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  • Open Access

Probing CP violation through vector boson fusion at high-energy muon colliders

Qing-Hong Cao1,2,3, Jian-Nan Ding3, Yandong Liu4,5,*, and Jin-Long Yuan1

  • *Contact author: ydliu@bnu.edu.cn
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Phys. Rev. D 113, 035029 – Published 24 February, 2026

DOI: https://doi.org/10.1103/f162-99qx

Abstract

We investigate CP-violating effects in electroweak interactions at future high-energy muon colliders within the Standard Model effective field theory framework. Focusing on four dimension-six CP-odd operators—OW˜,OHW˜,OHW˜B,OHB˜—we analyze vector boson fusion production of W and Higgs bosons using CP-odd observables and their asymmetries. With detailed simulations including parton showering, hadronization, and detector effects, we derive exclusion sensitivities through a binned likelihood analysis. For example, at s=3  TeV with 2  ab−1, the coefficient CW˜ can be constrained at the O(0.02) level, improving to O(0.008) at 10 TeV with 2  ab−1, and O(0.003) with 10  ab−1. These results significantly surpass current LHC and projected International linear collider sensitivities, demonstrating the unique potential of high-energy muon colliders to provide direct and model-independent probes of CP violation in the electroweak sector.

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Phys. Rev. D 113, 035029– Published 24 February, 2026
  • Received 17 November 2025
  • Accepted 2 February 2026
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Published by the American Physical Society under the terms of the Creative Commons Attribution 4.0 International license. Further distribution of this work must maintain attribution to the author(s) and the published article’s title, journal citation, and DOI. Funded by SCOAP3.

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