April 1994 arXiv papers — page 7

Ken Ganga, Lyman Page, Edward Cheng, Stephan Meyer

In many cosmological models, the large angular scale anisotropy in the cosmic microwave background is parameterized by a spectral index, $n$, and a quadrupolar amplitude, $Q$. For a Peebles-Harrison-Zel'dovich spectrum, $n=1$. Using data from the Far Infra-Red Survey (FIRS) and a new statistical measure, a contour plot of the likelihood for cosmological

Lenore Levine

A cellular game is a dynamical system in which cells, placed in some discrete structure, are regarded as playing a game with their immediate neighbors. Individual strategies may be either deterministic or stochastic. Strategy success is measured according to some universal and unchanging criterion. Successful strategies persist and spread; unsuccessful ones

X. Shi, D. N. Schramm, D. S. P. Dearborn

Without assuming any solar models and neutrino flavor conversions, $^8$B neutrinos seen by the Kamiokande experiment should contribute 2.6$\pm 0.45$ SNU to the chlorine experiment. When this rate is compared with the total event rate of 2.3$\pm 0.2$ SNU observed by the Homestake experiment which should inlude a 0.2 SNU contribution from uncertainty-free pep

B. Berger, P. T. Chrusciel, V. Moncrief

In this paper we study space-times which evolve out of Cauchy data $(Σ,{}^3g,K)$ invariant under the action of a two-dimensional commutative Lie group. Moreover $(Σ,{}^3g,K)$ are assumed to satisfy certain completeness and asymptotic flatness conditions in spacelike directions. We show that asymptotic flatness and energy conditions exclude all topologies and

Valery P. Karassiov, Andrei B. Klimov

A new general Lie-algebraic approach is proposed to solving evolution tasks in some nonlinear problems of quantum physics with polynomially deformed Lie algebras $su_{pd}(2)$ as their dynamic symmetry algebras. The method makes use of an expansion of the evolution operators by power series in the $su_{pd}(2)$ shift operators and a (recursive) reduction of fi

Ralf Hempfling

We introduce a new approach for studying unified supergravity models. In this approach all the parameters of the grand unified theory (GUT) are fixed by imposing the corresponding number of low energy observables. This determines the remaining particle spectrum whose dependence on the low energy observables can now be investigated. We also include some SUSY

Gregory Moore

In a previous paper we showed that bracket relations uniquely fix the tree-level bosonic string $S$-matrix for $N\leq 26$ particle scattering. In this note we extend the proof to $N$-particle scattering for all $N$.

Kevin Haglin, Scott Pratt

Pion and kaon mean free paths within a thermal hadronic background are calculated using relativistic kinetic theory. Free cross sections are used which include contributions from $ρ$, $K^{*}$, $Δ$ and heavier resonances. Given pion to baryon ratios appropriate for the breakup stage of a $200\cdot A$GeV relativistic-heavy-ion collision, we find for temperatur

F. D. Santos, A. Arriaga

It is shown that in the $d(p,pp)n$ reaction with a colinear geometry and the two outgoing protons in a singlet state, the only two independent T-matrix elements can be determined from spin correlation experiments. These matrix elements are strongly dependent on the deuteron helicity amplitudes, which are expected to vanish for $1.4fm^{-1}<p<1.7fm^{-1}$.\vspa

S. N. Solodukhin

We consider the 2D Poincaré gravity and show its exact integrability. The choice of the gauge is discussed. The Euclidean solutions on compact closed differential manifolds are studied.

Hiroaki Nakano

When the supersymmetric theory contains the ``anomalous&#34; $U(1)$ gauge symmetry with Green-Schwarz anomaly cancellation mechanism in 4 dimensions, its Fayet-Iliopoulos $D$-term generates non-universal scalar masses and the positive cosmological constant after the supersymmetry breaking. Both give the new contributions to the known results from $F$-term. O

A. N. Leznov

We establish an explicit form of the Backlund transformation for the most known integrable systems.

