Leonid meteoroids. Environmental Scanning Electron Microscope analyses of the r

F. Masset

We present an efficient and simple modification of the standard transport algorithm used in explicit eulerian fixed polar grid codes, aimed at getting rid of the average azimuthal velocity when applying the Courant condition. This results in a much larger timestep then the usual procedure, and it is particularly well-suited to the description of a Keplerian

I. Csabai, A. J. Connolly, A. S. Szalay, T. Budavari

We present a novel approach to photometric redshifts, one that merges the advantages of both the template fitting and empirical fitting algorithms, without any of their disadvantages. This technique derives a set of templates, describing the spectral energy distributions of galaxies, from a catalog with both multicolor photometry and spectroscopic redshifts.

P. Morel, J. Provost, G. Berthomieu

The evolution of a solar model is initialized with homogeneous models of either, pre-main sequence (P-models) or, zero-age main sequence (Z-models). The zero-age of a solar model is conventionally referenced as the time where the nuclear reactions just begin to dominate gravitation as the primary source of energy. Fixing the physics, we found that the struct

T. Ekholm, P. Lanoix, P. Teerikorpi, G. Paturel

A sample of 32 galaxies with accurate distance moduli from the Cepheid PL-relation (Lanoix 1999) has been used to study the dynamical behaviour of the Local (Virgo) supercluster. We used analytical Tolman-Bondi (TB) solutions for a spherically symmetric density excess embedded in the Einstein-deSitter universe (q_0=0.5). Using 12 galaxies within Theta=30 deg

S. V. Kalenskii, V. G. Promislov, A. V. Alakoz, A. Winnberg

A survey of 27 galactic star-forming regions in the 6_K-5_K, 5_K-4_K, and 8_K-7_K CH3CN lines at 110, 92, and 147 GHz, respectively, is made. Twenty-five sources are detected at 110 GHz, nineteen at 92 GHz, and three at 147 GHz. The strongest CH3CN emission arise in hot cores in the regions of massive star formation. CH3CN abundance in these objects is large

I. Ferreras, J. Silk

A simple chemical enrichment model for cluster early-type galaxies is described in which the mechanisms considered in the evolutionary model are infall of primordial gas, outflows and a possible variation in the star formation efficiency. We find that - within the framework of our models - only outflows can generate a suitable range of metallicities. The che

T. Oosterbroek, M. Orlandini, A. N. Parmar, L. Angelini

A new pulsar, 1SAX J1452.8-5949, was discovered during a BeppoSAX galactic plane survey on 1999 July 20 at R.A.=14h 52m 49s, Dec=-59 49' 18'' (J2000) with a 90% confidence uncertainty radius of 50''. Coherent pulsations were detected with a barycentric period of a 437.4 +/- 1.4 s. The X-ray spectrum can be modeled by a power-law with a ph

Yu. N. Parijskij, W. M. Goss, O. V. Verkhodanov, A. I. Kopylov

VLA maps obtained at 1.4 GHz with a resolution of 2\farcs5$\times$2\arcsec for three sources and 6\farcs5$\times$2\farcs3 for two sources detected in the RATAN-600 Zenith survey of 1988 have been analyzed. All five objects have an extended structure. Continuous radio spectra of these objects prepared by using the CATS database and RATAN-600 observations are

C. J. Conselice, J. S. Gallagher, D. Calzetti, N. Homeier

We present a panchromatic study of nearby starburst galaxies from the ultraviolet to the visible, including narrow band H(alpha) using WIYN and HST data, to determine how star formation processes affect the morphology and integrated fluxes of nearby starbursts. We find the UV/H(alpha) morphology of starbursts tend to differ, although not in a standard or pre

S. K. Saha, P. Venkatakrishnan

The technique of Blind Iterative De-convolution (BID) was used to remove the atmospherically induced point spread function (PSF) from short exposure images of two binary stars, HR 5138 and HR 5747 obtained at the cassegrain focus of the 2.34 meter Vainu Bappu Telescope(VBT), situated at Vainu Bappu Observatory (VBO), Kavalur. The position angles and separati

