March 2000 arXiv papers — page 21

Nedra Mellouli, Bernadette Bouchon-Meunier

This paper proposes two kinds of fuzzy abductive inference in the framework of fuzzy rule base. The abductive inference processes described here depend on the semantic of the rule. We distinguish two classes of interpretation of a fuzzy rule, certainty generation rules and possible generation rules. In this paper we present the architecture of abductive infe

James P. Delgrande, Torsten Schaub, Hans Tompits

We describe an approach for compiling preferences into logic programs under the answer set semantics. An ordered logic program is an extended logic program in which rules are named by unique terms, and in which preferences among rules are given by a set of dedicated atoms. An ordered logic program is transformed into a second, regular, extended logic program

Bert Van Nuffelen

The SLDNFA-system results from the LP+ project at the K.U.Leuven, which investigates logics and proof procedures for these logics for declarative knowledge representation. Within this project inductive definition logic (ID-logic) is used as representation logic. Different solvers are being developed for this logic and one of these is SLDNFA. A prototype of t

Nikolay Pelov, Emmanuel De Mot, Maurice Bruynooghe

Many logic programming based approaches can be used to describe and solve combinatorial search problems. On the one hand there are definite programs and constraint logic programs that compute a solution as an answer substitution to a query containing the variables of the constraint satisfaction problem. On the other hand there are approaches based on stable

Maurice Bruynooghe

A logic programming paradigm which expresses solutions to problems as stable models has recently been promoted as a declarative approach to solving various combinatorial and search problems, including planning problems. In this paradigm, all program rules are considered as constraints and solutions are stable models of the rule set. This is a rather radical

James P. Delgrande, Torsten Schaub, Hans Tompits

This paper describes a system, called PLP, for compiling ordered logic programs into standard logic programs under the answer set semantics. In an ordered logic program, rules are named by unique terms, and preferences among rules are given by a set of dedicated atoms. An ordered logic program is transformed into a second, regular, extended logic program whe

Thomas Lukasiewicz

We propose a combination of probabilistic reasoning from conditional constraints with approaches to default reasoning from conditional knowledge bases. In detail, we generalize the notions of Pearl's entailment in system Z, Lehmann's lexicographic entailment, and Geffner's conditional entailment to conditional constraints. We give some examples t

Horacio Arlo-Costa

The paper studies the notion of supposition encoded in non-Archimedean conditional probability (and revealed in the acceptance of the so-called indicative conditionals). The notion of qualitative change of view that thus arises is axiomatized and compared with standard notions like AGM and UPDATE. Applications in the following fields are discussed: (1) theor

Samir Chopra, Konstantinos Georgatos, Rohit Parikh

We present a method for relevance sensitive non-monotonic inference from belief sequences which incorporates insights pertaining to prioritized inference and relevance sensitive, inconsistency tolerant belief revision. Our model uses a finite, logically open sequence of propositional formulas as a representation for beliefs and defines a notion of inference

Richard Booth

The connections between nonmonotonic reasoning and belief revision are well-known. A central problem in the area of nonmonotonic reasoning is the problem of default entailment, i.e., when should an item of default information representing "if A is true then, normally, B is true" be said to follow from a given set of items of such information. Many an

Thomas Meyer

Intelligent agents are often faced with the problem of trying to merge possibly conflicting pieces of information obtained from different sources into a consistent view of the world. We propose a framework for the modelling of such merging operations with roots in the work of Spohn (1988, 1991). Unlike most approaches we focus on the merging of epistemic sta

Raymond Lau, Arthur H. M. ter Hofstede, Peter D. Bruza

Learning and adaptation is a fundamental property of intelligent agents. In the context of adaptive information filtering, a filtering agent's beliefs about a user's information needs have to be revised regularly with reference to the user's most current information preferences. This learning and adaptation process is essential for maintaining th

Beom Jun Kim, Petter Minnhagen

We investigate numerically the critical current of two-dimensional fully frustrated arrays of resistively shunted Josephson junctions at zero temperature. It is shown that a domino-type mechanism is responsible for the existence of a critical current lower than the one predicted from the translationally invariant flux lattice. This domino mechanism is demons

Hangmo Yi, H. A. Fertig, R. Cote

We present an effective elastic theory which {\em quantitatively} describes the stripe phase of the two-dimensional electron gas in high Landau levels ($N\geq2$). The dynamical matrix is obtained with remarkably high precision from the density-density correlation function in the time-dependent Hartree-Fock approximation. A renormalization group analysis show

