September 1992 arXiv papers — page 3

Al. R. Kavalov

A modified rigid string theory with infrared behaviour governed by a nontrivial fixed point is presented.

S. Dalley, I. Klebanov

We propose gauging matrix models of string theory to eliminate unwanted non-singlet states. To this end we perform a discretised light-cone quantisation of large N gauge theory in 1+1 dimensions, with scalar or fermionic matter fields transforming in the adjoint representation of SU(N). The entire spectrum consists of bosonic and fermionic closed-string exci

Daniel S. Freed

This paper is an expanded version of a talk given at the XIX International Colloquium on Group Theoretical Methods in Physics, Salamanca, July, 1992. We discuss the geometry of topological terms in classical actions, which by themselves form the actions of topological field theories. We first treat the Chern-Simons action directly. Then we explain how the ge

A. Polyakov

We describe conformal field theories, correlation functions of which satisfy equations of the two-dimensional fluid mechanics. Prediction for the energy spectrum is given, $E(k) \sim k^{-25/7}$.

Ram Brustein, Burt Ovrut

A canonical Lorentz invariant field theory extension of collective field theory of d=1 matrix models is presented. We show that the low density, discrete, sector of collective field theory includes single eigenvalue Euclidean instantons which tunnel between different vacua of the extended theory. These "stringy" instantons induce non-perturbative eff

Zheng Huang

We investigate a controversial issue on the measure of CP violation in strong in teractions. In the presence of nontrivial topological gauge configurations, the $θ$-term in QCD has a profound effect: it breaks the CP symmetry. The CP-violating amplitude is shown to be determined by the vacuum tunneling process, where the semiclassical method makes most sense

Zheng Huang

We examine an interesting scenario to solve the domain wall problem recently suggested by Preskill, Trivedi, Wilczek and Wise. The effective potential is calculated in the presence of the QCD axial anomaly. It is shown that some discrete symmetries such as CP and Z_2 can be anomalous due to a so-called $K$-term induced by instantons. We point out that Z_2 do

M. Carena, C. E. M. Wagner

The effective potential of scalar quantum electrodynamics with N flavors of complex scalar fields is studied, by performing a self consistent 1/N expansion up to next to leading order in $1/N$. Starting from the broken phase at zero temperature, the theory exhibits a phase transition to the symmetric phase at some finite temperature $T_c$. We work in general

V. Barger, M. S. Berger, P. Ohmann

We make a numerical study of gauge and Yukawa unification in supersymmetric grand unified models and examine the quantitative implications of fermion mass ansätze at the grand unified scale. Integrating the renormalization group equations with $α_1(M_Z)$ and $α_2(M_Z)$ as inputs, we find $α_3(M_Z)\simeq 0.111 (0.122)$ for $M_{SUSY}^{}=m_t$ and $α_3(M_Z)\sime

C. Bruno, J. Prades

We study the unknown coupling constants that appear at order $p^4$ in the Chiral Perturbation Theory analysis of $K \to πγ^* \to πl^+ l^-$, $K^{+-} \to π^{+-} γγ$ and $K \to ππγ$ decays. To that end, we compute the chiral realization of the $ΔS \, = \, 1$ Hamiltonian in the framework of the $1/N_c$-expansion of the low-energy action. The phenomenological imp

C. Gong

The classical SU(3) gauge theory is shown to be deterministic chaotic. Its largest Lyapunov exponent is dertermined, from which a short time scale of thermalization of a pure gluon system is estimated. The connection to gluon damping rate is discussed.

Dalia S. Goldwirth, Malcolm J. Perry, Tsvi Piran

We construct the propagator of a non-relativistic non-interacting particle in a flat spacetime in which two regions have been identified. This corresponds to the simplest "time machine". We show that while completeness is lost in the vicinity of the time machine it holds before the time machine appears and it is recovered afterwards. Unitarity, howev

Ofer Biham, L. -W. Chen, Gianfranco Vidali

Motivated by recent experimental studies of Hg and Pb monolayers on Cu(001) we introduce a zero temperature model of a monolayer adsorbed on a square substrate. Lennard-Jones potentials are used to describe the interaction between pairs of adlayer-adlayer and adlayer-substrate atoms. We study a special case in which the monolayer atoms form a perfect square

