January 1998 arXiv papers — page 4

D. Nicolaides, A. A. Lisyansky

Within the framework of an exactly solvable model, which takes into account the interaction of fluctuating modes with equal and opposite momenta, we consider phase diagrams in systems with coupled scalar order parameters. We show that, in agreement with the renormalization group theory, the fluctuation interaction can split the continuous disorder-order tran

T. F. A. Muller, V. Anisimov, T. M. Rice, I. Dasgupta

We study the electronic structure of the ladder compounds (SrCa)CuO 14-24-41 and SrCuO 123. LDA calculations for both give similar Cu 3d-bands near the Fermi energy. The hopping parameters estimated by fitting LDA energy bands show a strong anisotropy between the t_perp t_par intra-ladder hopping and small inter-ladder hopping. A downfolding method shows tha

C. Bergemann, A. W. Tyler, A. P. Mackenzie, J. R. Cooper

Piezolever torque magnetometry has been used to measure the magnetization of superconducting Tl2Ba2CuO6. Three crystals with different levels of oxygen overdoping were investigated in magnetic fields up to 10 Tesla. In all cases, the magnetization above the irreversibility line was found to depart from the behaviour M ~ ln(Hc2/H) of a simple London-like vort

D. Pini, G. Stell, N. B. Wilding

A thermodynamically self-consistent Ornstein-Zernike approximation (SCOZA) is applied to a fluid of spherical particles with a pair potential given by a hard-core repulsion and a Yukawa attractive tail $w(r)=-\exp [-z(r-1)]/r$. This potential allows one to take advantage of the known analytical properties of the solution to the Ornstein-Zernike equation for

Philip W. Anderson

This paper was given at the Santa Barbara workshop on non-Fermi Liquids, June 1996. It was delayed in posting by a clerical error.

V. Meregalli, S. Y. Savrasov

We report density functional calculations based on local density approximation (LDA) of the properties of doped barium bismuthates. Using linear-response approach developed in the framework of the linear muffin-tin-orbital method the phonon spectrum of the Ba$_{0.6}$K$_{0.4}$BiO$% _3$ system is calculated and is compared with the results of the neutron diffr

Sebastian Heinz, Christopher S. Reynolds, Mitchell C. Begelman

We present a simple model for an evolving radio galaxy, as it expands into the hot, X-ray emitting interstellar medium (ISM) of its host galaxy or similarly into the hot intracluster medium (ICM) of its host cluster. We solve the governing equations numerically on a grid of model parameters in order to present simple analytical tools for X-ray observations o

J. G. Kirk, F. M. Rieger, A. Mastichiadis

We model the acceleration of electrons at a shock front in a relativistic blazar jet and compute the radiation they emit in a post-shock region which contains a homogeneous magnetic field. The full space, time and momentum dependence of the electron distribution is used in this calculation. It is shown that the "homogeneous" synchrotron model is reco

A. A. Pamyatnykh, W. A. Dziembowski, G. Handler, H. Pikall

Frequencies of 13 oscillation modes in the star XX Pyxidis (CD-24 7599) are accurately measured but for none of the modes the spherical harmonic degree l is known. We present results of an attempt to construct the model whose low-l mode frequencies reproduce possibly close the observations. Models are constrained by the mean photometric and spectroscopic dat

E. Battaner, E. Florido, J. Jimenez-Vicente

The truncation of stellar discs is not abrupt but characterized by a continuous distancing from the exponential profile. There exists a truncation curve, $t(r)$, ending at a truncation radius, $r_t$. We present here a theoretical model in which it is assumed that the magnetic hypothesis explaining the flat rotation curve also explains the truncation. Once st

Neven Bilic, Faustin Munyaneza, Raoul D. Viollier

Heavy-neutrino (or neutralino) stars are studied using the general relativistic equations of hydrostatic equilibrium and the relativistic equation of state for degenerate fermionic matter. The Tolman-Oppenheimer-Volkoff equations are then generalized to include a system of degenerate neutrino and neutralino matter that is gravitationally coupled. The propert

