arXiv papers from July 1992

Andreas Gocksch, Yue Shen

We have determined the phase diagram of the simplest version of a lattice model introduced in the recent work of Kazakov and Migdal. If $m_0$ and $\lambda$ are the bare mass and self coupling of the scalar field in the model respectively, we find a line of first order phase transitions in the ($m_0, \lambda$) plane ending in a critical point where $\lambda$

G. Bathas, H. Neuberger

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

C. Grosse-Knetter, D. Schildknecht

We study the vector-boson production processes e+e- --> WWZ and e+e- -->WWgamma which are directly affected by the trilinear and quadrilinear self couplings of the W, Z and gamma. Our analysis is based upon a single-parameter effective-Lagrangian model for these self interactions which contains the standard model as a special case. Consequences for the pheno

R. C. Myers, V. Periwal

It is shown that conformal matter with $c_{\ssc L}\not=c_{\ssc R}$ can be consistently coupled to two-dimensional `frame' gravity. The theory is quantized, following David, and Distler and Kawai, using the derivation of their {\it ansatz} due to Mavromatos and Miramontes, and D'Hoker and Kurzepa. New super-selection rules are found by requiring SL(2,{\bf C})

M. P. Bellon, J-M. Maillard, G. Rollet, C-M. Viallet

We describe deformations of non-linear (birational) representations of discrete groups generated by involutions, having their origin in the theory of the symmetric five-state Potts model. One of the deformation parameters can be seen as the number $q$ of states of a chiral Potts models. This analogy becomes exact when $q$ is a Fermat number. We analyze the s

Abhijit K. Kshirsagar

A proposal for the path-integral of pure-spin-connection formulation of gravity is described, based on the two-form formulation of Capovilla et. al. It is shown that the resulting effective-action for the spin-connection, upon functional integration of the two-form field $\Sigma$ and the auxiliary matrix field $\psi$ is {\it non-polynomial}, even for the cas

Howard Georgi

I describe a version of so-called naive dimensional analysis, a rule for estimating the sizes of terms in an effective theory below the scale of chiral symmetry breaking induced by a strong gauge interaction. The rule is simpler and more general than the original, which it includes as a special case. I also give a simple qualitative interpretation of the rul

R. V. Gavai, U. M. Heller, F. Karsch, T. Neuhaus

Results of an investigation of the $O(4)$ spin model at finite temperature using anisotropic lattices are presented. In both the large $N$ approximation and numerical simulations using the Wolff cluster algorithm we find that the ratio of the symmetry restoration temperature $T_{\rm SR}$ to the Higgs mass $m_{\rm H}$ is independent of the anisotropy $\xi$. F

Sai Iyer, A R Prasanna

We have obtained the correct expression for the centrifugal force acting on a particle at the equatorial circumference of a rotating body in the locally non-rotating frame of the Kerr geometry. Using this expression for the equilibrium of an element on the surface of a slowly rotating Maclaurin spheroid, we obtain the expression for the ellipticity (as discu

R. Ibanez-Meier, I. Stancu, P. M. Stevenson

In order to investigate the Higgs mechanism nonperturbatively, we compute the Gaussian effective potential (GEP) of the U(1) Higgs model ("scalar electrodynamics"). We show that the same simple result is obtained in three different formalisms. A general covariant gauge is used, with Landau gauge proving to be optimal. The renormalization generalizes the "aut

A. Bellini, M. Ademollo, M. Ciafaloni

Corrections to the semiclassical approximation in nearly forward Planckian energy collisions are here reconsidered. Starting from the one-loop superstring amplitude, we are able to disentangle the first subleading high-energy contribution at large impact parameters, and we thus directly compute the one-loop correction to the superstring eikonal. We finally a

P. H. Damgaard, H. B. Nielsen, R. Sollacher

The (1+1)-dimensional bosonization relations for fermionic mass terms are derived by choosing a specific gauge in an enlarged gauge-invariant theory containing both fermionic and bosonic fields. The fermionic part of the generating functional subject to the gauge constraint can be cast into the form of a strongly coupled Schwinger model, which can be solved

A. Bellini

We suggest a method to compute leading contribution at Planckian energies for superstring scattering amplitudes of any genus. In particular we test the method at one-loop level by comparison with previous result for the Regge trajectory renormalization. Modular invariance of these asymptotic terms are also discussed.

