September 1995 arXiv papers — page 4

Yan Zhou, C. D. Lin

Hyperspherical close-coupling method is used to calculate the elastic, positronium formation and excitation cross sections for positron collisions with atomic hydrogen at energies below the H(n=4) threshold for the J=2 partial wave. The resonances below each inelastic threshold are also analyzed. The adiabatic hyperspherical potential curves are used to iden

Sidney van den Bergh

Early-type dwarf galaxies are found to have high specific globular cluster frequencies which are similar to the high S values that are observed in luminous galaxies of types E and S0. It appears unlikely that cluster formation during mergers between dwarf disk systems can account for the high specific globular cluster frequency that is observed in early-type

Sidney van den Bergh

There is a serious discrepancy between the distance to the LMC derived from the Cepheid Period-Luminosity relation and that obtained by using the Galactic calibration for the luminosity of RR Lyrae stars. It is suggested that this problem might be due to the fact that second parameter effects make it inappropriate to apply Galactic calibrations to RR Lyrae v

Sidney van den Bergh

By chance, the slope of the Mv(max) versus (B-V)max relation for recent theoretical models of supernovae of Type Ia (SNe Ia) by Hoflich & Khokhlov is indistinguishable from the slope of a reddening line in the V versus B-V plane. This coincidence allows one to determine a parameter Mv*(max) for SNe Ia that is independent of both supernova detonation model an

V. Berezinsky, G. Fiorentini, M. Lissia

We discuss what appears the last hope for an astrophysical solution to the solar neutrino problem: a correlated variation of the astrophysical factors for the helium burning cross sections ($S_{33}$ and $S_{34}$) and either $S_{17}$ or the central temperature $T_c$. In this context, we recognize the important role played by the CNO neutrinos. In fact, we can

Brian Chaboyer, Peter J. Kernan, Lawrence M. Krauss, Pierre Demarque

We report the results of a detailed numerical study designed to estimate both the absolute age and the uncertainty in age (with confidence limits) of the oldest globular clusters. Such an estimate is essential if a comparison with the Hubble age of the universe is to be made to determine the consistency, or lack thereof, of various cosmological models. Utili

F. H. A. Robijn, P. T. de Zeeuw

A simple numerical scheme is presented for the construction of three-integral phase-space distribution functions for oblate galaxy models with a gravitational potential of Stäckel form, and an arbitrary axisymmetric luminous density distribution. The intrinsic velocity moments can be obtained simultaneously with little extra effort. The distribution of the i

Hangmo Yi, C. L. Kane

We study theoretically a quantum dot in the quantum Hall regime that is strongly coupled to a single lead via a point contact. We find that even when the transmission through the point contact is perfect, important features of the Coulomb blockade persist. In particular, the tunneling into the dot via a second weakly coupled lead is suppressed, and shows fea

Minos Axenides, Andrei Johansen, Holger Bech Nielsen, Ola Törnkvist

The space of static finite-energy configurations of the electroweak theory admits a ${\bf Z}_{2}$ topological structure. Odd-parity configurations with odd pure-gauge behavior at spatial infinity (S sphaleron, W-Z strings, multisphalerons) mediate rapid $B+L$ violation in the Early Universe. Configurations with even pure-gauge behavior (S$^{*}$ sphalerons, W

Vladimir Visnjic

Two-dimensional large-$N$ quantum chromodynamics with scalar quarks is considered with particular emphasis on its strong coupling regime which has not been studied so far. Techniques necessary to deal with the infinitely oscillatory bound state wave functions in the strong coupling regime are developed. I derive an estimate for the ground state mass and show

Eric J. Bakker, Henny J. G. L. M. Lamers, L. B. F. M. Waters, Christoffel Waelkens

We present a study of low- and high-resolution ultraviolet, high-resolution optical CAT/CES spectra and ultraviolet, optical and infrared photometry of the peculiar supergiant HD101584. From the photometry we learn that the ultraviolet and optical energy distribution cannot be fitted in a consistent way and we need a model in which the UV and optical energy

Valter Moretti, Stefan Steidl

Thermal Wightman functions of a massless scalar field are studied within the framework of a ``near horizon'' static background model of an extremal R-N black hole. This model is built up by using global Carter-like coordinates over an infinite set of Bertotti-Robinson submanifolds glued together. The analytical extendibility beyond the horizon is imp

Eric J. Bakker, Frank L. A. Van der Wolf, Henny J. G. L. M. Lamers, Austin F. Gulliver

High-resolution optical spectra (UES/WHT) of the extreme metal-poor post-AGB star HR4049 were obtained at four different orbital phases. The spectra cover the wavelength region from 3650ang to 10850ang at a resolution of R=5.2x10^4. These observations are supplemented with four high-resolution spectra of the NaI D1 & D2 and CaII K lines at R=10^5 (CAT/CES).

