July 1999 arXiv papers — page 8

G. Conti, L. Chiappetti, E. Mattaini, D. Maccagni

We describe the VIRMOS Mask Manufacturing Unit (MMU) configuration, composed of two units:the Mask Manufacturing Machine (with its Control Unit) and the Mask Handling Unit (inclusive of Control Unit, Storage Cabinets and robot for loading of the Instrument Cabinets). For both VIMOS and NIRMOS instruments, on the basis of orders received by the Mask Preparati

T. Venturi, G. B. Taylor

Multifrequency polarimetric observations made with the Very Long Baseline Array of the quasar 3C216 reveal the presence of Faraday rotation measures (RMs) in excess of 2000 rad/m**2 in the source rest frame, in the arc of emission located at ~ 140 mas from the core. Rotation measures in the range -300 - +300 rad/m**2 are detected in the inner 5 mas (~30 pars

B. Garilli, D. Bottini, L. Tresse, O. LeFevre M. Saisse

VIMOS and NIRMOS are two multi Object Spectrographs being developed for the VLT. Their main scientific characteristic is the high multiplexing capability, allowing to obtain up to 800 spectra per exposure. To achieve such a high efficiency, a number of dedicated tools are necessary, from software to hardware. In part a), we describe the software tools which

M. Sevenster

We analyse a sample of 507 evolved stars in the inner galactic Plane. We derive average ages for subsets of this sample and use those sets as beacons for the evolution of the Galaxy. In the Bulge the oldest OH/IR stars in the plane are 7.5 Gyr, in the Disk 2.7 Gyr. The vertical distribution of almost all AGB stars in the Disk is found to be nearly exponentia

Faustin Munyaneza, Raoul D. Viollier

The emission spectrum of the supermassive compact dark object at the Galactic center is calculated in the framework of standard thin accretion disk theory assuming that the compact object is a neutrino ball of $2.6 \times 10^{6}M_{\odot}$ instead of a supermassive black hole. The neutrino ball scenario could explain the observed radio and infrared emission s

Feng Yuan

We investigate the influences of the outer boundary conditions(OBCs) on the structure of an optically thin accretion flow. We find that OBC plays an important role in determining the topological structure and the profiles of the surface density and temperature of the solution, therefore it should be regarded as a new parameter in the accretion disk model.

Megan Donahue, G. Mark Voit, Caleb A. Scharf, Isabella M. Gioia

We report on our ASCA, Keck, and ROSAT observations of MS1137.5+6625, the second most distant cluster of galaxies in the Einstein Extended Medium Sensitivity Survey (EMSS), at redshift 0.78. We now have X-ray temperatures, velocity dispersions, and X-ray images for a complete, high-redshift sample of EMSS clusters. ASCA observations of MS1137.5+6625 yield a

Ricard V. Sole, Bartolo Luque, Stuart Kauffman

The critical boundaries separating ordered from chaotic behavior in randomly wired S-state networks are calculated. These networks are a natural generalization of random Boolean nets and are proposed as on extended approach to genetic regulatory systems, sets of cells in different states or collectives of agents engaged into a set of S possible tasks. A orde

Ricard V. Sole, David Alonso, Alan McKane

A new model ecosystem consisting of many interacting species is introduced. The species are connected through a random matrix with a given connectivity. It is shown that the system is organized close to a boundary of marginal stability in such a way that fluctuations follow power law distributions both in species abundance and their lifetimes for some slow-d

B. Kaulakys

An analytically solvable model is proposed exhibiting 1/f spectrum in any desirably wide range of frequency (but excluding the point f=0). The model consists of pulses whose recurrence times obey an autoregressive process with very small damping.

Justin Werfel, Melanie Mitchell, James P. Crutchfield

Evolving one-dimensional cellular automata (CAs) with genetic algorithms has provided insight into how improved performance on a task requiring global coordination emerges when only local interactions are possible. Two approaches that can affect the search efficiency of the genetic algorithm are coevolution, in which a population of problems---in our case, i

Jack Boyce, Juan P. Torres, Raymond Y. Chiao

We report the first observation of a nonlinear mode in a cylindrical nonlinear Fabry-Perot cavity. The field enhancement from cavity buildup, as well as the large chi3 optical nonlinearity due to resonantly-excited Rb-85 vapor, allows the nonlinear mode to form at low incident optical powers of less than a milliwatt. The mode is observed to occur for both th

T. C. Ralph

We propose a quantum cryptographic scheme in which small phase and amplitude modulations of CW light beams carry the key information. The presence of EPR type correlations provides the quantum protection.

