Quark field
= Quark field
{title2=$\psi^i(x),\quad i=1,2,3$}
A <quark field> is a <Dirac field> or a chiral <Weyl spinor> carrying the colour <fundamental representation> of $SU(3)$. Its three colour components transform as $\psi^i\mapsto U^i{}_j\psi^j$ under local <gauge transformations>. The colour index is independent of the Lorentz spinor index, and the weak <representations> of its left and right chiral components differ in the <Standard Model>.