arXiv papers from October 1992

B. Fields, S. Dodelson, M. S. Turner

We have modified the standard code for primordial nucleosynthesis to include the effect of the slight heating of neutrinos by $e^\pm$ annihilations. There is a small, systematic change in the $^4$He yield, $\Delta Y \simeq +1.5\times 10^{-4}$, which is insensitive to the value of the baryon-to-photon ratio $\eta$ for $10^{-10}\la \eta \la 10^{-9}$. We also f

Jeffrey E. Mandula, Michael C. Ogilvie

We construct the Isgur-Wise limit of QCD in a form appropriate to lattice gauge theory techniques. The formulation permits a calculation of heavy quark processes even when the momentum transfers are much larger than the inverse lattice spacing. Applications include semi-leptonic heavy quark decay and scattering processes, including the computation of the non

Gerald Gilbert, Eric Raiten

A comprehensive analysis of small fluctuations about two-dimensional string-theoretic and string-inspired black holes is presented. It is shown with specific examples that two-dimensional black holes behave in a radically different way from all known black holes in four dimensions. For both the $SL(2,R)/U(1)$ black hole and the two-dimensional black hole cou

David Gershon

We show that several WZW coset models can be obtained by applying O(d,d) symmetry transformations (referred to as twisting) on WZW models. This leads to a conjecture that WZW models gauged by U(1)^n subgroup can be obtained by twisting (ungauged) WZW models. In addition, a class of solutions that describe charged black holes in four dimensions is derived by

I. Dolgachev, M. Gross

We calculate the Tate-Shafarevich group of an elliptic three-fold $f:X\rightarrow S$ when $X$ and $S$ are regular and $f$ is flat, relating it to the Brauer group of $X$ and $S$. We show that given certain hypotheses on $f$, the Tate-Shafarevich group has the interpretation of isomorphism classes of elliptic curves over the function field of $S$ which have t

H. O. Girotti, M. Gomes, J. L. deLyra, R. S. Mendes

This paper is dedicated to the study of the existence and the properties of electron-electron bound states in QED$_3$. A detailed analysis of the infrared structure of the perturbative series of the theory is presented. We start by analyzing the two-point Green's function, in the Bloch-Nordsieck approximation. The theory appears to be plagued by severe infra

Zongan Qiu

We consider a string theory with two types of strings with geometric interaction. We show that the theory contains strings with constant Dirichlet boundary condition and those strings are glued together by 2-d topological gravity with macroscopic boundaries. A light-cone string field theory is given and the theory has interactions to all orders. (Postscript

Feng Yu, Yong-Shi Wu

We give a unified description of our recent results on the the inter-relationship between the integrable infinite KP hierarchy, nonlinear $\hat{W}_{\infty}$ current algebra and conformal noncompact $SL(2,R)/U(1)$ coset model both at the classical and quantum levels. In particular, we present the construction of a quantum version of the KP hierarchy by deform

Fay Dowker

The phenomenon of linearisation instability is identified in models of quantum cosmology that are perturbations of mini-superspace models. In particular, constraints that are second order in the perturbations must be imposed on wave functions calculated in such models. It is shown explicitly that in the case of a model which is a perturbation of the mini-sup

S. J. Gates,, H. Nishino

We perform dimensional reductions of recently constructed self-dual $~N=2$~ {\it supersymmetric} Yang-Mills theory in $~2+2\-$dimensions into two-dimensions. We show that the universal equations obtained in these dimensional reductions can embed supersymmetric exactly soluble systems, such as $~N=1$~ and $~N=2$~ supersymmetric Korteweg-de Vries equations, $~

P. K. Lin

Let $X$ be a reflexive Banach space such that for any $x \ne 0$ the set $$ \{x^* \in X^*: \text {$\|x^*\|=1$ and $x^*(x)=\|x\|$}\} $$ is compact. We prove that any unrestricted product of of a finite number of $(W)$ contractions on $X$ converges weakly.

