arXiv papers from March 1992

Anamaria Font

We derive the period structure of several one-modulus Calabi-Yau manifolds. With this knowledge we then obtain the generators of the duality group and the mirror map that defines the physical variable $t$ representing the radius of compactification. We also describe the fundamental region of $t$ and discuss its relation with automorphic functions. As a bypro

M. Kenmoku, E. Kitajima, Y. Okamoto, K. Shigemoto

We consider an addition of the term which is a square of the scalar curvature to the Einstein-Hilbert action. Under this generalized action, we attempt to explain i) the flat rotation curves observed in spiral galaxies, which is usually attributed to the existence of dark matter, and ii) the contradicting observations of uniform cosmic microwave background a

Peter Cho

Charm and bottom mesons and baryons are incorporated into a low energy chiral Lagrangian. Interactions of the heavy hadrons with light octet Goldstone bosons are studied in a framework which represents a synthesis of chiral perturbation theory and the heavy quark effective theory. The differential decay rate for the semileptonic process $\LBzero \to \Sigma_c

Dan Kabat, Miguel Ortiz

Various approaches to high energy forward scattering in quantum gravity are compared using the eikonal approximation. The massless limit of the eikonal is shown to be equivalent to other approximations for the same process, specifically the semiclassical calculation due to G. 't Hooft and the topological field theory due to H. and E. Verlinde. This compariso

S. V. Ketov, S. J. Gates,, H. Nishino

The properties of Dirac gamma matrices in a four-dimensional space-time with the $(2,2)$ signature are studied. The basic spinors are classified, and the existence of Majorana-Weyl spinors is noted. Supersymmetry in $2 + 2$ dimensions is discussed, and the existence of the {\it real chiral} scalar supermultiplet is discovered. Supersymmetric {\it self-dual}

James H. Horne, Gary T. Horowitz

It is shown that an arbitrarily small amount of angular momentum can qualitatively change the properties of extremal charged black holes coupled to a dilaton. In addition, the gyromagnetic ratio of these black holes is computed and an exact rotating black string solution is presented.

Abhay Ashtekar, Carlo Rovelli, Lee Smolin

Results that illuminate the physical interpretation of states of nonperturbative quantum gravity are obtained using the recently introduced loop variables. It is shown that: i) While local operators such as the metric at a point may not be well-defined, there do exist {\it non-local} operators, such as the area of a given 2-surface, which can be regulated di

H. Nishino, S. J. Gates,, S. V. Ketov

We present the Green-Schwarz $\s\-$model coupled to the $N=1$ {\it {supersymmetric}} Yang-Mills and supergravity in a four-dimensional space-time with the indefinite signature $(+,+,-,-)$. We first confirm the $\k\-$invariance of the Green-Schwarz action, and show that all the $\b\-$functions for the backgrounds vanish consistently after the use of their sup

S. J. Gates,, H. Nishino, S. V. Ketov

The $N=2$ supersymmetric {\it self-dual} Yang-Mills theory and the $N=4$ and $N=2$ {\it self-dual} supergravities in $2+2$ space-time dimensions are formulated for the first time. These formulations utilize solutions of the Bianchi identities subject to the super-Yang-Mills or supergravity constraints in the relevant $N$-extended superspace with the space-ti

T. Tjin

Finite versions of W-algebras are introduced by considering (symplectic) reductions of finite dimensional simple Lie algebras. In particular a finite analogue of $W^{(2)}_3$ is introduced and studied in detail. Its unitary and non-unitary, reducible and irreducible highest weight representations are constructed.

Thomas G. Rizzo

We explore the phenomenology of new R-parity violating operators that can occur in E6 models. The set of allowed operators is found to depend sensitively on the nature of the extension of the standard model gauge group. These new interactions lead to additional production processes for the exotic particles in such models and allow the LSP to decay but with a

T. J. Hollowood

The problem of quantizing a class of two-dimensional integrable quantum field theories is considered. The classical equations of the theory are the complex $sl(n)$ affine Toda equations which admit soliton solutions with real masses. The classical scattering theory of the solitons is developed using Hirota's solution techniques. A form for the soliton $S$-ma

