August 2001 arXiv papers — page 23

Zumin Luo, Jonathan L. Rosner

Analysis of the present data on the semileptonic process $B \to π\ell ν$ indicates that they have not yet reached the precision to provide adequate information on the $B \to π$ form factor $F_+(q^2)$, which for $q^2 = m_π^2$ is known to be related to the factorized color-favored (``$T$'', or ``tree'') contribution to $B^0 \to π^+ π^-$. It is

R. L. Jaffe

The nucleon's axial vector charge, g_A, becomes delocalized in the chiral limit. When m_\pi = 0, and SU(2)_L x SU(2)_R is exact, 1/3 of the nucleon's axial charge is to be found at infinite distance from the nucleon. For finite m_\pi this result is approached smoothly as m_\pi -> 0. We illustrate this effect by considering the lepton-proton spin-spin interac

Georgios Kofinas

A general analysis of the induced brane dynamics is performed when the intrinsic curvature term is included in the action. Such a term is known to cause dramatic changes and is generically induced by quantum corrections coming from the bulk gravity and its coupling with matter living on the brane. The induced brane dynamics is shown to be the usual Einstein

W. Detmold, W. Melnitchouk, A. W. Thomas

We extract the x dependence of the nonsinglet u-d distribution function in the nucleon from the lowest few moments calculated on the lattice, using an extrapolation formula which ensures the correct behavior in the chiral and heavy quark limits. We discuss the implications for the quark mass dependence of meson masses lying on the J(PC)=1(--) Regge trajector

A. V. Bobyl, D. V. Shantsev, Y. M. Galperin, T. H. Johansen

The dynamics of magnetic flux distributions across a YBaCuO strip carrying transport current is measured using magneto-optical imaging at 20 K. The current is applied in pulses of 40-5000 ms duration and magnitude close to the critical one, 5.5 A. During the pulse some extra flux usually penetrates the strip, so the local field increases in magnitude. When t

Jonathan Bagger, Ferruccio Feruglio, Fabio Zwirner

We study spontaneous supersymmetry breaking induced by brane-localized dynamics in five-dimensional supergravity compactified on S^1/Z_2. We consider a model with gravity in the bulk and matter localized on tensionless branes at the orbifold fixed points. We assume that the brane dynamics give rise to effective brane superpotentials that trigger the supersym

T. Asaka, W. Buchmüller, L. Covi

We study the breaking of a supersymmetric SO(10) GUT in 6 dimensions by orbifold compactification. In 4 dimensions we obtain a N=1 supersymmetric theory with the standard model gauge group enlarged by an additional U(1) symmetry. The 4-dimensional gauge symmetry is obtained as intersection of the Pati-Salam and the Georgi-Glashow subgroups of SO(10), which a

M. Jorgensen, R. Ouyed, M. Christensen

We solve, and provide analytical expressions, for current-free magnetic configurations in the context of initial setups of 3-dimensional simulations of astrophysical jets involving an accretion disk corona in hydrostatic balance around a central object. These configurations which thread through the accretion disk and its corona preserve the initial hydrostat

Seppo Laine, Isaac Shlosman, Johan H. Knapen, Reynier F. Peletier

We analyze the observed properties of nested and single stellar bar systems in disk galaxies. The 112 galaxies in our sample comprise the largest matched Seyfert vs. non-Seyfert sample of nearby galaxies with complete near-infrared or optical imaging sensitive to lengthscales ranging from tens of pc to tens of kpc. We find that a significant fraction of the

Fabio Gavarini

The "quantum duality principle" states that a quantisation of a Lie bialgebra provides also a quantisation of the dual formal Poisson group and, conversely, a quantisation of a formal Poisson group yields a quantisation of the dual Lie bialgebra as well. We extend this to a much more general result: namely, given any principal ideal domain R, for eac

A. Rostovtsev

A Pomeron phenomenon remains a mystery. A short review of the experimental situation in diffractive physics and an account of some spectacular manifestations of the Pomeron are given.