Spiros A. Argyros

The class of countably intersected families of sets is defined. For any such family we define a Banach space not containing $\ell^{1}(\NN )$. Thus we obtain counterexamples to certain questions related to the heredity problem for W.C.G. Banach spaces. Among them we give a subspace of a W.C.G. Banach space not containing $\ell^{1}(\NN )$ and not being itself

Paul F. X. Müller

The real part of $H^\infty(\bT)$ is not dense in $L^\infty_{\tR}(\bT)$. The John-Nirenberg theorem in combination with the Helson-Szeg\"o theorem and the Hunt Muckenhaupt Wheeden theorem has been used to determine whether $f\in L^\infty_{\tR}(\bT)$ can be approximated by $\Re H^\infty(\bT)$ or not: $\dist(f,\Re H^\infty)=0$ if and only if for every $\e>0$ th

Joerg Wenzel

Given any Banach space $X$, let $L_2^X$ denote the Banach space of all measurable functions $f:[0,1]\to X$ for which ||f||_2:=(int_0^1 ||f(t)||^2 dt)^{1/2} is finite. We show that $X$ is a UMD--space (see \cite{BUR:1986}) if and only if \lim_n||f-S_n(f)||_2=0 for all $f\in L_2^X$, where S_n(f):=sum_{i=0}^{n-1} (f,w_i)w_i is the $n$--th partial sum associated

Jan Myrheim, Kåre Olaussen

We use a path integral representation for the partition function of non-interacting anyons confined in a harmonic oscillator potential in order to prove that the third virial coefficient of free anyons is finite, and to calculate it numerically. Our results together with previously known results are consistent with a rapidly converging Fourier series in the

G. P. Korchemsky, G. Marchesini

We discuss the relation between partonic distributions near the phase space boundary and Wilson loop expectation values calculated along paths partially lying on the light-cone. Due to additional light-cone singularities, multiplicative renormalizability for these expectation values is lost. Nevertheless we establish the renormalization group equation for th

J. Lopez, D. Nanopoulos, A. Zichichi

We present the simplest, string-derivable, supergravity model and discuss its experimental consequences. This model is a new string-inspired flipped $SU(5)$ which unifies at the string scale $M_U=10^{18}\GeV$ due to the introduction of an additional pair of \r{10},\rb{10} flipped $SU(5)$ representations which contain new intermediate scale `gap' particles. W

H. O. Girotti, M. Gomes, J. L. deLyra, R. S. Mendes

Vacuum polarization effects are non-perturbatively incorporated into the photon propagator to eliminate the severe infrared problems characteristic of QED$_3$. The theory is thus rephrased in terms of a massive vector boson whose mass is $e^2/(8\pi)$. Subsequently, it is shown that electron-electron bound states are possible in QED$_3$.

Stefan Forste

We consider correlation functions in Neveu--Schwarz string theory coupled to two dimensional gravity. The action for the 2D gravity consists of the string induced Liouville action and the Jackiw--Teitelboim action describing pure 2D gravity. Then gravitational dressed dimensions of vertex operators are equal to their bare conformal dimensions. There are two

S. Das Gupta, C. Gale, K. Haglin

We show that the coalescence model for fragment formation leads to an approximate site percolation model. Features characteristic of a percolation model also appear in microscopic models of disassembly.

Biswarup Mukhopadhyaya, D. P. Roy

The dimuon and dielectron data from the Tevatron $\bar pp$ collider are used to probe for heavy quarks, which decay dominantly via flavour changing neutral current. Depending on whether the $FCNC$ decay occurs at the tree or loop level, one gets a lower mass limit of 85 or 75 GeV. The former applies to singlet, vector doublet and mirror type quarks while the

B. Grossmann, M. L. Laursen, T. Trappenberg, U. J. Wiese

We present results for the confinement-deconfinement interface tension $\alpha_{cd}$ of quenched QCD. They were obtained by applying Binder's histogram method to lattices of size $L^2\times L_z\times L_t$ for $L_t=2$ and $L=8,10,12\mbox{ and }14$ with $L_z=30$ for $L=8$ and $L_z=3L$ otherwise. The use of a multicanonical algorithm and cylindrical geometries

Tatsuo Kobayashi, Tsuneo Uematsu

We investigate quantum deformation of conformal algebras by constructing the quantum space for $sl_q(4,C)$. The differential calculus on the quantum space and the action of the quantum generators are studied. We derive deformed $su(4)$ and $su(2,2)$ algebras from the deformed $sl(4)$ algebra using the quantum 4-spinor and its conjugate spinor. The 6-vector i

Vidyut Jain, Aris Papadopoulos

We study the effective field theory of a weakly coupled 3+1d gauged $\phi^4$ type model at high temperature. Our model has $4N$ real scalars ($N$ complex Higgs doublets) and a gauge group $SU(2)$ which is spontaneously broken by a nonzero scalar field $vev$ at zero temperature. We find, for sufficiently large $N$, that the transition from the high temperatur

