June 1999 arXiv papers — page 11

E. Comay

It is proved that the phase shift of a polarized neutron interacting with a spatially uniform time-dependent magnetic field, demonstrates the same physical principles as the magnetic Aharonov-Bohm effect. The crucial role of inert objects is explained, thereby proving the quantum mechanical nature of the effect. It is also proved that the nonsimply connected

George F. Bertsch, Thomas Papenbrock, Sanjay Reddy

We extend a recent billiard model of the nuclear N-body Hamiltonian to consider a finite two-body interaction. This permits a treatment of the Hamiltonian by a mean field theory, and also allows the possibility to model reactions between nuclei. The density and the mean field potential can be accurately described by a scaling function which shows the qualita

C. A. Stafford, B. R. Barrett

Recent theoretical investigations of the decay mechanism out of a superdeformed nuclear band have yielded qualitatively different results, depending on the relative values of the relevant decay widths. We present a simple two-level model for the dynamics of the tunneling between the superdeformed and normal-deformed bands, which treats decay and tunneling pr

S. Kondratyuk, O. Scholten

Form factors in the nucleon-photon vertex with one off-shell nucleon are calculated by dressing the vertex with pion loops up to infinite order. Cutting rules and dispersion relations are implemented in the model. Using the prescription of minimal substitution we construct a γπN N vertex and show that it has to be included in the model in order that the Ward

Minhyong Kim, Dinesh S. Thakur, José Felipe Voloch

We associate certain curves over function fields to given algebraic power series and show that bounds on the rank of Kodaira-Spencer map of this curves imply bounds on the exponents of the power series, with more generic curves giving lower exponents. If we transport Vojta's conjecture on height inequality to finite characteristic by modifying it by addi

Yucai Su

A notion of generalized highest weight modules over the high rank Virasoro algebras is introduced, and a theorem, which was originally given as a conjecture by Kac over the Virasoro algebra, is generalized. Mainly, we prove that a simple Harish-Chandra module over a high rank Virasoro algebra is either a generalized highest weight module, or a module of the

J. Scott Carter, Daniel Jelsovsky, Seiichi Kamada, Masahico Saito

State-sum invariants for knotted curves and surfaces using quandle cohomology were introduced by Laurel Langford and the authors in math.GT/9903135 In this paper we present methods to compute the invariants and sample computations. Computer calculations of cohomological dimensions for some quandles are presented. For classical knots, Burau representations to

Piotr Stachura

The construction of a C*-algebra of a differential groupoid is presented. It is shown that it defines a covariant functor from the category of differential groupoids in a sense of S. Zakrzewski to the category of C*-algebras.

Henrik Thys

We prove there is an equivalence of ribbon categories between a category introduced by Turaev whose morphisms are planar diagrams and a full subcategory of the category of finite-dimensional modules over U_q(sl_2).

Greg Kuperberg

Makeev conjectured that every constant-width body is inscribed in the dual difference body of a regular simplex. We prove that homologically, there are an odd number of such circumscribing bodies in dimension 3, and therefore geometrically there is at least one. We show that the homological answer is zero in higher dimensions, a result which is inconclusive

A. Ch. Ganchev, V. B. Petkova, G. M. T. Watts

We find the solution of the $\hat{sl}(3)_k$ singular vector decoupling equations on 3-point functions for the particular case when one of the fields is of weight $w_0\cdot kΛ_0$. The result is a function with non-trivial singularities in the flag variables, namely a linear combination of 2F1 hypergeometric functions. This calculation fills in a gap in [1] an

Emil Martinec, Vatche Sahakian

We study the thermodynamics of the D1-D5 system on a five-torus, focussing on the roles of different scales. One can take a decoupling limit such that the tension of the `little string' inside the fivebrane remains finite and the physics is 5+1 dimensional. The dual black geometry exhibits a boosted Hagedorn phase, as well as a phase describing a boosted

J. Ambjorn, Yu. Makeenko, G. W. Semenoff, R. J. Szabo

The thermal dynamics of D-branes and of open superstrings in background gauge fields is studied. It is shown that D-brane dynamics forbids constant velocity motion at finite temperature. T-duality is used to interpret this feature as a consequence of the absence of an equilibrium state of charged strings at finite temperature in a constant background electri