Wei Li, Gianfranco Vidali

We studied the growth and ordering of a Pb layer deposited on Cu(001) at 150 K. Contrary to the case of adsorption of Pb at room temperature, islands readily form. These islands order in a high-order commensurate structure of symmetry ( sqrt(61) x sqrt(61) ) R arctan(5/6). We followed the growth of these islands using atom beam scattering. From the measureme

Wei Li, Gianfranco Vidali

We report the discovery of a metal adatom induced corrugation of Cu(001) as probed by atom beam scattering (ABS). At Pb or Bi coverages of 0.05 (fraction of Cu layer), and while a (1$\times$1) LEED pattern is still observed, the ABS diffraction pattern from \underbar{uncovered} Cu(001) areas has changed considerably from that of clean Cu(001). We show that t

L. Bonora, C. S. Xiong

In the context of hermitean one--matrix models we show that the emergence of the NLS hierarchy and of its reduction, the KdV hierarchy, is an exact result of the lattice characterizing the matrix model. Said otherwise, we are not obliged to take a continuum limit to find these hierarchies. We interpret this result as an indication of the topological nature o

Terry Gannon

A natural first step in the classification of all `physical' modular invariant partition functions $\sum N_{LR}\,\c_L\,\C_R$ lies in understanding the commutant of the modular matrices $S$ and $T$. We begin this paper extending the work of Bauer and Itzykson on the commutant from the $SU(N)$ case they consider to the case where the underlying algebra is

Terry Gannon

Thus far in the search for, and classification of, `physical' modular invariant partition functions $\sum N_{LR}\,\c_L\,\C_R$ the attention has been focused on the {\it symmetric} case where the holomorphic and anti-holomorphic sectors, and hence the characters $\c_L$ and $\c_R$, are associated with the same Kac-Moody algebras $\g_L=\g_R$ and levels $k_L

J. R. Cudell, B. Margolis

We examine a model of hadronic diffractive scattering which interpolates between perturbative QCD and non-perturbative fits. We restrict the perturbative QCD resummation to the large transverse momentum region, and use a simple Regge-pole parametrization in the infrared region. This picture allows us to account for existing data, and to estimate the size of

Barry Friedman, Kikuo Harigaya

We consider luminescence in photo-excited neutral C_60 using the Su-Schrieffer-Heeger model applied to a single C_60 molecule. To calculate the luminescence we use a collective coordinate method where our collective coordinate resembles the displacement of the carbon atoms of the Hg(8) phonon mode and extrapolates between the ground state "dimerisation&#

David H Lyth, Andrew A Liddle

In a recent paper, we suggested that the density fluctuation spectra arising from power-law (or extended) inflation, which are tilted with respect to the Harrison--Zel'dovich spectrum, may provide an explanation for the excess large scale clustering seen in galaxy surveys such as the APM survey. In the light of the new results from COBE, we examine in de

B. Dubrovin

Misprints in the definition of semiclassical tau-function and in the formulae (3.40b) and (4.20) are corrected.

Rogier Brussee

Main difference with previous version: we prove that every differentiably embedded sphere with self intersection $-1$ in a simply connected algebraic surface with $p_g >0$ is homologous to a $(-1)$-curve if $|K_{\min}|$ contains a smooth irreducible curve of genus at least 2 and $p_g$ is even or $K_{\min}^2 \not\equiv 7 \pmod8$ (here $K_{\min}$ is the canoni

Fabian H. L. Essler, Vladimir E. Korepin, Kareljan Schoutens

We show how to construct a complete set of eigenstates of the hamiltonian of the one-dimensional Hubbard model on a lattice of even length $L$. This is done by using the nested Bethe Ansatz {\it and} the $SO(4)$ symmetry of the model. We discuss in detail how the counting of independent eigenstates is carried out.

