October 1999 arXiv papers — page 15

Boudewijn F. Roukema, David Valls-Gabaud

An initially highly biased value of the spatial correlation function, which decreases with time up to a transition redshift z_t ~ 1-2, was predicted theoretically at least as early as 1993, and shown to be consistent with the HDF-N angular correlation function estimates in 1997. Observational analyses are presented here which show (i) an HDF-N estimate of th

J. H. Fan

In this paper, the historical infrared (JHK) data compiled from the published literature are presented here for 30 blazars. Maximum near-IR variations are found and compared with the optical ones. For the color-magnitude relation, some objects show that the color index increases with magnitude while 1253-055 shows complex behaviour, which perhaps suggests th

N. Drory, U. Hopp, R. Bender, G. Feulner

The Munich Near-IR Cluster Survey (MUNICS) is a K' selected survey covering 1 square degree in the K' and J NIR bands with complementary optical photometry in the V, R, and I bands covering a subarea of 0.35 square degrees. The 3-sigma limiting magnitude is 19.5 in K'. The main goals of the project are the identification of clusters of galaxies a

M. W. Richmond, T. F. Droege, G. Gombert, M. Gutzwiller

The Amateur Sky Survey (TASS) is a loose confederation of amateur and professional astronomers. We describe the design and construction of our Mark III system, a set of wide-field drift-scan CCD cameras which monitor the celestial equator down to thirteenth magnitude in several passbands. We explain the methods by which images are gathered, processed, and re

Afsar Abbas

The Lightest Supersymmetric Particle predicted in most of the supersymmetric scenarios is an ideal candidate for the dark matter of cosmology. Their detection is of extreme significance today. Recently there have been intriguing signals of a 59 Gev neutralino dark matter at DAMA in Gran Sasso. We look at other possible signatures of dark matter in astrophysi

G. Delamarter, A. Frank, L. Hartmann

The interaction of a stellar or disk wind with a collapsing environment holds promise for explaining a variety of outflow phenomena observed around young stars. In this paper we present the first simulations of these interactions. The focus here is on exploring how ram pressure balance between wind and ambient gas and post-shock cooling affects the shape of

J. E. Chambers, M. A. Murison

Symplectic N-body integrators are widely used to study problems in celestial mechanics. The most popular algorithms are of 2nd and 4th order, requiring 2 and 6 substeps per timestep, respectively. The number of substeps increases rapidly with order in timestep, rendering higher-order methods impractical. However, symplectic integrators are often applied to s

Maxim Lyutikov, Roger Blandford, George Machabeli

Relativistic plasma masers operating on the anomalous cyclotron-Cherenkov resonance and the Cherenkov-drift resonance are capable of explaining the main observational characteristics of pulsar radio emission. Both electromagnetic instabilities are due to the interaction of the fast particles from the primary beam and from the tail of the secondary pairs dist

M. Wold, M. Lacy, P. B. Lilje, S. Serjeant

We have observed the galaxy environments around two complete samples of radio-loud (steep-spectrum) and radio-quiet quasars (RLQ and RQQ) at 0.5 < z < 0.8 that are matched in B-luminosity, and find that the environments of both quasar populations are pratically indistinguishable. A few objects are found in relatively rich clusters, but on average, they seem

Eric Emsellem, Daniel Friedli

We just started an observational program to obtain 2D kinematics of nuclear bars, to be compared to N body simulations of single and double-barred galaxies.

G. Lagache, J. L. Puget, R. Gispert

The recently discovered Submillimeter Extragalactic Background (submm EB) has opened new perspectives on our understanding of galaxy evolution. We detail in this paper one of the major cosmological consequences of this discovery, the submm luminosity density history of the Universe.

J. D. Kurk, H. J. A. Roettgering, L. Pentericci, G. K. Miley

Observations of the powerful radio galaxy 1138-262 at z=2.2 suggest that this galaxy is a massive galaxy in the center of a forming cluster. We have imaged the field of 1138-262 with the Very Large Telescope in a narrow band encompassing the redshifted Lyman alpha emission. We detect 34 probable line emitters in the 6&#39;x6&#39; field. These are candidate L

Vicent Quilis, Jose M. Ibanez, Diego Saez

Galaxy clusters are sources of gravitational radiation. The main aim of this paper is to give numerical estimates and theoretical description of the relevant features of the gravitational radiation coming from an appropriate spatial distributions of galaxy clusters. Since no analytical approaches are currently available to describe the strongly nonlinear reg

