June 2000 arXiv papers — page 4

Vladimir Kolevzon

Spontaneous spreading of a polymer drop on a solid substrate can be forced by a low pressure gaseous discharge applied between the cathode that supports the drop and a remote electrode. We prone to think that the driving force for this plasma driven spreading is the spatial distribution of the electric field at the cathode. Two distinct effects caused by the

Toshiya Hikihara

The ground-state phase transitions of a frustrated S=1 Heisenberg chain with the uniaxial single-ion-type anisotropy and the frustrating next-nearest-neighbor coupling are studied. For the system, it has been shown that there are gapless and gapped chiral phases in which the chirality κ_l = S^x_l S^y_{l+1} - S^y_l S^x_{l+1} exhibits a finite long-range order

Bambi Hu, Guoxiang Huang

Parametric simultaneous solitary wave (simulton) excitations are shown possible in nonlinear lattices. Taking a one-dimensional diatomic lattice with a cubic potential as an example we consider the nonlinear coupling between the upper cutoff mode of acoustic branch (as a fundamental wave) and the upper cutoff mode of optical branch (as a second harmonic wave

Eugene M. Chudnovsky

The prospect of developing magnetic qubits is discussed. The first part of the article makes suggestions on how to achieve the coherent quantum superposition of spin states in small ferromagnetic clusters, weakly uncompensated antiferromagnetic clusters, and magnetic molecules. The second part of the article deals with mechanisms of decoherence expected in m

G. Bellessa

Spin Tunneling in Fe8 powder : a comment on Europhys. Lett. 47, 722, 1999, by Del Berco et al.

Pascal Cedraschi, Markus Buttiker

We investigate the persistent current of a ring with an in-line quantum dot capacitively coupled to an external circuit. Of special interest is the magnitude of the persistent current as a function of the external impedance in the zero temperature limit when the only fluctuations in the external circuit are zero-point fluctuations. These are time-dependent f

Beat Ammon, Masatoshi Imada

Different models for doping of two-orbital chains with mobile $S=1/2$ fermions and strong, ferromagnetic (FM) Hund's rule couplings stabilizing the S=1 spins are investigated by density matrix renormalization group (DMRG) methods. The competition between antiferromagnetic (AF) and FM order leads to a rich phase diagram with a narrow FM region for weak AF

W. Apel, Yu. A. Bychkov

We study the relaxation of a spin I that is weakly coupled to a quantum mechanical environment. Starting from the microscopic description, we derive a system of coupled relaxation equations within the adiabatic approximation. These are valid for arbitrary I and also for a general stationary non--equilibrium state of the environment. In the case of equilibriu

Massimo Capone, Luca Capriotti, Federico Becca, Sergio Caprara

We investigate the metal-insulator transition in the half-filled Hubbard model on a two-dimensional triangular lattice using both the Kotliar-Ruckenstein slave-boson technique, and exact numerical diagonalization of finite clusters. Contrary to the case of the square lattice, where the perfect nesting of the Fermi surface leads to a metal-insulator transitio

P. Launois, R. Moret, D. Le Bolloc'h, P. A. Albouy

Following the synthesis of aligned single-wall carbon nanotubes in the channels of AlPO4-5 zeolite single crystals, we present the first X-ray diffraction and diffuse scattering results. They can be analysed in terms of a partial filling of the zeolite channels by nanotubes with diameter around 4A. The possible selection of only one type of nanotube during t

Perez Moses, Ross H. McKenzie

In a number of quasi-one-dimensional organic metals the dependence of the magnetoresistance on the direction of the magnetic field is quite different from the predictions of Boltzmann transport theory for a Fermi liquid with a scattering rate that is independent of momentum. We consider a model in which there are large variations in the scattering rate over

S. -R. Eric Yang, Min-Chul Cha, Jung Hoon Han

The analyticity of the lowest Landau level wave functions and the relation between filling factor and the total angular momentum severely limits the possible forms of trial wave functions of a disk of electrons subject to a strong perpendicular magnetic field. For N, the number of electrons, up to 12 we have tested these disk trial wave functions for the hal

Pengcheng Dai, H. A. Mook, G. Aeppli, S. M. Hayden

One of the most striking universal properties of the high-transition-temperature (high-$T_c$) superconductors is that they are all derived from the hole-doping of their insulating antiferromagnetic (AF) parent compounds. From the outset, the intimate relationship between magnetism and superconductivity in these copper-oxides has intrigued researchers. Eviden

