arXiv papers from October 1994

David G. Robertson

Light-cone quantization of (3+1)-dimensional electrodynamics is discussed, using discretization as an infrared regulator and paying careful attention to the interplay between gauge choice and boundary conditions. In the zero longitudinal momentum sector of the theory a general gauge fixing is performed and the corresponding relations that determine the const

Narcisse Randrianantoanina

Let $E$ be a separable Banach space and $\Omega$ be a compact Hausdorff space. It is shown that the space $C(\Omega,E)$ has property (V) if and only if $E$ does. Similar result is also given for Bochner spaces $L^p(\mu,E)$ if $1<p<\infty$ and $\mu$ is a finite Borel measure on $\Omega$.

Narcisse Randrianantoanina

Let $X$ be a Banach space and $(f_n)_n$ be a bounded sequence in $L^1(X)$. We prove a complemented version of the celebrated Talagrand's dichotomy i.e we show that if $(e_n)_n$ denotes the unit vector basis of $c_0$, there exists a sequence $g_n \in \text{conv}(f_n,f_{n+1},\dots)$ such that for almost every $\omega$, either the sequence $(g_n(\omega) \otimes

Stephen J. Dilworth, Maria Girardi

For an arbitrary infinite-dimensional Banach space $\X$, we construct examples of strongly-measurable $\X$-valued Pettis integrable functions whose indefinite Pettis integrals are nowhere weakly differentiable; thus, for these functions the Lebesgue Differentiation Theorem fails rather spectacularly. We also relate the degree of nondifferentiability of the i

L. H. Ford

Gravitons in a squeezed vacuum state, the natural result of quantum creation in the early universe or by black holes, will introduce metric fluctuations. These metric fluctuations will introduce fluctuations of the lightcone. It is shown that when the various two-point functions of a quantized field are averaged over the metric fluctuations, the lightcone si

Bernd Sturmfels

We study algebras k[x_1,...,x_n]/I which admit a grading by a subsemigroup of N^d such that every graded component is a one-dimensional k-vector space. V.I.~Arnold and coworkers proved that for d = 1 and n <= 3 there are only finitely many isomorphism types of such A-graded algebras, and in these cases I is an initial ideal (in the sense of Groebner bases) o

Maria J. Herrero, Ester Ruiz Morales

We study the complete non-decoupling effects of the standard model Higgs boson to one loop. Using effective field theory methods, we integrate out the Higgs boson and represent its non-decoupling effects by a set of gauge invariant effective operators of the electroweak chiral Lagrangian. In a previous work, we analyzed the non-decoupling effects in the two

Jonathan M. Evans

Division algebras are used to explain the existence and symmetries of various sets of auxiliary fields for super Yang-Mills in dimensions $d=3,4,6,10$. (Contribution to G\"ursey Memorial Conference I: Strings and Symmetries)

T. H. Hansson, Rodanthy Tzani

Using a loop formulation approach of QCD$_2$, we study the potential between two heavy quarks in the presence of adjoint scalar fields, and demonstrate how 't Hooft's planar rule is manifested in this formulation. Based on some physical assumptions, we argue that large adjoint loops ``confined'' inside an external fundamental one give a Casimir type contribu

G. E. Brown, M. Buballa, Zi Bang Li, J. Wambach

Three recent experiments, which looked at pionic effects in nuclei have concluded that there are no excess pions. This puts into serious question the conventional meson-exchange picture of the nucleon-nucleon interaction. Based on arguments of partial restoration of chiral symmetry with density we propose a resolution to this problem.

Igor V. Kanatchikov

We discuss a field theoretical extension of the basic structures of classical analytical mechanics within the framework of the De Donder--Weyl (DW) covariant Hamiltonian formulation. The analogue of the symplectic form is argued to be the {\em polysymplectic} form of degree $(n+1)$, where $n$ is the dimension of space-time, which defines a map between multiv

P. Bedaque

I argue that, within the Closed-Time-Path formalism, pinch singularities do not appear in truly out of equilibrium situations.

