September 1994 arXiv papers — page 4

K. G. Chetyrkin, C. A. Dominguez, D. Pirjol, K. Schilcher

The correlators of light-quark currents contain mass-singularities of the form log(m^2/Q^2). It has been known for quite some time that these mass- logarithms can be absorbed into the vacuum expectation values of other operators of appropriate dimension, provided that schemes without normal- ordering are used. We discuss in detail this procedure for the case

Philip G. Ratcliffe

We discuss the present situation with regard to polarised nucleon structure function measurements. In particular we examine the status of the Bjorken sum rule in the light of the recent data on the spin structure functions of (i) the deuteron obtained by the SMC group at CERN and (ii) the neutron by the E142 group at SLAC. In order to fully exploit all the a

H. Dreiner, G. K. Leontaris, S. Lola, Graham G. Ross

A very simple extension of the standard model to include an Abelian family symmetry is able to describe the hierarchy of quark and lepton masses and their mixing angles together with the unification of gauge couplings. We consider the implications of this model for neutrino masses and mixing angles and show that they are determined up to a discrete ambiguity

Philip G. Ratcliffe

The status of the Bjorken sum rule is examined in the light of recent data on the spin structure functions of the deuteron and proton obtained by the SMC group, the neutron by the E142 group and the proton by the E143 group. Combining the new data with that already obtained for the proton by the EMC group and SLAC/YALE collaborations, we show that the Bjorke

T. Moroi, M. Yamaguchi, T. Yanagida

We study the solution to the Polonyi problem where the Polonyi field weighs as $O(10{\rm TeV})$ and decays just before the primordial nucleosynthesis. It is shown that in spite of a large entropy production by the Polonyi field decay, one can naturally explain the present value of the baryon-to-entropy ratio, $n_B/s \sim (10^{-10}-10^{-11})$ if the Affleck-D

T. Hayashi, Y. Koide, M. Matsuda, M. Tanimoto

The effect of the "chromo-electric" dipole moment on the electric dipole moment(EDM) of the neutron is studied in the two-Higgs-doublet model. The Weinberg's operator $O_{3g}=GG\t G$ and the operator $O_{qg}=\bar qσ\t Gq$ are both investigated in the cases of $\tan\b\gg 1$, $\tan\b\ll 1$ and $\tan\b\simeq 1$. The neutron EDM is considerably reduc

Lynne H. Orr, W. J. Stirling

Extra soft jets in top events in $p \bar p$ collisions may arise not only from gluons radiated off initial state partons or final state $b$ quarks, but may also be radiated from the $t$ quarks themselves. We discuss predictions for distributions of soft gluons in $t \bar t$ production at the Tevatron and the implications for attempts to measure the top mass

Joseph D. Romano, Richard H. Price

We discuss isometric embedding diagrams for the visualization of initial data for the problem of the head-on collision of two black holes. The problem of constructing the embedding diagrams is explicitly presented for the best studied initial data, the Misner geometry. We present a partial solution of the embedding diagrams and discuss issues related to comp

Sucheta Koshti, Naresh Dadhich

We obtain the most general explicit (anti)self-dual solution of the Einstein equations. We find that any (anti)self-dual solution can be characterised by three free functions of which one is harmonic. Any stationary (anti)self-dual solution can be characterised by a harmonic function. It turns out that the form of the Gibbons and Hawking multi-center metrics

A. Tsutsumi, S. Haruki

We study the regularity of solutions of functional equations of a generalized mean value type. In this paper we give sufficient conditions for the regularity by using hypoellipticity which is a concept of the theory of partial differential equations. Further we also give an affirmative answer to a conjecture of H.Światak. A part of the results was announced

R. Z. Bariev, A. Klümper, A. Schadschneider, J. Zittartz

A recently presented anisotropic generalization of the multicomponent supersymmetric $t-J$ model in one dimension is investigated. This model of fermions with general spin-$S$ is solved by Bethe ansatz for the ground state and the low-lying excitations. Due to the anisotropy of the interaction the model possesses $2S$ massive modes and one single gapless exc

A. V. Balatsky, Elihu Abrahams

The magnetic analog of odd-time superconducting order is introduced. It is shown that the classification of possible odd-time magnetic states admits the existence of a novel state - the chiral spin nematic - which is characterized by an odd-in-time spin-spin correlation function.The known example of the chiral spin liquid appears naturally in this approach.

