Zhao, Q (reprint author), Chinese Acad Sci, Inst High Energy Phys, Beijing 100049, Peoples R China.
Intermediate hadronic meson loop contributions to J/psi, psi' -> gamma eta(c) (gamma eta'(c)) are studied apart from the dominant M1 transitions in an effective Lagrangian approach. Due to the property of the unique antisymmetric tensor Coupling in V -> V P, the hadronic loop transitions provide explicit corrections to the M1 transition amplitudes derived from the naive "quenched" c (c) over bar transitions via the coupling form factors. This mechanism interfering with the M1 transition amplitudes naturally accounts for the deviations from the Godfrey-Isgur model predictions in J/psi and psi' -> gamma eta(c). It also predicts a small branching ratio of psi' -> gamma eta'(c), which can be examined by experimental measurements at BES and CLEO-c. (C) 0 2008 Elsevier B.V. All rights reserved.