March 2000 arXiv papers — page 14

V. Pravda, A. Pravdova

Boost-rotation symmetric spacetimes are the only locally asymptotically flat axially symmetric electrovacuum spacetimes with a further symmetry that are radiative. They are realized by uniformly accelerated particles of various kinds or black holes. Their general properties are summarized. Several examples of boost-rotation symmetric solutions of the Maxwell

Mayeul Arminjon

The method of asymptotic expansions is used to build an approximation scheme relevant to celestial mechanics in relativistic theories of gravitation. A scalar theory is considered, both as a simple example and for its own sake. This theory is summarized, then the relevant boundary problem is seen to be the full initial-value problem. It is shown that, with a

László Á Gergely, Mitchell McKain

We present a geometric approach to the three-body problem in the non-relativistic context of the Barbour-Bertotti theories. The Riemannian metric characterizing the dynamics is analyzed in detail in terms of the relative separations. Consequences of a conformal symmetry are exploited and the sectional curvatures of geometrically preferred surfaces are comput

László Á Gergely

The dynamics of $N\geq 3$ interacting particles is investigated in the non-relativistic context of the Barbour-Bertotti theories. The reduction process on this constrained system yields a Lagrangian in the form of a Riemannian line element. The involved metric, degenerate in the flat configuration space, is the first fundamental form of the space of orbits o

A. Bernui, A. F. F. Teixeira

Exact expressions for probability densities of conjugate pair separation in euclidean isometries are obtained, for the cosmic crystallography.These are the theoretical counterparts of the mean histograms arising from computer simulation of the isometries. For completeness, also the isometries with fixed points are examined, as well as the orientation reversi

James A. Hoagland

In this dissertation, we present LaSCO, the Language for Security Constraints on Objects, a new approach to expressing security policies using policy graphs and present a method for enforcing policies so expressed. Other approaches for stating security policies fall short of what is desirable with respect to either policy clarity, executability, or the preci

W. -J. Zhu, C. L. Henley

We have built a database of ab-initio total energies for elemental Boron in over 60 hypothetical crystal structures of varying coordination $Z$, such that every atom is equivalent. Fitting to each subset with a particular $Z$, we extract a classical effective potential, written as a sum over coordination shells and dominated by three-atom (bond angle depende

J. A. Sanchez-Gil, J. V. Garcia-Ramos, E. R. Mendez

By means of rigorous numerical simulation calculations based on the Green's theorem integral equation formulation, we study the near EM field in the vicinity of very rough, one-dimensional self-affine fractal surfaces of Ag, Au, and Cu (for both vacuum and water propagating media) illuminated by a p polarized field. Strongly localized enhanced optical ex

R. Roth, S. Dietrich

By using the Rosenfeld density functional we determine the number density profiles of both components of binary hard-sphere fluids close to a planar hard wall as well as the corresponding excess coverage and surface tension. The comparison with published simulation data demonstrates that the Rosenfeld functional, both its original version and sophistications

Xavier Oriols, Jordi Sune

An original entity is defined to study quantum beams of conserved particles. The beam is described as a Stationary Incoherent Superposition of Wave packets (SISOW). Mean values are time-independent confirming that the SISOW describes a stationary flux of particles. The SISOW is a general entity that contains the Hamiltonian eigenstates as a particular limit.

Barbara Coluzzi, Enzo Marinari, Giorgio Parisi, Heiko Rieger

We study properties of the energy minima obtained by quenching equilibrium configurations of the Sherrington-Kirkpatrick (SK) mean field spin glass. We measure the probability distribution of the overlap among quenched configurations and the quenched energy, looking at the dependence on the starting equilibrium temperature, and performing a systematic analys

Soo-Young Lee, Sahng-Kyoon Yoo

We investigate the energy spectrum of the biaxial spin systems with magnetic field along the hard anisotropy axis by using the complex periodic orbit theory. All important features of the system appearing in whole energy range, such as oscillations of level splittings due to Wess-Zumino effect and their absence at higher magnetic field etc., can be completel

Alessandro Vespignani, Ronald Dickman, Miguel A. Munoz, Stefano Zapperi

We study sandpile models as closed systems, with conserved energy density $ζ$ playing the role of an external parameter. The critical energy density, $ζ_c$, marks a nonequilibrium phase transition between active and absorbing states. Several fixed-energy sandpiles are studied in extensive simulations of stationary and transient properties, as well as the dyn