Kohji Tomisaka, Joel N. Bregman

Reanalysis of Einstein IPC data and new observations from the GINGA LAC indicate the presence of extended X-ray emission (10-50 kpc) around the starburst galaxy M82. Here we model this emission by calculating numerical hydrodynamic simulations of the starburst event to much later times and larger scales than previously considered. For our models, we adopt a

Hao-wen Xi, J. D. Gunton, Jorge Vinals

We present a numerical study of a generalized two-dimensional Swift-Hohenberg model of spiral pattern formation in Rayleigh-Bénard convection in a non-Boussinesq fluid. We demonstrate for the first time that a model for convective motion is able to predict in considerable dynamical detail the spontaneous formation of a rotating spiral state from an ordered h

J. Avan, A. Jevicki

We propose a generalization of the collective field theory hamiltonian, including interactions between the original bosonic collective field $w_0 (z)$ and supplementary fields ${\bar w}_j (z)$ realizing classically a $w_\infty$ algebra. The latter are then shown to represent a 3--dimensional topological field theory. This generalization follows from a conjec

John Rogers, Donald Spector

We investigate quantum mechanical Hamiltonians with explicit time dependence. We find a class of models in which an analogue of the time independent §equation exists. Among the models in this class is a new exactly soluble model, the harmonic oscillator with frequency inversely proportional to time.

E. Bergshoeff, A. Sevrin, X. Shen

We derive the recently proposed BRST charge for non-critical W strings from a Lagragian approach. The basic observation is that, despite appearances, the combination of two classical ``matter'' and ``Toda'' w_3 systems leads to a closed modified gauge algebra, which is of the so-called soft type. Based on these observations, a novel way to co

Wolfgang Kalau

In this paper we discuss the BRST-quantization of anomalous 2d-Yang Mills (YM) theory. Since we use an oscillator basis for the YM-Fock-space the anomaly appears already for a pure YM-system and the constraints form a Kac-Moody algebra with negative central charge. We also discuss the coupling of chiral fermions and find that the BRST-cohomology for systems

Peter Bouwknegt, Jim McCarthy, Krzysztof Pilch

We discuss various techniques for computing the semi-infinite cohomology of highest weight modules which arise in the BRST quantization of two dimensional field theories. In particular, we concentrate on two such theories -- the $G/H$ coset models and $2d$ gravity coupled to $c\leq 1$ conformal matter. (to appear in the proceedings of the XXV Karpacz Winter

Fred C. Adams, Katherine Freese, J. S. Langer

Hadron bubbles that nucleate with radius $R_{nuc}$ in a quark sea (if the phase transition is first order) are shown to be unstable to the growth of nonspherical structure when the bubble radii exceed a critical size of $20 - 10^3$ $R_{nuc}$. This instability is driven by a very thin layer of slowly diffusing excess baryon number that forms on the surface of

Kyungsik Kang, Alan R. White

We present the minimal sextet--quark condensation model as an attractive alternative to the standard model. The model is constructed by a simple and natural extension beyond the standard model and has many new interesting features some of which can be tested readily at the existing colliders. A crucial test may be a short--lived axion-- like $η_6$ of mass 30

Vidyut Jain

We study the 3d effective theory of the high T Abelian Higgs model with N real scalars and gauge and scalar couplings denoted g and $λ$, respectively. We find for the three cases a) $6g^2/λ=0(1)$, b) $6g^2/λ=0(N)$ and c) $6g^2/λ=O(N^{2\over3})$ the following results: a) The O(N)+O(1) potential admits only a second order phase transition, b) The O(1) potentia

J. Madore

The Maxwell vector potential and the Dirac spinor used to describe the classical theory of electrodynamics both have components which are considered to be ordinary smooth functions on space-time. We reformulate electrodynamics by adding an additional structure to the algebra of these functions in the form of the algebra $M_n$ of $n \times n$ complex matrices

Christian Holm, Wolfhard Janke

We use the single-cluster Monte Carlo update algorithm to simulate the three-dimensional classical Heisenberg model in the critical region on simple cubic lattices of size $L^3$ with $L=12, 16, 20, 24, 32, 40$, and $48$. By means of finite-size scaling analyses we compute high-precision estimates of the critical temperature and the critical exponents, using

Edward Malec, Niall Ó Murchadha

The Cosmological Principle states that the universe is both homogeneous and isotropic. This, alone, is not enough to specify the global geometry of the spacetime. If we were able to measure both the Hubble constant and the energy density we could determine whether the universe is open or closed. Unfortunately, while some agreement exists on the value of the

