Zhang Yu-Dong, Sang Wen-Long, Zhang Hong-Fei
School of Physical Science and Technology, Southwest University, Chongqing 400700, China.
College of Big Data Statistics, Guizhou University of Finance and Economics, Guiyang 550025, China.
Phys Rev Lett. 2022 Sep 9;129(11):112002. doi: 10.1103/PhysRevLett.129.112002.
In this Letter, we study the exclusive decay of ϒ into J/ψ in association with η_{c} (χ_{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 ϒ→J/ψ+χ_{c1} is obtained as 3.73_{-2.06-1.19}^{+5.10+0.10}×10^{-6}, which agrees well with the Belle measurement, i.e., Br(ϒ→J/ψ+χ_{c1})=(3.90±1.21±0.23)×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 ϒ(2S)→J/ψ+χ_{c1}, where some tension exists between theory and experiment. Having the polarized decay widths, we study the J/ψ 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.
在这篇快报中，我们研究了 Υ 到 J/ψ 与 ηc(χc0,1,2) 相关联的专属衰变。在非相对论性 QCD 框架内，计算了不同螺旋度配置下的衰变宽度至 QCD 次领头阶。我们发现 QCD 修正显著减轻了所有过程中衰变宽度对重整化标度的依赖。Υ→J/ψ + χc1 的分支比为 3.73−2.06−1.19+5.10+0.10×10−6，与 Belle 实验测量值吻合良好，即 Br(Υ→J/ψ + χc1)=(3.90±1.21±0.23)×10−6。对于其他过程，除了 Υ(2S)→J/ψ + χc1 在理论与实验之间存在一些差异外，我们的分支比结果与 Belle 实验给出的上限相符。利用极化衰变宽度，我们研究了 J/ψ 极化，结果表明其与任何非微扰参数无关。此外，根据我们的计算，由于高亮度，在超级 B 工厂测量所有这些过程是很有希望的。
