Color States of a Gluon Pair

We first introduce the “star vertex” and derive new simple rules involving this vertex. Using the tensor method, we then derive the \(\textrm{SU}(N)\) irreps of a gluon pair and their associated projectors, starting with a detailed discussion of the basis of tensors used to construct them. Having seven irreps (for \(N> 3\) ) or six irreps (for \(N= 3\) ), the gg system is richer than the systems considered in previous chapters, making the case of a gluon pair ideal for sharpening your birdtrack drawing skills.