Zero-Norm States and Superstringy Symmetries
  We identify spacetime symmetry charges of the bosonic sector of 10D superstring theory from an infinite number of zero-norm states (ZNS) in the old covariant first quantized string spectrum. We give evidences to support this identification. These include supersymmetric sigma-model calculation, 2D super-Liouville theory calculation and, most importantly, three methods of high-energy scattering amplitude calculations. These calculations generalize the previous bosonic string calculations, which explicitly prove Gross's conjectures in 1988 on high energy symmetry of string theory. Moreover, we discover new high energy scattering amplitudes which are, presumably, related to the high energy massive spacetime fermionic scattering amplitudes in the R-sector of the theory. 
Jen-Chi Lee