Decay of the Z′ gauge boson with lepton flavor violation

The flavor-violating decay of a new neutral massive gauge boson Z ′ → μ e is analyzed in the context of extended models, in which this particle emerges. By means of the analysis of the μ → e γ decay, μ - e conversion process in nuclei and the μ → e e + e - decay, the strength of the Z ′ μ e coupling is estimated and used to calculate the branching ratio of the Z ′ → μ e decay. This is done for the so-called Z S , Z LR , Z χ , Z ψ and Z η bosons. We found that, through the μ - e conversion process, the most restrictive bound for the coupling is provided by the Z LR boson. Meanwhile, by means of the μ → e e + e - decay, the most restrictive bound for the Z ′ μ e coupling is provided by the Z χ boson. However, if we concentrate on the less restrictive prediction for the Br( Z ′ → μ e ), this comes from the Z η boson and the resulting branching ratio is less than 10 - 4 . On the other hand, if we consider the most restrictive bound, the branching ratio for the process is below 2 × 10 - 7 , which results from the Z RL boson, and is obtained through the μ - e conversion process.