Relating the neutrino mixing angles to a lepton mass hierarchy

Abstract

We propose two phenomenological scenarios of lepton mass matrices and show that either of them can exactly give rise to tan2θ13=me/(me+2mμ), tan2θ23=mμ/(me+mμ) and tan2θ12=(mem2+2mμm1)/(mem1+2mμm2) in the standard parametrization of lepton flavor mixing. The third relation, together with current experimental data, predicts a normal but weak hierarchy for the neutrino mass spectrum. We also obtain θ13≈2.8° for the smallest neutrino mixing angle and J≈1.1% for the Jarlskog invariant of leptonic CP violation, which will soon be tested in the long-baseline reactor and accelerator neutrino oscillation experiments. A seesaw realization of both scenarios is briefly discussed.