December 1995 arXiv papers — page 9

B. Eynard, C. Kristjansen

For $n\in [-2,2]$ the $O(n)$ model on a random lattice has critical points to which a scaling behaviour characteristic of 2D gravity interacting with conformal matter fields with $c\in [-\infty,1]$ can be associated. Previously we have written down an exact solution of this model valid at any point in the coupling constant space and for any $n$. The solution

Zouhair Tamsamani

In this paper we first give a simplicial approach to the definition of a non strict $n$-category that we call an $n$-nerve following the idea that a category could be interpreted as a simplicial set, and we prove that our construction generalises the case of the usual non strict 2-category. Next we give a simplicial definition of a non strict $n$-groupoid. T

J. G. Brankov, V. B. Priezzhev, A. Schadschneider, M. Schreckenberg

We propose a bridge between the theory of exactly solvable models and the investigation of traffic flow. By choosing the activities in an apropriate way the dimer configurations of the Kasteleyn model on a hexagonal lattice can be interpreted as space-time trajectories of cars. This then allows for a calculation of the flow-density relationship (fundamental

Michael C. Birse, Boris Krippa

We evaluate the $πN$ coupling constant using a QCD sum rule based on the pion-to-vacuum matrix element of the correlator of two interpolating nucleon fields. The part of the correlator with Dirac structure $k\llap/γ_5$ is used, keeping all terms up to dimension 5 in the OPE and including continuum contributions on the phenomenological side. The ratio of this

J. Shiraishi, Y. Morita, M. Kohmoto

A variant of the one-dimensional $t$-$J$ model with anisotropic spin interaction and broken parity is studied by the nested algebraic Bethe-ansatz method. The gapless charge excitations and the gapful spin excitations are obtained. It is shown that the singlet-superconducting correlation dominates in the low-density region by applying the finite-size scaling

Toshiya Kawai

We study a standard-embedding $N=2$ heterotic string compactification on $K3\times T^2$ with a Wilson line turned on and perform a world-sheet calculation of string threshold correction. The result can be expressed in terms of the quantities appearing in the two-loop calculation of bosonic string. We also comment and speculate on the relevance of our result

G. Bhattacharya, Pat Kalyniak, K. A. Peterson

We investigate the pair production of charged heavy leptons via photon-induced processes at the proposed CERN Large Hadron Collider (LHC). Using effective photon and Z approximations, rates are given for $L^+L^-$ production due to $γγ$ fusion and $Z γ$ fusion for the cases of inelastic, elastic and semi-elastic $pp$ collisions. These are compared with the co

J. D. Finley, III

Detailed mappings between zero-curvture equations for prolongation structures of nonlinear pde's and Estabrook-Wahlquist algorithms for same are given. The differences are exemplified by studies of the sine-Gordon equation. An example where the prolongation structure must be infinite-dimensional is given by the Robinson-Trautman equation, where the minim

B. Enriquez, V. N. Rubtsov

We define a 1-parameter family of $r$-matrices on the loop algebra of $sl_{2}$, defining compatible Poisson structures on the associated loop group, which degenerate into the rational and trigonometric structures, and study the Manin triples associated to them.

G. S. Danilov

The modular transformations of the $(1|1)$ complex supermanifolds in the like-Schottky modular parameterization are discussed. It is shown that these "supermodular" transformations depend on the spinor structure of the supermanifold by terms proportional to the odd modular parameters. The above terms are calculated in the explicit form. They are urge

Chaiho Rim

We present new family of exact analytic solutions for three anyons in a harmonic potential (or in free space) in terms of generalized harmonics on $S^3$, which supplement the known solutions. The new solutions satisfy the hard-core condition when $α={1\over 3},1$ ($α$ being the statistical parameter) but otherwise, have finite non-vanishing two-particle coll

Norma Mankoč Borštnik

In a space of $d $ Grassmann coordinates two types of generators of Lorentz transformations can be defined, one of spinorial and the other of vectorial character. Both kinds of operators appear as linear operators in Grassmann space, definig the fundamental and the adjoint representations of the group $ SO(1,d$$-$$1) $, respectively. The eigenvalues of commu

Xiaofeng Guo, Jianwei Qiu

We calculate the nuclear dependence of direct photon production in hadron-nucleus collisions. In terms of a multiple scattering picture, we factorize the cross section for direct photon production into calculable short-distance partonic parts times multiparton correlation functions in nuclei. We present the hadron-nucleus cross section as $A^α$ times the had

