Neutrino Mass Matrix with Two Zeros and Leptogenesis
  The leptogenesis is studied in the neutrino mass matrix with two zeros, which reduces the number of independent phases of the CP violation. These texture zeros are decomposed into the Dirac neutrino mass matrix and the right-handed Majorana one in the see-saw mechanism. It is found that there are six textures for the Dirac neutrino mass matrix, among which one texture with three zeros has three phases, three textures with four zeros have two phases, and two textures with five zeros have only one phase in the basis with the real right-handed Majorana mass matrix. The relation between the leptogenesis and the low energy CP violation is discussed in typical textures. It is remarked that the leptogenesis is linked strongly with the CP violation in the neutrino oscillations. The predicted baryon asymmetry of the universe is consistent with the observed value. 
S. Kaneko and M. Tanimoto (Niigata University)