April 1997 arXiv papers — page 6

Joseph J. Mohr, Gary Wegner

We use fundamental plane (FP) distance estimates to the components of the double cluster A2626 (cz~17,500 km/s) to constrain cluster kinematics and estimate total binding mass. The FP coefficients for a sample of 24 early type and S0 cluster members (alpha=1.30+/-0.36 and beta=0.31+/-0.06) are consistent with others reported in the literature. We examine the

Jacco Th. van Loon, Albert A. Zijlstra, Patricia A. Whitelock, L. B. F. M. Waters

We have searched for near-infrared stellar counterparts of IRAS point sources in the Large Magellanic Cloud (LMC), in J and K-bands. This resulted in the detection of 21 counterparts, of which 19 are new discoveries. Using colour-magnitude and colour-colour diagrams, we identify 13 Asymptotic Giant Branch (AGB) stars with thick circumstellar dust envelopes,

Rudy A. D. Wijnands, Michiel van der Klis

We have discovered two simultaneous quasi-periodic oscillations (QPOs) at 898.3+/-3.3 Hz and 1158.6+/-9.0 Hz in the 1996 August 1 observation of the low-mass X-ray binary KS 1731-260 with the Rossi X-ray Timing Explorer. The rms amplitude and FWHM of the lower frequency QPO were 5.3+/-0.7 % and 22+/-8 Hz, whereas those of the higher frequency QPO were 5.2+/-

Daniel E. Reichart

GRB 970228 is the first gamma ray burst for which prolonged post-burst transient x-ray, optical, and infrared emission has been detected. Recent Hubble Space Telescope observations show that the transient consists of two components: a point source, which is known to be fading, and an extended source, which is possibly fading. I fit standard fireball remnant

K. R. Priolkar, Mala N. Rao, R. B. Prabhu, P. R. Sarode

Inelastic neutron scattering investigation on ferromagnetic Kondo lattice compounds belonging to CeSi_{2-x}Ga_{x}, x = 0.7, 1.0 and 1.3, system is reported. The thermal evolution of the quasielastic response shows that the Kondo interactions dominate over the RKKY interactions with increase in Ga concentration from 0.7 to 1.3. This is related to the increase

Hideo Hasegawa

A systematic study has been made on the metal-insulator (MI) transition of the doubly degenerate Hubbard model (DHM) in the paramagnetic ground state, by using the slave-boson mean-field theory which is equivalent to the Gutzwiller approximation (GA). For the case of infinite electron-electron interactions, we obtain the analytic solution, which becomes exac

V. Balasubramanian, F. Larsen, R. G. Leigh

We construct the most general supersymmetric configuration of D2-branes and D6-branes on a 6-torus. It contains arbitrary numbers of branes at relative U(3) angles. The corresponding supergravity solutions are constructed and expressed in a remarkably simple form, using the complex geometry of the compact space. The spacetime supersymmetry of the configurati

Mahendra K. Verma

This paper is withdrawn. The revised paper appears in chao-dyn/9904020

J. Edsjo, P. Gondolo

We evaluate the relic density of the lightest neutralino, the lightest supersymmetric particle, in the Minimal Supersymmetric extension of the Standard Model (MSSM). For the first time, we include all coannihilation processes between neutralinos and charginos for any neutralino mass and composition. We use the most sophisticated routines for integrating the

A. Chou, R. Kallosh, J. Rahmfeld, S. -J. Rey

We study critical points of the BPS mass $Z$, the BPS string tension $Z_m$, the black hole potential $V$ and the gauged central charge potential $P$ for M-theory compactified on Calabi-Yau three-folds. We first show that the stabilization equations for $Z$ (determining the black hole entropy) take an extremely simple form in five dimensions as opposed to fou

Borge Nodland

We apply expansion methods to obtain an approximate expression in terms of elementary functions for the space and time dependence of wave packets in a dispersive medium. The specific application to pulses in a cold plasma is considered in detail, and the explicit analytic formula that results is provided. When certain general initial conditions are satisfied

