May 1994 arXiv papers — page 5

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

An effective two-body interaction is constructed from a new Reid-like $NN$ potential for a large no-core space consisting of six major shells and is used to generate the shell-model properties for light nuclei from $A$=2 to 6. (For practical reasons, the model space is partially truncated for $A$=6.) Binding energies and other physical observables are calcul

David E. Kahana, Declan Keane, Yang Pang, Tom Schlagel

The phenomenon of collective flow in relativistic heavy ion collisions is studied using the hadronic cascade model ARC. Direct comparison is made to data gathered at the Bevalac, for Au+Au at $p=1-2$ GeV/c. In contrast to the standard lore about the cascade model, collective flow is well described quantitatively without the need for explicit mean field terms

Peter G. Casazza, Nigel J. Kalton, Denka Kutzarova, M. Mastylo

We construct a class of super-reflexive complementably minimal spaces, and study uniformly convex distortions of the norm on Hilbert space by using methods of complex interpolation.

Dmitri Vassilevich

We consider possible definitions of physical variables in QED. We demonstrate that the condition $\partial_i A_i$$=0$ is the most convenient one because it leads to path integral over physical components with local action. However, other choices, as $A_3=0$, are also possible. The standard expression for configuration space path integral in $A_3=0$ gauge is

J. C. Brunelli, Ashok Das, Wen-Jui Huang

We generalize the construction of Gelfand-Dikii brackets to the case of nonstandard Lax equations. We also discuss the possible origin of Kac-Moody algebras present in such systems.

Peter Schaller, Thomas Strobl

A class of two dimensional field theories, based on (generically degenerate) Poisson structures and generalizing gravity-Yang-Mills systems, is presented. Locally, the solutions of the classical equations of motion are given. A general scheme for the quantization of the models in a Hamiltonian formulation is found.

T. Eguchi, Y. Yamada, S. -K. Yang

A systematic formulation of the higher genus expansion in topological string theory is considered. We also develop a simple way of evaluating genus zero correlation functions. At higher genera we derive some interesting formulas for the free energy in the $A_1$ and $A_2$ models. We present some evidence that topological minimal models associated with Lie alg

B. Schroer, FU Berlin

We derive the Kac Wakimoto formula in the algebraic framework of chiral conformal QFT s a consequence of the universal behaviour of high-temperature Gibbs-states on intertwiner subalgebras. By studying selfintertwiners in the presence of other charges, we obtain charge-polarization coefficients which generalize the entries of Verlinde matrix S and belong to

Leonard Susskind

Strominger has proposed an interesting concrete realization of Hawking's idea that information is lost in black hole evaporation. In this note we demonstrate that a straightforward interpretation of Strominger's model leads to a complete breakdown of the conditions for using statistics for analyzing the results of experiments. The probabilities produ

Neven Bilic

Transition from the quark-gluon (QG) plasma to a hadronic gas is studied in the framework of the relativistic combustion theory. The calculations reveal that the QG phase must be in a strongly supercooled state. The stability of this solution with respect to minor modifications is investigated. In particular the effect of an admixture of hadronic matter in t

A. Khodjamirian, R. Rückl

The method of QCD sum rules has proven to be particularly useful in heavy quark physics, where a small distance scale is provided by the inverse heavy quark mass. We present two new examples for the application of this method to B-physics: a calculation of the heavy-to-light form factors $B \rightarrow π,K$ and an estimate of the weak decay amplitude for $B

Markus H. Thoma

The damping rate of a hard photon in a hot relativistic QED and QCD plasma is calculated using the resummation technique by Braaten and Pisarski.

Alan D. Sokal

This article is a pedagogical review of Monte Carlo methods for the self-avoiding walk, with emphasis on the extraordinarily efficient algorithms developed over the past decade.

