October 1995 arXiv papers — page 12

J. H. Kung

In this paper, we study Raychaudhuri's equation in the background of $R + βR^2$ gravity with a phenomenological matter ($ρ\propto a(t)^{-n}$). We conclude that even though the Strong Energy Condition (S.E.C.) for Einstein's gravity, which guarantees singularity, is $n\geq 2$ for $ρ\propto a(t)^{-n}$, a perturbative analysis of Raychaudhuri's equa

Eduard Prugovecki

The basic properties of Poincare gauge invariant Hilbert bundles over Lorentzian manifolds are derived. Quantum connections are introduced in such bundles, which govern a parallel transport that is shown to satisfy the strong equivalence principle in the quantum regime. Path-integral expressions are presented for boson propagators in Hilbert bundles over glo

Andrew Chamblin, G. W. Gibbons

In this lecture we address some topological questions connected with the existence on a general spacetime manifold of diffeomorphisms connected to the identity which reverse the time-orientation.

Kiyoshi Shiraishi, Takuya Maki

We consider an $N$-body system of charged particle coupled to gravitational, electromagnetic, and scalar fields. The metric on moduli space for the system can be considered if a relation among the charges and mass is satisfied, which includes the BPS relation for monopoles and the extreme condition for charged black holes. Using the metric on moduli space in

Sergio Ferreira Cortizo

It is shown that theories already presented as rigorous mathematical formalizations of widespread manipulations of Dirac's delta function are all unsatisfactory, and a new alternative is proposed.

Sergio Ferreira Cortizo

A simultaneous extension of real numbers set and the class of real functions is discussed.

Sergio Ferreira Cortizo

An alternative organization for Differential and Integral Calculus, based on an extension of real numbers that include infinitesimal and infinite quantities, is presented. Only Elementary Set Theory is used, without reference to methods or results from Mathematical Logic.

Sergio Ferreira Cortizo

A process of extending sets which can be used as foundation for an alternative organization for Differential and Integral Calculus is presented.

Th. Pruschke, Th. Obermeier, J. Keller, M. Jarrell

We present $\vec{k}$-dependent one-particle spectra and corresponding effective bandstructures for the $2d$ Hubbard model calculated within the dynamical molecular field theory (DMFT). This method has proven to yield highly nontrivial results for a variety of quantities but the question remains open to what extent it is applicable to relevant physical situat

Marcus Kasner, A. H. MacDonald

The two-dimensional interacting electron gas at Landau level filling factor $ν=1$ and temperature $T=0$ is a strong ferromagnet; all spins are completely aligned by arbitrarily weak Zeeman coupling. We report on a theoretical study of its thermodynamic properties using a many-body perturbation theory approach and concentrating on the recently measured temper

German Rigau, Eneko Agirre

This paper explores the acquisition of conceptual knowledge from bilingual dictionaries (French/English, Spanish/English and English/Spanish) using a pre-existing broad coverage Lexical Knowledge Base (LKB) WordNet. Bilingual nominal entries are disambiguated agains WordNet, therefore linking the bilingual dictionaries to WordNet yielding a multilingual LKB

Eneko Agirre, German Rigau

This paper presents a method for the resolution of lexical ambiguity and its automatic evaluation over the Brown Corpus. The method relies on the use of the wide-coverage noun taxonomy of WordNet and the notion of conceptual distance among concepts, captured by a Conceptual Density formula developed for this purpose. This fully automatic method requires no h

S. A. Corcelli, J. D. Kress, L. R. Pratt, G. J. Tawa

This paper describes a mixed direct-iterative method for boundary integral formulations of dielectric solvation models. We give an example for which a direct solution at thermal accuracy is nontrivial and for which Gauss-Seidel iteration diverges in rare but reproducible cases. This difficulty is analyzed by obtaining the eigenvalues and the spectral radius

G. Hummer, S. Garde, A. E. Garcia, A. Pohorille

Hydrophobic interactions provide driving forces for protein folding, membrane formation, and oil-water separation. Motivated by information theory, the poorly understood nonpolar solute interactions in water are investigated. A simple heuristic model of hydrophobic effects in terms of density fluctuations is developed. This model accounts quantitatively for

E. T. Harlaftis, T. R. Marsh

We present observations of OY Car, obtained with the Anglo-Australian telescope, during a normal outburst in 1991. Two sinusoidal components are resolved in the Hbeta trailed spectra and we determine the location of the narrow component to be on the secondary star with a maximum contributed flux of ~2.5 per cent to the total flux. Imaging of the line distrib

