Phenomenological Study of Lepton Flavor Violation in Z Boson Decays with Constrained MSSM Extended by Type-II Seesaw Model

TL;DR

This study investigates lepton flavor violation in Z boson decays within a supersymmetric model extended by a type-II seesaw, predicting very low branching ratios well below current experimental detection limits.

Contribution

It provides the first detailed calculation of Z boson LFV decay branching ratios in the CMSSM extended by the type-II seesaw, considering experimental constraints and suppression effects.

Findings

Branching ratios are around 6×10^{-10} for eμ channel.

Branching ratios are around 10^{-9} for τμ and τe channels.

Predicted ratios are far below current experimental limits.

Abstract

In this work, we study the lepton flavor violation (LFV) of Z boson decays in the framework of the constrained minimal supersymmetric standard model (CMSSM) extended by the type-II seesaw model. The branching ratios of $Z\longrightarrow l_i l_j$ decays are calculated in this model. Here, $l_i$ and $l_j$ are different flavor charged leptons. After fitting to the experimental mass limits of the neutrino and supersymmetric particles, we have found that the branching ratios for LFV decays of Z boson are in the order of $6 \times {10}^{-10}$ for $e \mu$ channel and of $1 \times {10}^{-9}$ for both $\tau \mu$ and $\tau e$ decay channels. Considering recent experimental constraints on $l_{i}\rightarrow l_{j} \gamma$ decays, the branching ratios for LFV decays of Z boson get an additional suppression of $10^{-8}$ for $e \mu$ channel and of $10^{-3}$ for both $\tau \mu$ and $\tau e$ decay channels. The branching ratios theoretical predictions are several orders below the recent experimental limits for both scenarios, which give a very low probability to observe the LFV decays of Z boson in the future experiments.