Z. Kunszt, F. Zwirner

We study the Higgs sector of the Minimal Supersymmetric Standard Model, in the context of proton-proton collisions at LHC and SSC energies. We assume a relatively heavy supersymmetric particle spectrum, and include recent results on one-loop radiative corrections to Higgs-boson masses and couplings. We begin by discussing present and future constraints from

Andrew Parkes

We make a change of field variables in the J formulation of self-dual Yang--Mills theory. The field equations for the resulting algebra valued field are derivable from a simple cubic action. The cubic interaction vertex is different from that considered previously from the N=2 string, however, perturbation theory with this action shows that the only non-vani

E. Abdalla, M. Forger

We derive the current algebra of principal chiral models with a Wess-Zumino term. At the critical coupling where the model becomes conformally invariant (Wess-Zumino-Novikov-Witten theory), this algebra reduces to two commuting Kac-Moody algebras, while in the limit where the coupling constant is taken to zero (ordinary chiral model), we recover the current

Juan M. López, Miguel A. Rodríguez

We contrast analytical results of a variety of growth models involving subdiffusion, thermal noise and quenched disorder with simulations of these models, concluding that the assumed self-affinity property is more an exception than a rule. In our two dimensional models, self-affine surfaces may only appear when the roughness exponent is $\chi = 1/2$ or $\chi

Supriya K. Kar, Alok Kumar

The background for string propagation is obtained by a chiral gauging of the $SL(2,R)$ Wess-Zumino-Witten model. It is shown explicitly that the resulting background fields satisfy the field equations of the three dimensional string effective action and the target space has curvature singularity. Close connection of our solution with the three dimensional bl

G. P. Korchemsky, A. V. Radyushkin

It is shown that, in QCD, the same universal function $\Gamma_{cusp}(\vartheta, \alpha_\s)$ determines the infrared behaviour of the on-shell quark form factor, the velocity-dependent anomalous dimension in the heavy quark effective field theory (HQET) and the renormalization properties of the vacuum averaged Wilson lines with a cusp. It is demonstrated that

Sergei V. Pokrovsky

A quantum group analysis is applied to the Sine-Gordon model (or may be its version) in a strong-coupling regime. Infinitely many bound states are found together with the corresponding S-matrices. These new solutions of the Yang-Baxter eqations are related to some reducible representations of the quantum $sl(2)$ algebra resembling the Kac-Moody algebra repre

Oscar F. Hernandez, Brian R. Hill

It is hoped that the accuracy of a variety of lattice calculations will be improved by perturbatively eliminating effects proportional to the lattice spacing. In this paper, we apply this improvement program to the heavy quark effective theory currents which cause a heavy quark to decay to a light quark, and renormalize the resulting operators to order $\alp

V. Barger, M. S. Berger, T. Han, M. Zralek

By evolution of fermion mass matrices of the Fritzsch and the Georgi-Jarlskog forms from the supersymmetric grand unified scale, DHR obtained predictions for the quark masses and mixings. Using Monte Carlo methods we test these predictions against the latest determinations of the mixings, the CP-violating parameter epsilon_K and the B_d^0--Bbar_d^0 mixing pa

Francisco D. Mazzitelli

We consider the midisuperspace of four dimensional spherically symmetric metrics and the Kantowski-Sachs minisuperspace contained in it. We discuss the quantization of the midisuperspace using the fact that the dimensionally reduced Einstein Hilbert action becomes a scalar-tensor theory of gravity in two dimensions. We show that the covariant regularization

I. Antoniadis, E. Gava, K. S. Narain

We study moduli dependent threshold corrections to gravitational couplings in the case of the heterotic string compactified on a symmetric orbifold, for untwisted moduli, extending previous analysis on gauge couplings. Like in the gauge case, the contribution comes entirely from the spacetime $N=2$ sector. As a byproduct, this calculation provides a simple d

P. S. Howe, G. Papadopoulos

Power-counting arguments based on extended superfields have been used to argue that two-dimensional supersymmetric sigma models with (4,0) supersymmetry are finite. This result is confirmed up to three loop order in pertubation theory by an explicit calculation using (1,0) superfields. In particular, it is shown that the finite counterterms which must be int

