Mass Matrices and Their Renormalization
  We obtain explicitly the renormalization group equations for the quark mass matrices in terms of a set of rephasing invariant parameters. For a range of assumed high energy values for the mass ratios and mixing parameters, they are found to evolve rapidly and develop hierarchies as the energy scale decreases. To achieve the experimentally observed high degree of hierarchy, however, the introduction of new models with specific properties becomes necessary. 
Shao-Hsuan Chiu, T. K. Kuo, Tae-Hun Lee, Chi Xiong