April 2000 arXiv papers — page 11

Raffaele Cafiero, Guido Caldarelli, Andrea Gabrielli

We present a detailed study of a two-dimensional minimal lattice model for the description of mud cracking in the limit of extremely thin layers. In this model each bond of the lattice is assigned to a (quenched) breaking threshold. Fractures proceed through the selection of the part of the material with the smallest breaking threshold. A local damaging rule

S. Moukouri, C. Huscroft, M. Jarrell

We present the algorithmic details of the dynamical cluster approximation (DCA) algorithm. The DCA is a fully-causal approach which systematically restores non-local correlations to the dynamical mean field approximation (DMFA). The DCA is in the thermodynamic limit and becomes exact for an infinite cluster size, while reducing to the DMFA for a cluster size

Masaki Nomura, Toshio Aoyagi

We study a simple extended model of oscillator neural networks capable of storing sparsely coded phase patterns, in which information is encoded both in the mean firing rate and in the timing of spikes. Applying the methods of statistical neurodynamics to our model, we theoretically investigate the model's associative memory capability by evaluating its

Oded Farago, Yacov Kantor

A new formalism is used for a Monte Carlo determination of the elastic constants of a two-dimensional net of fixed connectivity. The net is composed of point-like atoms each of which is tethered to six neighbors by a bond limiting the distance between them to a certain maximal separation, but having zero energy at all smaller lengths. We measure the elastic

W. Westerburg, O. Lang, C. Felser, W. Tremel

We suceeded in the preparation of polycrystalline Ca_2FeReO_6 which has a Curie temperature of 540 K, the highest value of all magnetic perovskites investigated up to now. This material has been characterised by X-ray and neutron powder diffraction. We found at 548 K a monoclinic unit cell (space group P2_1/n) with a=5.4366(5) A, b=5.5393(5) A, c=7.7344(5) A

M. Tsaousidou, P. N. Butcher, P. A. Crump, R. J. Hyndman

We explain for the first time thermopower data for p-type GaAs/AlGaAs layers. The data span a temperature range between 0.2 to 1.2K. We calculate both the diffusion $S^{d}$ and the phonon-drag $S^{g}$ contributions to the thermopower. We find that $S^{d}$ is significant for temperatures up to 0.3K while at higher temperatures $S^{g}$ dominates. The calculate

Annick Lesne, Jean-Marc Victor

Conformational transitions of a single macromolecule of finite size $N$ cannot be described within standard thermodynamic framework. Taking as a basis a simple model of homopolymer exhibiting a coil-globule transition, we show that a relevant approach is to describe the thermal equilibrium distribution $P_N^{(β)}(t)$ of some variable $t$ characterizing the c

N. Vandewalle, S. Galam, M. Kramer

Percolation and jamming phenomena are investigated for random sequential deposition of rectangular needles on $d=2$ square lattices. Associated thresholds $p_c^{perc}$ and $p_c^{jam}$ are determined for various needle sizes. Their ratios $p_c^{perc} / p_c^{jam}$ are found to be a constant $0.62 \pm 0.01$ for all sizes. In addition the ratio of jamming thresh

G. H. F. van Raaij, K. J. H. van Bemmel, T. Janssen

Ground state properties and phonon dispersion curves of a classical linear chain model describing a crystal with an incommensurate phase are studied. This model is the DIFFOUR (discrete frustrated phi4) model with an extra fourth-order term added to it. The incommensurability in these models may arise if there is frustration between nearest-neighbor and next

Sher Alam, M. O. Rahman, M. Ando, S. B. Mohamed

Following our recent conjecture to model the phenomenona of antiferromagnetism and superconductivity by quantum symmetry groups, we discuss in the present note the choice of the classical symmetry group underlying the quantum group. Keeping in mind the degrees of freedom arising from spin, charge, and lattice we choose the classical group as SO(7). This choi

D. H. E. Gross

Non-extensive systems do not allow to go to the thermodynamic limit. Therefore we have to reformulate statistical mechanics without invoking the thermodynamical limit. I.e. we have to go back to Pre-Gibbsian times. We show that Boltzmann's mechanical definition of entropy S as function of the conserved ``extensive'' variables energy E, particle n

V. I. Yukalov, E. P. Yukalova

The problem of creating well-collimated beams of atoms escaping from a trap is studied. This problem is of high importance for the realization of atom lasers. Nonadiabatic dynamics of neutral atoms in nonuniform magnetic fields, typical of quadrupole magnetic traps, has been considered. The main result of this report is that an unusual semiconfining regime o

