Lepton flavor violating decays $l_j \rightarrow l_i\gamma$ in the $U(1)_X$VLFM

Abstract

In the $U(1)_X$ vector-like fermion model ($U(1)_X$VLFM), the Standard Model(SM) gauge group is extended with an additional $U(1)_X$ symmetry. Vector-like fermions and right-handed neutrinos are introduced, providing new sources of lepton flavor violation(LFV). In this paper, we perform a detailed study of the LFV decays $l_j \to l_i \gamma$ (with $j = \tau, \mu$; $i = \mu, e$; $i \neq j$) in this model. The numerical results show that, in certain parameter regions, the branching ratios of these processes can become large enough to be probed in future experiments. This work provides important theoretical guidance and constraints for exploring new physics beyond the SM.