Lepton Flavor Violating $l\to l^{\prime }\gamma$ and $Z\to l{\bar{l}}^{\prime }$ Decays Induced by Scalar Leptoquarks

Abstract

Motivated by the recent muon $g-2$ data, we study the lepton flavor violating $l\to l^{\prime }\gamma$ and $Z\to l{\bar{l}}^{\prime }$ ($l,l^{\prime }=e,\mu ,\tau$) decays with $l\ne l^{\prime }$ in a scalar leptoquark model. Leptoquarks can produce sizable LFV $l\to l^{\prime }\gamma$ decay rates that can be easily reached by present or near future experiments. % Leptoquark masses and couplings are constrained by the muon $g-2$ data and the current $l\to l^{\prime }\gamma$ bounds. We predict $Br(Z\to {\tau }^{\mp }{e}^{\pm })$ reaching the present limit ($10^{-5}$) and $Br(Z\to {\mu }^{\mp }{\tau }^{\pm })$ reaching $2\times 10^{-8}$, which will be accessible by future linear colliders, whereas, the current bounds on LFV impose very strong constraints on the $Br(Z\to {\mu }^{\mp }{e}^{\pm })$ and the ratio is too low to be observed in the near future.

Comments: 18 pages, 6 figures, version to appear in Phys. Rev. D