September 2000 arXiv papers — page 15

Lister Staveley-Smith, Sebastian Juraszek, Patricia A. Henning, Baerbel S. Koribalski

A blind HI survey using the Parkes telescope at |b|<5 deg, 300 deg < l < 332 deg has so far revealed 305 galaxies, most of which were previously unknown. These galaxies are used to map out the distribution of filaments and voids out to 10000 km/s. A preliminary measurement of the galaxy overdensity suggests only a moderate overdensity is present, and that th

Naoki Seto, Misao Sasaki

We examine the polarization signal of the cosmic microwave background radiation associated with distant clusters. The polarization is induced by the Thomson scattering of microwave photons with ionized gas of clusters and contains information of quadrupole temperature anisotropies observed at the clusters. The three-dimensional map of the signal are expresse

Brent A. Buckalew, Reginald J. Dufour, Patrick L. Shopbell, Donald K. Walter

We present the detection of He II sources in the Im galaxy NGC 1569 from HST WFPC2 imagery. Out of the fifteen detections, seven were Wolf-Rayet stars, five were stellar clusters with associated He II emission, and three were sources of unknown origin. The detected Wolf-Rayet stars&#39; colors and magnitudes are similar to Large Magellanic Cloud late-type WN

Myung Gyoon Lee, Narae Hwang

We present a study of photometric properties of the galaxies in the Hubble Deep Field South (HDFS) based on the released WFPC2 images obtained with the Hubble Space Telescope (HST). We have classified about 340 galaxies with $I<26$ mag in the HDFS as well as about 400 galaxies in the Hubble Deep Field North (HDFN) using the visual classification supplemented

G. L. Long, H. Y. Yan, Y. S. Li, C. C. Tu

A generalized quantum search algorithm, where phase inversions for the marked state and the prepared state are replaced by $π/2$ phase rotations, is realized in a 2-qubit NMR heteronuclear system. The quantum algorithm searches a marked state with a smaller step compared to standard Grover algorithm. Phase matching requirement in quantum searching is demonst

Simeon Pol&#39;shin

Taking the ${\Bbb R}^1 \times H^3$ space as an example, we develop the new method of quantization of fields over symmetric spaces. We construct the quantized massless fields of an arbitrary spin over the ${\Bbb R}^1 \times H^3$ space by the resolution over the systems of &#34;plane waves&#34; which are solutions of the corresponding wave equations. The propa

T. M. Dame, Dap Hartmann, P. Thaddeus

New large-scale CO surveys of the first and second Galactic quadrants and the nearby molecular cloud complexes in Orion and Taurus, obtained with the CfA 1.2 m telescope, have been combined with 31 other surveys obtained over the past two decades with that instrument and a similar telescope on Cerro Tololo in Chile, to produce a new composite CO survey of th

Steve Brandt, Randall Correll, Roberto Gomez, Mijan Huq

We present the first simulations of non-headon (grazing) collisions of binary black holes in which the black hole singularities have been excised from the computational domain. Initially two equal mass black holes $m$ are separated a distance $\approx10m$ and with impact parameter $\approx2m$. Initial data are based on superposed, boosted (velocity $\approx0

Anton A. Gerasimov, Samson L. Shatashvili

In these notes we revisit the tachyon lagrangian in the open string field theory using background independent approach of Witten from 1992. We claim that the tree level lagrangian (up to second order in derivatives and modulo some class of field redefinitions) is given by $L = e^{-T} (\partial T)^2 + (1+T)e^{-T}$. Upon obvious change of variables this leads

Eric Pfahl, Saul Rappaport

We present a new model for low-luminosity X-ray sources in globular clusters, with L_x < 10^34 erg/s. The model we propose is that of a single neutron star accreting from cluster gas that has accumulated as a natural product of stellar evolution. An analytic luminosity function is derived under the assumption that the speed distribution of neutron stars in t

P. Kaaret, A. H. Prestwich, A. Zezas, S. S. Murray

We have analyzed Chandra High Resolution Camera observations of the starburst galaxy M82, concentrating on the most luminous x-ray source. We find a position for the source of $\rm R.A. = 09^h 55^m 50^s.2, decl. = +69^{\circ} 40\arcmin 46\arcsec.7$ (J2000) with a $1σ$ radial error of $0.7\arcsec$. The accurate x-ray position shows that the luminous source is

