Ghost cohomologies and hidden space-time symmetries

We observe and study new nonlinear global space-time symmetries of the full ghost + matter action of RNS superstring theory. We show that these surprising new symmetries are generated by the special worldsheet currents (physical vertex operators) of RNS superstring theory, violating the equivalence of superconformal ghost pictures. We review the questions of BRST-invariance and nontriviality of picture-dependent vertex operators and show their relation to hidden space time symmetries and hidden space-time dimensions. In particular, we relate the space time transformations, induced by picture-dependent currents, to the symmetries observed in the 2T physics approach.