Ghost Cohomologies and Hidden Space-Time Symmetries

We observe and study new non-linear 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 (vertex operators) of RNS superstring theory, violating the equivalence of superconformal ghost pictures. We review the questions of BRST invariance and non-triviality 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 the picture-dependent currents, to the symmetries observed in the 2T physics approach.