X荷

${\displaystyle SO(10)\supset SU(5)\times U(1)_{X}}$

${\displaystyle X{\begin{pmatrix}T\\F\\N\\\end{pmatrix}}={\begin{pmatrix}1\cdot T\\-3\cdot F\\5\cdot N\end{pmatrix}}}$

${\displaystyle SU(5)\times U(1)_{X}\to SU(3)\times SU(2)_{L}\times U(1)_{Y}\times U(1)_{B-L}}$

${\displaystyle (B-L)={\frac {1}{5}}(X+4Y)}$