August 2000 arXiv papers — page 12

M Painchault, J Gaiffier, C Chauvin

The RFQ of the project IPHI is a 8 meter long, high power, very precise tolerances (0.01 mm on 1 meter long for example) device to accelerate protons. This RFQ is similar to the RFQ of the LEDA project. So, we realize a thermal and mechanical studies followed by different tests for machining and brazing copper. We describe in this paper those different steps

W. Barth, P. Forck, J. Glatz, W. Gutowski

The new 1.4 MeV/u front end HSI (HochStromInjektor) of the Unilac accelerates ions with A/q ratios of up to 65 and with beam intensities in emA of up to 0.25 A/q. The maximum beam pulse power is up to 1300 kW. During the stepwise linac commissioning from April to Septem-ber 1999 the beam behind of each cavity was analysed within two weeks. A very stable Ar1+

G. Hutter, W. Gutowski, W. Hartmann, G. Kube

The RF part of the new high current injector-linac HSI consists of five cavities with the new operating frequency of 36 MHz instead of 27 MHz of the removed Wideroe type injector. The calculated power requirements of the cavities including beam load in three structures were between 110 kW for a rebuncher and 1.75 MW pulse-power for the two IH-cavities. The b

T. Imai, K. Nakai, H. Hayano, J. Urakawa

A double kicker system which extracts the ultra-low emittance multi-bunch beam stably from ATF damping ring was developed. The performance of the system was studied comparing an orbit jitter with single kicker extraction in single bunch mode. The position jitter reduction was estimated from the analysis of the extraction orbits. The reduction was confirmed f

D. Schulte, I. Syratchev

Compensation of multi-bunch beam loading is of great importance in the main linac of the Compact Linear Collider (CLIC). The bunch-to-bunch energy variation has to stay below 1 part in 1000. In CLIC, the RF power is obtained by decelerating a drive beam which is formed by merging a number of short bunch trains. A promising scheme for tackling beam loading in

D. Schulte

A new CLIC Test Facility (CTF3) at CERN will serve to study the drive beam generation for the Compact Linear Collider (CLIC). CTF3 has to accelerate a 3.5 A electron beam in almost fully-loaded structures. The pulse contains more than 2000 bunches, one in every second RF bucket, and has a length of more than one microsecond. Different options for the lattice

R. Corsini, A. Ferrari, J. P. Potier, L. Rinolfi

The CLIC (Compact Linear Collider) RF power source is based on a new scheme of electron pulse compression and bunch frequency multiplication using injection by transverse RF deflectors into an isochronous ring. In this paper, we describe the modifications needed in the present LEP Pre-Injector (LPI) complex at CERN in order to perform a low-charge test of th

D. Schulte

In future normal-conducting linear colliders, the beams will be delivered in short bursts with a length of the order of 100 ns. The pulses will be separated by several ms. In order to maintain high luminosity, feedback is necessary on a pulse-to-pulse basis. In addition, intra-pulse feedback that can correct beam positions and angles within one pulse seem te

Alban Mosnier

Spallation source dedicated for neutron scattering experiments, as well as multi-purpose facilities serving several applications call for pulsed mode operation of a high intensity proton linac. There is general agreement on the superconducting technology for the high-energy part, which offers some advantages, like higher gradient capabilities or operational

Michael Schwamb, Hartmuth Arenhoevel

Photodisintegration of the deuteron above $π$ threshold is studied in a coupled channel approach including $N Δ$ and $πd$ channels with consideration of pion retardation in potentials and exchange currents. A much improved description of total and differential cross sections in the energy region between $π$ threshold and 400-450 MeV is achieved. With respect

G. Baur, K. Hencken, D. Trautmann, S. Typel

Breakup reactions are generally quite complicated, they involve nuclear and electromagnetic forces including interference effects. Coulomb dissociation is an especially simple and important mechanism since the perturbation due to the electric field of the nucleus is exactly known. Therefore firm conclusions can be drawn from such measurements. Electromagneti

Malcolm Butler, Jiunn-Wei Chen, Xinwei Kong

We study the four channels associated with neutrino-deuteron breakup reactions at next-to-next to leading order in effective field theory. We find that the total cross-section is indeed converging for neutrino energies up to 20 MeV, and thus our calculations can provide constraints on theoretical uncertainties for the Sudbury Neutrino Observatory. We stress