M. Heller, W. Sasin

A model, based on a noncommutative geometry, unifying general relativity with quantum mechanics, is further develped. It is shown that the dynamics in this model can be described in terms of one-parameter groups of random operators. It is striking that the noncommutative counterparts of the concept of state and that of probability measure coincide. We also d

B. Eynard, G. Bonnet

In this article, we study the q-state Potts random matrix models extended to branched polymers, by the equations of motion method. We obtain a set of loop equations valid for any arbitrary value of q. We show that, for q=2-2 \cos {l \over r} π(l, r mutually prime integers with l < r), the resolvent satisfies an algebraic equation of degree 2 r -1 if l+r is o

F. T. Brandt, J. Frenkel

We give a simple argument for the cancellation of the log(-k^2) terms (k is the gluon momentum) between the zero-temperature and the temperature-dependent parts of the thermal self-energy.

Dario Sassi Thober

It is discussed the singular string associated to the gauge field of monopoles must be a physical observable if the monopole charge is different from zero. It is naturally found that if the gauge is to be an observable, it is possibly connected to gravity.

Prem P. Srivastava, Stanley J. Brodsky

The light-front (LF) canonical quantization of quantum chromodynamics in covariant gauge is discussed. The Dirac procedure is used to eliminate the constraints in the gauge-fixed front form theory quantum action and to construct the LF Hamiltonian formulation. The physical degrees of freedom emerge naturally. The propagator of the dynamical $ψ_+$ part of the

C. Balazs

Shortened table of contents: 1. Introduction 1.1 The Standard Model of Elementary Particles 1.2 The Quantum Nature of Gauge Fields 2. Soft Gluon Resummation 2.1 Lepton Pair Production at Fixed Order in $α_s$ 2.2 The Resummation Formalism 3. Vector Boson Production and Decay in Hadron Collisions 3.1 Vector Boson Distributions 3.2 Lepton Distributions 4. Photo

Cheng-Wei Chiang, Adam K. Leibovich

We provide upper and lower bounds on the form factors for B -> D, D^* by utilizing inclusive heavy quark effective theory sum rules. These bounds are calculated to leading order in Lambda_QCD/m_Q and alpha_s. The O(alpha_s^2 beta_0) corrections to the bounds at zero recoil are also presented. We compare our bounds with some of the form factor models used in

Howard Baer, Sally Dawson, Laura Reina

The cross section for the reaction $e^+e^- \to t\bar{t} H$ depends sensitively on the top quark Yukwawa coupling $λ_t$. We calculate the rate for $t\bar{t}H$ production, followed by the decay $H\to b\bar{b}$, for a Standard Model Higgs boson with 100 < m_H <130 GeV. We interface with ISAJET to generate QCD radiation, hadronization and particle decays. We als

M. Anselmino, M. Boglione, J. Hansson, F. Murgia

Predictions for the single transverse spin asymmetry A_N in semi-inclusive DIS processes are given; non negligible values of A_N may arise from spin effects in the fragmentation of a polarized quark into a final hadron with a transverse momentum k_T with respect to the jet axis, the so-called Collins effect. The elementary single spin asymmetry of the fragme

J. Baacke, C. Patzold

We present a renormalized computational framework for the evolution of a self-interacting scalar field (inflaton) and its quantum fluctuations in an FRW background geometry. We include a coupling of the field to the Ricci scalar with a general coupling parameter $ξ$. We take into account the classical and quantum back reactions, i.e., we consider the the dyn

Y. -Y. Keum, P. Yu. Kulikov, I. M. Narodetskii, H. S. Song

We derive a new parton-like formula, which establishes a simple connection between the electroweak decay rate $Γ(\bar B \to X_sγ$) and the rate of a free b-quark decay. The main features of our approach are the treatment of the b-quark as an on-mass-shell particle and the inclusion of the effects arising from the b-quark transverse motion in the $\bar B$-mes

Ning Wu

In this paper, an electroweak model with massive neutrinos is proposed. The symmetry of the model is $SU(2)_L \times U(1)_Y \times U(1)_M$. Because of the mixing of neutrinos, the conversion of one lepton type to another is possible, but many of those kind processes are of extremely small possibilities. The total lepton-number conservation still holds in thi

