Research archive

arXiv papers from November 2002

The most recent 100 records published that month. Open any paper for its original abstract, citation metadata, related research, and reading tools.

  1. Tapas Kumar Das, Aveek Sarkar

    A number of `modified' Newtonian potentials of various forms are available in the literature which accurately approximate some general relativistic effects important for studying accretion discs around a Schwarzschild black hole. Such potentials may be called `pseudo-Schwarzschild' potentials because they nicely mimic the space-time around a non-rotating/slo

  2. Ken-ichi Okumura, Leszek Roszkowski

    We present the results of our analysis on $b \to s \gamma$ in the minimal supersymmetric standard model with a general flavor mixing in the squark sector. We identify the next--to--leading order focusing effect, which considerably reduces the gluino contribution to $b \to s \gamma$ relative to the leading order calculation. We illustrate that $BR(B \to X_s \

  3. Jeffrey R. Weeks

    Cosmic microwave background data shows the observable universe to be nearly flat, but leaves open the question of whether it is simply or multiply connected. Several authors have investigated whether the topology of a multiply connect hyperbolic universe would be detectable when 0.9 < Omega < 1. However, the possibility of detecting a given topology varies d

  4. O. Cakir, C. Leroy, R. Mehdiyev, A. Belyaev

    We study single production of excited electrons at the CERN LHC through contact interactions of fermions. Subsequent decays of excited electrons to ordinary electrons and light fermions via gauge and contact interactions are examined. The mass range accessible with the ATLAS detector is obtained.

  5. Vadim Kostrykin, Robert Schrader

    In the present article magnetic Laplacians on a graph are analyzed. We provide a complete description of the set of all operators which can be obtained from a given self-adjoint Laplacian by perturbing it by magnetic fields. In particular, it is shown that generically this set is isomorphic to a torus. We also describe the conditions under which the operator

  6. E. Aprile, A. Curioni, K. L. Giboni, M. Kobayashi

    LXeGRIT is the first prototype of a novel concept of Compton telescope, based on the complete 3-dimensional reconstruction of the sequence of interactions of individual gamma rays in one position sensitive detector. This balloon-borne telescope consists of an unshielded time projection chamber with an active volume of 400 cm$^2 \times 7$ cm filled with high

  7. Theodore Liolios

    The September 11 terrorist attack against America has caused a lot of concern to the American public and the entire world, which is suspecting a new attack sooner or later. The most frightening scenario is the one involving the detonation of a nuclear device at the heart of a large metropolitan city. Unless the terrorists are in possession of a fully assembl

  8. Ulrich W. Heinz

    I present a theory-guided review of RHIC data, arguing that they provide strong evidence for formation of a thermalized quark-gluon plasma at RHIC. Strong radial flow reflects high thermal pressure in the reaction zone. Large elliptic flow proves that the pressure builds up quickly and the system thermalizes on a very short time scale of less than 1 fm/c. Th

  9. Alan Kostelecky, Ralf Lehnert, Malcolm Perry

    Spacetime-varying coupling constants can be associated with violations of local Lorentz invariance and CPT symmetry. An analytical supergravity cosmology with time-varying fine-structure constant provides an explicit example. Estimates are made for some experimental constraints.

  10. Jeffrey Satinover

    A simplified Bogoliubov transform reduces a fully-interacting many-fermion spin-1/2 system-plus-environment to a more tractable many-to-one variant. The transform additionally yields exact solutions for bosonic multi-particle interactions sans the approximation introduced by using discrete time steps to deal with quantum parallelism. The decohering effect of

  11. Carlos A. R. Herdeiro

    The SO(4) isometry of the extreme Reissner-Nordstrom black hole of N=1, D=5 supergravity can be partly broken, without breaking any supersymmetry, in two different ways. The ``right'' solution is a rotating black hole (BMPV); the ``left'' is interpreted as a black hole in a Godel universe. In ten dimensions, both spacetimes are described by deformations of t

  12. Buma L. Fridman, Daowei Ma

    The paper is devoted to the description of changes of the structure of the holomorphic automorphism group of a bounded domain in ${\Bbb C}^n$ under small perturbation of this domain in the Hausdorff metric. We consider a number of examples when an arbitrary small perturbation can lead to a domain with a larger group, present theorems concerning upper semicon