Gilbert P. Holder, Lawrence M. Widrow

It is widely believed that dark matter halos are flattened, that is closer to oblate than prolate. The evidence cited is based largely on observations of galaxies which do not look anything like our own and on numerical simulations which use ad hoc initial conditions. Given what we believe to be a ``reasonable doubt'' concerning the shape of dark Gal

R. R. Ross, A. C. Fabian, W. N. Brandt

We consider the spectra of Thomson-thick, geometrically-thin accretion discs around Galactic black hole candidates in the reflection model and compute their iron K edges and iron K$α$ lines. We compare the smeared iron K edge profiles that we compute with observation and find them to be a satisfactory description of the data. We find that a combination of Do

M. Ruffert

We investigate the hydrodynamics of three-dimensional classical Bondi-Hoyle accretion. A totally absorbing sphere of different sizes (1, 0.1 and 0.02 accretion radii) moves at different Mach numbers (0.6, 1.4, 3.0 and 10) relative to a homogeneous and slightly perturbed medium, which is taken to be an ideal, nearly isothermal, gas ($γ=1.01$). The hydrodynami

S. Rauzy, R. Triay

In a previous paper, we have demonstrated the importance to define a statistical model describing the observed linear correlation between the absolute magnitude $M$ and the log line width distance indicator $p$ of galaxies (the Tully-Fisher relation). As long as the same statistical model is used during the calibration step of the relation and the step of th

Robin Tuluie, Pablo Laguna, Peter Anninos

We investigate the imprint of nonlinear matter condensations on the Cosmic Microwave Background (CMB) in $Ω_{0}<1$ cold dark matter (CDM) model universes. We consider simulation domains ranging from $120h^{-1}$ Mpc to $360h^{-1}$ Mpc in size. We concentrate on the secondary temperature anisotropies induced by time varying gravitational potentials occurring a

R. Triay, S. Rauzy, M. Lachièze-Rey

This paper completes the statistical modeling of the Hubble flow when a Tully-Fisher type relation is used for estimating the absolute magnitude $M\approx a\,p+b$ from a line width distance indicator $p$. Our investigation is performed with the aim of providing us with a full understanding of statistical biases due to selection effects in observation, regard

S. Rauzy, M. Lachièze-Rey, R. N. Henriksen

In this article we give an account of a method of smoothing spatial inhomogeneous data sets by using wavelet reconstruction on a regular grid in an auxilliary space onto which the original data is mapped. In a previous paper by the present authors, we devised a method for inferring the velocity potential from the radial component of the cosmic velocity field

N. W. Evans

Disk-halo models of the Galaxy and LMC are constructed and used to analyse the microlensing data-set. Deflectors in the LMC bar, disk and halo provide an optical depth to microlensing of $\sim 2 \times 10^{-7}$. Deflectors in the Galactic disk and halo contribute $\sim 5 \times 10^{-7}$. The extent, flattening and velocity anisotropy of the dark objects in t

J. Greiner

Neither a flaring nor a quiescent counterpart to a gamma-ray burst has yet been convincingly identified at any wavelength region. The present status of the search for counterparts of classical gamma-ray bursts is given. Particular emphasis is put on the search for flaring counterparts, i.e. emission during or shortly after the gamma-ray emission.

F. Sylos Labini, L. Amendola

We study the behaviour of the power spectrum (PS) in the case of fractal structures. We show that in this case the main observational features of the PS, the large scale flattening and the scaling of the amplitude with sample depth, are related to finite size effects, due to the fractal nature of galaxy distribution in the sample. Comparing with the recent r

Biman B. Nath, Shiv K. Sethi

We point out the peculiarities of the line of sight of Q0302-003 which was recently used to estimate the He II opacity at $z \sim 3.285$. This line of sight contains a large void in Lyman $α$ clouds, in the region used for the He II opacity observation, and the void is thought to be caused by the ionizing radiation from a foreground quasar (Dobrzycki and Bec

Neil J. Cornish, Janna J. Levin

In order to draw out the essential behavior of the universe, investigations of early universe cosmology often reduce the complex system to a simple integrable system. Inflationary models are of this kind as they focus on simple scalar field scenarios with correspondingly simple dynamics. However, we can be assured that the universe is crowded with many inter

Albert Stebbins, Tim Mckay, Joshua A. Frieman

While the strategy for the first applications of weak lensing has been to ``go deep&#39;&#39; it is equally interesting to use one&#39;s telescope time to instead ``go wide&#39;&#39;. The Sloan Survey (SDSS) provides a natural framework for a very wide area weak lensing survey.