B. Czerny, M. Nikolajuk, M. Piasecki, J. Kuraszkiewicz

We analyze the scaling of the X-ray power density spectra with the mass of the black hole on the example of Cyg X-1 and Seyfert 1 galaxy NGC 5548. We show that the high frequency tail of the power density spectrum can be successfully used for determination of the black hole mass. We determine the masses of the black holes in 6 Broad Line Seyfert 1 galaxies,

Ruth C. Peterson, Ben Dorman, Robert T. Rood

Determining the properties of old stellar systems using evolutionary population synthesis requires a library of reliable model stellar fluxes. Empirical libraries are limited to spectra of stars in the solar neighborhood, with nearly solar abundances and abundance ratios. We report here a first step towards providing a flux library that includes nonsolar abu

Luis A. Anchordoqui, Diego F. Torres

Recent measurements of the cosmic microwave background confirm that it is described by a Planckian distribution with high precision. It is non-extensivity bounded to be less than some parts in $10^5$, or to some parts in $10^4$ at most. This deviation may appear minuscule, but may have a non-negligible effect on a particle propagating through this background

Pedro Marronetti, Richard A. Matzner

We solve the elliptic equations associated with the Hamiltonian and momentum constraints, corresponding to a system composed of two black holes with arbitrary linear and angular momentum. These new solutions are based on a Kerr-Schild spacetime slicing which provides more physically realistic solutions than the initial data based on conformally flat metric/m

Sunil Mukhi, Nemani V. Suryanarayana

We write down couplings of the fields on a single BPS Dp-brane with noncommutative world-volume coordinates to the RR-forms in type II theories, in a manifestly background independent way. This generalises the usual Chern-Simons action for a commutative Dp-brane. We show that the noncommutative Chern-Simons terms can be mapped to Myers terms on a collection

Fred C. Adams, Gordon L. Kane, Manasse Mbonye, Malcolm J. Perry

We consider proton decay in theories that contain large extra dimensions. If virtual black hole states are allowed by the theory, as is generally the case, then proton decay can proceed via virtual black holes. The experimental limits on the proton lifetime place strong constraints on the quantum gravity scale $\mnew$ (the effective Planck mass). For most th

Feng Yuan

We find a new two-temperature hot branch of equilibrium solutions for stationary accretion disks around black holes. In units of Eddington accretion rate defined as $10L_{\rm Edd}/c^2$, the accretion rates to which these solutions correspond are within the range $\dot{m}_1 \la \dot{m} \la 1$, here $\dot{m}_1$ is the critical rate of advecti$. In these soluti

Rene A. Mendez, Maria T. Ruiz

The luminosity function of white dwarfs is a powerful tool for studies of the evolution and formation of the Milky Way. The (theoretical) white dwarf cooling sequence provides a useful indicator of the evolutionary time scales involved in the chronometry and star formation history of the galactic disk, therefore, intrinsically faint (& old) white dwarfs in t

Yuxing Wang, Bernard Revaz, Andreas Erb, Alain Junod

The specific heat due to line nodes in the superconducting gap of YBa2Cu3O7 has been obscured up to now by magnetic terms of extrinsic origin, even for high quality crystals. We report the specific heat of a new single crystal grown in a non-corrosive BaZrO3 crucible, for which paramagnetic terms are reduced to less than one spin-1/2 center for 20&#39;000 Cu

A. N. Schellekens, N. Sousa

We construct explicitly the open descendants of some exceptional automorphism invariants of U(2N) orbifolds. We focus on the case N=pq, p and q prime, and on the automorphisms of the diagonal and charge conjugation invariants that exist for these values of N. These correspond to orbifolds of the circle with radius R^2=2p/q. For each automorphism invariant we

R. Benton Metcalf

A new method for measuring gravitational lensing with high redshift type Ia supernovae is investigated. The method utilizes correlations between foreground galaxies and supernova brightnesses to substantially reduce possible systematic errors and increase the signal to noise ratio. It is shown that this lensing signal can be related to the mass, size and sub

Gordey B. Lesovik, Thierry Martin, Gianni Blatter

A weakly biased normal-metal-superconductor junction is considered as a potential device injecting entangled pairs of quasi-particles into a normal-metal lead. The two-particle states arise from Cooper pairs decaying into the normal lead and are characterized by entangled spin- and orbital degrees of freedom. The separation of the entangled quasi-particles i

