  Curci and Ferrari found a unique BRS-invariant action for non-Abelian gauge
theories which includes a mass term for the gauge bosons. I analyze this
action. While the BRS operator is not nilpotent, the Zinn-Justin equation
generalizes in a simple way so that the renormalization of the theory is
consistent with the infrared regularization provided by the mass---infrared
singularities and ultraviolet infinities are therefore clearly separated.
Relations between renormalization constants are derived in dimensional
regularization with minimal subtraction. Additional new symmetries allow a
simple characterization of physical operators. A new formula is given for the
gauge parameter dependence of physical operators.
