Datasets:

bluuebunny

/

arxiv_abstract_embedding_mxbai_large_v1_milvus_binary

like 0

hep-lat/9107001

How to Put a Heavier Higgs on the Lattice

Lattice work, exploring the Higgs mass triviality bound, seems to indicate that a strongly interacting scalar sector in the minimal standard model cannot exist while low energy QCD phenomenology seems to indicate that it could. We attack this puzzle using the 1/N expansion and discover a simple criterion for selecting a lattice action that is more likely to produce a heavy Higgs particle. Our large $N$ calculation suggests that the Higgs mass bound might be around $850 GeV$, which is about 30% higher than previously obtained.

U.M. Heller, H. Neuberger and P. Vranas

hep-lat

July

1991

https://arxiv.org/abs/hep-lat/9107001

hep-lat/9107002

Spectral Density Study of the SU(3) Deconfining Phase Transition

We present spectral density reweighting techniques adapted to the analysis of a time series of data with a continuous range of allowed values. In a first application we analyze action and Polyakov line data from a Monte Carlo simulation on $L_t L^3 (L_t=2,4)$ lattices for the SU(3) deconfining phase transition. We calculate partition function zeros, as well as maxima of the specific heat and of the order parameter susceptibility. Details and warnings are given concerning i) autocorrelations in computer time and ii) a reliable extraction of partition function zeros. The finite size scaling analysis of these data leads to precise results for the critical couplings $\beta_c$, for the critical exponent $\nu$ and for the latent heat $\triangle s$. In both cases ($L_t=2$ and 4), the first order nature of the transition is substantiated.

Nelsons A. Alves, Bernd Al. Berg and Sergiu Sanielevici

hep-lat

July

1991

https://arxiv.org/abs/hep-lat/9107002

hep-lat/9112001

Vectorized Cluster Search

Contrary to conventional wisdom, the construction of clusters on a lattice can easily be vectorized, namely over each ``generation'' in a breadth first search. This applies directly to, e.g., the {\it single cluster} variant of the Swendsen-Wang algorithm. On a Cray Y-MP, total CPU time was reduced by a factor 3.5 -- 7 in actual applications.

Hans Gerd Evertz

hep-lat

December

1991

https://arxiv.org/abs/hep-lat/9112001

hep-lat/9112002

Multi-Grid Monte Carlo III. Two-Dimensional O(4)-Symmetric Nonlinear $\sigma$-Model

We study the dynamic critical behavior of the multi-grid Monte Carlo (MGMC) algorithm with piecewise-constant interpolation applied to the two-dimensional O(4)-symmetric nonlinear $\sigma$-model [= SU(2) principal chiral model], on lattices up to $256 \times 256$. We find a dynamic critical exponent $z_{int,{\cal M}^2} = 0.60 \pm 0.07$ for the W-cycle and $z_{int,{\cal M}^2} = 1.13 \pm 0.11$ for the V-cycle, compared to $z_{int,{\cal M}^2} = 2.0 \pm 0.15$ for the single-site heat-bath algorithm (subjective 68% confidence intervals). Thus, for this asymptotically free model, critical slowing-down is greatly reduced compared to local algorithms, but not completely eliminated. For a $256 \times 256$ lattice, W-cycle MGMC is about 35 times as efficient as a single-site heat-bath algorithm.

Robert G. Edwards, Sabino Jos\'e Ferreira, Jonathan Goodman, Alan D. Sokal

hep-lat

December

1991

https://arxiv.org/abs/hep-lat/9112002

hep-th/9108001

Exact Black String Solutions in Three Dimensions

A family of exact conformal field theories is constructed which describe charged black strings in three dimensions. Unlike previous charged black hole or extended black hole solutions in string theory, the low energy spacetime metric has a regular inner horizon (in addition to the event horizon) and a timelike singularity. As the charge to mass ratio approaches unity, the event horizon remains but the singularity disappears.

James H. Horne and Gary T. Horowitz

hep-th

August

1991

https://arxiv.org/abs/hep-th/9108001

hep-th/9108002

Hamiltonian construction of W-gravity actions

We show that all W-gravity actions can be easilly constructed and understood from the point of view of the Hamiltonian formalism for the constrained systems. This formalism also gives a method of constructing gauge invariant actions for arbitrary conformally extended algebras.

A. Mikovic

hep-th

August

1991

https://arxiv.org/abs/hep-th/9108002

hep-th/9108003

Supersymmetric Gelfand-Dickey Algebra

We study the classical version of supersymmetric $W$-algebras. Using the second Gelfand-Dickey Hamiltonian structure we work out in detail $W_2$ and $W_3$-algebras.

Katri Huitu and Dennis Nemeschansky

hep-th

August

1991

https://arxiv.org/abs/hep-th/9108003

hep-th/9108004

Ground Ring Of Two Dimensional String Theory

String theories with two dimensional space-time target spaces are characterized by the existence of a ``ground ring'' of operators of spin $(0,0)$. By understanding this ring, one can understand the symmetries of the theory and illuminate the relation of the critical string theory to matrix models. The symmetry groups that arise are, roughly, the area preserving diffeomorphisms of a two dimensional phase space that preserve the fermi surface (of the matrix model) and the volume preserving diffeomorphisms of a three dimensional cone. The three dimensions in question are the matrix eigenvalue, its canonical momentum, and the time of the matrix model.

Edward Witten

hep-th

August

1991

https://arxiv.org/abs/hep-th/9108004

hep-th/9108005

Fusion Residues

We discuss when and how the Verlinde dimensions of a rational conformal field theory can be expressed as correlation functions in a topological LG theory. It is seen that a necessary condition is that the RCFT fusion rules must exhibit an extra symmetry. We consider two particular perturbations of the Grassmannian superpotentials. The topological LG residues in one perturbation, introduced by Gepner, are shown to be a twisted version of the $SU(N)_k$ Verlinde dimensions. The residues in the other perturbation are the twisted Verlinde dimensions of another RCFT; these topological LG correlation functions are conjectured to be the correlation functions of the corresponding Grassmannian topological sigma model with a coupling in the action to instanton number.

Kenneth Intriligator

hep-th

August

1991

https://arxiv.org/abs/hep-th/9108005

hep-th/9108006

Discrete and Continuum Approaches to Three-Dimensional Quantum Gravity

It is shown that, in the three-dimensional lattice gravity defined by Ponzano and Regge, the space of physical states is isomorphic to the space of gauge-invariant functions on the moduli space of flat $SU(2)$ connections over a two-dimensional surface, which gives physical states in the $ISO(3)$ Chern-Simons gauge theory.

Hirosi Ooguri and Naoki Sasakura

hep-th

August

1991

https://arxiv.org/abs/hep-th/9108006

hep-th/9108007

Infinite Quantum Group Symmetry of Fields in Massive 2D Quantum Field Theory

Starting from a given S-matrix of an integrable quantum field theory in $1+1$ dimensions, and knowledge of its on-shell quantum group symmetries, we describe how to extend the symmetry to the space of fields. This is accomplished by introducing an adjoint action of the symmetry generators on fields, and specifying the form factors of descendents. The braiding relations of quantum field multiplets is shown to be given by the universal $\CR$-matrix. We develop in some detail the case of infinite dimensional Yangian symmetry. We show that the quantum double of the Yangian is a Hopf algebra deformation of a level zero Kac-Moody algebra that preserves its finite dimensional Lie subalgebra. The fields form infinite dimensional Verma-module representations; in particular the energy-momentum tensor and isotopic current are in the same multiplet.

A. LeCLair and F. Smirnov

hep-th

August

1991

https://arxiv.org/abs/hep-th/9108007

hep-th/9108008

Novel Symmetries of Topological Conformal Field theories

We show that various actions of topological conformal theories that were suggested recentely are particular cases of a general action. We prove the invariance of these models under transformations generated by nilpotent fermionic generators of arbitrary conformal dimension, $\Q$ and $\G$. The later are shown to be the $n^{th}$ covariant derivative with respect to ``flat abelian gauge field" of the fermionic fields of those models. We derive the bosonic counterparts $\W$ and $\R$ which together with $\Q$ and $\G$ form a special $N=2$ super $W_\infty$ algebra. The algebraic structure is discussed and it is shown that it generalizes the so called ``topological algebra".