L. Ciotti, G. Giampieri

We investigate the motion, near the equilibrium configurations, of an initially spinless rigid body subject to an external tidal field. Two cases are considered: when the center of mass of the body is at rest at the equilibrium point of the field generated by a generic mass distribution, and when it is placed on a circular orbit subject to a spherically symm

Hale Bradt, Robert Shirey, Alan Levine

Data accumulated with RXTE during the active state of Cir X-1 as well as during an unusually long transition from the active state to the quiescent state are reported. The long decline from the active state allowed the source characteristics to be studied systematically as a function of intensity. The following results are presented: (1) spectral fits during

P. N. Arendt,, J. A. Eilek

Rotation distorts the vacuum magnetic field of a pulsar from that of a simple dipole. The effect is particularly strong close to the light cylinder, but also affects the field close to the stellar surface. We find the shape and locus of the field lines which just close at the light cylinder. Their footpoints define the pulsar polar cap. We find this cap is a

Rupert Croft, David Weinberg, Neal Katz, Lars Hernquist

A convincing physical picture for the Lyman-alpha forest has emerged from simulations and related semi-analytic studies of structure formation models. Observations can be be used in the context of this picture to study cosmology using the structure of the forest. With the availability of well motivated predictions, not only has it become possible to test mod

Rupert Croft, Gavin Dalton, George Efstathiou

(abridged) We estimate the cluster-galaxy cross-correlation function (Xi_cg), from the APM galaxy and galaxy cluster surveys, both in real space from the inversion of projected statistics and in redshift space using the galaxy and cluster redshift samples. The amplitude of Xi_cg is found to be almost independent of cluster richness. At large separations, r >

Jiannis Pachos

The Coulomb branch of the potential between two static colored sources is calculated for the Yang-Mills theory using the electric Schroedinger representation.

Jiannis Pachos

Here is presented a detailed work on the (1+1) dimensional SU(N) Yang-Mills theory with static sources. By studying the structure of the SU(N) group and of the Gauss' law we construct in the electric representation the appropriate wave functionals, which are simultaneously eigenstates of the Gauss' operator and of the Hamiltonian. The Fourier transfo

Alexander Polishchuk, Eric Zaslow

We describe an isomorphism of categories conjectured by Kontsevich. If $M$ and $\widetilde{M}$ are mirror pairs then the conjectural equivalence is between the derived category of coherent sheaves on $M$ and a suitable version of Fukaya's category of Lagrangian submanifolds on $\widetilde{M}.$ We prove this equivalence when $M$ is an elliptic curve and $

P. M. Cowdall, P. K. Townsend

Domain wall and electrovac solutions of gauged N=4 D=4 supergravity, with gauge group SU(2) or SU(2)xSU(2), are interpreted as supersymmetric Kaluza-Klein vacua of N=1 D=10 supergravity. These vacua are shown to be the near-horizon geometries of certain intersecting brane solutions.

R. A. J. van Elburg, K. Schoutens

We propose a quasi-particle formulation of effective edge theories for the fractional quantum Hall effect. For the edge of a Laughlin state with filling fraction ν=1/m, our fundamental quasi-particles are edge electrons of charge -e and edge quasi-holes of charge +e/m. These quasi-particles satisfy exclusion statistics in the sense of Haldane. We exploit alg

Eduard Looijenga

We define for every affine Coxeter graph a certain factor group of the associated Artin group and prove that some of these groups appear as orbifold fundamental groups of moduli spaces. Examples are the moduli space of nonsingular cubic algebraic surfaces and the universal nonhyperelliptic smooth genus three curve. We use this to obtain a simple presentation

Shaun Cole, Steve Hatton, David H. Weinberg, Carlos S. Frenk

We present a comprehensive set of mock 2dF and SDSS galaxy redshift surveys constructed from a set of large, high-resolution cosmological N-body simulations. The radial selection functions and geometrical limits of the catalogues mimic those of the genuine surveys. The catalogues span a wide range of cosmologies, including both open and flat universes. In al

J. Böckenhauer, D. E. Evans

We analyze the induction and restriction of sectors for nets of subfactors defined by Longo and Rehren. Picking a local subfactor we derive a formula which specifies the structure of the induced sectors in terms of the original DHR sectors of the smaller net and canonical endomorphisms. We also obtain a reciprocity formula for induction and restriction of se

