Renormalization Invariants of the Neutrino Mass Matrix
  The renormalization evolution of all parameters in the neutrino mass matrix depends only on one variable, the energy scale. This fact, coupled with rephasing considerations, leads to a set of renormalization invariants, correlating the evolution of physical parameters. For the general three flavor case, we obtain these invariants explicitly and discuss their implications. 
Sanghyeon Chang and T. K. Kuo