Solution of the massive spin-1 equation in expanding universe

The spinor formulation of the massive spin 1 equation is considered in the general Robertson-Walker space-time. The corresponding differential equations are separated by an elementary separation method that has the advantage of being a simple extension of the one previously used in the massless case. The independent separated angular and radial equations are shown to reduce to those of the massless case and are explicitly integrated. Two separated time functions satisfying two coupled differential equations are necessary to describe the time dependence. Explicit solutions of the time equations are given in the massless case and for some meaningfull laws of universe expansion in the massive case.