D. Allen, D. Senechal

The antiferromagnetic Heisenberg model on a chain with nearest and next nearest neighbor couplings is mapped onto the $SO(3)$ nonlinear sigma model in the continuum limit. In one spatial dimension this model is always in its disordered phase and a gap opens to excited states. The latter form a doubly degenerate spin-1 branch at all orders in $1/N$. We argue

Yan-Chr Tsai, Yonathan Shapir

The deposition dynamics of particles (or the growth of a rigid crystal) on a disordered substrate at a finite deposition rate is explored. We begin with an equation of motion which includes, in addition to the disorder, the periodic potential due to the discrete size of the particles (or to the lattice structure of the crystal) as well as the term introduced

Rodolfo A. Jalabert, Jean-Louis Pichard

We consider elastic reflection and transmission of electrons by a disordered system characterized by a $2N\!\times\!2N$ scattering matrix $S$. Expressing $S$ in terms of the $N$ radial parameters and of the four $N\!\times\!N$ unitary matrices used for the standard transfer matrix parametrization, we calculate their probability distributions for the circular

Joel D. Shore, Dirk Jan Bukman

We consider both equilibrium and kinetic aspects of the phase separation (``thermal faceting") of thermodynamically unstable crystal surfaces into a hill--valley structure. The model we study is an Ising lattice gas for a simple cubic crystal with nearest--neighbor attractive interactions and weak next--nearest--neighbor repulsive interactions. It is lik

S. Colombi, F. R. Bouchet, R. Schaeffer

We study the errors brought by finite volume effects and dilution effects on the practical determination of the count probability distribution function P_N(n,L), which is the probability of having N objects in a cell of volume L^3 for a set of average number density n. Dilution effects are particularly relevant to the so-called sparse sampling strategy. This

S. Fedoruk, V. G. Zima

Covariant first and second quantization of the free d=4 massless superparticle are implemented with the introduction of purely gauge auxiliary spinor Lorentz harmonics. It is shown that the general solution of the condition of maslessness is a sum of two independent chiral superfields with each of them corresponding to finite superspin. A translationally cov

M. Rueter H. G. Dosch

We calculate the squared gluon field strengths of a heavy q-$\rm \bar{q}$-pair in the model of the stochastic vacuum. We observe that with increasing separation a chromoelectric flux tube is built. The properties of the emerging flux tube are investigated.

K. Funahashi, T. Kashiwa, S. Sakoda, K. Fujii

Using the generalized coherent states we argue that the path integral formulae for $SU(2)$ and $SU(1,1)$ (in the discrete series) are WKB exact,if the starting point is expressed as the trace of $e^{-iT\hat H}$ with $\hat H$ being given by a linear combination of generators. In our case,WKB approximation is achieved by taking a large ``spin'' limit:

Naoyuki Haba, Chuichiro Hattori, Masahisa Matsuda, Takeo Matsuoka

In Calabi-Yau string compactification, it is pointed out that there exists a new type of $SU(5) \times U(1)^2$ model (the aligned $SU(5) \times U(1)^2$ model) in which the $SU(5)$ differs from the standard $SU(5)$ and also from the flipped $SU(5)$. With the aid of the discrete symmetry suggested from Gepner model, we construct a simple and phenomenologically

J. Choi

Sphaleron energies within the standard model with a real Higgs singlet added on are calculated. The coupled non-linear equations of motion are numerically solved and the sphaleron energy evaluated for a set of parameters in the Higgs potential. I find a small difference in the sphaleron energy compared to the standard model. A slightly stronger constraint on

Mirjam Cvetič, Donam Youm

We study supersymmetric, four-dimensional (4-d), Abelian charged black holes (BH's) arising in (4+n)-d (1 \le n \le 7) Kaluza-Klein (KK) theories. Such solutions, which satisfy supersymmetric Killing spinor equations (formally satisfied for any n) and saturate the corresponding Bogomol'nyi bounds, can be obtained if and only if the isometry group of

M. Bianchi, F. Fucito, G. C. Rossi, M. Martellini

In this talk we will describe a string solution which contains a self-dual (instantonic) metric and study its properties. Talk given by M.Bianchi at the Seventh Marcel Grossmann Meeting, Stanford July 24-30, 1994.

