We can write::formula_7 and formula_8The gluon contains an octet of fields, belongs to the adjoint representation (8), and can be written using the Gell-Mann matrices as::formula_9
We can write::formula_4 and formula_5The gluon contains an octet of fields (see gluon field), and belongs to the adjoint representation (8), and can be written using the Gell-Mann matrices as::formula_6(there is an implied summation over "a" = 1, 2, ... 8).