June 1994 arXiv papers — page 8

G. Giavarini, C. P. Martin, F. Ruiz Ruiz

We consider a family of local BRS-invariant higher covariant derivative regularizations of $SU(N)$ Chern-Simons theory that do not shift the value of the Chern-Simons parameter $k$ to $k+\,{\rm sign}(k)\,\cv$ at one loop.

T. Kamon, J. Lopez, P. McIntyre, J. White

We study the signals for supersymmetry at the Tevatron and DiTevatron ($\sqrt{s}=4\TeV$) in various well-motivated supersymmetric models. We consider the trilepton signature in the decay of pair-produced charginos and neutralinos, the missing energy signature in gluino and squark production, and the $b\bar b$ signal in the decay of the lightest supersymmetri

Leandros Perivolaropoulos

I show the existence of a new type of vortex solution which is non-static but stationary and carries angular momentum. This {\it spinning vortex} can be embedded in models with trivial vacuum topology like a model with $SU(2)_{global}\times U(1)_{local} \rightarrow U(1)_{global}$ symmetry breaking. The stability properties of the embedded spinning vortex are

Carl H. Albright, Satyanarayan Nandi

It has been recently suggested by others that one can simultaneously explain the depletions of solar electron-neutrinos and atmospheric muon-neutrinos along with a 7 eV neutrino component of mixed dark matter by postulating the existence of nearly-degenerate 2 eV neutrinos with the correct mixing parameters. We study this claim in the framework of a simple S

D. Kalafatis, M. C. Birse

We investigate from first principles the introduction of isospin-1 vector and axial-vector fields into the nonlinear sigma model. Chiral symmetry is nonlinearly realised and spin-1 fields are assumed to transform homogeneously under chiral rotations. By requiring the Hamiltonian of the theory to be bounded from below we find inequalities relating three- and

V. V. Kiselev

In the framework of QCD sum rules one uses a scheme, allowing one to apply the conditions of both nonrelativistic heavy quark motion inside mesons and independence of nonsplitting nS-state density on the heavy quark flavours. In the leading order an analitic expression is derived for leptonic constants of both heavy quarkonia and heavy mesons with a single h

Markus H. Thoma

The damping of a massless fermion coupled to a massless scalar particle at finite temperature is considered using the Braaten-Pisarski resummation technique. First the hard thermal loop diagrams of this theory are extracted and effective Green's functions are constructed. Using these effective Green's functions the damping rate of a soft Yukawa fermi

Harald Fritzsch, Dirk HoltmannspÖtter

It is shown that the simplest breaking of the subnuclear democracy leads to a successful description of the mixing between the second and third family. In the lepton channel the $ν_{μ} - ν_{τ}$ oscillations are expected to be described by a mixing angle of $2.65^ {\circ }$ which might be observed soon in neutrino experiments.

F. R. Klinkhamer

We discuss the position in configuration space of the electroweak vortex solution. (Talk given at the NATO Advanced Research Workshop "Electroweak Physics and the Early Universe", Sintra, Portugal, March 1994)

T. Kobayashi

We study the minimal supersymmetric standard model derived from $Z_N \times Z_M$ orbifold models. Moduli dependent threshold corrections of the gauge couplings are investigated to explain the measured values of the coupling constants. Also we study Yukawa couplings of the models. We find that the $Z_2 \times Z_6'$, $Z_2\times Z_6$, $Z_3 \times Z_6$ and $

A. Pordt, C. Wieczerkowski

Hierarchical renormalization group (RG) transformations are related to nonassociative algebras. These algebras serve as a new basic tool for a rigorous treatment of global RG flows and the search of nontrivial infrared fixed points. Convergent expansion methods are presented and analyzed in terms of algebra norms. It is shown that the infrared fixed points a

S. C. Power

It is shown that all the approximately finite dimensional C*-algebras which are not of Type I are isomorphic as Banach spaces. This generalises the matroid case given previously by Arazy. Analogous results are obtained for various families of triangular subalgebras of AF C*-algebras. In addition the classification of various continua of Type I AF C*-algebras

S. C. Power

The natural lexicographic semigroupoids associated with Cantor product spaces indexed by countable linear orders are classified. Applications are given to the classification of triangular operator algebras which are direct limits of upper triangular matrix algebras.