B. Friman

The properties of vector mesons in nuclear matter are discussed. Results for the momentum dependence of the $ρ$-meson self energy in matter due to $ρN$ interactions are presented, and consequences for the production rate of $e^+e^-$ pairs in hot and dense matter are discussed. I also examine the constraints imposed by elementary processes on the widths of $ρ

R. Casalbuoni

In this paper we study the compactification conditions of the M theory on D-dimensional noncommutative tori. The main tool used for this analysis is the algebra A(Z^D) of the projective representations of the abelian group Z^D. We exhibit the explicit solutions in the space of the multiplication algebra of A(Z^D), that is the algebra generated by right and l

J. E. Amaro, T. W. Donnelly

A theoretical description of nucleon knockout reactions initiated by polarized electron scattering from polarized nuclei is presented. Explicit expressions for the complete set of reduced response functions (independent of the polarization angle) that can be experimentally obtained assuming plane waves for the electron are given in a general multipole expans

A. G. Izergin, A. G. Pronko, N. I. Abarenkova

We consider the one-dimensional Hubbard model with the infinitely strong repulsion. The two-point dynamical temperature correlation functions are calculated. They are represented as Fredholm determinants of linear integrable integral operators.

Masaaki Nakamura

The spin-gap phase of the one-dimensional t-J-J' model is studied by the level-crossing of the singlet and the triplet excitation spectra. The phase boundary obtained between the Tomonaga-Luttinger and the spin-gap phases is remarkably consistent with the analytical results at the $J,J'\to 0$ and the low-density limits discussed by Ogata et al. The s

Konrad Banaszek

We present a complete statistical analysis of quantum optical measurement schemes based on photodetection. Statistical distributions of quantum observables determined from a finite number of experimental runs are characterized with the help of the generating function, which we derive using the exact statistical description of raw experimental outcomes. We us

Gi-Chol Cho

We study impacts on new physics search from the rare decay $K^+ \to π^+ ν\barν$. In a certain class of new physics models, the extra contributions to FCNC processes can be parametrized by its ratio to the standard model (SM) contribution with the common CKM factors. The ratio $R_1$ has been used in the analysis of $\xd$ and $ε_K$ parameters. In the above cla

Unal Goktas, Willy Hereman

Methods for the computation of invariants and symmetries of nonlinear evolution, wave, and lattice equations are presented. The algorithms are based on dimensional analysis, and can be implemented in any symbolic language, such as Mathematica. Invariants and symmetries are shown for several well-known equations. Our Mathematica package allows one to automati

Antoine Suarez

A real two-particle experiment is proposed in which one of the particles undergoes two successive impacts on beam-splitters. It is shown that the standard quantum mechanical superposition principle implies the possibility of influences acting backward in time ("retrocausation"), in striking contrast with the principle of causality. It is argued that

Karl Svozil

Review of the First International Conference on Unconventional Models of Computation UMC'98, Auckland, New Zealand, 5-9 January, 1998

R. Bijker, A. Leviatan

Interacting boson models provide an elegant and powerful method to describe collective excitations of complex systems by introducing a set of effective degrees of freedom. We review the interacting boson model of nuclear structure and discuss a recent extension to the nucleon and its excited states.

Tomohide Terasoma

Let C_1 and C_2 be two degenerations of genus g curves. We prove that if two degenerations defines the same conjugacy classes in the mapping class group, they are equivalent under analytic deformations.

Boris Shoikhet

In the present paper we generalize the lifting formulas from [Sh] and obtain the formula for the (2n+2l-1)-cocycle on the LIe algebra of differential operators on a n-dimensional space for arbitrary n and l.