Jeffrey E. McClintock, Ronald A. Remillard

In 1998 we made UV spectroscopic observations with HST/STIS of A0620-00 and Cen X-4, which are two X-ray novae (aka soft X-ray transients). These binary systems are similar in all respects except that the former contains a black hole and the latter contains a neutron star. A UV spectrum (1700-3100A) is presented for the quiescent state of each system in the

Piero Madau, Lucia Pozzetti

We assess the constraints imposed by the observed extragalactic background light (EBL) on the cosmic history of star formation and the stellar mass density today. The logarithmic slope of the galaxy number-magnitude relation from the Southern Hubble Deep Field} imaging survey is flatter than 0.4 in all seven UBVIJHK optical bandpasses, i.e. the light from re

J. P. Clemens, P. R. Rice

We investigate the photon statistics of light transmitted from a driven optical cavity containing one or two atoms interacting with a single mode of the cavity field. We treat arbitrary driving fields with emphasis on departure from previous weak field results. In addition effects of dephasing due to atomic transit through the cavity mode are included using

B. I. Shklovskii

Screening of a strongly charged macroion by multivalent counterions is considered. It is shown that counterions form a strongly correlated liquid at the surface of the macroion. Cohesive energy of this liquid leads to additional attraction of counterions to the surface which is absent in conventional solutions of Poisson-Boltzmann equation. Away from the sur

A. Giveon, D. Kutasov, O. Pelc

We argue that a class of ``non-critical superstring'' vacua is holographically related to the (non-gravitational) theory obtained by studying string theory on a singular Calabi-Yau manifold in the decoupling limit $g_s\to 0$. In two dimensions, adding fundamental strings at the singularity of the CY manifold leads to conformal field theories dual to a recent

Kurt Haller, Lusheng Chen, Y. S. Choi

We investigate solutions to a nonlinear integral equation which has a central role in implementing the non-Abelian Gauss's Law and in constructing gauge-invariant quark and gluon fields. Here we concern ourselves with solutions to this same equation that are not operator-valued, but are functions of spatial variables and carry spatial and SU(2) indices.

V. Aldaya, J. L. Jaramillo

A model for 2D Quantum Gravity is constructed out of the Virasoro group. To this end the quantization of the abstract Virasoro group is revisited. For the critical values of the conformal anomaly c, some quantum operators (SL(2,R) generators) lose their dynamical content (they are no longer conjugated operators). The notion of space-time itself in 2D gravity

Nuria Rius, Veronica Sanz

We calculate the baryon asymmetry generated at the electroweak phase transition in the minimal supersymmetric standard model, using a new method to compute the CP-violating asymmetry in the Higgsino flux reflected into the unbroken phase. The method is based on a Higgs insertion expansion. We find that the CP asymmetry at leading order is proportional to the

F. Gieres

By a series of simple examples, we illustrate how the lack of mathematical concern can readily lead to surprising mathematical contradictions in wave mechanics. The basic mathematical notions allowing for a precise formulation of the theory are then summarized and it is shown how they lead to an elucidation and deeper understanding of the aforementioned prob

S. Bass, M. Bleicher, W. Cassing, A. Dumitru

This paper contains the individual contributions of all speakers of the session on 'Last Call for RHIC Predictions' at Quark Matter 99, and a summary by the convenor.