A. Smilga, J. Verbaarschot

Based on the chiral symmetry breaking pattern and the corresponding low-energy effective lagrangian, we determine the fermion mass dependence of the partition function and derive sum rules for eigenvalues of the QCD Dirac operator in finite Euclidean volume. Results are given for $N_c = 2$ and for Yang-Mills theory coupled to several light adjoint Majorana f

M. A. C. Kneipp, D. I. Olive

Affine Toda field theories in two dimensions constitute families of integrable, relativistically invariant field theories in correspondence with the affine Kac-Moody algebras. The particles which are the quantum excitations of the fields display interesting patterns in their masses and coupling and which have recently been shown to extend to the classical so

Wolfgang Weich

The observable algebra O of SO_q(3)-symmetric quantum mechanics is generated by the coordinates of momentum and position spaces (which are both isomorphic to the SO_q(3)-covariant real quantum space R_q^3). Their interrelations are determined with the quantum group covariant differential calculus. For a quantum mechanical representation of O on a Hilbert spa

D. R. Grigore

We construct free fields of arbitrary spin in 1+2 dimensions i.e. free fields for which the one-particle Hilbert space carries a projective isometric irreducible representation of the Poincaré group in 1+2 dimensions. We analyse in detail these representations in the fiber bundle formalism and afterwards we apply Weinberg procedure to construct the free fiel

Kenji Ikegami

We define a discretized Langevin equation in Stratonovich-{\it type} calculus. We show that a generating functional with a field-dependent kernel can be written in mid-point prescription only when we calculate in the calculus. Moreover we investigate whether supersymmetry of the stochastic action with field-dependent kernel exists or not.

Tadahiko Kimura

We regularize the 3-D quantum electrodynamics by a parity invariant Pauli-Villars regularization method. We find that in the perturbation theory the Chern-Simons term is not induced in the massless fermion case and induced in the massive fermion case.

M. Greco, S. Rolli, A. Vicini

We study the inclusive photoproduction of neutral and charged pions and $η$ at HERA, via the resolved photon mechanism, in QCD to next-to-leading order. We present various distributions of phenomenological interest and study the theoretical uncertainties due to the mass scales, and to photon and proton sets of structure functions. A new set of fragmentation

Thomas G. Rizzo

Single $W_R$ production in $e^-e^-$ collisions at the NLC can be used to probe the Majorana nature of the heavy neutrinos present in the Left-Right Symmetric Model below the kinematic threshold for their direct production. For colliders in the $\sqrt {s}=1-1.5$ TeV range, typical cross sections of order $1-10 fb$ are obtained, depending on the specific choic

Katsuhiko Suzuki

We study roles of quark-quark correlations in the baryons for the deep inelastic structure function and the ${\Delta}I=1/2$ rule of the non-leptonic weak hyperon decay. The quark-quark correlation is incorporated phenomenologically as diquarks within the Nambu and Jona-Lasinio model. The strong diquark correlations in the spin-0 channel enhance the ${\Delta}

A. Ballestrero, E. Maina

An helicity formalism for perturbative calculations is presented. It is based on the formal insertion in spinor lines of a complete set of states built up with unphysical spinors. It is particularly convenient when massive spinors are present. Its application to $e^+\,e^-\,\rightarrow b\,\bar b\,W^+W^-$ is briefly discussed.

R. Alkofer, H. Reinhardt, J. Schlienz, H. Weigel

The role of chiral transformations in effective theories modeling Quantum Chromo Dynamics is reviewed. In the context of the Nambu--Jona--Lasinio model the hidden gauge and massive Yang--Mills approaches to vector mesons are demonstrated to be linked by a special chiral transformation which removes the chiral field from the scalar--pseudoscalar sector. The r

N. Kodama, M. Oka, T. Hatsuda

The QCD sum rule is applied to the H dibaryon and is compared to the flavor non-singlet di-nucleon. We find that the H dibaryon is almost degenerate to the di-nucleon in the $SU(3)_{flavor}$ limit and therefore is not deeply bound as far as th\ e threshold parameter is adjusted not to have a di-nucleon bound state. After introducing the $SU(3)_{f}$ breaking

Eilam Gross, Bernd A. Kniehl, Gustavo Wolf

We collect and update theoretical predictions for the production rate and decay branching fractions of the Standard Model Higgs boson that will be relevant for the Higgs search at LEP200. We make full use of the present knowledge of radiative corrections. We estimate the systematics arising from theoretical and experimental uncertainties.