T. Schmidt, R. J. Haug, V. I. Fal'ko, K. v. Klitzing

The local density of states of a degenerate semiconductor is investigated at low magnetic fields. In order to realize this experiment, we designed a strongly asymmetric double-barrier heterostructure with heavily doped contacts and study the resonant tunneling transport through the lowest localized (zero-dimensional) level in the quantum well. Fine structure

A. Esser, S. Grossmann

We analyze the mechanism that determines the boundary of stability in Taylor-Couette flow. By simple physical argument we derive an analytic expression to approximate the stability line for all radius ratios and all speed ratios, for co- and counterrotating cylinders. The expression includes viscosity and so generalizes Rayleigh's criterion. We achieve a

Géza Fülöp

We consider BRST-invariant inner product states for quantum electrodynamics constructed from trivial BRST-invariant states and a gauge regulator. The trivial states are products of matter and ghost states and are annihilated by hermitian operators. The co-BRST operator and some further gauge-fixing regulators are found. The relation between gauge fixing and

G. Cvetic

We study effects of the heavy top quark ($m_t \approx 180 GeV$) on the scalar sector of the minimal Standard Model. We construct the effective potential for the scalar doublet, by first taking into account the leading contributions of the top quark loops. Minimizing this potential gives us a condition analogous to the leading-Nc gap equation of the standard

P. A. M. Guichon, K. Saito, E. Rodionov, A. W. Thomas

The quark-meson coupling model, based on a mean field description of non-overlapping nucleon bags bound by the self-consistent exchange of $\sigma$, $\omega$ and $\rho$ mesons, is extended to investigate the properties of finite nuclei. Using the Born-Oppenheimer approximation to describe the interacting quark-meson system, we derive the effective equation o

N. Bralic, C. D. Fosco, F. A. Schaposnik

We show that when the Abelian \CS\ theory coupled to matter fields is quantized in a vacuum with non vanishing magnetic flux (or electric charge), the requirement of gauge invariance at finite temperature leads to the quantization of the \CS\ coefficient and its quantum corrections, in a manner similar to the non-Abelian case.

J. A. Mulvey

We discuss a class of evolution equations equivalent to the simplest Universal Field Equation, the so--called Bateman equation, and show that all of them possess (at least) biHamiltonian structure. The first few conserved charges are calculated.

A. Dimakis, F. Mueller-Hoissen, T. Striker

`Umbral calculus' deals with representations of the canonical commutation relations. We present a short exposition of it and discuss how this calculus can be used to discretize continuum models and to construct representations of Lie algebras on a lattice. Related ideas appeared in recent publications and we show that the examples treated there are speci

Oe. Elgaroey, L. Engvik, E. Osnes, F. V. De Blasio

In this work we study properties of neutron star crusts, where matter is expected to consist of nuclei surrounded by superfluid neutrons and a homogeneous background of relativistic electrons. The nuclei are disposed in a Coulomb lattice, and it is believed that the structure of the lattice influences considerably the specific heat of the neutronic matter in

J. Padilla, W. Zhong, David Vanderbilt

We present a first-principles study of 180-degree ferroelectric domain walls in tetragonal barium titanate. The theory is based on an effective Hamiltonian that has previously been determined from first-principles ultrasoft-pseudopotential calculations. Statistical properties are investigated using Monte Carlo simulations. We compute the domain-wall energy,

W. Zhong, David Vanderbilt

Using path-integral Monte Carol simulations and an ab initio effective Hamiltonian, we study the effects of quantum fluctuations on structural phase transitions in the cubic perovskite compounds SrTiO3 and BaTiO3. We find quantum fluctuations affect ferroelectric (FE) transitions more strongly than antiferrodistortive (AFD) ones, even though the effective ma