Jens Erler, Albrecht Klemm

There has been some confusion concerning the number of $(1,1)$-forms in orbifold compactifications of the heterotic string in numerous publications. In this note we point out the relevance of the underlying torus lattice on this number. We answer the question when different lattices mimic the same physics and when this is not the case. As a byproduct we clas

Jan Govaerts

Causal rigid particles whose action includes an {\it arbitrary} dependence on the world-line extrinsic curvature are considered. General classes of solutions are constructed, including {\it causal tachyonic} ones. The Hamiltonian formulation is developed in detail except for one degenerate situation for which only partial results are given and requiring a se

M. Campostrini, P. Rossi, E. Vicari

In the lattice CP(N) models we studied the problems related to the measure of the topological susceptibility and the string tension . We perfomed numerical simulations at N=4 and N=10. In order to test the universality, we adopted two different lattice formulations. Scaling and universality tests led to the conclusion that at N=10 the geometrical approach gi

Avner Landver

Let m be the least cardinal k such that MA(k) fails. The only known model for "m is singular" was constructed by Kunen. In Kunen's model cof(m)=omega_1. It is unknown whether "omega_1 < cof(m) < m" is consistent. The purpose of this paper is to present a proof of Kunen's result and to identify the difficulties of generalizing this result to an arbitrary unco

N. David Mermin

Text of a talk given at the International Colloquium on Group Theoretic Methods in Physics, Salamanca, July, 1992. Another futile attempt to persuade the world that space groups can be fun.

M. S. Berger

We show that the equivalence theorem approximating one-loop gauge sector diagrams by including only Goldstone bosons in the loop gives a remarkably poor approximation to the amplitude for the decay $H\rightarrow \gamma \gamma $ and for the process $\gamma \gamma \rightarrow HH$. At one loop, large logarithms can arise that evade power counting arguments.

Ana Achucarro

We show how to obtain the two-dimensional black hole action by dimensional reduction of the three-dimensional Einstein action with a non-zero cosmological constant. Starting from the Chern-Simons formulation of 2+1 gravity, we obtain the 1+1 dimensional gauge formulation given by Verlinde. Remarkably, the proposed reduction shares the relevant features of th

James M. Olness

The lowest moment of the twist-two, chiral-odd parton distribution $h_1(x)$ of the nucleon can be related to the so-called ``tensor charges'' of the nucleon. We consider the tensor charges in the Skyrme model, and find that in the large-$N_c$, SU(3)-symmetric limit, the model predicts that the octet isosinglet tensor charge, $g^8_T$, is of order $1/N_c$ with

C. D. Carone, E. H. Simmons

We study a model in which the electroweak symmetry is dynamically broken by technicolor interactions and the symmetry-breaking is communicated to the quarks and leptons by a weak doublet of scalar fields. The scalars may be regarded as elementary or as light bound states arising from strong extended technicolor interactions. This model is unusual in that it

Jean Avan

Chiral densities obeying a $w_{\infty}$ Poisson--bracket algebra are constructed for the $2+1\,\, A_{\infty}$ -- Toda field theory, using its alternative $w_{\infty}$ -- Toda representation. They are obtained from formal traces of powers of the Lax operator. The spin 2 and 3 currents are explicitely derived, and the consistency of their Poisson algebra is ch

E. C. Marino

Quantum Electrodynamics can be formulated as the theory of an antisymmetric tensor gauge field. In this formulation the topological current of this field appears as an additional source for the electromagnetic field. The topological charge therefore acts physically as an electric charge. The topologically nontrivial, electrically charged sector contains mass

B. Holdom

We study the electromagnetic pion form factor and the VV - AA two point function for momenta -(600 MeV)^2 < q^2 < (600 MeV)^2 and we note the similarity between vector meson dominance and two versions of the free constituent quark model. The similarity is more striking when the momentum dependence of the quark mass is taken into account. We consider the impl