J. Sonnenschein and S. Yankielowicz

hep-th

August

1991

https://arxiv.org/abs/hep-th/9108008

hep-th/9108009

Solving 3+1 QCD on the Transverse Lattice Using 1+1 Conformal Field Theory

A new transverse lattice model of $3+1$ Yang-Mills theory is constructed by introducing Wess-Zumino terms into the 2-D unitary non-linear sigma model action for link fields on a 2-D lattice. The Wess-Zumino terms permit one to solve the basic non-linear sigma model dynamics of each link, for discrete values of the bare QCD coupling constant, by applying the representation theory of non-Abelian current (Kac-Moody) algebras. This construction eliminates the need to approximate the non-linear sigma model dynamics of each link with a linear sigma model theory, as in previous transverse lattice formulations. The non-perturbative behavior of the non-linear sigma model is preserved by this construction. While the new model is in principle solvable by a combination of conformal field theory, discrete light-cone, and lattice gauge theory techniques, it is more realistically suited for study with a Tamm-Dancoff truncation of excited states. In this context, it may serve as a useful framework for the study of non-perturbative phenomena in QCD via analytic techniques.

Paul A. Griffin

hep-th

August

1991

https://arxiv.org/abs/hep-th/9108009

hep-th/9108010

String Winding in a Black Hole Geometry

$U(1)$ zero modes in the $SL(2,R)_k/U(1)$ and $SU(2)_k/U(1)$ conformal coset theories, are investigated in conjunction with the string black hole solution. The angular variable in the Euclidean version, is found to have a double set of winding. Region III is shown to be $SU(2)_k/U(1)$ where the doubling accounts for the cut sructure of the parafermionic amplitudes and fits nicely across the horizon and singularity. The implications for string thermodynamics and identical particles correlations are discussed.

Mordechai Spiegelglas

hep-th

August

1991

https://arxiv.org/abs/hep-th/9108010

hep-th/9108011

Twisted Black p-Brane Solutions in String Theory

It has been shown that given a classical background in string theory which is independent of $d$ of the space-time coordinates, we can generate other classical backgrounds by $O(d)\otimes O(d)$ transformation on the solution. We study the effect of this transformation on the known black $p$-brane solutions in string theory, and show how these transformations produce new classical solutions labelled by extra continuous parameters and containing background antisymmetric tensor field.

Ashoke Sen

hep-th

August

1991

https://arxiv.org/abs/hep-th/9108011

hep-th/9108012

On the Perturbations of String-Theoretic Black Holes

The perturbations of string-theoretic black holes are analyzed by generalizing the method of Chandrasekhar. Attention is focussed on the case of the recently considered charged string-theoretic black hole solutions as a representative example. It is shown that string-intrinsic effects greatly alter the perturbed motions of the string-theoretic black holes as compared to the perturbed motions of black hole solutions of the field equations of general relativity, the consequences of which bear on the questions of the scattering behavior and the stability of string-theoretic black holes. The explicit forms of the axial potential barriers surrounding the string-theoretic black hole are derived. It is demonstrated that one of these, for sufficiently negative values of the asymptotic value of the dilaton field, will inevitably become negative in turn, in marked contrast to the potentials surrounding the static black holes of general relativity. Such potentials may in principle be used in some cases to obtain approximate constraints on the value of the string coupling constant. The application of the perturbation analysis to the case of two-dimensional string-theoretic black holes is discussed.

Gerald Gilbert

hep-th

August

1991

https://arxiv.org/abs/hep-th/9108012

hep-th/9108013

Differential Equations for Periods and Flat Coordinates in Two Dimensionsional Topological Matter Theories

We derive directly from the N=2 LG superpotential the differential equations that determine the flat coordinates of arbitrary topological CFT's.

W.Lerche, D.Smit, and N. Warner

hep-th

August

1991

https://arxiv.org/abs/hep-th/9108013

hep-th/9108014

Loop Equations and the Topological Phase of Multi-Cut Matrix Models

We study the double scaling limit of mKdV type, realized in the two-cut Hermitian matrix model. Building on the work of Periwal and Shevitz and of Nappi, we find an exact solution including all odd scaling operators, in terms of a hierarchy of flows of $2\times 2$ matrices. We derive from it loop equations which can be expressed as Virasoro constraints on the partition function. We discover a ``pure topological" phase of the theory in which all correlation functions are determined by recursion relations. We also examine macroscopic loop amplitudes, which suggest a relation to 2D gravity coupled to dense polymers.

C. Crnkovic, M. Douglas, G. Moore

hep-th

August

1991

https://arxiv.org/abs/hep-th/9108014

hep-th/9108015

A $U(N)$ Gauge Theory in Three Dimensions as an Ensemble of Surfaces

A particular $U(N)$ gauge theory defined on the three dimensional dodecahedral lattice is shown to correspond to a model of oriented self-avoiding surfaces. Using large $N$ reduction it is argued that the model is partially soluble in the planar limit.

F. David, H. Neuberger

hep-th

August

1991

https://arxiv.org/abs/hep-th/9108015

hep-th/9108016

Non-Perturbative 2D Quantum Gravity, Again

This is a talk given by S.D. at the the workshop on Random Surfaces and 2D Quantum Gravity, Barcelona 10-14 June 1991. It is an updated review of recent work done by the authors on a proposal for non-perturbatively stable 2D quantum gravity coupled to c<1 matter, based on the flows of the (generalised) KdV hierarchy.

S.Dalley, C.Johnson and T.Morris

hep-th

August

1991

https://arxiv.org/abs/hep-th/9108016

hep-th/9108017

A New Solution to the Star--Triangle Equation Based on U$_q$(sl(2)) at Roots of Unit

We find new solutions to the Yang--Baxter equation in terms of the intertwiner matrix for semi-cyclic representations of the quantum group $U_q(s\ell(2))$ with $q= e^{2\pi i/N}$. These intertwiners serve to define the Boltzmann weights of a lattice model, which shares some similarities with the chiral Potts model. An alternative interpretation of these Boltzmann weights is as scattering matrices of solitonic structures whose kinematics is entirely governed by the quantum group. Finally, we consider the limit $N\to\infty$ where we find an infinite--dimensional representation of the braid group, which may give rise to an invariant of knots and links.

Cesar Gomez and German Sierra

hep-th

August

1991

https://arxiv.org/abs/hep-th/9108017

hep-th/9108018

Real Forms of Complex Quantum Anti de Sitter Algebra $U_q (Sp(4,C))$ and their Contraction Schemes

We describe four types of inner involutions of the Cartan-Weyl basis providing (for $ |q|=1$ and $q$ real) three types of real quantum Lie algebras: $U_{q}(O(3,2))$ (quantum D=4 anti-de-Sitter), $U_{q}(O(4,1))$ (quantum D=4 de-Sitter) and $U_{q}(O(5))$. We give also two types of inner involutions of the Cartan-Chevalley basis of $U_{q}(Sp(4;C))$ which can not be extended to inner involutions of the Cartan-Weyl basis. We outline twelve contraction schemes for quantum D=4 anti-de-Sitter algebra. All these contractions provide four commuting translation generators, but only two (one for $ |q|=1$, second for $q$ real) lead to the quantum \po algebra with an undeformed space rotations O(3) subalgebra.

J. Lukierski, A. Novicki and H. Ruegg

hep-th

August

1991

https://arxiv.org/abs/hep-th/9108018

hep-th/9108019

String Theory in Two Dimensions

I review some of the recent progress in two-dimensional string theory, which is formulated as a sum over surfaces embedded in one dimension.

Igor R. Klebanov

hep-th

August

1991

https://arxiv.org/abs/hep-th/9108019

hep-th/9108020

String Theory and the Donaldson Polynomial

It is shown that the scattering of spacetime axions with fivebrane solitons of heterotic string theory at zero momentum is proportional to the Donaldson polynomial.

