September 1997 arXiv papers — page 12

Z. -Q. Shen, T. -S. Wan, J. M. Moran, D. L. Jauncey

We report the results of a 5 GHz southern hemisphere VLBI survey of compact extragalactic radio sources. These observations were undertaken with the SHEVE array plus Shanghai station in November 1992. A sample of 22 sources was observed and images of 20 of them were obtained. Of the 20 sources imaged, 15 showed core-jet structure, one had a two-sided jet and

S. Capitani, M. Goeckeler, R. Horsley, H. Oelrich

We report on preliminary results of a high statistics quenched lattice QCD calculation of nucleon matrix elements within the Symanzik improvement programme. Using the recently determined renormalisation constants from the Alpha Collaboration we present a fully non-pertubative calculation of the forward nucleon axial matrix element with $O(a)$ lattice artifac

B. Y. Hou, W. L. Yang

In this paper, we propose an elliptic algebra $A_{q,p;\hatπ}(\hat{gl_2})$ which is based on the relations $RLL=LLR^{*}$, where $R$ and $R^{*}$ are the dynamical R-maxtrices of $A^{(1)}_{1}$ type face model with the elliptic moduli shifted by the center of the algebra. From the Ding-Frenkel correspondence, we find that its corresponding (Drinfeld) current alg

V. V. Vershinin

The notion of Vassiliev algebra in case of hanlebodies is developed. The analogues of the results of John Baez for links in handlebodies are proved. That means that there exists a one-to-one correspondence between the special class of finite type invariants of links in hanlebodies and the homogeneous Markov traces on Vassiliev algebras. This approach uses th

R. Simon, Mary Selvadoray, Arvind, N. Mukunda

We exploit results on the classical Stieltjes moment problem to obtain completely explicit necessary and sufficient conditions for the photon number distribution p(n) of a radiation field mode to be classical. These conditions are given in two forms - respectively local and global in the individual photon number probabilities. Central to the first approach i

Joachim Schirmer

We explicitly construct a star product for the complex Grassmann manifolds using the method of phase space reduction. Functions on $\mathbb{C}^{(p+q)\cdot p~*}$, the space of $(p+q)\times p$ matrices of rank p, invariant under the right action of $Gl(p,\mathbb{C})$ can be regarded as functions on the Grassmann manifold $G_{p,q}(\mathbb{C})$, but do not form

A. Wierling, G. Röpke

A self-consistent determination of the spectral function and the self-energy of electrons in a hot and dense plasma is reported. The self-energy is determined within the approximation of the screened potential. It is shown, that the quasi-particle concept is not an adequate concept for hot and dense plasmas, since the width of the spectral function has to be

G. Roepke

Within generalized linear response theory, an expression for the dielectric function is derived which is consistent with standard approaches to the electrical dc conductivity. Explicit results are given for the first moment Born approximation. Some exact relations as well as the limiting behaviour at small values of the wave number and frequency are investig

Amand Faessler, A. J. Buchmann, M. I. Krivoruchenko

The Green's functions are constructed and a one-loop calculation is given for the scalar and vector densities and for the equation of state of nuclear matter with a Bose condensate of dibaryons. This is the lowest approximation in the loop expansion of quantum hadrodynamics, sufficient to account for the presence of dibaryons not in the condensate in the

W. Poeschl, D. Vretenar, G. A. Lalazissis, P. Ring

The Relativistic Hartree Bogoliubov (RHB) model is applied in the self-consistent mean-field approximation to the description of the neutron halo in the mass region above the s-d shell. Pairing correlations and the coupling to particle continuum states are described by finite range two-body forces. Finite element methods are used in the coordinate space disc

A. V. Smirnov, Yu. N. Uzikov

The deuteron break-up exclusive reaction $p+d \to N(180^{\circ}) + (NN)(0^{\circ})$ is considered in the framework of the one-nucleon-exchange mechanism at the incident proton kinetic energy 0.2--2 GeV and the relative energy of nucleons in the forward going final NN-pair $E_{NN}=0$--20 MeV, that is close to the kinematical conditions of the planned experime