Ketino Aladashvili, Murman Margvelashvili

The flavour dependence of the mixed quark-gluon condensate is studied through the analysis of correlators of the hybrid current $a_μ=g\bar sγ_ργ_5 G_{ρμ}d$. The flavour symmetry breaking for this type of condensates is found to be less than that for the quark condensates. For the ratio of strange to nonstrange condensates we obtain \mbox{$R=0.95\pm 0.15$}. F

S. Dawson

We discuss the potential for making precision measurements of $M_W$ and $M_T$ at a muon collider and the motivations for each measurement. A comparison is made with the precision measurements expected at other facilities. The measurement of the top quark decay width is also discussed.

Jisuke Kubo, Myriam Mondragon, Shigeyuki Shoda, George Zoupanos

We study supersymmetric unified models with three fermion generations based on the gauge group $SO(10)$ and require Gauge-Yukawa Unification, i.e., a renormalization group invariant functional relationship among the gauge and Yukawa couplings of the third generation in the symmetric phase. In the case of the minimal model, we find that the predicted values f

H. Kawai, N. Tsuda, T. Yukawa

The complex structure of a surface generated by the two-dimensional dynamical triangulation(DT) is determined by measuring the resistivity of the surface. It is found that surfaces coupled to matter fields have well-defined complex structures for cases when the matter central charges are less than or equal to one, while they become unstable beyond c=1. A nat

Luigi Del Debbio, Simon Hands

We study the Thirring model in three spacetime dimensions, by means of Monte Carlo simulation on lattice sizes 8^3 and 12^3, for numbers of fermion flavors N_f=2,4,6. For sufficiently strong interaction strength, we find that spontaneous chiral symmetry breaking occurs for N_f=2,4, in accordance with the predictions of the Schwinger-Dyson approach. The phase

Daniel Kennefick, Amos Ori

It is demonstrated that, in the adiabatic approximation, non-Equatorial circular orbits of particles in the Kerr metric (i.e. orbits of constant Boyer-Lindquist radius) remain circular under the influence of gravitational radiation reaction. A brief discussion is given of conditions for breakdown of adiabaticity and of whether slightly non-circular orbits ar

Kiyoshi Ezawa

Ashtekar's formulation for canonical quantum gravity is known to possess the topological solutions which have their supports only on the moduli space $\CN$ of flat $SL(2,C)$ connections. We show that each point on the moduli space $\CN$ corresponds to a geometric structure, or more precisely the Lorentz group part of a family of Lorentzian structures, on

Vaclav Janis

We investigate quantitatively the effects of strong electron-electron coupling onto the dynamics of lattice electrons. To that purpose the self-consistent version of the bubble-chain approximation at zero temperature and half filling of the Anderson (Hubbard) model is used. Special attention is paid to a critical region of an electron-hole correlation functi

Chetan Nayak, Frank Wilczek

We propose a class of variational wave functions with slow variation in spin and charge density and simple vortex structure at infinity, which properly generalize both the Laughlin quasiparticles and baby Skyrmions. We argue that the spin of the corresponding quasiparticle has a fractional part related in a universal fashion to the properties of the bulk sta

P. Wurth, G. Uhrig, E. Mueller-Hartmann

The instability of the fully polarized ferromagnetic state (Nagaoka state) with respect to single spin flips is re-examined for the Hubbard model on the square lattice with a large family of variational wave functions which include correlation effects of the majority spins in the vicinity of the flipped spin. We find a critical hole density of $δ_{cr} = 0.25

S. Fujimoto, N. Kawakami, S. -K. Yang

The exact finite-size spectra for several quantum impurity models related to the Kondo problem are obtained from the Bethe ansatz solutions. Using the finite-size scaling in boundary conformal field theory, we determine various surface critical exponents from the exact spectrum, which accord with those obtained by Affleck and Ludwig with Kac-Moody fusion rul

S. Doniach, T. Garel, H. Orland

We consider a lattice model of a semiflexible homopolymer chain in a bad solvent. Beside the temperature $T$, this model is described by (i) a curvature energy $\varepsilon_h$, representing the stiffness of the chain (ii) a nearest-neighbour attractive energy $\varepsilon_v$, representing the solvent (iii) the monomer density $ρ={N \over Ω}$, where $N$ and $