E. J. Mele, S. C. Erwin

We study a model for anisotropic singlet pairing in $A_3{\rm C}_{60}$, using a realistic model for the Fermi surface in a hypothesized orientationally-ordered doped crystal. Anisotropic solutions are studied by combining numerical solutions to the gap equation in the low-temperature phase with a Landau expansion near the mean field critical temperature. We f

Jaime Ferrer

The existance of a spin disordered ground state for the frustrated Quantum Heisenberg Antiferromagnet on a square lattice is reconsidered. It is argued that there is a unique action which is continuous through the whole phase diagram, except at the Lifshitz point, so that the Neel and helicoidal states can not coexist and there has to be an intermediate spin

Jesus Bastero, J. Buernes, A. Pena

In this note we investigate some aspects of the local structure of finite dimensional $p$-Banach spaces. The well known theorem of Gluskin gives a sharp lower bound of the diameter of the Minkowski compactum. In [Gl] it is proved that diam$({\cal M}_n^1)\geq cn$ for some absolute constant $c$. Our purpose is to study this problem in the $p$-convex setting. I

Menachem Kojman

We prove that $μ=μ^{<μ}$, $2^μ=μ^+$ and ``there is a non reflecting stationary subset of $μ^+$ composed of ordinals of cofinality $<μ$&#39;&#39; imply that there is a $μ$-complete Souslin tree on $μ^+$.

Enrique F. Moreno

We study a theory of Dirac fermions on a disk in presence of an electromagnetic field. Using the heat-kernel technique we compute the functional determinant which results after decoupling the zero-flux gauge degrees of freedom from the fermions. We also compute the Green functions of the remaining fermionic theory with the appropriate boundary conditions. Fi

R. Brustein, B. Ovrut

New non-perturbative interactions in the effective action of two dimensional string theory are described. These interactions are due to ``stringy&#34; instantons

C. Bachas, M. Porrati

We calculate exactly the rate of pair production of open bosonic and supersymmetric strings in a constant electric field. The rate agrees with Schwinger&#39;s classic result in the weak-field limit, but diverges when the electric field approaches some critical value of the order of the string tension. (Phyzzx file)

J. E. Nelson, T. Regge

In [1,2] we established and discussed the algebra of observables for 2+1 gravity at both the classical and quantum level. Here our treatment broadens and extends previous results to any genus $g$ with a systematic discussion of the centre of the algebra. The reduction of the number of independent observables to $6g-6 (g > 1)$ is treated in detail with a prec

Lawrence M. Krauss, David Schramm

The lensing effect of curved space, which can cause the angular diameter of a fixed reference length seen on the sky to reach a minimum and then increase with redshift, depends sensitively on the value of the cosmological constant, $Λ$, in a flat universe. The redshift of an observed minimum and the asymptotic slope can in principle provide strong constraint

A. H. Chamseddine, G. Felder, J. Fröhlich

The formalism of non-commutative geometry of A. Connes is used to construct models in particle physics. The physical space-time is taken to be a product of a continuous four-manifold by a discrete set of points. The treatment of Connes is modified in such a way that the basic algebra is defined over the space of matrices, and the breaking mechanism is plante

Martin Hasenbusch

I present a cluster Monte Carlo algorithm that gives direct access to the interface free energy of Ising models. The basic idea is to simulate an ensemble that consists of both configurations with periodic and with antiperiodic boundary conditions. A cluster algorithm is provided that efficently updates this joint ensemble. The interface tension is obtained

A. Honecker

We comment on a program designed for the study of local chiral algebras and their representations in 2D conformal field theory. Based on the algebraic approach described by W. Nahm, this program efficiently calculates arbitrary n-point functions of these algebras. The program is designed such that calculations involving e.g. current algebras, W-algebras and

W. Eholzer, A. Honecker, R. Huebel

In this paper we consider the representation theory of N=1 Super-W-algebras with two generators for conformal dimension of the additional superprimary field between two and six. In the superminimal case our results coincide with the expectation from the ADE-classification. For the parabolic algebras we find a finite number of highest weight representations a

P. Menotti, G. Modanese, D. Seminara

We give a general procedure for extracting the propagators in gauge theories in presence of a sharp gauge fixing and we apply it to derive the propagators in quantum gravity in the radial gauge, both in the first and in the second order formalism in any space-time dimension. In the three dimensional case such propagators vanish except for singular collinear

