November 1994 arXiv papers — page 9

R. Barbieri, P. Ciafaloni, A. Strumia

In a generic Grand Unified Theory with a relatively small dispersion of the spectrum around the $Z$-boson and the unification masses, a connection is established, exact at one loop level, between $M_Z$, $G_{\rm F}$, $α(M_Z)$ and the strong coupling constant $α_3(M_Z)$. At this level of precision, this avoids the logical and phenomenological inconsistency of

J. A. Phillips, T. Joseph W. Lazio

We have observed the hard X-ray source 1E1740.7-2942 in the HCO+ (1-0) line using the Owens Valley millimeter interferometer. Previous single dish observations have found HCO+ emission coincident with the location of the radio continuum hot spots of the radio source associated with 1E1740.7-2942. Our higher resolution observations show a 15 arcsec offset bet

M. Laine

The high-temperature limit of the 2-loop effective potential for the Higgs field is calculated from an effective 3d theory, in a general covariant gauge. It is shown explicitly that a gauge-independent result can be extracted for the equation of state from the gauge-dependent effective potential. The convergence of perturbation theory is estimated in the bro

B. Bunk, K. Jansen, B. Jegerlehner, M. Lüscher

A previously introduced multi-boson technique for the simulation of QCD with dynamical quarks is described and some results of first test runs on a $6^3\times12$ lattice with Wilson quarks and gauge group SU(2) are reported.

Saurya Das, Parthasarathi Majumdar

The scattering of pointlike particles at very large center of mass energies and fixed low momentum transfers, occurring due to both their electromagnetic and gravitational interactions is re-examined in the particular case when one of the particles carries magnetic charge. At Planckian center-of-mass energies, when gravitational dominance is normally expecte

Burak Gurel, Metin Gurses, Ismagil Habibullin

Boundary value problems for integrable nonlinear partial differential equations are considered from the symmetry point of view. Families of boundary conditions compatible with the Harry-Dym, KdV and MKdV equations and the Volterra chain are discussed. We also discuss the uniqueness of some of these boundary conditions.

J. M. Sanchez, V. Pierron-Bohnes, F. Mejia-Lira

A reciprocal space formulation of the Cluster Variation is used in order to extract effective pair interactions in alloys from experimental short-range order diffuse intensities. The method is applied to the analysis of the short range order contribution to the neutron diffuse scattering of a $Fe-19.5 {\%} Al$ single crystal. A detailed comparison with real

Hiroyuki Yoshida

As we have shown several years ago [Y2], zeros of $L(s, Δ)$ and $L^(2)(s, Δ)$ can be calculated quite efficiently by a certain experimental method. Here $Δ$ denotes the cusp form of weight 12 with respect to SL$(2, Z)$ and $L(s, Δ)$ (resp. $L^(2)(s, Δ)$) denotes the standard (resp. symmetric square) $L$-function attached to $Δ$. The purpose of this paper is

William Duke

A new upper bound is given for the dimension of the space of holomorphic cusp forms of weight one and prime level $q$: $$ \hbox{dim}\, S_1(q) << q^{11/12} \log^4{q} $$ with an absolute implied constant.

Lay Nam Chang, Chopin Soo

We discuss a global anomaly associated with the coupling of chiral Weyl fermions to gravity. The Standard Model based upon $SU(3){\times}SU(2){\times}{U(1)}$ which has 15 fermions per generation is shown to be inconsistent if all background spin manifolds with signature invariant $τ=8k$ are allowed. Similarly, GUTs based on odd number of Weyl fermions are in

Geoffrey Dixon

In this episode, it is shown how the octonion X-product is related to E8 lattices, integral domains, sphere fibrations, and other neat stuff.

L. Chen, G. Dunne, K. Haller, E. Lim-Lombridas

We consider a spontaneously broken nonabelian topologically massive gauge theory in a broken phase possessing a residual nonabelian symmetry. Recently there has been some question concerning the renormalization of the Chern-Simons coefficient in such a broken phase. We show that, in this broken vacuum, the renormalized ratio of the Chern-Simons coupling to t

B. Bruegmann, E. Marinari

A crucial requirement for the standard interpretation of Monte Carlo simulations of simplicial quantum gravity is the existence of an exponential bound that makes the partition function well-defined. We present numerical data favoring the existence of an exponential bound, and we argue that the more limited data sets on which recently opposing claims were ba

Z. Hasiewicz, P. Siemion

We show that a chiral sector of a symplectic group manifold possesses a symmetry similar to, but somewhat weaker than the Lie--Poisson one.

