ScalarGluonVertex[{p}, {q}, {mu, a}] or ScalarGluonVertex[p, q, mu, a] yields the scalar-scalar-gluon vertex, where p and q are incoming momenta.
ScalarGluonVertex[{mu, a}, {nu, b}] yields the scalar-scalar-gluon-gluon vertex, where p and q are incoming momenta.
The dimension and the name of the coupling constant are determined by the options Dimension and CouplingConstant.
ScalarGluonVertex[{p}, {q}, {\[Mu], a}]i T^a g_s (p-q)^{\mu }