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October 2001 arXiv papers — page 9

Showing 801–900 of 3,352 papers

  1. I. Brevik, S. D. Odintsov

    The results of the paper of Verlinde [hep-th/0008140], discussing the holographic principle in a radiation dominated universe, are extended when allowing the cosmic fluid to possess a bulk viscosity. This corresponds to a non-conformally invariant theory. The generalization of the Cardy-Verlinde entropy formula to the case of a viscous universe seems from a

  2. Biswarup Mukhopadhyaya, Somasri Sen, Soumitra SenGupta

    We study the consequences of spacetime torsion coexisting with gravity in the bulk in scenarios with large extra dimensions. Having linked torsion with the Kalb-Ramond antisymmetric tensor field arising in string theories, we examine its artifacts on the visible 3-brane when the extra dimensions are compactified. It is found that while torsion would have led

  3. Abhijit Bandyopadhyay, Sandhya Choubey, Srubabati Goswami, Kamales Kar

    We examine the solar neutrino problem in the context of the realistic three neutrino mixing scenario including the SNO charged current (CC) rate. The two independent mass squared differences $Δm^2_{21}$ and $Δm^2_{31} \approx Δm^2_{32}$ are taken to be in the solar and atmospheric ranges respectively. We incorporate the constraints on $Δ$m$^2_{31}$ as obtain

  4. Oscar Bolina

    This paper has been withdrawn by the author.

  5. Anders W. Sandvik

    The two-dimensional antiferromagnetic S=1/2 Heisenberg model with random site dilution is studied using quantum Monte Carlo simulations. Ground state properties of the largest connected cluster on L*L lattices, with L up to 64, are calculated at the classical percolation threshold. In addition, clusters with a fixed number Nc of spins on an infinite lattice

  6. Richard D. Gill

    An experimentally observed violation of Bell's inequality is supposed to show the failure of local realism to deal with quantum reality. However, finite statistics and the time sequential nature of real experiments still allow a loophole for local realism, known as the memory loophole. We show that the randomized design of the Aspect experiment closes th

  7. M. K. Mak, T. Harko

    We present a class of exact solutions of Einstein's gravitational field equations describing spherically symmetric and static anisotropic stellar type configurations. The solutions are obtained by assuming a particular form of the anisotropy factor. The energy density and both radial and tangential pressures are finite and positive inside the anisotropic

  8. Kiyoshi Higashijima, Tetsuji Kimura, Muneto Nitta

    We construct the non-compact Calabi-Yau manifolds interpreted as the complex line bundles over the Hermitian symmetric spaces. These manifolds are the various generalizations of the complex line bundle over CP^{N-1}. Imposing an F-term constraint on the line bundle over CP^{N-1}, we obtain the line bundle over the complex quadric surface Q^{N-2}. On the othe

  9. Y. Kiem, S. Lee, S. -J. Rey, H. -T. Sato

    In noncommutative field theories, it was known that one-loop effective action describes propagation of non-interacting open Wilson lines, obeying the flying dipole's relation. We show that two-loop effective action describes cubic interaction among `closed string' states created by open Wilson lines. Taking d-dimensional noncommutative [Φ^3] theory a

  10. Eric Dennis, Alexei Kitaev, Andrew Landahl, John Preskill

    We analyze surface codes, the topological quantum error-correcting codes introduced by Kitaev. In these codes, qubits are arranged in a two-dimensional array on a surface of nontrivial topology, and encoded quantum operations are associated with nontrivial homology cycles of the surface. We formulate protocols for error recovery, and study the efficacy of th

  11. B. Georgeot, D. L. Shepelyansky

    We show explicitly that high harmonics of the classical Liouville density distribution in the chaotic regime can be obtained efficiently on a quantum computer [1,2]. As was stated in [1], this provides information unaccessible for classical computer simulations, and replies to the questions raised in [3,4].