B. Kónya, G. Lévai, Z. Papp

We propose two ways for determining the Green's matrix for problems admitting Hamiltonians that have infinite symmetric tridiagonal (i.e. Jacobi) matrix form on some basis representation. In addition to the recurrence relation comming from the Jacobi-matrix, the first approach also requires the matrix elements of the Green's operator between the firs

M. Lindner

The lack of deviations from the Standard Model at the current level of experimental precision can be explained systematically in suitable models of dynamical electro-weak symmetry breaking. The key ingredient is dynamics which produces a scalar unitarity partner for the Goldstone-Bosons and which leads to a decoupling of effects beyond the Standard Model. A

Peter Levai, Ramona Vogt

We investigate charm production in an equilibrated quark-gluon plasma produced in heavy-ion collisions at RHIC and LHC. Effective quark and gluon masses are introduced from thermal QCD calculations. Assuming a Bjorken-type longitudinal expansion and including the influence of temperature dependent masses on the expansion, we determine the total number of c\b

Michele Vendruscolo, Amos Maritan, Jayanth R. Banavar

The sensitivity of the native states of protein-like heteropolymers to mutations modelled as perturbations in the interaction potential between amino acids is studied. The stability threshold against mutations is shown to be zero for random heteropolymers on a lattice in two dimensions, whereas a design procedure modelling evolution produces a non-zero thres

Borge Nodland, John P. Ralston

We present evidence for a new phenomenon in the propagation of electromagnetic radiation across the Universe, a corkscrew rotation of the plane of polarization not accounted for by conventional physics.

Borge Nodland, John P. Ralston

We report a systematic rotation of the plane of polarization of electromagnetic radiation propagating over cosmological distances. The effect is extracted independently from Faraday rotation, and found to be correlated with the angular positions and distances to the sources. Monte Carlo analysis yields probabilistic P-values of order 10^(-3) for this to occu

Arnon Dar

Models where relativistic jets from merger or accretion induced collapse in compact binary systems produce cosmological gamma ray bursts (GRBs) also predict that GRBs are accompanied by delayed emission of high energy photons, TeV neutrinos, X-rays, optical photons and radio waves. Their emission mechanisms are similar to those responsible for their emission

Victor Ginzburg, Vadim Schechtman

Feigin and Fuchs have given a well-known construction of intertwining operators between "Fock-type" modules over the Virasoro algebra. The intertwiners are obtained via contour integration of certain "screening operators" over top homology classes of a configuration space. The main observation of the present paper is that the screening operat

I. G. Korepanov

This paper continues the series begun with works solv-int/9701016, solv-int/9702004 and solv-int/9703010. Here we construct more sophisticated strings, combining ideas from those papers and some considerations involving solutions of tetrahedron equation due to Sergeev, Mangazeev and Stroganov.

Antoine Suarez, Valerio Scarani

A new nonlocality experiment with moving beam-splitters is proposed. The experiment is analysed according to conventional quantum mechanics, and to an alternative nonlocal description in which superposition depends not only on indistinguishability but also on the timing of the impacts at the beam-splitters.

Tomasz Brzezinski

It is shown that quantum homogeneous spaces of a quantum group H can be viewed as fibres of quantum fibrations with the total space H that are dual to coalgebra bundles. As concrete examples of such structures the fibrations with the quantum 2-sphere and the quantum hyperboloid fibres are considered.

Sergiu I. Vacaru

We generalize the geometry of Santilli's locally anisotropic and inhomogeneous isospaces to the geometry of vector isobundles provided with nonlinear and distinguished isoconnections and isometric structures. We present, apparently for the first time, the isotopies of Lagrange, Finsler and Kaluza--Klein spaces. We also continue the study of the interior,

Sabbir Rahman

We analyse higher order background independence conditions arising from multiple commutators of background deformations in quantum closed string field theory. The conditions are shown to amount to a vanishing theorem for $Δ_S$ cohomology classes. This holds by virtue of the existence of moduli spaces of higher genus surfaces with two kinds of punctures. Our

K. Funakubo, A. Kakuto, S. Otsuki, F. Toyoda

The electroweak baryogenesis depends on the profile of the CP-violating bubble wall created at the first order phase transition. We attempt to determine it by solving the coupled equations of motion for the moduli and phases of the two Higgs doublets at the transition temperature. A variety of CP-violating bubble walls are classified by boundary conditions.