Keith R. Dienes

We provide a non-technical introduction to "misaligned supersymmetry", a generic phenomenon in string theory which describes how the arrangement of bosonic and fermionic states at all string energy levels conspires to preserve finite string amplitudes even in the absence of spacetime supersymmetry. Misaligned supersymmetry thus naturally constrains t

A. N. Kamal, A. B. Santra

In order to probe the factorization hypothesis in color-suppressed $B \rightarrow ψ(2S) + K (K^*)$ decays we have studied three ratios: $ R \equiv B (B \rightarrow ψK) / B (B \rightarrow ψ(2S) K)$, $ R' \equiv B (B \rightarrow ψK^*) / B (B \rightarrow ψ(2S) K^*)$ and $ P_L^\prime \equiv Γ_L (B \rightarrow ψ(2S) K^*)/Γ(B \rightarrow ψ(2S) K^*)$ in several

A. A. Gvozdev, N. V. Mikheev, L. A. Vassilevskaya

The radiative decay of the massive neutrino $ν_i \rightarrow ν_j γ( m_i > m_j )$ in the external electromagnetic field is analyzed in detail in the framework of the standard model with lepton mixing. It is shown, that a sort of a catalysis of the neutrino radiative decay takes place. The effect of catalysis is significant in the strong electromagnetic fields

M. Shifman

The theory of preasymptotic effects in inclusive decays of heavy flavors is briefly reviewed.

M. Shifman

Recent progress in determination of $|V_{cb}|$ within the heavy quark expansion is reported. Both exclusive and inclusive approaches are discussed.

J. F. Gunion, J. G. Kelly, J. Ohnemus

We demonstrate that supersymmetric decay modes of the neutral Higgs bosons of the MSSM could well make their detection extremely difficult when produced singly in $\gam\gam$ collisions at a back-scattered laser beam facility.

Aernout C. D. van Enter, Roberto Fernández, Roman Kotecký

We show that decimation transformations applied to high-$q$ Potts models result in non-Gibbsian measures even for temperatures higher than the transition temperature. We also show that majority transformations applied to the Ising model in a very strong field at low temperatures produce non-Gibbsian measures. This shows that pathological behavior of renormal

Jorge Pullin

We apply linear perturbation theory to the study of the universality and criticality first observed by Choptuik in gravitational collapse. Since these are essentially nonlinear phenomena our attempt is only a rough approximation. In spite of this, universal behavior of the final black hole mass is observed with an exponent of 1/2, slightly higher than the ob

Matt Visser

Considerable interest has recently been expressed regarding the issue of whether or not quantum field theory on a fixed but curved background spacetime satisfies the averaged null energy condition (ANEC). A comment by Wald and Yurtsever [Phys. Rev. D43, 403 (1991)] indicates that in general the answer is no. In this note I explore this issue in more detail,

O. Bertolami, P. V. Moniz

Retrieval of classical behaviour in quantum cosmology is usually discussed in the framework of minisuperspace models in the presence of scalar fields together with the inhomogeneous modes either of the gravitational or of the scalar fields. In this work we propose alternatively a model where the scalar field is replaced by a massive vector field with global

Gerhard Rein

The Vlasov-Einstein system describes a self-gravitating, collisionless gas within the framework of general relativity. We investigate the initial value problem in a cosmological setting with spherical, plane, or hyperbolic symmetry and prove that for small initial data solutions exist up to a spacetime singularity which is a curvature and a crushing singular

R. Z. Bariev, A. Klümper, A. Schadschneider, J. Zittartz

A fermion model consisting of two chains with interchain tunneling is formulated and solved exactly by the Bethe ansatz method. The interchain tunneling leads to Cooper pair like bound states and a threshold energy is required to overcome the binding energy. The correlation functions manifest superconducting properties.

