October 1997 arXiv papers — page 8

JLQCD Collaboration, S. Aoki, M. Fukugita, S. Hashimoto

We present results of a large-scale simulation for the Kaon B parameter $B_K$ in quenched lattice QCD with the Kogut-Susskind quark action. Calculating $B_K$ at 1% statistical accuracy for seven values of lattice spacing in the range $a\approx 0.24-0.04$ fm on lattices up to $56^3\times 96$, we verify a quadratic $a$ dependence of $B_K$ theoretically predict

E. Zafiris

In the search for exact solutions to Einstein's field equations the main simplification tool is the introduction of spacetime symmetries. Motivated by this fact we develop a method to write the field equations for general matter in a form that fully incorporates the character of the symmetry. The method is being expressed in a covariant formalism using t

Beverly K. Berger, David Garfinkle

Numerical studies of the plane symmetric, vacuum Gowdy universe on $T^3 \times R$ yield strong support for the conjectured asymptotically velocity term dominated (AVTD) behavior of its evolution toward the singularity except, perhaps, at isolated spatial points. A generic solution is characterized by spiky features and apparent ``discontinuities'' in

G. J. Mathews, P. Marronetti, J. R. Wilson

We discuss (3+1) dimensional general relativistic hydrodynamic simulations of close neutron star binary systems. The relativistic field equations are solved at each time slice with a spatial 3-metric chosen to be conformally flat. Against this solution the hydrodynamic variables and gravitational radiation are allowed to respond. We have studied four physica

L. Herrera, J. Martinez

In the context of the Müller-Israel-Stewart second order phenomenological theory for dissipative fluids, we analyze the effects of thermal conduction and viscosity in a relativistic fluid, just after its departure from hydrostatic equilibrium, on a time scale of the order of relaxation times. Stability and causality conditions are contrasted with conditions

I. B. Khriplovich, A. A. Pomeransky

We consider the motion of a spinning relativistic particle in external electromagnetic and gravitational fields, to first order in the external field, but to an arbitrary order in spin. The correct account for the spin influence on the particle trajectory is obtained with the noncovariant description of spin. Concrete calculations are performed up to second

Reinaldo Gleiser

Using second order black hole perturbation theory, we show that the difference between the ADM mass and the final black hole mass, computed to the lowest significant order, is equal, to the same order, to the total gravitational radiation energy, obtained applying the Landau and Lifschitz (pseudotensor) equation to the first order perturbation. This result m

Reinaldo Gleiser, Oscar Nicasio, Richard Price, Jorge Pullin

The Bowen-York initial value data typically used in numerical relativity to represent spinning black hole are not those of a constant-time slice of the Kerr spacetime. If Bowen-York initial data are used for each black hole in a collision, the emitted radiation will be partially due to the ``relaxation'' of the individual holes to Kerr form. We compu

Yan Luo, Ming-Xue Shao, Zhong-Yuan Zhu

In this paper, we explicitly prove the presymplectic forms of the Palatini and Ashtekar gravity to be zero along gauge orbits of the Lorentz and diffeomorphism groups, which ensures the diffeomorphism invariance of these theories.

Naichung Conan Leung, Sangkug Yi

In this paper we show that the Ray-Singer complex analytic torsion is trivial for even dimensional Calabi-Yau manifolds. Then we define the quaternionic analytic torsion for quaternionic manifolds and prove that they are metric independent. In dimension four, the quaternionic analytic torsion equals to the self-dual analytic torsion. For higher dimensional m

Kazimierz Bragiel, Wlodzimierz Piechocki

We prove that the space of smooth initial data and the set of smooth solutions of the Liouville equation are homeomorphic.

V. Ozolins, C. Wolverton, A. Zunger

The classic metallurgical systems -- noble metal alloys -- that have formed the benchmark for various alloy theories, are revisited. First-principles fully relaxed general potential LAPW total energies of a few ordered structures are used as input to a mixed-space cluster expansion calculation to study the phase stability, thermodynamic properties and bond l

Mohit Randeria

I begin by briefly reviewing various experimental results on the pseudogap phenomena in underdoped cuprates. I argue that, taken together, all of these lead to a picture of singlet pairing above $T_c$. I then explore the idea that the pseudogap is a normal state precursor of the superconducting gap due to local, dynamic pairing correlations in a state withou