L. Bertini, A. De Sole, D. Gabrielli, G. Jona-Lasinio

We formulate a dynamical fluctuation theory for stationary non equilibrium states (SNS) which is tested explicitly in stochastic models of interacting particles. In our theory a crucial role is played by the time reversed dynamics. Within this theory we derive the following results: the modification of the Onsager-Machlup theory in the SNS; a general Hamilto

Andrzej A. Zdziarski, Karen M. Leighly, Masaru Matsuoka, Massimo Cappi

We present a detailed analysis of a long, 100 ksec, observation of NGC 4151 by ASCA, contemporaneous with an observation by the CGRO/OSSE. We fit the data with physical models including an Fe K line and Compton reflection both relativistically broadened and coupled according to theoretical results. The model also includes a narrow Fe K component, which is em

Jun Kikuchi, Takao Matsuoka, Kiyoichiro Motoya, Touru Yamauchi

We report the observation of nuclear quadrupole resonance (NQR) of Cu from the sites near the doping center in the spin-Peierls system CuGe$_{1-x}$Si$_{x}$O$_3$. The signal appears as the satellites in the Cu NQR spectrum, and has a suppressed nuclear spin-lattice relaxation rate indicative of a singlet correlation rather than an enhanced magnetic correlatio

Yevgeny Kats, David A. Kessler, Yitzhak Rabin

We present a new algorithm for generating the equilibrium configurations of fluctuating continuous elastic filaments, based on a combination of statistical mechanics and differential geometry. We use this to calculate the distribution function of the end-to-end distance of filaments with nonvanishing spontaneous curvature and show that for small twist and la

R. N. Lee, A. I. Milstein, V. G. Serbo

We analyze the structure of the Coulomb and unitarity corrections to the single pair production as well as the cross section for the multiple pair production. In the external field approximation we consider the probability of $e^+e^-$ pair production at fixed impact parameter $ρ$ between colliding ultra-relativistic heavy nuclei. We obtain the analytical res

S. Burger, F. S. Cataliotti, C. Fort, P. Maddaloni

We study the phase transition of a gas of Rb atoms to quantum degeneracy in the combined potential of a harmonically confining magnetic trap and the periodic potential of an optical lattice. For high optical lattice potentials we observe a significant change in the temperature dependency of the population of the ground state of the system. The experimental r

N. Haba, K. Hamaguchi, Tomoharu Suzuki

It is well known that the Zee model induces small neutrino masses by radiative corrections, where the bi-maximal flavor mixing is possible. We analyze the cosmological condition in order for the baryon asymmetry generated in the early universe not to be washed out in the Zee model. Since the lepton number is violated explicitly in the Zee model, the baryon a

Ingve Simonsen

We consider the Nordic electricity spot market from mid 1992 to the end of year 2000. This market is found to be well approximated by an anti-persistent self-affine (mean-reverting) walk. It is characterized by a Hurst exponent of $H\simeq 0.41$ over three orders of magnitude in time ranging from days to years. We argue that in order to see such a good scali

S. Okamoto, S. Ishihara, S. Maekawa

We present a theory of the Raman scattering from the orbital wave excitations in manganese oxides. Two excitation processes of the Raman scattering are proposed. The Raman scattering cross section is formulated by using the pseudospin operator for orbital degree of freedom in a Mn ion. The Raman spectra from the orbital wave excitations are calculated and th

K. -I. Goh, B. Kahng, D. Kim

We study the dynamics of the Internet topology based on the empirical data on the level of the autonomous systems. It is found that the fluctuations occurring in the stochastic process of connecting and disconnecting edges are important features of the Internet dynamics. The network's overall growth can be described approximately by a single characterist

Alex C. Kalloniatis, Sergei N. Nedelko

A qualitative mechanism for the emergence of domain structured background gluon fields due to singularities in gauge field configurations is considered, and a model displaying a type of mean field approximation to the QCD partition function based on this mechanism is formulated. Estimation of the vacuum parameters (gluon condensate, topological susceptibilit

E787 Collaboration

We have performed a search for the angular-momentum forbidden decay K+ -> pi+ gamma with the E787 detector at BNL. No events were observed in the pi+ kinematic region around 227 MeV/c. An upper limit on the branching ratio for the decay is determined to be 3.6 x 10^{-7} at 90% confidence level.