Michael Joyce, Kimmo Kainulainen, Tomislav Prokopec

We report on a work in progress, whose goal is a systematic field theoretical derivation of the quantum transport equations for baryon production in the electroweak plasma at a first order phase transition in the limit of slowly varying background fields (thick wall limit). We start with the Schwinger-Dyson equations for the two point Green function written

Alexander Kupco

The HERWIG 5.9 cluster hadronization model is briefly discussed here. It is shown that the model has peculiar behaviour when new heavy baryon resonances are included in the HERWIG 5.9 particle table. New fragmentation model is proposed to cure this problem and simple tuning of HERWIG 5.9 with this new model has been made using event shapes variables and iden

I. Akushevich

QED radiative corrections to the cross section of diffractive electro- and photoproduction of vector mesons is calculated at HERA energies. Both semi-analytical and Monte Carlo approaches are discussed and compared.

A. V. Belitsky, D. Müller

We complete the construction of the non-forward evolution kernels in next-to-leading order responsible for the scale dependence of e.g. parity even singlet distribution amplitudes. Our formalism is designed to avoid any explicit two-loop calculations employing instead conformal and supersymmetric constraints as well as known splitting functions.

I. Akushevich, H. Boettcher, D. Ryckbosch

A new Monte-Carlo generator including real radiated photons in DIS on polarized and unpolarized targets is presented. Analytical and numerical tests are performed and discussed in details.

Christer Friberg, Torbjörn Sjöstrand

The production of jets is studied in collisions of virtual photons, specifically for applications at HERA. Photon flux factors are convoluted with matrix elements involving either direct or resolved photons and, for the latter, with parton distributions of the photon. Special emphasis is put on the range of uncertainty in the modeling of the resolved compone

Steven D. Bass

Gluon topology makes a potentially important contribution to the spin of the constituent quark.

R. O. Avakian, L. A. Gevorgian, K. A. Ispirian, R. K. Ispirian

It is investigated the stimulated radiation which arises when the density and energy of the beam of relativistic particles channeled in microscopic crystallic undulators (CU) obtained by the application of transverse ultrasonic (US) oscillations to single crystals, exceed certain values. For positron beams expected at future linear colliders and real CU it i

E. L. Berger, M. Klasen

The hadroproduction of lepton pairs with mass $Q$ and transverse momentum $Q_T$ can be described in perturbative QCD by the same partonic subprocesses as prompt photon production. We demonstrate that, like prompt photon production, lepton pair production is dominated by quark-gluon scattering in the region $Q_T>Q/2$. This leads to sensitivity to the gluon de

Bronislav Zakharov

Transverse spectra of induced radiation are discussed within the light-cone path integral approach to the LPM effect. The results are applicable in both QED and QCD.

Taku Izubuchi, Kei-ichi Nagai

We investigate the two dimensional lattice Gross--Neveu model in large flavor number limit using the domain-wall fermion formulation, as a toy model of lattice QCD. We study nonperturbative behaviorn of the restoration of chiral symmetry of the domain-wall fermions as the extent of the extra dimension $(N_s)$ is increased to infinity. We find the the parity

Takanori Fujiwara, Hiroshi Suzuki, Ke Wu

Axial anomaly of lattice abelian gauge theory in hyper-cubic regular lattice in arbitrary even dimensions is investigated by applying the method of exterior differential calculus. The topological invariance, gauge invariance and locality of the axial anomaly determine the explicit form of the topological part. The anomaly is obtained up to a multiplicative c

B. Alles, S. Caracciolo, A. Pelissetto, M. Pepe

We give the correct analytic expression of a finite integral appearing in the four-loop computation of the renormalization-group functions for the two-dimensional nonlinear sigma-model on the square lattice with standard action, explaining the origin of a numerical discrepancy. We revise the numerical expressions of Caracciolo and Pelissetto for the perturba

Joyce Garden, Jochen Heitger, Rainer Sommer, Hartmut Wittig

We determine the renormalization group invariant quark mass corresponding to the sum of the strange and the average light quark mass in the quenched approximation of QCD, using as essential input the mass of the K-mesons. In the continuum limit we find $(M_s + M_{light})/F_K=0.874(29)$, which includes systematic errors. Translating this non-perturbative resu

Andrei P. Kirilyuk

The new, complex-dynamical mechanism of the universal gravitation naturally incorporating dynamical quantization, wave-particle duality, and relativity of physically emerging space and time (quant-ph/9902015,16) provides the realistic meaning and fundamentally substantiated modification of the Planckian units of mass, length, and time approaching them closel

