September 1994 arXiv papers — page 3

Luchezar L. Avramov, Ragnar-Olaf Buchweitz, Judith D. Sally

Let $R=\bigoplus_{n\ges0}R_n$ be a graded commutative ring generated over a field $K=R_0$ by homogeneous elements $x_1,\dots,x_e$ of positive degrees $d_1,\dots,d_e$. The Hilbert-Serre Theorem shows that for each finite graded $R$--module $M=\bigoplus_{n\in\BZ}M_n$ the {\it Hilbert series\/} $\sum_{n\in\BZ}(\rank_K M_n)t^n$ is the Laurent expansion around $0

Stamatis Vokos

(Talk presented at the 7th Marcel Grossmann Meeting on General Relativity, Stanford, CA, July 24-30, 1994) We study the semi-classical limit of the solution of the Dirac equation in a background electromagnetic/gravitational plane wave. We show that the exact solution corresponding to an asymptotically fixed incoming momentum satisfies constraints consistent

R. Brooks

Wavefunctionals of three dimensional quantum gravity are extracted from the 3D field theoretic analogs of the four dimensional Donaldson polynomials. Our procedure is generalizable to four and other dimensions. This is a summary of a talk presented at the Seventh Marcel Grossmann Meeting on General Relativity, Stanford University, Stanford, CA, USA, July 24

P. A. Shah

It has been shown recently that the motion of solitons at couplings around a critical coupling can be reduced to the dynamics of particles (the zeros of the Higgs field) on a curved manifold with potential. The curvature gives a velocity dependent force, and the magnitude of the potential is proportional to the distance from a critical coupling. In this pape

C. Emmrich, N. Kutz

We extend the action for evolution equations of KdV and MKdV type which was derived in [Capel/Nijhoff] to the case of not periodic, but only equivariant phase space variables, introduced in [Faddeev/Volkov]. The difference of these variables may be interpreted as reduced phase space variables via a Marsden-Weinstein reduction where the monodromies play the r

John F. Donoghue

I give a very brief introduction to the use of effective field theory techniques in quantum calculations of general relativity. The gravitational interaction is naturally organized as a quantum effective field theory and a certain class of quantum corrections can be calculated.

Jonathan M. Evans, Timothy J. Hollowood

A formula for the mass-gap of the supersymmetric $\CP^{n-1}$ sigma model ($n > 1$) in two dimensions is derived: $m/Λ_{\overline{\rm MS}}=\sin(πΔ)/(πΔ)$ where $Δ=1/n$ and $m$ is the mass of the fundamental particle multiplet. This result is obtained by comparing two expressions for the free-energy density in the presence of a coupling to a conserved charge;

Jonathan M. Evans, Timothy J. Hollowood

A formula for the mass-gap of the supersymmetric O($N$) sigma model ($N>4$) in two dimensions is derived: $m/Λ_{\overline{\rm MS}}=2^{2Δ}\sin(πΔ)/(πΔ)$, where $Δ=1/(N-2)$ and $m$ is the mass of the fundamental vector particle in the theory. This result is obtained by comparing two expressions for the free-energy density in the presence of a coupling to a con

J. W. van Holten

New kinds of supersymmetry arise in supersymmetric $\sg$-models describing the motion of spinning point-particles in classical backgrounds, for example black-holes, or the dynamics of monopoles. Their geometric origin is the existence of Killing-Yano tensors. The relation between these concepts is explained and examples are given. --- Contribution to Proceed

J. W. van Holten

The supersymmetric extension of Taub-NUT space admits 4 standard supersymmetries plus several additional non-standard ones. The geometrical origin of these symmetries is traced. The result has applications to fermion modes in gravitational instantons as well as in long-range monopole dynamics.

Takeo Inami, Hitoshi Konno

We consider a general class of boundary terms of the open XYZ spin-1/2 chain compatible with integrability. We have obtained the general elliptic solution of $K$-matrix obeying the boundary Yang-Baxter equation using the $R$-matrix of the eight vertex model and derived the associated integrable spin-chain Hamiltonian.

