January 1996 arXiv papers — page 5

Hiroyuki Kobayashi, Izumi Tsutsui

We study the quantum mechanical Liouville model with attractive potential which is obtained by Hamiltonian symmetry reduction from the system of a free particle on $SL(2, \Real)$. The classical reduced system consists of a pair of Liouville subsystems which are `glued together' in such a way that the singularity of the Hamiltonian flow is regularized. It

Kazuo Ghoroku

We have examined the coupled system of the dilaton gravity and the $CP^{N-1}$ theory known as a model of the confinement of massive scalar quarks. After the quantization of the system, we could see the quantum effect of the gravitation on the coupling constant of $CP^{N-1}$ model and how the coupling constant of dynamically induced gauge field changes near t

Thomas Appelquist, Nick Evans, Stephen B. Selipsky

Extended technicolor (ETC) theories typically require ETC gauge bosons lighter than of order 1 TeV, to perturbatively generate the $t$ quark mass. We point out that explicit models of $t-b$ mass splitting also typically contain additional TeV scale ETC gauge bosons transforming in the {\it adjoint} of technicolor, leading to large weak-isospin-breaking effec

Denis Pollney, Peter Musgrave, Kevin Santosuosso, Kayll Lake

We examine the relative performance of algorithms for the calculation of curvature in spacetime. The classical coordinate component method is compared to two distinct versions of the Newman-Penrose tetrad approach for a variety of spacetimes, and distinct coordinates and tetrads for a given spacetime. Within the system GRTensorII, we find that there is no si

Sukanta Bose, Leonard Parker, Yoav Peleg

Studying two-dimensional evaporating dilatonic black holes, we show that the semiclassical approximation, based on the background field approach, is valid everywhere in regions of weak curvature (including the horizon), as long as one takes into account the effects of back-reaction of the Hawking radiation on the background geometry.

Paul C. W. Davies, Tevian Dray, Corinne A. Manogue

We derive conditions for rotating particle detectors to respond in a variety of bounded spacetimes and compare the results with the folklore that particle detectors do not respond in the vacuum state appropriate to their motion. Applications involving possible violations of the second law of thermodynamics are briefly addressed.

Luis P. Chimento, Alejandro S. Jakubi

The behavior near the singularity of an isotropic, homogeneous cosmological model with a viscous fluid source is investigated. This turns out to be a relaxation dominated regime. Full extended irreversible thermodynamics is used, and comparison with results of the truncated theory is made. New singular behaviors are found and it is shown that a relaxation do

S. Liberati

In this work some proposals for black hole entropy interpretation are exposed and investigated. In particular I will firstly consider the so called ``entanglement entropy" interpretation, in the framework of the brick wall model, and the divergence problem arising in the one loop calculations of various thermodynamical quantities, like entropy, internal

M. J. Howard, G. T. Barkema

We study theoretically and numerically the effects of the linear velocity field ${\bf v}=v_0y{\bf\hat x}$ on the irreversible reaction $A+B\rightarrow\emptyset$. Assuming homogeneous initial conditions for the two species, with equal initial densities, we demonstrate the presence of a crossover time $t_c\sim v_0^{-1}$. For $t\ll v_0^{-1}$, the kinetics are u

G. T. Barkema, G. M. Schütz

We present quantitative results for the drift velocity of a polymer in a gel if a force (e.g. through an electric or magnetic field) acts on a tag, attached to one of its ends. This is done by introducing a modification of the Rubinstein-Duke model for electrophoresis of DNA. We analyze this modified model with exact and Monte Carlo calculations. Tagged magn

G. T. Barkema, M. J. Howard, J. L. Cardy

We study theoretically and numerically the steady state diffusion controlled reaction $A+B\rightarrow\emptyset$, where currents $J$ of $A$ and $B$ particles are applied at opposite boundaries. For a reaction rate $λ$, and equal diffusion constants $D$, we find that when $λJ^{-1/2} D^{-1/2}\ll 1$ the reaction front is well described by mean field theory. Howe

Yacov Kantor, Mehran Kardar

We consider polymers in which M randomly selected pairs of monomers are restricted to be in contact. Analytical arguments and numerical simulations show that an ideal (Gaussian) chain of N monomers remains expanded as long as M<<N. This result is inconsistent with results obtained from free energy considerations by Brygelson and Thirumalai (PRL76, 542 (1996)