A. S. Alexandrov, A. M. Bratkovsky

A qualitatively different character of dHvA oscillations has been found in a multiband (quasi)two dimensional Fermi liquid with a fixed fermion density $n_{e}$ (canonical ensemble) compared with an open system where the chemical potential $μ$ is kept fixed (grand canonical ensemble). A new fundamental period $P_{f}$ appears when $n_{e}$ is fixed, a damping o

D. V. Ahluwalia

First, we show that in the $(1,0)\oplus(0,1)$ representation space there exist not one but two theories for charged particles. In the Weinberg construct, the boson and its antiboson carry {\it same} relative intrinsic parity, whereas in our construct the relative intrinsic parities of the boson and its antiboson are {\it opposite}. These results originate fr

Karim Benakli

A way to break supersymmetry in perturbative superstring theory is the string version of the Scherk-Schwarz mechanism. There, the fermions and bosons have mass splitting due to different compactification boundary conditions. We consider the implementation of this mechanism in abelian orbifold compactifications with Wilson line backgrounds. For $Z_N$ and $Z_N

H. Fort, R. Gambini

We show that a (3+1)-dimensional system composed of an open magnetic vortex and an electrical point charge exhibits the phenomenon of Fermi-Bose transmutation. In order to provide the physical realization of this system we focus on the lattice compact scalar electrodynamics $SQED_c$ whose topological excitations are open Nielsen-Olesen strings with magnetic

J. A. Mulvey

The variational properties of the scalar so--called ``Universal'' equations are reviewed and generalised. In particular, we note that contrary to earlier claims, each member of the Euler hierarchy may have an explicit field dependence. The Euler hierarchy itself is given a new interpretation in terms of the formal complex of variational calculus, and

H. J. W. Muller-Kirsten, Jian-Ge Zhou, Yan-Gang Miao, J. -Q. Liang

The ADM and Bondi mass for the RST model have been first discussed from Hawking and Horowitz's argument. Expressing the localized RST action in terms of the ADM formulation, the RST Hamiltonian can be derived, meanwhile keeping track of all boundary terms. Then the total boundary terms can be taken as the total energy for the RST model. It has been found

F. S. Nogueira, N. F. Svaiter

The mechanism of dimensional transmutation is discussed in the context of Maxwell-Chern-Simons scalar QED. The method used is non-perturbative. The effective potential describes a broken symmetry state. It is found that the symmetry breaking vacuum is more stable when the Chern-Simons mass is different from zero. Pacs number: 11.10.Ef, 11.10.Gh.

G. P. Salam

Mueller's dipole formulation of onium-onium scattering is used to study unitarity corrections to the BFKL power growth at high energies. After a short discussion of the spatial distribution of colour dipoles in a heavy quarkonium and the associated fluctuations, results are presented showing that the one and two-pomeron contributions to the total cross s

H. G. Dosch, J. Kripfganz, A. Laser, M. G. Schmidt

The high temperature phase of the electroweak standard theory is described by a strongly coupled SU(2)-Higgs-model in three dimensions. As in the Abbott-Farhi-model Higgs and W-boson are low lying bound states. Using a method by Simonov based on the Feynman-Schwinger representation of correlators we calculate the masses of these states. Our results are compa

G. K. Leontaris, S. Lola, C. Scheich, J. D. Vergados

We give a classification of heavy Majorana neutrino mass matrices with up to three texture zeroes, assuming the Dirac masses of the neutrinos to be of the same form as the ones of the up-quarks in the five texture zero solutions for the quark matrices. This is the case for many unified and partially unified models. We find that it is possible to have solutio

Marcelo Gleiser, Andrew F. Heckler

A nonperturbative correction to the thermal nucleation rate of critical bubbles in a first order phase transition is estimated. The correction originates from large-amplitude fluctuations which may be present before the transition occurs. Using a simple model of a scalar field in a double-well potential, we present a method to obtain a corrected potential wh

I. Arsenin, D. Chen, N. Christ, R. Edwards

The first stage in the construction of the 0.8 Teraflops Supercomputer at Columbia, a working, two node parallel computer, has been successfully completed. The next stage, a 512 node, 26 Gigaflops prototype, is in its final construction phase. A general description and current status of the hardware and software is presented.

