From transition magnetic moments to Majorana neutrino masses

It is well known that a Majorana mass induces a (small) transition magnetic moment. The converse is also true; in this Letter we estimate the loop contribution of transition magnetic moments [μ]αβ to the neutrino mass matrix [m]αβ. We show that for hierarchical neutrino masses, the contribution of [μ]eτ to [m]eτ can exceed the experimental value of [m]eτ.