Regular Article - Theoretical Physics
Explaining the CDF-II W-boson mass anomaly in the Georgi–Machacek extension models
School of Physics, Zhengzhou University, 450000, Zhengzhou, People’s Republic of China
2 Institute of Physics, Henan Academy of Sciences, 450046, Zhengzhou, People’s Republic of China
Accepted: 6 February 2023
Published online: 11 February 2023
Original Georgi–Machacek model can preserve the custodial symmetry at tree level after the electroweak symmetry breaking. Unless additional custodial symmetry breaking effects are significant, the new physics contributions to are always very small. Our numerical results show that ordinary GM model can contribute to a maximal amount 0.0012 GeV, which can not explain the new CDF-II anomaly on W boson mass. We propose firstly to introduce small misalignment among the triplet VEVs to increase , which can give large new physics contributions to . Such slightly misaligned triplet VEVs from custodial symmetry preserving scalar potential can still be allowed. Our numerical results indicate that the resulting can easily reach the range of CDF-II data and the splitting among the triplet VEVs () can be as small as 0.8 GeV for GeV. We also propose to introduce an additional custodial symmetry breaking source by extending the GM model with a low scale RH neutrino sector, which can adopt the leptogenesis mechanism and allow moderately large coupling strength even for triplet VEVs of order GeV. With low scale RH neutrino mass scale of order – TeV, the new physics contribution to can reach 0.03 GeV and is much larger than that of ordinary GM model. Combining both custodial symmetry breaking effects, the small misalignment among the triplet VEVs and the moderately large couplings allowed with RH neutrino sector, the value of can still easily reach the range of CDF-II data, with a minimum splitting (among the triplet VEVs) approximately 0.7 GeV for GeV.
© The Author(s) 2023
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