M. G. Stachiotti, C. O. Rodriguez, C. Ambrosch-Draxl, N. E. Christensen

The electronic structure of SrBi2Ta2O9 is investigated from first-principles, within the local density approximation, using the full-potential linearized augmented plane wave (LAPW) method. The results show that, besides the large Ta(5d)-O(2p) hybridization which is a common feature of the ferroelectric perovskites, there is an important hybridization betwee

Hans-Karl Janssen, Olaf Stenull

By employing the methods of renormalized field theory we show that the percolation behavior of random resistor-diode networks near the multicritical line belongs to the universality class of isotropic percolation. We construct a mesoscopic model from the general epidemic process by including a relevant isotropy-breaking perturbation. We present a two-loop ca

Walter Kob, Claudio Brangian, Torsten Stuhn, Ryoichi Yamamoto

We discuss the efficiency of the so-called parallel tempering method to equilibrate glassy systems also at low temperatures. The main focus is on two structural glass models, SiO_2 and a Lennard-Jones system, but we also investigate a fully connected 10 state Potts-glass. By calculating the mean squared displacement of a tagged particle and the spin-autocorr

David Carpentier, Pierre Le Doussal

We study via RG, numerics, exact bounds and qualitative arguments the equilibrium Gibbs measure of a particle in a $d$-dimensional gaussian random potential with {\it translationally invariant logarithmic} spatial correlations. We show that for any $d \ge 1$ it exhibits a transition at $T=T_c>0$. The low temperature glass phase has a non trivial structure, b

Yu. Gaididei, H. Büttner

The Heisenberg antiferromagnet on a compressible triangular lattice in the spin- wave approximation is considered. It is shown that the interaction between quantum fluctuations and elastic degrees of freedom stabilizes the low symmetric L-phase with a collinear Neel magnetic ordering. Multi-stability in the dependence of the on-site magnetization on an unaxi

A. P. Menushenkov, K. V. Klementev

X-ray absorption spectra of oxide systems Ba_{1-x}K_xBiO_3 and BaPbO_3 above Bi- and Pb-L3 absorption edges were investigated. It was shown that oxygen ions move in double-well potential and their oscillations are correlated with charge carrier movement. Observed breathing-like oxygen vibration in double-well potential with large amplitude and low frequency

A. Himeda, M. Ogata

Fermi surface of the two-dimensional t-J model is studied using the variational Monte Carlo method. We study the Gutzwiller projected d-wave superconducting state with an additional variational parameter t&#39;_v corresponding to the next-nearest neighbor hopping term. It is found that the finite t&#39;_v<0 gives the lowest variational energy in the wide ran

M. Ya. Amusia, V. R. Shaginyan

The self consistent version of the density functional theory (DFT) is presented, which allows to calculate the ground state and dynamic properties of finite multi-electron systems such as atoms, molecules and clusters. The exact functional equation for the effective interaction, using which one can construct the action functional, density functional, the res

J. Cserti, G. Vattay, J. Koltai, F. Taddei

The Path-Length Spectra of mesoscopic systems including diffractive scatterers and connected to superconductor is studied theoretically. We show that the spectra differs fundamentally from that of normal systems due to the presence of Andreev reflection. It is shown that negative path-lengths should arise in the spectra as opposed to normal system. To highli

G. Cappellini, S. Bouette-Russo, B. Amadon, C. Noguera

The structural properties and the band structures of the charge-transfer insulating oxides SrO, MgO and SrTiO3 are computed both within density functional theory in the local density approximation (LDA) and in the Hedin&#39;s GW scheme for self-energy corrections, by using a model dielectric function, which approximately includes local field and dynamical ef

Ken&#39;ichi Takano

We examine a chain of periodic arrays of 4 quantum spins with magnitudes of 1/2, 1, 3/2 and 1. There are four kinds of nearest-neighbour exchange parameters among them. We choose two independent parameters for concreteness: one represents the ratio of typical exchange parameters, and the other represents a distortion. We determine the phase diagram of the gr

Karl-Peter Marzlin, Weiping Zhang, Barry C. Sanders

We propose a scheme for the creation of skyrmions (coreless vortices) in a Bose-Einstein condensate with hyperfine spin F=1. In this scheme, four traveling-wave laser beams, with Gaussian or Laguerre-Gaussian transverse profiles, induce Raman transitions with an anomalous dependence on the laser polarization, thereby generating the optical potential required

