November 1994 arXiv papers — page 2

C. Bernard, T. Blum, A. De, T. DeGrand

Preliminary results from the MILC collaboration for $f_B$, $f_{B_s}$, $f_D$, $f_{D_s}$ and their ratios are presented. We compute in the quenched approximation at $β=6.3$, 6.0 and 5.7 with Wilson light quarks and static and Wilson heavy quarks. We attempt to quantify systematic errors due to finite volume, finite lattice spacing, large $am$, and fitting and

Wolfgang Bock

Regge's method for regularizing euclidean quantum gravity is applied to two dimensional gravity. Using topologies with genus zero and two and a scale invariant measure, we show that the Regge method fails to reproduce the values of the string susceptibilities of the continuum model.

Wolfhard Janke, Stefan Kappler

We performed Monte Carlo simulations of two-dimensional $q$-state Potts models with $q=10,15$, and $20$ and measured the spin-spin correlation function at the first-order transition point $β_t$ in the disordered and ordered phase. Our results for the correlation length $ξ_d(β_t)$ in the disordered phase are compatible with an analytic formula. Estimates of t

Wolfhard Janke, Stefan Kappler

Inspired by the multicanonical approach to simulations of first-order phase transitions we propose for $q$-state Potts models a combination of cluster updates with reweighting of the bond configurations in the Fortuin-Kastelein-Swendsen-Wang representation of this model. Numerical tests for the two-dimensional models with $q=7, 10$ and $20$ show that the aut

Christoph Best, Andreas Schäfer

We use a self-guided random walk to solve the ground-state problem of Hamiltonian U(1) pure gauge theory in 2+1 dimensions in the string sector. By making use of the electric-field representation, we argue that the spatial distribution of the electric field can be more easily measured than in ordinary Monte Carlo simulations.

Hartmut Wittig

We report on a set of simulations performed at several values of the lattice spacing on the Cray T3D at Edinburgh. Different methods to extract the lattice scale from the static quark potential are discussed.

N. Persky, R. Ben-Av, S. Solomon

We present a new measure of the Dynamical Critical behavior: the "Multi-scale Dynamical Exponent (MDE)"

Sorin Solomon

Many complex systems are representable as macroscopic set of elements which interact by simple rules. The complex macroscopically relevant phenomena are then the result of the generic emergence of a space-time multi-scale dynamics. Critical Slowing Down labels the emerging global features and describes their complex collective evolution. This paradigm is qui

Xiang-Qian Luo, Wolfgang Franzki

We report the recent results from the computer simulations of a fermion-gauge-scalar model with dynamical chiral-symmetry breaking and chiral transition induced by the scalar field. This model might be considered to be a possible alternative to the Higgs mechanism of mass generation. A new scheme is developed for detecting the chiral transition. Our results

Wolfgang Franzki, Xiang-Qian Luo

The strongly coupled lattice gauge models show an interesting mechanism of dynamical mass generation. If a suitable continuum limit can be found, one may think of it as an alternative to the Higgs mechanism. We present data on the spectrum, obtained in the model with U(1) gauge symmetry with dynamical fermions. They indicate that the fermion mass scales in t

Bas V. de Bakker

Due to the unrecognizability of certain manifolds there must exist pairs of triangulations of these manifolds that can only be reached from each other by going through an intermediate state that is very large. This might reduce the reliability of dynamical triangulation, because there will be states that will not be reached in practice. We investigate this p

Sergei V. Zenkin

We argue that non-trivial fixed points bordering on the paramagnetic and ferromagnetic phases are most likely to exist in the Higgs-Yukawa systems that have a connected domain with the paramagnetic phase and no ferrimagnetic phase. We find three examples of such systems; among them is the U(1) system with naive fermions.

M. Blatter, R. Burkhalter, P. Hasenfratz, F. Niedermayer

The classical equations of motion of the perfect lattice action in asymptotically free $d=2$ spin and $d=4$ gauge models possess scale invariant instanton solutions. This property allows the definition of a topological charge on the lattice which is perfect in the sense that no topological defects exist. The basic construction is illustrated in the $d=2$ O(3

Pimentel L O, Camacho A, Macias A

The Weyl equation (massless Dirac equation) is studied in a family of metrics of the Gödel type. The field equation is solved exactly for one member of the family.