S. C. Power

Some new connections are given between linear orderings and triangular operator algebras. A lexicograhic product is defined for triangular operator algebras and the Jacobson radical of an infinite lexicographic product of upper triangular matrix algebras is determined.

V. N. Muthukumar, M. Sardar

A recent experiment by Ma and collaborators shows that the gap anisotropy in ${\rm Bi}_2 {\rm Sr}_2 {\rm Ca}_1 {\rm Cu}_2 {\rm O}_{8+x}$ is strongly temperature dependent. In particular, the superconducting gap along the $Γ- M$ direction shows a weaker temperature dependence than the gap along the $Γ- X$ direction which decreases rapidly with temperature. We

T. P. Devereaux, R. T. Scalettar, G. T. Zimanyi

The behavior of flux lines in the presence of both columnar and point disorder in 1+1 dimension is investigated using Renormalization Group and world-line Quantum Monte Carlo techniques. In particular, we calculate the transverse wandering correlation function for a single boson and recover known results for point and columnar disorder separately. We then ex

R. G. Mints, I. B. Snapiro

We predict the Josephson vortex Cherenkov radiation of an electromagnetic wave. We treat a long one--dimensional Josephson junction. We consider the wave length of the radiated electromagnetic wave to be much less than the Josephson penetration depth. We use for calculations the nonlocal Josephson electrodynamics. We find the expression for the radiated powe

P. W. Brouwer, C. W. J. Beenakker

We have computed the probability distribution of the conductance of a ballistic and chaotic cavity which is connected to two electron reservoirs by leads with a single propagating mode, for arbitrary values of the transmission probability Gamma of the mode, and for all three values of the symmetry index beta. The theory bridges the gap between previous work

J. A. Melsen, C. W. J. Beenakker

The resistance is computed of an ${\rm NI}_{1}{\rm NI}_{2}{\rm S}$ junction, where N = normal metal, S = superconductor, and ${\rm I}_{i}$ = insulator or tunnel barrier (transmission probability per mode $Γ_{i}$). The ballistic case is considered, as well as the case that the region between the two barriers contains disorder (mean free path $l$, barrier sepa

A. S. Cattaneo, A. Gamba, I. V. Kolokolov, M. Martellini

We investigate the conductance of a 1-D disordered conducting loop with two contacts, immersed in a magnetic flux. We show the appearance in this model of the Al'tshuler-Aronov-Spivak behaviour. We also investigate the case of a chain of loops distributed with finite density: in this case we show that the interference effects due to the presence of the l

Nobuki Maeda

Applying a bi-local mean field approximation to the fractional quantum Hall state of $ν=1/3$, we obtain charged and neutral vortex mean field solutions numerically. We calculate the mean field energy and the fluctuation corrections. The charged vortex has a fractional charge and a fractional angular momentum. The neutral vortex is a bound state of two charge

Jeffrey C. Reynar

This article outlines a new method of locating discourse boundaries based on lexical cohesion and a graphical technique called dotplotting. The application of dotplotting to discourse segmentation can be performed either manually, by examining a graph, or automatically, using an optimization algorithm. The results of two experiments involving automatically l

Stephen Soderland, Wendy Lehnert

The availability of large on-line text corpora provides a natural and promising bridge between the worlds of natural language processing (NLP) and machine learning (ML). In recent years, the NLP community has been aggressively investigating statistical techniques to drive part-of-speech taggers, but application-specific text corpora can be used to drive know

Pascale Fung, Dekai Wu

We describe a method of using statistically-collected Chinese character groups from a corpus to augment a Chinese dictionary. The method is particularly useful for extracting domain-specific and regional words not readily available in machine-readable dictionaries. Output was evaluated both using human evaluators and against a previously available dictionary

Nancy Green, Sandra Carberry

This paper presents our implemented computational model for interpreting and generating indirect answers to Yes-No questions. Its main features are 1) a discourse-plan-based approach to implicature, 2) a reversible architecture for generation and interpretation, 3) a hybrid reasoning model that employs both plan inference and logical inference, and 4) use of