M. M. Fogler, B. I. Shklovskii

The Hall conductivity $σ_{\rm xy}$ of a two-dimensional electron system is quantized in units of $e^2/h$ when the Fermi level is located in the mobility gap between two Landau levels. We consider the deviation of $σ_{\rm xy}$ from a quantized value caused by the thermal activation of electrons to the extended states for the case of a long range random potent

Hanchul Kim, Jisoon Ihm

We present an ab initio pseudopotential local density functional calculation for stoichiometric high-Tc cuprate YBa_2Cu_3O_7 using the plane-wave basis set. We have overcome well-known difficulties in applying pseudopotential methods to first-row elements, transition metals, and rare-earth materials by carefully generating norm-conserving pseudopotentials wi

J. P. Hessling, Yu. Galperin

We calculate low-frequency noise (LFN) in a quantum point contact (QPC) which is electrostatically defined in a 2D electron gas of a GaAs-AlGaAs heterostructure. The conventional source of LFN in such systems are scattering potentials fluctuating in time acting upon injected electrons. One can discriminate between potentials of different origin -- noise may

A. Matro, D. L. Freeman, J. D. Doll

In this paper we present a method for locating transition states and higher-order saddles on potential energy surfaces using double-ended classical trajectories. We then apply this method to 7- and 8-atom Lennard-Jones clusters, finding one previously unreported transition state for the 7-atom cluster and two for the 8-atom cluster.

John G. Cramer, Robert L. Forward, Michael S. Morris, Matt Visser

Visser has suggested traversable 3-dimensional wormholes that could plausibly form naturally during Big Bang inflation. A wormhole mouth embedded in high mass density might accrete mass, giving the other mouth a net *negative* mass of unusual gravitational properties. The lensing of such a gravitationally negative anomalous compact halo object (GNACHO) will

Moshe Rozali

We show that heavy fermions decouple from the low energy physics also in non-perturbative instanton effects. Provided the heavy fermions are lighter than the symmetry breaking scale, all the instanton effects should be expressed as local operators in the effective Lagrangian. The effective theory itself doesn't admit instantons. We present the mechanism

K. M. Benson, M. Saadi

We describe flux tubes and their interactions in a low energy sigma model induced by $SU({N_f}) \rightarrow SO({N_f})$ flavor symmetry breaking in $SO(N_c)$ QCD. Unlike standard QCD, this model allows gauge confinement to manifest itself in the low energy theory, which has unscreened spinor color sources and global $Z_2$ flux tubes. We construct the flux tub

Paul Aspinwall, Brian Greene

We clarify certain important issues relevant for the geometric interpretation of a large class of N = 2 superconformal theories. By fully exploiting the phase structure of these theories (discovered in earlier works) we are able to clearly identify their geometric content. One application is to present a simple and natural resolution to the question of what

J. Salas

A method for computing low--temperature series for renormalized operators in the two--dimensional Ising model is proposed. These series are applied to the study of the properties of the truncated renormalized Hamiltonians when we start at very low temperature and zero field. The truncated Hamiltonians for majority rule, Kadanoff transformation and decimation

F. I. Mikhail, M. I. Wanas, E. I. Lashin, Ahmed Hindawi

The general solution of Møller's field equations in case of spherical symmetry is derived. The previously obtained solutions are verified as special cases of the general solution.

Scott Chapman, Pierre Scotto, Ulrich Heinz

The Hanbury-Brown Twiss correlation function for two identical particles is studied for systems with cylindrical symmetry. Its shape for small values of the relative momentum is derived in a model independent way. In addition to the usual quadratic ``side'', ``out'' and ``longitudinal'' terms in the exponent of the correlator, a previously neglected ``out-lo

Yoshifumi R. Shimizu, Masayuki Matsuzaki

The nuclear wobbling motion is studied from a microscopic viewpoint. It is shown that the expressions not only of the excitation energy but also of the electromagnetic transition rate in the microscopic RPA framework can be cast into the corresponding forms of the macroscopic rotor model. Criteria to identify the rotational band associated with the wobbling

Nancy Lynch, Isaac Saias, Roberto Segala

A method of analyzing time bounds for randomized distributed algorithms is presented, in the context of a new and general framework for describing and reasoning about randomized algorithms. The method consists of proving auxiliary statements of the form U (t)->(p) U', which means that whenever the algorithm begins in a state in set U, with probability p,