Lev Rozansky, Herbert Saleur

We carry on the study of the Alexander Conway invariant from the quantum field theory point of view started in \cite{RS91}. We first discuss in details $S$ and $T$ matrices for the $U(1,1)$ super WZW model and obtain, for the level $k$ an integer, new finite dimensional representations of the modular group. These have the remarkable property that some of the

V. G. J. Rodgers

This manuscripts corrects some minor error in the paper, Mod. Phys. Lett. A 6 1893 (1991)

Ralph Lano, V. G. J. Rodgers

We are able to show that BF theories naturally emerge from the coadjoint orbits of $W_2$ and $w_\infty$ algebras which includes a Kac-Moody sector. Since QCD strings can be identified with a BF theory, we are able to show a relationship between the orbits and monopole-string solutions of QCD. Furthermore, we observe that when 4D gravitation is cast into a BF

S. Cecotti, C. Vafa

We study some aspects of 2d supersymmetric sigma models on orbifolds. It turns out that independently of whether the 2d QFT is conformal the operator products of twist operators are non-singular, suggesting that massive (non-conformal) orbifolds also `resolve singularities' just as in the conformal case. Moreover we recover the OPE of twist operators for con

A. Libgober

The homotopy group $\pi_{n-k} ({\bf C}^{n+1}-V)$ where $V$ is a hypersurface with a singular locus of dimension $k$ and good behavior at infinity is described using generic pencils. This is analogous to the van Kampen procedure for finding a fundamental group of a plane curve. In addition we use a certain representation generalizing the Burau representation

M. Drees, R. M. Godbole

We discuss various reactions at future e+e- and gamma-gamma colliders involving real (beamstrahlung or backscattered laser) or quasi--real (bremsstrahlung) photons in the initial state and hadrons in the final state. The production of two central jets with large pT is described in some detail; we give distributions for the rapidity and pT of the jets as well

Dileep P. Jatkar

We study string theory in the background of a two-dimensional black hole which is described by an $SL(2, R)/U(1)$ coset conformal field theory. We determine the spectrum of this conformal field theory using supersymmetric quantum mechanics and give an explicit form of the vertex operators in terms of the Jacobi functions. We also discuss the applicability of

C. Destri, H. J. de Vega

We solve the RSOS($p$) models on the light--cone lattice with fixed boundary conditions by disentangling the type II representations of $SU(2)_q$, at $q=e^{i\pi/p}$, from the full SOS spectrum obtained through Algebraic Bethe Ansatz. The rule which realizes the quantum group reduction to the RSOS states is that there must not be {\it singular} roots in the s

C. Destri, H. J. de Vega

We present a new approach to the calculation of thermodynamic functions for crossing-invariant models solvable by Bethe Ansatz. In the case of the XXZ Heisemberg chain we derive, for arbitrary values of the anysotropy, a {\bf single} non--linear integral equation from which the free energy can be exactly calculated. The high--temperature expansion follows in

Didier A Depireux

Given the two boson representation of the conformal algebra \hat W_\infty, the second Hamiltonian structure of the KP hierarchy, I construct a bi-Hamiltonian hierarchy for the two associated currents. The KP hierarchy appears as a composite of this new and simpler system. The bi-Hamiltonian structure of the new hierarchy gives naturally all the Hamiltonian s

Gregory Moore

We consider the Sine-Gordon model coupled to 2D gravity. We find a nonperturbative expression for the partition function as a function of the cosmological constant, the SG mass and the SG coupling constant. At genus zero, the partition function exhibits singularities which are interpreted as signals of phase transitions. A semiclassical picture of one of the

G. Moore, R. Plesser

We find the general solution to Polchinski's classical scattering equations for $1+1$ dimensional string theory. This allows efficient computation of scattering amplitudes in the standard Liouville $\times$ $c=1$ background. Moreover, the solution leads to a mapping from a large class of time-dependent collective field theory backgrounds to corresponding non

S. B. Giddings

This paper revisits the conundrum faced when one attempts to understand the dynamics of black hole formation and evaporation without abandoning unitary evolution. Previous efforts to resolve this puzzle assume that information escapes in corrections to the Hawking process, that an arbitrarily large amount of information is transmitted by a planckian energy o

J. Distler, M. Doyle

Green and Seiberg showed that, in simple treatments of fermionic string theory, it is necessary to introduce contact interactions when vertex operators collide. Otherwise, certain superconformal Ward identities would be violated. In this note, we show how these contact terms arise naturally when proper account is taken of the superconformal geometry involved