A. Burnel, H. Caprasse, A. Dresse

It is shown that for a large class of non-holonomic quantum mechanical systems one can make the computation of BRST charge fully algorithmic. Two computer algebra programs written in the language of {\tt REDUCE} are described. They are able to realize the complex calculations needed to determine the charge for general nonlinear algebras. Some interesting spe

E. Sezgin

We review the salient features of spacetime and worldvolume supersymmetric super p-brane actions. These are sigma models for maps from a worldvolume superspace to the target superspace. For p-branes, the symmetries of the model depend crucially on the existence of closed super (p+1)-forms on a worldvolume superspace, built out of the pull-backs of the Kalb-R

C. P. Burgess

Several reasonably model-independent formulations of the implications of new physics for precision electroweak measurements have been developed over the past years, most notably by Peskin and Takeuchi, and by Altarelli \etal. These formulations work by identifying a small, but useful, set of parameters through which new physics often enters into well-measure

R. A. Bertlmann

We present two different aspects of the anomalies in quantum field theory. One is the dispersion relation aspect, the other is differential geometry where we derive the Stora--Zumino chain of descent equations.

M. Knecht, J. Stern

The Generalized Chiral Perturbation Theory enlarges the framework of the standard $χ$PT, relaxing certain assumptions which do not necessarily follow from QCD or from experiment, and which are crucial for the usual formulation of the low energy expansion. In this way, experimental tests of the foundations of the standard $χ$PT become possible. Emphasis is pu

Peter G. Tinyakov, Emil Mottola, Salman Habib

We consider winding number transitions in the two dimensional O(3) non-linear sigma model, modified by a suitable conformal symmetry breaking term. We discuss the general properties of the relevant instanton solutions which dominate the transition amplitudes at finite energy, and find the solutions numerically. The Euclidean period of the solution increases

G. de Divitiis, R. Frezzotti, M. Guagnelli, M. Luescher

The universality of the continuum limit and the applicability of renormalized perturbation theory are tested in the SU(2) lattice gauge theory by computing two different non-perturbatively defined running couplings over a large range of energies. The lattice data (which were generated on the powerful APE computers at Rome II and DESY) are extrapolated to the

C. Michael, P. S. Spencer

Using an under-relaxed cooling algorithm we investigated the vacuum in the $2d\ O(3)$ model and $4d$ pure gauge $SU(2)$. We calibrated the amount of cooling performed to have similar physical effect at different lattice spacings.

B. Alles, M. Beccaria, L. Del Debbio, R. Del Real

The continuum limit and scaling properties of an asymptotically free field theory regularized on a random lattice are compared with those on a regular square lattice. We work on random lattices parametrized by a degree of ``randomness&#39;&#39; $κ$. We show that the continuum limit exists and different $κ$ are related by a finite renormalization.

P. Lacock

We propose the study of non-local gauge invariant operators to obtain an uncontaminated ground state for hadrons. The efficiency of the operators is shown by looking at the wave function of the first excited state, which has a node as a function of spatial extent of the operator.

Randall D. Kamien, David R. Nelson

In the hexagonal columnar phase of chiral polymers a bias towards cholesteric twist competes with braiding along an average direction. When the chirality is strong, screw dislocations proliferate, leading to either a tilt grain boundary phase or a new &#34;moire state&#34; with twisted bond order. Polymer trajectories in the plane perpendicular to their aver

S. Havlin, L. A. N. Amaral, S. V. Buldyrev, S. T. Harrington

We study the dynamical exponent $z$ for the directed percolation depinning (DPD) class of models for surface roughening in the presence of quenched disorder. We argue that $z$ for $(d+1)$ dimensions is equal to the exponent $d_{\rm min}$ characterizing the shortest path between two sites in an isotropic percolation cluster in $d$ dimensions. To test the argu