S. W. Hawking, J. M. Stewart

If an evaporating black hole does not settle down to a non radiating remnant, a description by a semi classical Lorentz metric must contain either a naked singularity or what we call a thunderbolt, a singularity that spreads out to infinity on a spacelike or null path. We investigate this question in the context of various two dimensional models that have be

S. Govindarajan, T. Jayaraman, V. John

We show how the double cohomology of the String and Felder BRST charges naturally leads to the ring structure of $c<1$ strings. The chiral ring is a ring of polynomials in two variables modulo an equivalence relation of the form $x^p \simeq y^{p+1}$ for the (p+1,p) model. We also study the states corresponding to the edges of the conformal grid whose inclusi

Jiang Liu

The standard electroweak final-state interaction induces a false T-odd correlation in the top-quark semileptonic decay. The correlation parameter is calculated in the standard model and found to be considerably larger than those that could be produced by genuine T-violation effects in a large class of theoretical models.

Martin Schlichenmaier

Degenerations of Lie algebras of meromorphic vector fields on elliptic curves (i.e. complex tori) which are holomorphic outside a certain set of points (markings) are studied. By an algebraic geometric degeneration process certain subalgebras of Lie algebras of meromorphic vector fields on P^1 the Riemann sphere are obtained. In case of some natural choices

Ulrich Fuchs

Shelah introduced the revised countable support (RCS) iteration to iterate semiproperness. This was an endpoint in the search for an iteration of a weak condition, still implying that aleph1 is preserved. Dieter Donder found a better manageable approach to this iteration, which is presented here.

J Romao, F de Campos, J W F Valle

Higgs production from $Z$ decay in supersymmetry with spontaneous broken R parity proceeds mostly by the Bjorken process as in the standard model. However, the corresponding production rates can be weaker than in the standard model (SM), especially in the low mass region. This will substantially weaken the Higgs boson mass limits derived from LEP1. More stri

Matthias Neubert

I report on recent developments in the heavy-quark effective theory and its application to $B$ meson decays. The parameters of the effective theory, the spin-flavor symmetry limit, and the leading symmetry-breaking corrections to it are discussed. The results of a QCD sum rule analysis of the universal Isgur-Wise functions that appear at leading and subleadi

Luis Alvarez-Gaume, K. Becker, M. Becker, R. Emparan

This paper supersedes the preprint Superloop Equations in the Double Scaling Limit, CERN-TH-6575. It is an improved version with corrections in the derivation of the continuum limit, a clarification of the doubling of degrees of freedom for even potentials, and with a heuristic argument showing that the part of the free energy independent of fermion coupling

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

The neutral kaon system is a sensitive probe of quantum mechanics. We revive a parametrization of non-quantum-mechanical effects that is motivated by considerations of the nature of space-time foam, and show how it can be constrained by new measurements of $K_L \rightarrow 2\pi$ and $K_{L,S}$ semileptonic decays at LEAR or a $\phi$ factory.

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

We argue that the light particles in string theory obey an effective quantum mechanics modified by the inclusion of a quantum-gravitational friction term, induced by unavoidable couplings to unobserved massive string states in the space-time foam. This term is related to the $W$-symmetries that couple light particles to massive solitonic string states in bla

Stuart Staniford-Chen

For a system near a second order phase transition, the probability distribution for the order parameter can be given a finite size scaling form. This fact is used to compare the finite temperature phase transition for the Wilson lines in d=3+1 SU(2) lattice gauge theory with the phase transition in d=3 phi^4 field theory. I exhibit the finite size scaled pro

L. Frappat, E. Ragoucy, P. Sorba

We present a classification of $W$ algebras and superalgebras arising in Abelian as well as non Abelian Toda theories. Each model, obtained from a constrained WZW action, is related with an $Sl(2)$ subalgebra (resp. $OSp(1|2)$ superalgebra) of a simple Lie algebra (resp. superalgebra) $\cg$. However, the determination of an $U(1)_Y$ factor, commuting with $S

