October 1998 arXiv papers — page 9

Stuart Samuel

Addressed is the question of whether a natural mechanism exists to resolve the strong CP problem. The analogous issue for the two-dimensional $CP^{N-1}$ models is analyzed using computer simulations.

R. Burkhalter

We present an overview of recent results from the CP-PACS computer on the quenched light hadron spectrum and an on-going two-flavour full QCD study. We find that our quenched hadron mass results are compatible with the mass formulae predicted by quenched chiral perturbation theory, which we adopt in our final analysis. Quenched hadron masses in the continuum

C. P. Jessop

We report the first observation of two narrow charmed strange baryons decaying to $Ξ_c^+γ$ and $Ξ_c^0γ$, respectively, using data from the CLEO II detector at CESR. We interpret the observed signals as the $Ξ_c^{+\prime}(c{su})$ and $Ξ_c^{0\prime}(c{sd})$, the symmetric partners of the well-established antisymmetric $Ξ_c^+(c[su])$ and $Ξ_c^0(c[sd])$. The mas

Pawel Nurowski, Lane Hughston, David Robinson

The geometry of P, the bundle of null directions over an Einstein space-time, is studied. The full set of invariants of the natural G-structure on P is constructed using the Cartan method of equivalence. This leads to an extension of P which is an elliptic fibration over the space-time. Examples are given which show that such an extension, although natural,

Gérard Clément

I present a new method to generate rotating solutions of the Einstein--Maxwell equations from static solutions, and briefly discuss its general properties.

Octavio Obregon, Michael P. Ryan,

Unpolarized Gowdy models are inhomogeneous cosmological models that depend on time and one spatial variable and have complicated nonlinear equations of motion. There are two topologies associated with these models, a three-torus and a one-sphere cross a two-sphere. The three-torus models have been used for numerical studies because it seems difficult to find

Robert Strom, Guruduth Banavar, Tushar Chandra, Marc Kaplan

Gryphon is a distributed computing paradigm for message brokering, which is the transferring of information in the form of streams of events from information providers to information consumers. This extended abstract outlines the major problems in message brokering and Gryphon's approach to solving them.

Haranath Ghosh

We study time reversal symmetry breaking superconductivity with $Δ_k = Δ_{x^2-y^2} (k) +e^{iθ} Δ_α$ ($α= s$ or $d_{xy}$) symmetries. It is shown that the behavior of such superconductors could be {\em qualitatively} different depending on the minor components ($α$) and its phase at lower temperatures. It is argued that such {\em qualitatively different} beha

K. Fabricius, A. Klümper, B. M. McCoy

An analytical study is presented of the crossover in the gapless attractive XXZ chain from antiferromagnetic to ferromagnetic behaviour at low to high temperature, respectively. In particular, an analytic formula for the crossover in the long distance asymptotics and explicit results for the nearest-neighbour longitudinal correlation are obtained. We also pr

H. Schomerus, C. W. J. Beenakker

We present a semiclassical theory for the excitation spectrum of a ballistic quantum dot weakly coupled to a superconductor, for the generic situation that the classical motion gives rise to a phase space containing islands of regularity in a chaotic sea. The density of low-energy excitations is determined by quantum energy scales that are related in a simpl

Andreas Jaster

We present detailed Monte Carlo results for the two-dimensional melting transition of various systems up to N=65536 hard disks. The simulations are performed in the NVT ensemble, using a new updating scheme. In the isotropic phase the bond orientational correlation length xi_6 and the susceptibility chi_6 are measured and compared with the predictions of the

W. Weller, J. Dietel, Th. Koschny, W. Apel

We consider electrons in two dimensions in a strong magnetic field at half filling of the lowest Landau level using the Chern-Simons approach. Starting from a lattice Hamiltonian for the electrons, we derive a path integral (PI) formulation for the composite fermions (CF) which respects the order of the operators. We use a time lattice with intermediate time

A. Fledderjohann, C. Gerhardt, M. Karbach, K. -H. Mütter

We study the one-dimensional spin-1/2 model with nearest and next-to-nearest-neighbor couplings exposed to a homogeneous magnetic field $h_{3}$ and a dimer field with period $q$ and strength $δ$. The latter generates a magnetization plateau at $M=(1-q/π)/2$, which evolves with strength $δ$ of the perturbation as $δ^ε$, where $ε=ε(h_{3},α)$ is related to the