Bernhard Drabant

Within the framework of braided or quasisymmetric monoidal categories braided Q-supersymmetry is investigated, where Q is a certain functorial isomorphism in a braided symmetric monoidal category. For an ordinary (co-)quasitriangular Hopf algebra (H,R) a braided monoidal category of H-(co-)modules with braiding induced by the R-matrix is considered. It can b

Eric D'Hoker, Steven Weinberg

We investigate the structure of the most general actions with symmetry group $G$, spontaneously broken down to a subgroup $H$. We show that the only possible terms in the Lagrangian density that, although not $G$-invariant, yield $G$-invariant terms in the action, are in one to one correspondence with the generators of the fifth cohomology classes. For the s

Brian Mason, Marc Sher

The first three quarters of this paper consists of a pedagogical review of neutrino oscillations, including vacuum oscillations, constant density matter oscillations and variable density matter oscillations. We then address the question of whether MSW solar neutrino oscillations in the moon could be observed during a solar eclipse. For the small angle MSW so

Ahmed Ali, David London

We update the constraints on the parameters of the quark flavour mixing matrix $V_{CKM}$ in the standard model using the latest experimental and theoretical results as input. We present the 95$\%$ C.L. allowed region of the unitarity triangle and the corresponding ranges for the ratio $\vert V_{td}/V_{ts} \vert$ and for the quantities $\sin 2α$, $\sin 2β$ an

John F. Donoghue

There is a ``toy'' weak matrix element which can be expressed as an integral over the vector and axial vector spectral functions, $ρ_V (s) - ρ_A (s)$. I review our recent evaluation of these spectral functions, the study of four ``Weinberg'' sum rules and the calculation of this matrix element.

P. Colangelo

QCD sum rules are used to calculate the couplings of heavy-light quark pseudoscalar and vector mesons ($D, D^*$ and $B, B^*$) with soft pions, both for finite and infinitely heavy quark mass. The couplings are also computed in the framework of a QCD relativistic potential model; in this approach the relativistic corrections due to the light quark are relevan

Torsten Arens, L. M. Sehgal

It is shown that in the sequential decay $H\to ZZ\to (f_1\bar{f_1})+ (f_2\bar{f_2})$, the energy distribution of the final state particles provides a simple and powerful test of the $HZZ$ vertex. For a standard Higgs boson, the energy spectrum of any final fermion, in the rest frame of $H$, is predicted to be $dΓ/dx\sim 1+β^4-2(x-1)^2$, with $β= \sqrt{1-4m^2

A. A. Pankov, N. Paver

We explore the possibility of deriving model independent limits on the anomalous trilinear electroweak gauge boson couplings from high energy $e^+e^-\to W^+W^-$, by combining the cross sections for the different initial and final states polarizations integrated with suitable kinematical cuts. In the case of the CP conserving couplings the limits can be disen

W. Bietenholz, E. Focht, U. -J. Wiese

Fixed point actions for free and interacting staggered lattice fermions are constructed by iterating renormalization group transformations. At large N the fixed point action for the Gross-Neveu model is a perfect action in the sense of Hasenfratz and Niedermayer, i.e. cut-off effects are completely eliminated. In particular, the fermionic 1-particle energy s

D. Cinabro

We have studied the leptonic decay of the $Υ(1S)$ resonance into tau pairs using the CLEO II detector. A clean sample of tau pair events is identified via events containing two charged particles where exactly one of the particles is an identified electron. We find $B(Υ(1S) \to τ^+ τ^-) = (2.61~\pm~0.12~{+0.09\atop{-0.13}})%$. The result is consistent with ex

Philip D. Mannheim, Demosthenes Kazanas

In the standard treatment of the Einstein gravitational theory the energy-momentum tensor has always been taken to be composed of perfect fluid aggregates of kinematic Newtonian point test particles with fundamental mechanical masses. Moreover, this standard prescription was not revised after the discovery of the mass-generating Higgs mechanism which is know

Donald Marolf

We consider a quantization of the Bianchi IX cosmological model based on taking the constraint to be a self-adjoint operator in an auxiliary Hilbert space. Using a WKB-style self-consistent approximation, the constraint chosen is shown to have only continuous spectrum at zero. Nevertheless, the auxiliary space induces an inner product on the zero-eigenvalue

C. Lange, A. Klümper, J. Zittartz

We have found the exact ground state for a large class of antiferromagnetic spin-one chains with nearest and next-nearest neighbour interactions. The ground state is characterized as a matrix product of local site states and has the properties characteristic of the Haldane scenario.