  12. Seth Lloyd

    Merely by existing, all physical systems register information. And by evolving dynamically in time, they transform and process that information. The laws of physics determine the amount of information that a physical system can register (number of bits) and the number of elementary logic operations that a system can perform (number of ops). The universe is a

  13. Markus A. Cirone

    We propose a new approach to the problem of defining the degree of entanglement between two particles in a pure state with Hilbert spaces of arbitrary finite dimensions. The central idea is that entanglement gives rise to correlations between the particles that do not occur in separable states. We individuate the contributions of these correlations to the jo

  14. Jaromir Fiurasek

    We propose a scheme for conditional generation of two-mode N-photon path-entangled states of traveling light field. These states may find applications in quantum optical lithography and they may be used to improve the sensitivity of interferometric measurements. Our method requires only single-photon sources, linear optics (beam splitters and phase shifters)

  15. K. Inoue, M. Ohya, I. V. Volovich

    We study the chaotic behaviour and the quantum-classical correspondence for the baker's map. Correspondence between quantum and classical expectation values is investigated and it is numerically shown that it is lost at the logarithmic timescale. The quantum chaos degree is computed and it is demonstrated that it describes the chaotic features of the mod

  16. Peter Rowlands

    A brief history is given of the factor 2, starting in the most elementary considerations of geometry and kinematics of uniform acceleration, and moving to relativity, quantum mechanics and particle physics. The basic argument is that in all the significant cases in which the factor 2 or 1/2 occurs in fundamental physics, whether classical, quantum or relativ

  17. H. Mueller, J. R. Shepard, J. Piekarewicz

    The Contractor Renormalization (CORE) method is applied in combination with modern effective-theory techniques to the nuclear many-body problem. A one-dimensional--yet ``realistic''--nucleon-nucleon potential is introduced to test these novel ideas. It is found that the magnitude of ``model-space'' (CORE) corrections diminishes considerably w

  18. E. Teran, V. E. Oberacker, A. S. Umar

    We present the first set of results of solving the Hartree-Fock-Bogoliubov equations, which describe the self-consistent mean field theory with pairing interaction. Calculations for even-even nuclei are carried out on a two-dimensional axially symmetric lattice, in coordinate space. An important aspect of our method is the proper representation of the quasi-

  19. M. H. Wood, C. R. Brune, B. M. Fisher, H. J. Karwowski

    Angular distributions of sigma(theta), A_y, iT_11, T_20, T_21, and T_22 have been measured for d-p scattering at E_c.m.=667 keV. This set of high-precision data is compared to variational calculations with the nucleon-nucleon potential alone and also to calculations including a three-nucleon (3N) potential. Agreement with cross-section and tensor analyzing p

  20. J. Asch, R. D. Benguria, P. Šťovíček

    We derive the form of the asymptotic series, as $t\to +\infty$, for a general solution $h(t)$ of the non-linear differential equation $h(t)^{3}(h''(t)+h'(t))=1$.

  21. Pierluigi Contucci, Sandro Graffi, Stefano Isola

    For the long-range deterministic spin models with glassy behaviour of Marinari, Parisi and Ritort we prove weighted factorization properties of the correlation functions which represent the natural generalization of the factorization rules valid for the Curie-Weiss case.

  22. Michael R. Bush

    The $p$-group generation algorithm from computational group theory is used to obtain information about large quotients of the pro-2 group $G = \text{Gal} (k^{nr,2}/k)$ for $k = \mathbb{Q}(\sqrt{d})$ with $d = -445, -1015, -1595, -2379$. In each case we are able to narrow the identity of $G$ down to one of a finite number of explicitly given finite groups. Fr

  23. John H. Coates, Peter Schneider, Ramdoria Sujatha

    Let $p$ be a prime number, and $G$ a compact $p$-adic Lie group. We recall that the Iwasawa algebra $Λ(G)$ is defined to be the completed group ring of $G$ over the ring of $p$-adic integers. Interesting examples of finitely generated modules over $Λ(G),$ in which $G$ is the image of Galois in the automorphism group of a $p$-adic Galois representation, aboun

  24. Kay Wingberg

    In this paper we define a topology with sufficiently good properties on the set of prime ideals of a number field.

  25. Luis V. Dieulefait

    We give an effective version of a result reported by Serre asserting that the images of the Galois representations attached to an abelian surface with $\End(A)= \mathbb{Z}$ are as large as possible for almost every prime. Our algorithm depends on the truth of Serre's conjecture for two dimensional odd irreducible Galois representations. Assuming this con

  26. Charles Fefferman, C. Robin Graham

    This article presents a new definition of Branson's Q-curvature in even-dimensional conformal geometry. We derive the Q-curvature as a coefficient in the asymptotic expansion of the formal solution of a boundary problem at infinity for the Laplacian in the Poincare metric associated to the conformal structure. This gives an easy proof of the result of Gr

  27. Antonio Laface

    Let (M,L) be a polarized manifold and let G(M,L) be the graded algebra generated by H^0(M,iL) in degree i. The aim of this paper is to establish a connection between the generators of G(M,L) and the very ampleness of the line bundle rL. Some applications are given.

