O(& alpha;s2) corrections to J/& psi; plus & chi;c0,1,2 production at B factories

We compute the O(& alpha;s2) corrections to the exclusive channels e+e- & RARR; J/& psi; + & chi;cJ (J = 0, 1, 2) at & RADIC;s = 10.58 GeV within the nonrelativistic QCD (NRQCD) factorization framework. The validity of NRQCD factorization at O(& alpha;s2) has been confirmed for these double-charmonium exclusive production processes. We analyze the impact of the O(& alpha;s2) corrections on the polarized and unpolarized cross sections, as well as the J/& psi; angular distributions, which largely reduce the renormalization scale dependence but increase the O(& alpha;s) NRQCD predictions to some extent for & chi;c0,1. With high numerical accuracy, our predictions for & sigma;(J/& psi; + & chi;c1,2) through O(& alpha;s2) are compatible with the upper limit of the Belle measurement. Although the theoretical prediction for & sigma;( J/& psi; + & chi;c0) is consistent with both Belle and BaBar measurements within uncertainties, there still exists serious tension between the predicted and the measured profiles for the J/& psi; angular distribution. Regarding the bright observation prospect of the e+e- & RARR; J/& psi; + & chi;c1,2 channels in Belle 2 experiment, it is interesting to compare the future measurements with our NRQCD predictions. The more accurate measurement of e+e- & RARR; J/& psi; + & chi;0 at Belle 2 will also help to clarify the long-standing puzzle of J/& psi; angular distribution.& COPY; 2023 Institute of High Energy Physics, Chinese Academy of Sciences. Published by Elsevier B.V. This is an open access article under the CC BY license (http://creativecommons .org /licenses /by /4 .0/). Funded by SCOAP3.

Automated summary

In this study, we compute the O(αs^2) corrections to the exclusive channels e+e- -> J/ψ + χcJ (J = 0, 1, 2) within the nonrelativistic QCD (NRQCD) factorization framework at √s = 10.58 GeV. The validity of NRQCD factorization at O(αs^2) has been confirmed and the impact of the O(αs^2) corrections on the polarized and unpolarized cross sections, as well as the J/ψ angular distributions, are analyzed. Our predictions for σ(J/ψ + χc1,2) through O(αs^2) are compatible with the upper limit of the Belle measurement. However, there is still tension between the predicted and measured profiles for the J/ψ angular distribution. The future measurements in the Belle 2 experiment can provide interesting comparisons with our NRQCD predictions.