James D. Wells

A simple method to calculate the total annihilation cross section of massive cold relics is presented. Exact expressions for $\arel$, $\brel$, and $\crel$ of $σ\vrel=\arel+\brel \vrel^2+\crel \vrel^4$ are obtained from simple derivatives of the squared annihilation amplitude. Three examples are given. In one example, the computed annihilation cross section o

A. D. Y. Cheng, P. D. D&#39;Eath, P. R. L. V. Moniz

Diagonal Bianchi type-IX models are studied in the quantum theory of $ N = 1 $ supergravity with a cosmological constant. It is shown, by imposing the supersymmetry and Lorentz quantum constraints, that there are no physical quantum states in this model. The $ k = + 1 $ Friedmann model in supergravity with cosmological constant does admit quantum states. How

David Brown

The idea that spacetime points are to be identified by a fleet of clock--carrying particles can be traced to the earliest days of general relativity. Such a fleet of clocks can be described phenomenologically as a reference fluid. One approach to the problem of time consists in coupling the metric to a reference fluid and solving the super--Hamiltonian const

David Brown

Simple calculations indicate that the partition function for a black hole is defined only if the temperature is fixed on a finite boundary. Consequences of this result are discussed. (Contribution to the Proceedings of the Lanczos Centenary Conference.)

Dung-Hai Lee

We obtain the field-theory representations of several network models that are relevant to 2D transport in high magnetic fields. Among them, the simplest one, which is relevant to the plateau transition in the quantum Hall effect, is equivalent to a particular representation of an antiferromagnetic SU(2N) ($N\rightarrow 0$) spin chain. Since the later can be

Dung-Hai Lee

We obtain the field-theory representations of several network models that are relevant to 2D transport in high magnetic fields. Among them, the simplest one, which is relevant to the plateau transition in the quantum Hall effect, is equivalent to a particular representation of an antiferromagnetic SU(2N) ($N\to 0$) spin chain. Since the later can be mapped o

J. M. P. Carmelo, A. H. Castro Neto, D. K. Campbell

We show that the recently developed {\it pseudoparticle operator algebra} which generates the low-energy Hamiltonian eigenstates of multicomponent integrable systems also provides a natural operator representation for the the Virasoro algebras associated with the conformal-invariant character of the low-energy spectrum of the these models. Studying explicitl

J. M. P. Carmelo, A. H. Castro Neto, D. K. Campbell

We introduce a new operator algebra for the description of the low-energy physics of one-dimensional, integrable, multicomponent quantum liquids. Considering the particular case of the Hubbard chain in a constant external magnetic field and with varying chemical potential, we show that at low energy its Bethe-ansatz solution can be interpreted in terms of th

Heiko Rieger, A. Peter Young

We study the quantum transition at $T=0$ in the spin-$\frac12$ Ising spin--glass in a transverse field in two dimensions. The world line path integral representation of this model corresponds to an effective classical system in (2+1) dimensions, which we study by Monte Carlo simulations. Values of the critical exponents are estimated by a finite-size scaling

Michael A. Covington

Dependency grammar is usually interpreted as equivalent to a strict form of X--bar theory that forbids the stacking of nodes of the same bar level (e.g., N&#39; immediately dominating N&#39; with the same head). But adequate accounts of _one_--anaphora and of the semantics of multiple modifiers require such stacking and accordingly argue against dependency g

Dany Page

We show that Geminga&#39;s surface temperature can be understood by both types of neutrino cooling scenarios, i.e, slow neutrino cooling by the modified Urca process or fast neutrino cooling by the direct Urca process or by some exotic matter, and thus does not allow us to discriminate between these two competing schemes. However, for both types of scenarios

Emory F. Bunn, Karl B. Fisher, Yehuda Hoffman, Ofer Lahav

We derive an optimal linear filter to suppress the noise from the COBE DMR sky maps for a given power spectrum. We then apply the filter to the first-year DMR data, after removing pixels within $20^\circ$ of the Galactic plane from the data. The filtered data have uncertainties 12 times smaller than the noise level of the raw data. We use the formalism of co

