Membrane's Discrete Spectrum and BRST Residual Symmetry in the Conformal Light Cone Gauge

In this work we present a proof of the discreteness of the spectrum for bosonic membrane, in a flat minkowski space. This may be useful to show the quantum mechanical consistence of others bosonics extended models. This proof includes the BRST residual symmetry and was directly performed over the discretized membrane model. The BRST residual invariant effective action is explicity constructed.