January 1994 arXiv papers — page 6

Max Tegmark, Leehwa Yeh

We study properties of steady states (states with time-independent density operators) of systems of coupled harmonic oscillators. Formulas are derived showing how adiabatic change of the Hamiltonian transforms one steady state into another. It is shown that for infinite systems, sudden change of the Hamiltonian also tends to produce steady states, after a tr

C. M. Bender, S. Boettcher, M. Moshe

A previous paper (hep-lat/9311011) proposed a new kind of random walk on a spherically-symmetric lattice in arbitrary noninteger dimension $D$. Such a lattice avoids the problems associated with a hypercubic lattice in noninteger dimension. This paper examines the nature of spherically-symmetric random walks in detail. We perform a large-time asymptotic anal

Valentin V. Khoze

We argue that gauge transformations with arbitrary fractional winding numbers should be allowed in a non-Abelian gauge theory. This eliminates the topological distinction between large and small gauge transformations. We prove that the states which satisfy the Gauss's law constraint are strictly invariant under gauge transformations, i.e. no phase shift

M. A. Doncheski, R. W. Robinett

Several topics of relevance to low transverse momentum $ψ$ and $χ_{1,2}(c\overline{c})$ production in polarized proton-proton collisions are discussed. The leading ${\cal O}(α_S^3)$ contributions to the low $p_T$ $χ_1$ production cross-sections via $gg$, $qg$, and $q\overline{q}$ initial states are calculated as well as the corresponding spin-spin asymmetrie

P. Menotti, D. Seminara

We apply the reduced radial gauge to give the general solution of the metric in 2+1 dimensions in term of quadratures. It allows a complete controll on the support of the source. We use the result to prove that for a general stationary universe, conical at infinity, the weak energy condition and the absence of CTC at space infinity prevent the occurrrence of

Kikuo Harigaya, Shuji Abe

Optical absorption spectra of C_70 and C_76 are calculated by a tight binding model with a long ranged Coulomb interaction. The spectrum of C_70 is in overall agreement with the experiment of molecules in a solution. The variations of the spectral shape are discussed relating with the symmetry reduction from C_70 to C_76.

Raiko P. Zaikov

Higher spin extensions of nonabelian gauge symmetries for both free fermionic model and WZNW model are considered on a classical level. It is characteristic property of the WZNW model that the higher spin currents which correspond to linear realized higher spin extended affine algebra do not form an invariant space. An extended invariant current space is obt

Tanmay Vachaspati, George B. Field

In the context of electroweak strings, the baryon number anomaly equation may be reinterpreted as a conservation law for baryon number minus helicity. Since the helicity is a sum of the link and twist numbers, linked or twisted loops of electroweak string carry baryon number. We evaluate the change in the baryon number obtained by delinking loops of electrow

M. Cederwall, G. Ferretti, B. E. W. Nilsson, A. Westerberg

We postulate a new type of operator algebra with a non-abelian extension. This algebra generalizes the Kac--Moody algebra in string theory and the Mickelsson--Faddeev algebra in three dimensions to higher-dimensional extended objects ($p$-branes). We then construct new BRST operators, covariant derivatives and curvature tensors in the higher-dimensional gene

Rafael D. Sorkin

The additivity of classical probabilities is only the first in a hierarchy of possible sum-rules, each of which implies its successor. The first and most restrictive sum-rule of the hierarchy yields measure-theory in the Kolmogorov sense, which physically is appropriate for the description of stochastic processes such as Brownian motion. The next weaker sum-

Eric Bergshoeff, Ingeborg Entrop, Renata Kallosh

We formulate sigma-model duality transformations in terms of spin connection. This allows to investigate the symmetry of the string action including higher order $α'$ corrections. An important feature of the new duality transformations is a simple homogeneous transformation rule of the spin connection (with torsion) and specifically adjusted transformati

S. R. Beane, U. van Kolck

It is argued that constituent quarks live in an effective theory that possesses an approximate conformal invariance. An effective lagrangian is constructed which in the large-$\nc$ approximation incorporates Regge asymptotic constraints. The resulting picture explains why linear-sigma models provide successful constituent quark descriptions, both at zero and