G. Srinivas, A. Yethiraj, B. Bagchi

Long distance excitation energy transfer between a donor and an acceptor embedded in a polymer chain is usually assumed to occur via the Forster mechanism which predicts a 1/R^6 distance dependence of the transfer rate, where R is the distance between the donor and the acceptor. In solution R fluctuates with time. In this work, a Brownian dynamics simulation

Dragan Huterer, Michael S. Turner

Recent use of Type Ia supernovae to measure acceleration of the universe has motivated questions regarding their optimal use to constrain cosmological parameters Omega_M, Omega_Λ and w_Q. In this work we address the question: what is the optimal distribution of supernovae in redshift in order to best constrain the cosmological parameters? The solution to thi

James Binney

The Milky Way's satellites provide unique information about the density of the Galactic halo at large radii. The inclusion of even a few rather inaccurate proper motions resolves an ambiguity in older mass estimates in favour of higher values. Many of the satellites are concentrated into streams. The dynamics of the Magellanic Stream provided an early in

Raymundo Baptista, M. S. Catalan

We report on the R-band eclipse mapping analysis of high-speed photometry of the dwarf nova EX Dra on the rise to the maximum of the November 1995 outburst. The eclipse map shows a one-armed spiral structure of ~180 degrees in azimuth, extending in radius from R ~0.2 to 0.43 R_{L1} (where R_{L1} is the distance from the disk center to the inner Lagrangian po

T. L. Landecker, P. E. Dewdney, T. A. Burgess, A. D. Gray

We describe an aperture synthesis radio telescope optimized for studies of the Galactic interstellar medium (ISM), providing the ability to image extended structures with high angular resolution over wide fields. The telescope produces images of atomic hydrogen emission using the 21-cm HI spectral line, and, simultaneously, continuum emission in two bands ce

G. H. Marion, P. Hoeflich, J. C. Wheeler

We describe a research program to improve the understanding of Type Ia Supernovae (SNe Ia) by modeling and observing near infrared (NIR) spectra of these events. The NIR between 0.9 microns and 2.5 microns is optimal for examining certain products of the SNe Ia explosion that may be blended or obscured in other spectral regions. NIR analysis will enable us t

C. D. Wilson

In this review, I discuss recent detailed studies of individual molecular clouds in M33 in higher rotational transitions of CO, 13CO, and the fine structure line of atomic carbon. These data reveal that the temperature and density of the molecular gas is correlated with the presence of nearby massive star formation, with clouds with more intense star formati

L. D. Matthews

We explore the vertical light distribution as a function of galactocentric radius in the edge-on (i=88) Sd `superthin' galaxy UGC7321. UGC7321 is a low-luminosity spiral (M_B,i=-17.0) with a diffuse, low surface brightness stellar disk and no discernible bulge component. Within 0.25' (725 pc) of the disk center the global luminosity profile of UGC732

Steven R. Majewski, James C. Ostheimer, William E. Kunkel, Richard J. Patterson

We have begun a survey of the structure of the Milky Way halo, as well as the halos of other Local Group galaxies, as traced by their constituent giant stars. These giant stars are identified via large area, CCD photometric campaigns. Here we present the basis for our photometric search method, which relies on the gravity sensitivity of the Mg I triplet + Mg

W. J. Maciel

Two aspects of the chemical evolution of 4He in the Galaxy are considered on the basis of a sample of disk planetary nebulae by the application of corrections due to the contamination of 4He from the progenitor stars. First, the He/H radial gradient is analyzed, and then, the helium to heavy element enrichment ratio is determined for metallicities up to the

C. M. Dutra, E. Bica

We carried out a systematic search for new star clusters in a field of 5$^{\circ} \times5^{\circ}$ centred close to the Galactic Nucleus using the infrared JHK$_s$ 2MASS Survey archive. In addition we searched for embedded clusters in the directions of HII regions and dark clouds for $|\ell|\le4^{\circ}$. As a result we present a list of 58 IR star clusters

Gian Luigi Granato

I review recent advances in the determination of the cosmic history of star formation, and its relevance in our understanding of the formation of structures. I emphasize the importance of dust reprocessing in the high--z universe, as demonstrated in particular by IR and sub-mm data. This demand a panchromatic approach to observations and suitable modelling t