M. E. Simón, A. A. Aligia, C. D. Batista, E. R. Gagliano

We study the electronic excitations near the charge-transfer gap in insulating CuO$_2$ planes, starting from a six-band model which includes $% p_π$ and $d_{xy}$ orbitals and Cu-O nearest-neighbor repulsion $U_{pd}$. While the low lying electronic excitations in the doped system are well described by a modified $t-J$ model, the excitonic states of the insula

Luca Salasnich, Marko Robnik

We study the semiclassical behaviour of a two--dimensional nonintegrable system. In particular we analyze the question of quantum corrections to the semiclassical quantization obtaining up to the second order of perturbation theory an explicit analytical formula for the energy levels, which is the usual semiclassical one plus quantum corrections. We compare

Jane C. Charlton, Christopher W. Churchill

We challenge the conventional view that the majority of MgII/Lyman limit absorbers are extended halos of galaxies comprised of ``clouds&#39;&#39; with near-unity covering factor. The gaseous disks of spiral galaxies are known to extend to large radii and likely contribute a significant cross-section for absorption. We perform a Monte-Carlo survey of QSO fiel

Heino Falcke, Kris Davidson, Karl-Heinz Hofmann, Gerd Weigelt

With our new speckle imaging polarimeter we have obtained first polarimetric images with sub-arcsecond resolution of the Luminous Blue Variable eta Carinae in the Halpha line. The polarization patterns at the 3&#39;&#39; scale match well earlier conventional imaging photometry and can be interpreted as Mie scattering. In centered long-exposure images we dete

Stephen E. Zepf

Globular cluster systems provide valuable fossil records of the formation history of their parent galaxies. This review specifically concentrates on using color distributions of the globular cluster systems of elliptical galaxies to distinguish between competing models for the formation of these galaxies. The observational requirements for testing various fo

David S. P. Dearborn, Gary Steigman, Monica Tosi

New stellar models which track the production and destruction of $^3$He (and D) have been evolved for a range of stellar masses $(0.65\leq M/M_{\odot}\leq 100)$, metallicities $(0.01 \leq Z/Z_{\odot} \leq 1)$ and initial (main sequence) $^3$He mass fractions $(10^{-5} \leq X_{3,MS} \leq 10^{-3})$. Armed with the $^3$He yields from these stellar models we hav

Xingming Chen

Accretion disk instabilities are briefly reviewed. Some details are given to the short-wavelength thermal instabilities and the convective instabilities. Time-dependent calculations of two-dimensional advection-dominated accretion flows are presented.

Marek A. Abramowicz, Andrei M. Beloborodov, Xingming Chen, Igor V. Igumenshchev

A simple re-scaling of velocities calculated from the Paczy{ń}ski \& Wiita (1980) pseudo-Newtonian potential makes them consistent with special relativity and greatly improves the agreement with the exact relativistic calculations. The improvement is relevant in calculations of the Doppler effect, spectra and radiation transfer which all involve effects of s

Pedro Avelino

We study the efficiency of genus statistics in differentiating between different models of structure formation. Simple models which reproduce the salient features of the structure seeded by topological defects are examined. We consider accretion onto static point masses, modeling slow-moving cosmic string loops or other primordial point-like sources. Filamen

Eelco van Kampen

A complete catalogue of galaxy cluster models can be used to constrain cosmological parameters like $σ_8$, the amplitude of the initial density fluctuation spectrum. We focus here on two strong lensing statistics for clusters of galaxies: the fraction of rich Abell clusters that are critical to lensing, and the abundance of arcs in such clusters, especially

Leslie E. Kuchinski, Donald M. Terndrup

We present JHK surface photometry of 15 highly inclined, late-type (Sab-Sc) spirals and investigate the quantitative effects of dust extinction. Using the (J - H, H - K) two-color diagram, we compare the color changes along the minor axis of each galaxy to the predictions from different models of radiative transfer. Models in which scattering effects are sig

Gillian Wilson, Shaun Cole, Carlos S. Frenk

The morphology of galaxy clusters reflects the epoch at which they formed and hence depends on the value of the mean cosmological density, Omega. Recent studies have shown that the distribution of dark matter in clusters can be mapped from analysis of the small distortions in the shapes of background galaxies induced by weak gravitational lensing in the clus

Arnon Dar

The predictions of an improved standard solar model are compared with the observations of the four solar neutrino experiments. The improved model includes premain sequence evolution, element diffusion, partial ionization effects, and all the possible nuclear reactions between the main elements. It uses updated values for the initial solar element abundances,