Kikuo Harigaya

Effects of the superconducting pair potential on the impurity scattering processes in metallic carbon nanotubes are studied theoretically. The backward scattering of electrons vanishes in the normal state. In the presence of the superconducting pair correlations, the backward scatterings of electron- and hole-like quasiparticles vanish, too. The impurity giv

Vladimir I. Fal&#39;ko, S. V. Iordanski

We argue that the dissipative transport in ferromagnetic quantum Hall effect liquids at $ν=2N+1$ is dominated by the thermal activation of pairs consisting of an electron and an antiskyrmion (topological texture which represents a hole with &#39;screened&#39; exchange interaction), thus manifesting the lack of electron-hole symmetry in quantum Hall ferromagn

Douglas Scott, Guilaine Lagache, Colin Borys, Scott C. Chapman

The FIRBACK (Far InfraRed BACKground) survey represents the deepest extensive 170 micron images obtained by the ISO satellite. The sources detected comprise about 10% of the Cosmic IR Background (CIB) seen by COBE, and, importantly, were observed at a wavelength near the peak of the CIB. Detailed follow-up of these sources should help pin down the redshifts,

Max Tegmark, Angelica de Oliveira-Costa, John Staren, Peter Meinhold

We present Cosmic Microwave Background (CMB) maps from the Santa Barbara HACME balloon experiment (Staren etal 2000), covering about 1150 square degrees split between two regions in the northern sky, near the stars gamma Ursae Minoris and alpha Leonis, respectively. The FWHM of the beam is about 0.77 degrees in three frequency bands centered on 39, 41 and 43

P. A. Henning, L. Staveley-Smith, R. D. Ekers, A. J. Green

A blind survey for HI bright galaxies in the southern Zone of Avoidance, (212 deg < l < 36 deg; |b| < 5 deg), has been made with the 21 cm multibeam receiver on the Parkes 64 m radiotelescope. The survey, sensitive to normal spiral galaxies to a distance of about 40 Mpc and more nearby dwarfs, detected 110 galaxies. Of these, 67 have no counterparts in the N

Norman K. Glendenning

While model-independent limits are always interesting, a limit on neutron star radius as a function of mass attains special interest in light of recent interpretations of the periodic as well as quasi-periodic oscillations (QPOs) in brightness of X-rays emitted from neutron stars that are accreting matter from a low-mass companion. Here we derive such a limi

Y. -Z. Qian

I show that recent observations of r-process abundances in metal-poor stars are difficult to explain if neutron star mergers (NSMs) are the major r-process sources. In contrast, such observations and meteoritic data on Hf182 and I129 in the early solar system support a self-consistent picture of r-process enrichment by supernovae (SNe). While further theoret

Jeroen Homan, Michiel van der Klis

We report the discovery of a 695-Hz quasi-periodic oscillation (QPO) in data taken with the Rossi X-ray Timing Explorer of the low-mass X-ray binary (LMXB) EXO 0748-676. This makes EXO 0748-676 the second dipping LMXB, after 4U 1915-05, that shows kHz QPOs. Comparison with other sources suggests that the QPO corresponds to the lower frequency peak of the kHz

W. P. Gieren, M. Gomez, J. Storm, T. J. Moffett

We report BV(RI)c CCD photometric data for a group of seven Cepheid variables in the young, rich cluster NGC 1866 in the Large Magellanic Cloud. The photometry was obtained as part of a program to determine accurate distances to these Cepheids by means of the infrared surface brightness technique, and to improve the LMC Cepheid database for constructing Ceph

Zakir F. Seidov

The method of negative density is presented which allows to obtain the analytical solutions for potential energy of new kinds of homogeneous and ihhomogeneous self-gravitating bodies. The homogeneous bispherical concavo-convex lens is considered in particular.

