July 1997 arXiv papers — page 9

R. Kaminski, L. Lesniak, B. Loiseau

New solutions on the scalar -- isoscalar $ππ$ phase shifts are analysed together with previous $K\bar{K}$ results using a separable potential model of three coupled channels ($ππ$, $K\bar{K}$ and an effective $2π2π$ system). Model parameters are fitted to two sets of solutions obtained in a recent analysis of the CERN-Cracow-Munich measurements of the $π^- p

Aleandro Nisati, Silvano Petrarca, Giorgio Salvini

The possible detection of massive quasi-stable exotic particles at the high luminosity hadronic colliders is discussed. In the coming ten years the LHC, now under preparation, has the best opportunity to observe them at the TeV scale. The present design of the ATLAS detector,that has been almost irreversibly decided, may turn out to be flexible enough to all

J. Kwiecinski, C. A. M. Lewis, A. D. Martin

We use the BFKL equation to calculate the rate of deep inelastic scattering events containing two forward jets (adjacent to the proton remnants) at HERA. We compare the production of two forward jets with that of only one forward jet (the "Mueller" process). We obtain a stable prediction for this two to one jet ratio, which may serve as a measure of

V. Lubicz

In this talk I review some recent results from lattice QCD calculations which aim to a more accurate determination of the Standard Model parameters in the quark sector. After a review of our current knowledge of these parameters, I present lattice results for the strange, charm and bottom quark masses, the CKM matrix element $V_{ub}$ and the complex CKM phas

M. Heyssler, W. J. Stirling

The process $eq \to eq +γ$ exhibits radiation zeros, i.e. configurations of the final-state particles for which the scattering amplitude vanishes. We study these zeros for both $e^+u$ and $e^+d$ scattering. The latter exhibits a type of zero which to our knowledge has not previously been identified. The observability of radiation zeros at HERA is discussed.

S. M. Bilenky, C. Giunti, W. Grimus

The mixing of three and four massive neutrinos is considered. It is shown that the neutrino oscillation data are not compatible with a hierarchy of couplings in the three-neutrino case. In the case of four neutrinos, a hierarchy of masses is not favored by the data. Only two schemes with two pairs of close masses separated by a gap of the order of 1 eV can a

E. Gabrielli, V. A. Ilyin, B. Mele

The one-loop process e,gamma->e,h for intermediate Higgs masses is considered. Exact cross sections for unpolarized and longitudinally polarized beams are computed and found to be more than two orders of magnitude larger than the rates for the crossed process e,e->gamma,h, in the energy range \sqrt{s}=(0.5-2) TeV. We show that, apart from being competitive w

M. Beuthe, G. Lopez Castro, J. Pestieau

Quantum field theory provides a consistent framework to deal with unstable particles. We present here an approach based on field theory to describe the production and decay of unstable $K^0-\bar{K^0}$ and $B^0-\bar{B^0}$ mixed systems. The formalism is applied to compute the time evolution amplitudes of $K^0$ and $\bar{K^0}$ studied in DAPHNE and CPLEAR expe

Matthias Neubert

We present a detailed study of non-leptonic two-body decays of B mesons based on a generalized factorization hypothesis. We discuss the structure of non-factorizable corrections and present arguments in favour of a simple phenomenological description of their effects. We discuss tests of the factorization hypothesis and show how it may be used to determine u

Sean Fleming, Thomas Mehen

We study leptoproduction of $J/ψ$ at large $Q^2$ within the nonrelativistic QCD (NRQCD) factorization formalism. The cross section is dominated by color-octet terms that are of order $α_s$. The color-singlet term, which is of order $α^2_s$, is shown to be a small contribution to the total cross section. We also calculate the tree diagrams for color-octet pro

M. Göckeler, R. Horsley, H. Perlt, P. Rakow

We compute the hadron mass spectrum, the quark masses and the meson decay constants in quenched lattice QCD with non-perturbatively $O(a)$ improved Wilson fermions. The calculations are done for two values of the coupling constant, $β= 6.0$ and 6.2, and the results are compared with the predictions of ordinary Wilson fermions. We find that the improved actio

S. Aoki

We review our attempt at understanding the phase structure of lattice QCD with the Wilson fermion formulation at finite temperature, based on a spontaneous breakdown of parity-flavor symmetry. Numerical results demonstrating explicitly the spontaneous breakdown of parity-flavor symmetry beyond the critical line at both zero and finite temperatures are report

