Hidden charmonium decays of psi (nS) through charmed meson loops

Abstract

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.