Neutrino Mass Matrix with No Adjustable Parameters

On the basis of the so-called “yukawaon” model, we found out a special form of the neutrino mass matrix $M_{\nu }$ which gives reasonable predictions. The $M_{\nu }$ is given by a multiplication form made of charged lepton mass matrix $M_e$ and up-quark mass matrix $M_u$. This $M_{\nu }$ has no adjustable parameters except for those in $M_e$ and $M_u$. Here, $M_e$ and $M_u$ are described by one parameter $a_e$ (real) and two parameters $a_u$ (complex), respectively, and those parameters are constrained by their observed mass ratios. With this form of $M_{\nu }$, in spite of having only three parameters, the $M_{\nu }$ can give reasonable predictions ${\sin }^{2}2{\theta }_{atm}\simeq 0.99$, $\sin^2 2\theta_{13} \simeq 0.015$,$\Delta m^2_{21}/\Delta m^2_{32} \simeq 0.030$,$< m_{ee}> \simeq 0.0039$eV,andsoon,byusingobservedvaluesof$m_e/m_\mu$,$m_\mu/m_\tau$,$m_c/m_t$,and$\sin^2 \theta_{solar}$ as input values.