J. Ambjørn, G. Koutsoumbas, G. K. Savvidy

We perform Monte Carlo simulations of a four-dimensional gauge invariant spin system which describes random surfaces with gonihedric action. We develop the analogy between the flat-crumpled phase transition of the lattice surface model and the liquid-gas phase transition of non-ideal gases, and identify the self-intersection coupling constant $k$ of the surf

Siu A. Chin, Harald A. Forbert

When a sizable, hard-sphere-like impurity is placed in a trapped Bose-Einstein condensate, it will create a hole in the condensate wave function. Since it costs more energy to drill a hole at the wave function's maximum (near the trap center) than at its minimum (near the trap edge), the impurity will be expelled from the condensate. This suggests that C

Shun-Qing Shen, Z. D. Wang

We present an exact ground state solution of a one-dimensional electronic model for transition-metal oxides in the strong coupling limit. The model contains doubly degenerated orbit for itinerant electrons and the Hund coupling between the itinerant electrons and localized spins. The ground state is proven to be a full ferromagnet for any density of electron

J. H. Han, S. -R. Eric Yang

We demonstrate that a theory of the edge of a half-filled Landau level recently proposed by Lee and Wen predicts results for the edge occupation number similar to those of a variational trial wave function proposed previously by us. We treat Lee and Wen's edge action of a half-filled Landau level within the framework of bosonization theory, and show that

M. D. Grynberg

We investigate the late coarsening stages of one dimensional adsorption processes with diffusional relaxation. The nonequilibrium domain size distribution is studied by means of the field theory associated to the stochastic evolution. An exact asymptotic solution satisfying dynamical scaling is given for cluster sizes smaller than the average domain length.

M. Franz, A. J. Millis

We consider the effect of classical phase fluctuations on the quasiparticle spectra of underdoped high-$T_c$ cuprate superconductors in the pseudogap regime above $T_c$. We show that photoemission and tunneling spectroscopy data are well accounted for by a simple model in which mean field d-wave quasiparticles are semiclasically coupled to supercurrents indu

G. Boffetta, A. Celani, R. Prandi

The stability of a sheared magnetic field is analyzed in two-dimensional magnetohydrodynamics with resistive and viscous dissipation. Using a multiple-scale analysis, it is shown that at large enough Reynolds numbers the basic state describing a motionless fluid and a layered magnetic field, becomes unstable with respect to large scale perturbations. The exa

Stanley L. Robertson

Recent work has linked the quiescent luminosities and hard/soft spectral state switches of neutron stars (NSs) to their spinning magnetic fields. It is shown here that the quiescent luminosities and spectral switches of galactic black hole candidates (BHCs) could be produced in the same way for spin rates below 100 Hz and magnetic fields above 10^10 G. It is

Stuart D. Ryder, Johan H. Knapen

We present high-resolution, near-infrared imaging of the circumnuclear region of the barred spiral galaxy M100 (=NGC 4321), accompanied by near-infrared spectroscopy. We identify a total of 43 distinct regions in the K-band image, and determine magnitudes and colours for 41 of them. By comparison with other near-infrared maps we also derive colour excesses a

Stephen E. Schneider, John G. Spitzak, Jessica L. Rosenberg

We analyze the distribution of galaxy HI masses detected in a large, deep HI survey conducted at the Arecibo observatory, and we find possible evidence of a faint-end steepening of the mass function similar to what has been found optically. This is the first HI survey with enough dynamic range to see this steepening; the results of an earlier survey are foun

Matthew Trewhella, Barry F. Madore, Leslie Kuchinski

We have developed a new model that uses a cellular approach to calculate radiative transfer of starlight through dusty media. The model is designed to be user friendly enough to be distributed as a tool for use by the general astronomical community. Its features include treatment of scattering, absorption and far infrared emission; propagating many wavelengt

G. Hasinger, R. Giacconi, J. E. Gunn, I. Lehmann

An unusual double-lobed extended X-ray source (RX J105343+5735) is detected in the ROSAT ultra-deep HRI image of the Lockman Hole. The angular size of the source is 1.7 X 0.7 arcmin^2 and its X-ray flux is 2 X 10^-14 erg cm^-2 s^-1. R-band imaging from the Keck telescope revealed a marginal excess of galaxies brighter than R=24.5, but Keck LRIS spectroscopy