V. I. Yukalov, E. P. Yukalova, V. S. Bagnato

A method of exciting coherent spatial modes of Bose-condensed trapped atoms is considered. The method is based on the resonance modulation of the trapping potential. The population dynamics of coherent modes is analysed. The method makes it possible to create mixtures of different spatial modes in arbitrary proportions, including the formation of pure excite

M. Guerrero, R. M. Noack

Using the Density Matrix Renormalization Group, we study metallic ferromagnetism in a one-dimensional copper-oxide model which contains one oxygen p-orbital and one copper d-orbital. The parameters for the d-p model can be chosen so that it is similar to the one-dimensional periodic Anderson model. For these parameters, we compare the ground-state phase diag

D. B. Saakian

It is possible to formulate 2d field theory on the ultrametric space with the free correlators identical to 2d correlators and the same potential. Such model should carry some features of original model for scale invariant theories. For the case of strings and 2d conformal models it is possible to derive exact results. It is possible to investigate not only

Sahng-Kyoon Yoo, Soo-Young Lee

The oscillation of tunnel splitting are obtained by geometrical analysis of the topological Wess-Zumino phase on the basis of tunneling paths in biaxial nanomagnetic particles with magnetic field along the hard anisotropy axis. This theory not only just yields the previous quantum interference results for the ground state tunneling, but also gives the excite

Tal Alexander, Pawan Kumar

We show that main-sequence stars in dense stellar cusps around massive black holes are likely to rotate at a significant fraction of the centrifugal breakup velocity due to spin-up by hyperbolic tidal encounters. We use realistic stellar structure models to calculate analytically the tidal spin-up in soft encounters, and extrapolate these results to close an

Adam J. Burgasser, John C. Wilson, J. Davy Kirkpatrick, Michael F. Skrutskie

We report the discovery of a bright (J = 13.83$\pm$0.03) methane brown dwarf, or T dwarf, by the Two Micron All Sky Survey. This object, 2MASSI J0559191-140448, is the first brown dwarf identified by the newly commissioned CorMASS instrument mounted on the Palomar 60-inch Telescope. Near-infrared spectra from 0.9 - 2.35 $\micron$ show characteristic CH$_4$ b

Luis P. Chimento, Alejandro S. Jakubi

We have found exact constant solutions for the cosmological density parameter using a generalization of general relativity that incorporates a cosmic time-variation of the velocity of light in vacuum and the Newtonian gravitation constant. We have determined the conditions when these solutions are attractors for an expanding universe and solved the problems

Penny D. Sackett

The simple physics of microlensing provides a well-understood tool with which to probe the atmospheres of distant stars in the Galaxy and Local Group with high magnification and resolution. Recent results in measuring stellar surface structure through broad band photometry and spectroscopy of high amplification microlensing events are reviewed, with emphasis

Wei Cui, C. R. Shrader, C. A. Haswell, R. I. Hynes

We report the discovery of quasi-periodic oscillations (QPOs) at roughly 187 Hz and 150 Hz in the X-ray intensity of X-ray nova XTE J1859+226. The source was observed during a recent outburst with RXTE. Besides these high-frequency QPOs, we have also detected QPOs (and sometimes their harmonics) at 6--7 Hz, and significant broad-band variability at low frequ

N. A. Webb, T. Naylor, Z. Ioannou, P. A. Charles

We present 53 simultaneous photometric (I band) and spectroscopic (6900-9500 Angstroms) observations of J0422+32, taken during December 1997. From these we determine that J0422+32 was in its lowest state yet observed, at I=20.44+/-0.08. Using relative spectrophotometry, we show that it is possible to correct very accurately for telluric absorption. Following

Shmuel Balberg, Luca Zampieri, Stuart L. Shapiro

If a black hole formed in a core-collapse supernova is accreting material from the base of the envelope, the accretion luminosity could be observable in the supernova light curve. Here we continue the study of matter fall back onto a black hole in the wake of a supernova and examine realistic supernovae models which allow for an early emergence of the accret

T. Antoni

Measurements of electron, muon, and hadron lateral distributions of extensive air showers as recorded by the KASCADE experiment are presented. The data cover the energy range from about 5x10^14 eV up to almost 10^17 eV and extend from the inner core region to distances of 200 m. The electron and muon distributions are corrected for mutual contaminations by t