T. Garel, G. Iori, H. Orland

A disorder-dependent Gaussian variational approach is applied to the $d$-dimensional ferromagnetic XY model in a random field. The randomness yields a non extensive contribution to the variational free energy, implying a random mass term in correlation functions. The Imry-Ma low temperature result, concerning the existence ($d>4$) or absence ($d < 4$) of lon

S. Klimek, A. Lesniewski, N. Maitra, R. Rubin

We study the ergodic properties for a class of quantized toral automorphisms, namely the cat and Kronecker maps. The present work uses and extends the results of [KL]. We show that quantized cat maps are strongly mixing, while Kronecker maps are ergodic and non-mixing. We also study the structure of these quantum maps and show that they are effected by unita

Patrick B. Hall, Patrick S. Osmer, Richard F. Green, Alain C. Porter

We have used the KPNO 4-meter Mayall telescope to image 0.83 square degrees of sky in six fields at high galactic latitude in six filters spanning 3000-10000\AA\ to magnitude limits ranging from 22.1 to 23.8. As a first use of this database, we have conducted a multicolor survey for quasars. We discuss various methods of selecting outliers in different color

Patrick B. Hall, Patrick S. Osmer, Richard F. Green, Alain C. Porter

We have used the KPNO 4-meter Mayall telescope to image 0.83 square degrees of sky in six fields at high galactic latitude in six filters spanning 3000-10000Å to magnitude limits ranging from 22.1 to 23.8. We have assembled a catalog of 21,375 stellar objects detected in the fields for use primarily in conducting a multicolor search for quasars. This paper d

S. Durand, H. Dejonghe, A. Acker

We present a dynamical analysis of 673 galactic Planetary Nebulae, using a two-integral axisymmetric model with a Kuzmin-Kutuzov Stäckel potential. The method fits the kinematics to the projected moments of a distribution function, by means of Quadratic Programming. The 2.2 $μ$m COBE brightness map has been used after correction for the interstellar extincti

Reuven Ramaty

Gamma ray emission lines resulting from accelerated particle bombardment of ambient gas can serve as an important spectroscopic tool for abundance determinations. The method is illustrated by considering the gamma ray line emission observed from solar flares. The observation of similar gamma ray lines from Orion suggests the existence of large fluxes of low

Joerg P. Rachen, Karl Mannheim, Peter L. Biermann

We report results from the spectral analysis of pointed ROSAT PSPC observations of six PG quasars and the weak-bump quasar PHL 1657. Disregarding other frequency bands, the PSPC data are represented best by simple power-law source spectra ($dN/dE \propto E^Γ$) with a slope $Γ= -2.5\pm 0.4$ and do not show evidence for a more complex structure. However, withi

Peter Schneider

The last decade has seen an enormous increase of activity in the field of gravitational lensing, mainly driven by improvements of observational capabilities. I will review the basics of gravitational lens theory, just enough to understand the rest of this contribution, and will then concentrate on several of the main applications in cosmology. Cluster lensin

J. -M. Perrin, S. Darbon, J. -P. Sivan

Low-dispersion spectra have been obtained from 4000 to 9600 Å~along the axis and across the dusty halo of the galaxy M82. The spectra of the halo are explained in terms of scattering of the galactic light by dust grains: when divided by the spectrum of the galaxy, they reveal a broad emission band, similar to, although wider than the bump of Extended Red Emi

K. Mannheim, D. Grupe, K. Beuermann, H. -C. Thomas

We report some remarkable and unexpected results of optical/UV/X-ray follow-up observations of bright soft X-ray selected AGN from the ROSAT All-Sky-Survey. The majority of these AGN are rather anonymous Seyfert galaxies, mostly of the narrow-line Seyfert 1 subtype (nlSy1). We confirm the well-known X-ray variability by factors of a few. However, we also fou

Brian Fields

The light elements D, \he3, \he4, and \li7 are produced in big bang nucleosynthesis and undergo changes in their abundances due to galactic processing. Since one may observe most of these elements only in contemporary environments, knowledge of the intervening evolution is necessary for determining the observational constraints on primordial nucleosynthesis.

