The Effect of Majorana Phase in Degenerate Neutrinos

There are physical Majorana phases in the lepton flavor mixing matrix whenneutrinos are Majorana fermions. In the case of two degenerate neutrinos, thephysical Majorana phase plays the crucial role for the stability of the maximalflavor mixing between the second and the third generations against quantumcorrections. The physical Majorana phase of $\pi$ guarantees the maximal mixingto be stable against quantum corrections, while the Majorana phase of zero letsthe maximal mixing be spoiled by quantum corrections when neutrino masses areof O(eV). The continuous change of the Majorana phase from $\pi$ to 0 makes themaximal mixing be spoiled by quantum corrections with O(eV) degenerate neutrinomasses. On the other hand, when there is the large mass hierarchy betweenneutrinos, the maximal flavor mixing is not spoiled by quantum correctionsindependently of the Majorana phase.Comment: 7 pages, 1 figures, LaTe