G. E. Volovik

The momentum-space topological invariants, which characterize the ground state of the Standard Model, are continuous functions of two parameters, generated by the hypercharge and by the weak charge. These invariants provide the absence of the mass of the elementary fermionic particles in the symmetric phase above the electroweak transition (the mass protecti

C. Motch, F. Haberl, F. -J. Zickgraf, G. Hasinger

We report on X-ray and optical observations of a ROSAT X-ray source, RX J1605.3+3249, selected from the all-sky survey on the basis of its spectral softness and lack of bright optical counterpart. The ROSAT PSPC energy distribution is well fitted by a blackbody with kT = 92 +/- 6 eV and Nh =1.1 +/- 0.4 x 10^20 cm^-2. X-ray observations spanning 6.5 years fai

Giulio Biroli, Remi Monasson, Martin Weigt

A variational approach to finite connectivity spin-glass-like models is developed and applied to describe the structure of optimal solutions in random satisfiability problems. Our variational scheme accurately reproduces the known replica symmetric results and also allows for the inclusion of replica symmetry breaking effects. For the 3-SAT problem, we find

Zhi-zhong Xing

CP asymmetries in B_d \to D^+D^-, D^{*+}D^-, D^+D^{*-} and D^{*+}D^{*-} decays are investigated with the help of the factorization approximation and isospin relations. We find that the direct CP violation is governed only by the short-distance penguin mechanism, while the indirect CP asymmetries in B_d \to D^{\pm}D^{*\mp} transitions may be modified due to t

Rangan Lahiri, Mustansir Barma, Sriram Ramaswamy

We study the steady state resulting from instabilities in crystals driven through a dissipative medium, for instance, a colloidal crystal which is steadily sedimenting through a viscous fluid. The problem involves two coupled fields, the density and the tilt; the latter describes the orientation of the mass tensor with respect to the driving field. We map th

Zhi-zhong Xing

The formulae for D^0-\bar{D}^0 or B^0-\bar{B}^0 mixing and CP violation at the τ-charm or B-meson factories are derived, for the case that only the decay-time distribution of one D or B meson is to be measured. In particular, we point out a new possibility to determine the D^0-\bar{D}^0 mixing rate in semileptonic D decays at the Ψ(4.14) resonance; and show

M. Diehl, T. Gousset, B. Pire

We perform a QCD analysis of exclusive two-meson production in gamma* gamma collisions in the kinematical domain of large photon virtuality Q^2 and small hadronic invariant mass W^2. In these kinematics the amplitude factorizes into a perturbative subprocess gamma* gamma -> q qbar and a two-meson distribution amplitude. This opens the way to study new hadron

Paolo Valtancoli

We discuss a formalism for solving (2+1) AdS gravity on Riemann surfaces. In the torus case the equations of motion are solved by two functions f and g, solutions of two independent O(2,1) sigma models, which are distinct because their first integrals contain a different time dependent phase factor. We then show that with the gauge choice $k = \sqrt{\Lambda}

J. P. Carbotte, E. Schachinger, D. N. Basov

In conventional superconductors, the most direct evidence of the mechanism responsible for superconductivity comes from tunneling experiments in which a clear image of the electron-phonon interaction is revealed. The observed structure in the current voltage characteristics at the phonon energies can be used to measure, through inversion of the Eliashberg eq

P. Desgrolard, M. Giffon, E. Martynov, E. Predazzi

An extensive generalization of the ordinary and quasi-eikonal methods is presented for the $pp$ and $\bar pp$ elastic scattering amplitudes, which takes into account in a phenomenological way all intermediate multiparticle states involving the crossing even and crossing odd combinations of Reggeons. The formalism in this version involves a maximum of three p

Saburo Higuchi

A statistical model of loops on the three-dimensional lattice is proposed and is investigated. It is O(n)-type but has loop fugacity that depends on global three-dimensional shapes of loops in a particular fashion. It is shown that, despite this non-locality and the dimensionality, a layer-to-layer transfer matrix can be constructed as a product of local ver

Nobuko Fuchikami, Hijiri Iwata, Shunya Ishioka

To make clear several issues relating with the thermodynamics of computations, we perform a simulation of a binary device using a Langevin equation. Based on our numerical results, we consider how to estimate thermodynamic entropy of computational devices. We then argue against the existence of the so-called residual entropy in frozen systems such as ice.