Linda Bauman Peto

A COMPARISON OF TWO SMOOTHING METHODS FOR WORD BIGRAM MODELS Linda Bauman Peto Department of Computer Science University of Toronto Abstract Word bigram models estimated from text corpora require smoothing methods to estimate the probabilities of unseen bigrams. The deleted estimation method uses the formula: Pr(i|j) = lambda f_i + (1-lambda)f_i|j, where f_i

Arkadii G. Aronov, Alexander D. Mirlin

We present a detailed analysis of the behavior of two--level correlation function $R(s)$ in the disordered sample. We show that in the vicinity of the Anderson transition as well as in $2d$, the variance of the number of levels in an energy band of a width $E$ has a linear behavior as a function of $E$. This is related with an ``anomalous'' contribution to t

D. C. Zheng, B. R. Barrett, J. P. Vary, H. Müther

The Lee-Suzuki iteration method is used to include the folded diagrams in the calculation of the two-body effective interaction $v^{(2)}_{\rm eff}$ between two nucleons in a no-core model space. This effective interaction still depends upon the choice of single-particle basis utilized in the shell-model calculation. Using a harmonic-oscillator single-particl

Z. B. Li, L. Schuelke, B. Zheng

Based on the scaling relation for the dynamics at the early time, a new method is proposed to measure both the static and dynamic critical exponents. The method is applied to the two dimensional Ising model. The results are in good agreement with the existing results. Since the measurement is carried out in the initial stage of the relaxation process startin

E. Alvarez, L. Alvarez-Gaume, Y. Lozano

In these lectures a general introduction to T-duality is given. In the abelian case the approaches of Buscher, and Ro\u{c}ek and Verlinde are reviewed. Buscher's prescription for the dilaton transformation is recovered from a careful definition of the gauge integration measure. It is also shown how duality can be understood as a quite simple canonical transf

Martin Schoen

A higher-order analysis of the evolution of cosmological perturbations in a Friedman universe is given by using the PMF method. The essence of the PMF approach is to choose a gauge where all fluctuations of the density, the pressure, and the four-velocity vanish. In that gauge, even in higher orders, the perturbation field equations simplify considerably; th

Robert Guralnick, David Jaffe, Wayne Raskind, Roger Wiegand

For a homomorphism f: A --> B of commutative rings, let D(A,B) denote Ker[Pic(A) --> Pic(B)]. Let k be a field and assume that A is a f.g. k-algebra. We prove a number of finiteness results for D(A,B). Here are four of them. 1: Suppose B is a f.g. and faithfully flat A-algebra which is geometrically integral over k. If k is perfect, we find that D(A,B) is f.

Michael H. Seymour

We discuss two ways in which parton shower algorithms can be supplemented by matrix-element corrections to ensure the correct hard limit: by using complementary phase-space regions, or by modifying the shower itself. In the former case, existing algorithms are self-consistent only if the total correction is small. In the latter case, existing algorithms are

Chung-Yi Wu

By assuming that there is no significant intrinsic polarization of the gluon, we have computed the polarized quark contributions to the proton's spin under SU(3) flavor symmetry breaking for the polarized sea and have performed a global leading-order QCD fit to obtain the spin-dependent quark distributions, which could be used as input for analyzing lepton-h

Dimitra Karabali, V. P. Nair

We discuss many-body states and the algebra of creation and annihilation operators for particles obeying exclusion statistics.

J. Giesen

A description of elementary particles should be based on irreducible representations of the Poincar\'e group. In the theory of massive representations of the full Poincar\'e group there are essentially four different cases. One of them corresponds to the ordinary Dirac theory. The extension of Dirac theory to the remaining three cases makes it possible to de

Pablo M. Llatas, Shibaji Roy

It has been argued by Ishikawa and Kato that by making use of a specific bosonization, $c_M=1$ string theory can be regarded as a constrained topological sigma model. We generalize their construction for any $(p,q)$ minimal model coupled to two dimensional (2d) gravity and show that the energy--momentum tensor and the topological charge of a constrained topo

L. Perivolaropoulos

This is a pedagogical introduction to the basics of the cosmic string theory and also a review of the recent progress made with respect to the macrophysical predictions of the theory. Topics covered include, string formation and evolution, large scale structure formation, generation of peculiar velocity flows, cosmic microwave background (CMB) fluctuations,

Dao Vong Duc

We consider a version of generalised $q$-oscillators and some of their applications. The generalisation includes also "quons" of infinite statistics and deformed oscillators of parastatistics. The statistical distributions for different $q$-oscillators are derived for their corresponding Fock space representations. The deformed Virasoro algebra and SU(2) alg

F. Ardalan, K. Kaviani

We consider the non-commutative generalization of the chiral perturbation theory. The resultant coupling constants are severely restricted by the model and in good agreement with the data. When applied to the Skyrme model, our scheme reproduces the non-Skyrme term with the right coefficient. We comment on a similar treatment of the linear $\sigma $-model.