Peter M. Woods, Chryssa Kouveliotou, Jan van Paradijs, Thomas M. Koshut

The hard X-ray bursts observed during both major outbursts of the Bursting Pulsar (GRO J1744-28) show pulsations near the neutron star spin frequency with an enhanced amplitude relative to that of the persistent emission. Consistent with previous work, we find that the pulsations within bursts lag behind their expected arrival times based upon the persistent

M. Rejkuba, D. Minniti, M. D. Gregg, A. A. Zijlstra

We have obtained V and I-band photometry for 1886 stars down to I=27 and V=28 in the field of the dwarf irregular galaxy WLM, using deep STIS CL and LP-band images taken in the parallel mode with the Hubble Space Telescope. The photometry is used to study the horizontal branch identified in WLM. The horizontal branch, extending blueward from the red giant cl

Roger Coziol, Angela Iovino, Reinaldo R. de Carvalho

We present the results of the classification of spectral activity types for 193 galaxies from a new sample of 49 compact groups of galaxies in the southern hemisphere (SCGs). This sample was selected in automated fashion from a digitized galaxy catalogue, covering an area of ~5200 sq deg, around the South Galactic Pole. It is complete up to m ~14.5 in b_j fo

M. Scodeggio, D. Silva

The publicly available EIS-DEEP optical-NIR data for the AXAF (Chandra) Deep Field have been used to construct samples of Extremely Red Objects (EROs) using various single-band and multi-band color criteria. In this work we define as EROs objects with colors consistent with passively evolving elliptical galaxies at z $\geq$ 1. The EROs surface densities we d

M. J. Hardcastle

A number of authors have reported filaments connecting bright structures in high-resolution X-ray images, and in some cases these have been taken as evidence for a physical connection between the structures, which might be thought to provide support for a model with non-cosmological redshifts. In this paper I point out two problems which are inherent in the

N. E. Mavromatos

I discuss some theoretical ideas concerning the representation of quantum gravity as a Lorentz-symmetry-violating `medium' with non-trivial optical properties, which include a refractive index in `vacuo' and stochastic effects associated with a spread in the arrival times of photons, growing linearly with the photon energy. Some of these properties m

P. Vaisanen, E. V. Tollestrup, S. P. Willner, M. Cohen

New near-infrared galaxy counts in the J and K bands are presented over a total area of 0.70 and 0.97 degrees^2, respectively. The limiting magnitudes of the deepest regions are 19.5 in J and 18.0 in K. At J>16 and K>15 our J and K-band counts number counts agree well with existing surveys provided all data are corrected to a common magnitude scale. There ar

G. V. Rudenko

This paper is concerned with the Laplace boundary-value problem with the directional derivative, corresponding to the specific nature of measurements of the longitudinal component of the photospheric magnetic field. Boundary conditions are specified by a distribution on the sphere of projection of the magnetic field vector unto a given direction. It is shown

Naoyuki Tamura, Kouji Ohta

Color gradients in elliptical galaxies in distant clusters ($z=0.37-0.56$) are examined by using the archival deep imaging data of Wide Field Planetary Camera 2 (WFPC2) on-board the Hubble Space Telescope (HST). Obtained color gradients are compared with the two model gradients to examine the origin of the color gradients. In one model, a color gradient is a

M. Honma

In order to search for new VLBI sources in the Galactic plane that can be used as phase reference sources in differential VLBI, we have conducted 22 GHz observations of radio sources in the Galactic plane using the Japanese VLBI Network (J-Net). We have observed 267 VLBI source candidates selected from existing radio surveys and have detected 93 sources at t

Cristina Chiappini, Francesca Matteucci

In this work we present the predictions of a modified version of the ``two-infall model'' (Chiappini et al. 1997) for the evolution of 3He, 4He and D in the solar vicinity, as well as their distributions along the Galactic disk. In particular, we show that when allowing for extra-mixing process in low mass stars, as predicted by Charbonnel and do Nas

K. Nomoto, P. A. Mazzali, T. Nakamura, K. Iwamoto

We discuss the properties of the hyper-energetic Type Ic supernovae (SNe Ic) 1998bw and 1997ef and Type IIn supernova (SN IIn) 1997cy. SNe Ic 1998bw and 1997ef are characterized by their large luminosity and the very broad spectral features. Their observed properties can be explained if they are very energetic SN explosions with the kinetic energy of $E_{\rm