J.A.Harvey and A.Strominger

hep-th

August

1991

https://arxiv.org/abs/hep-th/9108020

hep-th/9108021

The big picture

We discuss the conformal field theory and string field theory of the NSR superstring using a BRST operator with a nonminimal term, which allows all bosonic ghost modes to be paired into creation and annihilation operators. Vertex operators for the Neveu-Schwarz and Ramond sectors have the same ghost number, as do string fields. The kinetic and interaction terms are the same for Neveu-Schwarz as for Ramond string fields, so spacetime supersymmetry is closer to being manifest. The kinetic terms and supersymmetry don't mix levels, simplifying component analysis and gauge fixing.

N. Berkovits, M.T. Hatsuda, and W. Siegel

hep-th

August

1991

https://arxiv.org/abs/hep-th/9108021

hep-th/9108022

Superstring Compactification and Target Space Duality

This review talk focusses on some of the interesting developments in the area of superstring compactification that have occurred in the last couple of years. These include the discovery that ``mirror symmetric" pairs of Calabi--Yau spaces, with completely distinct geometries and topologies, correspond to a single (2,2) conformal field theory. Also, the concept of target-space duality, originally discovered for toroidal compactification, is being extended to Calabi--Yau spaces. It also associates sets of geometrically distinct manifolds to a single conformal field theory. A couple of other topics are presented very briefly. One concerns conceptual challenges in reconciling gravity and quantum mechanics. It is suggested that certain ``distasteful allegations" associated with quantum gravity such as loss of quantum coherence, unpredictability of fundamental parameters of particle physics, and paradoxical features of black holes are likely to be circumvented by string theory. Finally there is a brief discussion of the importance of supersymmetry at the TeV scale, both from a practical point of view and as a potentially significant prediction of string theory.

John H. Schwarz

hep-th

August

1991

https://arxiv.org/abs/hep-th/9108022

hep-th/9108023

Fock space resolutions of the Virasoro highest weight modules with c<=1

We extend Felder's construction of Fock space resolutions for the Virasoro minimal models to all irreducible modules with $c\leq 1$. In particular, we provide resolutions for the representations corresponding to the boundary and exterior of the Kac table.

Peter Bouwknegt, Jim McCarthy and Krzysztof Pilch

hep-th

August

1991

https://arxiv.org/abs/hep-th/9108023

hep-th/9108024

On the S-matrix of the Sub-leading Magnetic Deformation of the Tricritical Ising Model in Two Dimensions

We compute the $S$-matrix of the Tricritical Ising Model perturbed by the subleading magnetic operator using Smirnov's RSOS reduction of the Izergin-Korepin model. The massive model contains kink excitations which interpolate between two degenerate asymmetric vacua. As a consequence of the different structure of the two vacua, the crossing symmetry is implemented in a non-trivial way. We use finite-size techniques to compare our results with the numerical data obtained by the Truncated Conformal Space Approach and find good agreement.

F. Colomo, A. Koubek, G. Mussardo

hep-th

August

1991

https://arxiv.org/abs/hep-th/9108024

hep-th/9108025

Correlation functions in super Liouville theory

We calculate three- and four-point functions in super Liouville theory coupled to super Coulomb gas on world sheets with spherical topology. We first integrate over the zero mode and assume that a parameter takes an integer value. After calculating the amplitudes, we formally continue the parameter to an arbitrary real number. Remarkably the result is completely parallel to the bosonic case, the amplitudes being of the same form as those of the bosonic case.

E. Abdalla, M.C.B. Abdalla, D.Dalmazi, Koji Harada

hep-th

August

1991

https://arxiv.org/abs/hep-th/9108025

hep-th/9108026

Superstring in Two Dimensional Black Hole

We construct superstring theory in two dimensional black hole background based on supersymmetric $SU(1,1)/U(1)$ gauged Wess-Zumino-Witten model.

Shin'ichi Nojiri

hep-th

August

1991

https://arxiv.org/abs/hep-th/9108026

hep-th/9108027

Factorization and Topological States in $c=1$ Matter Coupled to 2-D Gravity

Factorization of the $N$-point amplitudes in two-dimensional $c=1$ quantum gravity is understood in terms of short-distance singularities arising from the operator product expansion of vertex operators after the Liouville zero mode integration. Apart from the tachyon states, there are infinitely many topological states contributing to the intermediate states.

Norisuke Sakai, Yoshiaki Tanii

hep-th

August

1991

https://arxiv.org/abs/hep-th/9108027

hep-th/9108028

Applied Conformal Field Theory

These lectures consisted of an elementary introduction to conformal field theory, with some applications to statistical mechanical systems, and fewer to string theory. Contents: 1. Conformal theories in d dimensions 2. Conformal theories in 2 dimensions 3. The central charge and the Virasoro algebra 4. Kac determinant and unitarity 5. Identication of m = 3 with the critical Ising model 6. Free bosons and fermions 7. Free fermions on a torus 8. Free bosons on a torus 9. Affine Kac-Moody algebras and coset constructions 10. Advanced applications

Paul Ginsparg

hep-th

August

1991

https://arxiv.org/abs/hep-th/9108028

hep-th/9109001

Fractional Superstrings with Space-Time Critical Dimensions Four and Six

We propose possible new string theories based on local world-sheet symmetries corresponding to extensions of the Virasoro algebra by fractional spin currents. They have critical central charges $c=6(K+8)/(K+2)$ and Minkowski space-time dimensions $D=2+16/K$ for $K\geq2$ an integer. We present evidence for their existence by constructing modular invariant partition functions and the massless particle spectra. The dimension $4$ and $6$ strings have space-time supersymmetry.

Philip C. Argyres and S.-H. Henry Tye

hep-th

September

1991

https://arxiv.org/abs/hep-th/9109001

hep-th/9109002

Ashtekar's Approach to Quantum Gravity

A review is given of work by Abhay Ashtekar and his colleagues Carlo Rovelli, Lee Smolin, and others, which is directed at constructing a nonperturbative quantum theory of general relativity.

Gary T. Horowitz

hep-th

September

1991

https://arxiv.org/abs/hep-th/9109002

hep-th/9109003

The renormalization group flow in 2D N=2 SUSY Landau-Ginsburg models

We investigate the renormalization of N=2 SUSY L-G models with central charge $c=3p/(2+p)$ perturbed by an almost marginal chiral operator. We calculate the renormalization of the chiral fields up to $gg{^*}$ order and of nonchiral fields up to $g(g^{*})$ order. We propose a formulation of the nonrenormalization theorem and show that it holds in the lowest nontrivial order. It turns out that, in this approximation, the chiral fields can not get renormalized $\Phi^{k}=\Phi^{k}_{0}$. The $\beta$ function then remains unchanged $\beta=\epsilon gr$.

Jadwiga Bienkowska

hep-th

September

1991

https://arxiv.org/abs/hep-th/9109003

hep-th/9109004

Bosonisation of the Complex-boson realisation of $W_\infty$

We bosonise the complex-boson realisations of the $W_\infty$ and $W_{1+\infty}$ algebras. We obtain nonlinear realisations of $W_\infty$ and $W_{1+\infty}$ in terms of a pair of fermions and a real scalar. By further bosonising the fermions, we then obtain realisations of $W_\infty$ in terms of two scalars. Keeping the most non-linear terms in the scalars only, we arrive at two-scalar realisations of classical $w_\infty$.

X. Shen and X.J. Wang

hep-th

September

1991

https://arxiv.org/abs/hep-th/9109004

hep-th/9109005

World Sheet and Space Time Physics in Two Dimensional (Super) String Theory

We show that tree level ``resonant'' $N$ tachyon scattering amplitudes, which define a sensible ``bulk'' S -- matrix in critical (super) string theory in any dimension, have a simple structure in two dimensional space time, due to partial decoupling of a certain infinite set of discrete states. We also argue that the general (non resonant) amplitudes are determined by the resonant ones, and calculate them explicitly, finding an interesting analytic structure. Finally, we discuss the space time interpretation of our results.