Pimentel L O, Obregon O

For pure fourth order (${\cal{L}} \propto R^2$) quantum cosmology the Wheeler-DeWitt equation is solved exactly for the closed homogeneous and isotropic model. It is shown that by imposing as boundary condition that $Ψ= 0$ at the origin of the universe the wave functions behave as suggested by Vilenkin.

Pimentel L O, Diaz-Rivera L M

The effect of bulk viscisity on the evolution of the homogeneous and isotropic cosmological models is considered. Solutions are found, with a barotropic equation of state, and a viscosity coefficient that is proportional to a power of the energy density of the universe. For flat space, power law expansions, related to extended inflation are found as well as

T. Damour, A. M. Polyakov

It is pointed out that string-loop effects may generate matter couplings for the dilaton allowing this scalar partner of the tensorial graviton to stay massless while contributing to macroscopic gravity in a way naturally compatible with existing experimental data. Under a certain assumption of universality of the dilaton coupling functions (possibly realize

Yasunori Fujii

A quantum correction to the Brans-Dicke theory due to interactions among matter fields is calculated, resulting in violation of WEP, hence giving a constraint on the parameter $ω$ far more stringent than accepted so far. The tentative estimate gives the lower bounds $\gsim 10^{6}$ and $\gsim 10^{8}$ for the assumed force-range $\gsim 1$m and $\gsim 1$AU, res

M. J. W. Dodgson, M. A. Moore

The free energy costs for various defects within an Abrikosov lattice of vortices are calculated using the lowest Landau level approximation (LLL). Defect solutions with boundary conditions for lines to meet at a point (crossing defect) and for lines to twist around each other (braid defect) are sought for 2, 3, 6, and 12 lines. Many results have been unexpe

Harald Kinzelbach, Michael Lassig

We study the continuum field theory for an ensemble of directed polymers r_i (t) in 1+d' dimensions that live in a medium with quenched point disorder and interact via short-ranged pair forces g Ψ(r_i - r_j). In the strong-disorder (or low-temperature) regime, such forces are found to be relevant in any dimension d' below the upper critical dimension

Krzysztof Byczuk, Jozef Spalek

We point to the possibility of existence of the statistical-spin-liquid state as the state which differs from either Fermi or Luttinger liquid states. In the statistical spin liquid the double occupancies are excluded from the physical space. Each of the above three cases (Fermi, Luttinger and spin liquids) represents an universality class for the interactin

Gu Yan

We introduce a Hamiltonian coupled between a normal Fermi surface and a polarized Maxwell type gauge field.We adopt a {\it calibrated scaling } approach in order to be consistent with the results obtained at $2+1$ dimensions as well as the Weinberg's theo rem. Renormalization group equations are calculated by using a dimension regulator. It turns out tha

J. D. Brock, A. C. Finnefrock, K. L. Ringland, E. Sweetland

Using high resolution x-ray scattering, we have measured the structure of the Q_1 CDW in Ta-doped NbSe_3. Detailed line shape analysis of the data demonstrates that two length scales are required to describe the phase-phase correlation function. Phase fluctuations with wavelengths less than a new length scale $a$ are suppressed and this $a$ is identified wit

N. Chandrabhas, Ajay K. Sood, D. V. S. Muthu, C. S. Sundar

We have studied single crystals of $C_{70}$ by Raman scattering and photoluminescence in the pressure range from 0 to 31.1 GPa. The Raman spectrum at 31.1 GPa shows only a broad band similar to that of the amorphous carbon without any trace of the Raman lines of $C_{70}$. After releasing the pressure from 31.1 GPa, the Raman and the photoluminescence spectra

R. Aurich, T. Hesse, F. Steiner

Based on an accurate computation of the first 1851 quantal energy levels of the truncated hyperbola billiard, we have found an anomalous long-range modulation in the integrated level density. It is shown that the observed anomaly can be explained by an additional term in Gutzwiller's trace formula. This term is given as a sum over families of closed, non