H. F. Chau

A simple and computationally efficient way of finding inverse avalanches for Abelian sandpiles, called the inverse particle addition operator, is presented. In addition, the method is shown to be optimal in the sense that it requires the minimum amount of computation among methods of the same kind. The method is also conceptually nice because avalanche and i

Tabish Qureshi

Dynamics of tunneling centers (TC) in metallic systems is studied, using the technique of bosonization. The interaction of the TC with the conduction electrons of the metal involves two processes, namely, the screening of the TC by electrons, and the so-called electron assisted tunneling. The presence of the latter process leads to a different form of the re

D. G. Polyakov, B. I. Shklovskii

The prefactor of the activated dissipative conductivity in a plateau range of the quantum Hall effect is studied in the case of a long-range random potential. It is shown that due to long time it takes for an electron to drift along the perimeter of a large percolation cluster, phonons are able to maintain quasi-equilibrium inside the cluster. The saddle poi

P. Le Doussal, T. Giamarchi

We study the 2D vortex-free XY model in a random field, a model for randomly pinned flux lines in a plane. We construct controlled RG recursion relations which allow for replica symmetry breaking (RSB). The fixed point previously found by Cardy and Ostlund in the glass phase $T<T_c$ is {\it unstable} to RSB. The susceptibility $χ$ associated to infinitesimal

R. Eder, Y. Ohta

We present an exact diagonalization study of the dynamical spin and density correlation functions in small clusters of 2D t-J model for intermediate and low electron densities, rho<0.7. Both correlation functions agree remarkably well with the convolution of the single-particle spectral function, i.e. the simplest estimate within the Fermi liquid picture. De

C. Steidel, M. Dickinson

We present results of surveys for high redshift field galaxies selected by their having produced detectable absorption in the spectra of background QSOs. Such surveys, in essence selected by gas cross-section rather than by flux density, are almost completely independent of the conventional magnitude--limited redshift survey, and allow one to follow objects

S. Cristiani, F. La Franca

The present status of the ESO key-programme ``A Homogeneous Bright QSO Survey&#39;&#39; is described together with the first results concerning the QSO counts and the optical luminosity function. The related analysis of the evolution of the radio and X-ray selected QSOs is presented.

R. Turolla, L. Zampieri, L. Nobili

General--relativistic, frequency--dependent radiative transfer in spherical, differentially--moving media is considered. In particular we investigate the character of the differential operator defined by the first two moment equations in the stationary case. We prove that the moment equations form a hyperbolic system when the logarithmic velocity gradient is

Ian Affleck, Andreas W. W. Ludwig, Barbara A. Jones

Numerical renormalization group and conformal field theory work indicate that the two impurity Kondo Hamiltonian has a non-Fermi liquid critical point separating the Kondo-screening phase from the inter-impurity singlet phase when particle-hole (P-H) symmetry is maintained. We clarify the circumstances under which this critical point occurs, pointing out tha

H. Garcia-Compean, T. Matos

The chiral model for self-dual gravity given by Husain in the context of the chiral equations approach is discussed. A Lie algebra corresponding to a finite dimensional subgroup of the group of symplectic diffeomorphisms is found, and then use for expanding the Lie algebra valued connections associated with the chiral model. The self-dual metric can be expli

D. V. Ahluwalia

Continuing our recent argument where we constructed a FNBWW-type spin-$1$ boson having opposite relative intrinsic parity to that of the associated antiparticle, we now study eigenstates of the Charge Conjugation operator. Based on the observation that if $\phi_{_{L}}(p^\mu)$ transforms as a $(0,\,j)$ spinor under Lorentz boosts, then $\Theta_{[j]}\,\phi_{_{

T. S. Biro, C. Gong, B. Mueller

We explain why the maximal positive Lyapunov exponent of classical SU($N$) gauge theory coincides with (twice) the damping rate of a plasmon at rest in the leading order of thermal gauge theory. [This is a substantially revised and expanded version of the manuscript.]

J. G. Esteve, Germán Sierra

We propose a method to construct the ground state $ψ(λ)$ of local lattice hamiltonians with the generic form $H_0 + λH_1$, where $λ$ is a coupling constant and $H_0$ is a hamiltonian with a non degenerate ground state $ψ_0$. The method is based on the choice of an exponential ansatz $ψ(λ) = {\rm exp}(U(λ)) ψ_0$, which is a sort of generalized lattice version

M. B. Voloshin

A substantial enhancement is found of the $b \to c\,{\overline c}\, s$ decay rate due to the QCD interaction within the $\overline c s$ pair, which enhancement may amount to 30\%, or more. Some general features of calculation of the QCD radiative corrections in two first orders are discussed.