Peter W. Michor, Tudor Ratiu

We consider a natural Riemannian metric on the infinite dimensional manifold of all embeddings from a manifold into a Riemannian manifold, and derive its geodesic equation in the case $\Emb(\Bbb R,\Bbb R)$ which turns out to be Burgers' equation. Then we derive the geodesic equation, the curvature, and the Jacobi equation of a right invariant Riemannian

Toshinori Oaku, Nobuki Takayama

We give an algorithm to compute the following cohomology groups on $U = \C^n \setminus V(f)$ for any non-zero polynomial $f \in \Q[x_1, ..., x_n]$; 1. $H^k(U, \C_U)$, $\C_U$ is the constant sheaf on $U$ with stalk $\C$. 2. $H^k(U, \Vsc)$, $\Vsc$ is a locally constant sheaf of rank 1 on $U$. We also give partial results on computation of cohomology groups on

T. Pause, T. Heinzl

We discuss the construction of the physical configuration space for Yang-Mills quantum mechanics and Yang-Mills theory on a cylinder. We explicitly eliminate the redundant degrees of freedom by either fixing a gauge or introducing gauge invariant variables. Both methods are shown to be equivalent if the Gribov problem is treated properly and the necessary bo

Odd Magne Ogreid, Per Osland

We present results for some infinite series appearing in Feynman diagram calculations, many of which are similar to the Euler series. These include both one-dimensional and two-dimensional series. Most of these series can be expressed in terms of zeta(2), zeta(3), the Catalan constant G and Cl{2}(pi/3) where Cl{2}(theta) is Clausen's function.

Emanuel Katz, Lisa Randall, Shufang Su

We discuss the violation of the equality of the gauge coupling and gaugino coupling in the presence of soft supersymmetry breaking. Although this is a hard supersymmetry breaking effect, there are finite contributions to this difference which can be determined as a function of the soft supersymmetry breaking masses. The largest sources of this difference are

V. Elias, A. H. Fariborz, Fang Shi, T. G. Steele

We investigate lowest-lying scalar meson properties predicted from QCD Laplace sum rules based upon isovector and isoscalar non-strange $\bar{q}q$ currents. The hadronic content of these sum rules incorporates deviations from the narrow resonance approximation anticipated from physical resonance widths. The field theoretical content of these sum rules incorp

Boris Kopeliovich

We compare a few types of high energy reactions which seem to be practical for polarimetry at RHIC. Coulomb-nuclear interference (CNI) in pp elastic scattering leads to a nearly energy-independent left-right asymmetry A_N(t) at small t. The systematical uncertainty of this method is evaluated to be ~ 10%. The CNI in proton-nucleus elastic scattering is predi

Rajan Gupta

After a brief introduction to lattice QCD, I summarize the results for the light quark masses and the bag parameters $B_K$, $B_6^{1/2}$, and $B_8^{3/2}$. The implications of these results for the standard model estimates of CP violation parameters $ε$ and $ε'/ε$ are also discussed.

Galit Eyal, Yosef Nir

We construct phenomenologically viable supersymmetric models where CP is an approximate symmetry. The full high energy theory has exact CP and horizontal symmetries that are spontaneously broken with a naturally induced hierarchy of scales, $Λ_{CP}\llΛ_H$. Consequently, the effective low energy theory, that is the supersymmetric Standard Model, has CP broken

V. Barger, M. S. Berger, T. Han

We analyze the prospects at a muon collider for measuring chargino masses in the $μ^+μ^-\to \tildeχ^+\tildeχ^-$ process in the threshold region. We find that for the lighter chargino of a mass $100-200$ GeV, a measurement better than $50-300$ MeV should be possible with 50 fb$^{-1}$ integrated luminosity. The accuracy obtained here is better than with other

Burkhard Klaus, Claude Roiesnel

We describe the results of a systematic high-statistics Monte-Carlo study of finite-size effects at the phase transition of compact U(1) lattice gauge theory with Wilson action on a hypercubic lattice with periodic boundary conditions. We find unambiguously that the critical exponent nu is lattice-size dependent for volumes ranging from 4^4 to 12^4. Asymptot

Milind V. Diwan

We have designed a new experiment (E923) at the BNL-AGS to search for the T-violating polarization of the muon normal to the decay plane of the KMU3 decay. The experiment aims to search for T-violation beyond the Standard Model; such a search is motivated by the need for a stronger CP violation source to account for the baryon asymmetry of the Universe. The

Amos Ori

We construct a new class of plane-symmetric solutions possessing a curvature singularity which is null and weak, like the spacetime singularity at the Cauchy horizon of spinning (or charged) black holes. We then analyse the stability of this singularity using a rigorous non-perturbative method. We find that within the framework of (linearly-polarized) plane-