Matt Visser

Considerable interest has recently been expressed in (static spherically symmetric) blackholes in interaction with various classical matter fields (such as electromagnetic fields, dilaton fields, axion fields, Abelian Higgs fields, non--Abelian gauge fields, {\sl etc}). A common feature of these investigations that has not previously been remarked upon is th

Daniel Cangemi, Roman Jackiw

It is shown that the currently studied ``string-inspired'' model for gravity on a line can be formulated as a gauge invariant theory based on the Poincar\'e group with central extension -- a formulation that complements and simplifies H.~Verlinde's construction based on the unextended Poincar\'e group.

Yingchen Li, Motohico Mulase

A new relation between Prym varieties of arbitrary morphisms of algebraic curves and integrable systems is discovered. The action of maximal commutative subalgebras of the formal loop algebra of GL(n) defined on certain infinite-dimensional Grassmannians is studied. It is proved that every finite-dimensional orbit of the action of traceless elements of these

G. Bonacina, A. Gamba, M. Martellini

We show that Euclidean 3D-gravity coupled to a Gaussian scalar massive matter field in first-order dreibein formalism gives a quantum theory which has a finite perturbative expansion around a non-vanishing background. We also discuss a possible mechanism to generate a non-trivial background metric starting from Rovelli-Smolin's loop observables.

L. Susskind, L. Thorlacius

The puzzles of black hole evaporation can be studied in the simplified context of 1+1 dimensional gravity. The semi-classical equations of Callan, Giddings, Harvey and Strominger provide a consistent description of the evaporation process which we describe in detail. We consider the possibility that black hole evolution leads to massive stable remnants. We s

Emili Bifet, Franco Ghione, Maurizio Letizia

The aim of this paper is to present an algebro-geometric approach to the study of the geometry of the moduli space of stable bundles on a smooth projective curve defined over an algebraically closed field $k$, of arbitrary characteristic. This establishes a bridge between the arithmetic approach of Harder, Narasimhan et al. and the gauge group approach of At

Markus A. Luty

We consider a theory of gauge fields and fermions which we argue gives rise to dynamics similar to that of the Nambu--Jona-Lasinio (NJL) model when a gauge coupling constant is appropriately fine-tuned. We discuss the application of this model to dynamical electroweak symmetry breaking by a top-quark condensate. In this model, custodial symmetry is violated

M. Carfora, M. Martellini, A. Marzuoli

We provide a non-perturbative geometrical characterization of the partition function of $n$-dimensional quantum gravity based on a coarse classification of riemannian geometries. We show that, under natural geometrical constraints, the theory admits a continuum limit with a non-trivial phase structure parametrized by the homotopy types of the class of manifo

S. W. Hawking

Callan, Giddings, Harvey and Strominger have proposed an interesting two dimensional model theory that allows one to consider black hole evaporation in the semi-classical approximation. They originally hoped the black hole would evaporate completely without a singularity. However, it has been shown that the semi-classical equations will give a singularity wh

A. Galperin, E. Sokatchev

We propose a new formulation of the $D=10$ Brink-Schwarz superparticle which is manifestly invariant under both the target-space super-Poincar\'e group and the world-line local $N=8$ superconformal group. This twistor-like construction naturally involves the sphere $S^8$ as a coset space of the $D=10$ Lorentz group. The action contains only a finite set of a

D. B. DeLaney, S. Jadach, Ch. Shio, G. Siopsis

We use the theory of Yennie, Frautschi and Suura to realize, via Monte Carlo methods, the process $f\,\bbbarf\to f'\,\bbbarf'+n\gamma$ at SSC and LHC energies, where $f$ and $f'$ are quarks or leptons. QED infrared divergences are canceled to all orders in perturbation theory. The resulting Monte Carlo event generator, SSC-YFS2, is used to study the effects

C. P. Burgess, David London

Motivated by past and recent analyses we critically re-examine the use of effective lagrangians in the literature to constrain new physics and to determine the `physics reach' of future experiments. We demonstrate that many calculations, such as those involving anomalous trilinear gauge-boson couplings, either considerably overestimate loop-induced effects,

