October 1994 arXiv papers — page 3

George Lavrelashvili

Talk given at the 7th Marcel Grossmann Meeting on General Relativity, Stanford University, July 24-30, 1994.

Jae Kwan Kim, Hyeonjoon Shin

In topologically massive QED$_{2+1}$ with $N$ flavours, there is the possibility that two equal-charged fermions can form a bound state pair in either s-wave or p-wave. We are concerned about the s-wave pairs and obtain the low energy effective action describing them. It is shown that the fermion pairs behave like doubly charged spin-1 bosons and, when they

Salman Habib

We consider a simple quantum system subjected to a classical random force. Under certain conditions it is shown that the noise-averaged Wigner function of the system follows an integro-differential stochastic Liouville equation. In the simple case of polynomial noise-couplings this equation reduces to a generalized Fokker-Planck form. With nonlinear noise in

C. N. Leung, P. I. Krastev

The prospects of using spectral measurements of solar neutrinos to distinguish different mechanisms of neutrino flavor mixing are analyzed. The mechanisms studied include the conventional mass mixing mechanism and an alternative mechanism which assumes a flavor nondiagonal neutrino-gravity coupling.

T. E. Clark, S. T. Love

A fine tuned hierarchy between a strongly coupled high energy compositeness scale and a much lower chiral symmetry breaking scale is a requisite ingredient in many models of dynamical electroweak symmetry breaking. Using a nonperturbative continuous Wilson renormalization group equation approach, we explore the stability of such a hierarchy against quantum f

K. Whisnant, Bing-Lin Young, X. Zhang

Unitarity constraints on anomalous top-Higgs couplings are examined. We also compare the unitarity constraints with the constraints from electroweak baryogenesis and electric dipole moments derived earlier.

Stefan Blaser

We evaluate the branching ratios for the decays $K\rightarrow πππeν$ at leading order in chiral perturbation theory and give an isospin relation for the decay rates.

R. Michael Barnett

We review ongoing efforts and discuss possible future directions in informing the public and educating students about Particle Physics.

N. L. Ter-Isaakyan

It is shown that in the special infinite momentum frame where photon has pure transverse components at $P\rightarrow\infty$ the spin-dependent deep inelastic structure function $ g_{2}(x)$ has a reasonable interpretation in terms of quark-parton wave functions, whereas in the conventional frame where photon has pure z-component the parton model fails for $ g

S. Dawson, G. Valencia

We place bounds on anomalous gauge boson couplings from LEP data with particular emphasis on those couplings which do not contribute to $Z$ decays at tree level. We use an effective field theory formalism to compute the one-loop corrections to the $Z\rightarrow {\overline f} f$ decay widths resulting from non-standard model three and four gauge boson vertice

C. A. Dominguez

QCD sum rules are based on the Operator Product Expansion of current correlators, and on QCD-hadron duality. An extension of this program to finite temperature is discussed. This allows for a study of deconfinement and chiral-symmetry restoration. In addition, it is possible to relate certain hadronic matrix elements to expectation values of quark and gluon

C. A. Dominguez

I review recent determinations of the (on-shell) charm- and beauty-quark masses in the framework of relativistic and non-relativistic ratios of Laplace transform QCD moment sum rules. The validity of the non-relativistic version of QCD sum rules in this particular application is discussed.

Dima Bardin, Arnd Leike, Tord Riemann

The cross sections for the reaction $e^+ e^- \rightarrow l \bar l q \bar q $ and for similar four fermion production processes at LEP~1, LEP~2 and the NLC are calculated. Due to the extraordinary symmetry properties of the process, very compact analytical formulae describe the double differential distributions in the invariant masses of the $l \bar l$ and $q

K. A. Bronnikov, V. N. Melnikov

Vacuum cosmological models are considered in the context of a multidimensional theory of gravity with integrable Weyl geometry. A family of exact solutions with a chain of internal spaces is obtained. Models with one internal space are considered in more detail; nonsingular models are selected.

Emilio de Santis, Giorgio Parisi, Felix Ritort

We study the static as well as the glassy or dynamical transition in the mean-field $p$-state Potts glass. By numerical solution of the saddle point equations we investigate the static and the dynamical transition for all values of $p$ in the non-perturbative regime $p>4$. The static and dynamical Edwards-Anderson parameter increase with $p$ logarithmically.