J. Greiner, W. Wenzel

We present a 100 yr optical lightcurve of the recently discovered supersoft X-ray source RX~J0019.8+2156 as deduced from photographic plates of Harvard and Sonneberg Observatory. Apart from the periodic orbital variations two different timescales of optical variability are discovered. The timescales and amplitudes of this variability are discussed in the fra

M. Jaroszynski, B. Paczynski

A conventional explanation of the dipole anisotropy of the cosmic microwave background (CMB) radiation is in terms of the Doppler effect: our galaxy is moving with respect to CMB frame with $ \sim 600 ~ km ~ s^{-1} $. However, as the deep redshift surveys fail to reveal a convergence of the large scale flow to zero at distances as large as $ d \sim H^{-1} 15

A. Franceschini, P. Andreani

We report on observations performed at 1.25 $mm$ of a southern galaxy sample, selected from the IRAS PSC and complete to $S_{60}=2 Jy$. We detected 18 sources and set significant limits on 10 further objects. We use these data to discuss the spatial distribution of cold dust, the broad-band far-IR/mm spectra, the overall amount of dust, the gas-to-dust mass

N. Zacharias, A. L. Fey, J. L. Russell, K. J. Johnston

The radio observations are based on dual frequency Mark--III VLBI data from 1979 until the end of 1993. Currently 436 sources define the celestial inertial frame. A comparison to the JPL94R01 catalog is made. Position vs. time plots of selected sources show significant apparent non linear proper motions. The status of the project and recent results from opti

L. Carigi, P. Colin, M. Peimbert, A. Sarmiento

We discuss the chemical evolution of metal poor galaxies and conclude that their oxygen deficiency is not due to: the production of black holes by massive stars or a varying slope of the Initial Mass Function, IMF, at the high-mass end. A varying IMF at the low-mass end alone or in combination with: (a) an outflow of oxygen-rich material, (b) an outflow of w

Damiano Anselmi

Riemann surfaces with nodes can be described by introducing simple composite operators in matrix models. In the case of the Kontsevich model, it is sufficient to add the quadratic, but ``non-propagating'', term (tr[X])^2 to the Lagrangian. The corresponding Jenkins-Strebel differentials have pairwise identified simple poles. The result is in agreemen

Damiano Anselmi, Pietro Fre'

The monopole equations in the dual abelian theory of the N=2 gauge-theory, recently proposed by Witten as a new tool to study topological invariants, are shown to be the simplest elements in a class of instanton equations that follow from the improved topological twist mechanism introduced by the authors in previous papers. When applied to the N=2 sigma-mode

B. Holdom, Randy Lewis

A momentum dependent quark mass may be incorporated into a quark model in a manner consistent with dynamically broken chiral symmetry. We use this to study the high $Q^2$ behavior of the vector, axialvector, scalar and pseudoscalar two-point correlation functions. Expanding the results to order $1/Q^6$, we show the correspondence between the dynamical quark

Wolfgang Bauer

Multifragmentation reactions without large compression in the initial state (proton-induced reactions, reverse-kinematics, projectile fragmentation) are examined, and it is verified quantitatively that the high temperatures obtained from fragment kinetic energy spectra and lower temperatures obtained from observables such as level population or isotope ratio

R. Baier, Yu. L. Dokshitzer, S. Peigné, D. Schiff

Soft gluon radiation induced by multiple scattering of a fast quark or gluon propagating through QCD matter is discussed. After revisiting the Landau-Pomeranchuk-Migdal effect in QED we show that large formation times of bremsstrahlung quanta determine the QCD radiation intensity (in analogy to QED) and derive the gluon energy spectrum. Coherent suppression

Glenn Barnich, Friedemann Brandt, Marc Henneaux

It is shown that in the absence of free abelian gauge fields, the conserved currents of (classical) Yang-Mills gauge models coupled to matter fields can be always redefined so as to be gauge invariant. This is a direct consequence of the general analysis of the Wess-Zumino consistency condition for Yang-Mills theory that we have provided recently.