Dae Kwan Kim, Chul Koo Kim

We present a functional Schrödinger picture formalism of the (1+1)-dimensional $O(N) $ nonlinear sigma model. The energy density has been calculated to two-loop order using the wave functional of a gaussian form, and from which the nonperturbative mass gap of the boson fields has been obtained. The functional Schrödinger picture approach combined with the va

V. I. Yukalov, E. P. Yukalova

The state of art in studying thermodynamic properties of hot and dense nuclear matter is reviewed with the special emphasis on the confinement-deconfinement transition between hadron matter and quark-gluon plasma. The most popular models used for describing deconfinement are analysed, including statistical bootstrap models, pure phase models, the model of cl

Jong Bock Kim, Joon Ha Kim, Hyun Kyu Lee

Recent measurements of deuterium abundances from QSO absorption spectra show two conflicting numbers, which differ by an order of magnitude. Allowing the neutrino degeneracy together with gravitational constant variation at the epoch of primordial nucleosynthesis, the implication of these observations on the ^6Li, ^9Be and ^11B abundances will be discussed.

B. Blok, M. Shifman, Da-Xin Zhang

We discuss the issue of the local quark-hadron duality at high energies in two- and four-dimensional QCD. A mechanism of the dynamical realization of the quark-hadron duality in two- dimensional QCD in the limit of large number of colors, N_c -> \infty, (the 't Hooft model) is considered. A similar mechanism of dynamical smearing may be relevant in four-

J. P. Rodriguez, P. D. Sacramento, V. R. Vieira

The effect of anisotropy in the nearest-neighbor spin interactions that couple $N\geq 2$ consecutive spin-1/2 antiferromagnetic chains is studied theoretically by considering the limit where the coupling is purely of the Ising type. An analysis based on the equivalent Luttinger model reveals that the groundstate is an Ising antiferromagnet in general.

Rychard J. Bouwens, Laura Cayon, Joseph Silk

We develop an idealized inside-out formation model for disk galaxies to include a realistic mix of galaxy types and luminosities that provides a fair match to the traditional observables. The predictions of our infall models are compared against identical models with no-size evolution by generating fully realistic simulations of the HDF, from which we recove

J. M. Liu

Using our photoionization code CIRRUS, we show that the study of proximity effect on metal elements provides a possibility of placing constraints on the spectral shape of the metagalactic UV background (MUVB). From theoretical point of view, the most optimum indicator of the spectral shape of the MUVB is the ratio OIV/OIII. Unlike previous thought, the ratio

Henry E. Kandrup

This paper discusses the possibility of constructing time-independent solutions to the collisionless Boltzmann equation which depend on quantities other than global isolating integrals such as energy and angular momentum. The key point is that, at least in principle, a self-consistent equilibrium can be constructed from any set of time-independent phase spac

I. A. Zaliznyak, D. C. Dender, C. Broholm, Daniel H. Reich

We report an inelastic neutron scattering study of antiferromagnetic spin dynamics in the Haldane chain compound Ni(C2H8N2)2NO2ClO4 (NENP) under external hydrostatic pressure P = 2.5 GPa. At ambient pressure, the magnetic excitations in NENP are dominated by a long-lived triplet mode with a gap which is split by orthorhombic crystalline anisotropy into a low

Eric V. Siegel

Fourteen linguistically-motivated numerical indicators are evaluated for their ability to categorize verbs as either states or events. The values for each indicator are computed automatically across a corpus of text. To improve classification performance, machine learning techniques are employed to combine multiple indicators. Three machine learning methods

William K. Wootters

The entanglement of a pure state of a pair of quantum systems is defined as the entropy of either member of the pair. The entanglement of formation of a mixed state is defined as the minimum average entanglement of an ensemble of pure states that represents the given mixed state. An earlier paper [Phys. Rev. Lett. 78, 5022 (1997)] conjectured an explicit for

T. Banks, W. Fischler, I. R. Klebanov, L. Susskind

We consider Matrix theory compactified on T^3 and show that it correctly describes the properties of Schwarzschild black holes in 7+1 dimensions, including the energy-entropy relation, the Hawking temperature and the physical size, up to numerical factors of order unity. The most economical description involves setting the cut-off N in the discretized light-

Yuri Bespalov, Thomas Kerler, Volodymyr Lyubashenko, Vladimir Turaev

Let H be a Hopf algebra in a rigid braided monoidal category with split idempotents. We prove the existence of integrals on (in) H characterized by the universal property, employing results about Hopf modules, and show that their common target (source) object Int H is invertible. The fully braided version of Radford's formula for the fourth power of the

Ewa Czuchry, Wojciech Kopczynski

This paper contains discussion of the problem of motion of extended i.e. non point test bodies in multidimensional space. Extended bodies are described in terms of so called multipole moments. Using approximated form of equations of motion for extended bodies deviation from geodesic motion is derived. Results are applied to special form of space-time.