  28. Andrei Okounkov

    We give a concise direct proof of the orthogonality of interpolation Macdonald polynomials with respect to the Fourier pairing and briefly discuss some immediate applications of this orthogonality, such as the symmetry of the Fourier pairing and the binomial formula.

  29. Bouchta Bouali

    In this paper, we extend the Banach-Stone theorem to the non commutative case, i.e, we give a partial answere to the question 2.1 of [13], and we prove that the structure of the postliminal C*-algebras A determines the topology of its primitive ideals space.

  30. O. Arratia, M. A. del Olmo

    We analyze the elements characterizing the theory of induced representations of Lie groups, in order to generalize it to quantum groups. We emphasize the geometric and algebraic aspects of the theory, because they are more suitable for generalization in the framework of Hopf algebras. As an example, we present the induced representations of a quantum deforma

  31. O. Arratia, M. A. del Olmo

    In this paper we show how to construct explicitly induced representations for bicrossproduct Hopf algebras with abelian kernels starting from one-dimensional characters of the commutative sector. We introduce this technique by means of two concrete physical examples: two quantum deformations of the (1+1) Galilei algebra.

  32. C. Dupont

    In this paper, we study the attracting basins of the origin in C^(k+1) for the polynomial lifts of Lattes examples. We show that their boundaries are obtained as quotient of a spherical hypersurface and we explicit the singularities that appear. These domains are surprising, because they are very close to the ball, and admit a non injective self proper holom

  33. Everett W. Howe

    Given a prime power q, for every pair of positive integers m and n with m dividing the GCD of n and q-1, we construct a modular curve over F_q that parametrizes elliptic curves over F_q along with F_q-defined points P and Q of order m and n, respectively, with P and (n/m)Q having a given Weil pairing. Using these curves, we estimate the number of elliptic cu

  34. Bennett Chow

    Based on a suggestion of Richard Hamilton, we give an alternate proof of his matrix Harnack inequality for solutions of the Ricci flow with positive curvature operator. This Harnack inequality says that a certain endomorphism, consisting of an expression in the curvature and its first two covariant derivatives, of the bundle of 2-forms Whitney sum 1-forms is

  35. K. Sogut, A. Havare, I. Acikgoz

    We aimed to obtain the energy levels of spin-1 particles moving in a constant magnetic field. The method used here is completely algebraic. In the process to obtain the energy levels the wave function is choosen in terms of Laguerre Polynomials.

  36. J. A. Nieto

    A mechanism to find different Weyl invariant p-branes and Dp-branes actions is explained. Our procedure clarifies the Weyl invariance for such systems. Besides, by considering gravity-dilaton effective action in higher dimensions we also derive a Weyl invariant action for p-branes. We argue that this derivation provides a geometrical scenario for the Weyl in

  37. Jorgen Rasmussen, Mark A. Walton

    We consider three-point couplings in simple Lie algebras -- singlets in triple tensor products of their integrable highest weight representations. A coupling can be expressed as a linear combination of products of finitely many elementary couplings. This carries over to affine fusion, the fusion of Wess-Zumino-Witten conformal field theories, where the expre

  38. Richard L. Hall, Wolfgang Lucha, F. F. Schoberl

    We analyze the (discrete) spectrum of the semirelativistic ``spinless-Salpeter'' Hamiltonian H = β\sqrt{m^2 + p^2} + V(r), beta > 0, where V(r) represents an attractive, spherically symmetric potential in three dimensions. In order to locate the eigenvalues of H, we extend the ``envelope theory,'' originally formulated only for nonrelativisti

  39. Changrim Ahn, Chanju Kim, Chaiho Rim

    We study the ultraviolet asymptotics in $A_n$ affine Toda theories with integrable boundary actions. The reflection amplitudes of non-affine Toda theories in the presence of conformal boundary actions have been obtained from the quantum mechanical reflections of the wave functional in the Weyl chamber and used for the quantization conditions and ground-state

  40. M. Bordag, K. Kirsten

    The first heat kernel coefficients are calculated for a dispersive ball whose permittivity at high frequency differs from unity by inverse powers of the frequency. The corresponding divergent part of the vacuum energy of the electromagnetic field is given and ultraviolet divergencies are seen to be present. Also in a model where the number of atoms is fixed