R. B. Mann, W. N. Sajko

We demonstrate that charged null particles can be infinitely blue\-shifted in a Kerr-Newman spacetime. The surface of infinite blueshift can be outside of the ergosphere in a Kerr-Newman spacetime, and outside of the outer event horizon for a Reissner-Nordstrom spacetime. Implications for extensions of the standard model which incorporate charged neutrinos a

S. Bauberger, F. A. Berends, M. Boehm, M. Buza

Motivated by the precision results in the electroweak theory studies of two-loopFeynman diagrams are performed. Specifically this paper gives a contribution to the knowledge of massive two-loop self-energy diagrams in arbitrary and especially four dimensions.This is done in three respects firstly results in terms of generalized, multivariable hypergeometric

C. A. A. Nunes, F. S. Navarra, P. Ring, M. Schaden

An effective hamiltonian for heavy quarkonia is derived from QCD by separating gluonic fields in background and quantum fields and neglecting anharmonic contributions. Mesonic states with nonperturbative gluonic components are constructed. These states are invariant under gauge changes of the background fields and form an orthogonal basis. The effective hami

Arne Schirrmacher

An essential prerequisite for the study of q-deformed physics are particle states in position and momentum representation. In order to relate x- and p-space by Fourier transformations the appropriate q-exponential series related to orthogonal quantum symmetries is constructed. It turns out to be a new q-special function giving rise to q-plane wave solutions

Shin-ichi Tadaki, Macoto Kikuchi

The jam phases in a two-dimensional cellular automata model of traffic flow are investigated by computer simulations. Two different types of the jam phases are found. The spatially diagonal long-range correlation obeys the power law at the low-density jam configurations. The diagonal correlation exponentially decays at the high-density jam. The exponent of t

D. V. Fedorov, A. S. Jensen, K. Riisager

The large distance behavior of weakly bound three-body systems is investigated. The Schrödinger equation and the Faddeev equations are reformulated by an expansion in eigenfunctions of the angular part of a corresponding operator. The resulting coupled set of effective radial equations are then derived. Both two- and three-body asymptotic behavior are possib

D. V. Fedorov, A. S. Jensen, K. Riisager

We investigate conditions for the occurrence of Efimov states in the recently discovered halo nuclei. These states could appear in systems, where one neutron is added to a pronounced one-neutron halo nucleus. Detailed calculations of the properties of the states are presented and promising candidates are discussed.

Kurt Haller, Edwin Lim-Lombridas

We quantize Quantum Electrodynamics in $2+1$ dimensions coupled to a Chern-Simons (CS) term and a charged spinor field, in covariant gauges and in the Coulomb gauge. The resulting Maxwell-Chern-Simons (MCS) theory describes charged fermions interacting with each other and with topologically massive propagating photons. We impose Gauss&#39;s law and the gauge

N. G. Deshpande, Xiao-Gang He

The penguin mediated processes $b\rightarrow s g$ and $b\rightarrow s l^+l^-$ are studied. In the Standard Model, for the leptonic modes improvement in experimental limits will put strigient bounds on the top mass, where the present limit from $b\rightarrow s μ^+μ^-$ is 390 GeV. For hadronic penguin processes, although the gluonic penguin dominates, we find

W. Bernreuther

The matching condition which determines the effect of a heavy quark threshold on the running of the QCD coupling $α_{\overline{MS}}$ is reviewed. The matching scale is arbitrary to some extent. However, this affects the value of $α_{\overline{MS}}$ away from the threshold region only marginally.

Thomas Mannel

A mini-review of the heavy mass expansion in QCD is given. We focus on exclusive semileptonic decays and some topics of recent interest in inclusive decays of heavy hadrons.

C. Bachas, T. N. Tomaras

We establish the existence of static, classically-stable, winding solitons in renormalizable three-dimensional gauge models, with topologically trivial target space and vacuum manifold. They are prototypes for possible analogous particle-like excitations in the higgs sector of the standard electroweak theory.