A. P. Balachandran, L. Chandar, Arshad Momen

It is known that gauge fields defined on manifolds with spatial boundaries support states localized at the boundaries. In this paper, we demonstrate how coarse-graining over these states can lead to an entanglement entropy. In particular, we show that the entanglement entropy of the ground state for the quantum Hall effect on a disk exhibits an approximate `

M. T. Ressell, G. J. Mathews, M. B. Aufderheide. S. D. Bloom, D. A. Resler

We examine the effects on the nuclear neutral current Gamow-Teller (GT) strength of a finite contribution from a polarized strange quark sea. We perform nuclear shell model calculations of the neutral current GT strength for a number of nuclei likely to be present during stellar core collapse. We compare the GT strength when a finite strange quark contributi

M. J. Graf, S. -K. Yip, J. A. Sauls

We study the thermal conductivity within the E$_{1g}$ and E$_{2u}$ models for superconductivity in UPt$_3$ and compare the theoretical results for electronic heat transport with recently measured results reported by Lussier, Ellman and Taillefer. The existing data down to $T/T_c\approx 0.1$ provides convincing evidence for the presence of both line and point

Sanjay Reddy, Madappa Prakash

We calculate neutrino cross sections from neutral current reactions in dense matter containing hyperons. We show that Sigma- hyperons give significant contributions. To lowest order, the contributions from the neutral Lambda and Sigma0, which have zero hyper-charge, vanish. However, their presence furnishes baryon number which decreases the relative concentr

L. Anchordoqui, M. T. Dova, D. Gomez Dumm, P. Lacentre

We analyze the possibility of testing local Lorentz invariance from the observation of tau decays. Future prospects of probing distances below the electroweak characteristic scale are discussed.

G. Grignani, G. Semenoff, P. Sodano, O. Tirkkonen

We examine the possibility of a confinement-deconfinement phase transition at finite temperature in both parity invariant and topologically massive three-dimensional quantum electrodynamics. We review an argument showing that the Abelian version of the Polyakov loop operator is an order parameter for confinement, even in the presence of dynamical electrons.

G. Parzen

This paper studies the motion of a particle whose tune is inside and near a linear half-integer stopband. Results are found for the tune and beta functions in the stable region close to an edge of the stopband. It is shown that the eigenvalues and the eigenfunctions of the transfer matrix are real inside the stopband. All the results found are also valid for

Nicolas Pott

We calculate the O($\alpha_s$) gluon Bremsstrahlung corrections to the inclusive decay $b \rightarrow s \gamma$, involving the full operator basis $\hat O_1$ -- $\hat O_8$. Confirming and extending earlier calculations of Ali and Greub, we give formulas for the total decay width as well as the perturbative photon spectrum, regarding the former as a necessary

R. P. Manvelyan

The super-Weyl cocycle (effective action for supertrace anomaly) and corresponding invariant operator in nonminimal formulation of $d=4$,$N=1$ supergravity are obtained.

Carlos Castro

Extensions (modifications) of the Heisenberg Uncertainty principle are derived within the framework of the theory of Special Scale-Relativity proposed by Nottale. In particular, generalizations of the Stringy Uncertainty Principle are obtained where the size of the strings is bounded by the Planck scale and the size of the Universe. Based on the fractal stru

Ross H. McKenzie, C. J. Hamer, D. W. Murray

The Holstein model of spinless fermions interacting with dispersionless phonons in one dimension is studied by a Green's function Monte Carlo technique. The ground state energy, first fermionic excited state, density wave correlations, and mean lattice displacement are calculated for lattices of up to 16 sites, for one fermion per two sites, i.e., a half-fil

V. D. Dzhunushaliev

The quantum gravity has great difficulties with application of the probability notion. In given article this problem is analyzed according to algorithmic viewpoint. According to A.N. Kolmogorov, the probability notion can be connected with algorithmic complexity of given object. The paper proposes an interpretation of quantum gravity, according to which an a

Bong H. Lian, Gregg J. Zuckerman

The BRST formalism has played a fundamental role in the construction of bosonic closed string backgrounds, ie. the stringy analogs of classical solutions to the field equations of general relativity. The concept of a string background has been extended to the notion of $W$-strings, where the BRST symmetry is still largely conjectural. More recently, the BRST

Ivan Cherednik

This paper contains the proof of difference counterparts of the conjectures due to Keven Kadell on symmetric and anti-symmetric Macdonald polynomials.