P. A. Johnson

The contribution to the local cosmic-ray flux from the Geminga supernova is calculated assuming shock acceleration to 10^14 eV in a remnant which was formed several 10^5 years ago along with the Geminga pulsar. The particles are propagated to Earth using a simple diffusion model. In the region below the knee in the spectrum, it is found the supernova may con

Kieran G. O&#39;Grady

We prove that moduli spaces of torsion-free sheaves on a projective smooth complex surface are irreducible, reduced and of the expected dimension, provided the expected dimension is large enough. Actually we prove more: given a line bundle on the surface, we show that the number of moduli of sheaves which have a non-zero twisted (by the chosen line-bundle) e

Chong-Sun Chu, Pei-Ming Ho, Harold Steinacker

We construct the deformed Dirac monopole on the quantum sphere for arbitrary charge using two different methods and show that it is a quantum principal bundle in the sense of Brzezinski and Majid. We also give a connection and calculate the analog of its Chern number by integrating the curvature over $S^2_q$.

Atsushi Moriwaki

In this note, we will consider an arithmetic analogue of Bogomolov unstability theorem.

Z. Lalak, S. Lola, B. A. Ovrut, G. G. Ross

We give an analytical description of the spatial distribution of domain walls produced during a biased nonequilibrium phase transition in the vacuum state of a light scalar field. We discuss in detail the spectrum of the associated cosmological energy density perturbations. It is shown that the contribution coming from domain walls can enhance the standard c

Brian D. Wright

We consider a particular class of threshold corrections to Yukawa couplings and mass relations in the MSSM and supersymmetric grand unified models. We give a complete treatment of Yukawa coupling thresholds at the unification scale $\Mx$ and the effective supersymmetry scale $\Ms$ and apply them to corrections to the tree-level prediction $y_b(\Mx) = y_τ(\Mx

A. B. Finnila, M. A. Gomez, C. Sebenik, C. Stenson

Quantum annealing is a new method for finding extrema of multidimensional functions. Based on an extension of classical, simulated annealing, this approach appears robust with respect to avoiding local minima. Further, unlike some of its predecessors, it does not require an approximation to a wavefunction. In this paper, we apply the technique to the problem

S. Takahara, N. Onishi, N. Tajima

The properties of pairing correlation in nuclear matter are investigated by using various versions of Skyrme forces. Truncation of states involving pairing correlation, necessary due to zero range nature of the Skyrme force, is discussed in detail. A plateau appears in pairing gap versus cutoff for each force. We propose to choose the cutoff parameter in the

H. Neidhardt, V. A. Zagrebnov

We present an abstract result on removing regularization for singular potentials which are not semibounded from below. The relation between ``right&#39;&#39; regularizations and ``right&#39;&#39; self-adjoint extensions of the perturbed Schrödinger operators is examined.

D. K. Srivastava, Jicai Pan, V. Emel'yanov, C. Gale

The so-called $M_T$ scaling for dilepton spectra at RHIC energies is examined. It is seen that a proper accounting of the complete set of dilepton producing processes forces us to abandon the proposed scaling around $M_T$ = 2.6 GeV, which has been put forward as a possible signature of the presence of quark-matter. Any substantial transverse expansion in the

Xing-Wang Pan, Da Hsuan Feng

According to the analysis based on the fermion dynamical symmetry model, nuclei previously regarded as SO(6)-like (e.g. $^{128}$Xe and $^{196}$Pt) are shown to be more akin to the transitional nuclei between SO(7) and SO(6) symmetries.

N. Auerbach, V. Spevak

In this work we formulate the reaction theory of parity violation in compound nuclear states using Feshbach&#39;s projection operator formalism. We derive in this framework a complete set of terms that contribute to the longitudinal asymmetry measured in experiments with polarized epithermal neutrons. We also discuss the parity violating spreading width resu

V. G. J. Stoks, Th. A. Rijken

We report on the progress of the construction of the extended soft-core (ESC) Nijmegen potential. Next to the standard one-boson-exchange parts, the model includes the pion-meson-exchange potentials due to the parallel and crossed-box diagrams, as well as the one-pair and two-pair diagrams, vertices for which can be identified with similar interactions appea