Yuhai Tu, John Toner, Markus Ulm

We study a model of flocking for a very large system (N=320,000) numerically. We find that in the long wavelength, long time limit, the fluctuations of the velocity and density fields are carried by propagating sound modes, whose dispersion and damping agree quantitatively with the predictions of our previous work using a continuum equation. We find that the

Vidar Gudmundsson, Ingibjorg Magnusdottir, Sigurdur I. Erlingsson

We study the optical absorption of arrays of quantum dots and antidots in a perpendicular homogeneous magnetic field. The electronic system is described quantum mechanically using a Hartree approximation for the mutual Coulomb interaction of the electrons. The evolution of the absorption is traced from the homogeneous to the strongly modulated case identifyi

Mario Nicodemi

The generalization of Kasteleyn and Fortuin clusters formalism is introduced in XY (or more generally O(n)) models. Clusters geometrical structure may be linked to spin physical properties as correlation functions. To investigate percolative characteristics, the new cluster definition is analytically explored in one dimension and with Monte Carlo simulations

Mario Nicodemi

In the context of a simple microscopic schematic scalar model we study the effects of spatial correlations in force transmission in granular assemblies. We show that the parameters of the normalized weights distribution function, $P(v)\sim v^α\exp(-v/ϕ)$, strongly depend on the spatial extensions, $ξ_V$, of such correlations. We show, then, the connections b

B. Barbiellini, P. M. Platzman

We discuss the work aimed at studying the momentum density of high Tc superconducting oxides using Compton profile and positron annihilation spectroscopies.

Uwe Ritschel

In a recent experiment by Krimmel et al. [PRL 78, 3880 (1997)], the critical behavior of FeCo near a (001) surface was studied by x-ray scattering. Here the experimental data are reanalyzed, taking into account recent theoretical results on order-parameter profiles in the crossover regime between ordinary and normal transitions. Excellent agreement between t

Aninda Jiban Bhattacharyya, T. R. Middya, S. Tarafdar

In this paper we present a computer simulation study of ionic conductivity in solid polymeric electrolytes. The multiphase nature of the material is taken into account. The polymer is represented by a regular lattice whose sites represent either crystalline or amorphous regions with the charge carrier performing a random walk. Different waiting times are ass

A. V. Inyushkin, A. N. Taldenkov, S. Yu. Shabanov, L. N. Dem'yanets

The in-plane thermal conductivity K(T) of Zn-doped YBCO single crystals (YBCO:Zn) has been investigated in the temperature range from 5 to 250 K and in magnetic fields up to 30 kOe. The thermal conductivity decreases substantially with increase of the Zn concentration providing reduction in the thermal conductivity peak and its disappearance at a high conten

Sudhansu S. Mandal, V. Ravishankar

We derive an effective non-linear sigma model for quantum hall systems with arbitrary polarizations, by employing the recently proposed doublet model. We study the topological excitations, in particular, the skyrmions, as a function of the filling fraction as well as the polarization. We determine the relationship between the topological charge density and t

Christopher A. Voigt, Robert M. Ziff

We study the dynamic behavior of the Ziff-Gulari-Barshad (ZGB) irreversible surface-reaction model around its kinetic second-order phase transition, using both epidemic and poisoning-time analyses. We find that the critical point is given by p_1 = 0.3873682 \pm 0.0000015, which is lower than the previous value. We also obtain precise values of the dynamical

V. Ozolins, C. Wolverton, A. Zunger

The theory of epitaxial strain energy is extended beyond the harmonic approximation to account for large film/substrate lattice mismatch. We find that for fcc noble metals (i) directions <001> and <111> soften under tensile biaxial strain (unlike zincblende semiconductors) while (ii) <110> and <201> soften under compressive biaxial strain. Consequently, (iii

Arjendu K. Pattanayak, Paul Brumer

We use a recent result to show that the rate of loss of coherence of a quantum system increases with increasing system phase space structure and that a chaotic quantal system in the semiclassical limit decoheres exponentially with rate $2 λ_2$, where $λ_2$ is a generalized Lyapunov exponent. As a result, for example, the dephasing time for classically chaoti

Randall K. Smith, Eli Dwek

Small angle scatterings of X-rays by interstellar dust particles create halos around x-ray sources. By observing these halos with sufficient angular resolution it is possible to derive information about both the spatial distribution of the dust along the line of sight to the source and some of the physical properties of the scattering dust particles. Previou