Takemi HAYASHI, Yoshio Koide, Masahisa Matsuda, Morimitsu Tanimoto

We study the electric dipole moments(EDM) of the neutron and the electron in the two-Higgs-doublet model, in the case that $CP$ symmetry is violated maximally in the neutral Higgs sector. We take account of the Weinberg's operator $O_{3g}=GG\t G$ as well as the operator $O_{qg}=\bar q\sigma\tilde Gq$ for the neutron, and the Barr-Zee diagrams for the electro

Apostolos Pilaftsis

Minimal extensions of the Standard Model that are motivated by grand unified theories or superstring models with an E_6 symmetry can naturally predict heavy neutrinos of Dirac or Majorana nature. Such heavy neutral leptons violate the de- coupling theorem at the one-loop electroweak order and hence offer a unique chance for possible lepton-flavour decays of

Joonhyun Yeo

The reformulation of the mode-coupling theory (MCT) of the liquid-glass transition which incorporates the element of metastability is applied to the hard-sphere system. It is shown that the glass transition in this system is not a sharp one at the special value of the density or the packing fraction, which is in contrast to the prediction by the conventional

R. F. Bishop, R. G. Hale, Y. Xian

We apply the microscopic coupled-cluster method (CCM) to the spin-$1\over2$ $XXZ$ models on both the one-dimensional chain and the two-dimensional square lattice. Based on a systematic approximation scheme of the CCM developed by us previously, we carry out high-order {\it ab initio} calculations using computer-algebraic techniques. The ground-state properti

J. Rotvig, A. P. Jauho, H. Smith

We present a time-domain analysis of carrier dynamics in a semiconductor superlattice with two minibands. Integration of the density-matrix equations of motion reveals a number of new features: (i) for certain values of the applied static electric field strong interband transitions occur; (ii) in static fields the complex time-dependence of the density-matri

Gregor Hackenbroich, Felix von Oppen

We present a detailed study of quantum transport in large antidot arrays whose classical dynamics is chaotic. We calculate the longitudinal and Hall conduc- tivities semiclassically starting from the Kubo formula. The leading contribu- tion reproduces the classical conductivity. In addition, we find oscillatory quantum corrections to the classical conductivi

Levan R. Surguladze

The results of perturbative QCD evaluation of the ~m_f^2/M_Z^2 contributions to the decay rates in Z--->bb and Z--->hadrons for the quark masses m_f << M_Z are presented. The recent results due to the combination of renormalization group constraints and the results of several other calculations are independently confirmed by the direct computation. Some exis

N. Armesto, M. A. Braun

To calculate the intercept of the multigluon system in a symmetric spatial configuration a variational method is developed based on a complete system of one-gluon functions. The method is applied to two- and three- gluon cases to compare with the known results. The convergence turns out rather slow. Ways to improve results are discussed.

Mehran Kardar

Contents: A. Introduction B. High Temperature Expansions for the Ising Model C. Characteristic Functions and Cumulants D. The One Dimensional Chain E. Directed Paths and the Transfer Matrix F. Moments of the Correlation Function G. The Probability Distribution in Two Dimensions H. Higher Dimensions I. Random Signs J. Other Realizations of DPRM K. Quantum Int

J. F. L. Simmons, J. P. Willis, A. Newsam

Much interest has been generated recently by the ongoing MACHO, EROS and OGLE projects to identify gravitationally lensed stars from the Large Magellanic Cloud and Galactic bulge, and the positive identification of several events (Alcock et al, (1993), Aubourg et al, (1993) and Udalski et al, (1993)). The rate at which such events are found should provide co