C. P. Burgess, David London

Recently, calculations which consider the implications of anomalous trilinear gauge-boson couplings, both at tree-level and in loop-induced processes, have been criticized on the grounds that the lagrangians employed are not \gwk gauge invariant. We prove that, in fact, the general Lorentz-invariant and $U(1)_\em$ invariant but {\it not} $SU_L(2)\times U_Y(1

Timothy J. Ford

The purpose of this article is to show how one might compute the \'etale cohomology groups $H^p_{\acute{e}t}(X,G_m)$ in degrees $p=0$, $1$ and $2$ of a toric variety $X$ with coefficients in the sheaf of units. The method is to reduce the computation down to the problem of diagonalizing a matrix with integral coefficients. The procedure outlined in this arti

F. Bonechi, E. Celeghini, R. Giachetti, E. Sorace

Inhomogeneous quantum groups are shown to be an effective algebraic tool in the study of integrable systems and to provide solutions equivalent to the Bethe ansatz. The method is illustrated on the 1D Heisenberg ferromagnet whose symmetry is shown to be the quantum Galilei group Gamma_q(1) here introduced. Both the single magnon and the s=1/2 bound states of

Dan Christensen, Robert B. Mann

We investigate the causal structure of $(1+1)$-dimensional spacetimes. For two sets of field equations we show that at least locally any spacetime is a solution for an appropriate choice of the matter fields. For the theories under consideration we investigate how smoothness of their black hole solutions affects time orientation. We show that if an analog to

Hiroki Fukutaka

The path-integral measure of linearized gravity around a saddle-point background with the cosmological term is considered in order to study the conformal rotation prescription proposed by Gibbons, Hawking and Perry. It is also argued that the most generally used measure, i.e., the covariant path-integral measure, does not give us a one-loop partition functio

E. S. Fradkin, V. Ya Linetsky

A list of superconformal chiral operator product expansion algebras with quadratic nonlinearity in two dimensions is completed on the basis of the known classification of little conformal Lie superalgebras. In addition to the previously known cases and the constructed in our previous paper exceptional $N=8$ superalgebra associated with $F(4)$, a novel except

A. Marshakov, A. Mironov, A. Morozov, M. Olshanetsky

We propose to study a generalization of the Klebanov-Polyakov-Witten (KPW) construction for the algebra of observables in the $c = 1$ string model to theories with $c > 1$. We emphasize the algebraic meaning of the KPW construction for $c = 1$ related to occurrence of a {\it model} of {\it SU}(2) as original structure on the algebra of observables. The attem

S. Kharchev, A. Marshakov, A. Mironov, A. Morozov

We represent the partition function of the Generalized Kontsevich Model (GKM) in the form of a Toda lattice $\tau$-function and discuss various implications of non-vanishing "negative"- and "zero"-time variables: the appear to modify the original GKM action by negative-power and logarithmic contributions respectively. It is shown that so deformed $\tau$-func

B. Birnir, S. B. Giddings, J. A. Harvey, A. Strominger

Static solutions of large-$N$ quantum dilaton gravity in $1+1$ dimensions are analyzed and found to exhibit some unusual behavior. As expected from previous work, infinite-mass solutions are found describing a black hole in equilibrium with a bath of Hawking radiation. Surprisingly, the finite mass solutions are found to approach zero coupling both at the ho

Julian Barbour, Lee Smolin

Dynamical systems of a new kind are described, which are motivated by the problem of constructing diffeomorphism invariant quantum theories. These are based on the extremization of a non-local and non-additive quantity that we call the variety of a system. In these systems all dynaqmical variables refer to relative coordinates or, more generally, describe re

Bernd Bruegmann, Rodolfo Gambini, Jorge Pullin

Solutions to both the diffeomorphism and the hamiltonian constraint of quantum gravity have been found in the loop representation, which is based on Ashtekar's new variables. While the diffeomorphism constraint is easily solved by considering loop functionals which are knot invariants, there remains the puzzle why several of the known knot invariants are als

E. Gates, L. M. Krauss, M. White

The complete and concurrent Homestake and Kamiokande solar neutrino data sets (including backgrounds), when compared to detailed model predictions, provide no unambiguous indication of the solution to the solar neutrino problem. All neutrino-based solutions, including time-varying models, provide reasonable fits to both the 3 year concurrent data and the ful