Peter Leifer

A new type of a nonlinear gauge quantum theory (superrelativity) has been proposed. Such theory demands a radical reconstruction of both the quantum field conception and spacetime structure, and this paves presumably way to the comprehension of the quantum nature of inertia.

Leonid Friedlander, Albert Schwarz

The conjecture about relation between infinite-dimensional Grassmannian and string theory is based on the fact that moduli spaces of algebraic curves are embedded into Grassmannian via Krichever construction. We describe a multidimensional analog of Krichever construction, that can be used in the attempt to relate Grassmannian to membranes.

M. Kontsevich

We show that recently constructed invariants of 3-dimensional manifolds and of hyperkaehler manifolds (L.Rozansky and E.Witten, hep-th/9612216) come from characteristic classes of foliations and from Gelfand-Fuks cohomology. In particular, any symplectic foliation gives invariants of 3-manifolds. Our preprint has many intersections with the preprint alg-geom

Stefan Kammerer, Walter Kob, Rolf Schilling

Using molecular dynamics computer simulations, we investigate the dynamics of the rotational degrees of freedom in a supercooled system composed of rigid, diatomic molecules. The interaction between the molecules is given by the sum of interaction-site potentials of the Lennard-Jones type. In agreement with mode-coupling theory (MCT), we find that the relaxa

J. E. Pesce, C. M. Urry, L. Maraschi, A. Treves

Optical, near-infrared, and radio observations of the BL Lac object PKS2155-304 were obtained simultaneously with a continuous UV/EUV/X-ray monitoring campaign in 1994 May. Further optical observations were gathered throughout most of 1994. The radio, millimeter, and near-infrared data show no strong correlations with the higher energies. The optical light c

C. Megan Urry, A. Treves, L. Maraschi, H. Marshall

In May 1994 the BL Lac object PKS 2155-304 was observed continuously for ~10 d with IUE and EUVE and for 2 d with ASCA, as well as with ROSAT and with ground- based radio, IR, and optical telescopes. The light curves show a well-defined X-ray flare (x2 increase in 1/2 d, with similar decay) followed by a broader, lower amplitude EUV flare ~1 day later, and a

Luca Chiantini, Ciro Ciliberto

A linear series on a curve C in $P^3$ is "primary" when it does not contain the series cut by planes. We provide a lower bound for the degree of these series, in terms of deg(C), g(C) and of the number $s = min{i: h^0(I_C(i))\neq 0}$; as a corollary, we obtain bounds for the gonality of C. Examples show that our bound is sharp. Extensions to the case

Tae-Sun Kim, Esther M. Hu, Lennox L. Cowie, Antoinette Songaila

We have analyzed the properties of low column density Lyman alpha forest clouds (12.8 < log N_HI < 16.0) toward 5 QSOs at different redshifts, using high signal-to-noise data from the HIRES spectrograph on the Keck I 10-m telescope. The results are used to study the evolution of these clouds in the interval 2.1 < z < 3.5. We find: 1) The differential density

George F. Smoot

This paper discusses a couple of approaches to removing instrument gain and baseline variation from observations of the CMB anisotropy. These techniques were tested on the COBE DMR data, a balloon experiment, and by monte carlo simulations. This work, though considered technical, is made available because CMB anisotropy mapping data processing is currently v

U. Leinberger, E. Berdermann, F. Heine, S. Heinz

We present the first energy and angle resolved measurements of e+e- pairs emitted from heavy nuclei (Z>=40) at rest by internal pair conversion (IPC) of transitions with energies of less than 2MeV as well as recent theoretical results using the DWBA method, which takes full account of relativistic effects, magnetic substates and finite size of the nucleus. T

M. Franz, Ian Affleck, M. H. S. Amin

We investigate equilibrium flux lattice structures in superconductors with unconventional order parameters, such as high-$T_c$ cuprates, using a generalized London model with non-local electrodynamics derived from a simple microscopic model. We find a rich phase diagram containing triangular, centered rectangular and square lattices with various orientations