Y. Iwasaki

We investigate the phase structure of lattice QCD for general number of flavors $N_F$. Based on numerical results combined with the result of the perturbation theory we propose the following picture: When $N_F \ge 17$, there is only a trivial fixed point and therefore the theory in the continuum limit is trivial. On the other hand, when $16 \ge N_F \ge 7$, t

F. Igloi, D. Karevski, H. Rieger

According to the Harris-Luck criterion the relevance of a fluctuating interaction at the critical point is connected to the value of the fluctuation exponent omega. Here we consider different types of relevant fluctuations in the quantum Ising chain and investigate the universality class of the models. At the critical point the random and aperiodic systems b

James Badro, Philippe Gillet, Paul F. McMillan, Alain Polian

Combined X-ray absorption spectroscopy (XAS) and X-ray diffraction (XRD) experiments have been carried out on GaAsO4 (berlinite structure) at high pressure and room temperature. XAS measurements indicate four-fold to six-fold coordination changes for both cations. The two local coordination transformations occur at different rates but appear to be coupled. A

Parthapratim Biswas, Arnab Majumdar, Anita Mehta, J. K. Bhattacharjee

The well-known Edwards-Wilkinson equation with a flow term added exhibits a smoothing fixed point in addition to the normal EW fixed point. Based on this, we present a model of sandpiles involving a coupling between fixed and mobile grains, which then shows the smoothing behaviour that would be expected to obtain after avalanche propagation.

James Badro, Jean-Paul Itié, Alain Polian, Philippe Gillet

EXAFS spectroscopy experiments have been carried out on quartz-like GaAsO4 and AlAsO4 at high pressure and room temperature. It has been shown that these materials exhibit two structural phase transitions; the first transition to a high pressure crystalline form occurs at 9 GPa and is reversible upon decompression, whereas the second transition occurs at hig

M. E. Gruner, P. Entel

We perform constant pressure Monte Carlo simulations of a spin-analogous model which describes coupled spatial and magnetic degrees of freedom on an fcc lattice. Our calculations qualitatively reproduce magnetovolume effects observed in some rare earth manganese compounds, especially in the anti-Invar material YMn2. These are a sudden collapse of the magneti

Tomaz Prosen

Numerical evidence is given for non-ergodic (non-mixing) behavior, exhibiting ideal transport, of a simple non-integrable many-body quantum system in the thermodynamic limit, namely kicked $t-V$ model of spinless fermions on a ring. However, for sufficiently large kick parameters $t$ and $V$ we recover quantum ergodicity, and normal transport, which can be d

Dongsu Bak, Sang Pyo Kim, Sung Ku Kim, Kwang-Sup Soh

Using the Carlip's method we have derived the boundary action for the fermion Chern-Simons theory of quantum Hall effects on a planar region with a boundary. We have computed both the bulk and edge responses of currents to the external electric field. From this we obtain the well-known anomaly relation and the boundary Hall current without introducing an

J. Oswald, G. Span

We investigate the high magnetic field regime of wide quantum wells (WQW) for the case of a many valley host semiconductor. The complete system is described within a modified Landauer-Buettiker formalism and we demonstrate that a parallel contribution of two electron systems in different valleys of the band structure can lead to an edge channel related non-l

J. Oswald, G. Span, A. Homer, G. Heigl

We present magneto transport experiments of quasi 3D PbTe wide quantum wells. A plateau-like structure in the Hall resistance is observed, which corresponds to the Shubnikov de Haas oscillations in the same manner as known from the quantum Hall effect. The onsets of plateaux in Rxy do not correspond to 2D filling factors but coincide with the occupation of 3

J. Oswald, G. Heigl, G. Span, A. Homer

The results of non-local experiments in different contact configurations are discussed in terms of a non-local behaviour of the contact arms. It is shown that the observed reproducible fluctuations can be understood to result from fluctuations of a non-local bulk current in the contact arms. The fluctuations are explained by edge channel backscattering becau

J. Oswald, G. Heigl, G. Span, A. Homer

We show that for the case of a many valley host semiconductor an edge channel (EC) related non-local behaviour can persist also in the 3D-regime where the quantum Hall effect (QHE) is already quenched. We demonstrate that the QHE is replaced by conductance fluctuations due to EC backscattering in the contact arms, which leads to a fluctuating current redistr

Andre Kempe

This paper describes the conversion of a Hidden Markov Model into a sequential transducer that closely approximates the behavior of the stochastic model. This transformation is especially advantageous for part-of-speech tagging because the resulting transducer can be composed with other transducers that encode correction rules for the most frequent tagging e