K. N. Anagnostopoulos, M. J. Bowick, S. M. Catterall, M. Falcioni

We report the status of a high-statistics Monte Carlo simulation of non-self-avoiding crystalline surfaces with extrinsic curvature on lattices of size up to $128^2$ nodes. We impose free boundary conditions. The free energy is a gaussian spring tethering potential together with a normal-normal bending energy. Particular emphasis is given to the behavior of

Colin Morningstar

Sources of uncertainties in perturbative calculations, tadpole improvement and its role in lattice perturbation theory, and six recent calculations are discussed.

Simon Hands, John B. Kogut

We formulate a Euclidean lattice theory of interacting elementary spin-half electric and magnetic charges, which we refer to as electrons and magnetic monopoles respectively. The model uses the polymer representation of the fermion determinant, and exhibits a self-dual symmetry provided electric charge $e$ and magnetic charge $g$ obey the minimal Dirac quant

Thomas Kalkreuter

The Lanczos method of Cullum and Willoughby is studied for euclidean Wilson fermions in quenched and unquenched SU(2) gauge fields on lattices of volume ranging from $4^4$ to $16^4$. The method is reliable even on larger lattices, but its cost for the computation of a given fraction of the spectrum grows (approximately) with the square of the lattice volume.

Nivaldo A. Lemos

The quantum theory of a spatially flat Friedmann-Robertson-Walker universe with a massless scalar field as source is further investigated. The classical model is singular, and in the framework of the Arnowitt-Deser-Misner canonical quantization formalism a discussion is made of the cosmic evolution, particularly of the quantum gravitational collapse problem.

James B. Hartle

The ``evolving constants'' method of defining the quantum dynamics of time-reparametrization-invariant theories is investigated for a particular implementation of parametrized non-relativistic quantum mechanics (PNRQM). The wide range of time functions that are available to define evolving constants raises issues of interpretation, consistency, and t

J. Legare, J. W. Moffat

We study the problem of test-particle motion in the Nonsymmetric Gravitational Theory (NGT) assuming the four-velocity of the particle is parallel-transported along the trajectory. The predicted motion is studied on a static, spherically symmetric background field, with particular attention paid to radial and circular motions. Interestingly, it is found that

K. S. Virbhadra

Recently Nathan Rosen and the present author obtained the energy and momentum densities of cylindrical gravitational waves in Einstein's prescription and found them to be finite and reasonable. In the present paper we calculate the same in prescriptions of Tolman as well as Landau and Lifshitz and discuss the results.

K. S. Virbhadra

An axially symmetric exact solution of the Einstein-Maxwell equations is obtained and is interpreted to give the gravitational and electromagnetic fields of a charged tachyon. Switching off the charge parameter yields the solution for the uncharged tachyon which was earlier obtained by Vaidya. The null surfaces for the charged tachyon are discussed.

M. Langer, J. Schmalian, S. Grabowski, K. H. Bennemann

We analyze the breakdown of Fermi-liquid behavior within the 2D Hubbard model as function of doping using our recently developed numerical method for the self consistent summation of bubble and ladder diagrams. For larger doping concentrations the system behaves like a conventional Fermi-liquid and for intermediate doping similar to a marginal Fermi-liquid.

Rosario Fazio, F. W. J. Hekking, A. A. Odintsov, 11 pages RevTex

We calculate both the DC and the AC Josephson current through a one-dimensional system of interacting electrons, connected to two superconductors by tunnel junctions. We treat the (repulsive) Coulomb interaction in the framework of the one-channel, spin-$1/2$ Luttinger model. The Josephson current is obtained for two geometries of experimental relevance: a q

J. Gonzalez, M. A. Martin-Delgado, G. Sierra, M. A. H. Vozmediano

This entry has been removed since we are an archive and not an advertisement space.