Noureddine Chair

The potential that generates the cohomology ring of the Grassmannian is given in terms of the elementary symmetric functions using the Waring formula that computes the power sum of roots of an algebraic equation in terms of its coefficients. As a consequence, the fusion potential for $su(N)_K$ is obtained. This potential is the explicit Chebyshev polynomial

A. S. Alexandrov, R. T. Giles

Coulomb repulsion is taken into account to derive the thermodynamics of charged bosons in a random external potential. A simple analytical form of the partition function is proposed for the case of non-overlapping localised states (i.e. a small amount of disorder). The density of localised bosons and the specific heat show a peculiar non-uniform temperature

J. Fleischer, V. A. Smirnov, A. Frink, J. KÖrner

Two-loop vertex Feynman diagrams with infrared and collinear divergences are investigated by two independent methods. On the one hand, a method of calculating Feynman diagrams from their small momentum expansion extended to diagrams with zero mass thresholds is applied. On the other hand, a numerical method based on a two-fold integral representation is used

G. Murante, A. Provenzale, E. A. Spiegel, R. Thieberger

We show that an array of singular density concentrations accounts for the scaling exponents observed in the luminous matter distribution in the Universe for scales below 10Mpc. This model provides a good description of the matter distribution on those smaller scales.

A. A. Bel&#39;kov, G. Bohm, A. V. Lanyov, A. A. Moshkin

We have combined a new systematic calculation of mesonic matrix elements at O(p^6) from an effective chiral lagrangian approach using Wilson coefficients taken from [G.Buchalla, A.J.Buras, M.E.Lautenbacher, Rev.Mod.Phys. 68 (1996) 1125], derived in the framework of perturbative QCD, and restricted partly by experimental data. We derive complete expressions f

D. Miskowiec, S. Voloshin

We discuss the question of the normalization of the correlation function and its consistency with the often used form C(p1,p2) = 1+|f(p1,p2)|^2. We suggest an event mixing method which allows one to obtain absolutely normalized correlation functions from experimental data.

John L. Cardy, Uwe C. Täuber

We develop a systematic analytic approach to the problem of branching and annihilating random walks, equivalent to the diffusion-limited reaction processes 2A->0 and A->(m+1)A, where m>=1. Starting from the master equation, a field-theoretic representation of the problem is derived, and fluctuation effects are taken into account via diagrammatic and renormal

Kwan-tai Leung, Joergen Vitting Andersen, Didier Sornette

A spring-block model governed by threshold dynamics and driven by temporally increasing spring constants is investigated. Due to its novel multiplicative driving, criticality occurs even with periodic boundary conditions via a mechanism distinct from that of previous models. This mechanism is dictated by a coarsening process. The results show a high degree o

Y. Berest, I. Loutsenko

A new class of linear second order hyperbolic partial differential operators satisfying Huygens&#39; principle in Minkowski spaces is presented. The construction reveals a direct connection between Huygens&#39; principle and the theory of solitary wave solutions of the Korteweg-de Vries equation.

T. Opatrny, M. Dakna, D. -G. Welsch

It is shown that fundamental uncertainty relations between photon number and canonical phase of a single-mode optical field can be verified by means of balanced homodyne measurement. All the relevant quantities can be sampled directly from the measured phase-dependent quadrature distribution.

R. Graham, T. Wong, M. J. Collett, S. M. Tan

We study the build up of quantum coherence between two Bose-Einstein condensates which are initially in mixed states. We consider in detail the two cases where each condensate is initially in a thermal or a Poisson distribution of atom number. Although initially there is no relative phase between the condensates, a sequence of spatial atom detections produce

J. R. Mureika

Using the model framework for curve running as described in physics/9704022, the possible outcome of the 150m &#34;One to One&#34; showdown between sprinters Donovan Bailey and Michael Johnson are discussed (to be run 01 Jun 1997 at Skydome in Toronto, Ontario, Canada).