P. Di Francesco and D. Kutasov

hep-th

September

1991

https://arxiv.org/abs/hep-th/9109005

hep-th/9109006

(2+1)-Dimensional Chern-Simons Gravity as a Dirac Square Root

For (2+1)-dimensional spacetimes with the spatial topology of a torus, the transformation between the Chern-Simons and ADM versions of quantum gravity is constructed explicitly, and the wave functions are compared. It is shown that Chern-Simons wave functions correspond to modular forms of weight 1/2, that is, spinors on the ADM moduli space, and that their evolution (in York's ``extrinsic time'' variable) is described by a Dirac equation. (This version replaces paper 9109006, which was garbled by my mailer.)

Steven Carlip

hep-th

September

1991

https://arxiv.org/abs/hep-th/9109006

hep-th/9109007

High Temperature Limit of the Confining Phase

The deconfining transition in non-Abelian gauge theory is known to occur by a condensation of Wilson lines. By expanding around an appropriate Wilson line background, it is possible at large $N$ to analytically continue the confining phase to arbitrarily high temperatures, reaching a weak coupling confinement regime. This is used to study the high temperature partition function of an $SU(N)$ electric flux tube. It is found that the partition function corresponds to that of a string theory with a number of world-sheet fields that diverges at short distance.

Joseph Polchinski

hep-th

September

1991

https://arxiv.org/abs/hep-th/9109007

hep-th/9109008

Effective Superstrings

We generalize the method of quantizing effective strings proposed by Polchinski and Strominger to superstrings. The Ramond-Neveu-Schwarz string is different from the Green-Schwarz string in non-critical dimensions. Both are anomaly-free and Poincare invariant. Some implications of the results are discussed. The formal analogy with 4D (super)gravity is pointed out.

Zhu Yang

hep-th

September

1991

https://arxiv.org/abs/hep-th/9109008

hep-th/9109009

Bi-Hamiltonian Sturcture of Super KP Hierarchy

We obtain the bi-Hamiltonian structure of the super KP hierarchy based on the even super KP operator $\Lambda = \theta^{2} + \sum^{\infty}_{i=-2}U_{i} \theta^{-i-1}$, as a supersymmetric extension of the ordinary KP bi-Hamiltonian structure. It is expected to give rise to a universal super $W$-algebra incorporating all known extended superconformal $W_{N}$ algebras by reduction. We also construct the super BKP hierarchy by imposing a set of anti-self-dual constraints on the super KP hierarchy.

Feng Yu

hep-th

September

1991

https://arxiv.org/abs/hep-th/9109009

hep-th/9109010

W3 Constructions on Affine Lie Algebras

We use an argument of Romans showing that every Virasoro construction leads to realizations of $W_3$, to construct $W_3$ realizations on arbitrary affine Lie algebras. Solutions are presented for generic values of the level as well as for specific values of the level but with arbitrary parameters. We give a detailed discussion of the $\aff{su}(2)_\ell$-case. Finally, we discuss possible applications of these realizations to the construction of $W$-strings.

A. Deckmyn and S. Schrans

hep-th

September

1991

https://arxiv.org/abs/hep-th/9109010

hep-th/9109011

Critical Boundary Conditions for the Effective String

Gauge systems in the confining phase induce constraints at the boundaries of the effective string, which rule out the ordinary bosonic string even with short distance modifications. Allowing topological excitations, corresponding to winding around the colour flux tube, produces at the quantum level a universal free fermion string with a boundary phase nu=1/4. This coincides with a model proposed some time ago in order to fit Monte Carlo data of 3D and 4D Lattice gauge systems better. A universal value of the thickness of the colour flux tube is predicted.

M.Caselle, R.Fiore, F.Gliozzi, P.Provero and S.Vinti

hep-th

September

1991

https://arxiv.org/abs/hep-th/9109011

hep-th/9109012

Is S=1 for c=1?

The $c=1$ string in the Liouville field theory approach is shown to possess a nontrivial tree-level $S$-matrix which satisfies factorization property implied by unitary, if all the extra massive physical states are included.

D. Minic and Z. Yang

hep-th

September

1991

https://arxiv.org/abs/hep-th/9109012

hep-th/9109013

Collective Field Representation of Nonrelativistic Fermions in (1+1) Dimensions

A collective field formalism for nonrelativistic fermions in (1+1) dimensions is presented. Applications to the D=1 hermitian matrix model and the system of one-dimensional fermions in the presence of a weak electromagnetic field are discussed.

Dimitra Karabali

hep-th

September

1991

https://arxiv.org/abs/hep-th/9109013

hep-th/9109014

Generalized Drinfeld-Sokolov Hierarchies II: The Hamiltonian Structures

In this paper we examine the bi-Hamiltonian structure of the generalized KdV-hierarchies. We verify that both Hamiltonian structures take the form of Kirillov brackets on the Kac-Moody algebra, and that they define a coordinated system. Classical extended conformal algebras are obtained from the second Poisson bracket. In particular, we construct the $W_n^l$ algebras, first discussed for the case $n=3$ and $l=2$ by A. Polyakov and M. Bershadsky.

Nigel J. Burroughs, Mark F. deGroot, Timothy J. Hollowood and J. Luis Miramontes

hep-th

September

1991

https://arxiv.org/abs/hep-th/9109014

hep-th/9109015

On the solutions to the string equation

The set of solutions to the string equation $[P,Q]=1$ where $P$ and $Q$ are differential operators is described.It is shown that there exists one-to-one correspondence between this set and the set of pairs of commuting differential operators.This fact permits us to describe the set of solutions to the string equation in terms of moduli spa- ces of algebraic curves,however the direct description is much simpler. Some results are obtained for the superanalog to the string equation where $P$ and $Q$ are considered as superdifferential operators. It is proved that this equation is invariant with respect to Manin-Radul, Mulase-Rabin and Kac-van de Leur KP-hierarchies.

A.Schwarz

hep-th

September

1991

https://arxiv.org/abs/hep-th/9109015

hep-th/9109016

Classical Gravity Coupled to Liouville Theory

We consider the two dimensional Jackiw-Teitelboim model of gravity. We first couple the model to the Liouville action and $c$ scalar fields and show, treating the combined system as a non linear sigma model, that the resulting theory can be interpreted as a critical string moving in a target space of dimension $D=c+2$. We then analyse perturbatively a generalised model containing a kinetic term and an arbitrary potential for the auxiliary field. We use the background field method and work with covariant gauges. We show that the renormalisability of the theory depends on the form of the potential. For a general potential, the theory can be renormalised as a non linear sigma model. In the particular case of a Liouville-like potential, the theory is renormalisable in the usual sense.

F.D. Mazzitelli and N. Mohammedi

hep-th

September

1991

https://arxiv.org/abs/hep-th/9109016

hep-th/9109017

Singular vectors by Fusions in affine su(2)

Explicit expressions for the singular vectors in the highest weight representations of $A_1^{(1)}$ are obtained using the fusion formalism of conformal field theory.

M. Bauer and N. Sochen

hep-th

September

1991

https://arxiv.org/abs/hep-th/9109017

hep-th/9109018

Stochastic Quantization vs. KdV Flows in 2D Quantum Gravity

We consider the stochastic quantization scheme for a non-perturbative stabilization of 2D quantum gravity and prove that it does not satisfy the KdV flow equations. It therefore differs from a recently suggested matrix model which allows real solutions to the KdV equations. The behaviour of the Fermi energy, the free energy and macroscopic loops in the stochastic quantization scheme are elucidated.

J. Ambjorn, C.V. Johnson and T.R.Morris

hep-th

September

1991

https://arxiv.org/abs/hep-th/9109018

hep-th/9109019

Restricted Quantum Affine Symmetry of Perturbed Minimal Models

We study the structure of superselection sectors of an arbitrary perturbation of a conformal field theory. We describe how a restriction of the q-deformed $\hat{sl(2)}$ affine Lie algebra symmetry of the sine-Gordon theory can be used to derive the S-matrices of the $\Phi^{(1,3)}$ perturbations of the minimal unitary series. This analysis provides an identification of fields which create the massive kink spectrum. We investigate the ultraviolet limit of the restricted sine-Gordon model, and explain the relation between the restriction and the Fock space cohomology of minimal models. We also comment on the structure of degenerate vacuum states. Deformed Serre relations are proven for arbitrary affine Toda theories, and it is shown in certain cases how relations of the Serre type become fractional spin supersymmetry relations upon restriction.