J. Miralda-Escude, M. Rauch, W. L. W. Sargent, T. A. Barlow

We propose a new method of analysis for the \lya forest, namely to measure the 1-point and 2-point joint probability distribution of the transmitted flux. The results for a sample of seven observed quasars and from two simulations of structure formation are shown and compared. Statistically significant differences in the 2-point function between the results

G. J. Mathews, J. R. Wilson, J. Salmonson

We report on general relativistic hydrodynamic studies which indicate several new physical processes which may contribute to powering gamma-ray bursts in neutron star binaries. Relativistically driven compression, heating, and collapse of the individual stars can occur many seconds before inspiral and merger. This compression may produce a neutrino burst of

T. Saeki, K. Anraku, S. Orito, J. Ormes

A very sensitive search for cosmic-ray antihelium was performed using data obtained from three scientific flights of BESS magnetic rigidity spectrometer. We have not observed any antihelium; this places a model-independent upper limit (95 % C.L.) on the antihelium flux of 6*10**(-4) m**(-2)sr**(-1)s**(-1) at the top of the atmosphere in the rigidity region 1

T. W. Jones, Lawrence Rudnick, Byung-Il Jun, Kazimierz J. Borkowski

This paper reports on a workshop hosted by the University of Minnesota, March 23-26, 1997. It addressed fundamental dynamical issues associated with the evolution of shell supernova remnants and the relationships between supernova remnants and their environments. The workshop considered, in addition to classical shell SNRs, dynamical issues involving X-ray f

M. Kunzli, P. North

We test the hypothesis of Berthet (1992) which foresees that Am stars become giant metallic A and F stars (defined by an enhanced value of the blanketing parameter Delta_m_2 of the Geneva photometry) when they evolve. If this hypothesis is right, Am and metallic A-FIII stars need to have the same rate of binaries and a similar distribution of vsini. From our

G. R. Petitpas, C. D. Wilson

We have observed the 13CO J=2-1, 12CO J=2-1 and 12CO J=3-2 lines at a few locations in the dwarf irregular galaxies IC 10 and NGC 6822 using the James Clerk Maxwell Telescope. In addition, we report the first detection of the 13CO J=3-2 transition in a Local Group galaxy. These low metallicity environments appear to be porous to UV radiation and allow for mo

R. P. Olling, M. R. Merrifield

The distribution of shapes of galaxies&#39; dark halos provides a basic test for models of galaxy formation. To-date, few dark halo shapes have been measured, and the results of different methods appear contradictory. Here, we add to the sample of measured shapes by calculating the flattening of the Milky Way&#39;s dark halo based on the manner in which the

M. Kunzli, P. North

Calcium abundance in the atmosphere of Am stars is examined as a function of their evolutionary state within the main sequence. New spectroscopic abundances as well as abundances abtained photometrically by Guthrie (1987) are used, since they are mutually quite consistent. The main result of this work is that, contrary to earlier suggestions, calcium abundan

Dario Fadda, Giuliano Giuricin, Gian Luigi Granato, Donatella Vecchies

For an extended sample of Seyfert galaxies we compile from the literature the infrared fluxes in the four IRAS bands, the ground-based small-beam (~ 5-10&#34;) fluxes in the standard Q, N, M, L (or L&#39;) bands, and the nuclear (non-stellar) estimated fluxes in the JHK bands. We estimate nuclear fluxes in the L band by applying a correction for stellar ligh

T. Minezaki, M. Cohen, Y. Kobayashi, Y. Yoshii

We present new deep $K&#39;$ counts of stars at the South Galactic Pole (SGP) taken with the NAOJ PICNIC camera to $K&#39;=17.25$. Star-galaxy separation to $K&#39;=17.5$ was accomplished effectively using image profiles because the pixel size we used is 0.509 arcsec. We interpret these counts using the SKY (Cohen 1994) model of the Galactic point source sky

S. Malhotra, G. Helou, G. Stacey, D. Hollenbach

We report measurements of the [CII] fine structure line at 157.714 micron in 30 normal star-forming galaxies with the Long Wavelength Spectrometer (LWS) on the Infrared Space Observatory (ISO). The ratio of the line to total far-infrared luminosity, [CII]/FIR, measures the ratio of the cooling of gas to that of dust; and thus the efficiency of the grain phot