J. R. Mureika

The mathematical model of J. Keller for predicting World Record race times, based on a simple differential equation of motion, predicted quite well the records of the day. One of its shortcoming is that it neglects to account for a sprinter&#39;s energy loss around a curve, a most important consideration particularly in the 200m--400m. An extension to Keller

Th. Rubehn, K. X. Jing, L. G. Moretto, L. Phair

Fission in 3He and 4He induced reactions at excitation energies between the fission barrier and 140 MeV has been investigated. Twentythree fission excitation functions of various compound nuclei in different mass regions are shown to scale exactly according to the transition state prediction once the shell effects are accounted for. New precise measurements

Ying-Qing Wu

We use sutured manifold theory, essential laminations and essential branched surfaces to establish the upper bounds of distances between certain types of nonsimple Dehn surgery slopes. This is the revised version of an earlier preprint {\it Dehn surgery and simple manifolds.}

N. P. Chitaia, S. A. Gogilidze, Yu. S. Surovtsev

In the framework of the generalized Hamiltonian formalism by Dirac, the local symmetries of dynamical systems with first- and second-class constraints are investigated in the general case without restrictions on the algebra of constraints. The method of constructing the generator of local-symmetry transformations is obtained from the requirement for them to

David Gross

Talk presented at the conference ``Historical and Philosophical Reflections on the Foundations of Quantum Field Theory,&#39;&#39; at Boston University, March 1996. It will be published in the proceedings of this conference.

Alberto Accardi, Andrea Belli

We study the most general renormalization transformations for the first-order formulation of the Yang-Mills theory. We analyze, in particular, the trivial sector of the BRST cohomology of two possible formulations of the model: the standard one and the extended one. The latter is a promising starting point for the interpretation of the Yang-Mills theory as a

Masayasu Harada, Francesco Sannino, Joseph Schechter, Herbert Weigel

In the bound state approach the heavy baryons are constructed by binding, with any orbital angular momentum, the heavy meson multiplet to the nucleon considered as a soliton in an effective meson theory. We point out that this picture misses an entire family of states, labeled by a different angular momentum quantum number, which are expected to exist accord

David Atwood, Amarjit Soni

Mechanisms for the observed large $Br(B \to η&#39; +X_s)$ are examined. We propose that the dominant fraction of the $B \to η&#39; +X_s$ rate is due mainly to $b \to s g^*$, where $g^*$ is an off-shell gluon, followed by $g^* \to gη&#39;$ via the anomalous coupling of the $η&#39;$ to two gluons. The calculated rate for $B \to η&#39;+X_s$ is in rough accord w

Tran N. Truong

The problem of $γπ\to ππ$ is studied using the axial anomaly, elastic unitarity, analyticity and crossing symmetry. The solution of the integral equation for this amplitude is given by an iteration procedure.The final solution disagrees with vector meson dominance models.

Andrzej Czarnecki, Bernd Krause

We present a complete three-loop calculation of the electric dipole moment of the $u$ and $d$ quarks in the Standard Model. For the $d$ quark, more relevant for the experimentally important neutron electric dipole moment, we find cancellations which lead to an order of magnitude suppression compared with previous estimates.

Georg G. Raffelt

Mohanty and Samal have shown that the magnetic-moment interaction with nucleons contributes significantly to the photon dispersion relation in a supernova core, and with an opposite sign relative to the usual plasma effect. Because of a numerical error they overestimated the magnetic-moment term by two orders of magnitude, but it is still of the same order a

Jan Fischer

Methods of summation of power series relevant to applications in quantum theory are reviewed, with particular attention to expansions in powers of the coupling constant and in inverse powers of an energy variable. Alternatives to the Borel summation method are considered and their relevance to different physical situations is discussed. Emphasis is placed on

Christoph Greub, Tobias Hurth

We give a brief review of the next-to-leading logarithmic results in $B \to X_s γ$. Combining the results of different groups, a practically complete next-to-leading-logarithmic prediction of the inclusive decay rate was recently presented. The theoretical uncertainty in the decay rate in now less than half of the error in the previously leading-logarithmic

J. F. Gunion

I give an overview of the motivations for and theory/phenomenology of supersymmetry.

