model also involves an $SU(4)$ sextet field $D=(6,1,1)=(D_3,D^c_3)$.

The superpotential of the minimal 422 model is : $$\begin{aligned}
{\cal W} &=& F \lambda F^c h + \lambda_h S h h + \nonumber \\
         & & \lambda_S S (\bar H H - M^2_H) +
             \lambda_H H H D + \lambda_{\bar H} {\bar H} {\bar H} D +
             F^c \lambda' F^c \,{H H \over M_V}
\label{W3}\end{aligned}$$ where $S$ denotes a gauge singlet superfield, the $\lambda$’s are real dimensionless parameters and $M_H \sim M_X \sim 10^{16} {\rm\ GeV}$. Additionally, $M_V > M_X$ denotes the mass of extra exotic matter that has been integrated out from the model at high energy. As a result of the superpotential terms involving the singlet $S$, the Higgs fields develop VEVs $\langle H \> \rangle = \langle H_\nu \rangle \sim M_X$ and $\langle \bar H \rangle = \langle \bar H_\nu \rangle \sim M_X$ which lead to the symmetry breaking : $$SU(4) \otimes SU(2)_L \otimes SU(2)_R \to
SU(3)_c \otimes SU(2)_L \otimes U(1)_Y.
\label{422:321}$$ The singlet $S$ itself also naturally develops a small VEV of the order of the SUSY breaking scale [@KiSh] so that the $\lambda_h S$ term in Eq.  gives an effective $\mu$ parameter of the correct order 