G. Felder and A. LeClair

hep-th

September

1991

https://arxiv.org/abs/hep-th/9109019

hep-th/9109020

Infinite Quantum Group Symmetry in 2d Quantum Field Theory

I describe how integrable quantum field theories in 2 spacetime dimensions are characterized by infinite dimensional quantum group symmetries, namely the q-deformations of affine Lie algebras, and their Yangian limit. These symmetries can provide a new non-perturbative formulation of the theories.

Andre LeClair

hep-th

September

1991

https://arxiv.org/abs/hep-th/9109020

hep-th/9109021

Excited-state thermodynamics

In the last several years, the Casimir energy for a variety of 1+1-dimensional integrable models has been determined from the exact S-matrix. It is shown here how to modify the boundary conditions to project out the lowest-energy state, which enables one to find excited-state energies. This is done by calculating thermodynamic expectation values of operators which generate discrete symmetries. This is demonstrated with a number of perturbed conformal field theories, including the Ising model, the three-state Potts model, ${\bf Z}_n$ parafermions, Toda minimal S-matrices, and massless Goldstinos.

Paul Fendley

hep-th

September

1991

https://arxiv.org/abs/hep-th/9109021

hep-th/9109022

Some Applications of String Field Theory

We study general properties of the classical solutions in non-polynomial closed string field theory and their relationship with two dimensional conformal field theories. In particular we discuss how different conformal field theories which are related by marginal or nearly marginal deformations can be regarded as different classical solutions of some underlying string field theory. We also discuss construction of a classical solution labelled by infinite number of parameters in string field theory in two dimensions. For a specific set of values of the parameters the solution can be identified to the black hole solution.

Ashoke Sen

hep-th

September

1991

https://arxiv.org/abs/hep-th/9109022

hep-th/9109023

On quantum group symmetries of conformal field theories

The appearance of quantum groups in conformal field theories is traced back to the Poisson-Lie symmetries of the classical chiral theory. A geometric quantization of the classical theory deforms the Poisson-Lie symmetries to the quantum group ones. This elucidates the fundamental role of chiral symmetries that quantum groups play in conformal models. As a byproduct, one obtains a more geometric approach to the representation theory of quantum groups.

Fernando Falceto and Krzysztof Gawedzki

hep-th

September

1991

https://arxiv.org/abs/hep-th/9109023

hep-th/9109024

On the Liouville Approach to Correlation Functions for 2-D Quantum Gravity

We evaluate the three point function for arbitrary states in bosonic minimal models on the sphere coupled to quantum gravity in two dimensions. The validity of the formal continuation in the number of Liouville screening charge insertions is shown directly from the Liouville functional integral using semi-classical methods.

Kenichiro Aoki and Eric D'Hoker

hep-th

September

1991

https://arxiv.org/abs/hep-th/9109024

hep-th/9109025

Correlation functions of minimal models coupled to two dimensional quantum supergravity

We compute the three point functions of Neveu--Schwarz primary fields of the minimal models on the sphere when coupled to supergravity in two dimensions. The results show that the three point correlation functions are determined by the scaling dimensions of the fields, as in the bosonic case.

Kenichiro Aoki and Eric D'Hoker

hep-th

September

1991

https://arxiv.org/abs/hep-th/9109025

hep-th/9109026

String Effective Action and Two Dimensional Charged Black Hole

Graviton-dilaton background field equations in three space-time dimensions, following from the string effective action are solved when the metric has only time dependence. By taking one of the two space dimensions as compact, our solution reproduces a recently discovered charged black hole solution in two space-time dimensions. Solutions in presence of nonvanishing three dimensional background antisymmetric tensor field are also discussed.

S. Pratik Khastgir and Alok Kumar

hep-th

September

1991

https://arxiv.org/abs/hep-th/9109026

hep-th/9109027

On the connection between Quantum Mechanics and the geometry of two-dimensional strings

On the basis of an area-preserving symmetry in the phase space of a one-dimensional matrix model - believed to describe two-dimensional string theory in a black-hole background which also allows for space-time foam - we give a geometric interpretation of the fact that two-dimensional stringy black holes are consistent with conventional quantum mechanics due to the infinite gauged `W-hair' property that characterises them.

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

hep-th

September

1991

https://arxiv.org/abs/hep-th/9109027

hep-th/9109028

New Special Operators in $W$-Gravity Theories

We find new special physical operators of $W_3 -$gravity having non trivial ghost sectors. Some of these operators may be viewed as the liouville dressings of the energy operator of the Ising model coupled to {\it 2d~gravity} and this fills in a gap in the connection between pure $W_3 -$gravity and Ising model coupled to 2d gravity found in our previous work. We formulate a selection rule required for the calculation of correlators in $W -$gravity theories. Using this rule, we construct the non ghost part of the new operators of $W_N -$gravity and find that they represent the $(N , N+1)$ minimal model operators from both inside and outside the minimal table. Along the way we obtain the canonical spectrum of $W_N -$gravity for all $N$ .

S. Kalyana Rama

hep-th

September

1991

https://arxiv.org/abs/hep-th/9109028

hep-th/9109029

Beyond the Large N Limit: Non-linear W(infinity) as symmetry of the SL(2,R)/U(1) coset model

We show that the symmetry algebra of the $SL(2,R)_{k}/U(1)$ coset model is a non-linear deformation of $W_{\infty}$, characterized by $k$. This is a universal $W$-algebra which linearizes in the large $k$ limit and truncates to $W_{N}$ for $k=-N$. Using the theory of non-compact parafermions we construct a free field realization of the non-linear $W_{\infty}$ in terms of two bosons with background charge. The $W$-characters of all unitary $SL(2,R)/U(1)$ representations are computed. Applications to the physics of 2-d black hole backgrounds are also discussed and connections with the KP approach to $c=1$ string theory are outlined.

I. Bakas, E. Kiritsis

hep-th

September

1991

https://arxiv.org/abs/hep-th/9109029

hep-th/9109030

Topology Change in General Relativity

A review is given of recent work on topology changing solutions to the first order form of general relativity. These solutions have metrics which are smooth everywhere, invertible almost everywhere, and have bounded curvature. The importance of considering degenerate metrics is discussed, and the possibility that quantum effects can suppress topology change is briefly examined.

Gary T. Horowitz

hep-th

September

1991

https://arxiv.org/abs/hep-th/9109030

hep-th/9109031

Constant Curvature and Non-Perturbative W3 Gravity

We show that the new classical action for two dimensional gravity (the Jackiw-Teitelboim model) possesses a $W_3$ algebra. We quantise the resulting $W_3$ gravity in the presence of matter fields with arbitrary central charges and obtain the critical exponents. The auxiliary field of the model, expressing the constancy of the scalar curvature, can be interpreted as one of the physical degrees of freedom of the $W_3$ gravity. Our expressions are corrections to some previously published results for this model where the $W_3$ symmetry was not accounted for.

N. Mohammedi

hep-th

September

1991

https://arxiv.org/abs/hep-th/9109031

hep-th/9109032

Interaction of Discrete States in Two-Dimensional String Theory

We study the couplings of discrete states that appear in the string theory embedded in two dimensions, and show that they are given by the structure constants of the group of area preserving diffeomorphisms. We propose an effective action for these states, which is itself invariant under this infinite-dimensional group.

