April 1998 arXiv papers — page 10

W. Landsman, R. C. Bohlin, S. G. Neff, R. W. O'Connell

We analyze ultraviolet (~1500 A) images of the old open clusters M67, NGC 188, and NGC 6791 obtained with Ultraviolet Imaging Telescope (UIT) during the second flight of the Astro observatory in March 1995. Twenty stars are detected on the UIT image of M67, including 11 blue stragglers, seven white dwarf candidates, and the yellow giant -- white dwarf binary

D. A. Frail, S. R. Kulkarni, D. S. Shepherd, E. Waxman

We present radio observations of the gamma-ray burster GRB 970228 made with the Very Large Array (VLA) and the Owens Valley Radio Observatory (OVRO) spanning a range of postburst timescales from one to 300 days. A search for a time-variable radio source was conducted covering an area which included a fading X-ray source and an optical transient, both of whic

T. Nikola, R. Genzel, F. Herrmann, S. C. Madden

We present observations of NGC 4038/39 in the [CII] 158 micron fine structure line taken with the MPE/UCB Far-infrared Imaging Fabry-Perot Interferometer (FIFI) on the KAO with 55" resolution. The total [CII] luminosity of the Antennae is 3.7x10^8 L(sun), which is about 1% of the FIR luminosity. The main part of the [CII] emission probably arises from ph

Mark Hurwitz, Stuart Bowyer, Robert Bristol, W. Van Dyke Dixon

The Berkeley spectrograph aboard the ORFEUS telescope made its second flight on the 14-day ORFEUS-SPAS II mission of the Space Shuttle Columbia in November/December 1996. Approximately half of the available observing time was dedicated to the Berkeley spectrograph, which was used by both Principal and Guest Investigators. The spectrograph's full bandpass

Mark Hurwitz, Immo Appenzeller, Juergen Barnstedt, Stuart Bowyer

We present the first intermediate-resolution (lambda / 3000) spectrum of the bright quasi-stellar object 3C273 at wavelengths between 900 and 1200 A. Observations were performed with the Berkeley spectrograph aboard the ORFEUS-SPAS II mission. We detect Lyman beta counterparts to previously-identified intergalactic Lyman-alpha features at cz = 19900, 1600, a

Mark Hurwitz

We present observations of H_2 fluorescence at wavelengths between 1000 and 1200 A from the bright reflection nebula IC 63. Observations were performed with the Berkeley spectrograph on the ORFEUS-SPAS II mission. To the best of our knowledge, this is the first detection of astrophysical H_2 fluorescent emission at these wavelengths (excluding planetary atmo

J. G. Bartlett, A. Blanchard, M. Le Dour, M. Douspis

We use current cosmic microwave background data to constrain cosmological parameters. The results are presented as confidence regions in the ($Ω$--$H_o$) -- plane for both open and flat geometries, and are based on a $χ^2$ minimization to the power spectrum. Although such an approach does not strictly apply to power spectrum estimates, the results should non

T. Joseph W. Lazio, James M. Cordes

The scattering diameters of Sgr A* and several nearby OH masers (~ 1" at 1 GHz) indicate that a region of enhanced scattering is along the line of sight to the Galactic center. We combine radio-wave scattering data and free-free emission and absorption measurements in a likelihood analysis that constrains the following parameters of the GC scattering reg

T. Joseph W. Lazio, James M. Cordes

The scattering diameters of Sgr A* and several nearby OH masers (~ 1" at 1 GHz) indicate that a region of enhanced scattering is along the line of sight to the Galactic center. The scattering diameter of an extragalactic source seen through this scattering region is larger by the ratio (Sun-GC distance)/(GC-scattering region separation). This ratio could

N. Mowlavi, G. Meynet, A. Maeder, D. Schaerer

An analysis of some properties of stellar models as a function of metallicity Z (and helium content Y) is presented, with special attention to those stars with metallicities higher than twice or three times solar. It is shown that the stellar properties as a function of Z are mainly determined by the effects of the opacities at sub-solar metallicities, and b

Matthew R. Bate, Cathie J. Clarke, Mark J. McCaughrean

We study the interpretation of the mean surface density of stellar companions as a function of separation (or the two point correlation function of stars) in star-forming regions. First, we consider the form of the functions for various simple stellar distributions (binaries, global density profiles, clusters, and fractals) and the effects of survey boundari

Henning Seemann

This thesis discusses the influence of magnetic fields on the instability of line-driven winds in O-stars and Wolf-Rayet stars. This combination is an important concept to understand the strong, observed winds from Wolf-Rayet stars. In the second part of the thesis a model is derived which describes the wind outside the equatorial plane. This model allows to

