Quark doublet
= Quark doublet
{title2=$Q_L=(u_L,d_L)^T\sim(\mathbf3,\mathbf2)_{1/6}$}
In one <Standard Model> generation, the left-handed up and down <quark fields> form a weak $SU(2)$ doublet of <hypercharge> $1/6$. Each weak component has three colours. The same field therefore counts as three doublets for weak gauge-loop contributions and two colour fundamentals for strong gauge-loop contributions. Right-handed up and down quarks are separate weak singlets.