A. J. Bray, B. Derrida

The exponent $λ$ that describes the decay of the autocorrelation function $A(t)$ in a phase ordering system, $A(t) \sim L^{-(d-λ)}$, where $d$ is the dimension and $L$ the characteristic length scale at time $t$, is calculated exactly for the time-dependent Ginzburg-Landau equation in $d=1$. We find $λ= 0.399\,383\,5\ldots$. We also show explicitly that a sm

Alain Dasnières de Veigy, Stéphane Ouvry

The thermodynamic of particles with intermediate statistics interpolating between Bose and Fermi statistics is adressed in the simple case where there is one quantum number per particle. Such systems are essentially one-dimensional. As an illustration, one considers the anyon model restricted to the lowest Landau level of a strong magnetic field at low tempe

Johannes Richter, Sven E. Krüger, Andreas Voigt, Claudius Gros

We present a class of exactly solvable quantum spin models which consist of two Heisenberg-subsystems coupled via a long-range Lieb-Mattis interaction. The total system is exactly solvable whenever the individual subsystems are solvable and allows to study the effects of frustration. We consider (i) the antiferromagnetic linear chain and (ii) the Lieb-Mattis

Jose Abracos, Jose Gabriel Lopes

Cormack (1992) proposed a framework for pronominal anaphora resolution. Her proposal integrates focusing theory (Sidner et al.) and DRT (Kamp and Reyle). We analyzed this methodology and adjusted it to the processing of Portuguese texts. The scope of the framework was widened to cover sentences containing restrictive relative clauses and subject ellipsis. Te

Reinhold Egger, C. H. Mak

The dynamics of spin-boson systems at very low temperatures has been studied using a real-time path-integral simulation technique which combines a stochastic Monte Carlo sampling over the quantum fluctuations with an exact treatment of the quasiclassical degrees of freedoms. To a large degree, this special technique circumvents the dynamical sign problem and

Freddy Christiansen, Antonio Politi, Istituto Nazionale di Ottica, Firenze

A procedure to obtain the symbolic dynamics for conservative dynamical systems is introduced with reference to the standard map in a strongly chaotic regime. The method extends an approach previously developed for highly dissipative systems. It is based on the construction of a generating partition from homoclinic tangencies and fibers of invariant manifolds

Kim Griest

We review some recent determinations of the amount of dark matter on galactic, cluster, and large scales, noting some puzzles and their possible resolutions. We discuss the interpretation of big bang nucleosynthesis for dark matter, and then review the motivation for and basic physics of several dark matter candidates, including Machos, Wimps, axions, and ne

Mats Carlsson, Robert F. Stein

Enhanced chromospheric emission which corresponds to an outwardly increasing semiempirical temperature structure can be produced by wave motion without any increase in the mean gas temperture. Hence, the sun may not have a classical chromosphere in magnetic field free internetwork regions. Other significant differences between the properties of dynamic and s

Ezra Getzler

We study a pair of dual operads which arise in the study of moduli spaces of pointed genus 0 curves (this duality is similar to that between commutative and Lie algebras). These operads are both quadratic, and even Koszul, and arise in the theory of quantum cohomology.

Zurab Berezhiani, Enrico Nardi

In most supersymmetric models the stability of the proton is ensured by invoking R-parity. A necessary ingredient to enforce R-parity is the possibility of distinguishing the lepton superfields from the Higgs ones. This is generally achieved either by assuming different charges under some matter parity, or by assigning the superfields to different representa

Dariusz Prorok, Ludwik Turko

We consider an ideal gas of massive hadrons in thermal and chemical equilibrium. The gas expands longitudinally in an adiabatic way. This evolution for a baryonless gas reduces to a hydrodynamic expansion. Cooling process is parametrized by the sound velocity. The sound velocity is temperature dependent and is strongly influenced by hadron mass spectrum.