L. Bonora, V. Bonservizi

We quantize $sl_n$ Toda field theories in a periodic lattice. We find the quantum exchange algebra in the diagonal monodromy (Bloch wave) basis in the case of the defining representation. In the $sl_3$ case we extend the analysis also to the second fundamental representation. We clarify, in particular, the relation of Jimbo and Rosso's quantum $R$ matrix wit

Fabrizio Illuminati, Marco Patriarca

In the framework of the Caldeira-Leggett model of dissipative quantum mechanics, we investigate the effects of the interaction of the thermal reservoir with an external field. In particular, we discuss how the interaction modifies the conservative dynamics of the central particle, and the mechanism of dissipation. We briefly comment on possible observable co

Fabrizio Illuminati

For the many-anyon system in external magnetic field, we derive the energy spectrum as an exact solution of the quantum eigenvalue problem with particular topological constraints. Our results agree with the numerical spectra recently obtained for the 3- and the 4-anyon systems.

Fabrizio Illuminati

We discuss the problem of N anyons in harmonic well, and derive the semi-classical spectrum as an exactly solvable limit of the many-anyon Hamiltonian. The relevance of our result to the solution of the anyon-gas model is discussed.

J. Alfaro

This paper discusses the large N limit of the two-Hermitian-matrix model in zero dimensions, using the hidden BRST method. A system of integral equations previously found is solved, showing that it contained the exact solution of the model in leading order of large $N$.

S. P. de Alwis

We show that a whole class of quantum actions for dilaton-gravity, which reduce to the CGHS theory in the classical limit, can be written as a Liouville-like theory. In a sub-class of this, the field space singularity observed by several authors is absent, regardless of the number of matter fields, and in addition it is such that the dilaton-gravity function

Howard E. Haber, Alex Pomarol

We discuss the implications of global symmetries on the radiative corrections to the Higgs sector. We focus on two examples: the charged Higgs mass in the minimal supersymmetric model and the Higgs couplings to vector boson pairs. In the first case, we find that in the absence of squark mixing a global SU(2)$\times$SU(2) symmetry protects the charged Higgs m

Edward Witten

Certain two dimensional topological field theories can be interpreted as string theory backgrounds in which the usual decoupling of ghosts and matter does not hold. Like ordinary string models, these can sometimes be given space-time interpretations. For instance, three-dimensional Chern-Simons gauge theory can arise as a string theory. The world-sheet model

Theodore J. Allen

In this Letter the method of Lund is applied to formulate a variational principle for the motion of charged vortices in an effective non-linear Schr\"{o}dinger field theory describing finite size two-dimensional quantum Hall samples under the influence of an arbitrary perpendicular magnetic field. Freezing out variations in the modulus of the effective field

İbrahim Semiz

Using the tetrad formalism, we carry out the separation of variables for the massive complex Dirac equation in the gravitational and electromagnetic field of a four-parameter (mass, angular momentum, electric and magnetic charges) black hole.

J. M. Figueroa-O'Farrill, J. Mas, E. Ramos

The KP hierarchy is hamiltonian relative to a one-parameter family of Poisson structures obtained from a generalized Adler map in the space of formal pseudodifferential symbols with noninteger powers. The resulting $\W$-algebra is a one-parameter deformation of $\W_{\rm KP}$ admitting a central extension for generic values of the parameter, reducing naturall

Bernard de Wit, Antoine Van Proeyen

We show that the isometries of the manifold of scalars in $N=2$ supergravity in $d=5$ space-time dimensions can be broken by the supergravity interactions. The opposite conclusion holds for the dimensionally reduced $d=4$ theories, where the isometries of the scalar manifold are always symmetries of the full theory. These spaces, which form a subclass of the

C. S. Lam

A method is developed whereby spinor helicity techniques can be used to simplify the calculation of loop amplitudes. This is achieved by using the Feynman-parameter representation where the offending off-shell loop momenta do not appear. Background Feynman gauge also helps to simplify the calculations. This method is applicable to any Feynman diagram with an