D. Polarski

We investigate the possibility for a direct detection by future space interferometers of the stochastic gravitational wave (GW) background generated during the inflationary stage in a class of viable $Λ$CDM BSI models. At frequencies around $10^{-3}$Hz, maximal values $Ω_{gw}(ν)\sim 3\times 10^{-15}$ are found, an improvement of about one order of magnitude

Kerstin E. Kunze

The asymptotic behaviour at late times of inhomogeneous axion-dilaton cosmologies is investigated. The space-times considered here admit two abelian space-like Killing vectors. These space-times evolve towards an anisotropic universe containing gravitational radiation. Furthermore, a peeling-off behaviour of the Weyl tensor and the antisymmetric tensor field

M. Heller, W. Sasin

A model unifying general relativity with quantum mechanics is further developed. It is based on a noncommutative geometry which supposedly modelled the universe in its pre-Planckian epoch. The geometry is totally nonlocal with no time and no space in their usual meaning. They emerge only in the transition process from the noncommutative epoch to the standard

P. Bizoń, T. Chmaj

In a recent paper (gr-qc/9903081) Choptuik, Hirschmann, and Marsa have discovered the scaling law for the lifetime of an intermediate attractor in the formation of n=1 colored black holes via fine tuning. We show that their result is in agreement with the prediction of linear perturbation analysis. We also briefly comment on the dependence of the mass gap ac

Jin Yang, Paolo Grigolini

We adapt the Kolmogorov-Sinai entropy to the non-extensive perspective recently advocated by Tsallis. The resulting expression is an average on the invariant distribution, which should be used to detect the genuine entropic index Q. We argue that the condition Q >1 is time dependent.

T. Senthil, Matthew P. A. Fisher

We develop a theory of quasiparticle localization in superconductors in situations without spin rotation invariance. We discuss the existence, and properties of superconducting phases with localized/delocalized quasiparticle excitations in such systems in various dimensionalities. Implications for a variety of experimental systems, and to the properties of r

Paolo Politi, Genevieve Grenet, Alain Marty, Anne Ponchet

The planar front of a growing a crystal is often destroyed by instabilities. In the case of growth from a condensed phase, the most frequent ones are diffusion instabilities, which will be but briefly discussed in simple terms in chapter II. The present review is mainly devoted to instabilities which arise in ballistic growth, especially Molecular Beam Epita

R. J. Radwanski

In contrary to widely spread view about the substantial delocalization of f electrons in heavy- fermion (h-f) compounds it is argued that h-f phenomena can be understood with localized f electrons. Then the role of crystal-field interactions is essential and the heavy-fermion behaviour can occur for the localized Kramers-doublet ground state.

J. P. Warren, C. D. H. Williams

We report a preliminary experiment which demonstrates that 3He atoms in Andreev states are evaporated by high-energy (E/k_B ~ 10.2 K) phonons in a quantum evaporation process similar to that which occurs in pure 4He. Under conditions of low 3He coverage, high-energy phonons appear to evaporate 3He and 4He atoms with equal probability. However, we have not ma

P. T. Coleridge, P. Zawadzki, A. S. Sachrajda, R. L. Williams

Magnetoresistance measurements are presented for a strained p-SiGe quantum well sample where the density is varied through the B=0 metal-insulator transition. The close relationship between this transition, the high field Hall insulator transition and the filling factor $ν$=3/2 insulating state is demonstrated.

J. P. Warren, C. D. H. Williams

We have used quantum evaporation to investigate the two-dimensional fermion system that forms at the free surface of (initially isotopically pure) 4He when small quantities of 3He are added to it. By measuring the first-arrival times of the evaporated atoms, we have determined that the 3He-3He potential in this system is V_3S/k_B=(0.23+/-0.02) K nm^2 (repuls

N. K. Wilkin, J. M. F. Gunn

We provide evidence for several novel phases in the dilute limit of rotating BECs. By exact calculation of wavefunctions and energies for small numbers of particles, we show that the states near integer angular momentum per particle are best considered condensates of composite entities, involving vortices and atoms. We are led to this result by explicit comp