Manuel E. Merchan, Marcio A. G. Maia, Diego G. Lambas

We use the Updated Zwicky Catalog of galaxies (Falco et al. 1999) to generate a catalog of groups, by means of a friend-of-friend algorithm. The correlation length of the total sample is well fitted with a power law $ ξ(r)=(r/r_0)^γ$ with parameters $r_0=9.0 \pm 0.4 h^{-1}Mpc$ and $γ= -1.67 \pm 0.09$ for values of $r<70 h^{-1} Mpc$. Three subsamples defined

Jesper Sollerman, Cecilia Kozma, Claes Fransson, Bruno Leibundgut

We present observations of the peculiar supernova SN 1998bw, which was probably associated with GRB 980425. The photometric and spectroscopic evolution is monitored up to 500 days past explosion. We also present modeling based on spherically symmetric, massive progenitor models and very energetic explosions. The models allow line identification and clearly s

Andre Maeder, Georges Meynet

Several properties of massive stars with large effects of rotation and radiation are studied. We show that there are 2 roots for the equation giving the rotational velocities at break-up: 1) The usual solution, which is shown to apply when the Eddington ratio $Γ$ of the star is smaller than formally 0.639. 2) Above this value of $Γ$, there is a second root,

Georges Meynet, Andre Maeder

Grids of models for rotating stars are constructed in the range of 9 to 120 M$_{\odot}$ at solar metallicity. The following effects of rotation are included: shellular rotation, new structure equations for non-conservative case, surface distorsions, increase of mass loss with rotation, meridional circulation and interaction with horizontal turbulence, shear

E. Athanassoula

I briefly review the properties of the gas flow in and around the region of the bar in a disc galaxy and discuss the corresponding inflow and the loci of star formation. I then review the flow of gas in barred galaxies which have an additional secondary bar. Finally I discuss the signatures of bars in edge-on galaxies.

U. Becciani, V. Antonuccio-Delogu, C. Gheller, L. Calori

Over the past few years, the role of visualization for scientific purpose has grown up enormously. Astronomy makes an extended use of visualization techniques to analyze data, and scientific visualization has became a fundamental part of modern researches in Astronomy. With the evolution of high performance computers, numerical simulations have assumed a gre

Nelson Christensen, Renate Meyer

We present a strategy for a statistically rigorous Bayesian approach to the problem of determining cosmological parameters from the results of observations of anisotropies in the cosmic microwave radiation background. We propose the application of Markov chain Monte Carlo methods, specifically the Metropolis-Hastings algorithm, to estimate the parameters. A

V. Avila-Reese, C. Firmani

We study the evolution of disk galaxies using galaxy evolutionary models with initial and boundary conditions linked to the hierarchical formation scenario. Disks galaxies are modeled locally within growing cold dark matter halos and including a physical model for star formation. We focus our attention on predictions of the star formation history, size and s

Benjamin D. Wandelt, Romeel Dave, Glennys R. Farrar, Patrick C. McGuire

Spergel and Steinhardt have recently proposed the concept of dark matter with strong self-interactions as a means to address numerous discrepancies between observations of dark matter halos on subgalactic scales and the predictions of the standard collisionless dark matter picture. We review the motivations for this scenario and discuss some recent, successf

R. Kantowski, J. K. Kao, R. C. Thomas

We give distance--redshift relations in terms of elliptic integrals for three different mass distributions of the Friedmann-Lema\^ıtre-Robertson-Walker (FLRW) cosmology. These models are dynamically pressure free FLRW on large scales but, due to mass inhomogeneities, differ in their optical properties. They are the filled-beam model (standard FLRW), the empt

K. M. Nollett, R. B. Wiringa, R. Schiavilla

We have computed the cross section for the process d + alpha -> 6Li + gamma at the low energies relevant for primordial nucleosynthesis and comparison with laboratory data. The final state is a six-body wave function generated by the variational Monte Carlo method from the Argonne v_18 and Urbana IX potentials, including improved treatment of large-particle-

Ivan Horvath, Chetan T Balwe, Robert Mendris

It is shown that it is impossible to construct a free theory of fermions on infinite hypercubic Euclidean lattice in even number of dimensions that: (a) is ultralocal, (b) respects the symmetries of hypercubic lattice, (c) chirally nonsymmetric part of its propagator is local, and (d) describes single species of massless Dirac fermions in the continuum limit