Jonathan A. Bagger

This talk discusses the prospects for supersymmetry studies at the LHC and NLC. The results are based on those of the Supersymmetry Working Group at the 1996 Snowmass Workshop.

William G. Laarakkers, Eric Poisson

Numerical models of rotating neutron stars are constructed for four equations of state using the computer code RNS written by Stergioulas. For five selected values of the star's gravitational mass (in the interval between 1.0 and 1.8 solar masses) and for each equation of state, the star's angular momentum is varied from J=0 to the Keplerian limit J=

R. Jackiw

The story of (Ward-)Takahashi relations and their impact on physical theory is reviewed.

E. Katz, U. -J. Wiese

We use renormalization group methods to derive equations of motion for large scale variables in fluid dynamics. The large scale variables are averages of the underlying continuum variables over cubic volumes, and naturally live on a lattice. The resulting lattice dynamics represents a perfect discretization of continuum physics, i.e. grid artifacts are compl

David Clarke, Steven Strong

We present a detailed discussion of both theoretical and experimental evidence in favour of the existence of states of ``confined coherence'' in metals of sufficiently high anisotropy and with sufficiently strong correlations. The defining property of such a state is that single electron coherence is confined to lower dimensional subspaces (planes or

Seong-Gon Kim, I. I. Mazin, D. J. Singh

We report first principles LDA calculations of the electronic structure and thermoelectric properties of $β$-Zn$_{4}$Sb$_{3}$. The material is found to be a low carrier density metal with a complex Fermi surface topology and non-trivial dependence of Hall concentration on band filling. The band structure is rather covalent, consistent with experimental obser

Robert de Mello Koch, João P. Rodrigues

The matrix theory description of the discrete light cone quantization of $M$ theory on a $T^{2}$ is studied. In terms of its super Yang- Mills description, we identify symmetries of the equations of motion corresponding to independent rescalings of one of the world sheet light cone coordinates, which show how the $S$ duality of Type IIB string theory is real

Shun-Jen Cheng, Victor Kac, Minoru Wakimoto

In this paper we classify extensions between irreducible finite conformal modules over the Virasoro algebra, over the current algebras and over their semidirect sums.

S. Bertolini, J. Matias

We study the effect of supersymmetric contributions to the effective quark transition $b\to sγγ$, including leading order QCD effects. We apply the discussion to the decay $B_s\toγγ$. Even though one-particle irreducible contributions could play a role, numerical cancelations make the amplitude for the two-photon emission strongly correlated to the $b\to sγ$

R. L. Jaffe, Xuemin Jin, Jian Tang

We introduce twist-two quark interference fragmentation functions in helicity density matrix formalism and study their physical implications. We show how the nucleon's transversity distribution can be probed through the final state interaction between two mesons ($π^+π^-$, $K\bar K$, or $πK$) produced in the current fragmentation region in deep inelastic

Owen Dando, Ruth Gregory

We analyse the gravitational field of a global monopole within the context of low energy string gravity, allowing for an arbitrary coupling of the monopole fields to the dilaton. Both massive and massless dilatons are considered. We find that, for a massless dilaton, the spacetime is generically singular, whereas when the dilaton is massive, the monopole gen

John W. Barrett, Louis Crane

Relativistic spin networks are defined by considering the spin covering of the group SO(4), SU(2) times SU(2). Relativistic quantum spins are related to the geometry of the 2-dimensional faces of a 4-simplex. This extends the idea of Ponzano and Regge that SU(2) spins are related to the geometry of the edges of a 3-simplex. This leads us to suggest that ther

