Two-pion transitions in quarkonium revisited

Abstract

Two-pion transitions in charmonium and bottomonium are considered with the leading relativistic effects taken into account. The contribution of the chromo- magnetic interaction of the charmed quarks to the amplitude of the decay $\psi (2S)\to \pi \pi J/\psi$ is estimated from the available data. This contribution is enhanced by a factor of three in the decay ${\eta }_c(2S)\to \pi \pi {\eta }_c$ and should produce a noticeable modification of the rate and the spectrum in the latter decay. It is argued that the peculiar observed spectrum in the decay ${\rm Y}(3S)\to \pi \pi {\rm Y}$ arises due to a dynamical suppression of the leading nonrelativistic quarkonium amplitude and thus enhanced prominence of the relativistic terms. Also discussed are the effects of the final state interaction between the pions.

23 pages, 2 figures

References in corpus (2)

• Chromo-polarizability and pipi final state interaction
• First Observation of Upsilon(1D) States

Cited by in corpus (9)

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• The Exotic XYZ Charmonium-like Mesons
• Quarkonia and their transitions
• Implications of heavy quark spin symmetry on heavy meson hadronic molecules
• Pionic transitions from X(3872) to chi_{cJ}
• Bottomonium dipion transitions
• Di-Pion Decays of Heavy Quarkonium in the Field Correlator Method
• Remarks on the amplitude of the decay Upsilon(3S) -> Upsilon(1S) pi pi