PACS Collaboration, A. Ali Khan, S. Aoki, G. Boyd

We present results for light quark masses from a systematic lattice QCD study with two degenerate flavors of dynamical quarks. Simulations are made with a renormalization-group improved gauge action and a mean-field improved clover quark action for sea quark masses corresponding to $m_{\rm PS}/m_{\rm V} \approx 0.8$--0.6 and the lattice spacing $a=0.22$--0.1

P. Desgrolard, M. Giffon, E. Martynov

The modified additive quark model, proposed recently, allows to improve agreement of the standard additive quark model with the data on the $pp, \bar pp, π^{\pm} p, γp$ and $γγ$ total cross-sections, as well as on the ratios of real to imaginary part of $pp$ and $\bar pp$ amplitudes at $t=0$. Here, we extend this model to non forward elastic scattering of pr

Alex Chigogidze

It is well-known that every commutative separable unital C*-algebra of real rank zero is a quotient of the C*-algebra of all compex continous functions defined on the Cantor cube. We prove a non-commutative version of this result by showing that the class of all separable unital C*-algebras of real rank zero concides with the class of quotients of a certain

Feng Xu

We construct unitary modular categories for a general class of coset conformal field theories based on our previous study of these theories in the algebraic quantum field theory framework using subfactor theory. We also consider the calculations of the corresponding 3-manifold invariants. It is shown that under certain index conditions the link invaraints co

Feng Xu

We prove a conjecture about mininmal index of certain representations of Coset Algebraic Conformal Field Theories under general conditions as formulated previously by us. As a by-product, the Kac-Wakimoto Conjecture (KWC) which is related to the asympotics of the coset characters is true under the same conditions. The same idea in the proof also proves a rec

W. F. Chen

We manifestly verify that the miraculous cancellation of the infrared divergence of the topologically massive Yang-Mills theory in the Landau gauge is completely determined by a new vector symmetry existing in its large topological mass limit, the Chern-Simons theory. Furthermore, we show that the cancellation theorem proposed by Pisarski and Rao is an inevi

R. D. Peccei

I discuss a number of the highlights in theory presented at the BCP3 conference. These included new, and more stringent, CKM fits; a critical overview of heavy hadron lifetimes; progress in computing rates and CP-asymmetries in charmless B-decays; a thorough discussion of the implications of the new results on $ε^{\prime}/ε$; and, finally, a peek at the futu

Susumu Koretune

Using the soft pion theorem in the inclusive reactions, we estimate the soft pion contribution to the structure functions $F_2$ and $g_1$ in the nucleon, and show that it is an indispensable part in these structure functions in the small $x$ region. This contribution is asymmetric for the soft $π^+$ and $π^-$ due to pole terms in the soft pion limit, hence i

Alvaro Montero

We study by numerical methods a particular kind of SU(N) Yang-Mills solutions of the Euclidean equations of motion which appear on the torus when twisted boundary conditions are imposed. These are instanton-like configurations with the peculiarity of having fractional topological charge. We focus on those solutions with minimal non-trivial action $S=8π^2/\N$

Thomas W. Baumgarte

We introduce a new method to construct solutions to the constraint equations of general relativity describing binary black holes in quasicircular orbit. Black hole pairs with arbitrary momenta can be constructed with a simple method recently suggested by Brandt and Bruegmann, and quasicircular orbits can then be found by locating a minimum in the binding ene

G. E. Volovik

We consider the Landau-Khalatnikov two-fluid hydrodynamics of superfluid liquid as an effective theory, which provides a self-consistent analog of Einstein equations for gravity and matter.

Ke Xu, Wei Li

In this paper we propose a new type of random CSP model, called Model RB, which is a revision to the standard Model B. It is proved that phase transitions from a region where almost all problems are satisfiable to a region where almost all problems are unsatisfiable do exist for Model RB as the number of variables approaches infinity. Moreover, the critical

M. R. Baldan, E. Granato, S. C. Ying

Using Brownian molecular dynamics simulation, we study the surface dynamics near the reconstruction transition of W(100) via a model Hamiltonian. Results for the softening and broadening of the surface phonon spectrum near the transition are compared with previous calculations and with He atom scattering data. From the critical behavior of the central peak i