M. Jarrell, H. R. Krishnamurthy

The Dynamical Cluster Approximation (DCA) is modified to include disorder. The DCA incorporates non-local corrections to local approximations such as the Coherent Potential Approximation (CPA) by mapping the lattice problem with disorder, and in the thermodynamic limit, to a self-consistently embedded finite-sized cluster problem. It satisfies all of the cha

Dragoş-Victor Anghel

The phenomenon of Bose-like condensation, the continuous change of the dimensionality of the particle distribution as a consequence of freezing out of one or more degrees of freedom in the low particle density limit, is investigated theoretically in the case of closed systems of massive bosons and fermions, described by general single-particle hamiltonians.

Nima Arkani-Hamed, Lawrence Hall, Hitoshi Murayama, David Smith

An alternative to the conventional see-saw mechanism is proposed to explain the origin of small neutrino masses in supersymmetric theories. The masses and couplings of the right-handed neutrino field are suppressed by supersymmetry breaking, in a way similar to the suppression of the Higgs doublet mass, $μ$. New mechanisms for light Majorana, Dirac and steri

Zurab Kakushadze

We consider a recent proposal to solve the cosmological constant problem within the context of brane world scenarios with infinite volume extra dimensions. In such theories bulk can be supersymmetric even if brane supersymmetry is completely broken. We propose a setup where unbroken bulk supersymmetry appears to protect the brane cosmological constant. This

J. Goldstein, C. S. Hill, J. Incandela, Stephen Parke

The production of a Standard Model Higgs boson in association with a top quark pair at the upcoming high luminosity run (15 inverse fb integrated luminosity) of the Fermilab Tevatron (root s = 2.0 TeV) is revisited. For Higgs masses below 140 GeV we demonstrate that the production cross section times branching ratio for H->B Bbar decays yields a significant

G. Dvali, Ian I. Kogan, M. Shifman

The theories in which our world presents a domain wall (brane) embedded in large extra dimensions predict new types of topological defects. These defects arise due to the fact that the brane on which we live spontaneously breaks isometries of the extra space giving mass to some graviphotons. In many cases the corresponding vacuum manifold has nontrivial homo

Renyue Cen, Zoltan Haiman

Ionizing sources embedded in the neutral intergalactic medium (IGM) before cosmological reionization generate discrete HII regions. We show that a sufficiently bright quasar (for example, one tenth as luminous as that recently discovered by Fan et al.) can ionize a large volume, allowing the transmission of a substantial fraction of the flux of its intrinsic

Gonzalo Usaj, Harold. U. Baranger

We study spin-dependent transport through ferromagnet/normal-metal/ferromagnet double tunnel junctions in the mesoscopic Coulomb blockade regime. A general transport equation allows us to calculate the conductance in the absence or presence of spin-orbit interaction and for arbitrary orientation of the lead magnetizations. The tunneling magnetoresistance (TM

B. L. Aneva, D. Arnaudon, A. Chakrabarti, V. K. Dobrev

Combined $(q,h)$-deformations proposed by Kupershmidt and Ballesteros-Herranz-Parashar are studied. In each case a transformation is shown to lead to an equivalent, standard $q$-deformation. We briefly indicate that appropriate singular limits of the same type of transformations can however lead from standard biparametric $(p,q)$-deformations to non-hybrid b

Jerome Martin, Alain Riazuelo, Dominik J. Schwarz

We emphasize that the estimation of cosmological parameters from cosmic microwave background (CMB) anisotropy data, such as the recent high resolution maps from BOOMERanG and MAXIMA-1, requires assumptions about the primordial spectra. The latter are predicted from inflation. The physically best-motivated scenario is that of slow-roll inflation. However, ver

Adam P. Szczepaniak, Eric S. Swanson

The relationship of the quark model to the known chiral properties of QCD is a longstanding problem in the interpretation of low energy QCD. In particular, how can the pion be viewed as both a collective Goldstone boson quasiparticle and as a valence quark antiquark bound state where universal hyperfine interactions govern spin splittings in the same way as

J. A. de Azcárraga, A. J. Macfarlane

This paper attempts to provide a comprehensive compilation of results, many new here, involving the invariant totally antisymmetric tensors (Omega tensors) which define the Lie algebra cohomology cocycles of $su(n)$, and that play an essential role in the optimal definition of Racah-Casimir operators of $su(n)$. Since the Omega tensors occur naturally within

