SCALAR QED REVISITED

Scalar QED is investigated in the framework of causal perturbation the ory. This approach which is ultraviolet finite differs from the conven tional formalism because the inductive construction starts from the si mple first-order interaction, without the term quadratic in the electr omagnetic potential. The latter appears in the process of distribution splitting as a consequence of gauge invariance. In this way normaliza bility, gauge invariance and unitarity can be rigorously proven.