I. R. Klebanov and A. M. Polyakov

hep-th

September

1991

https://arxiv.org/abs/hep-th/9109032

hep-th/9109033

SU(3) x SU(2) x U(1): The residual symmetry of extended conformal gravity

Within the 4-dimensional conformal algebra, the presence of two translation operators implies the existence of 3 distinct metrics of definite Weyl weight constructible from the translational gauge fields. If we demand that each of these metrics give rise to a gauge theory of gravity, we are led to extend the symmetry so that each of these three metrics has a corresponding translation operator. Assigning a vierbein to each of these three translations, a different spacetime metric arises for every choice of inner product of the vierbeins. The covering group of the compact part of the minimal transitive group classifying these inner products is $SU(4)$. An additional $SU(2)$ symmetry classifies the antisymmetric parts of the vierbein product. If the metric is chosen as the gauge field of the translations in the standard way, the SU(4) part of this symmetry is broken to the semidirect product of $SU(3)$ with $U(1)$.

James T. Wheeler

hep-th

September

1991

https://arxiv.org/abs/hep-th/9109033

hep-th/9109034

A Deformation Theory of Self-Dual Einstein Spaces

The self-dual Einstein equations on a compact Riemannian 4-manifold can be expressed as a quadratic condition on the curvature of an $SU(2)$ (spin) connection which is a covariant generalization of the self-dual Yang-Mills equations. Local properties of the moduli space of self-dual Einstein connections are described in the context of an elliptic complex which arises in the linearization of the quadratic equations on the $SU(2)$ curvature. In particular, it is shown that the moduli space is discrete when the cosmological constant is positive; when the cosmological constant is negative the moduli space can be a manifold the dimension of which is controlled by the Atiyah-Singer index theorem.

C. G. Torre

hep-th

September

1991

https://arxiv.org/abs/hep-th/9109034

hep-th/9109035

Classification of Simple Current Invariants

We summarize recent work on the classification of modular invariant partition functions that can be obtained with simple currents in theories with a center (Z_p)^k with p prime. New empirical results for other centers are also presented. Our observation that the total number of invariants is monodromy-independent for (Z_p)^k appears to be true in general as well. (Talk presented in the parallel session on string theory of the Lepton-Photon/EPS Conference, Geneva, 1991.)

B. Gato-Rivera and A.N. Schellekens

hep-th

September

1991

https://arxiv.org/abs/hep-th/9109035

hep-th/9109036

Batalin-Vilkovisky Lagrangian Quantisation

The Lagrangian Batalin-Vilkovisky (BV) formalism gives the rules for the quantisation of a general class of gauge theories which contain all the theories known up to now. It does, however, not only give a recipe to obtain a gauge fixed action, but also gives a nice understanding of the mechanism behind gauge fixing. It moreover brings together a lot of previous knowledge and recipes in one main concept~: the canonical transformations. We explain the essentials of this formalism and give related results on the superparticle. Also anomalies (in general functions of fields and antifields) can be obtained in this formalism, and it gives the relation between anomalies in different gauges. A Pauli-Villars scheme can be used to obtain a regularised definition of the expressions at the one loop level. The calculations become similar to those of Fujikawa with the extra freedom of using arbitrary variables. A discrepancy between anomalies in light-cone gauge of the Green-Schwarz superstring and in the semi-light-cone gauge is discussed.

Antoine Van Proeyen

hep-th

September

1991

https://arxiv.org/abs/hep-th/9109036

hep-th/9109037

Some Correlation Functions of Minimal Superconformal Models Coupled to Supergravity

We compute general three-point functions of minimal superconformal models coupled to supergravity in the Neveu-Schwarz sector for spherical topology thus extending to the superconformal case the results of Goulian and Li and of Dotsenko.

L. ALvarez-Gaume Ph. Zaugg

hep-th

September

1991

https://arxiv.org/abs/hep-th/9109037

hep-th/9109038

Twisting Classical Solutions in Heterotic String Theory

We show that, given a classical solution of the heterotic string theory which is independent of $d$ of the space time directions, and for which the gauge field configuration lies in a subgroup that commutes with $p$ of the $U(1)$ generators of the gauge group, there is an $O(d)\otimes O(d+p)$ transformation, which, acting on the solution, generates new classical solutions of the theory. With the help of these transformations we construct black 6-brane solutions in ten dimensional heterotic string theory carrying independent magnetic, electric and antisymmetric tensor gauge field charge, by starting from a black 6-brane solution that carries magnetic charge but no electric or antisymmetric tensor gauge field charge. The electric and the magnetic charges point in different directions in the gauge group.

S. F. Hassan and Ashoke Sen

hep-th

September

1991

https://arxiv.org/abs/hep-th/9109038

hep-th/9109039

A $\kappa$-Symmetry Calculus for Superparticles

We develop a $\kappa$-symmetry calculus for the d=2 and d=3, N=2 massive superparticles, which enables us to construct higher order $\kappa$-invariant actions. The method relies on a reformulation of these models as supersymmetric sigma models that are invariant under local worldline superconformal transformations. We show that the $\kappa$-symmetry is embedded in the superconformal symmetry so that a calculus for the $\kappa$-symmetry is equivalent to a tensor calculus for the latter. We develop such a calculus without the introduction of a worldline supergravity multiplet.

Jerome P. Gauntlett

hep-th

September

1991

https://arxiv.org/abs/hep-th/9109039

hep-th/9109040

Irrational Axions as a Solution of The Strong CP Problem in an Eternal Universe

We exhibit a novel solution of the strong CP problem, which does not involve any massless particles. The low energy effective Lagrangian of our model involves a discrete spacetime independent axion field which can be thought of as a parameter labeling a dense set of $\theta$ vacua. In the full theory this parameter is seen to be dynamical, and the model seeks the state of lowest energy, which has $\theta_{eff} = 0$. The processes which mediate transitions between $\theta$ vacua involve heavy degrees of freedom and are very slow. Consequently, we do not know whether our model can solve the strong CP problem in a universe which has been cool for only a finite time. We present several speculations about the cosmological evolution of our model.

Tom Banks, Michael Dine and Nathan Seiberg

hep-th

September

1991

https://arxiv.org/abs/hep-th/9109040

hep-th/9109041

Renormalization Group Patterns and C-Theorem in More Than Two Dimensions

We elaborate on a previous attempt to prove the irreversibility of the renormalization group flow above two dimensions. This involves the construction of a monotonically decreasing $c$-function using a spectral representation. The missing step of the proof is a good definition of this function at the fixed points. We argue that for all kinds of perturbative flows the $c$-function is well-defined and the $c$-theorem holds in any dimension. We provide examples in multicritical and multicomponent scalar theories for dimension $2<d<4$. We also discuss the non-perturbative flows in the yet unsettled case of the $O(N)$ sigma-model for $2\leq d\leq 4$ and large $N$.

Andrea Cappelli, Jos\'e Ignacio Latorre and Xavier Vilasis-Cardona

hep-th

September

1991

https://arxiv.org/abs/hep-th/9109041

hep-th/9109042

Singular Vectors and Conservation Laws of Quantum KdV type equations

We give a direct proof of the relation between vacuum singular vectors and conservation laws for the quantum KdV equation or equivalently for $\Phi_{(1,3)}$-perturbed conformal field theories. For each degree at which a classical conservation law exists, we find a quantum conserved quantity for a specific value of the central charge. Various generalizations ($N=1,2$ supersymmetric, Boussinesq) of this result are presented.

P. Di Francesco and P. Mathieu

hep-th

September

1991

https://arxiv.org/abs/hep-th/9109042

hep-th/9109043

Implications of Target Space Duality

Based on the assumption that the target space duality ($T\to 1/T$) is preserved even nonperturbatively, the properties of static string vacua are studied. A discussion of the effective four-dimensional supergravity action based on target-space modular symmetry $SL(2,{\bf Z})$ is presented. The nonperturbative superpotential removes the vacuum degeneracy with respect to the compactification modulus ($T$) generically breaks supersymmetry with negative cosmological constant. Charged matter fields get negative $(mass)^2$ signalling an additional instability of string vacuum and the blowing up of orbifold singularities. In addition for a class of modularly invariant potentials topologically stable stringy domain walls of nontrivial compaction modulus field configuration are found. They are supersymmetric solutions, thus saturating the Bogomolnyi bound. Their physical implications are discussed.

