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Solving the rho - pi puzzle by higher charmonium Fock states

Yu-Qi Chen
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Abstract

A new explanation for the longstanding puzzle of the tiny branching fraction of psi' --> rho pi relative to that for J/psi --> rho pi was proposed. In the case of J/psi, we argue that this decay is dominated by a higher Fock state in which the c cbar pair is in a color-octet ^3S_1 state and annihilates via the process c cbar --> q qbar. In the case of the psi', we argue that the probability for the c cbar c pair in this higher Fock state to be close enough to annihilate is suppressed by a dynamical effect related to the small energy gap between the mass of the psi' and the D Dbar threshold.

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Yu-Qi Chen. 1998-08-06. Solving the rho - pi puzzle by higher charmonium Fock states. https://arxiv.org/abs/hep-ph/9808237

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