Tetsuo Deguchi, Tomotada Ohtsuki

We show that multivariable colored link invariants are derived from the roots of unity representations of $U_q(g)$. We propose a property of the Clebsch-Gordan coefficients of $U_q(g)$, which is important for defining the invariants of colored links. For $U_q(sl_2) we explicitly prove the property, and then construct invariants of colored links and colored r

Dimitri Kusnezov, John Sloan

We investigate the use of global demons, a `canonical dynamics', as an approach to simulating lattice regularized field theories. This deterministically chaotic dynamics is non-local and non-Hamiltonian, and preserves the canonical measure rather than $\delta(H-E)$. We apply this inexact dynamics to the 2D XY model, comparing to various implementations of hy

J. W. Moffat, D. C. Tatarski

We examine gravitational waves in an isolated axi--symmetric reflexion symmetric NGT system. The structure of the vacuum field equations is analyzed and the exact solutions for the field variables in the metric tensor are found in the form of expansions in powers of a radial coordinate. We find that in the NGT axially symmetric case the mass of the system re

John C. Collins

I show that factorization for hard processes in QCD is also valid when the detected particles are polarized, and that the proof of the theorem determines the operator form for the parton densities. Particular attention is given to the case of transversely polarized incoming hadrons.

Amitabha Lahiri

We consider the general procedure for proving no-hair theorems for static, spherically symmetric black holes. We apply this method to the abelian Higgs model and find a proof of the no-hair conjecture that circumvents the objections raised against the original proof due to Adler and Pearson.

P. Gondolo

Unstable relics with lifetime longer than the age of the Universe could be the dark matter today. Electrons, photons and neutrinos are a natural outcome of their decay and could be searched for in cosmic rays and in $\gamma$-ray and neutrino detectors. I compare the sensitivities of these three types of searches to the mass and lifetime of a generic unstable

V. Ogievetsky, F. Gursey, M. Evans

It is shown that self-dual theories generalize to four dimensions both the conformal and analytic aspects of two-dimensional conformal field theories. In the harmonic space language there appear several ways to extend complex analyticity (natural in two dimensions) to quaternionic analyticity (natural in four dimensions). To be analytic, conformal transforma

Daniel S. Fisher, A. Alan Middleton

The critical behavior of pinned charge density waves (CDW's) is studied as the threshold for sliding is approached. Using the Fukuyama-Lee-Rice Hamiltonian with relaxational dynamics, the polarization and linear response are calculated numerically. ... On the irreversible approach to threshold, the response due to avalanches triggered by local instabilities

Andreas Ruffing, Thomas Deck, Martin Schlichenmaier

The propagation differential for bosonic strings on a complex torus with three symmetric punctures is investigated. We study deformation aspects between two point and three point differentials as well as the behaviour of the corresponding Krichever-Novikov algebras. The structure constants are calculated and from this we derive a central extension of the Kri

R. Foot, O. F. Hernandez, F. Pisano, V. Pleitez

The $SU(3)_c\otimes SU(3)_L\otimes U(1)_N$ model of Pisano and Pleitez extends the Standard Model in a particularly nice way, so that for example the anomalies cancel only when the number of generations is divisible by three. The original version of the model has some problems accounting for the lepton masses. We resolve this problem by modifying the details

Pierre van Baal

It will be described how to uniquely fix the gauge using Coulomb gauge fixing, avoiding the problem of Gribov copies. The fundamental modular domain, which represents a one-to-one representation of the set of gauge invariant degrees of freedom, is a bounded convex subset of the trans- verse gauge fields. Boundary identifications are the only remnants of the

M. Fabbrichesi, R. Iengo

We study numerically the gravitational field of a star made of massive and neutral string states for the case in which the dilaton is massive. The solution exhibits very simple scaling properties in the dilaton mass. There is no horizon and the singularity is surrounded by a halo (the physical size of which is inversely proportional to the dilaton mass) wher

C. Escobar, O. L. G. Peres, V. Pleitez, R. Zukanovich Funchal

We consider the possibility that the $\tau$ decay puzzle, if it is confirmed in future experiments, is a consequence of the Kobayashi-Maskawa mixing in the leptonic sector

