Higher-Order QCD Corrections to ? Decay into Double Charmonia

In this Letter, we study the exclusive decay of Upsilon into J=psi in association with eta c (chi c0;1;2). The decay widths for different helicity configurations are evaluated up to QCD next-to-leading order within the nonrelativistic QCD framework. We find that the QCD corrections notably mitigate the renormalization scale dependence of the decay widths for all the processes. The branching fraction of Upsilon & RARR; J=psi +chi c1 is obtained as 3.73+5.10+0.10 -2.06-1.19 x 10-6, which agrees well with the Belle measurement, i.e., Br(Upsilon & RARR; J=psi+chi c1) = (3.90+ 1.21 + 0.23) x 10-6. For the other processes, our results of the branching fractions are compatible with the upper limits given by the Belle experiments, except for Upsilon(2S) & RARR; J=psi +chi c1, where some tension exists between theory and experiment. Having the polarized decay widths, we study the J=psi polarization, which turns out to be independent of any nonperturbative parameters. Further, according to our calculation, it is promising to measure all the processes at Super B factory thanks to the high luminosity.

Automated summary

In this letter, the exclusive decay of Upsilon into J=psi in association with eta c (chi c0;1;2) is studied. The decay widths for different helicity configurations are calculated within the nonrelativistic QCD framework and the QCD corrections are found to mitigate the renormalization scale dependence. The results of the branching fractions for most processes are in agreement with experiments, except for one process where tension exists between theory and experiment. The J=psi polarization is found to be independent of nonperturbative parameters and all processes can be measured at Super B factory with high luminosity.