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Scalar mesons in QCD and tests of the gluon content of the sigma

Stephan Narison
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Abstract

We summarize the different features of the scalar mesons from QCD spectral sum rule analyses of the two- and three-point functions. The results do not favour the u-bar u + d-bar d interpretation of the broad and low mass sigma (0.6), and the u-bar s resonance nature of the eventually observed kappa(0.9) meson. We also discuss some OZI-violating and classic semileptonic and radiative decay processes which can reveal in a model-independent way the eventual gluon component sigma_B of the sigma. In a meson-gluonium mixing scenario, one also expects an observation of the K K-bar final states from the sigma_B which may compete (if phase space allowed) with the one from a low mass s-bar s state assumed in the literature to be the SU(3) partner of the $σ(0.6)$ if this latter is a u-bar u + d-bar d state

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Stephan Narison. 2002-08-12. Scalar mesons in QCD and tests of the gluon content of the sigma. https://doi.org/10.1016/s0920-5632(03)01828-0

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