Boris Stern, Juri Poutanen, Roland Svensson

We observe strong correlations between the temporal properties of gamma ray bursts (GRBs) and their apparent peak brightness. The strongest effect (with a significance level of 10^{-6}) is the difference between the brightness distributions of simple bursts (dominated by a single smooth pulse) and complex bursts (consisting of overlapping pulses). The latter

Matthias Neubert

The decays B -> D^{**} pi, where D^{**} is a narrow p-wave charm resonance, are investigated in the context of a generalized factorization hypothesis, including the leading nonfactorizable corrections. The decay rates for these processes are related to the corresponding semileptonic rates at maximum recoil. It is pointed out that the current data on the bran

Norbert Dragon, Sergei M. Kuzenko

We construct a consistent self-coupling for the vector-tensor multiplet in N = 2 harmonic central charge superspace.

D Duque, P Tarazona

We present a simple one-dimensional model with molecular interactions favouring the formation of clusters with a defined optimal size. Increasing the density, at low temperature, the system goes from a nearly-ideal gas of independent molecules to a system with most of the molecules in optimal clusters, in a way that resembles the formation of micelles in a d

Konstantin G. Zloshchastiev

We justify the way of the direct quantization which means immediate quantization of a conservation law. It is shown that this approach is equivalent to introducing the super Hamiltonian on a minisuperspace in spirit of the Wheeler-DeWitt's approach. Then we will have: (i) all values are observable and have an obvious physical meaning and well-defined app

M. A. Ivanov, J. G. Korner, V. E. Lyubovitskij, A. G. Rusetsky

Exclusive nonleptonic decays of bottom baryons to charm baryons and pseudoscalar light mesons are analyzed within a relativistic three-quark model. We include factorizing as well as nonfactorizing contributions to the decay amplitudes. The total contribution of the nonfactorizing diagrams amount up to 30% of the factorizing contributions in amplitude. We pre

Dominik J. Schwarz

The spectrum of gravitational waves that have been produced in inflation is modified during cosmological transitions. Large drops in the number of relativistic particles, like during the QCD transition or at $e^+e^-$ annihilation, lead to steps in the spectrum of gravitational waves. We calculate the transfer function for the differential energy density of g

Francisco Delgado C., Bogdan Mielnik, Marco A. Reyes

The 'classical interpretation' of the wave function psi(x) reveals an interesting operational aspect of the Helmholtz spectra. It is shown that the traditional Sturm-Liouville problem contains the simplest key to predict the squeezing effect for charged particle states.

Reinhard H"aring-Oldenburg

Is is shown that the quantum Weyl group of $sl_2$ contains an element that is a cylinder twist, i.e. it gives rise to representations of the braid group of Coxeter type B.

J. R. Mureika

In a previous article (physics/9705004), the best 100m performances in track and field were determined by accounting for wind effects and atmospheric drag. In this report, I seek to ascertain what was the "fastest" 100m final through a statistical analysis of the competitors' times. Considered are the 100 finals from the 1984-1996 Olympic Games,

Miklos Gyulassy, Yang Pang, Bin Zhang

We propose a test of Monte Carlo Parton Cascade models based on analytic solutions of covariant kinetic theory for longitudinally boost and transverse translation invariant boundary conditions. We compute the evolution of the transverse energy per unit rapidity for typical mini-jet initial conditions expected in ultra-relativistic nuclear collisions. The kin

G. Q. Li, C. -H. Lee, G. E. Brown

The recent past witnesses the growing interdependence between the physics of hadrons, the physics of relativistic heavy-ion collisions, and the physics of compact objects in astrophysics. A notable example is the kaon which plays special roles in all the three fields. In this talk, we first review the various theoretical investigations of kaon properties in

Mirna Džamonja, Saharon Shelah

This note gives two results on guessing unbounded subsets of lambda^+. The first is a positive result and applies to the situation of lambda regular, while the second is a negative consistency result which applies to the situation of lambda singular. Both results are connected to an earlier result of the same authors in which they showed that a certain versi

A. C. V. V. de Siqueira, I. A. Pedrosa, E. R. Bezerra de Mello

We use the time-dependent invariant method in a geometric approach (Jacobi fields) to quantize the motion of a free falling point particle in the Schwarzschild black hole. Assuming that the particle comes from infinity, we obtain the relativistic Schrödinger wave function for this system.