G. L. W. Hart, B. M. Klein

We present several results related to the instability of MoC and MoN in the B1 (sodium chloride) structure. These compounds were proposed as potential superconductors with moderately high transition temperatures. We show that the elastic instability in B1-structure MoN, demonstrated several years ago, persists at elevated pressures, thus offering little hope

Stephan Buechner, Andreas Heuer

It is possible to formulate the thermodynamics of a glass forming system in terms of the properties of inherent structures, which correspond to the minima of the potential energy and build up the potential energy landscape in the high-dimensional configuration space. In this work we quantitatively apply this general approach to a simulated model glass-formin

B. Mehlig, J. T. Chalker

Statistical properties of eigenvectors in non-Hermitian random matrix ensembles are discussed, with an emphasis on correlations between left and right eigenvectors. Two approaches are described. One is an exact calculation for Ginibre&#39;s ensemble, in which each matrix element is an independent, identically distributed Gaussian complex random variable. The

Stephan Buechner, Andreas Heuer

Computer simulations of a model glass-forming system are presented, which are particularly sensitive to the correlation between the dynamics and the topography of the potential energy landscape. This analysis clearly reveals that in the supercooled regime the dynamics is strongly influenced by the presence of deep valleys in the energy landscape, correspondi

Victor M. Yakovenko, Hsi-Sheng Goan, Jonghwa Eom, Woowon Kang

We discuss the temperature dependence of the Hall conductivity $σ_{xy}$ in the magnetic-field-induced spin-density-wave (FISDW) state of the quasi-one-dimensional Bechgaard salts (TMTSF)_2X. Electronic thermal excitations across the FISDW energy gap progressively destroy the quantum Hall effect, so $σ_{xy}(T)$ interpolates between the quantized value at zero

Jens Eggers

We consider a dilute gas of granular material inside a box, kept in a stationary state by shaking. A wall separates the box into two identical compartments, save for a small hole at some finite height $h$. As the gas is cooled, a second order phase transition occurs, in which the particles preferentially occupy one side of the box. We develop a quantitative

M. Sieling, U. Löw, B. Wolf, S. Schmidt

We present electron spin resonance experiments in the one-dimensional antiferromagnetic S=1 spin chains NENP and NINO in pulsed magnetic fields up to 50T. The measured field dependence of the quantum energy gap for B||b is analyzed using the exact diagonalization method and the density matrix renormalization group method (DMRG). A staggered anisotropy term (

Alexander K. Hartmann

Ground states of three-dimensional EA Ising spin glasses are calculated for sizes up to 14^3 using a combination of a genetic algorithm and cluster-exact approximation. For each realization several independent ground states are obtained. Then, by applying ballistic search and T=0 Monte-Carlo simulations, it is ensured that each ground state appears with the

Arkadi A. Odintsov, Yasuhiro Tokura

Poor screening of the long-range Coulomb interaction in one-dimensional carbon nanotubes results in a peculiar picture of contact phenomena. Being brought to a contact with a metal, conducting nanotube accumulates electric charge whose density decays slowly with the distance from the contact. This should be contrasted to a conventional metal-metal contact wh

Yoichi Ando, T. Murayama, S. Ono

We report that it is possible to obtain a series of high-quality crystals of La-doped Bi-2201, of which the transport properties have been believed to be &#34;dirtier&#34; than those of other cuprates. In our crystals, the normal-state transport properties display behaviors which are in good accord with other cuprates; for example, in the underdoped region t

Joerg Rollbuehler, Arkadi A. Odintsov

We study the interference of interacting electrons in toroidal single-wall carbon nanotubes coupled to metallic electrodes by tunnel junctions. The dc conductance shows resonant features as a function of the gate voltage and the magnetic field. The conductance pattern is determined by the interaction parameter, which in turn can be cross-checked against the

Radim Vocka

We study the diffusion on an annealed disordered lattice with a local dynamical reorganization of bonds. We show that the typical rearrangement time depends on the renewal rate like $t_r \sim τ^α$ with $α\neq 1$. This implies that the crossover time to normal diffusion in a slow rearrangement regime shows a critical behavior at the percolation threshold. New

J. H. Jung, E. J. Choi, H. J. Lee, Jaejun Yu

We investigated optical properties of Pr_{0.5}Sr_{0.5}MnO_3, which has the A-type antiferromagnetic ordering at a low temperature. We found that T- dependence of spectral weight transfer shows a clear correlation with the magnetic phase transition. In comparison with the optical conductivity results of Nd_{0.5}Sr_{0.5}MnO_3, which has the CE-type antiferroma