R. L. M. Corradi, D. R. Goncalves, E. Villaver, A. Mampaso

We present images and high-resolution spectra of the planetary nebulae IC 2553 and NGC 5882. Spatio-kinematic modeling of the nebulae shows that they are composed of a markedly elongated inner shell, and of a less aspherical outer shell expanding at a considerably higher velocity than the inner one. Embedded in the outer shells of both nebulae are found seve

A. M. Bykov, R. A. Chevalier, D. C. Ellison, Yu. A. Uvarov

In evolved supernova remnants (SNRs) interacting with molecular clouds, such as IC 443, W44, and 3C391, a highly inhomogeneous structure consisting of a forward shock of moderate Mach number, a cooling layer, a dense radiative shell and an interior region filled with hot tenuous plasma is expected. We present a kinetic model of nonthermal electron injection,

Trinh Xuan Thuan, Yuri I. Izotov

Blue compact galaxies (BCG) are ideal objects in which to derive the primordial 4He abundance because they are chemically young and have not had a significant stellar He contribution. We discuss a self-consistent method which makes use of all the brightest He I emission lines in the optical range and solves consistently for the electron density of the He II

Zakir F. Seidov

Gravitational potential energy of the homogeneous bispherical concavo-convex lens, with the equal absolute values of radii of curvature of both surfaces is studied.

Jeffrey A. Willick

I review the status of cosmic velocity analysis as of January 2000, with an emphasis on two key questions: (1) What is the scale of the largest bulk flows in the universe? and (2) What is the value of beta=Omega_m^{0.6}/b indicated by cosmic velocities, and what does this tell us about Omega_m itself? These are the most important issues for cosmic flow analy

A. Loinger

A rigorous, non-perturbative proof that there is no radiation damping of gravitational motions.

Michael Blanton

Examining the nature of the relative clustering of different galaxy types can help tell us how galaxies formed. To measure this relative clustering, I perform a joint counts-in-cells analysis of galaxies of different spectral types in the Las Campanas Redshift Survey (LCRS). I develop a maximum-likelihood technique to fit for the relationship between the den

Bruce A. Campbell, Kirk Kaminsky

We investigate the noncommutative analogue of the spontaneously broken linear sigma model at the one-loop quantum level. In the commutative case, renormalization of a theory with a spontaneously broken continuous global symmetry depends on cancellations that enable the limited set of counterterms consistent with that symmetry to remove the divergences even a

Randy Lewis, R. M. Woloshyn

The mass spectrum of S and P-wave mesons containing a single heavy quark is computed in the quenched approximation, using NRQCD up to third order in the inverse heavy quark mass expansion. Previous results found third order contributions which are as large in magnitude as the total second order contribution for the charmed S-wave spin splitting. The present

Duane A. Dicus, Kristin Kovner, Wayne W. Repko

We compute the contribution of Kaluza-Klein graviton exchange to the cross section for photon-neutrino scattering. Unlike the usual situation where the virtual graviton exchange represents a small correction to a leading order electroweak or strong amplitude, in this case the graviton contribution is of the same order as the electroweak amplitude, or somewha

K. G. Chetyrkin, Stephan Narison

Including the radiative perturbative corrections and the short distance tachyonic gluon mass effects which mimic the ones of UV renormalons, we re-estimate the decay amplitudes, masses and widths of light hybrid mesons from QCD spectral sum rules. We show that the effects are tiny and confirm the previous lowest order results. We discuss the phenomenological

J. X. Lu

In this short note, we try to clarify a seemly trivial but often confusing question in relating a higher-dimensional physical gravitational constant to its lower-dimensional correspondence in Kaluza-Klein reduction. In particular, we re-derive the low-energy M-theory gravitational constant in terms of type IIA string coupling $g_s$ and constant $α&#39;$ thro

Leticia F. Cugliandolo, Daniel R. Grempel, Constantino A. da Silva Santos

We study the spin-glass transition in a disordered quantum model. There is a region in the phase diagram where quantum effects are small and the phase transition is second order, as in the classical case. In another region, quantum fluctuations drive the transition first order. Across the first order line the susceptibility is discontinuous and shows hystere

Louis Vervoort

For all Einstein-Podolsky-Rosen-type experiments on deterministic systems the Bell inequality holds, unless non-local interactions exist between certain parts of the setup. Here we show that in nonlinear systems the Bell inequality can be violated by non-local effects that are arbitrarily weak. Then we show that the quantum result of the existing Einstein-Po