Yongge Ma

A 4-dimensional Lorentzian static space-time is equivalent to 3-dimensional Euclidean gravity coupled to a massless Klein-field. By canonically quantizing the coupling model in the framework of loop quantum gravity, we obtain a quantum theory which actually describes quantized static space-times. The Kinematical Hilbert space is the product of the Hilbert sp

G. Gilbert, M. Hamrick, F. J. Thayer

In order to be practically useful, quantum cryptography must not only provide a guarantee of secrecy, but it must provide this guarantee with a useful, sufficiently large throughput value. The standard result of generalized privacy amplification yields an upper bound only on the average value of the mutual information available to an eavesdropper. Unfortunat

Marcella Iannuzzi, Michele Parrinello

An efficient method for calculating the electronic structure in large systems with a fully converged BZ sampling is presented. The method is based on a k.p-like approximation developed in the framework of the density functional perturbation theory. The reliability and efficiency of the method are demostrated in test calculations on Ar and Si supercells.

J. Gegelia, G. Japaridze

Cutoff regularized subleading order ${}^1S_0$ NN potential of effective field theory (EFT) is iterated using Lippmann-Schwinger equation. It is shown that the scattering amplitudes calculated in cutoff and subtractively renormalized EFT are equal up to the accuracy of performed calculations. Non-perturbative renormalization, where part of divergences are abs

Tetsufumi Hirano

The pseudorapidity dependence of elliptic flow in Au+Au collisions at 130 $A$ GeV is studied within a full three-dimensional hydrodynamic model in the light-cone coordinate. First, we prepare two initial conditions in the hydrodynamic model for analyzing elliptic flow. Both initial conditions lead to reasonable agreement with single particle spectra in centr

Paul Federbush

We let Psi_0 be a wave function for the Quantum Heisenberg ferromagnet sharp i sigma_zi and Psi_mu = exp(-mu*H)Psi_0. We study expectations similar to the form <Psi_mu,(sigma_zi)Psi_mu>/<Psi_mu,Psi_mu> for which we present a formal polymer expansion, whose convergence we prove for sufficiently small mu. The approach of the paper is to relate the wavefunction

A. Libgober

We study tori attached to the fundamental groups of plane curves with arbitrary singularities. These tori provide complete information about homology of finite abelian covers of the plane branched along the curve. We calculate these tori in terms of certain linear systems determined by the singularities of the curve. In the case of the complements to a union

Malgorzata Rowicka

All unitary representations of the quantum ``az+b&#39;&#39; group are found. It turns out that this quantum group is self dual i.e. all unitary representations are &#39;numbered&#39; by elements of the same group. Moreover, the formula for all unitary representations involving the quantum exponential function is proven.

A. Libgober

We decribe upper bounds for the orders of the eigenvalues of the monodromy of Milnor fibers of arrangements given in terms of combinatorics.

A. Libgober

Multivariable Alexander invariants of algebraic links calculated in terms of algebro-geometric invariants (polytopes and ideals of quasiadjunction). The relations with log-canonical divisors, the multiplier ideals and a semicontinuity property of polytopes of quasiadjunction is discussed.

A. Tsemo

In this paper we propose a higher non abelian cohomology theory without using the notion of n-category. We use this to study compositions series of affine manifolds and cohomology of manifolds.

Markus Keel, Hart Smith, Christopher D. Sogge

We prove almost global existence for semilinear wave equations outside of nontrapping obstacles. We use the vector field method, but only use the generators of translations and Euclidean rotations. Our method exploits 1/r decay of wave equations, as opposed to the much harder to prove 1/t decay.

Hugh R. Morton, Sascha G. Lukac

The main goal is to find the Homfly polynomial of a link formed by decorating each component of the Hopf link with the closure of a directly oriented tangle. Such decorations are spanned in the Homfly skein of the annulus by elements Q_λ, depending on partitions λ. We show how to find the 2-variable Homfly invariant <λ,μ> of the Hopf link arising from decora

P. Svetlov

In this note we prove that any closed graph manifold admitting a metric of non-positive sectional curvature (NPC-metric) has a finite cover, which is fibered over the circle. An explicit criterion to have a finite cover, which is fibered over the circle, is presented for the graph manifolds of certain class.

Zhiqin Lu

In this paper, we study the limiting properties of the $K$ energy for smooth hypersurfaces in the projective spaces. Our result generalizes the result of Ding-Tian (W. Ding and G. Tian. Kähler-Einstein metrics and the generalized Futaki invariant. {\em Invent Math}, 110:315-335, 1992.) in the case of hypersurfaces. In particular, we allow the center fiber of

Devin Greene, Stefan Richter, Carl Sundberg

We establish some multivariate generalizations of the Beurling-Lax-Halmos theorem.