J. S. Gallagher, C. J. Conselice, R. F. G. Wyse, ;

Dwarf ellipticals have the lowest stellar densities of any galaxies, but paradoxically are most common in the densest regions of the universe, and are especially frequent in rich clusters of galaxies. Simple estimates suggest that low luminosity dwarf ellipticals should be subject to substantial tidal heating in rich clusters if most of their mass is in the

M. A. Guerrero, L. F. Miranda, A. Manchado, R. Vazquez

Narrow-band H$α$ and [N {\sc ii}] images and high-dispersion spatially-resolved echelle spectroscopy of the planetary nebula NGC 6891 are presented. These observations show a great wealth of structures. The bright central nebula is surrounded by an attached shell and a detached outer halo. Both the inner and intermediate shells can be described as ellipsoids

Ludovic Berthier, Jean-Louis Barrat, Jorge Kurchan

We investigate a general scenario for ``glassy'' or ``jammed'' systems driven by an external, non-conservative force, analogous to a shear force in a fluid. In this scenario, the drive results in the suppression of the usual aging process, and the correlation and response functions become time translation invariant. The relaxation time and th

P. Kanti, E. Winstanley

We consider hairy black hole solutions of Einstein-Yang-Mills-Dilaton theory, coupled to a Gauss-Bonnet curvature term, and we study their stability under small, spacetime-dependent perturbations. We demonstrate that the stringy corrections do not remove the sphaleronic instabilities of the coloured black holes with the number of unstable modes being equal t

Abhay Ashtekar, Alejandro Corichi

Mechanics of non-rotating black holes was recently generalized by replacing the static event horizons used in standard treatments with `isolated horizons.' This framework is extended to incorporate dilaton couplings. Since there can be gravitational and matter radiation outside isolated horizons, now the fundamental parameters of the horizon, used in mec

Adrian Kent

In a secure bit commitment protocol involving only classical physics, A commits either a 0 or a 1 to B. If quantum information is used in the protocol, A may be able to commit a state of the form $α\ket{0} + β\ket{1}$. If so, she can also commit mixed states in which the committed bit is entangled with other quantum states under her control. We introduce her

Nikolai Laskin

The fractional quantum and statistical mechanics have been developed via new path integrals approach.

G. M. Williger, A. Smette, C. Hazard, J. A. Baldwin

We present a search for spatial and redshift correlations in a 2 A resolution spectroscopic survey of the Lyman alpha forest at 2.15 < z < 3.37 toward ten QSOs concentrated within a 1-degree diameter field. We find a signal at 2.7 sigma significance for correlations of the Lyman alpha absorption line wavelengths between different lines of sight over the whol

Xiao-jun Li, M. Schick

We consider a model of lipids in which a head group, characterized by its volume, is attached to two flexible tails of equal length. The phase diagram of the anhydrous lipid is obtained within self-consistent field theory, and displays, as a function of lipid architecture, a progression of phases: body-centered cubic, hexagonal, gyroid, and lamellar. We then

G. Lawes, S. C. J. Kingsley, N. Mulders, J. M. Parpia

We have investigated the superfluid transition of He-3 in a 99.5% porosity silica aerogel. This very dilute sample shows behaviour intermediary between bulk He-3 and He-3 confined to the denser aerogels previously studied. We present data on both the superfluid transition temperature and the superfluid density and compare our results with previous measuremen

Sheldon Stone

I discuss what measurements need to be done to search for physics beyond the Standard CKM model, rather than just what studies can be done in the near future. It is also important to accurately measure the CKM matrix elements. Current best estimates for two important elements are: |V_{cb}|=0.0381 +/- 0.0021 and |V_{ub}/V_{cb}|=0.085 +/- 0.019. Finally, futur

Niclas Wyllard

We study N=4 supersymmetric quantum-mechanical many-body systems with M bosonic and 4M fermionic degrees of freedom. We also investigate the further restrictions of conformal and superconformal invariance. In particular, we construct conformal N=4 extensions of the A_{M-1} Calogero models, which for generic values of the coupling constant are not SU(1,1|2) s

