arXiv papers from September 1994

Douglas M. Norman, the DZero Collaboration

A search for first and second generation leptoquarks has been done with the D\O \ detector at Fermilab's p\={p} collider with $\sqrt{s}=1.8$ TeV. 95\% C.L. mass limits for first generation scalar leptoquarks have been recently published. The number for the total integrated luminosity used in the first generation leptoquark analysis has changed (via a change

Georg G. Raffelt

If photons had a small electric charge $Q_\gamma$ their path in the galactic magnetic field would be curved, leading to a time delay between photons of different frequency from a distant source. Cocconi's previous application of this argument led to a limit which is too restrictive by a factor of about 200; the corrected bound is $Q_\gamma/e\lapprox10^{-29}$

M. E. Bracco, M. C. Nemes

We derive simple and physically transparent expressions for the contribution of the strong interaction to one nucleon removal processes in peripheral relativistic heavy ion collisions. The coherent contribution,i.e, the excitation of a giant dipole resonance via meson exchange is shown to be negligible as well as interference between coulomb and nuclear exci

Carlos Castro

A proposal for constructing a universal nonlinear ${\hat W}_{\infty}$ algebra is made as the symmetry algebra of a rotational Killing-symmetry reduction of the nonlinear perturbations of Moyal-Integrable deformations of $D=4$ Self Dual Gravity (IDSDG). This is attained upon the construction of a nonlinear bracket based on nonlinear gauge theories associated

Thomas G. Rizzo

The existence of anomalous electric($\tilde \kappa$) and/or magnetic($\kappa$) dipole moment couplings between the heavy flavor fermions ($c,b,\tau$) and the $Z$ boson can cause significant shifts in the values of several electroweak observables currently being probed at both the SLC and LEP. Using the good agreement between existing data and the predictions

M. Kibler, P. Labastie

Preliminary results concerning non-quadratic (and non-bijective) transformations that exibit a degree of parentage with the well known Levi-Civita, Kustaanheimo-Stiefel, and Fock transformations are reported in this article. Some of the new transformations are applied to non-relativistic quantum dynamical systems in two dimensions.

M. Gr"ater, C. Wetterich

We investigate the O(N) symmetric linear $\sigma$-model in two dimensions by means of an exact nonperturbative evolution equation. The perturbative infrared divergences are absent in this formulation. We use a simple approximative solution of the flow equation which corresponds to a derivative expansion for the effective action. For N=2 this gives a good pic

J. A. Casas, J. R. Espinosa, M. Quiros

We re-examine the lower bound on the mass of the Higgs boson, $M_H$, from Standard Model vacuum stability including next-to-leading-log radiative corrections. This amounts to work with the full one-loop effective potential, $V(\phi)$, improved by two-loop RGE, and allows to keep control of the scale invariance of $V$ in a wide range of the $\phi$-field. Our

S. W. Hawking

Three illustrated lectures given by Stephen Hawking as part of a series of six lectures with Roger Penrose on the nature of space and time sponsored by Princeton University Press.

G. K"opp, D. Schaile, M. Spira, P. M. Zerwas

Leptons, quarks and gauge bosons are assumed to be pointlike particles in the Standard Model. Stringent bounds on the radii of quarks and leptons and their weak anomalous magnetic moments can be derived from the high-precision measurements at LEP and SLC. We find a model-independent bound of $R\lsim 10^{-17}cm$ for quark and lepton radii. HERA will provide c

W. Kalau

We study the Hamilton formalism for Connes-Lott models, i.e., for Yang-Mills theory in non-commutative geometry. The starting point is an associative $*$-algebra $\cA$ which is of the form $\cA=C(I,\cAs)$ where $\cAs$ is itself a associative $*$-algebra. With an appropriate choice of a k-cycle over $\cA$ it is possible to identify the time-like part of the g

J. Grundberg, T. H. Hansson

We derive an $su(1,1)$ coherent state path integral formula for a system of two one-dimensional anyons in a harmonic potential. By a change of variables we transform this integral into a coherent states path integral for a harmonic oscillator with a shifted energy. The shift is the same as the one obtained for anyons by other methods. We justify the procedur