P. Parma, M. Murgia, H. R. de Ruiter, R. Fanti

After a brief introduction to the morphological properties of FRI radio sources, we discuss the possibility that FRI jets are relativistic at their bases and decelerate quickly to non-relativistic velocities. From two-frequency data we determine spectral index distributions and consequently the ages of FRI sources. We show that in the large majority of cases

S. Andreon, R. Pello, E. Davoust, R. Dominguez

We present extensive and accurate photometry in the near-infrared H band of a complete sample of objects in an area of about 400 arcmin2 toward the Coma cluster of galaxies. The sample, including about 300 objects, is complete down to H~17 mag, the exact value depending on the type of magnitude (isophotal, aperture, Kron) and the particular region studied. T

Osamu Kaburaki

A model for advection-dominated accretion flows (ADAFs) in a global magnetic field is proposed. In contrast to the well known ADAF models in which the viscosity of a fluid determines both angular momentum transfer and energy dissipation in the flow, the magnetic field and the electric resistivity, respectively, control them in this model. A manageable set of

S. G. Djorgovski

Quasars at large redshifts provide a powerful probe of structure formation in the early universe. Several arguments suggest that the formation of ellipticals and massive bulges may have involved an early quasar phase. At very large redshifts, such structures are likely to be found at the highest peaks of the density field, and would thus be highly biased tra

P. G. van Dokkum, M. Franx, D. Fabricant, D. D. Kelson

We present results from a morphological study of the distant X-ray cluster MS1054-03 at z=0.83. We have obtained a large, two color HST WFPC2 mosaic of this cluster, and measured redshifts of 186 galaxies in the MS1054-03 field with the 10m Keck telescope. Of 81 spectroscopically confirmed cluster galaxies observerd with HST, 13 are merger systems. Most of t

J. Christopher Howk, Blair D. Savage

We present new, deep optical images (BVI+H-alpha) of the interstellar medium (ISM) far above the plane of NGC 891. These sub-arcsecond images give a direct visual view of two physically distinct ``phases'' of the thick interstellar disk of this galaxy. A dense phase of the thick disk ISM is observed in our BVI images as highly-structured dust-bearing clouds

D. L. Khokhlov

It is assumed that proton decays into Planck neutrinos. The energy of the Planck neutrino is equal to the Planck mass in the preferred rest frame. In the frame moving relative to the preferred rest frame the energy of the Planck neutrino reduces by the corresponding Lorentz factor. The lifetime of proton depends on the kinetic energy of proton relative to th

C. M. Arizmendi

This is a brief introduction to fractals, multifractals and wavelets in an accessible way, in order that the founding ideas of those strange and intriguing newcomers to science as fractals may be communicated to a wider public. Fractals are the geometry of the wildness of nature, where the euclidian geometry fails. The structures of nonlinear dynamics associ

C. A. A. de Carvalho, R. M. Cavalcanti, E. S. Fraga, S. E. Jorás

We use a path integral formalism to derive the semiclassical series for the partition function of a particle in D dimensions. We analyze in particular the case of attractive central potentials, obtaining explicit expressions for the fluctuation determinant and for the semiclassical two-point function in the special cases of the harmonic and single-well quart

A. F. Boden, M. J. Creech-Eakman, D. Queloz

We report on the determination of the visual orbit of the double-lined spectroscopic binary system 12 Bootes with data obtained by the Palomar Testbed Interferometer in 1998 and 1999. 12 Boo is a nearly equal-mass double-lined binary system whose spectroscopic orbit is well known. We have estimated the visual orbit of 12 Boo from our interferometric visibili

E. Calzetta, B. L. Hu, S. Ramsey

Starting from the quantum kinetic field theory [E. Calzetta and B. L. Hu, Phys. Rev. D37, 2878 (1988)] constructed from the closed-time-path (CTP), two-particle-irreducible (2PI) effective action we show how to compute from first principles the shear and bulk viscosity functions in the hydrodynamic-thermodynamic regime. For a real scalar field with $λΦ^{4}$

T. Wong, Ozgur Mustecaplioglu, L. You, M. Lewenstein

We investigate the scattering of intense short laser pulses off trapped cold fermionic atoms. We discuss the sensitivity of the scattered light to the quantum statistics of the atoms. The temperature dependence of the scattered light spectrum is calculated. Comparisons are made with a system of classical atoms who obey Maxwell-Boltzmann statistics. We find t