Krzysztof A. Meissner, Marek Olechowski

We present a new solution in the heterotic M-theory in which the metric depends on (cosmic) time. The solution preserves N=1 supersymmetry in 4 dimensions in the leading order of the $κ^{2/3}$ expansion. It is the first example of the time-dependent supersymmetric solution in M-theory on $S^1/Z_2$. It describes expanding 4-dimensional space-time with shrinki

Pieter Kok, Samuel L. Braunstein

We study the use of detection devices in entanglement-based state preparation. In particular we consider optical detection devices such as single-photon sensitivity detectors, single-photon resolution detectors and detector cascades (with an emphasis on the performance of realistic detectors). We develop an extensive theory for the use of these devices. In e

J. S. Penttila, U. Parts, P. J. Hakonen, M. A. Paalanen

We have investigated asymptotic behavior of normal tunnel junctions at voltages where even the best ohmic environments start to look like RC transmission lines. In the experiments, this is manifested by an exceedingly slow approach to the linear behavior above the Coulomb gap. As expected on the basis of the quantum theory taking into account interaction wit

Ulf Lindstrom, Maxim Zabzine, Aleksandr Zheltukhin

For background geometries whose metric contain a scale $γ$ we reformulate the Born-Infeld D-brane action in terms of $ε\equiv γ/(2πα&#39;)$. This may be taken as a starting point for various perturbative treatments of the theory. We study two limits that arise at zeroth order of such perturbations. In the first limit, that corresponds to the $g_s\to\infty$ w

Helen R. Eisenberg, Daniel kandel

We propose a physical model which explains the existence of finite thickness wetting layers in epitaxially strained films. The finite wetting layer is shown to be stable due to the variation of the non-linear elastic free energy with film thickness. We show that anisotropic surface tension gives rise to a metastable enlarged wetting layer. The perturbation a

Zhenjun Xiao, Chong Sheng Li, Kuang-Ta Chao

We calculate the enhancements to the inclusive charmless decays of b quark, $b \to s g, s q\bar{q}, sgg$, from gluon penguin diagrams induced by the charged and neutral Higgs bosons $(H^{\pm}, h^0, H^0$, and A^0) in the Two-Higgs-Doublet Model with flavor-changing couplings. Within the considered parameter space, the new contributions from charged Higgs boso

Alessandro Pelizzola

The cluster variation - Pade` approximant method is a recently proposed tool, based on the extrapolation of low/high temperature results obtained with the cluster variation method, for the determination of critical parameters in Ising-like models. Here the method is applied to the three-dimensional simple cubic Ising model, and new results, obtained with an

C. Kiefer, D. Polarski, A. A. Starobinsky

Gravitons produced from quantum vacuum fluctuations during an inflationary stage in the early Universe have zero entropy as far as they reflect the time evolution (squeezing) of a pure state, their large occupation number notwithstanding. A non-zero entropy of the gravitons (classical gravitational waves (GW) after decoherence) can be obtained through coarse

L. Chayes, Leonid P. Pryadko, Kirill Shtengel

We consider a general class of (intersecting) loop models in D dimensions, including those related to high-temperature expansions of well-known spin models. We find that the loop models exhibit some interesting features - often in the ``unphysical&#39;&#39; region of parameter space where all connection with the original spin Hamiltonian is apparently lost.

Buoyu Hou, Dantao Peng, Ruihong Yue

The Bethe ansatz equations of the 1-D SU(3) Hubbard model are systematically derived by diagonalizing the inhomogeneous transfer matrix of the XXX model. We first derive the scattering matrix of the SU(3) Hubbard model through the coordinate Bethe ansatz method. Then, with the help quantum inverse scattering method we solve the nested transfer matrix and giv

Victor T. Kim, Victor A. Matveev, Grigorii B. Pivovarov, James P. Vary

Without a gauge fixing, canonical variables for the light-front SU(2) gluodynamics are determined. The Gauss law is written in terms of the canonical variables. The system is qualified as a generalized dynamical system with first class constraints. Abeliazation is a specific feature of the formulation (most of the canonical variables transform nontrivially o