R. Moderski, B. Czerny

Recently Ghosh (1998) reported a new regime of instability in Keplerian accretion disks which is caused by relativistic effects. This instability appears in the gas pressure dominated region when all relativistic corrections to the disk structure equations are taken into account. We show that he uses the stability criterion in completely wrong way leading to

George B. Field, Eric G. Blackman, Hongsong Chou

We extend the standard two-scale theory of the turbulent dynamo coefficient $α$ to include the nonlinear back reaction of the mean field $\bar B$ on the turbulence. We calculate the turbulent emf as a power series in $\bar B$, assuming that the base state of the turbulence ($\bar B=0$) is isotropic, and, for simplicity, that the magnetic diffusivity equals t

Jose A. Font, Jose M. Ibanez, Philippos Papadopoulos

In our program of studying numerically the so-called Bondi-Hoyle accretion in the fully relativistic regime, we present here first results concerning the evolution of matter accreting supersonically onto a rotating (Kerr) black hole. These computations generalize previous results where the non-rotating (Schwarzschild) case was extensively considered. We para

Michael W. Wise

We review the high resolution X-ray spectroscopy capabilities of the AXAF observatory focusing on the High Energy Transmission Grating (HETG). As part of the Guaranteed Time Observation (GTO) program, the HETG science team will observe both elliptical galaxies and clusters of galaxies. We discuss the problems associated with observing extended sources with t

Rudy Wijnands, Michiel van der Klis

We analyzed the rapid aperiodic X-ray variability of different types of X-ray binaries (black hole candidates, atoll sources, the recently discovered millisecond X-ray pulsar, and Z sources) at their lowest inferred mass accretion rates. At these accretion rates, the power spectra of all sources are dominated by a strong band-limited noise component, which f

Angel Morales

The status and prospects of the experimental efforts in the detection of Particle Dark Matter is reviewed. Emphasis is put in the direct searches for WIMPs (Weakly Interacting Massive Particles), outlining the various strategies and techniques currently followed and sumarizing the results. A briefing of the indirect methods of WIMP detection is also presente

Carsten van de Bruck, Wolfgang Priester

Evidence for a positive cosmological constant $Λ$, derived from the Ly$α$-forest in high-resolution spectra of quasars, leads to a closed, low-density, $Λ$-dominated universe. The analysis is based on the assumption of a universal shell structure expanding predominantly with the Hubble flow. Supporting evidence comes from two pairs of very wide absorption li

Tetsuya Shiromizu

The feature of the spectrum of primordial magnetic field is studied by using renormalization group analysis in magnetohydrodynamics. Taking account of the renormalized resistivity at the fixed point, we show that the scaling of the typical scale with time obeys $L(t) \sim t^{2/5}$ for random initial condition.

M. R. S. Hawkins

Numerical simulations and theoretical studies of the gravitational microlensing effect of a population of small bodies distributed along the line of sight to a compact light source such as a quasar indicate that caustic crossing effects will be present given a sufficiently large optical depth to lensing. These events will produce characteristic patterns in t

Marco Chiaberge, Annalisa Celotti, Gabriele Ghisellini

The quasi-symmetric shape of the lightcurves, as seen in the X-rays and in the optical, together with the fast variations of the flux observed, suggest that the cooling time for the highest energy electrons may be shorter than the light crossing time $R/c$. Moreover the existence of time lags between lightcurves at different frequencies can be interpreted, i

Charles H. Lineweaver

Recent cosmic microwave background measurements combined with recent supernovae limits and other observational data have ambushed Omega_lambda and Omega_m. These cosmological culprits are trapped in a small pocket of parameter space: Omega_lambda = 0.62 +/- 0.16 and Omega_m = 0.24 +/- 0.10. If this is correct then an unknown 2/3 of the Universe has been iden

Z. G. Dai, T. Lu

We here discuss a new model of $γ$-ray bursts (GRBs) based on differentially rotating strange stars. Strange stars in this model and differentially rotating neutron stars in the Kluźniak-Ruderman model can produce extremely relativistic, variable fireballs required by GRBs and then become millisecond pulsars. The effect of such pulsars on expansion of the po