Taichi Itoh, Yoonbai Kim, Masaki Sugiura, Koichi Yamawaki

We reformulate the Thirring model in $D$ $(2 \le D < 4)$ dimensions as a gauge theory by introducing $U(1)$ hidden local symmetry (HLS) and study the dynamical mass generation of the fermion through the Schwinger-Dyson (SD) equation. By virtue of such a gauge symmetry we can greatly simplify the analysis of the SD equation by taking the most appropriate gaug

R. Jagannathan, J. Van der Jeugt

Using the Fronsdal-Galindo formula for the exponential mapping from the quantum algebra $U_{p,q}(gl(2))$ to the quantum group $GL_{p,q}(2)$, we show how the $(2j+1)$-dimensional representations of $GL_{p,q}(2)$ can be obtained by `exponentiating&#39; the well-known $(2j+1)$-dimensional representations of $U_{p,q}(gl(2))$ for $j$ $=$ $1,{3/2},... $; $j$ $=$ 1

R. K. Bhaduri, R. S. Bhalerao, M. V. N. Murthy

We generalize the collision term in the one-dimensional Boltzmann-Nordheim transport equation for quasiparticles that obey the Haldane exclusion statistics. For the equilibrium situation, this leads to the ``golden rule&#39;&#39; factor for quantum transitions. As an application of this, we calculate the density response function of a one-dimensional electro

Fernando Torres

We study upper bounds on the order of automorphisms of non-singular curves $X$ satisfying at least one of the following hypothesis: 1) $X$ is an $m$-sheeted covering of exactly one non-singular curve of genus $γ$, where $m$ is prime; 2) the center of the group of automorphisms of $X$ is non-trivial.

A. E. Carlsson

A new order-N method for calculating the electronic structure of general (non-tight-binding) potentials is presented. The method uses a combination of the ``purification&#39;&#39;-based approaches used by Li, Nunes and Vanderbilt, and Daw, and a representation of the density matrix based on ``travelling basis orbitals&#39;&#39;. The method is applied to seve

M. Lawrence Glasser, Victor Kowalenko

We present a method derived from Laplace transform theory that enables the evaluation of fractional integrals. This method is adapted and extended in a variety of ways to demonstrate its utility in deriving alternative representations for other classes of integrals. We also use the method in conjunction with several different techniques to derive many result

Richard Kenyon

We show how to determine if a given simple rectilinear polygon can be tiled with rectangles, each having an integer side.

Richard Kenyon

We show that a square-tiling of a $p\times q$ rectangle, where $p$ and $q$ are relatively prime integers, has at least $\log_2p$ squares. If $q>p$ we construct a square-tiling with less than $q/p+C\log p$ squares of integer size, for some universal constant $C$.

Sergio R. Fenley

In this article we study the topological structure of the lifts to the universal of the stable and unstable foliations of $3$-dimensional Anosov flows. In particular we consider the case when these foliations do not have Hausdorff leaf space. We completely determine the structure of the set of non separated leaves from a given leaf in one of these foliations

A. H. Bougourzi

We extend the concept of conjugate vertex operators, first introduced by Dotsenko in the case of the bosonization of the $su(2)$ conformal field theory, to the bosonization of the dynamical vertex operators (type II in the classification of the Kyoto school) of the higher spin XXZ model. We show that the introduction of the conjugate vertex operators leads t

F. Antonuccio, S. Dalley

Motivated by a possible relativistic string description of hadrons we use a discretised light-cone quantisation and Lanczos algorithm to investigate the phase structure of phi^3 matrix field theory in the large N limit. In 1+1 dimensions we confirm the existence of Polyakov&#39;s non-critical string theory at the boundary between parton-like and string-like

F. Gliozzi, R. Tateo

We describe a new infinite family of multi-parameter functional equations for the Rogers dilogarithm, generalizing Abel&#39;s and Euler&#39;s formulas. They are suggested by the Thermodynamic Bethe Ansatz approach to the Renormalization Group flow of 2D integrable, ADE-related quantum field theories. The known sum rules for the central charge of critical fix

A. Y. Shiekh

A preferred form for the path integral discretization is suggested that allows the implementation of canonical transformations in quantum theory.