  41. Gennaro Corcella, Alexander D. Mitov

    We study the fragmentation of the b quark in top decay in NLO QCD, within the framework of perturbative fragmentation, which allows one to resum large logarithms $\sim\log (m_t^2/m_b^2)$. We show the b-energy distribution, which we compare with the exact ${\cal O} (α_S)$ result for a massive b quark. We use data from $e^+e^-$ machines in order to describe th

  42. Gerhard Buchalla

    The theory of rare $K$ decays is reviewed, emphasizing short-distance processes and the prospects to probe the physics of flavour. A brief overview of the subject is presented, along with a more detailed discussion of the theory of $K\toπν\barν$ decays.

  43. F. Becattini, G. Passaleva

    A detailed analysis of transverse momentum spectra of several identified hadrons in high energy collisions within the canonical framework of the statistical model of hadronisation is performed. The study of particle momentum spectra requires an extension of the statistical model formalism used to handle particle multiplicities, which is described in detail s

  44. Borut Bajc, Goran Senjanovic, Francesco Vissani

    Massive neutrinos are a generic prediction of SO(10), and models of unification cry for supersymmetry. Since we have a rather detailed information on neutrino and charged fermion masses, the real question is: how/whether it is possible to build a SO(10) supersymmetric model, that correctly incorporates fermion masses. We show that a simple construction is po

  45. Prasanta Das, Uma Mahanta

    In this paper we determine how the beta function for the top Yukawa coupling to one loop is modified by a light stabilized radion in the Randall-Sundrum model. We then use this beta function together with β(λ) to deteremine lower bounds on the radion vev <ϕ> for different values of λ(m_z) and m_ϕ by demanding that both g_t(μ) and λ(μ) should remain perturbat

  46. S. M. Bilenky

    A short review of the status of neutrino mixing and neutrino oscillations is given. The basics of neutrino mixing and oscillations is discussed. The latest evidences of neutrino oscillations obtained in the Super-Kamiokande and the SNO solar neutrino experiments and in the Super-Kamiokande atmospheric neutrino experiment are considered. The results of solar

  47. M. Biyajima, M. Ide, T. Mizoguchi, N. Suzuki

    Recently interesting data on $dN_{ch}/dη$ in Au-Au collisions ($η=-\ln \tan (θ/2)$) with the centrality cuts have been reported by PHOBOS Collaboration. Their data are usually divided by the number of participants (nucleons) in collisions. Instead of this way, using the total multiplicity $N_{ch} = \int (dN_{ch}/dη)dη$, we find that there is scaling phenomen

  48. C T Sachrajda

    I review two subjects in which lattice simulations are making, or can make in the future, a significant contribution to particle physics phenomenology. The first subject is the evaluation of quantities which enter into the determination of the vertex $A$ of the unitarity triangle from experimental measurements of decay rates and mixing amplitudes. These quan

  49. O. V. Zenin, V. V. Ezhela, S. B. Lugovsky, M. R. Whalley

    All available data on the total cross sections and R-ratio of e^+ e^- --> hadrons are compiled from the PPDS(DataGuide), PPDS(ReacData) and HEPDATA(Reaction) databases and transformed to a compilation of data on the e^+ e^- --> quark antiquark --> hadrons in the continuum region which can be used in tests of the parton model and pQCD calculations. This evalu

  50. Dean Lee

    We describe a first attempt to understand dynamical fermions within a Hamiltonian framework. As a testing ground we study compact QED3 which shares some important features of QCD4 such as confinement, glueballs, mesons, and chiral symmetry breaking. We discuss the methods used and show data for the chiral condensate.

  51. J. N. Simone, S. Hashimoto, A. S. Kronfeld, P. B. Mackenzie

    We summarize our lattice QCD study of the form factor at zero recoil in the decay anti-B --> D* lepton anti-neutrino. After careful consideration of all sources of systematic uncertainty, we find, h_A1(1) = 0.913(+0.024-0.017)(+0.017-0.030), where the first uncertainty is from statistics and fitting while the second combined uncertainty is from all other sys

  52. J. Froehlich, P. A. Marchetti

    We describe a new order parameter for the confinement-deconfinement transition in lattice SU(2) Yang-Mills theory. It is expressed in terms of magnetic monopole field correlators represented as sums over sheets of center vortices. Our construction establishes a link between &#34;abelian&#34; and &#34;center dominance&#34;. It avoids an inconsistency in the t

  53. P. H. Damgaard

    We review the exact results for microscopic Dirac operator spectra based on either Random Matrix Theory, or, equivalently, chiral Lagrangians. Implications for lattice calculations are discussed.