John C. Collins, L. Frankfurt, M. Strikman

This talk summarized the proof of hard-scattering factorization for exclusive deep-inelastic processes, such as diffractive meson production.

Brian Woodahl, Michelle Parry, Shu-Ju Tu, Ephraim Fischbach

It has been shown recently that the exchange of virtual neutrino pairs leads to an unphysically large energy-density in neutron stars and white dwarfs, unless neutrinos have a minimum mass, m > 0.4 eV. Here we consider the possibility that the presence of trapped low-energy neutrinos can suppress the exchange of virtual neutrino pairs, thereby avoiding a lar

Bing An Li

A Lagrangian of electroweak interactions without Higgs is used to study the contributions of quarks and leptons to the masses of the W and the Z bosons. It is shown that the $SU(2)\times U(1)$ symmetry is broken by both fermion masses and axial-vector components of the intermediate bosons. The masses of the W and the Z bosons are obtained to be (m^{2}_{W}={1

J. O. Andersen

Chapter one is devoted to a study of fermions and bosons in two spatial dimensions in external electromagnetic fields. The effectve action is calculated by integrating out the matter fields. In chapter two, I investigate the resummation program of Braaten and Pisarski. I calculate the screening mass squared and the free energy in Yukwava theory to two and th

Carlos Munoz

Charge and color breaking minima in SUSY theories might make the standard vacuum unstable. In this talk a brief review of this issue is performed. When a complete analysis of all the potentially dangerous directions in the field space of the theory is carried out, imposing that the standard vacuum should be the global minimum, the corresponding constraints t

C. Bernard, T. Blum, T. DeGrand, C. DeTar

The MILC collaboration computation of heavy-light decay constants is described. Results for $f_B$, $f_{B_s}$, $f_D$, $f_{D_s}$ and their ratios are presented. These results are still preliminary, but the analysis is close to being completed. Sources of systematic error, both within the quenched approximation and from quenching itself, are estimated, although

S. Hegyi

A generalization of the Polyakov-Koba-Nielsen-Olesen scaling law of the multiplicity distributions P(n,s) is developed. It states that a suitable change in the normalization point of P(n,s) compensated by a rescaling can restore data collapsing onto a universal curve if the original scaling rule is violated. We show that the iteratively executed transformati

Zhenjun Xiao

In this paper we pursue a consistent leptoquark interpretation for HERA anomalies in the framework of Technicolor. We find that: (a) one F=0 scalar Technicolor leptoquark $P_3^{'}$ with a mass of 200 GeV can provide the required contributions to account for the excess of both neutral and charged current events with high-$Q^2$ at HERA; (b) the current dat

Hisao Nakkagawa, Hiroshi Yokota

We have applied the recently proposed renormalization group improvement procedure of the finite temperature effective potential, and have investigated extensively the phase structure of the massive scalar $ϕ^4$ model, showing that the $ϕ^4$ model has a rich 3-phase structure at $T \neq 0$, two of them are not seen in the ordinary perturbative analysis. Tempe

J. -F. Lagae, D. K. Sinclair

We investigate a class of actions for lattice QCD with staggered quarks aimed at reducing the flavour symmetry violations associated with using staggered fermions. These actions replace the gauge field link fields in the quark action with covariantly smeared fields. As such they are an extension of actions considered by the MILC collaboration. We show that s

L. Del Debbio

We study the dynamical breaking of chiral symmetry in the 3-d Thirring model for a small number of fermion species. The critical point is identified by fitting lattice data to an equation of state. The spectrum of the theory is studied to confirm the phase structure of the model.

Roberto Frezzotti, Karl Jansen

We discuss a simulation algorithm for dynamical fermions, which combines the multiboson technique with the Hybrid Monte Carlo algorithm. The algorithm turns out to give a substantial gain over standard methods in practical simulations and to be suitable for dealing with fermion zero modes in a clean and controllable way.

