  The particle spectrum of all Majorana neutrino mass models with spontaneous
violation of global lepton number include a Goldstone boson, the so-called
majoron. The presence of this massless pseudoscalar changes the phenomenology
dramatically. In this work we derive general analytical expressions for the
1-loop coupling of the majoron to charged leptons. These can be applied to any
model featuring a majoron that have a clear hierarchy of energy scales,
required for an expansion in powers of the low-energy scale to be valid. We
show how to use our general results by applying them to some example models,
finding full agreement with previous results in several popular scenarios and
deriving novel ones in other setups.