CLEO Collaboration, G. Bonvicini et al

We have searched for lepton family number violating decays of the $τ$ lepton using final states with an electron or a muon and one or more $π^0$ or $η$ mesons but no neutrinos. The data used in the search were collected with the CLEO II detector at the Cornell Electron Storage Ring (CESR) and correspond to an integrated luminosity of 4.68 $fb^{-1}$. No evide

J. Bicak, K. Kuchar

We present the Lagrangian and Hamiltonian framework which incorporates null dust as a source into canonical gravity. Null dust is a generalized Lagrangian system which is described by six Clebsch potentials of its four-velocity Pfaff form. The Dirac--ADM decomposition splits these into three canonical coordinates (the comoving coordinates of the dust) and th

C. Wetterich

A nonlocal form of the effective gravitational action could cure the unboundedness of euclidean gravity with Einstein action. On sub-horizon length scales the modified gravitational field equations seem compatible with all present tests of general relativity and post-Newtonian gravity. They induce a difference in the effective Newton&#39;s constant between r

E. W. Mielke, D. Kreimer

The Dirac equation in Riemann-Cartan spacetimes with torsion is reconsidered. As is well-known, only the axial covector torsion $A$, a one-form, couples to massive Dirac fields. Using diagrammatic techniques, we show that besides the familiar Riemannian term only the Pontrjagin type four-form $dA\wedge dA$ does arise additionally in the chiral anomaly, but n

Gregory Johnson, Harvey Gould, J. Machta, L. K. Chayes

The Widom-Rowlinson model of a fluid mixture is studied using a new cluster algorithm that is a generalization of the invaded cluster algorithm previously applied to Potts models. Our estimate of the critical exponents for the two-component fluid are consistent with the Ising universality class in two and three dimensions. We also present results for the thr

Reimer Kuehn, Uta Horstmann

A random matrix approach to glassy physics is introduced. It leads to a class of models which exhibit both, glassy low-temperature phases, and double-- and single-well configurations in their potential energy. The distribution of parameters characterizing the local potential energy configurations can be computed, and differ from those assumed in the standard

Alan T. Dorsey, Raymond E. Goldstein

In the intermediate state of a thin type-I superconductor magnetic flux penetrates in a disordered set of highly branched and fingered macroscopic domains. To understand these shapes, we study in detail a recently proposed &#34;current-loop&#34; (CL) model that models the intermediate state as a collection of tense current ribbons flowing along the supercond

A. Yaouanc, P. Dalmas de Reotier, E. H. Brandt

Using approximate analytical and new numerical solutions of the conventional Ginzburg-Landau equations we calculate the small angle neutron scattering cross-section and the variance of the field distribution as measured by muon-spin rotation for superconductors with large Ginzburg-Landau parameter $κ$. Our results prove that a proper account of the finite si

D. R. C. Dominguez, D. Bollé

The categorization properties of an attractor network of three-state neurons which infers three-state concepts from examples are studied. The evolution equations governing the parallel dynamics at zero temperature for the overlap between the state of the network and the examples, the state of the network and the concepts as well as the neuron activity are di

Alice Ruini, Raffaele Resta, Stefano Baroni

The problem of Fermi-level pinning at semiconductor-metal contacts is readdressed starting from first-principles calculations for Al/GaAs. We give quantitative evidence that the Schottky barrier height is very little affected by any structural distortions on the metal side---including elongations of the metal-semiconductor bond (i.e. interface strain)---wher

Armin Schmiegel, Bruno Eckhardt

We study the dynamics of localised perturbations in plane Couette flow with periodic lateral boundary conditions. For small Reynolds number and small amplitude of the initial state the perturbation decays on a viscous time scale $t \propto Re$. For Reynolds number larger than about 200, chaotic transients appear with life times longer than the viscous one. D

Anthony H. Gonzalez, S. M. Faber

This paper investigates the impact of Malmquist bias on the distance to the Virgo cluster determined by the H_0 Key Project using M100, and consequently on the derived value of H_0. Malmquist bias is a volume-induced statistical effect which causes the most probable distance to be different from the raw distance measured. Consideration of the bias in the dis