R. M. Noack, S. R. White, D. J. Scalapino

Equal time spin--spin and pair field correlation functions are calculated for a two-chain Hubbard model using a density-matrix numerical renormalization group approach. At half-filling, the antiferromagnetic and pair field correlations both decay exponentially with the pair field having a much shorter correlation length. This is consistent with a gapped spin

P. Berglund, M. Henningson

We compute the elliptic genus for arbitrary two dimensional $N=2$ Landau-Ginzburg orbifolds. This is used to search for possible mirror pairs of such models. We show that if two Landau-Ginzburg models are conjugate to each other in a certain sense, then to every orbifold of the first theory corresponds an orbifold of the second theory with the same elliptic

D. Juriev

The present paper is devoted to various objects of the infinite dimensional W-geometry of a second quantized free string. Our purpose is to include the W-symmetries into the general infinite dimensional geometrical picture related to the quantum field theory of strings, which was described in the first part of the paper (Algebras Groups Geom.11(1994)[to appe

E. G. Gurvich, G. G. Leptoukh, E. K. Sarkisyan

A low constituent number scheme based on the nontrivial gluon string splitting (the Zip--model) is shown to yield a substantial intermittency for soft hadronic processes. With a simplest addition of the Bose--Einstein correlations the remarkable agreement with the NA22 experimental data on rapidity factorial moments is reached.

D. Fliegner, M. G. Schmidt, C. Schubert

The higher derivative expansion of the one-loop effective action for an external scalar potential is calculated to order O(T**7), using the string-inspired Bern-Kosower method in the first quantized path integral formulation. Comparisons are made with standard heat kernel calculations and with the corresponding Feynman diagrammatic calculation in order to sh

Ralf Hempfling, Andre H. Hoang

In the minimal supersymmetric model (MSSM), the upper limit of the lightest Higgs boson mass, $\mhl$, depends strongly on the top quark mass, $m_t$. We have computed the dominant two-loop radiative corrections to this upper limit of $\mhl$ in order to eliminate large uncertainties due to QCD and $m_t^6$ corrections. It is shown that the QCD corrections signi

Derek B. Leinweber

The short-time regime of QCD two-point correlation functions is examined through a QCD-Sum-Rule-inspired continuum model. QCD Sum Rule techniques are tested and alternate nucleon interpolating fields are discussed. The techniques presented here may be of practical use in determining heavy-light meson decay constants.

M. D. Maia, G. S. Silva

The cosmological constant problem is examined under the assumption that the extrinsic curvature of the space-time contributes to the vacuum. A compensation mechanism based on a variable cosmological term is proposed. Under a suitable hypothesis on the behavior of the extrinsic curvature, we find that an initially large $Λ(t)$ rolls down rapidly to zero durin

James M. Nester, Roh-Suan Tung, Yuan Zhong Zhang

We discuss earlier unsuccessful attempts to formulate a positive gravitational energy proof in terms of the New Variables of Ashtekar. We also point out the difficulties of a Witten spinor type proof. We then use the special orthonormal frame gauge conditions to obtain a locally positive expression for the New Variables Hamiltonian and thereby a ``localizati

James M. Nester, Roh-Suan Tung

Two locally positive expressions for the gravitational Hamiltonian, one using 4-spinors the other special orthonormal frames, are reviewed. A new quadratic 3-spinor-curvature identity is used to obtain another positive expression for the Hamiltonian and thereby a localization of gravitational energy and positive energy proof. These new results provide a link

C. H. Booth, F. Bridges, J. B. Boyce, T. Claeson

We present K-edge XAFS (X-Ray Absorption Fine Structure) data for various concentrations of Pr in Y$_{1- x}$Pr$_{x}$Ba$_{2}$Cu$_{3}$O$_{7}$. The character of the Pr K-edge XAFS data indicate that most of the Pr substitutes onto the Y site and is well ordered with respect to the unit cell. These data also show that the amplitude of the first Pr-O peak is grea

Ben Moore, Marc Davis

SHORTENED ABSTRACT: We present numerical investigations designed to critically test models of the origin of the Magellanic Stream. The most developed model is the tidal model which fails to reproduce several of its characteristic properties. We suggest an alternative model for the origin of the Stream which can explain all of its observed features and dynami

Chung-Pei Ma, Edmund Bertschinger

We present a systematic treatment of the linear theory of scalar gravitational perturbations in the synchronous gauge and the conformal Newtonian (or longitudinal) gauge. We first derive the transformation law relating the two gauges. We then write down in parallel in both gauges the coupled, linearized Boltzmann, Einstein and fluid equations that govern the