Somendra M. Bhattacharjee, Sutapa Mukherji

We propose that the phases of all vicinal surfaces can be characterized by four fixed lines, in the renormalization group sense, in a three-dimensional space of coupling constants. The observed configurations of several Si surfaces are consistent with this picture. One of these fixed lines also describes one-dimensional quantum particles with fractional excl

Abhay Ashtekar, Christopher Beetle, Stephen Fairhurst

A set of boundary conditions defining an undistorted, non-rotating isolated horizon are specified in general relativity. A space-time representing a black hole which is itself in equilibrium but whose exterior contains radiation admits such a horizon. However, the definition is applicable in a more general context, such as cosmological horizons. Physically m

Yaroslav Tserkovnyak, Robert Komar, Christian Nally, Chris Waltham

We present a three-dimensional calculation of atmospheric neutrino fluxes using accurate models of the geomagnetic field, hadronic interactions, tracking and decays. Results are presented for the Super-Kamiokande (SK) and Sudbury Neutrino Observatory (SNO) sites using the GEANT-FLUKA hadronic code. We make a comparison with previous one-dimensional calculati

Q. P. Liu

We consider the Miura map between the lattice KP hierarchy and the lattice modified KP hierarchy and prove that the map is canonical not only between the first Hamiltonian structures, but also between the second Hamiltonian structures.

Takayuki Tsuchida, Miki Wadati

Higher flows of the Heisenberg ferromagnet equation and the Wadati-Konno-Ichikawa equation are generalized into multi-component systems on the basis of the Lax formulation. It is shown that there is a correspondence between the multi-component systems through a gauge transformation. An integrable semi-discretization of the multi-component higher Heisenberg f

Mladen Pavicic

Spin interferometry of the 4th order for independent polarized as well as unpolarized photons arriving simultaneously at a beam splitter and exhibiting spin correlation while leaving it, is formulated and discussed in the quantum approach. Beam splitter is recognized as a source of genuine singlet photon states. Also, typical nonclassical beating between pho

F. Gieres

Differents formalismes sont utilises en mecanique quantique pour la description des etats et des observables : la mecanique ondulatoire, la mecanique matricielle et le formalisme invariant. Nous discutons les problemes et inconvenients du formalisme invariant ainsi que ceux de la notation des bras et kets introduite par Dirac dans ce contexte. Nous indiquons

J. L. Cohen, B. Dubetsky, P. R. Berman

The focusing of atoms interacting with both far-detuned and resonant standing wave fields in the thin lens regime is considered. The thin lens approximation is discussed quantitatively from a quantum perspective. Exact quantum expressions for the Fourier components of the density (that include all spherical aberration) are used to study the focusing numerica

Xin-Nian Wang

We calculate the hadron spectra in high-energy pp, pA and AA collisions within a pQCD parton model. Analyses of experimental data show that the modification of the spectra in pA and AA as compared to that in $pp$ collisions is consistent with multiple parton scattering scenario and is dictated by the transition from absorptive soft interaction at low p_T to

A. L. Barabanov

It is shown that new spin-orbit-like terms appear in the effective nonrelativistic weak Hamiltonian for nucleon provided that nuclear potential is taken into account. Arguments for their considerable enhancement, in particular, in relativistic nuclear model of Walecka are advanced.

J. Lehr, M. Effenberger, U. Mosel

We calculate total photon-nucleus and electron-nucleus cross sections $γA\to X$, $e A\to e^\prime X$ and several cross sections on pion and eta production in nuclei in the energy regime between the first and the third resonance region for photon virtualities $Q^2\le 1.0 GeV^2$ within a semi-classical BUU transport model. In both cases we discuss the varying

M. Asakawa, T. Csorgo, M. Gyulassy

Novel back-to-back correlations are shown to arise for thermal ensembles of squeezed bosonic states associated with medium-modified mass-shifts. The strength of these correlations could become unexpectedly large in heavy ion collisions.

P. Duvall, J. Keesling

A theoretical approach to computing the Hausdorff dimension of the topological boundary of attractors of iterated function systems is developed. The curve known as the Lévy Dragon is then studied in detail and the Hausdorff dimension of its boundary is computed using the theory developed. The actual computation is a complicated procedure. It involves a great

Margaret M. Bayer, Gabor Hetyei

The closed cone of flag vectors of Eulerian partially ordered sets is studied. It is completely determined up through rank seven. Half-Eulerian posets are defined. Certain limit posets of Billera and Hetyei are half-Eulerian; they give rise to extreme rays of the cone for Eulerian posets. A new family of linear inequalities valid for flag vectors of Eulerian

Erik Taflin

A quadratic discrete time probabilistic model, for optimal portfolio selection in (re-)insurance is studied. For positive values of underwriting levels, the expected value of the accumulated result is optimized, under constraints on its variance and on annual ROE's. Existence of a unique solution is proved and a Lagrangian formalism is given. An effectiv

Weiqiang Wang

We show that the dimension of the minimal nilpotent coadjoint orbit for a complex simple Lie algebra is equal to twice the dual Coxeter number minus two.

