Abstract
In this paper, we study double charmonia production in upsilon peaks, especially a S-wave charmonium and a P-wave charmonium , or a S-wave charmonium and the and within the nonrelativistic QCD (NRQCD) approach, which is a powerful tool to realize the factorization of double charmonia production in electron-positron annihilation. The state can provide an ideal laboratory for studying the properties of double-heavy quarkonium and also can separate the perturbative and nonperturbative parts due to the large heavy quark mass compared with the typical hadron scale . Explanation of the and as the and states, respectively, are compatible with the observed upper limits for the branching fractions of , where , by the Belle Collaboration. The branching fractions of are predicted to be around , which shall be tested in Belle-II experiments.
- Received 17 August 2015
DOI:https://doi.org/10.1103/PhysRevD.92.074017
© 2015 American Physical Society