W. B. R. Lickorish

Examples are given to show that some compact contractible 4-manifolds can be knotted in the 4-sphere. It is then proved that any finitely presented perfect group with a balanced presentation is a knot group for an embedding of some contractible 4-manifold in the 4-sphere.

Miriam Ruth Kantorovitz

For a commutative ring $R$ of characteristic $p$, let $ϕ: R \to R$ be the Frobenius homomorphism and let $^{ϕ^r}R$ denote the $R$-module structure on $R$ defined via the $r$-th power of the Frobenius. We show that the Tor functor against the Frobenius module, $\Tor^R_*(-, {^{ϕ^r}}R)$, is rigid for a certain class of depth zero rings which includes rings that

Uwe Grimm

Improved upper and lower bounds on the number of square-free ternary words are obtained. The upper bound is based on the enumeration of square-free ternary words up to length 110. The lower bound is derived by constructing generalised Brinkhuis triples. The problem of finding such triples can essentially be reduced to a combinatorial problem, which can effic

Toufik Mansour, Alek Vainshtein

We study the generating function for the number of permutations on n letters containing exactly $r\gs0$ occurences of 132. It is shown that finding this function for a given r amounts to a routine check of all permutations in $S_{2r}$.

D. G. C. McKeon, T. N. Sherry

In this paper, we survey the nature of spinors and supersymmetry (SUSY) in various types of spaces. We treat two distinct types of spaces: flat spaces and spaces of constant (non-zero) curvature. The flat spaces we consider are either three or four dimensional of signatures 3 + 1, 4 + 0, 2 + 2 and 3 + 0. In each of these cases, SUSY generators anti-commute t

Paul H. Frampton

In this talk I review some aspects of the idea that there is an infra-red conformal fixed-point at the TeV scale. In particular, it is shown how gauge coupling unification can be achieved by TeV unification in a semi-simple gauge group.

Kazuhiro Hikami

We study a geometry of the partition function which is defined in terms of a solution of the five-term relation. It is shown that the 3-dimensional hyperbolic structure or Euclidean AdS_3 naturally arises in the classical limit of this invariant. We discuss that the oriented ideal tetrahedron can be assigned to the partition function of string.

Elias Gravanis, Nick E. Mavromatos

Critical String Theory is by definition an $S$-matrix theory. In this sense, (quantum) gravity situations where a unitary $S$-matrix may not be a well-defined concept, as a consequence of the existence of macroscopic (global) or microscopic (local) gravitational fluctuations with event horizons, present a challenge to string theory. In this article, we take

H. K. Jassal, A. Mukherjee

The motion of a string in curved spacetime is discussed in detail. The basic formalism for string motion in Minkowski spacetime and in curved spacetime is presented. The description applies to cosmic strings as well as to fundamental strings. Major ansatze for solving the string equations of motion are reviewed. In particular, the ``null string ansatz&#39;&#

S. R. Beane

We investigate implications of quark-hadron duality for hybrid mesons in the large-Nc limit. A simple formalism is developed which implements duality for QCD two-point functions of currents of quark bilinears, with any number of gluons. We argue that the large-Nc meson masses share a common parameter, which is related to the QCD string tension. This paramete

S. Case, S. Koutsoliotas, M. L. Novak

We present sensitivities for the MiniBooNE experiment to a rare exotic pion decay producing a massive particle, Q^0. This type of decay represents one possible explanation for the timing anomaly reported by the KARMEN collaboration. MiniBooNE will be able to explore an area of the KARMEN signal that has not yet been investigated.

Mary K. Gaillard

The weakly coupled vacuum of $E_8\otimes E_8$ heterotic string theory remains an attractive scenario for particle physics. The particle spectrum and the issue of dilaton stabilization are reviewed. A specific model for hidden sector condensation and supersymmetry breaking, that respects known constraints from string theory, is described, and its phenomenolog

Josep F. Oliver, Arcadi Santamaria

We show that in theories that reduce, at the Fermi scale, to an extension of the standard model with two doublets, there can be additional dimension five operators giving rise to neutrino masses. In particular there exists a singlet operator which can not generate neutrino masses at tree level but generates them through operator mixing. Under the assumption