R. Aurich, M. Taglieber

The rate of quantum ergodicity is studied for three strongly chaotic (Anosov) systems. The quantal eigenfunctions on a compact Riemannian surface of genus g=2 and of two triangular billiards on a surface of constant negative curvature are investigated. One of the triangular billiards belongs to the class of arithmetic systems. There are no peculiarities obse

Victor S. L'vov, Itamar Procaccia

We propose a scheme for the calculation from the NS equations of the scaling exponents $ζ_n$ of the $n$th order correlators in fully developed hydrodynamic turbulence. The scheme is nonperturbative and constructed to respect the fundamental rescaling symmetry of the Euler equation. It constitutes an infinite hierarchy of coupled equations that are obeyed ide

A. C. Marti, F. Sagues, J. M. Sancho

We study front propagation in stirred media using a simplified modelization of the turbulent flow. Computer simulations reveal the existence of the two limiting propagation modes observed in recent experiments with liquid phase isothermal reactions. These two modes respectively correspond to a wrinkled although sharp propagating interface and to a broadened

Keith A. Olive

Following a brief introduction to early Universe cosmology, the current of status of big bang nucleosynthesis is reviewed and the concordance between theory and observation is examined in detail. The abundances of He4 and Li7 determine the value of the baryon-to-photon ratio, $η$ to be relatively low, $η\approx 1.8 \times 10^{-10}$, and agrees with some rece

P. Stein, H. Jerjen, M. Federspiel

Based on the photometric survey of the inner region of the Centaurus cluster (Jerjen & Dressler 1997a) we measured redshifts for a deep, surface brightness limited sample of galaxies using the MEFOS multifibre spectrograph at the ESO 3.6m telescope. With the new data set radial velocities for 120 centrally located cluster members become available which is eq

Tristan Guillot, Daniel Gautier, William B. Hubbard

Using the helium abundance measured by Galileo in the atmosphere of Jupiter and interior models reproducing the observed external gravitational field, we derive new constraints on the composition and structure of the planet. We conclude that, except for helium which must be more abundant in the metallic interior than in the molecular envelope, Jupiter could

David M. Goldberg, Michael A. Strauss

We estimate the degree to which the baryon density, $Ω_{b}$, can be determined from the galaxy power spectrum measured from large scale galaxy redshift surveys, and in particular, the Sloan Digital Sky Survey. A high baryon density will cause wiggles to appear in the power spectrum, which should be observable at the current epoch. We assume linear theory on

Jocelyn Tomkin, Bengt Edvardsson, David L. Lambert, Bengt Gustafsson

We have made new abundance determinations for a sample of NaMgAl stars. These stars, which are a subgroup of the nearby metal-rich field F and G disk dwarfs, were first identified by Edvardsson et al. (1993) on the basis of their apparent enrichment in Na, Mg and Al relative to other elements. The discovery of a planetary companion to the nearby solar type s

Martin D. Weinberg

Gravitational amplification of Poisson noise in stellar systems increases the dipole noise power by roughly a factor of six and the quadrupole noise by 50% for a King model profile. The dipole noise is amplified by a factor of fifteen for the core-free Hernquist model. The predictions are computed using the dressed-particle formalism of Rostoker & Rosenbluth

P. Magdziarz, R. Moderski, G. M. Madejski

We analyze average gamma-ray variability statistics for the sample of blazars detected by CGRO/EGRET. We re-reduce all the available EGRET observations and analyze light curves by Monte Carlo modeling of the variability statistics including observational artifacts. We show that the observed variability behavior is dominated by the distribution of measurement

Yoshiaki Taniguchi

Recently Umemura, Fukue, & Mineshige (1997) proposed the radiative avalanche fueling to active galactic nuclei; gas accretion is driven by radiation drag exerted by stellar radiation from circumnuclear starburst regions. This mechanism is also interesting in terms of starburst-AGN connections. We therefore present observational tests for the radiative avalan

T. Yoshikoshi, T. Kifune, S. A. Dazeley, P. G. Edwards

We have observed the Vela pulsar region at TeV energies using the 3.8 m imaging Cherenkov telescope near Woomera, South Australia between January 1993 and March 1995. Evidence of an unpulsed gamma-ray signal has been detected at the 5.8 sigma level. The detected gamma-ray flux is (2.9 +/- 0.5 +/- 0.4) x 10^-12 photons cm^-2 sec^-1 above 2.5 +/- 1.0 TeV and t