J. Rozanski

For a symmetry braid S-Lie coalgebras, as a dual object to algebras introduced by Gurevich, are considered. For an Young antisymmetrizer an S-exterior algebra is introduced. From this differential point of view S-Lie coalgebras are investigated. The dual Koszul theorem in this case is proved.

M. T. Ressell, J. Engel, P. Vogel

We use the experimental limit on the interference of M1 and E2 multipoles in the $γ$-decay of $^{57}$Fe to bound the time-reversal-violating parity-conserving $ρN N$ vertex. Our approach is a large-basis shell-model calculation of the interference. We find an upper limit on the parameter $\bar{g}_ρ$, the relative strength of the T-violating $ρN N$ vertex, of

Michael Christ

Examples are given of degenerate elliptic operators on smooth, compact manifolds that are not globally regular in $C^\infty$. These operators degenerate only in a rather mild fashion. Certain weak regularity results are proved, and an interpretation of global irregularity in terms of the associated heat semigroup is given.

Gilles Pisier

Recently, E.\ Kirchberg [K1--2] revived the study of pairs of $C^*$-algebras $A,B$ such that there is only one $C^*$-norm on the algebraic tensor product $A\otimes B$, or equivalently such that $A \otimes_{\rm min}B = A\otimes_{\rm max}B$. Recall that a $C^*$-algebra is called nuclear cf.\ [L, EL] if this happens for any $C^*$-algebra $B$. Kirchberg [K1] con

G. S. Danilov, I. T. Dyatlov, V. Yu. Petrov

The charge screening, confinement of fermion quantum numbers and the chiral condensate formation in two-dimensional QED is studied in details. It is shown that charge screening and confinement of fermion number in two-dimensional QED is due to an appearance of gauge fields which nullify the Dirac determinant. An appearance of the fields of another type but w

Hans-Christian Pauli, J&#34;org Merkel

The effective QCD-interaction as obtained from the front form Hamiltonian by DLCQ is Fourier transformed on the Retarded Schrödinger Equation for to describe the constituents of physical mesons. The crucial point is the use of a running coupling constant $α_s(Q^2)$, in a manner similar but not equal to the one of Richardson in the equal usual-time quantizati

A. A. Andrianov, V. A. Andrianov, V. L. Yudichev

Fermion models with selfinteraction including derivatives of fields are investigated in the strong coupling regime. The existence of three phases is established in the two channel model near tricritical point. The special phase of dynamical P-parity breaking is found.

G. C. Branco, W. Grimus, L. Lavoura

We perform a systematic study of CP-violating observables in \ddbar\ decays. We show that given a final state, which may be a CP eigenstate or not, all the observables can in principle be measured if decay-time information is available and if, for CP non-eigenstates, both decay rates into $f$ and $\bar f$ are considered. As an illustration of our analysis we

W. Roberts

We examine the rates for the exclusive decays $B\to K^{(*)}\ell^+\ell^-$. We use the scaling predictions of the heavy quark effective theory to extract the necessary form factors from fits to various combinations of data. These data include the $D\to K^{(*)}\ellν$ semileptonic decays, as well as the nonleptonic decays $B\to K^{(*)}ψ^{(\prime)}$ and the rare

Tadashi Yoshikawa

We study the effects of a vector-like SU(2) doublet quarks as the fourth generation on $R_b$ and $R_c$. By considering the constraint from the experimental data of forward-backward asymmetry, $A_{FB}^b$ and $A_{FB}^c$,as well as FCNC among light quarks, we show that there is an allowed region of parameters for $R_b$ but not for $R_c$.

S. Catterall, G. Thorleifsson, J. Kogut, R. Renken

By a sequence of numerical experiments we demonstrate that generic triangulations of the $D-$sphere for $D>3$ contain one {\it singular} $(D-3)-$simplex. The mean number of elementary $D-$simplices sharing this simplex increases with the volume of the triangulation according to a simple power law. The lower dimension subsimplices associated with this $(D-3)-

Peter N. Meisinger, Michael C. Ogilvie

We demonstrate that chiral symmetry restoration in quenched finite temperature QCD depends crucially on the $Z_3$ phase of the Polyakov loop ${\cal P}$. This dependence is a general consequence of the coupling of the chiral order parameter to the Polyakov loop. We construct a model for chiral symmetry breaking and restoration which includes the effect of a n

B. Alles, M. Beccaria, F. Farchioni

The renormalization constants present in the lattice evaluation of the topological susceptibility can be non-perturbatively calculated by using the so-called heating method. We test this method for the $O(3)$ non-linear $σ$-model in two dimensions. We work in a regime where perturbative calculations are exact and useful to check the values obtained from the

Paolo Franzini

$CP$ violation experiments, new measurements of the parameters of the neutral \K\ system and searches for rare decays are summarized. Perspectives for the near future are presented.