Eric Poisson

A rotating star's oblateness creates a deformation in the gravitational field outside the star, which is measured by the quadrupole-moment tensor. We consider the effect of the quadrupole moment on the orbital motion and rate of inspiral of a compact binary system, composed of neutron stars and/or black holes. We find that in the case of circular orbits,

A. M. Dyugaev, Yu. N. Ovchinnikov, P. Fulde, K. Kladko

We consider the contribution of magnetic impurities to the nuclear magnetic susceptibility $χ$ and to the specific heat $C$ of a metal. The impurity contribution to the magnetic susceptibility has a $1/T^2$ behaviour, and the impurity contribution to the specific heat has a $1/T$ behaviour, both in an extended region of temperatures $T$. In the case of a dir

Hsuan-Yi Chen, David Jasnow

A theoretical analysis of surface fluctuations of a freely standing thermotropic smectic-A liquid crystal film is provided, including the effects of viscous hydrodynamics. We find two surface dynamic modes (undulation and peristaltic). For long wavelengths and small frequencies in a thin film, the undulation mode is the dominant mode. Permeation enters the t

T. P. Devereaux, A. P. Kampf

A theory of electronic Raman scattering in nearly antiferromagnetic Fermi liquids is constructed using the phenomenological electron-electron interaction introduced by Millis, Monien, and Pines. The role of "hot spots" and their resulting signatures in the channel dependent Raman spectra is highlighted, and different scaling regimes are addressed. Th

S. Sorella, A. Parola

The dynamical properties of hole motion in an antiferromagnetic background are determined in one dimensional models in zero magnetic field, where spin isotropy holds, as well as in an external magnetic field. The latter case is also relevant, via particle-hole transformation, to the problem of hole propagation in one dimensional "superconductors". Th

N. M. R. Peres, P. D. Sacramento, J. C. Carmelo

The transport of charge and spin at finite energies is studied for the Hubbard chain in a magnetic field by means of the pseudoparticle perturbation theory. In the general case, this involves the solution of an infinite set of Bethe-ansatz equations with a flux. Our results refer to all densities and magnetizations. We express the charge and the spin-diffusi

K. B. Blagoev, J. R. Engelbrecht, K. S. Bedell

We investigate the behavior of weak ferromagnetic metals close to the ferromagnetic critical point. We show that in the limit of small magnetic moment the low temperature metallic phase is rigorously described by a local ferromagnetic Fermi liquid that has a momentum-independent self-energy. Whereas, non-Fermi liquid features develop at higher temperatures.

F. Green, M. P. Das

We review a semiclassical theory of high-field noise in degenerate conductors, based on propagator solutions to the Boltzmann equation for the fluctuation distribution function. The theory provides a microscopic description of correlation-induced suppression of noise in quantum-confined systems, such as heterojunction devices. It is also capable of describin

P. Schmelcher, F. K. Diakonos

The dynamics of one dimensional iterative maps in the regime of fully developed chaos is studied in detail. Motivated by the observation of dynamical structures around the unstable fixed point we introduce the geometrical concept of a turning point which represents a local minimum or maximum of the trajectory. Following we investigate the highly organized an

R. O. Vallejos, A. M. Ozorio de Almeida, C. H. Lewenkopf

We study the universal fluctuations of the Wigner-Smith time delay for systems which exhibit chaotic dynamics in their classical limit. We present a new derivation of the semiclassical relation of the quantum time delay to properties of the set of trapped periodic orbits in the repeller. As an application, we calculate the energy correlator in the crossover

F. Cecconi, R. Livi, A. Politi

A coupled-map lattice showing complex behavior in presence of a fully negative Lyapunov spectrum is considered. A phase transition from ordered to disordered evolution upon changing diffusive coupling is studied in detail. Various indicators provide a coherent description of the scenario: the existence of an intermediate transition region characterized by an

C. Giardina', R. Livi

The problem of the existence of a Strong Stochasticity Threshold in the FPU-beta model is reconsidered, using suitable microcanonical observables of thermodynamic nature, like the temperature and the specific heat. Explicit expressions for these observables are obtained by exploiting rigorous methods of differential geometry. Measurements of the correspondin

Rob Ivison, James Dunlop, David Hughes, Elese Archibald

We present the results of new rest-frame far-IR observations of the z = 4.25 radio galaxy, 8C1435+635, which not only confirm that it contains an enormous quantity of dust (as first inferred from its mm-wave detection by Ivison 1995) but also allow the first meaningful constraints to be placed on the mass of this dust and associated gas. The new measurements