E. T. Seppala, M. J. Alava, P. M. Duxbury

We analyze, in both (1+1)- and (2+1)- dimensions, a periodic elastic medium in which the periodicity is such that at long distances the behavior is always in the random-substrate universality class. This contrasts with the models with an additive periodic potential in which, according to the field theoretic analysis of Bouchaud and Georges and more recently

Shin Miyahara, Kazuo Ueda

Effects of the inter-layer couplings for the orthogonal dimer system SrCu$_2$(BO$_3$)$_2$ are discussed. The spin-gap $Δ$ of the three-dimensional model is independent of the inter-layer couplings when they are small. Therefore at low temperatures ($T < Δ$) thermodynamic properties are described well by the two-dimensional model. On the other hand at high te

N. Kumada, A. Sawada, Z. F. Ezawa, S. Nagahama

By tilting the samples in the magnetic field, we measured and compared the Skyrmion excitations in the bilayer quantum Hall (QH) state at the Landau-level filling factor $ν=2$ and in the monolayer QH state at $ν=1$. The observed number of flipped spins is $N_s=14$ in the bilayer system with a large tunneling gap, and $N_s=7$ in the bilayer system with a smal

Gregory M. Braverman

Magnetic properties of layered high temperature superconductors with a weak interlayer coupling in the region of the critical fluctuations are investigated in the framework of the Ginzburg--Landau approach. The sample magnetization is calculated within a perturbative approach to the second order in the interlayer coupling constant. The first order correction

D. J. Pisano, Eric M. Wilcots, Bruce G. Elmegreen

We present the results from an optical study of the stellar & star formation properties of NGC 925 using the WIYN 3.5m telescope. Images in B,V,R, & H-alpha reveal a galaxy that is fraught with asymmetries. From isophote fits we discover that the bar center is not coincident with the center of the outer isophotes nor with the dynamical center (from Pisano et

E. F. Tedesco, K. Muinonen, S. D. Price

We demonstrate the efficiency and effectiveness of using a satellite-based sensor with visual and infrared focal plane arrays to search for NEAs with orbits largely interior to the Earth&#39;s orbit. Such a space-based system could detect approximately 97% of the Atens and 64% of the, as yet hypothetical, objects with orbits entirely Interior to Earth&#39;s

V. S. Beskin, I. V. Kuznetsova

The most general form of the nonrelativistic Grad-Shafranov equation describing anisotropic pressure effects is formulated within the double adiabatic approximation. It gives a possibility to analyze quantitatively how the anisotropic pressure affects the 2D structure of the ideal magnetohydrodynamical flows.

Julia Kempe, Dave Bacon, Daniel A. Lidar, K. Birgitta Whaley

Universal quantum computation on decoherence-free subspaces and subsystems (DFSs) is examined with particular emphasis on using only physically relevant interactions. A necessary and sufficient condition for the existence of decoherence-free (noiseless) subsystems in the Markovian regime is derived here for the first time. A stabilizer formalism for DFSs is

D. A. Demir, Ernest Ma

We propose a new axionic solution of the strong CP problem with a Peccei-Quinn mechanism using the gluino rather than quarks. The spontaneous breaking of this new global U(1) at 10^{11} GeV also generates the supersymmetry breaking scale of 1 TeV (solving the so-called \mu problem at the same time) and results in the MSSM (Minimal Supersymmetric Standard Mod

Joaquim Gomis, Karl Landsteiner, Esperanza Lopez

We study a non-commutative non-relativistic scalar field theory in 2+1 dimensions. The theory shows the UV/IR mixing typical of QFT on non-commutative spaces. The one-loop correction to the two-point function turns out to be given by a delta-function in momentum space. The one-loop correction to the four-point function is of logarithmic type. We also evaluat

R. Walser, J. Cooper, M. Holland

We have formulated a kinetic theory for a condensed atomic gas in a trap, i.e., a generalized Gross-Pitaevskii equation, as well as a quantum-Boltzmann equation for the normal and anomalous fluctuations [R. Walser et al., Phys. Rev. A, 59, 3878 (1999)]. In this article, the theory is applied to the case of an isotropic configuration and we present numerical

A. Ceresole, G. Dall&#39;Agata

We give the full lagrangean and supersymmetry transformation rules for D=5, N=2 supergravity interacting with an arbitrary number of vector, tensor and hyper-multiplets, with gauging of the R-symmetry group SU(2)_R as well as a subgroup K of the isometries of the scalar manifold. Among the many possible applications, this theory provides the setting where a

Wilfried Buchmuller, Stefan Fredenhagen

The cosmological baryon asymmetry can be explained as remnant of heavy Majorana neutrino decays in the early universe. We study this out-of-equilibrium process by means of Kadanoff-Baym equations which are solved in a perturbative expansion. To leading order the problem is reduced to solving a set of Boltzmann equations for distribution functions.