Hyung Mok Lee, Jeremy Goodman

We study the rate of escape of stars (``evaporation&#39;&#39;) from tidally-limited postcollapse globular clusters having a power-law distribution of stellar masses. We use a multi-mass Fokker-Planck code and assume a steady tidal field. Stellar-dynamical processes cause the inner parts of the cluster to expand, which in turn causes stars to overflow the tid

Oleg Viro

For a nonsingular real algebraic curve in the 3-dimensional projective space and sphere a new numeric characteristic is introduced. It takes integer values, is invariant under rigid isotopy, multiplied by -1 under mirror reflection. In a sense it is a Vassiliev invariant of degree 1 and a counter-part of a link diagram writhe.

Thomas M. Gould, Stephen D. H. Hsu

We extend our previous results on the evolution of quantum fermi fields in Minkowski gauge field backgrounds to the case of spontaneously broken gauge theories. We obtain a selection rule which relates the amount of fermion number violation to the change in Higgs winding number of the configuration. This selection rule is applicable to any classical solution

Thomas M. Gould, Stephen D. H. Hsu

We consider the evolution of quantum fermi fields in Minkowski gauge field backgrounds. Our motivation is the study of anomalous fermion number violating processes. We derive selection rules for fermion scattering amplitudes which relate the violation of fermionic charge to the change in winding between early and late times of the vacuum part of the gauge fi

E. Bergshoeff, R. Kallosh, T. Ortín

We study the interplay between T-duality, compactification and supersymmetry. We prove that when the original configuration has unbroken space-time supersymmetries, the dual configuration also does if a special condition is met: the Killing spinors of the original configuration have to be independent on the coordinate which corresponds to the isometry direct

G. Kramer, W. F. Palmer, H. Simma

We calculate direct CP-violating rate asymmetries in charged $B\to PP$ and $B\to VP$ decays arising from the interference of amplitudes with different strong and CKM phases. The perturbative strong phases develop at order $\alpha_s$ from absorptive parts of one-loop matrix elements of the next-to-leading logarithm corrected effective Hamiltonian. CPT constra

G. Gallavotti

Various kinematical quantities associated with the statistical properties of dynamical systems are examined: statistics of the motion, dynamical bases and Lyapunov exponents. Markov partitons for chaotic systems, without any attempt at describing ``optimal results''. The Ruelle principle is illustrated via its relation with the theory of gases. An example of

G. Gallavotti, E. G. D. Cohen

Ruelle's principle for turbulence leading to what is usually called the Sinai-Ruelle-Bowen distribution (SRB) is applied to the statistical mechanics of many particle systems in nonequilibrium stationary states. A specific prediction, obtained without the need to construct explicitly the SRB itself, is shown to be in agreement with a recent computer experime

M. G. Olsson, S. Veseli, K. Williams

We consider possible dynamical models for a light fermion confined by a potential field. With the Dirac equation only Lorentz scalar confinement yields normalizable wavefunctions, while with the ``no pair'' variant of the Dirac equation only Lorentz vector confinement has normal Regge behaviour. A systematic investigation of Regge properties and phenomenolog

S. Franz, H. Rieger

We present an analysis of the data on aging in the three-dimensional Edwards Anderson spin glass model with nearest neighbor interactions, which is well suited for the comparison with a recently developed dynamical mean field theory. We measure the parameter $x(q)$ describing the violation of the relation among correlation and response function implied by th

Karin Harbusch, Gen-ichiro Kikui, Anne Kilger

Natural language generation must work with insufficient input. Underspecifications can be caused by shortcomings of the component providing the input or by the preliminary state of incrementally given input. The paper aims to escape from such dead-end situations by making assumptions. We discuss global aspects of default handling. Two problem classes for def

G. Sardanashvily

When joined the unified gauge picture of fundamental interactions, the gravitation theory leads to geometry of a space-time which is far from simplicity of pseudo-Riemannian geometry of Einstein's General Relativity. This is geometry of the affine-metric composite dislocated manifolds. The goal is modification of the familiar equations of a gravitational fie