J. Kwieciński

The QCD expectations concerning the deep inelastic lepton - hadron scattering at low $x$ and their phenomenological implications for HERA are summarised. Theoretical predictions for the structure function $F_2(x,Q^2)$ based on the leading log$1/x$ resummation are presented and compared with the results obtained from the Altarelli-Parisi equations. Theoretica

W. Dieter Heiss, Rashid G. Nazmitdinov, Stefanel Radu

A reflection-asymmetric deformed oscillator potential is analysed from the classical and quantum mechanical point of view. The connection between occurrence of shell structures and classical periodic orbits is studied using the ''removal of resonances method'' in a classical analysis. In this approximation, the effective single particle potential becomes sep

W. Dieter Heiss, Rashid G. Nazmitdinov, Stefanel Radu

The effect of an octupole term in a quadrupole deformed single particle potential is studied from the classical and quantum mechanical view point. Whereas the problem is nonintegrable, the quantum mechanical spectrum nevertheless shows some shell structure in the superdeformed prolate case for particular, yet fairly large octupole strengths; for spherical or

Martin Markl

We study algebras with a distributive law and the Koszulness of associated operads. As a corollary of our theory we prove that the homology operad of the little cubes operad is Koszul, the result which was originally proven by E. Getzler and J.D.S. Jones in their preprint "Operads, homotopy algebra, and iterated integrals for double loop spaces" using the co

M. Misiak, M. Muenz

We calculate the two-loop QCD mixing of the dimension-five flavor-changing operators that arise in the Standard Model after integrating out the $W$, $Z$ and Higgs bosons and the top-quark, i.e.~the mixing among gluonic and photonic magnetic moment operators. Our calculation completes the two-loop anomalous dimension matrix of operators that govern low energy

Hiroyuki Kawamura, Tsuneo Uematsu

We investigate the target mass effects in QCD Bjorken sum rule. The magnitude of the target mass correction is estimated in a variety of methods employing positivity bound as well as the experimental data for the asymmetry parameters. It turns out that the target mass correction is sizable at low $Q^2$ of the order of a few GeV$^2$, where the QCD correction

Matthias Neubert

We estimate the two-loop perturbative corrections to zero-recoil matrix elements of the flavour-changing currents $\bar c\,\gamma^\mu b$ and $\bar c\,\gamma^\mu\gamma_5\,b$ by calculating the terms of order $n_f\,\alpha_s^2$ and substituting the dependence on the number of flavours by the first coefficient of the $\beta$-function. Both for vector and axial v

I. Andrić, V. Bardek, L. Jonke

We consider the large-N Calogero model in the \h\ collective-field approach based on the $1/N$ expansion. The Bogomol'nyi limit appears and the corresponding equation for the semiclassical configuration gives the correct ground-state energy. Using the method of the orthogonal polynomial we find the excitation spectrum of density fluctuations around the semic

T. P. Singh, P. S. Joshi

We examine the role of the initial density and velocity distribution in the gravitational collapse of a spherical inhomogeneous dust cloud. Such a collapse is described by the Tolman-Bondi metric which has two free functions: the `mass-function' and the `energy function', which are determined by the initial density and velocity profile of the cloud. The coll

J. Klenner, A. Schäfer, W. Greiner

Diffractive meson production at HERA offers interesting possibilities to investigate diffractive processes and thus to learn something about the properties of the pomeron. The most succesful phenomenological description of the pomeron so far assumes it to couple like a $C = +1$ isoscalar photon to single quarks. This coupling leads, however, to problems for

W. J. Zakrzewski

We modify the recently proposed model of Speight and Ward to make it possess time dependent solutions. We find that for each lattice spacing and for each velocity of the sine Gordon kink we can find a modification of the model for which this kink is a solution. We find that this model has really 3 ``kink-like" solutions; the original kink, the static kink an

A. A. Gvozdev, N. V. Mikheev, L. A. Vassilevskaya

A brief overview of the recent measurements of the branching ratio of the rare $K_L^0 \to \mu^+ \mu^-$ decay in the context of their agreement with the Standard Model (SM) is given. It is shown that KEK result well correlates with the SM and B-physics, whereas the BNL results are in conflict with the SM with the heavy top quark.