V. Kartvelishvili, M. Margvelashvili

Comparing the results of finite energy and Borel transformed sum rules for the difference of vector and axial vector current correlators we evaluate the instanton contributions to the $τ$ hadronic width. In contrast to an explicit theoretical calculation we find that the instanton contributions to the $τ$ hadronic width are much smaller than the standard non

P. Binetruy, E. Dudas

We investigate the problem of the fermion mass hierarchy in supergravity models with flat directions of the scalar potential associated with some gauge singlet moduli fields. The low-energy Yukawa couplings are nontrivial homogeneous functions of the moduli and a geometric constraint between them plays, in a large class of models, a crucial role in generatin

J. M. Moreno, D. H. Oaknin, M. Quirós

We construct a simple class of exact solutions of the electroweak theory including the naked $Z$--string and fermion fields. It consists in the $Z$--string configuration ($ϕ,Z_θ$), the {\it time} and $z$ components of the neutral gauge bosons ($Z_{0,3},A_{0,3}$) and a fermion condensate (lepton or quark) zero mode. The $Z$--string is not altered (no feed bac

Yue Hu

We calculate the bubble nucleation rate in a fourth-order gravity theory whose action contains an $R^2$ term, under the thin-wall approximation, by two different methods. First the bounce solution is found for the Euclidean version of the original action. Next, we use a conformal transformation to transform the theory into general relativity with an addition

Ernest Ma

Two first examples beyond the standard model are given which exhibit left-right symmetry (g_L = g_R) and supersymmetry at a few TeV, together with gauge-coupling unification at around 10^{16} GeV.

Ernest Ma

The existence of supersymmetry above a few TeV and that of two Higgs doublets at the electroweak energy scale do not necessarily result in the minimal supersymmetric standard model (MSSM). An interesting counter example is given with m_h < 2^{1/2} m_W + radiative corrections = 145 GeV instead of m_h < m_Z + radiative corrections = 128 GeV in the MSSM.

Palash B Pal

We analyze two recent models based on the gauge group SU(3)$_c\times$SU(3)$_L\times$U(1)$_N$ where each generation is not anomaly-free, but anomaly cancels when three generations are taken into account. We show that the most general Yukawa couplings of these models admit of a Peccei-Quinn symmetry. This symmetry can be extended to the entire Lagrangian by us

Minoru Tanaka

We study effects of charged Higgs boson exchange in the $B$ semileptonic decays $\bar B \rightarrow D^{(*)}τ\barν_τ$. Both branching ratio and $τ$ polarization are examined. We use the recent experimental data on semileptonic $B$ decays and the heavy quark effective theory in order to reduce theoretical uncertainty in the hadronic form factors. Theoretical u

Kang Young Lee, Yeong Gyun Kim, Jae Kwan Kim

In order to study the end-point spectrum of inclusive semileptonic $b \rightarrow u$ decays, we investigate the parton model motivated by deep inelastic scattering process. The reliability of the model is carefully examined by comparing the decay rates and the lepton spectra for $b \rightarrow c$ decay with those of the heavy quark effective theory. We also

Keh-Fei Liu, Shao-Jing Dong

We study the valence approximation in lattice QCD of hadrons where the cloud quarks and antiquarks are deleted by truncating the backward time propagation (Z graphs) in the connected insertions. Whereas, the sea quarks are eliminated via the quenched approximation and in the disconnected insertions. It is shown that the ratios of isovector to isoscalar matri

A. Ali Khan, S. Collins, C. T. H. Davies, U. M. Heller

We present {\it preliminary} results for the spectrum and decay constants of B mesons using NRQCD heavy and Wilson light quarks on configurations at $β=5.6$ with two dynamical flavours of staggered fermions. All terms to order $1/M_Q$ are included in the NRQCD action; matrix elements are corrected to this order by calculating the small components of the heav

B. Jegerlehner

First results on the autocorrelation behaviour of a recently proposed fermion algorithm by M. Lüscher are presented and discussed. The occurence of unexpected large autocorrelation times is explained. Possible improvements are discussed.