E. Nardi

We study a new class of flavor changing interactions, which can arise in models based on extended gauge groups (rank $>$4) when new charged fermions are present together with a new neutral gauge boson. We discuss the cases in which the flavor changing couplings in the new neutral current coupled to the $Z^\prime$ are theoretically expected to be large, imply

David London, C. P. Burgess

We discuss several issues regarding analyses which use loop calculations to put constraints on anomalous trilinear gauge boson couplings (TGC&#39;s). Many such analyses give far too stringent bounds. This is independent of questions of gauge invariance, contrary to the recent claims of de Rujula et. al., since the lagrangians used in these calculations ARE g

M. L. Laursen

In a somewhat overlooked work by Seiberg, a definition of the topological charge for SU(N) lattice fields was given. Here, it is shown that Seibergs and Lüschers charge definition are related up to the section of the bundle. With the continued interest in baryon number violating processes, Seibergs paper is useful since it allows for a Chern-Simons number al

Alberto Bressan, Graziano Crasta

Let $F:[0,T]\times\R^n\mapsto 2^{\R^n}$ be a continuous multifunction with compact, not necessarily convex values. In this paper, we prove that, if $F$ satisfies the following Lipschitz Selection Property: \begin{itemize} \item[{(LSP)}] {\sl For every $t,x$, every $y\in \overline{co} F(t,x)$ and $\varepsilon>0$, there exists a Lipschitz selection $ϕ$ of $\ov

P. F. Bedaque, I. Horvath, S. G. Rajeev

We propose a bilocal field theory for mesons in two dimensions obtained as a kind of non local bosonization of two dimensional QCD. Its semi-classical expansion is equivalent to the $1/N_c$ expansion of QCD. Using an ansatz we reduce the classical equation of motion of this theory in the baryon number one sector to a relativistic Hartree equation and solve i

Stephen J. Montgomery-Smith

We give a formula for the tail of the distribution of the non-commutative Rademacher series, which generalizes the result that is already available in the commutative case. As a result, we are able to calculate the norm of these series in many rearrangement invariant spaces, generalizing work of Pisier and Rodin and Semyonov.

A. A. Tseytlin

We consider a $2d$ sigma model with a $2+N$ - dimensional Minkowski signature target space metric having a covariantly constant null Killing vector. We study solutions of the conformal invariance conditions in $2+N$ dimensions and find that generic solutions can be represented in terms of the RG flow in $N$ - dimensional ``transverse space&#39;&#39; theory.

Niels Gronbaek, Barry E. Johnson, George A. Willis

In this paper we study conditions on a Banach space X that ensure that the Banach algebra K(X) of compact operators is amenable. We give a symmetrized approximation property of X which is proved to be such a condition. This property is satisfied by a wide range of Banach spaces including all the classical spaces. We then investigate which constructions of ne

Andreas Blass

Let P be the direct product of countably many copies of the additive group Z of integers. We study, from a set-theoretic point of view, those subgroups of P for which all homomorphisms to Z annihilate all but finitely many of the standard unit vectors. Specifically, we relate the smallest possible size of such a subgroup to several of the standard cardinal c

Randall Dougherty, Thomas Jech

We consider algebras with one binary operation $\cdot$ and one generator ({\it monogenic}) and satisfying the left distributive law $a\cdot (b\cdot c)=(a\cdot b)\cdot (a\cdot c)$. One can define a sequence of finite left-distributive algebras $A_n$, and then take a limit to get an infinite monogenic left-distributive algebra~$A_\infty$. Results of Laver and

D. Bazeia

We show explicitly that the question of gauge invariance of the effective potential in standard scalar electrodynamics remains unchanged despite the introduction of the Chern-Simons term. The result does not depend on the presence of the Maxwell term in the Chern-Simons territory.

Sumit R. Das, S. Kalyana Rama

We study the dressing of operators and flows of corresponding couplings in models of {\it embedded} random surfaces. We show that these dressings can be obtained by applying the methods of David and Distler and Kawai. We consider two extreme limits. In the first limit the string tension is large and the dynamics is dominated by the Nambu-Goto term. We analyz

Timothy Hollowood

The first quantum mass corrections for the solitons of complex $sl(n)$ affine Toda field theory are calculated. The corrections are real and preserve the classical mass ratios. The formalism also proves that the solitons are classically stable.