Bruce Allen

The transverse traceless spin-two tensor harmonics on $S^3$ and $H^3$ may be denoted by $T^{(kl)}{}_{ab}$. The index $k$ labels the (degenerate) eigenvalues of the Laplacian $\square$ and $l$ the other indices. We compute the bitensor $\sum_l T^{(kl)}{}_{ab}(x) T^{(kl)}{}_{a&#39;b&#39;}(x&#39;)^*$ where $x,x&#39;$ are distinct points on a sphere or hyperbolo

Michael Maxwell

A generate and test algorithm is described which parses a surface form into one or more lexical entries using linearly ordered phonological rules. This algorithm avoids the exponential expansion of search space which a naive parsing algorithm would face by encoding into the form being parsed the ambiguities which arise during parsing. The algorithm has been

Bjarte Kileng, Per Osland

If gluinos are light, they will be produced in electron-positron annihilation at LEP, not only by radiation in pairs off quarks and antiquarks, but also without accompanying quark and antiquark jets. We here discuss the latter process, pair production of gluinos, in a model with soft supersymmetry breaking, allowing for mixing between the squarks. In much of

H. Awata, Y. Matsuo, S. Odake, J. Shiraishi

On the basis of the collective field method, we analyze the Calogero--Sutherland model (CSM) and the Selberg--Aomoto integral, which defines, in particular case, the partition function of the matrix models. Vertex operator realizations for some of the eigenstates (the Jack polynomials) of the CSM Hamiltonian are obtained. We derive Virasoro constraint for th

Alexios P. Polychronakos

We examine a collection of particles interacting with inverse-square two-body potentials in the thermodynamic limit. We find explicit large-amplitude density waves and soliton solutions for the motion of the system. Waves can be constructed as coherent states of either solitons or phonons. Therefore, either solitons or phonons can be considered as the fundam

Satoshi Iso

We study the $c=1$ conformal field theory of a free compactified boson with radius $r=\sqrtβ$ ($β$ is an integer). The Fock space of this boson is constructed in terms of anyon vertex operators and each state is labeled by an infinite set of pseudo-momenta of filled particles in pseudo-Dirac sea. Wave function of multi anyon state is described by an eigenfun

Leonid V. Razumov, R. M. Weiner

A Quantum Field Theory formulation of Bose-Einstein Correlations is given. It contains as a special case the classical current approach. It is shown that the particle-antiparticle correlations are a general feature of Bose-Einstein Correlations and not an artifact of a certain approximation. Relations are provided through which the quantum corrections to the

Ulrich H. E. Hansmann, Yuko Okamoto

We compare a few variants of the recently proposed multicanonical method with the well known simulated annealing for the effectiveness in search of the energy global minimum of a biomolecular system. For this we study in detail Met-enkephalin, one of the simplest peptides. We show that the new method not only outperforms simulated annealing in the search of

Daijiro Suematsu, Yoshio Yamagishi

Radiative symmetry breaking is studied in a superstring-inspired supersymmetric model which is extended with a low energy extra $U(1)$ symmetry. In this model the $μ$-problem is radiatively solved in an automatic way. The right-handed neutrino can be heavy and the seesaw mechanism will produce the small neutrino mass which makes the MSW solution applicable t

Jorma Louko, Bernard F. Whiting

Kuchař has recently given a detailed analysis of the classical and quantum geometrodynamics of the Kruskal extension of the Schwarzschild black hole. In this paper we adapt Kuchař&#39;s analysis to the exterior region of a Schwarzschild black hole with a timelike boundary. The reduced Lorentzian Hamiltonian is shown to contain two independent terms, one from

Joseph Pentheroudakis, Lucy Vanderwende, Microsoft Corporation

We describe an automated method for identifying classes of morphologically related words in an on-line dictionary, and for linking individual senses in the derived form to one or more senses in the base form by means of morphological relation attributes. We also present an algorithm for computing a score reflecting the system=92s certainty in these derivatio

W. A. Atkinson, J. P. Carbotte

We calculate the density of states of a layered superconductor in which there are two layers per unit cell. One of the layers contains a d-wave pairing interaction while the other is a normal metal. The goal of this article is to understand how the d-wave behaviour of the system is modified by the coupling between the layer-types. This coupling takes the for

A. W. Sandvik, D. J. Scalapino, UC Santa Barbara

The spin-lattice relaxation rate $1/T_1$ and the spin echo decay rate $1/T_{2G}$ for the 2D Heisenberg model are calculated using quantum Monte Carlo and maximum entropy analytic continuation. The results are compared to recent experiments on La$_2$CuO$_4$, as well as predictions based on the non-linear $σ$-model.