Wei Chen

(2+1) dimensional gravity is equivalent to an exactly soluble non-Abelian Chern-Simons gauge field theory (E Witten 1988). Regarding this as the topological phase of quantum gravity in (2+1)d, we suggest a topological symmetry breaking by introducing a mass term for the gauge fields, which carries a space-time metric and local dynamical degrees of freedom. W

A. H. Bougourzi, Robert A. Weston

We construct five independent screening currents associated with the $U_q(\widehat{sl(3)})$ quantum current algebra. The screening currents are expressed as exponentials of the eight basic deformed bosonic fields that are required in the quantum analogue of the Wakimoto realization of the current algebra. Four of the screening currents are `simple&#39;, in t

S. Odintsov, R. Percacci

We discuss the ``gravitationally dressed&#39;&#39; beta functions in the Gross--Neveu model interacting with 2d Liouville theory and in $SU(N)$ gauge theory interacting with the conformal sector of 4d quantum gravity. Among the effects that we suggest may feel the gravitational dressing are the minimum of the effective potential and the running of the gauge

Abhay Ashtekar

This article is based on an invited talk given at the Workshop on Mathematical Physics Towards XXIst Century, held at Beer-Sheva, Israel in 1993. It contains an introduction to quantum gravity for mathematical physicists with an emphasis on the difference between the structure of this theory from more familiar, Minkowskian quantum field theories which arise

C. Duval, Z. Horváth, P. A. Horváthy

The vanishing of the anomaly in the recent example of Nappi and Witten, constructed from the Wess-Zumino-Witten model based on a certain non-semisimple group, follows from a more general result valid for gravitational waves. The construction of the metric is explained.}

O. Castaños, R. López-Peña, V. I. Man&#39;ko

A two-dimensional generalized oscillator with time-dependent parameters is considered to study the two-mode squeezing phenomena. Specific choices of the parameters are used to determine the dispersion matrix and analytic expressions, in terms of standard hermite polynomials, of the wavefunctions and photon distributions. (to be publish in the Third Workshop

D. Persson, Vad. Zeitlin

Using a generalized proper-time method, we obtain expressions for the fermion density and the QED effective Lagrangian for an external magnetic field at finite chemical potential. The effective Lagrangian and the density are here written in terms of elementary functions, summed over a finite number of filled Landau levels.

Hans-Thomas Elze

Entropy is generated in high-multiplying events by a dynamical separation of strongly interacting systems into partons and unobservable environment modes (almost constant field configurations) due to confinement.

Junegone Chay, Soo-Jong Rey

We study instanton effects on inclusive semileptonic $b \rightarrow u$ decay using the heavy quark effective field theory and the operator product expansion. The effect contributes not only to the hadronic matrix element but also to the coefficient functions in the operator product expansion. We find that the coefficient function is singular near the boundar

I. B. Khriplovich, A. I. Milstein

Relativistic corrections to the positronium decay rate are calculated. They are close to $40(α/π)^2$ and $46(α/π)^2$ for singlet and triplet states respectively.

H. Baer, C. H. Chen, F. Paige, X. Tata

We study direct production of charginos and neutralinos at the CERN Large Hadron Collider. We simulate all channels of chargino and neutralino production using ISAJET 7.07. The best mode for observing such processes appears to be $pp\to\tw_1\tz_2\to 3\ell +\eslt$. We evaluate signal expectations and background levels, and suggest cuts to optimize the signal.

Andrei L. Talapov, Lev N. Shchur

High accuracy Monte Carlo simulation results for 1024*1024 Ising system with ferromagnetic impurity bonds are presented. Spin-spin correlation function at a critical point is found to be numerically very close to that of a pure system. This is not trivial since a critical temperature for the system with impurities is almost two times lower than pure Ising $T

C. Michael, P. S. Spencer

We present calculations of the size distribution of instantons in the 2d O(3) non-linear sigma-model, and briefly discuss the effects cooling has upon the configurations and the topological objects. (This preprint is also available via anonymous ftp to suna.amtp.liv.ac.uk in /pub/pss/ as instdist.uue.)

Gérard Clément

The solution of topologically massive gravity with cosmological constant is reduced, for space-times with two commuting Killing vectors, to a special-relativistic dynamical problem. This approach is applied to the construction of a class of exact sourceless, horizonless solutions asymptotic to the BTZ extreme black holes.