Shinobu Hikami, Edouard Brézin

Two dimensional quantum gravity coupled to a conformally invariant matter field of central charge c=n/2, is represented, in a discretized version, by n independent Ising spins per cell of the triangulations of a random surface. The matrix integral representation of this model leads to a diagrammatic expansion at large orders, when the Ising coupling constant

Chris Michael

We discuss states in the meson spectrum which have explicit gluonic components. Glueballs (with no valence quarks) and hybrid mesons (with valence quarks) are both reviewed. We present in some detail lattice simulation results. ( to appear in proceedings of QCD-20 years, Aachen Workshop)

Géza Fülöp

Canonical transformations relating the variables of the ADM-, Ashtekar&#39;s and Witten&#39;s formulations of gravity are computed in 2+1~dimensions. Three different forms of the BRST-charge are given in the 2+1 dimensional Ashtekar formalism, two of them using Ashtekar&#39;s form of the constraints and one of them using the forms suggested by Witten. The BR

V. L. Libero, D. L. Cox

We present a mean-field calculation of the phase diagram of a simple model of localized moments, in the hexagonal uranium heavy-fermion compounds. The model considers a non-Kramers quadrupolar doublet ground state magnetically coupled with a singlet excited-state, favoring in-plane van-Vleck magnetism, as has been conjectured for UPt$_3$. The Hamiltonian whi

R. J. Gooding, A. Mailhot

A model of $CuO_2$ planes weakly doped with partially delocalised holes is considered. The effect of such a hole on the background AFM spin texture can be represented by a purely magnetic Hamiltonian $H = - \sum_{(ijk)} (\vec S_i \cdot \vec S_j \times \vec S_k)^2$, where the summation is over the four triangles of a single plaquette. We show that this model

Ernest Ma

It is shown by explicit calculation that the one-loop mass renormalization of the Higgs boson in the standard model is gauge-independent. It could even be rendered finite if the following mass relationships were satisfied: $m_t^2 \simeq m_H^2 = (2 M_W^2 + M_Z^2)/3$. Numerically, this would imply $m_t \simeq 84~GeV$ which is below the current experimental low

I. Antoniadis, K. Benakli

Four-dimensional string theories predict in general the existence of light exotic particles with fractional electric charges. Such particles could escape present observations if they are confined by a gauge group of the &#34;hidden&#34; sector into integrally charged states. It is conceivable that the same gauge group is also responsible for dynamical supers

Takeo Inami, Satoru Odake

We study the continuum limit of the spin-1 chain in the non-Abelian bosonization approach of Affleck and show that the Hamiltonian of integrable spin-1 chain yields the Lagrangian of supersymmetric sine-Gordon model in the zero lattice spacing limit. We also show that the quantum group generators of the spin-1 chain give non-local charges of the supersymmetr

A. A. Bytsenko, E. Elizalde, S. D. Odintsov nd S. Zerbini

Open superstrings at non-zero temperature are considered. A novel representation for the free energy (Laurent series representation) is constructed. It is shown that the Hagedorn temperature arises in this formalism as the convergence condition (specifically, the radius of convergence) of the Laurent series.

J. Lopez, D. Nanopoulos, H. Pois

We present the results of an extensive exploration of the five-dimensional parameter space of the minimal $SU(5)$ supergravity model, including the constraints of a long enough proton lifetime ($τ_p>1\times10^{32}\y$) and a small enough neutralino cosmological relic density ($Ω_χh^2_0\le1$). We find that the combined effect of these two constraints is quite

J. Blümlein, G. J. van Oldenborgh, R. Rückl

First order QCD and leading QED corrections to Higgs boson production in the channel $e^-p \to νH^0 X; H^0 \to b\bar{b}$ are calculated for the kinematical conditions at LEP $\otimes$ LHC ($\sqrt{s} = 1360 \GeV$) and the interesting mass range $80 < M_H < 150 \GeV$. In the DIS scheme the QCD corrections (not including the corrections to the branching ratio,