Sabino José Ferreira, Alan D. Sokal

We study the antiferromagnetic $q$-state Potts model on the square lattice for $q=3$ and $q=4$, using the Wang-Swendsen-Kotecký Monte Carlo algorithm and a new finite-size-scaling extrapolation method. For $q=3$ we obtain good control up to correlation length $ξ\sim 5000$; the data are consistent with $ξ(β) = A e^{2β} β(1 + a_1 e^{-β} + \ldots)$ as $β\to\inf

H. Aoki, S. Iso, J. Nishimura, M. Oshikawa

We study the effect of dynamical gauge field on the Kaplan's chiral fermion on a boundary in the strong gauge coupling limit in the extra dimension. To all orders of the hopping parameter expansion, we prove exact parity invariance of the fermion propagator on the boundary. This means that the chiral property of the boundary fermion, which seems to survi

Bruce Allen, Paul Casper, Adrian Ottewill

Cosmic string loops are defined by a pair of periodic functions ${\bf a}$ and ${\bf b}$, which trace out unit-length closed curves in three-dimensional space. We consider a particular class of loops, for which ${\bf a}$ lies along a line and ${\bf b}$ lies in the plane orthogonal to that line. For this class of cosmic string loops one may give a simple analy

Wenbin Yu, D. Stroud

We show analytically that the inverse kinetic inductance $L^{-1}$ of an overdamped junction array at low frequencies is proportional to the admittance of an inhomogeneous equivalent impedance network. The $ij^{th}$ bond in this equivalent network has an inverse inductance $J_{ij}\cos(θ_i^0-θ_j^0-A_{ij})$, where $J_{ij}$ is the Josephson coupling energy of th

R. Kühn

The critical behaviour of the randomly spin-diluted Ising model in two space dimensions is investigated by a new method which combines a grand ensemble approach to disordered systems proposed by Morita with the phenomenological renormalization group scheme of Nightingale. Accurate approximations for the phase diagram and for the connectivity length exponent

A. Luther

Electronic states near a square Fermi surface are mapped onto quantum chains. Using boson-fermion duality on the chains, the bosonic part of the interaction is isolated and diagonalized. These interactions destroy Fermi liquid behavior. Non-boson interactions are also generated by this mapping, and give rise to a new perturbation theory about the boson probl

Mushti V. Ramakrishna, Jun Pan

Smalley and co-workers discovered that chemisorption reactivities of silicon clusters vary over three orders of magnitude as a function of cluster size. In particular, they found that \Si{33}, \Si{39}, and \Si{45} clusters are least reactive towards various reagents compared to their immediate neighbors in size. We explain these observations based on our stu

E. Roulet, S. Mollerach, G. F. Giudice

We discuss whether the astrophysical objects responsible for the recently reported microlensing events of sources in the Large Magellanic Cloud can be identified as the brown dwarf components of the spheroid of our galaxy, rather than the constituents of a dark baryonic halo.

Iqbal Adjali, José-Luis Fernández-Villacañas, Michael Gell

We build on a previous statistical model for distributed systems and formulate it in a way that the deterministic and stochastic processes within the system are clearly separable. We show how internal fluctuations can be analysed in a systematic way using Van Kanpen's expansion method for Markov processes. We present some results for both stationary and

Francois Gieres

Nous presentons une introduction aux concepts de la supersymetrie par l'intermediaire de trois exemples: (i) Mecanique quantique supersymetrique, (ii) Superalgebres de Lie, (iii) Superconnexions de Quillen. Les points communs a toutes ces notions sont soulignes et des applications sont indiquees. En particulier nous esquissons la demonstration du theorem

A. B. Lahanas, V. C. Spanos

We systematically analyze the anomalous dipole $Δk_γ$ and quadrupole $ΔQ_γ$ moments of the W gauge bosons in the context of the minimal supersymmetric standard model as functions of the soft SUSY breaking parameters $A_0,m_0,M_{1/2}$ and the top quark mass. The severe constraints imposed by the radiative breaking mechanism of the electroweak symmetry\,$ SU(2

Kanehisa Takasaki, Takashi Takebe

Analogues of the KP and the Toda lattice hierarchy called dispersionless KP and Toda hierarchy are studied. Dressing operations in the dispersionless hierarchies are introduced as a canonical transformation, quantization of which is dressing operators of the ordinary KP and Toda hierarchy. An alternative construction of general solutions of the ordinary KP a

Paul Demkin

Novel infinite-dimensional algebras of the Virasoro/Kac-Moody/ Floratos-Iliopoulos type are introduced, which involve special functions in their structure constants

Andrea Pasquinucci, Kaj Roland

We explicitly compute the anomalous magnetic moment at one loop level for an ``electron'' in a 4d heterotic string theory. The anomalous magnetic moment vanishes if the model is spacetime supersymmetric, as required by the supersymmetric sum rules.