R. L. Jaffe, W. Busza, J. Sandweiss, F. Wilczek

We discuss speculative disaster scenarios inspired by hypothetical new fundamental processes that might occur in high energy relativistic heavy ion collisions. We estimate the parameters relevant to black hole production; we find that they are absurdly small. We show that other accelerator and (especially) cosmic ray environments have already provided far mo

Nathan Salwen, Dean Lee

We introduce a spectral approach to non-perturbative field theory within the periodic field formalism. As an example we calculate the real and imaginary parts of the propagator in 1+1 dimensional phi^4 theory, identifying both one-particle and multi-particle contributions. We discuss the computational limits of existing diagonalization algorithms and suggest

Felix Finster, Joel Smoller, Shing-Tung Yau

We consider a static, spherically symmetric system of a Dirac particle in a classical gravitational and SU(2) Yang-Mills field. We prove that the only black-hole solutions of the corresponding Einstein-Dirac-Yang/Mills equations are the Bartnik-McKinnon black-hole solutions of the SU(2) Einstein-Yang/Mills equations; thus the spinors must vanish identically.

K. G. Chetyrkin, A. Retey

We derive explicit transformation formulae relating the renormalized quark mass and field as defined in the MS-bar scheme with the corresponding quantities defined in any other scheme. By analytically computing the three-loop quark propagator in the high-energy limit (that is keeping only massless terms and terms of first order in the quark mass) we find the

Aashish A. Clerk, Vinay Ambegaokar

Using a generalization of the non-crossing approximation which incorporates Andreev reflection, we study the properties of an infinite-U Anderson impurity coupled to two superconducting leads. In the regime where $Δ$ and $T_K$ are comparable, we find that the position of the sub-gap resonance in the impurity spectral function develops a strong anomalous phas

Peter Hanggi, Sigmund Kohler, Thomas Dittrich

Chaotic tunneling in a driven double-well system is investigated in absence as well as in the presence of dissipation. As the constitutive mechanism of chaos-assisted tunneling, we focus on the dynamics in the vicinity of three-level crossings in the quasienergy spectrum. The coherent quantum dynamics near the crossing is described satisfactorily by a three-

Laurent Bartholdi, Tullio G. Ceccherini-Silberstein

Extending the analogous result of Cannon and Wagreich for the fundamental groups of surfaces, we show that, for the l-regular graphs X associated to regular tessellations of hyperbolic plane by m-gons, the denominators of the growth series (which are rational and were computed by Floyd and Plotnick) are reciprocal Salem polynomials. As a consequence, the gro

J. A. Jones, V. Vedral, A. Ekert, G. Castagnoli

The experimental realisation of the basic constituents of quantum information processing devices, namely fault-tolerant quantum logic gates, requires conditional quantum dynamics, in which one subsystem undergoes a coherent evolution that depends on the quantum state of another subsystem. In particular, the subsystem may acquire a conditional phase shift. He

Patrick Dorey, Roberto Tateo

We exhibit a relationship between the massless $a_2^{(2)}$ integrable quantum field theory and a certain third-order ordinary differential equation, thereby extending a recent result connecting the massless sine-Gordon model to the Schrödinger equation. This forms part of a more general correspondence involving $A_2$-related Bethe ansatz systems and third-or

Carsten Timm, K. H. Bennemann

The rapid destruction of long-range antiferromagnetic order upon doping of Mott-Hubbard antiferromagnetic insulators is studied within a generalized Berezinskii-Kosterlitz-Thouless renormalization group theory in accordance with recent calculations suggesting that holes dress with vortices. We calculate the doping-dependent Neel temperature in good agreement

Tarun Deep Saini, Somak Raychaudhury, Varun Sahni, A. A. Starobinsky

Observations of high-redshift supernovae indicate that the universe is accelerating. Here we present a {\em model-independent} method for estimating the form of the potential $V(ϕ)$ of the scalar field driving this acceleration, and the associated equation of state $w_ϕ$. Our method is based on a versatile analytical form for the luminosity distance $D_L$, o

Maria C. Neacsu

It is well-known that the 5D equations without sources may be reduced to the 4D ones with sources, provided an appropriate definition for the energy-momentum tensor of matter in terms of the extra part of the geometry.The advantage consists on the naturally appearance of gravitational and electromagnetic fields from this decomposition. With this ansatz an al

