November 2000 arXiv papers — page 10

Gyeong Yun Jun, Pyung Seong Kwon

We discuss a new feature of the 5d Kaluza-Klein cosmology. For that purpose, we obtain the simplest x^5-dependent solution which, in the reduced description, is associated with a radiation-dominated Robertson-Walker universe, and also can be regarded as an extension of the Schwarzschild solution. This solution enables us to deduce an important result that an

Felix Ritort, Marta Sales

We present a constructive approach to obtain information about the compactness and shape of large-scale lowest excitations in disordered systems by studying order-parameter fluctuations (OPF) at low temperatures. We show that the parameter $G$ which measures OPF is 1/3 at T=0 provided the ground state is unique and the probability distribution for the lowest

Andrew R Liddle, Pedro T P Viana, A Kathy Romer, Robert G Mann

The redshift evolution of the galaxy cluster temperature function is a powerful probe of cosmology. However, its determination requires the measurement of redshifts for all clusters in a catalogue, which is likely to prove challenging for large catalogues expected from XMM--Newton, which may contain of order 2000 clusters with measurable temperatures distrib

Holger Schanz, Marc-Felix Otto, Roland Ketzmerick, Thomas Dittrich

We explain the mechanism leading to directed chaotic transport in Hamiltonian systems with spatial and temporal periodicity. We show that a mixed phase space comprising both regular and chaotic motion is required and derive a classical sum rule which allows to predict the chaotic transport velocity from properties of regular phase-space components. Transport

Rabin Banerjee, Biswajit Chakraborty

The translation group T(2), contained in Wigner's little group for massless particles, is shown to generate gauge transformations in the Kalb-Ramond theory, exactly as happens in Maxwell case. For the topologically massive ($B\wedge$F) gauge theory, both T(2) and T(3), act as the corresponding generators.

Yoshihiko Nonomura, Xiao Hu

The phase diagram for the vortex states of high-$T_{\rm c}$ superconductors with point defects in $\vec{B} \parallel c$ axis is drawn by large-scale Monte Carlo simulations. The vortex slush (VS) phase is found between the vortex glass (VG) and vortex liquid (VL) phases. The first-order transition between this novel normal phase and the VL phase is character

Shin'ichi Nojiri, Sergei D. Odintsov, Sachiko Ogushi

Holographic Renormalization Group (RG) in nine dimensions is considered. The d8 holographic conformal anomaly is found. It should correspond to d8 CFT in AdS_9/CFT_8 correspondence. The comparison of holographic and QFT anomalies in d8 de Sitter space is done. It may give the indication for rigorous AdS_9/CFT_8 correspondence proposal.

Tomoyuki Takenawa

A geometric approach to the equation found by Hietarinta and Viallet, which satisfies the singularity confinement criterion but exhibits chaotic behavior, is presented. It is shown that this equation can be lifted to an automorphism of a certain rational surface and can therefore be considered to be the action of an extended Weyl group of indefinite type. A

M. Albrow, J. An, J. -P. Beaulieu, J. A. R. Caldwell

We present VLT FORS1 spectroscopy that temporally resolves the second caustic crossing of the Bulge K giant source of microlensing event EROS 2000-BLG-5, the first time this has been accomplished for several phases of a caustic transit. The ~1 angstrom H-alpha equivalent width of the source star increases slightly as the center of the star egresses the caust

Kenji Harada, Naoki Kawashima

We present a new algorithm for quantum Monte Carlo simulation based on global updating with loops. While various theoretical predictions are confirmed in one dimension, we find, for S=1 systems on a square lattice with an antiferromagnetic biquadratic interaction, that the intermediate phase between the antiferromagnetic and the ferromagnetic phases is disor

F. Cannata, M. Ioffe, R. Roychoudhury, P. Roy

We investigate complex PT-symmetric potentials, associated with quasi-exactly solvable non-hermitian models involving polynomials and a class of rational functions. We also look for special solutions of intertwining relations of SUSY Quantum Mechanics providing a partnership between a real and a complex PT-symmetric potential of the kind mentioned above. We

Michael Kleckner, Amiram Ron

We study the effect of the environment on the process of the measurement of a state of a microscopic spin half system. The measuring apparatus is a heavy particle, whose center of mass coordinates can be considered at the end of the measurement as approximately classical, and thus can be used as a pointer. The state of the pointer, which is the result of its