Sheldon Katz, David R. Morrison, M. Ronen Plesser

We show how enhanced gauge symmetry in type II string theory compactified on a Calabi--Yau threefold arises from singularities in the geometry of the target space. When the target space of the type IIA string acquires a genus $g$ curve $C$ of $A_{N-1}$ singularities, we find that an $SU(N)$ gauge theory with $g$ adjoint hypermultiplets appears at the singula

A. A. Tseytlin

The supersymmetric action of type IIA D=10 superstring in N=2a, D=10 supergravity background can be derived by double dimensional reduction of the action of supermembrane coupled to D=11 supergravity. We demonstrate that the background Ramond-Ramond fields appear in the resulting superstring action with an extra factor of exponential of the dilaton.

Per Elmfors, Benny Lautrup, Bo-Sture Skagerstam

The micromaser possesses a variety of dynamical phase transitions parametrized by the flux of atoms and the time-of-flight of the atom within the cavity. We discuss how these phases may be revealed to an observer outside the cavity using the long-time correlation length in the atomic beam. Some of the phase transitions are not reflected in the average excita

Thomas Kerler

We study the relations between the invariants $τ_{RT}$, $τ_{HKR}$, and $τ_L$ of Reshetikhin-Turaev, Hennings-Kauffman-Radford, and Lyubashenko, respectively. In particular, we discuss explicitly how $τ_L$ specializes to $τ_{RT}$ for semisimple categories and to $τ_{HKR}$ for Tannakian categories. We give arguments for that $τ_L$ is the most general invariant

Adriano Barenco, Artur Ekert, Kalle-Antti Suominen, Päivi Törmä

We discuss the advantages of using the approximate quantum Fourier transform (AQFT) in algorithms which involve periodicity estimations. We analyse quantum networks performing AQFT in the presence of decoherence and show that extensive approximations can be made before the accuracy of AQFT (as compared with regular quantum Fourier transform) is compromised.

B. Enriquez, V. Rubtsov

We define double (central and cocentral) extensions of Manin pairs introduced by Drinfeld, attached to curves and meromorphic differentials. We define ``infinite twistings&#39;&#39; of these pairs and quantize them in the $sl_{2}$ case, adapting Drinfeld&#39;s ``new realizations&#39;&#39; technique. We study finite dimensional representations of these algebr

N. D. Socci, J. N. Onuchic, P. G. Wolynes

The quantitative description of model protein folding kinetics using a diffusive collective reaction coordinate is examined. Direct folding kinetics, diffusional coefficients and free energy profiles are determined from Monte Carlo simulations of a 27-mer, 3 letter code lattice model, which corresponds roughly to a small helical protein. Analytic folding cal

Isabella M. Gioia

This paper given at the meeting on &#34;Mapping, Measuring and Modelling the Universe&#34; presents three topics: 1) the study of the clusters and groups of galaxies found serendipitously in the North Ecliptic Pole (NEP) region of the ROSAT all-sky survey; 2) the highest redshift clusters found in the EMSS (up to z=0.82) and the cosmological implications of

T. Meissner, E. M. Henley

We use QCD sum rules for the three point function of a pseudoscalar and two nucleonic currents in order to estimate the charge dependence of the pion nucleon coupling constant $g_{NNπ}$ coming from isospin violation in the strong interaction. The effect can be attributed primarily to the difference of the quark condensates $<{\bar u}u>$ and $<{\bar d}d>$. Fo

Vladimir O. Soloviev

It is described how the standard Poisson bracket formulas should be modified in order to incorporate integrals of divergences into the Hamiltonian formalism and why this is necessary. Examples from Einstein gravity and Yang-Mills gauge field theory are given.

Anatolij I. Bugrij, Vitalij N. Shadura

It is shown that the partition function of the 2d Ising model on the dual finite lattice with periodical boundary conditions is expressed through some specific combination of the partition functions of the model on the torus with corresponding boundary conditions. The generalization of the duality relations for the nonhomogeneous case is given. These relatio

A. M. Abrahams, J. W. York,

This paper focuses on the imposition of boundary conditions for numerical relativity simulations of black holes. This issue is used to motivate the discussion of a new hyperbolic formulation of 3+1 general relativity. The paper will appear in the Proceedings of the Les Houches School on Astrophysical Sources of Gravitational Radiation, 1995, edited by J.-A.

