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arXiv · 1109.2392

The nature of the lightest scalar meson, its Nc behaviour and semi-local duality

J. R. Peláez·M. R. Pennington·J. Ruiz de Elvira·D. J. Wilson
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Abstract

One-loop unitarized Chiral Perturbation Theory (UChPT) calculations, suggest a different Nc behaviour for the sigma or f0(600) and rho(770) mesons: while the rho meson becomes narrower with Nc, as expected for a qqbar meson, the f0(600) contribution to the total cross section below 1 GeV becomes less and less important. Here we review our recent work where we have shown, by means of finite energy sum rules, that a different Nc behaviour for these resonances may lead to a conflict with semi-local duality for large Nc, since local duality requires a cancellation between the f0(600) and rho(770) amplitudes. However, UChPT calculations also suggest a subdominant qqbar component for the f0(600) with a mass above 1 GeV and this can restore semi-local duality, as we show.

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J. R. Peláez, M. R. Pennington, J. Ruiz de Elvira, D. J. Wilson. 2011-09-12. The nature of the lightest scalar meson, its Nc behaviour and semi-local duality. https://arxiv.org/abs/1109.2392

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