Detlef Lohse

Periodically kicked turbulence is theoretically analyzed within a mean field theory. For large enough kicking strength A and kicking frequency f the Reynolds number grows exponentially and then runs into some saturation. The saturation level can be calculated analytically; different regimes can be observed. For large enough Re we find the saturation level to

Bruno Eckhardt, Imre Varga, Peter Pollner

The fluctuations and correlations of matrix elements of cross sections are investigated in open systems that are chaotic in the classical limit. The form of the correlation functions is discussed within a statistical analysis and tested in calculations for a damped quantum kicked rotator. We briefly comment on the modifications expected for systems with slow

R. C. Orellana, Mike Zabrocki

We compute an explicit formula the Hilbert (Poincaré) series for the ring of hook Schur functions and (equivalently) the generating function for partitions which fit in a $(k,l)$-hook.

Jeffrey C. Lagarias

This paper describes the local density inequality approach to getting upper bounds for sphere packing densities in R^n. This approach was first suggested by L. Fejes-Toth in 1956 to prove the Kepler conjecture that the densest sphere packing in R^3 is the "cannonball packing". The approaches of L. Fejes-Toth, W.-Y. Hsiang, and T. Hales to the Kepler

John Bell, Alexandre J. Chorin, William Crutchfield

Optimal prediction (OP) methods compensate for a lack of resolution in the numerical solution of complex problems through the use of an invariant measure as a prior measure in the Bayesian sense. In first-order OP, unresolved information is approximated by its conditional expectation with respect to the invariant measure. In higher-order OP, unresolved infor

Philippe Roche, Andras Szenes

We describe an efficient construction of a canonical non-commutative deformation of the algebraic functions on the moduli spaces of flat connections on a Riemann surface. We show that this algebra, which is a variant of the quantum moduli algebra introduced by Alekseev-Grosse-Schomerus and Buffenoir-Roche, has a trace functional which is related to the canon

R. M. Kashaev

The operator realizing a Dehn twist in quantum Teichmuller theory is diagonalized and continuous spectrum is obtained. This result is in agreement with the expected spectrum of conformal weights in quantum Liouville theory at c>1. The completeness condition of the eigenvectors includes the integration measure which appeared in the representation theoretic ap

J. Cortes, M. de Leon, D. Martin de Diego, S. Martinez

We study mechanical systems subject to constraint functions that can be dependent at some points and independent at the rest. Such systems are modelled by means of generalized codistributions. We discuss how the constraint force can transmit an impulse to the motion at the points of dependence and derive an explicit formula to obtain the ``post-impact'&#

Dimitri Shlyakhtenko

We show that for each (0<λ<1), the free Araki-Woods factor of type III(_λ) cannot be written as a tensor product of two diffuse von Neumann algebras (i.e., is prime), and does not contain a Cartan subalgebra.

J. Niederle, B. Zupnik

The SU(3)/U(1) x U(1) harmonic variables are used in the harmonic-superspace representation of the D=4, N=3 SYM-equations. The harmonic superfield equations of motion in the simple non-covariant gauge contain the nilpotent harmonic analytic connections. It is shown that these harmonic SYM-equations are equivalent to the finite set of solvable linear iterativ

G. C. McLaughlin

The type II supernova is considered as a candidate site for the production of heavy elements. Since the supernova produces an intense neutrino flux, neutrino scattering processes will impact element formation. We examine active-sterile neutrino conversion in this environment and find that it may help to produce the requisite neutron-to-seed ratio for synthes

G. C. McLaughlin, J. N. Ng

The use of extra dimensional scenarios as models for neutrino mass affects many low energy observables. We consider the implications of virtual bulk neutrinos in precision experiments of the anomalous magnetic moments of the muon and the electron. We consider neutrino models in factorizable geometry of the type M_4 x T as well as the sliced AdS_5 non-factori

R. Rapp, E. Shuryak, I. Zahed

The analogue of Overhauser (particle-hole) pairing in electronic systems (spin-density waves with non-zero total momentum $Q$) is analyzed in finite-density QCD for 3 colors and 2 flavors, and compared to the color-superconducting BCS ground state (particle-particle pairing, $Q$=0). The calculations are based on effective nonperturbative four-fermion interac

Pierre van Baal

We will review our understanding of non-abelian gauge theories in finite physical volumes. It allows one in a reliable way to trace some of the non-perturbative dynamics. The role of gauge fixing ambiguities related to large field fluctuations is an important lesson that can be learned. The hamiltonian formalism is the main tool, partly because semiclassical