Yoshihiro Nambu, Yoshie Chiba-Kohno

We give a comprehensive and constructive proof of the no-go theorem of a bit commitment given by Mayers, Lo, and Chau from the viewpoint of quantum information theory. It is shown that there is a trade-off relation between information acquired by Bob during the commitment phase and the ability to change a commit bit by Alice during the opening phase. It is c

A. Papageorgiou, J. F. Traub

In a recent paper Keister proposed two quadrature rules as alternatives to Monte Carlo for certain multidimensional integrals and reported his test results. In earlier work we had shown that the quasi-Monte Carlo method with generalized Faure points is very effective for a variety of high dimensional integrals occurng in mathematical finance. In this paper w

Janis Alnis, Marcis Auzinsh

Origin of recently discovered reversed (opposite sign) dark resonances was explained theoretically and verified experimentally. It is shown that the reason for these resonances is a specific optical pumping of ground state level in a transition when ground state angular momentum is smaller than the excited state momentum.

Janis Alnis, Marcis Auzinsh

Excited state angular momentum alignment -- orientation conversion for atoms with hyperfine structure in presence of an external magnetic field is investigated. Transversal orientation in these conditions is reported for the first time. This phenomenon occurs under Paschen Back conditions at intermediate magnetic field strength. Weak radiation from a linearl

Gerald A. Miller

I discuss the use of light cone variables to compute the nucleonic and mesonic components of nuclear wave functions. A Lagrangian and its energy-momentum tensor $T^{^+μ}$ is used to define the total momentum operators $P^μ$. The aim is to use wave functions, expressed in terms of plus-momentum variables, which are used to analyze high energy experiments such

Jurgen Schaffner-Bielich

The formation of dibaryons with strangeness are discussed for the interior of neutron stars and for central relativistic heavy-ion collisions. We derive limits for the properties of H-dibaryons from pulsar data. Signals for the formation of possible bound states with hyperons at BNL's Relativistic Heavy-Ion Collider (RHIC) are investigated by studying th

A. V. Afanasjev, J. Konig, P. Ring, L. M. Robledo

A parameter free investigation of the moments of inertia of ground state rotational bands in well deformed rare-earth nuclei is carried out using Cranked Relativistic Hartree-Bogoliubov (CRHB) and non-relativistic Cranked Hartree-Fock-Bogoliubov (CHFB) theories. In CRHB theory, the relativistic fields are determined by the non-linear Lagrangian with the NL1

A. V. Afanasjev, P. Ring

A systematic investigation of the yrast superdeformed (SD) rotational bands in even-even nuclei of the $A\sim 190$ mass region has been performed within the framework of the cranked relativistic Hartree-Bogoliubov theory. The particle-hole channel of this theory is treated fully relativistically, while a finite range two-body force of Gogny type is used in t

P. S. Baranov, A. I. L'vov, V. A. Petrun'kin, L. N. Shtarkov

An analysis of all experimental data of 50's - 90's on elastic gamma-p scattering at photon energies below 150 MeV (10 experimental works) is performed in order to determine the electric (alpha_p) and magnetic (beta_p) polarizabilities of the proton. A fit of these data with the two free parameters, alpha_p and beta_p, embedded into a theoretical cro

Alexander Kiselev, Leonid Ryzhik

We consider a system of reaction-diffusion equations with passive advection term and Lewis number not equal to one. Such systems are used to describe chemical reactions in a flow in a situation where temperature and material diffusivities are not equal. It is expected that the fluid advection will distort the reaction front, increasing the area of reaction a

Rodislav Driben, Boris A. Malomed

We consider a long fiber-optical link consisting of alternating dispersive and nonlinear segments, i.e., a split-step model (SSM), in which the dispersion and nonlinearity are completely separated. Passage of a soliton through one cell of the link is described by an analytically derived map. Numerical iterations of the map reveal that, at values of the syste

V. E. Adler

The new examples are found of the constraints which link the 1+2-dimensional and multifield integrable equations and lattices. The vector and matrix generalizations of the Nonlinear Schrödinger equation and the Ablowitz-Ladik lattice are considered among the other multifield models. It is demonstrated that using of the symmetries belonging to the hierarchies