Apoorva Patel, Stephen Sharpe

We calculate the perturbative corrections to fermion bilinears that are used in numerical simulations when extracting weak matrix elements using staggered fermions. This extends previous calculations of Golterman and Smit, and Daniel and Sheard. In particular, we calculate the corrections for non-local bilinears defined in Landau gauge with gauge links exclu

J. D. Cohn, Vipul Periwal

This TASI lecture covers the material in hep-th/9205026. It reviewed the theory of effective strings, with particular emphasis on the manner in which Lorentz invariance is represented. The quantum properties of an example of an effective string are derived from the underlying field theory. A comparison is made with what one would expect if one assumed that q

P. Benassi, O. Pilla, G. Viliani, G. Ruocco

The frequency dependence of the Raman coupling coefficient $C(ω)$ is calculated numerically for square and cubic percolation clusters. No general scaling law in terms of the macroscopic parameters such as the fractal dimension $D$ or the spectral dimension $\overline d$ is found. $C(ω)$ is sensitive to the microscopic structure of the clusters and depends on

Ethan T. Vishniac

The galactic magnetic field is commonly supposed to be due to a dynamo acting on some large scale seed field. A major difficulty with this idea is that estimates of reasonable seed field strengths tend to be quite low, on the order of $\sim10^{-20}$ gauss. Here we examine the contribution due to the flux entrained in winds from protostars formed in the first

O. J. P. Eboli, M. C. Gonzalez-Garcia, F. Halzen, S. F. Novaes

The exchange of gluons between heavy quarks produced in $e^+e^-$ interactions results in an enhancement of their production near threshold. We study QCD threshold effects in $\gamma\gamma$ collisions. The results are relevant to heavy quark production by beamstrahlung and laser back-scattering in future linear collider experiments. Detailed predictions for t

L. A. Dickey

As in the first part of this paper (hep-th 9204092), solutions to a string equation are regarded as fixed points of some additional symmetries of a hierarchy of integrable equations. In this part matrix hierarchies are studied: the multi-component KP and KdV hierarchies, and the modified KdV hierarchy as their reduction. In particular, the action of addition

A. Kovner, B. Rosenstein

We develop the dual picture for Quantum Electrodynamics in 3+1 dimensions. It is shown that the photon is massless in the Coulomb phase due to spontaneous breaking of the magnetic symmetry group. The generators of this group are the magnetic fluxes through any infinite surface $\Phi_S$. The order parameter for this symmetry breaking is the operator $V(C)$ wh

R. Sekhar Chivukula, Mitchell Golden, Elizabeth H. Simmons

We consider the constraints that critical dynamics places on models with a top quark condensate or strong extended technicolor (ETC). These models require that chiral-symmetry-breaking dynamics at a high energy scale plays a significant role in electroweak symmetry breaking. In order for there to be a large hierarchy between the scale of the high energy dyna

G. Burdman

The scaling behavior of semileptonic form-factors in Heavy to Light transitions is studied in the Heavy Quark Effective Theory. In the case of $H\rightarrow \pi e\nu$ it is shown that the same scaling violations affecting the heavy meson decay constant will be present in the semileptonic form-factors.

A. Galperin, O. Ogievetsky

A reference has been corrected

Jae-Suk Park

We introduce the covariant forms for the non-Abelian anomaly counterparts in topological Yang-Mills theory, which satisfies the topological descent equation modulo terms that vanish at the space of BRST fixed points. We use the covariant anomalies as a new set of observables, which can absorb both $\dw$ and $\db$ ghost number violations of zero-modes. Then,

R. Sekhar Chivukula, Andrew G. Cohen, Michael Luke, Martin J. Savage

We estimate the cross section for the scattering of a slow, color-neutral technibaryon made of colored constituents with nuclei. We find a cross section of order $A^2\ 10^{-45}$ cm$^2$, where $A$ is the atomic number of the nucleus. Even if technibaryons constitute the dark matter in the galactic halo, this is too small to be detected in future underground d

Ladislav Hlavaty

A new type of algebras that represent a generalization of both quantum groups and braided groups is defined. These algebras are given by a pair of solutions of the Yang--Baxter equation that satisfy some additional conditions. Several examples are presented.

