Wigner 6j symbols with gluon lines: completing the set of 6j symbols required for color decomposition

Abstract

We construct a set of Wigner 6𝑗 symbols with gluon lines (adjoint representations) in closed form, expressed in terms of similar 6𝑗 symbols with quark lines (fundamental representations). Together with these Wigner 6𝑗 symbols with quark lines, this gives a set of 6𝑗 symbols sufficient for treating QCD color structure for any number of external particles, in or beyond perturbation theory. This facilitates a complete treatment of QCD color structure in terms of orthogonal multiplet bases, without the need of ever explicitly constructing the corresponding bases. We thereby open up for a completely representation theory based treatment of SU(N) color structure, with the potential of significantly speeding up the color structure treatment.