Travis Brooks, Lance Dixon

At very high energy and wide angles, Compton scattering on the proton (gamma p -> gamma p) is described by perturbative QCD. The perturbative QCD calculation has been performed several times previously, at leading twist and at leading order in alpha_s, with mutually inconsistent results, even when the same light-cone distribution amplitudes have been employe

C. M. Zhang, A. Beesham

The interference phase of the high energy mass neutrinos and the low energy thermal neutrons in a gravitational field are studied. For the mass neutrinos, we obtain that the phase calculated along the null is equivalent to the half phase along the geodesic in the high energy limit, which means that the correct relative phase of the mass neutrinos is either t

B. G. Sidharth

We argue, that from a background pre space-time Zero Point Field, physical space-time emerges on averaging over unphysical Compton scales.

Manuel González, Joaquín M. Gutiérrez

We show that, in some cases, the projective and the injective tensor products of two Banach spaces do not have the Dunford-Pettis property (DPP). As a consequence, we obtain that $(c_0\hat{\otimes}_πc_0)^{**}$ fails the DPP. Since $(c_0\hat{\otimes}_πc_0)^{*}$ does enjoy it, this provides a new space with the DPP whose dual fails to have it. We also prove th

Vladimir P. Gerdt

In this paper the relation between Pommaret and Janet bases of polynomial ideals is studied. It is proved that if an ideal has a finite Pommaret basis then the latter is a minimal Janet basis. An improved version of the related algorithm for computation of Janet bases, initially designed by Zharkov, is described. For an ideal with a finite Pommaret basis, th

Thang T. Q. Le

We consider quantum invariants of 3-manifolds associated with arbitrary simple Lie algebras. Using the symmetry principle we show how to decompose the quantum invariant as the product of two invariants, one of them is the invariant corresponding to the projective group. We then show that the projective quantum invariant is always an algebraic integer, if the

Wladyslaw Marcinek

An algebraic formalism for the study of interacting particle systems is developed. Particle processes are described in terms of the category theory. The problem for the unique description of these processes is discussed. Categories relevant for this subject are described. The concept of generalized transmutations of interacting particle systems is considered

Leonardo Gualtieri

In this thesis I review various aspects of the AdS_4/CFT_3 correspondence, where AdS_4 supergravity arises from compactification of M-theory on a coset space G/H and preserves N<8 supersymmetries. One focal point of my review is that the complete spectrum of such N-extended supergravity can be determined by means of harmonic analysis on the homogeneous space

D. U. Matrasulov, M. M. Musakhanov, T. Morii

Baryons containing two heavy quarks are treated in the Born-Oppenheimer approximation. Schrödinger equation for two center Coulomb plus harmonic oscillator potential is solved by the method of ethalon equation at large intercenter separations. Asymptotical expansions for energy term and wave function are obtained in the analytical form. Using those formulas,

Markus H. Thoma

The application of generalized Kramers-Kronig relations, the so-called Leontovich relations, to thermal field theory is discussed. Medium effects contained in the full, thermal propagators can easily be taken into account by this method. As examples the collisional energy loss of a charged particle in a relativistic plasma and the radiation of energetic phot

BingAn Li

A relativistic quark model and a new set of wave functions of nucleon and Delta have been used to study the electromagnetic propertities of (1/2)^+ baryons and photoelectric production of Delta(1236).

CDF Collaboration, T. Affolder

This Letter describes a direct measurement of the $W$ boson total decay width, $\gw$, using the Collider Detector at Fermilab. The measurement uses an integrated luminosity of $90\invpb$, collected during the 1994--1995 run of the Fermilab Tevatron $p\pbar$ collider. The width is determined by normalizing predicted signal and background distributions to 4984

M. D. Glinchuk, E. A. Eliseev, V. A. Stephanovich, M. G. Karkut

A thermodynamic theory of ferroelectric thin film multilayers is developed. The free energy function is written down using a multilayer model in which c-domain layers of one ferroelectric material alternate with a-domain layers of a second ferroelectric material. We assume that the interfaces are perfectly sharp and that the polarization at these boundaries

J. K. Viljas

This Master&#39;s Thesis presents some new quasiclassical calculations of the Josephson pi state in 3He-B weak links.