Kurt A. Mader, Alex Zunger

Self-consistent electronic structure calculations together with a structural model are used to study the effect of short-range atomic order on the optical properties of otherwise random Al(0.5)Ga(0.5)As, Ga(0.5)In(0.5)P, and Al(0.5)In(0.5)As alloys. We find that clustering can reduce the direct band gap of these alloys by as much as 100 meV. Furthermore, suf

E. R. Mucciolo, R. B. Capaz, B. L. Altshuler, J. D. Joannopoulos

We use semiconductors as an example to show that quantum chaos manifests itself in the energy spectrum of crystals. We analyze the {\it ab initio} band structure of silicon and the tight-binding spectrum of the alloy $Al_xGa_{1-x}As$, and show that some of their statistical properties obey the universal predictions of quantum chaos derived from the theory of

R. G. Carlberg

Hierarchical gravitational clustering creates galaxies that usually do not fully share the dynamical history of an average particle in the mass field. In particular, galaxy tracers identified in numerical simulations can have individual velocity dispersions in virialized regions a factor \bvs\ lower than the dark matter. The field average of the pairwise vel

John Dubinski, Konrad Kuijken

When a galaxy forms, the disk may initially be tilted with respect to a flattened dark halo. The misalignment between the disk and the halo is a common explanation for galactic disk warps, since in this state, disks have precessing bending modes which resemble real warps. A dubious assumption in this theory is that the gravitational response of the halo is n

Miles Reid

This paper studies reduced, connected, Gorenstein surfaces with ample -K, assumed to be reducible or nonnormal. The normalisation is a union of one or more standard surfaces (scrolls and Veronese surfaces), marked with a conic as double locus. The question is how to glue these together to get a Gorenstein scheme. In characteristic 0, the results amount to a

Arnaud Beauville

Riemann surface carries a natural line bundle, the determinant bundle. The space of sections of this line bundle (or its multiples) constitutes a natural non-abelian generalization of the spaces of theta functions on the Jacobian. There has been much progress in the last few years towards a better understanding of these spaces, including a rigorous proof of

S. Narison, :

We review the determinations of the QCD coupling $α_s$ from the inclusive and exclusive modes of $τ$-decays. The most recent $τ$-data provide the average value $ α_ s \left(M^2_τ\right)\simeq 0.347\pm 0.030 $ corresponding to $ α_ s \left(M^2_Z \right) \simeq 0.121\pm 0.003 \pm 0.001.$ The values of the QCD vacuum condensates extracted from the inclusive wei

Stuart M. Shieber

The formalism of synchronous tree-adjoining grammars, a variant of standard tree-adjoining grammars (TAG), was intended to allow the use of TAGs for language transduction in addition to language specification. In previous work, the definition of the transduction relation defined by a synchronous TAG was given by appeal to an iterative rewriting process. The

Shoudan Liang, Hanbin Pang

We have studied the stability of the ferromagnetic state in the infinite-U Hubbard model on a square lattice by approximate diagonalization of finite lattices using the density matrix renormalization group technique. By studying lattices with up to 5X20 sites, we have found the ferromagnetic state to be stable below the hole density of 22 percent. Beyond 22

Joel Langer, Ron Perline

The three equations named in the title are examples of infinite-dimensional completely integrable Hamiltonian systems, and are related to each other via simple geometric constructions. In this paper, these interrelationships are further explained in terms of the recursion operator for the Localized Induction Equation, and the recursion operator is seen to pl

O. Castaños, R. López-Peña, V. I. Man&#39;ko

The time dependent-integrals of motion, linear in position and momentum operators, of a quantum system are extracted from Noether&#39;s theorem prescription by means of special time-dependent variations of coordinates. For the stationary case of the generalized two-dimensional harmonic oscillator, the time-independent integrals of motion are shown to corresp

Pijush K. Ghosh, Avinash Khare

We obtain both topological as well as nontopological self-dual charged vortex solutions of finite energy per unit length in a generalized abelian Higgs model in $3+1$ dimensions. In this model the Bogomol&#39;nyi bound on the energy per unit length is obtained as a linear combination of the magnetic flux and the electric charge per unit length.