T. Einarsson, H. J. Schulz

We calculate the spin stiffness $ρ_s$ for the frustrated spin-$\frac{1}{2}$ Heisenberg antiferromagnet on a square lattice by exact diagonalizations on finite clusters of up to $36$ sites followed by extrapolations to the thermodynamic limit. For the non-frustrated case, we find that $ρ_s = (0.183\pm 0.003)J_1$, in excellent agreement with the best results o

Enzo Marinari, Giorgio Parisi, Felix Ritort

We discuss the behavior of the fully frustrated hypercubic cell in the infinite dimensional mean-field limit. In the Ising case the system undergoes a glass transition, well described by the random orthogonal model. Under the glass temperature aging effects show clearly. In the $XY$ case there is no sign of a phase transition, and the system is always a para

Giorgio Parisi

We study the statistical mechanics of a $D$-dimensional array of Josephson junctions in presence of a magnetic field. In the high temperature region the thermodynamical properties can be computed in the limit $D \to \infty$, where the problem is simplified; this limit is taken in the framework of the mean field approximation. Close to the transition point th

A. Fledderjohann, P. J. Hirschfeld

Recent thermal conductivity measurements on $UPt_3$ single crystals by Lussier et al. indicate the existence of a strong b--c anisotropy in the superconducting state. We calculate the thermal conductivity in various unconventional candidate states appropriate for the $UPt_3$ ``B phase" and compare with experiment, specifically the $E_{2u}$ and $E_{1g}$ $

Mats Wirén

Ideally, the time that an incremental algorithm uses to process a change should be a function of the size of the change rather than, say, the size of the entire current input. Based on a formalization of ``the set of things changed'' by an incremental modification, this paper investigates how and to what extent it is possible to give such a guarantee

Andre Kempe

The described tagger is based on a hidden Markov model and uses tags composed of features such as part-of-speech, gender, etc. The contextual probability of a tag (state transition probability) is deduced from the contextual probabilities of its feature-value-pairs. This approach is advantageous when the available training corpus is small and the tag set lar

Eric Brill, Philip Resnik

In this paper, we describe a new corpus-based approach to prepositional phrase attachment disambiguation, and present results comparing performance of this algorithm with other corpus-based approaches to this problem.

Pasi Tapanainen, Timo Järvinen

We are concerned with the syntactic annotation of unrestricted text. We combine a rule-based analysis with subsequent exploitation of empirical data. The rule-based surface syntactic analyser leaves some amount of ambiguity in the output that is resolved using empirical patterns. We have implemented a system for generating and applying corpus-based patterns.

S. Zaroubi, Y. Hoffman, K. B. Fisher, O. Lahav

The formalism of Wiener filtering is developed here for the purpose of reconstructing the large scale structure of the universe from noisy, sparse and incomplete data. The method is based on a linear minimum variance solution, given data and an assumed \prior model which specifies the covariance matrix of the field to be reconstructed. While earlier applicat

Martin G. Haehnelt

The role of momentum transfer (``radiation pressure'') due to an internal source of ionizing radiation for the formation of baryonic structures is investigated. Fully-ionized self-gravitating gaseous objects can be radiation-pressure supported on a characteristic length scale $D_{\rm rp} \sim 100 \pc - 3 \kpc$. On smaller scales momentum transfer due

Dmitri Zaitsev

Let $D$ be a bounded domain in $C^n$. By the theorem of H.~Cartan, the group $Aut(D)$ of all biholomorphic automorphisms of $D$ has a unique structure of a real Lie group such that the action $Aut(D)\times D\to D$ is real analytic. This structure is defined by the embedding $C_v\colon Aut(D)\hookrightarrow D\times Gl_n(C)$, $f\mapsto (f(v), f_{*v})$, where $

A. Gurevich, A. Lukyanov, K. Zybin

The plasma turbulence as is well known plays crucial role in the processes of plasma dynamics and transport phenomena. It affects both macroscopic plasma behaviour and distribution of particles, and besides suprathermal component of particle ensemble is even more sensitive to turbulent processes. We have performed investigation of behaviour of fast particles

Aaron Bertram

This paper works out the versions of the classical Giambelli and Pieri formulas in the context of quantum cohomology of a complex Grassmannian.