C. S. Lam

A $Z_{2L}\times Z_{2R}$ generation symmetry in the neutrino sector predicts the atmospheric neutrino mixing to be maximal, and the MNS matrix element $U_{e3}$ to be zero, consistent with observations. Solar neutrino mixing may be maximal but is not required by the symmetry. Neutrino masses of the first two generations are predicted to vanish, providing a fir

A. I. Davydychev, P. Osland, L. Saks

Results on the one-loop quark-gluon vertex with massive quarks are reviewed, in an arbitrary covariant gauge and in arbitrary space-time dimension. We show how it is possible to get on-shell results from the general off-shell expressions. The corresponding Ward-Slavnov-Taylor identity is discussed.

C. B. Mariotto, M. B. Gay Ducati, G. Ingelman

We show that both hard perturbative and soft non-perturbative QCD effects are important in hadroproduction of charmonium. Observed $x_F$ and $p_\perp$ distributions of J/psi in fixed target experiments can be well described by our Monte Carlo model based on perturbative QCD and the Color Evaporation Model.

V. P. Efrosinin, I. B. Khriplovich, G. G. Kirilin, Yu. G. Kudenko

We calculate the transverse muon polarization in the decay $K^{\pm}\toπ^0μ^{\pm}ν$ induced by the electromagnetic two-photon final-state interaction. For the central part of the Dalitz plot the typical value of this polarization is about $4\times 10^{-6}$.

P. Csizmadia, P. Levai

We study the production of the D and J/psi mesons from deconfined quark matter at CERN SPS energy. Using the MICOR microscopical coalescence model we determine the transverse momentum spectra of these charm mesons. We predict the slopes of their transverse momentum spectra in Pb+Pb collision at 158 GeV/nucleon beam energy.

John P. Ralston, Pankaj Jain, Bijoy Kundu, Jim Samuelsson

A brief overview of the status of color transparency experiments is presented. We report on the first complete calculations of color transparency within a perturbative QCD framework. We also comment on the underlying factorization method and assumptions. Detailed calculations show that the slope of the transparency ratio with $Q^2$, and the effective attenua

S. Pakvasa

It is shown that explanations of atmospheric neutrino anomaly other than $ν_μ- ν_τoscillations (e.g. decay, decoherence and $ν_μ- ν_τ- ν_{KK}$ mixing) can be tested at future facilities. Stringent tests of CPT invariance in neutrino oscillations can also be performed.

Bogdan A. Dobrescu, Konstantin T. Matchev

We analyze the Higgs sector in the Next-to-Minimal Supersymmetric Standard Model, emphasizing the possibility of a light CP-odd scalar (axion) in the spectrum. We compute the coupling of the Standard-Model-like Higgs boson to a pair of axions, and show that it can be large enough to modify the Higgs branching fractions, with a significant impact on the Higgs

A. Airapetian

The dependence on Q^2 (the negative square of the 4-momentum of the exchanged virtual photon) of the generalised Gerasimov-Drell-Hearn integral for the proton has been measured in the range 1.2 GeV^2 < Q^2 < 12 GeV^2 by scattering longitudinally polarised positrons on a longitudinally polarised hydrogen gas target. The contributions of the nucleon-resonance

T. Higo, Y. Funahashi, Y. Higashi, N. Hitomi

Following successful design and fabrication of damped detuned structures, the R&D for the accelerating structures of the NLC/JLC linear collider project proceeded to studies of Rounded Damped Detuned Structure with curved cross section of the cavity shape for increased shunt impedance. The important features of the structure are the accurately tuned accelera

N. Hitomi, Y. Funahashi, Y. Higashi, T. Higo

Following the successful design and fabrication of Damped Detuned Structures (DDS), the JLC/NLC linear collider project advanced to Rounded Damped Detuned Structures (RDDS) with curved cross section of the cavity shape for increased shunt impedance. Various advanced techniques for fabricating RDDS1 disks comparing to those for DDS were established to satisfy

T. Naito, K. Ebihara, H. Hayano, J. Urakawa

The rf distribution system for the linear collider requires stable x-band(11.424GHz) rf phase signal over 25km length. In order to realize the distribution system, a fiber optic link using a phase stabilized optical fiber was tested. The phase stabilized optical fiber has been employed at LEP, KEKB, etc.. This paper describes the hardware system and result o

