ON THE SPONTANEOUS BREAKDOWN OF MASSIVE GRAVITIES IN 2-DIMENSIONS(1)

We show that locally Lorentz-invariant, third-order, topological massi ve gravity cannot be broken down either to the local diffeomorphism su bgroup or to the rigid Poincare group. On the other hand, the recently formulated, locally diffeomorphism-invariant, second-order massive tr adic (translational) Chern-Simons gravity breaks down on rigid Minkows ki space to a double massive spin-two system. This flat double massive action is the uniform spin-two generalization of the Maxwell-Chern-Si mons-Proca system which one is left with after U(1) Abelian gauge inva riance breaks down in the presence of a sextic Higgs potential.