H. Müther, A. Polls, W. H. Dickhoff

The influence of short-range correlations on the momentum and energy distribution of nucleons in nuclei is evaluated assuming a realistic meson-exchange potential for the nucleon-nucleon interaction. Using the Green-function approach the calculations are performed directly for the finite nucleus $^{16}$O avoiding the local density approximation and its refer

Emanuel Knill

Let F be a family of subsets of {1,2,...,n}. The width-degree of an element x in at least one member of F is the width of the family {U in F | x in U}. If F has maximum width-degree at most k, then F is locally k-wide. Bounds on the size of locally k-wide families of sets are established. If F is locally k-wide and centered (every U in F has an element which

D. R. Karakhanyan, R. P. Manvelyan, R. L. Mkrtchyan

The general structure of trace anomaly, suggested recently by Deser and Shwimmer, is argued to be the consequence of the Wess-Zumino consistency condition. The response of partition function on a finite Weyl transformation, which is connected with the cocycles of the Weyl group in $d=2k$ dimensions is considered, and explicit answers for $d=4,6$ are obtained

Rajesh Parwani, Harvendra Singh

The order $g^5$ contribution to the pressure of massless $g^2 ϕ^4$ theory at nonzero temperature is obtained explicitly. Lower order contributions are reconsidered and two issues leading to the optimal choice of rearranged Lagrangian for such calculations are clarified.

C. Gomez, E. Lopez

A review on topological strings and the geometry of the space of two dimensional theories. (Lectures given by C. Gomez at the Enrico Fermi Summer School, Varenna, July 1994)

Oren Bergman, Barton Zwiebach

The zero-momentum ghost-dilaton is a non-primary BRST physical state present in every bosonic closed string background. It is given by the action of the BRST operator on another state $\x$, but remains nontrivial in the semirelative BRST cohomology. When local coordinates arise from metrics we show that dilaton and $\x$ insertions compute Riemannian curvatur

Paul Langacker

The current status of gauge unification is surveyed both in the standard model and its minimal supersymmetric extension. Implications for proton decay, Yukawa unification, and the Higgs mass are described.

Paolo Nason, Matteo Palassini

We compute the effect of small-size instantons on the coefficient function of the chiral condensate in the operator product expansion of current-current correlators. Furthermore, we also compute the instanton corrections associated with four-quark and six-quark operators in the factorization approximation. We discuss the phenomenological implications of our

Prakash Mathews, V. Ravindran

We present a systematic analysis of the processes $e^+ ~e^- \rightarrow e^+ ~e^- X$ to study the polarised and unpolarised photon structure functions. The effect of target photon mass, which manifests itself as new singly polarised structure functions is studied. The physical interpretation of these structure functions in terms of hadronic components is give

Martti Raidal

Single $W$-boson production in $e^-γ$ collisions with polarized beams is investigated. Helicity amplitudes for general couplings are derived and their properties are discussed. The results are applied to the Standard Model (SM) and the left-right model. In the framework of SM the updated estimates of the measurement precision of photon anomalous coupling par

Raimo Vuopionperä

The use of the existing proton storage rings combined with electron linear accelerator as a ring-linac type electron-proton or photon-proton collider is investigated. The total CM-energy of Proton-ring and Electron-linac Collider (PRELC) is in the range of 1.0 TeV. The most important physical issues are listed and the most critical machine aspects of the PRE

Barbara Schrempp

The two-loop ``top-down&#39;&#39; renormalization group flow for the top, bottom and tau Yukawa couplings is explored in the framework of supersymmetric grand unification; reproduction of the physical bottom and tau masses is required. Instead of following the recent trend of implementing exact Yukawa coupling unification i) a search for infrared (IR) fixed

K. N. Zyablyuk

It is shown how one can construct the lagrangian of dual supergravity by means of the equations of motion derived from the superspace approach.