  54. M. I. Polikarpov, A. I. Veselov, M. A. Zubkov

    We consider the electroweak theory without fundamental scalar field. The topological excitation of the SU(2)*U(1) theory (the monopole) plays the role of the Higgs field, it carries the SU(2)*U(1) topological charge due to the theta--term of the special type.

  55. LHPC, H. Rudolf Fiebig

    A system of two static quarks, at fixed distances r, and two light quarks is studied on an anisotropic lattice. Excitations by operators emphasizing quark or gluon degrees of freedom are examined. The maximum entropy method is applied in the spectral analysis. These simulations ultimately aim at learning about mechanisms of hadronic interaction.

  56. L3 Collaboration

    A search, in e^+e^- collisions, for chargino, neutralino, scalar lepton and scalar quark pair-production is performed, without assuming R-parity conservation in decays, in the case that only one of the coupling constants lambda_ijk or lambda&#39;&#39;_ijk is non-negligible. No signal is found in data up to a centre-of-mass energy of 208GeV. Limits on the pro

  57. The DELPHI Collaboration, J. Abdallah

    Technicolor represents a viable alternative to the Higgs mechanism for generating gauge boson masses. Searches for technicolor particles rho_T and pi_T have been performed in the data collected by the DELPHI experiment at LEP at centre-of-mass energies between 192 and 208 GeV corresponding to an integrated luminosity of 452 pb^{-1}. Good agreement is observe

  58. C. Chicone, B. Mashhoon

    The characteristics of the memory of accelerated motion in Minkowski spacetime are discussed within the framework of the nonlocal theory of accelerated observers. Two types of memory are distinguished: kinetic and dynamic. We show that only kinetic memory is acceptable, since dynamic memory leads to divergences for nonuniform accelerated motion.

  59. Adam D. Helfer

    A simple ordinary differential equation is derived governing the red-shifts of wave-fronts propagating through a non-stationary spherically symmetric space-time. Approach to an event horizon corresponds to approach to a fixed point; in general, the phase portrait of the equation illuminates the qualitative features of the geometry. In particular, the asympto

  60. J. W. Maluf, A. Goya

    We consider the class of space-time defects investigated by Puntigam and Soleng. These defects describe space-time dislocations and disclinations (cosmic strings), and are in close correspondence to the actual defects that arise in crystals and metals. It is known that in such materials dislocations and disclinations require a small and large amount of energ

  61. Laszlo B Szabados

    It is shown that the Chern-Simons functional, built in the spinor representation from the initial data on spacelike hypersurfaces, is invariant with respect to infinitesimal conformal rescalings if and only if the vacuum Einstein equations are satisfied. As a consequence, we show that in the phase space the Hamiltonian constraint of vacuum general relativity

  62. G. Allemandi, M. Francaviglia, M. Raiteri

    A general recipe proposed elsewhere to define, via Noether theorem, the variation of energy for a natural field theory is applied to Einstein-Maxwell theory. The electromagnetic field is analysed in the geometric framework of natural bundles. Einstein-Maxwell theory turns then out to be natural rather than gauge-natural. As a consequence of this assumption a

  63. Miguel Alcubierre, F. Siddhartha Guzman, Tonatiuh Matos, Dario Nunez

    We present a scenario for galaxy formation based on the hypothesis of scalar field dark matter. We interpret galaxy formation through the collapse of a scalar field fluctuation. We find that a cosh potential for the self-interaction of the scalar field provides a reasonable scenario for galactic formation, which is in agreement with cosmological observations

  64. W. B. Belayev

    Presented cosmological model is 3D brane world sheet moved in extra dimension with variable scale factor. Analysis of the geodesic motion of the test particle gives settle explanation of the Pioneer effect. It is found that for considered metric the solution of the semi-classical Einstein equations with various parameters conforms to isotropic expanded and a

  65. Rens Bod

    Structured language models for speech recognition have been shown to remedy the weaknesses of n-gram models. All current structured language models are, however, limited in that they do not take into account dependencies between non-headwords. We show that non-headword dependencies contribute to significantly improved word error rate, and that a data-oriente