G. Gat, R. Ray

The behavior of finite temperature planar electrodynamics is investigated. We calculate the static as well as dynamic characteristic functions using real time formalism. The temperature and density dependence of dielectric and permeability functions, plasmon frequencies and their relation to the screening length is determined. The radiative correction to the

L. D. Faddeev

In these lectures the introduction to algebraic aspects of Bethe Ansatz is given. The applications to the seminal spin 1/2 XXX model is discussed in detail and the generalization to higher spin as well as XXZ and lattice Sine-Gordon model are indicated. The origin of quantum groups and their appearance in CFT models is explained. The text can be considered a

Krzysztof Gawedzki

We express the correlation functions of the SU(2) WZW conformal field theory on Riemann surfaces of genus >1 by finite dimensional integrals.

Alon E. Faraggi

I outline a program to derive the Standard Model directly from superstring theory. I present a class of three generation superstring standard--like models in the free fermionic formulation. I discuss some phenomenological properties of these models. In particular these models suggest an explanation for the top quark mass hierarchy. A numerical estimate yield

R. S. Chivukula, E. H. Simmons, J. Terning

We explore corrections to electroweak parameters in the context of Extended Technicolor (ETC) models in which the ETC gauge-boson which generates the top-quark mass carries weak $SU(2)$ charge. For $m_t \sim 150$ GeV there exist potentially large corrections to the $Z$ decay width to $b$-quarks. Interestingly, in contrast to the situation in ETC models where

Carl H. Brans

Gompf&#39;s end-sum techniques are used to establish the existence of an infinity of non-diffeomorphic manifolds, all having the same trivial ${\bf R^4}$ topology, but for which the exotic differentiable structure is confined to a region which is spatially limited. Thus, the smoothness is standard outside of a region which is topologically (but not smoothly)

E. Frey, U. C. Täuber, F. Schwabl

Percolation clusters are probably the simplest example for scale--invariant structures which either are governed by isotropic scaling--laws (``self--similarity&#39;&#39;) or --- as in the case of directed percolation --- may display anisotropic scaling behavior (``self--affinity&#39;&#39;). Taking advantage of the fact that both isotropic and directed bond p

Stuart M. Shieber

We report on the recent Loebner prize competition inspired by Turing&#39;s test of intelligent behavior. The presentation covers the structure of the competition and the outcome of its first instantiation in an actual event, and an analysis of the purpose, design, and appropriateness of such a competition. We argue that the competition has no clear purpose,

Yves Schabes, Stuart M. Shieber

The precise formulation of derivation for tree-adjoining grammars has important ramifications for a wide variety of uses of the formalism, from syntactic analysis to semantic interpretation and statistical language modeling. We argue that the definition of tree-adjoining derivation must be reformulated in order to manifest the proper linguistic dependencies

John N. Bahcall

The claim by Dar and Shaviv that they have found a standard model solution to the solar neutrino problem is based upon an incorrect assumption made in extrapolating nuclear cross sections and the selective use of a small fraction of the nuclear physics and of the neutrino data. In addition, five different solar model codes show that the rate obtained for the

T. R. Bedding, J. G. Robertson, R. G. Marson

MAPPIT is an optical interferometer installed at the coude focus of the 3.9-m Anglo-Australian Telescope. The instrument combines non-redundant masking with wavelength dispersion and is able to record fringes simultaneously over a wide bandwidth. For typical observations centred near 600 nm, the bandwidth is 55 nm and the spectral resolution is 3 nm. This pa

Xinmin Zhang

In this paper I propose an scenario for the top quark as a topological color soliton. I illustrate some features of the top quark as a soliton in a toy model based on nonlinear realization of the $SU(3)_L \times SU(3)_R / SU(3)_{L+R}$, with $SU(3)_{L+R}$ being the color gauge group.