M. Kalelkar

We report results on two physics topics from the SLD experiment at the SLAC Linear Collider, using our full sample of 550,000 events of the type e+e- --> Z0 --> q-q(bar). The electron beam was polarized, enabling the quark and antiquark hemispheres to be tagged in each event. One physics topic is the first study of rapidities signed such that positive rapidi

A. Hosoya, A. Carlini, T. Shimomura

We propose a quantum version of a gedanken experiment which supports the generalized second law of black hole thermodynamics. A quantum measurement of particles in the region outside of the event horizon decreases the entropy of the outside matter due to the entanglement of the inside and outside particle states. This decrease is compensated, however, by the

Markus Walther

Temiar reduplication is a difficult piece of prosodic morphology. This paper presents the first computational analysis of Temiar reduplication, using the novel finite-state approach of One-Level Prosodic Morphology originally developed by Walther (1999b, 2000). After reviewing both the data and the basic tenets of One-level Prosodic Morphology, the analysis

Guy De Pauw

Data-Oriented Parsing (dop) ranks among the best parsing schemes, pairing state-of-the art parsing accuracy to the psycholinguistic insight that larger chunks of syntactic structures are relevant grammatical and probabilistic units. Parsing with the dop-model, however, seems to involve a lot of CPU cycles and a considerable amount of double work, brought on

Veronique Hoste, Walter Daelemans, Erik Tjong Kim Sang, Steven Gillis

We apply rule induction, classifier combination and meta-learning (stacked classifiers) to the problem of bootstrapping high accuracy automatic annotation of corpora with pronunciation information. The task we address in this paper consists of generating phonemic representations reflecting the Flemish and Dutch pronunciations of a word on the basis of its or

L. Balicas, J. S. Brooks, K. Storr, D. Graf

Shubnikov-De Haas effect (SdH) effect and angular dependent magnetoresistance oscillations (AMRO) were observed in the organic superconductor: $κ$-(BETS)$_2$FeBr$_4$. In contrast to its isostructural compound $κ-(BETS)$_2$FeCl$_4$, SdH oscillations, for fields perpendicular to the conducting planes, reveal three Fermi Surface (FS) closed orbits $α$, $β$, and

F. W. S. Lima, U. M. S. Costa, M. P. Almeida, J. S. Andrade

We use the single-histogram technique to study the critical behavior of the three-state Potts model on a (random) Voronoi-Delaunay lattice with size ranging from 250 to 8000 sites. We consider the effect of an exponential decay of the interactions with the distance,$J(r)=J_0\exp(-ar)$, with $a>0$, and observe that this system seems to have critical exponents

Gilberto Luiz Hoenicke, Wagner Figueiredo

A random distribution of inert sites is introduced in the Ziff-Gulari-Barshad model to study the phase transitions between active and poisoned states. The adsorption of ${\rm CO}$ and ${\rm O_2}$ molecules is not possible at the position of the inert sites. This model is investigated in the site and pair approximations, as well as through Monte Carlo simulat

Brian H. Ward, Isaac B. Rutel, James S. Brooks, John A. Schlueter

The first purely organic BEDT-TTF spin-Peierls system, b&#39;-(ET)2SF5CF2SO3, has been confirmed using a high-frequency electron spin resonance (EPR) cavity perturbation technique. The material exhibits the characteristics of a quasi-one-dimensional (1D) Heisenberg antiferromagnetic spin system above 30 K, but undergoes a second-order transition, at TSP = 33

U. Buchenau

The Gilroy-Phillips model of relaxational jumps in asymmetric double-well potentials, developed for the Arrhenius-type secondary relaxations of the glass phase, is extended to a formal description of the breakdown of the shear modulus at the glass transition, the flow process.