Yuli V. Nazarov

We show that quasiholes persist near the edge of incompressible Quantum Hall state forming a Wigner structure. The average density of quasiholes is fixed by electrostatics and decreases slowly with increasing distance from the edge. As we see from elementary reasoning, their specific arrangement can not be a regular Wigner lattice and shows a complex hierarc

Bruno Eckhardt, Shmuel Fishman, Jonathan Keating, Oded Agam

According to theorems of Shnirelman and followers, in the semiclassical limit the quantum wavefunctions of classically ergodic systems tend to the microcanonical density on the energy shell. We here develop a semiclassical theory that relates the rate of approach to the decay of certain classical fluctuations. For uniformly hyperbolic systems we find that th

Dan Maoz, Eran Ofek, Amotz Shemi, Aaron Barth

We report the optical identification of an $R=18.3$ mag, $z=2.432$ quasar at the position of a 6 cm radio source and a faint \rosat PSPC X-ray source. The quasar lies within the error circles of unidentified extreme-UV (EUV) detections by the \euve and \rosat WFC all-sky surveys at $\sim 400$ Å and $\sim 150$ Å, respectively. A 21 cm H I emission measurement

Pawan Kumar, Jeremy Goodman

We calculate the damping of quadrupole f and low order g modes (primary modes) by nonlinear coupling to other modes of the star. This damping is orders of magnitude more rapid than direct radiative damping when the primary amplitude is large, as in tidal capture. Primary modes destabilize high degree g-modes of half their frequency (daughter modes) by 3-mode

Dante Minniti

The results of a kinematic study of the Galactic bulge based on spectra of red giants in fields at projected distances of 1.4-1.8 kpc from the Galactic center are presented. There is a marked trend of kinematics with metallicity, in the sense that the more metal-poor population has higher velocity dispersion and lower rotation velocity than the metal-rich po

Paola Mazzei, Gianfranco De Zotti

Several lines of evidence suggest that early-type galaxies might have been very dusty during their initial evolutionary stages, characterized by intense star formation activity. The radio selection has provided, by far, the richest samples of high-$z$ galaxies, most likely of early type, which may therefore yield crucial direct information on the period when

Neal Katz, David H. Weinberg, Lars Hernquist

We describe numerical methods for incorporating gas dynamics into cosmological simulations and present illustrative applications to the cold dark matter (CDM) scenario. Our evolution code, a version of TreeSPH (Hernquist \& Katz 1989) generalized to handle comoving coordinates and periodic boundary conditions, combines smoothed--particle hydrodynamics (SPH)

Neal Katz, David H. Weinberg, Lars Hernquist, Jordi Miralda-Escude

We study the formation of damped \lya and Lyman limit absorbers in a hierarchical clustering scenario using a gas dynamical simulation of an $\Omega = 1$, cold dark matter universe. In the simulation, these high column density systems are associated with forming galaxies. Damped \lya absorption, $N_{HI} \simgt 10^{20.2}\cm^{-2}$, arises along lines of sight

Lars Hernquist, Neal Katz, David H. Weinberg, Jordi Miralda-Escude

Cosmological simulations with gas provide a detailed description of the intergalactic medium, making possible predictions of neutral hydrogen absorption in the spectra of background QSOs. We present results from a high-resolution calculation of an $Ω=1$ cold dark matter model. Our simulation reproduces many of the observed properties of the \lya forest surpr

M. J. Duff

We review electric/magnetic duality in $N=4$ (and certain $N=2$) globally supersymmetric gauge theories and show how this duality, which relates strong to weak coupling, follows as a consequence of a string/string duality. Black holes, eleven dimensions and supermembranes also have a part to play in the big picture.

F. Cardarelli, E. Pace, G. Salme', S. Simula

A parameter-free evaluation of the $N - Δ$ electromagnetic transition form factors is carried out in a light-front constituent quark model, based on $N$ and $Δ$ eigenstates of a mass operator which reproduces a large set of hadron energy levels. A one-body electromagnetic current, including the constituent quark form factors previously determined within the

Kevin C. K. Chan

A recent paper [M. Kamata and T. Koikawa, Phys. Lett. {\bf B353} (1995) 196.] claimed to obtain the charged version of the $(2+1)$-dimensional spinning $BTZ$ black hole solution by assuming a (anti-) self dual condition imposed on the electric and magnetic fields. We point out that the angular momentum and mass diverge at spatial infinity and as a consequenc

Gabor Vattay, Per E. Rosenqvist

A quantum generalization of the semiclassical theory of Gutzwiller is given. The new formulation leads to systematic orbit-by-orbit inclusion of higher $\hbar$ contributions to the spectral determinant. We apply the theory to billiard systems, and compare the periodic orbit quantization including the first $\hbar$ contribution to the exact quantum mechanical