  13. Costas G. Strouthos, David N. Walters

    We present results from numerical simulations of the 2+1d SU(2)xSU(2) Nambu - Jona-Lasinio model with N_f=4 fermion flavours at zero and nonzero temperature T. At zero temperature, critical exponents are extracted from the scaling of the order parameter and fermion mass and are found to be consistent with next-to-leading order predictions of the 1/N_f expans

  14. Julian Pfeifle, Günter M. Ziegler

    We construct 2^{\Omega(n^{5/4})} combinatorial types of triangulated 3-spheres on n vertices. Since by a result of Goodman and Pollack (1986) there are no more than 2^{O(n log n)} combinatorial types of simplicial 4-polytopes, this proves that asymptotically, there are far more combinatorial types of triangulated 3-spheres than of simplicial 4-polytopes on n

  15. F. Jegerlehner, O. Tarasov

    An approach for an effective computer evaluation of one-loop multi-leg diagrams is proposed. It's main feature is the combined use of several systems - DIANA, FORM and MAPLE. As an application we consider the one-loop correction to Higgs production in e+ e- to nu anti-nu H, which is important for future e+ e- colliders. To improve the stability of numerical

  16. F. Jegerlehner, M. Yu. Kalmykov, O. Veretin

    We discuss progress in SM two-loop calculations of the pole position of the massive gauge-boson propagators.

  17. Joseph Lipman, Keiichi Watanabe

    There has arisen in recent years a substantial theory of "multiplier ideals'' in commutative rings. These are integrally closed ideals with properties that lend themselves to highly interesting applications. But how special are they among integrally closed ideals in general? We show that in a two-dimensional regular local ring with algebraically closed resid

  18. Evanthia Hatziminaoglou, Guy Mathez, Jose-Maria Solanes, Alberto Manrique

    We construct a physically motivated analytical model for the quasar luminosity function, based on the joint star formation and feeding of massive black holes suggested by the observed correlation between the black hole mass and the stellar mass of the hosting spheroids. The parallel growth of massive black holes and host galaxies is assumed to be triggered b

  19. Sarah J. Witherspoon

    We give a general construction of rings graded by the conjugacy classes of a finite group. Some examples of our construction are the Hochschild cohomology ring of a finite group algebra, the Grothendieck ring of the Drinfel'd double of a group, and the orbifold cohomology ring for a global quotient. We generalize the first two examples by deriving product fo

  20. Sergey N. Solodukhin

    Particles colliding at impact parameter much larger than the effective gravitational radius can not classically form a black hole and just scatter off the radial potential barrier separating the particles. We show that the process of the black hole production can still go quantum-mechanically via familiar mechanism of the under-barrier tunneling. The mechani

  21. H. Salamati, P. Kameli

    The temperature dependence of ac susceptibility of YBCO thin film was measured as a function of frequency and ac field amplitude in a field perpendicular to the film plane. We show that all measured ac susceptibility curves can be caled into a single curve using the peak temperature (Tp) of its imaginary part as the scaling parameter. The frequency effect on

  22. Masato Inoue, Hyeyoung Park, Masato Okada

    The permutation symmetry of the hidden units in multilayer perceptrons causes the saddle structure and plateaus of the learning dynamics in gradient learning methods. The correlation of the weight vectors of hidden units in a teacher network is thought to affect this saddle structure, resulting in a prolonged learning time, but this mechanism is still unclea

  23. J. O. Indekeu, K. Sznajd-Weron

    A time- and space-discrete model for the growth of a rapidly saturating local biological population $N(x,t)$ is derived from a hierarchical random deposition process previously studied in statistical physics. Two biologically relevant parameters, the probabilities of birth, $B$, and of death, $D$, determine the carrying capacity $K$. Due to the randomness th

  24. Nobutaka Abe, Motoi Endo

    We study the deflected anomaly-mediated supersymmetry breaking (AMSB) scenario in the light of the recent result of the muon g-2 from Brookhaven E821 experiment. The E821 result suggests the deviation from the SM prediction, though there remain unsettled uncertainties. We find that the supersymmetric contribution to the muon g-2 can be \mathcal{O}(10^{-9}),

  25. Takashi Nakatsukasa, Kazuhiro Yabana

    Giant resonances in the continuum for deformed nuclei are studied with the time-dependent Hartree-Fock (TDHF) theory in real time and real space. The continuum effect is effectively taken into account by introducing a complex Absorbing Boundary Condition (ABC).