Uta Fritze - v. Alvensleben, Pierre - Alain Duc

Evolutionary synthesis models for Tidal Dwarf Galaxies (TDGs) are presented that allow to have varying proportions of young stars formed in the merger-induced starburst and of stars from the merging spirals' disks. Comparing model grids with observational data (see e.g. P.-A. Duc this conference for a review) we try to identify the present evolutionary s

A. D. Challinor, A. N. Lasenby

We present a new, fully covariant and manifestly gauge-invariant expression for the temperature anisotropy in the cosmic microwave background radiation resulting from scalar perturbations. We pay particular attention to gauge issues such as the definition of the temperature perturbation and the placing of the last scattering surface. In the instantaneous rec

S. Redner

Numerical data for the distribution of citations are examined for: (i) papers published in 1981 in journals which are catalogued by the Institute for Scientific Information (783,339 papers) and (ii) 20 years of publications in Physical Review D, vols. 11-50 (24,296 papers). A Zipf plot of the number of citations to a given paper versus its citation rank appe

Marcos Marino, Gregory Moore

We study Coulomb branch (``u-plane'') integrals for $\mathcal{N}=2$ supersymmetric $SU(2),SO(3)$ Yang-Mills theory on 4-manifolds $X$ of $b_1(X)>0, b_2^+(X)=1$. Using wall-crossing arguments we derive expressions for the Donaldson invariants for manifolds with $b_1(X)>0, b_2^+(X)>0$. Explicit expressions for $X=\IC P^1 \times F_g$, where $F_g$ is a R

T. J. Newman, Z. Toroczkai

We present a new method for extracting the persistence exponent theta for the diffusion equation, based on the distribution P of `sign-times'. With the aid of a numerically verified Ansatz for P we derive an exact formula for theta in arbitrary spatial dimension d. Our results are in excellent agreement with previous numerical studies. Furthermore, our r

M. Frank, E. Kirchberg

For a conditional expectation E on a (unital) C*-algebra A there exists a real number K>=1 such that the mapping (K.E-id_A) is positive if and only if there exists a real number L>=1 such that the mapping (L.E-id_A) is completely positive, among other equivalent conditions. The estimate min(K) <= min(L) <= min(K).[min(K)] is valid, where [.] denotes the inte

S. T. Johnson, E. M. Forgan, S. H. Lloyd, C. M. Aegerter

A small angle neutron scattering study of the flux-line lattice in a large single crystal of untwinned YBa2Cu3O is presented. In fields parallel to the c-axis, diffraction spots are observed corresponding to four orientations of a hexagonal lattice, distorted by the a-b anisotropy. A value for the anisotropy, the penetration depth ratio, of 1.18(2) was obtai

R. Aloisio, V. Azcoiti, G. Di Carlo, A. Galante

We present a detailed analysis of the QCD partition function in the Grand Canonical formalism. Using the fugacity expansion we find evidence for numerical instabilities in the standard evaluation of its coefficients. We discuss the origin of this problem and propose an issue to it. The correct analysis shows no evidence for a discontinuity in the baryonic de

Feng Yuan, Kuang-Ta Chao

We propose the color-octet mechanism combined with the two gluon exchange model for the diffractive $J/ψ$ production in hadron collisions. In the leading logarithmic approximation (LLA) in QCD, we find that the diffractive $J/ψ$ production rate is related to the off-diagonal gluon density in the proton and to the nonperturbative color-octet matrix element of

D. S. Golubev, A. D. Zaikin

We discuss a fundamental effect of the interaction-induced decoherence of the electron wave function in disordered metals. In the first part of the paper we consider a simple model of a quantum particle interacting with a bath of harmonic oscillators and analyze the physical origin of the effect. This exactly solvable model also allows to understand why the

Tae-Sun Park, Kuniharu Kubodera, Dong-Pil Min, Mannque Rho

The proton burning process p + p -> d + e(+) + ν(e), important for the stellar evolution of main-sequence stars of mass equal to or less than that of the Sun, is computed in effective field theory using chiral perturbation expansion to the next-to-next-to leading chiral order. This represents a model-independent calculation consistent with low-energy effecti

