The seesaw Lagrangian is $$-\mathcal{L}_{\rm mass}=\frac{Y^\ell_{ab}\langle H^0\rangle}{\sqrt{2}}\bar{\ell}_{aL}\ell_{bR}+\frac{Y^\nu_{ab}\langle H^0\rangle}{\sqrt{2}}\bar{\nu}_{aL}\nu_{bR}+\frac{1}{2}M_{ab}\bar{\nu}^C_{aR}\nu_{bR}+\text{h.c.}$$ For $3$ left(right)-handed charged leptons $\ell_{L(R)}$, $3$ left(right)-handed neutrinos $\nu_{L(R)}$, there are $18+18$ real parameters coming from the complex $3\times 3$ Yukawa matrices $Y^\ell, Y^\nu$ and $12$ more from complex symmetric $3\times 3$ Majorana matrix $M$. Therefore, the total real parameters in this Lagrangian is $48$.
- What is wrong in this counting? Please help!