Steven S. Vogt, Artie P. Hatzes, Anthony A. Misch, M. Kurster

We present 23 Doppler images of the spotted RS CVn star HR 1099 from 1981 to 1992. HR 1099 shows a large cool polar spot which has persisted for the 11 years of this study and other low-latitude spots which come and go on relatively short timescales. The polar spot has variable protuberances which look very similar to the time-variable vertical extensions of

Roelof Bottema, Jeroen P. E. Gerritsen

The spiral galaxy NGC 6503 exhibits a regular kinematical structure except for a remarkable drop of the stellar velocity dispersion values in the central region. To investigate the dynamics of the disc a theoretical framework has been described. This includes a mass decomposition of the galaxy into a family of disc/halo realizations compatible with the obser

Riccardo Giovanelli, Eric Avera, Igor Karachentsev

We present HI line observations of 744 edge-on spiral galaxies, extracted from the Flat Galaxy Catalog of Karachentsev et al. (1993). Fluxes, systemic velocities and line widths are given for 587 detected galaxies, as well as search parameters for 157 undetected systems. Widths are corrected for instrumental broadening, smoothing, signal-to--noise and profil

W. Bednarek, R. J. Protheroe

We investigate the consequences of the acceleration of heavy nuclei (e.g. iron nuclei) by the Crab pulsar. Accelerated nuclei can photodisintegrate in collisions with soft photons produced in the pulsar&#39;s outer gap, injecting energetic neutrons which decay either inside or outside the Crab Nebula. The protons from neutron decay inside the nebula are trap

W. Bednarek, R. J. Protheroe

Based on the detected variability time scales of X-ray and TeV gamma-ray emission, and the observed multiwavelength photon spectrum, of Mrk 421 we place constraints on the allowed parameter space (magnetic field and Doppler factor of the emission region) for the homogeneous synchrotron self-Compton model. The spectra calculated for the allowed parameters are

Piet Hut, Jeffrey M. Arnold, Junichiro Makino, Stephen L. W. McMillan

We present the outline of a research project aimed at designing and constructing a hybrid computing system that can be easily scaled up to petaflops speeds. As a first step, we envision building a prototype which will consist of three main components: a general-purpose, programmable front end, a special-purpose, fully hardwired computing engine, and a multi-

Toru Ohira

We propose here an autonomous traffic signal control model based on analogy with neural networks. In this model, the length of cycle time period of traffic lights at each signal is autonomously adapted. We find a self-organizing collective behavior of such a model through simulation on a one-dimensional lattice model road: traffic congestion is greatly diffu

R. M. Cavalcanti, C. A. A. de Carvalho

The density of states and the Hall conductivity of a two-dimensional electron gas in a uniform magnetic field and in the presence of a delta impurity are exactly calculated using elementary field theoretic techniques. Although these results are not new, our treatment is explicitly gauge-invariant, and can be easily adapted to other problems involving a delta

Miao Li, Emil Martinec

We compute the entropy of 5d black holes carrying up to three charges using matrix theory.

Patrick B. Hall, Paul Martini, D. L. Depoy, Ian Gatley

A candidate radio-loud broad absorption line quasar (RLBAL) has been reported by Becker et al. (1997). We present JHK observations of this object and three other radio-detected BALs taken with the new Michigan-Dartmouth-MIT/Ohio State/Aladdin IR Camera (MOSAIC) on the KPNO 4-meter. The candidate RLBAL 1556+3517 has B-K=6.63, redder than all but one or two kn

S. J. Brodsky, F. S. Navarra

Recent data on inclusive B decays into charmonium states taken by the CLEO collaboration suggest that a sizeable fraction of the nonleptonic decays may consist of the $J/ψΛ\overline p$ three body final state, corresponding to a distinct enhancement in the inclusive $J/ψ$ momentum distribution. The kinematical boundary of this structure corresponds to the cas

E. J. Kerins

In a previous study it was proposed that the Galactic dark matter being detected by gravitational microlensing experiments such as MACHO may reside in a population of dim halo globular clusters comprising mostly or entirely low-mass stars just above the hydrogen-burning limit. It was shown that, for the case of a standard isothermal halo, the scenario is con