P. Magdziarz, O. M. Blaes, A. A. Zdziarski, W. N. Johnson

We analyze a composite broad-band optical/UV/Xgamma-ray spectrum of the Seyfert 1 galaxy NGC 5548. The spectrum consists of an average of simultaneous optical/IUE/Ginga observations accompanied by ROSAT and GRO/OSSE data from non-simultaneous observations. We show that the broad-band continuum is inconsistent with simple disk models extending to the soft X-r

Emmanuel Davoust

The Pic du Midi Observatory, situated at an altitude of 2890 meters, was always very hard to reach, and living there was difficult. Its history is a lesson in courage. It is also a lesson in creativity, because astronomers took advantage of the remarkable quality of the site in many ways, to study planets and, later, to prepare for the Apollo missions. They

Max Pettini, Charles C. Steidel, Mark Dickinson, Melinda Kellogg

We review the spectral properties of the population of star forming galaxies at z = 3 discovered using a colour selection technique which targets the Lyman discontinuity at 912 Angstroms. The UV luminosity of the typical z = 3 galaxy exceeds by more than one order of magnitude that of the most luminous starbursts in the nearby universe, although the maximum

V. G. Gurzadyan, A. Melkonian, K. Oganessyan

The existence of period-doubling bifurcations is shown for the Konishi-Kaneko map. The value of the control parameter $k_{\infty}$ corresponding to the transition to the chaotic phase is estimated, along with the Feigenbaum universal number. This type of facts can be crucial in diagnosis of chaos in stellar dynamics.

V. G. Gurzadyan, S. Rauzy

The problem of reconstruction of the 3D velocities of clusters of galaxies from the redshift distribution of galaxies of the cluster is formulated. Though numerical simulations show the impossibility of direct use of Ambartsumian's formula derived for the stellar systems because of the small number of objects in the clusters, an additional physical assum

T. Yamada, I. Tanaka, A. Aragón-Salamanca, T. Kodama

We have obtained new deep optical and near-infrared images of the field of the radio-loud quasar 1335.8+2834 at $z=1.086$ where an excess in the surface number density of galaxies was reported by Hutchings et al. [AJ, 106, 1324] from optical data. We found a significant clustering of objects with very red optical-near infrared colors, $4 \lesssim R-K \lesssi

Constantin Teleman

This note outlines the Borel-Weil-Bott theory for (arbitrary-genus) flag varieties of loop groups, following ideas of G. Segal. Recent revivalist interest in the "WZW fusion rules" suggests that my original (CMP 1995) treatment of the matter is not all that well understood, so a brief account thereof has been recycled along with the more recent resul

Stephen R. Sharpe

I discuss the properties of pions in ``partially quenched'' theories, i.e. those in which the valence and sea quark masses, $m_V$ and $m_S$, are different. I point out that for lattice fermions which retain some chiral symmetry on the lattice, e.g. staggered fermions, the leading order prediction of the chiral expansion is that the mass of the pion d

James Badro, Philippe Gillet, Jean-Louis Barrat

It has recently been shown that amorphization and melting of ice were intimately linked. In this letter, we infer from molecular dynamics simulations on the SiO2 system that the extension of the quartz melting line in the metastable pressure-temperature domain is the pressure-induced amorphization line. It seems therefore likely that melting is the physical

Jordi Miralda-Escude, Martin J. Rees

If the universe was reionized by O and B stars in an early population of galaxies, the associated supernovae should have enriched the universe to a mean metallicity $\bar Z = 10^{-5} (1+ n_{rec})$, where $n_{rec}$ is the mean number of times that each baryon recombined during the reionization era. This is consistent with recent observations of the metallicit

Donald Spector

Using the theory of supersymmetric anyons, I extend the definition of the Witten index to 2+1 dimensions so as to accommodate the existence of anyon spin and statistics. I then demonstrate that, although in general the index receives irrational and complex contributions from anyonic states, the overall index is always integral, and I consider some of the imp

Dmitriy Rumynin

We continue the study of Hopf-Galois extensions with central invariants for a finite dimensional Hopf algebra. We concentrate on the geometrical side on the subject. We understand how to localize Hopf-Galois extensions and to paste them from local datum.