E. Gotsman, E. M. Levin, U. Maor

A comparative investigation of various Pomeron models is carried out through the study of their predicted values of $ σ_{tot}$, B, and $\frac{σ_{el}}{σ_{tot}}$ in high energy pp and p$\bar{p}$ scattering. Our results strongly support a picture of the Pomeron in which we have both moderate blackening and expansion of the p($\bar{p}$) - p amplitude in impact p

Martin Hasenbusch, Klaus Pinn

We compute properties of the interface of the 3-dimensional Ising model for a wide range of temperatures, covering the whole region from the low temperature domain through the roughening transition to the bulk critical point. The interface tension sigma is obtained by integrating the surface energy density over the inverse temperature beta. We use lattices o

C. B. Lang, U. Winkler

We study the one component $Φ^4$ model for four different lattice actions in the Gaussian limit and for the Ising model in the broken phase. Emphasis is put on the euclidean invariance properties of the boson propagator. A measure of the violation of rotational symmetry serves as a tool to compare the regularization dependence of the triviality bound.

Rolf Schimmrigk

The construction of mirror symmetry in the heterotic string is reviewed in the context of Calabi-Yau and Landau-Ginzburg compactifications. This framework has the virtue of providing a large subspace of the configuration space of the heterotic string, probing its structure far beyond the present reaches of solvable models. The construction proceeds in two st

B. Mueller, M. H. Thoma

We show that higher-order vacuum polarization would contribute a measureable net charge to atoms, if the charges of electrons and positrons do not balance precisely. We obtain the limit $|Q_e+Q_{\bar e}| < 10^{-18} e$ for the sum of the charges of electron and positron. This also constitutes a new bound on certain violations of PCT invariance.

David Garfinkle

A family of solutions to low energy string theory is found. These solutions represent waves traveling along &#34;extremal black strings&#34;

Akishi Kato, Yas-Hiro Quano, Jun&#39;ichi Shiraishi

A bosonization scheme of the $q$-vertex operators of $\uqa$ for arbitrary level is obtained. They act as intertwiners among the highest weight modules constructed in a bosonic Fock space. An integral formula is proposed for $N$-point functions and explicit calculation for two-point function is presented.

J. Shiraishi

A representation of the quantum affine algebra $U_{q}(\hat{sl_{2}})$ of an arbitrary level $k$ is realized in terms of three boson fields, whose $q \rightarrow 1$ limit becomes the Wakimoto representation. An analogue of the screening current is also obtained. It commutes with the action of $U_{q}(\hat{sl_{2}})$ modulo total difference of some fields.

G. Papadopoulos

An on-shell formulation of (p,q), 2\leq p \leq 4, 0\leq q\leq 4, supersymmetric coset models with target space the group G and gauge group a subgroup H of G is given. It is shown that there is a correspondence between the number of supersymmetries of a coset model and the geometry of the coset space G/H. The algebras of currents of supersymmetric coset model

Ashoke Sen

We analyze the allowed spectrum of electric and magnetic charges carried by dyons in (toroidally compactified) heterotic string theory in four dimensions at arbitrary values of the string coupling constant and $θ$ angle. The spectrum is shown to be invariant under electric-magnetic duality transformation, thereby providing support to the conjecture that this

A. J. Millis, H. Monien

A magnetic susceptibility which decreases with decreasing temperature is observed in all $CuO_2$ based superconductors with less than optimal doping. We propose that in $La_{2-x} Sr_x CuO_4$ this is due to antiferromagnetic ordering which is prevented by the low spatial dimensionality while in $YBa_2 Cu_3 O_{6.6}$ it is due to the interplay between antiferro

H. Monien

One of the interesting aspects of the CuO superconductors is that superconductivity is happening so close to the antiferromagnetic state. The nuclear magnetic resonance and the recent neutron scattering experiments clearly indicate that magnetic correlations persist in to the heavily doped regime. In this paper we will discuss some of the details of the coup

J. Chyla, A. Kataev

We present the next-to-next-to-leading order QCD analysis of the Gross-Llewellyn Smith (GLS) sum rule in deep inelastic lepton-nucleon scattering, taking into account dimension-two, twist-four power correction. We discuss in detail the renormalization scheme dependence of the perturbative QCD approximations, propose a procedure for an approximate treatment o