H. C. Rosu, J. Socorro, O. Obregón

After a short outline of the factorization and Grassmann picture of the one-dimensional (1D) Fokker-Planck (FP) equation, we consider a class of spatially-inhomogeneous solutions of the 2D FP equation with symmetric 2D (super)potentials. We show that the spatial inhomogeneities of that class of solutions can be attributed to underlying Grassmannian pseudo-de

R. Bertolotti, G. Contreras, L. A. Núñez, U. Percoco

We present a counter example to a theorem given by Amir {\em et al.} J. Math. Phys. {\bf 35}, 3005 (1994). We also comment on a misleading statements of the same reference.

Tibor Torma

We look at the Equivalence Theorem as a statement about the absence of polynomial infrared divergences when $m_W \rightarrow 0$. We prove their absence in a truncated toy model and conjecture that, if they exist at all, they are due to couplings between light particles.

N. E. Mavromatos, Elizabeth Winstanley

We analyze (3+1)-dimensional black-hole space-times in spontaneously broken Yang-Mills gauge theories that have been recently presented as candidates for an evasion of the scalar-no-hair theorem. Although we show that in principle the conditions for the no-hair theorem do not apply to this case, however we prove that the `spirit&#39; of the theorem is not vi

E. Alfinito, M. Blasone, A. Iorio, G. Vitiello

By resorting to recent results on fermion mixing which show that the Fock space of definite flavor states is unitarily inequivalent to the Fock space of definite mass states, we discuss the phenomenological implications on the neutrino oscillation formula. For finite momentum the oscillation amplitude is depressed, or &#34;squeezed&#34;, by a momentum depend

R. Calabrese, V. Guidi, P. Lenisa, E. Mariotti

A novel diagnostic method to detect ordering within one-dimensional ion beams in a storage ring is presented. The ions are simultaneously excited by a ultrashort pulsed laser ($\simeq 1$ ps) at two different locations along the beam and fluorescence is detected by a group of four photo-multipliers. Correlation in fluorescence signals is a firm indication tha

Volodimir Lyubashenko, Anthony Sudbery

It is shown that the quantised enveloping algebra of sl(n) contains a quantum Lie algebra, defined by means of axioms similar to Woronowicz&#39;s., This gives rise to Lie algebra-like generators and relations for the locally finite part of the quantised enveloping algebra, and suggests a canonical Poincare-Birkhoff-Witt basis.

J. A. Gomez Tejedor, F. Cano, E. Oset

The gamma p ---> pi+ pi- p reaction, in combination with data from the pi N ---> pi pi N reaction, allows one to obtain the s- and d-wave amplitudes for the N*(1520) decay into Delta pi with absolute sign with respect to the N*(1520) ---> N gamma helicity amplitudes. In addition one obtains the novel information on the q dependence of the amplitudes. This de

H. G Dosch, S. Narison

To leading order in $α_s$, we evaluate the leading and non-leading $1/M_b$ corrections to the $B^*Bπ$ and $B^*Bγ$ couplings using QCD spectral moment sum rules in the full theory. We find that, for large $M_b$ and contrary to the heavy-to-light $B\rar π(ρ) l\bar ν$ form factors, which are dominated by the $soft$ light quark vacuum condensate, these couplings

Yujiro Kawamata

The result on 3-fold is now optimal by the result of Ein-Lazarsfeld and Helmke.

Xiao-Song Lin

This is a survey on the current status of the study of finite type invariants of integral homology 3-spheres based on lectures given in the workshop on knot theory at Banach International Center of Mathematics, Warsaw, July 1995. As a new result, we show that the space of finite type invariants of integral homology 3-spheres is a graded polynomial algebra ge

J. E. Amaro, J. A. Caballero, T. W. Donnelly, A. M. Lallena

The electromagnetic and weak neutral current matrix elements that enter in the analysis of parity-violating quasielastic electron scattering are calculated using a continuum nuclear shell model. New approximations to the on-shell relativistic one-body currents and relativistic kinematics for use in such models are developed and discussed in detail. Results a

K. C. Chase, A. Z. Mekjian

An exactly solvable model of nuclear fragmentation is shown to lead to a simple connection between the critical point multiplicity $\langle m \rangle_{c}$ and the critical point exponent $τ$ recently reported on in the EOS collaboration. The importance of multiplicity fluctuations on critical point behavior is also discussed.