M. A. Clayton

Einstein's general relativity with both metric and vielbein treated as independent fields is considered, demonstrating the existence of a consistent variational principle and deriving a Hamiltonian formalism that treats the spatial metric and spatial vielbein as canonical coordinates. This results in a Hamiltonian in standard form that consists of Hamilt

Dmitriy Rumynin

We study Hopf-Galois extensions with central invariants for a finite dimensional Hopf algebra. We collect general facts about them and discuss some examples arising in the study of restricted Lie algebras and quantum groups at roots of unity. Our focus is on representation theory and its special feature in this situation, restriction of the central character

G. Carraro, Y. K. Ng, L. Portinari

A comparison is made between the age-metallicity relation obtained from four different types of studies: F and G stars in the Solar Neighbourhood, analysis of open clusters, galactic structure studies with the stellar population synthesis technique, and chemical evolution models. Metallicities of open clusters are corrected for the effects of the radial grad

M. A. Clayton

The time-dependent, spherically symmetric, Wyman sector of the Unified Field Theory is shown to be equivalent to a self-gravitating scalar field with a positive-definite, repulsive self-interaction potential. A homothetic symmetry is imposed on the fundamental tensor, and the resulting autonomous system is numerically integrated. Near the critical point (bet

V. A. Novikov, L. B. Okun, M. I. Vysotsky, A. N. Rozanov

A simple way of deriving and analyzing electroweak radiative corrections to the $Z$ boson decays is presented in the framework of the Standard Model. This paper is an updated and revised version of a plenary talk given at the Second Sakharov Conference; Lebedev Physical Institute, Moscow, May 20-24, 1996.

L. Jaede, H. V. von Geramb

The one solitary boson exchange potential (OSBEP) is used to evaluate observables of NN elastic scattering below pion threshold. In this approach, we use a nonlinear model of self-interacting mesons as a substitution for the commonly used phenomenological form factors. NN data support an empirical scaling law between the pion and other meson fields, which su

S. L. Dubovsky, D. S. Gorbunov, S. V. Troitsky

We consider the possibility of unification of the Supersymmetric Standard Model gauge groups with those of the dynamical supersymmetry breaking (DSB) sector in theories with gauge mediated supersymmetry breaking. We find constraints on the DSB gauge group beta function that come from unification of the gauge coupling constants of the two sectors. These const

Yasuhiro Matsushita, Martin P. Gelfand, Chikara Ishii

The ground state properties and phase diagram of the bilayer square-lattice Heisenberg model are studied in a broad parameter space of intralayer exchange couplings, assuming an antiferromagnetic coupling between constituent layers. In the classical limit, the model exhibits three phases: two of these are ordered phases specified by the ordering wave vectors

A. Damascelli, D. van der Marel, F. Parmigiani, G. Dhalenne

We investigated the far- and mid-infrared reflectivity (20-6000 wavenumber) of several pure and doped CuGeO3 single crystals. The b-axis and c-axis optical response is presented for different temperatures between 4 K and 300 K. Moreover, a full group theoretical analysis of the lattice vibrational modes of CuGeO3 in the high temperature undistorted phase as

F. Courbin, C. Lidman, P. Magain

We report on deep IR imaging of the double quasar HE 1104-1805. A new image deconvolution technique has been applied to the data in order to optimally combine the numerous frames obtained. The resulting J and K' images allow us to detect and study the lensing galaxy between the two lensed QSO images. The near infrared images not only confirm the lensed n

Ingve Simonsen, Alex Hansen, Olav Magnar Nes

We propose a new method for (global) Hurst exponent determination based on wavelets. Using this method, we analyze synthetic data with predefined Hurst exponents, fracture surfaces and data from economy. The results are compared with those obtained from Fourier spectral analysis. When many samples are available, the wavelet and Fourier methods are comparable

Fl. Stancu, S. Pepin, L. Ya. Glozman

It is shown that the short-range part of the Goldstone boson exchange interaction between the constituent quarks which explains baryon spectroscopy and the short-range repulsion in the NN system induces a strong short-range repulsion in the flavour-singlet state of the $ΛΛ$ system with $J^P=0^+$. It then suggests that a deeply bound H-particle should not exi

Shin'ichi Nojiri, Sergei D. Odintsov

We discuss the one-loop effective potential and static (large $d$) potential for toroidal D-brane described by DBI-action in constant magnetic and in constant electric fields. Explicit calculation is done for membrane case ($p=2$) for both types of external fields and in case of static potential for an arbitrary $p$. In the case of one-loop potential it is f