F. T. Hawes, K. Kusaka, A. G. Williams

Two examples of recent progress in applications of the Dyson-Schwinger equation (DSE) formalism are presented: (1) Strong coupling quantum electrodynamics in 4 dimensions (QED$_4$) is an often studied model, which is of interest both in its own right and as an abelian model of quantum chromodynamics (QCD). We present results from a study of subtractive renor

Stephen Godfrey

We study and compare the discovery potential for heavy neutral gauge bosons ($Z&#39;$) at various $e^+e^-$ and $p\stackrel{(-)}{p}$ colliders that are planned or have been proposed. Typical discovery limits are for the TEVATRON $\sim 1$ TeV, DI-TEVATRON $\sim 2$ TeV, LHC $\sim 4$ TeV, LSGNA (a 60 TeV $pp$ collider) $\sim 13$ TeV while the $e^+e^-$ discovery

Mario Pernici

A few years ago some attention has been given to a fermionic action on the lattice, with a Wilson-like term which is chirally invariant but breaks the hypercubic space-time lattice symmetry. This action describes two Dirac fields in the continuum limit, provided the coefficient $λ$ of the Wilson-like term satisfies $λ> \frac{1}{2}$. In this letter it is show

S. Abachi

We present new results on the search for the top quark in p anti-p collisions at S**(1/2) = 1.8 TeV with an integrated luminosity of 13.5 +- 1.6 pb**(-1). We have considered t anti-t production in the Standard Model using electron and muon dilepton decay channels (t anti-t -> e mu + jets, e e + jets, and mu mu + jets) and single-lepton decay channels (t anti

Douglas M. Eardley

This paper proves a theorem about the existence of an apparent horizon in general relativity, which applies equally well to vacuum configurations and matter configurations. The theorem uses the reciprocal of the surface-to-volume ratio of a region on a space slice to measure the radius of the region, and uses the minimum value $K_{\rm min}$ of certain compon

Hernando Quevedo, Roberto Sussman

We examine the consistency of the thermodynamics of irrotational and non-isentropic perfect fluids complying with matter conservation by looking at the integrability conditions of the Gibbs-Duhem relation. We show that the latter is always integrable for fluids of the following types: (a) static, (b) isentropic (admits a barotropic equation of state), (c) th

Hernando Quevedo, Roberto Sussman

We examine the consistency of the thermodynamics of the most general class of conformally flat solution with an irrotational perfect fluid source (the Stephani Universes). For the case when the isometry group has dimension $r\ge2$, the Gibbs-Duhem relation is always integrable, but if $r<2$ it is only integrable for the particular subclass (containing FRW co

Anzhong Wang, Patricio S. Letelier

The local and global properties of the Goetz thick plane domain wall space-time are studied. It is found that when the surface energy of the wall is greater than a critical value $σ_{c}$, the space-time will be closed by intermediate singularities at a finite proper distance. A model is presented in which these singularities will give rise to scalar ones whe

Anzhong Wang, Nilton O. Santos

Gravitational and massless particle radiation of straight cosmic strings with finite thickness is studied analytically. It is found that the non-linear interaction of the radiation fields emitted by a cosmic string with the ones of the string always makes the spacetime singular at the symmetry axis. The singularity is not removable and is a scalar one.

M. Ulmke, V. Janis, D. Vollhardt

We present a detailed, quantitative study of the competition between interaction- and disorder-induced effects in electronic systems. For this the Anderson-Hubbard model with diagonal disorder is investigated analytically and by Quantum Monte Carlo techniques in the limit of infinite spatial dimensions at half filling. We construct the magnetic phase diagram

N. Angelescu, S. Romano, V. A. Zagrebnov

The problem of the orientational ordering transition for lattice-gas models of liquid crystals is discussed in the low-dimensional case $d=1,2$. For isotropic short-range interactions, orientational long-range order at finite temperature is excluded for any packing of molecules on the lattice $Z^d$; on the other hand, for reflection-positive long-range isotr

Fred Cooper, John Dawson, Salman Habib, Yuval Kluger

We consider the dynamical system consisting of a quantum degree of freedom $A$ interacting with $N$ quantum oscillators described by the Lagrangian \bq L = {1\over 2}\dot{A}^2 + \sum_{i=1}^{N} \left\{{1\over 2}\dot{x}_i^2 - {1\over 2}( m^2 + e^2 A^2)x_i^2 \right\}. \eq In the limit $N \rightarrow \infty$, with $e^2 N$ fixed, the quantum fluctuations in $A$ a