W. P. Lin, G. Boerner, H. J. Mo

In this paper we present Monte-Carlo simulations of Lyman alpha absorption systems which originate in galactic haloes, galaxy discs and dark matter (DM) satellites around big central haloes. It is found that for strong Lyman alpha absorption lines galactic haloes and satellites can explain ~20% and 40% of the line number density of QSO absorption line key pr

Jürgen König, Yuval Gefen

We study coherence of electron transport through interacting quantum dots and discuss the relation of the coherent part to the flux-sensitive conductance for three different types of Aharonov-Bohm interferometers. Contributions to transport in first and second order in the intrinsic line width of the dot levels are addressed in detail. We predict an asymmetr

Emiliano Papa, Alexei M. Tsvelik

In this paper we study the critical exponents of the quantum sine-Gordon and U(1) Thirring models in the incommensurate phase. This phase appears when the chemical potential $h$ exceeds a critical value and is characterized by a finite density of solitons. The low-energy sector of this phase is critical and is described by the Gaussian model (Tomonaga-Luttin

Saurya Das, Romesh K Kaul, Parthasarathi Majumdar

A new entropy bound, tighter than the standard holographic bound due to Bekenstein, is derived for spacetimes with non-rotating isolated horizons, from the quantum geometry approach in which the horizon is described by the boundary degrees of freedom of a three dimensional Chern Simons theory.

Karl Landsteiner, Esperanza Lopez, Michel H. G. Tytgat

We study the dispersion relation for scalar excitations in supersymmetric, non-commutative theories at finite temperature. In N=4 Yang-Mills the low momenta modes have superluminous group velocity. In the massless Wess-Zumino model the minimum of the dispersion relation is at non zero momentum for temperatures above T_0 ~ (g \theta)^(-1\2). We briefly commen

Jochen Heitger, Rainer Sommer, Hartmut Wittig

We propose a general method to obtain accurate estimates for some of the &#34;low-energy constants&#34; in the one-loop effective chiral Lagrangian by means of simulating lattice QCD. In particular, the method is sensitive to those constants whose values are required to test the hypothesis of a massless up-quark. Initial tests performed in the quenched appro

J. J. Brey, A. Prados

A general kind of models with hierarchically constrained dynamics is shown to exhibit logarithmic anomalous relaxation, similarly to a variety of complex strongly interacting materials. The logarithmic behavior describes most of the decay of the response function.

R. P. Woodard

I consider Lagrangians which depend nonlocally in time but in such a way that there is no mixing between times differing by more than some finite value $Δt$. By considering these systems as the limits of ever higher derivative theories I obtain a canonical formalism in which the coordinates are the dynamical variable from $t$ to $t + {Δt}$. A simple formula

Hiroki Saito, Masahito Ueda

The critical behavior of collective modes and the collapsing dynamics of trapped Bose-Einstein condensates with attractive interactions are studied analytically and numerically. The time scales of these dynamics both below and above the critical point of the collapse are found to obey power laws with a single parameter of N/N_c - 1, where N is the number of

T. Kotani, N. Kawai, F. Nagase, M. Namiki

XTE J1748-288 is a new X-ray transient with a one-sided radio jet. It was observed with ASCA on 1998/09/06 and 1998/09/26, 100 days after the onset of the radio-X-ray outburst. The spectra were fitted with an attenuated power-law model, and the 2-6-keV flux was 4.6 * 10^{-11} erg s^{-1} cm^{-2} and 2.2 * 10^{-12} on 09/06 and 09/26, respectively. The light c

Henry P. Stapp

The paper develops a version of modal logic that stays completely within the framework provided by quantum principles, and then proves, within the framework of quantum thinking, and in particular without invoking &#34;hidden variables&#34;, a Bell-type nonlocality result.