  26. Manabu Ueda, Kazuhiro Yabana, Takashi Nakatsukasa

    Absorbing boundary condition approach to nuclear breakup reactions is investigated. A key ingredient of the method is an absorbing potential outside the physical area, which simulates the outgoing boundary condition for scattered waves. After discretizing the radial variables, the problem results in a linear algebraic equation with a sparse coefficient matri

  27. Ambar Jain, V. Ravishankar

    A general scheme is proposed here to describe the production of semi soft and soft quarks and gluons that form the bulk of the plasma in ultra relativistic heavy ion collisions. We show how to obtain rates as a function of time in a self consistent manner, without any ad-hoc assumption. All the required features - the dynamical nature of QCD vacuum, the non-

  28. M. Ericson, S. Kumano

    We investigate the nuclear effects on the transverse and longitudinal responses in the deep inelastic region due to the nuclear binding and nucleon Fermi motion. We display the role of the transverse-longitudinal admixture due to the transverse nucleon momentum. The mixing effect is appreciable at small Q^2 values, and gradually disappears at large Q^2 value

  29. Jay Strader, Jean P. Brodie, Duncan A. Forbes, Michael A. Beasley

    We present low resolution, integrated Keck spectra of the five globular clusters (GCs) of the Fornax dwarf spheroidal galaxy. We find a tentative age spread among the clusters, with the GC H5 younger by 2-3 Gyr than the others. The clusters generally appear to be very metal-poor ([Fe/H] ~ -1.8), with the cluster H4 slightly more metal-rich at [Fe/H] = -1.5.

  30. Kasper Astrup Eriksen, Ingve Simonsen, Sergei Maslov, Kim Sneppen

    We study the spectral properties of a diffusion process taking place on the Internet network focusing on the slowest decaying modes. These modes allow us to identify an underlying modular structure of the Internet roughly corresponding to individual countries. For instance in the slowest decaying mode the diffusion current flows from Russia towards US milita

  31. Lisa R. Hales

    The quantum Fourier transform (QFT) has emerged as the primary tool in quantum algorithms which achieve exponential advantage over classical computation and lies at the heart of the solution to the abelian hidden subgroup problem, of which Shor's celebrated factoring and discrete log algorithms are a special case. We begin by addressing various computational

  32. Giovanni Amelino-Camelia

    In the quantum-gravity literature there has been interest in the possibility that quantum properties of spacetime might affect the energy/momentum dispersion relation. The most used test theory for data analysis is based on a modification of the laws of propagation proposed in astro-ph/9712103 [Nature 393,763], and the present best limit on the quantum-gravi

  33. Z. C. Tu, Z. C. Ou-Yang

    A Comment on the Letter by Granger et.al., Phys. Rev. Lett. 89, 135506 (2002).

  34. Z. C. Tu

    In this paper, spiral symmetry in cylindrical coordinate and general Bloch&#39;s theorem induced from it are discussed. This general Bloch&#39;s theorem is useful for considering the properties related to single-walled carbon nanotubes.

  35. J. M. Hu, Z. D. Chen, S. Q. Shen

    Two single-molecule magnets are coupled antiferromagnetically to form a supramolecule dimer. We study the coupling effect and tunneling process by means of the numerical exact diagonalization method, and apply them to the recently synthesized supramoleculer dimer [Mn4]2 The model parameters are calculated for the dimer based on the tunneling process. The abs

  36. Lars Bildsten

    Recent theoretical work has made it plausible for neutron stars (NSs) to lose angular momentum via gravitational radiation on long timescales (around Myrs) while actively accreting. The gravitational waves (GWs) can either be emitted via the excitation of r-modes or from a deformed crust. GW emission can thus intervene to slow-down or halt the otherwise rele

  37. Mayeul Arminjon

    It is attempted to obtain the masses of the celestial bodies, the initial conditions of their motion, and the constant of gravitation, by a global parameter optimization. First, a numerical solution of the N-bodies problem for mass points is described and its high accuracy is verified. The osculating elements are also accurately computed. This solution is im

  38. Laurent Freidel, David Louapre

    We study the action of diffeomorphisms on spin foam models. We prove that in 3 dimensions, there is a residual action of the diffeomorphisms that explains the naive divergences of state sum models. We present the gauge fixing of this symmetry and show that it explains the original renormalization of Ponzano-Regge model. We discuss the implication this action

  39. B. M. Rodriguez, H. Moya-Cessa

    We analyze the possibility of measuring the state of a movable mirror by using its interaction with a quantum field. We show that measuring the field quadratures allows to reconstruct the characteristic function corresponding to the mirror state.