Stefan Teufel, Herbert Spohn

We consider an electron coupled to the quantized radiation field and subject to a slowly varying electrostatic potential. We establish that over sufficiently long times radiation effects are negligible and the dressed electron is governed by an effective one-particle Hamiltonian. In the proof only a few generic properties of the full Pauli-Fierz Hamiltonian

N. P. Landsman

Symplectic reduction is reinterpreted as the composition of arrows in the category of integrable Poisson manifolds, whose arrows are isomorphism classes of dual pairs, with symplectic groupoids as units. Morita equivalence of Poisson manifolds amounts to isomorphism of objects in this category. This description paves the way for the quantization of the class

N. P. Landsman, B. Ramazan

We prove the existence of a strict deformation quantization for the canonical Poisson structure on the dual of an integrable Lie algebroid. It follows that any Lie groupoid C*-algebra may be regarded as a result of a quantization procedure. The C*-algebra of the tangent groupoid of a given Lie groupoid G (with Lie algebra g) is the C*-algebra of a continuous

Shlomo Gelaki

A fundamental problem in the theory of Hopf algebras is the classification and construction of finite-dimensional (minimal) triangular Hopf algebras (A,R) introduced by Drinfeld. Only recently Etingof and the author completely solved this problem for semisimple A over algebraically closed fields of characteristics 0 and p>>dim(A) (any p if one assumes that A

Michael C. Laskowski, Saharon Shelah

If T has only countably many complete types, yet has a type of infinite multiplicity then there is a ccc forcing notion Q such that, in any Q --generic extension of the universe, there are non-isomorphic models M_1 and M_2 of T that can be forced isomorphic by a ccc forcing. We give examples showing that the hypothesis on the number of complete types is nece

A. B. Goncharov

We express the Aomoto trilogarithm explicitely via classical trilogarithm and investigate the algebraic-geometric structures behind this: different realuzations of the weight three motivic complexes. Using this results we give an explicit motivic construction of the Grassmannian 4-logarithm and Borel regulator map for K_7(C).

Michael C. Laskowski, Saharon Shelah

A class K of structures is controlled if, for all cardinals lambda, the relation of L_{infty,lambda}-equivalence partitions K into a set of equivalence classes (as opposed to a proper class). We prove that the class of doubly transitive linear orders is controlled, while any pseudo-elementary class with the omega-independence property is not controlled.

Saharon Shelah, Juris Steprāns

Martin&#39;s Axiom does not imply that all automorphisms of P(N)/[N]^{<aleph_0} are somewhere trivial.

A. B. Goncharov, J. Zhao

Some time ago the first author suggested two different constructions of Grassmannian n-logarithms. One of them works for all n, but its motivic nature is hidden. The other is a motivic but so far available only for n=2,3,4. We derived some general results about the first construction of Grassmannian polylogarithms, and found an explicit relation between the

Eiji Ogasa

We prove the following results (1) (2) (3) on relations between $n$-links and their components. (1) Let L=(L_1, L_2) be a (4k+1)-link (4k+1\geq 5). Then we have Arf L=Arf L_1+Arf L_2. (2) Let L=(L_1, L_2) be a (4k+3)-link (4k+3\geq3). Then we have σL=σL_1+σL_2. (3) Let n\geq1. Then there is a nonribbon n-link L=(L_1, L_2) such that L_i is a trivial knot. We

Vyjayanthi Chari, Michael Kleber

We study connections between the ring of symmetric functions and the characters of irreducible finite-dimensional representations of quantum affine algebras. We study two families of representations of the symplectic and orthogonal Lie algebras. One is defined via combinatorial properties and is easy to calculate; the other is closely related to the $q=1$ li

J. Fuchs, C. Schweigert

The role of automorphisms of infinite-dimensional Lie algebras in conformal field theory is examined. Two main types of applications are discussed; they are related to the enhancement and reduction of symmetry, respectively. The structures one encounters also appear in other areas of physics and mathematics. In particular, they lead to two conjectures on the

Jose F. Alves, Vitor Araujo

We give both sufficient conditions and necessary conditions for the stochastic stability of non-uniformly expanding maps either with or without critical sets. We also show that the number of probability measures describing the statistical asymptotic behaviour of random orbits is bounded by the number of SRB measures if the noise level is small enough. As an

Vadim E. Levit, Eugen Mandrescu

A maximum stable set in a graph G is a stable set of maximum size. S is a local maximum stable set if it is a maximum stable set of the subgraph of G spanned by the union of S and N(S), where N(S) is the neighborhood of S. A matching M is uniquely restricted if its saturated vertices induce a subgraph which has a unique perfect matching, namely M itself. One