C. Escobar, O. L. G. Peres, V. Pleitez, R. Zukanovich Funchal

We analize the current data on $\tau$-lepton decays and show that they are consistent with the Standard Model

M. Caselle, A. D'Adda, S. Panzeri

We give the exact solution of the Kazakov-Migdal induced gauge model in the case of a D=1 compactified lattice with a generic number $S$ of sites and for any value of N. Due to the peculiar features of the model, the partition function that we obtain also describes the vortex-free sector of the D=1 compactified bosonic string, and it coincides in the continu

H. Hata, I. Niigata

Under the assumption that the color charge can be written in a BRST exact form, the color confinement mechanism proposed by Kugo and Ojima (KO) explains the confinement of any colored particles including dynamical quarks and gluons. This mechanism, however, is known to break down in the Abelian gauge which treats the maximal Abelian subgroup of the gauge gro

Donald E. Knuth

Early 17th-century mathematical publications of Johann Faulhaber contain some remarkable theorems, such as the fact that the $r$-fold summation of $1^m,2^m,...,n^m$ is a polynomial in $n(n+r)$ when $m$ is a positive odd number. The present paper explores a computation-based approach by which Faulhaber may well have discovered such results, and solves a 360-y

A. Babichenko, S. Elitzur

Deviations from scale invariance resulting from small perturbations of a general two dimensional conformal field theory are studied. They are expressed in terms of beta functions for renormalization of general couplings under local change of scale. The beta functions for homogeneous background are given perturbatively in terms of the data of the original con

P. Aschieri, L. Castellani

We give a pedagogical introduction to the differential calculus on quantum groups by stressing at all stages the connection with the classical case ($q \rightarrow 1$ limit). The Lie derivative and the contraction operator on forms and tensor fields are found. A new, explicit form of the Cartan--Maurer equations is presented. The example of a bicovariant dif

Jun Nishimura

The phase shift of the O(4) symmetric $\phi^4$ theory in the symmetric phase is calculated numerically using the relation between phase shift and energy levels of two-particle states recently derived by L\"{u}scher. The results agree with the prediction of perturbation theory. A practical difficulty of the method for a reliable extraction of the phase shift

John W. Milnor

The following notes provide an introduction to recent work of Branner, Hubbard and Yoccoz on the geometry of polynomial Julia sets. They are an expanded version of lectures given in Stony Brook in Spring 1992. I am indebted to help from the audience. Section 1 describes unpublished work by J.-C. Yoccoz on local connectivity of quadratic Julia sets. It presen

Tomek Bartoszynski, Winfried Just, Marion Scheepers

Given a free ideal J of subsets of a set X, we consider games where player ONE plays an increasing sequence of elements of the sigma completion of J, and TWO tries to cover the union of this sequence by playing one set at a time from J. We describe various conditions under which player TWO has has a winning strategy that uses only information about the most

N. J. Cornish, J. W. Moffat

Damour, Deser and McCarthy have claimed that the nonsymmetric gravitational theory (NGT) is untenable due to curvature coupled ghost modes and bad asymptotic behavior. This claim is false for it is based on a physically inaccurate treatment of wave propagation on a curved background and an incorrect method for extracting asymptotic behavior. We show that the

R. L. Jaffe

I review the spin dependent structure functions which control dominant (twist-2) and sub-dominant (twist-3) phenomena in hard processes. Novel effects associated with chirally odd parton distributions and with transverse polarization are emphasized.

Paul A. Griffin

Staggered fermions are constructed for the transverse lattice regularization scheme. The weak perturbation theory of transverse lattice non-compact QED is developed in light-cone gauge, and we argue that for fixed lattice spacing this theory is ultraviolet finite, order by order in perturbation theory. However, by calculating the anomalous scaling dimension

Paul A. Griffin

The non-perturbative ultraviolet divergence of the sine-Gordon model is used to study the $k^+ = 0$ region of light-cone perturbation theory. The light-cone vacuum is shown to be unstable at the non-perturbative $\beta^2 = 8\pi$ critical point by a light-cone version of Coleman's variational method. Vacuum bubbles, which are $k^+=0$ diagrams in light-cone fi

J. -M. Frère J. M. Moreno M. Tytgat J. Orloff

In an effective Lagrangian approach to physics beyond the Standard Model, it has been argued that imposing $SU(2) \times U(1)$ invariance severely restricts the discovery potential of future colliders. We exhibit a possible way out in an extended gauge group context.