  40. G. Unel

    The Na59 collaboration aims to measure the linear polarization of its photon beam in the 20-170 GeV range, using an aligned thin crystal. The tracks of $e^-/e^+$ pairs created in two different crystal targets, germanium and diamond, are reconstructed to obtain the photon spectrum. Using the polarization dependence of the pair production cross section in an a

  41. Hans Schoutens

    Let R be a locally finitely generated algebra over a discrete valuation ring V of mixed characteristic. For any of the homological properties, the Direct Summand Theorem, the Monomial Theorem, the Improved New Intersection Theorem, the Vanishing of Maps of Tors and the Hochster-Roberts Theorem, we show that it holds for R and possibly some other data defined

  42. M. Carena, J. Ellis, S. Mrenna, A. Pilaftsis

    We investigate the hadron collider phenomenology of the Minimal Supersymmetric Standard Model (MSSM) with explicit CP violation for Higgs bosons that can be observed in Standard Model search channels: W/ZH(->b-bbar) at the Tevatron, and gg->H(->gamma-gamma), t-tbar-H(->b-bbar) and WW->H(->tau+tau-) at the LHC. Our numerical analysis is based on a benchmark s

  43. Oleg Lunin, Samir D. Mathur, Ashish Saxena

    In the AdS/CFT correspondence a chiral primary is described by a supergravity solution with mass equaling angular momentum. For AdS_3 X S^3 we are led to consider three special families of metrics with this property: metrics with conical defects, Aichelburg-Sexl type metrics generated by rotating particles, and metrics generated by giant gravitons. We find t

  44. Sujay K. Ashok, Richard Corrado, Nick Halmagyi, Kristian D. Kennaway

    We apply the proposal of Dijkgraaf and Vafa to analyze N=1 gauge theory with SO(N) and Sp(N) gauge groups with arbitrary tree-level superpotentials using matrix model techniques. We derive the planar and leading non-planar contributions to the large M SO(M) and Sp(M) matrix model free energy by applying the technology of higher-genus loop equations and by st

  45. D. P. Arovas, F. Guinea, C. Herrero, P. San Jose

    Disordered granular systems, at temperatures where charging effects are important, are studied, by means of an effective medium approximation. The intragrain charging energy leads to insulating behavior at low temperatures, with a well defined Coulomb gap. Non equilibrium effects can give rise to a zero temperature transition between a metallic, gapless phas

  46. D. Mattingly, T. Jacobson, S. Liberati

    A general characterization of lower and upper threshold configurations for two particle reactions is determined under the assumptions that the single particle dispersion relations E(p) are rotationally invariant and monotonic in p, and that energy and momentum are conserved and additive for multiple particles. It is found that at a threshold the final partic

  47. Harvey S. Reall

    It has recently been shown that the uniqueness theorem for stationary black holes cannot be extended to five dimensions. However, uniqueness is an important assumption of the string theory black hole entropy calculations. This paper partially justifies this assumption by proving two uniqueness theorems for supersymmetric black holes in five dimensions. Some

  48. Stephen Godfrey

    The existence of non-q\bar{q} hadrons such as glueballs and hybrids is one of the most important qualitative questions in QCD. The COMPASS experiment offers the possibility to unambiguously identify such states and map out the glueball and hybrid spectrum. In this review I discuss the expected properties of glueballs and hybrids and how they might be produce

  49. G. Lugones, J. E. Horvath

    Strange quark matter in a color flavor locked (CFL) state can be the true ground state of hadronic matter for a much wider range of the parameters of the model (the gap of the QCD Cooper pairs $\Delta$, the strange quark mass $m_s$ and the Bag Constant $B$) than the state without any pairing. We review the equation of state (EOS) of CFL strange matter and st

  50. G. Flores-Hidalgo, A. P. C. Malbouisson

    We consider a particle represented by an anharmonic oscillator, coupled to an environment (a field) modeled by an ensemble of anharmonic oscillators, the whole system being confined in a cavity of diameter $L$. Up to the first perturbative order in the quartic interaction (interaction parameter $\lambda$), we use the formalism of {\it dressed} states introdu

  51. Feng Liu, Florentin Smarandache

    The paper presents a fresh new comprehensive ideology on Neutrosophic Logic based on contradiction study. It does a survey on Chinese philosophy. The paper aims to solve the chaos of logic and exhibit the potential power of neutrosophy: a new branch of scientific philosophy.

