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Next-to-next-to-leading order event generation for Z-boson production in association with a bottom-quark pair

Javier Mazzitelli1, Vasily Sotnikov2, and Marius Wiesemann3

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Phys. Rev. D 112, 056031 – Published 24 September, 2025

DOI: https://doi.org/10.1103/1kqt-s3vk

Abstract

We consider the production of a Z boson decaying to leptons in association with a bottom-quark pair in hadronic collisions. For the first time, we compute predictions at next-to-next-to-leading order (NNLO) in QCD, and we combine them with the all-order radiative corrections from a parton-shower simulation (NNLO+PS). Our method represents the first approach to NNLO+PS event generation applicable to processes featuring a color singlet and a heavy-quark pair in the final state. The novel two-loop corrections are computed for massless bottom quarks, and the leading mass corrections are restored through a small-mass expansion. The calculation is carried out in the four-flavor scheme, and we find that the sizable NNLO QCD corrections lift the long-standing tension between lower-order predictions in four- and five-flavor schemes. Our predictions are compared to a CMS measurement for Z boson plus b-jet production, achieving an excellent description of the data.

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Phys. Rev. D 112, 056031– Published 24 September, 2025
  • Received 23 April 2024
  • Accepted 20 August 2025
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