Fred C. Adams, Katherine Freese

In this paper, we present quantitative constraints on the scalar field potential for a general class of inflationary models. (1) We first consider the reconstruction of the inflationary potential for given primordial density fluctuation spectra. Our work differs from previous work on reconstruction in that we find a semi-analytic solution for the potential f

D. V. Khveshchenko

We discuss a generalization of the conventional bosonization procedure to the case of current-current interactions which get their natural representation in terms of current instead of fermion number density operators. A consistent bosonization procedure requires a geometrical quantization of the hamiltonian action of $W_\infty$ on its coadjoint orbits. An i

Alexander Gorsky, Nikita Nekrasov

We study quantum intergrable systems of interacting particles from the point of view, proposed in our previous paper. We obtain Calogero-Moser and Sutherland systems as well their Ruijsenaars relativistic generalization by a Hamiltonian reduction of integrable systems on the cotangent bundles over semi-simple Lie algebras, their affine algebras and central e

C. Gruber, D. F. Wang

In this work, we continue the study of the supersymmetric t-J model with 1/r^2 hopping and exchange without translational invariance. A set of Jastrow wavefunctions are obtained for the system, with eigenenergies explicitly calculated. The ground state of the t-J model is included in this set of wavefunctions. The spectrum of this t-J model consists of equal

P. Wegrzyn

Classical bosonic open string models in fourdimensional Minkowski spacetime are discussed. A special attention is paid to the choice of edge conditions, which can follow consistently from the action principle. We consider lagrangians that can depend on second order derivatives of worldsheet coordinates. A revised interpretation of the variational problem for

Joel Langer, Ron Perline

The integrable hierarchy of commuting vector fields for the localized induction equation of 3D hydrodynamics, and its associated recursion operator, are used to generate families of integrable evolution equations which preserve local geometric invariants of the evolving curve or swept-out surface.

Kevin L. Haglin, Charles Gale

We calculate the $ϕ$-meson propagator at finite temperature at the one--loop order. The real and imaginary parts are studied separately in full kinematic ranges. From this activity we investigate how temperature affects such things as decay widths and dispersion relations. {}From here we estimate the thermal rate of lepton pair radiation in a hadron gas proc

Arnold Miller

These are lecture notes from a course I gave at the University of Wisconsin during the Spring semester of 1993. Part 1 is concerned with Borel hierarchies. Section 13 contains an unpublished theorem of Fremlin concerning Borel hierarchies and MA. Section 14 and 15 contain new results concerning the lengths of Borel hierarchies in the Cohen and random real mo

K. Skenderis, P. van Nieuwenhuizen

We {\em derive} the exact configuration space path integral, together with the way how to evaluate it, from the Hamiltonian approach for any quantum mechanical system in flat spacetime whose Hamiltonian has at most two momentum operators. Starting from a given, covariant or non-covariant, Hamiltonian, we go from the time-discretized path integral to the cont

Alexander A. Voronov

String backgrounds are described as purely geometric objects related to moduli spaces of Riemann surfaces, in the spirit of Segal's definition of a conformal field theory. Relations with conformal field theory, topological field theory and topological gravity are studied. For each field theory, an algebraic counterpart, the (homotopy) algebra satisfied b

Harold Roussel

In this paper we solve two matrix models, using standard and new techniques. The two models are represented by special form of antisymmetric matrices and are classified in the DIII generator ensemble. It is shown that, in the double scaling limit, their free energy has the same behavior as previous models describing oriented and unoriented surfaces. We also

Alexander Gorsky, Nikita Nekrasov

We show that elliptic Calogero-Moser system and its Lax operator found by Krichever can be obtained by Hamiltonian reduction from the integrable Hamiltonian system on the cotangent bundle to the central extension of the algebra of SL(N,C) currents.Elliptic deformation of Yang-Mills theory is presented.