Michel Goemans, Nancy Lynch, Isaac Saias

We consider the following scheduling problem. A system is composed of $n$ processors drawn from a pool of $N$. The processors can become faulty while in operation and faulty processors never recover. A report is issued whenever a fault occurs. This report states only the existence of a fault, but does not indicate its location. Based on this report, the sche

Isaac Saias

The correctness of most randomized distributed algorithms is expressed by a statement of the form ``some predicate of the executions holds with high probability, regardless of the order in which actions are scheduled''. In this paper, we present a general methodology to prove correctness statements of such randomized algorithms. Specifically, we show

V. L. Vereschagin

The main subject of the paper is the so-called Discrete Painlevé-1 Equation (DP1). Solutions of the DP1 are classified under criterion of their behavior while argument tends to infinity. The appropriate theorems of existence are proved.

B. M. Pimentel, J. L. Tomazelli

Starting from linear equations for the complex scalar field, the two- and three-point Green's functions are obtained in the infrared approximation. We show that the infrared singularity factorizes in the vertex function as in spinorial QED, reproducing in a straightforward way the result of lenghty perturbative calculations.

Daniel Cangemi, Gerald Dunne, Eric D'Hoker

We investigate the effective action of 2+1 dimensional charged spin 1/2 fermions and spin 0 bosons in the presence of a $U(1)$ gauge field. We evaluate terms in an expansion up to second order in derivatives of the field strength, but exactly in the mass parameter and in the magnitude of the nonvanishing constant field strength. We find that in a strong unif

Edward Witten

In 2 + 1 dimensions, in the presence of gravity, supersymmetry can ensure the vanishing of the cosmological constant without requiring the equality of bose and fermi masses.

Al. Zamolodchikov

Recently the scaling function of the dilute non-contractible self-avoiding 2D polymer loop on a cylinder was related to the Painleve III transcendent. Using the perturbation theory, the thermidynamic Bethe ansatz and numerical calculations we argue a similar relation for the contractible self-avoiding loop.

A. Candiello, K. Lechner, M. Tonin

The computation of $κ$-anomalies in the Green-Schwarz heterotic superstring sigma-model and the corresponding Wess-Zumino consistency condition constitute a powerful alternative approach for the derivation of manifestly supersymmetric string effective actions. With respect to the beta-function approach this technique presents the advantage that a result whic

Alexandros A. Kehagias, Patrick A. A. Meessen, George Zoupanos

We examine deformed Poincar\'e algebras containing the exact Lorentz algebra. We impose constraints which are necessary for defining field theories on these algebras and we present simple field theoretical examples. Of particular interest is a case that exhibits improved renormalization properties.

L. Guieu, V. Yu. Ovsienko

A symplectic structure on the space of nondegenerate and nonparametrized curves in a locally affine manifold is defined. We also consider several interesting spaces of nondegenerate projective curves endowed with Poisson structures. This construction connects the Virasoro algebra and the Gel'fand-Dikii bracket with the projective differential geometry.

G. Barnich, F. Brandt, M. Henneaux

The Wess-Zumino consistency condition for four-dimensional Einstein gravity is investigated in the space of local forms involving the fields, the ghosts, the antifields and their derivatives. Its general solution is constructed for all values of the form degree and of the ghost number. It is shown in particular that the antifields (= sources for the BRST var

P. Giacconi, F. Maltoni, R. Soldati

The axial anomaly is computed for Euclidean Dirac fermions on the plane. The dependence upon the self-adjoint extensions of the Dirac operator is investigated and its relevance concerning the second virial coefficient of the anyon gas is discussed.

Victor M. Villalba

In the present article we analyze the bound states of an electron in a Coulomb field when an Aharonov-Bohm field as well as a magnetic Dirac monopole are present. We solve, via separation of variables, the Schrödinger equation in spherical coordinates and we show how the Hydrogen energy spectrum depends on the Aharonov-Bohm and the magnetic monopole strength

M. Ikehara, N. Ishibashi, H. Kawai, T. Mogami

In this note, we review the recent developments in the string field theory in the temporal gauge. (Based on a talk presented by N.I. in the workshop {\it Quantum Field Theory, Integrable Models and Beyond}, Yukawa Institute for Theoretical Physics, Kyoto University, 14-18 February 1994.)