Rosa M. Gonzalez Delgado, Maria Luisa Garcia-Vargas, Jeff Goldader, Claus Leitherer

We have studied the physical conditions in the central 300 pc of the proto-typical starburst galaxy NGC 7714. Our analysis is based on ultraviolet spectroscopy with the HST+GHRS and ground-based optical observations.The data are interpreted using evolutionary models optimized for young starburst regions. The massive stellar population is derived in a self-co

Douglas Scott

The Microwave Anisotropy Probe (MAP) and Planck Surveyor satellites promise to provide accurate maps of the sky at a range of frequencies and angular scales, from which it will be possible to extract estimates for cosmological parameters. But the real Universe is a nasty, messy place, full of non-linear astrophysics. It is certainly clear that MAP and Planck

E. E. Benevolenskaya

It has been argued that the solar magnetic cycle consists of two main periodic components: a low-frequency component (Hale's 22-year cycle) and a high-frequency component (quasi-biennial cycle). The existence of the double magnetic cycle on the Sun is confirmed using Stanford, Mount Wilson and Kitt Peak magnetograph data from 1976 to 1996 (solar cycles 2

R. Jimenez

In the past 40 years a considerable effort has been focused in determining the age of the Universe at zero redshift using several stellar clocks. In this review I will describe the best theoretical methods to determine the age of the oldest Galactic Globular Clusters (GC). I will also argue that a more accurate age determination may come from passively evolv

Lisa Randall, Raman Sundrum

We show that in a general hidden sector model, supersymmetry breaking necessarily generates at one-loop a scalar and gaugino mass as a consequence of the super-Weyl anomaly. We study a scenario in which this contribution dominates. We consider the Standard Model particles to be localized on a (3+1)-dimensional subspace or ``3-brane'' of a higher dime

Wei Bao, S. Raymond, S. M. Shapiro, K. Motoya

Spin excitations of single crystal Fe0.7Al0.3 were investigated over a wide range in energy and reciprocal space with inelastic neutron scattering. In the ferromagnetic phase, propagating spin wave modes become paramagnon-like diffusive modes beyond a critical wave vector q0, indicating substantial disorder in the long-range ordered state. In the spin glass

A. W. C. Lau, P. Pincus

We consider the electrostatic interaction between two rigid membranes, with different surface charge densities of opposite sign, across an aqueous solution without added salt. Exact solutions to the nonlinear Poisson-Boltzmann equation are obtained and their physical meaning discussed. We also calculate the electrostatic contribution to the free energy and d

Radek Stompor

Gravitational interaction of cosmic microwave background (CMB) photons with matter perturbations present along the line-of-sight to the surface of last scattering modifies the shape of the CMB anisotropy power spectrum. Here I focus on (linear) integrated Sachs-Wolfe and (non-linear) gravitational lensing effects and discuss the detectability of the resultin

Jaemo Park, Soo-Jong Rey

Utilizing coset superspace approach, dual actions of super D1-and D3-branes on $AdS_5 \times S^5$ are constructed by carrying out duality transformation of world-volume U(1) gauge field. Resulting world-volume actions are shown to possess expected SL(2,{\bf Z}) properties. Crucial ingredient for deriving SL(2, {\bf Z}) transformation property of the D-brane

Kristen Menou, Ann A. Esin, Ramesh Narayan, Michael R. Garcia

We consider the X-ray luminosity difference between neutron star and black hole soft X-ray transients (NS and BH SXTs) in quiescence. The current observational data suggest that BH SXTs are significantly fainter than NS SXTs. The luminosities of quiescent BH SXTs are consistent with the predictions of binary evolution models for the mass transfer rate if (1)

Raissa M. D'Souza, Norman H. Margolus

We introduce a lattice gas model of cluster growth via the diffusive aggregation of particles in a closed system obeying a local, deterministic, microscopically reversible dynamics. This model roughly corresponds to placing the irreversible Diffusion Limited Aggregation model (DLA) in contact with a heat bath. Particles release latent heat when aggregating,

A. S. Kronfeld, S. Hashimoto

The renormalization of vector and axial-vector currents for massive fermions (in the ``Fermilab formalism'') is discussed. We give results for non-degenerate masses, which are needed for semi-leptonic form factors.