A. J. van der Sijs

Recently, Duncan and Mawhinney introduced a method to find saddle points of the action in simulations of non-abelian lattice gauge theory. The idea, called `extremization', is to minimize $\int(\delta S/\delta A_\mu)^2$ instead of the action $S$ itself as in conventional `cooling'. The method was implemented in an explicitly gauge variant way, however, and g

Kevin Cahill

In theories with spontaneous symmetry breaking, the conventional effective potential possesses a defective loop expansion. For such theories, the exact effective potential $V(\phi_c,T)$ is real and convex, but its perturbative series is complex and concave at small $\phi_c$ and $T$. A more effective potential is available.

Carlangelo Liverani, Maciej P. Wojtkowski

We discuss the Sinai method of proving ergodicity of a discontinuous Hamiltonian system with (non-uniform) hyperbolic behavior.

Peter Schupp, Paul Watts, Bruno Zumino

A bicovariant calculus of differential operators on a quantum group is constructed in a natural way, using invariant maps from \fun\ to \uqg\ , given by elements of the pure braid group. These operators --- the `reflection matrix' $Y \equiv L^+ SL^-$ being a special case --- generate algebras that linearly close under adjoint actions, i.e. they form generali

Ian H. Redmount, Wai-Mo Suen

The simple physics of a free particle reveals important features of the path-integral formulation of relativistic quantum theories. The exact quantum-mechanical propagator is calculated here for a particle described by the simple relativistic action proportional to its proper time. This propagator is nonvanishing outside the light cone, implying that spaceli

Wai-Mo Suen

Simon argued that the semi-classical theory of gravity, unless with some of its solutions excluded, is unacceptable for reasons of both self-consistency and experiment, and that it has to be replaced by a constrained semi-classical theory. We examined whether the evidence is conclusive.

Ian H. Redmount, Wai-Mo Suen

A very simple wormhole geometry is considered as a model of a mode of topological fluctutation in Planck-scale spacetime foam. Quantum dynamics of the hole reduces to quantum mechanics of one variable, throat radius, and admits a WKB analysis. The hole is quantum-mechanically unstable: It has no bound states. Wormhole wave functions must eventually leak to l

Edward Seidel, Wai-Mo Suen

Progress in numerical relativity has been hindered for 30 years because of the difficulties of avoiding spacetime singularities in numerical evolution. We propose a scheme which excises a region inside an apparent horizon containing the singularity. Two major ingredients of the scheme are the use of a horizon-locking coordinate and a finite differencing whic

Mauel Drees, Mihoko M. Nojiri

We discuss coherent scattering between supersymmetric neutralinos and nuclei via an effective neutralino-gluon interaction. We identify two new classes of diagrams which are not treated in the existing literature. These occur at the same order of perturbation theory as the previously considered diagrams. The new contributions can be numerically important, an

Wei Chen, Miao Li

By computing anomalous dimensions of gauge invariant composite operators $(\bar\psi\psi)^n$ and $(\phi^*\phi)^n$ in Chern-Simons fermion and boson models, we address that Chern-Simons interactions make these operators more relevant or less irrelevant in the low energy region. We obtain a critical Chern-Simons fermion coupling, ${1\over \kappa_c^2} = {6\over

P. H. Frampton, Daniel Ng, T. W. Kephart, T. C. Yuan

The lepton family number violation $Z$ boson decay, $Z \to e^-e^-\mu^+\mu^+$ or $e^+e^+\mu^-\mu^-$, mediated by a dilepton, e.g. from an SU(15) theory, is calculated. The branching ratio of such exotic decay for allowed dilepton masses is found to be smaller than 10$^{-10}$.

Paul H. Frampton, Daniel Ng, Marc Sher, Yao Yuan

Four models are considered which contain heavy leptons beyond the three families of the standard model. Two are fourth-generation extensions of the standard model in which the right-handed heavy leptons are either isosinglets or in an isodoublet; the other two are motivated by the aspon model of CP violation. In all these models, the heavy neutrino can eithe

Wei Li, Chang-Pu Sun, Mo-Lin Ge

In this paper we construct a new quantum double by endowing the l-state bosonalgebra with a non-trivial Hopf algebra structure,which is not a q-deformation of the Lie algebra or superalgebra.The universal R-matrix for the Yang-Baxter equation associated with this new quantum group structure is obtained explicitly.By building the representations of this quant