B. R. Trees, R. A. Murgescu

We report on a theoretical analysis, consisting of both numerical and analytic work, of the stability of synchronization of a ladder array of Josephson junctions under the influence of current induced magnetic fields. Surprisingly, we find that as the ratio of the mutual to self inductance of the cells of the array is increased a region of unstable behavior

Marlon Pierce, Efstratios Manousakis

Using a path-integral Monte Carlo method for simulating superfluid quantum films, we investigate helium layers adsorbed on a substrate consisting of graphite plus two solid helium layers. Our results for the promotion densities and the dependence of the superfluid density on coverage are in agreement with experiment. We can also explain certain features of t

A. Milchev, J. P. Wittmer, P. van der Schoot, D. Landau

The osmotic pressure $P$ in equilibrium polymers (EP) in good solvent is investigated by means of a three dimensional off-lattice Monte Carlo simulation. Our results compare well with real space renormalisation group theory and the osmotic compressibility $K \propto ϕ\upd ϕ/\upd P$ from recent light scattering study of systems of long worm-like micelles. We

O. Buisson, F. W. J. Hekking

We study the dynamics of a quantum superconducting circuit which is the analogue of an atom in a high-Q cavity. The circuit consists of a Josephson charge qubit coupled to a superconducting resonator. The charge qubit can be treated as a two level quantum system whose energy separation is split by the Josephson energy $E_j$. The superconducting resonator in

Z. Ropka, R. Michalski, R. J. Radwanski

Magnetic moment of the Fe2+ ion in FeBr2 has been calculated to be 4.32 mB in the magnetically-ordered state at 0 K. It is composed from the spin moment of 3.52 mB and the orbital moment of +0.80 mB. These calculations show that for the meaningful analysis of e-m properties of FeBr2 the spin-orbit coupling is essentially important and that the orbital moment

A. V. Chaplik

The classical Hall effect in inhomogeneous systems is considered for the case of one-dimensional inhomogeneity. For a certain geometry of the problem and for the magnetic field linearly depending on the coordinate the density of current distribution corresponds to the skin-effect.

T. Rejec, A. Ramsak, J. H. Jefferson

We study the conductance threshold of clean nearly straight quantum wires in the magnetic field. As a quantitative example we solve exactly the scattering problem for two-electrons in a wire with planar geometry and a weak bulge. From the scattering matrix we determine conductance via the Landauer-Buettiker formalism. The conductance anomalies found near 0.2

J. R. Cooper

A empirical model is proposed for the observed variation of the London penetration depth of cuprate superconductors with applied magnetic field $H$ below the lower critical field H_c1. It is suggested that the Doppler shift of the quasi-particle energies near the d-wave nodes could cause pair-breaking and that this could be responsible for the non-linear Mei

Janos Pipek, Imre Varga, Etienne Hofstetter

Numerical and analytical details are presented on the newly discovered superscaling property of the energy spacing distribution in the three dimensional Anderson model.

Miyuki K. shimamura, Tetsuo Deguchi

We discuss the probability of random knotting for a model of self-avoiding polygons whose segments are given by cylinders of unit length with radius $r$. We show numerically that the characteristic length of random knotting is roughly approximated by an exponential function of the chain thickness $r$.

M. Alba, S. Pouget

The influence of a strong disorder on the critical dynamics of 3D Heisenberg ferromagnet was investigated by high-resolution quasielastic neutron scattering. A new disorder-induced dynamical critical behavior was found, characterized by its critical exponent z=2.3. The dynamical scaling function appeared mainly unaffected by disorder but its description led

Serkan Erdin, Valery L. Pokrovsky

We have found the complete spectrum and eigenstates for harmonic oscillations of ideal spherical and cylindrical shells, both being infinitely thin. The spectrum of the cylindrical shell has an infinite number of Goldstone modes corresponding to folding deformations. This infrared catostrophe is overcome by accounting for curvature-part of energy.

M. Y. Choi, Gun Sang Jeon, Mina Yoon

The boundary effects on the current-voltage characteristics in two-dimensional arrays of resistively shunted Josephson junctions are examined. In particular, we consider both the conventional boundary conditions (CBC) and the fluctuating twist boundary conditions (FTBC), and make comparison of the obtained results. It is observed that the CBC, which have bee

Ryszard Piasecki

In random systems consisting of grains with size distributions the transport properties are difficult to explore by network models. However, the concentration dependence of effective conductivity and its critical properties can be considered within coarsened lattice model proposed that takes into account information from experimentally known size histograms.