  52. Swapneel Mahajan

    A theorem of Kontsevich relates the homology of certain infinite dimensional Lie algebras to graph homology. We formulate this theorem using the language of reversible operads and mated species. All ideas are explained using a pictorial calculus of cuttings and matings. The Lie algebras are constructed as Hamiltonian functions on a symplectic operad manifold

  53. Ko Okumura, Yoshitaka Tanimura

    We develop a Feynman rule for energy-level diagrams emphasizing their connections to the double-sided Feynman diagrams and physical processes in the Liouville space. Thereby we completely identify such diagrams and processes contributing to the two-dimensional response function in the Brownian oscillator model. We classify such diagrams or processes in quart

  54. G. Giachetta, L. Mangiarotti, G. Sardanashvily

    Given a first order dynamical system possessing a commutative algebra of dynamical symmetries, we show that, under certain conditions, there exists a Poisson structure on an open neighbourhood of its regular (not necessarily compact) invariant manifold which makes this dynamical system into a partially integrable Hamiltonian system. This Poisson structure is

  55. T. Aspelmeier, M. A. Moore

    The sample-to-sample fluctuations of the free energy in finite-dimensional Ising spin glasses are calculated, using the replica method, from higher order terms in the replica number $n$. It is shown that the Parisi symmetry breaking scheme does not give the correct answers for these higher order terms. A modified symmetry breaking scheme with the same stabil

  56. A. Omont, A. Beelen, F. Bertoldi, P. Cox

    We report 250GHz (1.2mm) observations of redshift 1.8 < z < 2.8 optically luminous (M_B < -27.0), radio quiet quasars using the Max-Planck Millimeter Bolometer (MAMBO) array at the IRAM 30-metre telescope. Nine quasars were detected and for 26 quasars 3-sigma flux density limits in the range 1.8 to 4mJy were obtained. Adopting a typical dust temperature of 4

  57. C. Garcia-Recio, J. Nieves, E. Ruiz Arriola, M. Vicente Vacas

    Meson-Baryon Interactions can be successfully described using both Chiral Symmetry and Unitarity. The $s-$wave meson-baryon scattering amplitude is analyzed in a Bethe-Salpeter coupled channel formalism incorporating Chiral Symmetry in the potential. Two body coupled channel unitarity is exactly preserved. The needed two particle irreducible matrix amplitude

  58. G. Papadopoulos, J. G. Russo, A. A. Tseytlin

    We investigate a string model defined by a special plane-wave metric ds^2 = 2dudv - l(u) x^2 du^2 + dx^2 with l(u) = k/u^2 and k=const > 0. This metric is a Penrose limit of some cosmological, Dp-brane and fundamental string backgrounds. Remarkably, in Rosen coordinates the metric has a ``null cosmology'' interpretation with flat spatial sections and scale f

  59. A. J. Fisher

    It is shown that a generalization of the fluctuation-dissipation theorem places an upper bound on the figure of merit for any quantum gate designed to entangle spatially-separated qubits. The bound depends solely on the spectral properties of the environment. The bound applies even to systems performing a quantum computation within a decoherence-free subspac

  60. K. Braun-Munzinger, J. A. Dunningham, K. Burnett

    In this paper we examine the excitations observable in atoms confined in an optical lattice around the superfluid-insulator transition. We use increases in the number variance of atoms, subsequent to tilting the lattice as the primary diagnostic of excitations in the lattice. We show that this locally determined quantity should be a robust indicator of coher

  61. Karim Noui, Philippe Roche

    We study the quantum deformation of the Barrett-Crane Lorentzian spin foam model which is conjectured to be the discretization of Lorentzian Plebanski model with positive cosmological constant and includes therefore as a particular sector quantum gravity in de-Sitter space. This spin foam model is constructed using harmonic analysis on the quantum Lorentz gr