L. E. Mendes, A. B. Henriques, R. G. Moorhouse

In this paper we calculate the Bogoliubov coefficients and the energy density of the stochastic gravitational wave background for a universe that undergoes inflation followed by radiation domination and matter domination, using a formalism that gives the Bogoliubov coefficients as continous functions of time. By making a reasonable assumption for the equatio

Steven Bird

In this paper I report on an investigation into the problem of assigning tones to pitch contours. The proposed model is intended to serve as a tool for phonologists working on instrumentally obtained pitch data from tone languages. Motivation and exemplification for the model is provided by data taken from my fieldwork on Bamileke Dschang (Cameroon). Followi

M. T. Batchelor, C. M. Yung

We derive the exact critical couplings ($x^*, y_{\rm a}^*$), where $y_{\rm a}^*/x^* = \sqrt{1+\sqrt2} = 1.533\ldots\,$, for the polymer adsorption transition on the honeycomb lattice, along with the universal critical exponents, from the Bethe Ansatz solution of the O($n$) loop model at the special transition. Our result for the thermal scaling dimension, an

Dan Radu Grigore

A general discussion of equations with universal invariance for a scalar field is provided in the framework of Lagrangian theory of first-order systems.

Ali Mostafazadeh

A thorough analysis of the general features of $(p=2)$ parasupersymmetric quantum mechanics is presented. It is shown that for both Rubakov--Spiridonov and Beckers--Debergh formulations of $(p=2)$-parasupersymmetric quantum mechanics, the degeneracy structure of the energy spectrum can be derived using the defining parasuperalgebras. Thus the results of the

Simon Davis

The symmetries associated with the closed bosonic string partition function are examined so that the integration region in Teichmuller space can be determined. The conditions on the period matrix defining the fundamental region can be translated to relations on the parameters of the uniformizing Schottky group. The growth of the lower bound for the regulariz

George Lavrelashvili

We discuss the properties and interpretation of a discrete sequence of a static spherically symmetric solutions of the Yang-Mills-dilaton theory. This sequence is parametrized by the number $n$ of zeros of a component of the gauge field potential. It is demonstrated that solutions with odd $n$ posses all the properties of the sphaleron. It is shown that ther

Masaru Nagura

We calculate the B-model on the mirror pair of $X_{2N-2}(2,2,\cdots,2,1,1)$ , which is an $(N-2)$-dimensional Calabi-Yau manifold and has two marginal operators i.e. $h^{1,1}(X_{2N-2}(2,2,\cdots,2,1,1))=2$. In \cite{nagandjin} we have discussed about mirror symmetry on $X_N(1,1,\cdots,1)$ and its mirror pair. However, $X_N(1,1,\cdots,1)$ had only one moduli.

J. Rau

I critically examine the notion of ``irreversibility,'' and discuss in what sense it applies to the spontaneous creation of particles in external fields. The investigation reveals that particle creation in very strong fields can only be described by a non-Markovian transport theory.

Noriko Saitoh, Satoru Saito, Akinobu Shimizu

A difference analogue of the logistic equation, which preserves integrability, is derived from Hirota's bilinear difference equation. The integrability of the map is shown to result from the large symmetry associated with the Bäcklund transformation of the KP hierarchy. We introduce a scheme which interpolates between this map and the standard logistic m

Bin Chen, Han-Ying Guo, Hong-Bo Teng, Ke Wu

We reconstruct the Lagrangian of a left-right symmetric model with the gauge group $SU(2)_L\times SU(2)_R\times U(1)_Y \times π_4(SU(2)_L\times SU(2)_R\times U(1)_Y) $. The Higgs fields appear as gauge fields on discrete gauge group $π_4(SU(2)_L\times SU(2)_R\times U(1)_Y) $ and are assigned in a way complying with the principle that both the original gauge

Peter Arnold, Chengxing Zhai

We compute the free energy density for gauge theories, with fermions, at high temperature and zero chemical potential. Specifically, we analytically compute the free energy through $O(g^4)$, which requires the evaluation of three-loop diagrams. This computation extends our previous result for pure gauge QCD.

Nimai C. Mukhopadhyay, L. Zhang

The influence of the phi-meson on the nucleon properties in the chiral soliton model is discussed.