Don D. Frantz

Heat capacity curves as functions of temperature for classical atomic clusters bound by pairwise Lennard-Jones potentials were calculated for aggregate sizes from 4 to 24 using Monte Carlo methods. J-walking (or jump-walking) was used to overcome convergence difficulties due to quasi-ergodicity in the solid-liquid transition region. The heat capacity curves

Leandros Perivolaropoulos

I review recent progress towards a detailed understanding of the power spectrum of cosmic string perturbations induced on the Microwave Background (CMB). The use of a simple analytic model allows to include important effects that have not been included in previous studies. These effects are potential fluctuations on the last scattering surface (the Sachs-Wol

John N. Bahcall, Chris Flynn, Andrew Gould, Sofia Kirhakos

We show that faint red stars do not contribute significantly to the mass budget of the Galaxy or to microlensing statistics. Our results are obtained by analyzing two long exposures of a high-latitude field taken with the Wide Field Camera on the newly repaired {\it Hubble Space Telescope}. Stars are easily distinguished from galaxies essentially to the limi

Francesca Primas, Paolo Molaro, Fiorella Castelli

High resolution CASPEC and EMMI spectra (R$\approx$10$^4$) of the faint metal- deficient candidates CS 22891--209, CS 22897--8, CS 22948--66 and CS 22968--14 taken from the survey of Beers, Preston and Shectman (1985, BPS) are analyzed for abundances. The fine analysis with LTE model atmospheres gives an iron metallicity for the four stars between $-$3.15 an

E. L. Martin, R. Rebolo, A. Magazzu

We present intermediate dispersion (0.7-2.2 Å~pix$^{-1}$) optical spectroscopic observations aimed at applying the ``Lithium Test'' to a sample of ten brown dwarf candidates located in the general field, two in young open clusters, and two in close binaries. We find evidence for strong Li depletion in all of them, and thus infer lower mass limits of

H. C. Rosu

The Hawking effect and the Unruh effect are two of the most important predictions in the theoretical physics of the last quarter of the 20th century. In parallel to the theoretical investigations there is great interest in the possibility of revealing effects of this type in some sort of experiments. I present a general discussion of the proposals to measure

M. A. Fradkin

An effect of the volume change upon proper ferroelastic (martensitic) phase transitions in cubic crystals is considered. Corresponding terms in the Ginzburg-Landau expansion of the Gibbs free energy are analyzed for the first- as well as second-order phase transitions from cubic to tetragonal lattice under the action of uniaxial and hydrostatic pressure. The

Alejandro Gangui

The presence of non--Gaussian features in the Cosmic Microwave Background (CMB) radiation maps represents one of the most long--awaited clues in the search for the actual structure of the primordial radiation, still needing confirmation. These features could shed some light on the non trivial task of distinguishing the real source of the primeval perturbatio

Ehud Cohen, Tsafrir Kolatt, Tsvi Piran

We compare the burst distribution of the new (2B) BATSE catalogue to a cosmological distribution. We find that the distribution is insensitive to cosmological parameters such as Omega and Lambda and to the width of the bursts luminosity function. The maximal red shift of the long bursts is ~2.1 (assuming no evolution) while Zm(long) of the short bursts is si

Alexander Vilenkin

The world view suggested by quantum cosmology is that inflating universes with all possible values of the fundamental constants are spontaneously created out of nothing. I explore the consequences of the assumption that we are a `typical' civilization living in this metauniverse. The conclusions include inflation with an extremely flat potential and low

F. R. Bouchet, S. Colombi, E. Hivon, R. Juszkiewicz

This paper deals with the time evolution in the matter era of perturbations in Friedman-Lemaitre models with arbitrary density parameter $Ω$, with either a zero cosmological constant, $Λ= 0$, or with a non-zero cosmological constant in a spatially flat Universe. Unlike the classical Eulerian approach where the density contrast is expanded in a perturbative s

J. Nemchik, N. N. Nikolaev, B. G. Zakharov

CEBAF is a high-luminocity factory of virtual photons with variable virtuality $Q^{2}$ and transverse size. This makes CEBAF, in particular after the energy upgrade to (8-12)GeV, an ideal facility for uncovering new phenomena, and opening new windows, at the interface of the perturbative and nonperturbative QCD. We discuss color transparency as the case for