Masako Asano, Saburo Higuchi

We investigate the 3d lattice topological field theories defined by Chung, Fukuma and Shapere. We concentrate on the model defined by taking a deformation $\D{G}$ of the quantum double of a finite commutative group $G$ as the underlying Hopf algebra. It is suggested that Chung-Fukuma-Shapere partition function is related to that of Dijkgraaf-Witten by $\zcfs

G. A. F. T. da Costa

The BH algebra is defined by two sets of generators one of which satisfy the relations of the braid group and the other the relations of the Hecke algebra of projectors.These algebras are then combined by additional relations in a way which generalizes the Birman-Wenzl algebra.In this paper we Yang-Baxterize the algebra BH and compute solutions of the Yang-B

Sergio Albeverio, Shao-Ming Fei

By investigating the symplectic geometry and geometric quantization on a class of supermanifolds, we exhibit BRST structures for a certain kind of algebras. We discuss the undeformed and q-deformed cases in the classical as well as in the quantum cases.

L. Lavoura

I discuss methods to identify the presence of dicrete symmetries in the two-Higgs-doublet model by observing the masses and the cubic and quartic interactions of the scalars. The symmetries considered are a $ Z_2 $ symmetry under which $ ϕ_2 \rightarrow - ϕ_2 $, and a CP symmetry which enforces real coupling constants in the Higgs potential. Those symmetries

H. -C. Jean, D. Robson, A. G. Williams

The work described in this paper is the first step toward a relativistic three-quark bound-state calculation using a Hamiltonian consistent with the Wigner-Bargmann theorem and macroscopic locality. We give an explicit demonstration that we can solve the two-body problem in momentum space with spin-dependent interactions. The form of the potential is a combi

R. Ma'nka

The phase transition in the Weinberg-Salam-Glashow (GSW) electroweak theory extended by the majoron and dilaton field is considered. The possibility of the boson condensation in the extreme conditions in the standard electroweak theory is shown. The first order phase transition induces by the radiative corrections (the Coleman-Weinberg potential) in the pres

M. Beneke, V. M. Braun, V. I. Zakharov

We investigate the one-loop radiative corrections to the semileptonic decay of a charged particle at finite gauge boson mass. Extending the Bloch-Nordsieck cancellation of infrared logarithms, the subsequent non-analytic terms are also found to vanish after eliminating the pole mass in favor of a mass defined at short distances. This observation justifies th

H. Holtmann, N. N. Nikolaev, J. Speth, A. Szczurek

In a recent CERN Drell-Yan experiment the NA51 group found a strong asymmetry of $\bar u$ and $\bar d$ densities in the proton at $x\simeq0.18$. We interpret this result as a decisive confirmation of the pion-induced sea in the nucleon.

F. del Aguila

All couplings of a new heavy gauge boson to ordinary fermions can be determined in a model-independent way at a large $e^+e^-$ collider for large enough statistics. No such determination is possible at LEP 200, however, because its design integrated luminosity is too low for existing and forthcoming limits on $Z'$ interactions. At any rate, it should be

Kirill Melnikov, Michael Spira, Oleg Yakovlev

The couplings of Higgs particles to two photons are analyzed in the threshold region, where the Higgs mass is about twice the loop--particle mass leading to possible bound state formation. The amplitude of the pseudoscalar decay $A\to γγ$ for pseudoscalar masses in the range of $(t\bar t)$--bound state masses is calculated in leading and next--to--leading or

M. Reuter, C. Wetterich

Within the Euclidean effective action approach we propose criteria for the ground state of QCD. Despite a nonvanishing field strength the ground state should be invariant with respect to modified Poincaré transformations consisting of a combination of translations and rotations with suitable gauge transformations. We have found candidate states for QCD with