Peter Gillin, David Sherrington

In a recent Physics Review Letter, Dorlas and Wedagedera have studied the random energy model with an additional p-spin ferromagnetic interaction. Here we note that (i) we have solved the corresponding problem of a spherical spin system with p-spin glass interactions and r-spin ferromagnetic interactions, and (ii) a simple mapping yields the results of DW an

Yohannes Shiferaw, Yadin Y. Goldschmidt

We present an exactly solvable model of a Gaussian (flexible) polymer chain in a quenched random medium. This is the case when the random medium obeys very long range quadratic correlations. The model is solved in $d$ spatial dimensions using the replica method, and practically all the physical properties of the chain can be found. In particular the differen

Elihu Abrahams, C. M. Varma

Recent angular-resolved photoemission experiments on high-temperature superconductors are consistent with a phenomenological description of the normal state of these materials as Marginal Fermi Liquids. The experiments also provide constraints on microscopic theories

K. Levin, Qijin Chen, Ioan Kosztin

On the basis of the observed short coherence lengths in the cuprates we argue that a BCS-Bose-Einstein condensation (BEC) crossover approach is an appropriate starting point for correcting the mean field approach of BCS and, thereby, for addressing pseudogap phenomena in these materials. Our version of the BCS-BEC approach is based on a particular Greens&#39

Wonkee Kim, J. P. Carbotte

We calculate the $c$-axis kinetic energy difference between normal and superconducting state for coherent and for incoherent interlayer coupling between CuO$_{2}$ planes. For coherent coupling the ratio of the missing conductivity spectral weight to the superfluid density is equal to one and there is no violation of the conventional sum rule, but for the inc

E. T. Seppala, V. I. Raisanen, M. J. Alava

The roughness properties of two-dimensional fracture surfaces as created by the slow failure of random fuse networks are considered and compared to yield surfaces of perfect plasticity with similar disorder. By studying systems up to a linear size L=350 it is found that in the cases studied the fracture surfaces exhibit self-affine scaling with a roughness e

J. A. Acebron, L. L. Bonilla, R. Spigler

A model for synchronization of globally coupled phase oscillators including ``inertial'' effects is analyzed. In such a model, both oscillator frequencies and phases evolve in time. Stationary solutions include incoherent (unsynchronized) and synchronized states of the oscillator population. Assuming a Lorentzian distribution of oscillator natural fr

L. Golubovic, T. C. Lubensky, C. S. O'Hern

Under appropriate conditions, mixtures of cationic and neutral lipids and DNA in water condense into complexes in which DNA strands form local 2D smectic lattices intercalated between lipid bilayer membranes in a lamellar stack. These lamellar DNA-cationic-lipid complexes can in principle exhibit a variety of equilibrium phases, including a columnar phase in

P. Christ, W. Biberacher, M. V. Kartsovnik, E. Steep

We present systematic magnetic torque studies of the ``magnetic field - temperature'' phase diagram of the layered organic conductor alpha-(BEDT-TTF)2KHg(SCN)4 at fields nearly perpendicular and nearly parallel to the highly conducting plane. The shape of the phase diagram is compared to that predicted for a charge-density-wave system in a broad fiel

Sven E. Krüger, Johannes Richter, Jörg Schulenburg, Damian J. J. Farnell

We study the zero-temperature phase diagram and the low-lying excitations of a square-lattice spin-half Heisenberg antiferromagnet with two types of regularly distributed nearest-neighbour exchange bonds (J>0 (antiferromagnetic) and J&#39;>0, J&#39;<0) using the coupled cluster method (CCM) for high orders of approximation (up to LSUB8). We use a Neel model

A. Weisse, H. Fehske, G. Wellein, A. R. Bishop

We propose a new optimized phonon approach for the numerical diagonalization of interacting electron-phonon systems combining density-matrix and Lanczos algorithms. We demonstrate the reliablity of this approach by calculating the phase diagram for bi-polaron formation in the one-dimensional Holstein-Hubbard model, and the Luttinger parameters for the metall

Livio Marangio, Alessandro Ramponi, Massimo Bernaschi

Fixed income markets share many features with the equity markets. However there are significant differences as well and many attempts have been done in the past to develop specific tools which describe (and possibly forecasts) the behavior of such markets. For instance, a correct pricing of fixed income securities with fixed cache flows requires the knowledg