Anjan S. Joshipura, Subhendra Mohanty

Neutrinos can scatter electrons in water detectors through their magnetic moments and charge radii in addition to the charged and neutral currents channels. The recent solar neutrino charged current event rates announced by SNO with the earlier solar and atmospheric neutrino observations from Super-Kamiokande allows us to put upper bounds of $μ<10^{-9} μ_B$

K. G. Chetyrkin, M. Steinhauser

The non-diagonal correlators of vector and scalar currents are considered at three-loop order in QCD. The full mass dependence is computed in the case where one of the quarks is massless and the other one carries mass $M$. We exploit the decoupling relations between the full theory and the heavy quark effective theory (HQET) in order to obtain the logarithmi

A. V. Butkevich, R. P. Kokoulin, G. V. Matushko, S. P. Mikheyev

We describe two independent methods to calculate the angular distribution of muons after traversing a thick scatterer due to multiple Coulomb scattering. Both methods take into account the nuclear size effect. We demonstrate a necessity to account for the nucleus extension as well as incoherent scattering on atomic electrons to describe the muon scattering a

Shuntaro Mizuno, Kei-ichi Maeda

We reanalyze a new quintessence scenario in a brane world model, assuming that a quintessence scalar field is confined in our 3-dimensional brane world. We study three typical quintessence models : (1) an inverse-power-law potential, (2) an exponential potential, and (3) kinetic-term quintessence ($k$-essence) model. With an inverse power law potential model

H. Kawamura, Y. Kiyo, J. Kodaira, K. Morii

We discuss W gamma production in polarized p p collisions at RHIC energy. We point out that the RHIC collider has two advantages over other hadron colliders to measure the characteristic feature of W gamma production: (1) the RHIC energy is not so high and (2) the polarized beams are available. We calculate the tree level cross section for W gamma production

ALEPH Collaboration

A measurement of the inclusive semileptonic branching ratios of b hadrons produced in Z decay is presented, using four million hadronic events collected by the ALEPH detector from 1991 to 1995. Electrons and muons are selected opposite to b-tagged hemispheres. Two different methods are explored to distinguish the contributions from direct $\bl$ and cascade $

K R P Sjodin, J A Vickers

The thin string limit of Cosmic Strings is investigated using a description in terms of Colombeau&#39;s theory of nonlinear generalised functions. It is shown that in this description the energy-momentum tensor has a well defined thin string limit. Furthermore the deficit angle of the conical spacetime that one obtains in the limit may be given in terms of t

Filipe C Mena, Brien C Nolan

The issue of the local visibility of the shell-focussing singularity in marginally bound spherical dust collapse is considered from the point of view of the existence of future-directed null geodesics with angular momentum which emanate from the singularity. The initial data (i.e. the initial density profile) at the onset of collapse is taken to be of class

Sergey S. Kokarev

Variational principle for a solid in classical mechanics is formulated in terms of a thin elastic 4D bar strain in Minkowsky events space of special relativity. It is shown, that the sum of elastic 4-energies of weak twist and bending under some identifications takes the form of classical non-relativistic action for a solids dynamics. The necessary condition

Florian Siebel, Jose A. Font, Philippos Papadopoulos

We study the interaction of massless scalar fields with self-gravitating neutron stars by means of fully dynamic numerical simulations of the Einstein-Klein-Gordon perfect fluid system. Our investigation is restricted to spherical symmetry and the neutron stars are approximated by relativistic polytropes. Studying the nonlinear dynamics of isolated neutron s

Geoffery Ericksson, Susan M. Scott

We investigate barotropic perfect fluid cosmologies which admit an isotropic singularity. From the General Vorticity Result of Scott, it is known that these cosmologies must be irrotational. In this paper we prove, using two different methods, that if we make the additional assumption that the perfect fluid is shear-free, then the fluid flow must be geodesic

Sibsankar Haldar, Paul Vitanyi

Shared registers are basic objects used as communication mediums in asynchronous concurrent computation. A concurrent timestamp system is a higher typed communication object, and has been shown to be a powerful tool to solve many concurrency control problems. It has turned out to be possible to construct such higher typed objects from primitive lower typed o

D. V. Shantsev, Y. M. Galperin, T. H. Johansen

The flux creep problem for a superconductor slab placed in a constant or time-dependent magnetic field is considered. Logarithmic dependence of the activation energy on the current density is assumed, U=U0 ln(J/Jc), with a field dependent Jc. The density B of the magnetic flux penetrating into the superconductor, is shown to obey a scaling law, i.e., the pro