H. Boehringer, W. Voges, J. P. Huchra, B. McLean

In the construction of an X-ray selected sample of galaxy clusters for cosmological studies, we have assembled a sample of 495 X-ray sources found to show extended X-ray emission in the first processing of the ROSAT All-Sky Survey. The sample covers the celestial region with declination $δ\ge 0°$ and galactic latitude $|b_{II}| \ge 20°$ and comprises sources

W. Rodejohann

Using a three neutrino framework we investigate bounds for the effective Majorana neutrino mass matrix. The mass measured in neutrinoless double beta decay is its (11) element. Lepton-number and -flavor violating processes sensitive to each element are considered and limits on branching ratios or cross sections are given. Those processes include $μ^- e^+$ co

R. Roth, H. Feldmeier

The stability of trapped dilute Fermi gases against collapse towards large densities is studied. A hermitian effective contact-interaction for all partial waves is derived, which is particularly suited for a mean-field description of these systems. Including the s- and p-wave parts explicit stability conditions and critical particle numbers are given as func

S. N. Dorogovtsev, J. F. F. Mendes, Yu. G. Pogorelov

We consider the Bak--Sneppen model near zero dimension where the avalanche exponent $τ$ is close to 1 and the exponents $μ$ and $σ$ are close to 0. We demonstrate that $τ-1=μ-σ=\exp\{-μ^{-1}-γ+...\}$ in this limit, where $γ$ is the Euler&#39;s constant. The avalanche hierarchy equation is rewritten in a form that makes possible to find the relation between t

Martin C. Weisskopf, J. Jeff Hester, Allyn F. Tennant, Ronald F. Elsner

The Chandra X-ray Observatory observed the Crab Nebula and Pulsar during orbital calibration. Zeroth-order images with the High-Energy Transmission Grating (HETG) read-out by the Advanced CCD Imaging Spectrometer spectroscopy array (ACIS-S) show a striking richness of x-ray structure, at a resolution comparable to that of the best ground-based visible-light

Ch. Hoelbling, C. Rebbi, V. A. Rubakov

We present a high-statistic numerical study of the free energy of a monopole-antimonopole pair in pure SU(2) theory. We find that the monopole-antimonopole interaction potential exhibits a screened behavior, as one would expect in presence of a monopole condensate. Screening occurs both in the low-temperature, confining phase of the theory, and in the high-t

R. Jackiw, V. P. Nair

We show that the second central extension of the Galilei group in (2+1) dimensions corresponds to spin, which can be any real number.

R. P. Malik

A new local, covariant and nilpotent symmetry is shown to exist for the interacting BRST invariant U(1) gauge theory in two dimensions of space-time. Under this new symmetry, it is the gauge-fixing term that remains invariant and the corresponding transformations on the Dirac fields turn out to be the analogue of chiral transformations. The extended BRST alg

Carlo Fulvi Mari

A large network of integrate-and-fire neurons is studied analytically when the synaptic weights are independently randomly distributed according to a Gaussian distribution with arbitrary mean and variance. The relevant order parameters are identified, and it is shown that such network is statistically equivalent to an ensemble of independent integrate-and-fi

P. Zavada

The class of the free relativistic covariant equations generated by the fractional powers of the D&#39;Alambertian operator $(\square^{1/n})$ is studied. Meanwhile the equations corresponding to n=1 and 2 (Klein-Gordon and Dirac equations) are local in their nature, the multicomponent equations for arbitrary n>2 are non-local. It is shown, how the representa

C. Tejedor, L. Martin-Moreno

We present a general description of low temperature transport through a quantum dot with any number of electrons at filling factor $1<ν<2$. We provide a general description of a novel Kondo effect which is turned on by application of an appropriate magnetic field. The spin-flip scattering of carriers by the quantum dot only involves two states of the scatter

Ugo Aglietti, Giulia Ricciardi

We consider the decay of a heavy flavour into an inclusive hadronic state X of invariant mass m_X small with respect to its energy E_X, m_X << E_X. The electron spectrum and the hadronic mass distribution in semileptonic b -> u decays, or the photon spectrum in b -> s gamma decays, all require, close to their endpoints, a control over this region. This regio

Ana Achucarro, Jon Urrestilla

We analyse the stability of global O(3) monopoles in the infinite cut-off (or scalar mass) limit. We obtain the perturbation equations and prove that the spherically symmetric solution is classically stable (or neutrally stable) to axially symmetric square integrable or power-law decay perturbations. Moreover we show that, in spite of the existence of a cons

Walter Dehnen

The tree code for the approximate evaluation of gravitational forces is extended and substantially accelerated by including mutual cell-cell interactions. These are computed by a Taylor series in Cartesian coordinates and in a completely symmetric fashion, such that Newton&#39;s third law is satisfied by construction and hence momentum exactly conserved. The

P. Nason, G. Ridolfi, O. Schneider G. F. Tartarelli, P. Vikas

We review the prospects for bottom production physics at the LHC.