Lucia Caporaso

A general canonical curve X determines a finite set T(X) of hyperplanes, which is in bijective correspondence with the set of odd theta-characteristics of X. The definition of T(X) can be extended to certain singular curves, in a way that is compatible with degenerations. If X is a Deligne-Mumford stable curve (or a cuspidal curve), we describe the enumerati

James W. Anderson, Gabriel P. Paternain

We consider the minimal entropy problem, namely the question of whether there exists a smooth metric of minimal entropy, for certain classes of 3-manifolds. Among other resulsts, we show that if M is a closed, orientable, geometrizable 3-manifold with zero simplicial volume, then the minimal entropy can be solved for M if and only if M admits a metric modell

Michael G. Megrelishvili, Vladimir G. Pestov, Vladimir V. Uspenskij

An action of a group $G$ on a compact space $X$ is called weakly almost periodic if the orbit of every continuous function on $X$ is weakly relatively compact in $C(X)$. We observe that for a topological group $G$ the following are equivalent: (i) every continuous action of $G$ on a compact space is weakly almost periodic; (ii) $G$ is precompact. For monothe

Jason Fulman

The asymptotic probability theory of conjugacy classes of the finite general linear and unitary groups leads to a probability measure on the set of all partitions of natural numbers. A simple method of understanding these measures in terms of Markov chains is given and compared with work on the uniform measure. Elementary probabilistic proofs of the Rogers-R

R. Loll

Just as for non-abelian gauge theories at strong coupling, discrete lattice methods are a natural tool in the study of non-perturbative quantum gravity. They have to reflect the fact that the geometric degrees of freedom are dynamical, and that therefore also the lattice theory must be formulated in a background-independent way. After summarizing the status

R. R. Metsaev, A. A. Tseytlin

We discuss superparticle and superstring dynamics in AdS_3 x S^3 supported by R-R 3-form background using light-cone gauge approach. Starting with the superalgebra psu(1,1|2) + psu(1,1|2) representing the basic symmetry of this background we find the light-cone superparticle Hamiltonian. We determine the harmonic decomposition of light-cone superfield descri

Alexander Burinskii

We give a review of the works devoted to the treatment of the Kerr super black hole solution as a spinning particle. The real, complex and stringy structures of the Kerr and super-Kerr geometries are discussed, as well as the recent results on the regular matter source for the Kerr spinning particle. It is shown that the source has to represent a rotating ba

Paul H. Frampton, Thomas W. Kephart

A systematic analysis is presented of compactifications of the IIB superstring on $AdS_5 \times S^5/Γ$ where $Γ$ is a non-abelian discrete group. Every possible $Γ$ with order $g \leq 31$ is considered. There exist 45 such groups but a majority cannot yield chiral fermions due to a certain theorem that is proved. The lowest order to embrace the nonSUSY stand

Sunil Mukhi, Nemani V. Suryanarayana

Stable non-BPS states can be constructed and studied in a variety of contexts in string theory. Here we review some interesting constructions that arise from suspended and wrapped branes. We also exhibit some stable non-BPS states that have holographic duals.

Christian Brouder, Alessandra Frabetti

We study the renormalization of massless QED from the point of view of the Hopf algebra discovered by D. Kreimer. For QED, we describe a Hopf algebra of renormalization which is neither commutative nor cocommutative. We obtain explicit renormalization formulas for the electron and photon propagators, for the vacuum polarization and the electron self-energy,

Robert Bluhm

A theoretical framework extending QED in the context of the standard model is used to analyze a variety of Lorentz and CPT tests in atomic systems. Experimental signatures of possible Lorentz and CPT violation in these systems are investigated, and bounds are discussed.