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 compare the extrapolated data to the renormalization-group

Stefan Sint

The Schrödinger functional in Wilson&#39;s lattice QCD leads to a sensible classical continuum theory which can be taken as starting point for a perturbative analysis. In dimensional regularization, the saddle point expansion of the Schrödinger functional is performed to one-loop order of perturbation theory. The divergences are partly cancelled by the usual

Sergio Caracciolo, Robert G. Edwards, Sabino J. Ferreira, Andrea Pelissetto

We present a simple and powerful method for extrapolating finite-volume Monte Carlo data to infinite volume, based on finite-size-scaling theory. We discuss carefully its systematic and statistical errors, and we illustrate it using three examples: the two-dimensional three-state Potts antiferromagnet on the square lattice, and the two-dimensional $O(3)$ and

J. L. Alonso, Ph. Boucaud, F. Lesmes, A. J. van der Sijs

The Roma and Zaragoza actions for chiral fermions on the lattice are shown to be essentially equivalent. The auxiliary fermion fields in the Roma model can be integrated out, and the resulting action is a special case of the Zaragoza approach. We use this result to perform a mean-field study of the phase diagram of chiral Yukawa models in the Roma formulatio

M. Caselle, F. Gliozzi, U. Magnea, S. Vinti

We discuss and rederive in a general way the logarithmic growth of the mean squared width of the colour flux tube as a function of the interquark separation. Recent data on 3D $Z_2$ gauge theory, combined with high precision data on the interface physics of the 3D Ising model fit nicely this behaviour over a range of more than two orders of magnitude.

G. Mack

Positing complex adaptive systems made of agents with relations between them that can be composed, it follows that they can be described by gauge theories similar to elementary particle theory and general relativity. By definition, a universal dynamics is able to determine the time development of any such system without need for further specification. The po

Donald Marolf

Local action principles on a manifold $\M$ are invariant (if at all) only under diffeomorphisms that preserve the boundary of $\M$. Suppose, however, that we wish to study only part of a system described by such a principle; namely, the part that lies in a bounded region $R$ of spacetime where $R$ is specified in some diffeomorphism invariant manner. In this

Jacek Jezierski

A twenty--dimensional space of charged solutions of spin--2 equations is proposed. The relation with extended (via dilatation) Poincaré group is analyzed. Locally, each solution of the theory may be described in terms of a potential, which can be interpreted as a metric tensor satisfying linearized Einstein equations. Globally, the non--singular metric tenso

Yu. Kubyshin, E. Moreno, J. I. Pérez Cadenas

We study the process of the evolution of the space of extra dimensions in the framework of Einstein-Yang-Mills cosmological models. It is shown that, for certain classes of models, the static compact space of extra dimensions is the attractor for a wide range of initial conditions. Also the effect of isotropization of extra dimensions in the course of evolut

Johann Kroha, Andrea Huck, Thilo Kopp

We investigate the influence of interference between Coulomb interaction and impurity scattering on the static electronic response $χ(0,q)$ in disordered metals to leading order in the effective Coulomb interaction. When the transport relaxation time $τ_{tr}$ is much shorter than the quasiparticle life time, we find a $\mbox{sgn}(2p_F-q)/\sqrt{|2p_F-q|}$ div

Nandini Trivedi, Mohit Randeria

We show that there are qualitative differences between the temperature dependence of the spin and charge correlations in the normal state of the 2D attractive Hubbard model using quantum Monte Carlo simulations. The one-particle density of states shows a pseudogap above $\tc$ with a depleted $N(0)$ with decreasing $T$. The susceptibility $\cs$ and the low fr

M. Widom, H. Zhang, Carnegie-Mellon U

Recently Groh and Dietrich claimed the thermodynamic state of a dipolar fluid depends on the shape of the fluid&#39;s container. For example, a homogeneous fluid in a short fat container would phase separate when transferred to a tall skinny container of identical volume and temperature. Their calculation thus lacks a thermodynamic limit. We show that remova

Xuejun Zhu, Mark S. Hybertsen, P. B. Littlewood, Martin C. Nuss

Using a perturbation theory based on the density-matrix formulation, we study the nonlinear optical responses of a noninteracting three-level model system to consecutive coherent pulsed excitations, as realized in several recent experiments involving excitonic transitions in quantum wells. The terahertz emission, which is a second order response, and the fou

A. B. Harris, C. Micheletti, J. M. Yeomans

We obtain the ANNNI model from a Heisenberg model with large single--ion anisotropy energy, $D$, as might be relevant for helical spin systems. We treat quantum fluctuations to lowest order in $1/S$ at zero temperature within an expansion in $J/D$, where $J$ is an exchange energy. The transition from the state with periodicity $p=4$ to the uniform state ($p=