A. Ya. Parkhomenko, A. D. Smirnov

The decay of heavy orthoquarkonium into quark-antiquark pair and two gluons is considered. The differential probability of the decay in the tree approximation is calculated and the final quark mass influence on the quark and gluon distribution functions is studied. It is shown that the collinear strengthening of the bottomonium decay probability takes place

A. D. Smirnov

A minimal extension of the Standard Model containing the four-color quark-lepton symmetry is discussed. Some features of an additional $Z'$-boson originated from this symmetry are investigated and the limits on $m_{Z'}$ from the current TRISTAN data and the possible limits on $m_{Z'}$ from the future LEP200 collider are obtained.

A. A. Gvozdev, N. V. Mikheev, L. A. Vassilevskaya

In the framework of the Standard Model with lepton mixing the radiative decay $\nu_i \rightarrow \nu_j \gamma$ of a neutrino of high ($E_\nu \sim 100 \, GeV$) and super-high ($E_\nu \ge 1 \, TeV$) energy is investigated in the Coulomb field of a nucleus. Estimates of the decay probability and ``decay cross-section'' for neutrinos of these energies in the ele

A. Mironov

This paper is a brief review of recent results on the concept of ``generalized $\tau$-function'', defined as a generating function of all the matrix elements in a given highest-weight representation of a universal enveloping algebra ${\cal G}$. Despite the differences from the particular case of conventional $\tau$-functions of integrable (KP and Toda lattic

Ph. Blanchard, A. Jadczyk

The standard formalism of quantum theory is enhanced and definite meaning is given to the concepts of experiment, measurement and event. Within this approach one obtains a uniquely defined piecewise deterministic algorithm generating quantum jumps, classical events and histories of single quantum objects. The wave-function Monte Carlo method of Quantum Optic

I. A. Korchemskaya, G. P. Korchemsky

We consider elastic quark-quark scattering at high energy and fixed transferred momentum. Performing factorization of soft gluon exchanges into Wilson line expectation value we find that there is one-to-one correspondence between high energy asymptotics in QCD and renormalization properties of the so called cross singularities of Wilson lines. Using this rel

Yair Minsky

We consider a geometric property of the closest-points projection to a geodesic in Teichm\"uller space: the projection is called contracting if arbitrarily large balls away from the geodesic project to sets of bounded diameter. (This property always holds in negatively curved spaces.) It is shown here to hold if and only if the geodesic is precompact, i.e. i

David H. Weinberg

I outline the connections between some of the most widely used statistical measures of galaxy clustering and the fundamental issues in the theory of structure formation. I devote particular attention to the problem of biasing, i.e. to a possible difference between the distribution of galaxies and the distribution of mass. Using numerical experiments, I show

P. A. Rikvold, M. Gamboa-Aldeco, J. Zhang, M. Han

We present two recent applications of lattice-gas modeling techniques to electrochemical adsorption on catalytically active metal substrates: urea on Pt(100) and (bi)sulfate on Rh(111). Both involve the specific adsorption of small molecules or ions on well-characterized single-crystal electrodes, and they provide a particularly good fit between the adsorbat

K. G. Chetyrkin, J. H. Kühn

A systematic theoretical evaluation of the cross section for hadron production in electron-positron collisions in the energy range just below the $B$ meson threshold is presented which includes charm and bottom mass effects and is accurate to order $\as^3$. The corresponding measurement in the energy region several $GeV$ above the threshold is also discussed

Greg L. Bryan, Anatoly Klypin, Chris Loken, Michael L. Norman

We present the first self-consistently computed results on the evolution of X-ray properties of galaxy clusters in a Cold + Hot Dark Matter (CHDM) model. We have performed a hydrodynamic plus N-body simulation for the COBE-compatible CHDM model with standard mass components: Omega(hot) = 0.3, Omega(cold) = 0.6 and Omega(baryon) = 0.1 (h = 0.5). In contrast w

Serban Protopopescu

We have searched for production of t-tbar pairs in p-pbar interactions at 1.8 TeV center-of-mass energy at the FNAL Tevatron collider. The search assumes standard model decay for top quark into W + b quark. We observe in e+jet and mu+jet final states a small, not statistically significant, excess above the background estimated by two different methods. The r

Joao M. Soares

The branching ratios for the hadronic B-meson weak decays B -> J/psi K and B -> D pi are used to extract the size of the ``non-factorizable'' terms in the decay amplitudes. It is pointed out that the solutions are not uniquely determined. In the B -> J/psi K case, a 2-fold ambiguity can be removed by analyzing the contribution of this decay to B -> K l+ l-.