C. G. Carvalhaes, L. V. Belvedere, C. P. Natividade, H. Boschi Filho

The operator solution of the anomalous chiral Schwinger model is discussed on the basis of the general principles of Wightman field theory. Some basic structural properties of the model are analyzed taking a careful control on the Hilbert space associated with the Wightman functions. The isomorphism between gauge noninvariant and gauge invariant descriptions

Martin Lavelle, David McMullan

It is shown that colour can only be defined on gauge invariant states. Since the ability to associate colour with constituent quarks is an integral part of the constituent quark model, this means that, if we want to extract constituent quarks from QCD, we need to dress Lagrangian quarks with gluons so that the result is gauge invariant. We further prove that

Martin Lavelle, David McMullan

Starting from the observation that colour charge is only well defined on gauge invariant states, we construct perturbatively gauge invariant, dynamical dressings for individual quarks. Explicit calculations show that an infra-red finite mass-shell renormalisation of the gauge invariant, dressed propagator is possible and, further, that operator product effec

Yoshi Fujiwara, Jiro Soda

Wavelet analysis is proposed as a new tool for studying the large-scale structure formation of the universe. To reveal its usefulness, the wavelet decomposition of one-dimensional cosmological density fluctuations is performed. In contrast with the Fourier analysis, the wavelet analysis has advantage of its ability to keep the information for location of loc

Vasilios Zarikas

We present the analysis of the phase transition for the two Higgs electroweak model. We have found that for a wide range of parameters the universe first tunnels to a new intermediate phase. This feature not only is very important by itself, but also provides the essential requirements for producing baryon asymmetry with only small explicit CP-violating term

L. S. F. Olavo, A. D. Figueiredo

In this continuation paper the Schrödinger equation for the half-integral spin eigenfunctions is obtained and solved. We show that all the properties already derived using the Heisemberg matrix calculation and Pauli's matrices are also obtained in the realm of these analytical functions. We also show that Einstein-Bose condensation for fermions is expect

L. S. F. Olavo

In these continuation papers (VI and VII) we are interested in approach the problem of spin from a classical point of view. In this first paper we will show that the spin is neither basically relativistic nor quantum but reflects just a simmetry property related to the Lie algebra to which it is associated. The classical approach will be paraleled with the u

V. V. Borzov, E. V. Damaskinsky, S. B. Yegorov

The classification of the representations of the generalized deformed oscillator algebra is given together with several comments about possibility of introducing a coproduct structure in some type of deformed oscillator algebra.

B. L. Feigin, A. V. Odesskii

In [4] we introduce the associative algebras $Q_{n,k}(\CE,τ)$. Recall the definition. These algebras are labeled by discrete parameters $n,k$; $n,k$ are integers $n>k>0$ and $n$ and $k$ have not common divisors. Then, $\CE$ is an elliptic curve and $τ$ is a point in $\CE$. We identify $\CE$ with $\BC/Γ$, where $Γ$ is a lattice.

J. J. de Swart, C. P. F. Terheggen, V. G. J. Stoks

The low-energy parameters describing the np scattering in the 3S1 + 3D1 partial waves, the deuteron parameters, and their relations are discussed. These parameters can be determined quite accurately in the energy-dependent Nijmegen partial-wave analyses of the np data and are also given by the high-quality Nijmegen potentials. The newest values for these par

Gary Horowitz, Ashoke Sen

We construct and study the electrically charged, rotating black hole solution in heterotic string theory compactified on a $(10-D)$ dimensional torus. This black hole is characterized by its mass, angular momentum, and a $(36-2D)$ dimensional electric charge vector. One of the novel features of this solution is that for $D >5$, its extremal limit saturates t

J"urgen Fuchs, Bert Schellekens, Christoph Schweigert

The fixed point resolution problem is solved for diagonal coset theories. The primary fields into which the fixed points are resolved are described by submodules of the branching spaces, obtained as eigenspaces of the automorphisms that implement field identification. To compute the characters and the modular S-matrix we use `orbit Lie algebras' and `twi

Parentani Renaud

In order to address the problem of the validity of the "background field approximation", we introduce a dynamical model for a mirror described by a massive quantum field. We then analyze the properties of the scattering of a massless field from this dynamical mirror and compare the results with the corresponding quantities evaluated using the origina