T. S. Mahesh, Kavita Dorai, Arvind, Anil Kumar

Quantum computing using two-dimensional NMR has recently been described using scalar coupling evolution technique [J. Chem. Phys.,109,10603 (1998)]. In the present paper, we describe two-dimensional NMR quantum computing with the help of selective pulses. A number of logic gates are implemented using two and three qubits with one extra observer spin. Some ma

E. Knill, R. Laflamme, G. Milburn

We previously established that in principle, it is possible to quantum compute using passive linear optics with photo-detectors (quant-ph/0006088). Here we describe techniques based on error detection and correction that greatly improve the resource and device reliability requirements needed for scalability. The resource requirements are analyzed for ideal l

W J Wykes, S. C. Chapman, G. Rowlands

The chaotic interaction between electrons and whistler mode waves has been shown to provide a mechanism for enhanced diffusion in phase space. Pitch angle diffusion is relevant for the scattering of electrons into the loss cones, thus providing a source for auroral precipitating electrons. A single whistler mode wave propagating parallel to the background ma

Jan M. L. Martin, Charles W. Bauschlicher,, Alessandra Ricca

The sensitivity of computed DFT (Density Functional Theory) molecular properties (including energetics, geometries, vibrational frequencies, and infrared intensities) to the radial and angular numerical integration grid meshes, as well as to the partitioning scheme, is discussed for a number of molecules using the Gaussian 98 program system. Problems with ty

W Wykes, S C Chapman, G Rowlands

During periods of increased magnetospheric activity, whistler wave emissions have been observed with increased wave amplitudes. We consider a pitch angle diffusion mechanism that is shown to scale with whistler wave amplitude and hence is &#39;switched on&#39; during these periods of intense activity. We consider the interaction between relativistic electron

K. Pomorski, L. Prochniak, K. Zajac, S. G. Rohozinski

The generalized Bohr Hamiltonian was used to describe the low-lying collective excitations in even-even isotopes of Ru, Pd, Te, Ba and Nd. The Strutinsky collective potential and cranking inertial functions were obtained using the Nilsson potential. The effect of coupling with the pairing vibrations is taken into account approximately when determining the in

J. F. Berger, K. Pomorski

The neutron and proton density distributions obtained in constrained Hartree-Fock-Bogolyubov calculations with the Gogny force along the fission paths of 232Th, 236U, 238U and 240Pu are analyzed. Significant differences in the multipole deformations of neutron and proton densities are found. The effect on potential energy surfaces and on barrier heights of a

B. Nerlo-Pomorska, K. Pomorski, J. F. Berger, J. Decharge

The proton and neutron density distributions, one- and two-neutron separation energies and radii of nuclei for which neutron halos are experimentally observed, are calculated using the self-consistent Hartree-Fock-Bogoliubov method with the effective interaction of Gogny. Halo factors are evaluated assuming hydrogen-like antiproton wave functions. The factor

Su Houng Lee, Ismail Zahed

We derive the analogue of the QCD low energy theorems for the scalar and pseudoscalar gluonic correlators in nuclear matter. We find that the scalar correlations are depleted while the pseudoscalar correlations are enhanced to leading order in the nuclear matter density. We briefly discuss the consequences of these findings on the QCD spectrum.

O. Civitarese, M. Gadella, R. Id Betan

In this work we discuss possible definitions of the mean value of the energy for a resonant (Gamow) state. The mathematical and physical aspects of the formalism are reviewed. The concept of rigged Hilbert space is used as a supportive tool in dealing with Gamow-resonances.

Richard L. Hall

Non-relativistic potential models are considered of the pure power V(r) = sgn(q) r^q and logarithmic V(r) = ln(r) types. Envelope representations and kinetic potentials are employed to show that these potentials are actually in a single family. The log spectra can be obtained from the power spectra by the limit q --> 0 taken in a smooth representation P_{n\e

Richard L. Hall, Nasser Saad

We study weak-coupling perturbation expansions for the ground-state energy of the Hamiltonian with the generalized spiked harmonic oscillator potential V(x) = Bx^2 + A/x^2 + lambda/x^alpha, and also for the bottoms of the angular momentum subspaces labelled by ell = 0,1,2 ..., in N-dimensions corresponding to the spiked harmonic oscillator potential: V(x) =

Roberto De Leo

We present the results of our numerical exploration of the fractal structure found by S.P. Novikov in the problem of the behviour of magnetoresistance in a normal metal under a strong magnetic field. The case we discuss in this paper is the simplest non-trivial one, namely the case of 2 Fermi Surfaces that cut the brillouin zone along of the coordinate axes

Peter A. Djondjorov, Vassil M. Vassilev

In the present work we study acceleration waves in plate-like bodies using the balance laws for the time-dependent von Karman equations presented in [P. A. Djondjorov and V. M. Vassilev, Conservation Laws and Group-Invariant Solutions of the von Karman Equations, Int. J. Nonlinear Mech. 31 (1), pp. 73-87, (1986)]. Two of these balance laws correspond to the

Vladimir Turaev

We give an exposition of the work of Bigelow and Krammer who proved that the Artin braid groups are linear.