Ulf-G. Meißner

I consider some selected topics in chiral perturbation theory (CHPT) as probed at colliders such as DA$Φ$NE. Emphasis is put on processes involving pions in the isospin zero S-wave which require multi-loop calculations. These include the scalar form factor of the pion, two--photon fusion into pion pairs and $K_{\ell 4}$--decays. The physics of the chiral ano

Alakabha Datta, Sandip Pakvasa

We calculate the s-wave strong interaction $Λ$$π$ phase shift at the $Ξ$ mass taking into account contributions from the ${{\frac{1}{2}}}^{-}$ and ${{\frac{3}{2}}}^{-}$ $Σ$ resonances. We find the S-wave phase shift to be small, of the order of 0.3 degrees and bounded by 0.5 degrees.

S. V. Goloskokov, S. P. Kuleshov, O. V. Selyugin

The one-to-one connection between the eikonal phase and the ratio of the elastic and total cross section is shown. Based on new experimental data of Collaboration CDF we analyzed intercept and power of the logarithmic growth of the Born and total Pomeron amplitude.

N. G. Uraltsev

Using rather general consideration I argue that the numerical impact of the existing next-to-leading logarithmic summations of terms $\log{m_b/m_c}$ for perturbative factors $η_A$, $η_V$ in the exclusive zero recoil semileptonic transitions is irrelevant, and adopting corresponding corrections beyond the exact one loop result for both estimating the values o

K. S. Babu, Jogesh C. Pati, Hanns Stremnitzer

Two vector-like families with masses of order 1 TeV, one of which is a doublet of $SU(2)_L$ and the other a doublet of $SU(2)_R$, have been predicted to exist in the context of a viable and economical SUSY composite model. One of the many attractive features of the model is an explanation of the inter-family mass-hierarchy for which the existence of the two

K. Hagiwara, D. Haidt, C. S. Kim, S. Matsumoto

A novel approach to study electroweak physics at one-loop level in generic ${\rm SU(2)_L \times U(1)_Y}$ theories is introduced. It separates the 1-loop corrections into two pieces: process specific ones from vertex and box contributions, and universal ones from contributions to the gauge boson propagators. The latter are parametrized in terms of four effect

J. L. Hewett

The possibility of using the charm system to search for new physics is addressed. Phenomena such as $D^0-\bar D^0$ mixing and rare decays of charmed mesons are first examined in the Standard Model to test our present understanding and to serve as benchmarks for signals from new sources. The effects of new physics from various classes of non-standard dynamica

F. Babalievski

An algorithm for solving the random resistor problem by means of the transfer-matrix approach is presented. Preconditioning by spanning clusters extraction both reduces the size of the conductivity matrix and speed up the calculations.

B. Fourcade, Jean Perrin

The field-theory for multifractals in percolation is reformulated in such a way that multifractal exponents clearly appear as eigenvalues of a second renormalization group. The first renormalization group describes geometrical properties of percolation clusters, while the second-one describes electrical properties, including noise cumulants. In this context,

E. Goering, O. Müller, M. Klemm, J. P. Urbach

We have measured the V 2p3/2 and O 1s x-ray absorption spectra of single crystal V2O5 and V6O13 and compared to linear combinations of atomic orbitals (LCAO) density of states (DOS) calculations. The spectra change dramatically with incident angle. The use of polarized light and a single crystal limits the number of transitions possible, revealing spectral f

T. S. Kobayakawa, Y. Hatsugai, M. Kohmoto, A. Zee

The universal connected correlations proposed recently between eigenvalues of unitary random matrices is examined numerically. We perform an ensemble average by the Monte Carlo sampling. Although density of eigenvalues and a bare correlation of the eigenvalues are not universal, the connected correlation shows a universal behavior after smoothing.