G. Faeldt, C. Wilkin

The cross section for the reaction $dd\rightarrow \,^4\!H\!e\,η$ close to threshold is estimated in a two-step model, similar to that which successfully describes near-threshold $pd\rightarrow \,^3\!H\!e\,η$ production. A $π$-meson, created in a $dp\rightarrow \,^3\!H\!e\,π^o$ process on one nucleon in the target deuteron, is converted into an $η$-meson by a

G. F. Bertsch, P. Danielewicz

Off-shell propagation of nucleons is neglected in one-body transport models of heavy-ion collisions, but it could be significant in processes that are limited by phase space, such as the threshold production of heavy particles. We estimate the relative magnitude of off-shell production to on-shell production of the N$^*$(1535) resonance in heavy ion collisio

Dimitri Kusnezov, David Mitchell

We explore the behavior of collective nuclear excitations under a multi-parameter deformation of the Hamiltonian. The Hamiltonian matrix elements have the form $P(|H_{ij}|)\propto 1/\sqrt{|H_{ij}|}\exp(-|H_{ij}|/V)$, with a parametric correlation of the type $\log \langle H(x)H(y)\rangle\propto -|x-y|$. The studies are done in both the regular and chaotic re

W. M. Zhang, R. Madey, J. Schambach, M. Elaasar

We measured neutron triple-differential cross sections from multiplicity-selected Au-Au collisions at 150, 250, 400, and 650 \AMeV. The reaction plane for each collision was estimated from the summed transverse velocity vector of the charged fragments emitted in the collision. We examined the azimuthal distribution of the triple-differential cross sections a

H. P. Nilles, S. Stieberger

Effective theories with the matter content of the minimal supersymmetric Standard Model below the string scale M_string predict a wrong value for the weak--mixing angle sin^2θ_W and strong coupling constant α_S at the scale M_Z. To resolve this problem one needs large threshold corrections. At the same time one would like to avoid introducing new intermediat

Leung Chim

The Tricritical Ising model perturbed by the subleading energy operator Φ_(3/5) was known to be an Integrable Scattering Theory of massive kinks and in fact preserves supersymmetry. We consider here the model defined on the half-plane with a boundary and computed the associated factorizable boundary S-matrix. The conformal boundary conditions of this model w

M. Moshinsky, C. Quesne, Yu. F. Smirnov

Some years ago, one of the authors~(MM) revived a concept to which he gave the name of single-particle Dirac oscillator, while another~(CQ) showed that it corresponds to a realization of supersymmetric quantum mechanics. The Dirac oscillator in its one- and many-body versions has had a great number of applications. Recently, it included the analytic expressi

W. Roberts, F. Ledroit

We examine the measured rates for the decays $D\to K^{(*)}\ellν$, $B\to K^{(*)}ψ^{(\prime)}$ and $B\to K^*γ$ in a number of scenarios, in the framework of the heavy quark effective theory. We attempt to find a scenario in which all of these decays are described by a single set of form factors. Once such a scenario is found, we make predictions for the rare d

J. Lopez, D. Nanopoulos

We show that the presence of an anomalous $\rm U_A(1)$ factor in the gauge group of string-derived models may have the new and important phenomenological consequence of allowing the vanishing of ${\rm Str}\,{\cal M}^2$ in the ``shifted&#34; vacuum, that results in the process of cancelling the anomalous $\rm U_A(1)$. The feasibility of this effect seems to b

E. Gabrielli, A. Masiero, L. Silvestrini

We consider FCNC and CP violating processes mediated by gluino exchange in generalized supersymmetric theories. We present the constraints on flavour (F) changing squark mass terms at the electroweak energy scale, focusing our analysis on $ΔF = 2$ transitions. Results are also given for $ΔF = 1$ CP conserving processes both in the hadronic and leptonic secto

N. Brambilla, G. M. Prosperi

We review our recent results \cite{bsult} on the derivation of a B-S equation in QCD in a Wilson loop context. We work in a second order formalism, use the Feynman--Schwinger path integral representation for a quark in external field and obtain a similar expression for a quark--antiquark amplitude in which the gauge fields appears only through the Wilson loo