T. Han, J. Jiang

We study the general Higgs-weak boson coupling with CP-violation via the process e+e- -> f \bar f h. We categorize the signal channels by sub-processes Zh production and ZZ fusion and construct four CP asymmetries by exploiting polarized e+e- beams. We find complementarity among the sub-processes and the asymmetries to probe the real and imaginary parts of t

H. J. de Vega

We implement the dynamical renormalization group (DRG) using the hard thermal loop (HTL) approximation for the real-time nonequilibrium dynamics in hot plasmas. The focus is on the study of the relaxation of gauge and fermionic mean fields and on the quantum kinetics of the photon and fermion distribution functions. As a concrete physical prediction, we find

Gustavo Burdman, Gudrun Hiller

Making use of the measurement of the $B\to K^*γ$ branching ratio together with the relations following from the limit of high recoil energy, we obtain stringent constraints on the values of the form-factors entering in heavy-to-light $B\to V\ell\ell&#39;$ processes such as $B\to K^*\ell^+\ell^-$, $B\to K^*ν\barν$ and $B\to ρ\ellν$ decays. We show that the sy

R. Sekhar Chivukula

Lecture 1 provides an introduction to dynamical electroweak symmetry breaking. Lectures 2 and 3 give an introduction to compositeness, with emphasis on effective lagrangians, power-counting, and the &#39;t Hooft anomaly-matching conditions.

K. R. S. Balaji, R. N. Mohapatra, M. K. Parida, E. A. Paschos

The renormalization group evolution equation for two neutrino mixing is known to exhibit nontrivial fixed point structure corresponding to maximal mixing at the weak scale. The presence of the fixed point provides a natural explanation of the observed maximal mixing of $ν_μ-ν_τ$ if the $ν_μ$ and $ν_τ$ are assumed to be quasi-degenerate at the seesaw scale wi

C. Panagiotakopoulos

Hybrid inflation is a natural scenario in the absence of supersymmetry. In the context of supergravity, however, it has to face the naturalness problems of the initial conditions and of the adequate suppression of the inflaton mass. Both can be successfully addressed in a class of models involving Kaehler potentials associated with products of SU(1,1)/U(1) K

S. V. Goloskokov

Double spin asymmetries in the diffractive $Q \bar Q$ and $J/Ψ$ leptoproduction are discussed. It is shown that the asymmetries for longitudinally polarized lepton and longitudinally or transversely polarized proton can be used to study spin dependent gluon distribution of the proton at small $x$.

Alexander Lenz

In this talk we summarize the status of theoretical predictions for the average number of charm quarks in a B-hadron decay.

E. Gotsman, E. Ferreira, E. Levin, U. Maor

We examine the latest HERA experimental measurements of the $Q^2$ logarithmic derivative of the proton structure function. We analyze the characteristics of DGLAP with and without screening, as well as a Regge type model, and compare their predictions to all available data on $\slope$ including those for fixed W. Our results show that the present data can be

Davison E. Soper

This is an introduction to the use of QCD perturbation theory, emphasizing generic features of the theory that enable one to separate short-time and long-time effects. I also cover some important classes of applications: electron-positron annihilation to hadrons, deeply inelastic scattering, and hard processes in hadron-hadron collisions.

H. Spiesberger, M. Spira, P. M. Zerwas

We present an introduction into the basic concepts of the Standard Model, i.e. the gauge theories of the forces and the Higgs mechanism for generating masses. The Glashow-Salam-Weinberg theory of the electroweak interactions will be described in detail. The key experiments are reviewed, including the precision tests at high energies. Finally, the limitations

Damir Becirevic

Recent results relevant for the B-physics phenomenology, obtained from lattice QCD simulations by the APE Collaboration, are reviewed. This includes the B0-B0bar mixing amplitude, B-> pi semileptonic decay and the relative width difference of B0_s mesons, $(ΔΓ/Γ)_{B_s}$.

Sinya Aoki

The recent progress on unquenched QCD simulations is critically reviewed. After some discussions on problems and subtleties in unquenched simulations, hadron spectra obtained from both quenched and unquenched simulations are compared among various gauge and quark actions. It is found that the Edinburgh plot does not agree in the continuum limit between Wilso

Fermilab E791 Collaboration, D. J. Summers

Limits at the 10**-4 level are reported for rare and forbidden decays of the D0 charm meson to a pair of leptons and either a vector meson or two pseudoscalar mesons. Of these searches, 18 are investigations of decays without previous published results; several others have significantly improved sensitivity over previous results.

G. Bauer

A measurement of Delta m_d is performed using inclusive lepton+vertex events at CDF. A probability based Same-Side Tagger was developed to tag the initial b-flavor of the B^0_d, which suppresses tagging on B-decay products. We find Delta m_d = 0.42 +/- 0.09 +/- 0.03 ps^-1.