M. Novello, L. R. Freitas, V. A. De Lorenci

We continue here the exam \cite{LuMa} of a theory of gravity that satisfies the Einstein Equivalence Principle (EEP) for any kind of matter/energy, except for the gravitational energy. This is part of a research program that intends to re-examine the standard Feynman-Deser approach of field theoretical derivation of Einstein\rq s General Relativity. The hypo

Paul A. Houle, James P. Sethna

From magnetic systems to the crust of the earth, many physical systems that exibit a multiplicty of metastable states emit pulses with a broad power law distribution in energy. Digital audio recordings reveal that paper being crumpled, a system that can be easily held in hand, is such a system. Crumpling paper both using the traditional hand method and a nov

A. E. Meyerovich, S. Stepaniants

This is the second in the series of papers on transport phenomena along random rough surfaces. We apply our simple general approach\cite{r1} to transport in very narrow channels, when the particles wavelength is comparable to the width of the channels and the motion across the channel is characterized by discrete quantum states. The discrete nature of the sp

Zhong-Yi Lu, Guido L. Chiarotti, S. Scandolo, E. Tosatti

We have carried out an ab-initio study of $α$-Sn (111), with the aim of predicting and understanding its structure, reconstructions, and electronic states. We consider a variety of structural possibilities, and optimize them by moving atoms according to Hellmann-Feynman forces. Our results indicate that the unreconstructed surface is highly unstable, while a

J. Ranninger, J. M. Robin

We study the normal state spectral properties of the fermionic excitations in the Boson-Fermion model. The fermionic single particle excitations show a flattening of the dispersion as the Fermi vector ${\bf k}_{_F}$ is approached from below, forshadowing a Bogoliubov spectrum of a superconducting ground state. The width of the quasiparticle excitations near

Fabio Siringo, Giuseppe G. N. Angilella, Renato Pucci

A renormalization group (RG) analysis of the superconductive instability of an anisotropic fermionic system is developed at a finite temperature. The method appears a natural generalization of Shankar&#39;s approach to interacting fermions and of Weinberg&#39;s discussion about anisotropic superconductors at T=0. The need of such an extension is fully justif

Bosiljka Tadic, Ramakrishna Ramaswamy

We study three models of driven sandpile-type automata in the presence of quenched random defects. When the dynamics is conservative, all these models, termed the random sites (A), random bonds (B), and random slopes (C), self-organize into a critical state. For Model C the concentration-dependent exponents are nonuniversal. In the case of nonconservative de

E. H. Brandt, R. G. Mints, I. B. Snapiro

It is shown that in extremely anisotropic layered superconductors the interaction of vortex lines with a parallel planar surface, which for straight lines along the c-axis decreases exponentially over the in-plane penetration depth $λ$, becomes a long-range dipole--dipole attraction when the vortex line is distorted randomly. This novel long-range fluctuatio

Yutaka Takahashi

Monte Carlo Simulations of the Spatial Transport of Excitons in a Quantum Well Structure Yutaka Takahashi (Dep. of Electrical and Information Eng., Yamagata University) The in-plane spatial transport of nonequilibrium excitons in a GaAs quantum well structure has been simulated with the ensemble Monte Carlo method. The simulation has been performed for excit

D. A. Hamburger, R. B. Gerber

The information content and properties of the cross section for atom scattering from a defect on a flat surface are investigated. Using the Sudden approximation, a simple expression is obtained that relates the cross section to the underlying atom/defect interaction potential. An approximate inversion formula is given, that determines the shape function of t

Baowen Li, Marko Robnik

Quantum chaos manifests itself also in algorithmical complexity of methods, including the numerical ones, in solving the Schrödinger equation. In this contribution we address the problem of calculating the eigenenergies and the eigenstates by various numerical methods applied to 2-dim generic billiard systems. In particular we analyze the dependence of the a