M. A. Clayton, L. Demopoulos, J. Legare

We consider the dynamical stability of a class of static, spherically-symmetric solutions of the nonsymmetric gravitational theory. We numerically reproduce the Wyman solution and generate new solutions for the case where the theory has a nontrivial fundamental length scale μ^{-1}. By considering spherically symmetric perturbations of these solutions we show

Yasuo Ezawa, Masahiko Kiminami, Masahiro Kajihara, Jiro Soda

Following the method of Buchbinder and Lyahovich, we carry out a canonical formalism for a higher-curvature gravity in which the Lagrangian density ${\cal L}$ is given in terms of a function of the salar curvature $R$ as ${\cal L}=\sqrt{-\det g_{μν}}f(R)$. The local Hamiltonian is obtained by a canonical transformation which interchanges a pair of the genera

D. R. C. Dominguez, D. Bolle

A complete self-control mechanism is proposed in the dynamics of neural networks through the introduction of a time-dependent threshold, determined in function of both the noise and the pattern activity in the network. Especially for sparsely coded models this mechanism is shown to considerably improve the storage capacity, the basins of attraction and the m

V. Yu. Irkhin, A. A. Katanin

The systems exhibiting quantum phase transitions (QPT) are investigated within the Ising model in the transverse field and Heisenberg model with easy-plane single-site anisotropy. Near QPT a correspondence between parameters of these models and of quantum phi^4 model is established. A scaling analysis is performed for the ground-state properties. The influen

V. Yu. Irkhin, Yu. P. Irkhin

The calculation of magnetic anisotropy constants is performed beyond the point charge model for a continuous charge density distribution of screening conduction electrons. An important role of the non-uniform electron density, in particular, of the Friedel oscillations, in the formation of crystal field is demonstrated. Such effects can modify strongly the e

Philip W. Anderson

This paper was submitted to Phys. Rev. Lett in an earlier version. This version was published in my book. It was delayed in posting by a clerical error.

Philip W. Anderson

This paper has been submitted to Science. It summarizes the experimental evidence for (and against) the interlayer theory. It was delayed in posting by clerical error.

Katsuji Sakai, Yasushi Yokoya, Yoshiko Oi Nakamura

Two-dimensional Eliashberg equations have been solved by use of a mixed interaction with $s$- and $d$-channels. It is discussed what kind of pairing symmetry of the superconducting state can be realized when the channel mixing parameters and the band-filling are varied. By changing the mixing parameters and varying the chemical potential $μ$ between zero- an

N. B. Wilding, F. Schmid, P. Nieleba

Using Monte-Carlo simulation and mean field calculations, we study the liquid-vapour phase diagram of a square well binary fluid mixture as a function of a parameter $δ$ measuring the relative strength of interactions between particles of dissimilar and similar species. The results reveal a rich variety of liquid-vapour coexistence behaviour as $δ$ is tuned.

Carsten Wengel, Uwe Claus T"auber

Structural and transport properties of interacting localized flux lines in the Bose glass phase of irradiated superconductors are studied by means of Monte Carlo simulations near the matching field B_Phi, where the densities of vortices and columnar defects are equal. For a completely random columnar pin distribution in the xy-plane transverse to the magneti

H. J. Luo, L. Schuelke, B. Zheng

Using Monte Carlo simulations, we systematically investigate the non-equilibrium dynamics of the chiral degree of freedom in the two-dimensional fully frustrated XY model. The critical initial increase of the staggered chiral magnetization is observed. By means of the short-time dynamics approach, we estimate the second order phase transition temperature $T_

Robert Eder

We present an approximation scheme for the calculation of the norm and energy of the nearest-neighbor-RVB state for the Heisenberg antiferromagnet on the 2D square lattice. The approximation leads to a systematic expansion of norm and energy, with the `expansion parameter' being the maximum length of loops taken into account in the calculation of energy

Jose F. Quesada

This paper presents a new context-free parsing algorithm based on a bidirectional strictly horizontal strategy which incorporates strong top-down predictions (derivations and adjacencies). From a functional point of view, the parser is able to propagate syntactic constraints reducing parsing ambiguity. From a computational perspective, the algorithm includes

