Neutrino mass matrix model with a bilinear form

A bstract A neutrino mass matrix model with a bilinear form is proposed within the framework of the so-called yukawaon model, which has been proposed for the purpose of a unified description of the lepton mixing matrix U PMNS and the quark mixing matrix V CKM . The model has only two adjustable parameters for the PMNS mixing and neutrino mass ratios. (Other parameters are fixed from the observed quark and charged lepton mass ratios and the CKM mixing.) The model gives reasonable values sin 2 2 θ 12 ≃ 0.85, sin 2 2 θ 23 ~ 1 and sin 2 2 θ 13 ~ 0.09 together with . Our prediction of the effective neutrino mass 〈 m 〉 in the neutrinoless double beta decay takes a sizable value 〈 m 〉 ≃ 0.0034 eV.