Matthias R. Gaberdiel, Michael B. Green

The SL(2,Z) duality transformations of type IIB supergravity are shown to be anomalous in generic F-theory backgrounds due to the anomalous transformation of the phase of the chiral fermion determinant. The anomaly is partially cancelled provided the ten-dimensional type IIB theory lagrangian contains a term that is a ten-form made out of the composite U(1)

F. Gonzalez-Rey, B. Kulik, I. Y. Park, M. Rocek

The full low energy effective action of N=4 SYM is believed to be self-dual. Starting with the first two leading terms in a momentum expansion of this effective action, we perform a duality transformation and find the conditions for self-duality. These determine some of the higher order terms. We compare the effective action of N=4 SYM with the probe-source

Jens A. Hauch, Dominic Holland, M. P. Marder, Harry L. Swinney

We have measured the velocity of a running crack in brittle single crystal silicon as a function of energy flow to the crack tip. The experiments are designed to permit direct comparison with molecular dynamics simulations; therefore the experiments provide an indirect but sensitive test of interatomic potentials. Performing molecular dynamics simulations of

A. Rosch

The resistivity in metals near an antiferromagnetic quantum critical point (QCP) is strongly affected by small amounts of disorder. In a quasi-classical treatment, we show that an interplay of strongly anisotropic scattering due to spin fluctuations and isotropic impurity scattering leads to a large regime where the resistivity varies as T^alpha, with an ano

E. Aurell, R. Baviera, O. Hammarlid, M. Serva

We introduce and discuss a general criterion for the derivative pricing in the general situation of incomplete markets, we refer to it as the No Almost Sure Arbitrage Principle. This approach is based on the theory of optimal strategy in repeated multiplicative games originally introduced by Kelly. As particular cases we obtain the Cox-Ross-Rubinstein and Bl

E. del Barco, N. Vernier, J. M. Hernandez, J. Tejada

We report observation of coherent quantum oscilations in spin-10 Fe8 molecular clusters. The powder of magnetically oriented Fe8 crystallites was placed inside a resonator, in a dc magnetic field perpendicular to the magnetization axis. The field dependence of the ac-susceptibility was measured up to 5 T, at 680 MHz, down to 25 mK. Two peaks in the imaginary

M. A. Anisimov, E. Luijten, V. A. Agayan, J. V. Sengers

Recent numerical studies of the susceptibility of the three-dimensional Ising model with various interaction ranges have been analyzed with a crossover model based on renormalization-group matching theory. It is shown that the model yields an accurate description of the crossover function for the susceptibility.

P. Q. Hung

The old issue of why there are more than one family of quarks and leptons is reinvestigated with an eye towards the use of anomaly as a tool for constraining the number of families. It is found that, by assuming the existence of right-handed neutrinos (which would imply that neutrinos will have a mass) and a new chiral SU(2) gauge theory, strong constraints

D. Bazeia, E. Ventura

We introduce an alternate model to describe twistons in crystalline polyethylene. The model couples torsional and longitudinal degrees of freedom and appears as an extension of a model that describes only the torsional motion. We find exact solutions that describe stable topological twistons, in good agreement with the torsional and longitudinal interactions

Lev I. Deych, M. Erementchouk, V. A. Ignatchenko

The selection rules for dipole and Raman activity can be relaxed due to local distortion of a crystalline structure. In this situation a dipole-inactive mode can become simultaneously active in Raman scattering and in dipole interaction with the electromagnetic field. The later interaction results in disorder-induced polaritons, which could be observed in fi

D. V. Ramana Reddy, A. Sen, G. L. Johnston

We present a detailed study of the effect of time delay on the collective dynamics of coupled limit cycle oscillators at Hopf bifurcation. For a simple model consisting of just two oscillators with a time delayed coupling, the bifurcation diagram obtained by numerical and analytical solutions shows significant changes in the stability boundaries of the ampli

F. Cardarelli, S. Simula

We present an investigation of the Isgur-Wise form factor relevant for the semileptonic decay Lambda_b -> Λ_c + l nu_l performed within a light-front constituent quark model. Adopting different baryon wave functions it is found that the Isgur-Wise form factor depends sensitively on the baryon structure. It is shown however that the shape of the Isgur-Wise fu