Antal van den Bosch, Ton Weijters, Walter Daelemans

In leading morpho-phonological theories and state-of-the-art text-to-speech systems it is assumed that word pronunciation cannot be learned or performed without in-between analyses at several abstraction levels (e.g., morphological, graphemic, phonemic, syllabic, and stress levels). We challenge this assumption for the case of English word pronunciation. Usi

Antal van den Bosch, Walter Daelemans

Memory-based learning, keeping full memory of learning material, appears a viable approach to learning NLP tasks, and is often superior in generalisation accuracy to eager learning approaches that abstract from learning material. Here we investigate three partial memory-based learning approaches which remove from memory specific task instance types estimated

Fausto Borgonovi

Classical and quantum properties of a discontinuous perturbed twist map are investigated. Different classical diffusive regimes, quasilinear and slow respectively, are observed. The regime of slow classical diffusion gives rise to two distinct quantal regimes, one marked by dynamical localization, the other by quasi-integrable localization due to classical C

D. J. Axon, A. Marconi, A. Capetti, F. D. Macchetto

We have obtained HST FOC f/48 long-slit spectroscopy of the inner 4" of the Narrow Line Region of NGC 1068 between 3500-5400A with a spectral resolution of 1.78A/pixel. At a spatial scale of 0.0287" per pixel these data provide an order of magnitude improvement in resolution over previous ground based spectra and allow us to trace the interaction bet

Jean-Pierre Luminet

Our understanding of space and time is probed to its depths by black holes. These objects, which appear as a natural consequence of general relativity, provide a powerful analytical tool able to examine macroscopic and microscopic properties of the universe. This introductory article presents in a pictorial way the basic concepts of black hole's theory,

A. H. Rots, K. Jahoda, D. J. Macomb, N. Kawai

Observations with the Rossi X-ray Timing Explorer and the Jodrell Bank, Parkes, and Green Bank telescopes have enabled us to determine the time delay between radio and X-ray pulses in the two isolated pulsars B1821-24 and B1509-58. For the former we find that the narrow X-ray and radio pulse components are close to being coincident in time, with the radio pe

R. A. E. Fosbury, R. Morganti, W. Wilson, R. D. Ekers

We present radio observations of the radio galaxy PKS 2152-699 obtained with the Australia Telescope Compact Array (ATCA). The much higher resolution and s/n of the new radio maps reveals the presence of a bright radio component about 10 arcsec NE of the nucleus. This lies close to the highly ionized cloud previously studied in the optical and here shown in

P. Vauterin, H. Dejonghe

A quasi self-consistent model for a barred structure in the central regions of our Galaxy is used to calculate the signature of such a triaxial structure on the kinematical properties of star samples. We argue that, due to the presence of a velocity dispersion, such effects are much harder to detect in the stellar component than in the gas. It might be almos

H. Lesch, A. Jessner, M. Kramer, Th. Kunzl

We consider the widespread hypothesis that coherent curvature radiation is responsible for the radio emission of pulsars. The comparison of energy conservation and the published data and luminosities explicitely proves that coherent curvature radiation cannot be the source for the radio emission of pulsars for frequencies below a few GHz. At higher frequenci

Peter P. Eggleton, Ludmila G. Kiseleva, Piet Hut

We derive from first principles equations governing (a) the quadrupole tensor of a star distorted by both rotation and the presence of a companion in a possibly eccentric orbit, (b) a functional form for the dissipative force of tidal friction, based on the concept that the rate of energy loss from a time-dependent tide should be a positive-definite function

F. Daigne, R. Mochkovitch

We construct models for gamma-ray bursts where the emission comes from internal shocks in a relativistic wind with a highly non uniform distribution of the Lorentz factor. We follow the evolution of the wind using a very simplified approach where a large number of layers interact by direct collisions but where all pressure waves have been suppressed. We supp

Cedric Ledoux, Patrick Petitjean, Jacqueline Bergeron

We report on high spectral resolution observations of five damped Lyman alpha systems whose line velocity profiles and abundances are analyzed. By combining these data with information from the literature, we study the kinematics of the low and high ionization phases of damped systems and discuss the possibility that part of the motions is due to rotation.