Carl E. Carlson, Nimai C. Mukhopadhyay

The existing inclusive electroproduction data base allow us a look at the issue of the relative behaviors of background and resonance excitations, a part of the Bloom-Gilman duality. These data lack accuracy at high Q^2, but establish PQCD scaling in the resonance region and even allow us a glimpse at the leading logarithmic corrections due to the gluon radi

P. Poulose, Saurabh D. Rindani

New CP-violating asymmetries of decay leptons in $e^+\,e^-\;\ra\;t\,\bar{t}$, arising from electric and weak dipole couplings of $t\,\bar{t}$ to $γ$ and $Z$, are examined in the case of unpolarized and longitudinally polarized electrons. The new asymmetries measured together with the old ones can help to determine independently the real and imaginary parts o

Bernd A. Kniehl

We present the two-loop QED and QCD corrections to the $f\bar fH$ Yukawa coupling that are induced by the exchange of a virtual photon or gluon, respectively, with a heavy-fermion loop inserted. As an application, we study the corresponding $Ø(α_s^2M_H^2/m_t^2)$ correction to the $H\to b\bar b$ decay rate.

P. Marenzoni, G. Martinelli, N. Stella, M. Testa

We present the results of two high-statistics studies of the gluon propagator in the Landau gauge, at $β=6.0$, on different lattice volumes. The dependence of the propagator on the momenta is well described by the expression $G(k^2) = \Big[ M^2+Z\cdot k^2(k^2/ Λ^2)^η)\Big]^{-1}$. We obtain a precise determination of $η=0.532(12)$, and verify that $M^2$ does

K. S. Viswanathan, R. Parthasarathy

We present calculations for the effective action of string world sheet in R3 and R4 utilizing its correspondence with the constrained Grassmannian sigma model. Minimal surfaces describe the dynamics of open strings while harmonic surfaces describe that of closed strings. The one-loop effective action for these are calculated with instanton and anti-instanton

David Hochberg

We consider the thermodynamics of a black hole coupled to thermal radiation in a spatially finite (spherical) region. Thermodynamic state functions are derived in the canonical ensemble, defined by elements of radius $r_o$ and boundary temperature $T(r_o)$. Using recent solutions of the semi-classical back reaction problem, we compute the $O(\hbar)$ correcti

Toshiharu Kawai

A black hole solution in a teleparallel theory of (2+1)-dimensional gravity, given in a previous paper, is examined. This solution is also a solution of the three-dimensional vacuum Einstein equation with a vanishing cosmological constant. Remarkable is the fact that this solution gives a black hole in a \lq \lq flat-land" in the Einstein theory and a Ne

Jun Hu, A. H. MacDonald

We report on a study of the thermodynamics of the Ginzburg-Landau model for two-dimensional type-II superconductors near the transition from the normal state to the Abrikosov-lattice state. We couch our analysis in terms of the participation-ratio entropy, $s(P)$, which expresses the volume in order-parameter-space with a given participation-ratio for the lo

J. Jaklic, P. Prelovsek

Finite-temperature spin dynamics in planar t-J model is studied using the method based on the Lanczos diagonalization of small systems. Dynamical spin structure factor at moderate dopings shows the coexistence of free-fermion-like and spin-fluctuation timescales. At T<J, the low-frequency and static susceptibility show pronounced T dependence, supporting a s

Jens O. Andersen, Tor Haugset

We consider Dirac fermions moving in a plane with a static homogeneous magnetic field orthogonal to the plane. We calculate the effective action at finite temperature and density. The magnetization is derived and it is shown that the fermion gas exhibits de Haas-van Alphen oscillations at small temperatures and weak magnetic fields. We also comment upon earl

N. Dupuis

The properties of a quasi-one-dimensional (quasi-1D) superconductor with {\it an open Fermi surface} are expected to be unusual in a magnetic field. On the one hand, the quasi-1D structure of the Fermi surface strongly favors the formation of a non-uniform state (Larkin-Ovchinnikov-Fulde-Ferrell (LOFF) state) in the presence of a magnetic field acting on the

Daniel Karp, Yves Schabes, Martin Zaidel, Dania Egedi

This paper presents a morphological lexicon for English that handles more than 317000 inflected forms derived from over 90000 stems. The lexicon is available in two formats. The first can be used by an implementation of a two-level processor for morphological analysis. The second, derived from the first one for efficiency reasons, consists of a disk-based da