S. M. Kuzenko, S. L. Lyakhovich, A. Yu. Segal

A new model of relativistic massive particle with arbitrary spin (($m,s$)-particle) is suggested. Configuration space of the model is a product of Minkowski space and two-dimensional sphere, ${\cal M}^6 = {\Bbb R}^{3,1} \times S^2$. The system describes Zitterbewegung at the classical level. Together with explicitly realized Poincar\'e symmetry, the action f

S. Hyun, J. -S. Park

The $N=2$ topological Yang-Mills and holomorphic Yang-Mills theories on simply connected compact Kähler surfaces with $p_g\geq 1$ are reexamined. The $N=2$ symmetry is clarified in terms of a Dolbeault model of the equivariant cohomology. We realize the non-algebraic part of Donaldson&#39;s polynomial invariants as well as the algebraic part. We calculate Do

Huaxin Lin, N. Christopher Phillips

We prove a classification theorem for purely infinte simple C*-algebras that is strong enough to show that the tensor products of two different irrational rotation algebras with the same even Cuntz algebra are isomorphic. In more detail, let C be be the class of simple C*-algebras A which are direct limits A = lim A_k, in which each A_k is a finite direct su

Bong H. Lian, Gregg J. Zuckerman

We discuss the notion of a Batalin-Vilkovisky (BV) algebra and give several classical examples from differential geometry and Lie theory. We introduce the notion of a quantum operator algebra (QOA) as a generalization of a classical operator algebra. In some examples, we view a QOA as a deformation of a commutative algebra. We then review the notion of a ver

S. Aoyama, Y. Kodama

We present a new class of topological conformal field theories (TCFT) characterized by a rational $W$ potential, which includes the minimal models of A and D types as its subclasses. An explicit form of the $W$ potential is found by solving the underlying dispersionless KP hierarchy in a particular small phase space. We discuss also the dispersionless KP hie

J. Polchinski, L. Thorlacius

The theory of a massless two-dimensional scalar field with a periodic boundary interaction is considered. At a critical value of the period this system defines a conformal field theory and can be re-expressed in terms of free fermions, which provide a simple realization of a hidden $SU(2)$ symmetry of the original theory. The partition function and the bound

Philippe Zaugg

A new derivation of the quantum deformation of the 2 dimensional Euclidean Poincare group (cf S. Zakrzewski) is proposed. It is based on a contraction of the Hopf algebra Fun(SO_q(3)). The deformation parameter q is sent to one, as in the construction of the $κ$-Poincare deformed algebra. The quantum group obtained is dual to that algebra.

R. Kallosh, T. Ortin

We discuss stationary supersymmetric bosonic configurations of the Einstein-Maxwell theory embedded in $N=2$ supergravity. Some of these configurations, including the Kerr-Newman solutions with $m = |q|$ and arbitrary angular momentum per unit mass $a$, exhibit naked singularities. However, $N=2$ supergravity has trace anomaly. The nonvanishing anomalous ene

Ling-Lie Chau, Hai-Yang Cheng

The decay rates of $D^+\toπ^+π^0$ and $D^0\to K^+π^-$ recently measured by CLEO give the ratios $R_1=2|V_{cs}/V_{cd}|^2Γ(D^+\to π^+π^0)/Γ(D^+\to\bar{K}^0 π^+)=3.29\pm 1.16$ and $R_2=|V_{cs}^*V_{ud}/(V_{cd}^*V_{us})|^2Γ(D^0\to K^+π^-)/Γ(D^0\to K^-π^+)=2.92\pm 1.34\,$. Both are about three times of those expected from SU(3) symmetry. We show that, in the large

Tevian Dray, Charles Hellaby

The divergence theorem in its usual form applies only to suitably smooth vector fields. For vector fields which are merely piecewise smooth, as is natural at a boundary between regions with different physical properties, one must patch together the divergence theorem applied separately in each region. We give an elegant derivation of the resulting &#34;patch

Charles Hellaby, Tevian Dray

The Divergence Theorem as usually stated cannot be applied across a change of signature unless it is re-expressed to allow for a finite source term on the signature change surface. Consequently all conservation laws must also be `modified&#39;, and therefore insistence on conservation of matter across such a surface cannot be physically justified. The Darmoi

A. Mironov, A. Morozov, G. Semenoff

We advocate a new approach to the study of unitary matrix models in external fields which emphasizes their relationship to Generalized Kontsevich Models (GKM) with non-polynomial potentials. For example, we show that the partition function of the Brezin-Gross-Witten Model (BGWM), which is defined as an integral over unitary $N\times N$ matrices, $\int [dU] e