K. Shizuya

A numerical analysis is made of the breakdown of the quantum Hall effect caused by the Hall electric field in competition with disorder. It turns out that in the regime of dense impurities, in particular, the number of localized states decreases exponentially with the Hall field, with its dependence on the magnetic and electric field summarized in a simple s

Unjong Yu, B. I. Min

Based on the combined model of the double exchange and the polaron, we have studied the small-to-large polaron crossover transition and explored its effects on the magnetic and transport properties in colossal magnetoresistance (CMR) manganites. We have used the variational Lang-Firsov canonical transformation, and shown that the magnetic and transport prope

J. M. Marin, J. Boronat, J. Casulleras

We have studied the solubility of molecular hydrogen in bulk liquid $^4$He at zero temperature using the diffusion Monte Carlo method and realistic interatomic potentials between the different species of the mixture. Around the $^4$He equilibrium density, the H_2 molecules clusterize in liquid-like drops blocking the existence of a uniform dilution. On the c

Leon Balents, Chandra M. Varma

The theory of doped excitonic insulators is reinvestigated in light of recent experiments on hexaborides. For the appropriate valley-degenerate X_3,X_3&#39; band structure, ``intra-valley&#39;&#39; condensation is energetically favored. Ferromagnetism occurs upon doping due to the quenching of kinetic energy at the otherwise direct first-order excitonic insu

S. Sridhar, Z. Zhai, A. Erb

We show that a common feature of temperature-dependent microwave absorption is the presence of absorption peaks. $ac$ loss peaks can arise when the internal $T$-dependent magnetic relaxation time crosses the measurement frequency. These features are observed in the \QTR{em}{insulating} ($Sr_{x}Ca_{14-x}Cu_{24}O_{41}$, $La_{5/3}Sr_{1/3}NiO_{4}$ and $YBa_{2}Cu

Zhongwei Pan, Richard Chin

Ultraviolet fluorescence (UVF) is introduced as a novel and versatile method for the determination of the contamination of metal impurities on silicon wafer surfaces. The results given demonstrate the usefulness of UVF for contamination control in silicon wafer processing. The experiments show some main characteristic peaks such as Fe, Cu, Ni and Na at room

Zhongwei Pan, Richard Chin

In this paper, we mainly present a new simple, efficient and nondestructive Raman scattering analysis method to study the distribution of strain in SiGe alloy films. The method can simultaneously determine both Ge fractional composition x and strain of SiGe films. We use the Ar+ laser lines (514.5, 488 and 457.9 nm) to detect the information of different dep

C. P. Dettmann

Nonequilibrium molecular dynamics simulations often use mechanisms called thermostats to regulate the temperature. A Hamiltonian is presented for the case of the isoenergetic (constant internal energy) thermostat corresponding to a tunable isokinetic (constant kinetic energy) thermostat, for which a Hamiltonian has recently been given.

M. Chertkov, G. Falkovich, I. Kolokolov, M. Vergassola

Kinematic dynamo theory is presented here for turbulent conductive fluids. We describe how inhomogeneous magnetic fluctuations are generated below the viscous scale of turbulence where the spatial smoothness of the velocity permits a systematic analysis of the Lagrangian path dynamics. We find analytically the moments and multi-point correlation functions of

Cristobal Lopez, Zoltan Neufeld, Emilio Hernandez-Garcia, Peter H. Haynes

We study the spatial patterns formed by interacting populations or reacting chemicals under the influence of chaotic flows. In particular, we have considered a three-component model of plankton dynamics advected by a meandering jet. We report general results, stressing the existence of a smooth-filamental transition in the concentration patterns depending on

M. Landgraf

The interaction of dust grains originating from the local interstellar cloud with the environment inside the heliosphere is investigated. As a consequence of this interaction the spatial distribution of interstellar dust grains changes with time. Since dust grains are charged in the interplanetary plasma and radiation environment, the interaction of small gr

Donald F. Figer, Sungsoo S. Kim, Mark Morris, Eugene Serabyn

We report Hubble Space Telescope (HST) Near-infrared Camera and Multi-object Spectrometer (NICMOS) observations of the Arches and Quintuplet clusters, two extraordinary young clusters near the Galactic Center. For the first time, we have identified main sequence stars in the Galactic Center with initial masses well below 10 Msun. We present the first determi