R. Nolthenius, A. A. Klypin, J. R. Primack

We present techniques for identifying and analyzing galaxy groups and show that they provide a powerful discriminator between cosmological models. We apply these to high-resolution PM N-body simulations of structure formation in CHDM (cold/hot/baryon fractions=.6/.3/.1, b=1.5 (COBE norm) and two CDM models; b=1.5 and b=1.0 (COBE norm). Groups are identified

E. S. C. Ching, P. T. Leung, W. M. Suen, K. Young

The late time behavior of waves propagating on a general curved spacetime is studied. The late time tail is not necessarily an inverse power of time. Our work extends, places in context, and provides understanding for the known results for the Schwarzschild spacetime. Analytic and numerical results are in excellent agreement.

S. Boettcher

In a recent letter, a simple method was proposed to generate solvable models that predict the critical properties of statistical systems in hyperspherical geometries. To that end, it was shown how to reduce a random walk in $D$ dimensions to an anisotropic one-dimensional random walk on concentric hyperspheres. Here, I construct such a random walk to model t

G. Sigl

We reexamine the constraints on mixing between electron and muon or tau neutrinos from shock-reheating and r-process nucleosynthesis in supernovae. To this end neutrino flavor evolution is described by nonlinear equations following from a quantum kinetic approach. This takes into account neutrino forward scattering off the neutrino background itself. In cont

Joao C A Barata, Florian Nill

Electrically as well as magnetically charged states are constructed in the 2+1-dimensional Euclidean Z_N-Higgs lattice gauge model, the former following ideas of Fredenhagen and Marcu and the latter using duality transformations on the algebra of observables. The existence of electrically and of magnetically charged particles is also established. With this w

Bruno Nachtergaele

We prove that for any finite set of generalized valence bond solid (GVBS) states of a quantum spin chain there exists a translation invariant finite-range Hamiltonian for which this set is the set of ground states. This result implies that there are GVBS models with arbitrary broken discrete symmetries that are described as combinations of lattice translatio

S. Colafrancesco, V. Antonuccio-Delogu, A. Del Popolo

We study the effect of the dynamical friction induced by the presence of substructure on the statistics of the collapse of density peaks. Applying the results of a former paper we show that within high density environments, like rich clusters of galaxies, the collapse of smaller peaks is strongly delayed until very late epochs. A bias of dynamical nature thu

Alexander Gorsky

We review recent results which clarify the role of the integrable many-body problems in the quantum field theory framework.They describe the dynamics of the topological degrees of freedom in the theories which are obtained by perturbing the topological ones by the proper Hamiltonians and sources. Interpretation of the many-body dynamics as a motion on the di

Minoru Hirayama, Takeshi Hamada, Jin Chen

The time-energy uncertainty relation of Anandan-Aharonov is generalized to a relation involving a set of quantum state vectors. This is achieved by obtaining an explicit formula for the distance between two finitely separated points in the Grassmann manifold.

L. H. Ford, Thomas A. Roman

Connections are uncovered between the averaged weak (AWEC) and averaged null (ANEC) energy conditions, and quantum inequality restrictions on negative energy for free massless scalar fields. In a two-dimensional compactified Minkowski universe, we derive a covariant quantum inequality-type bound on the difference of the expectation values of the energy densi

Matteo Marsili, Guido Caldarelli

The main result of this letter is that SOC naturally arises as a result of memory effects. We show that memory effects provide the mechanism for self organization. A general procedure to investigate this issue in models that display self organized critical behaviour is proposed and applied to some example. The simplest class of models exhibiting self organiz

H. Monien, A. W. Sandvik

The origin of the spin gap in the underdoped cuprate superconductors is still mysterious. Experimental evidence from neutron scattering and NMR experiments indicates that the spin gap might be present only in the bilayer compounds. A naive calculation for a two plane Heisenberg model locates the order-disorder transition only for very large exchange coupling

H. L. Lai, J. Botts, J. Huston, J. G. Morfin

The CTEQ program for the determination of parton distributions through a global QCD analysis of data for various hard scattering processes is fully described. A new set of distributions, CTEQ3, incorporating several new types of data is reported and compared to the two previous sets of CTEQ distributions. Comparison with current data is discussed in some det

