Probing Sterile Neutrino via Lepton Flavor Violating Decays of Mesons

A sterile neutrino at GeV mass scale is of particular interest in this work. Though not take part in neutrino oscillation, the sterile neutrino can induce flavor violating semileptonic and leptonic decay of $K,D$ and $B$ mesons. We calculated a box diagram contribution in these processes. By making use of current experiment limit of lepton flavor violating decays $M^+h\to M_l^+\ell_1^+\ell_2^-$and$M^0\to \ell_1^-\ell_2^+$, we explore the allowed parameter space of $U_{e4}$ and $U_{\mu 4}$ in different mass ranges. Generally speaking, both channels give a limit to the product of $U_{e4}$ and $U{\mu 4}$\mathrm{.}Whensterileneutrinomassislocatedinbetweenpionandkaonmass,$K^+\to \pi^+ e^{\pm}\mu^{\mp}$givesthestrongestconstraintwhile$B^+\to \pi^+ e^{\pm} \mu^{\mp}$ provides the dominated constraint when its mass in between of kaon and B meson. If sterile neutrino is even heavier than B mesons, the $B_s^0\to {\mu }^{\pm }{e}^{\mp }$ experiment which is performed at LHCb gives the strongest constraint.