Dania Egedi, Martha Palmer, Hyun S. Park, Aravind K. Joshi

It is often argued that accurate machine translation requires reference to contextual knowledge for the correct treatment of linguistic phenomena such as dropped arguments and accurate lexical selection. One of the historical arguments in favor of the interlingua approach has been that, since it revolves around a deep semantic representation, it is better ab

Takahiro Wakao

Reference resolution is one of the important tasks in natural language processing. In this paper, the author first determines the referents and their locations of &#34;dousha&#34;, literally meaning &#34;the same company&#34;, which appear in Japanese newspaper articles. Secondly, three heuristic methods, two of which use semantic information in text such as

Kumiko TANAKA, Kyoji UMEMURA

When using a third language to construct a bilingual dictionary, it is necessary to discriminate equivalencies from inappropriate words derived as a result of ambiguity in the third language. We propose a method to treat this by utilizing the structures of dictionaries to measure the nearness of the meanings of words. The resulting dictionary is a word-to-wo

Susanne Schacht, Udo Hahn, Norbert Broeker

The behavioral specification of an object-oriented grammar model is considered. The model is based on full lexicalization, head-orientation via valency constraints and dependency relations, inheritance as a means for non-redundant lexicon specification, and concurrency of computation. The computation model relies upon the actor paradigm, with concurrency ent

Helmut Schmid

Text corpora which are tagged with part-of-speech information are useful in many areas of linguistic research. In this paper, a new part-of-speech tagging method based on neural networks (Net- Tagger) is presented and its performance is compared to that of a HMM-tagger and a trigram-based tagger. It is shown that the Net- Tagger performs as well as the trigr

Norbert Broeker, Udo Hahn, Susanne Schacht

A grammar model for concurrent, object-oriented natural language parsing is introduced. Complete lexical distribution of grammatical knowledge is achieved building upon the head-oriented notions of valency and dependency, while inheritance mechanisms are used to capture lexical generalizations. The underlying concurrent computation model relies upon the acto

B. J. Boyle, T. Shanks, I. Georgantopoulos, G. C. Stewart

We report on a new estimate of the QSO X-ray luminosity function and its evolution with redshift based on a sample of 107 QSOs detected at faint X-ray fluxes, $S{\rm(0.5-2\,keV)}>4\times10^{-15}\,$\ergcms , with the {\it ROSAT} X-ray satellite. For $q_0=0.5$, the X-ray evolution of QSOs in this sample is consistent with strong luminosity evolution, $L_{\rm X

B. J. Boyle, R. G. Mcmahon, B. J. Wilkes, M. Elvis

We report on the first results obtained from a new optical identification programme of 123 faint X-ray sources with $S$(0.5--2$\,{\rm keV)}>2\times 10^{-14}\,$erg$\,$s$^{-1}\,$cm$^{-2}\,$ serendipitously detected in {\it ROSAT} PSPC pointed observations. We have spectroscopically identified the optical counterparts to more than 100 sources in this survey. Al

Matthias Bartelmann

It is shown in this paper that deviations of galaxy cluster lenses from spherical symmetry can render mass estimates for galaxy clusters based on the formation of large arcs systematically to high. Numerical models show that the mass needed for producing large arcs in clusters can be notably smaller than expected from simple spherically symmetric lens models

D. L. King, G. Vladilo, K. Lipman, K. S. de Boer

We present spectroscopic observations of supernova 1994D in NGC 4526, an S0$_3$ galaxy in the Virgo cluster 15 Mpc distant. The datasets consist of the interstellar Ca\II\ and Na\I\ lines towards the supernova at high spectral resolution (FWHM 6 \kms), \halpha\ and [N\,II] observations at lower resolution (FWHM 33 \kms) of the nucleus of NGC 4526 and the sup

Keith Lipman, Max Pettini

We present observations of Ti~II~$λ3384$ absorption towards 15 distant stars in the Galactic halo and the Magellanic Clouds. These new data extend existing surveys of the distribution of Ti$^+$ to larger distances from the plane of the Galaxy than sampled previously, allowing the scale height of titanium to be determined for the first time. We find $h_{Ti^+}

G. Domokos, S. Kovesi-Domokos

We investigate the resonant interaction of neutrinos in matter in the presence of mixing. At energies near the W resonance, oscillations are absent; the survival probability of electron antineutrinos is suppressed due to the presence of open inelastic channels.