E. Parizot, L. Drury

We investigate the spallative production of the light elements, Li, Be and B (LiBeB), associated with the evolution of a superbubble (SB) blown by repeated SNe in an OB association. It is shown that if about ten percent of the SN energy can power the acceleration of particles from the material inside the SB, the observed abundances of LiBeB in halo stars, as

M. E. Machacek, G. L. Bryan, A. Meiksin, P. Anninos

We investigate the properties of the Lyman alpha forest as predicted by numerical simulations for a range of currently viable cosmological models. This is done in order to understand the dependencies of the forest on cosmological parameters. Focusing on the redshift range from two to four, we show that: (1) most of the evolution in the distributions of optic

E. Gaztanaga, P. Fosalba, E. Elizalde

The gravitational evolution of the cosmic one-point probability distribution function (PDF) has been estimated using an analytic approximation that combines gravitational perturbation theory with the Edgeworth expansion around a Gaussian PDF. Despite the remarkable success of the Edgeworth expansion in modeling the weakly non-linear growth of fluctuations ar

T. J. Turner, I. M. George, Hagai Netzer

We present an ASCA observation of the NLSy1 Ark 564. The X-ray light curve shows rapid variability, but no evidence for energy-dependence to these variations, within the 0.6 -- 10 keV bandpass. A strong (EW ~ 70 eV) spectral feature is observed close to 1 keV. A similar feature has been observed in TON S180 (another NLSy1) but has not been observed in broad-

R. de Grijs, R. F. Peletier

We compare two methods of distance determination to spiral galaxies using optical/near-infrared (NIR) observations, the (I-K) versus M_K colour - absolute magnitude (CM) relation and the I and K-band Tully-Fisher relation (TFR). Dust-free colours and NIR absolute magnitudes greatly enhance the usefulness of the NIR CM relation as a distance indicator for mod

Luciano Lorenzi

The topic of the paper is the mathematical analysis of a radially decelerated Hubble expansion from the Bahcall & Soneira void center. Such analysis, in the hypothesis of local homogeneity and isotropy, gives a particular Hubble ratio dipole structure to the expansion equation, whose solution has been studied at different precision orders and successfully te

M. Rodriguez

A study of [Fe II] lines at various positions within the H II regions M42 and M43 is presented. The relative intensities of selected optical [Fe II] lines are shown to be correlated with the intensity of the apparent nebular continuous spectrum. Since the continuum of H II regions is known to be mostly stellar radiation scattered by dust intermixed with the

Luciano Lorenzi

To add to and refine the model presented at the Grado3 meeting, of a radial Hubble expansion from the Bahcall & Soneira huge void center, it is here outlined a formal analytical formulation of the theory and modelling on which the previous check work based itself. The new Hubble Law contains the distance R from the expansion center, multiplied by an angular

M. Vietri, C. Perola, L. Piro, L. Stella

Recently, BeppoSAX and ASCA have reported an unusual resurgence of soft X-ray emission during the afterglows of GRB 970508 and GRB 970828, together with marginal evidence for the existence of Fe-lines in both objects. We consider the implications of the existence of a torus of iron-rich material surrounding the sites of gamma ray bursts as would be expected

L. Lara, I. Marquez, W. D. Cotton, L. Feretti

We present radio and optical observations of the peculiar radio galaxy J1835+620, a member of a new sample of large angular size radio galaxies selected from the NRAO VLA Sky Survey. Its optical counterpart is in a group of at least three galaxies and shows strong, narrow emission lines which allow us to measure its redshift as z=0.518. The derived cosmologi

J. Nevalainen, M. Markevitch, W. R. Forman

We combine spatially resolved ASCA temperature data with ROSAT imaging data to constrain the total mass distribution in the cluster A401, assuming that the cluster is in hydrostatic equilibrium. We obtain a total mass within the X-ray core (290/h_50 kpc) of 1.2[+0.1,-0.5] 10^14 /h_50 Msun at the 90% confidence level, 1.3 times larger than the isothermal esti