J. M. Fierro, P. F. Michelson, P. L. Nolan, D. J. Thompson

Using the first three and a half years of observations from the Energetic Gamma Ray Telescope (EGRET) on board the Compton Gamma Ray Observatory (CGRO), phase-resolved analyses are performed on the emission from the three brightest high-energy gamma-ray pulsars, Crab, Geminga, and Vela. For each pulsar, it is found that there is detectable high-energy gamma-

Bruce A. Twarog, Keith M. Ashman, Barbara J. Anthony-Twarog

A set of 76 open clusters with abundances based upon DDO photometry and/or moderate dispersion spectroscopy has been transformed to a common [Fe/H] scale and used to study the local structure and evolution of the galactic disk. The metallicity distribution of clusters with R_GC is best described by two distinct zones. Between R_GC = 6.5 and 10 kpc, the distr

S. Leon, F. Combes, T. K. Menon

We have observed 70 galaxies belonging to 45 Hickson compact groups in the CO(1-0) and CO(2-1) lines, in order to determine their molecular content. We detected 57 galaxies, corresponding to a detection rate of 81%. We compare the gas content relative to blue and FIR luminosities of galaxies in compact groups with respect to other samples in the literature,

Alan M. Watson, Margaret M. Hanson

We have obtained the first classification spectrum and present the first direct spectral classification of the ionizing star of an ultracompact HII region. The ultracompact HII region is G29.96-0.02, a well-studied object with roughly twice solar metallicity. The near infrared K-band spectrum of the ionizing star exhibits CIV and NIII emission and HeII absor

Jacco Th. van Loon, Albert A. Zijlstra, Patricia A. Whitelock, Peter te Lintel Hekkert

We present N-band photometry for a sample of 21 dust- enshrouded AGB stars in the Large Magellanic Cloud, and three additional sources in the Small Magellanic Cloud. Together with near-IR photometry, this is used to give a tentative classification into carbon and oxygen-rich atmospheres. Bolometric luminosities are also estimated for these stars. In addition

C. L. Taylor, C. D. Wilson

We present 12CO J=1-0 observations from the Caltech Millimeter Array of a field in the nearby spiral galaxy M81. We detect emission from three features that are the size of large giant molecular clouds (GMCs) in the Milky Way Galaxy and M31, but are larger than any known in M33 or the SMC. The M81 clouds have diameters approximately 100 pc and molecular mass

Jacco Vink, Jelle Kaastra, Johan Bleeker

We present an analysis of ASCA X-ray data of SNR RCW 86. There appears to be a remarkable spectral variation over the remnant, indicating temperatures varying from 0.8 keV to > 3 keV. We have fitted these spectra with non-equilibrium ionization models and found that all regions are best fitted by emission from a hot plasma underabundant in metals (<0.25 sola

J. Heidt, S. J. Wagner

We present a study of the intraday variability behaviour of two samples of x-ray selected BL Lac objects, the EMSS and EXOSAT samples consisting of 22 and 11 sources, respectively. In both samples we were able to detect intraday variability in less than 40% of the sources only. The duty cycle (the fraction of time, when a BL Lac object is variable) in x-ray

Yoshiaki Sofue, Yoshinori Tutui, Mareki Honma, Akihiko Tomita

We have obtained high-resolution position-velocity (PV) diagrams along the major axes of the central regions of nearby galaxies in the CO-line emission using the Nobeyama 45-m telescope and the Millimeter Array. Nuclear rotation curves for 14 galaxies have been derived based on the PV diagrams using the envelope-tracing method. The nuclear rotation curves fo

Izumi Murakami, Kazuyuki Yamashita

We have examined the metal enrichment of the intergalactic medium (IGM) based on a galactic wind model. A galactic wind driven by supernovae brings metallic gas to the IGM but not so far beyond the gravitational potential. The expanding velocity of the outflow depends on the star formation timescale. Examining 3D calculation for the IGM in CDM model, we find

Daniel J. Eisenstein, Wayne Hu

We provide scaling relations and fitting formulae for adiabatic cold dark matter cosmologies that account for all baryon effects in the matter transfer function to better than 10% in the large-scale structure regime. They are based upon a physically well-motivated separation of the effects of acoustic oscillations, Compton drag, velocity overshoot, baryon in

Daniel Allcock, James A. Carlson, Domingo Toledo

We show that the moduli space M of marked cubic surfaces is biholomorphic to the quotient by a discrete group generated by complex reflections of the complex four-ball minus the reflection hyperplanes of the group. Thus M carries a complex hyperbolic structure: an (incomplete) metric of constant holomorphic sectional curvature.