Tao Li

A model with interlayer pairing is proposed to explain the sinusoidal modulation of the resonant neutron scattering in high temperature superconductors. It is found that the interlayer pairing has s-wave symmetry in the CuO$_2$ plane and has comparable magnitude with the d-wave intralayer pairing. It is also found that the interlayer pairing mainly affects m

Chao-Shang Huang

After a brief review of the inclusive and exclusive rare semileptonic decays of B mesons in the standard model (SM), an overview of recent theoretical developments in this field is given. New physics effects on various observables such as branching ratio, backward-forward asymmetry, polarization of lepton and CP violation in the decays are anlyzed in models

T. H. Hansson, J. M. Leinaas, S. Viefers

We study the statistical mechanics of a two-dimensional gas with a repulsive delta function interaction, using a mean field approximation. By a direct counting of states we establish that this model obeys exclusion statistics and is equivalent to an ideal exclusion statistics gas.

Steve van Straaten, Michiel van der Klis, Erik Kuulkers, Mariano Mendez

We study correlations between the burst properties and the position in the color-color diagram of the low mass X-ray binary 4U 1728-34 using 21 bursts found in two data sets obtained with the Rossi X-ray Timing Explorer. Using spectral fits we analyze the spectral evolution during the bursts and determine the burst peak flux, temperature, rise time and fluen

C. Kuhrts, M. Beyer, P. Danielewicz, G. Roepke

Within a microscopic statistical description of heavy ion collisions, we investigate the effect of the medium on the formation of light clusters. The dominant medium effects are self-energy corrections and Pauli blocking that produce the Mott effect for composite particles and enhanced reaction rates in the collision integrals. Microscopic description of com

Michael A. Ivanov

Possible effects are considered which would be caused by a hypothetical superstrong interaction of photons or massive bodies with single gravitons of the graviton background. If full cosmological redshift magnitudes are caused by the interaction, then the luminosity distance in a flat non-expanding universe as a function of redshift is very similar to the sp

Chiang-Mei Chen

New spherically symmetric dyonic solutions, describing a wormhole-like class of spacetime configurations in five-dimensional Kaluza-Klein theory, are given in an explicit form. For this type of solution the electric and magnetic fields cause a significantly different global structure. For the electric dominated case, the solution is everywhere regular but, w

J. Goryo

We analyze the chiral p-wave superconductor in the low temperature region. The superconductor has a epsilon_{x} p_{x} + i epsilon_{y} p_{y}-wave gap in two dimensional space (2D). Near the second superconducting transition point, the system could be described by a quasi-1D chiral p-wave model in 2D. The axial anomaly occurs in such a model and causes an accu

A. N. Bernal, M. P. Lopez, M. Sanchez

Ideal rods and clocks are defined as an infinitesimal symmetry of the spacetime. Since no a priori geometric structure is considered, all the possible models of spacetime are obtained.

Igor Volovich, Yaroslav Volovich

Bell&#39;s theorem states that quantum correlation function of two spins can not be represented as an expectation value of two classical random variables. Spin is described in Bell&#39;s model by a single scalar random variable. We discuss another classical model of spin in which spin is described by a triple of classical random variables. It is shown that i

Marin Slobodan Tomas

The decay rate and the classical radiation power of an excited molecule (atom) located in the center of a dispersive and absorbing dielectric sphere taken as a simple model of a cavity are calculated adopting the Onsager model for the local field. The local-field correction factor to the external (radiation and absorption) power loss of the molecule is found

B. J. Hiley, O. J. E. Maroney

In a recent paper Griffiths claims that the consistent histories interpretation of quantum mechanics gives rise to results that contradict those obtained from the Bohm interpretation. This is in spite of the fact that both claim to provide a realist interpretation of the formalism without the need to add any new mathematical content and both always produce e

N. Gisin, V. Scarani, W. Tittel, H. Zbinden

Past, present and future experimental tests of quantum nonlocality are discussed. Consequences of assuming that the state-vector collapse is a real physical phenomenon in space-time are developed. These lead to experiments feasible with today&#39;s technology.