Jaume Garriga

In $N+1$ dimensions, false vacuum decay at zero temperature is dominated by the $O(N+1)$ symmetric instanton, a sphere of radius $R_0$, whereas at temperatures $T>>R_0^{-1}$, the decay is dominated by a `cylindrical' (static) $O(N)$ symmetric instanton. We study the transition between these two regimes in the thin wall approximation. Taking an $O(N)$ sym

R. J. Budzynski, W. Kondracki

We introduce the notion of locally trivial quantum principal bundles. The base space and total space are compact quantum spaces (unital $C^{\star}$-algebras), the structure group is a compact matrix quantum group. We prove that a quantum bundle admits sections if and only if it is trivial. Using a quantum version of Čech cocycles, we obtain a reconstruction

R. J. Budzynski, W. Kondracki

These notes are based on a lecture given by S. L. Woronowicz at the Institute of Mathematics, Polish Academy of Sciences.

Le Tu Quoc Thang, Jun Murakami

We give a generalization of the Reshetikhin-Turaev functor for tangles to get a combinatorial formula for the universal Vassiliev-Kontsevich invariant of framed oriented links which is coincident with the Kontsevich integral. The universal Vassiliev-Kontsevich invariant is constructed using the Drinfeld associator. We prove the uniqueness of the Drinfeld ass

J. N. Tavares

We show that the Classical Constraint Algebra of a Parametrized Relativistic Gauge System induces a natural structure of Conformal Foliation on a Transversal Gauge. Using the theory of Conformal Foliations, we provide a natural Factor Ordering for the Quantum Operators associated to the Canonical Quantization of such Gauge System.

Makoto Natsuume

For $2D$ string theory, the perturbative $S$-matrices are not well-defined due to a zero mode divergence. Although there exist formal procedures to make the integral convergent, their physical meanings are unclear. We describe a method to obtain finite $S$-matrices physically to justify the formal schemes. The scheme uses asymptotic states by wave packets wh

Kei-Ichi Kondo, Takuya Iizuka, Eiji Tanaka, Toru Ebihara

The fermion flavor $N_f$ dependence of non-perturbative solutions in the strong coupling phase of the gauge theory is reexamined based on the interrelation between the inversion method and the Schwinger-Dyson equation approach. Especially we point out that the apparent discrepancy on the value of the critical coupling in QED will be resolved by taking into a

Carl Carlson, Marc Sher

Current experiments allow the possibility of gluino masses below about 600 MeV if the lifetime of the gluino is longer than 100 picoseconds. If the mass and lifetime are in this window, then photoproduction of pairs of gluino-gluon bound states can provide a means to observe them. The cross section is large enough that the window can be fully explored, up to

Th. Meissner, E. Ruiz Arriola, A. Blotz, K. Goeke

We give a comprehensive review of concepts and numerical calculations for SU(2) and SU(3) baryonic systems which are considered as many body systems composed of three quarks coupled to a polarized Dirac sea by a Nambu--Jona-Lasinio like interaction. The general formalism as well as the construction and numerical solution of non-topological mean field soliton

Boris Z. Kopeliovich, Enrico Predazzi

Diquark-antidiquark states are expected to exist as a natural complement of mesons and baryons. Although they were predicted long ago, and some candidates were found experimentally, none has, as yet, been reliably identified. We suggest that the search for the so-called $C(1480)$-meson in reactions such as photoproduction $γN\rightarrowϕπN$ and $K N \rightar

J. A. Gracey

We use the large N_f self consistency formalism to compute the $O(1/N_f)$ critical exponent corresponding to the renormalization of the flavour non-singlet twist two Wilson operators which arise in the operator product expansion of currents in deep inelastic processes. Expanding the $d$-dimensional expression in powers of $ε$ $=$ $(4-d)/2$ the coefficients o

R. Roncaglia, A. R. Dzierba, D. B. Lichtenberg, E. Predazzi

The Feynman--Hellmann theorem is used to show that vector meson energy eigenvalues are monotonically decreasing functions of the reduced masses of their constituent quarks. The experimental meson masses are used to put constraints on the values of quark masses and to predict the masses of some as yet undiscovered mesons. The mass of the $B_c^*$ meson is pred

G. Cynolter, E. Lendvai, G. Pócsik

In the standard model of electroweak interactions the Higgs doublet is replaced by a doublet of vector bosons and the gauge symmetry is broken dynamically. This generates masses for the gauge bosons and fermions, as well as it fixes the interactions in the model. The model has a low momentum scale. In this note we show that the model survives the test of the

U. Aglietti, G. Martinelli, C. T. Sachrajda

We propose a method for evaluating the slope (and higher derivatives) of the Isgur-Wise function at the zero recoil point using lattice simulations. These derivatives are required for the extrapolation of the experimental data for $B\rightarrow D^*l\barν$ decays to the zero recoil point, from which the $V_{cb}$ element of the CKM-matrix can be determined.

