1,588 research outputs found

    Antiproton-proton partial-wave analysis below 925 MeV/c

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    A partial-wave analysis of all antiproton-proton scattering data below 925 MeV/c antiproton laboratory momentum is presented. The method used is adapted from the Nijmegen phase-shift analyses of pp and np scattering data. The Nijmegen 1993 antiproton-proton database, consisting of 3646 antiproton-proton scattering data, is presented and discussed. The best fit to this database results in chi^2_min/Ndata = 1.043. The pseudovector coupling constant of the charged pion to nucleons is determined to be (f_c)^2 = 0.0732(11) at the pion pole, where the error is statistical.Comment: Report THEF-NYM 93.02 42 pages REVTeX, 7 separate postscript figures appended. Accepted for publication in Phys. Rev.

    Partial-Wave Analyses of all Proton-Proton and Neutron-Proton Data Below 500 MeV

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    In 1993 the Nijmegen group published the results of energy-dependent partial-wave analyses (PWAs) of the nucleon-nucleon (NN) scattering data for laboratory kinetic energies below Tlab=350 MeV (PWA93). In this talk some general aspects, but also the newest developments on the Nijmegen NN PWAs are reported. We have almost finished a new energy-dependent PWA and will discuss some typical aspects of this new PWA; where it differs from PWA93, but also what future developments might be, or should be.Comment: Presentation at the 19th European Conference on Few-Body Problems in Physics, Groningen, The Netherlands, 23-27 August 2004. 4 pages REVTeX4, no figure

    The Status of the Pion-Nucleon Coupling Constant

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    A review is given of the various determinations of the different piNN coupling constants in analyses of the low-energy pp, np, pbarp, and pi-p scattering data. The most accurate determinations are in the energy-dependent partial-wave analyses of the NN data. The recommended value is f^2 = 0.075 . A recent determination of f^2 by the Uppsala group from backward np cross sections is shown to be model dependent and inaccurate, and therefore completely uninteresting. We also argue that an accurate determination of f^2 using pp forward dispersion relations is not a realistic option.Comment: 19 pages, latex2e with a4wide.sty, more information is available at http://NN-OnLine.sci.kun.nl . Invited talk at FBXV, Groningen, The Netherlands, July 22-26, 1997. Invited talk at MENU97, Vancouver, B.C., Canada, July 28 - August 1, 199

    Deuteron Dipole Polarizabilities and Sum Rules

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    The scalar, vector, and tensor components of the (generalized) deuteron electric polarizability are calculated, as well as their logarithmic modifications. Several of these quantities arise in the treatment of the nuclear corrections to the deuterium Lamb shift and the deuterium hyperfine structure. A variety of second-generation potential models are used and a (subjective) error is assigned to the calculations. The zero-range approximation is used to analyze a subset of the results, and a simple relativistic version of this approximation is developed.Comment: 14 pages, LaTex - submitted to Physical Review

    The nucleon-sigma coupling constant in QCD Sum Rules

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    The external-field QCD Sum Rules method is used to evaluate the coupling constant of the light isoscalar-scalar meson (``σ\sigma'' or \epsilon) to the nucleon. The contributions that come from the excited nucleon states and the response of the continuum threshold to the external field are calculated. The obtained value of the coupling constant is compatible with the large value required in one-boson exchange potential models of the two-nucleon interaction.Comment: 11 pages, 4 figure

    Partial Wave Analyses of the pp data alone and of the np data alone

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    We present results of the Nijmegen partial-wave analyses of all NN scattering data below Tlab = 500 MeV. We have been able to extract for the first time the important np phase shifts for both I = 0 and I = 1 from the np scattering data alone. This allows us to study the charge independence breaking between the pp and np I = 1 phases. In our analyses we obtain for the pp data chi^2_{min}/Ndf = 1.13 and for the np data chi^2_{min}/Ndf = 1.12.Comment: Report THEF-NYM 94.04, 4 pages LaTeX, one PostScript figure appended. Contribution to the 14th Few-Body Conference, May 26 - 31, Williamsburg, V

    Cognitive animacy and its relation to linguistic animacy: Evidence from Japanese and Persian

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    Animacy, commonly defined as the distinction between living and non-living entities, is a useful notion in cognitive science and linguistics employed to describe and predict variation in psychological and linguistic behaviour. In the (psycho)linguistics literature we find linguistic animacy dichotomies which are (implicitly) assumed to correspond to biological dichotomies. We argue this is problematic, as it leaves us without a cognitively grounded, universal description for non-prototypical cases. We show that ‘animacy’ in language can be better understood as universally emerging from a gradual, cognitive property by collecting animacy ratings for a great range of nouns from Japanese and Persian. We used these cognitive ratings in turn to predict linguistic variation in these languages traditionally explained through dichotomous distinctions. We show that whilst (speakers of) languages may subtly differ in their conceptualisation of animacy, universality may be found in the process of mapping conceptual animacy to linguistic variation

    The J/ψDDJ/\psi D D Vertex in QCD Sum Rules

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    The J/ψDDJ/\psi D D form factor is evaluated in a QCD sum rule calculation for both DD and J/ψJ/\psi off-shell mesons. We study the double Borel sum rule for the three point function of two pseudoscalar and one vector meson current. We find that the momentum dependence of the form factors is different if the DD or the J/ψJ/\psi meson is off-shell, but they lead to the same coupling constant in the J/ψDDJ/\psi D D vertex.Comment: 11 pages, Latex, 4 eps figure

    Hamiltonian LGT in the complete Fourier analysis basis

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    The main problem in the Hamiltonian formulation of Lattice Gauge Theories is the determination of an appropriate basis avoiding the over-completeness arising from Mandelstam relations. We short-cut this problem using Harmonic analysis on Lie-Groups and intertwining operators formalism to explicitly construct a basis of the Hilbert space. Our analysis is based only on properties of the tensor category of Lie-Group representations. The Hamiltonian of such theories is calculated yielding a sparse matrix whose spectrum and eigenstates could be exactly derived as functions of the coupling g2g^2Comment: LATTICE99 (theoretical developments), 3 page
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