Holger Dette

A new characterization of the generalized Hermite polynomials and of the orthogonal polynomials with respect to the maesure $|x|^\g (1-x^2)^{\a-1/2}dx$ is derived which is based on a "reversing property" of the coefficients in the corresponding recurrence formulas and does not use the representation in terms of generalized Laguerre and Jacobi polynom

P. K. Lin

Let $X$ be a complex Banach space and let $J:X \to X^*$ be a duality section on $X$ (i.e. $\langle x,J(x)\rangle=\|J(x)\|\|x\|=\|J(x)\|^2=\|x\|^2$). For any unit vector $x$ and any ($C_0$) contraction semigroup $T=\{e^{tA}:t \geq 0\}$, Goldstein proved that if $X$ is a Hilbert space and if $|\langle T(t) x,J(x)\rangle| \to 1 $ as $t \to \infty$, then $x$ is

Fouad Chaatit, M. Khamsi

We prove that a Banach lattice $X$ which does not contain the $l^n_{\infty}$-uniformly has an equivalent norm which is uniformly Kadec-Klee for a natural topology $τ$ on $X$. In case the Banach lattice is purely atomic, the topology $τ$ is the coordinatewise convergence topology.

G. L. Rossini, F. A. Schaposnik

We discuss parity violation in the 3-dimensional (N flavour) Thirring model. We find that the ground state fermion current in a background gauge field does not posses a well defined parity transformation. We also investigate the connection between parity violation and fermion mass generation, proving that radiative corrections force the fermions to be massiv

P. S. Aspinwall, D. R. Morrison

The Kahler moduli space of a particular non-simply-connected Calabi-Yau manifold is mapped out using mirror symmetry. It is found that, for the model considered, the chiral ring may be identical for different associated conformal field theories. This ambiguity is explained in terms of both A-model and B-model language. It also provides an apparent counterexa

Guy Bonneau

We analyse with the algebraic, regularisation independant, cohomological B.R.S. methods, the renormalisability of torsionless N=2 and N= 4 supersymmetric non-linear $\si$ models built on Kähler spaces. Surprisingly enough with respect to the common wisdom, in the case of N=2 supersymmetry, we obtain an anomaly candidate, at least in the compact Kähler Ricci-

Guy Bonneau

In order to study in a regularisation free manner the renormalisability of d=2 supersymmetric non-linear $\si$ models, one has to use the algebraic BRS methods ; moreover, in the absence of an off-shell formulation, one has often to deal with open algebras. We then recall in a pedagogical and non technical manner the standard methods used to handle these que

H. J. de Vega, N. Sánchez

We compute the string energy-momentum tensor and {\bf derive} the string equation of state from exact string dynamics in cosmological spacetimes. $1+1,~2+1$ and $D$-dimensional universes are treated for any expansion factor $R$. Strings obey the perfect fluid relation $ p = (γ-1) ρ$ with three different behaviours: (i) {\it Unstable} for $ R \to \infty $ wit

G. A. Diamandis, B. C. Georgalas, E. Papantonopoulos

We study solutions of the tree level string effective action in the presence of the tachyon mode.We find that the 2-dim. static black hole is stable against tachyonic perturbations.For a particular ansatz for the tachyon field we find an exact solution of the equations of motion which exhibits a naked singularity.In the case of static fields we find numerica

I. L. Shapiro, G. Cognola

At high energy scale the only quantum effect of any asymptotic free and asymptotically conformal invariant GUT is the trace anomaly of the energy-momentum tensor. Anomaly generates the new degree of freedom, that is propagating conformal factor. At lower energies conformal factor starts to interact with scalar field because of the violation of conformal inva

Tien D Kieu

It is argued on general ground and demonstrated in the particular example of the Chiral Schwinger Model that there is nothing wrong with apparently anomalous chiral gauge theory. If quantised correctly, there should be no gauge anomaly and chiral gauge theory should be renormalisable and unitary, even in higher dimensions and with non-abelian gauge groups. F