Ravi Pilla, Abraham Loeb

Unsteady activity of gamma-ray burst sources leads to internal shocks in their emergent relativistic wind. We study the emission spectra from such shocks, assuming that they produce a power-law distribution of relativistic electrons and posses strong magnetic fields. The synchrotron radiation emitted by the accelerated electrons is Compton up-scattered multi

Jeremy S. Heyl, Lars Hernquist

Using recently calculated analytic and numerical models for the thermal structure of ultramagnetized neutron stars, we estimate the effects that ultrastrong magnetic fields $B \ge 10^{14}$ G have on the thermal evolution of a neutron star. Understanding this evolution is necessary to interpret models that invoke ``magnetars&#39;&#39; to account for soft $γ$-

S. W. Allen

We present a detailed comparison of mass measurements for clusters of galaxies using ASCA and ROSAT X-ray data and constraints from strong and weak gravitational lensing. Our results for a sample of 13 clusters provide a consistent description of the distribution of gravitating matter in these systems. For the 6 cooling-flow clusters in the sample, which are

Wayne Hu, Daniel J. Eisenstein

For a universe with massive neutrinos, cold dark matter, and baryons, we solve the linear perturbation equations analytically in the small-scale limit and find agreement with numerical codes at the 1-2% level. The inclusion of baryons, a cosmological constant, or spatial curvature reduces the small-scale power and tightens limits on the neutrino density from

Sergei Nayakshin, Fulvio Melia

We here examine the conditions of the two-phase disk model under which magnetic flares arise above the cold accretion disk due to magnetic buoyancy and produce X-rays via Comptonization of the disk&#39;s soft radiation. We find that the disk&#39;s ability to produce strong magnetic flares is substantially diminished in its radiation dominated regions due to

Paul R. Shapiro, Alejandro C. Raga, Garrelt Mellema

Energy released by a small fraction of the baryons in the universe, which condensed out of while the IGM was cold, dark, and neutral,reheated and reionized it, exposing gas clouds within it to the glare of ionizing radiation. The first gas dynamical simulations of the photoevaporation of an intergalactic cloud by a quasar, including radiative transfer, are p

Kai Nagel, Paula Stretz, Martin Pieck, Rick Donnelly

Knowledge of fundamental traffic flow characteristics of traffic simulation models is an essential requirement when using these models for the planning, design, and operation of transportation systems. In this paper we discuss the following: a description of how features relevant to traffic flow are currently under implementation in the TRANSIMS microsimulat

Michael B. Green, Michael Gutperle, Hwang-hyun Kwon

Certain one-loop processes in eleven-dimensional supergravity compactified on T**2 determine exact, non-perturbative, terms in the effective action of type II string theories compactified on a circle. One example is the modular invariant U(1)-violating interaction of sixteen complex spin-1/2 fermions of ten-dimensional type IIB theory. This term, together wi

Joel E. Moore, Xiao-Gang Wen

The effects of impurity scattering on a general Abelian fractional quantum Hall (FQH) edge state are analyzed within the chiral-Luttinger-liquid model of low-energy edge dynamics. We find that some disordered edges can have several different phases characterized by different symmetries. The stable impurity edge phases are in general more symmetric than the o

Yang Lu, Pavlos Protopapas, R. D. Amado

We calculate the full static interaction of a Skyrmion and an anti-Skyrmion as a function of separation and relative grooming. From this, using projection methods and Born-Oppenheimer mixing, we obtain the nucleon antinucleon interaction. We find agreement with the major features of the empirical interaction including the strong central attraction and the sh

H. Lu, C. N. Pope

Intersecting p-branes can be viewed as higher-dimensional interpretations of multi-charge extremal p-branes, where some of the individual p-branes undergo diagonal dimensional oxidation, while the others oxidise vertically. Although the naive vertical oxidation of a single p-brane gives a continuum of p-branes, a more natural description arises if one consid

Borut Bajc, Antonio Riotto, Goran Senjanovic&#39;

We show that the monopole problem in Grand Unified Theories as well as the domain wall problem may be easily solved if the lepton number asymmetry in the Universe is large enough.

D. Endesfelder

The scattering theory of quantum transport relates transport properties of disordered mesoscopic conductors to their transfer matrix $\bbox{T}$. We introduce a novel approach to the statistics of transport quantities which expresses the probability distribution of $\bbox{T}$ as a path integral. The path integal is derived for a model of conductors with broke

J. Soffer, O. V. Teryaev

The distribution of longitudinal gluons in a nucleon, introduced earlier by Gorsky and Ioffe, is estimated from below by making use of the positivity of density matrix and the analogue of the Wandzura-Wilczek relation for the light-cone distributions of polarized gluons in a transversely polarized nucleon.