Jarkko Ahonen, Kari Enqvist, Georg Raffelt

In the presence of primordial magnetic fields the oscillating cosmic axion field drives an oscillating electric field. The ensuing dissipation of axions is found to be inversely proportional to the conductivity of the primordial plasma. This counterintuitive result is essentially equivalent to ``Zeno&#39;s paradox&#39;&#39; or the ``watched-pot effect&#39;&#

P. Chiappetta, F. M. Renard, C. Verzegnassi

We consider the virtual signals of a $Z&#39;$ of very general type in the process $e^+e^-\to W^+W^-$ at a future linear collider (NLC). We show that possible deviations from the SM predictions in this channel are related to similar deviations in the purely leptonic one in a way that is only characteristic of this $Z&#39;$ model, and not in general of possibl

G. Thorleifsson, S. Catterall

We propose a new real-space renormalization group transformation for dynamical triangulations. It is shown to preserve geometrical exponents such as the string susceptibility and Hausdorff dimension. We furthermore show evidence for a fixed point structure both in pure gravity and gravity coupled to a critical Ising system. In the latter case we are able to

William A. Hiscock

The Euclidean action is calculated in the thin-wall approximation for a first-order vacuum phase transition in which the bubble appears symmetrically around either a global monopole or a gauge cosmic string. The bubble is assumed to be much larger than the core size of the monopole or string. In both cases the value of the Euclidean action is shown to be red

Alpan Raval, B. L. Hu, James Anglin

We analyze the statistical mechanical properties of n-detectors in arbitrary states of motion interacting with each other via a quantum field. We use the open system concept and the influence functional method to calculate the influence of quantum fields on detectors in motion, and the mutual influence of detectors via fields. We discuss the difference betwe

K. K. Likharev, K. A. Matsuoka

We have calculated the spatial distribution of the electrostatic potential created by an unbalanced charge $q$ in one of the conducting electrodes of a long, uniform, linear array of small tunnel junctions. The distribution describes, in particular, the shape of a topological single-electron soliton in such an array. An analytical solution obtained for a cir

Yi Wan, Gerardo Ortiz, Philip Phillips

We propose here a model for the pair tunneling states observed by Ashoori and co-workers (Phys. Rev. Lett. {\bf 68}, 3088 (1992)) in GaAs quantum dots. We show that while GaAs is a weakly-polar semiconductor, coupling to optical phonons is sufficiently strong to mediate a negative-U pairing state. The physical potential in which the two electrons are bound c

Yu-Liang Liu

We have proposed a model Hamiltonian, which describes a simple physical picture that the holes with single occupation constraint introduced by doping move in the antiferromagnetic background of the copper spins, to describe the normal state of the cuprate superconducting materials, and used the renormalization group method to calculate its anomalous magnetic

M. B. Walker

The effect of orthorhombicity on Josephson tunneling in high T$_c$ superconductors such as YBCO is studied for both single crystals and highly twinned crystals. It is shown that experiments on highly twinned crystals experimentally determine the symmetry of the superconducting twin boundaries (which can be either even or odd with respect to a reflection in t

N. Taniguchi, B. S. Shastry, B. L. Altshuler

We investigate the relation between the invariant correlators of random matrix theory and correlators of the integrable one-dimensional systems. Starting from the relation between correlators for the coupling strengths $λ=1/ 2$, $1$, and $2$, we explore the local current-density mapping applicable to arbitrary $λ$ including {\em irrational\/} values, which r

R. Schack, T. A. Brun, I. C. Percival

Quantum state diffusion (QSD) as a tool to solve quantum-optical master equations by stochastic simulation can be made several orders of magnitude more efficient if states in Hilbert space are represented in a moving basis of excited coherent states. The large savings in computer memory and time are due to the localization property of the QSD equation. We sh

Andi Burkert, Peter Bodenheimer

Hydrodynamical calculations in three space dimensions of the collapse of an isothermal, centrally condensed, rotating 1 M\sol protostellar cloud are presented. A numerical algorithm involving nested subgrids is used to resolve the region where fragmentation occurs in the central part of the protostar. A previous calculation by Boss, which produced a hierarch

