Constraining active-sterile neutrino mixing via lepton flavor violating decays of mesons

As a hypothetic particle, a sterile neutrino can exist in types of new physics models. In this work by investigating flavor violating semileptonic and leptonic decays of K , D , and B mesons induced by the GeV scale sterile neutrino, we explore its allowed regions in parameter space. Analytically, we derive branching fractions of semileptonic decay M h + → M l + ℓ 1 + ℓ 2 − and leptonic decay M 0 → ℓ 1 − ℓ 2 + , including the contribution from a new box diagram contribution due to the massive sterile neutrino. Imposing its mass ranges, we numerically analyze the active-sterile neutrino mixings in corresponding regions. We find that when the sterile neutrino mass is located in between pion and kaon mass, K + → π + e ± μ ∓ gives the strongest constraint while B + → π + e ± μ ∓ provides the dominated constraint when its mass in between of kaon and B meson. If the sterile neutrino is even heavier than B mesons, the LHCb B s 0 → μ ± e ∓ results gives the strongest constraint.