Y. Choquet-Bruhat, J. W. York,

We analyse the mathematical underpinnings of a mixed hyperbolic-elliptic form of the Einstein equations of motion in which the lapse function is determined by specified mean curvature and the shift is arbitrary. We also examine a new recently-published first order symmetric hyperbolic form of the equations of motion. This paper is dedicated to Andre Lichnero

A. Chaiken, M. A. Wall, R. H. Howell, I. Bozovic

Films of Bi$\rm _2$Sr$\rm _2$CaCu$\rm _2$O$\rm _8$ and Bi$\rm _2$Sr$\rm _2$CuO$\rm _6$ have been grown using Atomic-Layer-by-Layer Molecular Beam Epitaxy (ALL-MBE) on lattice-matched substrates. These materials have been combined with layers of closely-related metastable compounds like Bi$\rm _2$Sr$\rm _2$Ca$\rm _7$Cu$\rm _8$O$\rm _{20}$ (2278) and rare-eart

E. V. Ivashkevich

Kinetic equations, which explicitly take into account the branching nature of sandpile avalanches, are derived. The dynamics of the sandpile model is described by the generating functions of a branching process. Having used the results obtained the renormalization group approach to the critical behavior of the sandpile model is generalized in order to calcul

S. Galluccio, R. Graber, Y. -C. Zhang

In the theoretical biology framework one fundamental problem is the so-called error catastrophe in Darwinian evolution models. We reexamine Eigen&#39;s fundamental equations by mapping them into a polymer depinning transition problem in a ``genotype&#39;&#39; space represented by a unitary hypercubic lattice. The exact solution of the model shows that error

G. Gonzalez de la Cruz, Yu. G. Gurevich, V. V. Prosentsov

We consider the electronic transport in bounded semiconductors in the presence of an external magnetic field. Taking into account appropriate boundary conditions for the current density at the contacts, a change in the magnetoresistance of bulk semiconductors is found as compared with the usual theory of galvanomagnetic effects in boundless media. New mechan

Benjamin C. Bromley, Kaiyou Chen, Warner A. Miller

Line emission from an accretion disk and a corotating hot spot about a rotating black hole are considered for possible signatures of the frame-dragging effect. We explicitly compare integrated line profiles from a geometrically thin disk about a Schwarzschild and an extreme Kerr black hole, and show that the line profile differences are small if the inner ra

M. H. Sharifzadeh Amin, P. E. C. Stamp

We calculate the first vertex correction $δΛ_{\bf k}$ to the bare vertex $Λ_\circ$ in the nearly antiferromagnetic spin fluctuation Fermi liquid theory of the cuprate superconductor ${\rm YBa_2Cu_3O_7}$. It is calculated for $\bf k$ on the Fermi surface, and ${\bf Q}=(\pm {π\over a}, \pm {π\over a})$. We find that the dimensionless ratio $|δΛ_{\bf k}|/Λ_\cir

Carlos E. Laciana

The conditions that allow us to consider the vacuum expectation value of the energy-momentum tensor as a statistical average, at some particular temperature, are given. When the mean value of created particles is stationary, a planckian distribution for the field modes is obtained. In the massless approximation, the temperature dependence is as that correspo

Alexander Moroz

Using unitary equivalence of magnetic translation operators, explicit upper and lower convex bounds on the partition function of the Hofstadter model are given for any rational ``flux&#34; and any value of Bloch momenta. These bounds (i) generalize straightforwardly to the case of a general asymmetric hopping and to the case of hopping of the form $t_{jn}(S_

Alexander Goncharov

Two different constructions of an invariant of an odd dimensional hyperbolic manifold in the K-group $K_{2n-1}(\bar \Bbb Q)\otimes \Bbb Q$ are given. The volume of the manifold is equal to the value of the Borel regulator on that element. The scissor congruence groups in non euclidian geometries are studied and their relationship with algebraic K-theory of t

S. R. Johnson, D. E. Khmelnitskii

The free energy of the Coulomb Gap problem is expanded as a set of Feynman diagrams, using the standard diagrammatic methods of perturbation theory. The gap in the one-particle density of states due to long-ranged interactions corresponds to a renormalization of the two-point vertex function. By collecting the leading order logarithmic corrections we have de

L. F. Lemmens, F. Brosens, J. T. Devreese

For distinguishable particles it is well known that Brownian motion and a Feynman-Kac functional can be used to calculate the path integral (for imaginary times) for a general class of scalar potentials. In order to treat identical particles, we exploit the fact that this method separates the problem of the potential, dealt with by the Feynman-Kac functional