K. J. Harrington, R. B. Laughlin, S. Liang

The theory of stochastic transcription termination based on free-energy competition requires two or more reaction rates to be delicately balanced over a wide range of physical conditions. A large body of work on glasses and large molecules suggests that this should be impossible in such a large system in the absence of a new organizing principle of matter. W

M. Beckmann, A. Borissov, S. Brauksiepe, F. Burkart

The design, construction and operation of a Compton back-scattering laser polarimeter at the HERA storage ring at DESY are described. The device measures the longitudinal polarization of the electron beam between the spin rotators at the HERMES experiment with a fractional systematic uncertainty of 1.6%. A measurement of the beam polarization to an absolute

A. Czaykowska, T. M. Bauer, R. A. Treumann, W. Baumjohann

We present a statistical analysis of 132 dayside (LT 0700-1700) bow shock crossings of the AMPTE/IRM spacecraft. We perform a superposed epoch analysis of plasma and magnetic field parameters as well as of low frequency magnetic power spectra some minutes upstream and downstream of the bow shock by dividing the events into categories depending on the angle b

Gustavo R. Gonzalez-Martin

Geometric interactions in a new relativistic geometric unified theory include interactions other than gravitation and electromagnetism. In a low energy limit one of these interactions leads essentially to a Fermi type theory of weak interactions including the Hamiltonian and coupling constant.

A. Haibel, G. Nimtz

Tunnelling transit time for a frustrated total internal reflection in a double-prism experiment was measured using microwave radiation. We have found that the transit time is of the same order of magnitude as the corresponding transit time measured either in an undersized waveguide (evanescent modes) or in a photonic lattice. Moreover we have established tha

G. Nimtz, A. A. Stahlhofen, A. Haibel

Various experiments have shown superluminal group and signal velocities recently. Experiments were essentials carried out with microwave tunnelling, with frustrated total internal reflection, and with gain-assisted anomalous dispersion. According to text books a superluminal signal velocity violates Einstein causality implying that cause and effect can be ch

Gustavo R. Gonzalez-Martin

Excitations of a relativistic geometry are used to represent the theory of quantum electrodynamics. The connection excitations and the frame excitations reduce, respectively, to the electromagnetic field operator and electron field operator. Because of the inherent geometric algebraic structure these operators obey the standard commutation rules of QED. If w

N. M. Zubarev

The nonlinear dynamics of charged-surface instability development was investigated for liquid helium far above the critical point. It is found that, if the surface charge completely screens the field above the surface, the equations of three-dimensional (3D) potential motion of a fluid are reduced to the well-known equations describing the 3D Laplacian growt

M. Gedalin, Yu. E. Lyubarsky, M. Balikhin, R. J. Strangeway

We perform direct analysis of mirror mode instabilities from the general dielectric tensor for several model distributions, in the longwavelength limit. The growth rate at the instability threshold depends on the derivative of the distribution for zero parallel energy. The maximum growth rate is always $\sim k_\parallel v_{T\parallel}$ and the instability is

Jen-Hsu Chang, Ming-Hsien Tu

The bi-Hamiltonian structure of the Benney hierarchy is revisited. We show that the compatibility condition of the Poisson brackets provides the genus zero free energy of a topological field theory coupled to 2d gravity. We calculate the correlation functions via the Landau-Ginzburg formulation and derive the string equation based on the twistor construction

U. Bastolla, M. Laessig, S. Manrubia, A. Valleriani

We study a dynamic model of ecosystems where immigration plays an essential role both in assembling the species community and in mantaining its biodiversity. This framework is particularly relevant for insular ecosystems. Population dynamics is represented either as an individual based model or as a set of deterministic equations for population abundances. L

Robert Conte

Whether integrable, partially integrable or nonintegrable, nonlinear partial differential equations (PDEs) can be handled from scratch with essentially the same toolbox, when one looks for analytic solutions in closed form. The basic tool is the appropriate use of the singularities of the solutions, and this can be done without knowing these solutions in adv

Marian Grendar, Marian Grendar

The Boltzmann-Wallis-Jaynes&#39; multiplicity argument is taken up and elaborated. MaxEnt is proved and demonstrated to be just an asymptotic case of looking for such a vector of absolute frequencies in a feasible set, which has maximal probability of being generated by a uniform prior generator/pmf.