Mario Greco, Simona Rolli

Inclusive production of light mesons ($π^0$, $η$, $π^{\pm}$, $K^{\pm}$ ) at the Tevatron is considered in QCD to next-to-leading order in the formalism of fragmentation functions. We present various distributions of phenomenological interest, along with a new set of $K$ mesons fragmentation functions.

Isard Dunietz

Distinguishing the flavor of $B$ and $\overline B$ hadrons is critical in studies of CP-violation, $B^0 -\overline{B^0}$ mixing, and the underlying $b$-decay mechanisms. Methods of $b$ ``flavor tagging" are broadly divided into ``opposite $b$" tagging and self-tagging of the signal $b$ hadron. The former, while understood, has the perceived drawback

V. Barger, E. Mirkes, J. Ohnemus, R. J. N. Phillips

Further kinematical variables are suggested, in which to compare the putative leptonic $W$ plus 4-jet top quark signal with the QCD background. We show that the lepton rapidity asymmetry, the $p_T$-ranking of the tagged $b$-jet, the double-tag probability, the reconstructed $t+\bar t$ invariant mass, and the lepton energy in the parent top quark rest-frame,

kingman Cheung, Tzu Chiang Yuan

We compute model-independently the production rates and transverse momentum spectra for the $B_c$ mesons in various spin-orbital states ($n\,^1S_0$, $n\,^3S_1$, $n\,^1P_1$, and $n\,^3P_J\,(J=0,1,2)$ ) at hadron colliders via the direct fragmentation of the bottom antiquark and via the Altarelli-Parisi-induced gluon fragmentation. Since all the radially and o

Kingman Cheung

The perturbative QCD fragmentation functions can be applied phenomenologically as a model for charm and bottom quark fragmentation into heavy-light mesons. The predictions by this model on the observables $P_V$ and $\langle z \rangle$ for $D-D^*$ and $B-B^*$ systems are compared with experimental data.

T. Gehrmann, W. J. Stirling

We perform a global leading-order QCD fit to recent polarized structure function data in order to extract a consistent set of spin-dependent parton distributions. Assuming that there is no significant intrinsic polarization of the quark sea, the data are consistent with a modest amount of the proton's spin carried by the gluon, although the shape of the

S. A. Abel, S. Sarkar

We discuss the cosmology of string models with perturbative supersymmetry breaking at a scale of ${\cal O}$(TeV). Such models exhibit Kaluza-Klein like spectra and contain unstable massive gravitinos/gravitons. We find that considerations of primordial nucleosynthesis constrain the maximum temperature following inflation to be not much larger than the supers

V. V. Kiselev

The modification of the naive potential model of the heavy meson is considered on the basis of the single-time prescription for the quark-meson form factor and the covariant choice of the quatk relative momentum. The application of the model to the description of the semileptonic decays of the beauty meson allows one to determine the Isgur-Wise function slop

B. C. Allanach

Talk given at Frontiers in Particle Physics Conference, Cargese. In this paper, I provide some motivation for supersymmetric grand unified theories, briefly explain an extension of the standard model based on them and present a calculation performed using certain properties of some SUSY GUTs to constrain the available parameter space.

C. Bourrely, J. Soffer, Tai Tsun Wu

We show that the rising total photoproduction cross section recently observed at HERA is entirely consistant with the impact-picture in the theory of expanding protons which was proposed more than twenty years ago. More accurate data, which is expected to be forthcoming soon, will give this prediction a stringent test.

Fritz DeJongh

We review $B^+$ and $B^0$ mean lifetime measurements, including direct measurements and determination of the lifetime ratio via measurements of the ratio of branching ratios. We present world averages.

Ulvi Yurtsever

We describe an elementary proof that a manifold with the topology of the Politzer time machine does not admit a nonsingular, asymptotically flat Lorentz metric.