Bernd A. Kniehl

Low- and intermediate mass Higgs bosons decay preferably into fermion pairs. The one-loop electroweak corrections to the respective decay rates are dominated by a flavour-independent term of ${\cal O}(G_Fm_t^2)$. We calculate the two-loop gluon correction to this term. It turns out that this correction screens the leading high-$m_t$ behaviour of the one-loop

Yongseok Oh, Byung-Yoon Park, Dong-Pil Min

We investigate the pentaquark($P$) exotic baryons as soliton-antiflavored heavy mesons bound states in the limit of infinitely heavy meson mass. Our approach respects the chiral symmetry as well as the heavy quark symmetry. The results reveal a possibility for the loosely bound non-strange $P$-baryon(s).

John G. Learned, Sandip Pakvasa

It is suggested that a large deep underocean neutrino detector, given the presence of significant numbers of neutrinos in the PeV range as predicted by various models of Active Galactic Nuclei, can make unique measurements of the properties of neutrinos. It will be possible to observe the existence of the nu_tau, measure its mixing with other flavors, in fac

Claudio Coriano', Hsiang-nan Li

We investigate the transition to perturbative QCD in Compton processes, by concentrating on the specific reactions $πγ\to πγ$ and pion photoproduction at moderate energy scales. New sum rules for each of the helicities involved in the scattering and the cross section are given, together with a detailed stability analysis. Our results are then compared with t

Bas V. de Bakker, Jan Smit

The number of configurations of the dynamical triangulation model of 4D euclidean quantum gravity appears to grow faster than exponentially with the volume, with the implication that the system would end up in the crumpled phase for any fixed $κ_2$ (inverse bare Newton constant). However, a scaling region is not excluded if we allow $κ_2$ to go to infinity t

F. Abe

We summarize a search for the top quark with the Collider Detector at Fermilab (CDF) in a sample of $\bar{p}p$ collisions at $\sqrt{s}$= 1.8 TeV with an integrated luminosity of 19.3~pb$^{-1}$. We find 12 events consistent with either two $W$ bosons, or a $W$ boson and at least one $b$ jet. The probability that the measured yield is consistent with the backg

Des J. Mc Manus, Alan A. Coley

General relativistic anisotropic fluid models whose fluid flow lines form a shear-free, irrotational, geodesic timelike congruence are examined. These models are of Petrov type D, and are assumed to have zero heat flux and an anisotropic stress tensor that possesses two distinct non-zero eigenvalues. Some general results concerning the form of the metric and

Alan A. Coley, Des J. Mc Manus

A comprehensive analysis of general relativistic spacetimes which admit a shear-free, irrotational and geodesic timelike congruence is presented. The equations governing the models for a general energy-momentum tensor are written down. Coordinates in which the metric of such spacetimes takes on a simplified form are established. The general subcases of `zero

Karl H. Hofmann, Karl-H. Neeb

We answer a question raised by V.G.Pestov in the affirmative.

D. Poilblanc, H. Tsunetsugu, T. M. Rice

Spin gaps in coupled $t$-$J$ ladders are investigated by exact diagonalization of small clusters up to 4$\times$8 sites. At half-filling, the numerical results for the triplet excitation spectrum are in very good agreement with a second order perturbation expansion in term of small inter-ladder and intra-ladder exchange couplings between rungs ($J/J^\prime$$

Kikuo Harigaya

We theoretically investigate optical absorption spectra of $\soc^{6-}$ and $\rug^{6-}$, and discuss relations with the optical properties of alkali metal doped fullerides $A_6\soc$ and $A_6\rug$. This is a valid approach for systems where Frenkel exciton effects are dominant. We use a tight binding model with long ranged Coulomb interactions and bond disorde

Walter Daelemans

Current approaches to computational lexicology in language technology are knowledge-based (competence-oriented) and try to abstract away from specific formalisms, domains, and applications. This results in severe complexity, acquisition and reusability bottlenecks. As an alternative, we propose a particular performance-oriented approach to Natural Language P

B. Rumpf, H. Sauermann

Two classical, damped and driven spin oscillators with an isotropic exchange interaction are considered. They represent a nontrivial physical system whose equations of motion are shown to allow for an analytic treatment of local codimension 1 and 2 bifurcations. In addition, numerical results are presented which exhibit a Feigenbaum route to chaos.