C. Wilke, S. Altmeyer, T. Martinetz

The decay pattern of aftershocks in the so-called &#39;coherent-noise&#39; models [M. E. J. Newman and K. Sneppen, Phys. Rev. E54, 6226 (1996)] is studied in detail. Analytical and numerical results show that the probability to find a large event at time $t$ after an initial major event decreases as $t^{-τ}$ for small $t$, with the exponent $τ$ ranging from

B. Eynard, C. Kristjansen

We study the generalisation of Baxter&#39;s three-colour problem to a random lattice. Rephrasing the problem as a matrix model problem we discuss the analyticity structure and the critical behaviour of the resulting matrix model. Based on a set of loop equations we develop an algorithm which enables us to solve the three-colour problem recursively

Gouranga C Nayak, V. Ravishankar

We study the production and the evolution of quark-gluon plasma expected to be formed in ultra relativistic heavy-ion collisions, within the color flux-tube model. We introduce the gluonic component in the Boltzmann equation, which we solve in the phase space which is extended to include the SU(3) color degree of freedom. The color degree of freedom is shown

E. L. Bratkovskaya, W. Cassing, R. Rapp, J. Wambach

We present a dynamical study of $e^+e^-$ production in C + C and Ca + Ca collisions at BEVALAC/SIS energies on the basis of the covariant transport approach HSD employing momentum-dependent $ρ$-meson spectral functions that include the pion modifications in the nuclear medium as well as the polarization of the $ρ$-meson due to resonant $ρ- N$ scattering. We

Sean A. Hayward

A unified first law of black-hole dynamics and relativistic thermodynamics is derived in spherically symmetric general relativity. This equation expresses the gradient of the active gravitational energy E according to the Einstein equation, divided into energy-supply and work terms. Projecting the equation along the flow of thermodynamic matter and along the

Gregory Gabadadze

We use an analogy between the Yang-Mills theory Hamiltonian and the matrix model description of the closed bosonic membrane theory to calculate the spectrum of glueballs in the large $N_c$ limit. Some features of the Yang-Mills theory vacuum, such as the screening of the topological charge and vacuum topological susceptibility are discussed. We show that the

M. A. Manna, V. Merle

The multiple-scale perturbation theory, well known for long-waves, is extended to the study of the far-field behaviour of short-waves, commonly called ripples. It is proved that the Benjamin-Bona-Mahony- Peregrine equation can propagates short-waves. This result contradict the Benjamin hypothesis that short-waves tends not to propagate in this model and clos

S. Schneider, G. J. Milburn

We consider one source of decoherence for a single trapped ion due to intensity and phase fluctuations in the exciting laser pulses. For simplicity we assume that the stochastic processes involved are white noise processes, which enables us to give a simple master equation description of this source of decoherence. This master equation is averaged over the n

Richard L. Martin, P. Jeffrey Hay, Lawrence R. Pratt

Reported here are results of theoretical calculations on the hexaaquoferric complex and deprotonated products to investigate the molecular mechanisms of hydrolysis of ferric ion in water. The combination of density functional electronic structure techniques and a dielectric continuum model for electrostatic solvation applied to the Fe(H$_2$O)$_6$$^{3+}$ comp

V. S. Barashenkov, W. A. Rodrigues

In this paper we analyze the physical meaning of sub- and superluminal soliton-like solutions (as the X-waves) of the relativistic wave equations and of some non-trivial solutions of the free Schrödinger equation for which the concepts of phase and group velocities have a different meaning than in the case of plane wave solutions. If we accept the strict val

T. Matolcsi, W. A. Rodrigues

Recent theoretical results show the existence of arbitrary speeds (0 <= v < \infty) solutions of all relativistic wave equations. Some recent experiments confirm the results for sound waves. The question arises naturally: What is the appropriate geometry of spacetime to describe superluminal phenomena? In this paper we present a spacetime model that incorpor

T. A. Larsson

A class of Fock representations of non-central extensions of the super-diffeomorphism algebra in (N+1|M) dimensions is constructed, by superization of the paper [physics/9705040]. The representations act on trajectories in (N|M)-dimensional superspace, the extra dimension being the parameter along the trajectory. The restrictions to various subalgebras are c