Atsushi Yamagata

We perform the Monte Carlo simulations of the hard-sphere lattice gas on the simple cubic lattice with nearest neighbour exclusion. The critical activity is estimated, $z_{\rm c} = 1.0588 \pm 0.0003$. Using a relation between the hard-sphere lattice gas and the antiferromagnetic Ising model in an external magnetic field, we conclude that there is no re-entra

Pascale Fung, Kathleen McKeown

We propose a new algorithm called DK-vec for aligning pairs of Asian/Indo-European noisy parallel texts without sentence boundaries. DK-vec improves on previous alignment algorithms in that it handles better the non-linear nature of noisy corpora. The algorithm uses frequency, position and recency information as features for pattern matching. Dynamic Time Wa

H. M. P. Couchman, P. A. Thomas, F. R. Pearce

We present an implementation of Smoothed Particle Hydrodynamics (SPH) in an adaptive-mesh PPPM algorithm. The code evolves a mixture of purely gravitational particles and gas particles. The code retains the desirable properties of previous PPPM--SPH implementations; speed under light clustering, naturally periodic boundary conditions and accurate pairwise fo

Andrew Gould

Lensing of one member of a binary by its companion is studied for several classes of binaries. For binaries in which at least one member is an ordinary (non-compact) star, the optical depths to lensing is extremely low, $τ\lsim v_\esc^4/c^4\sim 10^{-11}$. Here $v_\esc$ is the escape velocity from the component with the weaker potential. Binaries composed of

F. A. Rasio, S. McMillan, P. Hut

The hierarchical triple system containing the millisecond pulsar PSR B1620-26 in M4 is the first triple star system ever detected in a globular cluster. Such systems should form in globular clusters as a result of dynamical interactions between binaries. We propose that the triple system containing PSR B1620-26 formed through an exchange interaction between

D. S. Salopek, J. M. Stewart

Using Hamilton-Jacobi theory, we develop a formalism for solving semi-classical cosmological perturbations which does not require an explicit choice of time-hypersurface. The Hamilton-Jacobi equation for gravity interacting with matter (either a scalar or dust field) is solved by making an Ansatz which includes all terms quadratic in the spatial curvature. G

Matthew Colless

The optical luminosity function is a fundamental characterization of the galaxy population. A combination of earlier redshift surveys with two new surveys allows the first accurate determination of the evolution of the luminosity function with redshift, and reveals a marked steepening of the faint end slope. This effect is more profound for star-forming gala

L. S. Finn

Radio observations of neutron star binary pulsar systems have constrained strongly the masses of eight neutron stars. Assuming neutron star masses are uniformly distributed between lower and upper bounds $m_l$ and $m_u$, the observations determine with 95\% confidence that $1.01 < m_l/\text{M}_\odot < 1.34$ and $1.43 < m_u/\text{M}_\odot < 1.64$. These limit

John Ellis, Marek Karliner, Mark A. Samuel, Eric Steinfelds

We use Pade Approximants to obtain improved predictions for the anomalous magnetic moments of the electron and the muon. These are needed because of the very precise experimental values presently obtained for the electron, and soon to be obtained at BNL for the muon. The Pade prediction for the QED contribution to the anomalous magnetic moment of the muon di

A. Dabelstein

The structure of the Higgs sector in the minimal supersymmetric standard model is reviewed at the one-loop level. An on-shell renormalization scheme of the MSSM Higgs sector is presented in detail together with the complete list of formulae for the neutral Higgs masses at the one-loop level. The results of a complete one- loop calculation for the mass spectr

A. D. Rutenberg, A. J. Bray

We present a simple, unified approach to determining the growth law for the characteristic length scale, $L(t)$, in the phase ordering kinetics of a system quenched from a disordered phase to within an ordered phase. This approach, based on a scaling assumption for pair correlations, determines $L(t)$ self-consistently for purely dissipative dynamics by comp

F. Ferrari, J. Sobczyk

The usual Laurent expansion of the analytic tensors on the complex plane is generalized to any closed and orientable Riemann surface represented as an affine algebraic curve. As an application, the operator formalism for the $b-c$ systems is developed. The physical states are expressed by means of creation and annihilation operators as in the complex plane a

Tatsuhiko Koike, Takashi Mishima

A simple analytic model is presented which exhibits a critical behavior in black hole formation, namely, collapse of a thin shell coupled with outgoing null fluid. It is seen that the critical behavior is caused by the gravitational nonlinearity near the event horizon. We calculate the value of the critical exponent analytically and find that it is very depe

A. Kreutz, M. Holder, M. Rost, R. Werthenbach

Improved branching ratios were measured for the $K_L \to 3 \pi^0 $ decay in a neutral beam at the CERN SPS with the NA31 detector: $\Gamma (K_L \to 3 \pi^0) / \Gamma (K_L \to \pi^+ \pi^- \pi^0) = 1.611 \pm 0.037$ and $\Gamma (K_L \to 3 \pi^0) / \Gamma (K_L \to \pi e \nu ) = 0.545 \pm 0.010$. From the first number an upper limit for $\Delta I =5/2$ and $\Delt

