A Simple Realization of the Inverse Seesaw Mechanism
  Differently from the canonical seesaw mechanism, which is grounded in grand unified theories, the inverse seesaw mechanism lacks a special framework that realizes it naturally. In this work we advocate that the 3-3-1 model with right-handed neutrinos has such an appropriate framework to accommodate the inverse seesaw mechanism. We also provide an explanation for the smallness of the $\mu$ parameter and estimate the branching ratio for the rare lepton flavor violation process $\mu \rightarrow e\gamma$. 
A. G. Dias, C. A. de S. Pires, P. S. Rodrigues da Silva, A. Sampieri
hep-ph