M. Cvetic

hep-th

September

1991

https://arxiv.org/abs/hep-th/9109043

hep-th/9109044

Topological Defects in the Moduli Sector of String Theory

We point out that the moduli sector of the $(2,2)$ string compactification with its nonperturbatively preserved non-compact symmetries is a fertile framework to study global topological defects, thus providing a natural source for the large scale structure formation. Based on the target space modular invariance of the nonperturbative superpotential of the four-dimensional N=1 supersymmetric string vacua, topologically stable stringy domain walls are found. They are supersymmetric solutions, thus saturating the Bogomolnyi bound. It is also shown that there are moduli sectors that allow for the global monopole-type and texture-type configurations whose radial stability is ensured by higher derivative terms.

M. Cvetic

hep-th

September

1991

https://arxiv.org/abs/hep-th/9109044

hep-th/9109045

Note on Discrete Gauge Anomalies

We consider the probem of gauging discrete symmetries. All valid constraints on such symmetries can be understood in the low energy theory in terms of instantons. We note that string perturbation theory often exhibits global discrete symmetries, which are broken non-perturbatively.

T. Banks and M. Dine

hep-th

September

1991

https://arxiv.org/abs/hep-th/9109045

hep-th/9109046

Hermitian vs. Anti-Hermitian 1-Matrix Models and Their Hierarchies

Building on a recent work of \v C. Crnkovi\'c, M. Douglas and G. Moore, a study of multi-critical multi-cut one-matrix models and their associated $sl(2,C)$ integrable hierarchies, is further pursued. The double scaling limits of hermitian matrix models with different scaling ans\"atze, lead, to the KdV hierarchy, to the modified KdV hierarchy and part of the non-linear Schr\"odinger hierarchy. Instead, the anti-hermitian matrix model, in the two-arc sector, results in the Zakharov-Shabat hierarchy, which contains both KdV and mKdV as reductions. For all the hierarchies, it is found that the Virasoro constraints act on the associated tau-functions. Whereas it is known that the ZS and KdV models lead to the Virasoro constraints of an $sl(2,C)$ vacuum, we find that the mKdV model leads to the Virasoro constraints of a highest weight state with arbitrary conformal dimension.

Timothy Hollowood, Luis Miramontes, Andrea Pasquinucci and Chiara Nappi

hep-th

September

1991

https://arxiv.org/abs/hep-th/9109046

hep-th/9109047

The supersymmetric sigma model and the geometry of the Weyl-Kac character formula

Field theoretic and geometric ideas are used to construct a chiral supersymmetric field theory whose ground state is a specified irreducible representation of a centrally extended loop group. The character index of the associated supercharge (an appropriate Dirac operator on $LG/T$) is the Weyl-K\v{a}c character formula which we compute explicitly by the steepest descent approximation.

Orlando Alvarez, I.M. Singer and Paul Windey

hep-th

September

1991

https://arxiv.org/abs/hep-th/9109047

hep-th/9109048

Elements of String Cosmology

Aspects of string cosmology for critical and non-critical strings are discussed emphasizing the necessity to account for the dilaton dynamics for a proper incorporation of ``large - small" duality. This drastically modifies the intuition one has with Einstein's gravity. For example winding modes, even though contribute to energy density, oppose expansion and if not annihilated will stop the expansion. Moreover we find that the radiation dominated era of the standard cosmology emerges quite naturally in string cosmology. Our analysis of non-critical string cosmology provides a reinterpretation of the (universal cover of the) recently studied two dimensional black hole solution as a conformal realization of cosmological solutions found previously by Mueller.

A. A. Tseytlin and C. Vafa

hep-th

September

1991

https://arxiv.org/abs/hep-th/9109048

hep-th/9109049

Extended Inflation from Strings

We study the possibility of extended inflation in the effective theory of gravity from strings compactified to four dimensions and find that it strongly depends on the mechanism of supersymmetry breaking. We consider a general class of string--inspired models which are good candidates for successful extended inflation. In particular, the $\omega$--problem of ordinary extended inflation is automatically solved by the production of only very small bubbles until the end of inflation. We find that the inflaton field could belong either to the untwisted or to the twisted massless sectors of the string spectrum, depending on the supersymmetry breaking superpotential.

J. Garcia-Bellido and M. quiros

hep-th

September

1991

https://arxiv.org/abs/hep-th/9109049

hep-th/9109050

Structure constants in the N=1 superoperator algebra

Using the Coulomb Gas formulation of N=1 Superconformal Field Theories, we extend the arguments of Dotsenko and Fateev for the bosonic case to evaluate the structure constants of N=1 minimal Superconformal Algebras in the Neveu-Schwarz sector.

L. Alvarez-Gaume, Ph. Zaugg

hep-th

September

1991

https://arxiv.org/abs/hep-th/9109050

hep-th/9109051

The Damping of Energetic Gluons and Quarks in High-Temperature QCD

When a gluon or a quark is sent through the hot QCD plasma it can be absorbed into the ambient heat bath and so can acquire an effective lifetime. At high temperatures and for weak couplings the inverse lifetime, or damping rate, for energetic quarks and transverse gluons, (those whose momenta satisfy $|\p| \gg gT$) is given by $\gamma(\p) = c\; g^2 \log\left({1\over g}\right)\; T + O(g^2T)$. We show that very simple arguments suffice both to fix the numerical coefficient, $c$, in this expression and to show that the $O(g^2T)$ contribution is incalculable in perturbation theory without further assumptions. For QCD with $N_c$ colours we find (expressed in terms of the casimir invariants $C_a=N_c$ and $C_f=(N_c^2-1)/(2N_c)$): $c_g=+{C_a\over 4\pi}$ for gluons and $c_q=+{C_f\over 4\pi}$ for quarks. These numbers agree with the more detailed calculations of Pisarski \etal\ but disagree with those of Lebedev and Smilga. The simplicity of the calculation also permits a direct verification of the gauge-invariance and physical sign of the result.

C.P. Burgess and A.L. Marini

hep-th

September

1991

https://arxiv.org/abs/hep-th/9109051

hep-th/9109052

Instantons and Solitons in Heterotic String Theory

This is a transcript of lectures given at the Sixth Jorge Andre Swieca Summer School in Theoretical Physics. The subject of these lectures is soliton solutions of string theory. We construct a class of exact conformal field theories possessing a spacetime soliton or instanton interpretation and present a preliminary discussion of their physical properties.

Curtis G. Callan, Jr

hep-th

September

1991

https://arxiv.org/abs/hep-th/9109052

hep-th/9109053

Gauge Coupling Running in Minimal SU(3)xSU(2)xU(1) Superstring Unification

We study the evolution of the gauge coupling constants in string unification schemes in which the light spectrum below the compactification scale is exactly that of the minimal supersymmetric standard model. In the absence of string threshold corrections the predicted values $\sin^2\theta _W=0.218$ and $\alpha _s=0.20$ are in gross conflict with experiment, but these corrections are generically important. One can express the string threshold corrections to $\sin^2\theta _W$ and $\alpha_s$ in terms of certain $modular$ $weights$ of quark, lepton and Higgs superfields as well as the $moduli$ of the string model. We find that in order to get agreement with the experimental measurements within the context of this $minimal$ scheme, certain constraints on the $modular$ $weights$ of the quark, lepton and Higgs superfields should be obeyed. Our analysis indicates that this $minimal$ $string$ $unification$

Luis Ibanez, Dieter Luest and Graham Ross

hep-th

September

1991

https://arxiv.org/abs/hep-th/9109053

hep-th/9109054

Integrable Discrete Linear Systems and One-Matrix Model

In this paper we analyze one-matrix models by means of the associated discrete linear systems. We see that the consistency conditions of the discrete linear system lead to the Virasoro constraints. The linear system is endowed with gauge invariances. We show that invariance under time-independent gauge transformations entails the integrability of the model, while the double scaling limit is connected with a time-dependent gauge transformation. We derive the continuum version of the discrete linear system, we prove that the partition function is actually the $\tau$-function of the KdV hierarchy and that the linear system completely determines the Virasoro constraints.