Simon Davis

Symplectic modular invariance of the bosonic string partition function has been verified at genus 2 and 3 using the period matrix coordinatization of moduli space. A calculation of the transformation of the holomorphic part of the differential volume element shows that an extra phase arises together with the factor associated with a specific modular weight;

Ronnie Mainieri

Nanometer scale electronics present a challenge for the computer architect. These quantum devices have small gain and are difficult to interconnect. I have analyzed current device capabilities and explored two general design requirements for the design of computers: error correction and long range connections. These two principles follow when Turing machines

Domenico Giulini

We make some general remarks on long-ranged configurations in gauge or diffeomorphism invariant theories where the fields are allowed to assume some non vanishing values at spatial infinity. In this case the Gauss constraint only eliminates those gauge degrees of freedom which lie in the connected component of asymptotically trivial gauge transformations. Th

Matteo Campellone

Models of spin glasses are studied with a phase transition discontinuous in the Parisi order parameter. It is assumed that the leading order corrections to the thermodynamic limit of the high temperature free energy are due to the existence of a metastable saddle point in the replica formalism. An ansatz is made on the form of the metastable point and its co

Alec J. Schramm, Berndt Müller

We estimate the cross section for quasi-elastic double pion exchange in high energy proton-proton collisions. Total and elastic $\pi\pi$ cross sections are calculated in an equivalent pion approximation, with pion-baryon vertices taken from chiral perturbation theory.

C. R. Hagen, D. K. Park

The Aharonov-Bohm effect is analyzed for a spin-1/2 particle in the case that a $1/r$ potential is present. Scalar and vector couplings are each considered. It is found that the approach in which the flux tube is given a finite radius that is taken to zero only after a matching of boundary conditions does not give physically meaningful results. Specifically,

H. Feshbach, M. S. Hussein, A. K. Kerman

We incorporate time reversal symmetry breaking (TRSB) effects into the theory of compound nuclear reactions. We show that the only meaningful test of TRSB in the overlapping resonances regime is through the study of cross-section correlations. The effect is channel-dependent. In the isolated resonance regime, we employ $K$-matrix theory to show the impact of

Henry E. Kandrup

This paper summarises a number of new, potentially significant, results, obtained recently by the author and his collaborators, which impact on various issues related to the gravitational N-body problem, both Newtonianly and in the context of general relativity. Topics addressed include: (1) direct N-body simulations and their interpretation, with reference

A. Marini, C. P. Burgess

We illustrate how the reorganization of perturbation theory at finite temperature can be economically cast in terms of the Wilson-Polchinski renormalization methods. We take as an example the old saw of the induced thermal mass of a hot scalar field with a quartic coupling, which we compute to second order in the coupling constant. We show that the form of t

Glennys R. Farrar, Antonio Masiero

We investigate the possibility that gauginos are massless at tree level and that the U(1) R-invariance is broken spontaneously by Higgs vevs, like the chiral symmetry of quarks in the standard model, or else explicitly by dimension 2 or 3 SUSY-breaking terms in the low energy effective Lagrangian. Gluino and lightest neutralino masses then depend on only a f

Hong-Jian He, Yu-Ping Kuang, C. -P. Yuan

We examine the Lorentz non-invariance ambiguity in longitudinal weak-boson scatterings and the precise conditions for the validity of the Equivalence Theorem (ET). {\it Safe} Lorentz frames for applying the ET are defined, and the intrinsic connection between the longitudinal weak-boson scatterings and probing the symmetry breaking sector is analyzed. A univ

M. K. Banerjee, J. Milana

Baryon masses are calculated in chiral perturbation theory at the one--loop-${\cal O}(p^3)$ level in the chiral expansion and to leading order in the heavy baryon expansion. Ultraviolet divergences occur requiring the introduction of counter--terms. Despite this neccessity, no knowledge of the counter terms is required to determine the violations to the Gell

C. O. Lousto, N. Sánchez

The ultrarelativistic limit of the Kerr - Newman geometry is studied in detail. We find the gravitational shock wave background associated with this limit. We study the scattering of scalar fields in the gravitational shock wave geometries and compare this with the scattering by ultrarelativistic extended sources and with the scattering of fundamental string

T. Nakatsukasa, K. Matsuyanagi, S. Mizutori, W. Nazarewicz

RPA calculations, based on the cranked shell model, are performed for superdeformed \dy\ in which five excited bands have been found recently. We show that characteristic features of the observed dynamical moments of inertia are well accounted for by explicitly taking the octupole correlations into account. Importance of the interplay between rotation and oc

L. Salasnich, F. Sattin

We made a classical trajectory Monte Carlo (CTMC) calculation of state selective cross sections for processes between some light ions and excited helium. The results, useful for analysis of spectroscopic data of fusion devices, are in good agreement with theoretical predictions of scaling laws.