  66. Rens Bod

    We aim at finding the minimal set of fragments which achieves maximal parse accuracy in Data Oriented Parsing. Experiments with the Penn Wall Street Journal treebank show that counts of almost arbitrary fragments within parse trees are important, leading to improved parse accuracy over previous models tested on this treebank (a precision of 90.8% and a recal

  67. Frank Harary, Wolfgang Slany, Oleg Verbitsky

    In the graph avoidance game two players alternatingly color edges of a graph G in red and in blue respectively. The player who first creates a monochromatic subgraph isomorphic to a forbidden graph F loses. A symmetric strategy of the second player ensures that, independently of the first player&#39;s strategy, the blue and the red subgraph are isomorphic af

  68. Victor Gurarie, Alexander E. Lobkovsky

    Many lamellar systems exhibit strongly anisotropic diffusion. When the diffusion across the lamellae is slow, an alternative mechanism for transverse transport becomes important. A tracer particle can propagate in the direction normal to the lamellae, never leaving a particular layer, by going around a screw dislocation. Given the density of positive and neg

  69. Ming Shaw, Z. Y. Weng, C. S. Ting

    We investigate the superconducting transition in a doped antiferromagnet. Based on the phase string framework of the t-J model, an effective model describing the phase-coherence transition is obtained and is studied through duality transformation and renormalization group treatment . We show that such a topological transition is controlled by spin excitation

  70. R. Mueller, C. Janowitz, M. Schneider, R. -St. Unger

    We present a comprehensive study performed with high-resolution angle-resolved photoemission spectroscopy on triple-layered Bi2Sr2Ca2Cu3O10+d single crystals. By measurements above TC the Fermi surface topology defined by the Fermi level crossings of the CuO2-derived band was determined. A hole-like Fermi surface as for single and double-CuO2 layered Bi-base

  71. Uwe Grimm, Przemyslaw Repetowicz

    We consider Ising models defined on periodic approximants of aperiodic graphs. The model contains only a single coupling constant and no magnetic field, so the aperiodicity is entirely given by the different local environments of neighbours in the aperiodic graph. In this case, the partition function zeros in the temperature variable, also known as the Fishe

  72. K. Hasselbach, D. Mailly, J. R. Kirtley

    We report on the dependence on field and temperature of the critical current of micro-SQUIDs: SQUIDs with diameters as small as 1 micron, using Dayem bridges as weak links. We model these SQUIDs by solving the Ginzburg-Landau equations with appropriate boundary conditions to obtain the supercurrent-phase relationships. These solutions show that the phase dro

  73. J. M. Hernandez, F. Torres, E. Molins, J. Tejada

    The question addressed in this paper is that of the influence of the density of dislocations on the spin tunneling in Mn12 clusters. We have determined the variation in the mosaicity of the crystal structure of fresh and thermally treated single crystals of Mn12 by analyzing the widening of low angle X-ray diffraction peaks. It has also been well established

  74. E. E. Takhtamirov, V. A. Volkov

    The Kohn-Luttinger envelope-function method is generalized to the case of heterostructures with atomically sharp heterojunctions based on lattice-matched layers of related semiconductors with zinc-blende symmetry. For electron states near the Γpoint in (001) heterostructures the single-band effective-mass equation is derived, taking into account both the spa

  75. K. P. Meletov, J. Arvanitidis, M. P. Kulakov, N. N. Kolesnikov

    Raman spectra of the MgB2 ceramic samples were measured as a function of pressure up to 32 GPa at room temperature. The spectrum at normal conditions contains a very broad peak at ~590 cm-1 related to the E2g phonon mode. The frequency of this mode exhibits a strong linear dependence in the pressure region from 5 to 18 GPa, whereas beyond this region the slo

  76. Juan M. Lopez, Henrik J. Jensen

    Fungal colonies are able to exhibit different morphologies depending on the enviromental conditions. This allows them to cope with and adapt to external changes. When grown in solid or semi-solid media the bulk of the colony is compact and several morphological transitions have been reported to occur as the external conditions are varied. Here we show how a

  77. David S. Dean, Satya N. Majumdar

    We consider the Newtonian dynamics of a massive particle in a one dimemsional random potential which is a Brownian motion in space. This is the zero temperature nondamped Sinai model. As there is no dissipation the particle oscillates between two turning points where its kinetic energy becomes zero. The period of oscillation is a random variable fluctuating