M. T. Grisaru, M. E. Wehlau

We describe various aspects of two-dimensional $N=2$ supergravity in superspace. We present the solution to the constraints in terms of unconstrained prepotentials, and the different superspace measures (full and chiral) used in the construction of invariant actions. We discuss aspects of the theory in light-cone gauge, including the Ward identities for corr

P. K. Kabir, A. Pilaftsis

The basic requirement that, in quantum theory, the time-evolution of any state is determined by the action of a unitary operator, is shown to be the underlying cause for certain ``exact'' results which have recently been reported about the time-dependence of transition rates in quantum theory. Departures from exponential decay, including the ``Quantu

Ian Balitsky

I demonstrate that the leading logarithms for high-energy scattering can be obtained as a result of evolution of the nonlocal operators - straight-line ordered gauge factors - with respect to the slope of the straight line.

N. G. Deshpande, Xiao-Gang He, J. Trampeti\' c

The importance of dipole penguin operator, $O_{11} = (g_s/8π^2)m_b \bar s σ_{μν}RT^a b G^{μν}_a$, on B decays is demonstrated. It is shown that branching ratios for the inclusive decay $b\to s s\bar s$, the semi-inclusive decay $b\to sϕ$, and the exclusive decay $B\to πK$ are enhanced by 20% to 30%. A useful consequence of this calculation is the inclusive $

Kei-Ichi Kondo

In the Maxwell--Chern-Simons theory coupled to $N_f$ flavors of 4-component fermions (or even number of 2-component fermions) we construct the gauge-covariant effective potential written in terms of two order parameters which are able to probe the breakdown of chiral symmetry and parity. In the absence of the bare Chern-Simons term, we show that the chiral s

Wolfgang Mödritsch

The approach used for the determination of S-wave amplitudes containing the application of the nonrelativistic approximation in the case of P-waves leads to unphysical divergencies. We show how to avoid the latter in calculations of contributions to the cross section near threshold in agreement with field theory. This enables us to give quantitatively reliab

Dima Bardin, Tord Riemann

The various four-fermion production channels in $e^+ e^-$ annihilation are discussed and the {\tt CC11} process $e^+ e^- \rightarrow {\bar f}_1^u f_1^d f^u_2 {\bar f}_2^d$, {\mbox{$f$$\neq$$e$}}, is studied in detail. The cross section $d^2σ/ds_1ds_2$, with $s_1,s_2$ being the invariant masses squared of the two fermion pairs, may be expressed by six generic

Yu. S. Kalashnikova

The notion of constituent gluon is introduced as a gluon propagating in the vacuum background field. The Hamiltonian approach for a system containing such gluon and a $q\bar{q}g$ pair is formulated, and the masses of lowest $q\bar{q}g$ hybrids are estimated.

K. Huitu, J. Maalampi, M. Raidal

We consider the production of a single right-handed gauge boson $W_R$ in the high-energy $e^-γ$ collisions with polarized beams. If the associated neutrino is light, the reaction will give the best discovery reach for $W_R$ in the Next Linear Collider.

Peter Stephenson

We extend and attempt to clarify recent results which showed possible problems for universality for the gauge group SU(2). We suggest that the presence of artifacts actually distorts the mixed-coupling plane. This implies that a separation of artifacts from physical quantities is intrinsically difficult. We suggest what the nature of the resolution might be.

Colin Morningstar, Mike Peardon

The scalar glueball mass and the string tension are computed in lattice SU(3) gauge theory with the aim of establishing the effectiveness of the improved action approach in removing finite-spacing artifacts.

Jon Ivar Skullerud

We present the first results from a study of the quark--gluon vertex function in the Landau gauge. The results are obtained for quenched QCD with an O(a)-improved Wilson fermion action, at beta=6.0. We discuss plans for further study, including extraction of a renormalised QCD coupling from the momentum dependence of the vertex.

Wolfgang Bock, Julius Kuti

The renormalized trajectory (RT) is determined from two different Monte Carlo renormalization group techniques with $δ$-function block spin transformation in the multi-dimensional coupling parameter space of the two-dimensional non-linear sigma model with O(3) symmetry. At a correlation length $ξ\approx 3$-$5$, the RT is shown to break away from the straight

M. Marcolli

These notes provide an introductory exposition of the Seiberg-Witten gauge theory. They collect the material presented in a series of seminars given by the author at the University of Milano.