Yuji Sugawara

We study the structures of partition functions of the large $N$ generalized two-dimensional Yang-Mills theories ($gYM_2$) by recasting the higher Casimirs. We clarify the appropriate interpretations of them and try to extend the Cordes-Moore-Ramgoolam&#39;s topological string model describing the ordinary $YM_2$ \cite{CMR} to those describing $gYM_2$. We pre

James Amundson, Sean Fleming, Ivan Maksymyk

We study the phenomenology of fixed-target elastic $J/ψ$ photoproduction in the NRQCD factorization formalism. Our the goal is to test an essential feature of this formalism --- the color-octet mechanism. We obtain an order-of-magnitude estimate for a certain linear combination of NRQCD color-octet matrix elements. Our estimate is consistent with other empir

Xiao-Song Lin

We show that a variation of Milnor&#39;s $\barμ$-invariants, the so-called Campbell-Hausdorff invariants introduced recently by Stefan Papadima, are of finite type with respect to {\it marked singular links}. These link invariants are stronger than quantum invariants in the sense that they detect easily the non-invertibility of links with more than one compo

Konrad Schm&#34;udgen, Axel Sch&#34;uler

We study $N^2-1$ dimensional left-covariant differential calculi on the quantum group $SL_q(N)$ for which the generators of the quantum Lie algebras annihilate the quantum trace. In this way we obtain one distinguished calculus on $SL_q(2)$ (which corresponds to Woronowicz&#39; 3D-calculus on $SU_q(2)$) and two distinguished calculi on $SL_q(3)$ such that th

David Raitt, Hermann Riecke

Surface waves on ferrofluids exposed to a dc-magnetic field exhibit a non-monotonic dispersion relation. The effect of a parametric driving on such waves is studied within suitable coupled Ginzburg-Landau equations. Due to the non-monotonicity the neutral curve for the excitation of standing waves can have up to three minima. The stability of the waves with

Jason Levy

Let $G$ be a reductive algebraic group defined over $\bQ$, with anisotropic centre. Given a rational action of $G$ on a finite-dimensional vector space $V$, we analyze the truncated integral of the theta series corresponding to a Schwartz-Bruhat function on $V(\bA)$. The Poisson summation formula then yields an identity of distributions on $V(\bA)$. The trun

Thomas Thiemann

The loop transform in quantum gauge field theory can be recognized as the Fourier transform (or characteristic functional) of a measure on the space of generalized connections modulo gauge transformations. Since this space is a compact Hausdorff space, conversely, we know from the Riesz-Markov theorem that every positive linear functional on the space of con

M. Crescimanno, S. G. Naculich, H. J. Schnitzer

The free energy in the weak-coupling phase of two-dimensional Yang-Mills theory on a sphere for SO(N) and Sp(N) is evaluated in the 1/N expansion using the techniques of Gross and Matytsin. Many features of Yang-Mills theory are universal among different gauge groups in the large N limit, but significant differences arise in subleading order in 1/N.

K. Davis

In this article we examine the compatibility of some recent results, results relating M-Theory to String Theory, with the string-string duality conjecture in six-dimensions. In particular, we rederive the relation between M-Theory and Type IIA strings. We then go on to examine in detail M-Theory on $K3 \times S^{1}$ and its relation to the Heterotic theory o

E. Elizalde, R. Kantowski, S. D. Odintsov

The renormalization group (RG) is used to study the asymptotically free $ϕ_6^3$-theory in curved spacetime. Several forms of the RG equations for the effective potential are formulated. By solving these equations we obtain the one-loop effective potential as well as its explicit forms in the case of strong gravitational fields and strong scalar fields. Using

Fuad M. Saradzhev

For the chiral QCD_2 on a cylinder, we give a construction of a quantum theory consistent with anomaly. We construct the algebra of the Poincare generators and show that it differs from the Poincare one.

Fyodor V. Tkachov

Ambiguities of jet algorithms are reinterpreted as instability wrt small variations of input. Optimal stability occurs for observables possessing property of calorimetric continuity (C-continuity) predetermined by kinematical structure of calorimetric detectors. The so-called C-correlators form a basic class of such observables and fit naturally into QFT fra

Taekoon Lee

We study the coupling of two longitudinal Z-bosons to two gluons via technicolor interactions. Noticing a similarity of this process to $2 γ\rightarrow 2 π^{0}$, we calculate the amplitude in chiral perturbation theory in one-generation technicolor model. At the invariant mass of $ Z_{L}Z_{L}$ above the colored pseudo-Goldstone boson threshold, we find the s