Robert L. Bryant

A Kahler metric is said to be Bochner-Kahler if its Bochner curvature vanishes. This is a nontrivial condition when the complex dimension of the underlying manifold is at least 2. In this article it will be shown that, in a certain well-defined sense, the space of Bochner-Kahler metrics in complex dimension n has real dimension n+1 and a recipe for an explic

Andrey I. Musienko

In the present paper we discuss arguments, favouring the view that massive fermions represent dislocations (i.e. topological solitons) in discrete space-time with Burgers vectors, parallel to an axis of time. If to put symmetrical parts of tensors of distortions (i.e. derivatives of atomic displacements on coordinates) and mechanical stresses equal zero, the

L. Alvarez-Gaume, J. L. F. Barbon

We show that the classic results of Schwinger on the exact propagation of particles in the background of constant field-strengths and plane waves can be readily extended to the case of non-commutative QED. It is shown that non-perturbative effects on constant backgrounds are the same as their commutative counterparts, provided the on-shell gauge invariant dy

Stoil Donev

In this paper a new look on the electro-magnetic duality is presented and appropriately exploited. The duality analysis in the nonrelativistic and relativistic formulations is shown to lead to the idea the mathematical model field to be a differential form valued in the 2-dimensional vector space ${\cal R}^2$. A full ${\cal R}^2$ covariance is achieved throu

Jayprokas Chakrabarti, Asis Basu, Bijon Bagchi

Fermions on the lattice have bosonic excitations generated from the underlying periodic background. These, the lattice bosons, arise near the empty band or when the bands are nearly full. They do not depend on the nature of the interactions and exist for any fermion-fermion coupling. We discuss these lattice boson solutions for the Dirac Hamiltonian.

Stanley J. Brodsky

Measurements of the power-law corrections to Bjorken scaling and the behavior of structure functions in the highly stressed $x_{bj} \to 1$ regime of electroproduction can lead to new information on the quark-quark correlations controlling the nucleon wavefunction at far-off-shell kinematics. Electroproduction on nuclei at $ A > x_{bj} > 1$ is sensitive to hi

A. Denner, S. Dittmaier, M. Roth, D. Wackeroth

RACOONWW is the first Monte Carlo generator for e+e- --> WW --> 4f(+gamma) that includes the electroweak O(alpha) radiative corrections in the double-pole approximation completely. Some numerical results for LEP2 energies are discussed, and the predictions for the total W-pair cross section are confronted with LEP2 data.

Z. Z. Aydin, A. Kandemir, O. Yilmaz, A. U. Yilmazer

Production of supersymmetric particles in TeV scale polarized photon-proton collisions is discussed. Polarizations of both photon and proton beams are considered. Associated productions of squark-chargino and squark-gluino, and production of squark pairs have been examined. Although the cross sections for different initial beam polarizations do not differ mu

A. Denner, S. Dittmaier, M. Roth, D. Wackeroth

We calculate the complete O(alpha) electroweak radiative corrections to e+e- --> WW --> 4f in the electroweak Standard Model in the double-pole approximation. We give analytical results for the non-factorizable virtual corrections and express the factorizable virtual corrections in terms of the known corrections to on-shell W-pair production and W decay. The

B. Krippa

Effective field theory of the in-medium nucleon-nucleon interaction is considered. The effective range parameters are found to be of a natural scale. The low density limit is discussed both in perturbative and nonperturbative situations. In the nonperturbative case the attractive character of the nucleon-nucleon interactions in the $^{1}S_0$ channel leads to

J. M. Campbell, R. K. Ellis

We report on QCD radiative corrections to the process, p\bar{p} to Zb\bar{b} in the approximation in which the b-quark is considered massless. The implementation of this process in the general purpose Monte Carlo program MCFM is discussed in some detail. These results are used to investigate backgrounds to Higgs boson production in the ZH channel. We investi

R. Kaminski, L. Lesniak, B. Loiseau

Interactions in coupled channels pipi, KKbar and an effective 2pi2pi in scalar-isoscalar wave have been analysed. Influence of interchannel couplings on analytical structure of multichannel interaction amplitudes has been studied. Interplay of S-matrix zeroes and poles and their relation with parameters of scalar resonances has been investigated.