  62. G Zwicknagl, P. Fulde

    We develop a theory for the electronic excitations in UPt$_3$ which is based on the localization of two of the $5f$ electrons. The remaining $f$ electron is delocalized and acquires a large effective mass by inducing intra-atomic excitations of the localized ones. The measured deHaas-vanAlphen frequencies of the heavy quasiparticles are explained as well as

  63. Ruth Durrer, Andrea Gabrielli, Michael Joyce, Francesco Sylos Labini

    Threshold biasing of a Gaussian random field gives a linear amplification of the reduced two point correlation function at large distances. We show that for standard cosmological models this does not translate into a linear amplification of the power spectrum (PS) at small k. For standard CDM type models this means that the``turn-over'' at small k of the ori

  64. Zhi-zhong Xing

    We show that the $3\times 3$ lepton flavor mixing matrix $V$ can be expanded in powers of a Wolfenstein-like parameter $\Lambda \equiv |V_{\mu 3}| \sim 1/\sqrt{2}$, which measures the strength of flavor conversion in atmospheric neutrino oscillations. The term of ${\cal O}(\Lambda^2)$ is associated with the large mixing angle in solar neutrino oscillations.

  65. Herbert I. M. Lichtenegger, Lorenzo Iorio, Bahram Mashhoon

    The general relativistic gravitomagnetic clock effect involves a coupling between the orbital motion of a test particle and the rotation of the central mass and results in a difference in the proper periods of two counter-revolving satellites. It is shown that at O(c^-2) this effect has a simple analogue in the electromagnetic case. Moreover, in view of a po

  66. Pantelis S. Apostolopoulos, Michael Tsamparlis

    A generalisation of a known theorem concerning the computation of the conformal algebra in 1+(n-1) decomposable spaces is presented. It is shown that the general form of Conformal Vector Fields (CVF) is the sum of a gradient CVF and a Killing or Homothetic (n-1)-vector. A simple criterion is established which enables one to check if a 1+(n-1) decomposable sp

  67. Mauro Caravati, Alberto Devoto, Wayne W. Repko

    We examine the implications of including corrections associated with the noncommutative extension of quantum electrodynamics - NCQED - to the decays of the ortho and para positronium (\Trip and \Sing) ground states. In NCQED, the well known charge conjugation argument restricting \Trip decays to an odd number of photons and \Sing decays to an even number of

  68. C. -J. D. Lin, G. Martinelli, E. Pallante, C. T. Sachrajda

    We perform a calculation in one-loop chiral perturbation theory of the two-pion matrix elements and correlation functions of an I=0 scalar operator, in finite and infinite volumes for both full and quenched QCD. We show that major difficulties arise in the quenched theory due to the lack of unitarity. Similar problems are expected for quenched lattice calcul

  69. S. M. Bilenky, C. Giunti, J. A. Grifols, E. Masso

    Compelling evidences in favor of neutrino masses and mixing obtained in the last years in Super-Kamiokande, SNO, KamLAND and other neutrino experiments made the physics of massive and mixed neutrinos a frontier field of research in particle physics and astrophysics. There are many open problems in this new field. In this review we consider the problem of the

  70. Marco Battaglia

    The problems of the origin of mass and of electro-weak symmetry breaking are central to the programme of research in particle physics, at present and in the coming decades. This paper reviews the potential of high energy, high luminosity e+e- linear colliders in exploring the Higgs sector,to extend and complement the data which will become available from had

  71. A. García-Parrado, J. M. M. Senovilla

    We define a new type of transformation for Lorentzian manifolds characterized by mapping every causal future-directed vector onto a causal future-directed vector. The set of all such transformations, which we call causal symmetries, has the structure of a submonoid. Some of their properties are investigated and we give necessary conditions for a vector field

  72. Hendryk Pfeiffer

    Let G be a compact Lie group. Using suitable normalization conventions, we show that the evaluation of GxG-symmetric spin networks is non-negative whenever the edges are labeled by representations of the form V\otimes V^* where V is a representation of G, and the intertwiners are generalizations of the Barrett--Crane intertwiner. This includes in particular

  73. M. Kenzelmann, G. Xu, I. A. Zaliznyak, C. Broholm

    Inelastic neutron scattering was used to probe edge states in a quantum spin liquid. The experiment was performed on finite length antiferromagnetic spin-1 chains in Y_2BaNi_{1-x}Mg_xO_5. At finite fields, there is a Zeeman resonance below the Haldane gap. The wave vector dependence of its intensity provides direct evidence for staggered magnetization at cha

  74. Helmuth K. Urbantke

    A proof more elementary than the original one is given for Moretti's theorem that the usual polar decomposition of real matrices when applied to an orthochronous proper Lorentz matrix yields just its standard rotation-boost decomposition. (The complex SL(2,C) analog is well-known.)

