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Parameter inference from final-state entanglement in Higgs boson decays

Jia Liu1,2,*, Masanori Tanaka2,†, Xiao-Ping Wang3,‡, Jing-Jun Zhang1,§, and Zifan Zheng1,∥

  • *Contact author: jialiu@pku.edu.cn
  • †Contact author: tanaka@pku.edu.cn
  • ‡Contact author: hcwangxiaoping@buaa.edu.cn
  • §Contact author: zhang_jingjun@stu.pku.edu.cn
  • ∥Contact author: zifanzheng@pku.edu.cn
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Phys. Rev. D 114, 015036 – Published 23 July, 2026

DOI: https://doi.org/10.1103/jynb-w9kq

Abstract

The decay out states of unstable Standard Model (SM) particles provide a natural, well-defined quantum-information probe of the SM parameter space. We use Higgs boson decays as a test case: After tracing out kinematics, we compute entanglement among final-state spins and colors across all decay channels and investigate a near-maximal entanglement-entropy criterion. This criterion turns out to be informative about fundamental parameters. Within the SM, we find that the entanglement entropy exhibits a global maximum close to the observed Higgs boson mass and the measured W mass, the latter being equivalent to the SU(2)L gauge coupling. In a two-parameter kappa framework, applying the same criterion is consistent with an SM-like balance between Higgs boson couplings to vector bosons and to fermions, providing sensitivity to the ratio of the sector-wide rescalings. These results suggest that entanglement extremality may serve as a complementary handle on fundamental parameters.

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Phys. Rev. D 114, 015036– Published 23 July, 2026
  • Received 26 November 2025
  • Accepted 25 June 2026
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