K. Tsushima, K. Saito, J. Haidenbauer, A. W. Thomas

The quark-meson coupling (QMC) model, which has been successfully used to describe the properties of both infinite nuclear matter and finite nuclei, is applied to a systematic study of $\Lambda, \Sigma$ and $\Xi$ hypernuclei. Assumptions made in the present study are, (i) the (self-consistent) exchanged scalar, and vector, mesons couple only to the u and d q

Koichi Yamawaki

We discuss the spontaneous symmetry breaking (SSB) on the light front (LF) in view of the zero mode. We first demonstrate impossibility to remove the zero mode in the continuum LF theory by two examples: The Lorentz invariance forbids even a free theory on the LF and the trivial LF vacuum is lost in the SSB phase, both due to the zero mode as the accumulatin

Nathalie Deruelle, David Langlois, Jean-Philippe Uzan

We consider a perfectly homogeneous and isotropic universe which undergoes a sudden phase transition. If the transition produces topological defects, which we assume, perturbations in the geometry and the cosmic fluid also suddenly appear. We apply the standard general relativistic junction conditions to match the pre- and post- transition eras and thus set

Cristopher Moore, James P. Crutchfield

To study quantum computation, it might be helpful to generalize structures from language and automata theory to the quantum case. To that end, we propose quantum versions of finite-state and push-down automata, and regular and context-free grammars. We find analogs of several classical theorems, including pumping lemmas, closure properties, rational and alge

Lu-Ming Duan, Guang-Can Guo

A simple scheme is proposed for observing the ghost interference and diffraction. The signal and the idler beams are produced by a beam splitter with the incident light being in a thermal state. A slit is inserted into the signal beam. We derive rigorously that interference-diffraction patterns can be observed in the first-order correlation by scanning the p

Valeri V. Dvoeglazov

We briefly review recent achievements in the theory of neutral particles (the Majorana-McLennan-Case-Ahluwalia construct for self/anti-self charge conjugate states for j=1/2 and j=1 cases). Among new results we present a theoretical construct in which a fermion and an antifermion have the same intrinsic parity; discuss phase transformations and find relation

Valeri V. Dvoeglazov

In the first part of this paper we review several formalisms which give alternative ways for describing the light. They are: the formalism `baroque' and the Majorana-Oppenheimer form of electrodynamics, the Sachs' theory of Elementary Matter, the Dirac-Fock-Podol'sky model, its development by Staruszkiewicz, the Evans-Vigier ${\bf B}^{(3)}$ field

Ute Ebert, Wim van Saarloos

We analyze ``pulled'' or ``linearly marginally stable'' fronts propagating into unstable states. While ``pushed'' fronts into meta- and unstable states relax exponentially, pulled fronts relax algebraically, and simultaneously the standard derivation of effective interface equations breaks down. We calculate all universal relaxation t

D. Menze

Statistically improved data of total cross sections and of angular distributions for differential cross sections and hyperon recoil polarizations of the reactions γp --> K^+ Λand γp --> K^+ Σ^0 have been collected with the SAPHIR detector at photon energies between threshold and 2.0 GeV. Here total cross section data up to 1.5 GeV are presented. The opposite

V. R. Manfredi, L. Salasnich

The Toda criterion of the Gaussian curvature is applied to calculate analytically the transition energy from regular to chaotic motion in a schematic model describing the interaction between collective dipole and quadrupole modes in atomic nuclei.

Jonathan David Farley

A brief introduction to the theory of ordered sets and lattice theory is given. To illustrate proof techniques in the theory of ordered sets, a generalization of a conjecture of Daykin and Daykin, concerning the structure of posets that can be partitioned into chains in a ``strong'' way, is proved. The result is motivated by a conjecture of Graham&#3

Martin Goldstern

Lukasiewicz logic is a "fuzzy" logic in which truth value can be real numbers in the unit interval. There are connectives for min, max, addition and complement (1-x). The "value" of a closed formula in a fuzzy (relational model) is defined in the natural way. A formula is called valid iff it has value 1 in every fuzzy model. We show that the

Martin Goldstern, Menachem Kojman

A ``k-rule&#34; is a sequence A=((A_n,B_n):n<omega) of pairwise disjoint sets B_n, each of cardinality at most k, where A_n is a subset of B_n. A set X of natural numbers (a ``real&#39;&#39;) follows a rule A if for infinitely many n we have that the intersection of X with B_n is exactly A_n. There are obvious cardinal invariants resulting from this definiti

