  We provide a systematic BRST formalism for the soft-collinear effective
theory describing interactions of soft and collinear degrees of freedom in the
presence of a hard interaction. In particular, we develop full BRST symmetry
transformation for SCET theory. We further extend the BRST formulation by
making the transformation field dependent. This establishes a mapping between
several SCET actions consistently when defined in different gauge conditions.
In fact, a definite structure of gauge-fixed actions corresponding to any
particular gauge condition can be generated for SCET theory using our
formulation.