Sami I. Muslih

The connection between the canonical and the path integral formulations of Einstein&#39;s gravitational field is discussed using the Hamilton - Jacobi method. Unlike conventional methods, it is shown that our path integral method leads to obtain the measure of integration with no $δ$- functions, no need to fix any gauge and so no ambiguous deteminants will a

Emil J. Straube, Marcel K. Sucheston

Boas and Straube proved a general sufficient condition for global regularity of the d-bar Neumann problem in terms of families of vector fields that commute approximately with d-bar. In this paper, we study the existence of these vector fields on a compact subset of the boundary whose interior is foliated by complex manifolds. This question turns out to be c

Michael Falk

The Orlik-Solomon algebra ${\cal A}(G)$ of a matroid $G$ is the free exterior algebra on the points, modulo the ideal generated by the circuit boundaries. On one hand, this algebra is a homotopy invariant of the complement of any complex hyperplane arrangement realizing $G$. On the other hand, some features of the matroid $G$ are reflected in the algebraic s

Caterina Consani, Jasper Scholten

The paper investigates some aspects of the geometry and the arithmetic of a non-rigid Calabi-Yau threefold. Particular emphasis is given to the study of its L-function L(H^3,s) and the Galois representation.

Marian Grendar,, Marian Grendar

Concept of exponential family is generalized by simple and general exponential form. Simple and general potential are introduced. Maximum Entropy and Maximum Likelihood tasks are defined. ML task on the simple exponential form and ME task on the simple potentials are proved to be complementary in set-up and identical in solutions. ML task on the general expo

E. Vasserot

We express the product of the cohomology ring of the Hilbert scheme in terms of the center of the algebra of the symmetric group. We give a conjecture for the case of crepant resolutions of symplectic quotient singularities.

D. -Q. Zhang

We classify minimal pairs (X, G) for smooth rational projective surface X and finite group G of automorphisms on X. We also determine the fixed locus X^G and the quotient surface Y = X/G as well as the fundamental group of the smooth part of Y. The realization of each pair is included. Mori&#39;s extremal ray theory and recent results of Alexeev and also Amb

G. W. Wei, Yun Gu

We propose a conjugated filter oscillation reduction scheme for solving Burgers&#39; equation with high Reynolds numbers. Computational accuracy is tested at a moderately high Reynolds number for which analytical solution is available. Numerical results at extremely high Reynolds numbers indicate that the proposed scheme is efficient, robust and reliable for

Viktor L. Ginzburg

A new invariant of Poisson manifolds, a Poisson K-ring, is introduced. Hypothetically, this invariant is more tractable than such invariants as Poisson (co)homology. A version of this invariant is also defined for arbitrary algebroids. Basic properties of the Poisson K-ring are proved and the Poisson K-rings are calculated for a number of examples. In partic

Tae Seong Kim, Won-Ho Kye, Jae Kwan Kim

We analyze (2+1)-dimensional Gross-Neveu model with a Thirring interaction, where a vector-vector type four-fermi interaction is on equal terms with a scalar-scalar type one. The Dyson-Schwinger equation for fermion self-energy function is constructed up to next-to-leading order in 1/N expansion. We determine the critical surface which is the boundary betwee

D. S. Popovic, B. Sazdovic

Using canonical method the Liouville theory has been obtained as a gravitational Wess-Zumino action of the Polyakov string. From this approach it is clear that the form of the Liouville action is the consequence of the bosonic representation of the Virasoro algebra, and that the coefficient in front of the action is proportional to the central charge and mea

Velimir Bardek, Stjepan Meljanac

We describe generally deformed Heisenberg algebras in one dimension. The condition for a generalized Leibniz rule is obtained and solved. We analyze conditions under which deformed quantum-mechanical problems have a Fock-space representation. One solution of these conditions leads to a q-deformed oscillator already studied by Lorek et al., and reduces to the

Kazuo Fujikawa, Hiroaki Terashima

The use of the mass term of the gauge field as a gauge fixing term, which was discussed by Zwanziger, Parrinello and Jona-Lasinio in a large mass limit, is related to the non-linear gauge by Dirac and Nambu. We have recently shown that this use of the mass term as a gauge fixing term is in fact identical to the conventional local Faddeev-Popov formula withou

Y. M. Cho, D. G. Pak

We present a gauge independent method to construct the effective action of QCD, and calculate the one loop effective action of $SU(2)$ QCD in an arbitrary constant background field. Our result establishes the existence of a dynamical symmetry breaking by demonstrating that the effective potential develops a unique and stable vacuum made of the monopole conde

