Operator quantization of the massive superparticle

The BFV-BRST operator method is used to quantize covariantly the massive Casalbuoni-Brink-Schwarz superparticle. In the naive use of the method, one has to put a restriction on the Hilbert space. Nevertheless, one can formulate an equivalent system, which is manifestly covariant and supersymmetric, without any restriction. Moreover it is shown that the physical subspace of the Hilbert space is positive definite. (author). 14 refs