Sebastiao Correia, Janos Polonyi, Jean Richert

A non-perturbative scheme, based on the functional generalization of the Callan-Symanzik equation is developed to treat the Coulomb interaction in an electron gas. The one-particle irreducible vertex functions are shown to satisfy an evolution equation whose initial condition is given by means of the classical action and the final point corresponds to the ph

S. Giovanazzi, D. O&#39;Dell, G. Kurizki

We show that the dipole-dipole interatomic forces induced by a single off-resonant running laser beam can lead to a self-bound pencil-shaped Bose condensate, even if the laser beam is a plane-wave. For an appropriate laser intensity the ground state has a quasi-one dimensional density modulation --- a Bose &#34;supersolid&#34;.

D. V. Efremov, L. Viverit

We predict a p-wave Cooper pairing of the spin-polarized fermions in a binary fermion-boson mixture due to the exchange of density fluctuations of the bosonic medium. We then examine the dependence of the Cooper paring temperature on the parameters of the system. We finally estimate the effect of combining the boson-induced interaction with other pairing mec

A. Vazquez, A. Flammini, A. Maritan, A. Vespignani

We introduce a graph generating model aimed at representing the evolution of protein interaction networks. The model is based on the hypotesis of evolution by duplications and divergence of the genes which produce proteins. The obtained graphs shows multifractal properties recovering the absence of a characteristic connectivity as found in real data of prote

Iacopo Carusotto, Yvan Castin

We present a new exact method to numerically compute the thermodynamical properties of an interacting Bose gas in the canonical ensemble. As in our previous paper (Phys. Rev. A, 63 023606 (2001)), we write the density operator $ρ$ as an average of Hartree dyadics $\ketbra{N:ϕ_1}{N:ϕ_2}$ and we find stochastic evolution equations for the wave functions $ϕ_{1,

S. Caprara, C. Di Castro, S. Fratini, M. Grilli

We propose an interpretation for the hump observed in the optical conductivity at or below a few hundreds of cm$^{-1}$, in overdoped cuprates like the electron-doped Nd_{2-x}Ce_xCuO_{4-y} at x\gtrsim 0.15 and the hole-doped Bi_2Sr_2CuO_6 and La_{2-x}Sr_xCuO_4. This interpretation is based on the direct excitation of charge collective modes, which become near

Michele Fabrizio, Luca Dell&#39;Anna, Claudio Castellani

We study the quasiparticle transport coefficients in disordered d-wave superconductors. We find that spin and charge excitations are generally localized unless magnetic impurities are present. If the system is close to a nesting point in the impurity-scattering unitary limit, the tendency towards localization is reduced while the quasiparticle density of sta

Bernd A. Berg, Alain Billoire, Wolfhard Janke

Recently, it has been conjectured that the statistics of extremes is of relevance for a large class of correlated system. For certain probability densities this predicts the characteristic large $x$ fall-off behavior $f(x)\sim\exp (-a e^x)$, $a>0$. Using a multicanonical Monte Carlo technique, we have calculated the Parisi overlap distribution $P(q)$ for the

Ramses van Zon, Jeremy Schofield

A recent mode coupling theory of higher-order correlation functions is tested on a simple hard-sphere fluid system at intermediate densities. Multi-point and multi-time correlation functions of the densities of conserved variables are calculated in the hydrodynamic limit and compared to results obtained from event-based molecular dynamics simulations. It is

Ramses van Zon, Jeremy Schofield

We present a theoretical framework for higher-order correlation functions involving multiple times and multiple points in a classical, many-body system. Such higher-order correlation functions have attracted much interest recently in the context of various forms of multi-dimensional spectroscopy, and have found an intriguing application as proposed measures

Kay-Yut Chen, Leslie R. Fine, Bernardo A. Huberman

We present a novel methodology for predicting future outcomes that uses small numbers of individuals participating in an imperfect information market. By determining their risk attitudes and performing a nonlinear aggregation of their predictions, we are able to assess the probability of the future outcome of an uncertain event and compare it to both the obj

G. Burbidge

A brief historical account of modern cosmology shows that the standard big bang (BB) model, believed by so many, does not have the strong observational foundations that are frequently claimed for it. The theory of the Quasi-Steady State Cosmology (QSSC) and explosive cosmogony is outlined. Comparisons are made between the two theories in explaining the obser