A. Ali Khan, M. Goeckeler, R. Horsley, P. E. L. Rakow

We investigate the neighbourhood of the chiral phase transition in a lattice Nambu--Jona-Lasinio model, using both Monte Carlo methods and lattice Schwinger-Dyson equations.

D. V. Khveshchenko

Applying the bosonization procedure to constrained fermions in the framework of the one dimensional t-J model we discuss a scenario of singlet superconductivity in a lightly doped double chain where all spin excitations remain gapful.

D. V. Khveshchenko, T. M. Rice

Applying the bosonization procedure to weakly coupled Hubbard chains we discuss the fixed points of the renormalization group flow where all spin excitations are gapful and a singlet pairing becomes the dominant instability.

J. F. Weisz, R. Kishore, Feodor V. Kusmartsev

Persistant current in isolated mesoscopic rings is studied using the continium and tight-binding models of independent electrons. The calculation is performed with disorder and also at finite temperature. In the absence of disorder and at zero temperature agreement is obtained with earlier results by D. Loss et. al., in that there is half quantum flux period

N B Volkov, A M Iskoldsky

The present paper is a concluding part of the series [N.B. Volkov and A.M. Iskoldsky: 1; 2; [1], [2]]. Here on the basis of the results of the above papers the experiments on the electric explosion in conductors have been discussed and the mechanism of "hot" plasma spots formation which was repeatedly observed in the experiments on a plasma focus, z-

Arshad Momen, Joseph Schechter, Anand Subbaraman

We discuss the generalization of the Callan-Klebanov model to the case of heavy quark baryons. The light flavor group is considered to be $SU(3)$ and the limit of heavy spin symmetry is taken. The presence of the Wess-Zumino-Witten term permits the neat development of a picture , at the collective level, of a light diquark bound to a ``heavy" quark with

Aric Hagberg, Ehud Meron

A new mechanism for spiral vortex nucleation in nongradient reaction diffusion systems is proposed. It involves two key ingredients: An Ising-Bloch type front bifurcation and an instability of a planar front to transverse perturbations. Vortex nucleation by this mechanism plays an important role in inducing a transition from labyrinthine patterns to spiral t

K. Egiyan, L. Frankfurt, W. R. Greenberg, G. A. Miller

We propose that measuring the $Q^2$ dependence of the number of final-state interactions of the recoil protons in quasi-elastic electron scattering from light nuclei is a new method to investigate Color Coherent effects at {\bf intermediate} values of $Q^2$ ({$\sim$ few $(GeV/c)^2$}). This is instead of measuring events without final-state interactions. Our

Richard M. Aron, Sean Dineen

Let $E$ be a Banach space and, for any positive integer $n$, let ${\cal P}(^nE)$ denote the Banach space of continuous $n$-homogeneous polynomials on $E$. Davie and Gamelin showed that the natural extension mapping from ${\cal P}(^nE)$ to ${\cal P}(^nE^{\ast\ast})$ is an isometry into the latter space. Here, we investigate when there is a natural isomorphism

Walter D. Neumann, Michael Shapiro

We show that the set $SA(G)$ of equivalence classes of synchronously automatic structures on a geometrically finite hyperbolic group $G$ is dense in the product of the sets $SA(P)$ over all maximal parabolic subgroups $P$. The set $BSA(G)$ of equivalence classes of biautomatic structures on $G$ is isomorphic to the product of the sets $BSA(P)$ over the cusps

D. Dalmazi

We study the problem of covariant separation between first and second class constraints for the $D=10$ Brink-Schwarz superparticle. Opposite to the supersymmetric light-cone frame separation, we show here that there is a Lorentz covariant way to identify the second class constraints such that, however, supersymmetry is broken. Consequences for the $D=10$ sup

S. Kharchev, A. Marshakov

We consider the canonical quantization scheme for $c \leq 1$ ($(p,q)$ -) string theories and compare it with what is known from matrix model approach. We derive explicitly a trivial ($\equiv $ topological) solution. We discuss a ``dressing" operator which in principle allows one to obtain a non-trivial solution, but an explicit computation runs into a pr

