  In the present work the massless vector field in the de Sitter (dS) space has
been quantized. "Massless" is used here by reference to conformal invariance
and propagation on the dS light-cone whereas "massive" refers to those dS
fields which contract at zero curvature unambiguously to massive fields in
Minkowski space. Due to the gauge invariance of the massless vector field, its
covariant quantization requires an indecomposable representation of the de
Sitter group and an indefinite metric quantization. We will work with a
specific gauge fixing which leads to the simplest one among all possible
related Gupta-Bleuler structures. The field operator will be defined with the
help of coordinate independent de Sitter waves (the modes) which are simple to
manipulate and most adapted to group theoretical matters. The physical states
characterized by the divergencelessness condition will for instance be easy to
identify. The whole construction is based on analyticity requirements in the
complexified pseudo-Riemanian manifold for the modes and the two-point
function.
