Next-to-leading-order QCD corrections to the decay of Z boson into χc(χb)

Sun, Zhan (Department of Physics, Guizhou Minzu University, Guiyang 550025, People’s Republic of China) ; Zhang, Hong-Fei (College of Big Data Statistics, Guizhou University of Finance and Economics, Guiyang 550025, China)

10 May 2019

Abstract: Based on the framework of nonrelativistic quantum chromodynamics, we carry out next-to-leading-order (NLO) QCD corrections to the decay of Z boson into χc and χb, respectively. The branching ratio of Zχc(χb)+X is about 105(106). For the color-singlet (CS) P3J[1] state, the heavy quark-antiquark pair associated process serves as the leading role. However the process of ZQQ¯[P3J[1]]+g+g can also provide non-negligible contributions, especially for the χb cases. In the case of the color-octet (CO) S31[8] state, the single-gluon-fragmentation diagrams that first appear at the NLO level can significantly enhance the leading-order results. Consequently the CO contributions account for a large proportion of the total decay widths. Moreover, including the CO contributions will thoroughly change the CS predictions on the ratios of Γχc1/Γχc0, Γχc2/Γχc0, Γχb1/Γχb0, and Γχb2/Γχb0, which can be regarded as an outstanding probe to distinguish between the CO and CS mechanism. Summing over all the feeddown contributions from χc and χb, respectively, we find Γ(ZJ/ψ+X)|χcfeeddown=(0.282.4)×105 and Γ(Zϒ(1S)+X)|χbfeeddown=(0.150.49)×106.

Published in: Physical Review D 99 (2019)
Published by: APS
DOI: 10.1103/PhysRevD.99.094009
arXiv: 1809.02426
License: CC-BY-4.0

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