S. De Leo, P. Rotelli

While in general there is no one-to-one correspondence between complex and quaternion quantum mechanics (QQM), there exists at least one version of QQM in which a {\em partial} set of {\em translations} may be made. We define these translations and use the rules to obtain rapid quaternion counterparts (some of which are new) of standard quantum mechanical re

Subir Ghoshal

We conjecture that the $O(N)$-symmetric non-linear sigma model in the semi-infinite $(1+1)$-dimensional space is ``integrable'' with respect to the ``free'' and the ``fixed'' boundary conditions. We then derive, for both cases, the boundary S-matrix for the reflection of massive particles of this model off the boundary at $x=0$.

Jean-Paul Blaizot, Edmond Iancu

We construct the energy-momentum tensor for the gauge fields which describe the collective excitations of the quark-gluon plasma. We rely on the description of the collective modes that we have derived in previous works. By using the conservation laws for energy and momentum, we obtain three different versions for the tensor $T^{μν}$, which are physically eq

Jean-Paul Blaizot, Edmond Iancu

We present new, non-abelian, solutions to the equations of motion which describe the collective excitations of a quark-gluon plasma at high temperature. These solutions correspond to spatially uniform color oscillations.

James M. Cline, Kimmo Kainulainen, Keith A. Olive

If the baryon asymmetry of the universe was created at the GUT scale, sphalerons together with exotic sources of $(B-L)$-violation could have erased it, unless the latter satisfy stringent bounds. We elaborate on how the small Yukawa coupling of the electron drastically weakens previous estimates of these bounds.

N. B. Volkov, A. M. Iskoldsky

In the present paper which is a sequel to [N.B. Volkov and A.M. Iskoldsky The dynamics of vortex structures and states of current: 1;[1]], the dynamics of non-equilibrium phase transitions and states of current in electrophysical systems providing an external circuit and a nonlinear element the model of which has been developed in [1] (in the development of

Robert J. Nemiroff, W. A. D. Thulsi Wickramasinghe

If the dark halo matter is primarily composed of MACHOs toward the lower end of the possible detection range ($ < 10^{-3}$ $M_{\odot}$) a fraction of the lens detection events should involve the lens crossing directly in front of the disk of the background star. Previously, Nemiroff (1987) has shown that each crossing would create an inflection point in the

A. Anderson, B. E. W. Nilsson, C. N. Pope, K. S. Stelle

Liouville and Toda gravity theories with non-vanishing interaction potentials have spectra obtained by dividing the free-field spectra for these cases by the Weyl group of the corresponding $A_1$ or $A_2$ Lie algebra. We study the canonical transformations between interacting and free fields using the technique of intertwining operators, giving explicit cons

T. Curtright, C. Zachos

We discuss the pseudodual chiral model to illustrate a class of two-dimensional theories which have an infinite number of conservation laws but allow particle production, at variance with naive expectations. We describe the symmetries of the pseudodual model, both local and nonlocal, as transmutations of the symmetries of the usual chiral model. We refine th

R. A. Kraenkel, J. G. Pereira, M. A. Manna

We consider a system formed by an infinite viscous liquid layer with a constant horizontal temperature gradient, and a basic nonlinear bulk velocity profile. In the limit of long-wavelength and large nondimensional surface tension, we show that hydrothermal surface-wave instabilities may give rise to disturbances governed by the Kuramoto-Sivashinsky equation

S. Gardner, J. Piekarewicz

We calculate the asymmetry in the missing-momentum distribution from the $(e,e&#39;p)$ reaction in a relativistic formalism. Longitudinal and transverse response functions are evaluated in parallel kinematics as a function of the three-momentum transfer to the nucleus. Analytic expressions for the responses are obtained in a relativistic plane-wave impulse a

Stefan Geiss, Marius Junge

Let $\on_{k \in \nz}$ be an orthonormal system on some $σ$-finite measure space $(\Om,p)$. We study the notion of cotype with respect to $Φ$ for an operator $T$ between two Banach spaces $X$ and $Y$, defined by $\fco T := \inf$ $c$ such that \[ \Tfmm \pl \le \pl c \pll \gmm \hspace{.7cm}\mbox{for all}\hspace{.7cm} (x_k)\subset X \pl,\] where $(g_k)_{k\in \nz

R. Brooks, C. Lucchesi

The actions for all classical (and consequently quantum) $BF$ theories on $n$-manifolds is proven to be given by anti-commutators of hermitian, nilpotent, scalar fermionic charges with Grassmann-odd functionals. In order to show this, the space of fields in the theory must be enlarged to include ``mass terms&#39;&#39; for new, non-dynamical, Grassmann-odd fi

Wolfram Boenkost

We prove the uncloseability of the free vertex operators used in conformal field theory for the BRST--construction of primary fields. Our proof includes minimal models as well as WZNW--models.