B. R. Schlei, D. Strottman, N. Xu

Within a hydrodynamical approach we investigate the sensitivity of single inclusive momentum spectra of hadrons in 158A GeV Pb+Pb collisions to three different equations of state of nuclear matter. Two of the equations of state are based on lattice QCD results and include a phase transition to a quark-gluon plasma. The third equation of state has been extrac

Erwin O. Alt

A brief overview is given of some recent advances in charged-composite particle scattering. On the theoretical side, I address the three-charged particle wave function asymptotics, the nonperturbative investigation of the long-range behaviour of the optical potential, and the question of the compactness of the kernels of the momentum space integral equations

A. Sibirtsev, W. Cassing, G. I. Lykasov, M. V. Rzjanin

We reanalyse the production of $p\bar{p}$ pairs in proton-nucleus and nucleus-nucleus collisions employing novel elementary cross sections for baryon-baryon and pion-baryon production channels based on a boson-exchange model. In contrast to previous transport studies performed in the literature the secondary pion induced channel is found to be most important

José Felipe Voloch

Let C be the curve y^2=x^6+1 of genus 2 over a field of characteristic zero. Consider C embedded in its Jacobian J by sending one of the points at infinity on C to the origin of J. In this brief note we show that the points of C whose image on J are torsion are precisely the two points at infinity and the six points with y=0.

Marc Bourdon, Hervé Pajot

In this paper we shall show that the boundary $\partial I_{p,q}$ of the hyperbolic building $I_{p,q}$ considered in M. Bourdon, \emph{Immeubles hyperboliques, dimension conforme et rigidité de Mostow} (Geometric And Functional Analysis, Vol 7 (1997), p 245-268) admits Poincaré type inequalities. Then by using Heinonen-Koskela&#39;s work, we shall prove Loewn

Daniel Zwanziger

We review the canonical quantization of continuum Yang-Mills theory, and derive the continuum Coulomb-gauge Hamiltonian by a simplification of the Christ-Lee method. We then analogously derive, by a simple and elementary method, the lattice Coulomb-gauge Hamiltonian in the minimal Coulomb gauge (and in other Coulomb gauges) from the known Kogut-Susskind Hami

E. J. Beggs, P. R. Johnson

We consider the canonical symplectic form for sine-Gordon evaluated explicitly on the solitons of the model. The integral over space in the form, which arises because the canonical argument uses the Lagrangian density, is done explicitly in terms of functions arising in the group doublecrossproduct formulation of the inverse scattering procedure, and we are

Hugo Garcia-Compean, Jerzy F. Plebanski, Maciej Przanowski

A geometric formulation of the Moyal deformation for the Self-dual Yang-Mills theory and the Chiral Model approach to Self-dual gravity is given. We find in Fedosov&#39;s geometrical construction of deformation quantization the natural geometrical framework associated to the Moyal deformation of Self-dual gravity.

C. Klimcik

Gauge theories are formulated on the noncommutative two-sphere. These theories have only finite number of degrees of freedom, nevertheless they exhibit both the gauge symmetry and the SU(2) &#34;Poincaré&#34; symmetry of the sphere. In particular, the coupling of gauge fields to chiral fermions is naturally achieved.

U. Baur, T. Han, J. Ohnemus

The processes $pp/ pbar p \to Z γ+ X \to \ell^+ \ell^- γ+ X$ ($\ell=e, μ$) and $pp/ pbarp \to Z γ+ X \to \barννγ+ X$ are calculated to ${\cal O}(α_s)$ for general $ZZγ$ and $Zγγ$ couplings. The impact of ${\cal O}(α_s)$ QCD corrections on the observability of $ZZγ$ and $Zγγ$ couplings in $Zγ$ production at the Tevatron and the Large Hadron Collider (LHC) is

R. Harlander, M. Steinhauser

In this article we evaluate mass corrections up to $O((m^2/q^2)^6)$ to the three-loop polarization function induced by an axial-vector current. Special emphasis is put on the evaluation of the singlet diagram which is absent in the vector case. As a physical application $O(α_s^2)$ corrections to the production of top quarks at future $e^+e^-$ colliders is co

J. Boguszynski, H. D. Dahmen, R. Kretschmer, L. Lukaszuk

The high-energy behaviour in a multi-channel system is investigated in the framework of collinear asymptotic dynamics for massive particles. We consider the most general trilinear coupling of N different scalar fields. We find Regge behaviour and obtain closed expressions for the Regge trajectories and couplings. The results are corraborated in the multi-cha

A. V. Efremov

The authors&#39;s point of view, based on QCD, on the nuclear quark structure is presented. Different models for explaining the EMC--effect are considered. It is also shown that cumulative production data are very useful for a better understanding of the EMC--effect and give some evidence in favor of its multiquark nature.