Mark Mandelkern, Jonas Schultz

We propose a construction of frequentist confidence intervals that is effective near unphysical regions and unifies the treatment of two-sided and upper limit intervals. It is rigorous, has coverage, is computationally simple and avoids the pathologies that affect the Likelihood Ratio and related constructions. Away from non-physical regions, the results are

D. Korotkin, N. Manojlovic, H. Samtleben

Schlesinger transformations are discrete monodromy preserving symmetry transformations of the classical Schlesinger system. Generalizing well-known results from the Riemann sphere we construct these transformations for isomonodromic deformations on genus one Riemann surfaces. Their action on the system&#39;s tau-function is computed and we obtain an explicit

Martin B. Plenio

Landauer&#39;s principle states that the erasure of information generates a corresponding amount of entropy in the environment. We show that Landauer&#39;s principle provides an intuitive basis for Holevo bound on the classical capacity of a quantum channel.

G. Mauro D&#39;Ariano, Massimiliano F. Sacchi, Prem Kumar

We propose a general method for measuring an arbitrary observable of a multimode electromagnetic field using homodyne detection with a single local oscillator. In this method the local oscillator scans over all possible linear combinations of the modes. The case of two modes is analyzed in detail and the feasibility of the measurement is studied on the basis

V. Roudnev, S. Yakovlev

Precise numerical calculations of bound states of a three-atomic Helium cluster are performed. The modern techniques of solution of Faddeev equations are combined to obtain an efficient numerical scheme. Binding energies and other observables for ground and excited states are calculated. Geometric properties of the clusters are discussed.

R. D. Pisarski, D. H. Rischke

We derive perturbatively the gap equations for a color-superconducting condensate with total spin J=0 in dense QCD. At zero temperature, we confirm the results of Son for the dependence of the condensate on the coupling constant, and compute the prefactor to leading logarithmic accuracy. At nonzero temperature, we find that to leading order in weak coupling,

M. V. Andres, E. G. Lanza, P. Van Isacker, C. Volpe

The effect of deformation on the excitation of multiple giant dipole resonances is studied. Analytical expressions are derived in the framework of the interacting boson model for the energies and E1 properties of giant dipole resonances in spherical and deformed nuclei, and a numerical treatment of transitional nuclei is proposed. Coulomb-excitation cross se

Johanna Gaier, Jakob Yngvason

The Tomita-Takesaki modular groups and conjugations for the observable algebras of space-like wedges and the vacuum state are computed for translationally covariant, but possibly not Lorentz covariant, generalized free quantum fields in arbitrary space-time dimension d. It is shown that for $d\geq 4$ the condition of geometric modular action (CGMA) of Buchho

Vicente Muñoz

We produce an equality between the Gromov-Witten invariants of the moduli space M of rank two odd degree stable vector bundles over a Riemann surface $Σ$ and the Donaldson invariants of the algebraic surface $Σ\times P^1$. We discuss on to how extent the Quantum cohomology of M determines its Gromow-Witten invariants. Finally we find the isomorphism between

Martin Andler, Alexander Dvorsky, Siddhartha Sahi

We study Kontsevich&#39;s deformation quantization for the dual of a finite-dimensional real Lie algebra (or superalgebra) g. In this case the Kontsevich star-product defines a new convolution on S(g), regarded as the space of distributions supported at 0 in g. For p in S(g), we show that the convolution operator f->f*p is a differential operator with analyt

C. Duval, P. Lecomte, V. Ovsienko

This article is a survey of recent work of the authors developing a new approach to quantization based on the equivariance with respect to some Lie group of symmetries. Examples are provided by conformal and projective differential geometry: given a smooth manifold M endowed with a flat conformal/projective structure, we establish a canonical isomorphism bet

Tom Banks, Lubos Motl

We construct the matrix description for a twisted version of the IIA string theory on S^1 with fermions antiperiodic around a spatial circle. The result is a 2+1-dimensional U(N) x U(N) nonsupersymmetric Yang-Mills theory with fermionic matter transforming in the (N,Nbar). The two U(N)&#39;s are exchanged if one goes around a twisted circle of the worldvolum