Valeri V. Dvoeglazov

It is shown that the massless $j=1$ Weinberg-Tucker-Hammer equations reduce to the Maxwell&#39;s equations for electromagnetic field under the definite choice of field functions and initial and boundary conditions. Thus, the former appear to be of use in a description of some physical processes for which that could be necessitated or be convenient. The possi

R. P. Malik

A $q$-deformed free spinning relativistic particle is discussed in the framework of the Lagrangian formalism. Three equivalent Lagrangians are obtained for this system which are endowed with $q$-deformed local (super)gauge symmetries and reparametrization invariance. It is demonstrated that these symmetries are on-shell equivalent only for $ q = \pm1 $ under

Pankaj Agrawal, David Bowser-Chao, Kingman Cheung

We revisit the exclusive signature $e^\pm (μ^\pm) + b\bar b$ in the associated production of the intermediate mass Higgs boson with a $W$ boson. We show that it is feasible to use this signature to identify the Higgs boson in the lower intermediate mass region ($90$ to $130$ GeV) at the LHC with reasonable acceptance cuts by assuming effective bottom-jet ide

J. N Bahcall, P. I. Krastev, C. N. Leung

We study the proposed solution of the solar neutrino problem which requires a flavor nondiagonal coupling of neutrinos to gravity. We adopt a phenomenological point of view and investigate the consequences of the hypothesis that the neutrino weak interaction eigenstates are linear combinations of the gravitational eigenstates which have slightly different co

Carl E. Carlson, Nimai C. Mukhopadhyay

We study log corrections to inelastic scattering at high Bjorken x for Q^2 from 1 to 21 GeV^2. At issue is the presence of log corrections, which can be absent if high x scattering has damped gluon radiation. We find logarithmic correction of the scaling curve extrapolated to low Q^2 improves the duality between it and the resonance plus background data in t

D. S. Shaw, R. R. Volkas

In recent years a new potential symmetry of fundamental particle physics has been investigated --- discrete quark-lepton symmetry. When this symmetry is implemented, however, it often leads to either of the unrealistic predictions $m_{u}=m_{e}$ or $m_{d}=m_{e}$. This paper considers two possible ways models based on $m_{d}=m_{e}$ can be made realistic.

L. Stella, G. L. Israel, S. Mereghetti, D. Ricci

This paper reviews some of the recent observational results on stellar mass black hole candidates. Over the last decade, much of the progress in this field has been achieved through the study of transient X--ray binary sources which shine only sporadically in the X--ray sky and undergo much larger luminosity variations then most persistent sources. There are

M. Horibe, K. Shigemoto

We have examined solutions of tetrahedron equations from the elliptic free fermion model by using Korepanov mechanism based on tetrahedral Zamolodchikov algebras. As a byproduct, we have found a new integrable 2-dim. lattice model. We have also studied the relation between tetrahedral Zamolodchikov algebras and tetrahedron equations.

Changhyun Ahn

We discuss the nonlinear extension of $N=2$ superconformal algebra by generalizing Sugawara construction and coset construction built from $N=2$ currents based on Kazama-Suzuki $N=2$ coset model $\frac{SU(3)}{SU(2) \times U(1)}$ in $N=2$ superspace. For the generic unitary minimal series $c = 6(1-\frac{3}{k+3})$ where $k$ is the level of $SU(3)$ supersymmetr

F. Ardalan, A. M. Ghezelbash

We consider the standard vector and chiral gauged WZNW models by their gauged maximal null subgroups and show that they can be mapped to each other by a special transformation. We give an explicit expression for the map in the case of the classical Lie groups $ A_N $, $ B_N $, $ C_N $, $ D_N $, and note its connection with the duality map for the Riemmanian

Chi-Keung Chow

In the heavy quark limit, hadrons appear as eigenstates of the light degrees of freedom under the static color field of the heavy quark. In this formalism, the weak form factors appear naturally as the overlaps of the initial and final wavefunctions of the light degrees of freedom, and the Bjorken and Voloshin sum rules are statements of conservation of prob

C. Q. Geng, S. K. Lee

The T violating transverse muon polarizations in $K^+\to π^0μ^+ν$ and $K^+\to μ^+νγ$ decays due to tensor interactions are studied. The magnitudes of these polarizations over the allowed phase space are presented.