Vincent Lucas, Stuart Raby

We show that one loop GUT scale threshold corrections to gauge couplings are a significant constraint on the GUT symmetry breaking sector of the theory. The one loop threshold corrections relate the prediction for $α_s(M_Z)$ to the proton lifetime. We have calculated these corrections in a new complete SO(10) SUSY GUT. The results are consistent with the low

M. Buza, Y. Matiounine, J. Smith, R. Migneron

In this paper we present the analytic form of the heavy-quark coefficient functions for deep-inelastic lepton-hadron scattering in the kinematical regime $Q^2 \gg m^2$ . Here $Q^2$ and $m^2$ stand for the masses squared of the virtual photon and heavy quark respectively. The calculations have been performed up to next-to-leading order in the strong coupling

Stanley J. Brodsky, Hung Jung Lu

Commensurate scale relations relate observables to observables and thus are independent of theoretical conventions, such as the choice of intermediate renormalization scheme. The physical quantities are related at commensurate scales which satisfy a transitivity rule which ensures that predictions are independent of the choice of an intermediate renormalizat

Fabio Zwirner

Rapporteur talk at the International Europhysics Conference on High Energy Physics, Brussels (Belgium), July 27-August 2, 1995. This talk begins with a brief general introduction to the extensions of the Standard Model, reviewing the ideology of effective field theories and its practical implications. The central part deals with candidate extensions near the

J. W. Bos, D. Chang, S. C. Lee, Y. C. Lin

We investigate the leading-order amplitudes for weak radiative decays of hyperons in chiral perturbation theory. We consistently include contributions from the next-to-leading order weak-interaction Lagrangian. It is shown that due to these terms Hara&#39;s theorem is violated. The data for the decays of charged hyperons can be easily accounted for. However,

A. P. Gottlob, M. Hasenbusch, K. Pinn

We study the iteration of block spin transformations in the O(3) symmetric non-linear sigma-model on a two-dimensional square lattice with help of the Monte Carlo method. In contrast to the classical Monte Carlo Renormalization Group approach, we do attempt to explicitly compute the block spin effective actions. Using two different methods for the determinat

S. Brian Edgar, A. Höglund

In the last few years renewed interest in the 3-tensor potential $L_{abc} $ proposed by Lanczos for the Weyl curvature tensor has not only clarified and corrected Lanczos&#39;s original work, but generalised the concept in a number of ways. In this paper we carefully summarise and extend some aspects of these results, and clarify some misunderstandings in th

A. Criscuolo, H. Waelbroeck

We propose an exact Hamiltonian lattice theory for (2+1)-dimensional spacetimes with homogeneous curvature. By gauging away the lattice we find a generalization of the ``polygon representation&#39;&#39; of (2+1)-dimensional gravity. We compute the holonomies of the Lorentz connection ${\bf A}_i = ω_i^a {\bf L}_a + e_i^a {\bf K}_a$ and find that the cycle con

A. A. Golubov, F. Wilhelm, A. D. Zaikin

We develop a detailed analysis of electron transport in normal diffusive conductors in the presence of proximity induced superconducting correlation. We calculated the linear conductance of the system and the profile of the electric field. A rich structure of temperature dependences was found and explained. Our results are consistent with recent experimental

R. Mélin

We discuss the eigenvalue spacing statistics of the Glauber matrix for various models of statistical mechanics (a one dimensional Ising model, a two dimensional Ising model, a one dimensional model with a disordered ground state, and a SK model with and without a ferromagnetic bias). The dynamics of the one dimensional Ising model are integrable, and the eig

Gunter M. Schütz

Stochastic reaction-diffusion processes may be presented in terms of integrable quantum chains and can be used to describe various biological and chemical systems. Exploiting the integrability of the models one finds in some cases good agreement between experimental and exact theoretical data. This is shown for the Rubinstein-Duke model for gel-electrophores

Gunter M. Schütz

We show that the stochastic dynamics of a large class of one-dimensional interacting particle systems may be presented by integrable quantum spin Hamiltonians. Using the Bethe ansatz and similarity transformations this yields new exact results. In a complementary approach we generalize previous work and present a new description of these and other processes

T. Nishino, K. Okunishi, M. Kikuchi

We apply a recently developed numerical renormalization group, the corner-transfer-matrix renormalization group (CTMRG), to 2D classical lattice models at their critical temperatures. It is shown that the combination of CTMRG and the finite-size scaling analysis gives two independent critical exponents.