J. R. Dorfman, P. Gaspard

The chaotic scattering theory is here extended to obtain escape-rate expressions for the transport coefficients appropriate for a simple classical fluid, or for a chemically reacting system. This theory allows various transport coefficients such as the coefficients of viscosity, thermal conductivity, etc., to be expressed in terms of the positive Lyapunov ex

Chris Mihos, Lars Hernquist

We use numerical simulation to investigate the triggering of starbursts in merging disk galaxies. The properties of the merger-driven starbursts are sensitive to the structure of the progenitor galaxies; specifically, to the amount of material in a dense central bulge. Galaxies without bulges develop bars shortly after their first close passage, driving sign

Gary Steigman

Two groups have independently reported the possible detection of extragalactic deuterium in the absorption spectrum of the same high redshift, low metalicity QSO. Although the high value for the inferred deuterium abundance poses no problems for cosmology (i.e., big bang nucleosynthesis), it is in apparent conflict with solar system observations of deuterium

T. Matsubara

The gravitational evolution of the genus of the density field in large-scale structure is analytically studied in a weakly nonlinear regime using second-order perturbation theory. Weakly nonlinear evolution produces asymmetry in the symmetric genus curve for Gaussian initial density field. The effect of smoothing the density field in perturbation theory on t

Klaus Altmann

The obstruction space T^2 and the cup product T^1 x T^1 -> T^2 are computed for toric singularities.

Chris Adami, C. Titus Brown

We present a new tierra-inspired artificial life system with local interactions and two-dimensional geometry, based on an update mechanism akin to that of 2D cellular automata. We find that the spatial geometry is conducive to the development of diversity and thus improves adaptive capabilities. We also demonstrate the adaptive strength of the system by bree

Chris Adami

We present a theoretical as well as experimental investigation of a population of self-replicating segments of code subject to random mutation and survival of the fittest. Under the assumption that such a system constitutes a minimal system with characteristics of life, we obtain a number of statements on the evolution of complexity and the trade-off between

A. L. Kataev, V. V. Starshenko

We present the estimates of the order $O(\alpha^{4}_{s})$ QCD corrections to $R(s)$, $R_{\tau}$ and to the deep-inelastic scattering sum rules, namely to the non-polarized and polarized Bjorken sum rules and to the Gross-Llewellyn Smith sum rule. The estimates are obtained in the $\overline{MS}$-scheme using the principle of minimal sensitivity and the effec

Andrew Strominger

This paper has been withdrawn pending revision.

V. F. Dmitriev, I. B. Khriplovich, V. B. Telitsin

A static magnetic quadrupole moment of a nucleus, induced by T- and P-odd nucleon-nucleon interaction, is investigated in the single-particle approximation. Models are considered allowing for analytical solution. The problem is also treated numerically in a Woods-Saxon potential with spin-orbit interaction. The stability of results is discussed.

Sakaé Fuchino, Saharon Shelah, Lajos Soukup

We show that a theorem of Leonid B. Shapiro which was proved under MA, is actually independent from ZFC. We also give a direct proof of the Boolean algebra version of the theorem under MA(Cohen).

Menachem Magidor, Saharon Shelah

Using the consistency of some large cardinals we produce a model of Set Theory in which the generalized continuum hypothesis holds and for some torsion-free abelian group G of cardinality aleph_{omega +1} and for some torsion group T, Bext^2(G,T) not =0 .