L. V. Laperashvili, H. B. Nielsen

The quantum field theory describing electric and magnetic charges and revealing a dual symmetry was developed in the Zwanziger formalism. The renormalization group (RG) equations for both fine structure constants - electric $α$ and magnetic $\tilde α$ - were obtained. It was shown that the Dirac relation is valid for the renormalized $α$ and $\tilde α$ at th

A. Levy Yeyati, A. Martin-Rodero, F. Flores

We present an interpolative method for describing coherent transport through an interacting quantum dot. The idea of the method is to construct an approximate electron self-energy which becomes exact both in the limits of weak and strong coupling to the leads. The validity of the approximation is first checked for the case of a single (spin-degenerate) dot l

Marcus Ansorg, Reinhard Meinel

We present a three-parameter family of solutions to the stationary axisymmetric Einstein equations that describe differentially rotating disks of dust. They have been constructed by generalizing the Neugebauer-Meinel solution of the problem of a rigidly rotating disk of dust. The solutions correspond to disks with angular velocities depending monotonically o

Elena A. Ostrovskaya, Yuri S. Kivshar, Mietek Lisak, Bjorn Hall

We apply the concepts of nonlinear guided-wave optics to a Bose-Einstein condensate (BEC) trapped in an external potential. As an example, we consider a parabolic double-well potential and derive coupled-mode equations for the complex amplitudes of the BEC macroscopic collective modes. Our equations describe different regimes of the condensate dynamics, incl

Philip Kim, Zhen Yao, Cristian A. Bolle, Charles M. Lieber

Dislocation-free decoration images containing up to 80,000 vortices have been obtained on high quality Bi$_{2}$Sr$_{2}$CaCu$_{2}$O$_{8+x}$ superconducting single crystals. The observed flux line lattices are in the random manifold regime with a roughening exponent of 0.44 for length scales up to 80-100 lattice constants. At larger length scales, the data exh

Q. H. Zhang, Sandra S. Padula

The Bose-Einstein correlations of two identically charged pions are derived when these particles, the most abundantly produced in relativistic heavy ion collisions, are confined in finite volumes. Boundary effects on single pion spectrum are also studied. Numerical results emphasize that conventional formulation usually adopted to describe two-pion interfero

Mark Stephenson, Carleton DeTar, Thomas DeGrand, Anna Hasenfratz

We test a recently proposed improved lattice-fermion action, the fat link clover action, examining indicators of pathological small-quark-mass lattice artifacts (&#34;exceptional configurations&#34;) on quenched lattices of spacing 0.12 fm and studying scaling properties of the light hadron spectrum for lattice spacing a=0.09 and 0.16 fm. We show that the ac

Jens Erler, Paul Langacker

A new analysis of the hadronic peak cross section at LEP 1 implies a small amount of missing invisible width in Z decays, while the effective weak charge in atomic parity violation has been determined recently to 0.6% accuracy, indicating a significantly negative S parameter. As a consequence of these two deviations, the data are described well if the presen

V. V. Konotop

An integrable discretization of the inhomogeneous Ablowitz-Ladik model with a linear force is introduced. Conditions on parameters of the discretization which are necessary for reproducing Bloch oscillations are obtained. In particular, it is shown that the step of the discretization must be comensurable with the period of oscillations imposed by the inhomog

A. J. Macfarlane, F. Wagner

Using a rational R-matrix associated with the 4 x 4 defining matrix representation of c_2=sp(4), the Lie algebra of Sp(4), a one-site operator solution of the associated Yang-Baxter algebra acting in the Fock space of two harmonic oscillators is derived. This is used to define N-site integrable systems, which are soluble by a version of the algebraic Bethe a

Vadim Kostrykin, Robert Schrader

In this article we continue our investigations of one particle quantum scattering theory for Schroedinger operators on a set of connected (idealized one-dimensional) wires forming a graph with an arbitrary number of open ends. The Hamiltonian is given as minus the Laplace operator with suitable linear boundary conditions at the vertices (the local Kirchhoff

A. N. F. Aleixo, A. B. Balantekin, M. A. Candido Ribeiro

Exact reflection and transmission coefficients for supersymmetric shape-invariant potentials barriers are calculated by an analytical continuation of the asymptotic wave functions obtained via the introduction of new generalized ladder operators. The general form of the wave function is obtained by the use of the F-matrix formalism of Froman and Froman which

