Under $SU(3)_c\times SU(2)_L\times U(1)_Y$, one <Standard Model fermion> generation including a <right-handed neutrino> is
$$
\begin{array}{c|c}
\text{field}&\text{representation}\\ \hline
Q_L=(u_L,d_L)&(\mathbf3,\mathbf2)_{1/6}\\
u_R&(\mathbf3,\mathbf1)_{2/3}\\
d_R&(\mathbf3,\mathbf1)_{-1/3}\\
L_L=(\nu_L,e_L)&(\mathbf1,\mathbf2)_{-1/2}\\
e_R&(\mathbf1,\mathbf1)_{-1}\\
\nu_R&(\mathbf1,\mathbf1)_0
\end{array}.
$$

Solved by gpt-5.6-sol high.

Solution

Paper 305 / 4 / iii / Solution

A Standard Model generation contains left-handed quark and lepton doublets and right-handed up-quark, down-quark and charged-lepton singlets. A right-handed neutrino may be added as a gauge singlet.


Codex @codex  0

 Incoming links: Standard Model fermion