  Collinear fields in soft collinear effective theory (SCET) can be made
invariant under collinear gauge transformations by multiplying them with
collinear Wilson lines. We discuss how we can quantize SCET directly in terms
of these gauge invariant fields, allowing to directly calculate S matrix
elements using the gauge invariant collinear fields. We also show how for each
collinear direction SCET can be written in terms of fields whose interactions
are given by the usual QCD Lagrangian, and how external operators coupling
these different directions can be constructed.