Gouranga C. Nayak, Walter Greiner

We compute the probabilty for the processes A -> q \bar{q}, gg via vacuum polarization in the presence of a classical space-time dependent non-abelian field A by applying the background field method of QCD. The processes we consider are leading order in gA and are simillar to A -> e^+e^- in QED. Gluons are treated like a matter field and gauge transformation

Shi-Lin Zhu, S. Puglia, M. J. Ramsey-Musolf

We calculate chiral corrections to the octet axial currents through ${\cal O}(p^3)$ using baryon chiral perturbation theory (BCPT). The relativistic BCPT framework allows one to sum an infinite series of recoil corrections at a given order in the chiral expansion. We also include SU(3)-breaking operators occuring at ${\cal O}(p^2)$ not previously considered.

O. J. P. Eboli, D. Zeppenfeld

Given its weak coupling to bottom quarks and tau leptons, the Higgs boson may predominantly decay into invisible particles like gravitinos, neutralinos, or gravitons. We consider the manifestation of such an invisibly decaying Higgs boson in weak boson fusion at the CERN LHC. Distinctive kinematic distributions of the two quark jets of the signal as compared

Marek Nowakowski

We discuss the derivation of Newtonian potentials in the framework of quantum field theory. We focus on two particular points: on long range forces i.e. forces which fall off as $1/r^n$ being mediated by light quanta like neutrinos or Goldstone bosons and on possible temperature dependence of such forces arising in situations when the exchanged quanta are in

Johan Bijnens, Joaquim Prades

We report on a calculation of epsilon&#39;/epsilon at next-to-leading in the 1/N_c expansion and to lowest order in Chiral Perturbation Theory. We also discuss the chiral corrections to our results and give the result of including the two known chiral corrections.

Johan Bijnens, Joaquim Prades

The K to pi pi system is analyzed in the chiral limit and at NLO in 1/N_c. The Delta I = 1/2 rule is reproduced and we obtain a large value for epsilon&#39; / epsilon.

K. Werner

We discuss the present status of microscopic models for RHIC, with an emphasis on models being realized via the Monte Carlo technique. This review is to a large extent based on the OSCAR3 workshop, where general concepts and new trends in this field have been discussed.

Eli Waxman

Observations suggest that gamma-ray bursts (GRBs) are produced by the dissipation of the kinetic energy of a relativistic fireball. In this talk, recent work on the production of high energy neutrinos by GRB fireballs is reviewed. A significant fraction of GRB energy is expected to be converted to an accompanying burst of high energy neutrinos. Photomeson in

Luis Amoreira, Pedro Alberto, Manuel Fiolhais

The multipole amplitudes for the N - Delta electromagnetic transition are computed in the framework of the linear sigma model and the chiral chromodielectric model for small and moderate photon virtualities. The models include quark and meson degrees of freedom and the nucleon and the delta are clusters of three valence hedgehog quarks surrounded by meson cl

S. A. Kulagin, A. V. Sidorov

We analyze the CCFR collaboration iron target data on the xF3 structure function making particular emphasis on the extraction of the higher twist contributions from data. Corrections for nuclear effects are applied in order to extract data on the structure function of the isoscalar nucleon. Our analysis confirms the observation made earlier, that the higher

S. R. Juarez W., S. F. Herrera H., P. Kielanowski, G. Mora H

The one loop Renormalization Group Equations for the Yukawa couplings of quarks are solved. From the solution we find the explicit energy dependence on $t=\ln E/μ$ of the evolution of the {\em down} quark masses $q=d,s,b$ from the grand unification scale down to the top quark mass $m_{t}$. These results together with the earlier published evolution of the {\

Bengt Petersson

In this talk I will first give a short discussion of some lattice results for QCD at finite temperature. I will then describe in some detail the technique of dimensional reduction, which in principle is a powerful technique to obtain results on the long distance properties of the quark-gluon plasma. Finally I will describe some new results, which test the te

UKQCD Collaboration, A. M. Green, J. Koponen, P. Pennanen

A brief review is given of attempts to understand the energies of four-quark systems calculated on a lattice in terms of nuclear-physics-inspired many-body techniques involving interquark potentials. Results are given for the next stage of this study where the wavefunctions of heavy-light mesons are also calculated on a lattice.

