Seesaw model and its Lorentz group formulation
  For two flavors, the seesaw matrix can be identified with a two dimensional representation of the Lorentz group. This analogy facilitates the computation of physical neutrino parameters, while giving an intuitive understanding of the results. It is found that the induced mixing angle exhibits resonance behavior. For maximal mixing, we derive a precise relation among the right-handed mixing angle, the Majorana mass ratio, and their phase. 
T. K. Kuo, Guo-Hong Wu, and Shao-Hsuan Chiu