H. R. Fiebig, R. M. Woloshyn

Scattering phase shifts of a meson-meson system in staggered 3-dimensional lattice QED are computed. The main task of the simulation is to obtain a discrete set of two-body energy levels. These are extracted from a 4-point time correlation matrix and then used to obtain scattering phase shifts. The results for the l=0 and l=2 partial waves are consistent wit

Brett van de Sande, Stephen Pinsky

During the last few years, interest has arisen in using light-front Tamm-Dancoff field theory to describe relativistic bound states for theories such as QCD. Unfortunately, difficult renormalization problems stand in the way. We introduce a general, non-perturbative approach to renormalization that is well suited for the ultraviolet and, presumably, the infr

Rinat Kedem

We demonstrate the relation of the infrared anomaly of conformal field theory with entropy considerations of finite temperature thermodynamics for the 3-state Potts chain. We compute the free energy and compute the low temperature specific heat for both the ferromagnetic and anti-ferromagnetic spin chains, and find the central charges for both.

G. Gompper, D. M. Kroll

The conformation and scaling properties of self-avoiding fluid vesicles with zero extrinsic bending rigidity subject to an internal pressure increment $\Delta p>0$ are studied using Monte Carlo methods and scaling arguments. With increasing pressure, there is a first-order transition from a collapsed branched polymer phase to an extended inflated phase. The

George Bathas, Herbert Neuberger

We consider the most general renormalizable chiral Yukawa model with $SU(3)_{\rm color}$ replaced by $SU(N_c)$, $SU(2)_{\rm L}$ replaced by $SU(N_w )$ and $U(1)_{Y}$ replaced by $U(1)^{N_w -1}$ in the limit $N_c \rightarrow\infty$, $N_w \rightarrow\infty$ with the ratio $\rho=\sqrt{{N_w}\over{N_c}} \ne 0,\infty$ held fixed. Since for $N_w \ge 3$ only one ren

S. Randjbar--Daemi, Abdus Salam, J. Strathdee

A generalization of the $SU(2)$--spin systems on a lattice and their continuum limit to an arbitrary compact group $G$ is discussed. The continuum limits are, in general, non--relativistic $\sigma$--model type field theories targeted on a homogeneous space $G/H$, where $H$ contains the maximal torus of $G$. In the ferromagnetic case the equations of motion d

Katsushi Ito

We discuss the $N=2$ super $W$ algebras from the hamiltonian reduction of affine Lie superalgebras $A(n|n-1)^{(1)}$ and $A(n|n)^{(1)}$. From the quantum hamiltonian reduction of $A(n|n-1)^{(1)}$ we get the free field realization of $N=2$ $CP_{n}$ super coset models. In the case of the affine Lie superalgebras $A(n|n)^{(1)}$, the corresponding conformal field

Sergei V. Zenkin

A formulation of chiral gauge theories on a lattice which is both reflection positive and gauge invariant is discussed.

Albrecht Klemm, Stefan Theisen

We review recent advances towards the computation of string couplings. Duality symmetry, mirror symmetry, Picard-Fuchs equations, etc. are some of the tools.

Jaume Casademunt, Wenbin Zhang, Jorge Vinals, R. F. Sekerka

We introduce a stochastic model to analyze in quantitative detail the effect of the high frequency components of the residual accelerations onboard spacecraft (often called g-jitter) on fluid motion. The residual acceleration field is modeled as a narrow band noise characterized by three independent parameters: its intensity $G^{2}$, a dominant frequency $Ω$

S. Majid

The $q$-Poincar\'e group of \cite{SWW:inh} is shown to have the structure of a semidirect product and coproduct $B\cocross \widetilde{SO_q(1,3)}$ where $B$ is a braided-quantum group structure on the $q$-Minkowski space of 4-momentum with braided-coproduct $\und\Delta \vecp=\vecp\tens 1+1\tens \vecp$. Here the necessary $B$ is not a usual kind of quantum gro

Khalil M. Bitar, Pavlos Vranas

A Monte Carlo simulation of the $O(4)$ $\lambda \phi^4$ theory in the broken phase is performed on a hypercubic lattice in search of an $I=1$, $J=1$ resonance. We investigate the region of the cutoff theory where the interaction is strong as it is there that a resonance would be expected to have a better chance to form. In that region the presence of an $I=1

B. Blok, M. Shifman

QCD-based analysis of nonfactorizable parts of weak nonleptonic amplitudes is reported. Nonperturbative effects due to soft gluon exchange play a key role leading to the emergence of a dynamical rule of discarding $1/N_c$ corrections.