Holger Schanz, Bernd Esser

The quantization of the electronic two site system interacting with a vibration is considered by using as the integrable reference system the decoupled oscillators resulting from the adiabatic approximation. A specific Bloch projection method is applied which demonstrates how besides some regular regions in the fine structure of the spectrum and the associat

Crystal L. Martin

We have combined measurements of the kinematics, morphology, and oxygen abundance of the ionized gas in \IZw18, one of the most metal-poor galaxies known, to examine the star formation history and chemical mixing processes.

Ben Dorman, Robert W. O&#39;Connell

We present preliminary results from spectral synthesis models of old stellar populations for the spectral range 912-4000 A with ~ 10A resolution, which can be used to investigate the UVX phenomenon and to assess ages and abundances. Model spectra incorporating extreme horizontal branch (EHB) and Post-Asymptotic Giant Branch (P-AGB) populations give good matc

A. Jaffe, M. S. Turner

We calculate limits to the properties of massive, unstable neutrinos using data from gamma-ray detectors on the Pioneer Venus Orbiter Satellite; a massive neutrino emitted from SN1987A that decayed in flight and produced gamma rays would be detectable by this instruments. The lack of such a signal allows us to constrain the branching ratio to photons ($\Bg$)

S. J. Maddox, G. Efstathiou, W. J. Sutherland

We present measurements of the angular two-point galaxy correlation function, $w(theta)$, from the APM Galaxy Survey. The performance of various estimators of $w$ is assessed using simulated galaxy catalogues and analytic arguments. Several error analyses show that residual plate-to-plate errors do not bias our estimates of $w$ by more than $10^{-3}$. Direct

Gillian Wilson, Shaun Cole, Carlos S. Frenk

Kaiser & Squires have proposed a technique for mapping the dark matter in galaxy clusters using the coherent weak distortion of background galaxy images caused by gravitational lensing. We investigate the effectiveness of this technique under controlled conditions by creating simulated CCD frames containing galaxies lensed by a model cluster, measuring the r

David J. D. Earn

A class of complete potential-density basis sets in cylindrical (R,phi,z) coordinates is presented. This class is suitable for stability studies of galactic disks in three dimensions and includes basis sets tailored for disks with vertical density profiles that are exponential (exp(-|z|/\zn)), Gaussian (exp(-(z/\zn)^2) or locally isothermal (sech^2(z/\zn)).

L. Ciotti, B. Lanzoni, A. Renzini

In this paper we explore several structural and dynamical effects on the projected velocity dispersion as possible causes of the fundamental plane (FP) tilt of elliptical galaxies. Specifically, we determine the size of the systematic trend along the FP in the orbital radial anisotropy, in the dark matter (DM) content and distribution relative to the bright

Arjun Dey, Andrea Cimatti, Wil van Breugel, Robert Antonucci

We report spectropolarimetric observations obtained with the W.M. Keck Telescope of the high redshift z=1.824 aligned radio galaxy 3C256. Our observations confirm that the spatially extended UV continuum emission from this galaxy is polarized (P_V = 10.9% +/- 0.9%) with the electric vector perpendicular to the aligned radio and optical major axes (PA = 48.0

Limin Lu, Wallace L. W. Sargent, Thomas A. Barlow

Studies of damped Lyman-alpha absorption systems in quasar spectra are yielding very interesting results regarding the chemical evolution of these galaxies. We present some preliminary results from such a program.

Gert-Martin Greuel, Christoph Lossen, Eugenii Shustin

Let P^2_r be the projective plane blown up at r generic points. Denote by E_0,E_1,...,E_r the strict transform of a generic straight line on P^2 and the exceptional divisors of the blown-up points on P^2_r respectively. We consider the variety V of all irreducible curves C in |dE_0-d_1E_1-...-d_rE_r| with k nodes as the only singularities and give asymptotic

Sergei Maslov, Yi-Cheng Zhang

We introduce and study a dynamic transport model exhibiting Self-Organized Criticality. The novel concepts of our model are the probabilistic propagation of activity and unbiased random repartition of energy among the active site and its nearest neighbors. For space dimensionality $d\geq 2$ we argue that the model is related to $d+1$ dimensional directed per

J. L. F. Barbon

We study the high energy, fixed angle, asymptotics of D-brane form factors to all orders in string perturbation theory, using the Gross-Mende saddle point techniques. The effective interaction size of all D-branes grows linearly with the energy as (alpha&#39;) E/n, where n is the order of perturbation theory, except for the D-instanton, whose form factor is

