gives them a Majorana nature. Therefore, $C$ must include at least two factors of Higgsino-gaugino mixing terms, each of which is proportional to the ratio of an electroweak VEV to $m_\text{soft}$: $$\label{eq:CX}
    C \sim \frac{v^2}{m_\text{soft}^3}.$$ A similar argument yields that $B\sim v/m_\text{soft}^2$ at lowest order. All of these conclusions can be verified with the full expressions in Appendix \[nu\].

The neutrino mass matrix is diagonalized by the so-called PMNS matrix: $$V_{PMNS} = 
    \begin{pmatrix}
        c_{12} c_{13}
        &
        s_{12} c_{13}
        &
        s_{13} e^{-i \delta}
        \\
        -s_{12} c_{23} - c_{12} s_{23} s_{13} e^{i \delta}
        &
        c_{12} c_{23} - s_{12}  s_{23} s_{13} e^{i \delta}
        &
        c_{13} s_{23}
        \\
        s_{12} s_{23} - c_{12} c_{23} s_{13}e^{i \delta}
        &
        -c_{12} s_{23} - s_{12} c_{23} s_{13} e^{i \delta}
        &
        c_{13} c_{23}
    \end{pmatrix} \times \text{diag}(1, e^{i \alpha/2}, 1),
\label{b1}$$ where $c_{ab} (s_{ab}) = \cos \theta_{ab} (\sin \theta_{ab})$. There are $N-1$ Majorana phases associated with N Majorana neutrinos. This translates into only one Majorana phase, $\alpha$, in this case because one of the neutrinos is massless and, therefore, does not have a Majorana mass. The CP phase $\delta$ corresponds to the freedom in the three-by-three $Y_\nu$ matrix. In models that predict a massless neutrino, such as the one discussed here, 