Constraints on Parameters of the R_F Parity Model from Quark and Neutrino Mass Matrices

The forms of quark and lepton mass matrices are severely restricted in the $R_F$ parity model. We determine the form of the quark mass matrix first and derive the form of the neutrino mass matrix. For this to be consistent with the present experiments, we conclude that the masses of the superpartners of the right--handed down-type squarks and sneutrino vacuum expectation values satisfy, ${m_{\tilde{d}_{Rj}}}\vmu \gtrsim 400 ~{\rm GeV}^2 $ or ${m_{\tilde{d}_{Rj}}}\vtau \gtrsim 400 ~{\rm GeV}^2 $. We also find that without a sterile neutrino it is difficult to obtain a large mixing angle solution of $\nu_\mu$ and $\nu_\tau$. With a sterile neutrino, we show a possibility for a large mixing angle solution of $\nu_\mu$ with $\nu_{\rm sterile}$.