Ludovic Berthier

We study analytically the aging dynamics of the O(n) model in the large-n limit, with conserved and with non-conserved order parameter. While in the non-conserved dynamics, the autocorrelation function scales in the usual way C(t,tw) = C(t/tw), in the case of a conserved order parameter, `multiscaling&#39; manifests itself in the form C(t,tw) = C (h(t)/h(tw)

Tatsuto Murayama, Yoshiyuki Kabashima, David Saad, Renato Vicente

A variation of Gallager error-correcting codes is investigated using statistical mechanics. In codes of this type, a given message is encoded into a codeword which comprises Boolean sums of message bits selected by two randomly constructed sparse matrices. The similarity of these codes to Ising spin systems with random interaction makes it possible to assess

V. Falko, S. V. Iordanski, A. Kashuba

We report on study of low-energy excitations in a bilayer hetero-structure 2D electron gas. We split the bilayer Hamiltonian into SU(4)-symmetric part and the anisotropy part and treat the latter as a perturbation. We find that both Goldstone and the charged excitations - skyrmions - are goverened by the non-linear Sigma Model. We calculate the anisotropic e

Guang-Shan Tian, Lei-Han Tang, Qing-Hu Chen

To describe the crossover from the bulk BCS superconductivity to a fluctuation-dominated regime in ultrasmall metallic grains, new order parameters and correlation functions, such as ``parity gap&#39;&#39; and ``pair-mixing correlation function&#39;&#39;, have been recently introduced. In this paper, we discuss the small-grain behaviour of the Penrose-Onsage

D. N. Sheng, Z. Y. Weng, X. G. Wen

The fate of integer quantum Hall effect (IQHE) at weak magnetic field is studied numerically in the presence of {\it correlated} disorders. We find a systematic {\it float-up} and {\it merging} picture for extended levels on the low-energy side which results in direct transitions from higher-plateau IQHE states to the insulator. Such direct transitions are c

J. Röhler

Oxygen doping in metallic YBa_2Cu_3O_x induces quadrupolar &#34;alpha-ortho&#39;&#39;, and breathing &#34;beta-ortho&#34; deformations of the CuO_2 planes. Breathing beta-ortho deformations favour hybridizations of the pd sigma Cu3d_x^2-y^2 - O2p_x,y with the pd pi Cu3d_x,z, 3d_y,z-O2p_z bands relaxing the confinement of the carriers in the overdoped regime,

Anupam Garg

The WKB and instanton answers for the tunnel splitting of the ground state in a symmetric double well potential are both reduced to an expression involving only the functionals of the potential, without the need for solving any auxilliary problems. This formula is applied to simple model problems. The prefactor for the splitting in the text book by Landau an

Anupam Garg

The perfect quenching of spin tunneling that has previously been discussed in terms of interfering instantons, and has recently been observed in the magnetic molecule \Fe8, is treated using a discrete phase integral (or Wentzel-Kramers-Brillouin) method. The simplest model Hamiltonian for the phenomenon leads to a Schrödinger equation that is a five-term rec

Nie Luo

Transport properties of high transition temperature (high Tc) cuprate superconductors are investigated within a two-band model. The doping dependent Hall coefficients of La_{2-x}Sr_xCuO_4 (LSCO) and Nd_{2-x}Ce_xCuO_4 (NCCO) are explained by assuming the coexistence of two carriers with opposite charges, loosely speaking electrons (e) and holes (h). Such a po

Anita L. Cochran, William D. Cochran, Edwin S. Barker

We observed comets 122P/1995\,S1 (deVico) and C/1995\,O1 (Hale-Bopp) with high spectral resolving power in order to determine the ratio of N$_2^+$/CO$^+$ in their comae. While we clearly detected the CO$^+$ in both of these comets, no N$_2^+$ was detected in either comet. From these spectra, we derive sensitive upper limits for N$_2^+$/CO$^+$. These upper li

R. Howe, J. Christensen-Dalsgaard, F. Hill, R. W. Komm

Helioseismic observations have detected small temporal variations of the rotation rate below the solar surface corresponding to the so-called `torsional oscillations&#39; known from Doppler measurements of the surface. These appear as bands of slower and faster than average rotation moving equatorward. Here we establish, using complementary helioseismic obse