John M. Lee

This paper relates the spectrum of the scalar Laplacian of an asymptotically hyperbolic Einstein metric to the conformal geometry of its ``ideal boundary'' at infinity. It follows from work of R. Mazzeo that the essential spectrum of such a metric on an $(n+1)$-dimensional manifold is the ray $[n^2/4,\infty)$, with no embedded eigenvalues; however, i

John Cardy

We discuss how the statistical properties of the area and radius of gyration of single self-avoiding loops, and of Ising and percolation cluster boundaries, may be calculated using ideas of two-dimensional field theory. For cluster boundaries, we show that almost all loops have area $C\ln L+O(1)$, where $L$ is the size of the system, and $C$ is a calculable

Avinash Dhar, Porus Lakdawala, Gautam Mandal, Spenta R. Wadia

Wolfram has provided a qualitative classification of cellular automata(CA) rules according to which, there exits a class of CA rules (called Class 4) which exhibit complex pattern formation and long-lived dynamical activity (long transients). These properties of Class 4 CA's has led to the conjecture that Class 4 rules are Universal Turing machines i.e.

Masaki Oshikawa

We consider the Hall conductivity of two-dimensional non-interacting Bloch electrons when the magnetic flux per unit cell is a rational number $p/q$ where $p$ and $q$ are mutually coprime. We present a counter-example for the naive expectation that the Hall conductivity carried by a band is given by treating gap minima as Dirac fermions. Instead of the above

C. Micheletti, J. M. Yeomans

We study the ground state of a classical X-Y model with $p \ge 3$-fold spin anisotropy $D$ in a uniform external field, $H$. An interface is introduced into the system by a suitable choice of boundary conditions. For large $D$, as $H \to 0$, we prove using an expansion in $D^{-1}$ that the interface unbinds from the surface through an infinite series of laye

A. Belkasri, J. L. Richard

The spectrum of a single hole is calculated within the spin-hole model using a variational method. This calculation is done for any rotational invariant magnetic background. We have found that when the magnetic background changes from a disordered to a locally ordered state, the spectrum changes qualitatively. We have also found that the spin pattern around

A. Belkasri, J. L. Richard

In recent work of Monthoux and Pines~[1] and also in Rice et {\sl al.}'s work~[2], quasi-averages like $\langle c_{k \uparrow} c_{- k \downarrow} \rangle$ were considered even in the case of a dimension less or equal two. But it is well known from the old work of Hohenberg~[3] that these quasi-averages are zero at $T \not= 0$ in case of 1 and 2 dimension

Salman Habib, Henry E. Kandrup, M. Elaine Mahon

ABBREVIATED ABSTRACT: This paper summarises an investigation of the effects of weak friction and noise in time-independent, nonintegrable potentials which admit both regular and stochastic orbits. The aim is to understand the qualitative effects of internal and external irregularities associated, e.g., with discreteness effects or couplings to an external en

Sergio Campana, Luigi Stella

We calculate the response of a line emitted from a relativistic accretion disk to a continuum variation of the central illuminating source. This model might be relevant to the very broad and sometimes redshifted emission lines which have been observed at optical and X-ray energies in Active Galactic Nuclei and X-ray binaries. We consider separately the cases

F. P. Pijpers

It has been claimed that in stellar winds traversed by strong shocks the mechanism for driving the wind by sound wave pressure cannot operate because sound waves cannot propagate past the shocks. It is shown here that sound waves can propagate through shocks in one direction and that this is a sufficient condition for the sound wave pressure mechanism to wor

J. Ocariz, H. Rago

The exterior solution for an arbitrary charged, massive source, is studied as a static deviation from the Reissner-Nordstrøm metric. This is reduced to two coupled ordinary differential equations for the gravitational and electrostatic potential functions. The homogeneous equations are explicitly solved in the particular case $q^2=m^2$, obtaining a multipole

Peter R. Taylor, Eric Bylaska, John H. Weare, Ryoichi Kawai

Contrary to recent experimental evidence suggesting that the monocyclic ring is the most stable 20-atom carbon species, highly accurate calculations convincingly predict that the smallest fullerene, the dodecahedron C$_{20}$, has the lowest energy. A related corannulene-like bowl is nearly degenerate in energy to the fullerene. Thermodynamic considerations s