John Dainton

Photon structure derives from quantum fluctuation in quantum field theory to fermion and anti-fermion, and has been an experimentally established feature of electrodynamics since the discovery of the positron. In hadronic physics, the observation of factorisable photon structure is similarly a fundamental test of the quantum field theory Quantum Chromodynami

Luis O. Pimentel

The Wheeler-DeWitt equation is considered in the context of generalized scalar-tensor theories of gravitation for Bianchi type I cosmology. Exact solutions are found for two selfinteracting potentials and arbitary coupling function. The WKB wavefunctions are obtained and a family of solutions satisfying the Hawking-Page regularity conditions of wormholes are

Nick E. Mavromatos

I discuss a specific model of space-time foam, inspired by the modern non-perturbative approach to string theory (D-branes). The model views our world as a three brane, intersecting with D-particles that represent stringy quantum gravity effects, which can be real or virtual. In this picture, matter is represented generically by (closed or open) strings on t

Foster Provost, Tom Fawcett

In real-world environments it usually is difficult to specify target operating conditions precisely, for example, target misclassification costs. This uncertainty makes building robust classification systems problematic. We show that it is possible to build a hybrid classifier that will perform at least as well as the best available classifier for any target

David Eppstein

We consider worst case time bounds for NP-complete problems including 3-SAT, 3-coloring, 3-edge-coloring, and 3-list-coloring. Our algorithms are based on a constraint satisfaction (CSP) formulation of these problems; 3-SAT is equivalent to (2,3)-CSP while the other problems above are special cases of (3,2)-CSP. We give a fast algorithm for (3,2)-CSP and use

David Eppstein, Joseph Wang

Social studies researchers use graphs to model group activities in social networks. An important property in this context is the centrality of a vertex: the inverse of the average distance to each other vertex. We describe a randomized approximation algorithm for centrality in weighted graphs. For graphs exhibiting the small world phenomenon, our method esti

Les Carr, Steve Hitchcock, Wendy Hall, Stevan Harnad

Based on an empirical analysis of author usage of CoRR, and of its predecessor in the Los Alamos eprint archives, it is shown that CoRR has not yet been able to match the early growth of the Los Alamos physics archives. Some of the reasons are implicit in Halpern&#39;s paper, and we explore them further here. In particular we refer to the need to promote CoR

Aharon Kapitulnik, Nadya Mason, Steven A. Kivelson, Sudip Chakravarty

We discuss the effect of dissipation on quantum phase transitions. In particular we concentrate on the Superconductor to Insulator and Quantum-Hall to Insulator transitions. By invoking a phenomenological parameter $α$ to describe the coupling of the system to a continuum of degrees of freedom representing the dissipative bath, we obtain new phase diagrams f

T. Konishi, K. Morikawa, K. Kobayashi, T. Mizokawa

We report on results from high-energy spectroscopic measurements on CeFe2, a system of particular interest due to its anomalous ferromagnetism with an unusually low Curie temperature and small magnetization compared to the other rare earth-iron Laves phase compounds. Our experimental results indicate very strong hybridization of the Ce 4f states with the del

P. W. Brouwer, C. Mudry, A. Furusaki

We review recent work on the random hopping problem in a quasi-one-dimensional geometry of N coupled chains (quantum wire with off-diagonal disorder). Both density of states and conductance show a remarkable dependence on the parity of N. The theory is compared to numerical simulations.

Alba Theumann, B. Coqblin, S. G. Magalhaes, A. A. Schmidt

It is presented a theory that describes a spin glass phase at finite temperatures in Kondo lattice systems with an additional RKKY interaction represented by long range, random couplings among localized spins like in the Sherrington- Kirkpatrick (SK) spin glass model. The problem is studied within the functional integral formalism where the spin operators ar

Patrick Ahlrichs, Ralf Everaers, Burkhard Duenweg

We study single-chain motion in semidilute solutions of polymers of length N = 1000 with excluded-volume and hydrodynamic interactions by a novel algorithm. The crossover length of the transition from Zimm (short lengths and times) to Rouse dynamics (larger scales) is proportional to the static screening length. The crossover time is the corresponding Zimm t

C. Preis, C. Helm, K. Schmalzl, J. Keller

Subgap resonances in the I-V curves of layered superconductors are explained by the coupling between Josephson oscillations and phonons with dispersion in c-direction. In the presence of a magnetic field applied parallel to the layers additional structures due to fluxon motion appear. Their coupling with phonons is investigated theoretically and a shift of t