Alexandre Dolgov, Katherine Freese

A semiclassical calculation of particle production by a scalar field in a potential is performed. We focus on the particular case of production of fermions by a Nambu-Goldstone boson $θ$. We have derived a (non)local equation of motion for the $θ$-field with the backreaction of the produced particles taken into account. The equation is solved in some special

S. Kalyana Rama, Siddhartha Sen

We present a scenario in $1 + 1$ and $3 + 1$ dimensional space time which is paradoxical in the presence of a time machine. We show that the paradox cannot be resolved and the scenario has {\em no} consistent classical solution. Since the system is macroscopic, quantisation is unlikely to resolve the paradox. Moreover, in the absence of a consistent classica

T. P. Cheng, Ling-Fong Li

A simple calculation in the framework of the chiral quark theory of Manohar and Georgi yields results that can account for many of the &#39;&#39;failures&#39;&#39; of the naive quark model: significant strange quark content in the nucleon as indicated by the value of $σ_{πN},$ the $\overline{u}$-$\overline{d} $ asymmetry in the nucleon as measured by the dev

Gerrit Rentier

We present an analysis of Dutch cross serial dependencies in Head-driven Phrase Structure Grammar. Arguably, our analysis differs from other analyses in that we do not refer to `additional&#39; mechanisms (e.g., sequence union, head wrapping): just standard structure sharing, an immediate dominance schema and a linear precedence rule.

M. Albert

The reaction $^{12}C(ν_μ,μ^-) X$ has been measured near threshold using a $π^+$ decay-in-flight $ν_μ$ beam from the Los Alamos Meson Physics Facility and a massive liquid scintillator neutrino detector (LSND). In the energy region $123.7 < E_ν< 280$ MeV, the measured spectral shape is consistent with that expected from the Fermi Gas Model. However, the measu

Jean Avan, Antal Jevicki

We describe the general framework for constructing collective--theory Hamiltonians whose hermicity requirements imply a Kac--Moody algebra of constraints on the associated Jacobian. We give explicit examples for the algebras $sl(2)_k$ and $sl(3)_k$. The reduction to $W_n$--constraints, relevant to $n$-matrix models, is described for the Jacobians.

C. M. Hull, P. K. Townsend

The effective action for type II string theory compactified on a six torus is $N=8$ supergravity, which is known to have an $E_{7}$ duality symmetry. We show that this is broken by quantum effects to a discrete subgroup, $E_7(\Z)$, which contains both the T-duality group $SO(6,6;\Z)$ and the S-duality group $SL(2;\Z)$. We present evidence for the conjecture

Ivan K. Kostov

We study a $U(N)$-invariant vector+matrix chain with the color structure of a lattice gauge theory with quarks and interpret it as a theory of open andclosed strings with target space $\Z$. The string field theory is constructed as a quasiclassical expansion for the Wilson loops and lines in this model. In a particular parametrization this is a theory of two

R. Chakrabarti, R. Jagannathan

A quantum algebra $U_{p,q}(ζ,H,X_\pm )$ associated with a nonstandard $R$-matrix with two deformation parameters$(p,q)$ is studied and, in particular, its universal ${\cal R}$-matrix is derived using Reshetikhin&#39;s method. Explicit construction of the $(p,q)$-dependent nonstandard $R$-matrix is obtained through a coloured generalized boson realization of

Jean-Pierre Demailly

The notes start with an elementary introduction to a few important analytic techniques of algebraic geometry: closed positive currents, $L^2$ estimates for the $\dbar$-operator on positive vector bundles, Nadel&#39;s vanishing theorem for multiplier ideal sheaves (a generalization of the well-known Kawamata-Viehweg vanishing theorem). Applications to adjoint

David Elworthy

In part of speech tagging by Hidden Markov Model, a statistical model is used to assign grammatical categories to words in a text. Early work in the field relied on a corpus which had been tagged by a human annotator to train the model. More recently, Cutting {\it et al.} (1992) suggest that training can be achieved with a minimal lexicon and a limited amoun