J. M. Montanero, A. Santos, V. Garzó

The Direct Simulation Monte Carlo method is applied to solve the Boltzmann equation in the steady planar Couette flow for Maxwell molecules and hard spheres. Nonequilibrium boundary conditions based on the solution of the Bhatnagar-Gross-Krook (BGK) model for the Couette flow are employed to diminish the influence of finite-size effects. Non-Newtonian proper

Andres Santos

A compressible flow characterized by a velocity field $u_x(x,t)=ax/(1+at)$ is analyzed by means of the Boltzmann equation and the Bhatnagar-Gross-Krook kinetic model. The sign of the control parameter (the longitudinal deformation rate $a$) distinguishes between an expansion ($a>0$) and a condensation ($a<0$) phenomenon. The temperature is a decreasing funct

Z. G. Dai

There is growing evidence that some long gamma-ray bursts (GRBs) arise from the core collapse of massive stars, and thus it is inevitable that the environments of these GRBs are preburst stellar winds or dense media. We studied, for the first time, the wind model for afterglows based on the Blandford-McKee self-similar solution of a relativistic shock, and s

Q. Daniel Wang

I review recent results from our deep ROSAT and Chandra observations of two galaxies, M101 and NGC 4631, in fields of exceptionally low Galactic extinction. Large amounts of X-ray-emitting gas are detected in these galaxies. Such gas is produced primarily in massive star forming regions and have an average characteristic temperature of a few times $10^6$ K.

Kenneth Wood, Scott Wolk, K. Z. Stanek, George Leussis

We report results of VRI photometric monitoring of the T Tauri star plus disk system HH30. We find that HH30 is highly variable over timescales of a few days with Delta V~1.5 mag, Delta I~1.1 mag. Furthermore we find hints of periodicity with periodograms indicating possible periods of 11.6 and 19.8 days. The VRI photometry is available through the anonymous

G. Torres, C. H. S. Lacy, A. Claret, J. A. Sabby

We present photometric observations in B and V as well as spectroscopic observations of the detached, eccentric 6.6-day double-lined eclipsing binary GG Ori, a member of the Orion OB1 association. Absolute dimensions of the components, which are virtually identical, are determined to high accuracy (better than 1% in the masses and better than 2% in the radii

Anderson Caproni, Zulema Abraham, Jose W. S. Vilas-Boas

The region centered in the NGC 6334 I(N) radio continuum source was surveyed in an extension of 6 arcmin in right ascension and 12 arcmin in declination, in the NH3(J,K) = (1,1) transition, using the Itapetinga radio telescope. The spectra show non-LTE behavior, and gradients of velocity and line-width were detected along the region. A detailed analysis of t

J. J. Blanco-Pillado, Ken D. Olum

Cusps in superconducting cosmic strings produce strongly beamed electromagnetic radiation. To calculate the energy emitted requires taking into account the effect of the charge carriers on the string motion, which has previously been done only heuristically. Here, we use the known exact solution to the equations of motion for the case where the current is ch

F. Eisenhauer, M. Tecza, S. Mengel, N. Thatte

We present SPIFFI, the integral field spectrometer for the VLT. This instrument allows simultaneous observation of infrared spectra in more than 1000 image points of a two dimensional field. With its set of four gratings and a pixel scale that can be varied by a factor of ten, SPIFFI provides high flexibility, and at the same time offers the unique possibili

I. Georgantopoulos, I. Papadakis

We present a series of RXTE observations of the nearby obscured Seyfert galaxies ESO103-G35, IC5063, NGC4507 and NGC7172. The period of monitoring ranges from seven days for NGC7172 up to about seven months for ESO103-G035. The spectra of all galaxies are well fit with a highly obscured (N_H>10^23 cm-2) power-law and an Fe line at 6.4 keV. We find strong evi

R. H. M. Voors, T. R. Geballe, L. B. F. M. Waters, F. Najarro

We report optical and near-infrared spectra of the central star of the radio source G79.29+0.46, a candidate luminous blue variable. The spectra contain numerous narrow (FWHM < 100 km/s emission lines of which the low-lying hydrogen lines are the strongest, and resemble spectra of other LBVc&#39;s and B[e] supergiants. A few prominent infrared lines are unid

C. Done, S. Nayakshin

Reflection of X-rays from cool material around a black hole is one of the few observational diagnostics of the accretion flow geometry. Models of this reflected spectrum generally assume that the accretion disk can be characterized by material in a single ionization state. However, several authors have recently stressed the importance of the classic ionizati

M. R. Merrifield, J. Gerssen, K. Kuijken

By making spectral absorption-line observations of disk galaxies at intermediate inclinations, we have been able to determine the amplitude of their constituent stars&#39; random motions in three dimensions. This full measure of the shape of the velocity ellipsoid is a useful diagnostic for determining the &#34;heating&#34; mechanism responsible for creating