F. Alexander Bais, Peter van Driel, Mark de Wild Propitius

We study the effect of a Chern-Simons term in a theory with discrete gauge group H, which in (2+1)-dimensional space time describes (non-abelian) anyons. As in a previous paper, we emphasize the underlying algebraic structure, namely the Hopf algebra D(H). We argue on physical grounds that the addition of a Chern-Simons term in the action leads to a non-triv

F. Alexander Bais, Peter van Driel, Mark de Wild Propitius

We analyse the fusion, braiding and scattering properties of discrete non-abelian anyons. These occur in (2+1)-dimensional theories where a gauge group G is spontaneously broken down to some discrete subgroup H. We identify the quantumnumbers of the electrically and magnetically charged sectors of the remaining discrete gauge theory, and show that on the qua

Jean-Loup Gervais, Mikhail V. Saveliev

NON-ABELIAN TODA THEORIES are shown to provide EXACTLY SOLVABLE conformal systems in the presence of a BLACK HOLE which may be regarded as describing a string propagating in target space with a black-hole metric. These theories are associated with non-canonical $\bf Z$-gradations of simple algebras, where the gradation-zero subgroup is non-abelian. They corr

Andrei Linde

We discuss relationship between inflation and various models of production of density inhomogeneities due to strings, global monopoles, textures and other topological and non-topological defects. Neither of these models leads to a consistent cosmological theory without the help of inflation. However, each of these models can be incorporated into inflationary

Lawrence M. Krauss, Soo-Jong Rey

Utilizing results on the cosmology of anomalous discrete symmetries we show that models of spontaneous CP violation can in principle avoid the domain wall problem first pointed out by Zel'dovich, Kobzarev and Okun. A small but nonzero $\theta_{QCD}$ explicitly breaks CP and can lift the degeneracy of the two CP conjugate vacua through nonperturbative effects

Anton Rebhan

Burgess and Marini have recently pointed out that the leading contribution to the damping rate of energetic gluons and quarks in the QCD plasma, given by $\gamma=c g^2\ln(1/g)T$, can be obtained by simple arguments obviating the need of a fully resummed perturbation theory as developed by Braaten and Pisarski. Their calculation confirmed previous results of

F. del Aguila, M. Martinez, M. Quiros

We perform a fit to precise electroweak data to determine the Higgs and top masses. Penalty functions taking into account their production limits are included. We find ${\displaystyle m_H=65^{+245}_{-4}\ GeV}$ and ${\displaystyle m_t=122^{+25}_{-20}\ GeV}$. However whereas the top $\chi^2$ distribution behaves properly near the minimum, the Higgs $\chi^2$ di

F. De Jonghe, R. Siebelink, W. Troost

We present an invariant regularisation scheme to compute two dimensional induced gauge theory actions, that is local in Polyakov's variables, but nonlocal in the original gauge potentials. Our method sheds light on the locality of this induced action, and leads to a straightforward proof that the $\varepsilon$-anomaly in $W_3$-gravity is completely given by

I. T. Ivanov, D. B. Uglov

R-matrices for the semicyclic representations of U_qsl^(2) are found as a limit in the checkerboard chiral Potts model.

G. Aldazabal, J. M. Maldacena

A method for quantizing the bidimensional N=2 supersymmetric non-linear sigma model is developed. This method is both covariant under coordinate transformations (concerning the order relevant for calculations) and explicitly N=2 supersymmetric. The OPE of the supercurrent is computed accordingly, including also the dilaton. By imposing the N=2 superconformal

C. Gomez, G. Sierra

We show that the anisotropic Heisenberg-Ising chains with higher spin allow, for special values of the anisotropy, integrable deformations intimately related to the theory of quantum groups at roots of unity. For the spin one case we construct and study the symmetries of the hamiltonian which depends on a spectral variable belonging to an elliptic curve. One

Kanehisa Takasaki

A group of volume-preserving diffeomorphisms in 3D turns out to play a key role in an Einstein-Maxwell theory whose Weyl tensor is selfdual and whose Maxwell tensor has algebraically general anti-selfdual part. This model was first introduced by Flaherty and recently studied by Park as an integrable deformation of selfdual gravity. A twisted volume form on t