Cristina Manuel

We present a two-loop computation of the beta functions and the anomalous dimensions of a $\gamma_5$-Yukawa model using differential renormalization. The calculation is carried out in coordinate space without modifying the space-time dimension and no ad-hoc prescription for $\gamma_5$ is needed. It is shown that this procedure is specially suited for theorie

A. K. Tollsten

The equations of motion of anomaly-free supergravity are shown to fulfil (to all orders in $\alpha'$) a differential condition corresponding to the one relating the Weyl anomaly coefficients for a non-linear sigma model representing a (heterotic) string propagating in a non-trivial background. This supports the possibility that anomaly-free supergravity coul

Mannque Rho

I discuss recent development on the description of heavy-quark (such as charmed and bottom) baryons as one or more heavy mesons "wrapped" by a skyrmion. Amazingly enough, such a description naturally arises when light-quark chiral symmetry and heavy-quark spin symmetry are incorporated in an effective Lagrangian. I interpret the resulting spectrum in terms o

C. Ford, D. R. T. Jones, P. W. Stephenson, M. B. Einhorn

We discuss renormalisation group improvement of the effective potential both in general and in the context of $O(N)$ scalar $\p^4$ and the Standard Model. In the latter case we find that absolute stability of the electroweak vacuum implies that $m_H\geq 1.95m_t-189~GeV$, for $\as (M_Z) = 0.11$. We point out that the lower bound on $m_H$ {\it decreases\/} if

Paul Hoyer

In heavy quark production at large Feynman $x$ there are two hardness scales, one given by the heavy quark pair mass $\M^2$\ and the other by $\Lambda_{QCD}^2/(1-x)$. When these two scales are comparable, the twist expansion of Perturbative QCD breaks down. We discuss the dynamics in this new QCD limit, where $\mu^2=\M^2(1-x)$ is held fixed as $\M^2\to \inft

A. Brignole, F. Zwirner

We set up a suitable renormalization programme for the one-loop computation of the decay rate Gamma(H==>hh) in the Minimal Supersymmetric extension of the Standard Model. We then perform an explicit diagrammatic calculation, including the full contributions from top, bottom, stop and sbottom loops. We find that, for tan(beta) close to 1, and m_H greater than

Elizabeth Jenkins, Michael Luke, Aneesh V. Manohar, Martin J. Savage

The parity-conserving $a$ and parity-violating $b$ amplitudes for weak radiative hyperon decay are studied using chiral perturbation theory. The imaginary parts of $a$ and $b$ are computed using unitarity. The real part of $b$ is dominated by a one-loop infrared divergent graph which is computed. The real part of $a$ has a large theoretical uncertainty and c

Kazuhiko Odaka

When the $q$-deformed creation and annihilation operators are used in a second quantization procedure, the algebra satisfied by basis vectors (orthogonal complete set) should be also deformed such as a field operator remains invariant under the coaction of the quantum group. In the 1+1 dimensional quantum field theories we deform the algebra of the basis vec

Jindřich Zapletal

We can generalize the definition of {\it splitting number } $s(\kappa )$ for $\kappa$ uncountable regular: $s(\kappa )=min\{ |\Cal S|:\Cal S\subset \Cal P(\kappa ) \forall a\in \kappa ^\kappa \exists b\in \Cal S |a\cap b|=|a\setminus b|=\kappa\}$ However,$\exists \kappa>\aleph_0$ $s(\kappa )>\kappa ^+$ becomes a considerable hypothesis,shown consistent from

H. C. Eggers, H-Th. Elze, I. Sarcevic

A statistical field theory of particle production is presented using a gaussian functional in three dimensions. Identifying the field with the particle density fluctuation results in zero correlations of order three and higher, while the second order correlation function is of a Yukawa form. A detailed scheme for projecting the theoretical three-dimensional

I. Sarcevic

We review recent experimental results on intermittency and multidimensional particle correlations in high-energy leptonic, hadronic and nuclear collisions. We discuss different theoretical models, including self-similar cascading and QCD parton showers, models with phase transitions and the three-dimensional statistical field theory for multiparticle density

Jeremy Schiff

I report on work on a Lagrangian formulation for the simplest 1+1 dimensional integrable hierarchies. This formulation makes the relationship between conformal field theories and (quantized) 1+1 dimensional integrable hierarchies very clear.