Toru Goto, Yasuhiro Okada, Yasuhiro Shimizu

Flavor changing neutral current processes such as $b \to s γ$, $b \to s l^+ l^-$, $b \to s ν\barν$, $ε_K$, $Δm_B$, $K^+ \to π^+ ν\barν$ and $\K_L \to π^0 ν\barν$ are calculated in the supersymmetric standard model based on supergravity. We consider two assumptions for the soft supersymmetry breaking terms. In the minimal case soft breaking terms for all scal

Takeo Moroi, Hitoshi Murayama

Mixed dark matter scenario can reconcile the COBE data and the observed large scale structure. So far the massive neutrino with a mass of a few eV has been the only discussed candidate for the hot dark matter component. We point out that the hadronic axion in the so-called hadronic axion window, f_a \sim 10^6 GeV, is a perfect candidate as hot dark matter wi

M. A. Halasz, A. D. Jackson, R. E. Shrock, M. A. Stephanov

We analyze the phase diagram of QCD with two massless quark flavors in the space of temperature, T, and chemical potential of the baryon charge, mu, using available experimental knowledge of QCD, insights gained from various models, as well as general and model independent arguments including continuity, universality, and thermodynamic relations. A random ma

B. Barbiellini

A variational method for many electron system is applied to momentum distribution calculations. The method uses a generating two-electron geminal and the amplitudes of the occupancies of one particle natural orbitals as variational parameters. It introduces correlation effects beyond the free fermion nodal structure.

I. M. Krichever

We outline an approach to a theory of various generalizations of the elliptic Calogero-Moser (CM) and Ruijsenaars-Shneider (RS) systems based on a special inverse problem for linear operators with elliptic coefficients. Hamiltonian theory of such systems is developed with the help of the universal symplectic structure proposed by D.H. Phong and the author. C

H. Babujian, A. Lima-Santos, R. H. Poghossian

Using quasiclassical limit of Baxter&#39;s 8 - vertex R - matrix, an elliptic generalization of the Knizhnik-Zamolodchikov equation is constructed. Via Off-Shell Bethe ansatz an integrable representation for this equation is obtained. It is shown that there exists a gauge transformation connecting this equation with Knizhnik-Zamolodchikov-Bernard equation fo

A. K. Kapoor, Pankaj Sharan

Using a scheme proposed earlier we set up Hamiltonian path integral quantization for a particle in two dimensions in plane polar coordinates.This scheme uses the classical Hamiltonian, without any $O(\hbar^2)$ terms, in the polar varivables. We show that the propagator satisfies the correct Schrödinger equation.

Shigeru Furuichi, Masanori Ohya, Hiroki Suyari

The dynamics of an atom on the Jaynes-Cummings model has been studied by an atomic inversion, von Neumann entropy and so on. In this letter, we will treat the Jaynes-Cummings model as a problem in non-equilibrium statistical mechanics and apply quantum mutual entropy to study the irreversible dynamics of a state for the atom on this model.

Roman Bezrukavnikov, Michael Finkelberg, Vadim Schechtman

The category $\cal{C}$ (studied by Andersen-Jantzen-Soergel) of representations of a Lusztig&#39;s small quantum group at a root of unity, together with its modular structure, is defined geometrically, using configuration spaces.

Alejandro Corichi

In this article we give an introduction to the Fock quantization of the Maxwell field. At the classical level, we treat the theory in both the covariant and canonical phase space formalisms. The approach is general since we consider arbitrary (globally-hyperbolic) space-times. The Fock quantization is shown to be equivalent to the definition of a complex str

S. S. Elbakian, E. V. Sekhpossian, A. G. Khachatryan

The expressions for wake fields, generated in plasma (in the plasma waveguide or unlimited plasma) by relativistic electron bunch, was received and analyzed for the cases of the presence and absence of strong external longitudinal magnetic field. For the both cases the comparative analysis of the dependence of field amplitudes on the parameters of the electr

Lu Lin

The possibility of a complex 4-dimensional space-time manifold is suggested. This may imply the existence of a matter wave.

J. Carbonell, B. Desplanques, V. A. Karmanov, J. -F. Mathiot

The wave function of a composite system is defined in relativity on a space-time surface. In the explicitly covariant light-front dynamics, reviewed in the present article, the wave functions are defined on the plane $ω\cd x=0$, where $ω$ is an arbitrary four-vector with $ω^2=0$. The standard non-covariant approach is recovered as a particular case for $ω= (

Tapani Hyttinen, Saharon Shelah

We prove a main gap theorem for e-saturated submodels of a homogeneous structure. We also study the number of e-saturated models, which are not elementarily embeddable to each other

