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Two-loop QCD corrections to e+e−→Z*→J/ψ+J/ψ

Xiang Chen1,*, Xin Guan2,†, Chuan-Qi He3,4,5,‡, and Yan-Qing Ma6,7,§

  • *Contact author: xiang.chen@physik.uzh.ch
  • †Contact author: guanxin@slac.stanford.edu
  • ‡Contact author: legend_he@m.scnu.edu.cn
  • §Contact author: yqma@pku.edu.cn
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Phys. Rev. D 113, 094017 – Published 8 May, 2026

DOI: https://doi.org/10.1103/n2sz-8b2x

Abstract

We present a next-to-next-to-leading-order (NNLO) calculation within the nonrelativistic QCD framework for the process e+e−→Z*→J/ψ+J/ψ. We find that the NNLO contribution is two to three times larger than the next-to-leading-order contribution, which itself is already three to five times larger than the leading-order result. In the high-energy limit, we provide analytic expressions for the leading-power coefficients in the asymptotic expansion of the two-loop amplitudes. Our results are directly applicable to the bottomonium process Z→ϒ+ϒ. Using the obtained hadronic amplitudes, we predict the decay width of the Z boson into these rare dicharmonium and dibottomonium final states.

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Phys. Rev. D 113, 094017– Published 8 May, 2026
  • Received 8 December 2025
  • Accepted 22 April 2026
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