Stuart D. Ryder, Ronald J. Buta, Hector Toledo, Hemant Shukla

We have made observations of the \ion{H}{1} in the southern ringed barred spiral galaxies NGC~1433 and NGC~6300 with the Australia Telescope Compact Array (ATCA), the main goal being to test the resonance theory for the origin of these rings. NGC~1433 is the prototypical ringed barred spiral, and displays distinct \ion{H}{1}~counterparts to its nuclear ring,

A. Refregier, D. J. Helfand, R. G. McMahon

The foreground component of the X-ray Background (XRB) can be studied by cross-correlating its intensity with galaxy catalogs. We computed the two-point cross-correlation function $W_{xg}$ between 67 {\em Einstein} X-ray fields and the APM galaxy catalog. We detected a signal with an amplitude of $W_{xg} = .04 \pm .01$, significant at the $3.5σ$ level. The r

L. R. Jones, C. A. Scharf, E. Perlman, H. Ebeling

The WARPS cluster survey is based on the ROSAT PSPC archive of pointed observations. It includes extended X-ray sources, detected with the Voronoi Tessellation and Percolation algorithm (VTP), and point-like X-ray sources with non-stellar optical counterparts. It is designed to minimize selection effects whilst covering a large area of sky. The aims of the s

S. Schindler

X-ray and radio continuum observations of the bimodal cluster A3528 in the Shapley Supercluster are presented. From a ROSAT PSPC pointed observation we find a marginal tendency of the intracluster gas to be hotter in the region between the two subclusters. This effect can be interpreted as the signature of interaction of the subclusters. We infer that the ce

Alexandre Refregier, Abraham Loeb

We examine the gravitational lensing effect of a foreground galaxy cluster on the number count statistics of background X-ray sources. The lensing produces a deficit in the number of resolved sources in a ring close to the critical radius of the cluster. This deficit could be detected at the $\sim 3σ$ level with the AXAF-ACIS camera.

E. Salvador-Sole

I review the main steps made so far towards the construction of a (semi) analytical model for describing the growth history of bound virialized objects or haloes in the gravitational instability scenario. I mainly focus on those models relying on the spherical collapse approximation which have led to the most complete description. I insist on the different a

Rosemary A. Mardling

We review the tidal capture mechanism for binary formation, an important process in globular cluster cores and perhaps open cluster cores. Tidal capture binaries may be the precursors for some of the low-mass X-ray binaries observed in abundance in globular clusters. They may also play an important role in globular cluster dynamics. We summarize the chaos mo

J. E. Hibbard, J. H. van Gorkom

We present high-quality aperture synthesis observations of the neutral hydrogen distribution in a sample of five galactic systems believed to be involved in progressive stages of merging: Arp295, NGC4676, NGC520, NGC3921, and NGC7252. These data are supplemented by wide-field images taken through a narrow band Halpha filter, and by deep R-band surface photom

Elisabeth Vangioni-Flam, Michel Cassé, Brian D. Fields, Keith A. Olive

The production of LiBeB isotopes by nuclear and neutrino spallation are compared in the framework of galactic evolutionary models. As motivated by $γ$-ray observations of Orion, different possible sources of low-energy C and O nuclei are considered, such as supernovae of various masses and WC stars. We confirm that the low energy nuclei (LEN), injected in mo

Sebastian M. Pascarelle, Rogier A. Windhorst, Simon P. Driver, Eric J. Ostrander

We report the serendipitous discovery of a group or cluster of young galaxies at $z\simeq$2.40 in a 24-orbit HST/WFPC2 exposure of the field around the weak radio galaxy 53W002. Potential cluster members were identified on ground-based narrow-band redshifted Ly$α$ images and confirmed via spectroscopy. In addition to the known weak radio galaxy 53W002 at z=2

Francisco Gallego, B. P. Purnaprajna

Let L be a normally generated line bundle on X; we say L satisfies property N_p (notation after Mark Green) if the matrices in the free resolution of R (the homogeneous coordinate ring of X) over S (the homogeneous coordinate ring of the projective space corresponding to the complete linear series |L|) have linear entries until the p-th stage. In this articl

Pietro Fré

In these lectures I review the general structure of electric--magnetic duality rotations in every even space--time dimension. In four dimensions, which is my main concern, I discuss the general issue of symplectic covariance and how it relates to the typical geometric structures involved by N=2 supersymmetry, namely Special K\"ahler geometry for the vector m