Holger Gies, Rashid Shaisultanov

An expression for the axial vector current in a strong, slowly varying electromagnetic field is obtained. We apply this expression to the construction of the effective action for low-energy neutrino-photon interactions.

S. Shankaranarayanan, T. Padmanabhan

We use the modified propagator for quantum field based on a ``principle of path integral duality&#34; proposed earlier in a paper by Padmanabhan to investigate several results in QED. This procedure modifies the Feynman propagator by the introduction of a fundamental length scale. We use this modified propagator for the Dirac particles to evaluate the first

A. B. Henriques, R. G. Moorhouse

We study a model for reheating that has been much investigated for parametric resonance, having a quartic interaction of the scalar inflaton with another scalar field. Attention is particularly on the quantum excitations of the inflaton field and the metric perturbation with a smooth transition from quantum to classical stochastic states, followed through fr

Takahiro Miura, Eiichi Takasugi, Masaki Yoshimura

We present neutrino mass matrices which predict the atmospheric neutrino mixing to be almost maximal, $\sin^2 2\theta_{atm}>0.999$, as well as the large solar neutrino mixing, $8/9>\sin^2 2\theta_{sol}>0.87$, and the large CP violation (the CP violation phase in the standard form is maximal $\delta=\pi/2$), based on the $Z_3$ symmetry.

Holger F. Hofmann, Toshiki Ide, Takayoshi Kobayashi, Akira Furusawa

Ideally, quantum teleportation should transfer a quantum state without distortion and without providing any information about that state. However, quantum teleportation of continuous electromagnetic field variables introduces additional noise, limiting the fidelity of the quantum state transfer. In this article, the operator describing the quantum state tran

P. Deuar, W. J. Munro

We find that very different quantum copying machines are optimal depending on the indicator used to assess their performance. Several quantum copying machine models acting on non-orthogonal input states are investigated, and assessed according to two types of criteria: Transfer of (Shannon) information encoded in the initial states to the copies, and fidelit

M. Tohyama

The strength functions of the DGDRs in 16O and 40Ca are calculated using an extended version of TDHF known as the time-dependent density-matrix theory (TDDM). The calculations are done in a self-consistent manner, in which the same Skyrme force as that used for the mean-field potential is used as the residual interaction to calculate two-body correlations. I

Hyun-Tak Kim, Kwang-Yong Kang, Bong-Jun Kim, Y. C. Kim

For a Ba_{0.63}K_{0.37}BiO_3 single crystal with T_c=31 K, H_{c1}=750 Oe at 5 K, and dimensions 3x3x1 mm^3, the temperature and field dependences of magnetic hysteresis loops have been measured within 5-25 K in magnetic fields up to 6 Tesla. The critical current density is J_c(0)=1.5 x 10^5 A/cm^2 at zero field and 1 x 10^5 A/cm^2 at 1 kOe at 5 K. J_c decrea

Xin-Nian Wang

Dynamical screening in the magnetic part of the one-gluon exchange interaction is included in the study of radiative energy loss of a fast parton propagating inside a quark-gluon plasma. As a result the final radiative energy loss is about twice as large as when only the electric part of one-gluon exchange interaction is considered. A non-perturbative magnet

Jinwu Ye

By a singular gauge transformation, the quasi-particle transport in the mixed state of high T_{c} cuprates is mapped into charge-neutral composite Dirac fermion moving in short-range correlated random scalar and long-range correlated vector potential. A fully quantum mechanical approach to longitudinal and transverse thermal conductivities is presented. The

S. Yoon, M. Rubhausen, S. L. Cooper, K. H. Kim

We report an inelastic light scattering study of the effects of charge-ordering on the spin-, charge-, and lattice-dynamics in ${\rm Bi}_{1-x}{\rm Ca}_{x}{\rm MnO}_3$ $(x>0.5)$. We find that charge-ordering results in anomalous phonon behavior, such as the appearance of `activated&#39; modes. More significantly, however, the transition to the CO phase result