Ken Kiers, Nathan Weiss

Motivated by the effect of matter on neutrino oscillations (the MSW effect) we study in more detail the propagation of neutrinos in a dense medium. The dispersion relation for massive neutrinos in a medium is known to have a minimum at nonzero momentum p \sim (G_Fρ)/\sqrt{2}. We study in detail the origin and consequences of this dispersion relation for both

Jason X. Prochaska, Arthur M. Wolfe

We present the first results of an ongoing program to investigate the kinematic characteristics of high redshift damped lya systems. Because damped lya systems are widely believed to be the progenitors of current massive galaxies, an analysis of their kinematic history allows a direct test of galaxy formation scenarios. We have collected a kinematically unbi

John Lott

We give relationships between the vanishing of the A-hat genus and the possibility that a spin manifold can collapse with curvature bounded below.

Giacomo Mauro D&#39;Ariano, Massimiliano Sacchi

We show the equivalence between two different communication schemes that employ a couple of modes of the electromagnetic field. One scheme uses unconventional heterodyne detection, with correlated signal and image-band modes in a twin-beam state from parametric downconversion. The other scheme is realized through a complex-number coding over quadrature-squee

John C. Collins, Andreas Freund

With the aid of simple examples we show how to make simple estimates of the sizes of higher-order Feynman graphs. Our methods enable appropriate values of renormalization and factorization scales to be made. They allow the diagnosis of the source of unusually large corrections that are in need of resummation.

Dan Maoz

Relatively few intensively star-forming galaxies at redshifts z>2.5 have been found in the Hubble Deep Field (HDF). This has been interpreted to imply a low space density of elliptical galaxies at high z, possibly due to a late (z<2.5) epoch of formation, or to dust obscuration of the ellipticals that are forming at z~3. I use HST UV (2300 Ang) images of 25

Jérôme Martin, Dominik J. Schwarz

We study the influence of the reheating and equality transitions on superhorizon density perturbations and gravitational waves. Recent criticisms of the `standard result&#39; for large-scale perturbations in inflationary cosmology are rectified. The claim that the `conservation law&#39; for the amplitude of superhorizon modes was empty is shown to be wrong.

Paolo Muratore Ginanneschi

The theory of stochastic differential equations is exploited to derive the Hopf&#39;s identities for a passive scalar advected by a Gaussian drift field delta-correlated in time. The result holds true both for compressible and incompressible velocity field.

J. A. Crittenden

The first five years of operation of the multi-purpose experiments ZEUS and H1 at the electron-proton storage ring facility HERA have opened a new era in the study of vector-meson production in high-energy photon-proton interactions. The high center-of-mass energy available at this unique accelerator complex allows investigations in hitherto unexplored kinem

E. Lipparini, N. Barberan, M. Barranco, M. Pi

We have investigated edge modes of different multipolarity sustained by quantum dots submitted to external magnetic fields. We present a microscopic description based on a variational solution of the equation of motion for any axially symmetric confining potential and multipole mode. Numerical results for dots with different number of electrons whose ground-

A. S. Belyaev, A. V. Gladyshev

The excess of high Q^2 events at HERA has been the subject of recent extensive studies in the framework of several models related to new physics. Here, we would like to concentrate on the most promising, from our point of view, model describing HERA anomaly. We investigate HERA events within the R-parity broken SUSY model and check its relation to LEP and TE

M. Gekhtman, M. Shapiro

In this paper we prove the complete integrability of Toda flows on generic coadjoint orbits in simple Lie algebras.

L. H. Ford

If one analyzes the effects of electromagnetic vacuum fluctuations upon an electron interference pattern in an approximation in which the electrons follow classical trajectories, an ultraviolet divergence results. It is shown that this divergence is an artifact of the classical trajectory approximation, and is absent when the finite sizes of electron wavepac

Giacomo M. D&#39;Ariano, Matteo G. A. Paris

Homodyne tomography provides a way for measuring generic field-operators. Here we analyze the determination of the most relevant quantities: intensity, field, amplitude and phase. We show that tomographic measurements are affected by additional noise in comparison with the direct detection of each observable by itself. The case of of coherent states has been