Kazuyoshi Kiyohara

We study $n$-dimensional Kähler manifolds whose geodesic flows possess $n$ first integrals in involution that are fibrewise hermitian forms and simultaneously normalizable. Under some mild assumption, one can associate with such a manifold an $n$-dimensional commutative Lie algebra of infinitesimal automorphisms. This, combined with the given $n$ first integ

Joe Watson, Daniel S. Fisher

A simple model for the nonlinear collective transport of interacting particles in a random medium with strong disorder is introduced and analyzed. A finite threshold for the driving force divides the behavior into two regimes characterized by the presence or absence of a steady-state particle current. Below this threshold, transient motion is found in respon

M. Goulian, S. T. Milner

We consider the problem of an ideal polymer confined in a droplet. When the droplet radius is smaller than the (unconfined) polymer radius of gyration, the polymer entropy will depend on the droplet shape. We compute the resulting surface free energy. Using parameters appropriate for polymers confined in microemulsions, we find that the polymer and bending s

Jonathan Miller, A. G. Rojo

Scattering between edge states that bound one-dimensional domains of opposite potential or flux is studied, in the presence of strong potential or flux disorder. A mobility edge is found as a function of disorder and energy, and we have characterized the extended phase. "paper_FINAL.tex" 439 lines, 20366 characters In the presence of flux and/or pote

Paul. L. Krapivsky, Sidney Redner

We investigate the kinetics of constant-kernel aggregation which is augmented by either: (a) evaporation of monomers from finite-mass clusters, or (b) continuous cluster growth -- \ie, condensation. The rate equations for these two processes are analyzed using both exact and asymptotic methods. In aggregation-evaporation, if the evaporation is mass conservin

C. C. Homes, T. Timusk, D. A. Bonn, R. Liang

The reflectance of high-quality, unpolished single crystals of YBa_2Cu_3O_{6+x}, for the doping range x=0.50 -> 0.95, has been measured with radiation polarized along the c axis from approx 50 cm^{-1} to 5000 cm^{-1} between 10 K and 300 K. In highly doped (x=0.95) material, the normal-state conductivity shows a metallic response. For intermediate dopings (x

Emilio Artacho, Felix Yndurain

The interstitial oxygen centers in silicon and germanium are reconsidered and compared in an analysis based on the first-principles total-energy determination of the potential-energy surface of the centers, and a calculation of their respective low energy excitations and infrared absorption spectra. The total-energy calculations reveal unambiguously that int

A J McKane, M B Tarlie

The formalism which has been developed to give general expressions for the determinants of differential operators is extended to the physically interesting situation where these operators have a zero mode which has been extracted. In the approach adopted here, this mode is removed by a novel regularisation procedure, which allows remarkably simple expression

E. P. Raposo, M. D. Coutinho-Filho

Using a microscopic numerical approach suitable to describe disordered antiferromagnets, with application to $Fe_{x}Zn_{1-x}F_{2}$, it is shown that the characteristics of the spin glass phase found for $x=0.25$ is much in agreement with the scenario predicted by the scaling theory of the droplet model.

A J McKane, R K P Zia

We study periodic Brownian paths, wrapped around the surface of a cylinder. One characteristic of such a path is its width square, $w^2$, defined as its variance. Though the average of $w^2$ over all possible paths is well known, its full distribution function was investigated only recently. Generalising $w^2$ to $w^{(N)}$, defined as the $N$-th power of the

C. A. Hayward, D. Poilblanc

The low energy behaviour of the isotropic t--J ladder system is investigated using exact diagonalization techniques, specifically finding the Drude weight, the charge velocity and the compressibility. By applying the ideas of Luttinger liquid theory, we determine the correlation exponent $K_ρ$ which defines the behaviour of the long range correlations in the

Gyorgy Szabo, Attila Szolnoki, Tibor Antal, Istvan Borsos

Instead of the homogeneous ordered particle distributions characteristic to equilibrium systems a self-organizing polydomain structure is found to be stable at low temperatures in a square lattice-gas model with repulsive nearest neighbor interaction when the particle jumps are biased by a uniform electric field. We have performed Monte Carlo simulations to