Decay of the $$Z^\prime $$ gauge boson with lepton flavor violation

Abstract

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