A. A. Suzko

Algebraic Bargmann and Darboux transformations for equations of a more general form than the Schrödinger ones with an additional functional dependence h(r) in the right-hand side of equations are constructed. The suggested generalized transformations turn into the Bargmann and Darboux transformations for both fixed and variable values of energy and an angula

P. Chingangbam, Pankaj Sharan

We examine two singular Lagrangian systems with constraints which apparently reduce the phase space to a 2-dimensional sphere and a 2-dimensional hyperboloid. Rigorous constraint analysis by Dirac&#39;s method, however, gives 2-dimensional open disc and an infinite plane with a hole in the centre respectively as the reduced phase spaces. Upon canonical quant

Giampiero Esposito

A modification of the spiked harmonic oscillator is studied in the case for which the perturbation potential contains both an inverse power and a linear term. It is then possible to evaluate trial functions by solving an integral equation due to the occurrence of the linear term. The general form of such integral equation is obtained by using a Green-functio

Danny Summers, Chun-yu Ma

During the recovery phase of a magnetic storm, fluxes of relativistic ($>1$ MeV) electrons in the inner magnetosphere ($3\le L \le 6$) increase to beyond pre-storm levels, reaching a peak about 4 days after the initiation of the storm. In order to account for the generation of these &#34;killer electrons&#34;, a model is presented primarily based on stochast

Amos Harpaz, Noam Soker

When an electric charge is supported at rest in a static gravitational field, its electric field is not supported with the charge, and it falls freely in the gravitational field. Drawing the electric field lines continuously in time, we find that they always emerge from the charge, but the electric field is curved and there is a stress force between the free

A. I. Smolyakov, P. H. Diamond

Generalized action invariants are identified for various models of drift wave turbulence in the presence of the mean shear flow. It is shown that the wave kinetic equation describing the interaction of the small scale turbulence and large scale shear flow can be naturally written in terms of these invariants. Unlike the wave energy, which is conserved as a s

M. V. Ivanov, P. Schmelcher

The electronic structure of the ground and some excited states of neutral atoms with the nuclear charge numbers $1\leq Z \leq 10$ and their single positive ions are investigated by means of our 2D mesh Hartree-Fock method for strong magnetic fields $0.5\leq γ\leq 10000$. For $γ=10000$ the ground state configurations of all the atoms and ions considered are g

Ernst Karl Kunst

An analysis of composite inertial motion (relativistic sum) within the framework of special relativity leads to the conclusion that every translational motion must be the symmetrically composite relativistic sum of a finite number of quanta of velocity. It is shown that the resulting space-time geometry is Gaussian and the four-vector calculus has its roots

T. R. Hemmert, B. R. Holstein, G. Knoechlein, D. Drechsel

Using the techniques of chiral effective field theories we evaluate the so called generalized polarizabilities of the nucleon, which characterize the structure dependent components in virtual Compton scattering (VCS) as probed in the electron scattering reaction e N \to e&#39; N gamma. Results are given for both spin-dependent and spin-independent structure

V. N. Stibunov, A. Yu. Loginov, D. M. Nikolenko, A. V. Osipov

The differential cross section and target asymmetry components of the reaction D(e,pp)e&#39;pi- on polarized deuteron were measured. The kinetic energies of the protons were measured within 55-180 MeV and 46-265 MeV. The polar acceptance angles in laboratory frame for the both protons are (64 - 82) degrees and the azimuthal angles are (-16 +16), (164 - 196)

A. Samoilenko, A. Prykarpatsky, V. Samoylenko

The canonical reduction algorithm is applied to Maxwell and Yang-Mills equations considered as Hamiltonian systems on some fiber bundles with symplectic and connection structures. The minimum interaction principle proved to have geometric origin within the reduction method devised.

Laurent Bartholdi

In 1980 Rostislav Grigorchuk constructed a group $G$ of intermediate growth, and later obtained the following estimates on its growth $\gamma$: $e^{\sqrt{n}}\precsim\gamma(n)\precsim e^{n^\beta},$ where $\beta=\log_{32}(31)\approx0.991$. He conjectured that the lower bound is actually tight. In this paper we improve the lower bound to $e^{n^\alpha}\precsim\g

Mark Brittenham

A Seifert surface F for a knot K is disk decomposable if there is a taut sutured manifold heirarchy for the complement of F, whose decomposing surfaces are all disks. It follows that F has minimal genus for the knot K, and has handlebody complement, i.e., F is free. We show that these necessary conditions for disk decomposability are not sufficient, by const