A. A. Tseytlin

We discuss time - dependent solutions of the leading order string effective equations for a non-zero central charge deficit and curved maximally symmetric space. Some regular solutions are found for the case of non-trivial antisymmetric tensor and vector backgrounds (in various dimensions) and negative spatial curvature. It remains an open question which con

Elise E. Cawley

The group $SL(n,{\bf Z})$ acts linearly on $\R^n$, preserving the integer lattice $\Z^{n} \subset \R^{n}$. The induced (left) action on the n-torus $\T^{n} = \R^{n}/\Z^{n}$ will be referred to as the ``standard action''. It has recently been shown that the standard action of $SL(n,\Z)$ on $\T^n$, for $n \geq 3$, is both topologically and smoothly rigid. That

Roger Brooks

A formal relationship between scattering amplitudes in critical bosonic string theory and correlation functions of operators in topological string theory is found.

Petr Horava

The exact black hole solution of 2D closed string theory has, as any other maximally extended Schwarzschild-like geometry, two asymptotically flat spacetime domains. One can get rid of the second domain by gauging the discrete symmetry on the SL(2,R)/U(1) coset that interchanges the two asymptotic domains and preserves the Kruskal time orientation everywhere

R. Holman, T. W. B. Kibble, Soo-Jong Rey

We investigate the dynamics of monopole annihilation by the Langacker-Pi mechanism. We find taht considerations of causality, flux-tube energetics and the friction from Aharonov-Bohm scatteering suggest that the monopole annihilation is most efficient if electromagnetism is spontaneously broken at the lowest temperature ($T_{em} \approx 10^6 GeV$) consistent

Ivan K. Kostov, Matthias Staudacher

We exhibit the multicritical phase structure of the loop gas model on a random surface. The dense phase is reconsidered, with special attention paid to the topological points $g=1/p$. This phase is complementary to the dilute and higher multicritical phases in the sense that dense models contain the same spectrum of bulk operators (found in the continuum by

Kurt Haller, Edwin Lombridas

We discuss the canonical quantization of Quantum Electrodynamics in $2+1$ dimensions, with a Chern-Simons topological mass term and gauge-covariant coupling to a Dirac spinor field. A gauge-fixing term is used which generates a canonical momentum for $A_0$, so that there are no primary constraints on operator-valued fields. Gauss's Law and the gauge conditio

Andrea Pasquinucci

In this note I discuss some features of the topological theory obtained from the Zakharov-Shabat (or general sl(2,C)) hierarchy, and comment on some possible physical and/or mathematical interpretations of it.

C. K. Zachos

The statistics-altering operators present in the limit $q=-1$ of multiparticle SU_q(2)-invariant subspaces parallel the action of such operators which naturally occur in supersymmetric theories. We illustrate this heuristically by comparison to a toy $N=2$ superymmetry algebra, and ask whether there is a supersymmetry structure underlying SU(2)_q at that lim

E. Gates L. Krauss J. Terning

We examine the issue of monopole annihilation at the electroweak scale induced by flux tube confinement, concentrating first on the simplest possibility---one which requires no new physics beyond the standard model. Monopoles existing at the time of the electroweak phase transition may trigger $W$ condensation which can confine magnetic flux into flux tubes.

Peter Haagensen, Jose I. Latorre

We extend the method of differential renormalization to massive quantum field theories treating in particular $\ph4$-theory and QED. As in the massless case, the method proves to be simple and powerful, and we are able to find, in particular, compact explicit coordinate space expressions for the finite parts of two notably complicated diagrams, namely, the 2

M. Blau

These lecture notes give an introductory account of an approach to cohomological field theory due to Atiyah and Jeffrey which is based on the construction of Gaussian shaped Thom forms by Mathai and Quillen. Topics covered are: an explanation of the Mathai-Quillen formalism for finite dimensional vector bundles; the definition of regularized Euler numbers of

J. Lopez, D. Nanopoulos, K. Yuan

We present an extensive search for a general class of flipped $SU(5)$ models built within the free fermionic formulation of the heterotic string. We describe a set of algorithms which constitute the basis for a computer program capable of generating systematically the massless spectrum and the superpotential of all possible models within the class we conside