P. D. Grannis

We review the search for the top quark conducted by the D-Zero collaboration using data from the Fermilab pbar-p collider. Based upon a preliminary analysis of an integrated luminosity of about 13.5 pb-1, we have searched for t-tbar production and decay in the experimental channels involving a pair of dileptons (electron or muon) plus jets, or single leptons

Guido Nolte, Jutta Kunz

We apply the gradient approach to obtain a path over the sphaleron barrier and to demonstrate the fermionic level crossing phenomenon. Neglecting the mixing angle dependence and assuming that the fermions of a doublet are degenerate in mass we employ spherically symmetric ans\"atze for the fields. The gradient path over the barrier is smooth, even for large

Cumrun Vafa, Edward Witten

We consider the interpretation in classical geometry of conformal field theories constructed from orbifolds with discrete torsion. In examples we can analyze, these spacetimes contain ``stringy regions'' that from a classical point of view are singularities that are to be neither resolved nor blown up. Some of these models also give particularly simple and c

D. M. Gitman, A. E. Goncalves, I. V. Tyutin

A new pseudoclassical model to describe Weyl particles is proposed. Different ways of its quantization are presented. They all lead to the theory of Weyl particle; namely, the massless Dirac equation and the Weyl condition are reproduced. In contrast with models discussed previously, this one admits both the Dirac quantization and quasicanonical quantization

Rajendran Raja

We present preliminary results for the search for the top quark in D-Zero in the electron + jets channel where one of the b quark jets is tagged by means of a soft muon, using 13.5 pb-1 of data. Standard model decay modes for the top quark are assumed. We present the resulting top cross section and error as a function of top mass using this channel combined

George Lavrelashvili, Dieter Maison

The aim of the present letter is to critically review the stability of the Bartnik-McKinnon solutions of the Einstein-Yang-Mills theory. The stability question was already studied by several authors, but there seems to be some confusion about the nature and the number of unstable modes. We suggest to distinguish two different kind of instabilities, which we

K. -P. Marzlin

The general construction of extended refrence frames for noninertial observers in flat space is studied. It is shown that, if the observer moves inertially before and after an arbitrary acceleration and rotation, the region where reference frames can coincide with an inertial system is bounded for final velocities exceeding 0.6 c.

E. Bergshoeff, H. J. Boonstra, M. de Roo

We discuss a realization of the bosonic string as a noncritical $W_3$-string. The relevant noncritical $W_3$-string is characterized by a Liouville sector which is restricted to a (non-unitary) $(3,2)$ $W_3$ minimal model with central charge contribution $c_l = - 2$. Furthermore, the matter sector of this $W_3$-string contains $26$ free scalars which realize

F. De Fazio

We use a QCD relativistic potential model to compute the strong coupling constant $g$ appearing in the effective Lagrangian which describes the interaction of $0^-$ and $1^-$ $\bar q Q$ states with soft pions in the limit $m_Q \to \infty$. We compare our results with other approaches; in particular, in the non relativistic limit, we are able to reproduce the

G. Ecker, U. -G. Meissner

We discuss the meaning of low-energy theorems (LETs) in the framework of the effective field theory of the standard model. Particular emphasis is put on the LET for neutral pion photoproduction off nucleons at threshold. The seemingly controversial situation surrounding this LET is clarified.

Wenbin Yu, David G. Stroud

We calculate the dynamical response of two-layer Josephson arrays to a bias current applied into only one layer (primary layer), in a perpendicular magnetic field. The pancake vortices in the two layers sometimes form into flux lines which move as a unit under the influence of the bias current. The lines break apart into independent pancakes in sufficiently

Franz-Josef Elmer

A damped chain of particles with harmonic nearest-neighbor interactions in a spatially periodic, piecewise harmonic potential (Frenkel-Kontorova model) is studied numerically. One end of the chain is pulled slowly which acts as a weak driving mechanism. The numerical study was performed in the limit of infinitely weak driving. The model exhibits avalanches s

Yong-Wan Kim, Young-Jai Park, Kee Yong Kim, Yongduk Kim

We quantize the self-dual massive theory by using the Batalin-Tyutin Hamiltonian method, which systematically embeds second class constraint system into first class one in the extended phase space by introducing the new fields. Through this analysis we obtain simultaneously the St\"uckelberg scalar term related to the explicit gauge-breaking effect and the n