Chao-Shang Huang, Tianjun Li, Wei Liao, Qi-Shu Yan

We revisit the eleven dimension Planck scale, the physical scale of the eleventh dimension, the physical scale of Calabi-Yau manifold and coupling in hidden sector in M-theory on $S^1/Z_2$. And we discuss the reasonable bound on them. Considering F-term of dilaton and moduli SUSY breaking and choosing two repersentative points which correspond to scalar quas

J. Hisano, Kiichi Kurosawa, Yasunori Nomura

Considering that the soft SUSY breaking scalar masses come from a vacuum expectation value of the D-term for an external gauge multiplet, the renormalization of the scalar masses is related to the gauge anomaly. Then, if the external gauge symmetry is anomaly-free and has no kinetic mixing with the other U(1) gauge symmetries, the scalar masses are non-renor

Cheongho Han, Tu-Whan Kim

Despite the detection of a large number of gravitational microlensing events, the nature of Galactic dark matter remains very uncertain. This uncertainty is due to two major reasons: the lens parameter degeneracy in the measured Einstein timescale and the blending problem in dense field photometry. Recently, consideration has been given to routine astrometri

K. G. Petrosyan, L. You

We show that the quantum topological effect predicted by Aharonov and Casher (AC effect) [Phys. Rev. Lett. 53, 319 (1984)] may be used to create circulating states of magnetically trapped atomic Bose-Einstein condensates (BEC). A simple experimental setup is suggested based on a multiply connected geometry such as a toroidal trap or a magnetic trap pinched b

Jacob Neufeld

There are reasons to believe that implications of a certain paradox introduced by Ginzburg and related problems have not been fully recognized. Pertinent issues remain open and unresolved. There are instances when the current widely used theory yields results having no physical meaning. As a result, the current widely used theory is not equipped to cope with

Yuji Igarashi, Katsumi Itoh, Ken Nakanishi

In a certain class of differential-difference equations for dissipative systems, we show that hyperbolic tangent model is the only the nonlinear system of equations which can admit some particular solutions of the Toda lattice. We give one parameter family of exact solutions, which include as special cases the Toda lattice solutions as well as the Whitham&#3

A. D. Lahiff, I. R. Afnan

A covariant model of elastic pion-nucleon scattering based on the Bethe-Salpeter equation is presented. The kernel consists of s- and u-channel nucleon and delta poles, along with rho and sigma exchange in the t-channel. A good fit is obtained to the s- and p-wave phase shifts up to the two-pion production threshold.

Henry C. King

This paper characterizes which subsets of C^n can be the set of positions of n points on a linkage in the complex plane C. For example, assuming compactness they are just compact semialgebraic sets. Noncompact configuration spaces are semialgebraics sets invariant under the Euclidean group, with compact quotient.

Jo Heath

Many mathematicians encounter k-to-1 maps only in the study of covering maps. But, of course, k-to-1 maps do not have to be open. This paper touches on covering maps, and simple maps, but concentrates on ordinary k-to-1 functions (both continuous and finitely discontinuous) from one metric continuum to another. New results, old results and ideas for further

Jo Heath, Van C. Nall

This paper considers the question of which continua are 2-to-1 retracts of continua.

Cameron McA. Gordon, Ying-Qing Wu

A manifold M is simple if it contains no essential disk, sphere, annulus or torus. If M is simple and two Dehn fillings M(r_1), M(r_2) are nonsimple, then there is an upper bound on Δ(r_1,r_2), the geometric intersection number between r_1 and r_2. There are 10 possibilities, depending on the types of M(r_i). In this paper it will be shown that if M(r_1) con

Xiaobo Liu, Gang Tian

Eguchi-Hori-Xiong and S. Katz proposed a conjecture that the partition function of topological sigma model coupled to gravity is annihilated by infinitely many differential operators which form half branch of the Virasoro algebra. In this paper, we give a proof to this conjecture for the genus 0 part.

W. Mück, K. S. Viswanathan

Using the AdS-CFT correspondence we calculate the two point function of CFT energy momentum tensors. The AdS gravitons are considered by explicitly solving the Dirichlet boundary value problem for $x_0=ε$. We consider this treatment as complementary to existing work, with which we make contact.

