Double ccbar production in e+e- annihilations at high energy

TL;DR

This paper reviews experimental findings on double ccbar production in high-energy e+e- annihilations, confirming large cross-sections and highlighting the significance of hidden-charm states in the mass spectrum.

Contribution

It provides a comprehensive review of experimental data on double ccbar production, emphasizing the confirmed large cross-sections and the role of hidden-charm states.

Findings

Large cross-sections (~20 fb) confirmed for e+e- -> gamma* -> psi(') ccbar_res

Hidden-charm states are prominent above open-charm threshold

Experimental results are consistent across multiple groups

Abstract

We review the current state of experimental knowledge on double ccbar production in e+e- annihilation. The large cross-sections (O(20 fb)) for e+e- -> gamma* -> psi(') ccbar_{res} processes have been confirmed by detailed tests and reproduced by a second group: they should now be considered well-established. The latest experimental results concern the case where the second ccbar system is above open-charm threshold: hidden-charm states continue to play a prominent role in the mass spectrum. Some ``loose ends'' in the field are also briefly discussed.