Tran N. Truong

The vector pion form factor is used as an example to analyze this question. Given the experimental radius of the pion, the crucial question is whether perturbative methods could be used for the effective chiral lagrangian to calculate the pion form factor. Our analysis shows that the pion rms radius is far too large (or the related rho resonance mass is too

R. Kaminski, L. Lesniak, K. Rybicki

We impose unitarity constraints on the S-wave isoscalar pion-pion amplitudes extracted from the analysis of the pi- p ---> pi+ pi- n data which have been measured by the CERN-Cracow-Munich collaboration on a transversely polarized target at 17.2 GeV/c pi- momentum. Two &#34;steep&#34; solutions contain a narrow S-wave f0(750) resonance under the rho(770) and

L. de Barbaro, E. L. Berger, R. Brock, D. Casey

The main focus of this working group was to investigate the different issues associated with the development of quantitative tools to estimate parton distribution functions uncertainties. In the conclusion, we introduce a &#34;Manifesto&#34; that describes an optimal method for reporting data.

Nadia Fettes, Ulf-G. Meißner

We analyze elastic-pion nucleon scattering to third order in the so-called small scale expansion. It is based on an effective Lagrangian including pions, nucleons and deltas as active degrees of freedom and counting external momenta, the pion mass and the nucleon-delta mass splitting as small parameters. The fermion fields are considered as very heavy. We pr

Changhao Jin

The governing role of light-cone dynamics in inclusive heavy hadron decay processes is demonstrated. Nonperturbative QCD effects on the processes can be systematically calculated using light-cone expansion and heavy quark effective theory. The applications of the light-cone approach to studying electroweak and strong interactions and hadron structure with se

T. S. Biro

In a simplified model we study how close can the result of a fast, non-equilibrium hadronization of quark matter in an expanding fireball come to hadronic composition in equilibrium. We present a chemical approach to the simple A+B --> C quark fusion, showing ideal equilibrium constrained by conservation laws, the fugacity parametrization, as well as linear

M. N. Chernodub, S. Fujimoto, S. Kato, M. Murata

We study various representations of infrared effective theory of SU(2) Gluodynamics as a (quantum) perfect lattice action. In particular we derive a monopole action and a string model of hadrons from SU(2) Gluodynamics. These are lattice actions which give almost cut-off independent physical quantities even on coarse lattices. The monopole action is determin

E. Frlez, B. K. Wright, D. Pocanic

We present the program optics that simulates the light response of an arbitrarily shaped scintillation particle detector. Predicted light responses of pure CsI polygonal detectors, plastic scintillator staves, cylindrical plastic target scintillators and a Plexiglas light-distribution plate are illustrated. We demonstrate how different bulk and surface optic

Richard Nisius, Daniel Haas, Claus Grupen

The measurements of hadronic structure functions of the photon based on the reaction ee --> ee gamma^(*)(P^2) gamma^*(Q^2)--> ee hadrons are discussed.

S. S. Gousheh, H. R. Sepangi

We discuss the construction of wave packets resulting from the solutions of a class of Wheeler-DeWitt equations in Robertson-Walker type cosmologies. We present an ansatz for the initial conditions which leads to a unique determination of the expansion coefficients in the construction of the wave packets with probability distributions which, in an interestin

J. Podolsky, J. B. Griffiths

The C-metric is usually understood as describing two black holes which accelerate in opposite directions under the action of some conical singularity. Here, we examine all the solutions of this type which represent accelerating sources and investigate the null limit in which the accelerations become unbounded. We show that the resulting space-times represent

J. Podolsky, J. B. Griffiths

The Bonnor-Swaminarayan solutions are boost-rotation symmetric space-times which describe the motion of pairs of accelerating particles which are possibly connected to strings (struts). In an explicit and unified form we present a generalised class of such solutions with a few new observations. We then investigate the possible limits in which the acceleratio

Zygmunt Haas, Joseph Y. Halpern, Li Li, Stephen B. Wicker

The allocation of scarce spectral resources to support as many user applications as possible while maintaining reasonable quality of service is a fundamental problem in wireless communication. We argue that the problem is best formulated in terms of decision theory. We propose a scheme that takes decision-theoretic concerns (like preferences) into account an