M. Bertolini, P. Fre`, R. Iengo, C. A. Scrucca

Using the D3-brane as the fundamental tool, we adress two aspects of D-branes physics. The first regards the interaction between two electromagnetic dual D-branes in 10 dimensions. In particular, we give a meaning to {\it both} even and odd spin structure contributions, the latter being non vanishing for non zero relative velocity $v$ (and encoding the Loren

Cumrun Vafa

Talk given at ICM '98, Berlin, reviewing some of the recent developments in understanding of string theory for a mathematical audience (to appear in Documenta Mathematica).

M. Nishimura, Y. Tanii

We study how local symmetry transformations of (p, q) anti de Sitter supergravities in three dimensions act on fields on the two-dimensional boundary. The boundary transformation laws are shown to be the same as those of two-dimensional (p, q) conformal supergravities for p, q \leq 2. Weyl and super Weyl transformations are generated from three-dimensional g

A. Astashkevich, N. Nekrasov, A. Schwarz

Motivated by the recently observed relation between the physics of $D$-branes in the background of $B$-field and the noncommutative geometry we study the analogue of Nahm transform for the instantons on the noncommutative torus.

Antal Jevicki, Yoichi Kazama, Tamiaki Yoneya

We study in detail the extension of the generalized conformal symmetry proposed previously for D-particles to the case of supersymmetric Yang-Mills matrix models of Dp-branes for arbitrary p. It is demonstrated that such a symmetry indeed exists both in the Yang-Mills theory and in the corresponding supergravity backgrounds produced by Dp-branes. On the Yang

S. J. Brodsky, J. R. Pelaez, N. Toumbas

We construct new tests of perturbative QCD by considering a hypothetical tau lepton of arbitrary mass, which decays hadronically through the electromagnetic current. We can explicitly compute its hadronic width ratio directly as an integral over the e^+ e^- annihilation cross section ratio, R_{e^+e^-}. Furthermore, we can design a set of commensurate scale r

H. B. O'Connell, A. G. Williams

We study the generation of vector meson masses in the Hidden Local Symmetry (HLS) model of low energy QCD. After demoting the HLS to a hidden global symmetry (HGS), the rho is explicitly shown to be massless for any value of the HS parameter "a" and the chiral partner of the pion appears as the Goldstone boson associated with the spontaneous breaking

Joao M. Soares

In the case of heavy-to-light weak meson transitions, a Quark Model derivation leads to very general relations between the form factors that parametrize the hadronic matrix elements. We investigate to what extent these form factor relations remain a good approximation, beyond the Quark Model. In heavy-to-light pseudoscalar-to-vector meson transitions, a simp

J. R. Morris

A type of scenario is considered where electrically charged vacuum bubbles, formed from degenerate or nearly degenerate vacuua separated by a thin domain wall, are cosmologically produced due to the breaking of a discrete symmetry, with the bubble charge arising from fermions residing within the domain wall. Stability issues associated with wall tension, fer

Gerhard Baur, Kai Hencken, Dirk Trautmann

In central collisions at relativistic heavy ion colliders like the Relativistic Heavy Ion Collider RHIC/Brookhaven and the Large Hadron Collider LHC (in its heavy ion mode) at CERN/Geneva, one aims at detecting a new form of hadronic matter - the Quark Gluon Plasma. We discuss here a complementary aspect of these collisions, the very peripheral ones. Due to

Bodo Lampe

Geometrical pictures for the family structure of fundamental particles are developed. They indicate that there might be a relation between the family repetition structure and the number of space dimensions.

Giampiero Passarino

The so-called CC20 processes have been extensively analyzed in the literature. They are a sensitive probe of anomalous electromagnetic couplings of the W boson and represent a background to searches for new physics beyond the standard model. Moreover, they represent a contribution to the WW total cross section, used to derive a value for the W boson mass. Th

Chris Michael

Lattice QCD determinations appropriate to hadron spectroscopy are reviewed with emphasis on the glueball and hybrid meson states in the quenched approximation. Hybrids are discussed for heavy and for light quarks. The effects of sea quarks (unquenching) are explored.