V. Azcoiti, G. Di Carlo, A. F. Grillo

We discuss detailed simulations of the non compact abelian model coupled to light fermions, using a method previously developed that includes the effects of the fermionic interactions in an effective action. The approximations involved are related to an expansion in the flavour number. We address the problem of the (non) triviality of the theory through a st

Holger Frahm, Andreas Schadschneider

We study the critical behaviour of the \SUN{} generalization of the one-dimensional Hubbard model with arbitrary degeneracy $N$. Using the integrability of this model by Bethe Ansatz we are able to compute the spectrum of the low-lying excitations in a large but finite box for arbitrary values of the electron density and of the Coulomb interaction. This info

Kanehisa Takasaki, Takashi Takebe

This paper deals with the dispersionless KP hierarchy from the point of view of quasi-classical limit. Its Lax formalism, W-infinity symmetries and general solutions are shown to be reproduced from their counterparts in the KP hierarchy in the limit of $\hbar \to 0$. Free fermions and bosonized vertex operators play a key role in the description of W-infinit

Takashi Kimura

In this paper, we formulate a generalization of the classical BRST construction which applies to the case of the reduction of a poisson manifold by a submanifold. In the case of symplectic reduction, our procedure generalizes the usual classical BRST construction which only applies to symplectic reduction of a symplectic manifold by a coisotropic submanifold

P. H. Cox, B. Harms, Y. Leblanc

We extend a previous calculation which treated Schwarschild black hole horizons as quantum mechanical objects to the case of a charged, dilaton black hole. We show that for a unique value of the dilaton parameter `a', which is determined by the condition of unitarity of the S matrix, black holes transform at the extremal limit into strings.

D. Senechal

We argue that a simple Yukawa coupling between the $O(3)$ nonlinear $\s$-model and charged Dirac fermions leads, after one-loop quantum corrections, to a Meissner effect, in the disordered phase of the nonlinear $\s$-model.

Leandros Perivolaropoulos

We use arguments based on Derrick's theorem to show that the property of collapse which is the key feature of global texture appears in several field theory models with broken global O(N) symmetry. Such models do not necessarily have nontrivial third homotopy group of the vacuum manifold but may give rise to collapsing global field configurations with proper

Richard Hain

In this paper we study the proalgebraic completion of mapping class relative to their maps to the symplectic group. The main result is that the natural map from the unipotent (a.k.a. Malcev) completion of the Torelli group to the prounipotent radical of the Sp_g completion of the mapping class group is a non trivial central extension with kernel isomorphic t

Leandros Perivolaropoulos

A cosmological model in which the primordial perturbations are provided by global monopoles and in which the dark matter is cold has several interesting features. The model is normalized by choosing its single parameter within the bounds obtained from gravitational wave constraints and by demanding coherent velocity f1ows of about 600km/sec on scales of $50

Ted Jacobson, Joseph D. Romano

It has recently been shown by Goldberg et al that the holonomy group of the chiral spin-connection is preserved under time evolution in vacuum general relativity. Here, the underlying reason for the time-independence of the holonomy group is traced to the self-duality of the curvature 2-form for an Einstein space. This observation reveals that the holonomy g

Ted Jacobson, Joseph D. Romano

General relativity has previously been extended to incorporate degenerate metrics using Ashtekar's hamiltonian formulation of the theory. In this letter, we show that a natural alternative choice for the form of the hamiltonian constraints leads to a theory which agrees with GR for non-degenerate metrics, but differs in the degenerate sector from Ashtekar's

H. Kanno, M. H. Sarmadi

The ring structure of Lian-Zuckerman states for $(q,p)$ minimal models coupled to gravity is shown to be ${\cal R}={\cal R}_0\otimes {\bf C} [w,w^{-1}]$ where ${\cal R}_0$ is the ring of ghost number zero operators generated by two elements and $w$ is an operator of ghost number $-1$. Some examples are discussed in detail. For these models the currents are a