Nick Manton, Paul Sutcliffe

We describe how an approximation to the minimal energy Skyrme crystal can be obtained from the holonomy of a Yang-Mills instanton. The appropriate instanton is twisted on a four-torus and has instanton number equal to one half. It generates a Skyrme field with the correct topological and symmetry properties of the crystal. An explicit solution for the instan

Paul Sutcliffe

We describe how the procedure of calculating approximate solitons from instanton holonomies may be extended to the case of soliton crystals. It is shown how sine-Gordon kink chains may be obtained from CP1 instantons on a torus. These kink chains turn out to be remarkably accurate approximations to the true solutions. Some remarks on the relevance of this wo

H. H. Soleng, O. Gron

In four dimensions a Gauss-Bonnet term in the action corre- sponds to a total derivative, and it does not contribute to the classical equations of motion. For higher-dimensional geometries this term has the interesting property (shared with other dimensionally continued Euler densities) that when the action is varied with respect to the metric, it gives rise

E. Bagan, Patricia Ball, V. M. Braun, P. Gosdzinsky

We reconsider the prediction of the semileptonic branching ratio of B mesons, using a recent calculation of the radiative corrections with account for finite quark masses in nonleptonic decays and taking into account 1/m_b^2 corrections. For the semileptonic branching ratio we obtain B_SL =(11.8\pm 1.6)% using pole quark masses and B_SL = (11.0\pm 1.9)% usin

M. Ferlini, V. R. Manfredi, G. Maino

To show the existence of precursor phenomena of the transition order$\ to$chaos in atomic nuclei a simple analysis has been made, based on a recent criterion proposed by Pavli\-chenkov. The basic idea is that nonlinear effects in rotational bands should lead to bifurcation, which qualitatively changes the spectrum for one of the nuclear excitation branches.

B. V. Karpov

In this paper we deal with semistable sheaves which can be represented as the cokernel of an injective (or as the kernel of a surjective) morphism $E_1\otimes\CC^m\longrightarrow E_2\otimes\CC^n$ , where $E_1$ and $E_2$ are exceptional bundles. To each such a sheaf we assign the linear map $\CC^m\otimes\hom^*(E_1,E_2)\longrightarrow \CC^n$. We obtain suffici

G. Aldazabal, I. Allekotte, E. Andres, Carmen Nunez

Moddings by cyclic permutation symmetries are performed in 4-dimensional strings, built up from N=2 coset models of the type $CP_m=SU(m+1)/SU(m)\times U(1)$. For some exemplifying cases, the massless chiral and antichiral states of $E_6$ are computed. The extent of the equivalence between different conformal invariant theories which possess equal chiral ring

Y. Kazama, Y. Satoh, A. Tsuchiya

A large class of solvable models of dilaton gravity in two space-time dimensions, capable of describing black hole geometry, are analyzed in a unified way as non-linear sigma models possessing a special symmetry. This symmetry, which can be neatly formulated in the target-space-covariant manner, allows one to decompose the non-linearly interacting dilaton-gr

G. Ellingsrud, S. A. Strømme

This paper has been rendered obsolete by our newer eprint alg-geom/9411005 "Bott's formula and enumerative geometry", which is a considerably expanded version of the same paper, in spite of the change of titles. Please download alg-geom/9411005 instead, and update possible references.

M. C. Bento, O. Bertolami

We establish the main features of homogeneous and isotropic dilaton, metric and Yang-Mills configurations in a cosmological framework. We identify a new energy exchange term between the dilaton and the Yang-Mills field which may lead to a possible solution to the Polonyi problem in 4-dimensional string models.