Michael R. Douglas

We use solvable two-dimensional gauge theories to illustrate the issues in relating large N gauge theory to string theory. We also give an introduction to recent mathematical work which allows constructing master fields for higher dimensional large N theories. We illustrate this with a new derivation of the Hopf equation governing the evolution of the spectr

Mesgun Sebhatu

A sine-Gordon solitary wave exchange NN potentials (SG SWEP) is presented as an example of a large class of realistic potentials with four or less parameters. SWEPs are derived from nonlinear quantum field theory developed by Burt. SG SWEPs resemble Reid SC potentials and they reproduce high quality phase shifts and deuteron parameters with only two paramete

Philippe Zaugg

We propose a contraction of the de Sitter quantum group leading to the quantum Poincare group in any dimensions. The method relies on the coaction of the de Sitter quantum group on a non--commutative space, and the deformation parameter $q$ is sent to one. The bicrossproduct structure of the quantum Poincaré group is exhibited and shown to be dual to the one

A. Brignole, F. Zwirner

We show how the spontaneous breaking of local N=1 supersymmetry and of the SU(2)xU(1) gauge symmetry can be simultaneously realized, with naturally vanishing tree-level vacuum energy, in superstring effective supergravities. Both the gravitino mass m_{3/2} and the electroweak scale m_Z are classically undetermined, and slide along moduli directions that incl

Lizeng Zhang

We investigate fractional quantum Hall effect at finite temperature using a fermion Chern-Simons field theoretical approach. In the absence of impurity scattering, the essential aspects of fractional quantum Hall effect, such as the quantization of Hall conductance, as well as quasi-particle charge and statistics are unrenormalized by thermal fluctuations. O

Fay Dowker, Adrian Kent

We describe some properties of consistent sets of histories in the Gell-Mann--Hartle formalism, and give an example to illustrate that one cannot recover the standard predictions, retrodictions and inferences of quasiclassical physics using the criterion of consistency alone.

Tsuyoshi Chawanya

A new type of asymptotic behavior in a game dynamics system is discovered. The system exhibits behavior which combines chaotic motion and attraction to heteroclinic cycles; the trajectory visits several unstable stationary states repeatedly with an irregular order, and the typical length of the stay near the steady states grows exponentially with the number

Olaf Stiller, Stefan Popp, Lorenz Kramer

Perturbation approaches developed so far for the dark soliton solutions of the (fully integrable) defocusing nonlinear Schroedinger equation cannot describe the dynamics resulting from dissipative perturbations of the Ginzburg-Landau type. Here spatially slowly decaying changes of the background wavenumber occur which requires the use of matching technics. I

Stefan Popp, Olaf Stiller, Igor Aranson, Lorenz Kramer

The cubic Complex Ginzburg-Landau Equation (CGLE) has a one parameter family of traveling localized source solutions. These so called 'Nozaki-Bekki holes' are (dynamically) stable in some parameter range, but always structually unstable: A perturbation of the equation in general leads to a (positive or negative) monotonic acceleration or an oscillati

Michael Hawrylycz, Victor Reiner

In this paper we show that the set of closure relations on a finite poset P forms a supersolvable lattice, as suggested by Rota. Furthermore this lattice is dually isomorphic to the lattice of closed sets in a convex geometry (in the sense of Edelman and Jamison). We also characterize the modular elements of this lattice and compute its characteristic polyno

Menachem Kojman, Saharon Shelah

We examine the existence of universal elements in classes of infinite abelian groups. The main method is using group invariants which are defined relative to club guessing sequences. We prove, for example: Theorem: For $n\ge 2$, there is a purely universal separable $p$-group in $\aleph_n$ if, and only if, $\cont\le \aleph_n$.

A. Kapustin, S. Skorik

We show that the the generalized Calogero-Moser model with boundary potential of the Pöschl-Teller type describes the non-relativistic limit of the quantum sine-Gordon model on a half-line with Dirichlet boundary condition.

Lynne H. Orr

This talk is an overview of prospects for measuring the top mass $m_t$ at present and future colliders. Methods for extracting $m_t$ appropriate to experiments at the Tevatron, Large Hadron Collider, and Next Linear Collider are discussed, with examples given for each. Sources of systematic uncertainties specific to each method and experiment are identified.