摘要
The invisible variant axion models (VAMs) offer a very attractive solution for the strong CP problem without the domain wall problem. We consider the up-type specific variant axion models and examine their compatibility with the muon g-2 anomaly and the constraints from lepton flavor universality, several flavor observables, and top-quark measurements. We find that the combined χ2 fit favors the parameters mA∼15 GeV and tanβ∼40, the same as the type-X two-Higgs doublet model. Moreover, we find that there is no conflict with any flavor observables as long as the mixing angle ρu is sufficiently small. In particular, a small nonzero mixing angle ρu∼π/100 is slightly favored by the observed Bs→μμ branching ratio. The up-specific VAM predicts the flavor-violating top rare decay t→uA followed by A→ττ, which would provide a smoking-gun signature at the LHC. We show that current searches of A already impose some constraints on the parameter space but are not sensitive to the most interesting light mA region. We propose an efficient search strategy that employs ditau tagging using jet substructure information and demonstrate that it can enhance the sensitivity on BR(t→uA), especially in the light mA region. This model also predicts the flavor-violating decay of heavy Higgs bosons, such as H→tu, that would suppress the H→ττ/μμ decays. We also examine the up-specific VAM with the muon-specific lepton sector and the down-type specific VAMs as interesting alternative scenarios.