Weiqiang Wang

We construct and study various dual pairs between finite dimensional classical Lie groups and infinite dimensional Lie algebras in some Fock representations. The infinite dimensional Lie algebras here can be either a completed infinite rank affine Lie algebra, the $\winf$ algebra or its certain Lie subalgebras. We give a formulation in the framework of verte

Brent Everitt, Colin Maclachlan

In this paper we show how to obtain representations of Coxeter groups acting on H^n to certain classical groups. We determine when the kernel of such a representation is torsion-free and thus the quotient a hyperbolic n-manifold.

Tomek Bartoszynski, Saharon Shelah

We show that the following are consistent with ZFC: 1. Strongly meager sets form an ideal with the same additivity as the ideal of meager sets. 2. There exists a strong measure zero set of size > d (dominating number).

Lieven Le Bruyn

The moduli spaces of theta-semistable representations of a finite quiver can be packaged together to form a noncommutative compact manifold.

Michel Dubois-Violette, Marc Henneaux

We construct N-complexes of non completely antisymmetric irreducible tensor fields on $\mathbb R^D$ generalizing thereby the usual complex (N=2) of differential forms. These complexes arise naturally in the description of higher spin gauge fields. Although, for $N\geq 3$, the generalized cohomology of these N-complexes is non trivial, we prove a generalizati

Wen-Li Yang, Yao-Zhong Zhang

We study the level-one irreducible highest weight representations of $U_q[\hat{gl(1|1)}]$ and associated q-vertex operators. We obtain the exchange relations satisfied by the vertex operators. The characters and supercharacters associated with these irreducible representations are calculated.

R. A. Janik, R. Peschanski

We consider small angle and large impact parameter high energy scattering of colourless states in SYM using the AdS/CFT correspondence. The gauge theory scattering amplitude is linked with a correlation function of tilted Wilson loops, which can be calculated by the exchange of bulk supergravity fields between the two corresponding string worldsheets. We ide

Paolo Valtancoli

We derive a perturbative scheme to treat the interaction between point sources and AdS-gravity. The interaction problem is equivalent to the search of a polydromic mapping $X^A= X^A(x^μ)$, endowed with 0(2,2) monodromies, between the physical coordinate system and a Minkowskian 4-dimensional coordinate system, which is however constrained to live on a hypers

Leszek Hadasz

We calculate (using zeta function regularization) the Casimir energy of the rotating Nambu-Goto string with the Gauss-Bonnet term in the action and point-like masses at the ends. The resulting value turns out to be negative for all values of the parameters of the model.

Tim M. P. Tait

The mechanism of the electroweak symmetry-breaking (EWSB) is studied in the context of the heavy top quark, whose large mass may provide a clue as to the mechanism which generates the mass of the $W^\pm$ and $Z$ bosons. As a result, it seems quite likely that the top quark may be special in the sense that it is involved in dynamics not experienced by the lig

Miklos Gyulassy, Peter Levai, Ivan Vitev

The modification and amplification of the gluon angular distribution produced along with hard jets in nuclear collisions is computed. We consider the limit of a thin quark-gluon plasma, where the number of rescatterings of the jet and gluons is small. The focus is on jet quenching associated with the formation of highly off-shell partons in hard scattering e

R. Fiore, A. Flachi, L. L. Jenkovszky, F. Paccanoni

We consider proton diffraction dissociation in the dipole Pomeron model, where the Pomeron is represented by a double pole in the $J-$plane, and show that unitarity can be satisfied without decoupling of the triple Pomeron vertex. Differential and total diffractive cross sections for the reaction $\bar{p}+p \to \bar{p}+X$ are analyzed and reproduced in this