C. B. Netterfield, N. Jarosik, L. Page, D. Wilkinson

We detect anisotropy in the cosmic microwave background (CMB) at degree angular scales and confirm a previous detection reported by Wollack et al. (1993). The root-mean-squared amplitude of the fluctuations is $44^{+13}_{-7} μ$K. This may be expressed as the square root of the angular power spectrum in a band of multipoles between $l_{eff}=69^{+29}_{-22}$. W

Andrew Ulmer, Ralph A. M. J. Wijers, Edward E. Fenimore

We examine the width of the gamma-ray burst luminosity function through the distribution of GRB peak fluxes as detected by the Pioneer Venus Orbiter (PVO) and the Burst and Transient Source Experiment (BATSE). The strength of the analysis is greatly enhanced by using a merged catalog of peak fluxes from both instruments with good cross-calibration of their s

Matthias Bartelmann, Ramesh Narayan

We review and discuss information on the mass distribution of galaxy clusters obtained from gravitational lensing.

Nikolaos Stergioulas, John L. Friedman

We present the first direct comparison of codes based on two different numerical methods for constructing rapidly rotating relativistic stars. A code based on the Komatsu-Eriguchi-Hachisu (KEH) method (Komatsu et al. 1989), written by Stergioulas, is compared to the Butterworth-Ipser code (BI), as modified by Friedman, Ipser and Parker. We compare models obt

Sheng-Li Tan

In this part of the series, we shall investigate Deligne-Mumford semistable reductions from the point of view of numerical invariants. As an application, we obtain two numerical criterions for a base change to be stabilizing, and for a fibration to be isotrivial. We also obtain a canonical class inequality for any fibration. Some other applications are prese

Sheng-Li Tan

In this paper, we shall prove Beauville&#39;s conjecture: if $f:S \to P^1$ is a non-trivial semistable fibration of genus g>1, then $f$ admits at least 5 singular fibers. We have also constructed an example of genus 2 with 5 singular fibers. This paper will appear in the Journal of Algebraic Geometry.

Takao Fujita

Main Result: Let $(M,L)$ be a smooth complex polarized threefold. Then the linear system $| K+tL|$ separates any two different points on $M$ for any $t\ge 6$, where $K$ is the canonical bundle of $M$. The argument in the proof is a variant of Ein-Lazarsfeld method. Although it is less powerful, it is cheaper, i.e., needs fewer pages. Unfortunately, at presen

Sergio Caracciolo, Robert G. Edwards, Andrea Pelissetto, Alan D. Sokal

We carry out a high-precision Monte Carlo simulation of the two-dimensional $O(3)$-invariant $σ$-model at correlation lengths $ξ$ up to $\sim 10^5$. Our work employs a new and powerful method for extrapolating finite-volume Monte Carlo data to infinite volume, based on finite-size-scaling theory. We discuss carefully the systematic and statistical errors in

M. Finkelberg, V. Schechtman

This paper is the first in a series. The main goal of the series is to present a geometric construction of certain remarkable tensor categories arising from quantum groups coresponding to the value of deformation parameter $q$ equal to a root of unity. In the present paper we study perverse sheaves over a complex affine space which are smooth along the strat

Damiano Anselmi

I develop a formalism for solving topological field theories explicitly, in the case when the explicit expression of the instantons is known. I solve topological Yang-Mills theory with the $k=1$ Belavin {\sl et al.} instanton and topological gravity with the Eguchi-Hanson instanton. It turns out that naively empty theories are indeed nontrivial. Many unexpec

A. Klemm, W. Lerche, S. Theisen, S. Yankielowicz

We present a first step towards generalizing the work of Seiberg and Witten on N=2 supersymmetric Yang-Mills theory to arbitrary gauge groups. Specifically, we propose a particular sequence of hyperelliptic genus $n-1$ Riemann surfaces to underly the quantum moduli space of $SU(n)$ N=2 supersymmetric gauge theory. These curves have an obvious generalization

Dragi Karevski, Gábor Palágyi, Loïc Turban

The surface critical behaviour of the semi--infinite one--dimensional quantum Ising model in a transverse field is studied in the presence of an aperiodic surface extended modulation. The perturbed couplings are distributed according to a generalized Fredholm sequence, leading to a marginal perturbation and varying surface exponents. The surface magnetic exp

Takeshi Suzuki

Without using Gabber&#39;s theorem, the finite-dimensionality of the space of conformal blocks in the WZNW-models is proved.