Saharon Shelah

The original theme of the paper is the existence proof of ``there is < eta_alpha : alpha < lambda > which is a (lambda,J)-sequence for < I_i:i<delta >, a sequence of ideals. This can be thought of as in a generalization to Luzin sets and Sierpinski sets, but for the product prod_{i< delta} Dom(I_i), the existence proofs are related to pcf. The second theme i

Saharon Shelah

We deal with several pcf problems; we characterize another version of exponentiation: number of kappa-branches in a tree with lambda nodes, deal with existence of independent sets in stable theories, possible cardinality of ultraproduct, the depth of ultraproducts of Boolean Algebras. Also we give cardinal invariant for each lambda with pcf restriction and i

Saharon Shelah

We give a framework for dealing with 0-1 laws (for first order logic) such that expanding by further random structure tend to give us another case of the framework. From another perspective we deal with 0-1 laws when the number of solutions of first order formulas with parameters behave dichotomically.

Sakaé Fuchino, Saharon Shelah, Lajos Soukup

We study combinatorial principles known as stick and club. Several variants of these principles and cardinal invariants connected to them are also considered. We introduce a new kind of side-by-side product of partial orders which we call pseudo-product. Using such products, we give several generic extensions where some of these principles hold together with

Ryan Bissell-Siders

Can a computer which runs for time $ω^2$ compute more than one which runs for time $ω$? No. Not, at least, for the infinite computer we describe. Our computer gets more powerful when the set of its steps gets larger. We prove that they theory of second order arithmetic cannot be decided by computers running to countable time.

Xi Chen

We proved the existence of rational curves in every linear system on a general K3 surface and that all rational curves in the hyperplane class are nodal on a general K3 surface of small genus.

E. Ballico, L. Chiantini

Let X be a smooth projective surface. Here we study the postulation of a general union Z of fat points of X, when most of the connected components of Z have multiplicity 2. This problem is related to the existence of &#34;good&#34; families of curves on X, with prescribed singularities, most of them being nodes, and to the cohomology of suitable line bundles

Claude LeBrun

We show that solutions of the Seiberg-Witten equations lead to non-trivial lower bounds for the L2-norm of the Weyl curvature of a compact Riemannian 4-manifold. These estimates are then used to derive new obstructions to the existence of Einstein metrics. These results considerably refine those previously obtained using scalar-curvature estimates alone.

Jaume Garriga

We present a non-singular instanton describing the creation of an open universe with a compactified extra dimension. The four dimensional section of this solution is a singular instanton of the type introduced by Hawking and Turok. The ``singularity&#39;&#39; is viewed in five dimensions as a smooth bubble of ``nothing&#39;&#39; which eats up a portion of sp

Stephen G. Naculich, Henric Rhedin, Howard J. Schnitzer

One-instanton predictions are obtained from the Seiberg-Witten curve derived from M-theory by Landsteiner and Lopez for the Coulomb branch of N=2 supersymmetric SU(N) gauge theory with a matter hypermultiplet in the antisymmetric representation. Since this cubic curve describes a Riemann surface that is non-hyperelliptic, a systematic perturbation expansion

D. Z. Freedman, H. Osborn

Recently a non-perturbative formula for the RG flow between UV and IR fixed points of the coefficient in the trace of the energy momentum tensor of the Euler density has been obtained for N=1 SUSY gauge theories by relating the trace and R-current anomalies. This result is compared here with an earlier perturbation theory analysis based on a naturally define

Debajyoti Choudhury, John Ellis

We present first calculations of new long-distance contributions to $B_s \to γγ$ decay due to intermediate $D_s$ and $D_s^*$ meson states. The relevant $γ$ vertices are estimated using charge couplings and transition moment couplings. Within our uncertainties, we find that these long-distance contributions could be comparable to the known short-distance cont

Kim Maltman

Narison&#39;s $τ$-decay-like sum rule for determining the strange quark mass is re-investigated, taking into account isospin-breaking corrections in the extraction of the input spectral functions from $e^+e^-\to hadrons$ data. The corrections, estimated using experimental data on vector meson electromagnetic decay constants and a QCD sum rule analysis of the

Kim Maltman

A numerical error is pointed out in the existing expression for the order $α_s^2$ longitudinal component of the squared-mass (D=2) contribution to the hadronic $τ$ decay rate. The corrected version is found to be such that, to order $α_s^2$, each term in the resulting series is larger than the previous one, ruling out the direct use of flavor breaking in had

Surajit Chakrabarti, Debajyoti Choudhury, Rohini M. Godbole, Biswarup Mukhopadhyaya

We discuss the possibility of observing doubly charged Higgs bosons in $γγ$ collisions. We find that one can increase the range of observability close to the kinematic limit by a judicious choice of the polarisations of the initial $e^-/ e^+$ beams as well as the initial laser beam photons which are made to back-scatter from the former. We also note that, in

Stefano Moretti, Leif Lönnblad, Torbjörn Sjöstrand

Over the years, many jet clustering algorithms have been proposed for the analysis of hadronic final states in $e^+e^-$ annihilations. These have somewhat different emphasis and are therefore more or less suited for various applications. We here review some of the most used and compare them from a theoretical and experimental point of view.