Anatoly Radyushkin

We investigate a model QCD sum rule for the pion wave function $φ_π(x)$ based on the non-diagonal correlator whose perturbative spectral density vanishes and $Φ(x,M^2)$, the theoretical side of the sum rule, consists of condensate contributions only. We study the dependence of $Φ(x,M^2)$ on the Borel parameter $M^2$ and observe that $Φ(x,M^2)$ has a humpy fo

J. L. Goity, W. Roberts

An analysis of semileptonic decays of $B$ mesons with the emission of a single soft pion is presented in the framework of the heavy-quark limit using an effective Lagrangian which implements chiral and heavy-quark symmetries. The analysis is performed at leading order of the chiral and inverse heavy mass expansions. In addition to the ground state heavy meso

Stephen D. H. Hsu

I discuss a formalism for computing quantum scattering amplitudes using a semiclassical expansion of a functional integral representation for the S-matrix. The classical background for the expansion is determined by solving the equations of motion subject to nontrivial boundary conditions determined by the initial and final quantum states. The formalism is d

R. Pittau

In this paper I investigate the production of four quarks at LEP 200 energies. Effects due to initial state QED corrections and background diagrams, including QCD contributions, are studied and examples of results obtained with an event generator presented.

F. A. Berends, R. Kleiss, R. Pittau

Four fermion processes at e+ e- colliders in a range of energy from 100 GeV to 1 TeV are discussed and examples of results obtained with an event generator presented. We also investigate the effects of the inclusion of initial state QED corrections and QCD contributions.

I. M. Dremin

Quantum chromodymamics (QCD) approach to the problem of multiplicity distributions in high energy particle collisions is described. The solutions of QCD equations for generating functions of the multiplicity distributions in gluon and quark jets are presented for both fixed and running coupling constants. The newly found characteristics very sensitive to dis

O. K. Kalashnikov

The spectral density method being applied to the quantum field theory at finite temperature is revived and its possibilities are briefly discussed.

I. M. Dremin, V. A. Nechitailo

The ratio of average multiplicities in gluon and quark jets is shown to become noticeably smaller in higher-order QCD compared to its lowest order value what improves agreement with experiment. QCD anomalous dimension has been calculated. It has been used to get energy dependence of mean multiplicities.

M. A. Fradkin

The effect of the external field on the weakly-discontinuous first-order phase transition is analyzed in the frame of the Landau theory. The transformation of the free energy expansion as a power series in the order parameter is suggested that maps the first-order phase transition onto the second-order one under the 'effective' external field, that d

Leon Balents, David R. Nelson

A flux liquid can condense into a smectic crystal in a pure layered superconductors with the magnetic field oriented nearly parallel to the layers. If the smectic order is commensurate with the layering, this crystal is {\sl stable} to point disorder. By tilting and adjusting the magnitude of the applied field, both incommensurate and tilted smectic and crys

A. Hoffmann, P. Lemmens, G. Guentherodt, V. Thomas

Single crystalline Tl2Ba2Ca2Cu3O10 was studied using electronic Raman scattering. The renormalization of the scattering continuum was investigated as a function of the scattering geometry to determine the superconducting energy gap 2Delta(k). The A1g- and B2g-symmetry component show a linear frequency behaviour of the scattering intensity with a peak related

R. S. Markiewicz

Spin-orbit coupling plays a large role in stabilizing the low-temperature orthorhombic phase of La$_{2-x}$Sr$_x$CuO$_4$. It splits the degeneracy of the van Hove singularities (thereby stabilizing the distorted phase) and completely changes the shape of the Fermi surfaces, potentially introducing diabolical points into the band structure. The present paper g

Penny D. Sackett, Hans-Walter Rix, Brian J. Jarvis, Kenneth C. Freeman

Kinematics and photometry of the polar ring galaxy NGC 4650A, including new observations of the rotation and velocity dispersion of its central stellar disk, are used to infer the presence of a dark matter halo and to measure its shape. Fits to the observed disk and polar ring rotation curves from detailed mass and photometric modeling rule out a spherical d

N. N. Nikolaev, B. G. Zakharov, V. R. Zoller

In hadron-nucleus interactions, the stronger is nuclear shadowing in the total cross section the higher is the multiplicity of secondary hadrons. In deep inelastic scattering, nuclear shadowing at small $x$ is associated with the hadronlike behaviour of photons as contrasted to the pointlike behaviour in the non-shadowing region of large $x$. In this paper w

Anders W. Sandvik, Marco Vekic

A two-dimensional Heisenberg model with random antiferromagnetic nearest-neighbor exchange is studied using quantum Monte Carlo techniques. As the strength of the randomness is increased, the system undergoes a transition from an antiferromagnetically ordered ground state to a gapless disordered state. The finite-size scaling of the staggered structure facto

Albert Kim

An extension to classical unification, called {\em graded unification} is presented. It is capable of combining contradictory information. An interactive processing paradigm and parser based on this new operator are also presented.