  75. F. Bonechi, N. Ciccoli, M. Tarlini

    We define even dimensional quantum spheres Sigma_q^2n that generalize to higher dimension the standard quantum two-sphere of Podle's and the four-sphere Sigma_q^4 obtained in the quantization of the Hopf bundle. The construction relies on an iterated Poisson double suspension of the standard Podle's two-sphere. The Poisson spheres that we get have the same s

  76. N. V. Gribova, V. N. Ryzhov, T. I. Schelkacheva, E. E. Tareyeva

    The role of reflection symmetry breaking for the character of the appearance of replica symmetric spin glass state is investigated. We establish the following symmetry rule for classical systems with one order parameter in the replica symmetric mean field approximation. If in the pure system the transition to the ordered phase is of the second order, then in

  77. Antoni Wojcik

    The proposed eavesdropping scheme reveals that the quantum communication protocol recently presented by Bostrom and Felbinger [Phys. Rev. Lett. 89, 187902 (2002)] is not secure as far as quantum channel losses are taken into account.

  78. F. Kleefeld

    A causal, non-Hermitian, renormalizable, local, unitary and Lorentz convariant formulation of Quantum Theory (QT) (= Quantum Mechanics (QM) and Quantum Field Theory (QFT)) is developed which is free of formalistic problems we face in the commonly used Hermitian formulation of QT. Side effects of the new formulation of QT are the derivation of a consistent (a

  79. Georges Chevalier

    By using a lattice characterization of continuous projections defined on a topological vector space E arising from a dual pair, we determine the automorphism group of their orthomodular poset Proj(E) by means of automorphisms and anti-automorphisms of the lattice L of all closed subspaces of E. A connection between the automorphism group of the ring of all c

  80. Patrick A. Lee, Naoto Nagaosa

    In the slave boson mean field treatment of the t-J model, the ground state for small doping is a d-wave superconductor. A conventional superconductor has collective modes associated with the amplitude and phase of the pairing order parameter. Here, the hopping matrix element $\chi_{ij}$ is also a mean field order parameter. We therefore expect that new colle

  81. A. Marconi, D. J. Axon, A. Capetti, W. Maciejewski

    We present HST/STIS spectra of the Sbc spiral galaxy NGC 4041 which were used to map the velocity field of the gas in its nuclear region. We detect the presence of a compact (r~0.4" ~40 pc), high surface brightness, rotating nuclear disk co-spatial with a nuclear star cluster. The disk is characterized by a rotation curve with a peak to peak amplitude of ~40

  82. J. Harnad, J. C. Hurtubise

    For the rational, elliptic and trigonometric r-matrices, we exhibit the links between three "levels" of Poisson spaces: (a) Some finite-dimensional spaces of matrix-valued holomorphic functions on the complex line; (b) Spaces of spectral curves and sheaves supported on them; (c) Symmetric products of a surface. We have, at each level, a linear space of compa

  83. S. Fournais, M. Hoffmann-Ostenhof, T. Hoffmann-Ostenhof, T. Østergaard Sørensen

    We prove that the electronic densities of atomic and molecular eigenfunctions are real analytic in ${\mathbb R}^3$ away from the nuclei.

  84. Cemsinan Deliduman

    The boundary states for AdS_2 D-branes in Lorentzian AdS_3 space-time are presented. AdS_2 D-branes are algebraically defined by twisted Dirichlet boundary conditions and are located on twisted conjugacy classes of SL(2,R). Using free field representation of symmetry currents in the SL(2,R) WZNW model, the twisted Dirichlet gluing conditions among currents a

  85. R. Prix, J. Novak, G. L. Comer

    We describe recent progress in the numerical study of the structure of rapidly rotating superfluid neutron star models in full general relativity. The superfluid neutron star is described by a model of two interpenetrating and interacting fluids, one representing the superfluid neutrons and the second consisting of the remaining charged particles (protons, e

  86. Anatoly N. Kochubei

    We study some classes of equations with Carlitz derivatives for $F_q$-linear functions, which are the natural function field counterparts of linear ordinary differential equations with a regular singularity. In particular, an analog of the equation for the power function, the Fuchs and Euler type equations, and Thakur's hypergeometric equation are considered

  87. N. G. Marchuk

    We improve the concept of our previous paper "Dirac type tensor equations with nonabelian gauge symmetries on pseudo-Riemannian space" and present a new compact formula for the tensor $B_\mu$.