Yakov Eliashberg, Leonid Polterovich

We prove, for a class of contact manifolds, that the universal cover of the group of contact diffeomorphisms carries a natural partial order. It leads to a new viewpoint on geometry and dynamics of contactomorphisms. It gives rise to invariants of contactomorphisms which generalize the classical notion of the rotation number. Our approach is based on tools o

D. Markushevich, A. S. Tikhomirov

A 10-dimensional symplectic moduli space of torsion sheaves on the cubic 4-fold is constructed. It parametrizes the stable rank 2 vector bundles on the hypeplane sections of the cubic 4-fold which are obtained by Serre&#39;s construction from normal elliptic quintics. The natural projection to the dual projective 5-space parametrizing the hyperplane sections

Brett McInnes

When the gauge groups of the two heterotic string theories are broken, over tori, to their &#34;SO(16)x SO(16)&#34; subgroups, the winding modes correspond to representations which are spinorial with respect to those subgroups. Globally, the two subgroups are isomorphic neither to SO(16)x SO(16) nor to each other. Any attempt to formulate the T-duality of th

H. W. Lee, Y. S. Myung

We consider an easy way to get the noncommutative spacetime in Minkowski space. This corresponds to introducing a magnetic field ${\rm\bf B} = B \hat {\rm\bf k}$ in the plane. We construct a green&#39;s function in coordinate space which includes a Moyal phase factor. The projection to the lowest Landau level(LLL) is necessary for a simple calculation. Using

A. de la Macorra

We study the cosmological evolution of string/M moduli fields T. We use T-duality to fix the potential and show that the superpotential W is a function of the duality invariant function j(T) only. If W is given as a finite polynomial of j then the moduli fields {\it do not} give an accelerating universe, i.e. they {\it cannot} be used as quintessence. Furthe

T. Teubner

The elastic production of vector mesons at HERA is discussed from the theoretical point of view. We briefly review different models, their successes and shortcomings. Main emphasis is put on recent issues in perturbative QCD calculations. Models including the vector meson wave function are compared with an approach based on parton-hadron duality. We discuss

Willem T. H. Vanoers, E497 Collaboration

Measurements of parity-violating longitudinal analyzing powers Az (normalized asymmetries) in polarized proton-proton scattering and in polarized neutron capture on the proton (n+p -> d+gamma) provide a unique window on the interplay between the weak and strong interactions between and within hadrons. Several new proton-proton parity violation experiments ar

El aaoud El hassan, A. N. Kamal

We have investimated the effect of the isospin 1/2, J^P = 0^+ resonant state K^*_0(1950) on the decays D^0 ->\bar{K}^{0}ηand D^0 ->\bar{K}^0 η&#39; as a function of the branching ratio sum r =Br(K^*_0(1950)->\bar{K}^0η)+ Br(K^*_0(1950)->\bar{K}^0 η&#39; and coupling constants g_{K^*_0\bar{K}^0η}, g_{K^*_0\bar{K}^0η&#39;}. We have used a factorized input for

Thomas Hebbeker

Within the framework of the constrained Minimal Supersymmetric extension of the Standard Model we show that recent LEP I limits on the invisible Z width exclude the possibility that the lightest sparticle is the sneutrino.

S. Y. Choi

In most supersymmetric theories, charginos $\tildeχ^\pm_{1,2}$ belong to the class of the lightest supersymmetric particles and they are easy to observe at e^+e^- colliders. By measuring the total cross sections and the left-right asymmetries with polarized beams as well as the angular correlations of the decay products of the charginos in $e^+e^-\to\tildeχ^

B. L. Ioffe

The improved calculation method of quark distributions in hadrons in the framework of QCD sum rules is presented. The imaginary part of the virtual photon scattering amplitude on some hadronic current is considered in the case, when initial and final virtualities of the current $p^2_1$ and $p^2_2$ are different, $p^2_1\not= p^2_2$. The double Borel transform

J. C. Williams

The transverse momentum distribution of the diffractive final state provides an interesting test of models of diffractive deep-inelastic scattering at HERA. We present a comparison of several colour-singlet exchange models with thrust transverse momentum data from a recent H1 analysis. We also study the effect of constraints imposed on the kinematically-acce