Xiao-Gang He, Wei-Shu Hou

The small P wave compoment of $B\to J/ψK^*$ measured by CLEO makes it practical to measure $\sin2β$ using $B^0\to J/ψK^{*0}\to J/ψK_S π^0$, independent from $B^0\to J/ψK_S$. Because these modes are color suppressed, new physics enhanced color dipole $bsg$ coupling, as hinted from the persistent ${\cal B}_{s.l.}$ and $n_C$ problems as well as the newly observ

Fumiaki Araki, Hideo Suganuma, Hiroshi Toki

We study the connection between monopoles and instantons in the Polyakov-like gauge, and the behavior of the monopole trajectories generated by instantons at finite temperature. The monopole trajectories become long and complicated at the zero-temperature which can be regarded as monopole condensation. On the other hand, they tend to become simple at finite

Yoshiaki Koma, Hideo Suganuma, Hiroshi Toki

We study the flux-tube solution in the dual Ginzburg-Landau (DGL) theory and apply it to the understanding of quark-gluon-plasma (QGP) formation in the ultra-relativistic heavy ion collision as the multi-flux-tube system. It is concluded that the annihilation process of two flux-tubes can contribute to the QGP formation with the energy deposition $\sim 4 GeV

J. Ambjorn, J. Greensite

We present a number of arguments relating magnetic disorder to center disorder, in pure Yang-Mills theory in D=3 and D=4 dimensions. In the case of the D=3 Georgi-Glashow model, we point out that the abelian field distribution is not adequatedly represented, at very large scales, by that of a monopole Coulomb gas. The onset of center disorder is associated w

Michael Creutz

I discuss some of the difficulties with formulating chiral symmetry on the lattice and review a recently proposed scheme for a fully finite and exactly gauge invariant lattice regularization of the standard model.

M. Laine, K. Rummukainen

We study the MSSM finite temperature electroweak phase transition with lattice Monte Carlo simulations, for a large Higgs mass (m_H ~ 95 GeV) and light stop masses (m_tR ~ 150...160 GeV). We employ a 3d effective field theory approach, where the degrees of freedom appearing in the action are the SU(2) and SU(3) gauge fields, the weakly interacting Higgs doub

Ties Behnke, Petra Hüntemeyer, Alexander Oh, Johannes Steuerer

The charge collection properties of CVD diamond have been investigated with ionising radiation. In this study two CVD diamond samples, prepared with electrical contacts have been used as solid state ionisation chambers. The diamonds have been studied with beta particles and 10 keV photons, providing a homogeneous ionisation density and with protons and alpha

A. N. Tahvildar-Zadeh, M. H. Hettler, M. Jarrell

Employing a quantum Monte Carlo simulation we find a pairing instability in the normal state of the infinite dimensional periodic Anderson model. Superconductivity arises from a normal state in which the screening is protracted and which is clearly not a Fermi liquid. The phase diagram is reentrant reflecting competition between superconductivity and Fermi l

S. Kleefisch, L. Alff, U. Schoop, A. Marx

We have studied the electric transport properties of symmetrical [001] tilt NdCeCuO bicrystal grain boundary Josephson junctions (GBJs) fabricated on SrTiO bicrystal substrates with misorientation angles of 24 and 36.8 degree. The superconducting properties of the NdCeCuO-GBJs are similar to those of GBJs fabricated from the hole doped high temperature super

B. Derrida, S. Goldstein, J. L. Lebowitz, E. R. Speer

We investigate properties of non-translation-invariant measures, describing particle systems on $\bbz$, which are asymptotic to different translation invariant measures on the left and on the right. Often the structure of the transition region can only be observed from a point of view which is random---in particular, configuration dependent. Two such measure

Y. Q. Li, Michael Ma, D. N. Shi, F. C. Zhang

The isotropic limit of spin systems with orbital degeneracy is shown to have global SU(4) symmetry. On many 2D lattices, the ground state does not posses long range order, which may explain the observed spin liquid properties of $LiNiO_2$. In the SU(4) Neel ordered state, spin-spin correlations can be antiferromagneitc between two neighboring sites with para