Cornelia C. Lang, K. R. Anantharamaiah, N. E. Kassim, T. J. W. Lazio

We report the discovery of a new non-thermal filament, G358.85+0.47, the ``Pelican&#39;&#39;, located ~225 pc in projection from SgrA, and oriented parallel to the Galactic plane. VLA continuum observations at 20 cm reveal that this 7&#39; (17.5 pc) structure bends at its northern extension and is comprised of parallel strands, most apparent at its ends. Obs

K. Tatematsu, D. T. Jaffe, R. Plume, N. J. Evans

We have mapped the C I 3P1-3P0 line at 492 GHzin three molecular clouds immersed in weak ultraviolet radiation fields, TMC-1, L134N, and IC 5146. In all three clouds, the CI peak TA* ~ 1 K, with very small dispersion. The spatial C I distribution is extended and rather smooth. The J = 2-1 transitions of CO isotopomers were observed at the same angular resolu

M. E. Kaiser, L. D. Bradley, J. B. Hutchings, D. M. Crenshaw

We present slitless spectra of the Narrow Line Region (NLR) in NGC4151 from the Space Telescope Imaging Spectrograph (STIS) on HST, and investigate the kinematics and physical conditions of the emission line clouds in this region. Using medium resolution (~0.5 Angstrom) slitless spectra at two roll angles and narrow band undispersed images, we have mapped th

Per Kraus, Finn Larsen, Ruud Siebelink

The divergences of the gravitational action are analyzed for spacetimes that are asymptotically anti-de Sitter and asymptotically flat. The gravitational action is rendered finite using a local counterterm prescription, and the relation of this method to the traditional reference spacetime is discussed. For AdS, an iterative procedure is devised that determi

Anushree Roy, Chiung-Yuan Lin, U. Mohideen

We report an improved precision measurement of the Casimir force. The force is measured between a large Al coated sphere and flat plate using an Atomic Force Microscope. The primary experimental improvements include the use of smoother metal coatings, reduced noise, lower systematic errors and independent measurement of surface separations. Also the complete

Heinz Sorge

In the first part I discuss the sensitivity of collective matter expansion in ultrarelativistic heavy-ion collisions to the transition between quark and hadronic matter (physics of the softest point of the Equation of State). A kink in the centrality dependence of elliptic flow has been suggested as a signature for the phase transition in hot QCD matter. Ind

David Atwood, Shaouly Bar-Shalom, Amarjit Soni

We consider the scattering amplitudes of the form V_1 V_2 -> V_3 V_4, where V_i=γ, Z, W or g(=gluon) are the Standard Model gauge bosons, due to graviton exchange in Kaluza-Klein theories with large extra dimensions. This leads to a number of experimentally viable signatures at high energy leptonic and hadronic colliders. We discuss the observability or futu

Michael P. Schmidt

Preliminary results from two recent CDF b physics analysis are presented. The first obtains sin(2beta) = 0.79 + 0.41 -0.44 from a measurement of the asymmetry in B0, B0bar to J/psi K_short decays, providing the best direct indication so far that CP invariance is violated in the b sector. The second obtains new results on the parity even (A_0 and A_par) and o

Asantha R. Cooray

A significant cross-correlation between the unresolved X-ray background (XRB) at soft energies (0.5 to 2 keV) and foreground bright galaxies has now been reported in several studies. This cross-correlation has been interpreted in terms of a low redshift and a low luminosity active galactic nuclei (AGN) population, clustered similar to optically bright galaxi

Hisa-aki Shinkai, Gen Yoneda

We present a set of dynamical equations based on Ashtekar's extension of the Einstein equation. The system forces the space-time to evolve to the manifold that satisfies the constraint equations or the reality conditions or both as the attractor against perturbative errors. This is an application of the idea by Brodbeck, Frittelli, Huebner and Reula who cons

Roger Ellman

A number of years ago the estimates of astronomers and astrophysicists were that the earliest galaxies took about 2.5 to 3 billion years to form, that is, that they did not appear until 2.5 to 3 billion years after the Big Bang. Those estimates were based on analysis of the processes involved in star formation and in the aggregation and &#34;clumping&#34; of

Frantisek Slanina, Yi-Cheng Zhang

A model of open economics composed of producers and speculators is investigated by numerical simulations. The capital flows from the environment to the producers and from them to the speculators. The price fluctuations are suppressed by the speculators. When the aggressivity of the speculators grows, there is a transition from the regime with almost sure pro