Daniel Cangemi

The two lineal gravities --- based on the de Sitter group or a central extension of the Poincar\'e group in 1+1 dimensions --- are shown to derive classically from a unique topological gauge theory. This one is obtained after a dimensional reduction of a Chern--Simons model, which describes pure gravity in 2+1 dimensions, the gauge symmetry being given by an

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

We present a multicanonical algorithm for the SU(3) pure gauge theory at the deconfinement phase transition. We measure the tunneling times for lattices of size L^3x2 for L=8,10, and 12. In contrast to the canonical algorithm the tunneling time increases only moderately with L. Finally, we determine the interfacial free energy applying the multicanonical alg

Shin'ichi Nojiri, Ichiro Oda

We consider exactly solvable semi-classical theory of two dimensional dilatonic gravity with electromagnetic interactions. As was done in the paper by Russo, Susskind and Thorlacius, the term which changes the kinetic term is added to the action. The theory contains massless fermions as matter fields and there appear the quantum corrections including chiral

H. David Politzer

Three simple examples illustrate properties of path integral amplitudes in fixed background spacetimes with closed timelike curves: non-relativistic potential scattering in the Born approximation is non-unitary, but both an example with hard spheres and the exact solution of a totally discrete model are unitary.

T. Damour, S. Deser, J. McCarthy

Motivated by the apparent dependence of string $\sigma$--models on the sum of spacetime metric and antisymmetric tensor fields, we reconsider gravity theories constructed from a nonsymmetric metric. We first show that all such "geometrical" theories homogeneous in second derivatives violate standard physical requirements: ghost-freedom, absence of algebraic

Urs M. Heller, Herbert Neuberger, Pavlos Vranas

We calculate the triviality bound on the Higgs mass in scalar field theory models whose global symmetry group $SU(2)_L \times SU(2)_{\rm custodial} \approx O(4)$ has been replaced by $O(N)$ and $N$ has been taken to infinity. Limits on observable cutoff effects at four percent in several regularized models with tunable couplings in the bare action yield triv

L. Clavelli, P. H. Cox, Kajia Yuan

The impact of the new tau decay data on the various $\tau$ puzzles and on the possibility of approximate supersymmetry is discussed. The most economical solution of the problems in $\tau$ decay and that favored by recent new data supports the existence of gluinos below one GeV.

Claude Bernard, Michael C. Ogilvie, Thomas A. DeGrand, Carleton DeTar

We report on a study of hadron thermodynamics with two flavors of Wilson quarks on 12^3x6 lattices. We have studied the crossover between the high and low temperature regimes for three values of the hopping parameter, kappa=0.16, 0.17, and 0.18. At each of these values of kappa we have carried out spectrum calculations on 12^3x24 lattices for two values of t

Stephen G. Naculich

We examine solitons in theories with heavy fermions. These ``quantum'' solitons differ dramatically from semi-classical (perturbative) solitons because fermion loop effects are important when the Yukawa coupling is strong. We focus on kinks in a $(1+1)$--dimensional $\phi^4$ theory coupled to fermions; a large-$N$ expansion is employed to treat the Yukawa co

S. Kelley, J. Lopez, D. Nanopoulos, H. Pois

We investigate the prospects for neutralino dark matter within the Supersymmetric Standard Model (SSM) including the constraints from universal soft supersymmetry breaking and radiative breaking of the electroweak symmetry. The latter is enforced by using the one-loop Higgs effective potential which automatically gives the one-loop corrected Higgs boson mass

D. Chang, I. Phillips, Lev Rozansky

Quantum superalgebras $su_{q}(m\mid n)$ are studied in the framework of $R$-matrix formalism. Explicit parametrization of $L^{(+)}$ and $L^{(-)}$ matrices in terms of $su_{q}(m\mid n)$ generators are presented. We also show that quantum deformation of nonsimple superalgebra $su(n\mid n)$ requires its extension to $u(n\mid n)$.