J. C. Wang, J. A. Appel, M. Artuso, J. N. Butler

The silicon pixel vertex detector is one of the key elements of the BTeV spectrometer. Detector prototypes were tested in a beam at Fermilab. We report here on the measured spatial resolution as a function of the incident angles for different sensor-readout electronics combinations. We compare the results with predictions from our Monte Carlo simulation.

N. Solomey

Recent results from the KTeV experiment at Fermilab using $Ξ^0$ hyperons have enabled a great leap in improving our understanding of elementary particle physics, especially with the first form-factor measurement from the semi-leptonic decay $Ξ^0 \to Σ^+ e^- \barν$. This decay is a test of whether the standard model contains all of the needed parameters to fu

S. Chan, CLEO Collaboration

Using the CLEO II detector at the Cornell Electron Storage Ring we have measured the $Ξ_c^{0}$ decay asymmetry parameter in the decay $Ξ_c^{0} \to Ξ^{-} π^+$. We find $α_{Ξ_c^{0}} α_Ξ = 0.26 \pm 0.18{(stat)}^{+0.05}_{-0.04}{(syst)}$, using the world average value of $α_Ξ = -0.456 \pm 0.014$ we obtain $α_{Ξ_c^{0}} = -0.56 \pm 0.39{(stat)}^{+0.10}_{-0.09}{(sys

Shahzad Sarwar

We report the preliminary measurement by the FOCUS Collaboration (E831 at Fermilab) of masses and widths of the L=1 charm mesons $D_2^{*0}$ and $D_2^{*+}$. The fit of the invariant mass distribution requires an additional term to account for a broad structure over background.

DZero Collaboration

We apply a quasi-model-independent strategy (&#34;Sleuth&#34;) to search for new high p_T physics in approximately 100 pb^-1 of ppbar collisions at sqrt(s) = 1.8 TeV collected by the DZero experiment during 1992-1996 at the Fermilab Tevatron. We systematically analyze many exclusive final states and demonstrate sensitivity to a variety of models predicting n

L3 Collaboration

The production of c and b quarks in gamma-gamma collisions is studied with the L3 detector at LEP with 410 pb^-1 of data, collected at centre-of-mass energies from 189 GeV to 202 GeV. Hadronic final states containing c and b quarks are identified by detecting electrons or muons from their semileptonic decays. The cross sections sigma(e+e- -> e+e- c c~ X) and

C. Giunti, M. Laveder

We consider the power to reject false values of the parameter in Frequentist methods for the calculation of confidence intervals. We connect the power with the physical significance (reliability) of confidence intervals for a parameter bounded to be non-negative. We show that the confidence intervals (upper limits) obtained with a (biased) method that near t

L3 Collaboration

Excited leptons are searched for using the L3 detector at LEP. The data collected at centre-of-mass energies in the range from 192 up to 202 GeV correspond to a total luminosity of 233 pb^(-1). No evidence of either pair production of excited leptons, nor of single production is found. From the searches for pair produced excited leptons, lower mass limits cl

Ana Nunes, Jose P. Mimoso, Tiago C. Charters

We examine the dynamical implications of an interaction between some of the fluid components of the universe. We consider the combination of three matter components, one of which is a perfect fluid and the other two are interacting. The interaction term generalizes the cases found in scalar field cosmologies with an exponential potential. We find that attrac

P. Astone

We have developped a procedure for the search of periodic signals in the data of gravitational wave detectors. We report here the analysis of one year of data from the resonant detector Explorer, searching for pulsars located in the Galactic Center (GC). No signals with amplitude greater than $\bar{h}= 2.9~10^{-24}$, in the range 921.32-921.38 Hz, were obser

Madhavan Varadarajan

We derive a transformation from the usual ADM metric-extrinsic curvature variables on the phase space of Schwarzschild black holes, to new canonical variables which have the interpretation of Kruskal coordinates. We explicitly show that this transformation is non-singular, even at the horizon. The constraints of the theory simplify in terms of the new canoni

Hendrik Blockeel, Luc De Raedt, Jan Ramon

An approach to clustering is presented that adapts the basic top-down induction of decision trees method towards clustering. To this aim, it employs the principles of instance based learning. The resulting methodology is implemented in the TIC (Top down Induction of Clustering trees) system for first order clustering. The TIC system employs the first order l