H. Saio, A. Gautschy

The theoretical period-luminosity relation for Cepheids was deduced from stellar evolution and pulsation computations. Questions concerning the metallicity dependence of the relation as well as the constancy of the pulsation `constant' Q in the instablility strip were addressed. We found no significant metallicity dependence of either the slope or of the

Paul P. van der Werf

The diagnostic use and detectability of luminous fine structure lines from high redshift galaxies is reviewed in the light of results from COBE concerning the Milky Way and from ISO on low redshift galaxies. At the highest luminosities (L>10^{12}\Lsun) the [CII] 158 micron line is somewhat less luminous with respect to the bolometric luminosity than for lowe

N. David Mermin

I explore whether it is possible to make sense of the quantum mechanical description of physical reality by taking the proper subject of physics to be correlation and only correlation, and by separating the problem of understanding the nature of quantum mechanics from the hard problem of understanding the nature of objective probability in individual systems

Anastasia Volovich

We study Witten's proposal that a domain wall exists in M-theory fivebrane version of QCD (MQCD) and that it can be represented as a supersymmetric three-cycle in G_2 holonomy manifold. It is shown that equations defining the U(1) invariant domain wall for SU(2) group can be reduced to the Monge-Ampere equation. A proof of an algebraic formula of Kapluno

P. Bouwknegt, K. Pilch

We discuss some aspects of the deformed W-algebras W_{q,t}[g]. In particular, we derive an explicit formula for the Kac determinant, and discuss the center when t^2 is a primitive k-th root of unity. The relation of the structure of W_{q,t}[g] to the representation ring of the quantum affine algebra U_q(\hat g), as discovered recently by Frenkel and Reshetik

Y. Sota, T. Kobayashi, K. Maeda, T. Kurokawa

We apply the renormalization group (RG) method to examine the observable scaling properties in Newtonian cosmology. The original scaling properties of the equations of motion in our model are modified for averaged observables on constant time slices. In the RG flow diagram, we find three robust fixed points: Einstein-de Sitter, Milne and Quiescent fixed poin

Ron Rubin, Nathan Salwen

We present here a complete description of the quantization of the baker's map. The method we use is quite different from that used in Balazs and Voros [BV] and Saraceno [S]. We use as the quantum algebra of observables the operators generated by {exp(2 Pi ix),exp (2 Pi ip)} and construct a unitary propagator such that as Planck's constant tends to ze

Itzhak Tserruya

The paper reviews all experimental results on dileptons with invariant mass m < 3 GeV/c$^2$ and real photons obtained from the CERN SPS heavy-ion program with S and Pb beams, together with the current attempts to understand them.

Alon E. Faraggi

An important issue in supersymmetry phenomenology is the suppression of squarks contributions to Flavor Changing Neutral Currents (FCNC). Recently it was noted that in some free fermionic three generation models the anomalous U(1) is family universal. It was further shown that if the $D$--term of the $U(1)_A$ is the dominant source of supersymmetry breaking,

Liu Lianshou, Chen Qinghua, Hu Yuan

The formation of quark-gluon plasma (QGP) in relativistic heavy ion collision, is expected to be accompanied by a background of ordinary collision events without phase transition. In this short note an algorithm is proposed to select the QGP candidate events from the whole event sample. This algorithm is based on a simple geometrical consideration together w

P. Hernandez

We consider a Wilson-Dirac operator with improved chiral properties. We show that, for arbitrarily rough gauge fields, it satisfies the index theorem if we identify the zero modes with the small real eigenvalues of the fermion operator and use the geometrical definition of topological charge. This is also confirmed in a numerical study of the quenched Schwin

The OPAL Collaboration, K. Ackerstaff et al

Photonic events with large missing energy have been observed in e+e- collisions at centre-of-mass energies of 130, 136, 161 and 172 GeV using the OPAL detector at LEP. Results are presented based on search topologies designed to select events with a single photon and missing transverse energy or events with a pair of acoplanar photons. In both search topolog

D. M. Stamper-Kurn, H. -J. Miesner, S. Inouye, M. R. Andrews

Collective excitations of a dilute Bose gas were probed above and below the Bose-Einstein condensation temperature. The temperature dependencies of the frequency and damping rates of condensate oscillations indicate significant interactions between the condensate and the thermal cloud. Hydrodynamic oscillations of the thermal cloud were observed, constitutin

J. M. G. Vilar, R. V. Solé, J. M. Rubí

We have analyzed the interplay between noise and periodic modulations in a mean field model of a neural excitable medium. To this purpose, we have considered two types of modulations; namely, variations of the resistance and oscillations of the threshold. In both cases, stochastic resonance is present, irrespective of if the system is monostable or bistable.