H. Lu, C. N. Pope, S. Schrans, X. J. Wang

We discuss new realisations of $W$ algebras in which the currents are expressed in terms of two arbitrary commuting energy-momentum tensors together with a set of free scalar fields. This contrasts with the previously-known realisations, which involve only one energy-momentum tensor. Since realisations of non-linear algebras are not easy to come by, the fact

R. Holman, S. D. H. Hsu, T. Kephart, E. Kolb

We examine the sensitivity of several solutions of the strong-CP problem to violations of global symmetries by Planck scale physics. We find that the Peccei-Quinn solution is extremely sensitive to U(1)_PQ violating operators of dimension less than 10. We construct models in which the PQ symmetry is protected by gauge symmetries to the requisite level.

Oscar F. Hernandez

We present a class of models in which the top quark, by mixing with new physics at a higher energy scale, is naturally heavier than the other standard model particles. We take this new physics to be extended color. Our models contain new particles with masses between 100 GeV and 1 TeV, some of which may be just within the reach of the next generation of expe

G. W. Gibbons, M. E. Ortiz, F. Ruiz Ruiz, T. M. Samols

A variation on the abelian Higgs model, with global SU(2) x local U(1) symmetry broken to global U(1) was recently shown by Vachaspati and Achucarro to admit stable, finite energy cosmic string solutions even though the manifold of minima of the potential energy does not have non-contractible loops. Here the most general solutions, both in the single and mul

F. Zwirner

The motivations for low-energy supersymmetry and the main features of the minimal supersymmetric extension of the Standard Model are reviewed. Possible non-minimal models and the issue of gauge coupling unification are also discussed. Theoretical results relevant for supersymmetric particle searches at present and future accelerators are presented, with emph

Clifford Johnson, Tim Morris, Bill Spence

A generalisation of the non--perturbatively stable solutions of string equations which respect the KdV flows, obtained recently for the $(2m-1,2)$ conformal minimal models coupled to two--dimensional quantum gravity, is presented for the $(p,q)$ models. These string equations are the most general string equations compatible with the $q$--th generalised KdV f

Joaquim Gomis, Hiroshi Suzuki

Based on a path integral prescription for anomaly calculation, we analyze an effective theory of the two-dimensional $N=2$ supergravity, i.e., $N=2$ super-Liouville theory. We calculate the anomalies associated with the BRST supercurrent and the ghost number supercurrent. From those expressions of anomalies, we construct covariant BRST and ghost number super

J. Laartz

The extension structure of the 2-dimensional current algebra of non-linear sigma models is analysed by introducing Kostant Sternberg $(L,M)$ systems. It is found that the algebra obeys a two step extension by abelian ideals. The second step is a non-split extension of a representation of the quotient of the algebra by the first step of the extension. The coc

S. Dalley

The Weingarten lattice gauge model of Nambu-Goto strings is generalised to allow for fluctuations of an intrinsic worldsheet metric through a dynamical quadrilation. The continuum limit is taken for $c\leq1$ matter, reproducing the results of hermitian matrix models to all orders in the genus expansion. For the compact $c=1$ case the vortices are Wilson line

C. P. Burgess, J. Cline, Markus Luty

Motivated by recent experimental claims for the existence of a 17 keV neutrino and by the solar neutrino problem, we construct a class of models which contain in their low-energy spectrum a single light sterile neutrino and one or more Nambu-Goldstone bosons. In these models the required pattern of breaking of lepton-number symmetry takes place near the elec

L. J. Romans

In flat space, the extreme Reissner-Nordstr\o m (RN) black hole is distinguished by its coldness (vanishing Hawking temperature) and its supersymmetry. We examine RN solutions to Einstein-Maxwell theory with a cosmological constant $\Lambda$, classifying the cold black holes and, for positive $\Lambda$, the ``lukewarm" black holes at the same temperature as

Eric Bedford, Sergey Pinchuk

No abstract available.

Jouko Mickelsson

A polarization of the Lie algebras $Map(C, G)$ of gauge transformations on the light-cone $C\subset\RM^4$ is introduced, using splitting of the initial data on $C$ for the wave operator to positive and negative frequencies. This generalizes the usual polarization of affine Kac-Moody algebras to positive and negative frequencies and paves the way to a general