Ofer Lahav

A statistical method for reconstructing large scale structure behind the Zone of Avoidance is presented. It also corrects for shot-noise and for redshift distortion in galaxy surveys. The galaxy distribution is expanded in an orthogonal set of spherical harmonics. We show that in the framework of Bayesian statistics and Gaussian random fields the $4 π$ harmo

Ofer Lahav

The motivation and major ways for probing the Zone of Avoidance (ZOA) are reviewed. Galaxies hidden behind the ZOA may have important implications for the internal dynamics of the Local Group, for the origin of its motion relative to the Microwave Background, and for the connectivity of the large scale structure. Current direct (`observational') methods

F. Illuminati, M. Patriarca, P. Sodano

We generalize the oscillator model of a particle interacting with a thermal reservoir by introducing arbitrary nonlinear couplings in the particle coordinates.The equilibrium positions of the heat bath oscillators are promoted to space-time functions, which are shown to represent a modulation of the internal noise by the external forces. The model thus provi

Kelly Jay Davis

This set of lecture notes presents a pedantic derivation of the connection between the $ {\hat A} $-genus of spacetime's loop space and the genus one partition function of the $ N=1/2 $ sigma model. It concludes with some remarks on possible generalizations of the $ {\hat A} $-genus which follow naturally from the `stringy' point-of-view but have yet

J. Bicak, C. Cris, P. Hajicek, A. Higuchi

Static solutions of the Einstein-Yang-Mills-Higgs system containing extreme black holes are studied. The field equations imply strong restrictions on boundary values of all fields at the horizon. If the Yang-Mills radial electric field $E$ is non-zero there, then all fields at the horizon take values in the centralizer of $E$. For the particular case of SU(3

Svend E. Rugh

Is it possible to define what we could mean by chaos in a space-time metric (even in the simplest toy-model studies)? Is it of importance for phenomena we may search for in Nature?

B. L. Altshuler, L. B. Ioffe, A. J. Millis

We calculate the fermion Green function and particle-hole susceptibilities for a degenerate two-dimensional fermion system with a singular gauge interaction. We show that this is a strong coupling problem, with no small parameter other than the fermion spin degeneracy, N. We consider two interactions, one arising in the context of the $t-J$ model and the oth

Gregory Pelts

We demonstrate in detail how the space of two-dimensional quantum field theories can be parametrized by off-shell states of a free closed string moving in a flat background. The dynamic equation corresponding to the condition of conformal invariance includes an infinite number of higher order terms, and we give an explicit procedure for their calculation. Th

S. A. Gurvitz

We develop a new approach to carrier transport between the edge states via resonant scattering on impurities, which is applicable both for short and long range impurities. A detailed analysis of resonant scattering on a single impurity is performed. The results are used for study of the inter-edge transport by multiple resonant hopping via different impuriti

Christopher D. Carone, Howard Georgi, Lev Kaplan, David Morin

We study nonleptonic decays of the orbitally excited, \su6 \rep{70}-plet baryons in order to test the hypothesis that the successes of the nonrelativistic quark model have a natural explanation in the large-$N_c$ limit of QCD. By working in a Hartree approximation, we isolate a specific set of operators that contribute to the observed s- and d-wave decays in

John W. Barrett, Bruce W. Westbury

The invariants of 3-manifolds defined by Kuperberg for involutory Hopf algebras and those defined by the authors for spherical Hopf algebras are the same for Hopf algebras on which they are both defined.