N. Giglioli, A. Saltelli

The aim of this paper is to present and describe SimLab 1.1 (Simulation Laboratory for Uncertainty and Sensitivity Analysis) software designed for Monte Carlo analysis that is based on performing multiple model evaluations with probabilistically selected model input. The results of these evaluations are used to determine both the uncertainty in model predict

Nikolay Pelov, Emmanuel De Mot, Marc Denecker

Many logic programming based approaches can be used to describe and solve combinatorial search problems. On the one hand there is constraint logic programming which computes a solution as an answer substitution to a query containing the variables of the constraint satisfaction problem. On the other hand there are systems based on stable model semantics, abdu

Yohei Ikezoe, Akira Sasaki, Yoshiki Ohshima, Ken Wakita

Although attribute grammars are commonly used for compiler construction, little investigation has been conducted on debugging attribute grammars. The paper proposes two types of systematic debugging methods, an algorithmic debugging and slice-based debugging, both tailored for attribute grammars. By means of query-based interaction with the developer, our de

M. Moraghebi, C. Buhler, S. Yunoki, A. Moreo

Using numerical techniques we study the spectral function $A(k,ω)$ of a spin-fermion model for cuprates in the regime where magnetic and charge domains (stripes) are developed upon hole-doping. From $A(k,ω)$ we study the electronic dynamics and determine the Fermi Surface (FS), which is compared with angular resolved photoemission results for $La_{2-x}Sr_xCu

Y. M. Galperin, O. Entin-Wohlman, Y. Levinson

Fluctuations in the acoustoelectric current, induced by a surface acoustic wave propagating along a ballistic quantum channel, are considered. We focus on the large wave-amplitude case, in which it has been experimentally found that the current is quantized, and analyze the noise spectrum. A phenomenological description of the process, in terms of a random p

Erik Luijten, Michael E. Fisher, Athanassios Z. Panagiotopoulos

The constant-volume heat capacity, C_V(T, rho), of the restricted primitive model (RPM) electrolyte is considered in the vicinity of its critical point. It is demonstrated that, despite claims, recent simulations for finite systems do not convincingly indicate the absence of a divergence in C_V(T, rho)--which would point to non-Ising-type criticality. The st

J. Wosnitza, S. Wanka, J. Hagel, H. v. Loehneysen

The quasi-two-dimensional organic superconductor beta-(BEDT-TTF)_2SF_5CH_2CF_2SO_3 (T_c approx 4.4 K)shows very strong Shubnikov-de Haas (SdH) oscillations which are superimposed on a highly anomalous steady background magnetoresistance, R_b. Comparison with de Haas- van Alphen oscillations allow a reliable estimate of R_b which is crucial for the correct ex

Rui D. M. Travasso, Alan J. Bray, Andrea Cavagna

We study the effect of a uniform shear flow on an interface separating the two broken-symmetry ordered phases of a two-dimensional system with nonconserved scalar order parameter. The interface, initially flat and perpendicular to the flow, is distorted by the shear flow. We show that there is a critical shear rate, γ_c, proportional to 1/L^2, (where L is th

T. Hakobyan, J. H. Hetherington, M. Roger

Using Density-Matrix Renormalization Group, we investigate the general phase diagram of the frustrated two-leg ladder with Heisenberg interactions along legs, rungs and diagonals. We confirm that all antiferromagnetic gapped states belong to the same universality class as the Haldane phase. In a three-dimensional phase diagram, we determine a continuous surf

P. Fazekas

The long-standing problem of the effect of correlations on the ferromagnetism of is apparently nearing solution. The ferromagnetism of transition metals compounds, for instance doped manganites, poses a new question: is there some kind of orbital order coexisting with itinerant ferromagnetism? The ideas and techniques introduced by Gutzwiller should be of us

Yukinori Yasui, Takayuki Takaai, Takayoshi Ootsuka

We investigate the macroscopic quantum tunneling of the attractive Bose-Einstein condensate. Within the effective Lagrangian framework, we find bounce solutions and explicitly calculate the decay rate of the condensate trapped in a cylindrically symmetric potential. In particular, in the case where the number of condensed bosons is slightly below a certain c

Dipten Bhattacharya, Pintu Das, A. Pandey, A. K. Raychaudhuri

The measurement of resistivity across a wide temperature range - from 15 to 1473 K - in rare-earth manganite series of compounds reveals a very interesting feature : normally observed insulating pattern beyond Tc (Curie Point) gives way to a reentrant metallic pattern around a characteristic temperature T*. The transport activation barrier Ea collapses to ze