Francesco Toppan

We define consistent finite-superfields reductions of the $N=1,2$ super-KP hierarchies via the coset approach we already developped for reducing the bosonic KP-hierarchy (generating e.g. the NLS hierarchy from the $sl(2)/U(1)-{\cal KM}$ coset). We work in a manifestly supersymmetric framework and illustrate our method by treating explicitly the $N=1,2$ super

E. Kh. Akhmedov

Present status of the neutrino magnetic moment solutions of the solar neutrino problem is reviewed. In particular, we discuss a possibility of reconciling different degrees of suppression and time variation of the signal (or lack of such a variation) observed in different solar neutrino experiments. It is shown that the resonant spin--flavor precession of ne

Wolfram Just

The dynamics of globally coupled map lattices can be described in terms of a nonlinear Frobenius--Perron equation in the limit of large system size. This approach allows for an analytical computation of stationary states and their stability. The complete bifurcation behaviour of coupled tent maps near the chaotic band merging point is presented. Furthermore

Wolfram Just

Bifurcations in a system of coupled maps are investigated. Using symbolic dynamics it is proven that for coupled shift maps the well known space--time--mixing attractor becomes unstable at a critical coupling strength in favour of a synchronized state. For coupled non--hyperbolic maps analytical and numerical evidence is given that arbitrary small coupling c

G. Sigl, M. S. Turner

The emission of $\MeV$-mass tau neutrinos from newly formed neutron stars is considered in a simple, but accurate, model based upon the diffusion approximation. The tau-neutrinosphere temperature is found to increase with mass so that emission of massive tau neutrinos is not suppressed by the Boltzmann factor previously used, $(\mnu /T_ν)^{1.5}\exp(-\mnu/T_ν

E. M. de Gouveia Dal Pino, W. Benz

Short abstract: We present fully 3-D simulations of supersonic, radiatively cooling intermittent jets with intermediate and long variability periods (that is, periods of the order of or longer than, the dynamical time scale of the jet). Variations of intermediate period elucidate the formation and evolution of chains of internal regularly spaced radiative sh

Richard Easther

We consider the spectrum of primordial fluctuations produced by inflationary models where the inflaton potential is the sum of two exponential terms. A wide range of spectra result, with the only constraint being that the scalar spectrum must have more tilt than the tensor spectrum. This model can mimic the spectra of most inflationary models, as well as pro

Mikhail Entov

We show how the classification of simple singularities of functions can be reduced directly, not using the normal forms, to the classification of irreducible Weyl groups. We also prove that the class of a singularity in its local algebra always belongs to the tangent cone to the stratum $μ=const$ of the singularity. An interesting characterization of Coxeter

H. Awata, M. Fukuma, Y. Matsuo, S. Odake

We diagonalize the Hilbert space of some subclass of the quasifinite module of the \Winf algebra. States are classified according to their eigenvalues for infinitely many commuting charges and the Young diagrams. The parameter dependence of their norms is explicitly derived. The full character formulae of the degenerate representations are given as summation

Adam Epstein, Linda Keen, Charles Tresser

Consider the two-parameter family of real analytic maps $F_{a,b}:x \mapsto x+ a+{b\over 2π} \sin(2πx)$ which are lifts of degree one endomorphisms of the circle. The purpose of this paper is to provide a proof that for any closed interval $I$, the set of maps $F_{a,b}$ whose rotation interval is $I$, form a contractible set.

Phillial Oh

We present a classical integrable model of $SU(N)$ isospin defined on complex projective phase space in the external magnetic field and solve it exactly by constructing the action-angle variables for the system. We quantize the system using the coherent state path integral method and obtain an exact expression for quantum mechanical propagator by solving the

A. V. Kotikov, V. G. Krivokhizhin, G. Parente

It is performed for the first time a next-to-next-to-leading order analysis of deep inelastic structure functions $F_2$ and $F_L$ using the recently determined first moments of the non-singlet anomalous dimensions and the corresponding Wilson coefficients. {}From a comparison to BCDMS data we found a slight decrease in the energy scale of perturbative QCD wi

Th. Meissner

We determine the convergence radius $m_{conv}$ for the expansion in the current quark mass using the Dyson-Schwinger (DS) equation of QCD in the rainbow approximation. Within a Gaussian form for the gluon propagator $D_{μν} ({\bf p}) \sim δ_{μν} χ^2 e^{- {{p^2} \over Δ}}$ we find that $m_{conv}$ increases with decreasing width $Δ$ and increasing strength $χ^

J. C. Talstra, F. D. M. Haldane

We present a new selection rule for matrix elements of local spin operators in the $S=1/2$ ``Haldane-Shastry'' model. Based on this rule we extend a recent exact calculation \cite{H93} of the ground-state dynamical spin correlation function $S^{ab}(n,t)$ = $\langle 0 | S^a(n,t)S^b(0,0)| 0 \rangle$ and its Fourier-transform $S^{ab}(Q,E)$ of this model

