  We derive the local, covariant, continuous, anticommuting and off-shell
nilpotent (anti-)BRST symmetry transformations for the interacting U(1) gauge
theory of quantum electrodynamics (QED) in the framework of augmented
superfield approach to BRST formalism. In addition to the horizontality
condition, we invoke another gauge invariant condition on the six (4,
2)-dimensional supermanifold to obtain the exact and unique nilpotent symmetry
transformations for all the basic fields, present in the (anti-)BRST invariant
Lagrangian density of the physical four (3 + 1)-dimensional QED. The above
supermanifold is parametrized by four even spacetime variables x^\mu (with \mu
= 0, 1, 2, 3) and a couple of odd variables (\theta and \bar\theta) of the
Grassmann algebra. The new gauge invariant condition on the supermanifold owes
its origin to the (super) covariant derivatives and leads to the derivation of
unique nilpotent symmetry transformations for the matter fields. The
geometrical interpretations for all the above off-shell nilpotent
transformations are discussed, too.

High Energy Physics - Theory