Habatwa Vincent Mweene

The approach to quantum mechanics which we have used to derive the matrix treatment of spin from first principles is now employed to treat systems of compounded angular momentum. A general treatment is first given, which is then applied to the concrete cases of a spin-0 and a spin-1 system obtained by adding the spins of two spin-1/2 systems. Thus the probab

Habatwa Vincent Mweene

In a recent paper, we introduced a new way of treating systems of compounded angular momentum. We obtained the probability amplitudes for measurements on the systems and used these to derive the matrix treatment of compounded spin. However, the matrix forms are in 3- and 4- dimensional space and are therefore entirely different from the standard forms. This

Jagdish Rai, Suranjana Rai

We explore the connection between quantum entanglement and the exchange symmetry of the states of N identical particles. Each particle has n-levels. The N particles span the nN dimensional Hilbert space. We shall call the general state of the particle as a qunit. The direct product of the N qunit space is given a decomposition in terms of states with definit

R. Milot, A. P. J. Jansen

The role of vibrational excitation of a single mode in the scattering of methane is studied by wave packet simulations of oriented CH4 and CD4 molecules from a flat surface. All nine internal vibrations are included. In the translational energy range from 32 up to 128 kJ/mol we find that initial vibrational excitations enhance the transfer of translational e

S. Furihata

The light fragment production reactions for 10 MeV to 3 GeV protons incident on O-16, Al-27, Fe, Nb-93, and Ag are analyzed by a combination of an intranuclear cascade model and a generalized evaporation model which includes light nuclei up to Mg as ejectiles. It is concluded that evaporation is the dominant process by which particles lighter than or equal t

D. Drechsel, M. Vanderhaeghen, M. M. Giannini, E. Santopinto

The reaction $γ+p\toγ&#39;+p+π^0$ has been suggested as a means to deduce the $Δ^+$ magnetic moment. The cross section for this process is estimated in both the constituent quark model and an effective Lagrangian procedure. The resulting total cross section is of the order 5-10 nb, which is at the limit of present experimental capabilities.

Fernando P. Simonotti, Marcos Saraceno

We obtain a semiclassical expression for the projector onto eigenfunctions by means of the Fredholm theory. We express the projector in the coherent state basis, thus obtaining the semiclassical Husimi representation of the stadium eigenfunctions, which is written in terms of classical invariants: periodic points, their monodromy matrices and Maslov indices.

Daniel Ruberman, Saso Strle

We show that the mod 2 Seiberg-Witten invariant can be determined for a spin manifold X which has the same homology groups as the 4-torus. The value depends on the structure of the cohomology ring of X, and in particular on the 4-fold cup product on H^1(X). We also consider some examples of homology tori.

Igor Belegradek

We prove a finiteness theorem for the class of complete finite volume Riemannian manifolds with pinched negative sectional curvature, fixed fundamental group, and of dimension $>2$. One of the key ingredients is that the fundamental group of such a manifold does not admit a small nontrivial action on an $R$-tree.

Eiji Ogasa

Let S^3_i be a 3-sphere embedded in the 5-sphere S^5 (i=1,2). Let S^3_1 and S^3_2 intersect transversely. Then the intersection C of S^3_1 and S^3_2 is a disjoint collection of circles. Thus we obtain a pair of 1-links, C in S^3_i (i=1,2), and a pair of 3-knots, S^3_i in S^5 (i=1,2). Conversely let (L_1,L_2) be a pair of 1-links and (X_1,X_2) be a pair of 3-

Eiji Ogasa

Let n be any integer greater than two. We prove that there exists a projection P having the following properties. (1) P is not the projection of any unknotted knot. (2) The singular point set of P consists of double points. (3) P is the projection of an n-knot which is diffeomorphic to the standard sphere. We prove there exists an immersed n-sphere (in R^{n+

Stefan Boller

In this paper we examine an inverse problem in the modular theory of von Neumann algebras in the case of finite factors. First we give a characterization of cyclic and separating vectors for finite factors in terms of operators associated with this vector and being affiliated with the factor. Further we show how this operator generates the modular objects of