Cong Xu

A local luminosity function at 15$μm$ is derived using the bivariate (15$μm$ vs. 60$μm$ luminosity) method, based on the newly published ISOCAM LW3-band (15$μm$) survey of the very deep IRAS 60$μm$ sample in the north ecliptic pole region (NEPR). New IRAS 60$μm$ fluxes are obtained using the SCANPI/SUPERSCANPI software at the new ISOCAM positions of the sour

Gregory J. Sobczak, Ronald A. Remillard, Michael P. Muno, Jeffrey E. McClintock

For all 209 RXTE observations of the 7-Crab X-ray nova XTE J1550-564, we analyzed the X-ray power spectra, phase lags, and coherence functions. These observations cover the entire 250 day outburst cycle of the source and are the most complete and arguably the richest data set for any black hole X-ray nova. We find that there are three fundamental types of QP

F. Leeuwin, E. Athanassoula

We use numerical simulations to investigate the cusp at the centre of elliptical galaxies, due to the slow growth of a super-massive black hole. We study this problem for axisymmetric models of galaxies, with or without rotation. The numerical simulations are based on the `Perturbation Particles&#39; method, and use GRAPEs to compute the force due to the cus

S. Cristiani, I. Appenzeller, S. Arnouts, M. Nonino

We report on low-resolution multi-object spectroscopy of 30 faint targets (R \~ 24-25) in the HDF-S and AXAF deep field obtained with the VLT Focal Reducer/low dispersion Spectrograph (FORS1). Eight high-redshift galaxies with 2.75< z < 4 have been identified. The spectroscopic redshifts are in good agreement with the photometric ones with a dispersion $σ_z

V. Elias, F. A. Chishtie, T. G. Steele

Asymptotic Pade-approximant methods are utilized to estimate the order $α_s^5$ contribution to the $H\to gg$ rate and the order $α_s^4$ contribution to the $H \to b \bar{b}$ rate. The former process is of particular interest because of the slow convergence evident from the three known terms of its QCD series, which begins with an order $α_s^2$ leading-order

Palle E. T. Jorgensen

Orthogonal wavelets, or wavelet frames, for L^2(R) are associated with quadrature mirror filters (QMF). The latter constitute a set of complex numbers which relate the dyadic scaling of functions on R to the Z-translates, and which satisfy the QMF-axioms. In this paper, we show that generically, the data in the QMF-systems of wavelets is minimal, in the sens

C. M. Zhang, A. Beesham

On the mass neutrino phase calculations along both the particle geodesic line and the photon null line, there exists a double counting error--factor of 2 when comparing the geodesic phase with the null phase. For the mass neutrino propagation in the flat spacetime, we study the neutrino interference phase calculation in the Minkowski diagram and find that th

Heather E. Logan, Ulrich Nierste

We compute the branching fractions of B_{s,d} -> l+ l- in the type-II two-Higgs-doublet model with large tan(beta). We find that the parameters of the neutral Higgs sector of the two-Higgs-doublet model cancel in the result, so that the branching fractions depend only on the charged Higgs mass and tan(beta). For large values of tan(beta) and a charged Higgs

V. Korepin, P. Zinn-Justin

We address the question of the dependence of the bulk free energy on boundary conditions for the six vertex model. Here we compare the bulk free energy for periodic and domain wall boundary conditions. Using a determinant representation for the partition function with domain wall boundary conditions, we derive Toda differential equations and solve them asymp

M. Zyskin

It was suggested in hep-th/0002106, that semiclassically, a partition function of a string theory in the 5 dimensional constant negative curvature space with a boundary condition at the absolute satisfy the loop equation with respect to varying the boundary condition, and thus the partition function of the string gives the expectation value of a Wilson loop

Sonja Kabana

Consequences resulting from the D Dbar excess derived indirectly by the NA50 experiment in S+U and Pb+Pb collisions at sqrt(s)=19, 17 GeV, relevant for the identification of the QCD phase transition in these collisions, are discussed. The dependence of open and closed charm yields in Pb+Pb collisions on the number of participating nucleons (N) indicates non

T. Ekedahl, S. Lando, M. Shapiro, A. Vainshtein

This article is an extended version of preprint math.AG/9902104. We find an explicit formula for the number of topologically different ramified coverings of a sphere by a genus g surface with only one complicated branching point in terms of Hodge integrals over the moduli space of genus g curves with marked points.