H. Rieger J. Kisker, M. Schreckenberg

Results of extensive Monte-Carlo simulations that investigate the out-of-equilibrium dynamics of the one-dimensional Ising spin glass model with a Gaussian bond-distribution are presented. At low enough temperatures a typical (interrupted) aging scenario is established as in two- and similar to three-dimensional spin glass models. Since the underlying mechan

Rinat Kedem, Barry M. McCoy

We study the quasi-particle spectrum of the integrable three-state chiral Potts chain in the massive phase by combining a numerical study of the zeroes of associated transfer matrix eigenvalues with the exact results of the ferromagnetic three-state Potts chain and the three-state superintegrable chiral Potts model. We find that the spectrum is described in

A. Ali, D. London

Motivated by the recent determination of the top quark mass by the CDF collaboration, $\mt =174 \pm 10 ^{+13}_{-12}$ GeV, we review and update constraints on the parameters of the quark flavour mixing matrix $V_{CKM}$ in the standard model. In performing these fits, we use inputs from the measurements of $\abseps$, the CP-violating parameter in $K$ decays, $

Nelson R. F. Braga

It is shown how the BRST quantization can be applied to a gauge invariant sector of theories with anomalously broken symmetries. This result is used to show that shifting the anomalies to a classically trivial sector of fields (Wess-Zumino mechanism) makes it possible to quantize the physical sector using a standard BRST procedure, as for a non anomalous the

C. Bartocci, U. Bruzzo, D. Hernandez Ruiperez

We define a Fourier-Mukai transform for sheaves on K3 surfaces over $\C$, and show that it maps polystable bundles to polystable ones. The role of ``dual'' variety to the given K3 surface $X$ is here played by a suitable component $\hat X$ of the moduli space of stable sheaves on $X$. For a wide class of K3 surfaces $\hat X$ can be chosen to be isomo

Erik A. Martinez

The quasilocal energy associated with a constant stationary time slice of the Kerr spacetime is presented. The calculations are based on a recent proposal \cite{by} in which quasilocal energy is derived from the Hamiltonian of spatially bounded gravitational systems. Three different classes of boundary surfaces for the Kerr slice are considered (constant rad

A. D. Martin

We review recent developments in the determination of parton densities from deep inelastic and related data. We show how the asymmetries observed in the W+- rapidity distributions and in pp/pn Drell-Yan production further constrain the partons at moderate x. We compare the GLAP and BFKL descriptions of the recent measurements of F2(x,Q**2) at HERA. We survey

Rolf Schimmrigk

Because of the existence of rigid Calabi--Yau manifolds, mirror symmetry cannot be understood as an operation on the space of manifolds with vanishing first Chern class. In this article I continue to investigate a particular type of Kähler manifolds with positive first Chern class which generalize Calabi--Yau manifolds in a natural way and which provide a fr

Q. Niu, M. C. Chang, C. K. Shih

We explore the possibility of using a double-tip STM to probe the single electron Green function of a sample surface, and describe a few important applications: (1) Probing constant energy surfaces in $\k$-space by ballistic transport; (2) Measuring scattering phase shifts of defects; (3) Observing the transition from ballistic to diffusive transport to loca

David R. Harrington

Meson exchange contributions have been suggested as one class of medium effects which might explain the continuing discrepancy between experimental results and theoretical predictions for K+-nucleus scattering. These exchange effects are negligible for near-forward K+-deuteron scattering because of the large size of the deuteron, but at large angles they mig

F. Cardarelli, I. L. Grach, I. M. Narodetskii E. Pace, G. Salmè

The high momentum components generated in the wave function of pseudoscalar mes* by the one-gluon-exchange interaction are investigated within a relativistic constituent quark model. Adopting the light-cone formalism, the sensitivity of the weak decay constant and the charge form factor to hard constituent quarks is illustrated.

