Regular Article - Theoretical Physics
Rare top-quark decays in the aligned two-Higgs-doublet model
Institute of Particle Physics and Key Laboratory of Quark and Lepton Physics (MOE), Central China Normal University, 430079, Wuhan, Hubei, China
2 School of Physics and Microelectronics, Zhengzhou University, 450001, Zhengzhou, Henan, China
Accepted: 18 September 2022
Published online: 6 October 2022
We update the Standard Model (SM) predictions for the branching ratios of the rare top-quark decays , and evaluate the maximum rates that can be reached in the aligned as well as in the four conventional two-Higgs-doublet models (2HDMs) with symmetries. Taking into account the relevant constraints on the model parameters resulting from a global fit obtained at the confidence level, we find that the branching ratios of and decays can reach up to and respectively, being therefore of the same order, in the aligned 2HDM (A2HDM). This is obviously different from the SM case, where the predicted branching ratio of the three-body decay is about two orders of magnitude larger than that of the two-body decay . On the other hand, compared with the SM predictions, no significant enhancements are observed in the four conventional 2HDMs with symmetries for the branching ratios of these two decays. Nevertheless, the predicted branching ratios of and decays in the A2HDM are still out of the expected sensitivities of the future high-luminosity Large Hadron Collider and the Future Circular Collider in hadron-hadron mode.
© The Author(s) 2022
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