S. Guruswamy, S. G. Rajeev

We study two dimensional Quantum Chromodynamics with massive quarks on a cylinder in a light--cone formalism. We eliminate the non--dynamical degrees of freedom and express the theory in terms of the quark and Wilson loop variables. It is possible to perform this reduction without gauge fixing. The fermionic Fock space can be defined independent of the gauge

K. C. K. Chan, R. B. Mann

Various physical properties of cosmological models in (1+1) dimensions are investigated. We demonstrate how a hot big bang and a hot big crunch can arise in some models. In particular, we examine why particle horizons do not occur in matter and radiation models. We also discuss under what circumstances exponential inflation and matter/radiation decoupling ca

Alice Rogers

(Replacement because mailer changed `hat' for supercript into something weird. The macro `\sp' has been used in place of the `hat' character in this revised version.) Fermionic Brownian paths are defined as paths in a space para\-metr\-ised by anticommuting variables. Stochastic calculus for these paths, in conjunction with classical Brownian paths, is descr

M. Caselle, F. Gliozzi, S. Vinti

The effective string describing the large distance behaviour of the quark sources of gauge field theories in the confining phase in D=3 or D=4 space-time dimensions can be formulated, in the infrared limit, as a suitable 2D conformal field theory on surfaces with quark loops as boundaries. Recent results on self-avoiding random surfaces allow to fix almost u

M. D. Freeman, P. West

The group theoretic method is extended to include fields with a background charge. This formalism is used to compute the tree level scattering for $W_3$ strings. The scattering amplitudes involve Ising model correlation functions. A detailed study of the four tachyon amplitude shows that the $W_3$ string must possess additional states in its spectrum associa

P. Cea, L. Cosmai

We investigate the dual superconductor mechanism of confinement for pure SU(2) lattice gauge theory in the maximally abelian gauge. We focus on the the dual Meissner effect. We find that the transverse distribution of the longitudinal chromoelectric field due to a static quark-antiquark pair satisfies the dual London equation. Moreover we show that the size

Qi-Ren Zhang, Bo-Qiang Ma, Walter Greiner

We confirmed the following idea by numerical calculation: The extended structure of baryons may make the nuclear equation of state stiffer at higher density while keeping the compression modulus for normal nuclear matter around its empirical value $K=240MeV$.The model built in this wayy fits all empirical data for normal nuclear matter and gives the mass lim

Stanley J. Brodsky, Paul Hoyer

We derive a quantum mechanical upper bound on the amount of radiative energy loss suffered by high energy quarks and gluons in nuclear matter. The bound shows that the nuclear suppression observed in quarkonium production at high $x_F$ cannot be explained in terms of energy loss of the initial or final parton states. We also argue that no nuclear suppression

A. M. El Gradechi, S. De Bièvre

In this work we propose an alternative description of the quantum mechanics of a massive and spinning free particle in anti-de~Sitter spacetime, using a phase space rather than a spacetime representation. The regularizing character of the curvature appears clearly in connection with a notion of localization in phase space which is shown to disappear in the z

J. L. Vazquez-Bello

This paper reviews the covariant formalism of N=1, D=10 classical superparticle models. It discusses the local invariances of a number of superparticle actions and highlights the problem of finding a covariant quantization scenario. Covariant quantization has proved problematic, but it has motivated in seeking alternative approaches that avoids those found i

Robert H. Brandenberger

The COBE satellite has discovered anisotropies in the cosmic microwave background (CMB) consistent with a scale invariant spectrum of density perturbations. As reviewed in this lecture, topological defect models of structure formation generically produce such a spectrum. We give a summary of the cosmic string and global texture models, focusing on distinct o

Robert H. Brandenberger

We construct an effective action for gravity in which all homogeneous solutions are nonsingular. In particular, there is neither a big bang nor a big crunch. The action is a higher derivative modification of Einstein's theory constructed in analogy to how the action for point particle motion in special relativity is obtained from Newtonian mechanics.

J. -S. Wang, P. Nielaba, V. Privman

We study by Monte Carlo computer simulations random sequential adsorption (RSA) with diffusional relaxation, of lattice hard squares in two dimensions. While for RSA without diffusion the coverage approaches its maximum jamming value (large-time fractional coverage) exponentially, added diffusion allows the deposition process to proceed to the full coverage.