  88. S. Colafrancesco, P. Marchegiani, E. Palladino

    In this paper we provide a general derivation of the non-thermal (as well as of the thermal) SZ effect in galaxy clusters which is exact in the Thomson limit to any approximation order in the optical depth. Such a general derivation is obtained using the full relativistic formalism and overcoming the limitations of the Kompaneets and of the single scattering

  89. N. G. Marchuk

    We discuss a connection between the Dirac equation for an electron and the Dirac type tensor equation with ${\rm U}(1)$ gauge symmetry.

  90. N. G. Marchuk

    The goal of this work is to extend Dirac-type tensor equations to a curved space. We take four 1-forms (a tetrad) as a unique structure, which determines a geometry of space-time.

  91. Ch. Renner, J. Peinke, R. Friedrich

    We adress the problem of interactions between the longitudinal velocity increment and the energy dissipation rate in fully developed turbulence. The coupling between these two quantities is experimentally investigated by the theory of stochastic Markovian processes. The so-called Markov analysis allows for a precise characterization of the joint statistical

  92. N. G. Marchuk

    In the model every quark or lepton is identified with a quartet of four "more elementary" particles. One particle in a quartet is a massive spin-0 boson and other three particles are massless spin-1/2 fermions.

  93. A. Boccaletti, J. C. Augereau, F. Marchis, J. Hanh

    We present the first ground-based near-infrared image of the circumstellar disk around the post-Herbig Ae/Be star HD141569A initially detected with the HST. Observations were carried out in the near-IR (2.2 $\mu$m) at the Palomar 200-inch telescope using the adaptive optics system PALAO. The main large scale asymmetric features of the disk are detected on ou

  94. Gad Eilam

    Motivated by the well known impact of rare decays of hadrons and leptons on the evolution of the Standard Model and on limits for new physics, as well as by the proposal for Giga-Z option at TESLA, we investigate the rare decay Z -> b s-bar in various extensions of the Standard Model.

  95. RP Campion, KW Edmonds, LX Zhao, KY Wang

    We demonstrate that GaMnAs films grown with As2 have excellent structural, electrical and magnetic properties, comparable or better than similar films grown with As4. Using As2, a Curie temperature of 112K has been achieved, which is slightly higher than the best reported to date. More significantly, films showing metallic conduction have been obtained over

  96. I. Rotter

    Exceptional points and double poles of the S matrix are both characterized by the coalescence of a pair of eigenvalues. In the first case, the coalescence causes a defect of the Hilbert space. In the second case, this is not so as shown in prevoius papers. Mathematically, the reason for this difference is the bi-orthogonality of the eigenfunctions of a non-H

  97. D. Segransan, P. Kervella, T. Forveille, D. Queloz

    e present 4 very low mass stars radii measured with the VLTI using the 2.2 microns VINCI test instrument. The observations were carried out during the commissioning of the 104-meter-baseline with two 8-meter-telescopes. We measure angular diameters of 0.7-1.5 mas with accuracies of 0.04-0.11 mas, and for spectral type ranging from M0V to M5.5V. We determine

  98. Johannes Kellendonk

    The cohomology of a tiling or a point pattern has originally been defined via the construction of the hull or the groupoid associated with the tiling or the pattern. Here we present a construction which is more direct and therefore easier accessible. It is based on generalizing the notion of equivariance from lattices to point patterns of finite local comple

  99. Y. Suhov, T. Voice

    This paper has been withdrawn by the authors, due to the discovery of paper 0201028 which predates it and contains most of it's results.

  100. Tamas Unger, Janos Kertesz

    In this paper we review the simulation method of the non-smooth contact dynamics. This technique was designed to solve the unilateral and frictional contact problem for a large number of rigid bodies and has proved to be especially valuable in research of dense granular materials during the last decade. We present here the basic principles compared to other