A. Honecker

The massive high-temperature phase of the chiral Potts quantum chain is studied using perturbative methods. For the Z_3-chain we present high-temperature expansions for the groundstate energy and the dispersion relations of the two single-particle states as well as two-particle states at general values of the parameters. We also present a perturbative argume

O. K. Vorov, A. V. Vagov

The density of states for a particle moving in a random potential with a Gaussian correlator is calculated exactly using the functional integral technique. It is achieved by expressing the functional degrees of freedom in terms of the spectral variables and the parameters of isospectral transformations of the potential. These transformations are given explic

Z. Fodor, J. Hein, K. Jansen, A. Jaster

Numerical simulations are performed to study the finite temperature phase transition in the SU(2) Higgs model on the lattice. In the presently investigated range of the Higgs boson mass, below 50 GeV, the phase transition turns out to be of first order and its strength is rapidly decreasing with increasing Higgs boson mass. In order to control the systematic

C. Ciofi degli Atti, S. Simula

Semi-inclusive deep inelastic lepton scattering off few-nucleon systems is investigated assuming that virtual boson absorption occurs on a hadronic cluster which can be either a two-nucleon correlated pair or a six-quark bag. In both cases the relevance of nuclear effects on forward and backward nucleon emissions is illustrated and the differences expected i

Erik Koelink

An identity involving basic Bessel functions and Al-Salam--Chihara polynomials is proved for which we recover Graf&#39;s addition formula for the Bessel function as the base $q$ tends to $1$. The corresponding product formula is derived. Some known identities for Jackson&#39;s $q$-Bessel functions are obtained as limiting cases. As special cases we prove ide

Erik Koelink

Jacobi polynomials are mapped onto the continuous Hahn polynomials by the Fourier transform and the orthogonality relations for the continuous Hahn polynomials then follow from the orthogonality relations for the Jacobi polynomials and the Parseval formula. In a special case this relation dates back to work by Bateman in 1933 and we follow a part of the hist

Madhav V. Marathe, H. Breu, Harry B. Hunt, S. S. Ravi

Unit disk graphs are intersection graphs of circles of unit radius in the plane. We present simple and provably good heuristics for a number of classical NP-hard optimization problems on unit disk graphs. The problems considered include maximum independent set, minimum vertex cover, minimum coloring and minimum dominating set. We also present an on-line colo

Madhav V. Marathe, Harry B. Hunt, S. S. Ravi

We extend the concept of polynomial time approximation algorithms to apply to problems for hierarchically specified graphs, many of which are PSPACE-complete. Assuming P != PSPACE, the existence or nonexistence of such efficient approximation algorithms is characterized, for several standard graph theoretic and combinatorial problems. We present polynomial t

Avrim Blum, Prasad Chalasani

Recent papers have shown optimally-competitive on-line strategies for a robot traveling from a point $s$ to a point $t$ in certain unknown geometric environments. We consider the question: Having gained some partial information about the scene on its first trip from $s$ to $t$, can the robot improve its performance on subsequent trips it might make? This is

Avrim Blum, Prasad Chalasani, Don Coppersmith, Bill Pulleyblank

We are given a set of points $p_1,\ldots , p_n$ and a symmetric distance matrix $(d_{ij})$ giving the distance between $p_i$ and $p_j$. We wish to construct a tour that minimizes $\sum_{i=1}^n \ell(i)$, where $\ell(i)$ is the {\em latency} of $p_i$, defined to be the distance traveled before first visiting $p_i$. This problem is also known in the literature

R. Ravi, R. Sundaram, Madhav V. Marathe, S. S. Ravi

We study the problem of finding small trees. Classical network design problems are considered with the additional constraint that only a specified number $k$ of nodes are required to be connected in the solution. A prototypical example is the $k$MST problem in which we require a tree of minimum weight spanning at least $k$ nodes in an edge-weighted graph. We