Luis A. Cabral, Victor O. Rivelles

We consider relativistic and non-relativistic particles and strings in spaces (or space-times) with a degenerate metric. We show that the resulting dynamics is described by a rich structure of constraints. All constraints are classified and the dynamics depends strongly on the parity of the difference between the dimension of the space (or space-time) and th

Mu-In Park, Jeongwon Ho

In a recent letter, Carlip proposed a generalization of the Brown-Henneaux-Strominger construction to any dimension. We present two criticisms about his formulation.

A. Ghinculov, Y. P. Yao

We give an algorithm for obtaining expansions of massive two-loop Feynman graphs in powers of the external momentum around a finite, nonzero value of the momentum. This is based on our general two-loop formalism to reduce massive two-loop graphs with renormalizable interactions into a standard set of special functions. After the algebraic reduction, the fina

Lorenzo Magnea, Stefano Forte

Evolution equations for parton distributions can be approximately diagonalized and solved in moment space without assuming any knowledge of the parton distribution in the region of small x. The evolution algorithm for truncated moments is simple and rapidly converging. Examples of applications are outlined.

J. A. Casas, J. R. Espinosa, A. Ibarra, I. Navarro

The neutral leptonic sector of the Standard Model presumably consists of three neutrinos with non-zero Majorana masses with properties further determined by three mixing angles and three CP-violating phases. We derive the general renormalization group equations for these physical parameters and apply them to study the impact of radiative effects on neutrino

Gabriel Karl

This note emphasizes that due to isospin violation the two central states in the octet mix, and this mixing can be measured in semileptonic decays, in particular with an accurate determination of the sigma plus semileptonic branching ratio.

Hans-Ulrich Martyn, Grahame A. Blair

A case study will be presented to determine the particle masses and parameters of a specific mSUGRA model at the TESLA Linear Collider with high precision.

Johan Bijnens

In this talk I describe work on computing non-leptonic matrix elements consistently with both long and short distance contributions included. On the simpler example of the $π^+$-$π^0$ mass difference I explain in detail the matching procedure and the difference between various low-energy models. I then explain the new difficulties in non-leptonic Kaon decays

Gianluca Oderda, George Sterman

We discuss a formalism in which high-$p_T$ dijet rapidity gaps are identified by energy flow in the interjet region. When the gap energy, $Q_{\rm gap}$, is sufficiently large, the cross section may be computed from standard factorization theorems. For $p_T\gg Q_T\ggΛ_{\rm QCD}$, this is a two-scale perturbative problem, in which we may resum logarithms of $Q

Gabriel Karl, Jack Paton

We discuss the ``spectroscopy&#39;&#39; of gluonic states in systems with two space dimensions, using simple models to mimic the results of lattice gauge theory computations. We first discuss the quantum numbers of these systems, including charge conjugation. Two types of systems are discussed in detail: ``gluelumps&#39;&#39; which have a heavy adjoint color

Matteo Cacciari

Soft-gluon resummation within the framework of heavy quarkonium hadroproduction is considered. A few selected cases are studied in detail. A sizeable increase of the cross sections with respect to the next-to-leading order predictions with central factorization/renormalization scale choice can generally be observed. Improvements in the dependence of the cros

Robert H. Brandenberger

These lecture notes intend to form a short pedagogical introduction to inflationary cosmology, highlighting selected areas of recent progress such as reheating and the theory of cosmological perturbations. Problems of principle for inflationary cosmology are pointed out, and some new attempts at solving them are indicated, including a nonsingular Universe co

Rajan Gupta

We present highlights of the spectrum of mesons and baryons calculated using NRQCD for heavy quarks and tadpole improved clover action for the light quarks.