F. R. Ferraro, F. Fusi Pecci, V. Testa, L. Greggio

We report the results of the observations in the JHK bands of 12 globular clusters in the LMC, and present CMDs down to K=16 for about 450 stars. We merge the data with the BV ones presented in paper I and use the merged data to study the evolution of integrated magnitudes and colours of SSPs. We find that the AGB contributes about 60 percent of integrated c

C. E. Corsi, R. Buonanno, F. Fusi Pecci, F. R. Ferraro

We present BV CCD-data for 11 intermediate-age LMC clusters; the main conclusions are: 1. in the (V_to, V_cl,m) and (V-to, (V_to-V_cl,m)) planes the models yield a good overall description of the data; 2. with the current sample, it is impossible to firmly choose between "classical" and "overshooting" models; 3. the separation in colour between the MS band a

Stjepan Meljanac, Ante Perica

Generalized quons interpolating between Bose, Fermi, para-Bose, para-Fermi, and anyonic statistics are proposed. They follow from the R-matrix approach to deformed associative algebras. It is proved that generalized quons have the same main properties as quons. A new result for the number operator is presented and some physical features of generalized quons

P. Colangelo, F. De Fazio, P. Santorelli

We use three-point function QCD sum rules to calculate the form factor $A_0(q^2)$ appearing in the matrix element of the flavour-changing axial current between the $D (B)$ state and a vector meson state. We describe the role of this form factor in nonleptonic $D (B) \to P V$ decays and analyze the light $SU(3)_F$ symmetry breaking effects. We also discuss a

S. Bertolini, J. O. Eeg, M. Fabbrichesi

We study the $CP$-violating, $|\Delta S| =1$ parameter $\varepsilon '/\varepsilon$ by computing the hadronic matrix elements in the chiral quark model. We estimate the coefficients of the next-to-leading order terms in the chiral expansion that correspond to the operators $Q_6$ and $Q_{11}$. We consider the impact of these corrections on the value of $\varep

A. Nyffeler, A. Schenk

The low energy structure of a theory containing light and heavy particle species which are separated by a mass gap can adequately be described by an effective theory which contains only the light particles. In this work we present a thorough analysis of the effective field theory of the linear $O(N)$ sigma model in the spontaneously broken phase. In particul

Masashi Chiba, Yuzuru Yoshii

We propose a method of distance determination based on the internal structure and dynamics of disk galaxies. The method relies on the universal luminosity profile of a stellar disk represented by an exponential law. Calibrating nearby galaxies with known distances, it is found that the scale length of the disk is tightly correlated with the specific combinat

Igor A. Bandos, Aleksey Yu. Nurmagambetov Dmitrij P. Sorokin, Dmitrij V. Volkov

Considered is a worldsheet supersymmetric generalization of the D=3 Ferber--Schirafuji twistor--superparticle action.

K. Z. Stanek

We propose a new method that can be used to constrain the properties of the Galactic bar (bulge). If the majority of the lensing objects are in the Galactic bar, then we predict a systematic offset in the apparent magnitude between lensed stars and all observed stars. Using OGLE color-magnitude diagram data we model this effect in the region of the diagram d

Darwin Chang, W. -Y. Keung

We present a simple model in which CP symmetry is spontaneously broken only after the radiative corrections are taken into account. The model includes two Higgs-boson doublets and two right-handed singlet neutrinos which induce the necessary non-hermitian interaction. To evade the Georgi-Pais theorem, some fine-tuning of coupling constants is necessary. Howe

Xiangdong Shi

The age of globular clusters inferred from observations depends sensitively on assumptions such as the initial helium abundance and the mass loss rate. A high helium abundance (e.g., $Y\approx$0.28), as well as an inclusion of helium diffusion and oxygen-enhancement in stellar models, can lower the current age estimate for metal-poor globular clusters from 1

Timothy Banks, R. J. Dodd, D. J. Sullivan

Statistical moment-based ellipse fitting was performed on observations of Large Magellanic Cloud clusters, confirming that trends are evident in their position angles and ellipticities, as had been reported in the literature. Artificial cluster images with known parameters were generated, and subjected to the same analysis techniques, revealing apparent tren

Hongguang Bi, Gerhard Boerner

(\rl = Richardson-Lucy) We propose a simulation-based bootstrap method to access global significance levels of deconvolution models in the \rl and other iterative restoration algorithms that converge locally. These significance levels allow one to check at each iterative step how good the model is and when iterations can be stopped. Adding more iterations in

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

Atmospheric extinction in the V passband at Mount John University Observatory, New Zealand, from 1987-94 is presented and the effect of the 1991 Mount Pinatubo volcanic eruption is discussed.