Pankaj Agrawal, David Bowser-Chao, Kingman Cheung, Duane Dicus

We examine the exclusive signature $pp \to WH \to \ell \nu\;b \bar b$ at the LHC. Although the backgrounds, principally arising from top production and $Wjj$, are quite severe, it is shown that judicious application of phase-space cuts and the use of $b$-tagging can in fact greatly enhance the detectability of this channel. (Presented at the Eighth Meeting o

A. Bashir

This talk gives an overview of the recent development in the study of non-perturbative fermion-boson vertex in quenched QED towards achieving that the fermion propagator satisfies the Ward-Takahashi identity, is multiplicatively renormalizable, agrees with perturbation theory for weak couplings and has a critical coupling for dynamical mass generation that i

F. Gliozzi

We review some universal features of the colour flux tube of gauge theories in the confining phase predicted by the infrared conformal limit of the underlying string theory. In particular we discuss shape effects in Wilson loops and rederive in a general way the logarithmic growth of the mean square width of the flux tube as a function of the interquark sepa

L. Palacios

We present a general argument for the construction of BRST charges of the `non-critical' $\W_{2,4}$, $\W_{2,5}$, $\W_{2,6}$, and $\W_{2,8}$ strings. This evidences the existence of BRST charges for a kind of soft-type algebras which can be constructed from two copies of quantum $\W_{2,s}$ algebras, (s=3,4,5,6,8).

Piotr T. Chruściel, Alan D. Rendall

We consider the question of strong cosmic censorship in spatially compact, spatially locally homogeneous vacuum models. We show in particular that strong cosmic censorship holds in Bianchi IX vacuum space--times with spherical spatial topology.

C. P. Martin, F. Ruiz Ruiz

We compute the beta function at one loop for Yang-Mills theory using as regulator the combination of higher covariant derivatives and Pauli-Villars determinants proposed by Faddeev and Slavnov. This regularization prescription has the appealing feature that it is manifestly gauge invariant and essentially four-dimensional. It happens however that the one-loo

D. V. Gal'tsov

Static axisymmetric Einstein-Maxwell-Dilaton and stationary axisymmetric Einstein-Maxwell-Dilaton-Axion (EMDA) theories in four space-time dimensions are shown to be integrable by means of the inverse scattering transform method. The proof is based on the coset-space representation of the 4-dim theory in a space-time admitting a Killing vector field. Hidden

M. Bianchi, F. Fucito, G. C. Rossi, M. Martellini

We show that the classical equations of motion of the low-energy effective field theory describing the massless modes of the heterotic (or type I) string admit two classes of supersymmetric self--dual backgrounds. The first class, which was already considered in the literature, consists of solutions with a (conformally) flat metric coupled to axionic instant

H. J. de Vega, A. L. Larsen, N. Sanchez

We compute the {\it exact} equation of state of circular strings in the (2+1) dimensional de Sitter (dS) and anti de Sitter (AdS) spacetimes, and analyze its properties for the different (oscillating, contracting and expanding) strings. The string equation of state has the perfect fluid form $P=(\gamma-1)E,$ with the pressure and energy expressed closely and

D. C. Cabra, K. D. Rothe

We obtain an explicit realization of all the primary fields of the Ising model in terms of a conformal field theory of constrained fermions. The four-point correlators of the energy, order and disorder operators are explicitly calculated.