Daniel Kandel

A model of submonolayer thin film growth is studied, where the attachment of atoms to island edges is hindered by an energy barrier. A novel behavior of the density of islands, N_s, is predicted as a function of flux F and temperature T. For example, N_s scales as F^X with X=2i^*/(i^*+3), where i^* is the critical island size, in contrast with the standard r

David H. Cobden, Marc Bockrath, Paul L. McEuen, Andrew G. Rinzler

The level spectrum of a single-walled carbon nanotube rope, studied by transport spectroscopy, shows Zeeman splitting in a magnetic field parallel to the tube axis. The pattern of splittings implies that the spin of the ground state alternates by 1/2 as consecutive electrons are added. Other aspects of the Coulomb blockade characteristics, including the curr

J. V. Alvarez, J. Gonzalez, F. Guinea, M. A. H. Vozmediano

The renormalization group approach to correlated fermions is used to determine the phase diagram of the oxide cuprates modeled by the t-t&#39; Hubbard model at the Van Hove filling. Spin-dependent interactions give rise to instabilities corresponding to ferromagnetic, antiferromagnetic and d-wave superconducting phases. Antiferromagnetism and d-wave supercon

Navot Israeli, Daniel Kandel

The flattening of a crystal cone below its roughening transition is studied by means of a step flow model. Numerical and analytical analyses show that the height profile, h(r,t), obeys the scaling scenario dh/dr = F(r t^{-1/4}). The scaling function is flat at radii r<R(t) \sim t^{1/4}. We find a one parameter family of solutions for the scaling function, an

Daniel Loss, B. Normand

Motivated by recent experiments on low-dimensional quantum magnets in applied magnetic fields, we present a theoretical analysis of their properties based on the nonlinear sigma model. The spin stiffness and a 1/N expansion are used to map the regimes of spin-gap behavior, predominantly linear magnetization, and spin saturation. A two-parameter renormalizati

Daniel Kandel

The scaling properties of the cluster size distribution of a system of diffusing clusters is studied in terms of a simple kinetic mean field model. It is shown that a one parameter family of mathematically valid scaling solutions exists. Despite this, the kinetics reaches a unique scaling solution independent of initial conditions. This selected scaling solu

Wei Chen, Kazuo Hida

The one dimensional S=1/2 Heisenberg model with dimerization and quadrumerization is studied by means of the numerical exact diagonalization of finite size systems. Using the phenomenological renormalization group and finite size scaling law, the ground state phase diagram is obtained in the isotropic case. It exhibits a variety of the ground states which co

H. J. M. van Bemmel, W. van Saarloos, D. F. B. ten Haaf

The effectiveness of the recently developed Fixed-Node Quantum Monte Carlo method for lattice fermions, developed by van Leeuwen and co-workers, is tested by applying it to the 1D Kondo lattice, an example of a one-dimensional model with a sign problem. The principles of this method and its implementation for the Kondo Lattice Model are discussed in detail.

Kyungsik Kim, J. S. Choi, Y. S. Kong

The multifractal behavior of the normalized first passage time is investigated on the two dimensional Sierpinski gasket with both absorbing and reflecting barriers. The normalized first passage time for Sinai model and the logistic model to arrive at the absorbing barrier after starting from an arbitrary site, especially obtained by the calculation via the M

Asantha R. Cooray, John E. Carlstrom, Marshall Joy, Laura Grego

We review recent results of Sunyaev-Zel&#39;dovich effect (SZE) observations toward galaxy clusters. Using cm-wave receivers mounted on the OVRO and BIMA mm-wave arrays we have obtained high signal to noise images of the effect for more than 20 clusters. We present current estimates of the Hubble constant and cosmological parameters and discuss the potential

Katherine Freese, Eleonora Krasteva

Catalysis of nucleon decay in white dwarfs is used to constrain the abundance of magnetic monopoles arising from Grand Unified Theories. Recent discoveries of the dimmest white dwarf ever observed, WD 1136-286 with $L = 10^{-4.94} L_{\odot}$, place limits on the monopole flux. An abundance of monopoles greater than the new bound would heat this star to a lum

W. Van Dyke Dixon, Mark Hurwitz

The UV-bright star Barnard 29 in the globular cluster M13 was observed for 5300 seconds with the Berkeley spectrometer on the ORFEUS-SPAS II Mission in 1996 November-December. The resulting spectrum extends from the interstellar cutoff at 912 A to ~ 1200 A at a resolution of ~ 0.33 A. It shows numerous absorption features, both photospheric and interstellar,