Erick J. Weinberg

A formalism is developed to calculate the bubble nucleation rate in theories where the symmetry breaking is by radiative corrections. Although to leading and next-to-leading order the result can be expressed in terms of the effective action of the theory, this is not true of the higher order corrections. In particular, the imaginary part of the effective pot

H. Kachkachi

An effective action for $N=1$, 2d-induced supergravity in the chiral gauge is obtained on a compact super Riemann surface without boundary and of arbitrary genus.

William Nelson

In this note, we extend the string theoretic calculation of the black hole entropy, first performed by Susskind and Uglum, away from the infinite mass limit. It is shown that the result agrees with that obtained from the classical action of string theory, using the Noether charge method developed by Wald. Also shown in the process is the equivalence of two g

P. Berglund, S. Katz

We review various constructions of mirror symmetry in terms of Landau-Ginzburg orbifolds for arbitrary central charge $c$ and \CY\ hypersurfaces and complete intersections in toric varieties. In particular it is shown how the different techniques are related

S. Guruswamy, S. G. Rajeev, P. Vitale

We study a three dimensional conformal field theory in terms of its partition function on arbitrary curved spaces. The large $N$ limit of the nonlinear sigma model at the non-trivial fixed point is shown to be an example of a conformal field theory, using zeta--function regularization. We compute the critical properties of this model in various spaces of con

Kimyeong Lee, Erick J. Weinberg

The existence of nonsingular classical magnetic monopole solutions is usually understood in terms of topologically nontrivial Higgs field configurations. We show that finite energy magnetic monopole solutions also exist within a class of purely Abelian gauge theories containing charged vector mesons, even though the possibility of nontrivial topology does no

P. Bouwknegt, A. W. W. Ludwig, K. Schoutens

We study the description of the $SU(2)$, level $k=1$, Wess-Zumino-Witten conformal field theory in terms of the modes of the spin-1/2 affine primary field $ϕ^α$. These are shown to satisfy generalized `canonical commutation relations', which we use to construct a basis of Hilbert space in terms of representations of the Yangian $Y(sl_2)$. Using this desc

Alexander Turbiner

It is shown that the Coulomb correlation problem for a system of two electrons (two charged particles) in an external oscillator potential possesses a hidden $sl_2$-algebraic structure being one of recently-discovered quasi-exactly-solvable problems. The origin of existing exact solutions to this problem, recently discovered by several authors, is explained.

Mikhail S. Volkov

The fermion energy spectrum along paths which connect topologically distinct vacua in the Einstein-Yang-Mills theory passing through the gravitational sphaleron equilibrium solutions is investigated.

D. V. Nanopoulos

A rather simple and non-technical exposition of our new approach to {\em Time, Quantum Physics, Black-Hole dynamics}, and {\em Cosmology}, based on non-critical string theory, is provided. A new fundamental principle, the {\em Procrustean Principle}, that catches the essence of our approach is postulated: the low-energy world is {\em unavoidably} an ``open&#

G. Papadopoulos, P. K. Townsend

We recently obtained the conditions on the couplings of the general two-dimensional massive sigma-model required by (p,q)-supersymmetry. Here we compute the Poisson bracket algebra of the supersymmetry and central Noether charges, and show that the action is invariant under the automorphism group of this algebra. Surprisingly, for the (4,4) case the automorp

A. H. Chamseddine, J. Fröhlich

A general definition of Chern-Simons actions in non-commutative geometry is proposed and illustrated in several examples. These are based on ``space-times'' which are products of even-dimensional, Riemannian spin manifolds by a discrete (two-point) set. If the *algebras of operators describing the non-commutative spaces are generated by functions ove

Michael B. Green, Joe Polchinski

The moduli associated with boundaries in a Riemann surface are parametrized by the positions and strengths of electric charges. This suggests a method for summing over orientable Riemann surfaces with Dirichlet boundary conditions on the embedding coordinates. A light-cone parameterization of such boundaries is also discussed.