Charles G. Hoopes, Kenneth R. Sembach, J. Christopher Howk, William P. Blair

We report a detection of far ultraviolet absorption from the supernova remnant SNR 0057 - 7226 in the Small Magellanic Cloud (SMC). The absorption is seen in the Far Ultraviolet Spectroscopic Explorer (FUSE) spectrum of the LBV/WR star HD 5980. Absorption from O VI 1032 and C III 977 is seen at a velocity of +300 km/s with respect to the Galactic absorption

D. W. Savin, E. Behar, S. M. Kahn, G. Gwinner

We have measured the resonance strengths and energies for dielectronic recombination (DR) of Fe XX forming Fe XIX via N=2 --> N&#39;=2 (Delta_N=0) core excitations. We have also calculated the DR resonance strengths and energies using AUTOSTRUCTURE, HULLAC, MCDF, and R-matrix methods, four different state-of-the-art theoretical techniques. On average the the

K. R. Sembach, J. C. Howk, B. D. Savage, J. M. Shull

We present Far Ultraviolet Spectroscopic Explorer (FUSE) observations of the molecular, neutral atomic, weakly ionized, and highly ionized components of the interstellar and intergalactic material toward the quasar 3C 273. We identify Ly-beta absorption in 8 of the known intergalactic Ly-alpha absorbers along the sight line with rest-frame equivalent widths

R. J. Reynolds, N. C. Sterling, L. M. Haffner

The Wisconsin H-Alpha Mapper (WHAM) Northern Sky Survey has revealed a loop of H II reaching 1300 pc from the Galactic midplane above the Cas OB6 association in the Perseus sprial arm. This enormous feature surrounds and extends far above the &#34;W4 Chimney&#34; identified by Normandeau et al. and appears to be associated with the star formation activity ne

A. Panaitescu, P. Kumar

We determine the basic physical characteristics of eight Gamma-Ray Bursts -- 980519, 990123, 990510, 991028, 991216, 000301c, 000926 and 010222 -- by modelling the broadband emission of their afterglows. We find that the burst kinetic energies after the GRB phase are well clustered around a mean value of 3E50 ergs. In contrast, the energy release in gamma-ra

Smita Mathur

I review Chandra&#39;s achievements in the last two years in AGN research. I concentrate on some topics of my interest; some others are reviewed in an accompanying article by K. Nandra. I comment briefly on the need to allow for the discovery space to ensure rapid progress in the field.

Eduardo Gueron, Patricio S. Letelier

The exact solution to the Einstein equations that represents a static axially symmetric source deformed by an internal quadrupole is considered. By using the Poincare section method we numerically study the geodesic motion of test particles. For the prolate quadrupolar deformations we found chaotic motions contrary to the oblate case where only regular motio

J. A. Maruhn, I. N. Mishustin, L. M. Satarov

The long-range energy deposition by heavy-ion beams makes new types of shock wave experiments possible in the laboratory. We have investigated a situation that is of relevance to supernova dynamics in astrophysics, where a shock wave is irradiated by a flux of neutrinos depositing energy throughout the shock wave and surrounding matter, thus changing the beh

Thomas M. Brown, Allen V. Sweigart, Thierry Lanz, Wayne B. Landsman

We present a UV CMD spanning the hot horizontal branch (HB), blue straggler, and white dwarf populations of the globular cluster NGC 2808. These data were obtained with the Space Telescope Imaging Spectrograph (STIS). Although previous optical CMDs of NGC 2808 show a high temperature gap within the hot HB population, no such gap is evident in our UV CMD. Ins

Graham P. Smith, Tommaso Treu, Richard Ellis, Ian Smail

We present near-IR spectroscopy and HST imaging of EROJ164023, an Extremely Red Object (ERO) with R-K=5.9 at z=1.05. EROJ164023 is a disk galaxy, with an optical/IR spectral energy distribution which is strongly reddened by dust (L_FIR/L_B<~200; A_V~5). The narrow emission lines (~300km/s) and the high [NII]/Halpha line ratio indicate that this is a ``compos

Henry E. Kandrup, Ioannis V. Sideris, C. L. Bohn

This paper uses the assumptions of ergodicity and a microcanonical distribution to compute estimates of the largest Lyapunov exponents in lower-dimensional Hamiltonian systems. That the resulting estimates are in reasonable agreement with the actual values computed numerically corroborates the intuition that chaos in such systems can be understood as arising

