Lepton and quark mass matrices - art. no. 013006

We propose a model that all quark and lepton mass matrices have the same ze ro texture. Namely, their (1,1), (1,3), and (3,1) components are zeros. The mass matrices are classified into two types. Type I is consistent with exp erimental data in the quark sector. For the lepton sector, if the seesaw me chanism is not used, type II allows a large nu(mu)-nu(tau) mixing angle. Ho wever, severe compatibility with all neutrino oscillation experiments force s us to use the seesaw mechanism. If we adopt the seesaw mechanism, it turn s out that type I instead of type II can be consistent with experimental da ta in the lepton sector too. [S0556-2821(99)05613-1].