A. B. Goncharov

We define a regulator map from the weight n polylogarithmic motivic complex to the weight n Deligne complex of an algebraic variety X. The regulator map is constructed explicitly via the classical polylogarithms with some funny combinations of Bernoulli numbers as coefficients. This leads to conjectures on special values of L-functions at s=n which reduce to

András Némethi, Ágnes Szilárd

In this article we give a construction of the resolution graphs of hypersurface surface singularities (X_k,0) given by generalized Iomdin series. All these resolution graphs are coordinated by an ``universal bi-colored graph&#39;&#39; which is associated with the ICIS determining the Iomdin series. The definition of this new graph is rather involved, and in

András Némethi

The article starts with some introductory material about resolution graphs of normal surface singularities (definitions, topological/homological properties, etc). We then discuss the case when the normal surface singularity is an N-fold cyclic covering of a surface germ, branched along a curve given by the germ of an analytic function f. We present non-trivi

Glenn Barnich

In the extended antifield formalism, a quantum BRST differential for anomalous gauge theories is constructed. Local BRST cohomological classes are characterized, besides the form degree and the ghost number, by the length of their descents and of their lifts, and this both in the standard and the extended antifield formalism. It is shown that during the BRST

Cesar D. Fosco, Francisco D. Mazzitelli

We show that the Pauli-Villars regularized action for a scalar field in a gravitational background in 1+1 dimensions has, for any value of the cutoff M, a symmetry which involves non-local transformations of the regulator field plus (local) Weyl transformations of the metric tensor. These transformations, an extension to the regularized action of the usual W

M. Alves, D. Bazeia, V. B. Bezerra

This work deals with the formation of black hole in bidimensional dilaton gravity coupled to scalar matter fields. We investigate two scalar matter systems, one described by a sixth power potential and the other defined with two scalar fields containing up to the fourth power in the fields. The topological solutions that appear in these cases allow the forma

G. Bertoldi, J. M. Isidro, M. Matone, P. Pasti

We compactify M(atrix) theory on Riemann surfaces Sigma with genus g>1. Following [1], we construct a projective unitary representation of pi_1(Sigma) realized on L^2(H), with H the upper half-plane. As a first step we introduce a suitably gauged sl_2(R) algebra. Then a uniquely determined gauge connection provides the central extension which is a 2-cocycle

Adel Bilal, Chong-Sun Chu

According to the AdS/CFT correspondence, the maximally supersymmetric SU(N) Yang-Mills theory in 4 dimensions is dual to the type IIB string theory compactified on AdS_5 x S^5. Most of the tests performed so far are confined to the leading order at large N or equivalently string tree-level. To probe the correspondence beyond this leading order and obtain 1/N

M. Calixto, V. Aldaya

The possibility of non-trivial representations of the gauge group on wavefunctionals of a gauge invariant quantum field theory leads to a generation of mass for intermediate vector and tensor bosons. The mass parameters &#34;m&#34; show up as central charges in the algebra of constraints, which then become of second-class nature. The gauge group coordinates

C. Adam, B. Muratori, C. Nash

We show that a previous paper of Freund describing a solution to the Seiberg-Witten equations has a sign error rendering it a solution to a related but different set of equations. The non-$L^2$ nature of Freund&#39;s solution is discussed and clarified and we also construct a whole class of solutions to the Seiberg-Witten equations.

Jaydeep Majumder, Ashoke Sen

It has been conjectured that the vortex solution on a D-brane - anti-D-brane system represents a D-brane of two lower dimension. We establish this result by first identifying a series of marginal deformations which create the vortex - antivortex pair on the brane - antibrane system, and then showing that under this series of marginal deformations the origina

O. V. Shaynkman, M. A. Vasiliev

We formulate the equations of motion of a free scalar field in the flat and $AdS$ space of an arbitrary dimension in the form of some &#34;higher spin&#34; covariant constancy conditions. Klein-Gordon equation is interpreted as a non-trivial cohomology of a certain &#34;\sgm-complex&#34;. The action principle for a scalar field is formulated in terms of the

Mohammad R. Garousi

By explicit evaluation of certain disk S-matrix elements in the presence of background B-flux, we find coupling of two open string tachyons to gauge field, graviton, dilaton or Kalb-Ramond antisymmetric tensor on the world-volume of a single non-BPS D$p$-brane. We then propose an extension of the abelian Dirac-Born-Infeld action which naturally reproduces th