Hidden charmonium decays of $$\psi (nS)$$ through charmed meson loops
Shidong Liu (College of Physics and Engineering, Qufu Normal University, Qufu, 273165, China); Zuxin Cai (College of Physics and Engineering, Qufu Normal University, Qufu, 273165, China); Yuanxin Zheng (College of Physics and Engineering, Qufu Normal University, Qufu, 273165, China); Gang Li (CAS Key Laboratory of Theoretical Physics, Institute of Theoretical Physics, Chinese Academy of Sciences, Beijing, 100190, China, College of Physics and Engineering, Qufu Normal University, Qufu, 273165, China)
We calculated transitions of the higher radial excited charmonia $$ \psi (nS) ~ ( n=3,4,5 )$$ to the orbital excited charmonium $$ h_c(1P) $$ with emission of one pion or eta meson. In calculations, the intermediate S- and P-wave charmed meson loops were considered in terms of the nonrelativistic effective field theory. The results indicate that the transitions of interest are dominated by the loops involving the $$ s_l^P=(1/2)^+ $$ charmed mesons, whereas the $$ s_l^P=(1/2)^- $$ charmed meson loops are of minor contributions. The partial decay widths of $$ \psi (nS) \rightarrow h_c \pi ^0 $$ are of the order of 0.01–1 keV. For the case of $$ \psi (nS) \rightarrow h_c \eta $$ , the partial decay widths are from 0.1 to 100 keV, implying the branching ratios from $$ 10^{-5} $$ to $$ 10^{-3} $$ . Moreover, the partial decay widths for $$ \psi (nS) \rightarrow h_c \eta $$ are found to decrease as the $$ \eta $$ - $$ \eta ' $$ mixing angle increases. It is hoped that the present calculated results would be observed in the future experiments.