Annie C. Robin, Michel Creze, Vijay Mohan

Three colour photometry on CCD frames in the Special Area SpA23 provides a deep probe of the galactic disc in a low absorption window towards the anticenter. Magnitudes to better than 10% at V = 25 and B-V colour down to V = 23 have been obtained. These new data, used in combination with lower magnitude photographic data in a wider field, give a strong evide

J. Russo, L. Susskind, L. Thorlacius

A weak version of the cosmic censorship hypothesis is implemented as a set of boundary conditions on exact semi-classical solutions of two-dimensional dilaton gravity. These boundary conditions reflect low-energy matter from the strong coupling region and they also serve to stabilize the vacuum of the theory against decay into negative energy states. Informa

Yong-Shi Wu, Chuan-Jie Zhu

We determine explicitly all structure constants of the whole chiral BRST cohomology ring in $D=2$ string theory including both the discrete states and tachyon states. This is made possible by establishing several identities for Schur polynomials with operator argument and exploring associativity. Furthermore we find that the (chiral) symmetry algebra of the

John Ellis, N. E. Mavromatos, D. V. Nanopoulos

Our answer is the latter. Space-time singularities, including the initial one, are described by world-sheet topological Abelian gauge theories with a Chern-Simons term. Their effective $N=2$ supersymmetry provides an initial fixed point where the Bogomolny bound is saturated on the world-sheet, corresponding to an extreme Reissner-Nordstrom solution in space

David Bowser-Chao, Debra L. Dzialo

The use of neural networks for signal vs.~background discrimination in high-energy physics experiment has been investigated and has compared favorably with the efficiency of traditional kinematic cuts. Recent work in top quark identification produced a neural network that, for a given top quark mass, yielded a higher signal to background ratio in Monte Carlo

K. S. Babu, R. N. Mohapatra

We show that minimal SO(10) Grand Unification models where the fermions have Yukawa couplings to only one (complex) {\bf 10} and one {\bf 126} of Higgs scalars lead to a very predictive neutrino spectrum. This comes about since the standard model doublet contained in the {\bf 126} of Higgs (needed for the see--saw mechanism) receives an induced vacuum expect

K. S. Babu, Q. Shafi

We present an ansatz for the quark and lepton mass matrices, derivable from SO(10) type GUTs, which accommodates a heavy $(> 92 GeV)$ top quark and permits large mixings in the $ν_μ\leftrightarrow ν_τ$ sector (as suggested by the recent Kamiokande and IMB data on the atmospheric neutrinos). The well known asymptotic relations $m_b = m_τ$, $m_s = \frac{1}{3}

Fred Cooper

Lectures Given at the Nato Advanced Study Institute-Particle Production in Highly Excited Matter Il Ciocco, Italy July 1992 figure available on request. Input harvmac.tex

P. Butera, M. Comi

High temperature series expansions of the spin-spin correlation function for the plane rotator (or XY) model on the square lattice are extended by three terms through order $β^{20}$. Tables of the expansion coefficients are reported for the correlation function spherical moments of order $l=0,1,2$. The expansion coefficients through $β^{15}$ for the vorticit

A. Kocic, J. B. Kogut, M. -P. Lombardo

We discuss chiral symmetry breaking critical points from the perspective of PCAC, correlation length scaling and the chiral equation of state. A scaling theory for the ratio $R_π$ of the pion to sigma masses is presented. The Goldstone character of the pion and properties of the longitudinal and transverse chiral susceptibilities determine the ratio $R_π$ wh

A. Kocic, J. B. Kogut, K. C. Wang

We simulate four flavor noncompact lattice QED using the Hybrid Monte Carlo algorithm on $10^4$ and $16^4$ lattices. Measurements of the monopole susceptibility and the percolation order parameter indicate a transition at $β= {1/e^2} = .205(5)$ with critical behavior in the universality class of four dimensional percolation. We present accurate chiral conden

A. J. Schofield, J. M. Wheatley

The rule relating the observed Hall coefficient to the spin and charge responses of the uniform doped Mott insulator is derived. It is essential to include the contribution of holon and spinon three-current correlations to the effective action of the gauge field. In the vicinity of the Mott insulating point the Hall coefficient is holon dominated and weakly