D. de Florian, M. Stratmann, W. Vogelsang

We study the prospects for HERA with polarized electron and/or proton beams to determine the functions describing the fragmentation of a longitudinally polarized parton into a polarized Lambda baryon. We examine both semi-inclusive deep-inelastic scattering (SIDIS) and photoproduction of Lambda.

Harald Fritzsch

In view of the observed strong hierarchy of the quark and lepton masses and of the flavor mixing angles, it is argued that the description of flavor mixing must take this into account. One particularly interesting way to describe the flavor mixing, which, however, is not the one used today, emerges, which is particularly suited for models of quark mass matri

D. L. Bennett, C. D. Froggatt, H. B. Nielsen

We put forward a model, or rather a relatively broad class of models, beyond the Standard Model based on the two main assumptions: MPP) The coupling constants should be fixed such as to ensure that there be many ``vacuum states&#39;&#39;, i.e. Lorentz invariant states of the fields, with the same energy density. Anti-GUT) At high energy, above an essential d

P. Zenczykowski

Weak radiative hyperon decays are discussed in the diquark-level approach. It is pointed out that in the general diquark formalism one may reproduce the experimentally suggested pattern of asymmetries, while maintaining Hara&#39;s theorem in the SU(3) limit. At present, however, no detailed quark-based model of parity-violating diquark-photon coupling exists

Subhendra Mohanty, Sarira Sahu

We show that in a supernova core the longitudinal photon (plasmon) has a space-like dispersion and Cerenkov absorption and emission of such photons is kinematically allowed. If the neutrino has a non-zero magnetic moment, then helicity flipping Cerenkov absorption of a plasmon $ν_L+γ\toν_R$ is the most efficient cooling mechanism of the supernova core, and t

R. Foot, R. R. Volkas, O. Yasuda

We compute up-down asymmetries for atmospheric neutrino induced electron and muon events in the SuperKamiokande detector for the following neutrino oscillation models: (A) maximally mixed $ν_μ - ν_τ$ or $ν_μ - ν_s$, (B) maximally mixed $ν_μ - ν_e$, (C) threefold maximal mixing between $ν_e, ν_μ$ and $ν_τ$, and (D) neutrino oscillations via Equivalence Princi

M. Carena, M. Quiros, C. E. M. Wagner

It has been recently shown that the observed baryon number may originate at the electroweak phase transition, provided that the Higgs boson and the lightest stop are sufficiently light. In this work, we perform a detailed analysis, including all dominant two-loop finite temperature corrections to the Higgs effective potential, as well as the non-trivial effe

Junko Shigemitsu, Colin J. Morningstar

A one-loop matching calculation between Lattice NRQCD and full QCD for the heavy-light axial current is described and the effects on f_B are discussed.

G. M. de Divitiis, R. Petronzio

By imposing axial and vector Ward identities for flavour-non-singlet currents, we estimate in the quenched approximation the non-perturbative values of combinations of improvement coefficients, which appear in the expansion around the massless case of the renormalization constants of axial, pseudoscalar, vector, scalar non-singlet currents and of the renorma

P. Bialas, Z. Burda, J. Jurkiewicz

We study the two-point correlation function in the model of branched polymers and its relation to the critical behaviour of the model. We show that the correlation function has a universal scaling form in the generic phase with the only scale given by the size of the polymer. We show that the origin of the singularity of the free energy at the critical point

C. T. H. Davies, A. J. Lidsey, H. P. Shanahan

We present an analysis of the mass spectrum of heavy quarkonia with non-degenerate quark masses. The heavier (bottom) valence quark is treated in a non-relativistic fashion and the other (charm) is a relativistic Wilson-like quark using the improved SW action. Such states provide and interesting probe between the relativistic B meson states and the non-relat

Kurt Langfeld, Hugo Reinhardt, Oliver Tennert

The magnetic vortices which arise in SU(2) lattice gauge theory in center projection are visualized for a given time slice. We establish that the number of vortices piercing a given 2-dimensional sheet is a renormalization group invariant and therefore physical quantity. We find that roughly 2 vortices pierce an area of 1 fm^2.