M. Holtrop, D. Jordan, T. McIlvain, R. Alarcon

The coincidence cross-section and the interference structure function, R_LT, were measured for the 12C(e,e&#39;p) 11B reaction at quasielastic kinematics and central momentum transfer of q=400 MeV/c. The measurement was at an opening angle of theta_pq=11 degrees, covering a range in missing energy of E_m = 0 to 65 MeV. The R_LT structure function is found to

Michael Joyce, Tomislav Prokopec

The usual sphaleron bound and the statement of the impossibility of baryon production at a second order phase transition or analytic cross-over are reformulated in the first part of the paper as requirements of the expansion rate of the Universe at the electroweak scale. With an (exact or effective) additional contribution to the energy density scaling as 1/

I. Chepelev, A. A. Tseytlin

We address the issue of correspondence between classical supergravity and quantum super Yang-Mills (or Matrix theory) expressions for the long-distance, low-velocity interaction potentials between 0-branes and various bound states of branes. The leading-order potentials are known to be reproduced by the F^4 terms in the 1-loop SYM effective action. Using sel

Sandu Popescu, Daniel Rohrlich

Quantum mechanics permits nonlocality - both nonlocal correlations and nonlocal equations of motion - while respecting relativistic causality. Is quantum mechanics the unique theory that reconciles nonlocality and causality? We consider two models, going beyond quantum mechanics, of nonlocality: "superquantum" correlations, and nonlocal "jamming" of correlat

B. Holdom

We develop a framework especially suited to the autocorrelation properties observed in financial times series, by borrowing from the physical picture of turbulence. The success of our approach as applied to high frequency foreign exchange data is demonstrated by the overlap of the curves in Figure (1), since we are able to provide an analytical derivation of

Carlos M. Naon

In this talk I describe a recently introduced field-theoretical approach that can be used as an alternative framework to study one-dimensional systems of highly correlated particles.

Gordon Chalmers

Using twistor methods we derive a generating function which leads to the hyperk\&#34; ahler metric on a deformation of the Atiyah-Hitchin monopole moduli space. This deformation was first considered by Dancer through the quotient construction and is related to a charge two monopole configuration in a completely broken SU(3) gauge theory. The manifold and met

V. D. Skarzhinsky, J. Audretsch

We consider the Dirac equation in cylindrically symmetric magnetic fields and find its normal modes as eigenfunctions of a complete set of commuting operators. This set consists of the Dirac operator itself, the $z$-components of the linear and the total angular momenta, and of one of the possible spin polarization operators. The spin structure of the soluti

David Merritt, Gerald Quinlan

We study the effect of a massive central singularity on the structure of a triaxial galaxy using N-body simulations. Starting from a single initial model, we grow black holes with various final masses Mh and at various rates, ranging from impulsive to adiabatic. In all cases, the galaxy achieves a final shape that is nearly spherical at the center and close

Sanjoy K. Sarker

This paper is being withdrawn.

M. Bordag, K. Kirsten, D. V. Vassilevich

In the present paper we study the Faddeev-Popov path integral quantization of electrodynamics in an inhomogenious dielectric medium. We quantize all polarizations of the photons and introduce the corresponding ghost fields. Using the heat kernel technique, we express the heat kernel coefficients in terms of the dielectricity $ε(x)$ and calculate the ultra vi

Miguel Alcubierre, Joan Masso

We present a mathematical characterization of hyperbolic gauge pathologies in general relativity and electrodynamics. We show how non-linear gauge terms can produce a blow-up along characteristics and how this can be identified numerically by performing convergence analysis. Finally, we show some numerical examples and discuss the profound implications this