R. Gielerak, R. Olkiewicz

It is demonstrated that the thermal structure of the noncritical free Bose Gas is completely described by certain periodic generalized Gaussian stochastic process or equivalently by certain periodic generalized Gaussian random field. Elementary properties of this Gaussian stochastic thermal structure have been established. Gentle perturbations of several typ

Giorgio Parisi

In this talk I will show that usual spin glasses are a peculiar kind of Abelian gauge theory. I will shortly review the techniques used to study them. At the end I will consider more general models (e.g. spin glasses based on non Abelian gauge group) and I will discuss the relevance of these models to real glasses. Finally I will derive from first principles

Achille Giacometti, Amos Maritan, Flavio Toigo, Jayanth R. Banavar

A novel exact dynamical real space renormalization group for a Langevin equation derivable from a Euclidean Gaussian action is presented. It is demonstrated rigorously that an algebraic temporal law holds for the Green function on arbitrary structures of infinite extent. In the case of fractals it is shown on specific examples that two different fixed points

Achille Giacometti

An exact closed form solution for the return probability of a random walk on the Bethe lattice is given. The long-time asymptotic form confirms a previously known expression. It is however shown that this exact result reduces to the proper expression when the Bethe lattice degenerates on a line, unlike the asymptotic result which is singular. This is shown t

Andreas Stolcke

We describe an extension of Earley&#39;s parser for stochastic context-free grammars that computes the following quantities given a stochastic context-free grammar and an input string: a) probabilities of successive prefixes being generated by the grammar; b) probabilities of substrings being generated by the nonterminals, including the entire string being g

R. G. Crittenden, D. Coulson, N. G. Turok

We study the polarization-temperature correlations on the cosmic microwave sky resulting from an initial scale invariant spectrum of tensor (gravity wave) fluctuations, such as those which might arise during inflation. The correlation function has the opposite sign to that for scalar fluctuations on large scales, raising the possibility of a direct determina

Heino Falcke, Gopal-Krishna, Peter L. Biermann

We link the lack of FR I type structure among quasars to the void of radio loud quasars below a critical disk luminosity of ~10^46 erg/sec in the PG sample. We argue that the opening angle of the obscuring torus in radio loud quasars depends on the power of the central engine, approaching the jet&#39;s beaming angle near the FR I/FR II break. Consequently, l

W. M. Oxbury

We show that the Verlinde formula for moduli spaces of spin bundles on an algebraic curve gives dimensions of direct sums of spaces of theta functions over the finite set of Prym varieties of unramified double covers of the curve. We then construct a natural duality (though we do not show it is nondegenerate) between the latter spaces and the spaces of secti

Didier Sornette, Anders Johansen, Ivan Dornic

We present a general conceptual framework for self-organized criticality (SOC), based on the recognition that it is nothing but the expression, &#39;&#39;unfolded&#39;&#39; in a suitable parameter space, of an underlying {\em unstable} dynamical critical point. More precisely, SOC is shown to result from the tuning of the {\em order parameter} to a vanishing

A. A. Tseytlin

We identify a string theory counterpart of the dilatonic Melvin D=4 background describing a &#34;magnetic flux tube&#34; in low-energy field theory limit. The corresponding D=5 bosonic string model containing extra compact Kaluza-Klein dimension is a direct product of the D=2 Minkowski space and a D=3 conformal sigma model. The latter is a singular limit of

Yakir Aharonov, Lev Vaidman

Protective measurements yield properties of the quantum state of a single quantum system without affecting the quantum state. A protective measurement involves adiabatic coupling to the measuring device together with a procedure to protect the state from changing. For nondegenerate energy eigenstates the protection is provided by the system itself. In this c

Maxim Braverman

Let F be a flat vector bundle over a compact Riemannian manifold M and let f be a Morse function. Let g be a smooth Euclidean metric on F, let g_t=e^{-2tf}g and let ρ(t) be the Ray-Singer analytic torsion of F associated to the metric g_t. Assuming that the vector field grad(f) satisfies the Morse-Smale transversality conditions, we provide an asymptotic exp

Nathan Poliatzky

Recently R. G. Newton published a comment criticizing the methods and the results of a paper published by the author. His criticism touches on a few key points of the subject and hence deserves a detailed reply. Here is the reply, point by point, to his criticism.