Smita Mathur, Martin Elvis, K. P. Singh

We present $\it {ASCA}$ observations of the z=1.98 prototype BALQSO: PHL5200. The source was detected in both SIS and GIS. A power-law spectrum ($α_E = 0.6^{+0.9}_{-0.6}$) with large intrinsic absorption (N$_H = 1.3^{+2.3}_{-1.1} \times 10^{23}$ cm$^{-2}$) best describes the spectrum. Excess column density over the local Galactic value is required at the 99\

Vladimir I. Pariev

Bondi type hydrodynamic accretion of the surrounding matter onto Kerr black hole with an arbitrary rotational parameter is considered. The effects of viscosity, thermal conductivity and interaction with radiation field are neglected. The black hole is supposed to be at rest with respect to matter at infinity. The flow is adiabatic and has no angular momentum

J. G. Skibo, C. D. Dermer

We show that Compton scattering of soft photons with energies near 100 eV in thermally stratified black-hole accretion plasmas with temperatures in the range 100 keV - 1 MeV can give rise to an X-ray spectral hardening near 10 keV. This could produce the hardening observed in the X-ray spectra of black holes, which is generally attributed to reflection or pa

Belinda J. Wilkes, Gary D. Schmidt, Paul S. Smith, Smita Mathur

The sub-parsec masing disk recently found to be orbiting a central mass of $\sim3.6\times10^7$~\msun\ in the Seyfert/LINER galaxy NGC~4258 provides the most compelling evidence to date for the existence of a massive black hole in the nucleus of a galaxy. The disk is oriented nearly edge-on %($\bf i=83$°) and the X-ray spectrum %(Makishima \etal\ 1994) is hea

Geoffrey T. Bodwin

We present a method for formulating gauge theories of chiral fermions in lattice field theory. The method makes use of a Wilson mass to remove doublers. Gauge invariance is then restored by modifying the theory in two ways: the magnitude of the fermion determinant is replaced with the square root of the determinant for a fermion with vector-like couplings to

V. V. Skalozub, A. Y. Tishchenko

The effective Lagrangian of arbitrary varying in space electromagnetic field in a dense medium is derived. It has been used for investigation of interaction between charged fermions in the medium. It is shown the possibility for the formation of metastable electron bound states in the medium when external magnetic field is applied.

Sandip K. Chakrabarti, Lev G. Titarchuk

We study the spectral properties of a very general class of accretion disks which can be decomposed into three distinct components apart from a shock at $r=r_s$: (1) An optically thick Keplerian disk on the equatorial plane ($r>r_s$), (2) A sub-Keplerian optically thin halo above and below this Keplerian disk $r>r_s$ and (3) A hot, optically slim, $τ\sim 1$

Antti J. Niemi

We suggest that four dimensional massive gauge vectors could be described by coupling ordinary Yang-Mills theory to a topological gauge theory. For this the coupling should excite a nontrivial degree of freedom from the topological theory, corresponding to the longitudinal polarization of a massive gauge vector. If the coupling can be selected so that furthe

R. Bijker, F. Iachello, A. Leviatan

We study the electromagnetic form factors of the nucleon in a collective model of baryons. Using the algebraic approach to hadron structure, we derive closed expressions for both elastic and transition form factors, and consequently for the helicity amplitudes that can be measured in electro- and photoproduction. Effects of spin-flavor symmetry breaking and

Lev A. Borisov

We consider Siegel upper half space of rank two ${\cal H}^2$ and different subgroups $H\subseteq {\bf Sp(4,Z)}$ of finite index. The purpose of this paper is to prove that the field of rational functions of ${\cal H}^2/H$ has general type for all but the finite number of $H$.

G. E. Volovik

An attempt is made to promote an analogy between quantized vortex in condensed matter and black hole: both compact objects have fermion zero modes which induce the finite temperature of these objects. The motion of the quantized vortex lines in Fermi superfluids and superconductors leads to the spectral flow of fermion zero mode. This results in finite tempe

N. V. Krasnikov, A. A. Pivovarov

We suggest a method of summing the perturbation theory (PT) asymptotic series related to infrared (IR) renormalons in QCD by using special renormalization schemes in which the running coupling can be integrated over the region of small momenta. For the method to work, one should consider higher order PT corrections to the standard bubble-chain diagrams. High

