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How to understand the lightest scalars

By Nils A. Tornqvist

Abstract

Based on previous papers I discuss how I understand the lightest scalars using a general coupled channel model. This model includes all light two-pseudoscalar thresholds, constraints from Adler zeroes, flavour symmetric couplings, unitarity and physically acceptable analyticity. One finds that with a large coupling there can appear two physical resonance poles on the second sheet although only one bare quark-antiquark state is put in. The f0(980) and f0(1370) resonance poles are thus in this model two manifestations of the same strange-antistrange quark state. On the other hand, the isoscalar state containing u and d quarks becomes (when unitarized and strongly distorted by hadronic mass shifts) a very broad resonance, with its pole at 470-i250 MeV. This is the sigma meson required by models for spontaneous breaking of chiral symmetry.Comment: Invited talk at the Conference: "Possible Existence of the Light Sigma Resonance and its Implications to Hadron Physics", Yukawa Institute for Theoretical Physics, Kyoto, Japan, June 11-14 2000. 6 pages. To appear in the conference proceeding

Topics: High Energy Physics - Phenomenology
Year: 2000
OAI identifier: oai:arXiv.org:hep-ph/0008136

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