Eric Bergshoeff, Renata Kallosh, Tomas Ortin

Extreme 4-dimensional dilaton black holes embedded into 10-dimensional geometry are shown to be dual to the gravitational waves in string theory. The corresponding gravitational waves are the generalization of pp-fronted waves, called supersymmetric string waves. They are given by Brinkmann metric and the two-form field, without a dilaton. The non-diagonal p

Hidenori Sonoda, Wang-Chang Su

The short-distance singularity of the product of a composite scalar field that deforms a field theory and an arbitrary composite field can be expressed geometrically by the beta functions, anomalous dimensions, and a connection on the theory space. Using this relation, we compute the connection perturbatively for the O(N) non-linear sigma model in two dimens

J. Ohnemus, S. Rudaz, T. F. Walsh, P. M. Zerwas

Leptoquarks can be produced in pairs by gluon--gluon fusion and quark--antiquark annihilation at hadron colliders. While HERA is the proper machine for single production of $(eu)$ and $(ed)$ type leptoquarks, the flavor species of ($μu$), ($μd$) and ($τu$), ($τd$) type leptoquarks can be produced at hadron colliders very efficiently. Besides exploiting gluon

Kingman Cheung

It has recently been shown that the studies of strongly-interacting electroweak symmetry breaking (EWSB) at photon colliders, via photon splitting into $W$ pair followed by longitudinal $W$-boson scattering, could be possible. Here we present a signal-background analysis for the scattering channels $W^+_L W^-_L \to Z_L Z_L$ and $W^+_L W^-_L \to W^+_L W^-_L$

M. A. Ivanov, T. Mizutani

We have studied the weak decay constants and the Isgur-Wise form factor of the B and D mesons in the heavy quark limit, by employing a relativistic quark confinement model. It is an attempt to improve our previous work within the same line of thinking, but by incorporating a couple of novel aspects. First, the infrared behavior of the heavy quark is consider

Nir Polonsky

Only small regions in the $m_{t} - \tanβ$ plane are allowed when considering simultaneously (assuming the MSSM) coupling constant unification and (minimal) GUT relations among Yukawa couplings (i.e., $h_{b} = h_τ$ at the unification point). In particular, if $m_{t} \simle 175$ GeV we find that only $1 \simle \tanβ\simle 1.5$ or $\tanβ\simgr 40 \pm 10$ is all

Nir Polonsky, Alex Pomarol

In minimal supergravity theories the soft supersymmetry breaking (SSB) parameters are universal (flavor blind) near the Planck scale. Nevertheless, one often assumes universality at the grand-unification scale $M_{G} \approx 10^{16}$ GeV instead, and corrections to the SSB parameters arising from their evolution between the Planck and GUT scales are neglecte

G. W. Botz, D. Bruß, O. Nachtmann

We present a study of parity (P) violating polarization rotations of atoms in external electric fields. Five different types of rotations are identified and the consequences of time reversal invariance (T) are discussed. The role played by Zeldovich's electric dipole moment of unstable states is elucidated. To calculate the effects, we use the standard m

Harald Anlauf, Hans D. Dahmen, Angelika Himmler, Panagiotis Manakos

We report on the status of the Monte Carlo event generator WOPPER. Version 1.1 of WOPPER describes four fermion production at LEP-II and beyond with leading logarithmic radiative corrections in the double W pole approximation. These approximations are appropriate for almost all practical purposes, but the inclusion of these finite width effects and radiative

D. Ebert, T. Feldmann, R. Friedrich, H. Reinhardt

By bosonization of an extended NJL model we derive an effective meson theory which describes the interplay between chiral symmetry and heavy quark dynamics. This effective theory is worked out in the low-energy regime using the gradient expansion. The resulting effective lagrangian describes strong and weak interactions of heavy $B$ and $D$ mesons with pseud

V. V. Kiselev, A. K. Likhoded

We assume that a rather large bag of the $Υ''(3S b\bar b)$ heavy quarkonium is in the phase of spontaneously broken chiral symmetry, in contrast to the $Υ(1S b \bar b)$ hadron bag, having small size and being in the phase of exact chiral symmetry, so that the shift of the phases in the $Υ'' \to Υππ$ transition is the additional source for the

Zenrō Hioki, Ryuichi Najima

Based on the recent CDF report on the top-quark, we have carried out an analysis on the Higgs mass within the minimal standard electroweak theory using the latest data on the $W$-mass. Although this theory is in quite a happy situation now, we wish to point out that more precise measurements of $M_W$ and $m_t$ in the future are crucial and they could come to