  78. Shoji Yamamoto, Masanori Ichioka

    Motivated by recent stimulative observations in halogen (X)-bridged binuclear transition-metal (M) complexes, which are referred to as MMX chains, we study solitons in a one-dimensional three-quarter-filled charge-density-wave system with both intrasite and intersite electron-lattice couplings. Two distinct ground states of MMX chains are reproduced and the

  79. Belal E. Baaquie

    In a recent formulation of a quantum field theory of forward rates, the volatility of the forward rates was taken to be deterministic. The field theory of the forward rates is generalized to the case of stochastic volatility. Two cases are analyzed, firstly when volatility is taken to be a function of the forward rates, and secondly when volatility is taken

  80. I. V. Tokatly, A. G. Tsibizov, A. A. Gorbatsevich

    The envelope-function method with generalized boundary conditions is applied to the description of localized and resonant interface states. A complete set of phenomenological conditions which restrict the form of connection rules for envelope functions is derived using the Hermiticity and symmetry requirements. Empirical coefficients in the connection rules

  81. Masaru Onoda, Naoto Nagaosa

    The anomalous Hall effect in two-dimensional ferromagnets is discussed to be the physical realization of the parity anomaly in (2+1)D, and the band crossing points behave as the topological singularity in the Brillouin zone. This appears as the sharp peaks and the sign changes of the transverse conductance $σ_{xy}$ as a function of the Fermi energy and/or th

  82. D. S. Golubev, A. D. Zaikin, Gerd Schön

    The quantum coherence of electrons can be probed by studying weak localization corrections to the conductivity. Interaction effects lead to dephasing, with electron-electron interactions being the important intrinsic mechanism. A controversy exists whether or not the dephasing rate, as measured in a weak localization experiment, vanishes at low temperatures.

  83. Anatoli Polkovnikov, Subir Sachdev, Matthias Vojta, Eugene Demler

    Recent neutron scattering, nuclear magnetic resonance, and scanning tunneling microscopy experiments have yielded valuable new information on the interplay between charge and spin density wave order and superconductivity in the cuprate superconductors, by using an applied perpendicular magnetic field to tune the ground state properties. We compare the result

  84. J. P. Huang, K. W. Yu, G. Q. Gu

    We present a theoretical study of electrorotation (ER) of two spherical particles under the action of a rotating electric field. When the two particles approach and finally touch, the mutual polarization interaction between the particles leads to a change in the dipole moment of the individual particle and hence the ER spectrum, as compared to that of the we

  85. M. Franz, Z. Tesanovic

    Within the phase fluctuation model for the pseudogap state of cuprate superconductors we identify a novel statistical &#34;Berry phase&#34; interaction between the nodal quasiparticles and fluctuating vortices. The effective action describing this model assumes the form of an anisotropic Euclidean quantum electrodynamics in (2+1) dimensions (QED_3) and natur

  86. Roman Rafikov

    Gap formation in a gas disk triggered by disk-planet tidal interaction is considered. Density waves launched by the planet are assumed to be damped as a result of their nonlinear evolution leading to shock formation and its subsequent dissipation. As a consequence wave angular momentum is transferred to the disk,leading to evolution of its surface density. P

  87. H. Shang, A. E. Glassgold, F. H. Shu, S. Lizano

    In order to compare the x-wind with observations, one needs to be able to calculate its thermal and ionization properties. We formulate the physical basis for the streamline-by-streamline integration of the ionization and heat equations of the steady x-wind. In addition to the well-known processes associated with the interaction of stellar and accretion-funn

  88. H. R. Schmitt, J. S. Ulvestad, R. R. J. Antonucci, C. J. Clarke

    We present a series of statistical tests using homogeneous data and measurements for a sample of Seyfert galaxies. These galaxies were selected from mostly isotropic properties, their far infrared fluxes and warm infrared colors, which provide a considerable advantage over the criteria used by most investigators in the past, like ultraviolet excess. Our resu

  89. H. R. Schmitt, A. L. Kinney, J. B. Hutchings, J. S. Ulvestad

    We discuss the viability of shocks as the principal source of ionization for the Narrow Line Region of Seyfert galaxies. We present the preliminary results of [OIII]5007A and radio 3.6 cm imaging surveys of Seyferts, discuss the effects of shocks in the ionization of two galaxies, and also calculate an upper limit to the Hbeta luminosity that can be due to s

