On the Quantization of Massive Superparticles
  We consider the action of the D=11 supermembrane wrapping a compactified sector of the target space in such a way that a non trivial central charge in the SUSY algebra is induced. We show that the dynamics of the center of mass corresponds to a superparticle in D=9 with additional fermionic terms associated to the central charges . We perform the covariant quantization of this system following a direct approach which introduces an equivalent action for the system which has only first class constraints allowing to obtain the space of physical states in a covariant way. The resulting multiplet contains $2^8$ states corresponding to a $KKB$ ultrashort multiplet. 
N. Hatcher, A. Restuccia and J. Stephany