L. Bonora, M. Martellini and C. S. Xiong

hep-th

September

1991

https://arxiv.org/abs/hep-th/9109054

hep-th/9109055

Deformations, Symmetries and Topological Degrees of Freedom of the String

We discuss three closely related questions; i)~Given a conformal field theory, how may we deform it? ii)~What are the symmetries of string theory? and iii)~Does string theory have free parameters? We show that there is a distinct deformation of the stress tensor for every solution to the linearised covariant equations of motion for the massless modes of the Bosonic string, and use this result to discuss the symmetries of the string. We also find an additional finite dimensional space of deformations which may correspond to free parameters of string theory, or alternatively may be interpreted as topological degrees of freedom, perhaps analogous to the isolated states found in two dimensions.

Mark Evans and Ioannis Giannakis (Rockefeller University)

hep-th

September

1991

https://arxiv.org/abs/hep-th/9109055

hep-th/9109056

A representation of the exchange relation for affine Toda field theory

Vertex operators are constructed providing representations of the exchange relations containing either the S-matrix of a real coupling (simply-laced) affine Toda field theory, or its minimal counterpart. One feature of the construction is that the bootstrap relations for the S-matrices follow automatically from those for the conserved quantities, via an algebraic interpretation of the fusing of two particles to form a single bound state.

E. Corrigan and P.E. Dorey

hep-th

September

1991

https://arxiv.org/abs/hep-th/9109056

hep-th/9109057

On the possibility of $Z_N$ exotic supersymmetry in two dimensional Conformal Field Theory

We investigate the possibility to construct extended parafermionic conformal algebras whose generating current has spin $1+\frac{1}{K}$, generalizing the superconformal (spin 3/2) and the Fateev Zamolodchikov (spin 4/3) algebras. Models invariant under such algebras would possess $Z_K$ exotic supersymmetries satisfying (supercharge)$^K$ = (momentum). However, we show that for $K=4$ this new algebra allows only for models at $c=1$, for $K=5$ it is a trivial rephrasing of the ordinary $Z_5$ parafermionic model, for $K=6,7$ (and, requiring unitarity, for all larger $K$) such algebras do not exist. Implications of this result for existence of exotic supersymmetry in two dimensional field theory are discussed.

F.Ravanini

hep-th

September

1991

https://arxiv.org/abs/hep-th/9109057

hep-th/9109058

Quantum Symmetries in 2D Massive Field Theories

We review various aspects of (infinite) quantum group symmetries in 2D massive quantum field theories. We discuss how these symmetries can be used to exactly solve the integrable models. A possible way for generalizing to three dimensions is shortly described.

Denis Bernard

hep-th

September

1991

https://arxiv.org/abs/hep-th/9109058

hep-th/9110001

The Lie h-Invariant Conformal Field Theories and the Lie h-Invariant Graphs

We use the Virasoro master equation to study the space of Lie h-invariant conformal field theories, which includes the standard rational conformal field theories as a small subspace. In a detailed example, we apply the general theory to characterize and study the Lie h-invariant graphs, which classify the Lie h-invariant conformal field theories of the diagonal ansatz on SO(n). The Lie characterization of these graphs is another aspect of the recently observed Lie group-theoretic structure of graph theory.

M.B. Halpern, E.B. Kiritsis, N.A. Obers

hep-th

October

1991

https://arxiv.org/abs/hep-th/9110001

hep-th/9110002

The Effective String of 3D Gauge Systems at the Deconfining Transition

It is argued that the effective string of whatever 3D gauge system at the deconfining transition is universally described by the minimal $N=2$ extended superconformal theory at $c=1$. A universal value of the critical temperature is predicted.

M. Caselle and F.Gliozzi

hep-th

October

1991

https://arxiv.org/abs/hep-th/9110002

hep-th/9110003

Field Identification in Non-Unitary Diagonal Cosets

We study the nonunitary diagonal cosets constructed from admissible representations of Kac-Moody algebras at fractional level, with an emphasis on the question of field identification. Generic classes of field identifications are obtained from the analysis of the modular S matrix. These include the usual class related to outer automorphisms, as well as some intrinsically nonunitary field identifications. They allow for a simple choice of coset field representatives where all field components of the coset are associated with integrable finite weights.

Pierre Mathieu, David Senechal and Mark Walton

hep-th

October

1991

https://arxiv.org/abs/hep-th/9110003

hep-th/9110004

Manifestly $O(d,d)$ Invariant Approach to Space-Time Dependent String Vacua

An $O(d,d)$ symmetry of the manifold of string vacua that do not depend on $d$ (out of $D$) space-time coordinates has been recently identified. Here we write down, for $d=D-1$, the low energy equations of motion and their general solution in a manifestly $O(d,d)$-invariant form, pointing out an amusing similarity with the renormalization group framework. Previously considered cosmological and black hole solutions are recovered as particular examples.

K.A. Meissner and G. Veneziano

hep-th

October

1991

https://arxiv.org/abs/hep-th/9110004

hep-th/9110005

Three-Dimensional Gravity and String Ghosts

It is known that much of the structure of string theory can be derived from three-dimensional topological field theory and gravity. We show here that, at least for simple topologies, the string diffeomorphism ghosts can also be explained in terms of three-dimensional physics.

S. Carlip and I. I. Kogan

hep-th

October

1991

https://arxiv.org/abs/hep-th/9110005

hep-th/9110006

On the Solution of Topological Landau-Ginzburg Models with $c=3$

The solution is given for the $c=3$ topological matter model whose underlying conformal theory has Landau-Ginzburg model $W=-\qa (x^4 +y^4)+\af x^2y^2$. While consistency conditions are used to solve it, this model is probably at the limit of such techniques. By using the flatness of the metric of the space of coupling constants I rederive the differential equation that relates the parameter \af\ to the flat coordinate $t$. This simpler method is also applied to the $x^3+y^6$-model.

Z. Maassarani

hep-th

October

1991

https://arxiv.org/abs/hep-th/9110006

hep-th/9110007

Some aspects of free field resolutions in 2D CFT with application to the quantum Drinfeld-Sokolov reduction

We review some aspects of the free field approach to two-dimensional conformal field theories. Specifically, we discuss the construction of free field resolutions for the integrable highest weight modules of untwisted affine Kac-Moody algebras, and extend the construction to a certain class of admissible highest weight modules. Using these, we construct resolutions of the completely degenerate highest weight modules of W-algebras by means of the quantum Drinfeld-Sokolov reduction. As a corollary we derive character formulae for these degenerate highest weight modules.

P. Bouwknegt, J. McCarthy, and K. Pilch

hep-th

October

1991

https://arxiv.org/abs/hep-th/9110007

hep-th/9110008

Duality Invariant Effective String Actions and Minimal Superstring Unification

Some results are presented concerning duality invariant effective string actions and the construction of automorphic functions for general (2,2) string compactifications. These considerations are applied in order to discuss the {\it minimal} unification of gauge coupling constants in orbifold compactifications with special emphasis on string threshold corrections.

D. Luest

hep-th

October

1991

https://arxiv.org/abs/hep-th/9110008

hep-th/9110009

Constituent Quarks as Solitons

We exhibit soliton solutions of QCD in two dimensions that have the quantum numbers of quarks. They exist only for quarks heavier than the dimensional gauge coupling, and have infinite energy, corresponding to the presence of a string carrying the non-singlet color flux off to spatial infinity. The quark solitons also disappear at finite temperature, as the temperature-dependent effective quark mass is reduced in the approach to the quark/hadron phase transition.

John Ellis, Yitzhak Frishman and Marek Karliner

hep-th

October

1991

https://arxiv.org/abs/hep-th/9110009

hep-th/9110010

Quantum Solitons in Affine Toda Field Theories

The spectra of $A_r$ affine Toda field theories with imaginary coupling constant, are investigated. Soliton solutions are found, which, despite the non-unitary form of the Lagrangian, have real classical masses and are stable to small perturbations. The quantum corrections to the soliton masses are determined, to lowest order in $\hbar$. The solitons have the same spectrum as the fundamental Toda particles; a feature that is preserved in the quantum theory.

Timothy Hollowood

hep-th

October

1991

https://arxiv.org/abs/hep-th/9110010