3,568 research outputs found

    Particle Conjugation and the 1/NC1/N_C Corrections to gAg_A

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    We impose the requirement that the isovector axial vector current for the soliton sector of the chiral quark model transforms correctly under particle conjugation. This forces us to choose an otherwise arbitrary ordering of collective space operators in such a way that the next--to--leading 1/NC1/N_C correction to gAg_A vanishes.Comment: 6 pages LaTeX, SU--4240--588, UNITU--THEP--23/199

    The Skyrme Model for Baryons

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    We review the Skyrme model approach which treats baryons as solitons of an effective meson theory. We start out with a historical introduction and a concise discussion of the original two flavor Skyrme model and its interpretation. Then we develop the theme, motivated by the large NCN_C approximation of QCD, that the {\it effective} Lagrangian of QCD is in fact one which contains just mesons of all spins. When this Lagrangian is (at least approximately) determined from the meson sector it should then yield a zero parameter description of the baryons. We next discuss the concept of chiral symmetry and the technology involved in handling the three flavor extension of the model at the collective level. This material is used to discuss properties of the light baryons based on three flavor meson Lagrangians containing just pseudoscalars and also pseudoscalars plus vectors. The improvements obtained by including vectors are exemplified in the treatment of the {\it proton spin puzzle}.Comment: Invited review for INSA-Book-2000 38 pages, 4 figures included via epsfi

    Three-dimensional nonlinear stability analysis of the sun-perturbed Earth-Moon equilateral points

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    Nonlinear analytic study of long period features of particle motion in Earth-Moon syste

    Analytical study of control devices for high amplitude combustion instability Quarterly report

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    Mathematical model and analysis of combustion processes in annular rocket engines for control of high amplitude combustion instabilit

    Global aspects of the scalar meson puzzle

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    A generalized linear sigma model for low energy QCD is employed to study the quark structure of eight low lying scalar isomultiplets as well as eight low lying pseudoscalar isomultiplets. The model, building on earlier work, assumes the possible mixing of quark anti-quark states with others made of two quarks and two antiquarks. No {\it a priori} assumption is made about the quark contents of the states, which emerge as predictions. An amusing and contrasting pattern for the quark structure is found; the lighter conventional pseudoscalars are, as expected, primarily of two quark type whereas the lighter scalars have very large four quark admixtures. The new feature of the present paper compared to earlier ones in this series involves the somewhat subtle and complicated effects of SU(3) flavor breaking. They do not alter the general pattern of two quark vs. four quark mixing obtained in the SU(3)symmetric case but, of course, give a more detailed picture

    Exploring the structure of a possible light scalar nonet

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    We first review the work of the Syracuse group, which uses an effective chiral Lagrangian approach, on meson-meson scattering. An illustration providing evidence for the existence of a strange scalar resonance of mass around 900 MeV is given. An attempt to fit this κ(900)\kappa (900) together with a similarly obtained σ(560)\sigma (560) and the well known a0(980)a_0(980) and f0(980)f_0(980) into a nonet pattern suggests that the underlying structure is closer to a dual quark-dual antiquark than to a quark-antiquark. A possible mechanism to explain a next higher-in mass scalar meson nonet is also discussed. This involves mixing between qqˉq{\bar q} and qqqˉqˉqq{\bar q} {\bar q} states.Comment: 8 pages, 4 figures, invited talk at workshop "Possible Existence of the Light Sigma Resonance and its Implications to Hadron Physics", Yukawa Institute for Theoretical Physics, Kyoto, Japan, June 200

    Light Scalar Mesons

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    We review how a certain effective chiral Lagrangian approach to pi pi scattering, pi K scattering and eta-prime decay to eta pi pi provides evidence for the existence of light scalars sigma(550) and kappa(900) as well as describing the f0(980) and the a0(980). An attempt to fit these into a nonet suggests that their structure is closer to a dual quark-dual antiquark than to a quark-antiquark. A possible mechanism to explain the next higher mass scalar nonet is also proposed.Comment: 10 pages, 4 figures, talk given at Hadron Physics: Effective Theories of Low Energy QCD, Coimbra, Portugal, Sept. 199

    Light Scalar Puzzle in QCD

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    An approach to understanding the light scalar meson phenomenology is briefly reviewed.Comment: Talk at XII Mexican Workshop on Particles and Fields, 5-14 Nov. 2009, Mazatlan, Mexic
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