V. Aldaya, J. Guerrero

Relativistic Quantum Mechanics suffers from structural problems which are traced back to the lack of a position operator $\hat{x}$, satisfying $[\hat{x},\hat{p}]=i\hbar\hat{1}$ with the ordinary momentum operator $\hat{p}$, in the basic symmetry group -- the Poincar\'e group. In this paper we provide a finite-dimensional extension of the Poincar\'e group con

P. S. Montague

Following on from a general observation in an earlier paper, we consider the continuous symmetries of a certain class of conformal field theories constructed from lattices and their reflection-twisted orbifolds. It is shown that the naive expectation that the only such (inner) symmetries are generated by the modes of the vertex operators corresponding to the

Xiaorong Huang

This paper presents \proverb\, a text planner for argumentative texts. \proverb\'s main feature is that it combines global hierarchical planning and unplanned organization of text with respect to local derivation relations in a complementary way. The former splits the task of presenting a particular proof into subtasks of presenting subproofs. The latter sim

M. Karbach, K. -H. Mütter, M. Schmidt

The static structure factors of the XXZ model in the presence of uniform field are determined from an exact computation of the groundstates at given total spin on rings with $N=4,6,\ldots,28$ sites. In contrast to the naive expectation a weak uniform field strengthens the antiferromagnetic order in the transverse structure factor for the isotropic case.

E. J. Chun

We show that the late-decaying particle scenario may be realized in the supersymmetric singlet majoron model with the majoron scale $10-200$ TeV. The smajoron decaying into two neutrinos is the late-decaying particle with the mass $0.1-1$ TeV and the life-time $2\times10^3-8\times10^4$ seconds. The lower limit of the majorino mass is $4-40$ TeV in order to a

Timothy Banks, D. J. Sullivan, M. C. Forbes, R. J. Dodd

The Vilnius Photometric system has been used with a CCD system only once before this study. Preliminary crowded field reductions of Vilnius CCD observations of the star clusters NGC~2004 and NGC~4755 (the $\kappa $ Crucis cluster) are presented, demonstrating the feasibility of using the filter set in this manner.

K. S. Gupta, A. Stern

A class of two dimensional conformal field theories is known to correspond to three dimensional Chern-Simons theory. Here we claim that there is an analogous class of four dimensional field theories corresponding to five dimensional Chern-Simons theory. The four dimensional theories give a coupling between a scalar field and an external divergenceless vector

David A. Lowe, Andrew Strominger

Orbifold techniques are used to study bosonic, type II and heterotic strings in Rindler space at integer multiples N of the Rindler temperature, and near a black hole horizon at integer multiples of the Hawking temperature, extending earlier results of Dabholkar. It is argued that a Hagedorn transition occurs nears the horizon for all N>1.

Wolfhard Janke

In the past few years considerable progress has been made in Monte Carlo simulations of first-order phase transitions and in the analysis of the resulting finite-size data. In this paper special emphasis will be placed on multicanonical simulations using multigrid update techniques, on numerical estimates of interface tensions, and on accurate methods for de

S. Kolitch, B. Hall

The conformal equivalence of some cosmological models in Brans-Dicke theory to general relativistic cosmologies with a scalar field is discussed. In the case of radiation-dominated universes, it is shown that the presence of the scalar field has a negligible impact upon the evolution of the models in the Einstein frame. It is also shown that power-law inflat

L. Salasnich, F. Sattin

We made a classical trajectory Monte Carlo (CTMC) calculation of state selective cross sections for processes between some light ions and excited helium. The results, useful for analysis of spectroscopic data of fusion devices, are in good agreement with theoretical predictions of scaling laws.

D. S. L. Soares, R. E. de Souza, R. R. de Carvalho, T. C. Couto da Silva

A catalogue of binary galaxies with 621 pairs has been determined by applying a surface density enhancement procedure to {\it The Surface Photometry Catalogue of the ESO-Uppsala Galaxies}. The method does not require any redshift information. An additional restriction, based on objective criteria that take into account the completeness of the source catalogu

W. J. Duschl, K. -H. Hofmann, F. Rigaut, G. Weigelt

We present a high-resolution image of $η$~Car. Together with IR and visual observations of the central arcsecond, we use this to discuss the morphological structure of $η$~Car on the different length scales. We identify three different structural components: a bipolar outflow, an equatorial disk of streamers, and the speckle objects. We discuss models for th