T. Kontos, M. Aprili, J. Lesueur, X. Grison

Planar tunneling spectroscopy reveals damped oscillations of the superconducting order parameter induced into a ferromagnetic thin film by the proximity effect. The oscillations are due to the finite momentum transfer provided to Cooper pairs by the splitting of the spin up and down bands in the ferromagnet. As a consequence, for negative values of the super

G. Manoj, P. Ray

We show that the persistence probability $P(t,L)$, in a coarsening system of linear size $L$ at a time $t$, has the finite size scaling form $P(t,L)\sim L^{-zθ}f(\frac{t}{L^{z}})$ where $θ$ is the persistence exponent and $z$ is the coarsening exponent. The scaling function $f(x)\sim x^{-θ}$ for $x \ll 1$ and is constant for large $x$. The scaling form impli

Lorenzo Matassini, Rainer Hegger, Holger Kantz, Claudia Manfredi

This paper provides a way to classify vocal disorders for clinical applications. This goal is achieved by means of geometric signal separation in a feature space. Typical quantities from chaos theory (like entropy, correlation dimension and first lyapunov exponent) and some conventional ones (like autocorrelation and spectral factor) are analysed and evaluat

F. Dalfovo, S. Stringari

Angular momentum can be transferred to a trapped Bose-Einstein condensate by distorting its shape with an external rotating field, provided the rotational frequency is larger than a critical frequency fixed by the energy and angular momentum of the excited states of the system. By using the Gross-Pitaevskii equation and sum rules, we explore the dependence o

Kazuhito Hatano, David Branch, Eric J. Lentz, E. Baron

A comparison of the ratio of the depths of two absorption features in the spectra of TypeIa supernovae (SNe Ia) near the time of maximum brightness with the blueshift of the deep red Si II absorption feature 10 days after maximum shows that the spectroscopic diversity of SNe Ia is multi-dimensional. There is a substantial range of blueshifts at a given value

L. Vanzi, L. H. Hunt, T. X. Thuan, Y. I. Izotov

We present near-infrared (NIR) spectra, deep J, H and K low-resolution ima ges, and high-resolution images in J and Ks of the low-metallicity blue dwarf gal axy SBS 0335-052. These new NIR data, together with optical and mid-infrared data from the literature, are used to constrain the properties and the star formation history of the galaxy. The NIR spectral

Anita Krishnamurthi, Christopher S. Reynolds, Jeffrey L. Linsky, Eduardo Martin

We present results from a 36-ksec observation of the core of the Pleiades open cluster using ACIS-I on the Chandra X-ray Observatory. We have detected 57 sources, most of which do not have previously known optical counterparts. Follow-up photometry indicates that many of the detections are likely to be AGNs, in accordance with extragalactic source counts, bu

Cristina Chiappini, Francesca Matteucci, Donatella Romano

We present theoretical results on the galactic abundance gradients of several chemical species for the Milky Way disk, obtained using an improved version of the two-infall model of Chiappini, Matteucci, & Gratton (1997) that incorporates a more realistic model of the galactic halo and disk. This improved model provides a satisfactory fit to the elemental abu

C. Impey, C. Petry

We match quasars discovered in a multi-color survey centered on the northern Hubble Deep Field (HDF) with radio sources from an ultra-deep radio survey. Although 3 out of 12 quasars are detected at a level below 0.2 mJy at 1.4 GHz, all of the quasars in the search area are radio-quiet by the criterion L_r < 10^{25} h^{-1}_{50} W/Hz. We combine this informati

K. A. Venn, D. J. Lennon, A. Kaufer, J. K. McCarthy

We have obtained the first high resolution spectra of individual stars in the dwarf irregular galaxy, NGC 6822. The spectra of the two A-type supergiants were obtained at the VLT and Keck Observatories, using UVES and HIRES, respectively. A detailed model atmospheres analysis has been used to determine their atmospheric parameters and elemental abundances. T

Jeffrey N. Cuzzi, Robert C. Hogan, Julie M. Paque, Anthony R. Dobrovolskis

Size-selective concentration of particles in a weakly turbulent protoplanetary nebula may be responsible for the initial collection of chondrules and other constituents into primitive body precursors. This paper presents the main elements of this process of turbulent concentration. In the terrestrial planet region, both the characteristic size and size distr