Martin Goldstern, Saharon Shelah

If L is an order polynomially complete lattice, (that is: every monotone function from L^n to L is induced by a lattice-theoretic polynomial) then the cardinality of L is a strongly inaccessible cardinal. In particular, the existence of such lattices is not provable in ZFC, nor from ZFC+GCH. Although the problem originates in algebra, the proof is purely set

Martin Goldstern, Saharon Shelah

It is consistent that there is a partial order (P,<) of size aleph_1 such that every monotone (unary) function from P to P is first order definable in (P,<). The partial order is constructed in an extension obtained by finite support iteration of Cohen forcing. The main points is that (1) all monotone functions from P to P will (essentially) have countable r

Martin Goldstern, Saharon Shelah

Let &#34;ex&#34; be the cardinality of the smallest independent family of subsets of omega (independent means that all nontrivial Boolean combinations are infinite) which cannot be extended to a homogeneous independent family. &#34;Homogeneous&#34; means that every finite partial map (points to points, sets to sets) that is compatible with the family is indu

J. A. Minahan, D. Nemeschansky, N. P. Warner

We consider the BPS states of the $E_8$ non-critical string wound around one of the circles of a toroidal compactification to four dimensions. These states are indexed by their momenta and winding numbers. We find explicit expressions, $G_n$, for the momentum partition functions for the states with winding number $n$. The $G_n$ are given in terms of modular

Julie D. Blum, Keith R. Dienes

We extend strong/weak coupling duality to string theories without spacetime supersymmetry, and focus on the case of the unique ten-dimensional, nonsupersymmetric, tachyon-free $SO(16)\times SO(16)$ heterotic string. We construct a tachyon-free heterotic string model that interpolates smoothly between this string and the ten-dimensional supersymmetric $SO(32)

F. Antonuccio, H. C. Pauli, S. Tsujimaru

We consider the 1+1 dimensional supersymmetric matrix field theory obtained from a dimensional reduction of ten dimensional ${\cal N} = 1$ super Yang-Mills, which is a matrix model candidate for non-perturbative Type IIA string theory. The gauge group here is U($N$), where $N$ is sent to infinity. We adopt light-cone coordinates to parametrize the string wor

Moulay Brahim Sedra

Using the harmonic superspace techniques in D=2 N=4, we present an explicit derivation of a new hyper-Kahler metric associated to the Toda like self interaction $H ^{4+}(ω, u)= (\frac{ξ^{++}}λ)^{2}\exp(2λω)$. Some important features are also discussed.

A. D. Mitov, M. N. Stoilov, D. Ts. Stoyanov

We consider a model of quantum field theory with higher derivatives for a spinor field with quartic selfinteraction. With the help of the Bethe-Salpeter equation we study the problem of the two particle bound states in the &#34;chain&#34; approximation. The existence of a scalar bound state is established.

H. P. Nilles, M. Olechowski, M. Yamaguchi

We investigate gaugino condensation in the framework of the strongly coupled heterotic $E_8 \times E_8$ string (M--theory). Supersymmetry is broken in a hidden sector and gravitational interactions induce soft breaking parameters in the observable sector. The resulting soft masses are of order of the gravitino mass. The situation is similar to that in the we

Robert Bluhm, Alan Kostelecky, Neil Russell

A theoretical framework is introduced that describes possible CPT-violating effects in the context of quantum electrodynamics. Experiments comparing the anomalous magnetic moments of the electron and the positron can place tight limits on CPT violation. The conventional figure of merit adopted in these experiments, involving the difference between the corres

M. A. Braun, C. Pajares, J. Ranft

In most of the models of hadronic collisions the number of exchanged colour strings grows with energy and atomic numbers of the projectile and target. At high string densities interaction between them should melt them into the quark-gluon plasma state. It is shown that under certain assumptions about the the string interaction, a phase transition to the quar

R. Engel, D. Yu. Ivanov, R. Kirschner, L. Szymanowski

We calculate the cross section of diffractive charge-parity C=+1 neutral meson production in virtual photon proton collision at high energies. Due to the opposite C-parities of photon and meson M (M = eta_C, pi^0, a_2) this process probes the t-channel C=-1 odderon exchange which is described here as noninteracting three-gluon exchange. Estimates for the cro

Hans-Christian Pauli

The canonical front form Hamiltonian for non-Abelian SU(N) gauge theory in 3+1 dimensions is mapped non-perturbatively on an effective Hamiltonian which acts only in the Fock space of a quark and an antiquark. Emphasis is put on dealing with the many-body aspects of gauge field theory, and it is shown explicitly how the higher Fock-space amplitudes can be re

A. Corsetti, R. M. Godbole, G. Pancheri

We discuss predictions for the total inelastic gamma-gamma cross-section and their model dependence on the input parameters. We compare results from a simple extension of the Regge Pomeron exchange model as well as predictions from the eikonalized mini-jet model with recent LEP data.