D. Jones, R. Allen, J. Basart, T. Bastian

At sufficiently low frequencies, no ground-based radio array will be able to produce high resolution images while looking through the ionosphere. A space-based array will be needed to explore the objects and processes which dominate the sky at the lowest radio frequencies. An imaging radio interferometer based on a large number of small, inexpensive satellit

D. L. Jones, A. E. Wehrle, B. G. Piner, D. L. Meier

The physical conditions in the inner parsec of accretion disks believed to orbit the central black holes in active galactic nuclei can be probed by imaging the absorption of background radio emission by ionized gas in the disk. We report high angular resolution observations of the nearby galaxy NGC 4261 which show evidence for free-free absorption by a thin,

P. G. Ostrov, E. Lapasset, N. I. Morrell

We present a V light curve of the eclipsing binary system HV 2543 (Sk-67 117) in the Large Magellanic Cloud based on CCD images acquired between the years 1995 and 1998. We have analysed this light curve and published radial velocity data, finding that this system is semidetached, with the secondary (less massive and less luminous component) filling its Roch

James M. Stone, Philip E. Hardee

We present the results of a series of axisymmetric time-dependent magnetohydrodynamic (MHD) simulations of the propagation of cooling, overdense jets, motivated by the properties of outflows associated with young stellar objects. A variety of initial field strengths and configurations are explored for both steady and time-variable (pulsed) jets. Even apparen

Solange V. Ramirez, Andrew Stephens, Jay. A. Frogel, D. L. DePoy

We present K-band spectra of more than 110 M giants in Galactic bulge fields interior to -4 degrees and as close as 0.2 degrees of the Galactic Center. From the equivalent widths of three features in these spectra, EW(Na),EW(Ca), and EW(CO) we calculate [Fe/H] for the stars with a calibration derived from globular clusters Stephens et al (2000). The mean [Fe

Barbara J. Anthony-Twarog, Ata Sarajedini, Timothy C. Beers, Bruce A. Twarog

CCD photometry on the uvbyCa system has been obtained for 521 candidate metal-poor stars from the northern hemisphere HK survey of Beers and colleagues. Reddening corrections, classifications of stars by luminosity class, and the derivation of metal abundances based on Stromgren indices m1 and hk are described and presented, along with preliminary spectrosco

X. Hernandez, David Valls-Gabaud, Gerard Gilmore

We use data from the Hipparcos catalogue to construct colour-magnitude diagrams for the solar neighbourhood, which are then treated using advanced Bayesian analysis techniques to derive the star formation history, $SFR(t)$, of this region over the last 3 Gyr. The method we use allows the recovery of the underlying $SFR(t)$ without the need of assuming any {\

Michael J. Kurtz, Douglas J. Mink

We develop a new method for estimating and removing the spectrum of the sky from deep spectroscopic observations; our method does not rely on simultaneous measurement of the sky spectrum with the object spectrum. The technique is based on the iterative subtraction of continuum estimates and Eigenvector sky models derived from Singular Value Decompositions (S

Smita Mathur

Narrow Line Seyfert 1 galaxies (NLS1s) are intriguing due to their continuum as well as emission line properties. The observed peculiar properties of the NLS1s are believed to be due to accretion rate close to Eddington limit. As a consequence, for a given luminosity, NLS1s have smaller black hole (BH) masses compared to normal Seyfert galaxies. Here we argu

C. Bruens, J. Kerp, P. M. W. Kalberla, U. Mebold

We present new observational results on high-velocity clouds (HVCs) based on an analysis of the Leiden/Dwingeloo HI survey. We cataloged all HVCs with NHI > 1 10^19 cm^-2 and found 252 clouds that form a representative flux limited sample. The detailed analysis of each individual HVC in this sample revealed a significant number of HVCs (nearly 20%) having si

Gregory Rudnick, Hans-Walter Rix, Robert C. Kennicutt

To investigate the link between weak tidal interactions in disk galaxies and the boosting of their recent star formation, we obtain images and spatially integrated spectra (3615A < lambda < 5315A) for 40 late-type spiral galaxies (Sab-Sbc) with varying degrees of lopsidedness (a dynamical indicator of weak interactions). We quantify lopsidedness as the ampli

S. Collin, A. Abrassart, B. Czerny, A. -M. Dumont

The main characteristics of the average spectrum of radio quiet AGN in the UV and X-ray range are reviewed, and the emission mechanisms are discussed in the framework of accretion disk models, in particular the ``irradiated cold relativistic disk&#34;. It is shown that some problems arise in confronting the predictions of the model to the observations. We pr