Roland Ketzmerick

It is shown that conductance fluctuations due to phase coherent ballistic transport through a chaotic cavity generically are fractals. The graph of conductance vs. externally changed parameter, e.g. magnetic field, is a fractal with dimension D=2-b/2 between 1 and 2. It is governed by the exponent b (<2) of the power law distribution P(t) ~ t^{-b} for a clas

G. V. Grigoryan, R. P. Grigoryan, I. V. Tyutin

A pseudoclassical theory of Weyl particle in the space--time dimensions $D=2n$ is constructed. The canonical quantization of that pseudoclassical theory is carried out and it results in the theory of the $D=2n$ dimensional Weyl particle in the Foldy--Wouthuysen representation. A quantum mechanics of the neutral Weyl particle in even--dimensional space--time

David H Lyth, Ewan D Stewart

In supersymmetric theories a field can develop a vacuum expectation value $M \gg 10^3\,{\rm GeV}$, even though its mass $m$ is of order $10^2$ to $10^3\,{\rm GeV}$. The finite temperature in the early Universe can hold such a field at zero, corresponding to a false vacuum with energy density $ V_0 \sim m^2 M^2 $. When the temperature falls below $V_0^{1/4}$,

Nuel Belnap, Laszlo E. Szabo

Greenberger, Horne, Shimony and Zeilinger gave a new version of the Bell theorem without using inequalities (probabilities). Mermin summarized it concisely; but Bohm and Hiley criticized Mermin&#39;s proof from contextualists&#39; point of view. Using the Branching Space-time language, in this paper a proof will be given that is free of these difficulties. A

Hong-Chen Fu, Ryu Sasaki

We propose a displacement-operator approach to some aspects of squeezed states for general multiphoton systems. The explicit displacement-operators of the squeezed vacuum and the coherent states are achieved and expresses as the ordinary exponential form. As a byproduct the coherent states of the $q$-oscillator are obtained by the {\it usual exponential} dis

SESAM-Collaboration, :, U. Glässner, S. Güsken

First results of a recently started simulation of full QCD with two flavours of sea-quarks at a coupling of $\beta = 5.6$ on a $16^3 \times 32$ lattice are presented. Emphasis is laid on the statistical significance that can be achieved by an ``integrated luminosity'' of 140 TFlop$\times$hrs, for Hybrid Monte Carlo simulations at four intermediate values of

Laszlo Feher

The generalized Drinfeld-Sokolov construction of KdV systems is reviewed in the case of an arbitrary affine Lie algebra paying particular attention to Hamiltonian aspects and $\W$-algebras. Some extensions of known results as well as a new interpretation of the construction are also presented.

V. Freilikher, E. Kanzieper, I. Yurkevich

Unitary ensembles of large N x N random matrices with a non-Gaussian probability distribution P[H] ~ exp{-TrV[H]} are studied using a theory of polynomials orthogonal with respect to exponential weights. Asymptotically exact expressions for density of levels, one- and two-point Green&#39;s functions are calculated. We show that in the large-N limit the prope

C. Frønsdal

A large family of &#34;standard&#34; coboundary Hopf algebras is investigated. The existence of a universal R-matrix is demonstrated for the case when the parameters are in general position. Special values of the parameters are characterized by the appearance of certain ideals; in this case the universal R-matrix exists on the associated algebraic quotient.

C. Quesne, N. Vansteenkiste

In a recent paper (1994 {\sl J.\ Phys.\ A: Math.\ Gen.\ }{\bf 27} 5907), Oh and Singh determined a Hopf structure for a generalized $q$-oscillator algebra. We prove that under some general assumptions, the latter is, apart from some algebras isomorphic to su$_q$(2), su$_q$(1,1), or their undeformed counterparts, the only generalized deformed oscillator algeb

J. M. Holender, M. J. Gillan

Ab initio molecular dynamics simulation is used to study the structure and electronic properties of the liquid Ga-Se system at the three compositions Ga$_2$Se, GaSe and Ga$_2$Se$_3$, and of the GaSe and Ga$_2$Se$_3$ crystals. The calculated equilibrium structure of GaSe crystal agrees well with available experimental data. The neutron-weighted liquid structu

S. V. Ketov

Based on our previous studies of the BRST cohomology of the critical N=2 strings, we construct the loop measure and make explicit the role of the spectral flow at arbitrary genus and Chern class, in a holomorphic field basis. The spectral flow operator attributes to the existence of the hidden `small&#39; N=4 superconformal symmetry which is non-linearly rea

