Key points are not available for this paper at this time.
Valuable data on quarkonia (the bound states of a heavy quark Q=c, b and the corresponding antiquark) have recently been provided by a variety of sources, mainly e^+e^- collisions, but also hadronic interactions. This permits a thorough updating of the experimental and theoretical status of electromagnetic and strong transitions in quarkonia. The QQ transitions to other QQ states are discussed, with some reference to processes involving QQ annihilation.
Eichten et al. (2008) studied this question.