J. F. Markham, T. D. Kieu

A simulation method based on the RG blocking is shown to yield statistical errors smaller than that of the crude MC using absolute values of the original measures. The new method is particularly suitable to apply to the sign problem of indefinite or complex-valued measures. We demonstrate the many advantages of this method in the simulation of 2D Ising model

S. L. Shapiro

We present a simple model illustrating how a highly relativistic, compact object which is stable in isolation can be driven dynamically unstable by the tidal field of a binary companion. Our compact object consists of a test-particle in a relativistic orbit about a black hole; the binary companion is a distant point mass. Our example is presented in light of

H. P. de Oliveira, Rudnei O. Ramos

We examine the solutions of the equations of motion for an expanding Universe, taking into account the radiation of the inflaton field energy. We then analyze the question of the generality of inflationary solutions in this more general setting of a dissipative system. We find a surprisingly rich behavior for the solutions of the dynamical system of equation

K. A. Bronnikov, C. P. Constantinidis, R. L. Evangelista, J. C. Fabris

We study the possible existence of black holes in scalar-tensor theories of gravity in four dimensions. Their existence is verified for anomalous versions of these theories, with a negative kinetic term in the Lagrangian. The Hawking temperature T_H of these holes is zero, while the horizon area is (in most cases) infinite. It is shown that an infinite value

E. Atasoy, T. Dereli, M. Onder

The N=2 supergravity action in D=5 is generalized by the inclusion of dimensionally continued Euler-Poincare form. The spacetime torsion implied by the Einsteinean supergravity is imposed by a Lagrangian constraint and resulting variational equations are solved for the Lagrange multipliers. The corresponding terms in the Einstein and Rarita-Schwinger field e

P. V. Moniz

In this paper we report whether conserved currents can be sensibly defined in supersymmetric minisuperspaces. Our analysis deals with a k=1 FRW model. Supermatter in the form of scalar supermultiplets is included. We show that conserved currents cannot be adequately established except for some very simple scenarios.

Weiping Li

We show that there is a well-defined cap-product structure on the Fintushel-Stern spectral sequence. Hence we obtain the induced cap-product structure on the ${\BZ}_8$-graded instanton Floer homology. The cap-product structure provides an essentially new property of the instanton Floer homology, from a topological point of view, which multiplies a finite dim

I. J. Maasilta, V. J. Goldman

We report experiments on the energy structure of antidot-bound states. By measuring resonant tunneling line widths as function of temperature, we determine the coupling to the remote global gate voltage and find that the effects of interelectron interaction dominate. Within a simple model, we also determine the energy spacing of the antidot bound states, sel

A. E. Duwel, S. Watanabe, E. Trias, T. P. Orlando

New resonance steps are found in the experimental current-voltage characteristics of long, discrete, one-dimensional Josephson junction arrays with open boundaries and in an external magnetic field. The junctions are underdamped, connected in parallel, and DC biased. Numerical simulations based on the discrete sine-Gordon model are carried out, and show that

Pijush K. Ghosh, Avinash Khare, M. Sivakumar

Using the ideas of supersymmetry and shape invariance we re-derive the spectrum of the $A_{N-1}$ and $BC_N$ Calogero-Sutherland model. We briefly discuss as to how to obtain the corresponding eigenfunctions. We also discuss the difficulties involved in extending this approach to the trigonometric models.

P. Fendley, A. W. W. Ludwig, H. Saleur

In a series of papers we combined the Bethe ansatz with a kinetic (Boltzmann) equation in order to compute exactly transport properties in a Luttinger liquid with an impurity. In a recent comment [cond-mat/9708163], Skorik claimed that while our results were correct in linear response, there was a ``serious flaw&#39;&#39; in our calculation at finite voltage

Mauricio Barahona, Shinya Watanabe

When magnetic flux moves across layered or granular superconductor structures, the passage of vortices can take place along channels which develop finite voltage, while the rest of the material remains in the zero-voltage state. We present analytical studies of an example of such mixed dynamics: the row-switched (RS) states in underdamped two-dimensional Jos