K. Ohta, T. Matsumoto, T. Maihara, F. Iwamuro

Results of a narrow-band imaging for the redshifted [OII]3727 emission around a quasar at z=4.7 obtained with the Subaru telescope and CISCO (a Cassegrain near infrared camera) are presented. A significant emission line is detected in the narrow-band H_2 (v=1-0 S(1)) filter at a location 2.4&#34; northwest from the quasar, where the presence of a companion h

G. A. Prodi, I. S. Heng, Z. A. Allen, P. Astone

The International Gravitational Event Collaboration, IGEC, is a coordinated effort by research groups operating gravitational wave detectors working towards the detection of millisecond bursts of gravitational waves. Here we report on the current IGEC resonant bar observatory, its data analysis procedures, the main properties of the first exchanged data set.

T. C. Beers, M. Chiba, Y. Yoshii, I. Platais

We present a revised catalog of 2106 Galactic stars, selected without kinematic bias, and with available radial velocities, distance estimates, and metal abundances in the range 0.0 <= [Fe/H] <= -4.0. This update of the Beers and Sommer-Larsen (1995) catalog includes newly-derived homogeneous photometric distance estimates, revised radial velocities for a nu

David P. Bennett, Sun Hong Rhie

We present a conceptual design for a space based Galactic Exoplanet Survey Telescope (GEST) which will use the gravitational microlensing technique to detect extra solar planets with masses as low as that of Mars at all separations >~ 1 AU. The microlensing data would be collected by a diffraction limited, wide field imaging telescope of ~ 1.5m aperture equi

G. Dvali, G. Gabadadze, M. Porrati

Theories with infinite volume extra dimensions open exciting opportunities for particle physics. We argued recently that along with attractive features there are phenomenological difficulties in this class of models. In fact, there is no graviton zero-mode in this case and 4D gravity is obtained by means of continuum bulk modes. These modes have additional d

Z. Tavassoli, A. Esmaeilnia Shirvani

Two models of binary fragmentation are introduced in which a time dependent transition size produces two regions of fragment sizes above and below the transition size. In the models we consider a fixed rate of fragmentation for the largest fragment and two different rates of fragmentation for the two regions of sizes above and below the transition size. The

M. Veselsky, R. W. Ibbotson, R. Laforest, E. Ramakrishnan

We have created quasiprojectiles of varying isospin via peripheral reactions of 28Si + 112Sn and 124Sn at 30 and 50 MeV/nucleon. The quasiprojectiles have been reconstructed from completely isotopically identified fragments. The difference in N/Z of the reconstructed quasiprojectiles allows the investigation of the disassembly as a function of the isospin of

Yang Sun, Cheng-Li Wu, Kumar Bhatt, Mike Guidry

We show that a nearly perfect SU(3) symmetry emerges from an extended Projected Shell Model. Starting from a deformed potential we construct separate bases for neutron and proton collective rotational states by exact angular momentum projection. These rotational states are then coupled by diagonalizing a residual pairing plus quadrupole interaction. The stat

M. Veselsky, R. W. Ibbotson, R. Laforest, E. Ramakrishnan

A dependence of the isobaric ratio Y(3H)/Y(3He) on the N/Z ratio of the reconstructed quasiprojectile for the reaction of 28Si beam with 112,124Sn targets at two different projectile energies 30 and 50 MeV/nucleon is presented. We demonstrate a linear dependence of ln(Y(3H)/Y(3He)) on the quasiprojectile N/Z ratio and show the dependence of the slope on reco

M. Lopez-Quelle, N. Van Giai, S. Marcos, and L. N. Savushkin

The splitting of single-particle energies between spin-orbit partners in nuclei is examined in the framework of different self-consistent approachs, non-relativistic as well as relativistic. Analytical expressions of spin-orbit potentials are given for various cases. Proton spin-orbit splittings are calculated along some isotopic chains (O, Ca, Sn) and they

S. M. Barr, Ilja Dorsner

A classification of models with three light neutrinos is given. This classification includes virtually all of the three-neutrino models proposed in the last few years, of which there are approximately one hundred. The essential ideas, attractive features, and characteristic problems of the different classes of model are discussed. The classification is based

