  We derive the nilpotent (anti-)BRST symmetry transformations for the Dirac
(matter) fields of an interacting four (3+1)-dimensional 1-form non-Abelian
gauge theory by applying the theoretical arsenal of augmented superfield
formalism where (i) the horizontality condition, and (ii) the equality of a
gauge invariant quantity, on the six (4, 2)-dimensional supermanifold, are
exploited together. The above supermanifold is parameterized by four bosonic
spacetime coordinates x^\mu (with \mu = 0,1,2,3) and a couple of Grassmannian
variables \theta and \bar{\theta}. The on-shell nilpotent BRST symmetry
transformations for all the fields of the theory are derived by considering the
chiral superfields on the five (4, 1)-dimensional super sub-manifold and the
off-shell nilpotent symmetry transformations emerge from the consideration of
the general superfields on the full six (4, 2)-dimensional supermanifold.
Geometrical interpretations for all the above nilpotent symmetry
transformations are also discussed in the framework of augmented superfield
formalism.
