Contents

Contents

Idea

The charge carried by quarks and gluons in the description of the strong nuclear force via quantum chromodynamics is called color charge.

If the gauge group is SU(N) and fermions are in the fundamental representation $\mathbf{N}$ of dimension $N$, so that $\mathbf{N}$ has a linear basis of $N$ elements, one says that these are $N$ colors of the given fermion particle.

Hence, more generally one could reasonably say that the “number of colors” of a given fundamental particle in gauge theory is physics synonym for the choice of linear representation of the gauge group that defines this particle.