On the Fukugita-Tanimoto-Yanagida ansatz with partially non-degenerate right-handed Majorana neutrinos

Taking three right-handed Majorana neutrino masses Mi to be partially non-degenerate, we make a new analysis of the Fukugita-Tanimoto-Yanagida ansatz and confront it with current neutrino oscillation data. We determine the parameter space for cases (A) M3=M2≠M1, (B) M2=M1≠M3 and (C) M1=M3≠M2, and examine their respective deviations from the original M1=M2=M3 case. The numerical constraints on three light neutrino masses, three neutrino mixing angles and three CP-violating phases are also obtained, together with the predictions for the Jarlskog invariant of CP violation and the effective masses of the tritium beta decay and the neutrinoless double-beta decay.