A. Zagoskin, A. Kadigrobov, R. Shekhter, M. Jonson

An arrangement of mesoscopic experiments is considered when the conductance of a mesoscopic normal metal sample is governed not only by the magnetic flux threading the sample but by the supercurrent inside the superconductor coupled to the normal metal sample as well. The conductance of the system is shown to be associated with the SNS Josephson current $j_J

Julyan H. E. Cartwright, Mario Feingold, Oreste Piro

Global aspects of the motion of passive scalars in time-dependent incompressible fluid flows are well described by volume-preserving (Liouvillian) three-dimensional maps. In this paper the possible invariant structures in Liouvillian maps and the two most interesting nearly-integrable cases are investigated. In addition, the fundamental role of invariant lin

F. M. L. Almeida, J. H. Lopes, J. A. Martins Simões, P. P. Queiroz Filho

The production and decay of exotic leptons are discussed in the context of the vector singlet, vector doublet and fer\-mion mirror-fer\-mion models, at c.m. energies $\sqrt{s}=190GeV$ (LEP II) and $\sqrt{s}=500GeV$ (NLC). The model dependence of total cross sections and kinematic distributions at these energies is shown to be weak for these three extended mo

Shao Liu, Myron Bander

Calculations of transverse polarization of leptons in the decay $W\rightarrow lν$ with polarized $W$&#39;s are presented. Planned accelerators will produce enough $W$&#39;s for observation of the Standard Model contributions to this polarization. One loop corrections to the polarization are given; these are too small to be seen at presently available $W$ sou

L. Zamick, D. C. Zheng, M. Fayache

We examine several ``landmarks&#39;&#39; for the effects of the tensor interaction on the properties of light nuclei. These were usually discussed in the context of small-space shell-model calculations. We show, using $G$ matrices derived from a realistic nucleon-nucleon potential, that when the model space is small (e.g., $0\hbarω$), these effects are overe

M. Jetter, H. W. Fearing

The role of the relativistic amplitudes for a number of ${\cal O}(k)$ processes usually neglected in potential model calculations of NN--bremsstrahlung is investigated. In particular, we consider the $Δ$--excitation pole contributions related to the one--pion and one--rho exchange and in addition include the exchange contributions induced by the radiative $ω

C. R. Chinn

A relativistic finite nucleus calculation using a Dirac optical potential is used to investigate the importance of final state interactions [FSI] at large momentum transfers in inclusive quasielastic electronuclear reactions. The optical potential is derived from first-order multiple scattering theory and then is used to calculate the FSI in a nonspectral Gr

K. Burzynski, J. Dobaczewski

We discuss the ability of the generator coordinate method (GCM) to select collective states in microscopic calculations. The model studied is a single-$j$ shell with hamiltonian containing the quadrupole-quadrupole interaction. Quadrupole collective excitations are constructed by means of the quadrupole single-particle operator. Lowest collective bands for $

Pavel Etingof, Alexander Kirillov

This paper is a continuation of our papers \cite{EK1, EK2}. In \cite{EK2} we showed that for the root system $A_{n-1}$ one can obtain Macdonald&#39;s polynomials as weighted traces of intertwining operators between certain finite-dimensional representations of $U_q(sl_n)$. The main goal of the present paper is to use this construction to give a representatio

W. G. Unruh

Quantum measurement theory has fallen under the resticting influence of the attempt to explain the fundamental axioms of quantum theory in terms of the theory itself. This has not only led to confusion but has also restricted our attention to a limited class of measurements. This paper outlines some of the novel types of measurements which fall outside the u

J. C. Brunelli, Ashok Das

We show that the KdV and the NLS equations are tri-Hamiltonian systems. We obtain the third Hamiltonian structure for these systems and prove Jacobi identity through the method of prolongation. The compatibility of the Hamiltonian structures is verified directly through prolongation as well as through the shifting of the variables. We comment on the properti

Walter Troost, Antoine Van Proeyen

We review the Lagrangian Batalin--Vilkovisky method for gauge theories. This includes gauge fixing, quantisation and regularisation. We emphasize the role of cohomology of the antibracket operation. Our main example is $d=2$ gravity, for which we also discuss the solutions for the cohomology in the space of local integrals. This leads to the most general for