J. M. G. Vilar, R. V. Solé

We have analyzed the interplay between noise and periodic modulations in a classical Lotka-Volterra model of two-species competition. We have found that the consideration of noise changes drastically the behavior of the system and leads to new situations which have no counterpart in the deterministic case. Among others, noise is responsible for temporal osci

J. M. G. Vilar, J. M. Rubí

We have analyzed the interplay between noise and periodic spatial modulations in bistable systems outside equilibrium and found that noise is able to increase the spatial order of the system, giving rise to periodic patterns which otherwise look random. This new phenomenon, which may be viewed as the spatial counterpart of stochastic resonance, then shows a

Francis J. Alexander, Gregory L. Eyink

Shape-dependent thermodynamics and non-local hydrodynamics are argued to occur in dissipative steady states of driven diffusive systems. These predictions are confirmed by numerical simulations. Unlike power-law correlations, these phenomena cannot be explained by a hypothesis of ``criticality&#39;&#39;. Instead, they require the effective Hamiltonian of the

M. Araki, H. Ozeki, S. Saito

The pure rotational transitions of the protonated hydrogen cyanide ion, HCNH+, and its isotopic species, HCND+ and DCND+, were measured in the 107 - 482 GHz region with a source modulated microwave spectrometer. The ions were generated in the cell with a magnetically confined dc-glow discharge of HCN and/or DCN. The rotational constant B0 and the centrifugal

Guido Caldarelli, Paul G. Higgs, Alan J. McKane

We introduce the Webworld model, which links together the ecological modelling of food web structure with the evolutionary modelling of speciation and extinction events. The model describes dynamics of ecological communities on an evolutionary timescale. Species are defined as sets of characteristic features, and these features are used to determine interact

Mordecai-Mark Mac Low, Andrea Ferrara

We model the effects of repeated supernova explosions from starbursts in dwarf galaxies on the interstellar medium of these galaxies, taking into account the gravitational potential of their dominant dark matter haloes. We explore supernova rates from one every 30,000 yr to one every 3 million yr, equivalent to steady mechanical luminosities of L=0.1-10 x 10

A. M. Glukhov, A. S. Pokhila, I. M. Dmitrenko, A. E. Kolinko

An oscillatory magnetic field dependence of the DC voltage is observed when a low-frequency current flows through superconducting Sn-Ge thin-film composites near the percolation threshold. The paper also studies the experimental realisations of temporal voltage fluctuations in these films. Both the structure of the voltage oscillations against the magnetic f

Wayne Hu

The next generation of cosmic microwave background (CMB) experiments, galaxy surveys, and high-redshift observations can potentially determine the nature of the dark matter observationally. With this in mind, we introduce a phenomenological model for a generalized dark matter (GDM) component and discuss its effect on large-scale structure and CMB anisotropie

H. W. Diehl

The critical behaviour of three-dimensional semi-infinite Ising ferromagnets at planar surfaces with (i) random surface-bond disorder or (ii) a terrace of monatomic height and macroscopic size is considered. The Griffiths-Kelly-Sherman correlation inequalities are shown to impose constraints on the order-parameter density at the surface, which yield upper an

Eizou Umezawa

We study constraints among coupling constants of the standard model obtained in the noncommutative geometry (NCG) method. First, we analyze the evolution of the Higgs boson mass under the renormalization group by adopting the idea of \'Alvarez et al. For this analysis we derive two certain constraints by modifying Connes's way of constructing the standard mo

Nicolau C. Saldanha, Carlos Tomei

We consider tilings of quadriculated regions by dominoes and of triangulated regions by lozenges. We present an overview of results concerning tileability, enumeration and the structure of the space of tilings.