Isospin Symmetry Breaking and the $ρ-ω$-System
Simple quark models for the low lying vector mesons suggest a mixing between the u- and d-flavors and a violation of the isospin symmetry for the $ρ-ω$- system much stronger than observed. It is shown that the chiral dynamics, especially the QCD anomaly, is responsible for a restoration of the isospin symmetry in the $ρ-ω$-system.
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