C. L. Schat, N. N. Scoccola

We investigate a model for hyperons based on the bound state approach in which vector mesons are explicitly incorporated. We show that for empirical values of the mesonic parameters the strange hyperon spectrum is well reproduced. We also discuss the extension of the model to heavier flavors. We show that the explicit presence of the heavy vectors leads to g

S. Bellucci, J. Gasser, M. E. Sainio

We evaluate the amplitude for $γγ\rightarrow π^0 π^0$ to two loops in chiral perturbation theory. The three new counterterms which enter at this order in the low-energy expansion are estimated with resonance saturation. We find that the cross section agrees rather well with the available data and with dispersion theoretic calculations even substantially abov

Tom Fleming, Mark Gross, Ray Renken

We define a simplified version of Regge quantum gravity where the link lengths can take on only two possible values, both always compatible with the triangle inequalities. This is therefore equivalent to a model of Ising spins living on the links of a regular lattice with somewhat complicated, yet local interactions. The measure corresponds to the natural su

J. W. Moffat

A gauge theory of quantum gravity is formulated, in which an internal, field dependent metric is introduced which non-linearly realizes the gauge fields on the non-compact group $SL(2,C)$, while linearly realizing them on $SU(2)$. Einstein&#39;s $SL(2,C)$ invariant theory of gravity emerges at low energies, since the extra degrees of freedom associated with

Jose Riera, Ariel Dobry

We study numerically, using a one-dimensional Heisenberg model, the spin-Peierls transition in the linear Cu$^{2+}$ spin-1/2 chains in the inorganic compound CuGeO$_3$ which has been recently observed experimentally. We suggest that the magnetic susceptibility, the temperature dependence of the spin gap and the spin-Peierls transition temperature of this mat

Hans C. Fogedby

We consider Lévy flights characterized by the step index $f$ in a quenched random force field. By means of a dynamic renormalization group analysis we find that the dynamic exponent $z$ for $f<2$ locks onto $f$, independent of dimension and {\em independent} of the presence of weak quenched disorder. The critical dimension, however, depends on the step index

Ramesh Narayan, Abraham Loeb, Pawan Kumar

It is well known that the standard transport equations violate causality when gradients are large or when temporal variations are rapid. We derive a modified set of transport equations that satisfy causality. These equations are obtained from the underlying Boltzmann equation. We use a simple model for particle collisions which enables us to derive moment eq

Marc Kamionkowski, David N. Spergel, Naoshi Sugiyama

We perform detailed calculations of cosmic microwave background (CMB) anisotropies in a CDM-dominated open universe with primordial adiabatic density perturbations for a variety of reionization histories. We show that to a great extent, the CMB anisotropies depend only on the geometry of the Universe, which in a matter dominated universe is determined by $Ω$

Dean Miller, Kimball A. Milton, Stephan Siegemund-Broka

We apply the finite-element lattice equations of motion for quantum electrodynamics given in the first paper in this series to examine anomalies in the current operators. By taking explicit lattice divergences of the vector and axial-vector currents we compute the vector and axial-vector anomalies in two and four dimensions. We examine anomalous commutators

R. Altmeyer, M. Goeckeler, R. Horsley, E. Laermann

We report on calculations of the hadronic coupling constants $g_{ρππ}$ and $g_{nnπ}$ based on lattice QCD with four flavors of dynamical staggered fermions. By computing 2--point and 3--point Green&#39;s functions we have been able to determine these coupling constants ab initio from QCD; the results are compatible with the experimental values.

J. Bonca, A. V. Balatsky

The new form of the composite operator generalizing the Cooper pairs for a BCS superconductor is introduced. The approach is similar to the derivation of the composite operator of the odd - frequency superconductors. The examples of the $d_{x^2-y^2}-,~d_{xy}-$ and $p-$ wave composite operators for a 2D $t-J$ model are given.