Mark Wardle, Farhad Yusef-Zadeh, T. R. Geballe

OH(1720 MHz) masers unaccompanied by 1665/7 MHz line masers have recently been proposed as indicators of the interaction of supernova remnants (SNRs) and molecular clouds. We present a model for the masing region in which water produced in a C-type shock wave driven into the molecular cloud is dissociated as a result of the X-ray flux from the SNR. We note t

Debades Bandyopadhyay, Somenath Chakrabarty, Prantick Dey, Subrata Pal

The neutrino emissivities resulting from direct URCA processes in neutron stars are calculated in a relativistic Dirac-Hartree approach in presence of a magnetic field. In a quark or a hyperon matter environment, the emissivity due to nucleon direct URCA processes is suppressed relative to that from pure nuclear matter. In all the cases studied, the magnetic

Ofer Lahav

We review cosmological inference from galaxy surveys at low and high redshifts, with emphasis on new Southern sky surveys. We focus on several issues: (i) The importance of understanding selection effects in catalogues and matching Northern and Southern surveys; (ii) The 2dF galaxy redshift survey of 250,000 galaxies (iii) The proposed 6dF redshift and pecul

J. R. Anglin, W. H. Zurek

A second order phase transition induced by a rapid quench can lock out topological defects with densities far exceeding their equilibrium expectation values. We use quantum kinetic theory to show that this mechanism, originally postulated in the cosmological context, and analysed so far only on the mean field classical level, should allow spontaneous generat

William T. Reach, Jeonghee Rho

Using the IRAM 30-m telescope, we observed the supernova remnant 3C 391 (G31.9+0.0) and its surroundings in the CO(2-1), HCO+(1-0), CS(2-1), CS(3-2), and CS(5-4) lines. The ambient molecular gas at the distance (9 kpc) of the remnant comprises a giant molecular cloud whose edge is closely parallel to a ridge of bright non-thermal radio continuum, which evide

Marc Postman, Tod R. Lauer, Istvan Szapudi, William Oegerle

We present constraints on the evolution of large-scale structure from a catalog of 710,000 galaxies with I_AB <= 24 derived from a KPNO 4m CCD imaging survey of a contiguous 4 deg x 4 deg region. The advantage of using large contiguous surveys for measuring clustering properties on even modest angular scales is substantial: the effects of cosmic scatter are

Cristopher Moore, Martin Nilsson

We exhibit some simple gadgets useful in designing shallow parallel circuits for quantum algorithms. We prove that any quantum circuit composed entirely of controlled-not gates or of diagonal gates can be parallelized to logarithmic depth, while circuits composed of both cannot. Finally, while we note the Quantum Fourier Transform can be parallelized to line

Maurice H. P. M. van Putten

Magnetohydrodynamics in divergence form describes a hyperbolic system of covariant and constraint-free equations. It comprises a linear combination of an algebraic constraint and Faraday&#39;s equations. Here, we study the problem of well-posedness, and identify a preferred linear combination in this divergence formulation. The limit of weak magnetic fields

Nick Evans

The curves that describe the M-theoretic extension of type IIA string configurations with non-supersymmetric field theories on their surface exhibit a duality map. The map suggests a continued link between a SU(N) gauge theory with F flavours and an SU(F-N) gauge theory with F flavours (the duality of supersymmetric QCD) even when the gaugino mass is taken t

J. Main, K. Weibert, V. A. Mandelshtam, G. Wunner

Semiclassical spectra weighted with products of diagonal matrix elements of operators A_{alpha}, i.e., g_{alpha alpha&#39;}(E) = sum_n <n|A_{alpha}|n><n|A_{alpha&#39;}|n>/(E-E_n) are obtained by harmonic inversion of a cross-correlation signal constructed of classical periodic orbits. The method provides highly resolved semiclassical spectra even in situatio

Michael Birkel, Subir Sarkar

The expected proton and neutrino fluxes from decays of massive metastable relic particles is calculated using the HERWIG QCD event generator. The predicted proton spectrum can account for the observed flux of extremely high energy cosmic rays beyond the Greisen-Zatsepin-Kuzmin cutoff, for a decaying particle mass of O(10^{12}) GeV. The lifetime required is o

B. Pire, J. Soffer, O. Teryaev

Off-Forward Parton Distributions (OFPD&#39;s) are new hadronic objects which may be measured in various exclusive reactions. We derive non-trivial positivity constraints for them that should allow to get extra restrictions for model inputs.