Sergio Caracciolo, Gianni De Franceschi, Fabrizio Palumbo

We present a perturbative approach to QCD based on quark composites, that is barions and mesons, as fundamental variables.

S. M. Ryan, A. X. El-Khadra, S. Hashimoto, A. S. Kronfeld

The increasing accuracy of experimental results for the exclusive, semileptonic decay B -> pi l nu requires a similarly accurate calculation of the hadronic matrix elements, to determine |Vub|. We present preliminary results for the form factors of the B to light meson decay mode. Using results from three lattices in the range 5.7 <= beta <= 6.1 we study the

J. N. Simone, A. X. El-Khadra, S. Hashimoto, A. S. Kronfeld

We estimate statistical and systematic errors in the extraction of the CKM ratio |Vcd|/|Vcs| from exclusive D-meson semileptonic decays using lattice QCD and anticipated new experimental results.

Shoichi Sasaki, Osamu Miyamura

We investigate the role of QCD-monopoles for the $U_{A}(1)$ anomaly in the maximally abelian gauge within the SU(2) lattice gauge theory. The existence of the strong correlation between instantons and QCD-monopoles in the abelian gauge was already shown by both analytic and numerical works including the Monte Carlo simulation. Their interrelation brings us a

Simonetta Frittelli, Ezra T. Newman

Normally the issue or question of the time of arrival of light rays at an observer coming from a given source is associated with Fermat&#39;s Principle of Least Time which yields paths of extremal time. We here investigate a related but different problem. We consider an observer receiving light from an extended source that has propagated in an arbitrary grav

N. R. Khusnutdinov, M. Bordag

We calculate the ground state energy of a massive scalar field in the background of a cosmic string of finite thickness (Gott-Hiscock metric). Using zeta functional regularization we discuss the renormalization and the relevant heat kernel coefficients in detail. The finite (non local) part of the ground state energy is calculated in 2+1 dimensions in the ap

Thomas W. Baumgarte, Stuart L. Shapiro

Many numerical codes now under development to solve Einstein&#39;s equations of general relativity in 3+1 dimensional spacetimes employ the standard ADM form of the field equations. This form involves evolution equations for the raw spatial metric and extrinsic curvature tensors. Following Shibata and Nakamura, we modify these equations by factoring out the

J. L. Cervantes-Cota, P. Ag. Chauvet

We analyze if Bianchi I, V, and IX models in the Induced Gravity (IG) theory can evolve to a Friedmann--Roberson--Walker (FRW) expansion due to the non--minimal coupling of gravity and the scalar field. The analytical results that we found for the Brans-Dicke (BD) theory are now applied to the IG theory which has $ω\ll 1$ ($ω$ being the square ratio of the H

Ram Brustein

String cosmology models predict a cosmic background of gravitational waves produced during a period of dilaton-driven inflation. I describe the background, present astrophysical and cosmological bounds on it, and discuss in some detail how it may be possible to detect it with large operating and planned gravitational wave detectors. The possible use of small

Krzysztof R. Apt

We provide here a proof theoretic account of constraint programming that attempts to capture the essential ingredients of this programming style. We exemplify it by presenting proof rules for linear constraints over interval domains, and illustrate their use by analyzing the constraint propagation process for the {\tt SEND + MORE = MONEY} puzzle. We also sho

Gabor Fath, Peter B. Littlewood

The behavior of Haldane-gap antiferromagnets in strong magnetic field is not universal. While the low-energy physics of the conventional 1D spin-1 Heisenberg model in its magnetized regime is described by one incommensurate soft mode, other systems with somewhat perturbed coupling constants can possess two characteristic soft modes in a certain range of the

M. Böhm, U. Krey

By ab initio LMTO calculations in atomic-sphere approximation we have studied the interlayer exchange coupling between Fe films separated by Au spacers in infinite Fe/Au multilayers with (001) interface orientation. We also performed detailed calculations of the magnetization and charge profiles across the system. We find an enhancement of the Fe moments at

Laurent Laloux, Pierre Cizeau, Jean-Philippe Bouchaud, Marc Potters

We show that results from the theory of random matrices are potentially of great interest to understand the statistical structure of the empirical correlation matrices appearing in the study of price fluctuations. The central result of the present study is the remarkable agreement between the theoretical prediction (based on the assumption that the correlati