Effects of heavy meson loops on heavy quarkonium radiative transitions Cheng-Wei Zhao, Gang Li, Xiao-Hai Liu and Feng-Lan Shao Eur. Phys. J. C, 73 7 (2013) 2482 Published online: 02 July 2013 DOI: 10.1140/epjc/s10052-013-2482-y