  90. T. Mazeh, L. Prato, M. Simon, E. Goldberg

    This paper outlines an infrared spectroscopic technique to measure the radial velocities of faint secondaries in known single-lined binaries. The paper presents our H-band observations with the CSHELL and Phoenix spectrographs and describes detections of three low-mass secondaries in main-sequence binaries: G147-36, G164-67, and HD144284 with mass ratios of

  91. James S. Ulvestad, Luis C. Ho

    The low-luminosity active galactic nuclei in NGC 3147, NGC 4203, and NGC 4579 have been imaged at four frequencies with the Very Long Baseline Array. The galaxies are unresolved at all frequencies, with size upper limits of $10^3-10^4$ times the Schwarzschild radii of their central massive black holes. The spectral indices between 1.7 and 5.0 GHz range from

  92. A. H. Corsico, L. G. Althaus, O. G. Benvenuto, A. M. Serenelli

    In this letter we investigate the pulsational properties of ZZ Ceti stars on the basis of new white dwarf evolutionary models calculated in a self-consistent way with the predictions of time dependent element diffusion and nuclear burning. In addition, full account is taken of the evolutionary stages prior to the white dwarf formation. Emphasis is placed on

  93. Y. -Z. Qian, G. J. Wasserburg

    (Abridged) We determine the yields of Na to Ni for Type II supernovae (SNe II) and the yield patterns of the same elements for Type Ia supernovae (SNe Ia) and very massive (>100 M_sun) stars (VMS) using a phenomenological model of stellar nucleosynthesis and the data on a number of stars with -4<[Fe/H]<-3, a single star with [Fe/H]=-2.04, and the sun. We con

  94. Philip Massey

    We present photometry and a preliminary interpretation of a UBVR survey of the Large and Small Magellanic Clouds. We determine improved values for the relative number of blue and red supergiants. We also compare the relative number of Red Supergiants (RSGs) and Wolf-Rayet stars, demonstrating a strong, tight correlation with metallicity, and reinvestigate th

  95. Xiao-Hu Yang, Long-Long Feng, Yao-Quan Chu, Li-Zhi Fang

    In this paper, we develop a theory of redshift distortion of the galaxy power spectrum in the discrete wavelet transform (DWT) representation. Because the DWT power spectrum is dependent of both the scale and shape (configuration) of the decomposition modes, it is sensitive to distortion of shape of the field. On the other hand, the redshift distortion cause

  96. Z. Y. Wu, K. P. Tian, L. Balaguer-Nunez, C. Jordi

    Absolute proper motions, their corresponding errors and membership probabilities of 501 stars in the intermediate-age open cluster NGC2548 region are determined from MAMA measurements of 10 photographic plates. The plates have the maximum epoch difference of 82 years and they were taken with the double astrograph at Zo-Se station of Shanghai Observatory, whi

  97. Ken&#39;ichi Nomoto, Keiichi Maeda, Hideyuki Umeda

    We review the characteristics of nucleosynthesis in &#39;Hypernovae&#39;, i.e., supernovae with very large explosion energies ($ \gsim 10^{52} $ ergs). The hypernova yields compared to those of ordinary core-collapse supernovae show the following characteristics: 1) Complete Si-burning takes place in more extended region, so that the mass ratio between the c

  98. G. Cimò, T. Beckert, T. P. Krichbaum, L. Fuhrmann

    Extreme Scattering Events (ESEs) are dramatic variations of the flux density at Gigahertz frequencies caused by ray path distortions within an isolated inhomogeneity (&#34;plasma lens&#34;) in the interstellar medium. These events are characterized by a deep flux density minimum in the light curve with, in some cases, surrounding maxima. The variability time

  99. F. Caputo, M. Marconi, I. Musella

    In a recent paper describing HST observations of Cepheids in the spiral galaxy NGC 4258, Newman et al. (2001) report that the revised calibrations and methods for the Key Project on the Extragalactic Distance Scale yield that the true distance modulus of this galaxy is 29.40+-0.09 mag, corresponding to a metric distance of 7.6+-0.3 Mpc. This Cepheid distance

  100. Yuka Y. Tajiri, Hideyuki Kamaya

    We discuss a correlation between star formation activity (SFA) and luminosity of star-forming galaxies at intermediate redshifts of $0.2\le z\le 0.6$ in both cluster and field environments. Equivalent width (EW) of [O{\sc ii}] is used for measurement of the SFA, and $R$-band absolute magnitude, $M_R$, for the luminosity. In less-luminous ($M_R \gsim -20.7$)