Peter Lemmens, M. Grove, M. Fischer, G. Guntherodt

We present a Raman light scattering study of the two-dimensional quantum spin system SrCu2(BO3)2 and show that the magnetic excitation spectrum has a rich structure, including several well-defined bound state modes at low temperature, and a scattering continuum and quasielastic light scattering contributions at high temperature. The key to the understanding

S. W. Hawking, T. Hertog, H. S. Reall

We study a Randall-Sundrum cosmological scenario consisting of a domain wall in anti-de Sitter space with a strongly coupled large $N$ conformal field theory living on the wall. The AdS/CFT correspondence allows a fully quantum mechanical treatment of this CFT, in contrast with the usual treatment of matter fields in inflationary cosmology. The conformal ano

Sergio Ferrara, Emery Sokatchev

We derive short UIR&#39;s of the OSp(8/4,R) superalgebra of 3d N=8 superconformal field theories by the requirement that the highest weight states are annihilated by a subset of the super-Poincare odd generators. We then find a superfield realization of these BPS saturated UIR&#39;s as &#34;composite operators&#34; of the two basic ultrashort &#34;supersingl

Carlo Angelantonj, Adi Armoni

We discuss the role of the dilaton tadpole in the holographic description of non-supersymmetric gauge theories that are conformal in the planar limit. On the string theory side, the presence of the dilaton tadpole modifies the AdS background inducing a logarithmic running for the radius and the dilaton. Using the holographic prescription we compute the Wilso

Ehud Behar, Jean Cottam, Steven M. Kahn

An analysis of the iron L-shell emission in the publicly available spectrum of the Capella binary system, as obtained by the High Energy Transmission Grating Spectrometer on board the Chandra X-ray Observatory, is presented. The atomic-state model, based on the HULLAC code, is shown to be especially adequate for analyzing high-resolution x-ray spectra of thi

F. Tafuri, J. R. Kirtley

We have observed spontaneous magnetic moments with random signs in c-axis oriented thin films of the high-Tc cuprate superconductor YBCO, imaged with a scanning SQUID microscope. These moments arise when the samples become superconducting, and appear to be associated with non-ferromagnetic defects in the films. In contrast with granular high-Tc samples, whic

C. Ungarelli, A. Vecchio

Gravitational wave experiments will play a key role in the investigation of the frontiers of cosmology and the structure of fundamental fields at high energies, by detecting, or setting strong upper-limits to, the primordial gravitational wave background produced in the early-Universe. Here we discuss the impact of space-borne laser interferometric detectors

Piero Madau

In popular cosmological scenarios, some time beyond a redshift of 10, stars within protogalaxies created the first heavy elements; these systems, together perhaps with an early population of quasars, generated the ultraviolet radiation and mechanical energy that reheated and reionized the cosmos. The history of the Universe during and soon after these crucia

Michele Caselle, Martin Hasenbusch, Andrea Pelissetto, Ettore Vicari

We compute the renormalized four-point coupling in the 2d Ising model using transfer-matrix techniques. We greatly reduce the systematic uncertainties which usually affect this type of calculations by using the exact knowledge of several terms in the scaling function of the free energy. Our final result is g4=14.69735(3).

Ralf Schützhold

A canonical particle definition via the diagonalisation of the Hamiltonian for a quantum field theory in specific curved space-times is presented. Within the provided approach radial ingoing or outgoing Minkowski particles do not exist. An application of this formalism to the Rindler metric recovers the well-known Unruh effect. For the situation of a black h

L. M. Baker, D. B. Fairlie

This article seeks to relate a recent proposal for the association of a covariant Field Theory with a string or brane Lagrangian to the Hamilton-Jacobi formalism for strings and branes. It turns out that since in this special case, the Hamiltonian depends only upon the momenta of the Jacobi fields and not the fields themselves, it is the same as a Lagrangian

Jizhong Lou, Tao Xiang, Zhaobin Su

The magnetic susceptibility and specific heat of the one-dimensional S=1 bilinear-biquadratic Heisenberg model are calculated using the transfer matrix renormalization group. By comparing the results with the experimental data of ${\rm LiVGe_2O_6}$ measured by Millet et al. (Phys. Rev. Lett. {\bf 83}, 4176 (1999)), we find that the susceptibility data of thi

S. Fukae, C. S. Kim, T. Yoshikawa

The effects of non-local interactions in rare B decays, $\Bsll$, are investigated. We show the correlation between the branching ratio and the forward-backward asymmetry via two coefficients of the non-local interactions. This will certainly help us find any deviations from the standard model through the non-local interactions.