Kimyeong Lee, Erick J. Weinberg, Piljin Yi

We consider the low-energy dynamics of a pair of distinct fundamental monopoles that arise in the $N=4$ supersymmetric $SU(3)$ Yang-Mills theory broken to $U(1)\times U(1)$. Both the long distance interactions and the short distance behavior indicate that the moduli space is $R^3\times(R^1 \times {\cal M}_0)/Z$ where ${\cal M}_0$ is the smooth Taub-NUT manif

Liviu I. Nicolaescu

We present a simpler proof for the existence of adiabatic limits. Moreover, we added a new section where the adiabatic process is reversed and in some nondegenerate cases we deform the adiabatic limits to genuine irreducible solutions of the SW equations.

J. Przeszowski, H. W. L. Naus, A. C. Kalloniatis

We examine QED(3+1) quantised in the `front form&#39; with finite `volume&#39; regularisation, namely in Discretised Light-Cone Quantisation. Instead of the light-cone or Coulomb gauges, we impose the light-front Weyl gauge $A^-=0$. The Dirac method is used to arrive at the quantum commutation relations for the independent variables. We apply `quantum mechan

S. Ambrosanio, B. Mele, G. Montagna, O. Nicrosini

The production of invisible pairs of lightest neutralinos accompanied by a large-angle hard photon in the reaction $e^+ e^- \to χ^0_1 χ^0_1 γ$ is studied at LEP2 energies. The most general gaugino/higgsino composition of the $χ^0_1$ within the Minimal Supersymmetric Standard Model is assumed. The spectrum of the observed photon is derived within the framewor

L. G. Mardoyan, A. N. Sissakian, V. M. Ter-Antonyan

A non--Abelian $SU(2)$ model is constructed for a five--dimensional bound system &#34;charge--dyon&#34; on the basis of the Hurwitz--transformed eight--dimensional isotropic quantum oscillator. The principle of dyon--oscillator duality is formulated; the energy spectrum and wave functions of the system &#34;charge--dyon&#34; are calculated.

Martin Schlichenmaier

Invited lecture at the XIV-th workshop on geometric methods in physics, Bialowieza, Poland, July 9-15, 1995. In this lecture results are reviewed obtained by the author together with Martin Bordemann and Eckhard Meinrenken on the Berezin-Toeplitz quantization of compact Kaehler manifolds. Using global Toeplitz operators, approximation results for the quantum

B. Bakalov, E. Horozov, M. Yakimov

We announce a systematic way for constructing bispectral algebras of commuting differential operators of any rank N. It enables us to obtain all previously known classes and examples of bispectral operators. Moreover, we give a representation-theoretic explanation of the results including those of Duistermaat and Grünbaum. The manifold of bispectral operator

Michael Penkava

An A-infinity algebra is a generalization of a associative algebra, and an L-infinity algebra is a generalization of a Lie algebra. In this paper, we show that an L-infinity algebra with an invariant inner product determines a cycle in the homology of the complex of metric ordinary graphs. Since the cyclic cohomology of a Lie algebra with an invariant inner

D. Kharzeev

Contents: 1. Introduction 2. Operator Product Expansion for Quarkonium Interactions 3. Scale Anomaly, Chiral Symmetry and Low-Energy Theorems 4. Quarkonium Interactions in Matter 5. Conclusions and Outlook

Bengt Friman, Madeleine Soyeur

We propose a simple meson-exchange model of the photoproduction of $ρ$- and $ω$-mesons off protons near threshold ($E_γ$ less than 2 GeV). This model provides a good description of the available data and implies a large $ρ$-nucleon interaction in the scalar channel ($σ$-exchange). We use this phenomenological interaction to estimate the leading contribution

W. Koepf, G. Krein, L. A. Barreiro

Binding energy differences of mirror nuclei for A=15, 17, 27, 29, 31, 33, 39 and 41 are calculated in the framework of relativistic deformed mean-field theory. The spatial components of the vector meson fields and the photon are fully taken into account in a self-consistent manner. The calculated binding energy differences are systematically smaller than the

A. Engel, A. K. Dutt-Mazumder, R. Shyam, U. Mosel

Motivated by the renewed interest in studying the pion production on nuclei with protons at few GeV incident energies, we investigate the pion production in proton-proton collisions over an energy range of 300 $MeV$ to 2 $GeV$. Starting from a realistic one-boson exchange model with parameters fitted to the amplitudes of the elastic nucleon-nucleon scatterin