A. V. Anisovich, V. V. Anisovich, L. Montanet, V. A. Nikonov

We discuss gamma gamma partial widths of pseudoscalar/isoscalar mesons eta(M) in the mass region M = 1000-1500 MeV. The transition amplitudes eta(1295) -> gamma gamma and eta(1440) -> gamma gamma are studied within an assumption that the decaying mesons are the members of the first radial excitation nonet 2^1S_0 q\bar q. The calculations show that partial wi

Fumihiro Takayama, Masahiro Yamaguchi

Neutrino masses and their mixing are studied in detail in the framework of a supersymmetric standard model with bilinear R-parity violation. In this scenario, the mixing matrix among the neutrinos is in a restrictive form. We find that only the small angle MSW solution is allowed for the solar neutrino problem when the results of the CHOOZ experiment are com

Wolfgang Ochs

We discuss observables in multiparticle production for three kinds of limits of decreasing kinematical scales: 1. the transition jet \to hadron (limit y_{cut}\to 0 of the resolution parameter y_{cut}); 2. single particle inclusive distributions normalized at threshold \sqrt s\to 0 and 3. particle densities in the limit of low momentum p,p_T\to 0. The observa

M. Stratmann

The main goals of `spin physics&#39; are recalled, and some theoretical and phenomenological aspects of longitudinally polarized deep inelastic scattering and other hard processes are reviewed. The spin dependent parton densities of protons and photons and polarized fragmentation functions are introduced, and the relevant theoretical framework in next-to-lea

S. Lazanu, I. Lazanu

Starting from the general Lindhard theory describing the partition of particles energy in materials between ionisation and displacements, analytical approximate solutions have been derived, for media containing one and more atomic species, for particles identical and different to the medium ones. Particular cases, and the limits of these equations at very hi

Thomas J. Weiler

The observation of cosmic--ray events above the Greisen-Kuzmin-Zatsepin (GZK) cutoff of $\sim 5\times 10^{19}$ eV challenges orthodox modeling. We discuss a possible solution which uses standard hot Big Bang cosmology and Standard Model (SM) particle physics augmented only by $\lsim $ eV neutrino masses as suggested by solar, atmospheric, and terrestrial neu

J. J. Godina, Y. Meurice, S. Niermann, M. B. Oktay

We discuss three questions related to the critical behavior of hierarchical spin models: 1) the hyperscaling relations in the broken symmetry phase; 2) the combined use of dual expansions to calculate the non-universal quantities; 3) the fine-tuning issue in approximately supersymmetric models.

J. N. Simone, S. Hashimoto, A. X. El-Khadra, A. S. Kronfeld

We describe a model independent lattice QCD method for determining the deviation from unity for h_{A1}(1), the B -> D* l nu form factor at zero recoil. We extend the double ratio method previously used to determine the B -> D l nu form factor. The bulk of statistical and systematic errors cancel in the double ratios we consider, yielding form factors which p

Chris Stewart, Roman Koniuk

Lattice NRQCD has proven successful in describing the physics of the upsilon system and B-mesons, though some concerns arise when it is used in simulations of charm quarks. It is certainly possible that the NRQCD expansion is not converging fast enough at this scale. We present some preliminary results on the low-mass breakdown of NRQCD, in particular the be

Marco Guagnelli, Jochen Heitger

We report on a parallelized implementation of SSOR preconditioning for O(a) improved lattice QCD with Schrödinger functional boundary conditions. Numerical simulations in the quenched approximation at parameters in the light quark mass region demonstrate that a performance gain of a factor $\sim$ 1.5 over even-odd preconditioning can be achieved.

CDF Collaboration, T. Affolder

We have reconstructed the radiative decays $χ_{b}(1P) \to Υ(1S) γ$ and $χ_{b}(2P) \to Υ(1S) γ$ in $p \bar{p}$ collisions at $\sqrt{s} = 1.8$ TeV, and measured the fraction of $Υ(1S)$ mesons that originate from these decays. For $Υ(1S)$ mesons with $p^Υ_{T}>8.0$ GeV/$c$, the fractions that come from $χ_{b}(1P)$ and $χ_{b}(2P)$ decays are $(27.1\pm6.9(stat)\pm

Daniel Ashery

The diffractive dissociation of 500 GeV/c $π^-$ into di-jets is described as a way to measure the momentum distribution of quarks in the pion. The measurements of the pion diffractive dissociation were carried out using data from Fermilab E791. Preliminary results show that the $|q\bar {q}>$ Asymptotic wave function which was developed using perturbative QCD

