SO(10) GUT and quark-lepton mass matrices

The phenomenological model that all quark and lepton mass matrices have the same zero texture, namely their (1,1), (1,3), and (3,1) components are zeros, is discussed in the context of SO(10) grand unified theories (GUTs). The mass matrices of type I for quarks are consistent with the experimental data in the quark sector. For the lepton sector, consistent fitting to the data of neutrino oscillation experiments forces us to use the mass matrix for the charged leptons which is slightly deviated from type I. Given quark masses and charged lepton masses, the model includes 19 free parameters, whereas the SO(10) GUTs give 16 constrained equations. Changing the remaining three parameters freely, we can fit all the entries of the CKM quark mixing matrix and the MNS lepton mixing matrix, and three neutrino masses consistently with the present experimental data.