Juana Moreno, Shaojin Qin, P. Coleman, Lu Yu

Using the density matrix renormalization group (DMRG) method we study a two-channel Kondo lattice model on a half filled ladder. Our model involves an on-site s-wave and a nearest neighbor d-wave coupling between the local moments and the conduction electrons on the ladder. By changing the relative strength of the two Kondo interactions we examine the evolut

H. Ferrari, D. Ibaceta, V. Bekeris, E. Calzetta

We report on the observation of the rearrangement of vortices in the ns time scale following a fast magnetic field variation due to selective local heating of a high Tc superconducting film. Detailed simulations describing the measured photoinduced voltage signals along the film lead to a better understanding of vortex dynamics in fast regimes, where mean vo

T. Senthil, Matthew P. A. Fisher

We propose several tests of the idea that the electron is fractionalized in the underdoped and undoped cuprates. These include the ac Josephson effect, and tunneling into small superconducting grains in the Coulomb blockade regime. In both cases, we argue that the results are qualitatively modified from the conventional ones if the insulating tunnel barrier

E. V. Vasiliu, S. D. Kaim, N. P. Kovalenko

The pair- and three-proton interaction potentials for metal-phase hydrogen are calculated. Irreducible three-proton interactions are shown to be essential in the development of the metal hydrogen structure. Possible manifestations of the three-ion interactions in the structure of quickly quenched metallic systems are discussed. Existence of amorphous metals

Hal Tasaki

Recently Allahverdyan and Nieuwenhuizen (cond-mat/0006404) argued that the second law of thermodynamics may be violated in a quantum system as a &#34;consequence of quantum coherence in the presence of the slightly off-equilibrium nature of the bath.&#34; By using a standard result about relative entropy, we prove rigorously that the second law is never viol

Ji Meng Loh, Jean M. Quashnock, Michael L. Stein

We examine the three-dimensional clustering of C IV absorption-line systems, using an extensive catalog of QSO heavy-element absorbers drawn from the literature. We measure clustering by a volume-weighted integral of the correlation function called the reduced second-moment measure, and include information from both along and across QSO lines of sight, thus

P. P. Sorokin, J. H. Glownia, R. T. Hodgson

It is shown that, under sufficiently intense OB-star illumination of a stationary photoexcitation front (PDR), nonlinear H2 photoexcitation processes comprising driven resonant two-photon transitions between X-state quantum levels, with VUV continuum light from the star supplying both driving fields, largely determine the photonic pathways of H2 molecules in

L. Stella

The relativistic precession model for quasi periodic oscillations, QPOs, in low mass X-ray binaries is reviewed. The behaviour of three simultaneous types of QPOs is well matched in terms of the fundamental frequencies for geodesic motion in the strong field of the accreting compact object for reasonable star masses and spin frequencies. The model ascribes t

M. Wold, M. Lacy, P. B. Lilje, S. Serjeant

We have quantified the galaxy environments around a sample of 0.5 < z < 0.8 radio-quiet quasars using the amplitude of the spatial galaxy--quasar correlation function, B_gq. The quasars exist in a wide variety of environments, some sources are located in clusters as rich as Abell class 1--2 clusters, whereas others exist in environments comparable to the fie

Francis J. Robinson, Kwing L. Chan

We present results of two simulations of the convection zone, obtained by solving the full hydrodynamic equations in a section of a spherical shell. The first simulation has cylindrical rotation contours (parallel to the rotation axis) and a strong meridional circulation, which traverses the entire depth. The second simulation has isorotation contours about

Ewa Szuszkiewicz, Roberto Turolla, Luca Zampieri

Thermal instability driven by radiation pressure might be relevant for intrinsically bright accreting sources. The most promising candidate where this instability seems to be at work is one of the two known galactic superluminal sources, GRS 1915+105 (Belloni et al. 1997). In spite of being of relevance, this scenario has not yet been confirmed by proper tim

S. Bardelli, E. Zucca, T. Venturi, R. Morganti

Rich superclusters are the ideal environment for the detection of cluster mergings, because the high peculiar velocities induced by the enhanced local density of the large-scale structure favour the cluster-cluster collisions, in the same way as seen in the simulations. The Shapley Concentration supercluster represents a unique laboratory where it is possibl