A. V. Postnikov, G. Borstel

{}From a series of total energy calculations by the full-potential linear muffin-tin orbital method, the total energy hypersurface as function of atomic displacements from equilibrium positions has been fitted for different Gamma phonon modes in orthorhombic KNbO3. Frequencies and eigenvectors of all TO Gamma phonons have been calculated in the harmonic appr

N. Kawashima, J. E. Gubernatis

We discuss the development of cluster algorithms from the viewpoint of probability theory and not from the usual viewpoint of a particular model. By using the perspective of probability theory, we detail the nature of a cluster algorithm, make explicit the assumptions embodied in all clusters of which we are aware, and define the construction of free cluster

Jonathan E. Grindlay, Eyal Maoz

In a recent study (Maoz and Grindlay 1995) we have found that a number of previously recognized anomalies in the diffuse x-ray background at soft energies (\sim 0.5-2 keV) can be understood if about 20-30% of the diffuse flux arises from a population of low luminosity sources in a thick disk or flattened halo distribution in the Galaxy. Here we summarize our

C. P. Burgess, R. C. Myers, F. Quevedo

We consider the effects of abelian duality transformations on static, spherically-symmetric, asymptotically flat string spacetimes in four dimensions, where the dilaton, axion, metric, and gauge fields are allowed to be nonzero. Independent of the alpha&#39; expansion, there is a six-parameter family of such configurations, labelled by the charges characteri

Dallas C. Kennedy

Summary of electroweak Standard Model, including aspects of gauge summetry, symmetry breaking, and quantum radiative corrections. Implications of precise electroweak measurements for Standard Model and hypothetical non-Standard states and interactions. Status of exact and approximate symmetries of the Standard Model. The minimal electroweak Standard Model sa

D. Krob, B. Leclerc

We present several identities involving quasi-minors of noncommutative generic matrices. These identities are specialized to quantum matrices, yielding q-analogues of various classical determinantal formulas.

Mariano Quirós

We present bounds on the Higgs mass in the Standard Model and in the Minimal Supersymmetric Standard Model using the effective potential with next-to-leading logarithms resummed by the renormalization group equations, and physical (pole) masses for the top quark and Higgs boson. In the Standard Model we obtain lower bounds from stability requirements: they d

S. Aoki, M. Fukugita, S. Hashimoto, N. Ishizuka

Charmonium spectroscopy with Kogut-Susskind valence quarks are carried out for quenched QCD at $β=6.0$ and for two-flavor full QCD at $β=5.7$. Results for 1P--1S mass splitting and estimates of $α^{(5)}_{\overline{MS}}(m_Z)$ are reported. Problems associated with flavor breaking effects and finite size effects of $1P$ states are discussed.

L. Del Riego, P. E. Parker

The pseudoconvex and disprisoning conditions for geodesics of linear connections are extended to the solution curves of general homogeneous sprays. The main result is that pseudoconvexity and disprisonment are jointly stable in the fine topology on the space of all homogeneous sprays of any degree of homogeneity.

M. Kolesik, M. Suzuki

An analysis of the critical behavior of the three-dimensional Ising model using the coherent-anomaly method (CAM) is presented. Various sources of errors in CAM estimates of critical exponents are discussed, and an improved scheme for the CAM data analysis is tested. Using a set of mean-field type approximations based on the variational series expansion appr

Matthias H. Hettler, Herbert Schoeller

The influence of high-frequency fields on quantum transport through a quantum dot is studied in the low-temperature regime. We generalize the non crossing approximation for the infinite-U Anderson model to the time-dependent case. The dc spectral density shows asymmetric Kondo side peaks due to photon-assisted resonant tunneling. As a consequence we predict

Jean Pierre Boon, Olivier Decroly

We show that, when music pieces are cast in the form of time series of pitch variations, the concepts and tools of dynamical systems theory can be applied to the analysis of {\it temporal dynamics} in music. (i) Phase space portraits are constructed from the time series wherefrom the dimensionality is evaluated as a measure of the {\pit global} dynamics of e