R. Escribano, F. S. Ling, M. H. G. Tytgat

We study the temperature dependence of the eta and eta&#39; meson masses within the framework of U(3)_L x U(3)_R chiral perturbation theory, up to next-to-leading order in a simultaneous expansion in momenta, quark masses and number of colours. We find that both masses decrease at low temperatures, but only very slightly. We analyze higher order corrections

Angelica de Oliveira-Costa, Max Tegmark, Mark J. Devlin, L. M. Haffner

We quantify the level of foreground contamination in the QMAP Cosmic Microwave Background (CMB) data with two objectives: (a) measuring the level to which the QMAP power spectrum measurements need to be corrected for foregrounds and (b) using this data set to further refine current foreground models. We cross-correlate the QMAP data with a variety of foregro

Hongchen Fu, Yinqi Feng, A. I. Solomon

The paper has been withdraw by authors

Julia Kempe, Christoph Simon, Gregor Weihs

We show that optimal universal cloning of the polarization state of photons can be achieved via stimulated emission in three-level systems, both of the Lambda and the V type. We establish the equivalence of our systems with coupled harmonic oscillators, which permits us to analyze the structure of the cloning transformations realized. These transformations a

X. X. Yi, C. P. Sun

The unitary evolution can be represented by a finite product of exponential operators. It leads to a perturbative expression of the density operator of a close system. Based on the perturbative expression scheme, we present a entanglement measure, this measure has the advantage that it is easy to compute for a general dynamical process.

Satoshi Ishizaka, Tohya Hiroshima

We propose novel mixed states in two qubits, ``maximally entangled mixed states&#39;&#39;, which have a property that the amount of entanglement of these states cannot be increased further by applying any unitary operations. The property is proven when the rank of the states is less than 4, and confirmed numerically in the other general cases. The correspond

C. S. Unnikrishnan

The long-standing puzzle of the nonlocal Einstein-Podolsky-Rosen correlations is resolved. The correct quantum mechanical correlations arise for the case of entangled particles when strict locality is assumed for the probability amplitudes instead of locality for probabilities. Locality of amplitudes implies that measurement on one particle does not collapse

J. C. Lemm

Bayesian field theory denotes a nonparametric Bayesian approach for learning functions from observational data. Based on the principles of Bayesian statistics, a particular Bayesian field theory is defined by combining two models: a likelihood model, providing a probabilistic description of the measurement process, and a prior model, providing the informatio

Josh P. Kemp, Ulrich H. E. Hansmann, Zheng Y. Chen

The similarity in the thermodynamic properties of two completely different theoretical models for the helix-coil transition is examined critically. The first model is an all-atomic representation for a poly-alanine chain, while the second model is a minimal helix-forming model that contains no system specifics. Key characteristics of the helix-coil transitio

B. Derrida, S. C. Manrubia, D. H. Zanette

If one goes backward in time, the number of ancestors of an individual doubles at each generation. This exponential growth very quickly exceeds the population size, when this size is finite. As a consequence, the ancestors of a given individual cannot be all different and most remote ancestors are repeated many times in any genealogical tree. The statistical

Emmanuel Centeno, Didier Felbacq

We exhibit the strong influence on light propagation of the finite size in photonic band-gap material. We show that light emission can be controlled by the symmetry group of the boundary of the finite device. These results lead simply to important practical applications.

Josiph Mladenov Rangelov

The physical model (PhsMdl) of the leptons is offered by means of the PhsMdls of the vacuum and electron,described in our recent works. It is assumed that the vacuum is consistent by dynamides, streamlined in junctions of some tight crystalline lattice. Every dynamide contains a neutral pair of massless point-like (PntLk) contrary elementary electric charges

Josiph Mladenov Rangelov

The physical model (PhsMdl) of the hadrons is offered by means of the obvious analogy with the transparent surveyed PhsMdls of the vacuum and leptons in our recent works. It is assumed that the vacuum is consistent by dynamides, streamlined in junctions of some tight crystalline lattice. Every dynamide contains a neutral pair of massless contrary point-like

S. Kondratyuk, O. Scholten

Pion-loop corrections for Compton scattering are calculated in a novel approach based on the use of dispersion relations in a formalism obeying unitarity. The basic framework is presented, including an application to Compton scattering. In the approach the effects of the non-pole contribution arising from pion dressing are expressed in terms of (half-off-she

