The studies on $$Z \rightarrow \Upsilon (1S)+g+g$$ Z→Υ(1S)+g+g at the next-to-leading-order QCD accuracy

• Main Author: Zhan Sun
• Format: Article
• Language: English
• Published: SpringerOpen 2020-04-01
• Series: European Physical Journal C: Particles and Fields
• Online Access: http://link.springer.com/article/10.1140/epjc/s10052-020-7873-2

Abstract In this paper, we carry out the next-to-leading-order (NLO) studies on $$Z \rightarrow \Upsilon (1S)+g+g$$ Z→Υ(1S)+g+g via the color-singlet (CS) $$b{\bar{b}}$$ bb¯ state. We find the newly calculated NLO QCD corrections to this process can significantly influence its leading-order (LO) results and greatly improve the dependence on the renormalization scale. By including the considerable feeddown contributions, the branching ratio $${\mathcal {B}}_{Z \rightarrow \Upsilon (1S)+g+g}$$ BZ→Υ(1S)+g+g is predicted to be (0.56–0.95) $$\times 10^{-6}$$ ×10-6 , which can reach up to 19–31$$\%$$ % of the LO predictions given by the CS dominant process $$Z \rightarrow \Upsilon (1S)+b+{\bar{b}}$$ Z→Υ(1S)+b+b¯ . Moreover, $$Z \rightarrow \Upsilon (1S)+g+g$$ Z→Υ(1S)+g+g also seriously affects the CS predictions on the $$\Upsilon (1S)$$ Υ(1S) energy distributions, especially when z is relatively small. In summary, for the inclusive $$\Upsilon (1S)$$ Υ(1S) productions in Z decay, besides $$Z \rightarrow \Upsilon (1S)+b+{\bar{b}}$$ Z→Υ(1S)+b+b¯ , the gluon radiation process $$Z \rightarrow \Upsilon (1S)+g+g$$ Z→Υ(1S)+g+g can provide indispensable contributions as well.