Chris Mihos, Lars Hernquist

We use numerical models which include star formation to analyze the mass profiles of remnants formed by mergers of disk galaxies. During a merger, dissipation in gas and ensuing star formation leave behind a dense stellar core in the remnant. Rather than joining smoothly onto a de Vaucouleurs profile, the starburst population leads to a sharp break in the su

Simon L. Morris

The origin and evolution of structure in the Universe is one of the major questions occupying astronomers today. An understanding of the Lyalpha absorbers seen in QSO spectra is an important part of this program since such absorbers can be traced back to very high redshifts. Their mere existence places constraints on the physical state of the intergalactic m

G. A. Drukier

This is the second of two papers presenting a detailed examination of Fokker-Planck models for the globular cluster NGC 6397 and is concerned with extracting information on the cluster from the models. The models give a current cluster mass of $6.6\pm 0.5\times 10^4 \Msolar$ of which about 2500 \Msolar\ is in neutron stars. This mass gives a $V$-band mass-to

G. A. Drukier

This is the first of two papers presenting a detailed examination of Fokker-Planck models for the globular cluster NGC 6397. I show that these models provide a good match to observations of the surface density profile, mass functions at three radii and the velocity dispersion profile. The constraint of requiring the best matches to the mass functions and sur

D. V. Khveshchenko

We discuss an approach to higher dimensional bosonization of interacting fermion s based on a picture of fluctuating Fermi surface. Compared with the linearized"constructive" approach developed in Refs.[9-11] this method allows an account of the Fermi surface curvature due to nongaussian terms in the bosonized Lagrangian. On the basis of this description we

Mario Mateo, A. Udalski, M. Szymanski, J. Kaluzny

We present deep CCD photometry of a field in the newly discovered dwarf spheroidal galaxy in Sagittarius (hereafter Sgr), and of a nearby control field. These data (totaling ~3.5 hrs exposure time in V and I) were used to produce color-magnitude (CM) diagrams reaching I ~ 22.3 in both fields. After statistically removing the field-stars from the CM diagram w

D. L. Stein, C. M. Newman

We study the nature and mechanisms of broken ergodicity (BE) in specific random walk models corresponding to diffusion on random potential surfaces, in both one and high dimension. Using both rigorous results and nonrigorous methods, we confirm several aspects of the standard BE picture and show that others apply in one dimension, but need to be modified in

P. Fendley, F. Lesage, H. Saleur

The general one-dimensional ``log-sine'' gas is defined by restricting the positive and negative charges of a two-dimensional Coulomb gas to live on a circle. Depending on charge constraints, this problem is equivalent to different boundary field theories. We study the electrically neutral case, which is equivalent to a two-dimensional free boson with an imp

Arkady Kheyfets, Warner A. Miller

We present here an application of a new quantization scheme. We quantize the Taub cosmology by quantizing only the anisotropy parameter $\beta$ and imposing the super-Hamiltonian constraint as an expectation-value equation to recover the relationship between the scale factor $\Omega$ and the time $t$. This approach appears to avoid the problem of time. (Pape

Henry C. Ferguson, Bruno Binggeli

Dwarf elliptical (dE) galaxies, with blue absolute magnitudes typically fainter than $M_B = -16$, are the most numerous type of galaxy in the nearby universe. Tremendous advances have been made over the past several years in delineating the properties of both Local Group satellite dE's and the large dE populations of nearby clusters. We review some of these

Eric Braaten

The free energy of a nonabelian gauge theory at high temperature $T$ can be calculated to order $g^5$ using resummed perturbation theory, but the method breaks down at order $g^6$. A new method is developed for calculating the free energy to arbitrarily high accuracy in the high temperature limit. It involves the construction of a sequence of two effective f

George M. Frichter, Douglas W. McKay, John P. Ralston

New structure function data at small Bjorken $x$ from HERA are used along with next-to-leading order QCD evolution to predict a cross section for charged-current interactions of ultrahigh energy neutrinos with nucleons. This new result is over twice the size of previous estimates and has important implications for cosmic ray experiments now underway as well

B. Basu-Mallick, P. Ramadevi

Yang-Baxterising a braid group representation associated with multideformed version of $GL_{q}(N)$ quantum group and taking the corresponding $q\rightarrow 1$ limit, we obtain a rational $R$-matrix which depends on $\left ( 1+ {N(N-1) \over 2} \right ) $ number of deformation parameters. By using such rational $R$-matrix subsequently we construct a multipara

Clifford V. Johnson, Robert C. Myers

In the low-energy limit, string theory has two remarkable symmetries, O(d,d+p) and SL(2,R). We illustrate the use of these transformations as techniques to generate new solutions by applying them to the Taub--NUT metric.