Valerie Poulin, Hugo Touchette

A family of non-conjugate chaotic maps generalizing the well-known logistic function is defined, and some of its basic properties studied. A simple formula for the Lyapunov exponents of all the maps contained in this family is given based on the construction of conjugacies. Moreover, it is shown that, despite the dissimilarity of their polynomial expressions

E. Bogomolny, P. Leboeuf, C. Schmit

The statistical properties of a Hamiltonian $H_0$ perturbed by a localized scatterer are considered. We prove that when $H_0$ describes a bounded chaotic motion, the universal part of the spectral statistics are not changed by the perturbation. This is done first within the random matrix model. Then it is shown by semiclassical techniques that the result is

C. O. Weiss, G. Slekys, V. B. Taranenko, K. Staliunas

We describe experiments testing the existence and investigating the properties of spatial solitons in nonlinear resonators. We investigate the properties of stationary and moving spatial solitons in lasers with saturable absorber, with a subcritical bifurcation, as well as their manipulation. As opposed, spatial solitons relying on a supercritical bifurcatio

Pavel Etingof, Alexander Varchenko

The main object considered in this paper is the trace function, defined as a suitably normalized trace of a product of intertwining operators for the Drinfeld-Jimbo quantum group, multiplied by the exponential of an element of the Cartan subalgebra. This function depends of two parameters -- the element of the Cartan subalgebra, and the highest weight of the

Inna Sysoeva

This paper is the first part of a series of papers aimed at improving the classification by Formanek of the irreducible representations of Artin braid groups of small dimension. In this paper we classify all the irreducible complex representations $ρ$ of Artin braid group $B_n$ with the condition $rank (ρ(σ_i)-1)=2$ where $σ_i$ are the standard generators. F

Angelo Gilio

In this paper we consider the inference rules of System P in the framework of coherent imprecise probabilistic assessments. Exploiting our algorithms, we propagate the lower and upper probability bounds associated with the conditional assertions of a given knowledge base, automatically obtaining the precise probability bounds for the derived conclusions of t

R. N. Syzdykova, Kur. R. Myrzakul, G. N. Nugmanova, R. Myrzakulov

Some aspects of the multidimensional soliton geometry are considered.

P. Redparth

We give a spectral description of the semi-classical Schrodinger operator with a piecewise linear, complex valued potential. Moreover, using these results, we show how an arbitrarily small bounded perturbation of a non-self-adjoint operator can completely change the spectrum of the operator.

Rafał Latała, Krzysztof Oleszkiewicz

We establish a family of functional inequalities interpolating between the classical logarithmic Sobolev and Poincaré inequalities. We prove that they imply the concentration of measure phenomenon intermediate between Gaussian and exponential. Our bounds are close to optimal.

Luigi Grasselli, Michele Mulazzani

In this paper we show that all 3-manifolds of a family introduced by M. J. Dunwoody are cyclic coverings of lens spaces (eventually $\bf S^3$), branched over genus one 1-bridge knots. As a consequence, we give a positive answer to the Dunwoody conjecture that all the elements of a wide subclass are cyclic coverings of $\bf S^3$ branched over a knot. Moreover

Xiang-Mao Ding, Bo-Yu Hou, Liu Zhao

We propose a rational quantum deformed nonlocal currents in the homogenous space $SU(2)_k/U(1)$, and in terms of it and a free boson field a representation for the Drinfeld currents of Yangian double at a general level $k=c$ is obtained. In the classical limit $\hbar \to 0$, the quantum nonlocal currents become $SU(2)_k$ parafermion, and the realization of Y

Shun'ya Mizoguchi

Extending the seminal work of Bilal and Gervais, we construct a tachyon-free, modular invariant partition function for critical superstrings on four-dimensional Minkowski x two-dimensional black hole. This model may be thought of as an SL(2,R)/U(1) version of Gepner models and corresponds to a conifold point on the moduli space of Calabi-Yau compactification

Xiang-Mao Ding, Pei Wang

A construction of $W$-symmetries is given only in terms of the nonlocal fields (parafermions ${\ps}_{\al}$), which take values on the homogeneous space $G/U(1)^r$, where $G$ is a simply connected compact Lie group manifold (its accompanying Lie algebra ${\cal G}$ is a simple one of rank $r$). Only certain restriction of the root set of Lie algebra on which t