G. Bonneau, G. Valent

In the same spirit as done for N=2 and N=4 supersymmetric non-linear $\si$ models in 2 space-time dimensions by Zumino and Alvarez- Gaumé and Freedman, we analyse the (2,0) and (4,0) heterotic geometry in holomorphic coordinates. We study the properties of the torsion tensor and give the conditions under which (2,0) geometry is conformally equivalent to a (2

R. Jackiw, Q. Liu, C. Lucchesi

First, we investigate the static non-Abelian Kubo equation. We prove that it does not possess finite energy solutions; thereby we establish that gauge theories do not support hard thermal solitons. A similar argument shows that "static" instantons are absent. In addition, we note that the static equations reproduce the expected screening of the non-Abelian e

F. D. M. Haldane

Various aspects of the Haldane-Shastry spin chain with 1/r^2 exchange, and its various generalizations, are reviewed, with emphasis on its Yangian quantum group structure, and the interpretation of the model as the generalization of an ideal gas (of ``spinons&#39;&#39;) to the case of fractional statistics. Some recent results on its dynamical correlation fu

A. Dobado, J. R. Pelaez

We develop an alternative formulation of the symmetry breaking sector of the Standard Model as a gauged non-linear sigma model (NLSM) following the philosophy of the Chiral lagrangian approach, which is the only compatible with all the experimental and theoretical constraints. We derive the BRS symmetry of the model and the corresponding quantum lagrangian,

Jorge Ananias Neto

We point out the question of ordering momentum operator in the canonical \break quantization of the SU(2) Skyrme Model. Thus, we suggest a new definition for the momentum operator that may solve the infrared problem that appears when we try to minimize the Quantum Hamiltonian.

Ming Lu, Mark B. Wise

We estimate the long distance contribution to the $K^+ \rightarrow π^+ ν\barν$ decay amplitude using chiral perturbation theory. We find that it is likely to be less than a few percent of the part of the short distance contribution proportional to the square of the charm quark mass. In the large $N_c$ limit the leading (in chiral perturbation theory) long di

V. D. Mur, V. S. Popov, Yu. A. Simonov, V. P. Yurov

Starting from the QCD Lagrangian and taking into account both perturbative and nonperturbative effects, we use the method of vacuum correlators to derive the Dirac equation (rigorously for the Coulomb interaction and heuristically for the confining potential) for a system consisting of a light quark and heavy antiquark. As a result the confining potential is

Carsten Grosse-Knetter

A locally SU(2)xU(1)-invariant term of dimension six with effective interactions of the electroweak gauge and Higgs fields is examined. This term also contains higher derivatives of the fields. It yields nonstandard quartic gauge-boson self-interactions but neither nonstandard cubic self-interactions nor tree-level effects on presently measurable quantities.

J. J. Rehr, C. H. Booth, F. Bridges, S. I. Zabinsky

Oscillatory structure is found in the atomic background absorption in x-ray-absorption fine structure (XAFS). This atomic-XAFS or AXAFS arises from scattering within an embedded atom, and is analogous to the Ramsauer-Townsend effect. Calculations and measurements confirm the existence of AXAFS and show that it can dominate contributions such as multi-electro

L. S. Levitov, G. B. Lesovik

We study fluctuations of electric current in a quantum resistor and derive a general quantum-mechanical formula for the distribution of transmitted charge. For that we introduce a scheme of current measurement that involves a spin $1/2$ coupled to the current so that it precesses at the rate proportional to the current. Our approach allows the study of charg

N. Lemke, J. J. Arenzon, F. A. Tamarit

The dynamics of an extremely diluted neural network with high order synapses acting as corrections to the Hopfield model is investigated. As in the fully connected case, the high order terms may strongly improve the storage capacity of the system. The dynamics displays a very rich behavior, and in particular a new chaotic phase emerges depending on the weigh

M. Kasner

In the hierarchical theory of the fractional quantum Hall effect, the low--energy behaviour of a daughter state in the next level of the hierarchy is described by an interacting system of quasiparticles of the parent state. Taking the filled lowest Landau level as the parent state, we examine analytically the quantitative consequences of this approach for el