H. W. Lee, Y. S. Myung

We study the 5D black holes in the type IIB superstring theory compactified on $S^1 \times T^4$. Far from horizon, we have flat space-time. Near horizon, we have $AdS_3(BTZ black hole) \times S^3 \times T^4$. We calculate the greybody factor of a minimally coupled scalar by replacing the original geometry($M_5 \times S^1 \times T^4$) by $AdS_3 \times S^3 \ti

F. Luczak, F. Brosens, J. T. Devreese, L. F. Lemmens

In this paper we show how the transposition, the basic operation of the permutation group, can be taken into account in a diffusion process of identical particles. Whereas in an earlier approach the method was applied to systems in which the potential is invariant under interchanging the Cartesian components of the particle coordinates, this condition on the

Geon Hyoung Lee, Tack Hwi Lee, Jae Hyung Yee

We have extended the perturbative expansion method around the Gaussian effective action to the fermionic field theory, by taking the 2-dimensional Gross-Neveu model as an example. We have computed both the zero temperature and the finite temperature effective potentials of the Gross-Neveu model up to the first perturbative correction terms, and have found th

Changhyun Ahn, Kyungho Oh, Radu Tatar

We analyze the relation between the large N limit of 6 dimensional superconformal field theories with eight supercharges and M theory on orbifolds of AdS_7xS^4. We use the known spectrum of Kaluza-Klein harmonics of supergravity on AdS_7xS^4 and we take their orbifold projection to get information about the chiral primary operators of 6 dimensional SCFT whic

K. Fonseca Romero, M. C. Nemes, J. G. Peixoto de Faria, A. N. Salgueiro

We show that two-atom correlation measurements of the type involved in a recent experimental study of the evolution of a mesoscopic superposition state prepared in a definite mode of a high-Q cavity can be used to determine the eigenvalues of the reduced density matrix of the field, provided the assumed dynamical conditions are actually fulfilled to experime

J. Sekutowicz, M. Ferrario, C. Tang

We discuss the new layout of a cavity chain (superstructure) allowing, we hope, significant cost reduction of the RF system of both linacs of the TESLA linear collider. The proposed scheme increases the fill factor and thus makes an effective gradient of an accelerator higher. We present mainly computations we have performed up to now and which encouraged us

John David Crawford, Anandhan Jayaraman

The nonlinear evolution of a unstable electrostatic wave is considered for a multi-species Vlasov plasma. From the singularity structure of the associated amplitude expansions, the asymptotic features of the electric field and distribution functions are determined in the limit of weak instability, i.e. $γ\to 0^+$ where $γ$ is the linear growth rate. The asym

Michael C. Birse

The renormalisation of NN scattering in theories with zero-range interactions is examined using a cut-off regularisation where the cut-off is taken to infinity, dimensional regularisation (DR) with minimal subtraction, and DR with power-divergence subtraction. In the infinite cut-off limit power counting breaks down: terms of different orders in the potentia

Zhen Mei, Chih-Wen Shih

We study impact of a forced symmetry-breaking in boundary conditions on the bifurcation scenario of a semilinear elliptic partial differential equation. We show that for the square domain the orthogonality of eigenfunctions of the Laplacian may compensate partially the loss of symmetries in the boundary conditions and allows some solution to have more symmet

Feng-Yu Wang

Let $M$ be a connected, noncompact, complete Riemannian manifold, consider the operator $L=\DD +\nn V$ for some $V\in C^2(M)$ with $\exp[V]$ integrable w.r.t. the Riemannian volume element. This paper studies the existence of the spectral gap of $L$. As a consequence of the main result, let $\rr$ be the distance function from a point $o$, then the spectral g

Mu-Fa Chen, Feng-Yu Wang

In this paper, some new forms of the Cheeger&#39;s inequalities are established for general (maybe unbounded) symmetric forms, the resulting estimates improve and extend the ones obtained by Lawler and Sokal (1988) for bounded jump processes. Furthermore, some existence criteria for spectral gap of general symmetric forms or general reversible Markov process

S. M. Gusein-Zade, I. Luengo, A. Melle-Hernandez

A meromorphic function on a compact complex analytic manifold defines a $\bc\infty$ locally trivial fibration over the complement of a finite set in the projective line $\bc\bp^1$. We describe zeta-functions of local monodromies of this fibration around atypical values. Some applications to polynomial functions on $\bc^n$ are described.