Kenji Bekki, Yasihiro Shioya

We numerically investigate how fundamental properties of the spectral energy distribution (SED) of a major gas-rich galaxy merger with dusty starburst are determined by the initial orbital configuration of the merger. We found that an infrared luminous galaxy with dusty starburst formed by a nearly retrograde-retrograde merger suffers the most remarkable dus

S. Jeyakumar, D. J. Saikia, A. Pramesh Rao, V. Balasubramanian

We determine the small-scale structure for a large sample of Compact Steep Spectrum (CSS) and Gigahertz Peaked Spectrum (GPS) sources and a sample of larger radio sources at 327 MHz using the technique of Inter-Planetary Scintillation (IPS) with the Ooty Radio Telescope. Our observations provide structural information on angular scales ranging from about 50

C. J. A. P. Martins

I motivate and discuss some recent work on theories with varying constants, and consider some possible observational consequences and tests. Particular emphasis is given to models which can (almost) exactly mimic the predictions of standard inflationary models.

Myung Gyoon Lee

Supernovae play a critical role in observational cosmology as well as in astrophysics of stars and galaxies. Recent era has seen dramatic progress in the research of supernovae. Several programs to search systematically supernovae in nearby to distant galaxies have been very successful. Recent progresses in the modern supernova search are reviewed.

P. F. Bloser, T. Narita, J. A. Jenkins, J. E. Grindlay

We report on the construction and laboratory testing of pixellated CZT detectors mounted in a flip-chip, tiled fashion and read out by an ASIC, as required for proposed hard X-ray astronomy missions. Two 10 mm x 10 mm x 5 mm detectors were fabricated, one out of standard eV Products high-pressure Bridgman CZT and one out of IMARAD horizontal Bridgman CZT. Ea

C. C. Steidel, M. Pettini, K. L Adelberger

We report the detection of significant Lyman continuum flux in the composite spectrum of 29 Lyman break galaxies (LBGs) with redshifts <z> = 3.40+/-0.09. After correction for opacity due to intervening absorption using a new composite QSO spectrum evaluated at the same redshift, the ratio of emergent flux density at 1500 Åin the rest frame to that in the Lym

C. Alcock, R. A. Allsman, D. R. Alves, T. S. Axelrod

We attempt to determine whether the MACHO microlensing source stars are drawn from the average population of the LMC or from a population behind the LMC by examining the HST color-magnitude diagram (CMD) of microlensing source stars. We present WFPC2 HST photometry of eight MACHO microlensing source stars and the surrounding fields in the LMC. The microlensi

Lior M. Burko

We study the spacetime singularity in 2+1 dimensional AdS-scalar black hole with circular symmetry using a quasi-homogeneous model. We show that this is a spacelike, scalar curvature, deformationally strong singularity.

M. M. Mola, S. Hill, J. S. Brooks, J. S. Qualls

We report torque magnetization measurements in regions of the mixed state phase diagram (${\bf B}\simμ_o{\bf H}_{c2}$ and T$_c$/$10^3$) of the organic superconductor $κ-$(ET)$_2$Cu(NCS)$_2$ where quantum fluctuations are expected to dominate thermal effects. Over most of the field range below the irreversibility line (${\bf B}_{irr}$), magneto-thermal instab

Silviu Podariu, Peter Nugent, Bharat Ratra

We examine the constraints that satellite-acquired Type Ia and IIP supernova apparent magnitude versus redshift data will place on cosmological model parameters in models with and without a constant or time-variable cosmological constant $Λ$. High-quality data which could be acquired in the near future will result in tight constraints on these parameters. Fo

Nathan Berkovits

After reviewing the Green-Schwarz superstring using the approach of Siegel, the superstring is covariantly quantized by constructing a BRST operator from the fermionic constraints and a bosonic pure spinor ghost variable. Physical massless vertex operators are constructed and, for the first time, N-point tree amplitudes are computed in a manifestly ten-dimen

J. Pumplin, D. R. Stump, W. K. Tung

When a large body of data from diverse experiments is analyzed using a theoretical model with many parameters, the standard error matrix method and the general tools for evaluating errors may become inadequate. We present an iterative method that significantly improves the reliability of the error matrix calculation. To obtain even better estimates of the un