A. T. Okazaki, I. Negueruela

When applied to Be/X-ray binaries, the viscous decretion disc model for Be stars naturally predicts the truncation of the circumstellar disc. The distance at which the circumstellar disc is truncated depends mainly on the orbital parameters and the viscosity. In systems with low eccentricity, the disc is expected to be truncated at the 3:1 resonance radius,

G. Rüdiger, D. A. Shalybkov

The linear marginal instability of an axisymmetric MHD Taylor-Couette flow of infinite vertical extension is considered. For flows with a resting outer cylinder there is a well-known characteristic Reynolds number even without magnetic field but for sufficiently weak magnetic fields there are solutions with smaller Reynolds numbers so that a characteristic m

Oleg Y. Gnedin, Ofer Lahav, Martin J. Rees

Estimating the age of the Universe is an old problem. Rapid progress in observational cosmology in recent years has led to more accurate values of the fundamental parameters. The current most popular model is a flat Universe, with about 30% of the critical density in the form of matter (baryonic and non-baryonic) and 70% in the form of `dark energy&#39;. The

T. Yaqoob

We review what we have learnt with ASCA from studying the Fe-K lines in AGN and describe a program to deconvolve the narrow, non-disk components of the lines with Chandra. This is necessary to derive the correct profiles of the broad, relativistic lines obtained using data from XMM and other high-throughput instruments. Since reverberation techniques are now

T. Tanimori, T. Naito, T. Yoshida, CANGAROO collaboration

The differential spectrum of TeV gamma rays between 1.5 TeV and 20 TeV from the north-east rim of SN1006 was obtained from the data observed in 1996 and 1997 using the 3.8m CANGAROO Čerenkov telescope. This spectrum matches the model calculated using the Inverse Compton (IC) process with 2.7k Cosmic Microwave Background (CMB). This enables us to estimate the

A. Miller, J. Beach, S. Bradley, M. J. Devlin

We describe two related experiments that measured the anisotropy in the cosmic microwave background (CMB). QMAP was a balloon-borne telescope that flew twice in 1996, collecting data on degree angular scales with an array of six high electron mobility transistor-based amplifiers (HEMTs). QMAP was the first experiment to use an interlocking scan strategy to d

E. S. Phinney

There is an extremely simple relationship between the spectrum of the gravitational wave background produced by a cosmological distribution of discrete gravitational wave sources, the total time-integrated energy spectrum of an individual source, and the present-day comoving number density of remnants. Stated in this way, the background is entirely independe

Sean M. Carroll

A brief review is offered of the theoretical background concerning dark energy: what is required by observations, what sort of models are being considered, and how they fit into particle physics and gravitation. Contribution to the SNAP (SuperNova Acceleration Probe) Yellow Book.

Sean M. Carroll, Manoj Kaplinghat

In conventional general relativity, the expansion rate H of a Robertson-Walker universe is related to the energy density by the Friedmann equation. Aside from the present day, the only epoch at which we can constrain the expansion history in a model-independent way is during Big-Bang Nucleosynthesis (BBN). We consider a simple two-parameter characterization

Peter N. Meisinger, Travis R. Miller, Michael C. Ogilvie

Two phenomenological models describing an SU(N) quark-gluon plasma are presented. The first is obtained from high temperature expansions of the free energy of a massive gluon, while the second is derived by demanding color neutrality over a certain length scale. Each model has a single free parameter, exhibits behavior similar to lattice simulations over the

Chong-Sun Chu, Valentin V. Khoze, Gabriele Travaglini

We study in detail the ADHM construction of U(N) instantons on noncommutative Euclidean space-time R_{NC}^4 and noncommutative space R_{NC}^2 x R^2. We point out that the completeness condition in the ADHM construction could be invalidated in certain circumstances. When this happens, regular instanton configuration may not exist even if the ADHM constraints

Norihiro Iizuka, Daniel Kabat, Gilad Lifschytz, David A. Lowe

We use a 0-brane to probe a ten-dimensional near-extremal black hole with N units of 0-brane charge. We work directly in the dual strongly-coupled quantum mechanics, using mean-field methods to describe the black hole background non-perturbatively. We obtain the distribution of W boson masses, and find a clear separation between light and heavy degrees of fr