S. M. Bilenky, C. Giunti, W. Grimus

We discuss what information about the neutrino mass spectrum and the elements of the neutrino mixing matrix can be inferred from the results of neutrino oscillation experiments. The cases of three and four massive neutrinos are considered. It is shown that the general characteristics of the neutrino mixing matrix are quite different from those of the quark m

T. Kon, T. Matsushita, T. Kobayashi

We investigate a production process $e^+p \to \st X \to \sb W^+ X$ at HERA, where we consider a decay mode $\sb \to \barν_e d$ of the sbottom in the framework of an R-parity breaking supersymmetric standard model. Both processes of the stop production $e^+ d \to \st$ and the sbottom decay $\sb \to \barν_e d$ are originated from an R-parity breaking superpote

H. G. Ballesteros, L. A. Fernandez, V. Martin-Mayor, A. Munoz Sudupe

Using finite-size scaling techniques, we study the critical properties of the site-diluted Ising model in four dimensions. We carry out a high statistics Monte Carlo simulation for several values of the dilution. The results support the perturbative scenario: there is only the Ising fixed point with large logarithmic scaling corrections. We obtain, using the

M. A. Clayton

A discussion of relativistic quantum-geometric mechanics on phase space and its generalisation to the propagation of free, massive, quantum-geometric scalar fields on curved spacetimes is given. It is shown that in an arbitrary coordinate system and frame of reference in a flat spacetime, the resulting propagator is necessarily the same as derived in the sta

V. M. Manuilov, A. S. Mishchenko

We prove that for matrix algebras $M_n$ there exists a monomorphism $(\prod_n M_n/\oplus_n M_n)\otimes C(S^1) \to {\cal Q} $ into the Calkin algebra which induces an isomorphism of the $K_1$-groups. As a consequence we show that every vector bundle over a classifying space $Bπ$ which can be obtained from an asymptotic representation of a discrete group $π$ c

Muriel Ney-Nifle

We present a finite size scaling analysis of Monte Carlo simulation results on a four dimensional Ising spin glass. We study chaos with both coupling and temperature perturbations, and find the same chaos exponent in each case. Chaos is investigated both at the critical temperature and below where it seems to be more efficient (larger exponent). Dimension fo

Ivar Martin, Philip Phillips

We present here a simple qualitative model that interpolates between the high and low temperature properties of quasi-1D conductors. At high temperatures we argue that transport is governed by inelastic scattering whereas at low temperatures the conductance decays exponentially with the electron dephasing length. The crossover between these regimes occurs at

Robert M. Ziff, Steven R. Finch, Victor S. Adamchik

Monte-Carlo simulations on a variety of 2d percolating systems at criticality suggest that the excess number of clusters in finite systems over the bulk value of nc is a universal quantity, dependent upon the system shape but independent of the lattice and percolation type. Values of nc are found to high accuracy, and for bond percolation confirm the theoret

A. Zheludev

$R_2BaNiO_5$ ($R=$ rare earth) quasi-1-D antiferromagnets are structurally equivalent to the well-studied 1-D S=1 Haldane-gap compound Y_2BaNiO_5. Unlike the Y-nickelate though, these materials undergo 3-D magnetic ordering at finite temperatures. Recent inelastic neutron scattering studies of Pr_2BaNiO_5 and (Nd_{x}Y_{1-x})_2BaNiO_5 revealed purely 1-dimens

A. Zheludev, S. Maslov, G. Shirane, Y. Sasago

The magnetic structure of Ba_2CuGe_2O_7 is investigated by neutron diffraction in magnetic fields applied along several directions in the $(a,b)$ plane of the crystal. In relatively weak fields, $H\lesssim 0.5$~T, the propagation vector of the spin-spiral rotates to form a finite angle with the field direction. This angle depends on the orientation of $H$ it

Torsten Henning, H. Kliem, A. Weyers, W. Bauhofer

The resistivity vs. temperature relation in bulk ceramic HTSC under self-field conditions as well as in weak external magnetic fields is modelled by local Lorentz force induced fluxon motion with temperature dependent pinning. A pinning force density and two viscous drag coefficients in intergrain and intragrain regions, respectively, can be used as characte