John Ellis

Various issues in neutrino phenomenology are reviewed, including: the possibility of large mixing angles in various models for neutrino masses, difficulties for degenerate neutrinos as candidates for hot dark matter, strategies for discriminating between different oscillation interpretations of the atmospheric and solar neutrino anomalies, the programme of w

Mario Franz, Hyun-Chul Kim, Klaus Goeke

We present in this talk the recent investigation of the effective weak chiral Lagrangian within the framework of the instanton-induced chiral quark model. The low energy constants in leading order $g_8$ and $g_{27}$, and their ratio are determined. The momentum-dependence of the constituent quark mass turns out to improve the low energy constants to the grea

M. Caselle, M. Hasenbusch, P. Provero

We study the spectrum of massive excitations of the three-dimensional phi^4 and Ising models, in the broken-symmetry phase. Using a variational method, we show that the spectrum contains all the 0+ states that one expects from duality with the glueball spectrum of the Z(2) gauge model. From the point of view of continuum phi^4 theory, we show that at least o

R. Appel

A large low-background sample of events (10300) has been collected for the rare decay of kaons in flight K+ -> pi+ e+ e- by experiment E865 at the Brookhaven AGS. The decay products were accepted by a broad band high-resolution charged particle spectrometer with particle identification. The branching ratio (2.94 +- 0.05(stat.) +- 0.13(syst.) +- 0.05(model))*

I. S. Booth, R. B. Mann

We extend the quasilocal formalism of Brown and York to include electromagnetic and dilaton fields and also allow for spatial boundaries that are not orthogonal to the foliation of the spacetime. The extension allows us to study the quasilocal energy measured by observers who are moving around in a spacetime. We show that the quasilocal energy transforms wit

Humberto Salazar, Ruben Cordero

A class of stationary rigidly rotating perfect fluid coupled with non-linear electromagnetic fields was investigated. An exact solution of the Einstein equations with sources for the Carter B(+) branch was found, for the equation of state $3p + ε= constant$. We use a structural function for the Born-Infeld non-linear electrodynamics which is invariant under

Debasis Dan, Mangal C. Mahato, A. M. Jayannavar

The mobility of an overdamped particle, in a periodic potential tilted by a constant external field and moving in a medium with periodic friction coefficient is examined. When the potential and the friction coefficient have the same periodicity but have a phase difference, the mobility shows many interesting features as a function of the applied force, the t

D. Thirumalai

The impact of two landmark papers one by Edwards and the other by de Gennes on the field of polymer physics is highlighted.

S. Pliberšek, P. F. Meier

The nuclear quadrupole resonance (NQR) spectrum of strontium doped La$_2$CuO$_4$ surprisingly resembles the NQR spectrum of La$_2$CuO$_4$ doped with excess oxygen, both spectra being dominated by a main peak and one principal satellite peak at similar frequencies. Using first-principles cluster calculations this is investigated here by calculating the electr

A. Morello, A. G. M. Jansen, R. S. Gonnelli, S. I. Vedeneev

The irreversible magnetization of the layered high-T_{c} superconductor Bi_{2+x}Sr_{2-(x+y)}Cu_{1+y}O_{6 +- delta} (Bi-2201) has been measured by means of a capacitive torquemeter up to B=28 T and down to T=60 mK. No magnetization jumps, peak effects or crossovers between different pinning mechanisms appear to be present. The deduced irreversibility field B_

W. Westerburg, F. Martin, G. Jakob, P. J. M. van Bentum

We measured the temperature dependence of the linear high field Hall resistivity of La_0.67Ca_0.33MnO_3 (T_C=232K) and La_0.67Sr_0.33MnO_3 (T_C=345K) thin films in the temperature range from 4K up to 360K in magnetic fields up to 20T. At low temperatures we find a charge carrier density of 1.3 and 1.4 holes per unit cell for the Ca- and Sr-doped compound, re

F. C. Alcaraz, R. Z. Bariev

We consider the exact solution of a model of correlated particles, which is presented as a system of interacting XX and Fateev-Zamolodchikov chains. This model can also be considered as a generalization of the multiband anisotropic $t-J$ model in the case we restrict the site occupations to at most two electrons. The exact solution is obtained for the eigenv

