6533b7d3fe1ef96bd125ff13

RESEARCH PRODUCT

Unitarity constraints on resonance mixing and the Okubo-Zweig-Iizuka rule

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We discuss unitarity constraints on the (complex) mixing angle (δ) between resonances. In particular, when the mixing is small, as when it is forbidden by the Okubo-Zweig-Iizuka (OZI) rule, or some other mechanism, one can derive useful bounds on δ or determine Arg (δ) from the data of allowed decays of the resonances. In the case of f′−f mixing the unitarity bound |δ|≳0.05±0.015 is barely compatible with the experimental f′←ππ rate (if one assumes that it is dominated by f′←f←ππ transition). Furthermore, experimentally Im δ≈0 which together with unitarity gives Re δ=−0.08±0.03, in clear discrepancy with the observed f′←ππ rate. This suggests that the mixing of f′ with higher f-like recurrences, which would at least partly cancel the f′←f←ππ transition, cannot be neglected. For the φ-ω mixing the unitarity bound is well satisfied and our prediction of Arg δ≈−5° is in agreement with the experimental estimate.