D. A. Hamburger, A. T. Yinnon, R. B. Gerber

We propose a novel method to measure the fractal dimension of a submonolayer metal adatom system grown under conditions of limited diffusivity on a surface. The method is based on measuring the specular peak attenuation of He atoms scattered from the surface, as a function of incidence energy. The (Minkowski) fractal dimension thus obtained is that of contou

Miao Li

Dirichlet-branes have emerged as important objects in studying nonperturbative string theory. It is important to generalize these objects to more general backgrounds other than the usual flat background. The simplest case is the linear dilaton condensate. The usual Dirichlet boundary condition violates conformal invariance in such a background. We show that

S. Abachi

We have searched for associated production of the lightest chargino, $\widetilde{W}_1$, and next-to-lightest neutralino, $\widetilde{Z}_2$, of the Minimal Supersymmetric Standard Model in $p\bar{p}$ collisions at \mbox{$\sqrt{s}$ = 1.8 TeV} using the \D0 detector at the Fermilab Tevatron collider. Data corresponding to an integrated luminosity of 12.5$\pm 0.

R. Onofrio, T. Calarco

Temporal Bell-like inequalities are derived taking into account the influence of the measurement apparatus on the observed magnetic flux in a rf-SQUID. Quantum measurement theory is shown to predict violations of these inequalities only when the flux states corresponding to opposite current senses are not distinguishable. Thus rf-SQUIDs cannot help to discri

M. Daoud, M. Kibler

This paper is concerned with statistical properties of a gas of $qp$-bosons without interaction. Some thermodynamical functions for such a system in $D$ dimensions are derived. Bose-Einstein condensation is discussed in terms of the parameters $q$ and $p$. Finally, the second-order correlation function of a gas of photons is calculated.

Serge Yu. Potapenko

It is shown that step moving to meet solution flow can be unstable against lateral perturbations. The instability of long-wavelength perturbations occurs at values of the solution flow intensity less than some critical value depending on the step velocity. At given intensity of the solution flow, the instability comes at the step velocity exceeding a critica

Larbi Beldjoudi, Tran Truong

$τ\toππν$, $τ\toπKν$, $τ\to Kην$, $τ\to 3πν$ and $τ\to ππKν$ have been investigated using chiral symmetry with dispersion relation in agreement with the unitarity condition.

Yasuhiro Hatsugai, Mahito Kohmoto, Tohru Koma, Yong-Shi Wu

We study statistical characterization of the many-body states in the exactly solvable model with internal degree of freedom in more than one dimension. The model exhibits the Mott metal-insulator transition. It is shown that the ground state is described by that of a generalized ideal gas of particles (called exclusons) which have mutual exclusion statistics

Mirjam Cvetic, Arkady A. Tseytlin

We consider a six-dimensional solitonic string solution described by a conformal chiral null model with non-trivial $N=4$ superconformal transverse part. It can be interpreted as a five-dimensional dyonic solitonic string wound around a compact fifth dimension. The conformal model is regular with the short-distance (`throat&#39;) region equivalent to a WZW t

G. A. El

We present a fundamental solution to an initial value problem for the KdV-Whitham system in an explicit integral form. Monotonically decreasing initial data with finite number of breaking points are considered. Generating function for the commuting flows of the averaged KdV hieararchy producing the analytical solutions to the KdV-Whitham system is constructe

Wen-Xiu Ma

A Bargmann symmetry constraint is proposed for the Lax pairs and the adjoint Lax pairs of the Dirac systems. It is shown that the spatial part of the nonlinearized Lax pairs and adjoint Lax pairs is a finite dimensional Liouville integrable Hamiltonian system and that under the control of the spatial part, the time parts of the nonlinearized Lax pairs and ad

H. M. França, A. Maia, C. P. Malta

We give an example in which it is possible to understand quantum statistics using classical concepts. This is done by studying the interaction of charged matter oscillators with the thermal and zeropoint electromagnetic fields characteristic of quantum electrodynamics and classical stochastic electrodynamics. Planck&#39;s formula for the spectral distributio

Z. Haba

Quantum dynamics of integrable systems is discussed. Localized wave packets generalizing the conventional coherent states of minimal uncertainty are constructed. The wave packet moves along a certain trajectory and does not change its shape for times of order $\frac{1}{\hbar}$.