S. Drożdż, J. Okołowicz, T. Srokowski, A. Budzanowski

Statistical aspects of the dynamics of chaotic scattering in the classical model of $α$-cluster nuclei are studied. It is found that the dynamics governed by hyperbolic instabilities which results in an exponential decay of the survival probability evolves to a limiting energy distribution whose density develops the Boltzmann form. The angular distribution o

Greg Kuperberg, Oded Schramm

The Koebe circle packing theorem states that every finite planar graph can be realized as the nerve of a packing of (non-congruent) circles in R^3. We investigate the average kissing number of finite packings of non-congruent spheres in R^3 as a first restriction on the possible nerves of such packings. We show that the supremum k of the average kissing numb

Stephen Pinsky

In the first part of this lecture I will give an introduction to light-cone field theory, focussing on the ``zero mode problem''. In the second part I discuss $ϕ^4$-theory in 1+1 dimensions. I will show how the dynamics of the zero modes can give rise to spontaneous symmetry breaking in spite of the trivial vacuum structure on the light-cone.

Andrei Bytsenko, Klaus Kirsten, Sergio Zerbini

An attempt is made to compare the asymptotic state density of twisted $p$-branes and the related state density of mass level $M$ of a $D$-dimensional neutral black hole. To this aim, the explicit form of the twisted $p$-brane total level degeneracy is calculated. The prefactor of the degeneracy, in contrast to the leading behaviour, is found to depend on the

L. Faddeev, A. Yu. Volkov

The hamiltonian formalism is developed for the sine-Gordon model on the space-time light-like lattice, first introduced by Hirota. The evolution operator is explicitely constructed in the quantum variant of the model, the integrability of the corresponding classical finite-dimensional system is established.

A. Strominger, L. Thorlacius

Quantum mechanical boundary conditions along a timelike line, corresponding to the origin in radial coordinates, in two-dimensional dilaton gravity coupled to $N$ matter fields, are considered. Conformal invariance and vacuum stability severely constrain the possibilities. The simplest choice found corresponds to a nonlinear Liouville-type boundary interacti

Gautam Dutta, K. B. Vijaykumar, Anjan S. Joshipura

Gauged extensions [$SU(2)_L\otimes U(1)_Y\otimes U(1)_X$] of the standard $SU(2)_L\otimes U(1)_Y$ model obtained without extending the fermion content of the model are studied. Models that are possible when $U(1)_X$ is identified with some combination of the family lepton numbers are systematically classified. Most of these contain flavor violations in the l

Gautam Dutta, Anjan S. Joshipura

Specific class of textures for the Dirac and Majorana mass matrices in the seesaw model leading to a pair of almost degenerate neutrinos is discussed. These textures can be obtained by imposing a horizontal $U(1)$ symmetry. A specific model is discussed in which: (1) All three neutrino masses are similar in magnitude and could lie around eV providing hot com

Xiao-Gang He, B. H. J. McKellar

We study $ε'/ε$ in the Standard Model and $ε'/ε$ due to anomalous $WWγ$ and $WWZ$ interactions %using recent result on the top quark mass from CDF. as a function of the top quark mass. In the Standard Model, $ε'/ε$ is in the range $10^{-3} \sim 10^{-4}$ for the central value of top quark mass reported by CDF. The anomalous gauge couplings can hav

David K. Griegel, Thomas D. Cohen

QCD sum rules are useful tools for studying the spectral properties of hadrons; however, assumptions underlying standard sum-rule analyses can lead to inconsistencies with known results of chiral perturbation theory. This possibility is demonstrated with QCD sum-rule extractions of the nucleon mass and $σ$ term. In both cases, inconsistent chiral behavior le

Tanmay Vachaspati

We describe electroweak strings and their ability to carry Chern-Simons number. Certain string configurations, for any $θ_W$, carry Chern-Simons number equal to that of the sphaleron and we conjecture that such strings are ``extended sphalerons''. The production of electroweak strings during the phase transition is discussed and it is suggested that

Tanmay Vachaspati

We consider dyon configurations in the standard electroweak model. In the presence of a $θ$ term and no fermions, the usual result $q = (n+θ/2π) e$ is obtained for the electric charge spectrum. The effect of including standard model fermions is discussed qualitatively.