C. M. Becchi, C. Imbimbo

We point out that averages of equivariant observables of 2D topological gravity are not globally defined forms on moduli space, when one uses the functional measure corresponding to the formulation of the theory as a 2D superconformal model. This is shown to be a consequence of the existence of the Gribov horizon {\it and} of the dependence of the observable

Amihay Hanany

Families of hyper-elliptic curves which describe the quantum moduli spaces of vacua of $N=2$ supersymmetric $SO(N_c)$ gauge theories coupled to $N_f$ flavors of quarks in the vector representation are constructed. The quantum moduli spaces for $2N_f < N_c-1$ are determined completely by imposing $R$-symmetry, instanton corrections and the proper classical si

Thais L. Lungov, Carlos O. Escobar

The possibility of distinguishing between two higgs production mechanisms, W fusion and gluon fusion, is investigated using the Monte Carlo event generator PYTHIA. It is shown that, considering the designed CM energy and luminosity for the LHC, it is not possible to distinguish between the two higgs production processes as, for a given integrated luminosity,

Kingman Cheung, Tzu Chiang Yuan

At the large transverse momentum region, the production of heavy-heavy bound-states such as charmonium, bottomonium, and $\bar bc$ mesons in high energy $e^+e^-$ and hadronic collisions is dominated by parton fragmentation. We calculate the heavy quark fragmentation functions into the D-wave quarkonium and $\bar bc$ mesons to leading order in the strong coup

Pengfei Zhuang, Ulrich Heinz

We derive the kinetic equations for both the covariant and equal-time Wigner functions of Dirac particles with electromagnetic, scalar and pseudoscalar interactions. We emphasize the constraint equations for the spinor components in the equal-time formulation.

Pyungwon Ko, Jungil Lee, H. S. Song

It is pointed out that the radiative decays of a $ϕ$ meson, $\phirho$ and $\phiom$, receive dominant contributions from the pseudoscalar ($P = η, η^{&#39;}$) exchanges. Using the vector meson dominance model, we find that $B (\phirho) \approx 1.3 \times 10^{-4}$ and $B (\phiom) \approx 1.5 \times 10^{-5}$, which are mainly from the $η^{&#39;}$ pole. Thus, th

C. Michael

The lattice gauge theory technique for non-perturbative calculations in QCD is reviewed. The extraction of the continuum limit of lattice results is discussed with particular examples appropriate to hadron spectroscopy (the light hadrons and the glueballs). The determination of the strong coupling constant is presented. The lattice approach to the evaluation

Pyungwon Ko, Jungil Lee, H. S. Song

The inclusive $S-$wave charmonium production rates in $B$ decays are considered using the Bodwin-Braaten-Lepage (BBL) approach, including the relativistic corrections and the color-octet mechanism suggested as a possible solution to the $ψ^{&#39;}$ puzzle at the Tevatron. We first consider relativistic and radiative corrections to $J/ψ\rightarrow e^{+} e^{-}

Jisuke Kubo, Myriam Mondragon, George Zoupanos

Gauge-Yukawa Unification (GYU) yields a functional relation among the gauge and Yukawa couplings, and it may follow from the usual Grand Unification if it is supplemented with some additional principles. Postulating the principles of finiteness and reduction of couplings, we have achieved Gauge-Yukawa Unification in various supersymmetric unified models lead

Peter D. Olmsted, Eugene M. Terentjev

The fluctuation spectrum of membranes in nematic solvents is altered by the boundary condition imposed on the bulk nematic director by the curved membrane. We discuss some properties of single and multi-membrane systems in nematic solvents, primarily based on the Berreman-de~Gennes model. We show that: membranes in nematic solvents are more rigid and less ro

T. Chou, D. R. Nelson

We study the interplay between an isostructural critical point and dislocation mediated two-dimensional melting, using a combination of Landau and continuum elasticity theory. If dislocations are excluded, coupling to the elastic degrees of freedom leads to mean field critical exponents. When dislocations are allowed, modified elastic constants lead to a new

N. Kawashima, A. P. Young

We have studied the three-dimensional Ising spin glass with a $\pm J$ distribution by Monte Carlo simulations. Using larger sizes and much better statistics than in earlier work, a finite size scaling analysis shows quite strong evidence for a finite transition temperature, $T_c$, with ordering below $T_c$. Our estimate of the transition temperature is rathe