ZEUS Collaboration

First inclusive measurements of isolated prompt photons in photoproduction at the HERA ep collider have been made with the ZEUS detector, using an integrated luminosity of 38.4 pb$^{-1}$. Cross sections are given as a function of the pseudorapidity and the transverse energy ($η^γ$, \eTg) of the photon, for $\eTg > $ 5 GeV in the $γp$ centre-of-mass energy ra

Fabrizio Palla

In this article I will review the measurements of the b quark mass performed by ALEPH and DELPHI and presented at the HEP99 Conference in Tampere. Very clean effects of the mass running are observed, even if a wide spread in the results and large systematic errors due to hadronization corrections prevent to extract an average value of the running b quark mas

ZEUS Collaboration

The forward-jet cross section in deep inelastic ep scattering has been measured using the ZEUS detector at HERA with an integrated luminosity of 6.36 pb^-1. The jet cross section is presented as a function of jet transverse energy squared, E(T,jet)^2, and Q^2 in the kinematic ranges 10^-2<E(T,jet)^2/Q^2<10^2 and 2.5 10^-4<x<8.0 10^-2. Since the perturbative

L. A. Mikaelyan

This is a short review of the present ~ 1 km baseline oscillation experi-ments at nuclear reactors. An idea of a new search for very small mixing angle oscillations at Krasnoyarsk is also mentioned.

Rong-Gen Cai, Anzhong Wang

We investigate the late-time evolution of the Yang-Mills field in the self-gravitating backgrounds: Schwarzschild and Reissner-Nordström spacetimes. The late-time power-law tails develop in the three asymptotic regions: the future timelike infinity, the future null infinity and the black hole horizon. In these two backgrounds, however, the late-time evolutio

E. Coccia, F. Fucito, J. A. Lobo, M. Salvino

We study the response and cross sections for the absorption of GW energy in a Jordan-Brans-Dicke theory by a resonant mass detector shaped as a hollow sphere.

Shingo Suzuki, Kei-ichi Maeda

A spinning test particle around a Schwarzschild black hole shows a chaotic behavior, if its spin is larger than a critical value. We discuss whether or not some peculiar signature of chaos appears in the gravitational waves emitted from such a system. Calculating the emitted gravitational waves by use of the quadrupole formula, we find that the energy emissi

Iwan Jensen

A closed plane meander of order n is a closed self-avoiding loop intersecting an infinite line 2n times. Meanders are considered distinct up to any smooth deformation leaving the line fixed. We have developed an improved algorithm, based on transfer matrix methods, for the enumeration of plane meanders. This allows us to calculate the number of closed meande

Yongmin Kim, C. H. Perry, J. A. Simmons

In-plane magnetic field photoluminescence spectra from a series of GaAs/AlGaAs coupled double quantum wells show distinctive doublet structures related to the symmetric and antisymmetric states. The magnetic field behavior of the upper transition from the antisymmetric state strongly depends on sample mobility. In lower mobility samples, the transition energ

J. Talamantes, M. Pollak, I. Varga

The problem of two electrons in a two-dimensional random potential is addressed numerically. Specifically, the role of the Coulomb interaction between electrons on localization is investigated by writing the Hamiltonian on a localized basis and diagonalizing it exactly. The result of that procedure is discussed in terms of level statistics, and the expectati

C. M. Varma

A theory for the phenomena observed in Copper-Oxide based high temperature superconducting materials derives an elusive time-reversal and rotational symmetry breaking order parameter for the observed pseudogap phase ending at a quantum-critical point near the composition for the highest $T_c$. An experiment is proposed to observe such a symmetry breaking. It

Maya Schoeck, Christoph Suergers, Hilbert v. Loehneysen

The cleaved and (2 x 1) reconstructed (111) surface of p-type Si is investigated by scanning tunneling microscopy (STM). Single B acceptors are identified due to their characteristic voltage-dependent contrast which is explained by a local energetic shift of the electronic density of states caused by the Coulomb potential of the negatively charged acceptor.

Mucio A. Continentino

Recently we have shown that a one-parameter scaling, $T_{coh}$, describes the physical behavior of several heavy fermions in a region of their phase diagram. In this paper we fully characterize this region, obtaining the uniform susceptibility, the resistivity and the specific heat in terms of the coherence temperature $T_{coh}$. This allows for an explicit