Constraints on νi → νjγ from μ → eγ, τ → μγ, eγ

Using the effective Lagrangian approach, we obtain bounds on the lepton-number-nonconserving decays νμ → νeγ, ντ → νμγ, νeγ from the known experimental constraints on μ → eγ and τ→ μγ, eγ. We get a bound on the transition magnetic moment of the muon neutrino κμe ⩽ 1 × 10−11 for mνμ ⩽ 270 keV, which improves the bound obtained from astrophysical considerations. Our results also lead to bounds on the transition magnetic moments of the τ neutrino.