Charles A. Nelson

The usage of polarimetry and spin-correlation tests to determine the {\em complete Lorentz structure} of the tau lepton&#39;s charged and neutral-current couplings is reviewed. The emphasis is on tests for ``something&#39;&#39; in a $(V-A) + $ ``something&#39;&#39; structure in ${J^{Charged}}_{Lepton}$ current, so as to bound the scales $Λ$ for ``new physics

D. Makovoz, G. A. Miller

An exactly solvable model is used to investigate the assumptions behind color transparency.

J. Dobaczewski, W. Nazarewicz, T. R. Werner

The shell structure of magic nuclei far from stability is discussed in terms of the self-consistent spherical Hartree-Fock-Bogoliubov theory. In particular, the sensitivity of the shell-gap sizes and the two-neutron separation energies to the choice of particle-hole and particle-particle components of the effective interaction is investigated.

Martin Bridgeman

We define a decomposition of link projections whose pieces we call atoroidal graphs. We describe a surgery operation on these graphs and show that all atoroidal graphs can be generated by performing surgery repeatedly on a family of well known link projections. This gives a method of enumerating atoroidal graphs and hence link projections by recomposing the

M. Laczkovich, Arnold W. Miller

A function f:R -> R is approximately continuous iff it is continuous in the density topology, i.e., for any ordinary open set U the set E=f^{-1}(U) is measurable and has Lebesgue density one at each of its points. Denjoy proved that approximately continuous functions are Baire 1., i.e., pointwise For any f:R^2 -> R define f_x(y) = f^y(x) = f(x,y). A function

Walter D. Neumann, Lawrence Reeves

Let $E$ be a virtually central extension of the group $G$ by a finitely generated abelian group $A$. We show that $E$ carries a biautomatic structure if and only if $G$ has a biautomatic structure $L$ for which the cohomology class of the extension is represented by an $L$-regular cocycle. Moreover, a cohomology class is $L$-regular if some multiple of it is

A. Foerster, H. O. Girotti, P. S. Kuhn

The operator and the functional formulations of the dynamics of constrained systems are explored for determining unambiguously the quantum Hamiltonian of a nonrelativistic particle in a curved space.

F. Toppan

A covariant pseudodifferential calculus on Riemann surfaces, based on the Krichever-Novikov global picture, is presented. It allows defining scalar and matrix KP operators, together with their reductions, in higher genus. Globally defined Miura maps are considered and the arising of polynomial or rational ${\cal W}$ algebras on R.S. associated to each reduct

M. P. Grabowski, P. Mathieu

We present a detailed analysis of the structure of the conservation laws in quantum integrable chains of the XYZ-type and in the Hubbard model. With the use of the boost operator, we establish the general form of the XYZ conserved charges in terms of simple polynomials in spin variables and derive recursion relations for the relative coefficients of these po

Stephen Pinsky

In 1+1 dimensional compact QCD the zero modes of $A^+$ give the theory a non- trivial topological structure. We examine the effects of these topological structures on the confining infrared structure of the theory. We show that the ground state wavefunction of the topological excitation smears the infrared behavior sufficiently to eliminate confinement for s

Roger Dashen, Elizabeth Jenkins, Aneesh V. Manohar

The spin-flavor structure of large N baryons is described in the 1/N expansion of QCD using quark operators. The complete set of quark operator identities is obtained, and used to derive an operator reduction rule which simplifies the 1/N expansion. The operator reduction rule is applied to the axial currents, masses, magnetic moments and hyperon non-leptoni

P. H. Chankowski, Z. Płuciennik, S. Pokorski

We calculate ~$\sin^2θ(M_Z)$ ~in the MSSM in terms of ~ $α_{EM}$, ~$G_F$, ~$m_t$, ~$\tanβ$ ~and SUSY mass parameters with the same accuracy as the present calculations of ~$\sin^2θ(M_Z)$ ~in the SM. We compare the results with the standard leading logarithmic approximation used for SUSY threshold corrections and find important differences in the case of ligh