Suraj N. Gupta, James M. Johnson

We have investigated the spectra of light-heavy quarkonia with the use of a quantum-chromodynamic potential model which is similar to that used earlier for the heavy quarkonia. An essential feature of our treatment is the inclusion of the one-loop radiative corrections to the quark-antiquark potential, which contribute significantly to the spin-splittings am

Neil Marcus

We construct the U(N) spinning particle theories, which describe particles moving on Kahler spaces. These particles have the same relation to the N=2 string as usual spinning particles have to the NSR string. We find the restrictions on the target space of the theories coming from supersymmetry and from global anomalies. Finally, we show that the partition f

A. Baldassarri, L. F. Cugliandolo, J. Kurchan, G. Parisi

We show that the dynamical order parameters can be reexpressed in terms of the distribution of the staggered auto-correlation and response functions. We calculate these distributions for the out of equilibrium dynamics of the Sherrington-Kirpatrick model at long times. The results suggest that the landscape this model visits at different long times in an out

R. A. Hyman, M. Wallin, M. P. A. Fisher, S. M. Girvin

We have performed Monte Carlo simulations to determine current--voltage characteristics of two different vortex glass models in two dimensions. The results confirm the conclusions of earlier studies that there is a transition at $T=0$. In addition we find that, as $T\to 0$, the linear resistance vanishes exponentially, and the current scale, $J_{nl}$, where

A. V. Smilga

Pure Yang-Mills theory at high temperature is considered. We show that no distinct $Z_N$- phases separated by domain walls do exist in the physical Minkowski space. That means the absense of the spontaneous breaking of $Z_N$- symmetry in the physical meaning of this word.

A. Klümper, S. I. Matveenko, J. Zittartz

New exactly solvable nineteen vertex models and related quantum spin-1 chains are solved. Partition functions, excitation energies, correlation lengths, and critical exponents are calculated. It is argued that one of the non-critical Hamiltonians is a realization of an integrable Haldane system. The finite-size spectra of the critical Hamiltonians deviate in

Marc Dymetman, Julie Brousseau, George Foster, Pierre Isabelle

Professional translators often dictate their translations orally and have them typed afterwards. The TransTalk project aims at automating the second part of this process. Its originality as a dictation system lies in the fact that both the acoustic signal produced by the translator and the source text under translation are made available to the system. Proba

Zhenping Li, Yubing Dong, Weihsing Ma

A longitudinal transition operator that satisfies the gauge invariance requirement is introduced in constituent quark model. The corresponding longitudinal transitions between the nucleon and baryon resonances are calculated. We show that the study of the longitudinal coupling plays an important role in understanding the structure of baryons.

Andrew R Liddle, David H Lyth

With the imminent promise of constraints on the epoch of reionization from observations of microwave background anisotropies, the question of whether or not the standard Cold Dark Matter (CDM) model permits early reionization has been subjected to detailed investigation by various authors, with the conclusion that reionization may occur at quite high redshif

S. Graffi, V. R. Manfredi, L. Salasnich

A test on the numerical accuracy of the semiclassical approximation as a function of the principal quantum number has been performed for the Pullen--Edmonds model, a two--dimensional, non--integrable, scaling invariant perturbation of the resonant harmonic oscillator. A perturbative interpretation is obtained of the recently observed phenomenon of the accura

Andreas Cap, Jan Slovak

Let $E_1,\dots ,E_k$ and $E$ be natural vector bundles defined over the category $\Cal Mf_m^+$ of smooth oriented $m$--dimensional manifolds and orientation preserving local diffeomorphisms, with $m\geq 2$. Let $M$ be an object of $\Cal Mf_m^+$ which is connected. We give a complete classification of all separately continuous $k$--linear operators $D\:\Ga _c

J. A. de Azcarraga, P. P. Kulish, F. Rodenas

Reflection and braid equations for rank two $q$-tensors are derived from the covariance properties of quantum vectors by using the $R$-matrix formalism.