Simone Artz, Luca Mezincescu, Rafael I. Nepomechie

We propose an expression for the eigenvalues of the transfer matrix for the $U_q(B_n)$-invariant open quantum spin chain associated with the fundamental representation of $A^{(2)}_{2n}$. By assumption, the Bethe Ansatz equations are ``doubled&#39;&#39; with respect to those of the corresponding closed chain with periodic boundary conditions. We verify that t

JM Figueroa-O&#39;Farrill, CM Hull, L Palacios, E Ramos

The conventional quantization of w_3 strings gives theories which are equivalent to special cases of bosonic strings. We explore whether a more general quantization can lead to new generalized W_3 string theories by seeking to construct quantum BRST charges directly without requiring the existence of a quantum W_3 algebra. We study W_3-like strings with a di

Joshua Boorstein, David Kutasov

We discuss the effective action for Polyakov-Wilson loops winding around compact Euclidean time, which serve as order parameters for the finite temperature deconfinement transition in $SU(N)$ Yang-Mills gauge theory. We then apply our results to the study of the high temperature continuation of the confining phase, and to the analysis of certain $Z_N$ domain

F. Toppan

In this talk the class of multi-fields reductions of the KP and super-KP hierarchies (leading to non-purely differential Lax operators) is revisited from the point of view of coset construction. This means in particular that all the hamiltonian densities of the infinite tower belong to a coset algebra of a given Poisson brackets structure.

F. Toppan

The structure of classical non-linear $\cw$ algebras closing on rational functions is analyzed both for the ordinary and the supersymmetric case. Such algebras appear as a result of a coset construction. Their relevance to physical applications is pointed out.

H. Sato

We present the new explicit geometrical knowledge of the Landau-Ginzburg orbifolds, when a typical type of superpotential is considered. Relying on toric geometry, we show the one-to-one correspondence between some of the $(a,c)$ states with $U(1)$ charges $(-1,1)$ and the $(1,1)$ forms coming from blowing-up processes. Consequently, we find the monomial-div

M. Sakamoto, M. Tachibana

We study toroidal orbifold models with topologically invariant terms in the path integral formalism and give physical interpretations of the terms from an operator formalism point of view. We briefly discuss a possibility of a new class of modular invariant orbifold models.

K. Behrndt

We investigate quantum corrections of the 2-d dilaton gravity near the singularity. Our motivation comes from a s-wave reduced cosmological solution which is classically singular in the scalar fields (dilaton and moduli). As result we find, that the singularity disappears and a dilaton/moduli potential is created.

T. A. Osborn, F. H. Molzahn

The Moyal--Weyl description of quantum mechanics provides a comprehensive phase space representation of dynamics. The Weyl symbol image of the Heisenberg picture evolution operator is regular in $\hbar$. Its semiclassical expansion `coefficients,&#39; acting on symbols that represent observables, are simple, globally defined differential operators constructe

A. Khodjamirian, R. Rückl

We discuss the form factors of the heavy-to-light transitions $B \ra π$ and $D\ra π$, the $B^*B π$ and $D^*D π$ coupling constants, and the nonfactorizable amplitude of the decay $ B \ra J/ψK$ in the framework of QCD sum rules.

L. Kisslinger, Zhenping Li

A gauge invariant electromagnetic two-point function, crucial to the investigations of the violation of isospin symmetry, is derived for heavy-light quark systems. Thus QED can be consistently introduced into the QCD Sum Rule method, which was not previously possible.

R. D. Ball, S. Forte

We show that the double asymptotic scaling of the HERA structure function data is consistent with pre-HERA data at larger $x$, soft pomeron behaviour at small $x$ and a sensible starting scale $Q_0$. We can thus actually calculate $F_2^p$ at small $x$ and large $Q^2$ by evolving up perturbatively at two loops, without any fitting.

R. D. Ball, S. Forte

We show that the rise in $F_2^p$ at small $x$ and large $Q^2$ seen at HERA is indeed the non-Regge double asymptotic scaling behaviour expected from the perturbative emission of strongly ordered hard gluons. An alternative explanation, in which there is no strong ordering, and a new hard Reggeon is generated, is also tried but found wanting: its theoretical

Naoya Hata, Paul Langacker

Besides the opportunity for discovering new neutrino physics, solar neutrino measurements provide a sensitive probe of the solar interior, and thus a rigorous test of solar model predictions. We present model independent determinations of the neutrino spectrum by using relevant flux components as free parameters subject only to the luminosity constraint. (1)