V. Bruyndoncx, L. Van Look, M. Verschuere, V. V. Moshchalkov

Superconducting structures with the size of the order of the superconducting coherence length xi(T) have a critical temperature T_c, oscillating as a function of the applied perpendicular magnetic field H (or flux Phi). For a thin-wire superconducting loop, the oscillations in T_c are perfectly periodic with H (this is the well-known Little-Parks effect), wh

Martin Ahr, Michael Biehl, Robert Urbanczik

We investigate zero temperature Gibbs learning for two classes of unrealizable rules which play an important role in practical applications of multilayer neural networks with differentiable activation functions: classification problems and noisy regression problems. Considering one step of replica symmetry breaking, we surprisingly find that for sufficiently

R. Baviera

We consider a new approach to portfolio selection in presence of transaction costs which allows to map the problem into one without costs. The proposed approach connects all the quantities of interest to exit times and probabilities to reach barriers. This leads to analytic results in the Wiener case and to directly measurable quantities on a historical data

M. Barranco, M. Guilleumas, D. M. Jezek, R. J. Lombard

We present a study of phase separation from supersaturated 3He-4He liquid mixtures at low temperatures addressing both the degree of critical supersaturation Dx and the thermal-to-quantum crossover temperature T* for the nucleation process. Two different nucleation seeds are investigated, namely 3He droplets and 4He vortex lines with cores filled with 3He. W

S. A. Sergeenkov, V. V. Gridin, M. Ausloos

A method, using a Corbino disk sample geometry, is described and applied to study of resistive tails of sintered $YBCO$. When the transport current passes radially from the rim of the disk sample to its center, the two component potential drop signal is detected below $T_c$, which is due to (i) quasiparticles $W_q$ and (ii) vortex-core-motion related contrib

Gyorgy Szabo, M. A. Santos, J. F. F. Mendes

The evolution of domain structure is investigated in a two-dimensional voter model with three states under cyclic dominance. The study focus on the dynamics of vortices, defined by the points where three states (domains) meet. We can distinguish vortices and antivortices which walk randomly and annihilate each other. The domain wall motion can create vortex-

Jason K. Perry, Jamil Tahir-Kheli

Previously we showed the major effect of electron correlation in the cuprate superconductors is to lower the energy of the Cu d_x^2-y^2/O p_sigma (x^2-y^2) band with respect to the Cu d_z^2/O' p_z (z^2) band. In our 2D Hubbard model for La_1.85Sr_0.15CuO_4 (LaSCO), the z^2 band is narrow and crosses the standard x^2-y^2 band just below the Fermi level. I

D. F. Agterberg, Victor Barzykin, Lev P. Gor'kov

We consider the effect of isotropic impurity scattering on the exotic superconducting states that arise from the usual BCS mechanism in substances of cubic and hexagonal symmetry where the Fermi surface contains inequivalent but degenerate pockets (e.g. around several points of high symmetry). As examples we look at CeCo$_2$, CeRu$_2$, and LaB$_6$; all of wh

Dirk Drasdo

Growth and folding in one-layered model tissue sheets are studied in a stochastic, lattice-free single cell model which considers the discrete cellular structure of the tissue, and a coarse grained analytical approach. The polarity of the tissue sheet is considered by a bending term. Cell division gives rise to a locally increasing metric. An exponential and

Michael Junk, S. V. Raghurama Rao

The relation between Latttice Boltzmann Method, which has recently become popular, and the Kinetic Schemes, which are routinely used in Computational Fluid Dynamics, is explored. A new discrete velocity model for the numerical solution of the Navier-Stokes equations for incompressible fluid flow is presented by combining both the approaches. The new scheme c

M. Wilkinson, B. Mehlig

It might be anticipated that there is statistical universality in the long-time classical dynamics of chaotic systems, corresponding to the universal correspondence of their quantum spectral statistics with random matrix models. We argue that no such universality exists. We discuss various statistical properties of long period orbits: the distribution of the

Jerome Plumecoq, Marc Lefranc

We give numerical evidence of the validity of a previously described algorithm for constructing symbolic encodings of chaotic attractors from a template analysis. We verify that the different solutions that can be found are dynamically equivalent, and that our approach yields results that are consistent with those obtained from methods based on homoclinic ta

Jerome Plumecoq, Marc Lefranc

We present a detailed algorithm to construct symbolic encodings for chaotic attractors of three-dimensional flows. It is based on a topological analysis of unstable periodic orbits embedded in the attractor and follows the approach proposed by Lefranc et al. [Phys. Rev. Lett. 73, 1364 (1994)]. For each orbit, the symbolic names that are consistent with its k

TING, Juhi-Lian Julian

Short comment for a recent paper, suggesting for some directions related to previous studies in chaotic dynamics.