Ganpathy Murthy

Using the Hamiltonian formulation of Composite Fermions developed recently, the temperature dependence of the spin polarization is computed for the translationally invariant fractional quantum Hall states at $ν=1/3$ and $ν=2/5$ in two steps. In the first step, the effect of particle-hole excitations on the spin polarization is computed in a Composite Fermion

Avinash Dhar, Spenta R. Wadia

In this note we discuss local gauge-invariant operators in noncommutative gauge theories. Inspired by the connection of these theories with the Matrix model, we give a simple construction of a complete set of gauge-invariant operators. We make connection with the recent discussions of candidate operators which are dual to closed strings modes. We also discus

Todd A. Oliynyk, H. P. Kunzle

We prove local existence and uniqueness of static spherically symmetric solutions of the Einstein-Yang-Mills equations for an arbitrary compact semisimple gauge group in the so-called regular case. By this we mean the equations obtained when the rotation group acts on the principal bundle on which the Yang-Mills connection takes its values in a particularly

Cumrun Vafa

We embed the large N Chern-Simons/topological string duality in ordinary superstrings. This corresponds to a large $N$ duality between generalized gauge systems with N=1 supersymmetry in 4 dimensions and superstrings propagating on non-compact Calabi-Yau manifolds with certain fluxes turned on. We also show that in a particular limit of the N=1 gauge theory

A. B. Kuklov, Joseph L. Birman

We present an exact many body solution for the dynamics of the population difference $N_2-N_1$ induced by an rf-field in the two-component atomic cloud characterized by equal scattering lengths. This situation is very close to the actual JILA experiments with the two-component $^{87}$Rb vapor. We show that no intrinsic decoherence exists for $N_2-N_1$, provi

S. Willenbrock

The top quark, discovered at the Fermilab Tevatron collider in 1995, is the heaviest known elementary particle. Its large mass suggests that it may play a special role in nature. It behaves differently from the other known quarks due both to its large mass and its short lifetime. Thus far we have only crude measurements of the properties of the top quark, su

Y. Kinar, A. Loewy, E. Schreiber, J. Sonnenschein

We look at the string theory dual of the $\N=1^*$ theory, involving 5--branes, which was recently proposed by Polchinski and Strassler \cite{PolStr}. We argue that SUGRA alone is not enough in order to obtain the correct screening and confinement behaviour of the various massive field theory vacua, but that appropriate worldvolume phenomena of the 5--branes

S. Catani, D. de Florian, M. Grazzini

We consider the resummation of the logarithmic contributions to the region of small transverse momenta in the distributions of high-mass systems (lepton pairs, vector bosons, Higgs particles, ....) produced in hadron collisions. We point out that the resummation formulae that are usually used to compute the distributions in perturbative QCD involve process-d

I. F. Riad, M. M. Sheikh-Jabbari

We study QED on noncommutative spaces, NCQED. In particular we present the detailed calculation for the noncommutative electron-photon vertex and show that the Ward identity is satisfied. We discuss that in the noncommutative case moving electron will show {\it electric} dipole effects. In addition, we work out the electric and magnetic dipole moments up to

M. Th. Keil, G. Penner, U. Mosel

Using a previously established effective Lagrangian model we describe anti-kaon induced reactions on the nucleon. The dominantly contributing channels in the cm-energy region from threshold up to 1.72 GeV are included (K N, πΣ, πΛ). We solve the Bethe-Salpeter equation in an unitary $K$-matrix approximation.

S. F. King, M. Oliveira

We study Yukawa unification, including the effects of a physical neutrino mass consistent with the Superkamiokande observations, in a string/$D$-brane inspired Pati-Salam model which allows the most general non-universal scalar and gaugino masses, including the usual $D$-term contributions which arise in SO(10). We investigate how the tight constraints from

J. D. Offenberg, D. J. Fixsen, B. J. Rauscher, W. J. Forrest

We examine cosmic ray rejection methodology on data collected from InSb and Si:As detectors. The application of an Up-the-Ramp sampling technique with cosmic ray identification and mitigation is the focus of this study. This technique is valuable for space-based observatories which are exposed to high-radiation environments. We validate the Up-the-Ramp appro

Tomas Bohr, Martin van Hecke, Rene&#39; Mikkelsen, Mads Ipsen

In this Letter we show that the transition from laminar to active behavior in extended chaotic systems can vary from a continuous transition in the universality class of Directed Percolation with infinitely many absorbing states to what appears as a first order transition. The latter occurs when {\em finite} lifetime non-chaotic structures, called ``solitons