Maria Cristina Neacsu

In this paper is presented a general-relativistic approach of cuasi-neutral bodies endowed with magnetic field. Starting from the similarity of neutron particles with neutron stars for which the general-relativistic framework is imposed, this treatment is extended to neutrons. A class of interior solutions is derived from the Einstein field equations for a s

Maria Cristina Neacsu

The exterior of a relativistic star can be modelated with the Vaidya radiating metric. It is started from the generalized Vaidya metric that allows a type II fluid and studied the conditions of generating new analytical solutions of the Einstein&#39;s field equations. It is shown that the mass parameter solution gives the classical de Sitter universe in the

Zhi-Zhong Chen, Michelangelo Grigni, Christos Papadimitriou

We consider a modified notion of planarity, in which two nations of a map are considered adjacent when they share any point of their boundaries (not necessarily an edge, as planarity requires). Such adjacencies define a map graph. We give an NP characterization for such graphs, and a cubic time recognition algorithm for a restricted version: given a graph, d

M. Reynolds

It is shown that the decision problem for the temporal logic with until and since connectives over real-numbers time is PSPACE-complete.

Anand Venkataraman

A statistical model for segmentation and word discovery in child directed speech is presented. An incremental unsupervised learning algorithm to infer word boundaries based on this model is described and results of empirical tests showing that the algorithm is competitive with other models that have been used for similar tasks are also presented.

Young-Kyun Kwon, David Tomanek

Using Monte Carlo simulations, we investigate the possibility of an orientational melting transition within a &#34;rope&#34; of (10,10) carbon nanotubes. When twisting nanotubes bundle up during the synthesis, orientational dislocations or twistons arise from the competition between the anisotropic inter-tube interactions, which tend to align neighboring tub

Jung M. Woo, Jan Wehr

We study central limit theorems for certain nonlinear sequences of random variables. In particular, we prove the central limit theorems for the bounded conductivity of the random resistor networks on hierarchical lattices.

Marcelo M. Leite

The susceptibility amplitude ratio in the neighborhood of a uniaxial Lifshitz point is calculated at one-loop level using field-theoretic and $ε_{L}$-expansion methods. We use the Schwinger parametrization of the propagator in order to split the quadratic and quartic part of the momenta, as well as a new special symmetry point suitable for renormalization pu

Alok Shukla, Sumit Mazumdar

We show that chemical modification of the trans-polyacetylene structure that involves substitution of the backbone hydrogen atoms with conjugated side groups, leads to reduction of the backbone bond alternation as well as screening of the effective Coulomb interaction. Consequently the optical gap of the substituted material is smaller than the parent polyen

Pascal Chauve, Pierre Le Doussal, Thierry Giamarchi

We study moving periodic structures in presence of correlated disorder using renormalisation group. We find that the effect of disorder persists at all velocities resulting at zero temperature in a Moving Bose Glass phase with transverse pinning. At non zero temperature we find two distinct moving glass phases. We predict a sharp transition, as velocity incr

Yuri Kudasov, Gennadi Uimin, Peter Fulde, Alexander Ovchinnikov

We discuss the effects of an applied magnetic field on the low energy excitations in the low temperature phase of Yb4As3. We show also why the magnetic interaction of the Yb{3+} ions is nearly of an isotropic Heisenberg spin-1/2 type. A small anisotropy due to an intrachain dipolar interaction leads to the opening of a gap when a magnetic field is applied. T

Reimer Kuehn, Jens Urmann

We report on a refined version of our spin-glass type approach to the low-temperature physics of structural glasses. Its key idea is based on a Born von Karman expansion of the interaction potential about a set of reference positions in which glassy aspects are modeled by taking the harmonic contribution within this expansion to be random. Within the present

A. R. Denton

Charge-stabilized colloidal suspensions can be conveniently described by formally reducing the macroion-microion mixture to an equivalent one-component system of pseudo-particles. Within this scheme, the utility of a linear response approximation for deriving effective interparticle interactions has been demonstrated [M. J. Grimson and M. Silbert, Mol. Phys.

Yuriy A. Kosevich, Stefano Lepri

The localization of vibrational energy, induced by the modulational instability of the Brillouin-zone-boundary mode in a chain of classical anharmonic oscillators with finite initial energy density, is studied within a continuum theory. We describe the initial localization stage as a gas of envelope solitons and explain their merging, eventually leading to a