D. S. Reed, B. Balick, A. R. Hajian, T. L. Klayton

The optical expansion parallax of NGC 6543 has been detected and measured using two epochs of HST images separated by a time baseline of only three years. We have utilized three separate methods of deriving the angular expansion of bright fiducials, the results of which are in excellent agreement. We combine our angular expansion estimates with spectroscopic

Graca Rocha

This paper covers several techniques of intercomparison of Cosmic Microwave Background (CMB) anisotropy experiments and models of structure formation. It presents the constraints on several cosmological parameters using current CMB observations.

Robert V. Wagoner, Alexander S. Silbergleit

Compton scattering by a locally plane parallel atmosphere is analyzed within the Kompaneets approximation. In contrast to almost all previous analytic calculations of inverse Compton scattering, we assume neither homogeneity nor isotropy of the photon distribution. However, we do adopt an assumed angular distribution of the photons. For any specified energy

T. Sivarani, M. Parthasarathy, P. Garcia-Lario, A. Manchado

From an analysis of the spectrum (4000Åto 8800Å) of HD~101584 it is found that most of the neutral and single ionized metallic lines are in emission. The forbidden emission lines of [OI] 6300Åand 6363Åand [CI] 8727Åare detected, which indicate the presence of a very low excitation nebula. The H$α$, FeII 6383Å, NaI D$_{1}$, D$_{2}$ lines and the CaII IR tripl

V. C. Bailey, M. B. Davies

We simulate collisions involving red-giant stars in the centre of our galaxy. Such encounters may explain the observed paucity of highly luminous red giants within the central 0.2pc. The masses of the missing stars are likely to be in the range 2 to 8 solar masses. Recent models of the galactic centre cluster's density and velocity distributions are used

Lawrence M. Krauss

I review here recent developments which have affected our understanding of both the absolute age of globular clusters and the uncertainties in this age estimate, and comment on the implications for cosmological models. This present estimate is in agreement with the range long advocated by David Schramm. The major uncertainty in determining ages of globular c

D. P. Finkbeiner, D. J. Schlegel

This chapter discusses Galactic dust and how its thermal emission confuses CMBR measurements. Interstellar dust grains are composed of many differing species, and observational evidence has only begun to disentagle their composition and sizes. Fortunately, their far-IR/millimeter emission is less complex. We describe how a very simple two-species model can d

Noam Soker

In a recent work Ciardullo et al. (1999) list 19 planetary nebulae surveyed by the Hubble Space Telescope for the presence of resolved visual binary companions of their central stars. For ten planetary nebulae they argue for probable physical association of the resolved stars with the central stars, while for nine the association is less likely. Such stellar

R. Weinberger, S. Temporin, F. Kerber

We present the discovery of an isolated compact group of galaxies that is extremely dense (median projected galaxy separation: 6.9 kpc), has a very low velocity dispersion ($σ_{\rm 2D}$ = 67 km s$^{-1}$), and where all observed members show emission lines and are morphologically disturbed. These properties, together with the lack of spirals and the presence

Alan P. Smale, Erik Kuulkers

We present RXTE observations of LMC X-2 obtained during a five-day interval in 1997 December, during which the source was radiating at a mean intensity near the Eddington limit, and strongly variable on timescales of seconds to hours. The shapes of the X-ray color-color and hardness-intensity diagrams during the observations, the presence of VLFN and HFN in

Amri Wandel

We suggest that the growth of the central black hole in active galactic nuclei (AGN) due to the matter accreted over the AGN lifetime causes an evolution of the luminosity and spectrum. In a previous paper we have shown that the effective temperature of the UV continuum spectrum and the emission-line equivalent width are anti-correlated with the black-hole m