Lee Brekke, Hans Dykstra, Adam F. Falk, Tom D. Imbo

We study the statistics of vortices which appear in (2+1)--dimensional spontaneously broken gauge theories, where a compact group G breaks to a finite nonabelian subgroup H. Two simple models are presented. In the first, a quantum state which is symmetric under the interchange of a pair of indistinguishable vortices can be transformed into an antisymmetric s

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

We derive the two-loop evolution equations for the Cabibbo-Kobayashi-Maskawa matrix. We show that to leading order in the mass and CKM hierarchies the scaling of the mixings $|V_{ub}|^2$, $|V_{cb}|^2$, $|V_{td}|^2$, $|V_{ts}|^2$ and of the rephase-invariant CP-violating parameter $J$ is universal to all orders in perturbation theory. In leading order the oth

M. Forger, J. Laartz, U. Schaeper

The recently derived current algebra of classical non-linear sigma models on arbitrary Riemannian manifolds is extended to include the energy-momentum tensor. It is found that in two dimensions the energy-momentum tensor $\theta_{\mu\nu}$, the Noether current $j_\mu$ associated with the global symmetry of the theory and the composite field $j$ appearing as t

P. De, Robert Pelcovits, E. Vogel, J. Vogel

We investigate the supercooling of a nematic liquid crystal using fluctuating non-linear hydrodynamic equations. The Martin-Siggia-Rose formalism is used to calculate renormalized transport coefficients to one-loop order. Similar theories for isotropic liquids have shown substantial increases of the viscosities as the liquid is supercooled or compressed due

Rinat Kedem, Barry M. Mccoy

We use the single particle excitation energies and the completeness rules of the 3-state anti-ferromagnetic Potts chain, which have been obtained from Bethe's equation, to compute the modular invariant partition function. This provides a fermionic construction for the branching functions of the $D_4$ representation of $Z_4$ parafermions which complements the

Warren G. Anderson, Patrick R. Brady, Werner Israel, Sharon M. Morsink

The Weyl curvature inside a black hole formed in a generic collapse grows, classically without bound, near to the inner horizon, due to partial absorption and blueshifting of the radiative tail of the collapse. Using a spherical model, we examine how this growth is modified by quantum effects of conformally coupled massless fields.

J. Avan, M. Talon

A classical R-matrix structure is described for the Lax representation of the integrable n-particle chains of Calogero-Olshanetski-Perelo\-mov. This R-matrix is dynamical, non antisymmetric and non-invertible. It immediately triggers the integrability of the Type I, II and III potentials, and the algebraic structures associated with the Type V potential.

R. Altmeyer, K. D. Born, M. Goeckeler, R. Horsley

A numerical calculation of the lattice staggered renormalisation constants at $\beta = 5.35$, $m = 0.01$ is presented. It is seen that there are considerable non-perturbative effects present. As an application the vector decay constant $f_\rho$ is estimated. (LAT92 contribution, one LATEX file with 3 postscript figures appended.)

Augusto Sagnotti

An interesting feature of some open superstring models in $D < 10$ is the simultaneous presence, in the spectrum, of gauge fields and of a number of antisymmetric tensor fields. In these cases the Green-Schwarz mechanism can (and does) take a generalized form, resulting from the combined action of all the antisymmetric tensors. These novelties are illustrate

L. Pitaevskii, S. Stringari

A natural generalization of the Heisenberg uncertainty principle inequality holding for non hermitian operators is presented and applied to the fractional quantum Hall effect (FQHE). This inequality was used in a previous paper to prove the absence of long range order in the ground state of several 1D systems with continuous group symmetries. In this letter

Y. Umino, F. Myhrer

Excited negative parity hyperon masses are calculated in a chiral bag model in which the pion and the kaon fields are treated as perturbations. We also calculate the hadronic widths of $\lama$ and $\lamb$ as well as the coupling constants of the lightest $I=0$ excited hyperon to the meson-baryon channels, and discuss how the dispersive effects of the hadroni

A. Borzi, A. Koubek

We present a multi-grid algorithm in order to solve numerically the thermodynamic Bethe ansatz equations. We specifically adapt the program to compute the data of the conformal field theory reached in the ultraviolet limit. Submitted to Computer Physics Communications