H. B. Nielsen, Y. Takanishi

We have investigated a neutrino mass matrix model without supersymmetry including three see-saw right-handed neutrinos around order $10^{12}$ GeV masses, aiming at a picture with all small numbers explained as being due to approximately conserved gauge charges. The prediction of the solar neutrino mixing angle is given by $\sin^22θ_{\odot}= 3 {+3\atop -2}\ti

Pieter-Jan De Smet, Joris Raeymaekers

We study the tachyon potential in the NS sector of Witten&#39;s cubic superstring field theory. In this theory, the pure tachyon contribution to the potential has no minimum. We find that this remains the case when higher modes up to level two are included.

Jessica L. Rosenberg, Stephen E. Schneider

The Arecibo Dual-Beam Survey is a &#34;blind&#34; 21 cm search for galaxies covering \~430 deg^2 of sky. We present the data from the detection survey as well as from the follow-up observations to confirm detections and improve positions and flux measurements. We find 265 galaxies, many of which are extremely low surface brightness. Some of these previously

I. Safi, P. Devillard, T. Martin

A microscopic theory of current partition in fractional quantum Hall liquids, described by chiral Luttinger liquids, is developed to compute the noise correlations, using the Keldysh technique. In this Hanbury-Brown and Twiss geometry, at Laughlin filling factor ν=1/3, the real time noise correlator exhibits oscillations which persist over larger time scales

A. Barroso, L. Brucher, R. Santos

Using the on-shell scheme and the general linear R_xi gauge we have calculated the one-loop amplitude W+ -> u_I d_j. In agreement with previous work we have shown that the Cabibbo-Kobayashi-Maskawa (CKM) matrix ought to be renormalized. We show how to renormalize the CKM matrix and, at the same time, obtain a gauge independent W decay amplitude.

Jaume Garriga, Oriol Pujolas, Takahiro Tanaka

We show that in brane-world scenarios with warped extra dimensions, the Casimir force due to bulk matter fields may be sufficient to stabilize the radion field $ϕ$. In particular, we calculate one loop effective potential for $ϕ$ induced by bulk gravitons and other possible massless bulk fields in the Randall-Sundrum background. This potential has a local ex

Yuki Yamamoto

We study a similarity transformation to construct an effective Hamiltonian systematically, which does not contain particle-number-changing interactions, by means of Fukuda-Sawada-Taketani-Okubo&#39;s method. We show that such Hamiltonian can be constructed from Feynman diagrams and give rules for constructing it in the Light-Front Yukawa model. We prove that

Ludwik Dabrowski, Cesare Reina, Alessandro Zampa

It is shown that when q is a primitive root of unity of order not equal to 2 mod 4, A(SL_q(2)) is a free module of finite rank over the coordinate ring of the classical group SL(2). An explicit set of generators is provided.

Betti Hartmann, Burkhard Kleihaus, Jutta Kunz

We construct axially symmetric dyons in SU(2) Yang-Mills-Higgs theory. In the Prasad-Sommerfield limit, they are obtained via scaling relations from axially symmetric multimonopole solutions. For finite Higgs self-coupling they are constructed numerically.

Pil Hun Song

The emergence of quantum chaos for interacting Fermi systems is investigated by numerical calculation of the level spacing distribution $P(s)$ as function of interaction strength $U$ and the excitation energy $ε$ above the Fermi level. As $U$ increases, $P(s)$ undergoes a transition from Poissonian (nonchaotic) to Wigner-Dyson (chaotic) statistics and the tr

Roberto De Pietri, Carlo Petronio

The problem of constructing a quantum theory of gravity has been tackled with very different strategies, most of which relying on the interplay between ideas from physics and from advanced mathematics. On the mathematical side, a central role is played by combinatorial topology, often used to recover the space-time manifold from the other structures involved

Feng Yuan

The predicted radio flux for nearby ellipticals by the canonical ADAF(advection-dominated accretion flow) model is well above the observations. If the mass accretion rate favored by the numerical simulation were adopted, the ADAF model would also significantly overpredict the radio flux of Sgr A*. On the observational side, strong evidence for the existence